"In principle, cryonics is not impossible, but the current form of it is based largely on rank speculation and costs a load of dough. "- 
Cryonics is the low-temperature preservation of the brain, and sometimes entire body, of deceased individuals, with the hope of future revival. People preserved this way are often referred to as "patients".
- As technology advances, in the future supporters hope cryonics patients may be revived.
- Opponents suspects those who sign up for cryonics are paying out vast sums of Money for Quackery.
How plausible is cryonics? In the 1930's many sensible people were sure human beings would never get to the moon and that was just one of many predictions that turned out incorrect.  Is the essence of consciousness, memories and the personality of the dead person preserved in the preserved brain? In the early 21st Century we don't fully understand what causes consciousness and personality or how memory functions so we can't say one way or the other. Still cryonics is highly speculative and unproved at best.
The central premise of cryonics is that identity is stored in the physical structure of the brain. The brain is preserved with cryonics, and freezing damage is avoided using cryoprotectants. As medical technology increases, supporters hope in the future, cryopreserved individuals could be revived. A serious drawback is that we don't know which aspects of the brain are important to preserve.
The procedure begins as soon as possible after legal death, when the heart stops beating. The first step of the procedure is to place the patient in an ice bath, in order to cool the body. A HLR (Heart Lung Recessitator) is placed on the body, in order to continue the circulation of blood. By connecting tubes to major arteries, the blood is replaced with cryoprotectants over the course of several hours. Cryoprotectants are chemicals that prevent Water from crystallizing. The adding of cryoprotectants is known as vitrification. If cryoprotectants are not added to the body, the water inside of cells would burst as the body is frozen. The bursting of cells would cause the calls to burst, and therefore, would render the likelihood of revival to be extremely small. Vitrification prevents this, and the cellular structure of vitrified samples remains intact. After the body is vitrified, it cooled and placed into an aluminum container. The container is then placed into a bigfoot Dewar, such as the one pictured above. A bigfoot Dewar is basically a large version of a Dewar flask, which uses a vacuum as insulation. The body is kept at -196*C.
Some alternatives to the procedure of cryonics have been proposed, with the intent of preserving the brain, with the intent of revival in the future.
Plastination is one of these proposals. It is much cheaper than cryonics, and the brain after it has been plastinated can be touched without damage. However, the problem with plastination is that some decay still occurs, albeit very slowly. On the other hand, it increases the probability that the body will make it in time for sufficient nanotechnology to be developed. Cryonics requires that an organization exist that maintains the vitrified corpse. One rough year for a cryonics organization, and your brain is eaten by maggots. Plastination needs no organization to maintain the corpse. From the looks of it, plastination is a good idea, and is in some ways better than cryonics.
Freeze drying has also been proposed, although there are many problems with this proposal. A freeze dried brain would be very brittle, potentially turning to dust if handled improperly. Exposure to any moisture could also ruin the brain. From the looks of it, freeze drying is a horrible idea.
List of cryonics organizationsEdit
- Alcor Life Extension Foundation - located in Scottsdale, Arizona
- Cryonics Institute - located in Clinton Township, Michigan
- KrioRus - Headquartered in Moscow, Russia. It is the only organization that offers cryonics services in Eurasia.