Difference between revisions of "Cryonics"

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= Revival =
= Revival =
See [[Cryonics revival]]
== Damage ==
The kinds of damage that need to be repaired have been slowly reduced over time, but at present, under the best conditions, the process of cryopreservation still causes severe damage to the Patients.
=== Cryoprotectant Toxicity ===
=== Cracking ===
There are two forms of cracking: That which is caused by thermal stress, and that which is caused by cooling below T<sub>g</sub>. Cracks are generally few and large, which is far better than many smaller cracks; since from an information point of view they cause little damage.
If revival is attempted through Whole Brain Emulation, then fixing cracks is just a matter of adjusting the images. If it is attempted through some form of Biological Repair, this will require other methods to readjust the severed pieces of tissue.
==== Thermal Stress ====
==== Glass Cracks ====
When materials (Not only glasses) are cooled below their vitrification temperature, cracking occurs. Since the T<sub>g</sub> of the cryoprotectant solutions is far above the temperature at which Nitrogen liquefies, cracking occurs during the cooling to this temperature, whether tissue has been vitrified or not. If cryoprotective Perfusion is not carried out properly or is compromised by severe ischemic injury, cracking can begin at temperatures as high as -90 ºC.
A solution for this (In properly perfused patients for whom cracking will only occur below glass transition) is Intermediate Temperature Storage.
== Biological Repair ==
== Whole Brain Emulation ==
''See [[Whole Brain Emulation]]''
[[File:Cryoultramicrotome.jpg|thumb|A cryoultramicrotome used to section tissue at low temperatures.]]
[[File:Spikes real and fake.jpg|thumb|One of these columns is a graph of the activity of a rat's pyramidal neuron under electrical stimulation. The other is an [[Izhikevich model of spiking neurons|Izhikevich simulation]] of the same. This shows that reality and abstract models can have different internal behavior and foundations, but produce the same activity.]]
This approach to cryonics takes the ideas of information-theoretic death and the central tenets of [[Whole Brain Emulation]] (Memory and personality are stored in the brain, consciousness arises from material processes, et cetera) and proposes that [[#Patients|cryonics patients]] may be revived by scanning the connectivity and properties of the cells in their brains (For example, with an [[ATLUM]] or some form of high-resolution tomography); and that an abstract, computer model of these properties will be very similar to the person who was cryopreserved.
=== Process ===
# The vitrified brain is extracted from the patient. Necessary extra fixatives are applied.
# The brain is segmented into as many pieces as needed.
# Each piece is laminated and scanned by a cryoultramicrotome, [[ATLUM]] or some other machine.
## Current technology is rather slow, but new massively-parallel electron microscopes are being, developed, primarily by the semiconductor industry. The speed of scanning depends on how many machines you have.
# A stack of electron micrographs is built, one for every slice.
# Noise is eliminated, different electron micrographs at the same height are pasted together by inferring edge connectivity.
# An edge detector traces the contours of neurites and cellular structures.
# Other algorithms detect intracellular structures of interest (Polyribosome complexes).
# This is done for every layer.
# Another algorithm joins the edges in different layers, creating a 3D model of the brain.
# Another algorithm uses that model to create a graph of the connectivity of the brain. Each node in this graph is a neuron, and the neuron data structure is supplied with all the necessary extra information acquired by step 7.
# After the scan is complete, the graph is stored in a neuromorphic computer; a machine where every processor is a hardware implementation of some model of neurons.
# The graph at the lowest level of the stem is joined with a species-generic graph of the connectivity of the spine, ie: Axons of the brain are matched to virtual nerve endings.
# The simulation of the body and brain, either connected to a robot or virtual avatar, is started.
== Molecular Nanotechnological Repair ==
''See [[Molecular Manufacturing]]''
The approach of using [[Molecular Nanotechnology]] to revive cryonics patients dominated the discussions of the future of cryonics for over a decade since the publication of ''Engines of Creation'', but has now mostly shifted to a historical curiosity.
= Postmortem Examination =
= Postmortem Examination =

Revision as of 15:15, 9 August 2017

Cryonics is a controversial life extension technique that aims to preserve neural activity and life typically of a recently deceased person through use of preservation techniques and low temperatures so that resurrection may be possible in the future when technologies have improved.

Possible necessary future technologies include:

Imported content

That is not dead that can eternal lie,

and with strange aeons even death may die.

- H.P. Lovecraft

Margaret, Paul, I wish you the very best and it is my most fervent desire that we meet again, hopefully in a time and place where we can laugh and reminisce about the dark ages from which we were so lucky to have made our escape from...
- Mike Darwin

Cryonics is the preservation of dead persons at temperatures low enough to practically stop decomposition, with the intent of future revival. While there is experimental evidence attesting to the conservation of vitrified tissue and the possibilities of repair; the decision to undergo cryonic preservation after death is an act of faith, not of science.


File:Ettinger with HSSV.jpg
Robert Ettinger dreamed of a time machine that would bridge the gap between today's patients and tomorrow's medicine.

The two main ideas behind cryonics are Information-Theoretic Death and the technology vitrification. The first idea is the idea that our criteria for death has changed as our technology and our understanding of biology has changed. In the 1800s, a person who drowned was considered dead. Information-theoretic death is the 'ultimate' death, the one that we know as fact is irreversible, and does not depend upon a changing understanding of nature. Information theoretic death is reached when the body (Especially the brain) has been damaged to the point that it is beyond repair; where repair means having enough structure and contextual information to bring the brain, along with the personality, memories and attitudes that it contains, back to a functioning state. If tissues have been properly preserved, this revival could be accomplished through a variety of ways, but even the best methods leave behind irreparable damage, which means memory loss and personality changes, and other neurological (Motor control) damage. The latter is sufficiently generic to be repaired when that kind of technology arrives, the former is unique to each person and impossible to recover.

The second idea, vitrification, is a process through which tissue is lowered to cryogenic temperatures without freezing or forming ice. The most widely believed myth about cryonics is that when people are frozen, ice inside their cells bursts and destroys tissue irreparably. This is false on two points: Modern cryonics uses cryoprotectants which prevent ice damage by vitrifying instead of freezing, and the water that forms ice is mostly outside the cells. A common argument against cryoprotectants is that they are toxic: While true, this only affects the prospects of suspended animation through vitrification, since cryonics patients would probably be revived through more complicated means than just thawing them and applying CPR once a cure for what killed them is found.


See History of cryonics


Revival of Dogs after Profound Hypothermia

Scientists' Open Letter on Cryonics

To whom it may concern,

Cryonics is a legitimate science-based endeavor that seeks to preserve human beings, especially the human brain, by the best technology available. Future technologies for resuscitation can be envisioned that involve molecular repair by nanomedicine, highly advanced computation, detailed control of cell growth, and tissue regeneration.

With a view toward these developments, there is a credible possibility that cryonics performed under the best conditions achievable today can preserve sufficient neurological information to permit eventual restoration of a person to full health.

The rights of people who choose cryonics are important, and should be respected.

The Suda Experiments

Organ Vitrification

Viability of Vitrified Tissue

  • Cryopreservation of rat hippocampal slices by vitrification, Yuri Pichugin, Gregory M. Fahy, Robert Morin. Cryobiology: International Journal of Low Temperature Biology. Link.


Interestingly (and somewhat to the author’s surprise) there are no published technical articles on cryonics that claim it won’t work. - Ralph Merkle

Most criticism of cryonics arises from fundamental misconceptions (For example, that cryonics involves freezing) and ignorance of current cryopreservation techniques and procedures.

Scientific American



The preservation of cells, tissues and organs by cryopreservation is a promising technology nowadays. However, the primary purpose of this science has been diverted to a doubtful technology, cryonics. Cryopreservation techniques are now being adapted with the aim of preserving people’s bodies after death in hope that in the future, medicine will be able to revive them. In this report we analyze both scientific and social issues involved with this technology. We first studied the events taking place in the cells during regular freezing. Various research experiments show that freezing causes damage to the cells. Therefore, vitrification presented by cryonics companies as an alternative, seems to be reasonable. We also looked at all the difficulties of this procedure and at the injuries that such a treatment could cause to the human body. Studies show that the vitrification procedure suppresses the injuries related to freezing but the use of cryoprotectants, although necessary, is toxic to the cells. Organs, such as kidneys, are the largest entities ever vitrified and thawed with success. By analyzing all present scientific data, we conclude that there is a limit to the size of living matter that can be cryonised effectively; therefore we conclude that it is not possible to cryonize an entire human body with the current technology without causing severe damage to it.

While definitely great progress from most cryonics 'criticism' to date, the paper seems to address the well-known fact that reanimation from cryopreservation is impossible (Or nearly so) due to the toxicity of cryoprotectant solutions. The most discussed methods of revival, Molecular Nanotechnology and Whole Brain Emulation are not discussed.

Larry Johnson


While it's sad that people focus on philosophical issues instead of the myriad technical and social problems that plague cryonics, along with its attachment to a history of failure and incompetence, philosophical concerns should still be addressed.

By far the biggest philosophical concern people put forward against cryonics is the issue of continuity of consciousness. In these debates, people can easily talk past each other by using different definitions of what constitutes consciousness and how this relates to personal identity. In general, we have two definitions of consciousness:

  • Real Definition: Consciousness is self-awareness, and thus becomes discontinuous during sleep, unconsciousness, et cetera.
  • Alternate Definition: Consciousness is defined as a subset of (Or the totality of) brain activity, and thus a person's consciousness remains continuous during sleep and what is usually called 'unconsciousness', and only stops when brain activity ceases (Medico-legal death, not necessarily Information-theoretic).

But what is relevant is not the definition of consciousness, but how this matters to personal identity. Again, here we have two opinions:

  • Definition 1: Personal identity is a person's personality and memories. Consciousness is fundamental to life, of course, but its continuity is not fundamental to personal identity (It uses the Real Definition of consciousness).
  • Definition 1: Personal identity is a person's personality, memories, and continuous consciousness (It uses the Alternate Definition of consciousness). When consciousness becomes discontinuous, the identity 'stops' and ceases to exist.

Under Definition 1, cryonics patients will be the same person (± brain damage). Under the second definition, when they are repaired, the patients are fundamentally different people who claim to be the same as the original and only shre personality and memories.


See cryonics organisations


See Cryonics procedure


See Cryonics revival

Postmortem Examination

So far, only three postmortem, post cryopreservation examinations of cryonics patients have been carried out, all three in the 1980's. Some of the data was lost and most of the images are low quality due to being scanned from black-and-white publications. Medical examination provides a chance to examine the damage caused by cryonic preservation to patients on both the macroscale. They also provide the only opportunity to safely remove tissue for histological examinations, due to the fact that extracting tissue from a patient in Liquid Nitrogen could cause severe fracturing and damage from thermal stress, especially if one wishes to extract tissue near the brain or from it.

James Bedford

Source: Evaluation of the Condition of Dr. James H. Bedford After 24 Years of Cryonic Suspension.

  1. Dewar
    1. The dewar had been built in mid 1970 and was failing.
    2. The patient's refilled the dewar regularly for 21 years, preventing the patient from experiencing any significant warming. The presence of water ice, still in the form of cubes, confirms this.
  2. Body
    1. The patient did not have any visible surface fracture events.
    2. Head
      1. The head is turned to the left and two puncture marks ~1cm apart are visible on the anteriomedial aspect of the sternocleidomastoid muscle (Site of injection of the solution).
      2. A frozen, bloody exudade is visible around the mouth and nose, consistent with the presence of a respirator mask and improper chest compressions.
      3. A larger quantity of darker blood appears to have flowed from the mouth during dry ice freezing, as it retains the folds of the wrapping used to cover the patient.
      4. The eyes are partially open and the corneas are white due to ice. The nostrils were flattened, presumably compressed by the weight of dry ice.
      5. The had was fringed with short gray hair.
      6. There were remains of aluminized mylar on the occiput.
    3. Neck
      1. The skin of the left side of the neck is distended with the injection of a fluid bolus into the subcutaneous space.
      2. Examination of the left side of the neck was made impossible by the position of the head.
    4. Limbs
      1. Arms
        1. The skin of the right forearm appeared erythematous and discolored.
      2. Legs
        1. The legs are crossed, with the right foot over the left.
    5. Torso
      1. The skin from the mandible to ~2cm above the areolas appeared erythematous and discolored.
    6. Abdomen
      1. The skin was erythematous.

The general discoloration is probably a product of the injection of pure or highly concentrated DMSO.

Ray Mills

Source: Postmortem Examination of Three Cryonic Suspension Patients.

  1. Dewar
  2. Body
    1. Head
    2. Neck
    3. Limbs
      1. Arms
      2. Legs
    4. Torso
    5. Abdomen

Katherine Mills

Source: Postmortem Examination of Three Cryonic Suspension Patients.

  1. Dewar
  2. Body
    1. Head
    2. Neck
    3. Limbs
      1. Arms
      2. Legs
    4. Torso
    5. Abdomen

Janice Foote

Sources: Postmortem Examination of Three Cryonic Suspension Patients and Histological Study of a Temporarily Cryopreserved Human.

  1. Dewar
    1. The patient had been stored in the Andonian Dewar.
    2. The patient had been stored in an aluminium cassette lined with open-cell urethane foam as insulation.
    3. An overhead crane removed the cassette and placed it on the ground with the patient on a supine position.
  2. Body
    1. Head
    2. Neck
    3. Limbs
      1. Arms
      2. Legs
    4. Torso
    5. Abdomen


Delay and Ischemic Injury

Lack of Regulation

Storage Safety

The Tyranny of the Singularity

Multi-Century Commitment


See Cryonics patients


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Freeze Drying

Freeze drying, also known as Lyophilization; consists of freezing tissue, then reducing the atmospheric pressure and applying heat to sublimate the water ice in it. A freeze drying machine is a large chamber of heated shelves. Its atmosphere is connected to a vacuum pump and exposed to refrigeration coils.

In the process, the solid is first frozen; creating damaging ice crystals. The vacuum pump lowers the pressure to .6 ATM; ten, the shelves are heated, and due to the low pressure, the ice sublimates directly. This process can take several days (A single (.1386Kg) human brain took 28 to freeze dry. Slicing it, however, reduced the time to 14 days.[1]).

The material, at least in the case of food, can be preserved for several years without decay.

The main advantages of Lyophilization are that the removal of water and oxygen from tissue will reduce decay, and that it does not require expensive equipment or maintenance. A secure container, however, must be obtained and inspected to ensure that Oxygen does not enter the tissues.

The reduced dependence on equipment increases the safety of the storage and reduces the vulnerability of the tissue. There is some overlap in the storage advantages (Namely very low cost and easy storage) of Plastination. Moreover, freeze-dried material can be cryogenically stored later on.

In terms of cost, a single Lyophilization machine, the Taxi-Dry runs at 'less than a dollar a day', and most machines capable of fitting a human brain, head or body cost above $10,000, significantly cheaper than the cheapest perfusion machine.

The most obvious disadvantage is the the Lyophilization process is very destructive it itself. Since freezing happens before dehydration, ice crystals form. When they sublimate, the structural integrity of the tissue is compromised, due to the pores this leaves behind. This might be a solvable problem, but for now, the process is more destructive than the standard Vitrification protocol. Freeze drying also leaves 2% moisture, reducing the storage time to mere years.


Recently, the Brain Preservation Foundation has launched the Brain Preservation Technology Prize, a $100,000+ prize to anyone who can preserve an entire human brain for a long amount of time, such that every neurological feature is preserved and can be examined with today's electron microscopy. Ken Hayworth believes this will be a form of plastination.

Alcohol Storage

Alcohol storage is an old and still widely used preservation method. If storing whole organisms, removal of the intestines is required. Proper storage can be achieved with 70%-90% purity alcohol or methylated spirit. To better preserve the DNA, sodium chloride (Common salt) can be added. 5% Glycerine also supposedly protects the specimen should an accident cause the alcohol to escape or evaporate. The container should be sealed and stored in a dark and cool place, such as a freezer.

The container's alcohol should be replaced at least once, a few weeks after immersion (Or whenever the liquid starts to turn darker or cloudy), as body fluids seep out and contaminate the alcohol. The above-mentioned additives should only be added after the replacement of the alcohol.

While alcohol preservation is very cheap and easy to do, both commercially and DIY (All it takes it some alcohol, a glass container and a freezer), it is overall a very poor preservation method, at least from the perspective of what cryonics tries to achieve: Under a microscopy, they degrade into mush after only a few months.

While biological specimens can be stored for many decades without exterior degradation (Einstein's brain and the Tasmanian Tiger "clone pup", the latter remaining integral after 130 years of alcohol storage), it only preserves macroscopic structure, and maybe enough genetic material to make a clone. Another, less significant issue, is the flammability of alcohol.

Permafrost Burial

File:Permafrost distribution.jpg
Distribution of permafrost in the Northern Hemisphere. Map by Philippe Rekacewicz, UNEP/GRID-Arendal; data from International Permafrost Association, 1998. Circumpolar Active-Layer Permafrost System (CAPS), version 1.0.
File:Permafrost temperature.jpg
Permafrost temperature profile.
Record Low Temperatures
Location Lowest Recorder Temperature (Cº)
Vostok, Antarctica -89.2ºC
Plateau Station, Antarctica -84ºC
Oymyakon, Russia -71.1ºC
Northice, Greenland -66ºC
Snag, Yukon -63ºC
Rogers Pass, Montana -56.5ºC


Cryoprotectant toxicity

  • Non-toxic cryoprotectants
    • Fractures would still be a problem when around Tg.
      • Fractures in some cases will require vascular surgery (Katherine Mills; severed aorta) and in the worst cases organ transplantation & spinal cord replacement/regeneration (Janice Foote, almost severed lung, spinal cord severed in 3). See the postmortem examination.
  • The Prometheus Project tried to achieve reversible brain cryopreservation, but this didn't pan out.

Research into Alternatives

  • Alternatives to cryonics may produce low-cost solutions for long term storage of patients
  • May also increase chances of revival and better preserve the tissues
  • Things like plastination may be more easily accepted by the mainstream neuroscience community


In Popular Culture

See Cryonics in popular culture


  • 21CM: 21st Century Medicine, Inc.
  • ATP: Adenosine Triphosphate.
  • BBB: Blood Brain Barrier.
  • CNS: Central Nervous System.
  • Corpscicle: See Patient.
  • CPB: Cardiopulmonary Bypass.
  • CPA: CryoProtectant Agent.
  • CPS: CryoProtectant Solution.
  • CPR: Cardiopulmonary Resuscitation.
  • Cryostat: A custom-made, fiberglass storage tank of Liquid Nitrogen for cryopatients. It is not a dewar, due to the isolation being perlite surrounded by soft vacuum. It is used by the CryonicsInst.
  • CT: Computerized Tomography.
  • Deanimate: 'Die', but not in the information-theoretic death. A term used to describe cryonicists who experience legal death and are cryopreserved.
  • Deep Hypothermia:10-27ºC.
  • Dewar: A container used to store Liquid Nitrogen. It consists of two containers, separated by a vacuum jacket in the middle. The vacuum provides isolation by preventing convective heat exchange.
  • ECMO: Extracorporeal Membrane Oxygenation.
  • EM: Electron Microscope or Electron Microscopy.
  • EMS: Emergency Medical System.
  • HD: Hemodialysis.
  • HLM: Heart Lung Machine.
  • ICP: Intracranial Pressure.
  • ITS: Intermediate Temperature Storage.
  • LAPC: Liquid Assisted Pulmonary Cooling.
  • ME Case: A cryonics patient who is autopsied prior to cryopreservation.
  • MH: Mild Hypothermia; 33-35ºC.
  • MI: Myocardial Infarction.
  • MRI: Magnetic Resonance Imaging.
  • MSOF: Multiple System Organ Failure.
  • MW: Molecular Weight.
  • Neuro: A type of patient for which only the head is stored.
  • NMR: Nuclear Magnetic Resonance.
  • O2: Oxygen.
  • Patient: A cadaver under the custody of a cryonics organization.
  • Perfuse: Infuse an organ or system with a fluid, in the case of cryonics, Cryoprotectant solutions.
  • Perfusate: The solution that is used for perfusion.
  • SAH: Subarachnoid Hemorrhage.
  • SCA: Sudden Cardiac Arrest.
  • Tg: The glass transition temperature.
  • PIB: Portable Ice Bath.
  • Whole Body: A type of patient for which the whole body is cryopreserved and stored.
  • WBE: Whole Brain Emulation.


See Also



The Prospect of Immortality by [[Robert Ettinger]], 1962
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The First Immortal: A Novel Of The Future by James L. Halperin, 1998
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Man into Superman: The Startling Potential of Human Evolution -- And How To Be Part of It by [[Robert Ettinger]], 1972
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Connectome: How the Brain's Wiring Makes Us Who We Are by [[Sebastian Seung]], 2012
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  1. Freeze-Drying Biological Specimens: A Laboratory Manual
  2. http://issuu.com/alcorlife/docs
  3. http://www.cryonics.org/resources/long-life-magazine

External links