For as far back
as we can trace our existence, humans have been fascinated
with death and resurrection. Nearly every religion in the world
has some interpretation of them, and from our earliest myths to the latest cinematic blockbusters,
the dead keep coming back. But is resurrection really possible? And what is the actual difference between
a living creature and a dead body, anyway? To understand what death is,
we need to understand what life is. One ancient theory
was an idea called vitalism, which claimed
that living things were unique because they were filled
with a special substance, or energy, that was the essence of life. Whether it was called qi, lifeblood, or humors, the belief in such an essence
was common throughout the world, and still persists
in the stories of creatures who can somehow drain life from others, or some form of magical sources
that can replenish it. Vitalism began to fade
in the Western world following the Scientific Revolution
in the 17th century. René Descartes advanced the notion that the human body was essentially
no different from any other machine, brought to life by a divinely created soul
located in the brain's pineal gland. And in 1907, Dr. Duncan McDougall
even claimed that the soul had mass, weighing patients immediately
before and after death in an attempt to prove it. Though his experiments were discredited,
much like the rest of vitalism, traces of his theory
still come up in popular culture. But where do all these discredited
theories leave us? What we now know is
that life is not contained in some magical substance or spark, but within the ongoing
biological processes themselves. And to understand these processes, we need to zoom down
to the level of our individual cells. Inside each of these cells, chemical reactions
are constantly occurring, powered by the glucose and oxygen
that our bodies convert into the energy-carrying molecule
known as ATP. Cells use this energy
for everything from repair to growth to reproduction. Not only does it take a lot of energy
to make the necessary molecules, but it takes even more
to get them where they need to be. The universal phenomenon of entropy means that molecules will tend
towards diffusing randomly, moving from areas
of high concentration to low concentration, or even breaking apart
into smaller molecules and atoms. So cells must constantly keep
entropy in check by using energy to maintain
their molecules in the very complicated formations necessary for biological functions
to occur. The breaking down of these arrangements
when the entire cell succumbs to entropy is what eventually results in death. This is the reason organisms
can't be simply sparked back to life once they've already died. We can pump air into someone's lungs, but it won't do much good if the many other processes
involved in the respiratory cycle are no longer functioning. Similarly, the electric shock
from a defibrillator doesn't jump-start an inanimate heart, but resynchronizes the muscle cells
in an abnormally beating heart so they regain their normal rhythm. This can prevent a person from dying,
but it won't raise a dead body, or a monster sewn together
from dead bodies. So it would seem
that all our various medical miracles can delay or prevent death
but not reverse it. But that's not as simple as it sounds because constant advancements
in technology and medicine have resulted in diagnoses such as coma, describing potentially
reversible conditions, under which people would have previously
been considered dead. In the future, the point of no return
may be pushed even further. Some animals are known
to extend their lifespans or survive extreme conditions by slowing down their biological processes to the point where
they are virtually paused. And research into cryonics
hopes to achieve the same by freezing dying people
and reviving them later when newer technology
is able to help them. See, if the cells are frozen,
there's very little molecular movement, and diffusion practically stops. Even if all of a person's cellular
processes had already broken down, this could still conceivably be reversed
by a swarm of nanobots, moving all the molecules
back to their proper positions, and injecting all of the cells
with ATP at the same time, presumably causing the body
to simply pick up where it left off. So if we think of life
not as some magical spark, but a state of incredibly complex,
self-perpetuating organization, death is just
the process of increasing entropy that destroys this fragile balance. And the point at which
someone is completely dead turns out not to be a fixed constant, but simply a matter
of how much of this entropy we're currently capable of reversing.
