Seconds You Could Stay in Space without Injury
(Guardians of the Galaxy Spoilers ahead)
There's a common misconception that exposure to the vacuum of space would cause immediate death. Guardians of the Galaxy came out last weekend and there's one scene in which Peter Quill floats through space for some time without any protection . That scene has been getting some attention prompting James Gunn, the film's director, to debunk the idea that we'd die in just a few seconds. There's quite a bit of evidence there to support him too, without even having to fall back on the excuse that it's "just a movie".
Chief among those is the fact that it takes some time for people to lose consciousness from a lack of oxygen. Trained divers can hold their breath for minutes, and a lack of oxygen in space would knock you out, sure, but you'd still have to exhaust all the oxygen that's still in your blood. While space is famously very, very cold, there's also nothing besides radiation to carry heat away from your body, so you wouldn't quickly freeze either. Most people seem to think the real threat would be the lack of pressure, but even that isn't an instant killer. There've been more than a few accidents and experiments wherein mammals were exposed to hard vacuums, and they typically survive. Your circulatory system is, contrary to popular belief, a closed system. Your blood wouldn't boil off, and you wouldn't explode Total Recall-style. Instead, you'd become something of a balloon and expand slightly. That's certainly not good for you, but it's survivable.
In fact, if there's anything the film got really wrong it's that neither Gamora nor Star-lord soiled themselves. And yes, that's totally a thing.
Bottom pic: 2001, via MGM