Time travel

[Goatse]

Is controlled travel through the 4th dimension possible?

Also, what would stuff look like if we were 4 dimensional creatures?

[lithium]

We are 4D creatures coz we exist in four dimensions: three spatial and one temporal.

There are some experiments being undertaken in the near future looking into time travel. It'll be nothing spectacular; just seeing if signals can get to a destination before they're "supposed" to.

[Janus]

Is controlled travel through the 4th dimension possible?
Some scientists do not think so however theoretically (according to general relativity) it should be possible through a wormhole for example.

[Goatse]

But surely we're 3d in the sense that we can only travel in 3 dimensions? We have no control over the fourth.

[Janus]

We can only perceive the 3 spatial dimensions due to our binocular vision. Thus, we are 3 dimensional beings. However, if you place time as the 4th dimension then you could say that humans are able to travel through it.

[lithium]

We have very limited control over time. It can be bent and so on. Either way, we're moving through it just as we're moving through the spatial dimensions.

[Ezan]

so lithium if human beings were capable of reaching higher dimension's it is possible we could control our time? just wondered.

[ComradeRed]

Originally posted by [email protected] 10, 2007 08:42 pm
so lithium if human beings were capable of reaching higher dimension's it is possible we could control our time? just wondered.
I think it would have to be temporal rather than spatial dimensions.

Though that would not necessarily be the case. You could think of it like a plane out of all positive real numbers.

You can only go forward, and reposition the origin, but you can't translate backwards.

There have been oddities with clocks made out of quantum matter. Chiefly there is a finite positive probability that they run backwards.

We don't know how to interpret that at the moment. It could be that the clock just fucked up for a moment, or perhaps time really did run backwards? We don't know.

Frankly I think that quantum theory is not a final theory, so that quantum clock is incorrect.

But it is interesting to think about nonetheless.

[Kwisatz Haderach]

All you have to do to travel into the future is accelerate near the speed of light (time will then pass slower for you than for the rest of the universe, so, in essence, the universe zooms around you in fast-forward mode).

Travel into the past, however, is impossible - for the same reasons that faster-than-light travel is impossible. See here (http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html) and here (http://math.ucr.edu/home/baez/physics/Relativity/GR/time_travel.html).

[apathy maybe]

I once did a school project on this very topic. I'm sure the main reason I got an 'A' (the highest mark) was because the teacher didn't understand half of it.

But, woe is me, I can't remember most of what I wrote. It was something along the lines of it is probably impossible for a variety of reasons, and some interpretations of quantum theory mean that even if it was technically "possible", you wouldn't travel back in your own time line, but would instead create a new one. Or something to that effect.

Anyway, if you want a way to travel forward in time (and I mean at the same time staying the same biological age as well), that is rather simple (relatively). And funnily enough, one way has to do with relativity. Travel really fast for a period of time, and then turn around and come back. You would have aged less then what you are coming back to. Another way is to freeze yourself and then unfreeze automatically x units of time in the future.

Don't try either of these tricks at home kids! Especially not on your younger siblings! (You have to use a special freezer.)


Edit: And I just noticed that Edric O said the same thing about the speed of light as I did. Shit happens.

[Pow R. Toc H.]

I always wondered about time trave, but my thinking was that if you ever travelled back in time, wouldnt you travel back to before we figured how time travel was possible and be stuck in the past?

[redcannon]

Originally posted by Edric [email protected] 11, 2007 12:20 am
All you have to do to travel into the future is accelerate near the speed of light (time will then pass slower for you than for the rest of the universe, so, in essence, the universe zooms around you in fast-forward mode).

Travel into the past, however, is impossible - for the same reasons that faster-than-light travel is impossible. See here (http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html) and here (http://math.ucr.edu/home/baez/physics/Relativity/GR/time_travel.html).
but thats not really traveling into the future anymore than we're traveling through the future now. its merely manipulating time to make it appear slower or faster. and there is no law of physics that says that time travel, whether forward or backward, is impossible

[Janus]

but my thinking was that if you ever travelled back in time, wouldnt you travel back to before we figured how time travel was possible and be stuck in the past?
But the time traveler would still have the knowledge. A bigger problem, on the other hand, would be something like the Grandfather paradox.

[Dr. Rosenpenis]

Originally posted by [email protected] 12, 2007 05:26 pm
and there is no law of physics that says that time travel, whether forward or backward, is impossible
I don't know no scientific laws, but it's a very basic principle of our human common knowledge that time is a passing thing. It comes then it goes. Not exactly something you can access at will. Did I just state very obvious facts? Yes. But sometimes folks need to be reminded of the fact that we have absolutely no way of even imagining how time travel would work, since it's something totally nonsensical according to the nature of time or at least our relation with it. The ability to transport your body in its present state to the same place but at a different time actually does violate many laws of physics. To begin with, there is only one planet Earth and it's currently at a certain time period we know as 2007 AD. To remove your body as it exists on Earth in 2007 and place it on Earth in say, 2006 is certainly a violation of many basic scientific principles. The earth as it was in 2006 doesn't exist anymore. The Earth as it may exist in 2008 doesn't exist yet. How can you summon these nonexistent places?

My bet is that time travel will never happen. But then again you never know.

[redcannon]

Originally posted by [email protected] 12, 2007 01:19 pm

but my thinking was that if you ever travelled back in time, wouldnt you travel back to before we figured how time travel was possible and be stuck in the past?
But the time traveler would still have the knowledge. A bigger problem, on the other hand, would be something like the Grandfather paradox.
Actually, the grandfather paradox seems more like a solution to a problem then a problem itself. Thanks to causality, I can go back in time and shoot whoever the fuck I want and blowup whatever the fuck I want and it won't change a thing in the present time.

[Janus]

Thanks to causality, I can go back in time and shoot whoever the fuck I want and blowup whatever the fuck I want and it won't change a thing in the present time.
What if you shot your biological father/grandfather? That's the key point of this paradox.

[apathy maybe]

As I mentioned, according to at least one interpretation of Quantum Physics, it wouldn't matter!

Because it would just make a new time stream. History in the original time stream would continue as before, with the universe from the point the time traveller entered would split off into a new stream.

[Janus]

Right, this paradox can be solved if one takes into account multiple/parallel universes but then that would give rise to other problems in their turn.

[ComradeRed]

Originally posted by apathy [email protected] 16, 2007 02:44 pm
As I mentioned, according to at least one interpretation of Quantum Physics, it wouldn't matter!

Because it would just make a new time stream. History in the original time stream would continue as before, with the universe from the point the time traveller entered would split off into a new stream.
Yes, but it looks like that interpretation could be falsified from observations in testing semiclassical gravity.

Supposing of course you are referring to Everett's interpretation.

There are better interpretations out there though, like the Relational Quantum mechanics ;)

[chimx]

All you need to do is spin the earth backwards. I read it in superman.

[redcannon]

Originally posted by [email protected] 16, 2007 02:04 pm

Thanks to causality, I can go back in time and shoot whoever the fuck I want and blowup whatever the fuck I want and it won't change a thing in the present time.
What if you shot your biological father/grandfather? That's the key point of this paradox.
but according to causality, i would have already shot my grandfather, because in the stream of time i'd've shot him, then been born, then gone back in time. According to causality, I wouldn't be able to shoot my grandpa, at least not til after he gave birth to my dad or mom

[BurnTheOliveTree]

You can't travel backwards in time, due to simple logic. There's a finite amount of energy in the universe which cannot be altered, the addition of an extra person, or indeed and extra anything, violates that law.

The idea of the 'slow pill', which is what you see in the films, where the subject experiences time very quickly to his body going very slowly is possible. It's not time travel, as such, because there is no 'jump'. You still experience all the time you 'miss' linearly, just in a way so far removed from normal human experience that it could be perceived as a leap through time.

-Alex

[Janus]

According to causality, I wouldn't be able to shoot my grandpa, at least not til after he gave birth to my dad or mom
There is no causal law in this. This is all hypothetical: if you had killed your grandfather before your father was born how could you have been born much less been able to travel back in time and kill him. The only way around this is if you take in parallel universes,etc.

[Goatse]

Originally posted by [email protected] 16, 2007 10:04 pm

Thanks to causality, I can go back in time and shoot whoever the fuck I want and blowup whatever the fuck I want and it won't change a thing in the present time.
What if you shot your biological father/grandfather? That's the key point of this paradox.
Then you would never have been born, therefore no one would be able to shoot your grandfather, therefore everything would be normal, you would live your life exactly the same and the same events which led you to go back in time and shoot your grandfather would happen, therefore you would never have been born... basically it's impossible.

[Janus]

Then you would never have been born
Yet you did kill him. The rest of your statement makes no sense at all as you're stating that you would be both alive but never born...

[RNK]

He's saying that it would be impossible to do so, because if you were never born, who shot your father?

[apathy maybe]

Meh, if you people are going to discuss philosophy, take it to philosophy.

[Janus]

because if you were never born, who shot your father?
That's the whole point of the paradox, if you were never born since your grandfather/father was dead (by your hands), how could you have tried to go back in time? The only solution would be a multiple history/universe theory.

[redcannon]

look, its very simple. if you went back in time you would already have been born, and so it would be impossible to shoot your grandfather before he gave birth to your parent. this is why you cannot alter the present by going back in the past, because by the time you were born you would have already done it and everything would work out normally

RNK explains it very well and simply a few posts above this one

[Janus]

and so it would be impossible to shoot your grandfather before he gave birth to your parent.
I understand what you're trying to argue (that it's "impossible" since you're technically still alive/exist) but provided that time travel is possible, what would physically prevent you from killing your grandfather/father/yourself?


this is why you cannot alter the present by going back in the past, because by the time you were born you would have already done it and everything would work out normally
This is provided you do nothing that affects your very existence and this also follows the multiple history line of reasoning in that as soon as you change something in the past, it branches off into an alternative/different history.

Carl Sagan on the grandfather paradox:

The grandfather paradox is a very simple, science-fiction-based apparent inconsistency at the very heart of the idea of time travel into the past. It's very simply that you travel into the past and murder your own grandfather before he sires your mother or your father, and where does that then leave you? Do you instantly pop out of existence because you were never made? Or are you in a new causality scheme in which, since you are there you are there, and the events in the future leading to your adult life are now very different? The heart of the paradox is the apparent existence of you, the murderer of your own grandfather, when the very act of you murdering your own grandfather eliminates the possibility of you ever coming into existence.

Among the claimed solutions are that you can't murder your grandfather. You shoot him, but at the critical moment he bends over to tie his shoelace, or the gun jams, or somehow nature contrives to prevent the act that interrupts the causality scheme leading to your own existence.

[RebelDog]

You shoot him, but at the critical moment he bends over to tie his shoelace, or the gun jams, or somehow nature contrives to prevent the act that interrupts the causality scheme leading to your own existence.

Surely if its possible to interact with the past at all, then you will affect the future no matter how small one perceives the interaction. When he bends down to tie his shoelace or the gun jams smash his skull in with a rolling pin. If it was possible to travel to the past then in simple terms the present day universe would have less mass/energy than it hitherto had. How would we present day mortals explain that?

[redcannon]

Originally posted by The [email protected] 21, 2007 07:56 pm
If it was possible to travel to the past then in simple terms the present day universe would have less mass/energy than it hitherto had. How would we present day mortals explain that?
we still haven't figured out the rules of the universe yet. it may very well be possible to travel back in time, who knows? unitl we know everything there is to know about the universe, we can't rule out any possiblities. there is even a peice of quantum mechanics that shows faster than light speed is possible, thanks to the uncertainty principle and entangled photons...

[Goatse]

Basically, if you went back and changed something, it's already happened. So obviously, you never went back and killed your grandfather.

Isn't discussing alternate realities moving into the area of the 5th and 6th dimensions?

[bcbm]

I understand what you're trying to argue (that it's "impossible" since you're technically still alive/exist) but provided that time travel is possible, what would physically prevent you from killing your grandfather/father/yourself?

If you went back in time and shot your grandfather, you wouldn't be born in the future and therefore could not go back in time to shoot your grandfather and he would therefore still be alive... and able to sire you for you to attempt to go back and kill him.

Catch-22 dude.

[redcannon]

its funny, theres been 5 explanations of the same thing, i hope everyone gets it by now

[Janus]

Catch-22 dude.
Yeah, it's a paradox we've all gotten that.

Anyways, debate about this kind of stuff is pointless until we actually begin to understand how to actually do time travel if that's actually possible at all.