Star Trek's time travel paradox

Originally Posted by Chris

I've attached a quick image I made in photoshop of why the lastest Star Trek film last summer has ruined ST forever (I'm still bitter I guess). Most time travel stories in science fiction never work because they run into paradoxes. ST has made the same mistake that many other sci fi films and shows have. That problem is this: People travel back in time, tell others in the past of future events, and then the ppl from the past prevent the event from ever taking place in the future. However, if that event were to never take place in the future, subsequently there would have been no one that traveled back to warn them. If no body traveled back to warn them, then how did they manage to know about the event in the future to stop it? And therein is the paradox.

I think it's only a paradox if you assume that only one timeline can exist, and that it has to be static. Maybe timeline A (the original events) still exists even after timeline B (with the altered events) is created, but the Spock and Nero that end up in timeline B originally came from timeline A.

Or maybe the two timelines just cycle back and forth, like in digital electronics when you wire an inverter's output into its input: you create a condition that, on paper, creates a contradiction but in reality it creates an oscillation between the two states.

"Into the Universe with Stephen Hawking" was on the Discovery Channel this evening. He discusses the various possibilities of time travel and mentions the problem of paradoxes with traveling to the past. He doesn't seem to find any problem with time travel into the future however.
I think spending several years on a gigantic spacecraft traveling near the speed of light to return to Earth several hundred years "in the future" is a very poor "time travel" option. If you happen to have friends and family on Earth, scooting forward, never to see them again (since they will have died during the 100 years on Earth) is not at all desirable. Remember, this spaceship option does not allow you to return to your "own time".
Worm holes seem mighty questionable, especially since physicists haven't actually produced any concrete evidence of their existence. May as well believe in a god who can tell you about what's going to happen in the future.
Cryogenics may have a better option. Live as much of one's life on Earth until your health is impaired enough to make it painful. Be frozen for the next 200 years. Then revive to "the future". You got to live your life with your family and still got to see what 2300 looks like. Makes much more sense to me. Much more energy conscious too, since traveling at near light speed would require an astronomical amount of energy.
As far as Star Trek goes, the best "time travel" is watching an old episode or movie from the 1960's and 90's. Imagination can take you anywhere, any time.

You guys are a bunch of geeks and I'm sure I have no idea what you're even talking about...

So anyway, the WORST Star Trek time travel faux pas was in Star Trek Voyager. There was one episode where they were investigating a planet which had been destroyed and Janeway had fallen through a time sphincter or something and was trapped in the past and the crew was trying to save her. She saw that what they were doing to save her was about to intersect with a pipe, which would have caused the destruction of the planet, so she stopped it. Since she stopped it the planet wasn't destroyed and since it wasn't destroyed it was not interesting and they passed right by it. So she traveled back in time because the planet blew up because she traveled back in time. With writers without a grasp on even the simplest scientific concepts it's a wonder that show made it 4 seasons. Such an interesting concept, so poorly executed (the show, NOT that idiotic episode).

Speaking of the voyager team's lack of scientific understanding, there was one episode with a water planet which, for some reason, needed more than gravity to hold it together. They found out that what was holding it together was a machine in the center. The people living there were using the water to produce power. They separated out the lighter elements, making the heavier ones sink to the middle where this machine was. This was causing the machine to fail because EVERYBODY knows that if you have a ton of bricks and a ton of feathers it weighs WAY more if you put the bricks on the bottom...somehow. They had to have hired the dumbest people in sci-fi for that show.

First of all, time travel, although not shown to be physical impossible, is not (yet) a reality. So how are we complaining that the scifi movie makers got it wrong?

Its easy to think of the universe as a 3 dimensional object with a universal clicking clock, but it is far from that. It is also easy to think of you as being a 3 dimensional agent made up of little atoms sliding through time and 1 second per second, but this too is not quite true. The particles in your body have a 4th dimensional extent, which in classical general relativity can be called world lines. Quantum mechanics however, shows us that this world line view is not entirely true either in that a particle that goes through a double slit, for example, has taken all possible physical paths to arrive at the detector on the other side. It has a non unique history. If I can conjecture a little bit, I would say that our understanding of the present is more or less a measurement (or better yet a collection of measurements) that do not have a unique history. Just like the double slit where we measure the particle on the detector side, but can not know which slit it came through. The important take aways are that a unique history is not the reality of nature and that you are not the particles that make you up, more accurately you are the interactions of those particles. If this idea reflects reality than the truth is that there are infinitely many "presents" in which people like us are living. If you go to the past, it may not be the past you remember, but be completely different, likely more different the further in the past you go. Whats more, changing something, does nothing to your "present." There is also another view that every quantum mechanical process such as the decay of a particle causes there to be multiple realities (universes) that coexist. That might mean there are not only infinitely many present moments in the past but maybe infinitely many right "now."

OK, thats pretty heady... hope I was clear enough.