Questions About Speed of Light & Time

[jtbell]

why does traveling faster or equivelent than light always come up with cooky answers?

Look at almost any relativistic equation and you'll find a factor of

[tex]\frac {1}{\sqrt {1 - v^2 / c^2}}[/tex]

in there somewhere (possibly buried inside some variable). As v approaches c, this approaches infinity, and for v > c it gives an imaginary number. People have played around with trying to make sense out of these imaginary numbers for real physical quantities, but so far there is no actual experimental evidence for any of this; it's just speculation.

For a more "physical" answer rather than a "mathematical" one, imagine pushing on an object to accelerate it towards the speed of light. In relativity theory (and as has been verified over and over again in high-energy particle accelerators), as you do more and more work on the particle, the "gains" in terms of speed diminish. Each additional joule of work gains you less and less additional speed, and in the limit as the object's speed approaches the speed of light, the amount of work necessary to make it go even a tiny bit faster approaches infinity. In other words, just to make something go at the speed of light would require an infinite amount of work (energy).