Cryonics is almost universally panned by scientists. Could there be any light at the end of the tunnel?
Cryonics, in short, is the freezing of a patient who can no longer be sustained by current medical technology in the hope that future medical advances will allow them to be reanimated.
The theory sounds like science fiction, and, at this stage, it is. The science of cryonics is met by staunch skepticism and a strong dose of derision.
But is it really so far-fetched?
Although the idea of freezing and reanimating humans after death has been in popular culture for some time, it was not until the 1960s when a physics teacher - Robert Ettinger - first presented cryonics as a genuine possibility.
Ettinger's book, The Prospect of Immortality, published in 1962, argues that diseases and conditions that are fatal today, might not be in the future. If we could freeze and store a recently (or almost) dead person, we might be able to fix their ailment further down the line and bring them spluttering back to life.
Cryonics in 2016
There are a small number of cryonics companies who take this area of investigation incredibly seriously. They will happily freeze you (or your pet) for a not-so-small fee. One of the largest cryonics companies charges upward of $200,000, plus a yearly subscription fee.
Globally, there are only four facilities set up to freeze bodies - three in the US and one in Russia; an estimated 250 humans have been cryogenically preserved as of 2015 and another 1,500 have signed up.
How does it work? In an ideal world, the cryonics company is able to reach the patient just after the heart has stopped beating but before the brain has died. This allows them to restart the heart and lungs, although the patient is clinically dead.
Initially, the body is dropped to 0°C in an ice bath while respiration and heartbeat are mechanically maintained; heparin is injected to prevent the blood from coagulating, along with a host of other chemicals.
Next, the blood is removed and replaced by cryoprotectants that defend cells from the damage caused by ice crystals developing between cells. This process leads to a state called "vitrification," in other words, crystallization during freezing is prevented and, instead, a "solid liquid" or "glassy state" is produced.
The body is eventually dropped to temperatures of -130°C and below using nitrogen gas. And there you will remain. Indefinitely.
The technology of freezing without damaging tissue has been the main thrust of cryonics research over the decades. But, of course, that is less than half of the battle; reversing the freezing and restoring life are the real stumbling blocks.
Cryonics has never enjoyed any popularity among the scientific populace, and, in the 1970s, its reputation took a substantial kick. The Cryonics Society of California, led by a former TV repairman - Robert Nelson - made it into the news for all of the wrong reasons.
Nelson's organization ran out of money and could no longer fund the preservation of the chilled cadavers it was storing. He was sued for leaving nine bodies to unceremoniously decompose.
The majority of mainstream scientists and medical professionals do not give cryonics researchers much favor. Some scientists simply mumble their dissent under their breath, others are vibrantly venomous, including neuroscientist Michael Hendricks, who refers to cryonics as:
"An abjectly false hope that is beyond the promise of technology and is certainly impossible with the frozen, dead tissue offered by the 'cryonics' industry. Those who profit from this hope deserve our anger and contempt."
Science does not seem to hold out much hope for the possibility of cryonics. It certainly has an incredibly long path ahead of it, and there is no telling whether that path leads to a pot of gold or a brick wall. However, there are some reasons to pass a sympathetic gaze over the field.
The shifting sands of death
The statement "a dead person cannot be revived" seems so obvious that it is hardly worth writing down, but when you look a little deeper, it is not so clear cut.
Could a dead person ever be revived?
A few decades ago, someone who suffered a cardiac arrest was considered irreversibly dead.
Move forward to today, and we routinely bring those people back from the brink. So, in some regards, our definition of what constitutes "dead" has shifted.
It is this kind of stance that cryonics researchers often take when faced with dissenters.
Their argument, whether you are prepared to run with it or not, is that death has already had its goal posts moved, so who is to say that they cannot be moved again?
Today, brain death, rather than cardiac death, is considered the stamp of finality. But even this, it might be argued, is not entirely infallible. For instance, in 1955, James Lovelock cooled a rat to just above 0°C. Its brain completely stopped its normal business. However, Lovelock managed to reanimate the rodent by warming it back up.
More recently, pigs were given the same freeze-to-death-warm-to-life treatment with an impressive degree of success. Even after having their blood almost entirely removed and their internal temperatures dropped to 10°C for 60 minutes, the majority survived.
In a similar experiment, pigs were also found to be neurologically normal after their ordeal. Their ability to learn new tasks was still intact, as was their ability to remember tasks learned prior to their "death."
Ice bath trauma care
Even more recently, in 2015, UPMC Presbyterian Hospital in Pittsburgh, PA, began a groundbreaking new treatment for victims of severe traumas, such as gunshot wounds and knife attacks.
The medical team replaces the patient's blood with a cold saline solution that rapidly cools the body and stops almost all cellular activity, including brain activity.
Cells at cooler temperatures need less oxygen, so a significant drop means that brain tissue can survive longer. This state of "induced hypothermia" gives surgeons more time to treat the injuries before returning the blood back to the system.
On the next page, we look at some more surprising examples of life after death, some pitfalls of nomenclature and the many practical problems facing cryonics.