Science Physics - Berkeley CSUA MOTD
Berkeley CSUA MOTD:Science:Physics:
Berkeley CSUA MOTD
2017/09/20 [General] UID:1000 Activity:popular

2013/7/8-8/23 [Science/Physics] UID:54705 Activity:nil
7/8     Why do immigrants kick ass in science?
        \_ Cuz they have no friends
        \_ Cuz excelling in science requires less background of the local
           culture than excelling in other areas.
2013/5/7-18 [Science/Physics] UID:54674 Activity:nil
        This is totally awesome.
        "equips each node in the network with quantum transmitters–i.e.,
        lasers–but not with photon detectors which are expensive and bulky"
        \_ The next phase of the project should be stress-testing with real-
           world confidential data by NAMBLA.
2013/4/29-5/18 [Science/Physics] UID:54664 Activity:nil
4/29    "Speed of Light May Not Be Constant, Phycisists Say" (
        "Two papers ...... attempt to derive the speed of light from the
        quantum properties of space itself."  (i.e. instead of measuring it)
2013/3/14-5/5 [Science/Physics] UID:54626 Activity:nil
3/14    "Confirmed! Newfound Particle Is the Higgs"
        \_ so, what's next?
           \_ "Q: Why does Higgs Boson have mass?"
2012/10/2-11/7 [Science/Physics, Science/GlobalWarming] UID:54490 Activity:nil
10/2    Ars takes a tour of SLAC: [ars]
2012/7/2-27 [Science/Physics] UID:54426 Activity:nil
        URL says it all.
        \_ A comic video helps explain it:
2017/09/20 [General] UID:1000 Activity:popular

2011/7/26-8/2 [Science/Physics] UID:54145 Activity:nil
7/26    "Hong Kong scientists 'show time travel is impossible'" (
        \_ Rest of World Emits Collective 'duh'
        \_ I'm no physics wizard.  They may have proven that a single photon
           does not travel faster than c.  But how does this imply that
           no physical object can travel faster than c?  And how does that
           imply that no information can travel faster than c?
        \_ tell that to the guys who had the "Time Machine Invented" article.
           LESSON: you can't believe the internets for things outside the
           scope of knowledge of the avg compunerd. Yes, high end physics,
           much like economics, classics, lit theory, politics, and how to
           talk to women, are all out of scope.
2011/3/6-4/20 [Science/Physics, Science/Space] UID:54055 Activity:nil
3/5     "NASA scientist finds evidence of alien life" (
        \_ This was published in the Journal of Cosmology.  Here's a
           description of the very first paper they published, in 2009:
2011/2/11-19 [Computer/SW/Security, Science/Physics, Science/Electric] UID:54035 Activity:nil
        Tardis at UCB
        \_ yeah there are 'tards at ucb alright
2010/9/8-30 [Science/Physics] UID:53950 Activity:nil
9/5     String Theory and God.
        \_ "My specialty was in biophysics, not in theoretical physics,"  That
           sums up the rest of his articles - a big copy-and-paste job of
           fragments that he doesn't really understand.
2010/4/7-15 [Science/GlobalWarming, Science/Physics] UID:53773 Activity:nil
4/7     "CERN creates 10 million mini-Big Bangs in one week"
        See?  I told you that this experiment won't create any black holes that
        get out of control and swallow the entire eart&$*(!~#@%& NO CARRIER
2009/12/2-9 [Science/Physics] UID:53557 Activity:nil
12/2    Looking for a "LHC and Higgs bosom for Dummies" equivalent site.
        I'd like to learn more but most sites out there are just way
        beyond me. Is there a dummy's version for it?
        \_ W = weak force, EM = electromagnetic force, S = strong force,
           G = gravity. They're the four forces, and the holy grail of
           physics is to unify them all in a single theory -- the Grand
           Unification Theory. W, EM, and S have been combined
           successfully, but G works so differently that all attempts
           to unify it with the others have failed so far. The basic
           problem is that general relativity and quantum mechanics
           have highly incompatible frameworks, so it's hard to bridge
           that gap. String theorists swear they're onto something,
           but the jury's still out on that.
           \_ Aside from whether or not there is an existing unification
              theory for 3 or 4 of the forces, what does it mean by "unifying
              the forces into a single theory" in the first place?  Does it
              mean simply coming up with an equation that involves 3 or 4
              variables that represent the forces?  Does something silly like
              "W + EM + S + G = ma" (ie. total force = mass * accel) count?
              -- dummy #2
              \_ No, it's more like looking for, "this is why the universe
                 works the way it does."  Right now we have ways to describe
                 why particles behave the way they do, and why gravity
                 behaves the way it does, but not both at the same time.
        \_ Is "Quantum Physics For Dummies" (ISBN-10: 0470381884) any good?
           \- Some of this is pretty hard to understand and watered-down
              explanations almost mean nothing. But you can at least get a
              sense of what some of the fundamental questions are:
              --what are unification and symmetry about?
              --where does mass come from
              --how many fundamental physical constants are there
              --what is the "hierarchy problem" etc.
              --what is consistant/inconsistant with the std model
              i think "Dreams of a Final Theory" is pretty good, but not
              that current. You can also look at Lisa Randall's "Warped
              Passages" book (if you were in berkeley cs a while ago, her
              Passages" book (if you were in berkeley CS a while ago, her
              sister Dana was a grad student here). if you have ome specific
              question, i can try to address that. Qs like "what do they
              mean by 'the higgs gives rise to mass'" or "what does 'quark
              confinement' mean?" have sort of a hand wavey explantions,
              while "what is gauge renormalization?" doesnt.
2009/11/11-30 [Science/Physics, Science/GlobalWarming] UID:53518 Activity:low
11/11   Watch the History Channel today! It's got Oppenheimer and the atomic
        bomb history. Did you know at one time 10% of the entire electricity
        in the U.S. was used to refine U235 and weapon grade plutonium?
        Holy jesus! I wonder how much energy is used to get plutonium fuel
        that generates today's nuclear powered electric plant
        \_ it talks about the 2 different methods for getting U235. So
           I was curious and looked it up:
           Basically, refine uranium into U235 (0.7%) and U238. But
           then it also talks about using U235 to bombarad U238 into
           U239, plutonium. How does that work?
           \_ Physics is hard.
              \_ why the hell did you even bother to answer if
                 your answer doesn't help
                 \_ you're new around here, aren't you?
                 \_ Here then:
2009/5/4-6 [Science/GlobalWarming, Science/Physics] UID:52946 Activity:nil
5/4     Next-generation stealth technology :-)
2009/4/20-23 [Science/GlobalWarming, Science/Physics] UID:52881 Activity:nil
4/20    Cold Fusion on 60 Minutes:
2009/4/20-28 [Science/GlobalWarming, Science/Physics] UID:52875 Activity:kinda low
4/20    "Stephen Hawking hospitalized, reported very ill"
        Hope he doesn't die until he solves the mystery of the universe(s) for
        all of us.
           \_ Update:
        \_ This has all been taken out of context...he went in to get some
           26s put on his wheel chair and a couple of other mods and the the
           Technician said "It's gonna be ILL!"
        \_ Stephen Hawking is overrated
           \_ Really?  Then who is the forefront guy in the field now?  Thx.
              \_ Hawking isn't really the foremost scientist, but he's one
                 of the best at making the concepts accessible.
                 Filipenko is similar in that way.  -tom
                 \- i think that characterization short changes hawking.
                    picking a "market leader" may depends on your thoughts
                    about string theory.
        \_ Uh, he's been very ill for decades.
                    \_ It's nice we're so willing to spend $$ to support
                       string philosophy, but how about doing some science?
                       \- you can say string theory has affected the job
                          mkt but i dont think this is a reasonable crit ...
                          e.g. LHC is $$$. the waste of $$$ from a science
                          perspective is humans in space. and a lot of public
                          money is spent on medican research, if you consider
                          science beyond fundamental physics.
                          \_ I slam string philosophy because it is producing
                             no testable predictions.  Engineering
                             demonstrations such as trips to space have
                             their uses, and so does medical research, but
                             have any testable hypotheses come out of many
                             years of string philosophy?  Though perhaps
                             I should use the less perjorative term
                             string mathematics, because that is all that
                             can be said to have come of it.  Math is worth
                             pursuing for its own sake, but I think that
                             the physicists need to concentrated on producing
                             some testable hypotheses or look at alternatives.
                             \_ The LHC will test parts of string theory.
                                \_ My PhD physicist friend claims that these
                                   tests don't really distinguish string
                                   theory from other available theories.
                                   \_ wow, you have a PhD physicist friend,
                                      you must know what you're talking
                                      \_ You noticed I said "claims"?
                                         Are you too dim to pick up
                                         that this means I don't
                                         necessarily trust he is right?
                                         However, I do grant him some
                                         credibility.  What credibility
                                         do you have, asshole?
                                         \_ I have *two* PhD physicist
                 \_ I'd put Filipenko in the same category as Neil DeGrasse:
                    amazingly good at evangelizing science.
                    \- that short changes Filipenko.
        \_ Being a string theorist is a great scam.  Its impossible to
           prove or disprove any of your data in your thought experiments
           while sitting at the cafe in downtown Palo Alto.
           \- while all the B School people are earning their bread for sure.
2008/6/22-23 [ERROR, uid:50328, category id '18005#0' has no name! , , Science/Physics] UID:50328 Activity:high Cat_by:auto
6/22    Glass' solid/liquid nature explained: [new scientist]
        \- "John Kerry, is glass a solid or a liquid?"
        \_ This article is a joke, right?
           "Although glass feels like a solid, its molecules cannot quite
           settle into a regular 3D lattice and, given enough time, it flows
           like a liquid."
           Um, no it doesn't flow like a liquid.
           \_ It doesn't?
           \- yes it does. have you ever seen multi-hundred year old windows?
              without obsessing over the "like a liquid part", glass does flow.
           \_ Have you ever seen really old windows?  -- ilyas
              \_ No, it doesn't.  Otherwise all glass bottles over a certain
                 age would be glass puddles.  Yet we have them from the middle
                 ages.  It's a common misconception, most likely due to early
                 glass pane making techniques that made glass panes thicker on
                 one end than another.  Now, when people point out the thicker
                 bottom on glass panes they say that's proof that it's a
                 liquid.  They conveniently overlook panes with thicker tops
                 and sides.  The real slowest solid-like liquid is pitch IIRC.
                 \_ Why not put the whole setup in a centrifuge to accelerate
                    the process?
2008/6/15-20 [Science/Physics] UID:50263 Activity:nil
6/15    Plastic Semiconductors: [new scientist]
2008/4/16-23 [Science/Physics] UID:49758 Activity:nil
4/16    This article sort of argues that we should have set of odds to gauge
        how likely it is the CERN will destroy the earth.  I'm not quite sure
        how one would take odds on somehting we basically think is impossible.  (NYTimes)
/16     Pope fashion show!  I had no idea he had so many outfits.,29307,1730229,00.html
        \_ Hello,  I am offering Earth destroyal insurance at the modest
           cost of only $100.  Should the Earth be destroyed by CERN,
           I will pay each policy holder $10M.  Policy only good for
           lifetime of holder.
2008/3/19-21 [Science/Physics] UID:49497 Activity:moderate
3/19    This is one of the funniest xkcd's I've seen
        \_ This xkcd is not funny.  This is one of the funniest xkcd's you have
           ever seen.  Therefore, you do not like laughing.        ^
           \_ You're an idiot                                      |
              \_ O WAU YR RITE                                     |
                 \_ Yes, this is the level of the argument of the gp.
        \_ MythBusters is totally bad science.  The kind of bad science that
           leads to "proving" theories that are completely invalid.  XKCD
           is wrong wrong WRONG about this one.
           \_ You are precisely the kind of person Zombie Feynman would
              \_ My problem is not rigor.  My problem is tests that don't
                 disprove the hypothosis.  Hypothosis is "can x be done".
                 The test is "can I do x via method y".  That may doesn't
                 disprove "can x be done".  (Basically I'm sick of know-it-alls
                 telling me mythbusters proved something doesn't work
                 when mythbusters did no such thing.  People aren't learning
                 to create tests and verify, people are learning "trust
                 the geeks on my tv".)
                 \_ How would you disprove "x can be done"?
                    \_ You can't.  But you go do a lot better than "Can we go
                       faster than the speed of light?  Well we built a really
                       cool rocket car and it only got to 300mph, so we are
                       going to say NO!"
                       \_ Wow, with strawmen like that I can see how you're a
                          much better thinker than the MythBusters.
                    \_ Well, it is probably impossible to show that in an
                       absolute sense most X cannot be done or some phenomenon
                       X is impossible.  The best that one can hope for is that
                       if X was possible it would violate the known laws of
                       Re Mythbusters - I think they pick things that can be
                       disproven/proven for pratical purposes via a reasonable
                       experiement. I think of it as a first approximation,
                       rather than the final proof. Sometimes an approximation
                       may "promote the Progress of Science and useful Arts"
                       as much as a final proof will.
                       \_ I'm sorry, they are bad science.  0 controls.
                          Multiple independant variables.  This kind of
                          stuff matters and isn't hard to get right.
                          Why don't they?
                          \_ They routinely have controls.  So you don't watch
                             the show, eh?
                          \_ When did they ever call themselves scientists?
                             They're special effects engineers putting together
                             an entertaining program.  Seriously people...
                             And the XKCD isn't putting them forth as
                             scientists either.  Whatever you're arguing is
                             missing the point.
                          \_ Okay, so they are engineers rather than scientists
                             :-). In any case, the presenters are doing
                             "science" in that they are are verifying claims
                             via experiment, albeit very crude and imprecise
                             experiments. Sure you can probably do a better,
                             more precise experiment, with controls, &c. But
                             it would probably be far less entertaining.
                             If you want rigor, watch Nova.
                             \_ Didn't Nova do a huge string theory special?
                                  -- ilyas
                                \_ Well, they had a big 2 hour special
                                   with Brian Greene based on "The Elegant
                                   Universe." I think they have had a few
                                   shorter shows on loop quantum gravity,
                                   string/m-theory, &c. with Neil deGrasse
                                   Tyson. Most of the Nova episodes re string
                                   or m-theory have included some discussion
                                   that the theory may not be physics b/c it
                                   is untestable.
                                   \_ I don't remember Nova string theory stuff
                                      being anything other than a huge
                                      cheerleading PR thing for string theory.
                                        -- ilyas
                                      \_ Hmm. I recall the string theory pgms
                                         as being mostly cheerleading, but not
                                         totally one-sided. Also there was a
                                         program on LQG, which, I think, is a
                                         different, testable, theory that
                                         unites GR and QM w/o all the kookiness
                                         of string/m-theory.
                                   \_ Who is more anoying, Brian Greene or
                                      Neil deGrasse Tyson?
                                      \_ Not sure, but Samantha Carter recently
                                         said that she thinks Neil deGrasse
                                         Tyson is hotter.
                 \_ You're blaming Mythbusters for stupid people.  They're
                    pretty good at narrowing their focus and explicitly saying
                    what that focus is.  Instead of mental wanking (like people
                    asking about a plane taking off from a treadmill), they
                    actually try it.  That *is* valuable, and that's precisely
                    what Zombie Feynman's point was.  It's also a really good
                    shot at string theorists.
                 \_ Mythbusters isn't trying to prove that it impossible for
                    X to be done by any method. I think it is fairly obvious
                    from the show that the presenters pick the methods most
                    likely to accomplish X and then show whether X can be
                    accomplished via those methods. If it turns out that X
                    cannot be accomplished via the methods selected, then
                    the presenters conclude that it is unlikely that X can
                    accomplished. Although it is not a rigorous proof that
                    X cannot be accomplished at all, the demonstration can
                    be considered a sufficient approximation for most purposes.
                    The show can also be considered to as "educational" in the
                    sense that it teaches people to disbelieve claims that
                    cannot be demonstrated via experiment.
                    \_ Ack this is just bull. Something either is, or isn't.
                       You're either with us, or against us, it's as simple
                       as that!
                       \_ Does this pass for humor in your circles?
2007/10/21-25 [Science/Physics] UID:48401 Activity:moderate
10/21   I am one of the biggest sceptics of Roomba iRobot. 2 of my friends
        had the first and second generation Roomba respectively, and their
        feelings for it were lukewarm. Their units were loud, a hastle to
        use (need to find the unit and charge manually), and most
        importantly, DUMB. Well, after doing an extensive research, I
        decided to buy the latest Rooma anyways. I got a Roomba 560,
        the FIFTH generation and boy, it is the most amazing thing I've
        even seen and cleans amazingly well! Here are the highlights:
        1) auto docks when it is done or gonna die. The homing beacon
        mechanism is amazing!!! 2) 7 day timer so you don't even have to
        press start 3) cleans very well, goes under my bed too! 4) it's got
        external corner brushes to clean the sides REALLY well, in fact
        better than my regular vacuum cleaner 5) it comes with 2 virtual
        wall/room units, so you can block or request to clean up to 3
        different rooms (and it'll remember which room it is in)  6) it is
        a lot quieter than the first generations and lastly 7) it is
        a LOT smarter than the first and second generation Roomba and
        statistically goes through different surfaces quite evenly. It
        knows to clean the sides (did I mention it's got side brushes?).
        Roomba 5th generation is a quantum leap from the first few
        generations, and it's worth every penny. Good job iRobot, looking
        forward to buying your stock.
        \_ can it do stairs?
           \_ No because it doesn't have a penis.
           \_ Assuming it can't do stairs, can it not fall down stairs
              if it is upstairs?  Is it smart enough not to go over a
              \_ It cannot do stairs, there are no vacuum robots today
                 that can do stairs. It does have fall/cliff protection
                 so you don't have to worry about a thing. If you're
                 curious just check out some Roomba 560 vids on YouTube.
                 \_ I'm not sure how 'newer' models do  with stairs, but ours
                    has managed to go fall down our stairs once or twice
                    when let loose in the upstairs.  My current peeve is the
                    irobot can be activated unexpectedly by a cat walking
                    on its power button. -ERic
                    \_ Uh, ya, blame it on the machine and not the cat.
                       Brilliant. How about putting a cardboard on top
                       of the button? Actually, I'm curious Eric. Do you
                       have no pet peeve with cats? What do you like
                       about cats?
                    \_ I'm sorry to hear that. I don't seem to have that
                       problem with my dog.
                       \_ Cats are programmed statistically to walk on every
                          horizontal surface in a house 1-4 times a day.
                          \_ LOL. My Roomba is just as entertaining and
                             smart as my cat, but my cat is still cuter.
        \_ I don't get it.  Is running a vaccuum over a floor every so often
           so hard you need a toy to do it for you?
           \_ It is tedious when you have pets and/or children. In my case
              any hour I can gain a week is a HUGE gain  -tired guy w/chores
              \_ Is this the life you planned for yourself?  Is it worth it?
                 \_ Most of the people in this world don't plan every little
                    detail of their lives. Most kids, even in developed
                    countries, are still "accidents."
                    \_ Sex without condom/pill/whatever that leads to
                       children is not an accident.  The failure rate for
                       various methods is under 10% on average.  If he has
                       kids, odds are greatly in favor of him planning on it.
                       \_ abortion or lack thereof is also a choice
                          \_ True.  So all these parents in one way or another
                             have chosen it.  Which goes back to my original
                             questions to the tired guy w/chores,
                             "Is this the life you planned for yourself?
                              Is it worth it?"
                             \_ I am not tired guy with chores, but I too have
                                a daughter that keeps me busy and I can say
                                without reservation that it is the greatest
                                thing I have ever done. Even if I do have to
                                hire a maid to clean the bathroom, since I
                                am too busy (usually playing with my daughter)
                                to do it myself.
                                to do it myself. And yes, this is the life I
                                planned for myself.
2007/10/8 [Science/Physics, Science/GlobalWarming] UID:48270 Activity:nil 52%like:48271
10/8    Question for the motd physics geeks.  I was talking to some friends
        about flywheels.  It's well known that one problem with flywheels is
        their resistance to rotation (it's the well known effect that keeps
        bicycles upright).  One proposed way of handling this is to install
        flywheels in pairs so they counteract each other.  The question is,
        how much energy should you expect to bleed off in this way?  -- ilyas
2007/10/1-5 [Science/GlobalWarming, Science/Physics] UID:48215 Activity:high
10/1    "Time travel machine"
        Is this real?
           There was a piece on him on This American Life that was utterly
           heartbreaking. An amazing person.
           \_ I can't see the top link, but the wiki article makes it clear
              that to this point he doesn't even having a working theory as
              to how time travel might work.
              \_ It's a hard problem when you're sane.
              \_ I think that drawing this conclusion from a wikipedia article
                 really does justify the fears that people have about the
                 level of misunderstanding something like wikipedia can
                 engender. He appears to be both sane and knowledgeable enough
                 to be worth listening to.
                 \_ Wikipedia is shit.  Citing wikipedia on a subject
                    generally signals 'I know nothing about the subject
                    \_ Uhm, what?  This is *time travel*!  There is no one on
                       the planet who truly understands *time travel*.  Going
                       to wikipedia is better than reading this guy's papers
                       that no one is going to understand.  Hey, did I mention
                       this was about *time travel*?  *TIME TRAVEL*!  Sheesh.
                       \_ No it's not.  One of the reasons wikipedia is so
                          dangerous is it makes people think it's a better
                          source than the source, so to speak.  Your first
                          impulse if you don't understand something is to try
                          to understand it, or ask someone who does understand,
                          not consult wikipedia.  In this case, if you want
                          to know if the guy is a kook, talk to a physicist.
                          Wikipedia is the source of McDonaldization of
                          Wikipedia is a source of McDonaldization of
                                                   \_ This is an excellent
                                                      phrase. I hope you don't
                                                      mind if I adopt it.
                                                      \_ This is due to George
                                                         Ritzer.  At any rate,
                                                         ideas belong to all
                                                         mankind. -- ilyas
                          knowledge.  -- ilyas
                          \_ Lacking any physicists nearby who understand the
                             math and high energy physics involved in this
                             guy's work, I'll take the dime store version at
                             wp.  Lacking the time and honesty, having a great
                             deal of apathy towards the entire time travel
                             silliness, I'll skip trying to decipher his
                             actual papers and be satisfied knowing that he's
                             having fun at some Uni tucked harmlessly out of
                             the way mumbling, "They mocked me at the Academy!
                             But I'll show them!  I'll show them alllll!!!!!
                             Muahahahhahahaaa!!!!!"  *TIME TRAVEL*!
                             \_ You are better off simply admitting ignorance
                                than assuming a contrarian is wrong simply
                                because he's a contrarian.  Biased certainty
                                is not better than unbiased uncertainty.
                                If you are interested in rationally evaluating
                                things, that is.  It's great fun to poke fun
                                at contrarians.  -- ilyas
                                \_ tell us about the stars, ilyas
                                \_ Uhm, duh, it is *TIME TRAVEL*.  How can I
                                   not be ignorant of it?  That is what I've
                                   been saying since this topic went up. Please
                                   do tell exactly who on this planet is not
                                   ignorant of how *TIME TRAVEL* works.  It is
                                   great fun to poke fun at people who try to
                                   seriously discus *TIME TRAVEL* as if it was
                                   something we could rationally discuss as a
                                   scientific concept and not a philosophical
                                   one.  And yes when I finish my *TIME TRAVEL*
                                   machine I am so going back to whack your
                                   grand dad just to put an end to this silly
                                   nonsense.  Nothing personal, I think you're
                                   an ok guy.
                                   \_ Time travel is a scientific concept.
                                      You are operating using a very strange
                                      distinction between science and
                                      philosophy.  -- ilyas
                    \_ Wikipedia is great for some things.  One prof's
                       vaugly out there research is not one of those
                       \_ The problem with wikipedia for 'some things' is
                          you never really know if the information is
                          accurate.  So the only thing wikipedia is good for
                          is procrastinating.
                          \_ 1. Many times I do know if the information
                                is accurate, or it's not something I'm
                                worried about being exactly right.
                             2. If I do care about if information is right
                                using wikipedia as my only or primary source
                                is fucking stupid, yes, however it can be
                                a very useful starting point.  Go to wikipedia
                                get the basics and then research those to
                                make sure they seem reasonable.
                             3. The problem with this prof isn't the accuracy
                                or lack thereof.  The problem is it's a poorly
                                written article about something very few people
                                care about.  What it told me was this dude is
                                someone who cares a lot about time travel and
                                has done research in the field that isn't
                                obviously batshit insane.  If I want to know
                                more I can research other places and come to
                                my own conclusions.
        \_ On a vaguely related note there is some good discussion on the
           blogs about 'contrarian' vs 'conservative' strategies in science.
             -- ilyas
2007/9/18 [Science/GlobalWarming, Science/Physics] UID:48098 Activity:nil 75%like:48099
9/18    "Shrinking kilogram bewilders physicists"
        *The* kilogram is getting smaller in mass.
2007/6/1-5 [Science/GlobalWarming, Science/Physics] UID:46831 Activity:nil
6/1     Boeing scientists create 40% efficient solar cells:
        \_ What's the efficiency of solar cells in typical roof-top solar
           panels these days?
2007/4/11-12 [Science/GlobalWarming, Science/Physics] UID:46260 Activity:high
4/11    Motd poll:  What do you think the Easter Islander that chopped down
        the last Easter Island tree was saying as he did it?
        "Jobs, not trees!":
        "Technology will solve our problems, never fear, we'll find a
        substitute for wood.":
        "We don't have proof that there aren't palm trees somewhere else
        on Easter, we need more research, your proposed ban on logging
        is premature and driven by fear-mongering":
        "this is gonna make a nice fire to cook my dinner on"
        "I better take this tree now, before my neighbor does"
        \_ "This ought to make sierra-club libural hippies in SF cry."
           \_ You sure are smart.
        "Jobs, not trees!":
        "Technology will solve our problems, never fear, we'll find a
        substitute for wood.":
        "We don't have proof that there aren't palm trees somewhere else
        on Easter, we need more research, your proposed ban on logging
        is premature and driven by fear-mongering":
        "this is gonna make a nice fire to cook my dinner on"
        "I better take this tree now, before my neighbor does"
        \_ On a funny note, I saw a Fox news blurb yesterday about how
           trees may cause global warming.
        \_ "I'm sure this isn't _really_ the last tree."
        \_ "As history has demonstrated, we will always invent newer and
           newer technologies to locate more and more trees that we can't see
           now as tree-cutting rate goes up and up.  These will include, but
           not limited to, technologies to find transparent trees, trees that
           float at 20000ft altitude, quantum trees that have no fixed
           position, as well as anti-metter trees.  Our tree supply will be
        \_ Whatever they said, if they said anything, I'm sure it wasn't
           in English.  ;-)
        "You've seen one tree, you've seen 'em all."
2007/3/20-22 [Science/Physics, Computer/Theory] UID:46030 Activity:nil
3/20    E8 Lie group mapped:
        \_ "While many scientific projects involve processing large amounts of
           data, the E8 calculation is very different, as the size of the
           input is comparatively small, but the answer itself is enormous,
           and very dense."  How is E8 significant in this sense?  I can
           easily state a problem like "Find the first N prime numbers." and
           input N=1000000".  Then the input is small and the answer is
           enormous and it involves lots of computation.  Is that the same?
           \_ How about "what is the ratio of the circumference of a circle
              to it's diameter, to 10^8 places"?
2007/2/22-26 [Science/GlobalWarming, Science/Physics] UID:45790 Activity:nil
2/22    Element 118 created ... in Iran!
        \- e118 created ... "again"
           in other news, berkeley >> the 'fraud
2006/10/5-7 [Science/Physics] UID:44683 Activity:nil
10/5    Beam me up Hamlet: (
2006/9/19-22 [Science/Electric, Science/Physics] UID:44441 Activity:nil
9/19    Cornell researchers invent oled that also acts as a solar cell: (
        \_ Awesome, finally my solar powered flashlight will be a reality!
2006/5/11-17 [Science/Physics] UID:43023 Activity:nil
5/11    Physics question.  Why doesn't the Weak Nuclear Force fall off
        inversely proprotionally to the square of distance?
        \- Oh hello, this is a good question and "why is the weak force not
           like the em force or gravity" is one of the great results of
           THE STANDARD MODEL. I am going to assume you have taken a little
           bit of quantum mechantics but not quantum field theory, so this
           will be a little bit hand-wavey. Basically, the weak force is
           different from the em/gravity because unlike the photon [em]
           and the graviton, THE FORCE CARRIERS FOR THE WEAK FORCE ARE
           NOT MASSLESS PARTICLES [see W+ W- and Z particles]. The hand-
           wavey part is: higher masses are associated with higher energies
           which in turn are associated with smaller interaction distances.
           This comes from the uncertainty principle and some dictates of
           relativity [speed of light constant and finite] but that is beyond
           the motd. Why the weak force carriers have mass is at the cutting
           edge of HEP research in a area called the HIGGS MECHANISM. The
           LHC coming online at CERN in about a year should be producing
           some amazing and eagerly anticipated results "soon". To go up a
           notch from here, this length-energy relationship is why STRING
           THEORY involves lengths so many orders of mag smaller and energies
           so many orders of mag higher [the WEAK SCALE and the PLANK SCALE
           about 16-17 orders of mag apart]. another cool thing about the
           weak force is PARITY VIOLATION, which if you have taken a little
           intro QM is related to the spin statistics. BTW, the weak force
           also proves god does not exist. ok tnx. --psb
           \- hey this was a pretty good explanation. I took particle physics
              and was about to write something but then psb pwned it. good
              job! -linxu. ps: wikipedia has much on this. pretty accurate.
              \- which class is "particle physics"? there is an upper div
                 quantum class and a special relativity class, but is there a
                 particle physics class before 221? BTW, do you have any
                 preferences between the ZEE and WEINBERG QFT books?
                 "QFT is hard. let's go shopping."
              \- oh the wikipedia entry on the "weak force" is pretty good.
                 (meaning it is comprehenssable)
                 i thought it was kinda funny they "hand waved" over the
                 same part i did: "uncertainty+special relativity -> short
                 interaction distance", but i guess it makes the additional
                 point about particle life time. BTW, here is some interesting
                 trivia about the parity violation: YANG & LEE did the
                 theoretical work to predict this. apparently they took a
                 class at UCHICAGO from S CHANDRASEKAR (possibly with some-
                 body else too) and it turns out that everybody in that class
                 would go on to win the nobel prize in physics ... in fact
                 the teacher himself would be the last person to win the
                 nobel. also, perhaps even a greater scandal than the
                 WATSON/CRICK/WILKINS vs ROSALIND FRANKLIN female nobel snub
                 was not naming WU along with YANG and LEE for the parity
                 violation nobel (since you are allowed to name up to 3
                 co winners). WU also did her phd at UCB under EOLAWRENCE.
              \- which particle physics course? i didnt think there was a
                 particle physics class until after 221. what textbook do
                 you use ... WEINBERG or ZEE? ("QFT is hard")?
                 the wikipedia entry on the "weak force" is pretty good.
                 (meaning it is comprehensable). i thought it was kinda funny
                 they "hand waved" over the same part i did:
                 "uncertainty+special relativity -> short interaction
                 distance", but i guess it makes the additional point about
                 particle life time. BTW, here is some interesting trivia
                 about the parity violation: YANG & LEE did the theoretical
                 work to predict this. apparently they took a class at
                 UCHICAGO from S CHANDRASEKAR (possibly with somebody else
                 too) and it turns out that everybody in that class would go
                 on to win the nobel prize in physics ... in fact the teacher
                 himself would be the last person to win the nobel. also,
                 perhaps even a greater scandal than the WATSON/CRICK/WILKINS
                 vs ROSALIND FRANKLIN female nobel snub was not naming WU
                 along with YANG and LEE for the parity violation nobel (since
                 you are allowed to name up to 3 co-winners). WU also did her
                 phd at UCB under EOLAWRENCE.
                 \- Woo that's pretty interesting to know. I took 129A. It was
                    taught by Gaillard, an old professor who actually did
                    stuff back in the day. To be honest, most of the math
                    went over my head... I got a B+ in the class but I don't
                    deserve it. (Really i should have gotten a C). Some
                    really interesting stuff re: renormalization, Feynman
                    diagrams, etc. -linxu
                    \- oh i was kinda curious if it was MKG or ZUMINO ...
                       i didnt think the dept let them near undergrads.
                       BTW, another interesting bit of trivia maybe for
                       some of you: some of you may have had DANA RANDALL
                       as a TA for a CS THEORY class ... her sister LISA
                       did her postdoc at UCB/LBL is now a prominent
                       physicist and just came out with this book:
                       which should cover some of the topics above
                       at a level accessible to a reasonable sloda user.
                       BTW, for berkeley MKG isnt that "old" ... not with
                       people like Al Ghiorso still around ... who started
                       working for SEABORG in the 40s.
        \_ What's with the caps?
           \- high speed keyword matching. sort of like compiler hints.
2006/3/27-29 [Science/Physics, Reference/History/WW2] UID:42450 Activity:kinda low
3/27    This is a very stupid and specific question regards to design
        of main battle tank:
        why the main gun of most of main battle tank in the world are
        smoothbored instead of rifled?
        \_ Just a guess but the advent of laser guided missiles obviated the
           need for point-to-point riffled payloads. In another word there
           is no longer a clear need for line-of-sight with modern missiles.
        \_ I'm not an MBT designer, but I would guess that they're able to
           accomplish the desired accuracy/range with a smoothbore, and a
           rifled shell has less explosive power (because it needs a heavier
           casing to withstand the greater stress of the rotation). Mortars
           shells contain more explosive than equivalent-sized artillery shells
           for the same reason (which makes them particularly deadly for
           urban fighting). Oh, and the M1 (but not the A1 or A2 variants)
           and the new Stryker multi-tank-thing, plus the British Leopard and
           a few others, all have rifled cannon. -gm
        \_ Find-stabilized shells, among others.  Not all MBT barrels are
           smoothbore (examples are Rheinmetall 120mm and several of the
           newer Soviet ones.)  What above poster said too, but it's not so
           much the explosive power as for accuracy of heavier shells.  Also
           rifled barrels wear out faster.  -John
           \_ thanks.  This is cool.
        \- Hello, I too am not a MBT designer but having some knowledge of
           EULER && LAGRANGE && NEWTON, I suspect the Moments of Inertia
           which would characterize a tank shell would suggest it would not
           be amenable to rotional stabilization as a small, cigar shaped
           shell would be. For a discussion accessible to a science undergrad
           see e.g.
           particlarly the two conclusions at the bottom of the page. For a
           more involved discussion, see the famous:
           A simple demonstration of this can be done with a bed pillow
           which isnt too floppy. say it is 20" long, 14" wide and 6" deep.
           which isnt too floppy. say it is 2ft long, 1.5ft wide and 6in deep.
           if you throw it up in the air in front of you spinning about each of
           the possible axes, you will notice it is obviously less stable when
           you spin it about the 1.5ft axis or "middle" Moment of Inertia axis.
           you spin it about the 14" or "middle" Moment of Inertia axis.
           This is actually something pretty cool to prove, rather than just
           one of these artificial physics problems. And now we can talk about
           \_ My classical mechanics text called this The Tennis Racket Theorem.
              I tend to think a better example is with skateboards. Rotating
              around the principle axis with the smallest moment of inertia
              is a kickflip, rotating around the axis with the largest moment
              of inertia is a varial or a shove-it, but the unstable middle
              axis is called the "ollie impossible" for good reason.  Both
              the kickflip and the varial can be done by just kicking the
              board and landing, but the impossible generally involves guiding
              to board around with your foot to keep it stable.  At least that's
              how I do it.  I could kickflip and varial years before I learned
              the imposible, which I think you'll find is typical of most
              skaters.  Of course I could do all three years before I
              knew what a moment of inertia tensor was or could prove the
              tenis racket theorem.
           \_ My classical mechanics text called this The Tennis Racket
              Theorem. I tend to think a better example is with
              skateboards. Rotating around the principle axis with the
              smallest moment of inertia is a kickflip, rotating around the
              axis with the largest moment of inertia is a varial or a
              shove-it, but the unstable middle axis is called the "ollie
              impossible" for good reason.  Both the kickflip and the varial
              can be done by just kicking the board and landing, but the
              impossible generally involves guiding to board around with
              your foot to keep it stable.  At least that's how I do it.  I
              could kickflip and varial years before I learned the
              imposible, which I think you'll find is typical of most
              skaters.  Of course I could do all three years before I knew
              what a moment of inertia tensor was or could prove the tenis
              racket theorem.
              \- Oh, i havent heard that name. what CM text? that is a pretty
                 good name, although since a rackt isnt symmetric in one of
                 the axes, people may get distracted by that. i didnt claim
                 a pillow was the best object to demonstrate, but i think more
                 people on the motd have a pillow than a skateboard. but sure,
                 i think people have an intuitive sense of the instability of
                 of the "middle rotation" with the s'board and racket. i always
                 liked the calculations/proofs that had physical interp ...
                 kepler planet laws, calculate escape velocity, period of a
                 pendulum indep of mass ... more than the contrived problems.
                 \_ Barger and Olsson, which I loathed.
                    I really liked that class, and learned from a mix of
                    different books plus lecture, but I do not recomend this
                    book except for a couple random topics.  I see what you
                    mean about pillow vs. skateboard.  I guess my point is
                    that while the typical pillow user does not do a whole
                    lot of rotational mechanics experiments, the typical
                    skateboard user spends hours and hours conducting those
                    experiments and develops a certain intuition about it.
                 \_ I replied earlier and it got deleted.  The text was
                    Barger and Olson[sp?], which I do not recommend.  The class
                    kicked ass, but that text was overall pretty weak.  I see
                    what you mean about more people having access to a pillow.
                    My arguement is that while there are fewer skateboard users
                    than pillow users, most pillow users rarely do rotational
                    mechanics experiments with their pillows whereas skaters
                    spend so much time doing these experiments that they have
                    multiple names for all three of the principle axes.  Also,
                    I think a lot of non-skaters now know what the kickflip
                    and the ollie impossible are because of that Tony Hawk
                    video game.
                    \- oh, i have not heard of that book. i didnt think
                       MARION and THORNTON was that exciting. GOLDSTEIN
                       was really good but pretty hard. herstein:algebra::
                       goldstein::mechanics. VI ARNOLD was life changing, but
                       really that is an EVANS HALL book not a LECONTE book.
                       have you also used LANDAU and LIFSHITZ? I have only
                       analyized their awesome Stat Mech book, but their
                       Classical Mech book is also supposed to be awesome.
                       BTW, the AMAZONG comments for some of these books
                       are pretty funne, esp for MISNER && THORNE && WHEELER.
                       oh, i suppose you can alos do the "tennis racket"
                       experiment with an UNOPENED CEREAL BOX.
                       One of my favorite AMAZONG comments is from UCB
                       MONSTER FIELDS PROFESSOR about BOGOLIUBOV QFT book
                       \_  I think the Jackson comments on Amazon are some of
                           the funniest.  Also the comments on Wolfram's
                           latest doorstop are hillarious.  Yeah, L&L rules.
                           I used that a bit during the course.  Where you a
                           physics major, or are you just into it for fun?
                           \_ started in physics but didnt want to do 111
                              and a year of 110 [i spent some time designing
                              the polarimetery system of a satellite so i
                              got enough EM on the job] so ended up doing
                              a lot of work in smplectic geometry and
                              ergodic theory and lie algebras.
           \_ thanks... i flunked my Fizzix 7A :p
           \_ I tried the pillow experiment.  That is cool.
2005/11/23-28 [Science/Physics] UID:40715 Activity:nil
11/23   Physicists at UCR may have made positronium:
        \_ I find it hard to believe that a positron/electron atom could
           exist, and the evidence they've presented is pretty weak.
           \_ if you bothered to read the article, the positronium atoms
              are a given at this point, and have been made.  What they
              are announcing is evidence that they made Molecules out of these
              \_ reading is hard; let's play motd!
2005/11/17-19 [Science/Physics] UID:40637 Activity:kinda low
11/17   Warp Drive Patented:
        \_ While this patent is clearly bullshit, it is not completely clear
           that Podkletnov's work is all bullshit.  It's true that no one
           has been able to duplicate it, but Podkletnov is a very odd
           person, and has been very paranoid about giving out certain key
           details about how to duplicate the experiment because he hopes
           to perfect it on his own with a shoestring budget and get rich
           off of it.  A friend of mine is totally obsessed with this work,
           and is neither a believer nor a total skeptic, but has spent time
           sniffing around in Europe, talking to some of Podkletnov's
           co-authors trying to get to the bottom of this, and he's still
           not convinced either way.  Part of what's interesting about it
           is that since no honest person seriously claims that high T_C
           superconductors are understood, there's plenty of room for crazy,
           unanticipated physics, and some theorists have been able to make
           crap up that might support Podkletnov's work.  Definitely worth
           keeping an eye on.
           \_ "yeah, who needs a Nobel Prize, I'll just advance the frontiers
               of science by screwing around in my garage."  The guy's an
               obvious crackpot.  -tom
        \_ You might want to listen to Act III from This American Life:
2005/9/22-23 [Science/Physics] UID:39827 Activity:high
9/22    What are the downsides to using a nuclear bomb to disperse forming
        Islamic extremists?  I'm pretty sure the cost of the bomb would be
        offset by the money saved in devastation (100+ billion in a major city
        \_ 9/23 reply:
        \_ if you use a neutron bomb, nothing (well other than a bunch of
           annoying anti-bomb peacenicks protesting in the streets and
           annoying anti-bomb peaceniks protesting in the streets and
           making the morning commute that much worse)
           \_ Does the US even possess neutron weapons anymore?  I thought
              those were only deployed for a brief time during the '80s as
              a buffer against a Russian tank invasion of Europe?
              \_ Possibly.  They have a short shelf life, and we aren't
                 making anymore AFAIK.  We might be refurbishing them
              \_ Do you really think the government is dumb enough to
                 get rid of something like the neutron bomb (regardless
                 of what the official peacenik friendly story is)?
              \_ Do you really think the government is dumb enough to get
                 rid of something like the neutron bomb (the official
                 story is probably just a cover to keep the peaceniks
        \_ Assuming this is a serious question, (a) the islamic extremists
           that threaten anyone don't "form" per se, (b) we'd blow up a lot
           of innocent people and their infrastructure which we're at least
           not supposed to do, (c) we have always had a policy since the end
           of WWII of never using nukes first, and (d) nobody would ever ever
           talk to the US again.  Go sit in a corner.  -John
           \_ re (b), best reason to use a neutron bomb, the infrastructure
              remains intact, some collateral human damage will occur, but
              in war that can't be helped.
              re (c), the no first strike policy has been "reviewed" by the
              current admin and may be rescinded if the situation was dire
              enough - therefore this policy is presently not a barrier to
              the use of "nucular" weapons
              re (d), the US is not well liked overseas, it is not likely
              that further degradation of international opinion is a major
              concern to the decision makers - armed retaliation may be a
              concern but currently no nation can field a force sufficient
              to make retaliation a sufficient threat to avoid first strike.
              \_ neutron bombs are still atomic bombs ; they are just optimized
                 for radiation output vs. explosive blast power.  If you want
                 to kill people and not infrastructure biological and chemical
                 weapons are the way to go.  There's significant political
                 costs to their use, however...
                 \_ As opposed to less significant costs for normal atomic
2005/8/21-22 [Science/Electric, Science/Physics] UID:39208 Activity:nil
        Ok can some physics person explain this:
        "the light signal travelled faster than 300 million meters a
        second. And even though this seems to violate all sorts of cherished
        physical assumptions, Einstein needn't move over -- relativity isn't
        called into question, because only a portion of the signal is affected"
        \_ Speed is length traveled over time taken.  The trouble is, length
           traveled of a set of particles isn't a precise interval, but a
           'smear' due to quantum effects.  So some particles traveled a little
           more and some a little less.  If the length traveled is very short,
           these sorts of 'smear' effects become significant.  Actually, the
           way I understand it, the particles that finish 'a little after the
           finish line' also started 'a little after the start line', except
           we had no measurements of this.  So each particle is still traveling
           at c.  But this is a 'sane interpretation' where things have
           positions. -- ilyas
2005/8/20-22 [Science/Physics] UID:39203 Activity:nil
8/19    [ Thread deleted out of frustration.  I can't seem to explain my
          own question, so people just show up to chew the fat about QM.
          Not a single person gave me an account of what an 'observation'
          exactly is.  I know what the slit experiment is.  I know what all
          the conventional interpretations of QM say.  Doesn't it bother anybody
          that the standard interpretation of QM is based on an apparently
          undefined notion? ] -- ilyas
        \_ Re last sentence - it bothers/has bothered lots of people (including
           Bohr and Einstein). You may wish to see:
           [ and many others, you can google as well as I can ]
        \_ Also be aware that attempts to reconcile microscopic notions
           with the macroscopic world have plagued physicists for a long
           time. It boggles our minds that certain particles can be in
           many states at once. So does the wave-particle duality and some
           other issues. I think this field is still very young and a lot
           more will be learned and the model will be refined.
           \_ I think an important point is that the field is also
              *experimentally* young.  The number of physical systems in which
              quantum mechanical entanglement, decoherence, etc. are being
              tested is growing very rapidly (thanks to the fact that the NSA
              is willing to throw hundreds of millions of dollars at quantum
2005/8/19-20 [Science/Physics] UID:39194 Activity:high
8/19    Anybody who knows any physics, what's the deal with QM being based
        on the notion of an 'observer?'  Does anybody understand what an
        'observer' means in QM context?  I mean of course the standard
        interpretation of QM usually taught. -- ilyas
        \_ Once you *know* the cat is in the box, the cat can't not be in
           the box.
        \_ all of modern science builds models with a latent component and
           an observable component. QM isn't "based" on an observed. Its models
           just follow the latent-observable dichotomy. It's healthy. There
           are things you see, and things you want to know.
        \_ As I understand it under the most widely accepted interpretation
           of QM, the Bohr-Heisenberg Copenhagen Interpretation, the state
           of an atom is indeterminate prior to observation. Note that CI
           is not the only interpretation of QM (some others I've heard of
           are the hidden variables theory, the many-worlds theory and
           \_ It's a probability function and where on the function the
              atom is can only be known when you observe it. By observing
              it you "give" it a state.
              \_ The problem, as I understand it, is that you can only
                 give something a state via observation if that thing
                 is in a closed system. However, no such system exists
                 anywhere in the universe.
                 Also the implication of CI is that w/o some sort of
                 observers the universe does not "exist" other than
                 as a superposition of all possible states. Many,
                 including Einstein, felt that this cannot possibly
                 be true. [ Note I am not a physicist, I've mostly on
                 read about this stuff in Lectures on Physics, &c. ]
        \_ At a basic level you can't observe a system without changing it.
           You need to affect its state in some way to make a measurement.  An
           'observation' is really no different from plain old interference.
           To take the Shrodinger's cat example, observation is information,
           aka. photons leaving the box, and prior to that any internal state
           was possible.
           \_ I don't mean to be rude, but I don't think what you posted is
              really answering my question.  -- ilyas
           \_ So what exactly changed that allows me to see a live cat?
              Why would a camera (or a robot) not see a live cat? -- ilyas
              \_ Because now the box can't not have a live cat.
                 \_ You don't seem to understand my problem.  Why am I an
                    observer, but a camera, or a robot, or a robot that looks
                    and acts exactly like me isn't an observer?  What is an
                    'observer'? -- ilyas
                    \_ Anything that alters the internal state of the box by
                       letting photons out of it is an observer.  So a robot
                       which opens the box and snaps a picture would cause the
                       cat to assume a single state.  However if you set up
                       the experiment with a camera on a timer inside the box
                       then until something external observes/changes the box
                       both the cat and the image on the film are in an
                       indeterminate state. -pp
                       \_ But what if the robot himself is also in another
                          bigger box?  Shouldn't the state of the at now be
                          entangled with the state of the robot?  I can setup
                          lots of boxes like one of those russian Matryoshka
                          dolls -- at what point does the state of the cat
                          get settled? -- ilyas
                    \_ In any given problem you're applying QM to you define
                       something to be your "system".  In real life it's
                       probably an atom or something, but in the cat example
                       it's generally assumed to be the box and the cat
                       together.  An "observer" can be anything from the rest
                       of the universe interacting with the system.  So it's
                       a bit arbitrary.  I think the point is, though, that
                       you always draw the line between observer and system
                       between *you* and your experiment somewhere.  Another
                       observer could put you in the "system" box and say
                       the same things about your quantum state that you can
                       about some cat in a box.  So to I think answer your
                       question, in the interpretation of QM I was tought
                       the concept of observer has nothing to do with sentience.
                       the concept of observer has nothing to do with
                       Of course, since you've already classified my brain
                       as:small, you might want to ignore what I have to say.
                    \_ The camera doesn't make an observation. Until you
                       view the film the state of the film is indeterminate -
                       the film could be in any valid state. Only when you
                       view the film does its wave function collapse into
                       a particular state.
                       In order for any of this to make sense the observer
                       must be outside the closed system that is observed.
                       HOWEVER, there is no such thing as a closed system
                       w/in the universe.
                       \_ So to summarize, there is no closed system in the
                          Universe.  So while in Schrodinger's hypothetical
                          experiment the cat's state gets settled, it would
                          not get settled in ours.  So does the collapse
                          phenomenon exist or not? -- ilyas
           In the wave model, much significance is often attached to the
           idea that determining the position of a particle close to the
           slits "destroys" the "interference" because the "wave function
           If you measure the position of the electron just before it gets
           to the slit, you totally change the outcome of the experiment.
           A simple and elegant way of proving that the observer is part
           of the experiment. I will try to find a cleaner explaination
           of this phenomena. -ausman
2005/8/19-22 [Science/Physics, Science/Biology] UID:39188 Activity:moderate
8/19    Hey Emarkp.  Re: Religion. Please prove that there is God. For
        extra credit prove Joseph Smith was telling the truth.
        \_ Someone deleted this along with a post about ID.  I'll note that I'm
           not presenting God or Joseph Smith as a falsifiable scientific
           theory.  ID proponents /are/ claiming their theory as science.
           \_ We had a long discussion about this already.  In the narrow
              sense of
        \_ Please prove there is no god.  For extra credit prove Joseph Smith
           was not telling the truth.
           \_ The burden of proof is on someone who claims God exists.  (Just
              like the burden of proof of evolution being on someone who claims
              evolution is real.)
                 \_ Absence of proof is not proof of absence ;-)
                    \_ yup, Rumsfeld can tell you that it worked well with
              \_ You are confusing a syntactic distinction with a semantic one.
                 You seem to be saying that existence statements are 'special'
                 and require more proof than their negations.  But almost
                 anything can be phrased as an existence statement (e.g.
                 there exists a sequence of physical events giving rise to
                 a bacterium while starting from raw chemicals).
                 \_ What about "One can't prove a negative."?
                    \_ I don't understand what this means.  In mathematics,
                       as in empirical science, 'a negative' is just a
                       syntactic distinction.  In math what you can prove
                       usually has little relation to its syntactic form.
                       In empirical science you can prove nothing.
                       \_ Apparently you flunked Science. The central tenet
                          of science is that if you can't empirically prove
                          that it does exist, we will assume that it
                          doesn't. Science has traditionally followed
                          such principals as Occam's Razor, in which
                          the simplist explanation (we assume that
                          things do not exist until they are empirically
                          proven to be as such) is usually the most
                          \_ Uh no, science says that if something cannot be
                             empirically proven, it means that it cannot be
                             empirically proven.  Whether that implies "yet" or
                             "at all" is up to the observer.  Last I checked,
                             science made allowance for, say, circumstantial or
                             observational evidence not obtained through proper
                             empirical experimentation, even though you wouldn't
                             necessarily rely on these as proof.  Note that I'm
                             not implying that ID and friends are complete and
                             not implying that ID and friends aren't complete,
                             utter intellectually dishonest bunkum, I would
                             just like to point out the flaw here.  -John
                          likeliest. Also, in science, it's not merely
                          a syntactic distinction, that's why it's referred
                          to as empirical science vs. religious wizardry.
                          And math != science, because yes, math IS
                          pure syntatics.
                          \_ 'Empirically prove'?  'Pure syntatics?'
                             'Simplist'?  'Likeliest'?  You such at science,
                             you suck at English, you suck at trolling, and you
                             suck at life.
                          \_ Since Science can't explain the change from
                             "nothing" to "something" in the universe should
                             we assume that Science doesn't exist or that
                             the universe doesn't exist?  Please explain
                             further.  ;-)
                             \_ Science CAN explain how the universe could
                                have come from nothing:
                                \_ Nonsense.  Did you even read your own link?
                                   It not only doesn't attempt to explain how
                                   the universe was created.  It makes it
                                   quite clear that we have no idea and
                                   presents a bunch of ideas that don't rise
                                   above the level of hypothesis.  These
                                   non-explanations are no better than "God
                                   did it" or "it fell out of a magic hat with
                                   a rabbit".  By the standards mentioned
                                   earlier in this thread not only does
                                   science not exist, but the universe doesn't
                                   either.  Your link (that you apparently
                                   didn't read or expected others not to) says
                                   something entirely different from what you
                                   claim it says.
                                   \_ Alexander Vilenkin (mentioned in the
                                      link above) has written many papers
                                      about this. You can google for more
                                      detailed info.
                                   \_ Well the universe does exist to
                                      science since we observe it.
2005/8/16-20 [Politics/Domestic/911, Science/Physics] UID:39143 Activity:nil
8/16    Once again, the onion news story sounds no sillier than the reality:
        "Even critics of Intelligent Falling admit that Einstein's ideas about
         gravity are mathematically irreconcilable with quantum mechanics. This
         fact, Intelligent Falling proponents say, proves that gravity is a
         theory in crisis."
        \_ The differential equation on the screen is awesome.
           \_ What does it read?  It's too small for me.
              \_ dx/dt = 1 Cor. 1:10
                 \_ Sweet...
                 \_ Haha!  This shows how silly the Evangelical "scientists"
                    are.  Gravity is related to acceleration, which is dv/dt
                    not dx/dt.
                    Oh shit!  I forgot that this is The Onion!
                    \_ tom's axiom 1
        \_ What Newton said, in his own words:
           \_ Makes sense to me.  That's why people say he came up with the
              "law of gravity" versus "a theory of gravity".  Not saying that
              a theory is a full explanation, but at least it's more in that
2005/8/9-13 [Science/Biology, Science/Physics] UID:39076 Activity:moderate
          \_ this link doesn't work anymore
        I haven't been paying attention to the ID vs. Evolution
        discussion but I read this in the Merc and I was a bit
        surprised by the arguments made in favor of ID.
        Do the ID folks really think that the universe has more
        order now than at some point in the past when all the
        forces were unified (more entropy/disorder now right?)
        Also I'm confused by the assertion that the laws of nature
        imply ID. Isn't is equally plausible that the laws of
        nature are the result of (1) random chance or (2) the
        result of a natural process (such as collisions of branes
        in higher dimensional space) that creates an infinite
        number of universes so all possible laws of physics are
        \_ Well, I don't know about most of the arguments presented, but
           it is a little puzzling that the fundamental constants would arrange
           themselves randomly into an interesting looking universe that
           we have.  If things were a little off, the universe would be
           it is a little puzzling that the fundamental constants would
           arrange themselves randomly into an interesting looking universe
           that we have.  If things were a little off, the universe would be
           very boring indeed. -- ilyas
           \_ But there is a small but finite probability that the came
              about by random chance right?
              And by boring you mean boring to people right? Some other
              arrangement might give rise to a universe that is interesting
              to different form of "life".
              What I don't understand about ID is that there does not
              appear to be a way to show that ID is more likely than
              the theory that branes are/have been colliding in higher
              dimensional space for an infinite amt of time thus making
              possible every arrangement of the fundamental constants.
              How can one accept a theory which is by definition un-
              \_ By 'boring' I mean you can't have life as we understand it
                   -- low entropy entities that use energy to maintain their
                   state, or for that matter planets, stars and galaxies --
                   things needed to support life. -- ilyas
                 \_ The only way we can even talk about this is if we
                    happen to have the conditions for life.  So, just
                    out luck that we happen to have these conditions,
                    however small the chance.  It really doesn't prove
                            \_ And this is called the "weak anthropic"
                               principle.  For some strange reason, I can't
                               find anything in ID addressing it (which I'd
                               think would be important). -emarkp
                    \_ You don't understand.  This isn't meant to be a proof
                       of anything, but something requiring an explanation.
                         -- ilyas
                         \_ The point you're missing is that if there are
                            an infinite number of universes, only in the
                            ones where the physical laws are conducive to
                            the rise of intelligent life will there ever
                            be anyone to notice that the physical laws
                            are conducive to the rise of intelligent
                            life.  -tom
                            \_ And what if there isn't an infinite number of
                               universes?  Occam's razor says to assume the
                               least.  Why is it more 'expensive' to assume
                               intelligent design than to assume infinitely
                               many universes? -- ilyas
                               \_ Because intelligent design still presupposes
                                  a creator, which just pushes the question
                                  up a level; who created the creator?
                                  It's a lot easier to assume an infinitude
                                  of universes than to assume that an
                                  intelligent being somehow sprang into
                                  existence before the universe did.  -tom
                                  \_ So you would rather postulate an
                                     infinitude of worlds than suspend for a
                                     moment your intuitions borne of your
                                     linear perception of time?  Seems like
                                     people suspend intuitions a lot when
                                     looking at fundamental things -- consider
                                     quantum mechanics.  I should mention that
                                     'created' is a causal notion, and causality
                                     is an illusion, a way our brain organizes
                                     information.  There is no causality in
                                     physics. -- ilyas
                                     'created' is a causal notion, and
                                     causality is an illusion, a way our
                                     brain organizes information.  There is
                                     no causality in physics. -- ilyas
                                     \_ Wikipedia on "Causality (physics)":
                                        "special relativity has shown that it
                                        is not only impossible to influence the
                                        "Despite these subtleties, causality
                                        remains an important and valid concept
                                        in physical theories."
                                        \_ This is one of those cases where I
                                           know more about the subject matter
                                           than wikipedia.  There is no
                                           causality in physics, only in
                                           physicists.  The standing of
                                           causality in modern physics is so
                                           weak that even my advisor, a fairly
                                           influential causality guy, concedes
                                           that it's all likely an artifact of
                                           the human brain, and not an objective
                                           feature of reality.  On a slightly
                                           unrelated note, I wish people would
                                           stop quoting wikipedia as an
                                           authoritative source.  I read some of
                                           their 'contention' pages, and wasn't
                                           really impressed.  You don't have to
                                           look far to find wikipedia blatantly
                                           being wrong -- in the general
                                           Causality article, Pearl and
                                           Spirtes are listed under
                                           'Probabilistic Causality,' which is
                                           untrue, proponents of that area
                                           include Good, Cartwright, etc.
                                           Pearl/Spirtes are in 'Structural
                                           Causality.'  Wikipedia is trash.
                                             -- ilyas
                                           the human brain, and not an
                                           objective feature of reality.  On
                                           a slightly unrelated note, I wish
                                           people would stop quoting
                                           wikipedia as an authoritative
                                           source.  I read some of their
                                           'contention' pages, and wasn't
                                           really impressed.  You don't have
                                           to look far to find wikipedia
                                           blatantly being wrong -- in the
                                           general Causality article, Pearl
                                           and Spirtes are listed under
                                           'Probabilistic Causality,' which
                                           is untrue, proponents of that
                                           area include Good, Cartwright,
                                           etc. Pearl/Spirtes are in
                                           'Structural Causality.'
                                           Wikipedia is trash. -- ilyas
                                           \_ I support quoting of Wikipedia as
                                              an authoritative source, with
                                              disagreements with Wikipedia well
                                              disagreements with Wikipedia
                                              documented on motd for any sodan
                                              to evaluate. -jctwu
                                              to evaluate.  Wikipedia's
                                              usefulness significantly
                                              outweighs its negatives when
                                              used in this way. -jctwu
                                              \_ What usefulness?  It's an
                                                 encyclopedia and it's WRONG.
                                                 A lot.  Do you really want me
                                                 to look through the causality
                                                 article and list all things it
                                                 got wrong?  Wikipedia's
                                                 'usefulness' is misleading
                                                 people into thinking they
                                                 know something.  -- ilyas
                                                 \_ Then fix it man -- you're
                                                    extremely lucid in your
                                                    writing when you set your
                                                    mind to it.  That's one of
                                                    the nice things about
                                                    Wikipedia -- I assume that
                                                    people with brains and
                                                    enough confidence in their
                                                    knowledge go in and remove
                                                    blatant inaccuracies, so
                                                    as time goes on, the
                                                    overall quality of the
                                                    information gets better.
                                                    Don't get me wrong -- it's
                                                    still a source of info
                                                    which resides in the
                                                    internet and therefore is
                                                    deserving of a little
                                                    skepticism, but it's still
                                                    a damned handy reference.
                                                 \_ It's a Wiki-based
                                                    encyclopedia, not a
                                                    traditional encyclopedia.
                                                    In your opinion, Wikipedia
                                                    is trash; I already stated
                                                    my opinion.
                                                    You could also submit a
                                                    change, but that's your
                                                    prerogative whether you
                                                    do or do not and why you
                                                    I don't think we can get
                                                    any farther than this.
                                                    any farther on this.
                                                    One more thing you can do:
                                                    We can avoid the subjective
                                                    question of whether
                                                    Wikipedia is useful or not,
                                                    and you can instead explain
                                                    calmly and succinctly why
                                                    there is no causality in
                                                    physics, and/or post a URL
                                                    which says so.  Pretend
                                                    you're Feynman lecturing to
                                                    a freshman physics class.
                            \_ This logic appeals to me, but many find
                               it deficient.  Of course, if things weren't
                               conducive to us being here, we wouldn't be
                               here....  Those who have the most trouble
                               with this usually cite the incredible odds
                               against it.  However, with possibly a trillion
                               "trial" locations, over a span of billions of
                               years, it doesn't seem unlikely to me that
                               life would somewhere arise and ponder the
                               unlikelyhood of it all....  But the pondering
                               would 100% take place in those lucky, rare
                               locations that "won".  Like here.
                                         \-there is a good paper that assess
                                           the amount of "tolerance" we can
                                           have in various "free parameters"
                                           [i.e. the fundamental physical
                                           constants] in light of the
                                           anthropomorphic principle [the idea
                                           that we have to be here to to ask
                                           the questions] ... i can dig up
                                           the reference if there is interest.
                                           if you are interested in this
                                           you may want to review first review
                                           the list of free parameters ...
                                           some of them are pretty technical
                                           but you need some knowledge of what
                                           the are to see how things fit
                                           in terms of "dependencies". there
                                           are many good discussions of this.
                               \_ Who says there are "trials" or they take any
                                  "time"?  Why not "every possible existence
                                  that could be, is"?  And maybe that means
                                  there are an infinite number of existences,
                                  and maybe that means there are a finite but
                                  greater than one number and maybe that means
                                  this is it and the only it.  It's all just
                                  freshman lounge chat anyway since we can't
                                  ever know but this is better than a lot of
                                  the other motd/wall posts.
                   \_ Hey ilyas, tell us about the stars.  -aspo
                      \_ Aspolito is a meme's way of making another meme.
                           -- ilyas
        \_ ID is intellectual fraud.  It presents strawman arguments about
           evolution and largely consists of handwaving.  I can't distinguish
           between it and more sophisticated moon-hoaxers. -emarkp
           \_ Do other religious conservatives give you a lot of shit for
              being such a decent, rational person on science issues?
              I think it's fantastic to see someone who self identifies as
              a religious conservative speak out against these people.  You
              can probably get a lot more traction stopping them from destroying
              American science than us liberal jewish athiest scientists.
              can probably get a lot more traction stopping them from
              destroying American science than us liberal jewish athiest
              \_ I've never been criticized for it.  I point it out
                 misrepresentations of science when I see them, and
                 misrepresentations of religion when I see /them/.  I'm
                 particularly annoyed about ID because it is an attempt to
                 misrepresent science to defend the author of physical law, and
                 I just read a 30-page article this weekend from ID that read
                 like an anti-religion tract but was basically anti-Evolution.
        \_ ID isn't really about the universe and physical laws, but
           more about:  Goddamn, can you believe a tiny sperm and a tiny
           egg can combine and grow into one new human being, without anything
           else going wrong?  GAWD or ALIENS must have been involved!
           \- a fairly cool book on weird examples and corner cases in
              biology is THE DIVERSITY OF LIFE by EO WILSON. I found this
              quite readable and interesting and I have a fairly limited
              bio background.
              \_ Cf. a good deal of Stephen Jay Gould's work on evolution.
                 \- isnt SJG soft on ID?
                    \_ No. Read Bully for Brontosaurus.
                 \- Some comments: the ID vs Evolution debate is somewhat
                    interesting for various reasons but it mainly has to
                    do with politics when hitting a low [like BUSH weighing
                    in about it] or philosophy of science [what is a theory
                    vs a collection of fact, what are standards of proof,
                    causality in an empirical or observational science].
                    if you are interested in actual debates on evolution,
                    those dont really concern the teleological or "invisible
                    hand" aspect of ID but other "legitimate" issues with
                    the various competing evolution theories.
                    dawkins and gould are the populerizers, but
                    you can also look at wilson, mayr [died recently too],
                    this fellow H. Orr, Stevene Pinker, matt ridley,
                    and r lewontin [recently gave a talk at berkeley]
                    and daniel dennet. a lot of these guys have secondary
                    agendas and strong personalities so it makes for
                    an interesting story/debate to follow.
        \_ The problems with ID are twofold: 1) It is not science, it is
           philosophy.  Don't teach philosophy in science classes.  And 2)
           As soon as you use the "The Wizard Did It" type of logic to explain
           the world then it's religion, not knowledge, and you can go to
           church to become indoctrinated in such a fashion.
2005/7/18-19 [Science/GlobalWarming, Science/Physics] UID:38679 Activity:nil
7/18    More "cold" fusion results:
        \_ So, this could possibly produce net energy gain?
           \_ A different article I read on this quite some time ago said no
              way, it was only interesting in a theoretical sense.
              \_ That's cool, I'm all for improving our understanding of
                 fusion.  It just that the article is half about how
                 fusion is going to solve all of our energy problems.
        \_ [elevated]
        \_ Someone posted on 4/27:
2005/7/13-14 [Recreation/Dating, Science/Physics] UID:38592 Activity:high
7/13    Color footage of Einstein:
        \_ obJewBaiting.
        \_ The bastard is smart but is still a bastard. "His letters reveal a
           tumultuous personal life, married twice and indifferent toward his
           children while obsessed with physics. Yet he charmed lovers and
           admirers with poetry and sailboat outings." What as ASSHOLE.
           I guess you can say that he's extremely brilliant and contributed
           greatly to mankind. He's also extremely horny and takes little
           responsibility for women he fucks and children he created.
           \_ Hey asshole.  Why do you keep deleting all replies to your
                \_ I didn't delete them, I just unintentionally overwritten
                   them since I don't use motdedit or vi
                   \_ I didn't kill him, I just shot him in the head.  Blame
                      the bullet.
                      \_ I think this kind of defense are actually used in
                         manslughter trials, sadly.
                \-FYI: one of einstein's children operated out of ucbberkeley
           \_ Frank Lloyd Wright did many of the same things: ignored
              children, had mistresses, obsessed with his work. Are there
              examples of geniuses who were consummate family men?
              \_ Yes, but FLW wasn't a Jew, which I suspect is what is really
                 clamping froth-boy's nipples.
                 \_ Pablo Picasso was never called an asshole.
                    Not like you.
                    \_ is that a punk rock reference? you're so cool!
                       \_ It is much cooler to accuse someone of anti-semitism
                          on the basis of absolutely no evidence.
                          \- there is a somewhat famous example in moral
                             philosophy that looks at paul gaugain chosen
                             by bernard williams [now dead but formerly
                             ucb phil] on this point ... "does success excuse
                             not honoring some claims people have on you".
              \_ iirc, Euler was a family man (twice married) but took care
                 of his kids, grandkids, &c.
                 Other examples from the top of my head: Bohr, Feynman,
                 Jefferson (and don't give me that crap about Jefferson's
                 slave kids, DNA testing shows that Jefferson's brother
                 was most likely the parent of the slave kids - Jefferson
                 gave his word to his wife when she died that there would
                 be no other women and Jefferson kept it).
                 Re Einstein - Two points:
                 (1) He is not a bastard as his parents were married at the
                     time of his birth.
                 (2) Even assuming the colloquial meaning of "bad person",
                     Einstein does not qualify. He may have been a distant
                     or less than ideal father (many non-genius fathers
                     fall into this category) but he never really neglected
                     his children. For example, he provided Mileva (wife 1)
                     and the children w/ all the money from his Nobel
                     prize. Also, he was basically separated from Mileva
                     when he started seeing Elza (wife 2). There is some
                     evid that he saw women on the side some years after
                     he married Elza but there is no proof that he fathered
                     any children w/ them (or that he dated anyone other
                     than Elza during his marriage).
        \_ meh
        \_ There was color movie back in 1943?
           \_ Ever seen Wizard of Oz?
           \_ This reminds me of the Calvin and Hobbes where Calvin asks his
              dad why old photos are always in black and white.
2005/5/26-27 [Science/Physics] UID:37845 Activity:low
5/26    LED capable of emitting exactly one photon each time:
        \_ Two questions: 1) The idea is that the receiver will know that a
           message is intercepted because a photon can only be received by
           either the interceptor or the receiver, not both.  But what if the
           intercepter then injects a different photon with the same wavelength
           back to the stream right away?  Then the receiver won't notice,
           right?  2) Regardless of #1, isn't it more important to prevent a
           message from being intercepted, than to know that the message has
           been intercepted after it happens?  It doesn't help much to find out
           that someone has intercepted your SSN when it is transmitted this
           \_For quantum criptography you need a PAIR  of coupled particles,
             one for the sender and one for the reciever.  Then both
             sides make spin measurements on either the x & z axis randomly.  By\
             comparing a subset of those measurements you can determine if some-\
             one was listening in.  The rest is used for a key.   -scottyg
           \_ You don't send your SSN that way, you send a random string of
              bits over the quantum channel, throw away the ones that get
              read by the evesdropper, and use the remaining bits as the key
              to a one time pad that you use to send the SSN over a classical
              \_ This answers #2, thanks.  What about #1?
           \_ Not an expert, but wouldn't there be a machine-perceptible
              delay as the intercepting device receives the photon and stores
              its identifying info, then recalibrates and sends a different
              photon with the same wavelength to the originally designated
              receiving end?
2005/4/28-30 [Science/Physics, Computer/Theory] UID:37415 Activity:nil
04/28   Quantum Crypto for Video Conferencing:
        \_ I think you don't need to crack every frame to steal secrets.  If
           you can crack the audio stream and you can crack one video frame per
           two or three seconds, that's good enough.
2005/4/28-30 [Recreation/Dating, Science/Physics] UID:37408 Activity:nil
4/28    I'm surprised this hasn't been posted yet. Husband and Wife physics
        professors fillibuster Frist:
        I recognize that Griffiths book from Physics h7a!
        \- Do you know who Ed Witten is?
2005/4/27-28 [Science/GlobalWarming, Science/Physics] UID:37385 Activity:nil
04/27   Desktop fusion
2005/3/14-15 [Science/Physics, Politics/Foreign/Europe] UID:36681 Activity:moderate
3/14    Why Mormons shouldn't move to UK:
        \_ What the hell does any of that have to do with mormonism?  Or even
           religion at all?  Huh?
        \_ Hi troll! -emarkp (I had more Physics and Math than just about
           anyone else I knew in the CS major.)
           \_ yes, and the war in Iraq is the right decision, and Bush is
              right, and everyone who thinks otherwise will go to hell.
              \_ Woohoo!  You win the stupidest troll of the day award!
                 \_ I don't think that's possible, given the guy below.  -tom
                    \_ I assume you mean those 2 in the gay marriage
                       thread?  Yeah, I wrote this before those were
                       posted.  Maybe we need to take a vote.
                       \_ Tom's a fag, he's obviously biased.
              \_ Wow, didn't know the "rightness" of the war in Iraq was
                 scientifically measurable.  And no, I don't make pronouncments
                 about a person's eternal soul based on their politics.
                 about a person's eternal progression based on their politics.
                 Oh and sign your name.  -emarkp
         \_ I'd rather be a mormon than a fag.
            \_ is that because you are mormon?
               \_ You misspelled "moron"
            \_ Why, exactly?  And why have you given this thought?
               \_ Well, I'll just throw gasoline on the troll fire and comment
                  that the two aren't mutually exclusive. -emarkp
                  \_ Uh oh.  I don't think your metaphors are rowing with a
                     full deck of marbles.
2005/3/10 [Science/GlobalWarming, Science/Physics] UID:36632 Activity:nil
3/10    Berkeley physicist Charles Townes wins Templeton prize for "advancing
        knowledge in spiritual matters".  News link: and here's a link to the
        essay that is primarily responsible for him winning the prize:
        The subject of the relationship between science and religion has come
        up a few times on the motd, so this seems relevant.
2005/3/8-9 [Science/GlobalWarming, Science/Physics] UID:36575 Activity:nil
3/8     RIP Hans Bethe
2005/2/25 [Science/Physics] UID:36423 Activity:very high
2/25    Is anti-matter and dark matter the same thing?  Thx.
        \_ Is our children learning?
           \_ No they ain't. As to original question, not at all.
              \_ No, you're wrong. Technically speaking dark-matter could
                 be the "same" as anti-matter if it turns out to be
                 composed of neutrinos. Since neutrinos are their own
                 anti-particle you could say that dark matter is composed
                 of anti-matter. Right now we don't know what dark matter
                 is. Perhaps it could be composed primarily of some sort
                 of anti-matter. Nobody knows.
           \_ "More seldom than not, the movies gives us exquisite sex and
              wholesome violence, that underscores our values. Every two
              child did. I will."
        \_ Dark matter is quite different from normal baryonic matter
           and anti-matter.  There are several views on what exactly
           anti-matter is, but in general it can be though of as
           matter that is composed of particles that are similar to
           protons and electrons except that they have the opposite
           charge (ex. positron is an electron with a + charge).
           Dark matter is completely different. It interacts with
           regular matter very weakly and is probably not composed
           of any sort of known particles. Dark matter's presence
           is mostly inferred from gravitational anomalies in the
           rotation of galaxies.  Some newer experiments are trying
           to detect dark matter based on nuclear interactions, but
           so far nothing has turned up.
           \_ There was some /. story recently on something that looks like
              an entire galaxy composed entirely of dark matter.  Dark matter
              has a bit of a 'magic blue smoke' quality to it, imo. -- ilyas
              \_ I agree. The entire dark-matter/dark-energy discussion
                 reminds me a lot about the cosmic ether discussions prior
                 to SR. It seems like the universe is telling us something
                 fundamental and physicists want to shoe-horn it into the
                 standard model.
                 BTW, how did they detect a dark matter galaxy?
                 \_ I am not a specialist, so I don't know (the article didn't
                    really explain it well).  Obviously using some indirect
                    way involving gravity, coupled with noticing there are no
                    stars there. -- ilyas
                    \_ If you are talking about the recent results re
                       VIRGOHI21, my understanding is that it was a
                       radio telescope search looking for H emission
                       lines. Also this isn't a dark matter galaxy
                       but a dark galaxy (basically a huge cloud of
                       H w/o many stars).
                       \_ I would be very surprised if you could get a cloud of
                          H to behave like a galaxy without any star formation.
                            -- ilyas
           \_ How much dark matter is in a liter of the air next to you?
              If none, how much dark matter is there in a liter of volume
              of deep space?
              If negligible, about how much volume of deep space would you
              need to get one particle of dark matter?
              \_ IIRC current estimates are that each second every square
                 meter of the earth passes through 1e9 dark matter particles.
                 \_ That means 1 liter has ~ one million dark matter particles!
                    I am swimming in dark matter!
                    \_ In comparison a liter of water has ~ 1e25 water
                       \_ If we take 1 liter of air, I'm getting ~ 4 particles
                          of dark matter for every trillion molecules of
                          air.  Is that right?
                          \_ Sort of. Dark matter is "there" but it doesn't
                             interact w/ regular matter. It just passes
                             through your body (and pretty much everything
                             else) as if it wasn't even there.
           \_ Hmmm, so the motd is dark-matter.  If we put ilyas and tom
              together, would they explode?
              \_ I think that you are confusing a few concepts. Dark
                 matter is weakly interacting and does not affect
                 normal matter except via its gravitation effect.
                 The following works a bit better: the motd is space-time,
                 ilyas is matter, tom is anti-matter. If they both
                 meet on the motd you will get an uncontrollable burst
                 of energy that will destroys everything in its path.
        \_ If the only way to detect dark matter so far is from gravitational
           anomalies, how do they know that dark matter is in the form of
           discrete particles (or wave-particles like the way normal particles
           are in quantum physics)?
           \_ If you really want to know, look online in a source that does
              not consist of computer science people.  There is much
              bullshit in the above answers, and I have become tired of
              having flamewars with morons on the motd about physics.
              Look on the websites of the various darkmatter searches out
              there, and they should have good explanations of what they're
              looking for and why.
              \_ is dark matter like the Force?
           \_ Not everyone agrees that dark matter is made of particles.
              The leading theory is from the super-symmetry people who
              think that one of the particles in their theory, the
              neutralino, fits the dark matter bill.
              FYI, SciAm had some decent articles on this topic a few
              months back.
2004/11/18 [Science/Physics] UID:34950 Activity:low
11/17   SICP for physics:
        \_ drool.  thank you.
        \_ OMG this rocks! Thank you.
2004/10/9-11 [Science/GlobalWarming, Science/Physics] UID:34011 Activity:nil
10/9    Regarding that Dyson dude on TV with the vacuum that doesn't lose
        suction- what's the technology that keeps the dirt away from the
        \_ Well I wrote a well thought-out reply but some douchebag overwrote
           it.  I was sort of right in that there can be no bag and that
           airflow causing the dust to settle might be the mechanism.  A little
           googling produced:
           So the airflow is designed to increase centrifugal force and stick
           the dirt to the side of the cannister.
2004/10/4-6 [Science/Physics, Reference/Military] UID:33922 Activity:high
10/4    Photon Torpedos anyone? (
        \_ A photon is not matter.  However, they *have* used antimatter
           weapons in trek.
           \_ m = E / c^2 :-)
              \_ No, a photon has no mass.  You just gave the mass-equivalence
                 of a photon.
           \_ Photon Torpedos are based on antimater:
        \_ Nothing will come from this for many decades, if ever.  They should
           be spending that money on something useful like the homeless or
           universal health care.
           \_ You can use the homeless as weapons?  Cool!
        \_ The article mentions positronium, but makes no mention of trying to
           use antihydrogen.  Is there some reason positronium is preferable?
           \_ We have to catch up to the terrorists who are already building
              anti-matter weapons out of unobtanium.
              \_ Why do you hate America?
        \_ Why is this conducted by the Air Force?  Shouldn't it be the Dept of
           Dept of Energy?  Air Force should be working on better planes,
           Energy in a Lawrence lab?  Air Force should be working on better planes,
           better missles, and maybe better space-based weapons, not working on
           something that involves so much fundamental physics.
           \_ The Air Force typically has always held sway over the "cutting
              edge/whiz bang/star trek side" of military tech.
              \_ no.  I know of quite a bit of far-out physics research
                 that gets funded by both the Navy and the Army.  The army
                 spends a lot of money on quantum computing, and you can't
                 get much more star trek than that.
                 \_ My computer told me otherwise this morning.  It was built
                    by the USMC with Marine-Tech(tm).
2004/9/29 [Science/GlobalWarming, Science/Physics] UID:33835 Activity:high
9/29    What an embarrassment for Nature.  The editors and Mann of global
        warming fame are beginning to look very suspicious.
        \_ The editors of Nature are known to be jackasses.  Talk to anyone
           who has been in any field of science at a high level for long
           enough to have dealt with them, and they'll all tell you this.
           And it's not just sour grapes.  I know pleny of people who've
           been published in Nature multiple times who think this.  As far
           as this stupid "dogleg plot" controversy goes, peer review is
           only as good as the peers of the person who submits the paper.
           Some fields have a lot of jackasses in them.  Just for shits and
           grins, you should go through the old copies of Nature from a
           hundred years ago or more in the stacks of a university
           library and see how nasty scientific controversies were back
           then.  Believe it or not, they were worse.
           \_ Were there scientific controversies 100 years ago that were
              used as evidence to promote the wholesale realignment of
              global industrial policy?
           \_ Yeah, there are some pretty horriable peer review stories out
              there.  We had a talk here at LLNL a month or so back about
              using bad computer data in published papers.  The peer review
              process let a lot of really bad science pass.  (Like, you can
              see that this graph increases linearly!  When investigated, it
              turns out they only plotted 2 points. etc.)
        \_ Are you a Republican?
           \_ Why do you ask?  Because only Republicans require good data to
              base their decisions on? -!op
              \_ There's no such thing as "good data".  There's only bias.
                 Once you have determined your bias, then you pick the data
                 to support your bias, and you form your conclusion based
                 on your data.
                 \_ There is good data.  Because of good data, bridges stay
                    up, airplanes fly, and the Internet doesn't grind to a
                    halt.  Nature is not forgiving to bias.  You should
                    maybe read up on this invention called
                    'empirical science.'  (Yes, my sarcasm detector is in
                    the shop). -- ilyas
                 \_ There is good data and there is bad data.  The data in the
                    seminal paper "Electron-Band Structure in Germanium, My
                    Ass" was bad data.
                    \_ And there is even worse than bad data, which is
                       cooked data. At least the E-BSiGMA paper accurately
                       plotted what he observed.
                       \_ I prefer my cooked data with gravy made from the
                          blood of the working man.
                          \_ Mm, one of my favorite recipes from "To Serve
2004/9/21 [Science/Physics] UID:33680 Activity:nil
9/21    [Iran nuke thread restored, completely]
        Hi, I'm a completely unqualified dolt who has taken physics 7C and
        I think Iran will have nuclear weapons in 24 months. What do you
        guys think?
        \_ I mean so what? We have nukes too. It's not like we are telling
           them, oh, you can't have it because no one have it. We invented
           WMD, we have the MOST WMD on earth, but sorry, you just can't have
           it because we are the big boss.
           \_ I think everybody should have nukes, this way, little Bush
              can't go around fuck other countries. Go NK.
          \_(Sarcastically) Oh, yeah, you are much smarter and wiser than
            sanctioned members of the inspection team, therefore even though
            they say it's gonna be one year you're completely right.
             \_yeah, but I took 7C with professor Blugerblat, and he said
               that it wasn't making a nuke that was a problem, it was
               refining the stuff in it.
               \_ Oh, you don't mean THE professor Blugerblat, do you? Oh my,
                  you MUST be an expert.
                  \_Well, I am, because A) I'm a liberal, B) I took physics 7C,
                    and C) I'm a disciple of Blugerblat. And the Hiroshima
                    bomb was never tested, nevermind that a bunch of existing
                    and future nobel laureates spent a couple years on
                    project Manhattan to develop the first atomic bomb,
                    because, goddamnit, I'm an expert because I took physics
                    7C. Did I mention I was a liberal and I took physics 7C?
        \_ We've used up all our credibility on Iraq, that we can't do
           anything to North Korea and Iran... and Pakistein (for helping out
           Iran/N.Korea to develop nukes).  Furthermore, this pre-emptive
           strike doctrine really need some revision.  United Nations just
           released a report saying that 40 countries has the capability of
           making nukes.  The thought of invading more than 4-5 coutries
           at the time is beyond my imagination.
              40 COUNTRIES AT ONCE!!!
2004/9/8 [Science/Physics, Politics] UID:33425 Activity:nil
9/8     Resurrected:
        \_ These are very different ideas.  Belief in an
           impersonal force which refrains from direct
           interaction with the universe admits for the
           possible existence of other metaphysical
           constructs, such as an afterlife.  If you deny
           the existence of anything metaphysical, you are
           stuck with just the physical.
           \_ So you're just kind of hoping for an afterlife. No real
              reasoning behind it. I guess my point is: what's the meaning
              of this possible afterlife? It seems like people just project
              the existential questions of this mortal life into this
              afterlife, and that settles that. But what do you do in that
              afterlife? And if you believe that the universe is running
              purely on physics then your life is tied to the physical
              processes of your body anyway (a soul is not physical).
              Of course, evidence tells this anyway (physical changes
              to the brain and brain chemistry directly affect people's
              minds). Personally I think the human race has the theoretical
              capacity to create "heaven" right here on Earth, and elsewhere.
              We just aren't quite advanced enough, don't focus all our
              energies toward it, and most of us complacently accept the
              standard religious placebos that avoid the question. I like
              to think that we ourselves collectively hold, in some measure,
              the power of our own salvation.
2004/8/30-31 [Science/Physics] UID:33238 Activity:high
        This creates some problems for the modern interpretation of
        quantum mechanics.  This is a very recent result: august 2004.
          -- ilyas
        \_ Ilyas, tell us about the...oh never mind.
        \_ OK what do we do now?
           \_ Well, presumably first we duplicate the results a couple of times
              to make sure it's right, and if they still hold, we chain some
              theoretical physicists to their chairs until they give a good
              interpretation of QM which fits this data. -- ilyas
                 \_ what the fuck ever.  for those of us who don't get
                    our science from blogs based on misunderstood crap,
                    here's what 10 seconds of google turned up:
                    basically various people debunking the article that the
                    blogsphere scrambled and amplified.
                    funny how Science and Nature missed out on this
                    "earthshattering" discovery.
                    \_ Hey idiot. Afshar is one of the bloggers. Fucknut.
                       Another one is Kathryn's dad John, who you may
                       have heard of. Jerk.
                       \_ hi ilyas!  glad to see you are still following the
                          inverse of the golden rule!
        \_ Shahriar Afshar is obviously a Kerry supporter.  Light, both a
           particle AND a wave, AND at the same time, too?  Which is it,
           Afshar?  You CAN'T have it both ways!
        \_ For those who are curious, the URL explains
           why Afshar is wrong.  Thanks.  No problems created.
                          \_ Wasn't me.  Try again.  Incidentally, Afshar
                             being wrong is _good_, not _bad_.  I am just
                             reporting an item of possible interest.
                               -- ilyas
                             \_ Oops.  You had seemed pretty irritable lately,
                                but not that much.
        \_ I really don't understand how these experiments are touted as
           showing the "dual nature" of light.  Like any double experiment
           this demonstrates 1.) the WAVE nature of light and 2.) the fact
           that the detector detects in discreet quantities.  There are
           equations for energy exchange between wave functions.  Where is
           the need to resort to any "particle" nature? -phuqm
2004/7/1-2 [Science/GlobalWarming, Science/Physics] UID:31108 Activity:very high
7/1     Light might have been slower 2 billion yrs ago:
        \_ Just in case you don't know, is about as reliable
           a source for science news as *name-of-random-tabloid* for news.
                \_ any better sources?
                   \_ <DEAD><DEAD>, and <DEAD><DEAD> for physics.
                      There must be others, but be warned that they are
                      all boring: the more reliable the more boring.
                      More generally, science != news != entertainment.
                   \_ Uh, Nature?  Departmental hearsay?  Anything? -- ilyas
           \_ Just by reading the article, I have no clue whether it's real or
              fake.  Are you saying that the article is a hoax, or it's just
              flawed science?
2004/6/17 [Science/Physics] UID:30871 Activity:nil
6/17    Atoms teleported:
2004/3/18 [Science/GlobalWarming, Science/Physics] UID:12743 Activity:nil
3/18    I love this.  What do we do when we found out Pakistan was selling
        nuclear technology to N.Korea, and other so-called "rogue nation?"
        We forgave 480 million USD of debt.  How ironic we actually invade
        Iraq for the same reason.  Moral of the story?  This is not about
        WMD, it's about being on the good side of USA.
        \_ Well duh, we're the good guys.
2004/3/15 [Science/Physics] UID:12664 Activity:high
3/15    Something for you Physics students  -John
        \_ so, are all you cs dudes "rolling in cash?" -physicsstudent
2004/1/29 [Science/Physics] UID:12006 Activity:nil
1/29    Fermionic condensate created: (
        \_ Fermions cannot form condensate.  Bosons can.  However, pairs of
           fermions can become pseudoparticle bonsons and condense, which is
           what happens in conventional superconductor.  What they probably
           achieved is cooling fermions so much that they fill up the fermi
           levels from ground up (almost) one-by-one.  (Look up phy 7C text.)
           It's interesting stuff, although calling it fermionic condensate is
           an intentional oxymoron and a PR exercise.  Also, there are far
           more known states of matter than listed in the above url.
           \_ The same phenomenon happens whenever you make a superconductor.
              Pairs of electrons act like bosons.  The only special thing is
              that they did it with bigger fermions than before.
              \_ I think not.  In conventional SC, fermions are bounded as
                 Cooper pair and not in their free states, but this is outside
                 the scope of motd.
                 \_ The valence (highest orbital) electrons form pairs and carry
                    the current.  The lower-orbital electrons are bound.
2003/12/4 [Science/Physics, Computer/Theory] UID:11308 Activity:nil
12/3    Did anybody catch the Nova series on PBS a month or so ago on
        String Theory?  What do you think of it?  Is this Witten guy really
        that smart?  He looks a bit phony.
        \_ Dunno about string theory, but string practice:  ~john/ringback.jpg
           \_ Hot.  Who's she?
        \_ why the fuck do people keep talking about this goddamn show?
           If you want to know about string theory, for some godforsaken
           reason, read a fucking book.
           \_ somepeople want a lay person's explanation to be done in
              an hour.  Books take much longer than that.
              \_ How about
              \_ I'll sum it up in two lines on the motd:
                 If a theory is unrelated to experiment, it's not
                 physics, it's philosophy.
                 for more information type "dict wank."
                 \_ Apparently you're a wank wannabe scientist who's never
                 read Kuhn. --williamc
                 \_ I heard there may be experiments with the potential
                    to falsify string theory coming after the CERN accelerator
                    comes online in 2006. -- ilyas
                    \_ right, and when they do, the theory will either
                       be falsified or just unverified.  wake me when
                       they can calculate the mass on the electron from
                       frist principles or predict a new particle
                       acurately, or do *anything* predictive. <snore>
                       \_ We will eventually run out of things to predict.
                          A theory isn't good only if it predicts something new
                          (although that's really nice).  A theory is good
                          if it doesn't contradict any data and is as small
                          as possible.  Personally I know next to nothing
                          about string theory, and lack the background to
                          learn more.  I don't know how well it fits, and
                          I don't know how small it is (or why there's so
              \_ How about
                          much hype).  -- ilyas
           \_ wow, this is the first time i heard this show mentioned. i must
              be out of it. anyway, go read Brian Greene's "The Elegant
              Universe." it gets pretty dense as you get into it, but given
              enough dedication, you can follow what he's writing.
              \- the Witten/Schwartz/MGreen(not BGreene) is a pretty standard
                 serious work on string theory:
                 witten solved a problem a bunch of other people were
                 stuck on [i think this is descrived in vague terms in
                 the show, but i saw it a only in part and a while ago]
                 annd he's not doubt a bright guy ... but personally i
                 find s. weinberg more impressive and certainly more
                 articulate. "dreams of a final theory" is a more accessible
                 but still interesting book. it's also cheeper than the
                 GSW book ... which is a $50 "paperback" and fairly tough
                 going if you dont have say 2yrs of grad math. --psb
                 \_ did anyone in this thread express interest in
                    a "standard serious work?"
                    \- dear mr. too short: "phony physicists rarely write
                       standard serious works". --psb
                       \_ fuck off. -real physicist
                          \_ you lie. a real physicist wouldn't call herself
                             such (maybe "physics grad student" or "physics
                             prof"). i wont make judgments on whether she'd
                             be posting to the motd.
                             \_ doh! you got me! it turns out that i'm the
                                pompus ass sysadmin knowitall who learns
                                about the most useless theory in physics
                                to impress girls at parties, and you're actually
                                the physicist! my bad!
2003/12/3 [Science/Biology, Science/Physics] UID:11286 Activity:nil
12/2    FYI, after the APA Board of Trustees removed homosexuality as a
        disorder from DSM-II in 1973, there was a big uproar from
        psychiatrists.  The issue was brought to a referendum, and out of
        ~ 10,000 votes, 58% voted that it should be removed from DSM-II.
        \_ Wow.  Science by vote.
           \_ of course. it's fundamental principle which democracy
                is build upon.  We can not allow few elites hijack
                the reality and the truth.  Science should belong to the
                oridinary people.
           \_ In a qualitative science, could you do any better?
              \_ Wtf is a qualitatiave science?
                 \_ One that relies on qualitative data.  I.e. "He was
                    diagnosed as crazy" vs. "He is 73.2% crazy"
                 \_ Contrast with quantitative. It's fuzzy science, if it is
                    science at all.
                    \_ That was sort of my point.  There are no fuzzy sciences.
                       There are analytic sciences (mathematics), and
                       empirical sciences (biology, physics, etc.).
                       \_ then, there is Chemistry. you can argue that it's
                          not a science at all.  -- ex Chem Eng major
2003/11/3 [Science/GlobalWarming, Science/Physics] UID:10912 Activity:moderate
11/2    I want to share a story regards to shoulder-fire missile.  In the late
        1980s, I was talking to an immigrant from the mainland China.
        What make him an interesting figure is that he used to work in
        some rocket R&D/manufacturing facility in Gan-Su province.  I
        asked him rather China could make stuff as cool as shoulder-fire
        missile like Stinger. He told me, to my suprise, yes.  According
        to him, China got a good R&D boost when then the Socialist
        government of Afghanistan captured bunch American made
        Stinger missles from the Muslim extremist rebel (read: TALIBAN)
        which USA supported. It gave the mainland China half dozen of
        those shoulder-fired missiles. By reverse engineering it, China
        was able to make, though crude by comprison, a mock up that
        actually works.

        Isn't it kind of funny that both the regime which USA supported
        and the Stinger missile technology it leaks out as result, are
        coming back and haunt USA?
        \_ Why would that be funny?  You see, kid, there was this thingy a
           few years back called 'The Cold War' in which two superpowers of
           markedly different ideologies fought for global supremacy through
           a variety of means.  Control of obscure pieces of territory where
           cash flow and stragetic positioning of intercontinental nuclear
           weapons was the currency used in this 'Cold War'.  Sadly, since
           both of these Superpower thingies existed in the real world
           (rather than your ESL anti-US utopia), nasty immoral things often
           had to be done to keep the opposing ideological faction from
           gaining the upperhand.  This led to both of these regimes supporting
           nasty evil religious or just plain nasty and evil dictatorships and
           other things to keep the other in check.  That there 'Cold War'
           is now over, and sadly, these evil little regimes are still there.
           It is a phenomenon often referred to by educated people as 'the
           lesser of two evils'.  Keep this one factoid in mind: You're not
           nearly as clever, perceptive, or intelligent as you think you are.
        \_ Yea really funny you fucking traitorous piece of shit.   Go
           back your homeland if its so great.
        \_ technology is good for only 10 years, till which it'll be made
           obsolete by other technology or be stolen and used against the
           originator. It's happened to the Greeks, Egyptians, Chinese,
           US vs. Brits, etc. Nothing new here.
           \_ agree, then why we are so obsessed with 50 year old technology
              such as Nuclear bomb and chemical weapon?
              \_ Uhm, because they're weapons capable of inflicting casualties
                 in the 5-7 digit range relatively instantly?  Because their
                 manufacture is pretty sophisticated?  Maybe because the
                 materials are often difficult to obtain, create, or find?
                 Maybe because there are people out there that are willing to
                 inflict insane civilian casualties for completely ideological
                 reasons based strictly on hate?
              \_ Hey, nice bit of intenional intellectual dishonesty and
                 stupidity.  Is there a class where they teach that sort of
                 self induced blindness?
        \_ this is not the first time in history. The Ballista technology
           was taken away from the Roman army. The Greek fire was copied and
           used against the inventor's home. The American colony got
           the gunmaking technology from the Brits and won. The Japs got
           the plane technology from Boeing to make lots of Mitsubishi Zeros
           to attack Pearl harbor. The list goes on and on. I saw a documentary
           that says a new war technology is good for only 10 years, after
           which it'll be stolen or made obsolete.
           \_ agree, that is why I thought it's silly to invade Iraq,
              sanction North Korea over  poliferation of nuclear bomb and
              other WMD.
        \_ The Taliban came later, but whatever.  Anyway, as the above said,
           this is standard in warfare.  If you bring something to the
           battlefield, the enemy will eventually get their hands on one and
           reverse engineer it.  If you don't bring a new weapon to the battle
           then there was no point in making it, eh?  In addition to the above
           list, I'd like to add the bazooka which the WWII Germans eventually
           captured.  As the story goes, a few German generals got wiped out
           by back blast during a demonstration, but hey, it's just a story.
           \_ My point is not so much about proliferation of technology, as it
              is bound to happen.  I just thought that it's really silly to
              proliferate technologies over muslim fundamental extremist.
                                -- OP
2003/10/25-26 [Politics/Domestic/Crime, Politics/Domestic/President/Bush, Science/Physics] UID:10784 Activity:nil
10/24   How much extra radiation do you get when flying during a Coronal Mass
        Ejaculation?  Like the one occuring right now.
        \_ "When that bowel shock strikes the earth's magnetic field, it's
           traveling a million miles an hour or more. So it's really moving.
           That's a lot of particles, a lot of hydrogen particles protons and
           electrons slamming in the magnetic field. And it sort of makes it
        \_ You'll die.
           \_ Sooner?
              \_ Instantly.  Like a marshmellow over a fire pit.
        \_ Should you worry more about possible plane crash caused by
           communication to control tower or GPS satellites being disrupted,
           than the higher radiation that you body receives?
           \_ In a word, Yes.
              \_ Like a marshmellow.  ZZZZT!
                 \_ ORBITAL LASERS!
                    \_ The Mafia with the help of the Men in Black and The
                       Evil Scientists for a Better Tomorrow would like to
                       attack to control The Orbital Mind Control Lasers.
                       Base attack is 11 or less.  Anyone want to pay to
                       stop it?
                       \_ I have a B-1 Bomber with a 100 Megaton warhead.
                          \_ SDI!
                       \_ Since the Boy Sprouts have a controlling influence
                          on the Mafia, and since the Rand Corporation owns
                          the Men in Black, NPR will stop that attack on
                          their soveignity over the OMCL.
                          \_ Not yet they don't!  I've got White Collar Crime!
                             Enron shuts off power to NPR's broadcast towers
                             and TOMC are mine!
2003/10/24 [Computer/SW/Apps, Science/Physics, Computer/Theory] UID:10762 Activity:high
        hahahahahahahahahahah!  --maxmcc
        \_ Dumbass.
                \_ =(((((((((((((((
                \_ ??????
2003/6/10-11 [Science/Physics] UID:28692 Activity:moderate
6/10    Physics buffs: back in physics 7C, the prof said that some physics
        genius/nobel laureate wrote a PhD dissertation that was only 3
        pages, but I forgot who he was. Does anyone know about this?
        \_ might have been laplace. -ali
        \_ I think I remember Prof. Zettel saying something about
           de Broglie's thesis on matter waves being really short. -emin
                \_ bingo! That was it. I had Zettl too. (looking it up
                   it was actually 7 pages. oops.) Thanks.
                   \_ it's always better in the retelling.  did you note he
                      used sub-pixel fonts and no margins?
2003/2/13-14 [Science/Physics] UID:27401 Activity:very high
2/13    What was the most impressive classroom science demonstration you've
        ever seen? ok to inlude TV, but only if it *could* be done in a
        \_ O-ring in a glass of ice water.
        \_ Detonation of a hydrogen-oxygen filled balloon.
        \_ Thermit reaction.  Very very bright and molten metal drips out
                the bottom.
        \_ first place  nuclear fusion, followed by a photon torpedo
           as a close second.
        \_ Something called a "Roman Candle". Lighting up a bunch of different
           chemicals that explode with different candles , starting with
           18M sulphuric acid. When I was in HS, I did this experiment in front
           of a bunch of 8th graders, who were thoroughly impressed.
        \_ we put a flux capacitor in the teachers deloreon
           \_ The one they do in Chem 1A during big game week with the blue
              and gold solutions.   ha ha ha.
        \_ In HS, our crazy scientist physics teacher put the van de
           graff generator up against the classroom's metal door knob.
           so when the attendance boy came to open the door, he got
           a nasty shock. our physics teacher giggled for hours. not
           so much impressive as amusing.
        \_ I always liked the demonstration of oxygen's magnetic properties
           by dumping liquid oxygen between two poles of a magnet and watching
           the liquid spin around as it evaporates.  If you must have the
           pyrotechnics, you could always light it and blow yourself up . . .
           \_ Pure oxygen doesn't combust.  It needs fuel.
        \_ The smokey serpent one:
        \_ In what grade are you target students?
           \_ second year undergrad, mostly EE students, some applied physics.
        \_ Dr Birkett's physics 7A demo when he shot a monkey (stuffed).
           Which included a performance by cal band for some reason
           \_ CAL BAND GREAT!
           \_ Jacobson did it better.
2002/12/11 [Science/GlobalWarming, Science/Physics] UID:26784 Activity:very high
12/10   Physics question: When one lifts weights, s/he exerts more forces,
        hence the pressure the ground s/he stands on receives more
        pressure.  Is that correct?  My friend tried to tell me it is
        rather because the object (the weights) are moving, it is the
        acceration that translates into greater force hence greater
        pressure.  But shouldn't the object as a whole (the weights +
        the weight lifter) be considered a still object since the area
        touching the ground isn't moving?  Any url reference to this
        would be great.
        \_ pressure is force per area, so if the are is fixed(the area
           of the bottoms of your shoes if you are standing), then the
           force is your weight plus the weight of the weights plus
           the added force from the acceleration of the weights.  this
           added force is the mass of the weights plus your arms(measuresd
           in slugs) times the acceleration you apply.  if you don't bielive
                \_ what do you mean measured in slugs?  It doens't matter
                   what units you use.  English units are confusing.  Best
                   to use kg to measure mass, but slugs will work too.
                   \_ right. i was just making the point that slugs
                      are mass and pounds are force.  IF you use kilograms,
                      you'd better use Newtons, which most people are
                      not familiar with.
           that this aceleration adds force, accelerate the weights as
           fast as you can, and feel the burn in the knees.
           to keep the same force, but change preassure on the floor, just
           change area: stand on tiptoes or sit down.
           \_ You can also do the experiment by lifting dumbbell while standing
              on a bathroom scale.  The reading is roughly the same as the
              force (although expressed in mass units) between your feet and
              the ground when the scale is not there.  Watch the reading
              becomes higher after you grab the dumbbells and hold them steady.
              Then watch the reading changing when you accelerate and
              decelerate the dumbbells in the vertical direction.
           \_ I understand f=ma.  But ultimately, it's the weight lifter
              that needs to exert more force.  The acceration of the
              weights is caused by the extra force the lifter has to put
              out.  My friend's argument is that the accerleration generates
              more force, but isn't it really the oher way around in this
              case?  The fact of the weights moving at an accerlerated speed
              and the greater pressure are both caused by the more force
              exerted from the lifter, no?
              \_ Don't confuse energy and force.  I can slump on the sofa
                 like a big pig not spending a single calorie of energy,
                 but my fat butt would still be exerting a force on the
                 sofa.  Remember Energy = Force x Distance Moved.  I
                 am a lazy bum who don't like to move, and AnyForce x Zero
                 is still equal to Zero.
                 \_ hmm.  I am more confused with weight v.s. force.
                          Isn't weight force in the first place? _/
                    Help me settle the bet here.  My friend's arguement
                    is weight changes as objects are being lifted.  But
                    my argument is it's the force that's changing, not
                    weight.  Isn't weight simply the gravitational pull
                    on the mass?  In this case, aren't both constant?
                    \_ What the bathroom scale usually measures is the
                       gravitational attraction (a force) between your mass
                       and the fat lump of mass we call the Earth.  When you
                       hold onto two dumbbells like some dumb body builder
                       and stand on the bathroom scale, it is now measuring the
                       the gravitational attraction between "your mass
                       plus two dumbbells" and the Earth.  When you are
                       further accelerating the two dumb bells upwards,
                       the bathroom scale is now measuring the above plus
                       an additional force exerted by the accelerating
                       dumbbells on your body.  Remember "Action Reaction".
                       That's why when measuring yourself on a bathroom scale,
                       you try to be naked, so that there isn't any
                       extra mass, and you try not to jump up and down.
                       What your friend refers to as "weight" is what
                       is measured on the bathroom scale.  What you
                       refer to as "weight" is the gravitational
                       attraction between your mass and the Earth's mass.
                       As seen above, the two of you are referring to
                       different things.  The two are only one and the same
                       when you are naked and not jumping up and down.
                       I think I have been trolled.  Oh well.
                    \_ Your friend's thinking is inherently flawed, but explain
                       it to him this way:
                       When you talk about a person's weight, you imply that
                       that person isn't moving.  If he jumps up while on a
                       scale, his "weight" will increase as he jumps up.
                       This is cheating; you take weight when you're standing
                       still.  So you can't be pushing dumbbells while taking
                       your weight.
                       Likewise, you can't raise your arms up and down.  Ask
                       him if his weight is changing when he's pumping his
                       arms or jumping on the scale.
              \_ conservation of angular momentum
                 \_ Huh?
                    \_ Check an elementary physics text.  Or sit on a
                       computer chair, hold a spinning bicycle wheel and
                       twist it.
                       \_ Yeah I know what conservation of angular momentum is,
                          but what does that have to do with the questions in
                          this thread?
        \_ the overall pressure's the same but your feet exert more.
                       \- if you have flies in a jar on a scale
                          the scale wil read the same whether they are
                          sitting on the bottom, the side or flying ...
                          but at lift off it will register more.
                        \- here is a fun problem: you have a uniform gold
                           chain of legnth l ... say 1meter ... with mass
                           m ... say 100 grams. you hold the chain l units
                           above a scale and drop it. so at t0 when you
                           release the chain, the scale reads 0 and at t1
                           then the chain is resting on the scale, it reads
                           m->100g ... plot f(t) between t0->t1 where f(t)
                           is what the scale reads. this might be sort of
                           unkind as an interview problem for a software
                           guy :-)   --psb
                                \_ Birkett demonstrated and then explained
                                   this in class once, but I forgot the
                                   physical basis of it. Can you post it?
                           \_ typical physics h7a homework problem
                                \_ yeah, so typical.
                           \_ Ok, I give up.  What is the solution?
                              I got a big complicated equation
                              ( (7Mggtt)/(2l) ) which I don't think
                              is right.
2002/6/26 [Science/Physics, Politics/Domestic/Immigration] UID:25199 Activity:very high

        Almost half of the U.S. recipients of the 2000 Nobel Prizes
        were immigrants to the United States. In the fields of
        Physics, Chemistry and Physiology, three American immigrant
        scientists were rewarded for their outstanding achievements.

        According to a 1998 National Research Council Report, about
        a third of U.S. winners of the Nobel Prize were born outside
        of the U.S. Further, between 1901 and 1991, 44 of the 100
        Nobel Prizes awarded to U.S. researchers were won by immigrants
        or their children.
        \_ a large fraction of these are a very specific group of people:
           european jews who immigrated by way of the nyc area.  City College
           was a free school that did not have quotas on jews as did MIT,
           Harvard, etc in the 30's and 40's, and it produced an absurdly
           high number of nobel prizes for a free school no one had heard of.
           many factors combinded to make this incredible generation of
           scientists, but it was an oddity of history from which it
           is dangerous to draw general conclusions.
           \_ Don't bring facts into this.  H1b == Nobel winner!  Yeah!
        \_ They forgot to include relevant figures such as the percentage
           of the general US population that is 1st or 2nd generation
           \_ Currently, 1st and 2nd generations make up about 20 percent,
              about 10 percent for each.
              \_ Aha, but what about in 1901?
        \_ How many H1-B's?
        \_ I hope this isn't some bizarre attempt to say that since the feds
           go out of their way to import top scientists from around the world
           that H1b's are good too.  Just don't even go there, it's such a
           stupid comparison.  We *should* be stripping the rest of the world
           of their top scientists.  That's good for America.  It is *not*
           good for American to import hundreds of thousands of the poorly
           trained dregs so Cisco and Sun can pay dirt to foreigners while
           more highly skilled US citizens are collecting unemployment.
           \_ have you considered that you're either demanding too much money,
              or not as highly skilled as you think you are?
              \_ Excuse me but I'm fully employed.  You're trying to deflect
                 the point (poorly).  I'll spell it out for you again:  Buying
                 foreign Nobel quality scientists is good.  Buying low wage
                 low skilled workers to replace skilled Americans is not good.
                 H1b's are not Nobel winners.  Thanks for the cheap shot and
                 the weak rhetorical attack.  I suggest a few weeks in an
                 intro Rhetoric course.
                 \_ So you're not unemployed, just irrationally xenophobic?
                    \_ You're still ducking.  Thanks for playing, troll.
                       \_ I wasn't the original poster.  But, it is quite
                          clear from your ignorant statements that you are
                          quite xenophobic.  The original poster said nothing
                          about this article leading any proof to why H1-B
                          visa status is good.  He was just citing an example.
                          However, your blanket statement about all H1-B's
                          being untrained and and unfit for employment in the
                          U.S. is indicative of poor mental hygiene.  Go back
                          to Georgia, you hick.
                          \_ It was an obvious response to threads from
                             yesterday.  Not my fault if you weren't around.
                             Go find it in the archives instead of slinging
                             meaningless personal insults.  It's really easy
                             to scream "RACIST!" and dismiss someone entirely
                             without responding.  It shows "poor mental
                             hygiene".  It's always much harder to actually
                             respond intelligently, especially when you're not.
                             I'm done feeding you cookies, troll.
2002/6/18 [Science/Physics, Academia/Berkeley/CSUA/Motd] UID:25134 Activity:high
6/17    motd opinion poll:
        CMOS will be replaced by some other technology for the
        majority of personal computing applications

        next 5 years
        next 10 years      ..
        next 50 years
        next 100 years
        \_ Oh my god no!  Don't take my CMOS!  I think a poll on sibling incest
           would have been more interesting.  This is so nerdy.
           \_ i have 50 inflation-adjusted dollars ridding on this
           \_ i have 50 inflation-adjusted dollars ridding [sp inc] on this
              a nerd.
              in a bet with a co-worker. but then, i am indeed
              a nerd.  [motd spelling bitch was here]
                        \_ ok, jerkoff, you remember how to spell and i'll
                           remember how MOSFETs work and how to make them,
                           and we'll see which is a more usefull skill.
                           \_ it's not possible to know both device physics
                              and spelling?  shrug.  personally, i'm rooting
                              for soi, but i've seen simple cmos do some
                              amazing things i'd never have thought possible,
                              so no bet.  heh.  just flashed back to asking
                              dillon in the old fish bowl what that cmos thing
                              was about for my cs150 project.
                                \_ This narrows down who you are a lot.
                                   Why not just sign your name? -PM
                                   \_ why?  there are a few of us around
                                      who go that far back, and it's not
                                      obvious who i am unless you actually
                                      know us.  if it helps, i think i have
                                      the oldest file on soda.
                                      \_ damn!  defron has older files.  fine,
                                         oldest file amongst guys who still use
                                         \_ nope, as it turns out donald does.
                                            \_ Actually, root does (unless
                                               you count files with timestamp
                                               0 [a la 12/31/1969 16:00 PST].
                                               See /csua/archive/lib/Fun/song.
                                \_ [deleted for lack of sense of humor]
                           \_ Yet another ESL drone who thinks he has unique
                              skills....  "They can't fire me!  I'm valuable!"
                              Famous last words.
2002/5/3-5 [Science/Physics] UID:24689 Activity:moderate
5/2     hi.  does anybody out there know about how physics postdocs do in
        doctoral programs for finance, accounting, etc?  any personal
        stories, cautionary tales, etc, please write to me, hahnak.
        thanks in advance
        \_ hi.
        \_ if you go from physics to finance with a phd from a name-brand
           school, no post-doc is necessary, and you certainly don't
           want to waste your time with some idiotic finance grad program.
           for reasons that are perhaps a litle odd, there are lots of
           finance type employers on wall street desperately trying to
           recruit physics phds all the time.  i am a second year grad student
           in applied physics, and i periodically get solicited by these
           people even though i am years from graduating.  lot's of people
           seem to go this route, but no one i know personally because
           it tends to be the particle theorist wannabe loosers, and i'm
           in condensed matter experiment.  from what i've heard, expect
           to make less than the *real* finance poeple, to work long
           hours, to hate your boss, and to lead a pointless existence
           in the most expensive city in the US(nyc).
           in the most expensive city in the US(nyc). huh.  this reply
           was intended as a troll(although i honestly believe everything i
           said.) apparently this is the wrong crowd.
           \_ What part of physics studies is applicable in the financial
                \_ being able to think and create mathematical models.
                   \_ yeah, and also an understanding of the study
                      of random processes.
2002/4/27-28 [Science/Physics] UID:24617 Activity:nil
4/26    [stupid physics troll nuked AGAIN]
        \_ die thread, die.
2002/3/25-26 [Science/Physics] UID:24219 Activity:moderate
        \_ Shrek was a highly inferior film.  Dreamworks is a highly inferior
           group.  The Oscars are highly inferior as well, but I won't go into
           any of these as my head aches too much already.
           \_ Compared to Monsters Inc. and (gasp) Jimmy Neutron?
              \_ Yes.  Especially compared to Monsters, Inc.
              \_ Indeed.  Monster's Inc. was immensely superior.
        \_ ??? Power and Data Interface??
           \_ i think they mean PDI-Dreamworks
        \_ Maybe next year, John.
2002/2/12 [Academia/GradSchool, Science/Physics] UID:23839 Activity:very high
2/11    What is the $ of a typical grad school and how much TA/RA money does
        one expect to get relative to the tuition and the cost of living?
                                -still waiting for grad schools to reply
        \_ in physics it's full tuition paid plus from 16 to 21 thousand a year
           \_ Because we need future weapon designers.
              \_ yeah, i belive there are three reasons: we built the bomb
                 and there is not enough money in physics to justify
                 students taking large debt in school and we provicde
                 comparitivly cheap labor.  fourty grand total a year including
                 tuition is still pretty cheap for what we do. and yes,
                 we design military technology of tomorow.
                 \_ a pacifist physics phd friend of mine thinks shes working
                    on detection equipment for nuclear treaty compliance of
                    some sort but it sounded like a better use was sticking it
                    on an interceptor so it can differentiate between real
                    and dummy/fake warheads....  I didn't break it to her.  She
                    seemed so happy thinking she was using physics for peace.
        \_ I dunno about other schools.  If you've got a TA or RA full-time
           position, you're going to get half/full ride on fees, +
           about 18k to maintain yourself.  This is in EECS/Berkeley.
           Half ride for a TA, full for an RA, and half ride leaves about 2k
           per semester in fees.  --PeterM
           \_ What's a "full-time TA/RA"? 20 hr/wk? 40 hr/wk? -alexf
              \_ Nominally 20 hr/wk.  However, some TA jobs are quite
                 a lot heavier.  If you TA, pick your assignment carefully.
                 Half-time is 10hr/wk.  --PeterM
        \_ did you apply for any fellowships? those pay tuition+books+
           somewhere around 20k a year, for about three years, on average...
                \_ no, I did not apply to any because both of my GPA and GRE
                   are lower than yours. I don't think that I'll qualify
                        \_ You never know what fellowship might apply.
                           There might be a fellowship targeted at anonymous
                           motd stalkers!  --PeterM
2001/9/16 [Science/GlobalWarming, Science/Physics] UID:22484 Activity:nil
9/15    Anyone interested in a small nuclear reactor?
2001/8/7 [Science/Physics, Finance/Investment] UID:22029 Activity:insanely high
8/6     Are there any bioE majors on soda?  My friend's advisor (Bryan Jones,
        for those of you who are familiar) told her she had to take 8 tech
        courses her sophomore year.  I'm of the opinion that this is only going
        to screw her and her gpa over.  Thoughts?
           \_ screw her?
              \_ [ the joke got old months ago. deleted ]
        \_ I have a degree in Biophysics and tried to take 7 tech courses my
           junior year (including OChem and QM at the same time). Yes, it
           screwed up my gpa and probably kept me out of med school. -ausman
        \_ I took Physics 137A, Physics 105, Physics 112, Math 104, Math
           110, Math 113, and Economics 101AB my junior year. I didn't do
           so hot. Then again, the alternative is to stay in school forever
           while you take the hard classes one at a time. If she doesn't
           take the 8 classes then what are her options? --dim
        \_ Yes, it's possible, and sometimes even the right thing to do. I've
           had semesters when I've taken 4 techs, and without regrets. In most
           cases, for most people, it's probably NOT the right thing to do,
           given risk to GPA/academic standing, stress level, lack of free
           time, etc. The best thing you can tell your friend is probably to
           get a second opinion of some other faculty in the department, and/or
           from other undergrads who have taken the particular techs she's
           being pushed into, and then think for herself. -alexf
        \_ Tech courses were fun while I was at Berkeley.  Four at a time
           is even better.  If she fears them, maybe it's not for her.
           For example, I feared four upper division CS courses.  That was
           not for me, but if she's got a knack --
           \_ Math power pack: 104, 113, 110, 128A.  Delicious, nutritious,
              and educationally stimulating.
           \_ in my experience, Bryan Jones is nearly always wrong.  She should
              plot out her academic future with help from sympathetic profs or
              better yet upperclassmen friends.  Best of luck and let us know
              if she actually ends up needing to take 8 tech courses.
        \_ At last something I really can help with. BioE is in the eng. science
           cluster of majors. They are very much catch as catch can for advisors
           and the advising I received was poor verging on criminal. I made
           numerous mistakes in class choices, some of which I am still dealing
           with as a result. By all means, get a second opinion. Unless your
           friend is a whiz kid who is comfortable with the load, find a way
           to balance out the 8 classes over time. It's better to just be in
           school longer. Really. It is. Feel free to email me if you want to
           talk about it more.
           -- ulysses (BioE for first year, then grad. in Env Eng Sci, 1995)
        \_ My brother is doing BioE and he seemed to be able to handle that
           load just fine while keeping his GPA above 3.
           When I was an undergrad I took 6 technicals 2nd year and 8 techs
           junior year and it wasn't too bad. I even graduated above 3.
           \_ I don't know what the case is outside of BioE and my own major, but
              we needed a 3.5 or better to be seriously considered for graduate
              school - and it is assumed you are going to grad school if you
              are in an eng. sci. major. Also, don't forget that for BioE two
              of those classes are the biochem sequence where you are head to
              head with bloodthirsty pre-meds, many of whom are taking only that
              one course or maybe one other. -- ulysses
        \_ Are all ucb students this wimpy now, or is it just the bioE majors?
           I was eecs, and I've never taken less than 15 units of technical
           classes a semester.
           \_ When I was a student, we walked uphill, both ways, in the rain.
              \_ Pansy.  We walked through blinding snow, and we didn't
                 have schools.  We had treebark!  We would sit down on
                 treebark and take notes on treebark, and we liked it!  We
                 loved it.
2001/6/14-15 [Science/Physics, Computer/Theory] UID:21510 Activity:kinda low
6/13    Long lived quantum entanglement of 2 macroscopic objects has been
        Food for thought.  -- ilyas
        \_ Thaumaturgy scheduled for teaching at UCB in year 2011
           \_ We will teleport your gonads into the icy environs of deep space!
        \_ Eh. Note that this has only been submitted to Nature and thus hasn't
           passed peer review yet. The results they claim do sound impressive,
           but I'm holding off on the party for time being (and I'm not nearly
           enough of a physicist to evaluate actual procedure used and the
           consequent claims' validity). -alexf
        \_ .5 milli seconds is longlived? not useful for engineers yet..
           \_ for quantum computation, that is wuite long.  If you could
              get that kind of lifetime for a 10,000 qubit system,
              you would have a real quantum computer.
              \_ Even 200-300 qubits at that speed should kick the crap out
                 of the current state of classical machines. -alexf
        \_ 0.5 ms is long for all scientist/engineers.
           \_ that's not what their sexual partners think.
2001/4/28-29 [Science/Physics] UID:21128 Activity:high
4/27    Anyone here took phil 135 metaphysics?  What the hell is metaphysics?
        (at berkeley)
        \_ Its the physics of the mind body and the soul.
           Its the most important subject you can study for
           the betterment of your life and all of humanity.
           - Deepak Chopra
        \_ Its the physics of the mind body and the soul. - Deepak Chopra
        \_ Fake physics
           \- if a bookstore has a sectional called "metaphysics" you know it
           is a bad bookstore. if the "metaphysics" section is bigger than the
           philosophy and physics sections put together, then it is a really
           bad bookstore. For a long answer to your question (that is not too
           hard to read) see I. Kant:  Prologomena to Every Future Metaphysics
           That May Be Presented as a Science. For an even longer answer,
           Critique of Pure Reason ... "Hume took as his starting point a
           single but important conception of metaphysics ... the connection
           of cause and effect ... metaphysics consists, then, of a priori
           knowlege ... to distinguish from pure mathematics, pure philos
           knowledge ... i must refer the reader to the Critique of Pure
           Reason, where the distinction between the two ways of using reason
           are clearly and adequately presented." ok tnx. --Kant, Prologomena.
           p.s. Kant is 277yrs and 1 week old today.
        \_ I took it.  Meta physics is a uber class of philosophy dealing
           particularly with being, reality, mind, knowledge. It is
           inclusive of sub branches of philosophy as epistimology,
           ontology, theory of knowledge, philosophy of mind, etc.
           Generally will asks questions such as:  what is the nature
           of being? What is truth? What does it mean to exist? What
           is the relation of cause and effect?  etc.  Very interesting
           topics but if you're not use to philosophy classes you might
           be asking for too much.  If you're not a philosophy major
           don't be surprised if you get a C (or less) on your first paper.
           \_ i used to be a philosophy major (among other things) i had
              history of philosophy (heraclitus -> sartre); philosophy 132.
              is this enough?
              \_ history of philosophy is not philosophy proper, it's
                 history.  So I don't know if it's enough for 135, but
                 definitely avoid courses in philo on Kant and Heidegger
                 unless you really really want to read a lot of difficult
                 \_ I'm making your burger. -philo major
                    \_ So how was that book on Kant? And I will have
                       a fries and a milkshake with that. Thanks.
                 \_ Do you know why the called him Kant? It was short
                    for Stupid Philospher, Can't Get a Job!
                    \_ Hey!  I love Kant!  -!psb
                        \_ I wonder if Nick "don't go into CS for the money"
                           Weaver is one of the morons commenting above. -tom
              \_ camus can do, but sartre is smartre!
2001/4/20 [Science/Physics] UID:21029 Activity:very high
4/19    Say you have a long pole of some hard substance. If you push on
        the end, how soon does the other end move? Is there some ripple
        effect at the atomic level that propagates at some speed? If so,
        is this "c"?
        \_ Are you trying to figure out if you can transmit information faster
           than the speed of light (say, a giant pole to another planet)? I
           think mechanical energy transfers through a metal pole similarly
           to how sound would through air.
        \_ if you push on my pole, baby, i'll move faster than c
        \_ Are you trying to figure out if you can transmit information
           faster than the speed of light (say, a giant pole to another
           planet)? I think mechanical energy transfers through a metal
           pole similarly to how sound would through air.
                \_ Yes, the sound speed in the metal.  You're propagating
                   compression/tension waves, more or less.  Not only
                   would it be < c, it would be WAY less than c.
        \_ Since the bonds that hold the hard substance together are
           electromagnetic, the maximum speed to transfer an impulse from one
           end to the other would be the speed of propogation of an EM wave.
           So, yes, c is the limit.
           \_ Sure, c is "the limit", but your understanding is poor.
              Consider hammering a metal train track with a sledghammer.
              How long would it take to "notice" that the rail was hammered?
              How long would it take your friend "joe" down the track
              to hear that it had been hammered?  The distance to joe
              divided by the speed of sound in metal, that's how long.
              Moving it is essentially the same as hammering it.  It's
              just a very large amplitude, slow frequency sound impulse.
              What is the speed of sound in steel?  Very high, but nothing
              like c.
              \_ hm, makes sense, thanks. so it seems the speed of sound in
                 diamond is around 10^4 m/sec. okay, there goes my plan
                 to revolutionize fiber optics. (fiber sonics?)
                 \_ What's the speed of light inside fiber optic cables then?
                    \_ approximately c/1.52.  Index of refraction of glass
                       is 1.52 ( vacuum speed / material speed ) --jon
                       \_ Then how is using diamond going to beat fiber optics?
                             \_ damn. as I suspected, people are already working
                                on everything. i was basically thinking about
                                what they call wavelength division multiplexing.
                                those fuckers.
                          \_ I said "there goes my plan." Although, something
                             else occured to me. But this one might be the
                             million dollar idea. I'm sure you buy that huh?
                             Hmm. --original poster
                             \_ hey, don't feel bad.  there are plenty
                             of very succesful internet companies that have
                             made all of their money via the reciprocal
                             motion of rigid rods.  it just has to be the
                             right rod.
                                \_ The one they shoved up your ass as
                                   they took all your money in exchange
                                   for worthless options.
                             \_ Oops, never mind.
                             \_ damn. as I suspected, people are already
                                 working n everything. i was basically
                                thinking about what they call wavelength
                                division multiplexing. those fuckers.
                                \_ take a look at negative ir.
        \_ I think Einstein said nothing, not even information itself, can
           travel faster than c.  But I think some quantum mechanics guys
           said otherwise.  They said for certain pair of particles
           far apart, if they do something to one particle, the other particle
           responses in some way in a time shorter than light requires to
           travel between the two.  It's something like that, I don't know
           \_ Feynman explained this to me once, and I thought I understood
              it at the time, but afterwards, I realized I had no idea what
              he was talking about. Here it is:
              \_ You knew/met Feynman?!? Lucky dog.
           \_ You are talking about "spooky action at a distance". The problem
              with this analysis is that it forgets to take into account the
              wave modes of the particles. There was a paper discussing this
              last year in phy. letters or something.
           \_ You can't use this to transmit a message, though.  Imagine
              that you and I have two coins that are mystically linked, so
              that when they are flipped, they both come up the same way.
              We both flip the coins a bunch of times, and -- wow! -- the
              sequence of heads and tails that arises is the same for us
              both.  But we can't know this until we get together and compare
              notes.  Until then, it just looks like a bunch of random
              coin flips.  This quantum thing is like that.
              \_ But you're assuming that "flipping a coin" is random.
                 It's not. If you train yourself, you can consistently flip
                 quarters to come up the same side pretty much every time.
2000/5/5-7 [Science/Physics] UID:18182 Activity:high
4/35    Does aluminum foil or white sheets of paper reflect more light, if the
        direction of the reflected light is not important?  -- yuen
        \_ Are you talking about strictly visible light?  IR?  UV?
           \_ I'm interested in daylight (5500K).  -- yuen
        \_Christ, get a clue. Get a strong light source and a dark wall.
          Hold up a sheet of paper and a sheet of tin foil that are the
          same size. Measure the size of the square of reflected light.
          Estimate the intensity in a small area, and multiply by the
          entire area of the reflected light. Very simple. Any fourth
          grader could do it.
        \_ WAG (wild-ass-guess): Metal over paper any day.  However, to test,
           put some paper and aluminum foil out in the sun for a few hours.  See
           which is warmer.
           \_ This is incorrect advice.  Just because something 'feels' warmer
              does not mean it is.  For instance, titanium watches feel
              neutral on your hand, but steel watches feel cold (when you first
              put them on).  However, both are at the same (room) temperature.
              The subjective sensation of coldness can often be caused by the
              _rate_ of heat transfer, not the actual temperature.  In the case
              of watches, steel has a greater heat transfer rate, so it absorbs
              more heat from the human skin in the same amount of time than
              titanium.  These rapid temperature changes is what the human
              skin's thermal receptors are most sensitive to.
                -- motd physics god
              \_ i knew this, too. - motd physics weenie
           \_ as tom pointed out on wall, this won't work for another
              good reason: paper transmits light, aluminum doesn't.
              so you need to check the temperature as well as the trasmitted
              light. -ali
        \_ take both into a dark room and flash a flashlight at them...
           have it reflect against a wall.  seems like a logical
           test *shrug*
           \_ this doesn't take into consideration the fact that aluminum
              is specular and paper diffuse. the pattern on the wall will
              look different. you need to add the TOTAL amount of energy
        \_ Who cares?
              reflected everywhere on the wall, not just look at the intensity
              at one point on the wall. the only good quick way i can think
              of this is to point a thin laser at the paper, measure the
              reflected intensity at some angle, and scale to the rest of the
              hemisphere, and do the same with aluminum, but measure the
              reflected intensity near the surface normal. -ali
        \_ The two sides of my foil differ. Which side you talking 'bout?

        \_ If you want to grow pot, don't use aluminum foil. _Very_ hard to keep
         flat enough to reflect light.
        \_ I think of it this way - mirrors are made of melted metal (I don't
           know which) poured over the back of glass. Mirrors are *very*
           reflective. I believe that part of the reason is that the glass
           holds the metal flat. Put paper on the back of glass, and you
           don't get anything particularly reflective. If my life depended
           on it, I'd choose aluminum.
2000/1/8-10 [Science/Physics] UID:17195 Activity:nil
1/8     Need 2 units?  IB 98/198 DeCal course; Science in Science Fiction.
        We watch movies, then have professors from the IB, MCB, Physics, Astro,
        and CS departments tell us about the real science that inspired it.
        Check out for
        more info.                      -sofia
        \_ Deep.
2000/1/1 [Science/GlobalWarming, Science/Physics] UID:17139 Activity:high
12/31   Was the Y2K bug that big of a deal? Looks like its effects are
        small and sporadic, so far. Would it have made that much of a
        difference in terms of power/phones shutting off, etc, if people
        didn't try to make everything compliant?
        \_ It isn't over yet, fool.  The U.S. hasn't rolled into Y2k yet! How
           can you be so naive?  The Rapture is coming!
           \_ Wrong. Guam was one of the first to enter 2000.
                \_ Guam is a tiny speck of nothing territory.  It isn't a part
                   of the United _States_.  We _own_ it.  They also don't have
                   any nuclear power plants.  So young, so foolish.
        \_ "Better safe than sorry" -- more true today than at any time in
           human history.
1999/12/31-2000/1/1 [Science/Physics] UID:17135 Activity:moderate
12/31   Any recommendation on a photography book for someone who happens to
        have a solid background in physics?
        \_ What does physics have to do with the art of photography?  Or
           are you looking for something that explains lenses and film?
           \_ Not one that explains how films and lenses work but how to
                apply them to achieve the expected effects with scientific
                \_ I doubt your vaunted physics background will help you.
        \_ Are aeronautic Phds good test pilots? No. Get a fuckin life peterm
1999/8/13 [Science/Physics] UID:16305 Activity:high
8/12    Is it possible to take 37 units in one semester?
        \_ With approval you are allowed to try anything.  You won't pass
           37 units unless it's mostly crap courses.
        \_ Not sure if it's physically possible, but you have to get Dean's
           approval to go past 20 or 21.
           \_ It's possible if you need them for graduation; a friend of
              mine did 38 his last semester. -calbear
              \_ Are you sure he didn't attempt to slit his own throat?
                 \_ Pretty sure.  He seems happy to me.  He's currently
                    involved in a start-up for a couple of months before
                    leaving to New York to work as an attorney in mergers
                    and acquistions. -calbear
                    \_ Wait a second. Attorney? That explains everything.
                       His units were probably mostly in the humanities
                       and social sciences. I'd like to see someone take
                       38 units of science or engineering. --dim
                       \_ Everyone's different. I would die with that many
                          units of humanities, cuz I can't write worth shit
                          term papers.
                          \_ But clearly you could easily do 38 units
                             of science and engineering classes? Come on.
                             All you're admitting to is being a moron that
                             can't write. I submit that it would be
                             almost *impossible* for an undergrad to take 38
                             units of science and engineering courses
                             and pass with grades of C or better in each.
                             The reason? Problem sets and labs. Papers
                             are not near as time-consuming, ignoring
                             whether or not they are "easier". --dim
                                \- i think if you are one of these amazing
                        people [there were classes it took me 20hrs/week to
                        to the homework, while people i knew took 40 minutes,
                        but they also got 3 digit scores on the putnam ...
                        and didnt ever bring a pen or pencil or paper to
                        class to take notes] it can done. for a normal person
                        this would be impossible. i took 5 problem set classes
                        plus one political science class one semester and i
                        basically sleeped under 30hrs a week for the whole
                        semeser and only went home every few days [it was
                        also my highest gpa semester, but i was in a black
                        mood the whole time]. i think you couldnt physically
                        do the reading for 7 heavy reading classes, however
                        for many of those classes you can do quite well in
                        without doing much of the reading. --psb
                        \_ I guess I didn't have it as bad, but it was still
                           a pretty horrible experience for me.  CS 164 with
                           Hilfinger, CS 184 with Sequin, EE 122, Polisci 2,
                           and project partners that were either lazy,
                           incompetent, or just ditched me half way through
                           a project.  I didn't sleep much that semester but
                           boy did I learn a lesson about choosing classes.
                \_ I'm currently in my 5th year of EECS however
                   there was a semester in which I thought i should do
                   philosophy instead, so I took 4 philosophy courses
                   philos 12(foundations of logic), philos 25a(ancient),
                   philos 133 (language), philos 132 (mind)
                   and cs61c. This was all without approval from my
                   faculty advisor. Anyways to make a long story short,
                   I didn't do jack shit in any of the philosophy courses
                   and got 4 A's and a B. You can guess where the B came from.
                   I spent roughly 30 hours for the entire semester outside
                   of class for each philosophy course.
                   Compare that with two weeks of an upper div CS or EE class.
                   I now think that any dumbass can get a Berkeley degree,
                   but which kind of degree is what counts. I spend
                   15 hrs a week outside of class for each EE/CS course.
                        \-try taking h104, h113, 115, physics 137a+105.
                        one problem set due on wed, 2 on thr, 2 on fri.
                        you are too wiped out to do anything all weekend.
                        you learn a lot more about fear and trmbling that way
                        than reading kierkegaard.
                        \_ go go math power pack! -- ilyas
                       \_ Of course i don't mean to diss physics. as an
                          eecs major i respect math and physics
                          as more difficult, and realize it requires
                          much more thought. i couldn't do most upper div math.
                          and i know history is alot of work. im just saying
                          generally, that most non-science (anthro, poli sci,
                          bus, econ, etc.) don't know the meaning of blood
                          sweat and tears. i do think english and history
                          are siginificantly harder than other humanities
                          but getting through
                          means you are a bad mo-fo.
        \_ Just to let you all know, the first two years of medical school
           on most campuses is about 30 units or so, and it wasn't that bad.
           A lot of work in amount, but not that hard conceptually. -drex
1999/6/9-12 [Science/GlobalWarming, Science/Physics] UID:15931 Activity:kinda low
6/9     Yet another Nobel prize for Berkeley:
        \_ nobel prize, huh?  possibly, but unlikely i think.
        \_ wel gee, I could get a nobel prize too, if I had an
           umpty-billion-dollar  cyclotron, and free license to play around
              as I see fit.
           \_ D00D!!!1!!!!  CYKLOTR0NS R 4 PUSS13Z!!!!1!!!1!!!!!  ALL U N33D
              2 G3T A N0B3L PR13Z 1Z A TRUSTY C=64 ---- 1F UR *DAMN G00D*!!1!
                \_ I had a cyclotron once, but then the aliens came and took
                   it away just as I was about to discover The Truth.
                   \_ That's right -- and they gave it to *me*, because they
                      liked me better!  Nyah!
        \_ Go Bears
1998/8/27 [Science/Physics] UID:14519 Activity:moderate
8/26    Recommendations for a 1 unit (science unit only) EECS class I can
        take so I'll graduate?  --dbushong
        \_ If you're a CS person, CS9?. If you're a science person, CS9X.
           \_ I know two seniors taking 9C for a science unit.
        \_ How about physics 111?
        \_ EECS 39X, "Potstickers and the PDP-10: Brian Harvey, A Life"
           \_ Comp Lit 39M, "The soda motd and its discontents"
1998/8/25 [Science/Physics] UID:14502 Activity:high
8/23    i have a friend coming from out of town next week.  hes a
        physicist and asked me to take him to what he calls a
        'science bookstore'.  ive never heard of such a thing, but
        would like to go to one myself.  he is interested in
        buying physics books.  is there a 'science bookstore' in
        the bay area?  im hoping to take him to a place other
        than the asuc...  [his work is in condensed matter theory,
        if that helps]                                  -hahnak
        \_ Well, he would probably like the physics and related
           sections of the campus bookstores.  Also, Cody's is
           fairly respectable though somewhat random the last
           time I looked.
        \_ best place i've been to is University Bookstore on University
           Ave and High St in downtown Palo Alto. -ali
        \_ ObStacy's for just sheer variety. --jon
        \-Cody's has a pretty good selection of Springers. Occasionally
        they have really good prices during their "Silver Sale" [silver =
        physics, yellow = math]. ASUC actually has reasonable number of books
        on condensed matter physics. [reasonable here is 3 instead of 0].
        stacy's and [stanford] univeristy books are best bet for south bay.
        [dont bother with kepler's ... it is an overrated bookstore ... they
        are just good for fiction and "events"]. --psb
        \_ There's also a Stacy's in SF (on Market, a block from the
           Montgomery BART).  Black Oaks is also worth checking out.
           There are some real finds there.
1998/4/13 [Science/GlobalWarming, Science/Physics] UID:13945 Activity:nil
4/11    Sandia said a few days ago that they think they can get high-yield
        nuclear fusion in a bit over a decade.  Does anyone believe them or
        have more information?  If it's true, it would be a Good Thing.
        \_  I'd love to read this.  Give me a ref?  I'll follow up
            with my opinion on it...  --PeterM
                \_ It is capital Z, yet htm extension. Weird.   -muchandr
                \-i was talking about commercial fusion power with a friend
        of the family who works on fusion at LLL maybe 1.5 yrs ago, and he
        said the press that implied it was "right around the corner, early
        21st cent" were way off. "not in this decade". --psb
        \_ Check out latest issue of Discover.  There's a proposal of using
           proton-boron reaction instead of conventional deuterium.  -- cm1ee
           \_ Saw the origional of that in Science a few months ago.  Mostly
                an "on paper" proposal.  Nothing much more than that.
2017/09/20 [General] UID:1000 Activity:popular
Berkeley CSUA MOTD:Science:Physics: