Okay, this is not the first time that a guy stuck his hand into liquid nitrogen in front of a camera, but the use of high quality cameras and a clear container for the experiment make for some interesting visuals.
The principal that protects Theodore Gray’s hand from a liquid cold enough to snap freeze it is the Leidenfrost effect. You can see it in action if you splash a few droplets of water on a hot plate. With the water on the hot plate, you see what is happening in this video… in reverse. The hot plate is really hot, the water is cool – so when it falls onto the hot plate it creates an insulating layer of gas around itself.
In this experiment, the hand becomes the hot plate. In comparison to the liquid nitrogen, which is somewhere in the vicinity of −195 °C or −320 °F, the hand is extremely hot. Thus, the hand instantly vaporizes the liquid nitrogen with which it comes into contact and nitrogen gas keeps delicate human flesh from being frozen into oblivion. [PopSci via Nerd Approved]
Hand vs. Liquid Nitrogen, the First Time
While the PopSci video makes for interesting viewing, I preferred a clip that did the rounds on YouTube about a year ago. The video quality is not quite as good, but YouTube user NurdRage demonstrated greater faith in science by keeping his hand in the container for a little bit longer.