Time Travel

[feral chile]

we have a limited perspective of what time is though.. or if it even exists

[Guest]

That's true. it hurts my head to think about what time actually is. it's one of those things you know until you actually think about.

[Guest]

Anyway, since we've never encountered time travellers, either they're banned from visiting earlier periods with scientific knowhow, or they're so careful to avoid detection that they haven't been noticed. Or our era has zero interest. Or...we have been visited, but have interpreted the future travellers as something else.

Or, most likely, time travel will never be possible.

[feral chile]

what if we could travel but not interract, or even be seen.. a kind of ethereal non-entity...

you see...

useless

[metallimuse]

Anyway, since we've never encountered time travellers, either they're banned from visiting earlier periods with scientific knowhow, or they're so careful to avoid detection that they haven't been noticed. Or our era has zero interest. Or...we have been visited, but have interpreted the future travellers as something else.

Or, most likely, time travel will never be possible.

[feral chile]

Time travel is theoretically possible though and been proven,however your perception of it is somewhat different to the actuality.

Scientists have proven that if they could build a train which rotated around the world at a certain speed for 20 years the people on board said train would emerge having only experienced a week on board,therefore they would be in their future.

[Guest]

That would be quite fun. With time travel, though, wouldn't you have to account for the earth travelling through space as well? Otherwise, you'd go back in time and the earth wouldn't be where we left it?

[Guest]

Time travel is theoretically possible though and been proven,however your perception of it is somewhat different to the actuality.

Scientists have proven that if they could build a train which rotated around the world at a certain speed for 20 years the people on board said train would emerge having only experienced a week on board,therefore they would be in their future.

[metallimuse]

if they haven't done it, then I'm not sure how it's been proven

[Guest]

Aha,bad choice of word there.What I meant was that it is scientifically accepted that its possible,we just lack the infrastructure to do so.

Edited March 15, 2013 by tonyblair

[metallimuse]

ok...so it's theoretically possible.

I'm confused as to where the 20 years has occurred?

[Guest]

Yeah,as I started my post by saying.My use of the word 'proven' is just as a mathematical equation.

I'm not sure what you mean by your question of the 20 years.

[metallimuse]

a train travels around the world at a certain speed for 20 years, but the passengers get off as if they've only been on for a week...

they've either been on the train for 20 years, or a week. The theory seems to be suggesting they've done both.

[Ed209]

Time travel is theoretically possible though and been proven,however your perception of it is somewhat different to the actuality.

Scientists have proven that if they could build a train which rotated around the world at a certain speed for 20 years the people on board said train would emerge having only experienced a week on board,therefore they would be in their future.

[Guest]

The time in the train slows down so they only experience a week but the world has moved on.It's something to do with stabalizing forces or something,I don't know.

20 years was just an arbitrary number I used,it may have been 5 or 10 or 20 I can't quite remember.

The point was technically time travel is possible but its not like the sci fi popping in and out of time style,just slowing down your experience of time to experience the future...or is that speeding up your time to experience the future lol?

Edited March 15, 2013 by tonyblair

[Ed209]

a train travels around the world at a certain speed for 20 years, but the passengers get off as if they've only been on for a week...

they've either been on the train for 20 years, or a week. The theory seems to be suggesting they've done both.

[feral chile]

Its all relative to the observer. It actually creates a paradox. There's a very common thought experiment known as the twin paradox.

Twins are separated at birth, one is launched into space in a rocket at very high speeds and is then bought back to earth. The twin on earth has aged more than the twin on the rocket. The paradox is that, relative to the twin launched into space (who is stationary in their own frame of reference) the twin on earth is the one who is moving at very high speeds so it should be them who ages less. However there's some stuff about asymmetrical accelerations which resolves it. But thats an undergraduate lecture series in itself

[Ed209]

No, moving into the past is not compatible with Einsteins theories of relativity at all. Time always flows forward (also a consequence of the second law of thermodynamics). Everything breaks down if into the past was impossible. Causality, one of core axioms of all scientific disciplines, collapses

Edited March 15, 2013 by Ed209

[Ed209]

Should add, the only way special relativity would let you still move forwards in your reference but moving into the past would require speeds in excess of the speed of light which is impossible as everything reaches singularity at the speed of light. Its a natural impenetrable barrier.

[Guest]

No, moving into the past is not compatible with Einsteins theories of relativity at all. Time always flows forward (also a consequence of the second law of thermodynamics). Everything breaks down if travelling backwards was impossible. Causality, one of core axioms of all scientific disciplines, collapses

[Guest]

Should add, the only way special relativity would let you still move forwards in your reference but moving into the past would require speeds in excess of the speed of light which is impossible as everything reaches singularity at the speed of light. Its a natural impenetrable barrier.

[feral chile]

No, moving into the past is not compatible with Einsteins theories of relativity at all. Time always flows forward (also a consequence of the second law of thermodynamics). Everything breaks down if into the past was impossible. Causality, one of core axioms of all scientific disciplines, collapses

[Ed209]

until we discover that isn't so...?

[Ed209]

One argument people have for not being able to travel back in time is why we don't see people coming back from the future. Well maybe the human race gets wiped out before we ever get the chance to build a time machine.

There's a happy friday afternoon thought.

[fred quimby]

Should add, the only way special relativity would let you still move forwards in your reference but moving into the past would require speeds in excess of the speed of light which is impossible as everything reaches singularity at the speed of light. Its a natural impenetrable barrier.