R. J. Riggins: Thermodynamics for Two, Please

“Thermodynamics” sounds really scientific, and intimidating as all get out. We’ve all known people who drop names, or toss around impressive jargon to make themselves look important or smart. And we’ve probably all seen someone who, showing off, misuses a technical word, or otherwise goofs up, and manages to make a complete fool of himself in the presence of a real expert. I’ve even known people who, thus caught out, try to maintain the bluff and make fun of the truly knowledgable person, in an effort to save face before their friends. We’ve all seen that, especially among children.

Something mighty close to that is what is happening whenever someone tosses out a line like, “Evolution is impossible because it breaks the Second Law of Thermodynamics.” I know for a fact that I’ve heard that from folks who haven’t a clue what any of the Laws of Thermodynamics are. But they’ve heard that really impressive-sounding line used in a lecture, or a tract, or maybe one of those tiny little comic books, or from behind a pulpit–and because it sounds so scientific, they adopt it as one of their one-line slogans that “disprove” evolution.

I promise not to get technical here, and I don’t think I could if I wanted to. I would be trying to run an intimidating bluff if I did. I imagine that I learned the Laws of Thermodynamics in high school physics. But stated in their usual dry, “scientific” language, they didn’t make much of an impression on me at the time. I didn’t really grasp how they related to the earth or life or daily life. They seemed to have to do with the temperature of water in various boring lab-table “experiments”, and I knew darn well they would be on the exam, and I would probably get them confused with a lot of other equally dry laws and such, that all seemed to be named after Italians and Germans. I first really “got it”, though, when a writer (maybe Asimov?), in an SF magazine (maybe Analog?), cast the Laws of Thermodynamics into a simple poker-player’s analogy:

• You can’t win.
• You can’t break even.
• And you can’t get out of the game.

Wow! Now I get it. I can see what that would mean in terms of energy, instead of money. The Universe is the House, the Great Casino. Or maybe it’s God who is the Great Dealer, who controls the deck, and always takes His percentage, so that in the long run the player is broke, and his chips–his heat energy–is dissipated into the void, unrecoverable.

Somewhere along the line I ran into that slogan: evolution is contrary to the Second Law of Thermodynamics. I am far from being a physicist, but I knew immediately there had to be something wrong with that. First of all, I knew that there wasn’t any war between physicists and biologists about whether evolution broke a major law of nature. If physicists didn’t see a problem, I figured they probably had a deeper understanding of the matter than the person throwing that slogan around. Then after remembering, more or less, what the Second Law is, I saw what seemed to me a really obvious and simple solution.

The Second Law of Thermodynamics is You can’t break even. If you do work, if you use energy, if you convert it from one form to another, you will lose some of it. No machine can be 100% efficient. If you burn coal to make steam, to drive a generator, to make electricity, to heat a home–you’ll end up with less heat than you originally got from the coal. You always lose in this game. You can never recover the energy you lost. All you can do is try to lose as little as possible. The creationist looks at this game and says, “See, life should be going downhill, gaining entropy (becoming less organized), losing energy, and generally falling apart. Life has defied those rules, become more organized, brought order out of chaos. Since that’s forbidden by the Second Law of Thermodynamics, then it had to be a miracle.”

After pondering this dilemma for about three seconds, the answer was plain. In this game we are penny-ante players. “We” is the whole Earth. The high roller at this table, the billionaire playboy who can lose a thousand dollars a hand and never miss it, is Old Man Sol. We–living things on the Earth–are petty players indeed, compared to him. He places a huge bet every hand, and loses every time, but as he shoves his chips to the Dealer, a few drop into our laps. We sneak a few out of the pot. The Dealer doesn’t mind. The House is gaining steadily, and the players, as a whole, are losing. If the tiny Earth, at the end of the table, seems to be getting ahead, sneaking chips from Sol, it’s no matter. They’re mere pennies compared to Sol’s huge losses. And even the measly chips snatched by Earth–our apparent “winnings”–are only temporary. They, too, will eventually be forfeit to the House. And we can’t get out of the Game.

For the literal-minded (and to avoid floundering too long in my own analogy), these are the facts. The Sun, every second, burns up tons of its hydrogen fuel, losing forever some of its mass, converted to energy (its entropy increases). A micro-fraction of that mega-wattage is intercepted by living things on the Earth, which store some of it, use it to build up biomass, and use it in all the ways life uses energy. Most of that is lost quickly too, through the inefficiencies of living “machinery”. Some is stored, though, and some is used to build up more complex molecules, molecular systems and life forms (locally, entropy decreases). But that’s very locally, compared to the vast sphere of “wasted” energy radiating away from the sun. And the decrease in entropy is vanishingly small, compared to the huge increase in entropy in the solar system as a whole. And remember, whatever life temporarily “harvests” will eventually be lost also. (People are especially good at that: look at how fast we’re burning our way through the fossil fuels that it took living things epochs to capture from the sun.)

So where is the “violation of the Second Law”? The Law does not say that in every part of a system, at all times, entropy can only increase. If that were the case, no machine, mechanical or living, could ever work, because that’s what a machine does: temporarily and locally, entropy is decreased, at the expense of a larger, permanent increase elsewhere in the system. The Law says that in the system as a whole, in the long run, entropy must increase. And it certainly does in the solar system. We’re sticking our tiny waterwheel into the vast outflow of a reservoir that will never be refilled. We’re warming ourselves by the exhaust pipe of a huge diesel, that is gradually emptying its fuel tank. We are not breaking the Second Law of Thermodynamics. Not now, and not in the formation and evolution of life.

Isn’t all this pretty blatantly obvious? Then how can people keep hauling out this “breaking the Second Law of Thermodynamics” nonsense? My guess is that a lot of them have little or no grasp of these simple physics concepts, and it sounds “real scientific”, and it backs up their prejudices about how things have to be, so why not quote it and try to sound smart? I think a lot of it also comes from the old notion that the Earth is the biggest, most important thing around. Any decrease in entropy here seems huge. In our everyday experience, it looks like we can win, or at least break even. In our subconscious, the old, geocentric, sun-hung-in-the-firmament-to-give-us-light picture of the universe endures, because that’s the way things look in our daily experience. 30% or so of American adults still think the Sun orbits the Earth. It’s hard to grasp how insignificant our tiny, local reversal of entropy really is, and that the Sun’s loss, on the scale of billions of years, really is an irreversible loss. Our little niche of life doesn’t begin to compensate. On our scale of lifetimes, it’s hard to get the big picture. Some of us are like the tourist in Vegas, who walks away with a pocketful of quarters from the slots, and $100 from the blackjack table, thinking he’s made a killing, amazed at how the casino can stay in business, losing so much money to sharks such as he.

And now for the irony (if not to say hypocrisy). Here’s a guy who says that the evolution of life breaks the Second Law of Thermodynamics. He says that’s impossible, because nothing can break that Law. (Add in the chutzpah of thinking that he knows physics better than the average Nobel laureate.) Then what’s his solution? Miraculous creation. If one dares to point out to him, then, that supernatural creation, ala Genesis, is in fact truly contrary to the natural laws of the universe, including his favorite Second Law, his response may be something to the effect that God is outside those laws. He makes the laws, and can break them any time He sees fit. So that “crime” (against the laws of nature) doesn’t count. That seems about as far as that sort of person can think. He seems to be saying, “You guys can’t do that; it’s against the rules of the Game (but I’ve made up different rules for myself).” He has rationalized his preconceived notion with scientific-sounding reasoning, and thrown in a statement of faith, to boot. His reasoning never seems to extend this far: if evolution violates the Second Law (it doesn’t, but just suppose), and if God can violate that Law any time he sees fit, then why can’t it be God that makes things evolve? If any answer at all is forthcoming, it can be summarized as follows: “It don’t say that in the Bible, so it ain’t true.” *** R. J. Riggins
riggins@outreach.rice.edu
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