The Canon (21 page)

The sun and Earth comprise another energy system best thought of as isolated, at least until we invent some version of a
Star Trek
warp drive and can seek out new life and new Saudi Arabias. For the time being, energy derived from solar radiation or its chemical, composted, or meteorological offspring—coal, wood, wind currents—or from the manipulation of matter on Earth in nuclear power plants or the still fanciful fusion rings, will have to suffice.

The system to close all systems, though, is the universe itself. The first law of thermodynamics applies to the entirety of the cosmos. What we have is what we've got and will always have. The energy released at the moment of the Big Bang, 13.7 billion years ago, is our first E, our final E, our only hope and dowry. No deposits, no returns, no spontaneous generation—exchanges for in-store merchandise only. This is not a bad law, really, and in a way it gives salve to the soul. For one thing, there is enough energy to fuel the 10 billion trillion stars of the 100 billion galaxies of the electromagnetically visible universe, as well as the huge quantities of dark matter and dark energy that are lightless and invisible but that we know are out there. Our universe is like a French pastry: full of air yet unspeakably rich, and really, don't you think one will do?

For the nonreligious among us, the law of the conservation of energy offers the equivalent of a spiritual teddy bear, something to clutch at during those late-night moments of quiet terror, when you think of death and oblivion, the final blinding of I. The law of conservation of energy is, in effect, a promise of eternal existence. The universe is, practically speaking, a closed system. Its total energy will be conserved. More will not be created, none will be destroyed. Your private sum of E, the energy in your atoms and the bonds between them, will not be annihilated, cannot be nulled or voided. The mass and energy of which you're built will change form and location, but they will be here, in this loop of life and light, the permanent party that began with a Bang. "Nothing is destroyed, nothing is ever lost, but the entire machinery, complicated as it is, works smoothly and harmoniously ... the most perfect regularity preserved," waxed the British physicist Joule of thermodynamic's first law. I tell this to my daughter whenever she's scared of the dark, and though she'd prefer a more personalized form of perpetuity, she's found some warmth in this thermodynamic verity. On leaving the house one frigid morning for school, she glanced wistfully at Manny, a purring, well-fed spit curl of fur tucked in the arm of the couch. "After I die," my daughter said, "I hope some of my atoms can find their way into a cat."

Just as the "First World War" carries the suggestion of others and the addition of a qualifying Roman numeral I after "Queen Elizabeth" or "King Felipe" means that others with that name have since been at least nominal heads of state, so the first law of thermodynamics sounds like we're just getting started. In fact, there are four basic laws of thermodynamics—and one of them, conceived after the first, was given the fun-loving name of "the zeroth law of thermodynamics"—but the most important by far are the first and the second. It's like the amendments to the U.S. Constitution. The first guarantees freedom of speech, press, and religion. The second protects your right to bear a howitzer. What more do you need?

As it happens, scientists view the second law of thermodynamics as a firearm of sorts, spraying a scattershot of slugs through the house, knocking pictures from the walls, blowing out the flat-screen television, and making chintzmeat of the furniture. If the first law of thermodynamics is the "good news," as Robert Hazen and James Trefil have written, "a natural law analogous to the immortality of the soul," then the
second law is the "bad news," a natural law that helps clarify why the body grows old. The second law might also be called the "Humpty Dumpty directive." Once the big, smirking, pedantic, cravated egg had his great fall, all the king's horses, all the king's men, all the plastic surgeons, duct tape, and members of the National Transportation Safety Board couldn't put Humpty Dumpty together again. The second law is the reason why either you or a hired professional must expend considerable effort to clean your house, but if you leave the place alone for two weeks while on vacation, it will get dirty for free. It explains why some drinks taste good cold, some taste good hot, and most taste lousy at room temperature—red wines, of course, excepted. The second law guarantees a certain degree of chaos and mishap in your life no matter how compulsively you plan your schedule and triple-check every report. To err is not just human: it's divined.

These are some of the philosophical implications and sneaky fine-print clauses of the second law. What are the physical principles behind it? The first, deceptively modest premise of the law is that heat will not flow spontaneously from a cold body to a hot one. If you are carrying an ice cream cone around on a hot day, the ice cream will start to melt. If you continue carrying it around on a hot day, it will melt more, dribbling down the cone, snaking over your fingers, and splattering to the ground. The ice cream will not change its mind and start to freeze up again. On the flip season, if you take your hot coffee outdoors in winter and you don't have a well-insulated mug, the coffee will quickly grow cold. It won't figure out a way of extracting and concentrating whatever small amounts of heat might be had from the moving air around it. In our universe, the spontaneous flow of heat is unidirectional, moving from a warm body to a cooler one. Time and time and time again, the warmth of the summer air will head into your ice cream, and the warmth of your coffee diffuse into the winter snap, and if you suddenly start finding otherwise, maybe it's time to consider rehab.

On a molecular level, heat's arrow makes sense. The molecules of a warm object are moving faster than those of a cool object. As the energetic particles bump into the more stately molecules, they transfer some of their energy to the slow motes, and become less energetic in the barter. The hot summer air molecules bump into the crystals of your ice cream, the crystals start jiggling and break apart; and though the air molecules right around the cone cool down slightly as they convey their verve to the ice cream, it's hard to tell when there's so much hot air to go around. In your hot coffee, the fast-moving molecules at the surface share their energy with the cold air just above them. Those heated air
molecules jiggle the air above, while the heat rising from farther down in the cup jiggles the slowed coffee molecules at the surface. In either case, for the transfer of energy from hot to cold not to occur, the cool, slow molecules would somehow have to resist the comparatively greater impact of the speedy, heated molecules, and there is no way for them, of their own accord, to rebuff the body blows.

The result of heat's natural tendency to flow from hot spot to cold is a gradual leveling and homogenization, a diffusion of energy into a limper and less organized pattern. The ice cubes in a glass of lemonade left out on a counter lose their structure. As the heat in a cup of coffee drifts into its surroundings, the molecular reactions that account for the beverage's rich, aromatic zest likewise slow down, and the coffee starts to taste bland. To maintain structure, to maintain a temperature gradient that resists the spontaneous wafting of heat toward coolness, you need an inoculum of energy. You can keep your ice nicely cubed in a freezer, but the intricate cooling mechanism of a refrigerator or freezer is driven by electricity, as are the coolant coils in an air conditioner. You can warm your house in the winter, and counter the gradual loss of that warmth into the frigid air outside, but again you need energy: a wood-burning stove, a furnace fueled by oil or natural gas. No matter how well insulated your home, still there will be a gradual loss of heat to the street, and the consequent call for fresh fodder.

This leads to the second premise of the second law, which can be simply stated as: nothing's perfect. More formally, you can never build an engine that would be 100 percent efficient, able to turn every gram of fuel you feed it into useful, honest, Protestant ethic–approved work. You cannot build a perpetual-motion machine that will keep clicking and tocking without periodic help from outside, though Leo only knows that thousands of humans from da Vinci fore and aft have tried. They fought the second law, the law won. No matter how generously lubricated an engine may be, no matter how beautifully honed and fitted its gears, some amount of the energy that drives it will be lost as heat, will be puffed into the sky rather than turned to the task at hand. Some kinetic energy will end up exciting the air molecules around the engine, or the atoms of the base surrounding the moving parts, or the bolts holding the parts together. Something, somewhere, will take the heat and squander it. Most machines, including all the small, organic ones inside the cells of our body, are far less efficient than 100 percent, or even 50 percent. Many plant species, for example, manage to translate only 5 percent of the energy coming at them from the sun into stored energy to grow on.

To understand the inevitability of inefficiency, think for a moment about a simple part of a car engine, the up-down, in-out motions of the pistons in the cylinders that turn the crankshafts. Each time a piston is thrust down through its cylinder, the air within is compressed and heated. As a result, not only is some of the energy from combustion waylaid into an unnecessary stimulation of the cylinder's air molecules, but now that hot, surly air must be removed from the cylinder before the piston cycle can begin again; otherwise, the engine will overheat and blow a fuse, pop a gasket, disengage from the vehicle's central processing unit, or otherwise cease to function. That demand means opening an exhaust valve to dump the hot air into the atmosphere, where it will abandon all pretense of productive, taxpaying citizenship and instead start mingling with other hotheaded gases that have nothing better to do than disrupt the global climate.

In sum, first you have to pay for something you didn't need or want in the first place, then you have to pay to get rid of it. Sounds like many things in life, doesn't it? Desserts and the gym, the injury you acquired at the gym when you dropped a dumbbell on your finger and the doctor's bill for sewing the finger together again, your daughter's pet African bullfrog and removal of your daughter's decomposing African bullfrog from under her bedroom floorboards. Nothing's perfect, nobody's perfect, and the smart ones don't waste too much time trying to be.

Which brings us to the third and potentially most depressing premise of the second law: every isolated system grows more disordered with time. Or, as a sign on my editor's door put it,
ENTROPY ALWAYS GETS YOU IN THE END
.

The word "entropy" has gained a certain popular cachet, and is often used as a synonym for chaos, but the two terms have distinct meanings. In physics and mathematics, chaos refers to systems like the weather, or a nation's economy, that seem random and unpredictable but that often have regular, repeated patterns underlying them—high pressure clouds, the PBS broadcasts of Suze Orman. Entropy, by comparison, is a measure of how much energy in a system is "not available to do work." The energy is there, but it might as well not be, like a taxi passing you on a rainy night with its
NOT IN SERVICE
lights ablaze, or a chair in a museum with a rope draped from arm to arm, or a teenager. Rudolf Clausius, a German physicist and thermodynamics pioneer, coined the term "entropy" from the Greek word for "transformation," and he coined it with care, to sound as much like "energy" as possible. Wherever you have energy, Clausius said, entropy is sure to follow, with crowbar in hand.

The first law of thermodynamics insists that energy can be neither created nor destroyed. The second law replies, Fine, then I'll have to settle for breaking its knees.

In a closed system, entropy creeps higher, and order slowly subsides. It is a cold, hard, tepid, flaccid, probabilistic truth. If you bring a pot of water to a full boil, put an egg in it, cover the pot with a tight-fitting lid, and turn off the flame, you'll have a reasonably isolated system. The water will be hot enough to cook the egg to a soft-boiled or medium-soft consistency. But at some point before the egg reaches the child-friendly status of maximum firmness, the system will lose its culinary power. Much of the kinetic energy that the water molecules had won through boiling will be shrugged off as heat into the air under the lid. In their less vigorous state, the water molecules abutting the eggshell cannot continue revising, linking, and cross-linking the egg proteins and cholesterol chains within. The total energy of the system may be the same as it was when the lid first descended, but it has become diffuse, and defused—it's no longer cooking with gas.

The second law, alas, has overwhelming odds in its favor. When physicists speak of an ordered system, they mean one in which the components are organized in a regular, predictable pattern, as the atoms of sodium and chloride are neatly stacked in a crystal of salt, or as books are arranged in a meticulously managed library—thematically and alphabetically. But think of that library, and how easy it is to perturb its order. You don't have to reduce the entire collection to a jumble on the floor; a single, misinserted volume is enough to ruin a scholar's whole morning. In fact, there is only one way for the books to be arranged on the shelves in a flawless Dewey-decimal sequence, but thousands upon hundreds of thousands of ways that they can be set astray. Herein lies the engine of entropy. Order, by definition, has restrictions and limitations, while disorder knows no bounds. The odds of the boiled water in our pot retaining its heat by dint of the agitated water molecules on the surface repeatedly bumping into only other water molecules below and beside them, rather than some of them slapping against the air molecules above, are infinitesimally small. In theory, it could happen, just as you theoretically could close your eyes, begin tossing a couple of hundred bricks into the corner, and find, on opening your eyes, that you've thrown them into the perfectly aligned, beautifully crafted Flemish-style hearth wall of your dreams. In probabalistic reality, you will be treated to the sight of a haphazard pile of half-cracked bricks and a haze of pulverized clay, and to the sound of the police pounding on your front door with heavy objects of their own.