Faster Than Light Communication/Transportation Not Possible?

[dgoodpasture2005]

okay I've read about half of it... and everything is saying that the speed of light controls time... why does this not make sense to me? If i am watching someone travel at .99c and i am here on Earth and i can look into his ship at a clock inside of his ship, and watch it the whole trip, i'd see exactly how long it would take, and our times would be running the same... would they not? if he is traveling at the speed of light, and his destination is one light year away, and i am able to view his clock from here on Earth the whole time(trip), he will still arrive in a year... and it will also take me a year of observation.. therefore our times are running at exactly the same pace? i don't see where this slowing of time comes into affect... or if i do, i don't see how it makes any sense... especially with that explanation i just gave, our time still runs at the same speed, even relative to each other.

 

[εllipse]

okay I've read about half of it... and everything is saying that the speed of light controls time... why does this not make sense to me? If i am watching someone travel at .99c and i am here on Earth and i can look into his ship at a clock inside of his ship, and watch it the whole trip, i'd see exactly how long it would take, and our times would be running the same... would they not? if he is traveling at the speed of light, and his destination is one light year away, and i am able to view his clock from here on Earth the whole time(trip), he will still arrive in a year... and it will also take me a year of observation.. therefore our times are running at exactly the same pace? i don't see where this slowing of time comes into affect... or if i do, i don't see how it makes any sense... especially with that explanation i just gave, our time still runs at the same speed, even relative to each other.

What you are reading about is Einstein's special theory of relativity. It is counter-intuitive at first, but the good news is it can actually start to make a lot of sense once you convince yourself that Einstein's two postulates ("postulate" is another word for "assumption") are correct. Einstein's two postulates are:

(1) All inertial reference frames are equivalent for the description of the laws of nature.
(2) The speed of light is the same in all inertial reference frames.

The second postulate is one of the hardest to accept, but it has been adequately verified by experiment. No matter how fast you move, light always moves at the same speed. As a result of this second postulate, we find that the way nature allows the speed of light to be the same in any reference frame is by shortenning our perception of length (length contraction) and slowing down our clocks (time dilation).

For a good, layman description of the special theory of relativity, read Robert Geroch's General relativity from A to B. I have not read this personally, but have seen it recommended enough on these forums for me to feel sure it is a good source. For a slightly more advanced approach, I would read Einstein's Relativity: The Special and General Theory (if you have graduated from high school, and feel up to the challenge, you should be able to understand this in an appreciative way -- it has very little math, but enough for you to play with, and it's all basic algebra). This has helped me a lot personally because a lot of things in relativity seem so outrageous when you first hear them (especially the relativity of simultaneity) that it helped reading from a physicist as prominent as Einstein himself, because you're much more likely to accept what he says rather than think he may not know what he's talking about. That has been my personal experience, anyway. Einstein also liked understanding things conceptually, so he explains in a conceptual manner. (You can find it online here ( http://www.bartleby.com/173/ ) or also in most book stores with a physics section ... or a local library) If you would like to try a textbook, refer here ( http://math.ucr.edu/home/baez/physics/Administrivia/rel_booklist.html#intro_sr ) for a list of respected relativity textbook authors and what level textbook may suit you best.

And welcome to Einstein's wonderful world of relativity!

 

[brookstimtimtim]

You know I heard allot of this before and will I'm just not buying it. Why is everyone so quick to ftl is impossible. I see a one problem with Einstein theory. If mass changes with the speed of an object, then is mass a virable? With out know what interaction makes this happen I think it is a bit much to say FTL is not possible. If one day we find the cause of this change in mass it might be possible to change the mass of an object to nothing, Einstein own theory say mass is not a constain nor is time. Would this not mean once we have a better understand of both, that both time and mass could be changed to make FTL possible, or do we keep doing as we have been doing, and say everything impossible? Another good one, is the people who says there no way to get around gravity or there not antigravity, they are sure that it is impossible yet nobody know what cause gravity. How do you know it is impossible when you don't why is possible?

 

[Ich]

As long as SR´s first postulate and the relativity of simultatneity hold, FTL leads inevitably to causality violations and is therefore considered impossible.
However, if you assume some sort of Hyperspace which violates the first postulate, you can avoid these inconsistencies - FTL would become logically possible. Still I guess you would have a hard time implementing eg energy conservation or gravitation in such a theory.