www.csua.org/u/tvp -> news.yahoo.com/hong-kong-scientists-show-time-travel-impossible-150026913.html
The Hong Kong University of Science and Technology research team led by Du Shengwang said they had proved that a single photon, or unit of light, "obeys the traffic law of the universe". "Einstein claimed that the speed of light was the traffic law of the universe or in simple language, nothing can travel faster than light," the university said on its website. "Professor Du's study demonstrates that a single photon, the fundamental quanta of light, also obeys the traffic law of the universe just like classical EM (electromagnetic) waves." The possibility of time travel was raised 10 years ago when scientists discovered superluminal -- or faster-than-light -- propagation of optical pulses in some specific medium, the team said. It was later found to be a visual effect, but researchers thought it might still be possible for a single photon to exceed light speed. Du, however, believed Einstein was right and determined to end the debate by measuring the ultimate speed of a single photon, which had not been done before. "The study, which showed that single photons also obey the speed limit c, confirms Einstein's causality; that is, an effect cannot occur before its cause," the university said. "By showing that single photons cannot travel faster than the speed of light, our results bring a closure to the debate on the true speed of information carried by a single photon," said Du, assistant professor of physics. "Our findings will also likely have potential applications by giving scientists a better picture on the transmission of quantum information." The team's study was published in the US peer-reviewed scientific journal Physical Review Letters.
Fattmoo about an hour ago I already proved that time travel is impossible in a paper I wrote as a child. To sum it up time machines will never exist because if they could, there would never be a time without time machines. To illustrate this say in 10,000 years a time machine is invented, making it possible for traveling back in time. No one has ever came back in said time machine meaning that it never exists. Push this time frame out to infinite and if time travel is possible out that far then still there would never be a time without time travel. Critics of my theory say well what if they just choose to never come back this far in time. I say not likely given an infinite amount of time that the time machines would be in existence providing an infinite number of opportunities for time travel back to this moment in time.
Greaseman 3 hours ago Many people are confusing advances in technology and science with the laws of nature. People didn't know the earth was round because of religion and stupidity, not because there is a law of nature that says the earth is flat. We didn't think we could reach the moon because we didn't have the technology before, not because a law of nature says it is impossible to reach the moon. However, the laws of nature are telling us FTL travel is impossible, its not the lack of technology that is preventing us from reaching such speeds. Physics tells us that accelerating a massive particle to the speed of light would require infinite energy, so that right there tells you that not only is it impossible to reach the speed of light, but it is impossible to exceed it. And before you say "well physics changes, it could be wrong", the physics has been verified countless times in experiments and in nature, so this is one of those things that physicists understand extremely well.
adm 6 hours ago You don't need to study subatomic particles to prove that time travel is impossible: A scientist (forgot the name) had a simple experiment to prove this: One day he hosted a party for time travellers from the future, but did not send any invitation. In the next few days, he published the results (as well as an invitation) of the event (including the day, time, and address) in a scientific journal and a newspaper (and it was even featured on television). After the results of the no-show party became public knowledge, he declared that time travel was impossible. He said that if time travel is possible, or would become possible in the near, or far - future, then people from that time would obviously know about the event, and would do their best to attend his party. The fact that no one came to his party meant that even if people from the future knew about it, they did not have the means to go back.
Jfet Harken 6 hours ago so how does this explain quantum entanglement, where a subatomic particle can take on opposite properties of another particle even when separated by a large distance. The change on one particle happens instantly to the other, thus this change propagation is faster than light.
So who's to say that if someone from the future actually managed to travel into the past, that they actually landed on the earth? Let's say they traveled 1000 years into the past, they probably landed in the middle of space where the earth was currently miles or light years away from where it's current position in space is. So that might be a reason why we have yet to be visited by any future humans.
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