Cryonics

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Cryonics is the practice of preserving organisms, or at least their brains, for possible future revival by storing them at cryogenic temperatures where metabolism and decay are almost completely stopped.

A person held in such a state (either frozen or vitrified) is said to be cryopreserved. Barring social disruptions, a perfectly vitrified person can be expected to remain physically viable for about 10,000 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.

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.

Cryonics has traditionally been dismissed by mainstream cryobiology, of which it is arguably a part. The reason generally given for this dismissal is that the freezing process creates ice crystals, which damage cells and cellular structures, so as to render any future repair impossible. Cryonicists have long argued, however, that the extent of this damage was greatly exaggerated by the critics, presuming that some reasonable attempt is made to perfuse the body with cryoprotectant chemicals (traditionally glycerol) that inhibit ice crystal formation. Anti-cryonics cryobiologists quite commonly will claim that tissues undergo total destruction and that the cells burst from the inside-out due to crystal growth. Both of these oft-cited claims are known to be false, however. While glycerol-based freezing does create a lot of ice crystals, the damage done is nowhere near total, and cells do not burst from the inside out. Actually, it is only the water in the spaces between cells that crystalizes, not the water within. Damage is still extensive, however, and many (perhaps even most) cryonicsts will readily admit that traditional glycerol-based freezing is a long-shot at survival. But a long-shot, they would say, is better than no shot at all.

Recently, however, dramatic breakthroughs in the science of cryobiology have made the ice crystal objection essentially moot. Around the turn of the millenium, Greg Fahy and Brian Wowk, of Twenty-First Century Medicine, virtually eliminated ice crystal formation using new cryoprotectants that allow vitrification, causing the cooled tissue to form a glass. In a cooled substance that is vitrified, rather than frozen, the molecules remain in a disordered state, as in a fluid, rather than forming an ordered crystalline structure. Alcor Life Extension Foundation, the world's largest cryonics provider, has since been using these cryoprotectants, along with a new, faster cooling method, to vitrify whole human brains. They continue to use the less effective glycerol-based freezing for patients who opt to have their whole bodies preserved, since vitrification of an entire body is beyond current technical capabilities (although Alcor says they have a whole-body vitrification method under development). The only other full-service cryonics provider in the world, the Cryonics Institute, is currently testing its own vitrification solution.

The biggest drawback to current vitrification technology is the large-scale fracturing of the brain that occurs, a result of cooling to a temperature significantly below the glass transition temperature of about -125�C. Currently, brains are cooled to -196�C, the temperature of liquid nitrogen, for long-term storage. This is mostly a cost issue, not one of technological feasibility: cryogenic freezers capable of maintaining a brain at the required temperature exist now, but are too expensive to be practical. All that is needed for Alcor to vitrify with very little fracturing, and possibly none at all, is an inexpensive long-term cryogenic storage system that can maintain a brain at a temperature somewhat below the glass transition temperature, but high enough to avoid the fracturing, at around -150�C. Alcor is currently working on such a storage system, based on technology developed by, again, Twenty-First Century Medicine. Alcor believes, however, that even before such a storage system is deployed, their current vitrification method is far superior to traditional fracture-free glycerol-based freezing, since the vitrification fractures are very clean breaks, and the loss of neurological structure is still less than that caused by ice formation, by orders of magnitude.

Critics sometimes object to cryonics because, they claim, the patients are dead, and thus cannot ever be revived. Such objections, however, assume what they seek to prove, and only hold if cryonics patients really are dead. But it is impossible to say, at this point, whether they are or not. All we can really say is that they have been declared legally dead by a qualified medical doctor. But as any such doctor can tell you, a declaration of legal death does not mean that life has suddenly ended�death is a gradual process, not a sudden event. Rather, legal death is a declaration by medical personnel that there is nothing more they can do to save the patient. What we do know is this: if cryonics procedures begin very shortly after legal death is declared, then ischemic damage due to lack of blood flow is very minimal. Such a patient can have their circulation artificially restored via CPR, and can be perfused with cryoprotectant quite effectively. Although they are legally dead, such patients are still biologically alive. This is true to the extent that a general anesthetic is required to maintain unconsciousness during the procedure.

Indeed, the definition of "death" has changed over the years with the advance of medicine, and there is every reason to presume it will continue to do so, and patients currently unrevivable (legally dead) may be revivable in the future. This possibility is the basis for cryonics. Thus, cryonicists generally reject the idea that they are trying to "raise the dead", viewing their procedures instead as highly experimental medical procedures, whose efficacy is yet to be either demonstrated or refuted.

Even assuming perfect cryopreservation techniques, many cryonicists would still regard eventual revival as a long shot. In addition to the many technical hurdles that remain, the likelihood of obtaining a good cryopreservation is not very high because of logistical problems. The likelihood of the continuity of cryonics organizations as businesses, and the threat of legislative interference in the practice, don't help the odds either. Most cryonicists, therefore, regard their cryopreservation arrangements as a kind of medical insurance�not certain to keep them alive, but better than no chance at all and still a rational gamble to take.

While cryopreservation arrangements can be expensive (currently ranging from $28,000 to $120,000), most cryonicists pay for it with life insurance. The elderly, and others who may be uninsurable for health reasons, will often pay for the procedure through their estate. Others simply invest their money over a period of years, accepting the risk that they might die in the meantime. All in all, cryonics is affordable for the vast majority of those in the industrialized world who really want it, especially if they make arragements while still young.

Historically, cryonics began in 1962 with the publication of The Prospect of Immortality by Robert Ettinger. In the late 1960s and 1970s, some early cryonics organizations began to perform cryopreservations. Two such organizations went bankrupt, allowing their patients to thaw out. This was a greatly demoralizing experience for the cryonics community as a whole, and cryonics organizations have since developed much more effective long-term financial policies (for instance, funding must be in place before legal death, and must not be left to the family after legal death).

During the 1980s, the problems associated with crystallization became better appreciated, and the emphasis shifted from whole body to brain-only or "neuropreservation", on the assumption that the rest of the body could be regrown, perhaps by cloning of the person's DNA or by using embryonic stem cell technology. The primary goal now is to preserve the information contained in the structure of the brain, on which memory and personal identity depends. Damage caused by freezing and fracturing is thought to be potentially repairable in the future, using nanotechnology, which will enable the manipulation of matter at the molecular level.

Some cryonicists question Alcor's emphasis on the brain, arguing that there is no particular reason to suggest that the mechanical structure of the brain is wholly responsible for personal identity and memories. Partly for this reason, and partly for reasons of public relations, the Cryonics Institute preserves only whole bodies. Supporters of neuropreservation counter that everything we know about the brain indicates that it is very nearly the sole carrier of all our identity-critical information. Spinal cord injury victims, organ transplant patients, and amputees, for instance, appear to retain their personal identity and memories.

If Alcor is successful in their attempt to develop a whole body vitrification procedure, it is possible that neuropreservation will lose some of its predominance, and whole body preservations may enjoy a come-back. In addition, as vitrification methods improve, revival without nanotechnology looks more and more feasible, and so the importance of nanotechnology to the cryonics movement may begin to decrease.

See also: Interstellar travel, Biostasis, Immortality Institute

External links


References

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