The American Heritage Dictionary defines “random” as:
having no specific pattern, purpose, or objective.
If scientists are correct that many natural processes are actually random--like the
random mutations that form a fundamental part of the modern theory of evolution, or
the inherent randomness of quantum mechanics--does this mean that nature is
fundamentally without “pattern, purpose, or objective?” Is nature fundamentally disordered?
We often consider order and randomness to be complete opposites,
but when we look at some common examples, we can see them existing side by side.
Imagine emptying your junk drawer into a big box--filling
it with keys, expired coupons, pens and pencils, takeout menus, whatever.
If you shake the box and look inside, you’ll see a random collection of stuff bouncing around. If
you stop shaking it, you’ll see that same random collection of stuff, sitting still.
Now, imagine dumping a bunch of ping pong balls into the box and doing the same thing. If you
shake the box and look inside, you’ll still see a random, chaotic mess. But, if you stop shaking it,
a very visible and specific hexagonal pattern will emerge.
Both of these are random processes--very clearly so while they are in motion, but
also in their end results. If we numbered the ping pong balls or painted them different colors,
which ping pong ball ended up where would be unpredictable and random, even though the overall
hexagonal pattern would always remain the same. How does this order arise out of randomness?
The answer comes down to symmetry. Because the ping pong balls are all spheres of the same size,
they tend to arrange themselves in the particular pattern we observed, known as “hexagonal packing.”
From a physics perspective, this is just a process of minimizing gravitational energy
as the motion stops--that is, of cramming as many of the ping pong balls as close to the bottom of
the box as possible. This energy minimization process was also occurring in our previous
example with the junk drawer box. But, since its contents were all different shapes and sizes,
no consistent, obvious pattern emerged. It might seem like this
nice hexagonal symmetry comes out of nowhere--some sudden order out of randomness--but if you look at
it from the right perspective, you can see that we actually lost some symmetry in the process.
Let me break this down for you. The hexagonal pattern is a six-fold symmetry,
in the sense that there are six ways that I could rotate it and still get the same
general pattern. It’s a bit more complicated in three dimensions, with lots of ping pong balls, but it is a finite symmetry.
But each of the individual ping pong balls is a sphere which could be rotated by any angle
and any axis and look basically the same. The higher symmetry of the individual spheres,
(the infinite symmetry in this case) is “broken down” into a finite hexagonal period when they are all piled together.
This sort of hexagonal packing shows up all over the place in nature. For example, you can think
of honeycombs, or the heads of some flowers, or even a zoomed-in close up of an insect eye.
This pattern of higher symmetries breaking down to reveal new “lower” symmetries
goes beyond simple geometry. In physics, there are complex mathematical symmetries at
work in how we understand what electrons, quarks, and other fundamental particles are
and how they interact with one another. Those symmetries are, in a sense,
“broken down” as these fundamental particles combine to form protons and neutrons, and eventually atoms. But, in doing so, they reveal
“lower” symmetries of a kind, that we find in the periodic table that are newer and, in many ways, more diverse. Those
new symmetries are then broken down further as these atoms are arranged into molecules--revealing
even more new patterns, shapes, and symmetries of chemistry and paving the way for the diversity and beauty we
find in the biological world. The motion and activity of the individual constituents are
usually random and fairly unpredictable, but the patterns that emerge are usually very stable and extremely comprehensible.
The biologist Stephen J. Gould popularized a thought experiment of rewinding the tape of life,
claiming that, because of the randomness and variability of evolutionary biology,
if we were able to rewind history hundreds of millions of years to some arbitrary point and
let evolution run its course again, we would end up with a completely different taxonomy of life -- different plants and animals.
Now, apparently, some biologists contend that things might not be as different
as Gould suggested, claiming that certain patterns and properties of animals and plants
could be predicted to arise, no matter what. But as a physicist, I’m more interested in the idea of running the
tape of the universe back further and further, all the way to the Big Bang even. As best we can tell,
right after the Big Bang happened 13.8 billion years ago, the universe was a hot dense quantum
mess undergoing a chaotic explosion. If we were able to rerun the history of
the universe from that moment, a great number of things about our universe would be very different.
The Sun, the Earth and the other planets of our solar system, and the rest of the Milky
Way galaxy wouldn’t exist as we know it. The particular distribution of stars and galaxies
that form our universe and our familiar night sky would all be redistributed as a result of
random quantum fluctuations in the early universe. That being said, much about the structure
and the nature of the universe would remain exactly the same. The physical matter making
up the universe would still be distributed into photons, electrons, and quarks with
exactly the same properties in roughly the same proportions, which would lead to similar
distributions of protons and neutrons--and then the same distribution of atoms in the periodic table. While the particular
location and distribution of stars and galaxies would vary, the general structure and history of
individual galaxies, stars, and even the planets would have unfolded much like our own universe did.
It’s fairly certain that even the properties of basic chemistry--like the formation of molecules
like ammonia and water, and even some carbon based organic chemistry like benzene rings--would
have unfolded in just the same way. It is hotly debated whether life--as we
know it or otherwise--would have necessarily developed in this “rewound” universe. Yet,
as unreliable as our biology textbooks might be in that universe, it’s likely that our physics
textbooks and large swathes of our chemistry textbooks would survive with only minor revisions.
There are many processes in the natural world that are chaotic and random,
at least in practice and most likely in principle as well.
But, this does not mean that the natural world is completely random, or that it is fundamentally
disordered or unintelligible. In fact, randomness at one level often gives rise to order
at a different level, and the way order seems to arise “out of randomness” in the natural world is
almost always a sign of a deeper order and structure that we don’t always notice at first.
In fact, it is arguably precisely by giving up on the desire for complete order, stability,
and predictability in every familiar physical process that scientists have
actually come to a deeper understanding of the existing patterns and order present in nature.
By letting go of the presumption that “order” and “intelligibility” would mean a sort of
clockwork “precision” and “predictability,” we have not only come to understand significantly
more profound truths about the order, structure, and causes present in our universe: we have also
come one step closer to glimpsing the wonderful creativity of the God who established that order.
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