Last week my brother asked my friend a common
question, “If you could go back in time and kill Hitler as a baby, would you?”
After asking, he pointed out that killing Hitler might not save the world from
the kind of hardship Hitler created. Perhaps if the world hadn’t learned the
lessons it learned during WWII, it would have been forced to learn them some
other way. I told him I followed his argument, but I made an additional point
and said that neither he, nor any of his friends would be here today if he were
to go back and kill Hitler. I went on to say that no one under the age of 60
would be here today if Hitler had not existed. My brother and our friend
disagreed with me on this point. Sternly. It didn’t sound right to them. But
after a few minutes I was able to convince them otherwise. Let’s see if I can
convince you.
To start we have to discuss the nature of
stochasticity. Stochastic processes are processes where there are so many
moving and interacting parts that it is impossible for a human to observe a
starting state and make a precise prediction about how things will end up. They
are the purview of thermodynamics and chaos theory. They involve phenomena that
appear to vary in a random or chaotic manner and include processes like the
growth of a population of bacteria, an electrical current fluctuating due to
thermal noise, and the movement of a molecule of gas. Many processes are
stochastic. Stochastic models are used in chemistry, physics, biology, computer
science, economics and many others.
You have heard of the “butterfly effect” right? The
idea is that one flap of a butterfly’s wings can alter wind current and
atmospheric pressure in a way that could potentially be responsible for a storm
on a different continent. Now adding a butterfly wing beat in South America is
not going to change the weather in Africa a second later. However, as more time
passes, the butterfly’s tiny push will have effects that ripple outwards into
the environment. As you can imagine the existence or nonexistence of WWII would
have profound and far-reaching ripples.
Most of what goes on inside our cells is stochastic.
Our brain activity, and our reproductive biology are also highly stochastic.
This means that the butterfly effect comes into play whenever we make a
decision, and whenever a person is conceived. So a major change in the Earth’s
sociopolitical timeline is going to have significant repercussions that reach
down to cellular and molecular scales. It is pretty clear to see that miniscule
changes in stimulus reception by the brain have cascading effects on downstream
biological outcomes. Outcomes like mate choice, fertilization, and conception.
Consider this. A healthy man’s ejaculate contains
hundreds of millions of sperm. That means that even a slight perturbation
during the act of sex (a small change in the force of thrust, or a fraction of
millisecond change in timing) could easily result in a different sperm
fertilizing the egg. That sperm decides 50% of the DNA and determines whether
the offspring is male or female. It is very clear that tiny variations at a
molecular level can have profound consequences.
If you were comparing two timelines, one where you
friend says a single extra word at parting, and another one where he doesn’t,
that difference will alter your trip home to see your spouse. That word may
have delayed your departure by less than a second, but nevertheless it could
result in a chain of causal events that will slightly throw off the time you
arrive home. This in turn could throw off a reproductive event. But the act of
sex aside, miniscule variations in perceived events play roles in how the
information in our brain is processed. Since our brains process stimuli
stochastically there is no telling what kind of difference a single word can
make. It could cause a person to make different decisions, pursue different
interests, and even develop a different personality.
I have heard people talk about WWII for as long as I
can remember. I have heard the word and related words thousands of times. I
have taken semester long history courses on the topic. I clearly would not be
the same exact person I am today if none of this had occurred. But even more to
the point, everyone I have been exposed to has had the same experience. Our
personal identity is very fragile. It is a tiny twig at the end of a tremendous
branching structure that has branched innumerable times since our birth. Taking
a slightly different branch at age four could create irrevocable changes to who
we are as a person that are then compounded over time.
Now you may point out that there are hunter-gatherer
groups that have been relatively isolated from the rest of the world, that they
would not have been affected much by WWII, and that people born within such
groups would still be alive today if WWII had never occurred. But I disagree.
The world wars altered plane and boat schedules dramatically and spotting
planes and boats would have affected the lives of hunter-gatherers when they
saw them. Add to this that there is no tribe on earth that has been completely
isolated from outside contact, and that a single visit, or even just a small
change in timing in such a visit, would have grossly altered the cascade of
neurological and reproductive causality for the people of the tribe.
If the 1940 had played out differently, I would not be
here for one million reasons. Let me give you a few straightforward ones. A few
minutes after my paternal grandfather left his station abord a Navy ship to
check his mail during WWII, a bomb destroyed his deck and most of the men that
worked there with him. If he had not decided to check the mail on a whim, I
would not be here. He then met my grandmother after the war. If the war had
never occurred, they likely would never have met or gotten married. As another
example, my father got to know my mother due to chance. He noticed that she was
talking while walking along an elevated rocky surface and that the rock looked
slippery. He went below her, and when she fell, he caught her. They got to know
each other because of this uncommon, relatively improbable interaction. Many
couples meet under improbable circumstances.
Now there are people that were born before World War 2
that are still alive today. So it is not possible to generalize this concept to
everyone alive in 2021. However, I would take the general line of reasoning
expounded above to conclude that if a prominent historical figure who lived
before the 20th century (Shakespeare, Napoleon etc.) had never been born that
absolutely no person living today would still be alive because of the
far-reaching nature of stochastic processes. That is not to say that the world
would not be incredibly similar to the way it is today. It is just to say that
people who look identical to us, with our names, our DNA, and our personal
identities would not be here.
I posted the question that this blog entry addresses
on Quora. I received a few different answers from people with advanced degrees.
They seemed to believe that if Napoleon Bonaparte had never been born, that
they, their friends, and everyone else would still be alive today. I’d like to
think that if they read this blog entry that they would be convinced otherwise.
Specifically, I asked:
If a prominent historical figure who lived before the
20th century (Shakespeare, Napoleon etc.) had never been born would anyone
living now still be alive today given the nature of stochastic processes?
A man with a Ph.D. in statistics answered:
“That’s a strange question. I wouldn’t expect the
absence Shakespeare to have much effect on whether you or I would be here.”
https://www.quora.com/If-a-prominent-historical-figure-who-lived-before-the-20th-century-Shakespeare-Napoleon-etc-had-never-been-born-would-anyone-living-now-still-be-alive-today-given-the-nature-of-stochastic-processes
So far we have asked how much an important person
would alter history. A similar question would ask if an unimportant person can
appreciably alter history. One might
ask, “would I be alive if the least causally important adult person were erased
from history.” If that person lived more than 1000 years ago, then I believe
that I would not be alive. It might be impossible to know, and you might need a
computer the size of (identical to) our universe to run a proper model of it to
test the prediction.
