Time Travel

[GL2814]

Is time travel possible?
I've thought about this for a long time. Part of me says, "Yes." But the other part of me says, "No." Because time is not tangible.

 

[Dream]

Time travel is very possible. Einstein's theory of relativity stated that as speed increased, time slows down. So all one needs to do is to travel at a fast speed, and they will travel into the future at a rate faster than had they been stationary.

In fact, the astronauts that flew to the moon and back were 4 seconds younger than they would have been had they not taken the trip. No, it's not a substantial leap into the future, but the faster one could travel, the further along the timeline one could progress.

Just remember, time is relative.

 

[funyun]

As DreamTheater pointed out, we are all doing our own time traveling right now into the future. That's not just dramatic new age rhetoric; it's true.

 

[_Paladin_]

It is true that we are always moving forward in time, the real question is "can we move backward?"

 

[Dream]

It is true that we are always moving forward in time, the real question is "can we move backward?"

Surpassing the speed of light will send one "backwards" in time.

 

[funyun]

That's not possible, though.

 

[michabo]

It is entirely possible (ie: there are consistent descriptions) that particles do move backwards in time, but appear to us as anti-particles moving forwards in time. On some scales, the arrow of time all but disappears.

I have seen physicists say that there are devices which could be constructed which would act as a time machine, but they would almos certainly atomize anything which tried to use them. I'm not qualified to judge their arguments however, so don't wish to endorse them.

 

[Iron Sun 254]

One idea on how to build a time machine would involve creating a stable wormhole and then get send one end of the wormhole into space at near light speed and then bring it back. The idea is that one end of the wormhole will have slowed down in time so that less time has passed and thus, it will be in the past. You could then step throught the wormhole to travel to the earlier time.

 

[funyun]

It is entirely possible (ie: there are consistent descriptions) that particles do move backwards in time, but appear to us as anti-particles moving forwards in time. On some scales, the arrow of time all but disappears.

Yeah, I've read that before. It's an interesting thought.

 

[michabo]

One idea on how to build a time machine would involve creating a stable wormhole and then get send one end of the wormhole into space at near light speed and then bring it back.

So just a couple of minor technical hurdles, then?

 

[VioletAngel]

So just a couple of minor technical hurdles, then?

Yes, why not.

But I like the movie "Somewhere in Time" - and doing all by the mind. That seems to be so neat.

 

[notto]

The one issue that I've never seen resolved related to time travel is that if a physical thing is moved backward in time (by whatever means), it would also mean that the physical matter that makes it up would be duplicated.

What happens to the matter that makes up a body that moves backward in time? If that matter existed as something else previously, what happens when its form from the future is in the same frame of reference as its form from the past.

This, to me, shows that there are still some things that need to be resolved before I would accept that timetravel to the past is possible, even on a small scale or with small pieces of matter.

 

[Kripost]

The one issue that I've never seen resolved related to time travel is that if a physical thing is moved backward in time (by whatever means), it would also mean that the physical matter that makes it up would be duplicated.

What happens to the matter that makes up a body that moves backward in time? If that matter existed as something else previously, what happens when its form from the future is in the same frame of reference as its form from the past.

This, to me, shows that there are still some things that need to be resolved before I would accept that timetravel to the past is possible, even on a small scale or with small pieces of matter.

Are you refering to conservation of mass and energy?

 

[notto]

Are you refering to conservation of mass and energy?

Pretty much but it is more basic than that.

If I take an iron ball, fashioned from materials from the earth, and take that back in time to before when the ball was fashioned, do the materials that make up the ball exist in the earth or not at that time?

 

[Locrian]

They would, but the causation issue you bring up has a lot of merit in this discussion.

To try an answer to the OP:

Any method proposed to move backwards in time always involves at least one brand new physical hypothesis that has absolutely no evidence to support its existence.

That doesn't make it impossible. However, these new hypothesis proposed are always of the most extreme nature. To make a wormhole, you'd need matter with imaginary mass. Moving one of the ends seems quite unlikely. Nothing with mass can pass the speed of light barrier (whether they were slower to start with, or faster). There is no exception to that rule currently, and it is unlikely we'll find one.

Many times betting against science is a losing proposition. This limitation, however, seems likely to hold for far more than our lifetimes.

 

[pgp_protector]

In fact, the astronauts that flew to the moon and back were 4 seconds older than they would have been had they not taken the trip. No, it's not a substantial leap into the future, but the faster one could travel, the further along the timeline one could progress.

Just remember, time is relative.

If they aged slower (There clocks were moving slower than our refrence due to there speed), wouldnt they be 4 seconds younger ?

 

[Dream]

If they aged slower (There clocks were moving slower than our refrence due to there speed), wouldnt they be 4 seconds younger ?

Yes, you're right. My mistake.

 

[Alarum]

They would, but the causation issue you bring up has a lot of merit in this discussion.

To try an answer to the OP:

Any method proposed to move backwards in time always involves at least one brand new physical hypothesis that has absolutely no evidence to support its existence.

That doesn't make it impossible. However, these new hypothesis proposed are always of the most extreme nature. To make a wormhole, you'd need matter with imaginary mass. Moving one of the ends seems quite unlikely. Nothing with mass can pass the speed of light barrier (whether they were slower to start with, or faster). There is no exception to that rule currently, and it is unlikely we'll find one.

Many times betting against science is a losing proposition. This limitation, however, seems likely to hold for far more than our lifetimes.

This is not, strictly speaking, true. It has been mathematically demonstrated that a very long, very dense cylinder would generate an odd field. If you went around that cylinder very quickly you'd travel back in time. This requires NO additional physical principles - merely some wierd objects.

And you don't want to know what happens at the ends

 

[Locrian]

This is not, strictly speaking, true. It has been mathematically demonstrated that a very long, very dense cylinder would generate an odd field. If you went around that cylinder very quickly you'd travel back in time. This requires NO additional physical principles - merely some wierd objects.

Please provide a reference for this, as your description of it makes no sense (what is an "odd" field?) and I find it physically unlikely.

 

[Alarum]

It's been called various things, the sources I've found call it a Van Stokum Cylinder. I'll give you the details, and you can decide for yourself how practicle construction is. Nevertheless it takes no new physical properties, just some very odd existing ones.

http://www.wired.com/wired/archive/11.08/pwr_timetravel.html?pg=2
http://www.madsci.org/posts/archives/aug2001/996754957.As.r.html
http://yolanda3.dynalias.org/wbpage/time/travel.html

Basically a long, dense cylinder rotating at near-light speeds does some very stupid things to time as a whole.