The Science of Cryonics
FirstScience looks at the present science behind cryonics: "cryonically preserving a body, or a brain, after death doesn't actually involve freezing - at least not anymore. The problem with freezing is that the structure and growth of ice crystals in cells is very damaging - anyone who has eaten dried-out food damaged by freezer burn has direct experience with the destructive effects of ice crystals. To avoid ice formation, cryonics has been moving towards a process called vitrification. To vitrify a body, a machine replaces blood with a solution containing a high concentration of chemicals called cryoprotectants that chill the body while preventing ice formation. ... The water molecules don't have time to form the rigid crystalline structure of ice, but instead maintain a fairly random arrangement that is referred to as a glass-like state. After vitrification, cryonics labs suspend people in liquid nitrogen at temperatures below -180 degrees C." Debates of the merits of the science usually devolve to "we can't restore cryopreserved people now," which rather misses the point. Our knowledge of physics and biochemistry show no roadblocks to the development of a future technology capable of restoring cryopreserved people - and they have all the time in the world to wait.
Link: http://www.firstscience.com/home/articles/humans/suspending-life-the-science-of-cryonics_14148.html