Quote:
Originally Posted by kovidgoyal
@RSE: Actually it's not the speed of light that's upper bounded (and note that as you correctly point out, the speed of light is not a constant, except in an ideal vacuum and no such beast exists). So it is fair to say the speed of light is never constant.
What is upper bounded (and again not constant) is the speed of signaling, i.e. information transfer. And I would not really want to live in a universe where the speed of signaling is not upper bounded. I can't even imagine what such a universe would be like. The havoc it would play on causality alone makes me shudder.
It could of course be argued that the upper bound is not the speed of light, but such an upper bound must exist. And I somehow doubt that the upper bound, if higher than c will be high enough to allow for IST.
To me the only semi-hopeful way that interstellar travel can be achieved is by space-time distortions that temporarily alter the topology of the universe to connect remote regions. Wormholes for the layman  Unfortunately, I know very little about General Relativity, so I cannot really comment on the feasibility of that as a practical means of travel. Which is probably why I find it hopeful  |
Speed of signaling has so far been limited to speed of medium carrying the signal. I have great difficulty getting my mind around a situation where the medium can travel faster than a signal embedded in it.
I was merely pointing out to S/F writer a potential loophole that legitimately allows FTL <sic> travel (by speeding up light). The underlying issue (to me) is
why C not what
C. I suspect that we will find that "the ether" was a correct concept, after all. Michaelson Morley didn't disprove "ether", they merely showed it didn't affect light measurement. The Lorentz transformation explained why. Both were incorporated in Special Relativity, and mathematically consistent with it. For example, if one thought of "the ether" as a scalar quantity rather than a vector quantity (and why not?), then you would get the same result from Michaelson Morley as you currently get. (To get a grasp of a scalar "ether" think of a 3-D sandpaper throughout space, not moving. No matter which way you go, you get the same frictional drag.)