The Canon (18 page)

As we'll see in the next chapter, chemistry explains why the atoms of our fingers or those of a piece of wood manage to stay together and maintain a semblance of solidity. Nevertheless, said Brian Greene, "If you could imagine zooming in close enough to see the atoms of your fingers interacting with the atoms in this table, or this chair"—he touched each item of furniture in turn—"you would see their outer electrons repelling each other with electromagnetic force. Any time you touch or feel something, that is the electromagnetic force at work.

"In fact, electromagnetism governs all our senses," he said. Sight: the electromagnetic waves that we call light waves convey their message by interacting with the electrons in the atoms of our retina. Hearing: atoms of air press against the atoms of our auditory canal, and the consequent skirmishing among electrons is interpreted by the brain as Bach's Sonata for oboe and harpsichord. Taste and smell: food atoms poke their electrons against the atoms of the taste buds on our tongue and of the olfactory receptors in our nose, and the specific pattern of taste and smell receptors thus chafed informs the brain, Roast chicken. Gee. I haven't had any of that since last night.

Even as protons and neutrons form the overwhelming bulk of matter, of our bodies, the floor beneath our feet, the stained upholstery on our seat, the leftovers we are about to eat, it is the electrons, those fidgety flecks that account for less than a tenth of 1 percent of an atom's mass, that allow us to perceive and embrace the world around us. To frame it another way, it is one electron's antipathy toward another that shields us from the essential emptiness of every entity, that allows the protons and neutrons to puff with pride and play the pooh-bah, the fat of the land. How are they to know that, when you look at a table or any other object, you're not seeing the regal nuclear particles, but rather light bouncing off the electron mask with which each atom is adorned.

Consider, then, that, while the force of gravity may keep our feet on
the ground and our planet skating around the sun, electron hostility is what makes the trip worthwhile.

I hate winter, the whole surgical tool kit of it: the scalpel cold, the retractor wind, the trocar dankness. I hate the snow, whether it's fluffy virginal or doggy urinal. I hate the inevitable harangues about how you lose 30, 50, 200 percent of your body heat through your head, because above all I hate winter hats and refuse to wear one. What happens with a hat? You take it off, and half your hair leaps up and waves about like the cilia of a paramecium, while the rest lies flat against your skull as though laminated in place.

The last section ended with a paean to electron hostility. This one begins with a peeve about electron mobility, the source of what is paradoxically, and somewhat inaccurately, called static electricity. The peeve can't last long, though, for I love subatomic nomadism when it's not wasting time raising manes or sticking skirts to stockings but is instead making itself useful by toasting bagels and running blenders, or for that matter allowing brain cells to fire or muscle cells to extend or contract. And guess whose fleet feet are behind the flicking of a switch that we in the West so take for granted and depend on that major blackouts cost billions in lost business? The electron, from the Greek word for "amber," the fossilized trickles of tree sap that, according to Greek myth, were the sun-dried tears of the gods, and that, according to Greek experience, were readily charged when rubbed with cloth.

Electrons are extremely tiny. They have mass, but the amount is so modest that they can sometimes behave almost like photons, the mass-less particles that carry light. Moreover, as far as we know, electrons are elementary particles, meaning they can't be broken down into even smaller particles. Scientists can crack apart the nuclear particles, the protons and neutrons, into even smaller subnuclear particles, called quarks. But no matter how they have slammed and shazammed electrons in the brutal conditions of a high-energy particle accelerator, they have not found subelectronic components inside.

Electrons have internal integrity, but atomic fealty is another matter. For electrons, one proton is as good as the next, and though the attraction between the negatively and positively charged particles is reasonably strong, it is also, in some cases, a surprisingly easy connection to rupture. If you drag a comb through your dry hair, the comb will strip off millions of electrons from the outermost shells of the atoms of your coiffure. That comb is now bristling with extra electrons, and thus is a
negatively charged device. If you then hold the comb close to a few snips of paper, the pieces will hesitate for a moment, and then jump up and stick to the teeth of the comb. This act of levitation is evidence of electronic itinerancy. During that initial hesitation, many electrons on the surface of the paper clippings were repelled by the bolus of electrons presented to them on the negatively charged comb, and jumped aside, either to the edges of the paper, or off the scraps altogether. As a result, the surface atoms of the paper pieces suddenly found themselves in a state of electron deficit; and how better to resolve the crisis than by bounding toward the surfeit of negative particles beckoning from the comb overhead? Yes, the very same grooming tool that had thrust the paper into a predicament of positivity in the first place. It's like entrepreneurial capitalism. Forget about finding an extant consumer demand to be filled; go out there and dig a new need from scratch.

The Winter Hat Trick is a slightly different composite of repulsive reactions and rebound attractions. Why do some hairs stick up and out when you remove your wool cap? In being pulled off your head, the wool scrapes electrons from the outer layers of your hair, transforming each strand into an electron-depleted, positively charged object. Positive repels positive just as negative repels negative, so the strands try to get as far from one another as possible. At the same time, the positively charged hairs closer to your scalp and face become unusually attractive to the electrons in your skin, drawing the strands in close enough so the electrons can hopscotch between flesh and tress.

Importantly, charged atoms seek to fill their vacant shells or to shed their excess electrons and return to the bliss of Swiss neutrality; and so, too, of necessity, do the objects to which the disgruntled particles are hitched. Some materials are more apt than others to help alleviate one's imbalance of electric charges, a facility that usually requires a high tolerance for the most totable of motes, electrons. The metal of a doorknob is an excellent Ellis Island for electrons, for when metal atoms arrange themselves into molecules, the electrons in their outer shells are often loosely attached and free to roam about from one metal atom to another. The neighborly sharing of electrons tends to strengthen the bonds among atoms, lending metals their legendary toughness and historic utility to the military profession. A metal's steady electron churning also means there are always holes to be found, regions of positive charge toward which immigrant streams of electrons will be drawn. Metals, in short, are superb conductors of electron flow.

Dry air is an abysmal conductor of electrons. The reason why static cling and shocking handshakes are a particular problem in winter is
that indoor, heated air tends to be extremely dry. Thus, any charged particles you may have gathered on your person by walking across a carpeted room or removing an overcoat will likely remain on your person unless or until they have somewhere else to go. They'll tug remaining layers of clothes together, or they'll jump from you to the proffered hand of a newcomer—especially if that person is wearing a metal ring. In that single shocking moment, about a trillion electrons typically leap to their new host, bringing the donor back to the near neutrality that usually characterizes the human body.

On a muggy summer day, by contrast, water molecules in the air, which happen to be slightly positively charged on one end, tend to wash the odd electron from foot or fabric fairly quickly, returning you to a state of private tranquillity before you reach the door.

Not so for the world outside. The forked lightning of a fabulous summer thunderstorm offers the most spectacular example in nature of how a swelling buildup of charge disparities—between slip-sliding stacks of air masses, and between turbulent atmosphere above and stolid terrasphere below—is resolved by the abrupt conductance of negative and positive charges from cloud to ground and back up again, all courtesy of the bucket brigade of water droplets in the intervening sky. Lightning, in other words, is a doorknob spark on a very big scale. You can call it the vente grande version of static electricity, if you like. But you do so at your peril: The word "electricity," like "force," like "charge," means different things to different people, or to the same people in different moods and typefaces. And for some scientists and engineers, the constant, careless bandying of the term "electricity" makes them so ANGRY they could BLOW A FUSE. William J. Beaty, an electrical engineer who keeps an uppercase-heavy Web site devoted to explaining electromagnetism and the many myths and misconceptions surrounding it, complains that electricity is a "catchall word" applied helter-skelter to a welter of very different phenomena: electrical energy, electric current, electric charge, electric bills. For the sake of clarity, he argues, maybe we'd be better off if we all agreed that "ACTUALLY, 'ELECTRICITY' DOES NOT EXIST!"

Beaty is mostly right on two counts. First, the term is terribly vague, far more so than many other examples of crossover vocabulary. Whereas "force" and "charge" retain specific scientific meanings apart from their everyday sentiments, "electricity" does not. It survives among scientists mainly as a folksyism, the way herpetologists still talk to the public about "reptiles," even though they abandoned the term among themselves years ago as archaic and imprecise.

Second, as far as most people are concerned, the thing they are likeliest to call "electricity" barely seems to exist until it ACTUALLY does not EXIST! That is, when they are at their desk laboring frantically on their computer—too frantically to bother saving their work now and again—and suddenly, "Hey, what the Helmholtz happened to all the electricity??!!" For many of us, electricity is the invisible power we expect to purr forth bounteously from wall outlets or spring-loaded sets of alkaline batteries and light our lamps, warm our rooms, chill our food, clean our clothes, and run the little digital clocks embedded in at least seventy-four household devices, including the cat box. "Electricity" is what we try to guard our toddlers against by plugging up empty outlets with pronged pieces of plastic. If electricity isn't the right word, what is? Of greater relevance, what is this thing we've been misnaming all these years?

Here is where many researchers might question Beaty's uppercased rebuff of the word. As they see it, the topic of electricity and how it works offers a beautiful opportunity for conveying many fundamental principles of physics in a single jolt. Sure, "electricity" is used at the whimsical and often confused discretion of the speaker to describe a motley set of physical events, but if you take each of those effects in turn and reflect on where it fits into the ordinary extraordinary act of filling a room with a fistful of fabricated sun, you may surmount your conviction that you'll always be left in the dark.

I mentioned earlier that lightning is a kind of Wagnerian show of static electricity, although scientists like Beaty would howl, again rightly, that there is nothing "static" about it.

Nevertheless, people of varying degrees of electrical expertise have long distinguished between the flying sparks and thunderbolts that they can't control, and the electric currents that they generally can (unless they work for my utility company). An electric current, like static cling, arises from the peregrinations of charged particles, but in an electric current the flow of particles is continuous and targeted and expensive; static cling is episodic and unmanageable, a little offer-with-purchase that you can't quite refuse.

Comprehending and domesticating electricity for the betterment of the better-off segments of humankind took centuries of work by a procession of scientists whose names have been immortalized in an enviable format: as standard international units of measurement to be memorized by physics students on the eve of finals. There was Count Alessandro Volta, an Italian physicist who invented the chemical battery; James Prescott Joule, a British physicist who showed that heat is a form of energy; Charles Augustin de Coulomb, a French physicist and pioneer in the study of magnets and electrical repulsion; James Watt, a British engineer and inventor who designed and patented a very good steam engine but who never worked as secretary of the interior for the Reagan administration; André Marie Ampère, a French mathematician and physicist who discovered the relationship between magnetic force and electric current and whom we honor in the ampere, or amp, but not, curiously enough, in the verb "amplify," which derives from the Latin word for "enough"; Luigi Galvani, who discovered that electric currents prompt contractions in nerves and muscles, and whose name is behind the thesaurus-friendly "galvanize"; and Georg Simon Ohm, a German physicist who determined the relationship between voltage, current, and resistance in an electrical current, and who is rumored to have practiced yogic meditation when he thought nobody was around.

From Ohm we get ohm, the unit used to measure resistance in an electrical circuit or device. And though no one expects you to master the nuances of units or their namesakes (except to remember who the real watt's Watt was and what that Watt was not), the ohm is a good place to start talking about the electricity coursing through your cords, and what it says about all of us.

Resistance, in the broad, Newtonian sense, is a force, like friction, that works in the opposite direction of a moving body and tends to slow the body down. When it comes to an electric current, resistance is a measure of how much a material impedes the free flow of electrons from input to household device. The higher the resistance and the larger the ohm, the slower the flow. Dry air, as I've discussed, has extremely high resistance to electron passage. Metals tend to have low resistance and conduct electron flow readily. Some metals are better conductors than others because they have comparatively more gaps in their shells, which are open for electron trafficking. The shells of copper and tungsten, for example, are particularly well honeycombed, bearing vacancies in their penultimate as well as their outermost shells. So it is that copper is often spun into electrical wiring, while the comparatively rarer tungsten is reserved for the delicate filaments of a light bulb.