How Things Work: Cryonics

What do Captain America, Fry (Futurama), and Austin Powers have in common?

They have all been frozen and kept in suspended animation for many years, then thawed out and miraculously brought back to life. This process is known as cryonics, where living beings are frozen to temperatures of approximately –384°F — when nitrogen is in its liquid state. The first cryonics technique was developed in 1990 by cryobioligists Gregory Fahy and Brian Wowk.

At temperatures below freezing, cellular metabolism slows and eventually halts when sufficiently low temperatures are achieved. This is the reason why you feel sleepy when the weather is cold, and how certain mammals hibernate over winter; in the cold, their metabolism drops to such low rates that they barely need food or oxygen to survive.

Cryonics takes this phenomenon to a higher level by freezing bodies at temperatures so low that cellular metabolism stops entirely. At these temperatures, the process of natural decay halts as well — meaning that the bodies can, theoretically, be preserved eternally.

The largest difficulty with cryogenic preservation is, unsurprisingly, ice.

During the process of freezing, jagged ice crystals begin forming within semi-frozen body fluids, puncturing cells and causing permanent structural damage to tissues.
In order to prevent this from happening, cryonics subjects must have most of their bodily fluids replaced with specially designed anti-freezing agents, which stop crystals from forming.

These anti-freezing chemicals allow ice to form without ice crystals in a process called vitrification, allowing the body to be cooled to near absolute-zero temperatures safely.

Due to the ethical concerns and inherent dangers, currently it is only legal in the United States to perform cryonics on people who have been pronounced legally dead.
In other words, you cannot ask to be frozen while you are alive. Being legally dead, however, is not the same as being completely dead. A person is declared legally dead if his or her heart stops beating. Most human cells take a long time to actually die after legal death, and brain function may persist for hours.

It is during this crucial period between legal death and complete death that the cryonics emergency response teams must rush to work.The (legally) dead body is quickly cooled to below freezing temperatures, which immediately slows cellular metabolism and brain function, slowing the decay of bodily tissue.
Heparin, a blood-thinning agent, is injected into the body to prevent blood clotting, and pumps are used to continue circulation of blood and oxygen as the body is quickly transported to the freezing facility.

Upon arrival, the pumps begin circulating anti-freezing agents in place of bodily fluids, while the body is maintained at very low temperatures. Once the body is saturated with antifreeze, the temperature is quickly lowered to under negative 202°F and vitrification occurs, causing the antifreeze to solidify.
Once the body is frozen solid, it is lowered into a storage container filled with liquid nitrogen, where it will sit until the day it is removed to be thawed.

Judging from several cryonics institutes’ websites, the price of cryopreserving a human being can range from just under $30,000 to over $150,000, not including membership fees, yearly subscriptions, and preparation and thawing fees.

Of course, the most important part of cryogenic preservation would be the hopes for eventual revival. In this aspect, scientists universally agree that there is no viable solution within the short-term future that will permit the complete resuscitation of a frozen human body.
However, there remains hope that, given sufficient advancement in medical technology, there may one day emerge technologies capable of repairing the damages done to cellular tissue during the trauma of death and freezing.

After all, a frozen body is essentially in stasis — assuming the freezing temperature is maintained, the body can literally be kept for centuries in perfect preservation exactly the same as the day it was frozen.

With an eternity to wait, the few brave undertakers of cryonic preservation are staking their lives on the idea that medical science will one day be able to reawaken them.
According to an FAQ by Alcor, one of the leading cryonics foundations, the only intractable problem with cryonics may be the issue of memory preservation. While future medical science may be capable of overhauling cells on a molecular basis — which could potentially repair any damage done both before death and during the process of freezing — information and memory loss may be inevitable.

The earliest patient of cryonics, one James Bedford, was frozen in the year 1967 at the ripe old age of 72 — although baseball player Ted Williams is perhaps the most well-known person to opt for cryonics after death.

Today, there are around 200 bodies being cryogenically preserved in the United States alone.