Re:Re:Re:time travel
You are quite correct that the speed of light "limit" is NOT proven. It exists as a result of the mathematics which apply to Relativity and many of THOSE equations HAVE been tested and proved, including the Time Dilation effect. We actually have no way to really test that limit at this time except possibly in the feild of Quantum Mechanics. This is where the 'tachyon' hypothesis comes from.
Notice that I said "if" one accepts the limit, then relativity has no bearing on Time Travel. Since it is accepted at this time in the scientific community as a valid theory, I won't make hypotheses that ASSUME it is wrong. It has to be proven, or at least accepted to be, wrong first before I can use theories that consider superluminal velocities. You'll find those who will devise hypotheses that make the assumptions that certain generally accepted scientific theories are incorrect, but I'm not one of them. Even tho I do question some very fundamental theories that are popular in Quantum Mechanics (QM), I DO NOT assume my postulations are fact, nor do I base theories on assuming they are wrong. That would be bad science.
If you go down the board and check some of my earlier postings, you will find my specifics regarding the problems I see with QM, so I won't repeat them here.
Time Dilation however, IS NOT Time Travel. For example:
If we send an astronaut on a journey near the speed of light, and his journey only ever takes him on an elliptical orbit in our own solar system, we will never lose sight of him, or our ability to communicate directly with him, delays due to distance and doppler shifting notwithstanding. He also has a telescope aboard his craft and never loses sight of Earth.
He stays on this journey for 60 years, then returns home. The fact is, in that sixty years the dilation has caused him to age only 5 years lets say. He has STILL not traveled to any future but the collective one WE ALL proceded forward into, even if it didn't seem as long to him from his frame of reference.
Here's a question to ponder. If we never lost sight of each other, and we endured 60 years while he only endured 5, did he, during his flight see the Earth orbit the Sun 60 times or 5? Even tho we've measured time dilation, (or at least believe we have), does this scenario not seem like a paradox in itself?
Enjoy, and thank you for your question.