Cryonics

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On the twelfth of January, 1967, a retired psychology professor named James Hiram Bedford was cooled below the temperature of life and placed in storage. He had died that day, of cancer, in California. He is still there — moved, maintained, watched over by an organization that did not exist when he was born — the first human being kept, after legal death, on the bet that legal death is not the last word. Everything cryonics asks turns on whether that bet can ever be paid.

Cryonics is the practice of preserving a legally dead person at the temperature of liquid nitrogen, roughly minus one hundred ninety-six degrees Celsius, in the hope that future medicine will be able to revive them or otherwise recover the person they were. The word that recurs in every careful description, the providers’ included, is hope. No one has been revived, and no one expects to be soon. The practice is a kind of waiting, conducted in steel and cold, and its whole intellectual life is the argument over whether the waiting could end in anything.

That argument rests on a redefinition of death. Cryonicists separate two endpoints usually treated as one. The first is clinical or legal death — the stopping of heart and breath, the pronouncement that, in law, ends a life and permits the procedures to begin. The second they call information-theoretic death: the irreversible loss of the structure, chiefly in the brain, that encodes who a person was. The two need not coincide. A heart can stop while the fine architecture of the cortex still stands, intact for some window before decay erases it. If that is so, the reasoning runs, a person pronounced dead by the older standard may not yet be dead by the newer one, and preservation begun quickly enough might catch a person still, in principle, there to catch. The inference is contested at every joint, and the length of that window — how long the structure truly lasts after the blood stops — is not something the science has settled. Time is the enemy the protocols are built against. Oxygen starvation begins degrading brain tissue within minutes, so cooling and perfusion are meant to start the moment the law allows.

What happens then is an attempt to defeat ice. Water freezing into crystals tears cells apart; straight freezing, the old method, left gross damage behind. The current approach is vitrification. The body, or the brain alone, is perfused with high concentrations of cryoprotectant chemicals — in one provider’s account, replacing more than half the water in the cells — so that on deep cooling the tissue does not freeze but solidifies into a glass, with no crystals to rupture anything. Even done well it is not clean: the glassy solid can crack under thermal stress as it cools, and the cryoprotectants that prevent the ice are themselves a problem the argument will return to. Providers offer the procedure in two forms: whole-body, the entire corpse preserved, and the cheaper neuropreservation, the head only, on the premise that the brain is the seat of the person and a future able to revive a brain could supply a body. At one large provider, more than half of the members preserved have chosen the head alone. The choice is funded, typically, by life insurance; the sums run from the tens of thousands into the low hundreds of thousands of dollars.

The movement has a founder and a founding text. Robert Ettinger, a Michigan physics teacher, argued in The Prospect of Immortality — circulated in 1962, published by Doubleday in 1964 — that the dead of the present might be the patients of the future, and that the rational course was to preserve them and wait. The book made him, by common consent, the father of cryonics. He founded the Cryonics Institute in 1976; when he died in 2011 he was himself cryopreserved and stored there. The other landmark organization, the Alcor Life Extension Foundation in Arizona, is larger and better known. Around them a small constituency has grown — a few hundred preserved, a couple of thousand with arrangements made — overlapping heavily with the transhumanist and life-extension communities, which share the conviction that death is not a fate but an engineering problem.

Here the registers must be held apart, because the strongest evidence and the strongest hope point in different directions and are easy to confuse. What laboratory cryobiology has actually shown is real and limited. The most solid viability result belongs to a kidney. The cryobiologist Greg Fahy and colleagues, with a vitrification solution refined over years with Brian Wowk, vitrified a rabbit kidney, cooled it toward minus one hundred thirty degrees, rewarmed it, transplanted it back, and watched it support the animal’s life. That is a genuine demonstration that a whole mammalian organ can be vitrified and recovered — once, for a relatively simple organ. It is also one kidney, not a brain, not a body, and not a robustly repeated result for harder organs; it does not show that a brain, still less a person, can be brought back. The field is candid about why the gap is hard to close. The vitrification solutions strong enough to suppress ice are themselves too toxic, at the needed concentrations, to let complex organs recover. Cryoprotectant toxicity is named, by cryobiologists and not only their critics, as the central barrier to reversible cryopreservation — a concession from the field itself.

The other much-cited result is the one most easily misread, and it rewards being stated precisely. Between 2016 and 2018 a technique called aldehyde-stabilized cryopreservation won both stages of a prize offered by the Brain Preservation Foundation — first for a whole rabbit brain, then for a whole pig brain. The method, developed by Robert McIntyre and Greg Fahy at 21st Century Medicine, perfuses the brain with the fixative glutaraldehyde, then a cryoprotectant, then vitrifies it. What it achieved, verified by extensive electron microscopy, was preservation of synaptic ultrastructure and three-dimensional neuronal connectivity across an entire brain — the wiring kept intact at a scale never before reached, the paper noting that “processes were easily traceable and synapses were crisp.” What it did not do is the load-bearing point. Glutaraldehyde fixes the tissue, which is to say it kills it. The Foundation that awarded the prize was blunt: the technique causes death by contemporary standards, the researchers did not revive a pig or a pig brain, and what they had made was “a very, very dead brain.” The 2015 paper claimed no viability and no revival; it presented the method as a way to bank brains for the study of their connections. This matters because it is a different road from the one cryonics suspension travels. Suspension vitrifies without fixation, leaving biological viability at least theoretically open; aldehyde stabilization trades the living tissue away to lock the structure in place. It speaks to the hope of preserving the connectome for future scanning — the mind-uploading pathway — not to the hope of thawing a living person. To merge the two is to claim more than either has earned.

Against the whole enterprise stands the scientific mainstream, which regards cryonics with deep skepticism and has often called it pseudoscience. The sharpest published critique came from the neuroscientist Michael Hendricks, who held that any suggestion of coming back to life was snake oil, and that the industry trades on a “purposeful conflation of what is theoretically conceivable with what is ever practically possible.” His substantive case bears on both hopes at once: a static map of connections lacks most of the information needed to simulate a mind, since synapses are molecular machines of thousands of proteins and much of the brain’s signaling never passes through them at all — so the wiring diagram, even preserved perfectly, would underdetermine the person it once carried. Other cryobiologists put it more mildly: people may always have hope, one said, but there is no scientific foundation supporting cryonics at this time. The fair summary is neither verdict the partisans want. No reversible cryopreservation of a whole mammalian brain or body has ever been demonstrated. The revival side of cryonics is wholly prospective — neither shown to be possible nor shown to be impossible, an unredeemed note on a science that does not yet exist.

The promise has a shadow that is not scientific but custodial, and it has already failed some of those entrusted to it. Cryonics begins only after legal death, a rule that produces a permanent tension: the cryonicist wants preservation to begin before the brain decays, but the law requires the person be dead first, and the courts have held that line. The mathematician Thomas Donaldson, facing a brain tumor he feared would destroy his brain before it could be preserved, asked California in the early 1990s for the right to be cryopreserved while still alive; the courts refused, with warnings of murder charges, and he died of natural causes years later. Beyond the law sits the simpler problem of endurance. A preserved body must be maintained, in liquid nitrogen, for decades or centuries, by an institution that must not fail. In 1979 one did: a California operator let nine bodies thaw and decompose when the money for nitrogen ran out — the field’s defining scandal, a reminder that the cold costs money every day, forever, against a payoff that may never come. Modern providers answer with patient-care trusts and insurance funding; the structural risk remains, that no one can guarantee whether, when, or in what condition a patient would ever return.

Underneath the cryobiology and the custody lies a question the freezers cannot touch. Suppose, granting everything the hopeful ask, that structure were one day perfectly preserved and the person restored or rebuilt from it. Would that person be the one who died, or an extraordinarily faithful copy who merely believes she is? That is the old problem of personal identity, dressed in nitrogen, and no laboratory result settles it; it turns on what one takes a self to be, carried into a future that may never arrive to test it. James Bedford has lain in the cold for nearly sixty years, longer than the organizations that have tended him have individually endured. Whether anything of him is still there to recover, no laboratory has yet found a way to determine. For now he is a body kept very cold, and a bet that has not come due.

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