Do you think time travel will ever be possible?

[Woolong]

Obviously of course, not speaking of moving forward in time, because we're doing it right now. I'm talking about going back in time. Our technology as of now, is assumably nowhere near achieving time travel. But even if we do manage to gain the technologies to do it without killing ourselves first... Would it be possible? Would we screw everything up? What would happen?

Take this, for example:

You travel back in time in order to, say, assassinate Hitler before he ever began invading other countries in an attempt to conquer the world. Upon achieving this, you go back to your own time (assuming you can even get back to the eact time of place that you left, because if you accidentally ran into yourself, well, let's just say I doubt your brain could handle what you would be seeing seeing) and he never did. Everything he did never happened. However, now that he was assassinated before having attempted to achieve world domination, you have no reason to go back in time and kill him. Hell, you've probably never even heard of Hitler before, because he's no longer a prominent historical figure. Meaning you never go back in time to kill him. Meaning he does attempt to conquer the planet. Meaning you go back in time to kill him. Wash, rinse, repeat.

What effect would something like that have on the fabrics of time? Would another timeline split off, in which Hitler really was assassinated, and another in where he wasn't? or would it continue to loop until the entirey of the universe just went "WTF happened there?" and give us all the Blue Screen of Death?

Your thoughts?

 

[YOyoYOhowsDAjello]

Here's some Time Travel Highly Technical discussion for some opinions that were already made:

1
2
3
4

Lots in OT too.

 

[Woolong]

I have to get used to using the search feature.

I comfrom a board that archives topics, so duplicates happen. A lot.

That and searching for something serious usually only brings up secret topics, joke topic, ASCII topics, and the like...

...

Anyway, I was just kinda wondering what people's opinions were. That and this is only my third topic here.

 

[f95toli]

I think whole idea of having an "opinion" is flawed in this case, simply because we do not have enough information. Anyone who answers this question is simply guessing.

For some reason many people tend to think of moderns physics as a form of philosophy, but it is not; it is science and a question like "is time travel possible" has a definite answer (yes or no) but we do not know enough about the universe to answer it yet.

Maybe in 20 years if e.g. string theory continues to develop.

 

[MobiusPizza]

I doubt it though it's possible. Nature is a well designed and defined environment. The consquences of time travel possible is insane.

I ever wondered how would time travel be possible even if time is an extra dimension. I meant does the nature record what you do, what you think, where a dust particle was, the orbitals of every electrons and their spins, in every zetto atto seconds? This huge information database cannot be stored by all matter in the universe; In extra dimension? Could be, but I doubt since time begun the information have been storing since then

If time travel is possible, we should be seeing people from future by now.

 

[bsobel]

I meant does the nature record what you do, what you think, where a dust particle was, the orbitals of every electrons and their spins, in every zetto atto seconds? This huge information database cannot be stored by all matter in the universe;

Sure it can, see 'infinite' If you buy the multiverse model then time travel really isn't a big problem, the universe infinitely splits along descision trees. In one multi-verse I'm teling you how to build the time machine, in another you killed me for responding, and in ours I'm ending my post

 

[YHPats]

I agree - time travel into "the future" is possible, by going on a trip in a near-light-speed capable ship and returning to Earth - whence hundreds of years have passed while you haven't really aged.
But you'd be stuck there - unable to return to "the past".
So in reality, all you'd have done is arrested your own aging process - so the trip would only be equivalent to cryogenic suspension rather than true time travel where you could go on a time excursion ... that really is the stuff of science fiction.
Neither past nor future can be altered simply because we can't travel backwards.
Alter "the future" and it stays altered.

 

[cquark]

General Relativity permits time travel, and you can find scientific papers explaining how to do it in detail. However, you cannot travel to a time before the time machine was built, so you can't touch Hitler unless you find a time machine built by aliens before 1945.

Even if GR is correct, I don't think we'll be able to construct such a device for centuries if ever, as it requires a large high-density torus of matter spinning near the speed of light, where large means greater than planetary mass and high density means neutron star or black hole density.

 

[EvilHomer]

No ...time travel will never be possible ...Time is unfortunatly one of the few definites in life ... sucks huh....

 

[f95toli]

Originally posted by: EvilHomer
No ...time travel will never be possible ...Time is unfortunatly one of the few definites in life ... sucks huh....

Prove it!

I am quite sure you can't. You ASSUME time travel is not possible because "it would not make sense"; however we aldready know that nature does not "make sense" so that is not a valid argument.
I don't think time travel is more"strange" than for example quantum tunneling, teleportation etc

.

 

[Acanthus]

In my own mind, using deductive reasoning, time can be slowed, but can never be stopped or reversed.

Time is the way the mind pervieves its environment, its linear. This happens, then this happens, then this happens. This is what time is.

No matter how fast you travel or how far you go, time does not stop, you just went somewhere really really fast.

Now i do believe that we will someday exceed the speed of light, you will be able to travel incredible distances at a speed greater than the speed of light and actually see into the past. But this is only radiation from the past, an "instant replay" if you will. You cant manipulate it, you can only see what happened.

Like now, we can see stars 10 light years away. The light from those stars is 10 years old, so we are seeing what that star looked like 10 years ago when we look at it. No matter how fast we travel to that star, it will always be in the present. We can circle it 400 times, slingshot off of the gravity of black holes, whatever... Time is still going forward.

You cant undo what has already been done, no amount of speed or technology can surpass the barrier that is time.

This is of course my opinion.

 

[cquark]

Originally posted by: AnnihilatorX
I ever wondered how would time travel be possible even if time is an extra dimension. I meant does the nature record what you do, what you think, where a dust particle was, the orbitals of every electrons and their spins, in every zetto atto seconds? This huge information database cannot be stored by all matter in the universe; In extra dimension? Could be, but I doubt since time begun the information have been storing since then

Time's just another dimension, so you could just as well ask how nature stores with the radial coordinate information of every event instead of the time coordinate. A GR time machine works by rotating your 4-dimensions so that the radial coordinate takes the place of the time coordinate.

As for the insane consequences, that's from our perspective, having evolved in at the 1-meter scale where quantum and general relativistic are invisible. Even at the millimeter scale of insects, physics appears very different--you can walk on water and even carry spheres of water instead of needing containers.

At the molecular scale inside the cell, secondary electromagnetic effects are stronger than gravitation and solidity begins to be revealed for the illusion it is, so that ideas as simple as making a stack of items on your solid surface become quite complex, as putting two items (molecules) so close to each other can cause them to deform and interact and gravity's not strong enough to hold your stack to your surface.

At the atomic quantum scale, physics becomes fully probabilistic, and at this point, we're still further from the high gravity regime that allows time travel than we've moved from the everyday physics of the 1-meter scale.

In other words, you can't trust your intuition on these matters--it's based on 1 meter physics, and as I've shown that begins to break down at the 1-mm scale, while we're talking about the Planck scale, 40 orders of magnitude smaller in distance (or equivalently, higher in energy) when we're dicussing time travel.

If time travel is possible, we should be seeing people from future by now.

Note that the time travel permitted by General Relativity doesn't permit travel to a time before you constructed the time machine, so you wouldn't see people from the future until you build a time machine.

 

[SVT Cobra]

I have always loved this topic...

Similar in topic....i remember reading that this one scientist was able to travel in time an electron, but because it could only travel as far ahead as when the time machine sent it into the future, an exact duplicate appeared.....i do not remember the details....but it can be proved as time travel....let me see if i can find the journal....theyre still working on it in germany i believe

 

[Fox5]

I don't think time travel is possible directly, but I believe it might be possible to view things that happened in the past and turn the current state of something back to the same as it was in the past.(so to turn the entire universe back to the way it was would take a lot of effort)
So you make the universe go back in time around you, not put yourself into the past of the universe.

 

[nomadwind]

so to turn the entire universe back to the way it was would take a lot of effort)

A lot of effort it is - I too do not think it is possible nor beneficial to go back in time. I've got my theories in my tiny head, but I'll simplify it.

Essentially, the universe should be in equillibrium. If you changed only one aspect of it, that is, let's say Earth's history, then the result would be some inequillibrium with the rest of the universe - no need to go too far, just take the solar system. In fact, to go back in time with "the knowledge that you are from the future" easily upsets the balance.

Remember Einstein's saying that energy is not destroyed - conservation of energy - but simply converted? Yes. Think of it, the many trees that were cut down - what became of them? Cut down, burnt or turned into paper, which is then further converted. Everyday it happens. In your engine (fuel turns into power and heat), in your stomach.

Therefore, to turn everything back, you would need to turn all the energy into that time's state - humongous, humongous amount of energy if you consider E=mc^2. Not to mention anyone attempting to do so, no wait, everybody born after a chosen point in time would cease to exist. That includes the person attempting time travel.

That's what I think, I've tried to simplify it as much as I can. (though I suppose you do need some background knowledge...)

 

[imported_jb]

i think i've said all i need to say about time travel in the other topics. exept this:

as Acanthus brought up, light takes time to get places. light from a planet 20 lightyears away takes 20 years to get to Earth.
now add 'entangled particles', where information could possibly be sent instantaneously. those two technologies allow the following scenario:
video from a telescope of a planet 20 lightyears away is made public. however, if both planets actually had entangled particle based information transfer, a select few could know what is going on Now, while the public gets a 20year delay.

so no betting on football in other galaxies.

 

[f95toli]

The problem with that idea is that you can not use entaglement (=quantum teleportation in this case) to transfer information faster than the speed of light.

 

[Velk]

Originally posted by: AnnihilatorX
I doubt it though it's possible. Nature is a well designed and defined environment. The consquences of time travel possible is insane.

Ah the "It can't be true, think of how messy that would be" argument 8). It's ok, Einstein was fond of that one as well, unfortunately all the evidence of recent decades seems to be suggesting that the universe actually is a gigantic mess and nothing really works in nice neat ways even if it looks like it at first.

I ever wondered how would time travel be possible even if time is an extra dimension. I meant does the nature record what you do, what you think, where a dust particle was, the orbitals of every electrons and their spins, in every zetto atto seconds? This huge information database cannot be stored by all matter in the universe; In extra dimension? Could be, but I doubt since time begun the information have been storing since then

You would do as well to ask how the universe knows where everything is when you move a pencil from one side of your desk to the other. It's the pencil that's moving, not the universe, and the universe doesn't need to "know" where everything is.

If time travel is possible, we should be seeing people from future by now.

And if life on other planets is possible we should already have been overrun by hostile aliens that look like elvis - what's your point ? 8)

 

[TheoPetro]

k so say time travel is possable......someone creates a machine so in the future we can transport back to it....well were in the future sitten around and we wanna go back 10 years so we get in and go back. when we appear in the "past" are we creating matter? is that matter created from some energy stored in the machine and will it run out eventually? are we pulling matter from the plant we will eat as a salad in 2 years at the moment we appear? or are we simply transporting our matter from the present. say you wernt born when the machine was made. then will all the matter that went into creating you just appear? this seems like it would be breaking one of the most fundimental rules of physics that energy is conserved wether its mass or in the form of energy it has to come from somewhere and as of yet im pretty darn sure we cant create it and everywhere we look mass is conserved. just something to think about

 

[Darksamie]

Hmm... I don't see a whole lot here on parallel dimension theory which could occur in going forward or back in time.

Basically you would be travelling through time to a parallel dimension, so you could in effect travel to a state before the time machine was built. However, you could never travel back to "your" dimension in time as there would be no way to plot a course to a dimension in an infinite number of dimensions.

This is linked to string theory and cross dimensional time travel as some people believe it to be the only way time travel would be possible.

Having multiple dimensions or "instances" of time also raises many questions about "god" etc etc as in effect there would be an infinite number of worlds are parallel universes etc etc so you could theoretically go through time forever and never get back to where you started.

If anyone wants more info on this or wants to debate further, weigh in and lets have some interesting conversation.

 

[Gamingphreek]

You cannot travel in time.

It is thought that when traveling at light speed time is "bent" per se, however traveling at light speed is impossible for anything because at that speed you require infinite energy and have infinite mass... ie: you turn into pure energy.

-Kevin

 

[cquark]

Originally posted by: TheoPetro
k so say time travel is possable......someone creates a machine so in the future we can transport back to it....well were in the future sitten around and we wanna go back 10 years so we get in and go back. when we appear in the "past" are we creating matter? is that matter created from some energy stored in the machine and will it run out eventually? are we pulling matter from the plant we will eat as a salad in 2 years at the moment we appear? or are we simply transporting our matter from the present. say you wernt born when the machine was made. then will all the matter that went into creating you just appear? this seems like it would be breaking one of the most fundimental rules of physics that energy is conserved wether its mass or in the form of energy it has to come from somewhere and as of yet im pretty darn sure we cant create it and everywhere we look mass is conserved. just something to think about

Actually, conservation of energy isn't actually as simple as it's made to be in freshman physics and doesn't present a barrier to time travel.

Curved spacetime, even without time travel, breaks global non-relativistic conservation of energy, as the simple definition of conservation of energy as dE/dt=0 over all of space no longer works, for the definition of derivative effectively assumes a flat Euclidean space. You can't cover spacetime using a single coordinate system if the spacetime is curved.

Relativity allows only local conservation of energy, where the amount of energy inside a small volume changes only when stuff flows in or out of that volume. A local volume is small enough to be effectively flat (think of your location on the surface of the Earth, which is effectively flat even though the Earth is spherical in shape), so you can use a single coordinate system for the local volume, and thus can do regular derivates and integrals.

Local conservation of energy isn't violated by time travel, so there's no problem with it. Global conservation is a much more theoretical principle in any case, as we can't observe the entire universe at once.

 

[cquark]

Originally posted by: Gamingphreek
You cannot travel in time.

It is thought that when traveling at light speed time is "bent" per se, however traveling at light speed is impossible for anything because at that speed you require infinite energy and have infinite mass... ie: you turn into pure energy.

While special relativity doesn't address time travel, general relativity does and GR permits time travel.

Time dilation does occur as you approach light speed, but your mass doesn't increase as your speed increases. While many popular accounts alter the definition of mass instead of momentum, physicists eschew the concept of relativistic mass in favor of relativistic momentum, as it leads to many misconceptions, such as the idea that if you could accelerate an object fast enough, its mass would approach infinitity, causing it to collapse to a black hole.

 

[imported_jb]

Originally posted by: f95toli
The problem with that idea is that you can not use entaglement (=quantum teleportation in this case) to transfer information faster than the speed of light.

i thought that it was thought of as instantaneous. i could be wrong.

 

[robisc]

No never, you can't get back to something that has already been or something that hasn't yet happened, think about it literally not scientifically.