from quarks to mind
IS OUR EXISTENCE INEVITABLE?
Gleiser is the Appleton Professor of Natural Philosophy and
Professor of Physics and Astronomy at Dartmouth College and
the author of A
Tear at the Edge of Creation: A Radical New Vision for Life
in an Imperfect Cosmos. This essay originally appeared
a look at your hands. In them, you find atoms that once belonged
to stars dead more than five billion years ago. Those stars,
bigger than our sun, forged much of the chemistry of life during
their last moments, before exploding into giant supernovae.
They forged chemical elements spread through the interstellar
medium, collecting here and there in self-gravitating hydrogen
clouds. Occasionally, these clouds would become unstable to
their own gravity and contract. These contracting nebulae gave
rise to stars and their orbiting planets, trillions of them
in our Milky Way alone. In at least one of them, elements combined
in incredibly complex ways to create living creatures. And of
these myriad beings, one developed mind, the ability to sustain
complex thoughts and to wonder about its origins.
are, in a very real sense, self-aware stardust.
all the stars had to start with was hydrogen and gravity. As
gravity compressed the hydrogen gas to enormous pressures, hydrogen
fused into helium, climbing the first step of the chemical ladder.
For most of their life, stars kept this fusion process on. As
they ran out of hydrogen in their core, they started fusing
helium into carbon, then oxygen and nitrogen, and so on all
the way to uranium. That's what stars do, they make chemical
the modern scientific view, we are what happens when you give
hydrogen and gravity a few billion years.
are many gaps to fill in this cosmic narrative, and this is
what makes science exciting. As we thrust ahead, we learn more
about the universe and our place in it. Perhaps one of the most
controversial questions that follows from this discussion concerns
our inevitability. Is our existence an inevitable consequence
of the laws of Nature? Or are we an accident, and the cosmos
could equally well exist without us?
hard line scientific position would answer that all we can do
is explain what we measure. There is no purpose or plan, just
what happens. And what we measure tells a story that starts
at least with quarks (the particles that make up protons and
neutrons), electrons, and radiation, and ends, a few billions
later, with life and humans. As we move on from the early universe
populated with quarks one-millionth of a second after the big
bang to the star-studded cosmos of today, there is no question
that matter became more ‘complex,’ in the sense
that more complicated structures arose as time went by. I don’t
think anyone in his/her right mind would argue that a cosmos
filled with a soup of elementary particles and radiation is
less complex than one filled with stars, planets and people.
So, we see a connection between the arrow of time and the increase
in complexification of the natural world. Why?
venturing down this road, we should pause for a second and contemplate
the beauty of this achievement. We humans have come to understand,
at least in part, this grand epic of creation from its origins
to today. And what we’ve learned speaks of our deep connection
with the cosmos, not just because we live in it but because
we are made of it. If we are bits of star stuff -- as is any
other aggregation of matter across space -- we are one with
the cosmos: we are in the cosmos and the cosmos is in us.
doubts that science is a deeply spiritual endeavor should reflect
upon this. The very concrete data gathering and theorizing that
are the trademarks of science and that make up most of a scientist’s
everyday activities are all part of this quest. Some may stop
there and not bother to look around, and that’s fine.
But if you do take a step back and lift your head, the truth
is obvious for all who want to see it: Science responds to the
same spiritual need for meaning that has been with us since
the dawn of humanity.
if we return to our existence and ask if we are inevitable,
what can we say? Yes, there is an obvious increase in complexification
as you go from quarks to mind. And yes, there could be a hidden
principle out there explaining why this is so. But could it
have been otherwise, that is, could the universe and, in particular,
life on Earth, have developed so that we wouldn’t be here?
From what we know now, the honest answer is yes. If we look
at the way in which life evolved here at least, we see contingency
playing a big role: change this or that cosmic event and life
would have taken another turn. Dinosaurs were here for 150 million
years and were doing fine until the big rock came from the sky
and killed them. Before the dinosaurs, for the first three billion
years, life here was mostly bacteria. So, it’s hard to
state with confidence that there is an imperative for complex
intelligent life to exist in the universe -- Although many do.
On the other hand, even if we don’t think there is an
imperative for our existence, we are here, products of 13.7
billion years of cosmic evolution. And that is a fact.
you choose to respond to this question tells much about who
you are and what you believe in. If you think there is some
kind of cosmic teleology, a sense of purpose that inevitably
leads to life, you are saying we are inevitable. If you don’t,
if you say we are the result of a series of cosmic accidents,
then you believe we aren’t inevitable. We just happened.
This latter position is often accused of being nihilistic: if
we are the results of accidents, what’s the point of being
since we presently lack a principle explaining our inevitability,
I’d argue that precisely because we are the result of
accidents we are very important. We don’t have to be the
result of a grand plan to have a sense of purpose. Going further,
I’d claim that our purpose comes from our rarity, from
the fact that at least as far as we know we are the only beings
capable of thinking about our existence. So, the point of being
the result of an accident and yet being alive and intelligent
is to celebrate and protect that what made us possible: our
universe and our planet. Until we find a principle explaining
our cosmic inevitability, this gives me plenty to work with.