Time travel
 

Recently I’ve watched an episode of “Into the Universe with Stephen Hawking” about time. Hawking tried to find out whether traveling in the fourth dimension – time – was possible.

At first he wanted to check if we could go back to the past. It turns out that there are plenty of microscopic quantum tunnels all around us. But even if the scientists succeeded to enlarge one of such tunnels, going back to the past would be rather impossible, mainly because of paradox. Hawking showed an example of a crazy scientist who created a tunnel which could transport him 1 minute back in time. Using this tunnel he shot himself (in other words the “present scientist” shot the “past scientist”). So, if the “past scientist” has been killed, who shot him? And this is paradox.

Next Hawking wanted to figure out whether going into the future was possible. Again, it turns out that very heavy objects make time slow down. So for people who are standing next to a pyramid in Egypt the time passes slower than for people on the desert. The difference is incredibly small. But if humans managed to build a spacecraft which could move around a black hole (which is incredibly heavy), the difference would be much bigger. So if the crew of that spacecraft spent 10 years moving around the black hole, people on Earth would be 20 years older.

Another possibility: we could build a train which would move around Earth (on its surface) almost with the speed of light. Time inside that train would pass much slower. Like: 1 year for the people on Earth and 1 week for the passengers of the train.

I know, sometimes I fail at explaining, but I tried to do it the easiest way. :P It’s hard to understand this, but I’d like to know your opinions. What do you think of Hawking’s theories? If traveling into the future was possible, would you like to go there? And why?

Thanks for reading this. :)Here’s the link to the video, if someone would like to watch it. YouTube - Pt 1 of 4 Stephen Hawking's Time Travel

If you notice any grammatical errors here, please let me know. :P

That is really interesting, I'm glad you made this thread. I can use some of the info I just read in future arguments about time travel. :cool:

I can't watch the video(s) now though, I will in the morning though.

I'm no genius, but Hawkings is and I've seen his "Into The Universe" series (well I missed that part about time travel) so I would believe anything he says XD

Before watching this I had a deep understanding of what "deep" physics dictated (not the actual mathematics but a good summary). I was already under the impression that time travel to the past was impossible (at least in theory but who knows); however, if you did manage to go back in time and shoot yourself, the timeline in a parallel universe would change rather than the universe you were currently inhabiting so no paradox would exist. I find Hawking's explanation for feedback as the reason for no time travel to the past odd because could you not send something back in time (something a few nanometers long) through a tiny microscopic wormhole (accumulating feedback at a slower rate by virtue of its size) before it collapsed (Unless of course a smaller wormhole requires less radiation to destroy in which case it would still be infeasible but I would still imagine the difference rate that a wormhole accumulates feedback would not increase in a one to one ratio to the level or radiation required to collapse it).

This is correct, because if you overcame near impossible odds to time travel into the past (which I still believe is impossible), you would be doing so in a mirror universe where your actions would have no consequences in the present universe.

However, time travel into the future, so to speak, is easy. Travelling at high speeds causes time dilation: someone travelling at near the speed of light for extended periods of time would have time go "slower" for them compared to an observer on Earth. That said, you could leave Earth at near the speed of light and age some years and return to Earth finding everyone you knew long dead. This has been experimentally proven using highly accurate atomic clocks. So by driving a car or flying in planes for your whole life, you have traveled into the future by a zillionth of a nanosecond compared to someone who did not. :D

This leaves me wondering, a lot... as with all scientific TV-programs :S Still though, I don't really see what we would gain out of this into the future time travel if the travelers would still exists in the same universe as -all others- :hmm:

I mean, the way I view time travel as is a journey minded in helping people... not just travel away for some time and then come back and like WHOAH, look! Everything is so different!... but how will we be able to travel back and tell everyone about this? <:O *great shock* Well you can't! Because there are no such thing as time travel to the past!

Meh, I've never really been comfortable with the way scientists make impossible odds hypothesis's just so they have something to ponder over :/

Hawkings is damn smart though. Even though his theories might be wrong (as some above claim) If he's wrong it will just help other to get it right :P
You can't be right without someone else being wrong.

Well, if i could go into the future, i want to go to that time where the universe ends, Must be a brilliant spectacular scene :D

Wouldn't that mean you would end too (if you were actually present inside that universe)?

lol self ownage :P

Edit:

Hmm... seems like I missread :S "Into the future"... well.... I dunno really... maybe to 2014 to see "avatar 2" :P

not really though :/ would ruin the experience to watch it right away.

Knew most of that before. You can also experience time more slowly by travelling close to the speed of light (the reason the ISV trip takes ~5.75years on it and ~6years from the perspectives of Earth and Pandora), with the rate of time dilation increasing the faster you go.

The way I see it, paradoxes have three possible solutions: Time is nonlinear, in which case it would be easy to travel back and kill your past self and you would change the future while the now-alternate you would still be in that time, time is linear so that would not be possible because if you did, you would have been unable to travel back from the future, or time self-corrects in which case if you killed your past self, you would disappear too (unlikely, but occurs in some fiction).

I can travel back in time whenever I want.

http://www.shacknews.com/images/gene...splitters3.jpg

I think eventually, seeing how much technolgy is advancing, we may be able to acheive time travel some day.

But that's a long time away. Unless some scientist makes a massive breakthrough.
Besides, we'd be studying it for years non stop before we acheive it.

Yeah, the real problem though is that we hardly understand our own universe/reality at all. Physics seems conclusive, but without the discovery of a Higg's boson, physics as we know it may be completely wrong. We don't fully understand where gravity comes from, other than Einstein's theory of relativity that explains it as the curvature of spacetime. We don't know exactly what spacetime is/why it has to be together. We don't have anything to account for about 96% of the mass in the universe so we just call it "dark" matter because we either don't understand physics correctly, or there is some matter that we can't see with most light on the spectrum. That said, major discoveries are set to occur in our lifetime that may make things like time travel not so science-fiction.

Mmmh. Got me thinking, but I think everyone has pretty much said what needs to be said. Time travel certainly is interesting. But it has very little practical application other than tourism. But it's all risky because you immediately create a mirror universe. :(

I think you all have heard this one before...."If timetravel will be possible in the future, where are all the timetravelers?"