[Guest]

I'm afraid I've been neglecting my buddies from Brainden lately.. And by lately I mean for the past six months or so.

So what's up? And let's move on.

I can't remember why, since this is something that happened a while ago, but I started thinking about time travel, and whether or not it could really happen.

Now, don't hit me on the hands with a ruler if I'm not accurate, or completely wrong, but one of Einstien's theories, I believe, states that time slows down at speeds approaching that of the speed of light. Which is why astronauts might feel like they were on the moon longer than we felt like they were. (Or was it the other way around?) And when a vessel hits the speed of light, time stops completely.

Well, let's say we were to get something past the speed of light?

Okay, disclaimer here, we're all talking in theory, I want to talk about the possibility if this happened, not the possibility of a vessel reaching the speed of light.

So anyways, if you were to get this "Flying DeLorean" past the speed of light, what would happen? I feel like the equation would keep going in the same direction, and you would travel back in time.

Of course, I doubt this will ever happen for a simple reason, we haven't come across any time travelling tourists from the future, have we? (I was very pleased with myself to read that Stephen Hawking used that same reasoning to deduce that time travelling won't ever happen.)

As usual, my logic is most likely flawed to all hell.

So, let's see what you think

[unreality]

when matter is going the speed of light, it becomes pure energy because matter just cant go the speed of light (that's my understanding of it anyways). So maybe energy can go back in time. Hell if I know

I do know that the only paradox-free possibility of time travel is if a new universe branches off at the exact point that that the new matter/energy/whatever is arriving.

So it's like this:

------a-----------------b-->

let's say someone/something at point b goes back in time to point a the new timeline(s) look(s) like this:

------a-----------------b-->

	   |

	   ---------->

the two universes have the same history until point a, that's when it branches off (in the top universe, it happens as it did, but in the bottom one, the someone/something suddenly arrives and it all starts changing from there)

edit: also, going forward in time doesn't merit a new universe, it's just like disappearing and then reappearing later

Edited May 2, 2009 by unreality

[Izzy]

Unreality, I remember reading (possibly?) something about matter becoming completely distorted as it approaches the speed of light, and once it travels at the speed of it, is infinite? *shrugs*

My basic understand of this is that time travel isn't possible (evil physicists tell me so), beyond the science, because of the paradoxes it would pose. In reality (my understanding) fourth-dimensional space-time doesn't share the same multi-directional freedom as the first directions do. Like, mathematically, you can go backwards or forwards in the first three dimensions, but it doesn't work with the fourth*. I suppose you can make a time machine that takes you to the future, but *shrugs* I need to find this one post where a guy explained it fairly well.. >_>

*I don't actually know the math for this.

[Guest]

I suppose you can make a time machine that takes you to the future, but *shrugs* I need to find this one post where a guy explained it fairly well.. >_>

You wouldn't necessarily need a time machine (unless you count a space shuttle )...though it wouldn't be easy. I'm pretty sure that time travel that involves only going forward in time is actually possible. It only involves slowing time down for you, while time remains the same for everyone else, so when you return to normal time, everything has gotten ahead of you. This would most likely involve going into space (if you really want to go far, try out a black hole - not actually go through it, but close), which isn't exactly cheap and easy to do (or even realistic). I may not be completely correct on this, but that's as best I know it.

[hugemonkey]

What about looking at the problem from the other end.

Going forward in time is easy. Just sit back and let it happen. We are all moving forward in time. I guess the real trick wold be moving forward faster than everyone else. This is theoretically possible now if you were to move very fast in relation to the Earth so that time slowed down for you but outside of the Time Machine it moved normally.

Going Backward in time would be different and although I cannot describe how it could be achieved I can describe what it would look like.

Let's say that you were moving through space along a straight path in a time machine but you had not switched it on yet. You decide that you would like to switch it on and go back in time one minute. When you switch it on you would keep moving in the same direction but now you are traveling backward in time. You do this for one minute and then you switch it off and experience time normally always moving in a straight line from your point of view.

What would this look like to an outside observer?

1 minute before the moment that you activated the time machine there would be you in your time machine moving toward the point when (and where) you activated it. There would also be the future you just exiting the time travel mode but further along the line of travel.

At the moment of exiting the time travel mode an external observer would see the post-time-travel future you become two. One moving backwards and one moving forward. The original you would still be moving forward in space and time; still waiting to switch the time machine on. So now there are three of you; one moving forward in time toward the point of switching the machine on, one moving in the same direction but further along the line of travel having successfully time traveled; and one that has just appeared at the point of when the time machine was switched off to normal time moving backward in time (inside) but appearing to move backwards in and space to an outside observer. Th the observer it would be moving backwards toward the first you. At the moment that the time machine is switched on both you in the time machine and an outside observer would see you "crash" into the backward moving duplicate. If you in the time machine were to look behind you, you would see the original you moving backwards away from the now backward time traveling you as it retraced its steps. An outside observer would see both machines "crash" into each other and disappear. The post time travel you would still continue forward along the path looking backwards would see the same thing as a outside observer. As the one minute of time travel passes the time traveling you would see that post time travel you getting closer and closer moving backwards toward you until the moment that you turn the time travel switch off at that moment it would appear to disintegrate at the moment of impact. This is the same moment that I described earlier when the duplicate time machines appeared going in opposite directions except this time from the time traveler's perspective.

[Guest]

the first 3 dimensions and the fourth are linked together if you were to warp space (like the string theory or not die in a black hole) you would warp space

or just find/make a glitch

[unreality]

Unreality, I remember reading (possibly?) something about matter becoming completely distorted as it approaches the speed of light, and once it travels at the speed of it, is infinite? *shrugs*

My basic understand of this is that time travel isn't possible (evil physicists tell me so), beyond the science, because of the paradoxes it would pose. In reality (my understanding) fourth-dimensional space-time doesn't share the same multi-directional freedom as the first directions do. Like, mathematically, you can go backwards or forwards in the first three dimensions, but it doesn't work with the fourth*. I suppose you can make a time machine that takes you to the future, but *shrugs* I need to find this one post where a guy explained it fairly well.. >_>

*I don't actually know the math for this.

the only reason the 4th d (time) would be different in its restrictions is because the temporal direction is linked to causality - events earlier along the "time axis" cause events (that is, the state of space) at later points along the time axis.

The only way that time travel is possible paradox-free WITHOUT the branching universes that I was talking about in the above post (with branching universes, no paradox can possibly occur, no matter what you do) is if there is no such thing as causality... that is, if it only SEEMS like one event earlier in time causes another. If ALL events at ALL times are caused by some external timeless source or law of nature for whatever reason, then going back in time and "changing the past" wouldn't change anything because all events would be caused externally and it only appears to us that there's some sort of causality going on. I just thought of this right now so I don't know if it has any basis at all - I doubt it though. It seems unlikely

You wouldn't necessarily need a time machine (unless you count a space shuttle )...though it wouldn't be easy. I'm pretty sure that time travel that involves only going forward in time is actually possible. It only involves slowing time down for you, while time remains the same for everyone else, so when you return to normal time, everything has gotten ahead of you. This would most likely involve going into space (if you really want to go far, try out a black hole - not actually go through it, but close), which isn't exactly cheap and easy to do (or even realistic). I may not be completely correct on this, but that's as best I know it.

yeah we're constantly going forward in time. You can change your "rate" of seconds per Earth second (lol) by going different speeds. (see the Time Dilation section here, or this cool interactive thingy)

[hugemonkey]

the only reason the 4th d (time) would be different in its restrictions is because the temporal direction is linked to causality - events earlier along the "time axis" cause events (that is, the state of space) at later points along the time axis.

Causality is an illusion. Let's say that A causes B in frontward time. If you were to move backward in time it would look like B caused A. I'm not saying that A & B are not linked but the causality thing is based on how we perceive time more than anything else.

Actually our perception of time is due to the fact that we have memory.

If we knew the future but forgot it as soon as it happened and we had no memory of the past then we would perceive time backwards like Benjamin Button, and causality would be flipped but otherwise life would be normal.

Edited May 11, 2009 by hugemonkey

[Guest]

u are all sort of ignorant. when going past the speed of light, u have infinite mass and no length.

How does that work?

it doesn't! time travel is impossible and if attempted, may cause mass destruction

[Guest]

u are all sort of ignorant.

That...is a very bold statement to make, particularly in that fashion.

As far as Time Travel is concerned, that all depends entirely on how you look at things. After all, in theory, time is a dimension just like the three that we know, which means that if we could come up with a way to map it, in theory we should be able to come up with a way to travel through it. In theory, if we could travel at the speed of light then time would stop, but we can't. As far as travelling FORWARD in time, in theory if we could make everything ELSE travel at a speed approaching the speed of light, then we could move through time faster than the world around us (maybe we could just find some way to stop moving? After all, pretty much the entirety of the universe is in motion). Of course, that all requires putting a lot of faith in Einstein's thought experiments. It's exceedingly difficult (impossible?) to travel close enough to the speed of light to observe what happens at that speed, so who knows?

For our intents and purposes though, yeah, time travel is impossible. Maybe we'll discover some sort of crazy wormhole technology (or that they just exist), and that will change all of that, but it won't be in my lifetime.

[Guest]

I'm trying to remember exactly how it worked, but I remember a paradox regarding this theory.

Suppose you have a set of identical twins. Separate them at birth, send one into a ultra high speed orbit (nearing speed of light) and bring him back 21 years later. He, by the theory, would have aged much slower, while the twin would age normally.

Obviously all theory, but kind of a cool paradox of sorts, Identical twins who appear to be several years different in age.

[hugemonkey]

u are all sort of ignorant. when going past the speed of light, u have infinite mass and no length.

How does that work?

it doesn't! time travel is impossible and if attempted, may cause mass destruction

They use to think that if you ran a 5 minute mile your heart would explode. Or that breaking the sound barrier was impossible.

Read the above posts I think that this discussion is more about though experiments of the type Einstein would do than why or why not it is impossible.

It is troubling that your first post on the den is to call people ignorant.

[hugemonkey]

I'm trying to remember exactly how it worked, but I remember a paradox regarding this theory.

Suppose you have a set of identical twins. Separate them at birth, send one into a ultra high speed orbit (nearing speed of light) and bring him back 21 years later. He, by the theory, would have aged much slower, while the twin would age normally.

Obviously all theory, but kind of a cool paradox of sorts, Identical twins who appear to be several years different in age.

This is not really just theory. There was an experiment done where two super-accurate atomic clocks were synchronized and then one of them was flown around the world for a while in a plane and the other stayed on the ground. When they reunited the clock on in the plane with the one that was on the ground, the one that had been on the plane was behind the other. Not by much but it was a measurable amount. If the plane were to travel faster for a longer period of time the clocks would be off by more.

I may have the exact details wrong, but that was the gist of the experiment. I think that they have repeated this with the space shuttle and/or satellites.

[Guest]

This is not really just theory. There was an experiment done where two super-accurate atomic clocks were synchronized and then one of them was flown around the world for a while in a plane and the other stayed on the ground. When they reunited the clock on in the plane with the one that was on the ground, the one that had been on the plane was behind the other. Not by much but it was a measurable amount. If the plane were to travel faster for a longer period of time the clocks would be off by more.

I may have the exact details wrong, but that was the gist of the experiment. I think that they have repeated this with the space shuttle and/or satellites.

Ah yea, I remember that one.

[hugemonkey]

As far as Time Travel is concerned, that all depends entirely on how you look at things. After all, in theory, time is a dimension just like the three that we know, which means that if we could come up with a way to map it, in theory we should be able to come up with a way to travel through it.

We are actually aware of at least 4 dimensions. We are aware of time because our brains have a mechanism called memory. Not every thing that we interact with including some animals have this ability. This gives us the sense that we are moving through time in a particular direction.

In theory, if we could travel at the speed of light then time would stop, but we can't. As far as travelling FORWARD in time, in theory if we could make everything ELSE travel at a speed approaching the speed of light, then we could move through time faster than the world around us (maybe we could just find some way to stop moving? After all, pretty much the entirety of the universe is in motion). Of course, that all requires putting a lot of faith in Einstein's thought experiments. It's exceedingly difficult (impossible?) to travel close enough to the speed of light to observe what happens at that speed, so who knows?

Light is always measured as the same speed relative to the observer. Motion is relative to another object. Speeding up everything around you to move in the opposite direction would be exactly the same as speeding yourself up.

For our intents and purposes though, yeah, time travel is impossible. Maybe we'll discover some sort of crazy wormhole technology (or that they just exist), and that will change all of that, but it won't be in my lifetime.

Einstein's laws do negate the possibility of accelerating to the speed of light but they do not forbid the existence of particles that are already going faster than light (tachyons). Although these have never been observed they would be going backward in time. Also, they do not forbid worm holes that would allow one to "travel" without going through "space" as we know it. So that you could get from point A to point B without traveling in-between those points in space. So far all just theoretical but not forbidden.

[Guest]

I heard a paradox about this once, it went something like this: In order for Man to travel at the speed of light, he would need to keep adding more energy, which in return adds more mass, so you would need more energy, and once again more mass, and so on. So the point being you would need an infinite amount of energy to reach them speeds. Forgot what I was watching but it kinda makes sense. Unless anyone knows of an invisible,weightless, energy source. If anyone knows where this came from please share it. (or if I left some parts out).

[hugemonkey]

I heard a paradox about this once, it went something like this: In order for Man to travel at the speed of light, he would need to keep adding more energy, which in return adds more mass, so you would need more energy, and once again more mass, and so on. So the point being you would need an infinite amount of energy to reach them speeds. Forgot what I was watching but it kinda makes sense. Unless anyone knows of an invisible,weightless, energy source. If anyone knows where this came from please share it. (or if I left some parts out).

That is basically (part of) Einstein's theory of relativity. We're talking time travel here which is not the same thing as going faster than the speed of light. Read my post before yours.

[Magic_luver101]

my problem is not with going back in time it is how do you get back to the starting point of to the futer with out wating

[hugemonkey]

my problem is not with going back in time it is how do you get back to the starting point of to the futer with out wating

You could travel very fast relative to the Earth. Then time would move more quickly for you. The wait to return to the future would be less for you than it would be for every one else on Earth.