Cryonics

Cryonics is the practice of preserving humans and pets by storing them at cryogenic temperatures -- where metabolism and decay are almost completely stopped -- for the purpose of future reanimation. Cryonics is not a widespread medical practice and is viewed with skepticism by most scientists and doctors today. However, there is a high representation of scientists among cryonicists. It was not long ago that most scientists viewed the idea of cloning with skepticism. Support for cryonics is based on controversial projections of future technologies and of their ability to enable molecular-level repair of tissues and organs.

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Viruses, bacteria, sperm/eggs, embryos at early stages of development, insects, and even small animals (small frogs, some fish) can be cryogenically frozen, preserved for an indefinite time (as long as low temperature is maintained) and then thawed and returned to a living state. Large animals or organs (a few centimeters and larger) cannot be safely frozen because removing heat via thick tissue by natural thermoconductivity becomes so slow that ice microcrystals grow big enough to damage cell membranes. This problem can be overcome by the use of cryoprotectants that allow water to vitrify rather than freeze, preventing ice crystals from forming, but only at the expense of toxicity from the cryoprotectants.

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A cryogenically preserved organism, whether frozen or vitrified, is said to be cryopreserved. Barring social disruptions, cryonicists believe that a perfectly vitrified person can be expected to remain physically viable for at least 30,000 years, after which time cosmic ray damage is thought to be irreparable. Many scientists in the field, most notably Ralph Merkle and Brian Wowk, hold that molecular nanotechnology has the potential to extend even this limit many times over.

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To its detractors, the justification for the actual practice of cryonics is unclear, given the primitive state of preservation technology. Advocates counter that even a slim chance of revival is better than no chance. In the future, they speculate, not only will conventional health services be improved, but they will also quite likely have expanded even to the conquering of old age itself (see links at the bottom). Therefore, if one could preserve one's body (or at least the contents of one's mind) for, say, another hundred years, one might well be resuscitated and live indefinitely long. While technology does not permit revival today, it does, they argue, preserve the detailed structure of the brain very well, making the attempt at preservation a rational, if uncertain, bet on the future. Critics of the field disagree, contending that cryonics, while an interesting technical idea and a valid subject for research, is currently little more than a pipedream, that current "patients" will never be successfully revived, even in the distant future, and that decades of research, at least, must occur before cryonics is to be a legitimate field with any hope of success. Responses to these criticisms note that they do not address what advocates regard as the central issue: whether molecular-level tissue repair will, in fact, prove to be feasible.

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Probably the most famous cryopreserved patient is Ted Williams. The popular urban legend that Walt Disney was cryopreserved is false; he was cremated, and interred at Forest Lawn Memorial Park Cemetery. Robert Heinlein, who wrote enthusiastically of the concept, was cremated and his ashes distributed over the Pacific Ocean. Timothy Leary was a long-time cryonics advocate, and signed up with a major cryonics provider. He changed his mind, however, shortly before his death, and so was not cryopreserved.

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A cryopreserved person is sometimes whimsically called a corpsicle (a portmanteau of "corpse" and "popsicle"). This term was first used by science fiction author Larry Niven, who credits its formulation to Frederick Pohl.

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Cryogenic: REDIRECT Cryogenics...

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