time stops at lightspeed... at lightspeed, is time travel really possible? the wonders of quantum physics...?
156415
If Astral travel and out of body experiences are reality for some people , than Physics is exploring the experiences of our old sages.
945559
Relativistic time travel is possible. Time passes more slowly for an observer who is in motion relative to one that is at rest. The next trick is to define which is which, which is why Einstein won the Nobel Prize (although it actually wasn't for relativity, but that's another question).
189139
Do some research on a gentleman by the name of Kip Thorne, and he will explain about the possibility of time travel through use of a wormhole. Think of a universe as a sheet of paper. bend it so that one end touches the other, the wormhole would connect the two opposite ends of the paper by the shorter distance between the ends of the paper, you follow? This is what a wormhole does. Now according to Einstein's Theory of Relativity, time will slow as you move closer to the speed of light, and will stop entirely once you reach that speed. SO, if we have two ends of a wormhole, and send one off into deep space at light speed, for several years, then when it returns in, let's say, the year 2020, then we would be able to jump in the end of the wormhole that stayed here and come out the other end in the year 2006. Time travel into the past would be highly unlikely due to the fact that in the past (like prehistoric times), neither you nor the time machine existed. Mr. Thorne also has several possiblities when entering a wormhole. 1) soon as you enter one end of a wormhole, you instantly pop out the other. 2) there is a slight delay between the time you enter and the time you exit. 3) you exit the wormhole before you even enter it. Wild huh? the only problem is that wormholes are unpredictable, they open and close all the time, so one may get crushed in it while attempting to travel to the past. However, they have recently found a way of transporting information FASTER than the speed of light. Accordind to Einstein's ToR, that would cause a reverse in time...so who knows...?
855043
It's all theory, we don't know if (something) can exceed the speed of light. I would argue that time would be void at that moment, but again it's my theory. Interesting thought though.
137522
NOVA: Do you think that backwards time travel will ever be possible?\n\n\nSagan: Such questions are purely a matter of evidence, and if the evidence is inconsistent or insufficient, then we withhold judgment until there is better evidence. Right now we're in one of those classic, wonderfully evocative moments in science when we don't know, when there are those on both sides of the debate, and when what is at stake is very mystifying and very profound. \n\nIf we could travel into the past, it's mind-boggling what would be possible. For one thing, history would become an experimental science, which it certainly isn't today. The possible insights into our own past and nature and origins would be dazzling. For another, we would be facing the deep paradoxes of interfering with the scheme of causality that has led to our own time and ourselves. I have no idea whether it's possible, but it's certainly worth exploring.\n\nNOVA: Would you like it to be possible?\n\n \nSagan: I have mixed feelings. The explorer and experimentalist in me would very much like it to be possible. But the idea that going into the past could wipe me out so that I would have never lived is somewhat disquieting.
862196
From our perception here on earth, it would appear to end at where space and time begins.  Remember that because the speed of light is finite, you can look at a galaxy that's 10 billion light-years away and you'll actually see it AS IT WAS 10 billion years ago....so theoretically, you can look back to the beginning of time itself.  You can't see that far away and perceive anything as it is NOW.  So the CURRENT limits are quite unknown...if there are indeed any.
1152446
Well this one is interesting.  Mathematics tell us that to move in time, one must move faster than the speed of light.  There are particles that do move that fast so it is theoretically possible.\n\nWith that having been said, I'll go back to the particles that move faster than light.  These particles cannot be seen or measured in any way that we can figure out but we know that they exist because of the reaction of other things.  ( its like the wind blowing,  you dont see it but trees and stuff react to it )\n\nOne theory suggests that if we do manage to travel back in time,  we wont be able to interact with it at all. ( I dont understand all the mechanics on this one)  But it would be like being an invisible ghost.  You could observe things and events but couldnt make actual physical contact with anything thus you couldnt change events.
1011227
Love to give you specifics, but don't know how.\n\nTheoretically, what you suggest is possible by relativistic theory. There are things called "tachyons" which are these kinds of rays which reverse time - well not "reversing" it, but definitely messing it all around.  Einstein said that nothing could accelerate to faster than speed of light without becoming infinite mass - but "...Einstein said nothing about entities already traveling at that speed or greater..." (Prote in K-Pax).  \n\nSo who knows - is it around the corner for us?  Probably not.  Is it possible?  I love this universe, so I say yes.  Keep surprising me...
990179
time is not the movement of light. \nit is only perceived that way because it's the fastest thing we know of.  \n\nIf you traveled to a planet that is 4 lightyears away in only 3 years, time has still passed, and you are still older, you have simply managed to get to that planet faster than light waves were able to.
409498
By traveling faster than the speed of light.  As velocity approaches the speed of light, time slows down.  Traveling faster than light speed then - would make you travel back in time.  Theoretically, it is possible (according to the theory of relativity) but scientifically, it doesn't seem possible.
339701
Time travel occurs everyday with everyone.  Just sitting in front of the computer now I am advancing into the future at a rate of one second per second.  What the clock on the jet experiences is time dilation.  This simply means that for the clock on the Jet, time slowed down.  In this sense it is possible to travel into the future.  This would be done by travelling at extremely high speed.  This would essentially "fast forward" you into the future, but is a one way ticket as there is no way back.\n\nTime travel as a sci-fi concept (e.g Dr Who or Back to the Future) is not possible (as currently thought), as this would mean travelling into the past as well as the future.  There are some theories that could allow time travel into both the future and the past  However, in these theories, you could not travel futher back in time than the instant the time machine was built - the reasons for which are complicated and stop paradoxes from occuring!
887827
Time travel is possible. Theoretically.  According to some theories, there are random tears in the fabric of space-time.  Some researchers have even interviewed people who have had experiences of "lost time" and weird visions such as seeing things that were there one moment but gone the next only to find out that the particular thing they had see there only exsted in a time before.  For a better explanation you should visit http://paranormal.about.com/library/weekly/aa040802a.htm
692266
It is an open question of physics, whether it is possible to travel backwards in time. No one knows yet.\nhttp://en.wikipedia.org/wiki/Time_travel\n\nBut it is known now that it is possible to travel forward in time faster than normal, you just should move around very quickly, close to the speed of light. That is called the Twin Paradox.\nhttp://en.wikipedia.org/wiki/Twin_paradox
971027
No. Einstein's theory of relativity is commonly misinterpreted by non-scientists as "proof" that time travel is possible. However, Einstein's theory states that time & perception of time travels relative to your location and your surroundings.\nThus, if you are moving in an extremely fast velocity, atoms will move much slower (time will move forward slower).\n\nThis does NOT mean that you can travel back and forth in time. Time is NOT a linear dimension in which we can move up and down. Time in the non-scientific laymen's sense is really just a "perception" and invented by people.
1186042
That's the problem. You can't go beyond the speed of light. It is the cosmic speed limit. But if you could, then you'll be able to travel through time, past and future.
51835
The physics community thinks not, but that never proved anything. The assumption is that nothing can travel faster than light. The answers are usually along the lines of, "since quantum entanglement happens instantaneously, its faster than light, but nothing can travel faster than light, so its impossible".\n\nThere may come a future theoretical structure in which lightspeed is surpassed under some circumstances, without temporal repercussions, then this assumption does not hold.\n\nI would add that I think its possible, based on an experiment described in Brian Greenes fabric of the universe that he uses to explain that its not.\n\nIts a simple extension of the two slit experiment where, immediately after the slits you use a photon doubler to create two entangled photons for each one passing through the slits. One for each slit. One photon carries on, the other is bent off at 90 degrees using a half silvered mirror and sent a long distance.\n\nIf no measurement is made on this second photon,, the other photons act as waves and you get an interference pattern. If a measurement is made, they act as particles and you get hotspots behind each slit.\n\nMy extension is that, by choosing to measure the photons that travel a long distance, you can instantaneous make the photons produce an interference pattern or not. Such a pattern would be noticable. If the split photons have travelled many light years, this pattern should be formable in a few seconds, so the message is coded in interference / non interference. Much like morse code in dots and dashes.
59515
Time travel is actually 100% possible.  You're time travelling right now, the problem is that you cannot control how to time travel.  \n\nIf you had enough fuel on a spaceship that could go at 99% the speed of light, the time on the spaceship is slowed down dramatically, this is called time dilation, which means your biological clock also slows down, slowing your aging process.  If you come back to Earth by travelling 60000 light-years, you're only 40 years older then, but the Earth and everyone on it is 60000 years older.\n\nTime travelling to the past is currently not possible.