Cryonics

Established Cryonics is a practising industry with a fifty-year operating record and no demonstration of its central claim in any organism. Both halves of that sentence are matters of record and the brief exists to hold them at once. Established The Cryonics Institute was founded on 4 April 1976 by Robert Ettinger, whose 1964 book The Prospect of Immortality created the field; Alcor was founded in 1972 in California by Fred and Linda Chamberlain as the Alcor Society for Solid State Hypothermia and renamed in 1977. Established Between them, a Swiss entrant and a few smaller operations, fewer than 600 human beings have ever been cryopreserved. Established None has been revived, no cryopreserved mammalian brain has been restored to function, and no party in the field disputes either point.

Established What is actually done is vitrification, not freezing. After legal death is pronounced, the patient is cooled, blood is washed out, and a concentrated cryoprotectant solution is perfused so that on further cooling the tissue solidifies as a glass rather than growing ice crystals. Established Alcor states it has used vitrification since 2001 with the M22 solution developed by 21st Century Medicine, and storage is in liquid nitrogen at -196 degC. Established The Cryonics Institute stores patients in cryostats holding up to eight people each at the same temperature.

Frontier The brief separates three questions the field routinely runs together. First, does the procedure preserve the structural information that specifies a particular person — a question with partial empirical answers, some of them unflattering to cryonics and flattering to its rival. Speculative Second, could a preserved state ever be reversed — a question on which one 2023 result changed the argument for the first time in two decades. Established Third, will the organisation still exist when the answer arrives — a question that is not scientific at all, and the one with an actual failure in the field's own history.

Established The industry is small enough to count, and its own numbers do not agree. The Cryonics Institute's member statistics page, updated March 2025, reports 1,995 members, 268 patients in cryostasis, 279 pet patients and 336 holders of Suspended Animation standby contracts. Established An encyclopaedic entry compiled from later material gives CI 2,322 members and 278 patients and describes it as the largest provider. Established Alcor is the better-documented organisation and its discrepancies are larger: its own itemised census, published 28 February 2021 with data as of 31 January 2021, gives 181 patients — 115 neuro, 62 whole body, 4 recorded as both; 134 male, 47 female — against 1,338 members, 304 associate members and 96 applicants pending. Established Alcor's undated fact sheet says “over 250” patients and “over 1,500” members. Established An encyclopaedic entry citing October 2023 gives 1,927 members including 222 who have died and been cryopreserved, 116 of them neuro-only. Frontier Three sources, three counts, one organisation, and they cannot all be current. Established The 2021 itemised census is the only fully broken-out patient census any provider publishes and is the figure this brief uses where one is needed, with its date attached; the same document gives the geography, 1,151 members and 164 patients in the United States, 70 members and 3 patients in Canada, 40 and 3 in the United Kingdom, 20 members in Germany, 11 members and 3 patients in Australia.

Established The prices are published and they are lower than the public believes at the bottom of the range and higher at the top. Alcor's 2025 schedule is $80,000 for neuropreservation and $220,000 for whole body, out of pocket. Established Annual dues run $60 for ages 0 to 17, $200 for a new member at 18, and thereafter current age multiplied by $15, so a thirty-year-old pays $450 a year, with the multiplier reviewed annually by the board. Established Surcharges are itemised: $10,000 for members outside the United States and Canada, $20,000 if services are required within the first 180 days of membership, $25,000 where a third party signs on the member's behalf, and $50,000 for a non-member cryopreservation arranged by a third party. Established Alcor quotes life-insurance funding at “as low as” $25 to $45 a month for neuro and $50 to $75 for whole body, which is the number that actually governs who can buy this. Established The Cryonics Institute quotes its basic procedure at under $30,000, with a total including logistics that can exceed $100,000 — the gap between CI and Alcor is standby, transport and perfusion protocol, not storage. Established In Europe, Tomorrow Biostasis and the European Biostasis Foundation quote EUR 200,000 whole body for members and EUR 230,000 for non-members, EUR 75,000 brain-only for members and EUR 115,000 for non-members, on an EUR 50 per month membership, with brain-only cheaper because those patients “require less space in long-term dewars and lower maintenance costs.”

Established Ice is the enemy the field solved; toxicity is the one it did not. Freezing kills tissue mechanically and osmotically: growing extracellular ice concentrates solutes, dehydrates cells and shears membranes, which is why pre-2001 practice produced obvious structural destruction. Established Vitrification avoids ice entirely by loading cryoprotectant to concentrations at which the solution becomes a glass on cooling, and the technical foundation is Fahy and Wowk's treatment of the subject in Methods in Molecular Biology in 2014. Established 21st Century Medicine developed the B1C, B2C and M22 solutions Alcor uses, and Alcor describes M22 as “relatively gentle to molecules.” Frontier The trade is exact and unavoidable: the concentrations that suppress ice are, at normal body temperature, lethally toxic, and the entire art of the field is delivering them cold enough and fast enough that cumulative toxic exposure stays below the level that destroys what is being preserved. Speculative This brief prints no quantitative toxicity figure for M22, because the research pack behind it could not verify one; readers should treat any specific M22 toxicity number they encounter as requiring a primary source. Frontier The second physical problem is fracturing: below the glass transition, around -125 degC for M22-class solutions, vitrified tissue is a brittle solid under thermal stress, and cooling to -196 degC for storage guarantees passage through the regime where it can crack. Speculative Incidence and severity across actual patients are not published, which is itself the finding.

Established The organ evidence is real, recent, and smaller than it sounds. In July 2005, 21st Century Medicine announced at the Society for Cryobiology meeting that a rabbit kidney had been vitrified to -135 degC, rewarmed, transplanted, and had supported the animal, which was euthanised on day 48 for histology. Frontier That is one kidney in one rabbit, and its primary publication — Fahy and colleagues in Organogenesis in 2009 — was not obtainable for this brief, so no number from it is printed here. Established The result that changes the argument is from 2023: Han, Rao, Gangwar and colleagues in Nature Communications vitrified rat kidneys, stored them at -150 degC for up to 100 days, and rewarmed them volumetrically using iron oxide nanoparticles driven by an alternating magnetic field at 63 kA/m and 180 kHz. Established The achieved warming rate was 72.0 +/- 8.0 degC per minute, above the roughly 50 degC per minute critical warming rate for the cryoprotectant used, and syngeneic transplants into male Lewis rats, n=5 nanowarmed against n=5 fresh controls, produced survival of all five nanowarmed recipients through the full 30-day study. Established Function followed a recognisable trajectory: peak dysfunction at postoperative days 2 to 3, serum creatinine normalising by days 14 to 23, terminal creatinine 0.4 to 0.8 mg/dL, matching fresh controls; one 60-hour cold-stored control kidney failed intraoperatively. Frontier This is the first demonstration that a mammalian organ can be vitrified, stored for months, rewarmed and support life, and the enabling step is volumetric rewarming, which solves the specific failure that killed earlier attempts — convective rewarming from the outside is too slow at organ scale, so the tissue devitrifies and cracks on the way up. Established It is also a rat kidney of roughly one gram, from one laboratory, with n=5, and a human brain is about 1,300 grams with a vascular geometry far less forgiving than a kidney's. Frontier The scaling problem is not addressed by this paper and nobody has published an attempt.

Established The best structural evidence in the whole preservation field was produced by cryonics' technical rival, and cryonics conceded the point. Aldehyde-stabilised cryopreservation, developed by Song (formerly McIntyre) and Fahy and published in Cryobiology in 2015, perfuses glutaraldehyde to fix tissue almost instantly, then adds cryoprotectant and cools to a storable solid at -135 degC. Established It won the Brain Preservation Foundation's Small Mammal Prize in February 2016 for an entire rabbit brain in which, on independent 3D electron microscopy, synaptic connectivity was preserved across the whole brain to the prize standard, and the $80,000 Large Mammal Prize in March 2018 for a pig brain evaluated the same way after rewarming from cold storage. Established The awarding foundation attached its own limit to the second award, stating that a “single prize-winning laboratory demonstration is insufficient to address the quality-control measures that should be expected of any procedure applied to humans.” Established Alcor's March 2018 position statement concedes that “ASC produces clearer images than current methods of vitrification without fixation,” then objects that fixation causes molecular-scale damage, that it is “likely to be much harder to reverse so as to restore biological viability as compared to vitrification without fixation,” and that it is a research dead end for reversible preservation. Frontier Both parties are right about the other: fixation buys structure at the cost of any biological route back, and vitrification buys a possible route back at the cost of image quality. Frontier Note what the concession costs cryonics on its own central claim — on the one axis where the structural argument is testable today, the method cryonics does not use images better. Full treatment is in Brain Preservation.

Established Legally, a cryonics patient is a donated body, and that single fact generates the field's largest uncontrolled variable. Alcor operates under the Uniform Anatomical Gift Act: patients are received as anatomical donations, so cryonics is a form of body donation rather than a medical treatment. Established Preservation may begin only after pronouncement of legal death, which is what makes it lawful. Frontier It is also what guarantees a period of warm ischaemia before perfusion starts, ranging from minutes in a planned hospice case with a standby team present to days in an unattended death, an autopsy jurisdiction or an international transfer, and no provider publishes the distribution of those intervals across its cases. Established The litigation record concerns custody and contracts rather than efficacy. Established In the Dora Kent case of 1987 to 1988 a county coroner alleged that a patient had been killed with barbiturates before neuropreservation; no charges were ever filed, a judge subsequently ruled that she was already deceased at preservation and that no foul play had occurred, and Alcor prevailed in actions for false arrest and illegal seizure. Established The Ted Williams dispute of 2002 to 2004 was a family disagreement over the baseball player's wishes, resolved in Alcor's favour with the remains staying in suspension. Established No court has ruled on whether cryonics works, and none has been asked to.

Frontier Nanowarming is the first genuinely new capability the field has been able to point to in twenty years, and its replication status is one paper. The 2023 rat-kidney result is one laboratory, the Minnesota group, with n=5. Frontier What makes it different in kind from everything else cryonics cites is that it is a reversal demonstration rather than a structure demonstration: the organ came back and worked, which is the category of result the field has always lacked. Speculative If volumetric rewarming scales, the reversibility argument stops being a promissory note and becomes an engineering programme with a measurable completion criterion.

Frontier The preservation field has split into two technically incompatible camps and the split became public between 2016 and 2018. One optimises structural information retention and abandons viability outright; the other optimises potential viability and accepts worse structural imaging. Established There is no published method that does both. Frontier The choice between them is therefore not a technical question but a bet on what a person is made of, and neither camp can settle it with the instruments it owns.

Frontier The most consequential missing number in the topic is one nobody has to invent an instrument to obtain. Because perfusion cannot begin until legal death is pronounced, every case carries a warm-ischaemic interval, and the quality of the preservation almost certainly depends on it more than on any other single variable. Established No published dataset quantifies the distribution of those intervals across the field's roughly 600 cases. Speculative Providers hold this data as a matter of course — case reports exist internally — so its absence from the literature is an editorial choice rather than a measurement problem, and it is the cheapest correctable defect in the field.

Frontier The European entrant is changing the cost structure and the geography. Tomorrow Biostasis operates a Swiss storage facility on an EUR 50 per month membership model and raised EUR 5 million in 2025 for expansion into the United States. Established Cryonics has been an effectively two-provider American industry for its entire history; a subscription-priced European operation with a different regulatory environment is a structural change, whatever one thinks of the underlying claim. Frontier Growth at the incumbents is real but small: CI reports moving from 268 patients and 1,995 members to 278 and 2,322 across roughly a year of reporting.

Speculative A reporting discrepancy is itself a finding when the product is century-scale custody. An organisation publishing three mutually inconsistent patient counts across its own materials has a data-hygiene problem, and this is the organisation asking members to trust it with an interval longer than any corporation has survived. Speculative Nothing here suggests bad faith, and Alcor is the provider that publishes the most; the point is that the most transparent actor in the field still cannot produce one number, and that this is the kind of defect an outside auditor would catch in an afternoon.

Frontier Two live technical choices inside the industry are usually reported as marketing rather than as open questions. The first is neuro against whole body, which is a bet on what a person is made of and not a budget decision: as of January 2021, 115 of Alcor's 181 patients, 64 per cent, were neuro. Speculative The second is storage temperature. Frontier Liquid nitrogen at -196 degC is cheap, passive and fails safe against power loss, but guarantees passage through the fracture regime; intermediate-temperature storage near -135 degC would avoid it and substitutes active refrigeration and a permanent maintenance obligation. Speculative Neither choice has a published outcome dataset attached, because there are no outcomes to attach.

Frontier The experiment that would move cryonics from a philosophical position to an empirical programme has not been attempted. No one has vitrified and rewarmed a whole mammalian brain with a functional endpoint. Speculative After the 2023 result the tools exist: nanoparticle-mediated volumetric rewarming, a cryoprotectant with a characterised critical warming rate, and an obvious readout in evoked field potentials from a rodent or rabbit brain. Handwave That such an experiment would succeed is not being claimed here; what is being claimed is that its absence is now conspicuous, and that a negative result would be worth as much to the field as a positive one.

Frontier The workback plan from a revived human runs about ten links, and the honest reading is that four of them have never been started. Link one, reversible whole-organ vitrification, has been achieved once: rat kidney, 100 days at -150 degC, nanowarming, five of five surviving to 30 days. Frontier Link two is independent replication of that in a second laboratory and ideally a second organ, and it does not exist. Speculative Link three is scaling from about one gram to about one hundred, with uniform nanoparticle loading and radiofrequency field homogeneity in a rabbit or pig kidney — an industrial problem with no obvious physical barrier. Speculative Link four is any vitrified-and-rewarmed brain with an electrophysiological endpoint, working up from rodent brain slices to a whole rodent brain to a rabbit brain. Frontier Link five is cryoprotectant toxicity at brain scale, measured as viability at M22-equivalent concentrations rather than argued from analogy. Speculative Link six is eliminating or at least characterising fracturing, which intermediate-temperature storage near -135 degC would test at a known cost in refrigeration engineering. Established Link seven is publishing the distribution of warm-ischaemic intervals across all cases, which requires no new science at all.

Handwave Link eight is where the chain leaves anything that resembles a research programme. Repair of accumulated ischaemic and cryoprotectant injury at cellular and molecular scale has no demonstrated component whatsoever; it is the step where every optimistic account substitutes a future capability for an experiment. Speculative Link nine is institutional survival across the storage interval, for which no instance exists in any preservation organisation. Speculative Link ten is a legal status as treatment rather than anatomical gift, which would permit stabilisation before pronouncement and collapse the ischaemic interval towards zero.

Frontier Which link is binding depends on which question is being asked, and the brief declines to collapse them. Scientifically it is link four: no whole mammalian brain has been vitrified and rewarmed with a functional endpoint, and after 2023 there is no longer a good excuse, because this is a two-year project rather than a twenty-year one. Speculative Practically it is link nine, because institutional failure is the mode with an actual instance in the field's history and it is not a technical problem at all. Speculative Link ten is the highest-leverage change nobody is in a position to make: legal death gates everything downstream, and it is for obvious reasons the change least likely to happen.

Frontier Cryonics consumes results from four research programmes and produces none of them. From cryobiology it needs a quantitative toxicity model for vitrification solutions at organ scale, which the field's own founders have pursued for decades and which is the reason M22 exists. Frontier From thermal engineering it needs volumetric rewarming that holds at a thousand times the demonstrated mass, which is the single result the 2023 paper started and nobody has continued. Speculative From connectomics it needs a readout capability that is roughly six orders of magnitude away on published throughput figures, and which matters only under the structural reading of the claim.

Speculative The fourth dependency is not a technology and cannot be bought. Whether long-term memory and personal identity are carried wholly by structural features that survive preservation is an open question in neuroscience, addressed at length in Brain Preservation, and it has never been tested in any organism, including ones whose complete connectomes have been available for decades. Frontier Adjacent evidence cuts both ways: eight genetically identical C. elegans reconstructed across development have connectomes described as “partly unique,” which shows the connectome carries individual information and simultaneously shows that some connectome differences carry no identity at all.

Speculative A fifth dependency runs the other way and is usually omitted. Cold-tolerance biology from Human Hibernation would, if transferable, reduce the severity of everything upstream by widening the temperature range tissue survives before cryoprotectant is introduced. Handwave No transferable mechanism has been identified, and the hibernation literature's own large-mammal record is weaker than its reputation.

Frontier None of these dependencies is being pursued for cryonics, and that is the field's most durable strategic fact. Organ banking funds the vitrification and rewarming work because a transplantable-organ supply is a large conventional medical prize; connectomics is funded because circuit neuroscience wants it; hibernation research is funded by critical care and by spaceflight architecture. Speculative Cryonics is a downstream consumer of all three, contributes almost nothing to any of them, and would benefit from every one of them succeeding for reasons entirely unrelated to itself.

Frontier Six experiments would tell the field more than the next decade of argument, and four are affordable now. The first is the whole-brain reversal series: vitrify and nanowarm a rodent brain slice, then a whole rodent brain, then a rabbit brain, with evoked field potentials rather than histology as the endpoint. Speculative A null result at slice level would be extremely informative and would cost a fraction of one patient's whole-body fee.

Frontier The second is independent replication of the 2023 nanowarming result in a second laboratory, ideally in a second organ and a second species, reporting the same endpoints: warming rate against critical warming rate, survival to a fixed horizon, and a creatinine or equivalent function trajectory. Established One paper with n=5 from a single group is where the current evidence sits.

Established The third costs nothing and is purely editorial: publish, per case and in aggregate, the interval between pronouncement and the start of perfusion, along with the cause of death, whether standby was in place, and whether an autopsy intervened. Speculative This would convert the field's largest uncontrolled variable into a measured one and would allow outcomes of any future readout to be stratified by preservation quality.

Frontier The fourth is a matched fixed-and-unfixed molecular assay — mass spectrometry or expansion microscopy on synaptic post-translational modification state — to measure what each preservation method destroys rather than inferring it from image quality. Speculative The fifth is a fracture census: store a cohort of large-animal brains at intermediate temperature near -135 degC against a liquid-nitrogen cohort and report fracture incidence and plane geometry in both. Speculative The sixth belongs to the structural claim and is the cheapest decisive experiment in the entire preservation cluster: train an invertebrate whose complete connectome already exists, preserve it, image it, simulate it, and test whether the learned association survives. Frontier Nobody has done it in either C. elegans or Drosophila, and until somebody does, the structural hypothesis remains an assumption held by serious people rather than a finding.

Speculative Three of these six require no new instrument and no new theory. The ischaemic-interval publication needs a spreadsheet and a decision; the fracture census needs two freezers and a cohort; the invertebrate experiment needs a laboratory that already exists and a connectome that is already public. Frontier A field whose decisive cheap experiments remain unperformed after fifty years is telling the reader something about its incentives, and the observation applies to the sceptics as much as to the practitioners — a negative result here would be publishable, cheap and permanent.

Speculative Scaling volumetric rewarming from a rat kidney to a human brain is four engineering problems, not one. Nanoparticle distribution must be uniform through 1,300 grams of tissue whose vascular geometry terminates in capillary beds far denser and more fragile than a kidney's, and perfusion is the only delivery route available. Speculative Radiofrequency field homogeneity must hold across a volume more than a thousand times larger than the demonstrated one, where field non-uniformity translates directly into differential warming and therefore into thermal stress. Frontier Cryoprotectant loading must reach full concentration everywhere without generating a toxicity gradient between the perfused surface and the deepest tissue, and the brain is the organ least tolerant of osmotic transients. Handwave Finally the central nervous system would have to tolerate the resulting thermal transient, about which nothing is known because it has never been imposed.

Established The rest of the engineering is unglamorous, real, and already operating. Providers run standby teams, field perfusion equipment, refrigerated transport, and dewar farms with liquid nitrogen resupply; the price gap between a sub-$30,000 basic procedure and a $220,000 whole-body case is almost entirely this logistics chain rather than storage. Speculative Intermediate-temperature storage near -135 degC, proposed to avoid the fracture regime, replaces passive liquid-nitrogen boil-off with active refrigeration, which trades a physical failure mode for a dependence on continuous power and maintenance over centuries. Frontier That trade is the correct engineering framing of the fracture question and it has not been costed in public by anyone.

Speculative Two requirements sit between the current practice and any future readout, and both are cheap to build now and impossible to add later. The first is instrumentation of the case itself: continuous temperature logging at multiple depths, perfusion pressure and cryoprotectant concentration curves, and time-stamped intervals from pronouncement onward, archived with the patient. Speculative The second is a chain of custody for that record which survives the organisation, since a preserved patient with no preservation history is a specimen of unknown provenance whatever the future can do. Frontier Nothing about either is technically hard; both are engineering decisions the field has not visibly made.

Established Organ banking is the adjacent field that pays for the science, and it does not need cryonics to be right. Vitrification of living tissue starts with Rall and Fahy's 1985 demonstration of mouse-embryo vitrification, and clinical oocyte and embryo vitrification is now routine and unremarkable, which is the field's one fully established reversal result at cellular scale. Frontier A transplantable-organ bank is a large medical prize with conventional funding, and the 2023 nanowarming result was pursued for that reason rather than for cryonics.

Frontier Aldehyde-stabilised preservation is the nearest neighbour and the direct competitor, treated in Brain Preservation: it wins on structural imaging, loses any biological route back, and its two prizes went to a single laboratory with no independent replication at large-mammal scale. Speculative Connectomics supplies the readout that a structural claim needs, and its published state of the art is one cubic millimetre of mouse cortex costing about two petabytes, roughly six months of automated electron microscopy and over a million manual proofreading edits.

Frontier Clinical hypothermia and emergency preservation are the closest thing to a human-facing cousin, covered in Human Hibernation. Established The EPR-CAT trial, which cools trauma patients in cardiac arrest to about 10 degC by aortic flush, is the only human protocol that deliberately induces a near-arrested metabolic state, and the contemporaneous Department of Defense progress report from September 2019 records five subjects and five controls enrolled with “none of these subjects have survived.” Speculative If a successor protocol ever produces a survivor, it will move the legal and clinical boundary that cryonics is currently on the wrong side of.

Handwave The far downstream neighbour is repair biology, and cryonics needs more from it than any living patient ever will. The damage a revived patient would carry is ischaemic, osmotic and chemical injury distributed across every cell, which is a strictly harder problem than the age-related damage addressed in Cellular Rejuvenation and Longevity Therapies. Speculative Any repair capability sufficient for a cryonics patient would have transformed ordinary medicine first, which is a useful ordering constraint: the world will know long before revival is attempted whether the required class of capability exists at all.

Frontier The binding institutional requirement is an organisation that outlives every organisation of its kind that has ever existed. Storage obligations run for an unbounded interval, funded from a one-time payment, in an industry whose largest provider holds a few hundred patients. Established The standard mechanism is a patient care trust or endowment funded from the cryopreservation fee, with member dues covering operations, and the standard funding instrument for the member is a life-insurance policy naming the provider — a structure that works well for the member and transfers all long-horizon risk to the institution.

Speculative The field's own history contains an institutional failure, and this brief names it without printing details it could not source. The Cryonics Society of California's storage facility at Chatsworth failed in the 1970s and patients thawed. Speculative The research behind this brief could not obtain a primary source, so no count, no date and no attribution of cause is asserted here; readers should treat the specifics they encounter elsewhere as requiring verification. Frontier The structural lesson survives the sourcing gap intact: the technical case can be perfect and the institution can still fail, and the industry's own record contains an instance of exactly that.

Frontier There is no oversight body, no quality standard and no reporting requirement. Because patients are received as anatomical donations rather than as patients, no medical regulator asserts jurisdiction over procedure quality, and no external party audits patient counts, perfusion records or ischaemic intervals. Established The Brain Preservation Foundation, which funds and judges the prizes in the adjacent field, has itself stated that a single laboratory demonstration is insufficient to address the quality-control measures a human procedure should meet. Speculative A field that adopted three reporting standards — a reconciled patient census, per-case ischaemic intervals, and published perfusion parameters — would be more credible within a year at essentially no cost, and the fact that it has not is informative about incentives.

Speculative The financial structure has a specific weak point that is rarely stated. A one-time fee funding an unbounded storage obligation is solvent only if the endowment's real return exceeds real storage costs indefinitely, which is a claim about capital markets over centuries and not about cryobiology. Frontier Every historical instance of an endowment surviving that long belongs to a church, a state or a university, none of which was funded by a few hundred customers, and none of which promised a service whose delivery date is unknown. Speculative The European subscription model shifts some of this risk onto a recurring revenue stream and therefore onto continued demand, which is a different bet rather than a smaller one.

Frontier The consent architecture is unusually well developed and has an obvious pressure point. Members sign in advance, in good health, with insurance funding; Alcor's own schedule prices the alternative cases explicitly, charging $25,000 where a third party signs on a member's behalf and $50,000 for a non-member cryopreservation arranged by a third party. Speculative Those two line items are the ethically hardest transactions in the industry, because they describe preservation arranged by relatives for someone who did not choose it, and the litigation record shows exactly this shape of family conflict.

Speculative The charge that cryonics sells false hope has to be weighed against what it actually charges for it. At $25 to $75 a month in insurance premiums the product is not a wealth transfer of the kind the criticism usually implies, and the comparison the field invokes — against cremation or burial, both certainly information-destroying — is a fair one. Frontier The genuine ethical defect is different and narrower: marketing that presents an untested reversal claim with the confidence appropriate to the partially tested structural one, and that never mentions the warm-ischaemic interval that dominates case quality.

Handwave The hardest question is one no cryonics provider currently faces and a related field already does. If preservation quality depends on beginning before pronouncement, the logical endpoint is a procedure performed on a living person that causes their death, which is homicide in every jurisdiction absent a specific legal framework. Established The commercial actor that proposed exactly this in brain preservation described its own procedure as fatal by design, and its academic partner severed the relationship within a month. Speculative Any serious argument for improving cryonics outcomes runs into this wall, and the field is generally honest enough not to pretend otherwise.

Speculative There is a duty of care owed to the bereaved that neither side of the public argument discharges. Families encounter this decision at the worst moment of their lives, from providers with a commercial interest and from critics with a rhetorical one, and the accurate position — that the structural claim is partly testable and partly tested, the reversal claim is untested, and the institutional risk is real and historically instantiated — is available from almost nobody. Frontier Getting that sentence into circulation is worth more than another round of the underlying dispute.

Speculative At current scale the civilizational implications of cryonics are zero, and that is a substantive finding rather than a dismissal. Fewer than 600 preserved humans exist worldwide, growth is in the low tens per year, and no plausible near-term expansion changes any demographic, economic or legal aggregate.

Handwave Conditional on the claim being right, the implications are large and almost entirely institutional. A society that could revive preserved people would have to answer who holds custody of a person across centuries, what legal personhood attaches to a preserved patient, whether estates and identities are restored or reconstituted, and how revival is triaged when demand exceeds capacity. Speculative None of these are novel problems in kind — guardianship, trusts and the law of missing persons all supply partial analogies — but all of them would arrive at once and with no precedent for the underlying fact pattern.

Speculative The asymmetry is the interesting part. The cost of the field being wrong is a few hundred people who were going to be destroyed anyway being destroyed more slowly and more expensively; the cost of it being right and abandoned is the irreversible loss of everyone who could have been preserved during the interval of disbelief. Handwave That asymmetry is the whole decision-theoretic case, it is not an empirical claim, and it should never be presented as one.

Speculative The most transferable civilizational lesson has nothing to do with revival. Cryonics is a fifty-year natural experiment in how a society handles a claim that cannot be checked on the timescale of the people arguing about it, and the observed answer is that both sides substitute confidence for evidence and neither runs the cheap experiments. Frontier Institutions designed to carry obligations across centuries — nuclear waste custody, seed vaults, deep-time archives, sovereign endowments — face the same structure, and the cryonics record is a small, documented and unusually candid instance of it. Speculative A civilisation that cannot keep a promise for two hundred years should notice that it has an existing case study with actual patients in it.

These horizons track the experiments and institutional facts that would change what can honestly be said, not predictions of revival.

• 10 yr: Frontier Independent replication of nanowarming in a second laboratory, and scale-up from a one-gram organ towards a hundred-gram one, are both reasonable expectations on current funding, because organ banking wants them for its own reasons. Speculative A vitrified-and-rewarmed rodent brain with an electrophysiological endpoint is technically available now and is the single result to watch for; its absence ten years from now would be a stronger statement about the field than any argument. Speculative A reconciled patient census, published ischaemic-interval distributions and archived per-case perfusion records are available whenever the industry chooses, at a cost of approximately nothing.
• 25 yr: Speculative If the brain series succeeds at rabbit scale, cryonics acquires an empirical programme and a measurable completion criterion for the first time in its history; if it fails, the structural camp's position strengthens and the reversibility argument narrows to repair-after-the-fact. Speculative Either outcome is worth more than the field's entire current evidence base. Frontier On present growth the worldwide patient population is still likely to be in the low thousands at most, which means the institutional risk compounds without the scale that would make an industry robust.
• 50 yr: Handwave Whole-brain readout at electron-microscopy resolution requires throughput gains of roughly five to six orders of magnitude on published connectomics figures; nothing in physics forbids it, and no demonstrated trend delivers it on this horizon. Speculative The two metrics that track progress honestly are cubic millimetres imaged per instrument-year and manual proofreading edits per millimetre of reconstructed neurite, both of which are published quantities. Speculative An organisation reaching this point without losing a patient would itself be the field's first novel datum about its binding risk.
• 100 / 250+ yr: Handwave Repair of ischaemic and cryoprotectant injury at molecular scale, followed by revival, has no demonstrated component and no experiment in progress anywhere. Handwave Any date attached to it — by advocates, or by critics asserting impossibility — is an assertion about a capability nobody can currently specify, which is precisely why this brief records no dependency edges. Speculative What can be said is narrower and firmer: the answer arrives, if it arrives, through general repair medicine and readout instrumentation built for other purposes, and the field's own contribution to reaching it is custody.

• Depends on This brief records no dependency edges, and the decline is a position rather than an omission. Cryonics plainly draws on results produced elsewhere — volumetric rewarming, vitrification chemistry, connectomic readout, the structural-preservation evidence from the rival paradigm — and it would be easy to list those as prerequisites. It would also be wrong. A dependency edge is a claim that one result sits on another's critical path, and a critical path is only knowable when the endpoint can be recognised. Cryonics has no recognisable endpoint short of the outcome itself: there is no intermediate measurement that would tell anyone the procedure is working, because the only evidence that the preserved state was recoverable is its recovery. Every candidate prerequisite is therefore a prerequisite conditional on an assumption — that the chain terminates in a revived person — which no evidence available today supports or refutes. Recording the edge anyway would smuggle that assumption into a machine-readable field and let it be counted, aggregated and drawn as a line on a map, which is exactly the failure this schema exists to prevent.
• Enables Nothing is recorded as enabled by this brief either, for the mirror-image reason. A revived cryonics patient would enable a great deal — a new legal category of person, a hard test of what identity is made of, a demand shock in repair medicine — but the enabling result is precisely the one never demonstrated in any organism, so an edge drawn outward from here originates in an unverified premise and inherits its status. Where cryonics has genuinely contributed, the contribution is real and of the wrong kind for this field: a standing commercial demand for cryoprotectant development, a customer base that funded 21st Century Medicine, and a set of prizes that produced the best structural-preservation results anyone has. That is institutional and financial influence, not a result another brief is waiting on, and conflating the two would inflate the map's edge count with sponsorship.
• Adjacent The honest relationships are adjacencies and the brief states them plainly rather than upgrading them. Brain preservation is the direct technical rival, shares the identity question, and currently wins on the one axis where either camp can be tested. Human hibernation and emergency preservation approach the same cold-tolerance problem from the warm end and are the only human-facing work in the neighbourhood. Organ banking owns the entire vitrification and rewarming toolchain, is funded for reasons unconnected to cryonics, and will produce the decisive results whether or not any cryonics organisation still exists when they land. Connectomics supplies the readout on which the structural reading depends, and its published throughput is the number that bounds that reading. Each of these is a real intellectual neighbour; not one of them is waiting on cryonics for anything, and saying so is more useful to a reader than a diagram would be.

Established “Cryonics freezes people.” Current practice is vitrification — solidification without ice-crystal formation, using M22-class cryoprotectants, in use at Alcor since 2001 with ice-elimination results published in 2004. Established “Frozen” describes pre-2001 practice accurately and current practice not at all, and the distinction is the single most load-bearing technical fact in the topic.

Frontier “A rabbit kidney was cryopreserved and transplanted, so organ cryopreservation is solved.” The 2005 result was one kidney in one rabbit, euthanised on day 48 for histology, and its primary publication was not obtainable for this brief. Established The genuinely strong result is from 2023, it is a rat kidney, n=5, 100 days, from a single laboratory. This is an enthusiast-side error and it inflates a two-animal evidence base into a solved problem.

Established “Cryonics costs a quarter of a million dollars.” It costs $80,000 for neuropreservation at Alcor, under $30,000 for the basic procedure at the Cryonics Institute, and EUR 75,000 for brain-only in Europe, and it is routinely funded by life insurance at $25 to $75 a month. Established The $220,000 figure is Alcor whole-body, the most expensive option offered by the most expensive provider. This is a sceptic-side error and it makes the practice sound like a plutocrats' club when the binding constraint on uptake is belief rather than money.

Established “There are thousands of people in cryonic suspension.” On the best figures obtainable: 268 to 278 at the Cryonics Institute depending on the reporting date, 181 to 250 at Alcor depending on which Alcor source is read, plus small numbers elsewhere. Established Fewer than 600 worldwide, ever. This error is held on both sides, because both an industry and its critics benefit from the subject sounding larger than it is.

Established “Courts have ruled that cryonics is or is not legitimate.” The litigation record concerns custody, contracts, coroners' jurisdiction and family disputes. Established No court has ruled on whether the procedure works and none has been asked to; a ruling that a specific patient was already legally dead at preservation, as in the Dora Kent case, is a finding about a death, not about a technology.

Frontier “Cryonics patients are legally dead, so nothing is being lost.” True, and load-bearing in a direction enthusiasts dislike. Established Because preservation cannot begin until after pronouncement, every case includes a warm-ischaemic interval, and no provider publishes its distribution. Speculative This is very probably the largest quality variable in the practice and it is invisible in the marketing material of every provider.

Frontier “Nanowarming means cryonics works now.” The 2023 paper rewarmed a roughly one-gram rat kidney with a simple vascular tree, using nanoparticles distributed by perfusion, with n=5 and a 30-day endpoint. Established A human brain is about 1,300 times heavier, is the organ least tolerant of thermal and osmotic transients, and has never been attempted. This is the newest enthusiast-side error, dating from 2023, and it is the one most likely to be encountered as fresh news.

Established “Neuropreservation is a cost-cutting compromise.” It is a distinct technical bet that the person is the brain, and it is the majority choice: 115 of Alcor's 181 patients, 64 per cent, were neuro as of January 2021. Speculative It also imports a larger technological requirement rather than a smaller one, because a revived neuro patient needs a body that must be reconstructed or replaced — capabilities strictly greater than those revival alone requires. The cheaper option is the more speculative one.

Established “A human was successfully placed in suspended animation in 2019.” The contemporaneous Department of Defense progress report on the EPR-CAT trial, dated September 2019, records five emergency-preservation subjects and five controls enrolled and states that “none of these subjects have survived.” Established The press coverage that produced this claim reported that a procedure had been performed, not that a patient had survived it. This error belongs to the same family as the rest: a real result about a conditional quantity restated as a result about an unconditional one.

Speculative “Cryonics is a bet on revival.” The strongest available form of the argument is not about revival at all, and the field uses it least. Established The legal and clinical definition of death has moved repeatedly with technology, from cardiac criteria to brain-death criteria, always in the same direction. Speculative On that reading cryonics is insurance against misdiagnosis of death rather than against death, and it requires nothing about revival technology — only that the diagnostic boundary keeps moving as it has for a century. Handwave What it still requires is that the preserved state be recoverable at all, which returns the argument to exactly the unfalsifiable place it started, and readers should notice that this is a reframing rather than an escape.

Frontier Both terminal positions deserve to be printed at full strength, and this brief declares the tie rather than resolving it. Against: no mammal has been revived from cryopreservation; the one reversal result is a one-gram rat kidney, n=5, from a single laboratory; vitrification requires cryoprotectants that are toxic at the concentrations used; perfusion cannot begin until after legal death, guaranteeing an ischaemic interval that is never reported; storage requires an institution to survive centuries and the field's own history contains a failure in which patients thawed; and the provider with the best documentation publishes three inconsistent patient counts. Speculative For: every one of those objections is about present capability and institutional risk, and cryonics has never claimed present capability; the relevant comparison is not against medicine but against cremation, where the alternative is certain information destruction; the bet costs $25 to $75 a month; and its falsifiable component, whether structure survives, is being actively tested and has been partly answered in the affirmative by the rival method. Frontier These are not two views of the same question. One is an evidential argument and the other is a decision-theoretic one, they are both valid, and no experiment now in progress adjudicates between them.