Cryonics, often incorrectly called cryogenics, is the practice of preserving a legally deceased human body at ultra-low temperatures. This preservation usually occurs in liquid nitrogen at -196°C, with the hope that future medical technology can repair the damage caused by the process and the underlying cause of death. While people are actively being cryopreserved today, no human or complex mammal has ever been successfully revived from this state, meaning the prospect of revival remains entirely theoretical. This differs from medical cryopreservation, which is a well-established technique used to store individual cells, embryos, or tissues, as these require far less complex repair than an entire organism.
The Current State of Cryopreservation
Cryonics does not fall under the umbrella of regulated medical treatment because the procedure only begins after a person has been declared legally dead. Instead of a medical service, it is a contractual arrangement for the long-term storage and maintenance of human remains. Organizations like the Alcor Life Extension Foundation and the Cryonics Institute manage the preservation process as non-profit or legally distinct entities.
The process requires a legally binding contract to ensure the procedure can commence immediately following death. This quick transition is paramount to minimizing cellular damage from lack of oxygen. As of the mid-2010s, approximately 250 individuals had undergone cryopreservation, with thousands more having made financial and contractual arrangements. Because of its non-medical status, the success of the endeavor relies on the long-term solvency and technical competence of these specific organizations.
The Step-by-Step Process
The preservation process is designed to halt biological decay and prevent the formation of damaging ice crystals. The first step involves rapid cooling, often using an ice bath and cardiopulmonary support equipment, immediately after legal death is pronounced to reduce the body’s metabolic rate. Once stabilized, a crucial surgical step called perfusion takes place, where the patient’s blood is replaced with a complex chemical solution.
This solution is composed of cryoprotectant agents (CPAs), which act like a medical-grade antifreeze. CPAs, such as glycerol or dimethyl sulfoxide, are circulated through the vascular system to minimize the concentration of water inside the cells. The goal is to achieve vitrification, the transformation of the body’s tissues into a solid, glass-like state without forming destructive ice crystals. Vitrification bypasses the damage caused by ice crystals by increasing the viscosity of the water until it solidifies like glass when cooled below the glass transition temperature, typically around -130°C.
After vitrification, the patient is slowly cooled down to the final storage temperature of -196°C over several days in a computer-controlled cooling unit. The individual is then placed head-down into a large, vacuum-insulated container called a dewar, which is constantly maintained using liquid nitrogen. At this ultra-low temperature, all chemical and biological activity is effectively suspended, allowing for potential storage that could last for centuries.
Scientific Hurdles to Revival
While vitrification prevents large-scale ice damage, the process introduces challenges that must be overcome for revival to be possible. The most immediate obstacle is the toxicity of the cryoprotectant agents themselves. The high concentrations of CPAs required for complete vitrification are chemically damaging to cells and tissues, making them currently incompatible with life.
Another hurdle is the difficulty of reversing the process without causing new damage. Re-warming a large, vitrified mass without causing fracturing or renewed ice formation is technically difficult. Furthermore, some microscopic structural damage still occurs, particularly within the neural circuits of the brain. Restoring the brain is paramount because the individual’s identity and memory are stored in its structure, requiring a degree of cellular repair currently far beyond medical capabilities. Successful revival would likely require highly advanced, molecular-scale repair machines, or nanobots, capable of fixing this damage cell by cell—a technology that does not yet exist.
Practicalities of Signing Up
Securing a cryopreservation contract involves significant financial and legal commitments. The cost for whole-body preservation varies significantly between organizations, ranging from tens of thousands to over $200,000. This expense is most commonly funded through a dedicated life insurance policy, which names the cryonics provider as the beneficiary to ensure funds are available immediately upon legal death.
Comprehensive legal planning is necessary to ensure the organization has the authority to take possession of the body and begin the procedure without delay. The plan also requires arrangements for a specialized standby and transport team to be deployed upon imminent death. This immediate availability is necessary because minimizing the time between circulatory arrest and the start of stabilization is the most important factor for maximizing the quality of the preservation.