FAQ: General Questions

Cryonics (from Greek kryos meaning icy cold) is the low-temperature preservation of humans who can no longer be sustained by contemporary medicine, in the expectation they can be healed and resuscitated in the future using more advanced medical technologies. Cryopreservation of people is not reversible with current technology, and is today only practiced following pronouncement of legal death. The rationale for cryonics is that current medical and legal definitions of death are inaccurate and that cryopreserved patients who do not meet the more stringent information-theoretic definition of death retain sufficient biological/neurological structure to be restored to full physical and mental health using advanced future technologies.

Except for embryos, no human has ever been revived from temperatures far below freezing. Cryonics patients are cared for in the expectation that future technology, especially molecular nanotechnology, will be available to reverse damage associated with the cryonics process.

Before cryonics procedures can begin under present law, a patient must be legally dead. Legal death is a determination made by a legally qualified authority that a patient whose heart or brain has stopped normal functioning cannot benefit from further medical care. The details of the determination depend upon care that is available, disease prognosis, and patient wishes (e.g. do-not-resuscitate order).

The legal status of cryonics care is after-death care. There is no legal ambiguity. However, philosophically, cryonics can be regarded as an attempt to continue care in hope of future resuscitation even after today’s medicine declares that it can do no more to resuscitate someone. Ethically, morally, and spiritually, cryonicists believe that cryopreserved people should be regarded as unconscious, with their final prognosis to be determined by future medicine.

The common dictionary definition of “death” is “a permanent cessation of all vital functions.” If a cryopreserved person is in fact awakened in the future then there has been no permanent cessation of vital functions (only a temporary cessation of vital functions) and therefore, by this definition, if cryonics works and a cryopreserved person is awakened in the future that person was never dead according to the common dictionary definition of “death,” even though they were legally dead.

Physical conditions corresponding to death change over time. In the past, if someone stopped breathing they were declared dead. Later, death became cessation of heartbeat. Today, a stopped heart can often be restarted, or life sustained even without a working heart. As medical technology gets better, the biology of death changes.

Given the gulf between today’s medical technology and the expected capabilities of future medical technology, the gap between present and future medical criteria for determination of death is likely to persist for some time (The future of death. J Crit Care. 2014;29(6):1111-3).

Under ideal conditions, cryonics procedures can begin shortly after the heart stops beating. Blood circulation and breathing can be artificially restored, keeping cells of the brain and body alive and functioning during the early stages of cryopreservation. Cryonics may also be performed after longer periods of legal death while retaining the possibility of future repair and resuscitation. Until information theoretic death occurs, there is reason to believe a cryopreserved person might be resuscitated in the future.

Cryonics procedures should ideally begin within the first one or two minutes after the heart stops, and preferably within 15 minutes. Longer delays place a greater burden on future technology to reverse injury and restore the brain to a healthy state, and make it more uncertain that the correct original state can be determined. Exactly when such restoration is no longer feasible is a matter of some debate and could be many hours. The greatest impact of delay is that it degrades the circulatory system, reducing the ability to circulate chemicals that reduce freezing injury. For further information, see the FAQ question “Doesn’t the brain die after 4 to 6 minutes without oxygen?,” the article “Cardiopulmonary Support in Cryonics,” and the “Cases without Cardiopulmonary Support” section of Alcor Procedures.

The most effective way of reducing delays and getting the highest quality cryopreservation is to relocate to cooperative hospice care near Alcor (see the FAQ question “What can I do to optimize my chances of being cryopreserved under good conditions?”).

Cold preservation (cryopreservation) is not yet reversible with present technology, but this says nothing about the abilities of future technology. What is “fatal” varies from place to place and time to time depending on available medical technology. Future medical capabilities should be able to heal and cure in cases that today would be considered hopeless, just as today’s medicine would be viewed as miraculous in past centuries.

That depends on when they are cryopreserved, the specific details of how well they are cryopreserved, and how rapidly future medical technologies, particularly molecular nanotechnology, are developed. Cryonics technology is always improving; it is better now than it was in 2000, which was better than it was in 1990, which in turn was much better than the crude methods used on the first cryonics patients in the late 1960s. Eventually a time will come when human suspended animation will be perfected. In other words, it will be possible to routinely turn people “off” and “on” for medical time travel, space travel and other purposes. As progress continues, it will then become possible to recover people preserved at earlier times, with less perfect methods and greater degrees of injury.

Some think it will take centuries before patients can be revived, while others think the accelerating pace of technological change might so rapidly transform our world that decades would suffice. Alcor is planning for however long it might take.

The short answer is “Alcor will revive them.”

The third item in Alcor’s mission statement is: “Eventually restore to health and reintegrate into society all patients in Alcor’s care.”

Reviving the patients is also required by Alcor’s contracts with members: “When, in Alcor’s best good faith judgement, it is determined that attempting revival is in the best interests of the Member in cryopreservation, Alcor shall attempt to revive and rehabilitate the Member.”

Reviving the patients is also a duty of the Alcor Patient Care Trust: “At such time as Alcor deems that repair and revival of the Patients is feasible, the Trust shall expend whatever amounts of money are necessary to revive the Patients and reintroduce them to society, as long as on-going care of the Patients remaining in biostasis is not endangered. It is the intent of the Trust that such repair and revival proceed in such manner that ongoing Trust earnings reasonably can be predicted to provide for the eventual repair and revival of all Patients.”

Financially, the Patient Care Trust should grow in real value over time — compound interest should eventually produce sufficient assets to cover the costs of revival. At the same time, as technology progresses the cost of reviving patients should decrease over time. Eventually, the increasing funds available in the PCT should be sufficient to pay the costs of reviving and reintegrating patients into society.

Socially, Alcor is a community. Some members of this community are alive and healthy, while others have been cryopreserved. This community forms an interconnected network of friendships and close ties. At any point in time the healthy members of this network have friends, relatives and loved ones in cryopreservation and will seek to revive them. Once revived, those members will in turn have other friends in cryopreservation, and they will in turn seek to revive them.

The plan is not for “them” to revive us. The plan is that we, the Alcor community, will revive ourselves.

There is no point in prolonging life if the result will be illness and debilitation. People are now living longer, healthier lives than their grandparents, and their children will live longer still. Eventually, aging itself will be a treatable, reversible condition as medicine attains full control of the human body at the molecular level. By the time it becomes possible to revive cryonics patients, especially today’s cryonics patients, biological aging as we know it today will not exist. In the 19th century, 30% of people living in Paris died of “consumption.” Today almost no one in the industrialized world even knows what “consumption” is.

This depends on many factors, including when you are cryopreserved, how long you spend in cryopreservation, how long it takes to develop life-extending technologies, and whether your friends or family are themselves interested in being cryopreserved. It cannot be reliably predicted how many decades (or generations) it might take to develop the technologies needed to substantially lengthen lifespans or to revive patients from cryopreservation. You can increase your chances of seeing your current friends and family in the future by interesting them in cryonics or by making friends within the cryonics community. At any rate, if cryonics works it will give you the greatest opportunity of all — the ability to make new friends (including, perhaps, with your own descendants).

The practice of cryonics is justified by three facts:

  1. Cells and organisms need not operate continuously to remain alive. Many living things, including human embryos, can be successfully cryopreserved and revived. Adult humans can survive cardiac arrest and cessation of brain activity during hypothermia for up to an hour without lasting harm. Other large animals have survived three hours of cardiac arrest near 0°C (+32°F ) (Cryobiology 23, 483-494 (1986)). There is no technical reason based on known physical law why such states of “suspended animation” could not be extended indefinitely at even lower temperatures (although the technical obstacles are enormous).
  2. Existing cryopreservation techniques, while not yet reversible, can preserve the fine structure of the brain with remarkable fidelity. This is especially true for cryopreservation by vitrification. The observations of point (a) make clear that survival of structure, not function, determines survival of the organism.
  3. It is now possible to foresee specific future technologies (see “A Cryopreservation Revival Scenario using Molecular Nanotechnology“) that will one day be able to diagnose and treat injuries right down to the molecular level. Such technology could repair and/or regenerate every cell and tissue in the body if necessary. For such a technology, any patient retaining inferable brain structure (the physical basis of their mind) will be viable and recoverable.

That is the argument for why cryonics should work, even though it is not reversible today.

It should also be realized based on point 3 that most people who have just been declared legally dead today will merely be in cardiac arrest to future physicians, and will be “coded” for resuscitation. Today’s limit of 4 to 6 minutes for resuscitation without brain injury will likely expand to an hour or more in the future. That is why people are cryopreserved even if prompt cardiopulmonary support is not possible.

Yes. When carried out under favorable conditions, both current evidence and current theory support the conclusion that cryonics has a reasonable chance of working. That said, not all cryopreservations are carried out under favorable conditions. The degree to which cryonics is successful for a particular patient will depend on how much of the patient’s original memory and personality survives the cryopreservation and restoration process.

Assuming future medical capabilities are as effective as we expect, complete molecular repair and tissue regeneration should permit recovery of perfect health after any injury other than complete physical destruction. Unlike medicine today, which can leave a patient alive but suffering from chronic and incurable physical or neurological deficits, mature medical capabilities based on molecular repair should be able to cure almost all medical conditions — with the notable exception of permanent memory loss. Even here, it is important to distinguish between (1) loss of memory caused by failure of the retrieval mechanisms (which could eventually be cured), and (2) loss of memory caused by obliteration of the memory trace itself (which even future medical technology would not be able to repair).

Survival of your memories and personality depend on the extent of survival of brain structures that store your memories and other identity-critical information. While cryonics under apparently ideal conditions results in good preservation of brain structure and information, cryonics under non-ideal conditions happens all too frequently and is more problematic. A major complication is the fact that today’s legal and medical systems, along with the general public, do not regard cryonics patients as people worthy of protection. This could change in the future (particularly if we are successful in explaining the value and scientific merit of cryonics), but the quality of today’s cryopreservations are adversely impacted more by social and legal factors than by technical ones.

It cannot be reliably known with present scientific knowledge how a given degree of preservation would translate to a given degree of memory retention after extensive repair, but sophisticated future recovery techniques using advanced technology might allow for memory recovery even after damage that today might make many think there was little room for hope [see Cryonics, Cryptography and Maximum Likelihood Estimation]. Our ability to judge when information is truly destroyed has been proven incorrect on more than one occasion: for example, the information loss apparently caused by paper shredders can and has been reversed, to the surprise and great dismay of those who did the shredding. Recovered information about memories could help guide the nanomedical repairs of the neuronal structures in the brain that encode those memories. Cryonics takes the most conservative approach by seeking to cryopreserve patients even when conditions are less than ideal and the risk of amnesia might be increased by some unknown extent.

For futher discussion of the problem of identity recovery after major brain repair, see the articles Cryonics, Cryptography, and Maximum Likelihood Estimation, Molecular Repair of the Brain, Neural Archaeology, and Prospects of a Cure for “Death”.

To be successful, Alcor will have to keep you cryopreserved for as long as might be needed [see How will Alcor sustain itself for the duration of my cryopreservation?]. Some long-term risks are subject to mitigation strategies, such as earthquake risk (one of the reasons Alcor moved out of California). Other long-term risks, such as socio-economic disruption, are difficult to quantify.

Finally, when the time comes, Alcor will have to revive you. As explained elsewhere, this is a task to which the Alcor community is committed [see Who will revive the patients?].

The few technical articles in the scientific literature that directly address the question all conclude that cryonics, when carried out using today’s methods under favorable conditions, should work.

This observation was first made by Merkle (Molecular Repair of the Brain, footnote 24), who said “A literature search on cryonics along with personal inquiries has not produced a single technical paper on the subject that claims that cryonics is infeasible or even unlikely. On the other hand, technical papers and analyses of cryonics that speak favorably of its eventual success have been published. It is unreasonable, given the extant literature, to conclude that cryonics is unlikely to work. Such unsupported negative claims require further analysis and careful critical evaluation before they can be taken seriously.” Merkle has also written an article to explicitly address the probability that cryonics will work.

More recently, Crowley (An open letter to scientific critics of cryonics) said “Though many experts in cryogenics and other relevant fields are quoted in the media as condemning cryonics practice, none have written at greater length to explain their reasons. The closest thing to such a reason I can find is Michael Shermer’s [2001] article ‘Nano Nonsense and Cryonics,’ but the reason he gave was one that he knew at the time of writing was contrary to scientific reality, and in response to my email asking where I could learn more he recommended three authors all of whom consider cryonics technically plausible.” Shermer’s editorial has been refuted by Merkle (Cryonics and Scientific American).

Now that Robert McIntyre and Greg Fahy from 21st Century Medicine have won the Small Mammal Brain Preservation Prize for their work preserving rabbit brains, Shermer himself seems to have adopted a very different tone in his 2016 article “Can Our Minds Live Forever?” Shermer’s views have also been used as a case study in “A Skeptic’s Guide to Cryonics” (Cryonics, September 2013, pages 6-7).

Cryobiologists are scientists who specialize in cold tolerance in nature and demonstrably reversible cold preservation of cells and tissues. Cryobiologists correctly point out that cryopreservation of whole humans is not demonstrably reversible. Some cryobiologists incorrectly claim that this means that cryonics is not founded on science. This claim is incorrect because cryonics does not assume that cryopreservation can be reversed using today’s technology. The claim made by cryonics is that it is possible to preserve sufficient biological information today to permit reversal in the future with foreseeable technology. Evaluation of this proposition requires knowledge of cryopreservation methods used in cryonics, knowledge of neuroscience, and knowledge of future technologies proposed to reverse the process. Very few scientists have knowledge in all these areas. Cryobiologists, as a group, lack expertise in the future technologies that have been proposed to revive cryopreserved patients. Some individual cryobiologists have significant knowledge of these technologies. Notably, these individuals have much more favorable views of cryonics.

While the Society for Cryobiology used to have bylaws that allowed their Board of Governors to “expel members… engaged in or who promote… any practice or application of freezing deceased persons in the anticipation of their reanimation,” in 2018 the Society adopted a new Position Statement on Cryonics that says in part “Preferences regarding disposition of postmortem human bodies or brains are clearly a matter of personal choice and, therefore, inappropriate subjects of Society policy. The Society does, however, take the position that the knowledge necessary for the revival of live or dead whole mammals following cryopreservation does not currently exist and can come only from conscientious and patient research in cryobiology and medicine.”

Most people pay for cryonics with life insurance, which is what makes cryonics affordable for the average person. Since the actual cost of insurance depends on your age and health and other factors, to find out your specific cost you would need to shop for life insurance. Alcor offers two options: for whole body preservation you would need a minimum policy of $200,000, and for neuropreservation you would need a minimum policy of $80,000 (neuropreservation is explained in the Neuropreservation FAQ section.) However, you should get a greater amount of coverage to allow for cost increases between now and the time of your cryopreservation. Other funding options are available besides life insurance, including trusts, annuities, and prepaid cash or equivalent (for details see Funding Methods). Alcor members also pay annual dues, as explained in the Membership Questions section.

For the latest statistics on this, see our membership statistics page.

For the latest statistics on this, see our membership statistics page.

People may refrain for signing up for cryonics because it’s not traditional, it costs money, they’re skeptical of anything they haven’t seen work, they’re afraid of what their friends might think, they live in denial of their own risk of death, they don’t want to think about the subject, they procrastinate, they don’t like life well enough to want more of it, or they are afraid of a future in which they may be alienated from friends and family and a familiar social environment.

Typical Alcor members (if any Alcor member could be called “typical”) tend to be highly educated independent minded people who enjoy life and think cryonics has a reasonable chance of working. They pay for it with life insurance and think the future is likely to work out pretty well. They often have friends or relatives who are Alcor members. They expect Alcor to revive them using nanomedicine and expect to continue their lives with as much passion and joy as today — only with much more amazing technology.

Alcor is a 501(c)(3) non-profit organization authorized to accept anatomical donations under the provisions of the Uniform Anatomical Gift Act (UAGA) and Arizona Anatomical Gift Act (AAGA) for research purposes. These are the same state laws that govern medical schools, neurological research banks, and other scientific uses of donated tissue. Several courts have also ruled that decedents or their relatives have the right to choose cryonics based on laws that empower people to choose the disposition of their remains. For further information, read The Legal Status of Cryonics Patients.

No. Current law does not allow freedom of choice in this matter. Under current law cryopreserved humans are legally dead. Actively making a person legally dead is a crime regardless of what that person’s wishes may be. Alcor must wait for an independent authority to declare that illness or injury has caused the heart to stop, that further medical care is not appropriate, and that therefore legal death has occurred. Only after that determination is made can the cryopreservation procedures legally begin.

Misunderstandings about cryonics can sometimes lead to disputes. Today’s medical and legal practice usually pronounces a human “dead” when their heart stops beating. Alcor views its members as “dead” only after they meet the information-theoretic criterion of death, that is, only after their brain has been obliterated to the point where it is clear that inference of their memory and personality is in principle no longer possible, even by the most advanced medical technology that might be developed in future centuries. Alcor believes that cryopreservation can prevent this form of death. The purpose of cryonics is therefore to prevent dying people from dying, which is not how most people presently think about cryonics.

While Alcor members wish today’s legal, social and medical organizations would accept cryonics as a legitimate medical treatment that any terminally ill patient could choose, this is not the case. The accommodation we have reached is that Alcor members have the legal right to be cryopreserved after they are declared “legally dead,” but not before. In practice this means we can be cryopreserved after our heart has stopped beating. While far from ideal, cessation of heartbeat usually occurs at a point in time well before information-theoretic death has occurred, meaning that cryopreservation after “legal death,” but before information-theoretic death, can be a way of saving our lives.

Unfortunately, sometimes traditional practices and perceptions of death can lead to interference with a patient’s right to be cryopreserved. Hospitals will sometimes refuse to cooperate with Alcor. Grieving sons, daughters, brothers and sisters who are already feeling great stress might not understand the decision to be cryopreserved made by parents or siblings. They might not even have heard about the decision until confronted with it by Alcor staff, which can add to the shock and stress. Relatives might fight among themselves about how to respond to the cryonics arrangements, and sometimes stand to inherit significant assets if they can successfully block cryopreservation.

When anyone for any reason tries to block the timely cryopreservation of an Alcor member, Alcor has only a few options. Obviously, the best option is to try to “talk them down.” This often works, and we’ve gotten pretty good at it. When it doesn’t, we have to turn to lawyers and courts. Again, we try to negotiate a settlement, as this minimizes everyone’s risk and everyone’s costs. We’ve gotten pretty good at this, too, and are often able to avoid court cases and their costs. But when these don’t work, we have to pursue litigation. Sadly, we’ve gotten pretty good at this, as well. We must do so to fulfill our mission, to fulfill our contractual obligation to our members, and most importantly to save our member’s life. The member being cryopreserved is often a longtime friend, or an acquaintance, or friend of a friend. And every time, each one of us is thinking in the back of our minds: “What will happen when it’s my turn? What will Alcor do if someone tries to block my cryopreservation?”

And speed is critical. Once someone has been pronounced “dead”, the clock is ticking. Speed both limits the available options and makes negotiations harder. There’s no time to let upset relatives calm down, there’s no time to work out additional and possibly more complex options that somehow accommodate everyone’s concerns — things need to happen, and they need to happen quickly. Lawyers are called and told to prepare “in case we can’t negotiate an agreement.” Intransigent relatives are told that if they don’t agree to a compromise quickly they’re going to be facing a lawsuit Monday morning.

All this is done under heavy time pressure, while dealing with grief, stress, money, and a new definition of death. Given all this, it’s hardly surprising that Alcor’s name appears in litigation, and that sometimes relatives say unkind and wildly inaccurate things about us. Sometimes a public official, politician, or other person will see the noise and confusion and conclude that they can pick up some easy votes, favorable publicity, or a few dollars in book and magazine sales by attacking Alcor. This has proven to be a mistake. We take such attacks very seriously, and are forced to spend valuable time and resources in countering them. We much prefer to avoid these conflicts if at all possible.

For information about how Alcor members can help minimize the chance of hostile interference by family members or third parties, and thereby significantly reduce litigation risks, costs, and delays, see the article How to Protect Your Cryonics Arrangements from Interference by Third Parties.

In September of 1970, Linda and Fred Chamberlain, the founders of Alcor, were asked to come up with a name for a rescue team for the now defunct Cryonics Society of California (CSC). They believed that people would someday travel to the stars, so they searched through star catalogs and astronomy books, hoping to find a star that could serve as a cryonics acronym. Alcor, 80 Ursae Majoris, was precisely what they had been looking for. The name roughly fit the acronym Allopathic Cryogenic Rescue. (Allopathy, as opposed to Homeopathy, is a medical perspective wherein any treatment which improves the prognosis is valid.) It is a dim 5th magnitude star near the bright star Mizar. Alcor has been used for centuries as a test for good eyesight. If you can see Alcor, you have excellent focus and vision.