Star Trek fans, prepare to be disappointed. Kirk, Spock and the rest of the crew would die within a second of the USS Enterprise approaching the speed of light.
The problem lies with Einstein's special theory of relativity. It transforms the thin wisp of hydrogen gas that permeates interstellar space into an intense radiation beam that would kill humans within seconds and destroy the spacecraft's electronic instruments.
Interstellar space is an empty place. For every cubic centimetre, there are fewer than two hydrogen atoms, on average, compared with 30 billion billion atoms of air here on Earth. But according to William Edelstein of the Johns Hopkins University School of Medicine in Baltimore, Maryland, that sparse interstellar gas should worry the crew of a spaceship travelling close to the speed of light even more than Romulans decloaking off the starboard bow.
This is sort of why Santa is a myth.