From Bloody Disgusting:
Ridley enters and sees our tape recorders.
"Look at this technology. Jesus Christ. 40 years ago when Kirk said 'Beam me up, Scotty' we used to think that was fucking ridiculous, remember? Seriously, that’s been 40 years and then when he says the 'disintegration' of his matter into the 'reintegration' of his matter in the next space, that right there is light speed. So they touched on light speed. I’ve talked to NASA about this and they’ve said that’s light speed. So 'Can you do it?' They said 'Yeah. Have you got seven glasses of water?' I go 'Not the seven glasses of water trick, please.' There were all scientists in the room and he started to explain to me the relativity and the speed of light. 'Can you do it?' 'Yeah.' He said the only barrier is 'us.' He said, I can mathematically explain how, but we haven’t gotten there with that."
Actual Prometheus spoilers and hints, discussion of the film's evolution from Scott's idea called Alien: Paradise, and the moment when he forgets Jean-Pierre Jeunet's name (you know, "the Frenchman") in the full chat courtesy of Bloody Disgusting, if you dare...