Human cryopreservation, often referred to as cryonics or, more precisely, biostasis, is an advanced medical procedure that seeks to pause the dying process using cryogenic temperatures. It is performed on individuals after they have been pronounced legally dead, with the goal of preserving them in a state of biological stasis until future medical technology may be capable of treating their cause of death, repairing accumulated damage, and restoring them to full health. This practice is not a guarantee of future life but rather an ambitious medical intervention, a bridge to a potential future where today's untreatable conditions may become curable.
What is Cryonics? A Bridge to a Future Hospital
At its core, human cryopreservation is the practice of preserving a human body, particularly the brain, at the temperature of liquid nitrogen ($-196^{\circ}$C) after legal death has been declared.1 The fundamental premise is that death is a process rather than an instantaneous event. By intervening quickly after the heart stops, it is possible to halt the cellular degradation that leads to irreversible biological decay. This places the patient in a state of biostasis, where all metabolic activity is effectively stopped, allowing them to be preserved indefinitely without further deterioration.1
This concept is often best understood through the "ambulance to the future" analogy.3 When a person has a condition that today's hospitals cannot treat, cryopreservation acts as a form of ultimate emergency medicine. It transports the patient through time to a "future hospital" where the necessary technology for treatment might exist. This challenges the conventional definition of "end of life." The development of cardiopulmonary resuscitation (CPR) in the 1960s transformed what was once considered final death (cardiac arrest) into a treatable medical event. Similarly, cryopreservation proposes that what is considered "death" today may simply be a reflection of the limits of current medical capabilities.1
To better align the procedure with its medical and biological underpinnings, and to distance it from science-fiction connotations, organizations like Tomorrow Bio prefer the term "biostasis".4 Biostasis is a state of suspended animation that occurs naturally in some organisms. Cryopreservation is currently the most advanced method developed to induce this state in humans.5 While revival from this state is not currently possible and its future feasibility remains unknown, there is no fundamental biological or physical law that proves it to be impossible.1