At what moment are you dead Randall Hayes

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.

早在我们可以追溯到我们的存在时,

人类就
对死亡和复活着迷。

世界上几乎每个宗教
都有对它们的某种解释

,从我们最早的神话

到最新的电影大片
,死者不断地回来。

但复活真的可能吗?

无论如何,活物和尸体之间的实际区别是什么?

要了解死亡是什么,
我们需要了解生命是什么。

一个古老的理论
是一种叫做活力论的思想,


声称生物之所以独一无二,

是因为它们充满
了一种特殊的物质或能量,

这就是生命的本质。

无论被称为气、

命脉

还是体液,

对这种本质的信仰在
全世界都很普遍,

并且仍然存在

可以以某种方式从他人身上汲取生命的生物的故事中,

或者某种可以补充生命的魔法来源
的故事中。 在 17 世纪的科学革命之后,

活力论开始
在西方世界消退

René Descartes 提出了这样的概念

,即人体本质上
与任何其他机器没有什么不同,

是由位于大脑松果体中的神圣创造的灵魂赋予生命的

1907 年,Duncan McDougall 博士
甚至声称灵魂有质量,

并在患者死前和死后立即称重以试图证明这一点。

尽管他的实验
声名狼藉,就像其他活力

论一样,他的理论的痕迹
仍然出现在流行文化中。

但是,所有这些声名狼藉的
理论将把我们留在哪里?

我们现在知道的是
,生命不包含

在某种神奇的物质或火花中,

而是包含在正在进行的
生物过程中。

为了理解这些过程,

我们需要缩小
到我们单个细胞的水平。

在这些细胞中的每一个内部,

化学反应
都在不断发生,


我们的身体转化

为能量携带
分子 ATP 的葡萄糖和氧气提供动力。

细胞将这种能量
用于从修复

到生长

再到繁殖的所有事情。

不仅需要大量的能量
来制造必要的分子,

而且需要更多的能量
才能将它们送到需要的地方。

熵的普遍现象

意味着分子将
倾向于随机扩散,


高浓度区域移动到低浓度区域,

甚至分裂
成更小的分子和原子。

因此,细胞必须

通过使用能量将
其分子维持

在生物功能发生所必需的非常复杂的结构中来不断地控制熵

当整个细胞屈服于熵

时,这些安排的破坏最终导致死亡。

这就是
生物一旦死亡就不能简单地复活的原因

我们可以将空气泵入某人的肺部,

如果呼吸循环中涉及的许多其他过程

不再起作用,它就不会起到太大作用。

同样,
除颤器的电击

不会启动无生命的心脏,

而是
使异常跳动的心脏中的肌肉细胞重新同步,

使它们恢复正常节律。

这可以防止一个人死亡,
但它不会复活一具尸体,

或者用尸体缝合在一起的怪物

因此
,我们所有的各种医学奇迹似乎都

可以延迟或预防死亡,
但不能逆转它。

但这并不像听起来那么简单,

因为
技术和医学的

不断进步导致了昏迷等诊断,

描述了潜在的
可逆情况,

在这种情况下,人们以前会
被认为已经死亡。

未来,不归路
可能会被推得更远。

众所周知,有些动物可以通过将生物过程减慢到几乎停止的程度
来延长它们的寿命

或在极端条件下生存

对人体冷冻学的研究
希望

通过冷冻垂死的人
并在

以后新
技术能够帮助他们时使他们复活来实现同样的目标。

看,如果细胞被冷冻,
分子运动就会很少

,扩散实际上会停止。

即使一个人的所有细胞
过程都已经分解,

这仍然可以
通过一群纳米机器人来逆转,

将所有分子
移回其正确位置,

同时向所有细胞
注入 ATP,

大概导致
身体只需从上次停下的地方重新开始。

因此,如果我们认为生命
不是某种神奇的火花,

而是一种极其复杂、
自我延续的组织状态,那么

死亡就是
熵增加的过程,

它破坏了这种脆弱的平衡。

一个人完全死亡的时间

点并不是一个固定常数,

而只是

我们目前能够逆转多少熵的问题。