| WIKI | FAQ | Tech FAQ | |
 http://csua.com/feed/ | |
| ||||||
| 5/24 |
| 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
exactly.
\_ 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:
http://www.stardrive.org/feynman.html -ausman
\_ 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. |
| 5/24 |
|
| www.stardrive.org/feynman.html What is required to eliminate the field oscillator 3 for a delayed action at a distance between electrons 1 and 2? The Feynman equations in standard notation are in these gifs. In ordinary words these equations mean that the effective interaction for electrons 1 and 2 has the important contribution Integral from past to present of oscillator pump force from 1 and 2 multiplied by influence functional. The influence functional in the present consists of two parts. The retarded part from the past to the present, plus the advanced part from the future back to the present. Each part of the influence functional has an integrand which is the product of two factors. The first factor is sin2pif(time difference)/2pimf where m is the mass of the field oscillator 3 of frequency f Hz. Therefore, the net interaction is a kind of wavelet sin transform of trans-temporal auto-correlations and cross-correlations of the pump forces from the electrons with themselves and with each other both from past to present and from future to present. In other words, what happens now in the present to the pair of electrons depends both on their past and future co-evolution in a globally self-consistent loop of retarded and advanced causation. Feynman's Space-Time Picture of Non-Relativistic Quantum Mechanics in which the Born probability density is from the combined influence of advanced paths from the future meeting retarded paths from the past at a single event (x,t). Cramer's transactional interpretation is different from Feynman's idea. Cramer uses the same paths from the past with information running both directions forward and backward in time from (x,t). There are many typo errors in the equations in this book especially the part on Wheeler-Feynman theory. Similarly, John Gribbinsotherwise interesting pop book, Schrodingers Kittens, seems to have a serious conceptual error in regard to his description of Cramers handshake quantum version of the Wheeler-Feynman classical theory when generalized to massive particles like electrons rather than massless photons. Gribbin also mis-describes the meaning of quantum nonlocality in orthodox quantum theory by using the word aware when he says that quantum connected electrons are aware of what the other is doing in a faster-than-light way. No they are not aware because that violates Eberhards theorem. What can be said is that their simultaneous behavior in the preferred global frame of the Hubble flow of the expanding universe is synchronized forming a meaningful pattern of Jungian-type synchronicity. But observers at each electron have no local way of knowing this until much later when there is enough time for a light signal to connect the two observers. However, in post-quantum mechanics with a new hypothetical property of the universe called back-action, then quantum randomness is defeated by a controllable intelligent order and the electrons can then be aware in the sense that Gribbin wrote it. However, back-action is only a conjecture at this time that would explain both ordinary consciousness and paranormal spooky action at a distance in a unified way. Juicy quotes of Feynman given exclusively to Jagdish Mehra on the topic of immediate interest. I met Jagdish at Salams Institute in Trieste and at Prigogines Institute in Brussels 23 years ago. When you accelerate an electron it radiates energy and you have to do extra work to account for that energy. The extra force against which this work is done is called the force of radiation resistance. The origin of this force (following the work of the Dutch physicist, Hendrik Antoon Lorentz) was identified in those days as the action of the electron upon itself. The first term of this action, of the electron on itself, gave a kind of inertia (which was relativistically not quite satisfactory). But the inertia-like term was infinite for the point charge. Yet the next term in the sequence gave an energy loss rate which for a point charge agrees exactly with the rate that you get by calculating how much energy is radiated. The next sentence attributed to Feynman by Mehra seems to be missing the word not that he missed correcting in the galley proofs. So, the force of radiation resistance, which is absolutely necessary for the conservation of energy, would disappear if I said that a charge could act on itself. Feynman continued with his account of John Archibald Wheelers response to his idea First, he said, let us suppose that the return action by the charges in the absorber reaches the source by advanced waves as well as by the ordinary retarded waves of reflected light, so that the law of interaction acts backward in time, as well as forward in time. I was enough of a physicist at that time not to say, Oh, no, how can that be? For today all physicists know by studying Einstein and Bohr that sometimes an idea which looks completely paradoxical at first, if analyzed to completion in all detail and in experimental situations, may, in fact, not be paradoxical. So it did not bother me any more then it bothered Professor Wheeler to use advanced waves for the back reaction -- a solution of Maxwells equations which previously had not been physically used. I use the word back-action in a seemingly different context. In the Wheeler-Feynman classical electrodynamical theory that Feynman is describing, we have two electrons exchanging light waves. The back-reaction is from the future, but it is an advanced light wave from the absorber electron in the future back on the source electron in the past. The way I mean back-action is, on the surface, different. This electron has an actual position in space at a definite time that is a hidden-variable not found in Bohrs Copenhagen interpretation of the meaning of quantum theory. According to Bohm, the electron really is a pointlike particle which has a quantum pilot wave attached to it. This pilot wave is not to be confused with a light wave in the way Wheeler and Feynman mean. Quantum pilot waves of slower than light electrons counter-intuitively move faster than light. Furthermore, when there are two electrons that have interacted with each other, they share a common pilot wave in a six-dimensional configuration space that is more than three-dimensional ordinary space that we see and feel with our senses. Now, the pilot-wave does exert a new kind of quantum force on the electron which is qualitatively different from the classical electric and magnetic forces on the electron. Indeed, the new quantum force explains why the point electron can behave like a wave under proper conditions. But, the electron cannot emit or absorb its own quantum pilot waves, nor can it modify them in any direct way, because to do so would impose a controllable coherent order on what is believed to be an irreducible uncontrollable quantum randomness on fundamental natural processes. So this looks very different from the Wheeler-Feynman model. However, let us suppose that orthodox quantum mechanics is only an approximation to a deeper post-quantum mechanics in which the electron can directly modify the shape of its own attached pilot wave by emitting new parts and/or absorbing old parts of it. In summary, the Wheeler-Feynman back-reaction is an advanced light wave from the future absorber electron back on the emitter electron at the past moment it first emitted a retarded light wave to that absorber electron. This kind of back-reaction involves two different particles at the very minimum. In contrast, post-quantum back-action, is the reaction of the particle to the Bohm quantum force of the particles own pilot wave on it. We cannot imagine that one electron emits a quantum pilot wave to another electron which then absorbs it. What we can imagine is that both electrons modify their common pilot wave in six-dimensional configuration space. But such a modification violates orthodox quantum mechanics. Note, however, that the quantum pilot-wave of a given electron is indirectly modified only by the action of other electrons and other particles. This is what happens when both the boundary conditions on the pilot-wave are changed and when the interaction Hamiltonian is changed... |