Time Travel: Is it possible? Should it be done?

[Kobuk]

Was bored tonight and watched an old favorite movie called "The Final Countdown".
http://en.wikipedia.org/wiki/The_Final_Countdown_%28film%29
.........which made me curious to post this topic.

The main points of this topic are: Is time travel possible? And if so, Should we be tampering with history or should we let events occur "as is" without interference?

Personally, I am of the belief that past history (People, Places, and Things) should not be changed and interfered with lest there be severe consequences on future events and people. If I could go back through time and change anything, I wouldn't. I would rather be an "observer" instead and just enjoy history as it unfolds. If I had the chance to go back in time and watch/relive history, then I would want to observe the following:
* The supposed Roswell UFO crash incident of June/July 1947
* Find out what happened regarding the death of Elvis.
* Observe the attack on Pearl Harbor on December 7, 1941.

If I had the chance to change history, then the only event I might change is the asassination of John F. Kennedy.

I've always been confused on the following: If someone did go back in time and change history, then are they changing the current timeline, or have they created a second separate "parallel/alternate" timeline?

[Battery]

 I believe that time travel is possible.  I remember watching a special on tv about it and there is a guy trying to develop a time machine that uses high powered lasers. His goal is to send a partical back. The catch is that you can only send something back as far as the time when the machine was turned on.  So once he turns it on particals and stuff will start showing up.

Can you change the past?  I say no
Time fits like a puzzle so If you go back and try to change the past you'll only cause what's suppose to happen or you will be a spectator to the event, If you do some how change history your time machine sent you to an alternate universe where those events happened.
 
So all I can really say is time travel is confusing and stupid!!!

[Kael]

Time travel, if ever created, would require us to be observers. Because, if we go back in time to change something, either we create an alternate universe which we MIGHT be able to return to if we they made a machine of their own,

Or, we would create a paradox, as per if we go to change it, and it does, in current time it would be that you would never have gone back to change it in the first place. This would either make you cease to exist, or destroy the entire world...

So, yeah, not really thinking it's gonna happen...

[furtopia02]

I definitely feel that if this is ever possible it shouldn't be done and rather the science of it destroyed before anyone even knows it was figured out. It's for the best. Altering something ages ago could mean the end (or rather, non-existence) of many of us today even if it didn't seem directly related it would always be indirectly related. You could wipe out hundreds of thousands of people with any simple action that would alter time. It isn't right and I certainly hope it is never figured out.

[Foxpup]

Pfft. Assuming our understanding of quantum mechanics is correct, it's not possible to change the past if you go back in time. (Note: neither quantum mechanics nor relativity rule out the possibility of time travel, just that of changing the past) A time-traveller would only be able to do things that he already did in that time (by `he', I mean the time-traveller returning to the past, not the version of him that already existed at that time (although he would also only be able to do things he already did, because he already them, if that makes sense)). Paradoxes don't and can't happen, and any attempt to cause one will fail.

Also, all current theoretical time-machine designs have the constraint that they cannot send a person back to a time before the time machine was constructed (which is obvious if you think about it, since the time machine doesn't exist anymore).

If I had the chance to go back in time and watch/relive history, then I would want to observe the following:
* The supposed Roswell UFO crash incident of June/July 1947

The object that crashed near Corona, New Mexico has been identified as Mogul Flight #4, a high-altitude balloon designed to detect Soviet nuclear tests. The project was Top Secret at the time, which is why the wreckage was shipped to the Roswell Army Air Field and the alien spaceship story was created as a cover-up. Apparently the cover-up worked too well, since people still believe it was an alien spaceship, even after all the details have been declassified.

* Find out what happened regarding the death of Elvis.

He died of a heart attack, possibly brought on by drugs, on 16 August 1977. What else do you want to know?

[Kobuk]

The object that crashed near Corona, New Mexico has been identified as Mogul Flight #4, a high-altitude balloon designed to detect Soviet nuclear tests. The project was Top Secret at the time, which is why the wreckage was shipped to the Roswell Army Air Field and the alien spaceship story was created as a cover-up. Apparently the cover-up worked too well, since people still believe it was an alien spaceship, even after all the details have been declassified.

I don't believe that, and most likely never will. 

[aspect]

Like others have said, our best guess right now is that going back in time cannot create paradoxes, and doesn't split the timeline into a new Universe. If this is true, I see no harm in plenty of time tourism; the improved knowledge of the past would be great. (There are methods of building time machines that may let us travel further back than the machine's creation, such as incorporating a worm hole of the right age.) But people probably wouldn't be able to resist helping people in the past when they go back and visit. We might find that our present history depends upon assistance given to both well-known and unknown historical figures. There may be certain mysterious, important "assistance events" brought on by people in the distant future with far superior technology. But we shouldn't feel a ... responsibility to develop that technology and accomplish said assistance event, it'll happen anyway.

Now, hopefully I can explain this adequately but: there are some physicists who feel the apparent paradox of going back in time and not being able to change anything is an actual paradox. That is, some parts of physics seem to tell us it is possible to travel back in time; others seem to tell us it is possible to, say, kill a person; therefore the conclusion should be that it's perfectly possible to travel back and kill our parents, so there has to be a mistake somewhere. Or from a more mechanical viewpoint: It seems perfectly possible to build a machine which will transmit a signal ten seconds back in time only if it didn't receive a signal ten seconds ago. This sort of contradiction means there must be a mistake in the math somewhere. For us, and some physicists, it's easy enough to imagine something like fate keeping such a machine from being built; but that's not a real theory of what happens.

I believe that time travel is possible.  I remember watching a special on tv about it and there is a guy trying to develop a time machine that uses high powered lasers. His goal is to send a partical back.

This is probably a different guy but I remember seeing Günter Nimtz on television back when I was in middle school. He actually did create a little time machine which sends a signal back in time a fraction of a second; he can be seen on a couple different documentaries playing his recording of Mozart that he beamed back in time through the machine. (Maybe it was a different composer, I don't remember.) I downloaded his paper on the subject and after all its calculations and whatnot it said "No exchange of cause and effect." A year or two ago I found out he has since published a book about time travel more aimed at the masses. I've got it but I haven't read it yet, too busy reading other physics books.

I definitely feel that if this is ever possible it shouldn't be done and rather the science of it destroyed before anyone even knows it was figured out.

I don't think hiding knowledge like this is ever the best option. It's certainly true that discovering time travel might fundamentally alter the fabric of reality here on Earth. But treating it as a state secret just makes it more likely to be rediscovered later by someone who doesn't realize the danger.

[victorwolf]

i believe that time travel is possible maybe through a worm hole or something, but i wouldn't recommend doing it unless it's to the future because you can't change the outcome of the present like that

[Kay Alett]

You cannot go back and change the past, because didn't.

Basically no matter your interference you can't alter what history has already been laid down.

This is one line of thought. Then there is the Back to The Future line of thought that you can change things but really you can only change things that you had no intentions of changing. (Don't bring up 2 and 3 to me because I don't like them,the only one worth watching is the first IMO)

Then you have the Bill and Ted's Excellent Adventure style which I feel is the best and follows the path of the aforementioned rule. They had things happen for them like a trash can in the jail, keys mysteriously appearing and a fax from themselves all because they did these things later after the movie. They couldn't forget to do them because they already happened. Same way with Ted and hiss watch, no matter how many times he reminds himself he will always forget because it happened.

[furtopia02]

Regardless of what anyone talks about in this thread it still isn't real science yet. Not really. We don't know what would happen, though I'm very confident we will never know what would happen either because this just isn't going to be invented. You are never going to time travel and really this whole conversation is just for entertaining wild 'what-if' kind of questions like a small circle of friends in a basement in a cloud of incense smoke. Fun to talk about but not important or practical in any sense.

[Kobuk]

Regardless of what anyone talks about in this thread it still isn't real science yet. Not really. We don't know what would happen, though I'm very confident we will never know what would happen either because this just isn't going to be invented. You are never going to time travel and really this whole conversation is just for entertaining wild 'what-if' kind of questions like a small circle of friends in a basement in a cloud of incense smoke. Fun to talk about but not important or practical in any sense.

Even if time travel isn't possible, I still find it curious to discuss. Or as you said: "Fun to talk about....." 

[Hashira]

I think if tine travel existed that we'd screw up and ruin the future with something we thought was good. Just sayin'

[Mylo]

What would happen then if you traveled back in time and killed your other self in the previous time?

[victorwolf]

you would cease to excist

[aspect]

you would cease to excist

Rather, the Universe would cease to exist.

My plan has always been to build a machine which, when activated, goes back in time and destroys itself. Press the button whenever anything bad happens. Thus nothing bad ever happens because the Universe keeps itself from being destroyed.

[Foxpup]

My plan has always been to build a machine which, when activated, goes back in time and destroys itself. Press the button whenever anything bad happens. Thus nothing bad ever happens because the Universe keeps itself from being destroyed.

Such a device would be useful in quantum computing.

[Storm Fox]

Since the Earth is always rotating, and we are always orbiting around the Sun,
The Sun is always orbiting around the center of the Milky Way, and the Milky Way Galaxy is always moving. (Maybe around another larger center).
The position that we are all in right now in the universe, is different from that at any other point in time.

And if someone traveled through time by just one single minute, the Earth would have moved approximately 36,000 kilometers within that time.

So wouldn’t it be impossible for someone to travel through time and remain in the same place relative to the surface of Earth, let alone stay on Earth?

[Landrav]

So wouldn’t it be impossible for someone to travel through time and remain in the same place relative to the surface of Earth, let alone stay on Earth?

I figure, hey, we're talking about time freaking travel here. Compensating for spatial drift should be child's play.


I believe that, since it is mathematically possible to travel through time, the universe must have some mechanism of coping with the possibility of altering past events.  Whether that means we are living in the most stable version of reality*, or it means spin-off realities, I dunno.

*Edit: by which I mean the universe "stabilizes" to our version.  Something inherent about our timeline prevents further changes.

[aspect]

So wouldn’t it be impossible for someone to travel through time and remain in the same place relative to the surface of Earth, let alone stay on Earth?

We can always appeal to the laws of relativity. If you feel like you're staying still, then in some sense you are. Time travel shouldn't be much different than airplane travel in this respect.

[Foxpup]

Since the Earth is always rotating, and we are always orbiting around the Sun,
The Sun is always orbiting around the center of the Milky Way, and the Milky Way Galaxy is always moving. (Maybe around another larger center).
The position that we are all in right now in the universe, is different from that at any other point in time.

And if someone traveled through time by just one single minute, the Earth would have moved approximately 36,000 kilometers within that time.

So wouldn’t it be impossible for someone to travel through time and remain in the same place relative to the surface of Earth, let alone stay on Earth?

Impossible to remain fixed in place relative to a point on the Earth's surface? Yes. Impossible to remain in some kind of orbit around the Earth? Not if inertia and free fall have anything to do with it (assuming a time warp is affected by gravity the same way everything else in the universe is, which is a pretty good bet, considering that any other option violates relativity).

[Storm Fox]

Impossible to remain fixed in place relative to a point on the Earth's surface? Yes. Impossible to remain in some kind of orbit around the Earth? Not if inertia and free fall have anything to do with it (assuming a time warp is affected by gravity the same way everything else in the universe is, which is a pretty good bet, considering that any other option violates relativity).

That's assuming it is affected, but I'm thinking like this…

Someone or something is going to be sent through time…

The starting location [A] is where we are,
The destination [B] is where we are going, (one minute in the future).
And [C] represents all the locomotive physics of our universe.

Now if we are present during that minute between [A] and [B], we are subject to [C], just as we always are.
But if we skip over that minute when we travel from [A] to [B], we skip one minute of exposure to [C], while everything else was subject to it’s effects.

[aspect]

Now if we are present during that minute between [A] and [B], we are subject to [C], just as we always are.
But if we skip over that minute when we travel from [A] to [B], we skip one minute of exposure to [C], while everything else was subject to it’s effects.

If we keep momentum during that time, everything will be roughly fine. If we keep momentum and gravity, even more so, which is required by relativity (according to relativity gravity doesn't really exist, it's just a part of how momentum works). If we don't keep these things, at least in my way of thinking all our atoms fall apart and could come out absolutely anywhere in the Universe.

It's not like there's some absolute reference frame with respect to which we might stand briefly still; except of course that of momentum.

[Kobuk]

I can't remember what magazine title it was, maybe Science, Discover, or something else, but there was an entire issue devoted to time that I saw on a newsstand yesterday.

[Wereaibo]

I don't think time travel will ever be possible. Too bad because there is much about my past I'd like to change. So much time wasted on useless bullcrap.

[Foxpup]

I don't think time travel will ever be possible. Too bad because there is much about my past I'd like to change. So much time wasted on useless bullcrap.

Go watch the Star Trek: The Next Generation episode "Tapestry" (season 6 episode 15).