Corrected entry: The spaceship travels approximately 14.5 times faster than the speed of light [the absolute maximum speed possible in universe]. You find that by dividing the distance to earth [3.27*10^17m] by the time they needed to arrive there [two years, four months, 18 days, 36 hours and 15 minutes], which is mentioned by David five minutes after the distance shows up.
Vader47000
2nd Oct 2012
Correction: First off, it's 3.27 x 10^14 km. And it's a science-fiction film set in the future, a genre well known for fictional technologies that enable FTL travel.
Vader47000