Words cannot describe death, for those who have experienced it have not the power to express anymore. Death is reality – an integral part of life – an absolute balance to nature – the finishing touch of a complete life cycle.
But what if this cycle can be terminated to form a linear life with no end? What is the prospect of immortality, if ever created, by mere mortals?
In 1962, Michigan College physics teacher Robert Ettinger published a book which addressed an analogous issue: Cryonics.
Cryonics is derived from the Greek word κρύος (kryos), meaning icy cold. It is the process of cryopreservating of a body to liquid nitrogen temperature to stop the natural decay processes that occur after death. Cryonics practitioners hope that future technology will allow the legally deceased person to be restored to life when and if science is able to cure all disease, rejuvenate people to a youthful condition and repair damage from the cryopreservation process itself.
The basic principle of cryonics is that memory, personality, and identities are stored in the structure and chemistry of the brain. If this states can be preserved and can be restored, it is possible to revive the state of a patient.
To achieve a long-term cryopreservation, requires cooling to near -196 °C, the temperature of liquid nitrogen. Cooling whole people to this temperature causes injuries that are not reversible with present technology. When untreated tissue is slowly cooled below the freezing point of water, ice forms between cells, causing mechanical and chemical damage. Cryonics uses cryoprotectants to reduce this damage.
Cryoprotectant solutions are circulated through blood vessels to remove and replace water inside cells with chemicals that prevent freezing. This can reduce damage greatly but not enough for whole people to recover spontaneously from cryopreservation. When used at high concentrations, cryoprotectants stop ice formation completely. This process of cooling and solidification without freezing is called vitrification.
It is universally agreed by scientists and cryonics advocates that reversing human cryopreservation is not possible with “any near-term technology.” Those who believe that revival may someday be possible generally look toward advanced bioengineering, molecular nanotechnology and nanomedicine where molecular-level repair and regeneration of damaged tissues can be achieved.
Revival of cryopreserved patients
Revival of cryopreserved patients requires repairing damage from lack of oxygen, cryoprotectant toxicity, thermal stress (fracturing), freezing in tissues that do not successfully vitrify, physical therapy to regain function of the body (similar to that of a long-term coma), and reversing the effects that caused the patient death. In many cases extensive tissue regeneration will be necessary. Hypothetical revival scenarios generally envision repairs being performed by vast numbers of microscopic organisms or devices. These devices would restore healthy cell structure and chemistry at the molecular level, ideally before warming.
Forms of Cryonics
There are two distinct preservation options in cryonics: “whole body preservation” or “Neuropreservation” (sometimes called “neuro”). The latter is the cryopreservation of only the brain, usually within the head, with surgical removal and disposal of the rest of the body.
Neuropreservation is motivated by the fact that the brain is the primary repository of memory and personal identity. (For instance, spinal cord injury victims, organ transplant patients, and amputees retain their personal identity.) It is also motivated by the belief that reversing any type of cryonic preservation is so difficult and complex that any future technology capable of it must by its nature be capable of generalized tissue regeneration, including regrowth of a new body around a repaired brain. Some suggested revival scenarios for whole body patients even involve discarding the original body and regenerating a new one because tissues are so badly damaged by the preservation process. These considerations, along with lower costs, easier transportation in emergencies, and the specific focus on brain preservation quality, have motivated many cryonicists to choose neuropreservation.
Companies offering Cryopreservation
The largest current practitioners of cryonics are two member-owned, non-profit organizations, the Alcor Life Extension Foundation in Scottsdale, Arizona, with 77 cryopreserved patients and the Cryonics Institute in Clinton Township, Michigan with 85.
The picture below shows “bigfoot” Dewar which is custom-designed to contain four wholebody patients and six neuropatients immersed in liquid nitrogen at −196 degrees Celsius. The Dewar is an insulated container which consumes no electric power. Liquid nitrogen is added periodically to replace the small amount that evaporates the container.
It has been claimed that if technologies for general molecular analysis and repair are ever developed, then theoretically any damaged body could be “revived”. Disease and aging are also assumed to be reversible. Survival would then depend on whether preserved brain information was sufficient to permit restoration of all or part of the personal identity of the original person, with AMNESIA being the final dividing line between life and death – between a cycle and a linear life form.