Cryonics (from Greek κρύος 'kryos-' meaning 'cold') is the low-temperature preservation of animals and humans who cannot be sustained by contemporary medicine, with the hope that healing and resuscitation may be possible in the future.
Cryopreservation of people or large animals is not reversible with current technology. The stated rationale for cryonics is that people who are considered dead by current legal or medical definitions may not be dead according to the more stringent information-theoretic definition of death. It is proposed that cryopreserved people might someday be recovered by using highly advanced technology.
Cryonics procedures ideally begin within minutes of cardiac arrest, and use cryoprotectants to prevent ice formation during cryopreservation. There are presently three cryonics service providers: Alcor and Cryonics Institute based in the US, and KrioRus in Russia.
A central premise of cryonics is that long-term memory, personality, and identity are stored in durable cell structures and patterns within the brain that do not require continuous brain activity to survive. This premise is generally accepted in medicine; it is known that under certain conditions the brain can stop functioning and still later recover with retention of long-term memory. Brain structures encoding personality and long-term memory persist for some time after legal death, these structures are preserved by cryopreservation, and future technologies that could restore encoded memories to functional expression in a healed person are theoretically possible. At present, only cells, tissues, and some small organs can be reversibly cryopreserved.
A moral premise of cryonics is that all terminally ill patients should have the right, if they so choose, to be cryopreserved.
Obstacles to success
Long-term cryopreservation can be achieved by cooling to near 77.15 Kelvin (approximately -196.01°C), the boiling point of liquid nitrogen. It is a common mistaken belief that cells will lyse (burst) due to the formation of ice crystals within the cell, since this only occurs if the freezing rate exceeds the osmotic loss of water to the extracellular space. However, damage from freezing can still be serious; ice may still form between cells, causing mechanical and chemical damage. The difficulties of recovering complex organisms from a frozen state have been long known. Attempts to recover large frozen mammals by simply rewarming were abandoned by 1957.
When used at high concentrations, cryoprotectants stop ice formation completely. Cooling and solidification without crystal formation is called vitrification. The first cryoprotectant solutions able to vitrify at very slow cooling rates while still being compatible with tissue survival were developed in the late 1990s by cryobiologists Gregory Fahy and Brian Wowk for the purpose of banking transplantable organs. This has allowed animal brains to be vitrified, warmed back up, and examined for ice damage using light and electron microscopy. No ice crystal damage was found.
Those who believe that revival may someday be possible generally look toward advanced bioengineering, molecular nanotechnology, or nanomedicine as key technologies. Revival would require repairing damage from lack of oxygen, cryoprotectant toxicity, thermal stress (fracturing), freezing in tissues that do not successfully vitrify, and reversing the effects that caused the patient's death. In many cases extensive tissue regeneration would be necessary.
It has sometimes been written that cryonics revival will be a last in, first out process. People cryopreserved in the future, with better technology, may require less advanced technology to be revived because they will have been cryopreserved with better technology that caused less damage to tissue. In this view, preservation methods would get progressively better until eventually they are demonstrably reversible, after which medicine would begin to reach back and revive people cryopreserved by more primitive methods. Revival of people cryopreserved by early cryonics technology may require centuries, if it is possible at all. The "last in, first out" view of cryonics has been criticized because the quality of cryopreservation depends on many factors other than the era in which cryopreservation takes place.
Legally, cryonics patients are treated as deceased persons. Cryonics providers tend to be treated as medical research institutes. In France, cryonics is not considered a legal mode of body disposal; only burial, cremation, and formal donation to science are allowed. However, bodies may legally be shipped to other, less restrictive countries for cryonic freezing.
Cryonics views legal death as a perhaps sometimes pragmatically useful but fundamentally flawed and usually incorrect diagnosis which has no theoretical or philosophical justification. "Legal death" is usually just another name for a set of symptoms that have proven resistant to treatment by contemporary medicine. If death is not an event that happens suddenly when the heart stops (and "legal death" is often pronounced) this raises philosophical questions about what exactly death is. In 2005 an ethics debate in the medical journal, Critical Care, noted “…few if any patients pronounced dead by today’s physicians are in fact truly dead by any scientifically rigorous criteria.” Ethical and theological opinions of cryonics tend to pivot on the issue of whether cryonics is regarded as interment or medicine. Many followers of Nikolai Fyodorovich Fyodorov, a Russian Orthodox Christian philosopher, see cryonics as an important step in the Common Cause project which he originated.
At the request of the American Cryonics Society, in 1995, philosopher Charles Tandy,  authored a paper entitled “Cryonic-Hibernation in Light of the Bioethical Principles of Beauchamp and Childress.” Tandy considered the four bioethical factors or principles articulated by philosophers Beauchamp and Childress as they apply to cryonics. These four principles are 1) respect for autonomy; 2) nonmaleficence; 3) beneficence; and 4) justice. Tandy concluded that in respect to all four principles “biomedical professionals have a strong (not weak) and actual (not prima facie, but binding) obligation to help insure cryonic-hibernation of the cryonics patient.”
In 1922 Alexander Yaroslavsky, member of Russian immortalists-biocosmists movement, wrote "Anabiosys Poem". However, the modern era of cryonics began in 1962 when Michigan college physics teacher Robert Ettinger proposed in a privately published book, The Prospect of Immortality, that freezing people may be a way to reach future medical technology. (The book was republished in 2005 and remains in print.) Even though freezing a person is apparently fatal, Ettinger argued that what appears to be fatal today may be reversible in the future. He applied the same argument to the process of dying itself, saying that the early stages of clinical death may be reversible in the future. Combining these two ideas, he suggested that freezing recently deceased people may be a way to save lives. In 1955 James Lovelock was able to reanimate rats frozen at 0 Celsius using microwave diathermy.
Slightly before Ettinger’s book was complete, Evan Cooper (writing as Nathan Duhring) privately published a book called Immortality: Physically, Scientifically, Now that independently suggested the same idea. Cooper founded the Life Extension Society (LES) in 1964 to promote freezing people. Ettinger came to be credited as the originator of cryonics, perhaps because his book was republished by Doubleday in 1964 on recommendation of Isaac Asimov and Fred Pohl, and received more publicity. Ettinger also stayed with the movement longer.
DARPA currently funds several research projects aimed on sending the human body into a state of suspended animation, essentially “shutting down” the heart and brain until proper care can be administered that can be regarded as a step to cryopreservation of humans.
Cryonicists are predominantly nonreligious white males; according to the New York Times, among living cryonicists, men outnumber women by about three to one. As of 2015, Alcor has 104 male patients and 39 female patients. However, cryonics pioneer Bob Nelson claims the majority of cryonics patients are women.
In 2015 Du Hong, a 61-year-old female writer of children's literature, became the first known Chinese person to be cryopreserved.
In popular culture
Suspended animation is a popular theme in science fiction and fantasy settings, appearing in comic books, films, literature, and television. A survey in Germany found that about half of the respondents were familiar with cryonics, and about half of those familiar with cryonics had learned of the subject from films or television.
- Famous people who are cryopreserved
Among cryopreserved are James Bedford, Dick Clair, L. Stephen Coles (in 2014), Thomas K. Donaldson, FM-2030, Hal Finney (in 2014), Jerry Leaf, and John-Henry Williams. Baseball player Ted Williams is the best known cryopreserved patient.
- Famous people associated with cryonics but who were not cryopreserved
The urban legend suggesting Walt Disney was cryopreserved is false; he was cremated and interred at Forest Lawn Memorial Park Cemetery. Robert A. Heinlein, who wrote enthusiastically of the concept in The Door into Summer (serialized in 1956), was cremated and had his ashes distributed over the Pacific Ocean. Timothy Leary was a long-time cryonics advocate and signed up with a major cryonics provider, but he changed his mind shortly before his death and was not cryopreserved.
- Chemical brain preservation
- Indefinite lifespan
- Information-theoretic death
- Life extension
- Suspended animation
- Vitrification in cryopreservation
- McKie, Robin (13 July 2002). "Cold facts about cryonics". The Observer. Retrieved 1 December 2013.
Cryonics, which began in the Fifties, is the freezing - usually in liquid nitrogen - of human beings who have been legally declared dead. The aim of this process is to keep such individuals in a state of refrigerated limbo so that it may become possible in the future to resuscitate them, cure them of the condition that killed them, and then restore them to functioning life in an era when medical science has triumphed over the activities of the Banana Reaper.
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The extant literature supports but does not prove the hypothesis that cryonics is a feasible method of saving the lives of people who would otherwise certainly die.
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This is the first evidence of preservation of memory after cryopreservation (vitrification or slow freezing).
- Mayford M, Siegelbaum SA, and Kandel ER (April 10, 2012). "Synapses and Memory Storage" (PDF). Cold Spring Harb Perspect Biol 4: a005751. doi:10.1101/cshperspect.a005751.
Procedural and declarative memories differ dramatically. They use a different logic (unconscious vs. conscious recall) and they are stored in different areas of the brain. Nevertheless, these two disparate memory processes share several molecular steps and an overall molecular logic. Both are created in at least two stages: one that does not require the synthesis of new proteins and one that does. In both, short-term memory involves covalent modification of preexisting proteins and changes in the strength of preexisting synaptic connections, whereas long-term memory requires the synthesis of new proteins and the growth of new connections. Moreover, both forms of memory use PKA, mitogen-activated protein kinase (MAPK), CREB-1, and CREB-2 signaling pathways to convert short-term to long-term memory. Finally, both forms appear to use morphological changes at synapses to stabilize long-term memoryline feed character in
|quote=at position 58 (help)
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We know that secondary memory does not depend on continued activity of the nervous system, because the brain can be totally inactivated by cooling, by general anesthesia, by hypoxia, by ischemia, or by any method, and yet secondary memories that have been previously stored are still retained when the brain becomes active once again. Therefore, secondary memory must result from some actual alterations of the synapses, either physical or chemical.
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Each patient is a free agent entitled to full explanation and full decision-making authority with regard to his medical care. John Stuart Mill expressed it as: `Over himself, his own body and mind, the individual is sovereign.' The legal counterpart of patient autonomy is self-determination. Both principles deny legitimacy to paternalism by stating unequivocally that, in the last analysis, the patient determines what is right for him. ... If the [terminally ill] patient is a mentally competent adult, he has the legal right to accept or refuse any form of treatment, and his wishes must be recognized and honored by his physician.
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