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Ask HN: Can time travel be possible .... ever?
- stevewillows 13y agoIn theory, but we will have to pass the speed of light. That will take some time.
- krapp 13y ago>That will take some time. Sorry, but isn't that fundamentally impossible?
- wikiburner 13y agoNASA doesn't seem to think so: https://news.ycombinator.com/item?id=4534359 https://news.ycombinator.com/item?id=4534359 https://news.ycombinator.com/item?id=6238297 https://news.ycombinator.com/item?id=6238297 but the OP is talking about traveling forward through time by going near light speed, which isn't really relevant to a warp drive.
- bad_alloc 13y agoAccording to our current knowledge, it is impossible. However that knowledge may be incomplete or incorrect, both of which is very likely.
- hacknat 13y agoNo Edit The theory on time travel is incomplete. We need the unifying theory first if we are to make any assessment about General Relativity's and Special Relativity's projections about inertial frames. Special Relativity says that the fundamental laws of physics should be the same across inertial frames. I suspect that our next great Physical theory will do to this idea what Relativity did to Newtonian physics. The answer will be, "well, most of the time".
- rpedela 13y agoHasn't time dilation been verified by experiment?
- hacknat 13y agoTime dilation and time travel are two very different things.
- rpedela 13y agoWhat is the difference?
- hacknat 13y agoTime dilation is about one frame reference, let's call it "a" being simultaneous with another frame reference, "b", yet "a" experiences slower time from the perspective of "b". The classic and dramatic example is if an astronaut left earth and zipped around the galaxy several times at the speed of light. When he/she returned there perception of time would be that they experienced very little of it, while the earth would seem to them to have elapsed over a great deal of time. Is this technically time travel? From a psychological point of view it is absolutely time travel, but from a physics point of view, not really. We all experience time dilation in unnoticeable amounts during our life. Someone who is at a higher altitude than you will experience time a tiny, tiny, tiny amount slower than you. To my mind, time travel means I can go forwards and backwards in time. Time dilation, from a a psychological point of view, is about slowing one thing down relative to another. Like this: https://www.youtube.com/watch?v=AZRYyejNksk#t=9m59s https://www.youtube.com/watch?v=AZRYyejNksk#t=9m59s
- wikiburner 13y agoHaven't Einstein, Hawking, and others made statements that the only indications that time travel is impossible are the issues of time paradoxes and because we haven't seen any evidence of time travelers? I thought besides those issues, they felt it should be theoretically possible?
- hacknat 13y agoYes, and 300 years ago there was no Universal speed limit. Hawking has stated that he has no theoretical objections to time travel, but thinks that there is probably a theoretical reason for why it isn't, he just doesn't know what that might be. Let's not forget, the brightest minds in the world, self admittedly, don't know that much about how the Universe actually works. There are theoretical objections to time travel.
- rpedela 13y agoWe already can travel to the future. The faster you move through space, the slower time moves for you. So astronauts have travelled a few nanoseconds into the future because they travel so fast orbiting the earth or going to the moon. Travelling back in time is another issue. Supposedly time reverses when moving faster than the speed of light, but we don't how to do that.
- dragonwriter 13y ago> We already can travel to the future. And we're doing it all the time.
- rpedela 13y agoYes, I guess that is true. :)