Time travel (209)

151 Name: Anonymous Scientist : 2008-02-17 12:02 ID:FQiRyXDB

>>150

We have trouble understanding time, because we spend all our life immersed in it. It's a bit like air: in the past people did not realised that air is not just space between objects, it's something in itself. Of course there were hints (water/air interface forming bubbles, winds). Nowadays it's much easier to understand air, because we see all the time applications of our knowledge of it (airplanes, etc).

I have no knowledge of reverse-time physics, but it's not a problem in this case, because all your questions equally apply to time flow variations: as you may know, the flow of time you're in depends on the mass surrounding you and on your speed.

So if you are travelling at close to the speed of light, your time will be very different from all surrounding objects which travel at a slower speed. As you can see, you can induce a local variation in the flow of time without requiring infinite amounts of energy. One could extend the reasoning and assume that you can vary the local flow of time to such an extent, that you might locally revert it. The conceptual difficulties are the same in both cases.

As for your question with the rock, you just have to think about black holes. In a black hole the mass is infinite, and the flow of time is ripped apart (and I think nobody knows what's going on inside a blackhole). So if you throw a rock into the black hole, as the rock travels space, the flow of time it is subjected to will slow down until it reaches singularity, and then it's anyone's guess. Some people have even suggested that matter could emerge in other points of space or time through white holes (it's not only time which is ripped apart, but space too).

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