Time travel - Possible or Impossible?

[EvoGamer]

I wanted to hear what you guys think. Me and fellow members always have huge debates on how this could actually work. Now, I was doing my research, and I found out that time travel means different to each person you ask. It could mean :

- Viewing the past
- Viewing the future
- Physically traveling in the past
- Physically traveling to the future

If you can, you should address each one of these.

[Shyknight]

I would add another meaning to that list:

- Physically traveling to a completely separate dimension that happens to be exactly like yours except for it is so many years ahead or behind your dimension in time.

I refuse to speculate on whether any of the above time travels are possible. There is insufficient data to do anything but guess.

[EvoGamer]

Actually you will find that the majority of scientists will say its possible and therefore say there is enough evidence that it is possible.

[Shyknight]

You will also find that scientists talk out of their asses half the time.

[RadicalDreamer]

- Viewing the past

Hm... Yesterday I had a Snickers bar... but for some reason couldn't seem to finish it. I had a stomach ache.

OMG TEH FTUTRE IS TEH NOWZ!!!!1!!1!!

[Bjarni Herjolfsson]

The theory goes that you must surpass the speed of light to bend time back enough to travel back. The theory also goes that light speed is a proverbial asymptote (sp?) and therefore can never be reached. But scientists at NASA have concluded the men who came back from Apollo 11 from the moon (yes they did reach the moon) were 1 point something seconds younger than they would have otherwise been had they not gone. I dont know what kinda test they did but your best bet would be to call NASA. While you're at it, leave the planet and have a vacation (you might also become younger). To do so. I got these directions from Douglas Adams so they're infalliable:

1) Phone NASA. Their phone number is (713) 843-3111. Explain that it's very important that you get away as soon as possible.

2)If they do not cooperate, phone any friend you might have at The White House- (202) 456-1414- to have a word on your behalf with the guys at NASA.

3)If you dont have any friends in the White House, phone the Krremlin (ask the overseas operator for 0107-095-295-9051). They dont have any friends there either (at least none to speak of), but they do seem to have a little influence so you may as well try.

4)If that also fails, phone the Pope for guidance. His telephone number is 011-39-6-6982, and I gather his switchboard is infallible.

5)If all these attempts fail, flag down a passing flying saucer and explain that it's vitally important you get away before your phone bill arrive.

[AlexanderBarca]

I would say it is possible to physically travel to the past (don't ask me how, but in the realm of possibility...) and unlikely to the future. However, it would be impossible to alter anything in the past, as your present would already be the result of whatever you do. (In other words, the past already happened, and if you acted in it, you already acted in it. Therefore, going back in time and trying to save Kennedy would fail, because the reality of your present is that Kennedy was shot). The future is a bit more sketchy, as it has yet to be written (hence your choices have not been made) and anything you experience there will influence your choices...

...OK, that didn't sound too coherent, but its been a long day and I still have a midterm tomorrow to study for. Toodles.

[Stapr]

Here are my thoughts. Please be aware I only know what I've learned from a standard high school textbook, so, yeah, whatever. Oh, I assume when you say "viewing", you mean, seeing what has happened live, without necessarily physically being at that point in time.

- Viewing the past

This is possible, and actually happens on a small scale whenever you look at something. It takes time for the light to travel from the object to your eyes. So, take a look at the sun one day (not though a telescope, mind you). It takes roughly eight minutes for light to travel from the sun to the Earth. Ta-da! You're looking into the past.

Now, I don't think it is possible to see yourself while you were eating a candy bar yesterday, live (with the exception of erecting several enclosed mirrors around you so the light reflects around several millions times). You would need to travel faster than the speed of light along the path the light traveled away from the event. In other words, you would need to outrun the light from the event. Now, I have not seen any evidence that an object can travel faster than the speed of light, which is why I don't think this is possible.

- Physically traveling to the future

This is possible. The speed of light is constant at all speeds. Assume you travel at .5c in relation to a person. After two seconds, the person emits a flash of light (in relation to him). After two more seconds (in relation to him), you've traveled one light-second. After another second, the beam of light is where you were one second ago, and you've traveled .5 light seconds. After .5 seconds, the light is where you where .5 seconds ago, and you are .25 seconds. And so on and so on, until it reaches you. From their point of view, it would take 4 seconds after the light is flashed, until it reach you. From your point of view, light is always traveling at c, so it would only take 2 seconds for the light to reach you.

This discrepancy is the basis for time traveling. Assume you were traveling at an ever increasing speed away from a clock. The time discrepancy grows as you approach the speed of light. You would see the hands of the clock moving slower than the hands of a wristwatch on your wrist. If you stop and travel back at the clock, the time between the clock and your wristwatch would be off, and you are in the future. In other words, the time you experienced is less than the time the clock experienced.

- Viewing the future

Assume a friend is going to turn on a flashlight in two seconds. If you are pressing you eye onto the glass, and he turns it on, you would see it after a very small delay. The further you are from the flashlight, the longer is would take for you to see the light. So it would seem that, if you were a negative distance from the light, you would see if before it happens. Since distance is not a vector quantity, it doesn't have a negative value. That's the only way I could come up with to see the future, so I would say this is not possible.

- Physically traveling in the past

I don't believe this is possible. In theory, it would require traveling faster than the speed of light. In the example of the clock, when you hit the speed of light, the hands on the clock won't move. Increasing speed would cause you to "outrun" light, and you would see the hands of the clock moving counter-clockwise. Then, if you travel fast enough for long enough, stop, and travel back at the clock, you would see the clock is behind your wristwatch; you are in the past.

Now, I have not seen any evidence that an object can travel faster than the speed of light, which is why I don't think this is possible.

[Makh]

We had that kind of experimentation in the desert of kazakstan but no one know where.

First, I think all of you should stop to watch Back to the futer

This reflexion makes my head burn...

Shyknight (about dimension) and AlexanderBarca, this is very interesting.

Seriously, I can not see how it could be possible to travel in the past. It is impossible. I will tell you why. I also know it is impossible to travel in the future (or perhaps we are in the past )

OK, how a man can use a device to make a journey in the past ? How can the past be reconstructed ? I will not use the word dimension, I prefer to use the words time line for my explanation.

If we travel in the past, it means we need to have (to jump on) a second time line (or more if more than one person travel). For example, you want to visit Genghis Khan in 1210. You take your machine and go. While you are gone, all the people in 2004 will continue to live and to work but in another time line. I draw a picture for you:



Here, you, you are with Genghis, you eat, you sleep, etc. But you are not on the same time line of your mother, girlfriend, etc. You do not ask to yourself ``what my girlffriend is doing`` because she is not even born. Remember, you are in 1210. 1210 is the current time, the present. This time line only exist for you.

Hitler is dead in our time line, so we can not bring him back in 2004 to kick his face. However, we can jump in another time line, bring him here, and then kick his face, that would be possible in theory (people in that time line will be pleased to get rid of him).

In other words, it will be impossible to travel in time if you can not jump in another time line. Good luck to find out how to do that he he

EDIT: I am not sure I understand your last big paragraph Stapr and I fail to see how the travel in light speed can alter the time. It only means you go faster. It only means you will reach a distant planet faster. Do not worry, I know this theory is controversial just like mine.

[Killer-Rabbit]

[quote="Bjarni Herjolfsson";p="288750"]But scientists at NASA have concluded the men who came back from Apollo 11 from the moon (yes they did reach the moon) were 1 point something seconds younger than they would have otherwise been had they not gone. I dont know what kinda test they did but your best bet would be to call NASA. While you're at it, leave the planet and have a vacation (you might also become younger). To do so.[/quote]
That's not really time travel, it's relativity. The test they probably did was not on the crew but just comparing a clock on earth and a clock that went with them that were syncronized before they left.

As for time travel, it may be possible or it may not be, but it probably wont be happening any time soon. Also, I believe that the past cannot be changed so any traveling back in time wont change the present. But then people argue that people's free will would allow them to change the present, but then I say that free will is just an illusion and is really just a complex combination of set chemical reactions and then their head explodes and then I gotta explain it to the police somehow and...

[Ender_Wiggin]

[quote="RadicalDreamer";p="288739"]

- Viewing the past

Hm... Yesterday I had a Snickers bar... but for some reason couldn't seem to finish it. I had a stomach ache.

OMG TEH FTUTRE IS TEH NOWZ!!!!1!!1!![/quote]


Remembering the past is different than viewing it. We're talking about being able to SEE the Civil War, without being there physically. As in your seeing EXACTLY what happened in full color, full audio, etc....

[Pout]

Here's an interesting one for you. Professors at the University of Moncton have discovered a way to transport electrical signals at 3 times the speed of light. (for real...actually, some professors from somewhere else used an improved method to bring it up to 300c...there is even a RL comic about it...)

Now imagine a fireworks display at point A where there is a camera hooked to above mentionned technology. At point B, perhaps a couple miles away, there is a screen showing the images captured by the camera at point A.

A firework bursts, the camera captures the images and sends them to point B where observer sees the firework (on the screen) before the photons from point A reach point B (3 times faster, in fact.).

So..in a sense...the observer viewed the future before it happened (well, HIS future, since he also saw the PAST of observers at point A.)

[daemon princess]

I have a silly thought. If you could somehow manage to change everything around you, including your brain to exactly how it was, say a year ago, would it then become a year ago?

[Shyknight]

'everything around you' includes the entire universe, layla. Because the moon and the stars have subtle influences on the world that we cannot perceive. As well as making all the people one year younger somehow. Only God could accomplish such a feat.

But yeah, I guess it would be. It would be like hitting the rewind button.

There was actually a novel I read once in which a man discovers how to travel back to the past. He found a building that was exactly the same as it had been like 200 years ago, and he lived in that building for a while without looking at the outside world. Then he studied a bunch of images from that area the way it was in the past. And he focused his mind on thoughts that were contemporary to that time. Then he closed his eyes, focused, and made himself believe he was in the 1800's.

When he opened his eyes and looked out the window, it was.

[furre]

[quote="Shyknight";p="289308"]'everything around you' includes the entire universe, layla. Because the moon and the stars have subtle influences on the world that we cannot perceive. As well as making all the people one year younger somehow. Only God could accomplish such a feat.

But yeah, I guess it would be. It would be like hitting the rewind button.[/quote]
Keyword: like
It wouldn't be hitting the rewind button, it would be LIKE hitting the rewind button. Just because there's no memory or sign of it ever happening doesn't mean it didn't happen.
But then comes the questions about the nature of time and if is time influenced by the universe or if the universe influenced by time etc etc.

/me needs to go into rehab or somesuch