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 sourcesthat 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 ongoingbiological 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 oxygenthat our bodies convert
into the energy-carrying moleculeknown 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 tendtowards diffusing randomly,
moving from areasof high concentration to low concentration,
or even breaking apartinto smaller molecules and atoms.
So cells must constantly keepentropy 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 cellsin 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 advancementsin technology and medicine
have resulted in diagnoses such as coma,
describing potentiallyreversible conditions,
under which people would have previouslybeen considered dead.
In the future, the point of no return may be pushed even further.
Some animals are knownto 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 moleculesback 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 lifenot as some magical spark,
but a state of incredibly complex,
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.