h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Although your environmental concerns are still very relavent, I feel I can shed light on the light speed problem.

Most scientists agree that matter is incapable of being accelerated to light speed without being distorted beyond recognition.

However it is not necessary to attain such high speed to prove the time and spac3 thing that Einstine first described. In the 60's, two very accurate atomic clocks were synchronized at a singular point in timespace, one clock was put on a fast aaircraft and flown at high speed while the other remained "stationary". When the two were compaired a distinct discrepancy was found.

Less time has passed for the people who traveled faster.