Cryonics
Cryonics is the low-temperature preservation of humans and animals that can no longer be sustained by contemporary medicine until resuscitation may be possible in the future. Currently, human cryopreservation is not reversible, which means that it is not currently possible to bring people out of cryopreservation. The rationale for cryonics is that people who are dead by the current legal or medical definitions are not necessarily dead by the information-theoretic definition of death[1]; and that people could be brought out of cryopreservation in the future.
In the United States, cryonics can only be legally performed on humans after they have been pronounced legally dead. The word cryonics is derived from the Greek word κρύος (kryos), meaning cold. Note that "cryonics" is often mistaken for the concept of suspended animation.
Premises of cryonics
The central premise of cryonics is that memory, personality, and identity are stored in cellular structures and chemistry, principally in the brain. While this view is widely accepted in medicine, and brain activity is known to stop and later resume under certain conditions, it is not generally accepted that current methods preserve the brain well enough to permit revival in the future. Cryonics advocates point to studies showing that high concentrations of cryoprotectant circulated through the brain before cooling can prevent structural damage from ice, preserving the fine cell structures of the brain in which memory and identity presumably reside Obstacles to success
In the United States, cryonics can only be legally performed on humans after they have been pronounced legally dead. The word cryonics is derived from the Greek word κρύος (kryos), meaning cold. Note that "cryonics" is often mistaken for the concept of suspended animation.
Premises of cryonics
The central premise of cryonics is that memory, personality, and identity are stored in cellular structures and chemistry, principally in the brain. While this view is widely accepted in medicine, and brain activity is known to stop and later resume under certain conditions, it is not generally accepted that current methods preserve the brain well enough to permit revival in the future. Cryonics advocates point to studies showing that high concentrations of cryoprotectant circulated through the brain before cooling can prevent structural damage from ice, preserving the fine cell structures of the brain in which memory and identity presumably reside Obstacles to success
Preservation injury
Long-term cryopreservation requires cooling to near −196 °C (−321 °F), the boiling point of liquid nitrogen. It is a common mistaken belief that cells will lyse (burst) due to the formation of ice crystals within the cell, but this only occurs if the freezing rate exceeds the osmotic loss of water to the extracellular space (and it is virtually impossible to cool a large tissue that quickly). However, damage from freezing can still be serious; ice may still form between cells, causing mechanical and chemical damage. Cryonics organizations use 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 freezing of whole people still causes injuries that are not reversible with present technology
Financial issues
Long-term cryopreservation requires cooling to near −196 °C (−321 °F), the boiling point of liquid nitrogen. It is a common mistaken belief that cells will lyse (burst) due to the formation of ice crystals within the cell, but this only occurs if the freezing rate exceeds the osmotic loss of water to the extracellular space (and it is virtually impossible to cool a large tissue that quickly). However, damage from freezing can still be serious; ice may still form between cells, causing mechanical and chemical damage. Cryonics organizations use 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 freezing of whole people still causes injuries that are not reversible with present technology
Financial issues
Costs of cryonics vary greatly, ranging from $28,000 for cryopreservation by the Cryonics Institute, to $155,000 for whole body cryopreservation for the American Cryonics Society’s most expensive plan. Alcor’s whole body preservation is priced at $150,000 (or $80,000 for neuropreservation of the head alone) plus a ~$500 annual membership fee during life by Alcor. After payment of an initiaton fee, ACS full members pay an annual fee of $300 currently.
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