Suspending Life: The Science of Cryonics

Moments after death, some people are being preserved in very cold conditions with the hopes that future technology will be able to bring them back to life. Is this scientifically possible?

Freezing people only to revive them at a later date is a good plot device for movies such as Idiocracy, Austin Powers, or Forever Young. It may sound like science fiction but in fact over 140 people, including famous baseball player Ted Williams, have already been preserved using a technique called cryonics, where human bodies are cooled to extremely low temperatures and stored in the hope that future technology will bring them back to life. But how does cryonics actually work? Or, according to many scientists, not work?

Credit: Alcor Life Extension Foundation

This "bigfoot" Dewar is custom-designed to contain four wholebody patients and six neuropatients immersed in liquid nitrogen at -196 degrees Celsius. The Dewar is an insulated container that consumes no electric power. Liquid nitrogen is added periodically to replace the small amount that evaporates.

Preserving bodies

Supporters of cryonics are primarily concerned with preserving a person’s identity, thoughts and memories which are physically stored in the brain, under the assumption that in the future it will be possible to ‘regrow’ a new body. Therefore, at the Alcor Life Extension Foundation and the Cryonics Institute, the two biggest organizations that provide this service, people can choose to have either their entire body or only their head preserved. But 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. As cryobiologist Kenneth Storey from Carleton University in Canada explains, the secret lies in the extreme speed with which tissues can be cooled to extremely low temperatures. “If you change the temperature of a solution very, very fast—5000 to 10,000 degrees Celsius a minute—that solution will actually just stop in place.” 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.