Re: Do Logic , Intuition, and Experiment Rule Out Past Time Travel?

Posted by paultrr on July 18, 2003 at 19:49:02:

In Reply to: Do Logic , Intuition, and Experiment Rule Out Past Time Travel? posted by OsherDoctorow on July 17, 2003 at 16:48:11:

My personal take on this is that they do cancel, but only in the sense of how our Global vacuum structure confines the information we can receive to a C limited lightcone. In one respect, and I will not go into the full math on this here, you can take certain equations from SR and have any value for C applied to them and yet, the vacuum state will always limit the information we can observe to C. That velocity is its "speed of sound" for the medium in question. Its not that higher velocities on information transfer cannot exist, its just the part of the "wave" that we can read is limited to the mediums maximum global propagation velocity.

Now, does this in and of itself limit time travel?

No, in fact, I rather agree with most of Kip Throne's viewpoints on this issue. However, I do think that there are certain restraints on how time travel is possible. For one, while this relates indirectly, it was once general believed that quantum processes are the same irrespective of the arrow of time. We now know that does not always hold true. In fact, persent models used to account for anti-matter asymmetry utilize this aspect. So if QFT can limit certain time reversal operations then it would be wize at least to consider time travel in the classical sence as having limits.

I once ran into someone who mentioned some of my own ideas on phase shifting time at the quantum level seemed to support time travel of the passanger type. I thought about what this individual was saying then showed him how while the idea worked for forward time travel it simply would not work for backwards time travel because the original copy(the passanger) is distroyed in the process of going backwards. Now granted one could still travel as a copy and return to one's starting point as a third copy. But in the classical sense that is not time travel.

Now does the future and past waves continue in their course? Yes, they still exist. But can we observe them in most cases? At the present time I'd wager no would be the answer unless we look for effects we cannot attribute to normal C limited velocities.

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