How Cryonics Works

­Cryonics is the practice of preserving human bodies in extremely cold temperatures with the hope of reviving them sometime in the future. The idea is that, if some­one has "died" from a disease that is incurable today, he or she can be "frozen" and then revived in the future when a cure has been discovered. A person preserved this way is said to be in cryonic suspension.

To understand the technology behind cryonics, think about the news stories you've heard of people who have fallen into an icy lake and have been submerged for up to an hour in the frigid water before being rescued. The ones who survived did so because the icy water put their body into a sort of suspended animation, slowing down their metabolism and brain function to the point where they needed almost no oxygen.

Cryonics is a bit different from being resuscitated after falling into an icy lake, though. First of all, it's illegal to perform cryonic suspension on someone who is still alive. People who undergo this procedure must first be pronounced legally dead -- that is, their heart must have stopped beating. But if they're dead, how can they ever be revived? According to scientists who perform cryonics, "legally dead" is not the same as "totally dead." Total death, they say, is the point at which all brain function ceases. Legal death occurs when the heart has stopped beating, but some cellular brain function remains. Cryonics preserves the little cell function that remains so that, theoretically, the person can be resuscitated in the future.

­If ­you decide to have yourself placed in cryonic suspension, what happens to you? Well, first, you have to join a cryonics facility and pay an annual membership fee (in the area of $400 a year). Then, when your heart stops beating and you are pronounced "legally dead," an emergency response team from the facility springs into action. The team stabilizes your body, supplying your brain with enough oxygen and blood to preserve minimal function until you can be transported to the suspension facility. Your body is packed in ice and injected with heparin (an anticoagulant) to prevent your blood from clotting during the trip. A medical team awaits the arrival of your body at the cryonics facility.

Once you are transported to the cryonics facility, the actual "freezing" begins. Cryonics facilities can't simply put their patients into a vat of liquid nitrogen, because the water inside their cells would freeze. When water freezes, it expands -- this would cause the cells to simply shatter. The cryonics team must first remove the water from your cells and replace it with a glycerol-based chemical mixture called a cryoprotectant -- a sort of human antifreeze. The goal is to protect the organs and tissues from forming ice crystals at extremely low temperatures. This process, called vitrification (deep cooling without freezing), puts the cells into a state of suspended animation.

Once the water in your body is replaced with the cryoprotectant, your body is cooled on a bed of dry ice until it reaches -130 C (-202 F), completing the vitrification process. The next step is to insert your body into an individual container that is then placed into a large metal tank filled with liquid nitrogen at a temperature of around -196 degrees Celsius (-320 degrees Fahrenheit). Your body is stored head down, so if there were ever a leak in the tank, your brain would stay immersed in the freezing liquid.

Cryonics isn't cheap -- it can cost up to $150,000 to have your whole body preserved. But for the more frugal futurists, a mere $50,000 will preserve your brain for perpetuity -- an option known as neurosuspension. Hopefully for those who have been preserved this way, technology will come up with a way to clone or regenerate the rest of the body.

If you opt for cryonic suspension, expect to have some company. Several bodies and/or heads are often stored together in the same liquid-nitrogen-filled tank.

­Doz­ens of people are being stored in cryonic facilities. Probably the most famous of them is baseball legend Ted Williams (see below). But no one has actually been revived, because the technology to do so still does not exist.

Critics say companies that perform cryonics are simply bilking people out of their money with the promise of an immortality they cannot deliver. Even scientists who perform cryonics say they haven't successfully revived anyone -- and don't expect to be able to do so in the near future. One of the problems is that, if the warming process isn't done at exactly the right speed, the cells could turn to ice and shatter.

Even though people in cryonic suspension haven't yet been revived, living organisms can be -- and have been -- brought back from a dead or near-dead state. Defibrillators and CPR bring accident and heart attack victims back from the dead on an almost daily basis. Neurosurgeons often cool patients' bodies so they can operate on aneurysms -- enlarged blood vessels in the brain -- without damaging or rupturing them. Human embryos that are frozen in fertility clinics, defrosted and implanted in a mother's uterus grow into perfectly normal human beings.

Cryobiologists are hopeful that a new technology called nanotechnology will make revival a reality someday. Nanotechnology uses microscopic machines to manipulate single atoms -- the tiniest units of an organism -- to build or repair virtually anything, including human cells and tissues. The hope is that, one day, nanotechnology will repair not only the cellular damage caused by the freezing process, but also the damage caused by aging and disease. Some cryobiologists predict that the first cryonic revival might occur somewhere around the year 2040.

­The first person to be cryogenically frozen was a 73-year-old psychologist, Dr. James Bedford, wh­o was suspended in 1967. His body is reportedly still in good condition at Alcor Life Extension Foundation.

The idea that a person could be frozen and then brought back to life when the technology had evolved far enough originated with the book "The Prospect of Immortality," written by physics teacher Robert Ettinger in 1964. The word "cryonics" is derived from the Greek term for "cold."

By the late 1970s, there were about six cryonics companies in the United States. But to preserve and then maintain each body indefinitely was so expensive, many of these companies wound up closing shop by the following decade.

Today, only a handful of companies offer full cryosuspension services, including Alcor Life Extension Foundation in Arizona and the Cryonics Institute in Michigan. In early 2004, Alcor had more than 650 members and 59 patients in cryopreservation.

For more information on cryonics and related topics, check out the links on the next page.