The problem with time travel is space travel.

[Veritass]

I have always hated fiction that requires time travel as a plot mechanism.

For me, it is always the associated space travel that is the problem. Suppose for a moment that I invented a machine that would take me back one year in time (or forward, same issue). The problem is that if I wanted to be "here" in my mad scientist lab one year ago, my lab wasn't "here" one year ago. The Earth has rotated, and moved within the solar system, and the solar system within the galaxy, and the galaxy within the universe (which is expanding). So how do I accelerate through space in such a way as to go back one year and remain "here"?

On the micro level, to get from now to one year ago, at some point I have to move through a river of quantum time units. More simply explained, to get to one year ago, I have to pass through one second ago, two seconds ago, etc. As I pass through the instant of one second ago, the world/universe has shifted around me, and I am now in existence at that time occupying the same space as the matter that was there. No matter which direction the world shifts relative to me, I will be taking up the same space as the ground below me, or the air above me, or the table beside me. I'm sure that is not healthy for me, and probably will cause some weird subamotic event as my atoms try to take up the same space as other atoms.

I guess I'll have to give up on inventing time travel, and go back to work on invisibility, so I can sneak into women's locker rooms.

 

[Perfection]

The real problem is that "here twenty minutes ago" is completely reference frame dependant and thus arbitrary. You can't say it without regards to a reference frame.

 

[Sidhe]

Good point

Of course you could always time it precisely to end up in a position where the Earth was, and wormholes tend to exist between specific points in time and space. We could also assume that time and space are directly linked and so if you move back in time you move back in space accordingly. However you'd be suposing a link between the two and not just a concept regarding the two, but I believe although I could be mistaken that they do correlate in theory. Particles that move back in time to anihilate a particle moving forward, such as in high energy matter anti matter reactions do in fact appear to do this, but to be honest it's a real speculative field and the fact that anti matter has a correlative anti-time effect is even more speculative.

 

[homeyg]

The only problem is that time travel is not possible, and will never be possible.

 

[Erik Mesoy]

It appears to be possible in the forward direction, if I understand The Road To Reality correctly.

 

[Bozo Erectus]

So how do I accelerate through space in such a way as to go back one year and remain "here"?

Simple. Instead of instantly traveling through time, slow down the process. Make the speed of time travel match the speed of space travel. If it takes you E amount of time to get to point M in space, set the speed of time-travel or, C to match. Make sure you check your coordinates twice. Its easier to remember this way: E=MC2

 

[Red Stranger]

Maybe you're just passing through the gaps between the atoms.

 

[Erik Mesoy]

Also, travel faster than light and you can travel back in time. If a time machine vibrates back and forth at FTL speed within a box on the Earth's surface, gravity might very well keep it there.

 

[Masquerouge]

Just wait for the people of the future to invent a solution to your problem, and bring it to you

 

[Gladi]

Bright day
So.... your problem with fiction vehicle is that it is fictinous?

Ok if I traveled to march, my "here" now would in march vacuum of space. But why would I stop moving if I traveled in time backwards? I move in time normaly and so far have not flown off-planet...

 

[homeyg]

There's a very simple way to tell that time travel will never be invented: there are no people from the future visiting our time.

 

[Warman17]

Well that could easily be because we'll be destroyed by various reasons and what not before we invent time travel.

 

[North King]

No.

Assuming we were to use some sort of "wormhole", then it would exist simultaneously at both points in time, and there would be no intervening time. Furthermore, to go back in time, one would assume that one could go through space as well (not for nothing do they call it space-time), so the problem of ending up in a different place is hardly a problem at all.

Time travel wipes out the future timeline, and you only exist in the "past", so that would explain why no one would want to (and no one does) go back--you'd be destroying your own future.

 

[Gladi]

Time travel wipes out the future timeline, and you only exist in the "past", so that would explain why no one would want to (and no one does) go back--you'd be destroying your own future.

Now please...

 

[Bozo Erectus]

There's a very simple way to tell that time travel will never be invented: there are no people from the future visiting our time.

How do you know?

 

[North King]

Now please...

Now please what?

 

[homeyg]

How do you know?

I don't, but wouldn't it be kinda obvious if there was?

 

[Veritass]

Now please what?

Now please, SIR!

 

[Bozo Erectus]

I don't, but wouldn't it be kinda obvious if there was?

I dont know that it would be. Theyd just be people, right? Why would anyone think they were from the future?

 

[North King]

I don't, but wouldn't it be kinda obvious if there was?

Clarke's Third Law. Any technology sufficiently advanced is indistinguishable from magic. So if someone was observing the past, without having destroyed their own future (an unlikely proposition in and of itself), assuming their technology was stupendously advanced, then they would have no difficulty completely evading us.