From Chapter 6 of Future Rising: A Journey from the Past to the Edge of Tomorrow
In a 2018 ranking of US states by road quality, Florida and Hawaii did pretty well, but my former state of Michigan did not. In fact, the report confirmed Michigan’s dubious status as the pothole capital of the country—something my bones can vigorously attest to!
Potholes may seem a far cry from the future of the universe, yet they are both tied together by a natural tendency that threads through the cosmos: entropy.
Entropy is one of those concepts that people often invoke when they try to explain life, the universe, and everything, yet is rarely understood—much to the chagrin of physicists the world over. Despite this, it plays an important role in determining how and why the universe behaves as it does, as it slips from past to future.
Entropy is related to the amount of usable energy in a system—the energy that you can actually put to work to achieve something. The greater the entropy, the less usable energy there is. The idea goes that, if you have an imbalance in energy between one object and another—say, for instance, between a cool Earth orbiting a searing hot sun, or a really hot cup of coffee and a pair of cold hands—you can make that energy work for you by moving it from one place to another. But when the imbalance has been eliminated, you’re done. You can no more make use of energy when any energy difference has gone than you can make water flow uphill. As energy is used, imbalances are reduced, and entropy increases. And potholes, it turns out, are a symptom of this.
Potholes are, unfortunately, part of the natural future state of roads. They’re what roads aspire to, if only people would leave them alone. And they are an inevitable outcome of entropy. To make sense of this, think of roads as objects that represent massive amounts of stored energy in the form of the work that goes into making them straight, smooth, and durable. As a result, there’s an energy imbalance between them, the environment, and the tires that they’re constantly being pounded by. As that energy difference is evened out, with a little help from the elements and daily wear and tear, cracks and crevices form and ultimately turn into potholes. And as they do, entropy increases.
Without regular repairs, our roads would simply get more and more potholed until they become impossible to use. It’s a very real and frustratingly tangible example of entropy as it acts as the inexorable “arrow of time.” And it’s one that reminds us that, not only is the future inevitable, but when left to its own devices, it’s likely to be rougher than the past.
This is the same process that many scientists believe is leading to the universe winding down. Experts are still uncertain whether we’re ultimately heading for a big crunch—a fitting mirror to the big bang, where everything contracts back into a pre-big-bang singularity—or a big freeze, where the universe simply slows down and stops. Many scientists suspect that increasing entropy will ultimately lead to what they refer to as “heat death,” where all the usable energy in the universe has been, not to put too fine a point on it, used up.
It’s the celestial equivalent of the universe becoming so potholed that it’s impossible to drive on it any more.
In the grand scheme of things, this is one future that the laws of physics indicate is likely to occur—a predictable pathway toward a dead universe, where increasing entropy has sucked the marrow out of every atom and every molecule. It’s a default future that has little time for the complexity of living organisms. Yet, far from slipping toward heat death, Planet Earth has somehow spawned organisms that can seemingly reverse the universe-wide flow of entropy. And because of this, we have emerged as creatures that can not only imagine the future, but also intentionally alter it.