On the other hand, I am skeptical of extreme optimism about such matters. In his book Live Long Enough to Live Forever, the inventor Ray Kurzweil predicts that immortality will be attained in the next few decades. If you can manage to live long enough to survive to that point, you will live forever. Personally, I feel quite confident that you, dear readers, will die, and so will I.
If you are a long-term optimist but a short-term pessimist, what should you do? Why not prepare for your demise by joining Alcor? Dunk your body into a liquid nitrogen time capsule, so that it might last the centuries or eons required for humanity to master not only the art of immortality but also that of resurrection. Cryonics is a temporary measure, practiced by forward-looking members of a civilization advanced enough to make liquid nitrogen, but not advanced enough to live forever.
By now everyone seems to have heard of cryonics. (Some people say “cryogenics,” but this refers to the generic study of low temperatures, not to the bid for immortality.) The turning point of public awareness was probably 2002, when the baseball star Ted Williams died. His son and daughter by his third marriage sent the body to Alcor for preservation. His daughter by his first marriage filed a lawsuit, citing the request Williams made in his will for cremation. During the bizarre court battle that followed, Alcor sat on the sidelines waiting for the verdict while Williams’s severed head and body, chilled but not frozen, sat in their warehouse. Ultimately, Alcor received the rest of their fee and laid the athlete’s remains to rest in liquid nitrogen.
According to my reading of public opinion, people are now becoming more willing to at least entertain the claims of cryonics. Alcor members have gone further, believing fervently enough to invest money in freezing. Religion has long been successful at convincing people to believe in the incredible. In 1917, a crowd of seventy thousand gathered near the Portuguese village of Fatima to witness the sun change colors and dance wildly in the sky, while three shepherd children proclaimed their visions of the Blessed Virgin Mary and the rest of the Holy Family. Every year, millions of pilgrims now voyage to the site of the “Miracle of the Sun,” which was officially acknowledged by the Roman Catholic Church in 1930.
The pollsters tell us that 80 percent of Americans believe in miracles. I have heard some Christians scoff at such stories, regarding belief in miracles as primitive and vulgar. But let’s not forget that Christianity makes much ado about the most famous miracle of all, the resurrection of Jesus Christ. According to the Roman Catholic doctrine of transubstantiation, miracles continue to happen every Sunday in every church, when the wafer and the wine are transformed into the body and blood of Christ. If you are religious, it is rational and consistent to insist on the miraculous. What other evidence can you have for the existence of forces that are supernatural?
Today we have fallen in love with another source of miracles. In the days preceding June 29, 2007, thousands of fanatics throughout the United States assembled in front of shrines to the technology of Apple Incorporated. Within the first day and a half of the iPhone launch, 270,000 customers had converted. Millions more followed suit by the end of the year. In the frenzy leading up to the most anticipated new release of the decade, some bloggers had dubbed it the “Jesus phone.”
Judging from the excitement that it inspired, the iPhone was clearly out of the ordinary. One might even call it a modern miracle. If you think that’s hyperbolic, imagine how the iPhone would be viewed by someone who lived in the nineteenth century. According to Clarke’s Third Law of Prediction, “Any sufficiently advanced technology is indistinguishable from magic.” Through a steady stream of miracles, technology has persuaded us of its amazing powers. A new cult of technological optimism has deeply embedded itself in the zeitgeist.
John the Baptist told us that the Messiah would come and that the Kingdom of God was nigh. Technology’s prophet is Ray Kurzweil, and its gospel is his 2005 book, The Singularity Is Near. I’ve already mentioned Moore’s Law, which describes the exponential growth in computational power that has astounded us over the past forty years. By extrapolating this glorious past to the future, and to other technologies beyond computers, Kurzweil presents a vision of a future that knows no limits.
His boundless optimism reminds me of Leibniz, whose views on perception I talked about earlier. Leibniz taught that we live in the best of all possible worlds, a doctrine that he deduced from a simple argument: Since God is perfect and all-powerful, surely he would never create anything less than the best world. Leibnizian optimism is mainly remembered through its lampooning by the French philosopher Voltaire. In the satirical novel Candide, the learned Dr. Pangloss tries to convince the other characters of the world’s perfection, seemingly unaware of the evil and mayhem that surrounds them wherever they go.
Of course we don’t live in the best of all possible worlds, but just wait—technology will get us there. Such is the Panglossian promise of Kurzweil. The whiff of possibility has drawn people to cryonics. In my opinion, their suspension of disbelief is a sign that they accept mechanism. That’s the philosophical doctrine that the body—and therefore the brain—is nothing more than a machine. Granted, our bodies are much more sophisticated than the machines we make, but in the end, mechanism says, there is no fundamental difference.
We have resisted the doctrine for a long time. Even in the nineteenth century, some biologists stuck to the idea of a “vital force” present in living organisms and absent from the laws of physics and chemistry. In the twentieth century, advances in the field of molecular biology pushed “vitalism” to the wayside. Many still cling to some form of dualism, the idea that mental phenomena depend on something nonphysical, such as the soul. But plenty of people have been convinced by the discoveries of neuroscience that there is no “ghost in the machine.”
If the body is a machine, why can’t it be repaired? That possibility doesn’t seem to violate the laws of logic or physics, assuming that you accept the doctrine of mechanism. In The Sword and the Stone, his telling of the legend of King Arthur, T. H. White satirized totalitarian societies by describing a colony of ants living in a nest with every entrance decorated by the slogan “Everything not forbidden is compulsory.” Kurzweil has updated Leibniz, telling us that “Everything possible is inevitable.”
But as every inveterate dreamer hates to be reminded, there are lots of possibilities that we never end up pursuing. Any decision involves weighing costs and benefits. Reanimation may be possible, but at what cost? Yes, a human life is priceless—but what if no bank contains enough money to pay? For example, suppose that reanimation is possible in principle, but in practice would require more energy than exists in the known universe. At some point, the constraint of finite or expensive resources starts to matter.
The difficulty of reanimation also matters for Alcor members, because it determines their time horizon. A wonderful selling point of cryonics is that while submersed in liquid nitrogen you can wait for all eternity and never get bored. But can you count on your resting place to remain intact? What is the chance that Alcor will still exist by the time reanimation becomes feasible, if it takes a million years of technological progress to reach that point?
Some believers in cryonics may choose to turn a blind eye to practical considerations. But those who are skeptical by nature will have to consider Ettinger’s Wager. Pascal argued that there’s no need for calculation, because the wager is for an infinite jackpot. Yet in reality, nothing about our universe is truly infinite. The rational decision-maker must, in the end, actually perform the probabilistic calculations. Although no one really knows the numbers involved, at the very least an estimate can be made. Doing that in an informed way requires some study of the scientific and medical issues.
It’s true that any machine can be kept running indefinitely by replacing its broken parts. In 2007 the world’s oldest running car was auctioned off. “La Marquise,” which has a steam engine rather than an internal combustion engine, was built in 1884 by De Dion, Bouton et Trépardoux, th
e largest automobile manufacturer in the world for a time. But the price the car fetched—$3.2 million—tells you just how rare it is for a very old car to be in working order. Automobiles are generally designed to last for about a dozen years of use. Beyond twenty-five years of age, a car is considered an antique. Maintaining it longer than that is not cost-effective if the only goal is transportation; replacement parts are expensive to make in small quantities and to install piece by piece. Keeping a car running forever is worth doing only for aesthetic or sentimental reasons.
Of course, there are better reasons to keep humans running. Sometimes bodies can be repaired by replacing parts at great cost. Organ transplantation is made possible by drugs that suppress the recipient’s immune system, preventing it from attacking the donor organ. It would be better to avoid the immune reaction altogether by using an organ made of cells that are genetically identical to those of the recipient. Right now this is possible only when transplanting an organ from one identical twin to another. But tissue engineers have the dream of culturing organs in vitro, by growing cells on artificial scaffolding. If they are successful, it will become possible to take cells from someone, grow an organ from them, and transplant the cultured organ back into the person. No donor would be necessary.
Optimistic though we may be about future advances in organ replacement, there’s a fundamental limitation: The brain is an organ that cannot be replaced. That’s not a statement about the technical difficulty of a brain transplant. What I’m talking about is the issue of personal identity, illustrated nicely by the true story of Sonny and Terry.
In 1995 Sonny Graham received a heart donated by Terry Cottle, who had committed suicide. In a surprising turn of events, Terry’s widow, Cheryl, married Sonny nine years later. Four years into their marriage, Sonny committed suicide in the same way that Terry had, shooting himself in the head. The tabloids went crazy with headlines like “Suicide Claims Two Men Who Shared One Heart.”
Reporters and bloggers erupted with wild speculations and questions. Did the transplanted heart contain memories that made Sonny fall in love with Cheryl? Did it drive Sonny to suicide, just as it had done to Terry? The story became less mysterious when the police found that Cheryl had been married five times, reportedly driving all of her husbands to despair. After receiving Terry’s heart, Sonny was still Sonny. His personal identity remained intact. It’s doubtful that it was the transplanted heart that made Sonny fall in love with Cheryl. More likely, he was attracted to Cheryl because she was attractive. (After all, she did manage to secure five husbands.)
In contrast, let’s consider a hypothetical brain transplant. The procedure is impossible today, but it makes for an interesting thought experiment. Suppose Terry’s brain had been transplanted into Sonny’s body. It would not make sense to say that Sonny had received Terry’s brain, since the postsurgical Sonny would not be the Sonny his friends knew. If they asked, “Sonny, remember the time we . . . ?” they’d get a blank stare in return. We might say instead that Terry had received Sonny’s body. In other words, we could call it a body transplant rather than a brain transplant. Then Cheryl’s second encounter with a suicidal husband might have a different explanation.
The bizarre story of Sonny and Terry introduces an important point for cryonics: Preservation of the brain is the pivotal issue. Most Alcor members have chosen the cut-rate option of freezing only their heads, believing—presumably—that any future civilization advanced enough to resurrect them will be advanced enough to replace their bodies. But will this future civilization also be able to revive their frozen brains?
This question faces anyone deciding whether to engage Alcor’s services, but I think it’s profoundly interesting even for those who don’t care a whit about Alcor. Reanimation is the ultimate challenge for the doctrine of mechanism. Philosophers can argue until they’re blue in the face, and scientists can uncover all the evidence they want, but they can never completely convince us that the body and the brain are machines. The final proof will come only when engineers manage to construct machines that are just as complex and miraculous. Or when they can bring dead bodies and brains back to life by repairing them like cars.
In a more practical vein, we can view the Alcor question as an extreme version of one asked in hospitals. Friends and family of a patient lying in coma would like to know: Will she ever wake up? Like the brains of the comatose, Alcor’s brains have been damaged. Both types of brains blur the line between life and death. What are the fundamental limits of restoring life to damaged brains? Once again, we cannot properly address this question without considering connectomes.
Alcor’s procedures are based on a field of science known as cryobiology. You probably know that fertility doctors freeze sperm, eggs, and embryos for later use. Blood banks freeze rare blood types for transfusion years later. The classic method is to lower the temperature slowly, say one degree per minute, after immersing cells in glycerol or other cryoprotective agents that increase their survival rate. The method is far from perfect. Sperm survive the best; eggs and embryos do less well. Cryobiologists would like to freeze entire organs, since it is wasteful to discard them just because immediate transplantation is not possible.
Slow freezing was discovered mainly by trial and error. To improve on the method, cryobiologists have tried to understand why it works. It’s not easy to sort out the complex phenomena happening inside cells during cooling. One thing is certain: The formation of ice inside cells is lethal. It’s not known why intracellular ice kills, but cryobiologists know to avoid it at all costs. Slow freezing is intended to cool cells so that the water outside freezes to ice while the water inside does not.
How is that possible? If you live in a cold climate, you’ve probably seen people scattering salt on the sidewalk during a winter snow. This prevents ice from forming (and people from falling), because salt water freezes at a lower temperature than pure water. The higher the concentration of salt, the lower the freezing point. When cells are cooled slowly, water is gradually sucked out of them owing to a force known as osmotic pressure. The water remaining in the cell becomes saltier and saltier, and hence resists icing. If cells are cooled too rapidly, however, their contents don’t become salty enough, and they freeze, with deadly consequences.
Slow freezing is not completely benign, because it replaces ice with saltiness. The latter, though not as deadly, is still damaging to cells, and additives like glycerol can protect only so much. Some researchers have therefore given up on slow freezing. Instead, they cool cells under special conditions that turn liquid water into an exotic state of matter that is said to be glassy or “vitrified,” from the Latin word for glass. The vitrified state is solid but not crystalline. Its water molecules remain disorganized; they’re not arranged into the orderly lattice you see in ice crystals.
Under normal circumstances, vitrification requires extremely rapid cooling, which is feasible for cells but not entire organs. Alternatively, you can get water to vitrify even at slow cooling rates if you add extremely high concentrations of cryoprotectants. Fertility researchers are already applying this method to oocytes and embryos, with some success.
Greg Fahy, who works at a company called 21st Century Medicine, has worked for decades on the problem of cryopreserving organs. Fahy has used an electron microscope to examine vitrified tissues. The process appears to protect cellular structures, with relatively little damage to membranes. But disappointingly, vitrified organs failed the acid test repeatedly over the years: They didn’t survive and function after rewarming and transplantation. In a remarkable advance, Fahy’s team has at last succeeded, demonstrating recently that a previously vitrified kidney functioned for weeks after transplantation into a rabbit. Inspired by Fahy’s research, Alcor now uses vitrification to preserve the corpses of its members.
So how long can those corpses stay frozen without damage? You’ve probably noticed that items in your freezer do not last indefinitely. This has no bearing on cryonics, because the –196
degrees of liquid nitrogen is far colder than your freezer gets. It is closer to the lowest temperature possible—“absolute zero,” or –273 degrees. Cold temperatures preserve because they slow down chemical reactions, the transformations that alter the atomic structure of molecules. The extreme cold of liquid nitrogen halts chemical reactions almost completely. The molecules in the corpses do not change, except when they are hit by cosmic rays or other types of ionizing radiation. Since such collisions are rare, the physicist Peter Mazur has estimated that cells should last for thousands of years in liquid nitrogen. The clock may be ticking for Alcor members, but they have at least a few millennia before their time runs out.
There’s a more fundamental problem, though. The Alcor members were all dead before they were vitrified, for hours or sometimes even days. Isn’t death irreversible, by definition? If so, how could reanimation ever succeed?
Irreversibility is indeed a central aspect of our definition of death. This makes the definition problematic. Irreversibility is not a timeless concept; it depends on currently available technology. What is irreversible today might become reversible in the future. For most of human history, a person was dead when respiration and heartbeat stopped. But now such changes are sometimes reversible. It is now possible to restore breathing, restart the heartbeat, or even transplant a healthy heart to replace a defective one.
Conversely, even if the heartbeat and respiration continue, a person with sufficiently severe brain damage is now regarded as legally dead. This redefinition was spurred by the introduction of mechanical ventilators in the 1960s. These kept accident victims alive so that the heart still pumped, even though the patient never regained consciousness. Eventually the heart stopped, or family members requested removal of the ventilator. At autopsy, the organs of the body looked perfectly normal to the naked eye or under a microscope. But the brain was discolored, soft or partially liquefied, and often disintegrated as it was removed. From this condition, nicknamed “respirator brain,” pathologists concluded that the brain had died well before the rest of the body.
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