Electric Universe

by David Bodanis

  Bardeen was puzzled—“this is the opposite of what one might expect,” he wrote in his lab notebook—but engineers are good at following up what works. He and Brattain soon realized that instead of inserting an atom with extra electrons to carry a current, they had inserted atoms that had fewer electrons than the others around them. Their perfect lattice now had holes in it: gaps where those new atoms had an unfilled outer shell.

  Electrons from the other atoms started falling into those holes, but each time an electron fell forward, it left a fresh gap where it had been. Other electrons rushed forward to fill those gaps, which meant there were now free spaces even farther back in the rocky lattice. A bizarre empty hole was speeding backward, inside a solid crystal. It was a roundabout approach, but they had found a way to fling holes from one point in a solid material all the way through it to the other side. It wasn’t the controlled transfer of negative electrons they’d first expected, but it worked. (The actual experiments were with germanium, not silicon: both elements have four “gaps” in their outermost shell, but germanium is slightly easier to work with.)

  But Ohl…knew enough of quantum mechanics

  The extra insight that the quantum engineers used was that electrons were as much like waves as like particles. This means that the silicon or germanium crystals are suffused with electron waves, which can interfere with one another across the whole volume of the crystal. The insights are summarized in the band theory of solids. Rather than looking at the individual electrons around one atom, and asking whether they are tightly attached to the atom or available to be pulled elsewhere in the solid, one instead looks at the assemblage of all electrons in the solid and measures analogous properties for them as a whole.

  Watson Watt’s colleague Arnold Wilkins knew that the summated activities of great numbers of electrons would approximate to distinct conduction bands, and this is why Drude’s pre-quantum image of individual electrons being those conductors was valid enough for his calculations. It’s also why Bardeen and Brattain could talk about conducting holes, without however having to imagine that the hole is literally being passed from one atom to the next. The Al-Khalili or Polkinghorne texts in the reading guide for this chapter give good background.

  New chemical fabrication techniques

  Generations of engineering and computer professors have sighed over the way their students place a flowering “geranium” at the heart of transistor technology. To keep the spelling straight, it helps to remember the context in which the element was discovered. There was bitter hatred between France and Germany after the Franco-Prussian War of 1870–71, so when the French chemist de Boisbaudran discovered in 1875 a new element that Mendeleyeev had predicted, he named it gallium, after the Latin name for France. When the German researcher Clemens Alexander Winkler, a decade later, discovered yet another element Mendeleyeev had predicted—one that occupied a gap directly beneath silicon in Mendelyeev’s table, and so had many properties in common with silicon—there was no question but that he would name it germanium, after his newly triumphant country.

  The rock itself doesn’t have to move, swiveling…like a big metal switch

  What’s being described is simply the idea behind a standard three-layer transistor. The outer layers are configured (though having an excess of electrons) to easily carry negative charge. The middle layer blocks them. But since that middle layer is a semi-conductor, its nature easily changes. Even a very slight increase in a current that’s fed in will make it transform, so that the charges from the outer layers can get across.

  Note the similarity to Edison’s carbon-button microphone. In a modern hearing aid a battery is constantly attempting to push a steady current across the middle layer of a transistor, but only the weak voice signal fed in from outside will make that middle layer transform to let the current across. The stronger the voice, the stronger the current from the battery that gets through.

  If the effect was exactly one for one, the transistor wouldn’t be much help, but the great power of transistors comes from the fact that the middle layer is so precarious that even a slight change in the input—the slightest shift in the voice to be heard—can make it transform considerably. There will be an enormous “power gain,” and it was measuring a similar power gain in November 1947 that made Brattain and Bardeen realize they were on the right track.

  Hopper liked explaining in later years

  She also liked describing the day in 1947 when she found a moth shorting the circuitry in the computer she was working on at Harvard. “First actual case of a bug being found,” she wrote next to its carefully preserved carcass, which she taped in her logbook. The term seems to have been used as a generic explanation for mysterious faults in electric circuits from time to time as far back as Edison, but with Hopper’s central position at Harvard, plus the taped-up evidence, the label “bug” for a computer fault now took off.

  An electronics magazine came to take a photo

  It’s the photo used in innumerable textbooks and histories, taken for the September 1948 cover of Electronics, but it has as much accuracy as the ones emanating from the Kremlin in its Politburo days. Walter Brattain can be seen directly behind Shockley, who’s peering aimlessly through Brattain’s own microscope. When Brattain was young, he’d once spent almost a full year in the mountains, largely on horseback, guarding a cattle herd with a rifle on his lap. In the photo one can see his tensed hands, tilted slightly forward, in a path that, if continued, would let him wring Shockley’s neck. Forty-five years later Bardeen was interviewed about that day. “Boy, Walter sure hates this picture,” the mild Bardeen explained. See Michael Riordan’s and Lillian Moddeson’s Crystal Fire: The Invention of the Transistor and the Birth of the Information Age (New York: W. W. Norton, 1997), p. 167.

  Bardeen left…no transistors were mass-produced in time

  Bardeen and Brattain were surprisingly close to making the great breakthrough to the MOS (metal-oxide-silicon) transistor, which became the heart of Intel’s chips in later decades. Although their final 1947 experiments had used germanium, from which the key oxide layer needed for MOS transistors washed off, if Shockley had let them continue, they would probably soon have turned back to silicon—which they’d been following in great detail—and on silicon the crucial oxide layer would have remained.

  The incoming wave, feeble as it is

  Battery power is at a premium aboard satellites, and the antenna on a GPS satellite glows with the energy of only five small lightbulbs. By the time the signal reaches Earth’s surface, having had to push through the thick atmosphere and having dispersed over thousands of miles, our receivers have less than one-billionth of a watt of power to work with. The transistors in our GPS receivers are sensitive indeed: an ordinary toaster needs about one trillion times more power than that to warm a single piece of bread.

  Many people had seen demonstrations…The twenty-year-old Mary Shelley

  She hadn’t seen the most famous demonstration herself, for she’d only been five years old in 1802, when Galvani’s nephew, Giovanni Aldini, had come to London and obtained permission to set up his equipment around an understandably worried young convict, Thomas Forster, who was very soon to become a nice fresh corpse.

  Forster was lifted up, hanged, then his body brought down; Aldini poured paste into Forster’s nostrils and mouth, and then connected a battery. For a horrible long moment Forster’s body seemed to live again, and “convulsions appeared to be much increased,” appearing in his “head, face, and neck, as far as the deltoid.”

  The gruesome effect was much discussed, not least by Percy Shelley—Mary’s future husband—who as a schoolboy often used voltaic piles to charge up his body till his hair stood on end. See Esther Schor, ed., The Cambridge Companion to Mary Shelley (Cambridge, England: Cambridge University Press, 2003).

  Any atom that has a different number of electrons…is called an ion

  When we talk about the “pH” of a solution, that’s simply shorthand for
counting the electrically powerful ions inside it. In a glass of water there’s one bare hydrogen ion on the loose for about every 10,000,000 ordinary molecules, which is why water’s pH is said to be seven—the number of zeros in 10,000,000. The hydrochloric acid in our stomach has one hydrogen ion for about every hundred water molecules, and so had a pH of about two. That greater density of electrically charged ions attacks the bacteria on the food we swallow, and it sizzles into the cell membranes of the food itself.

  Cosmetics companies often advertise their products as being pH balanced, which means they have a pH of seven. The labels are less forthcoming in explaining how this expensive feat is achieved. Quite often, the customer is simply buying a product mixed with a great deal of liquid that has those hydrogen ions diluted to one in 10,000,000. In other words, the customer is spending most of his money on water.

  When we have a thought, and a nerve cell in our brain begins to fire

  Since the simple movement of electrons inside a wire sends out radio waves, might not the natural shaking of electrons inside the human brain send out similar invisible waves? Almost as soon as Hertz’s experiments became known, a number of researchers, led by the radio pioneer Oliver Lodge, thought that this could be the scientific basis for extrasensory perception (ESP). In the 1920s, the spread of ordinary radios—little boxes that really could detect invisible messages from afar—bolstered the general public’s belief in phenomena like ESP.

  It turns out that although the brain does in fact generate low-power radio waves, they’re too weak to be clearly detected at any significant distance. The explanation has to do with the trade-off between the length of a wave and the number of those waves it takes to cross a given distance. Hodgkin and Huxley confirmed that the nerve cells in our brain fire at the fairly slow rate of a few thousand times a second, so as with the comb calculation on page 246, this means the front of each wave has a head start of about one-thousandth of a second on the back of the same wave.

  A bullet can’t go far in one-thousandth of a second, but it takes only one full second for electromagnetic waves to travel 186,000 miles, which means they’ll travel 186 miles in one-thousandth of a second. That’s what emerges from our brains, and at first this fact—that invisible waves with a distance from peak to peak of 186 miles are constantly pouring from our heads—seems to be solid evidence for extrasensory phenomena. (The waves can be a little longer or a little shorter, depending on the actual rate of neuron firing.)

  But it’s not quite as good as it sounds, for 186 miles is a huge wave. Cell phones produce electromagnetic waves with a length of only a few inches; even AM radio produces waves with a length of only a few hundred yards. For a wave to be easily detected, it needs to be produced from a source that’s relatively large compared to the wave. But the human head is tiny compared to 186 miles. That means the wave is generated very inefficiently, and so the field it produces is far too weak for humans to detect unaided; the fact that the signals interfere with one another makes it even feebler.

  Sigmund Freud…plant extract called cocaine

  Freud almost got credit for discovering cocaine’s anesthetic properties, but he got distracted by other work and didn’t take the time to elaborate his findings. Instead of blaming himself for this professional failure, however, he wrote: “looking back…it was my fiancée’s fault if I did not become famous in those early years.” But he didn’t hold a grudge, and more than once sent her small vials of cocaine to sample; he even began taking it regularly, on and off for almost a decade: it helped him relax, and—as he promised her before another visit—it also turned him into “a big wild man with cocaine in his body.” See Peter Gay, Freud: A Life for Our Time (London: J. J. Dent & Sons, 1988), 42–45.

  The mechanism was exactly the same as in humans

  Although humans need sensitive lab equipment to detect the electric currents in live nerves, many animals don’t. The seemingly cuddly duck-billed platypus, for example, hunts in muddy river bottoms at night. The crayfish or shrimp that are its prey try to hide in the mud, but their nerves—just like ours—are constantly pouring charged sodium ions back and forth. Those moving charges send electromagnetic fields undulating outward. The platypus’s beak is loaded with cells that can detect those fields; with a quick bite, or an accurate slash from its venom-filled ankle spurs, the crayfish is gone.

  Hammerhead sharks are even better at this, for the vast space in the “hammer” swelling on their heads means they carry even more cells that can detect electric fields. The shark’s prey might be cowering unseen around a turn, or burrowed deep into layers of sand. But that prey’s heart is going to be beating, and the quivering pulses of its heart muscle are controlled—again, like ours—by microscopic pumps in the walls of its nerve fibers, pouring charged sodium and other ions back and forth. The invisible electromagnetic fields stretching outward begins to pulse. The hammerhead detects that, even in total darkness, and turns closer, jaws widening, to…investigate.

  The future that insights into neurotransmitters will create still remains to be seen

  What happens to personal responsibility when we’ve found a biological source for all our actions? “If we can find explanations for the evil people do, then are we not replacing moral evil, which is freely undertaken, with natural evil, which is beyond our control? To the volcano and the virus might we now add the dysfunctional amygdala and the abnormal orbitofrontal cortex?” (Sean Spence, University of Sheffield, in New Scientist, March 20, 2004.)

  As many…as there are stars in the Milky Way galaxy

  Kant wrote that “Two things fill the mind with ever new and increasing wonder and awe—the starry heavens above me and the moral law within me.”

  He was more right than he could have known. The numerical similarity is just chance, but quantum fluctuations in the very early universe seem to have been responsible for the distribution of galactic clusters that we find in the starry heavens above; those same quantum fluctuations control neuronal processing of each human brain contemplating the moral law within.

  For a one-sided yet entertaining discussion of free will and quantum mechanics, see Roger Penrose, The Emperor’s New Clothes: Concerning Computers, Minds, and the Laws of Physics (Oxford: Oxford University Press, 1989).

  GUIDE TO FURTHER READING

  EARLY ELECTRICITY

  The classic account of electricity’s early years is John Heilbron’s Electricity in the Seventeenth and Eighteenth Centuries: A Study of Early Modern Physics (Berkeley: University of California Press, 1979). This has such vignettes as the Englishman Robbert Symmer’s baffled report, in November 1758, that “I had for some time observed, that upon pulling off my stockings in an evening they frequently made a crackling or snapping noise; and in the dark I could perceive them to emit sparks of Wre”; Thomas Hankins’s Science and the Enlightenment (Cambridge: Cambridge University Press, 1985) homes in on the way eighteenth-century investigators tried exploring the observations of Symmer and others, through such expedients as leading the static crackling along long cotton strings, creating something like simple telegraphs; he leads up to the seminal experiments of Galvani and Volta, a bickering, sulk-ridden relationship described with much delight in The Ambiguous Frog: The Galvani-Volta Controversy on Animal Electricity, by Marcello Pera (Princeton, NJ: Princeton University Press, 1992).

  Benjamin Franklin’s contributions were slighted in this book, but Walter Isaacson’s Benjamin Franklin: An American Life (New York: Simon & Schuster, 2003) provides an eloquent introduction, as well as evaluating whether the famous kite experiment ever happened (he votes yes). I. Bernard Cohen’s writings on Franklin began with Franklin and Newton (Philadelphia: American Philosophical Society, 1956) and were still going strong forty years later with his Science and the Founding Fathers: Science in the Political Thought of Jefferson, Franklin, Adams and Madison (New York: W. W. Norton, 1995), which shows a profundity of analytic intelligence among America’s political leaders not quite matched by more recent
occupants of Thomas Jefferson’s office. Patricia Fara’s long series of writings on early magnetism are well represented in “ ‘A treasure of hidden vertues’: the attraction of magnetic marketing,” in The British Journal for the History of Science 28 (1995): 5–35.

  HENRY AND MORSE

  Joseph Henry was an easygoing, matter-of-fact man, who found an easygoing, matter-of-fact biographer in Thomas Coulson. His Joseph Henry: His Life and Work (Princeton, NJ: Princeton University Press, 1950) captures Henry’s life, down even to the way that Henry’s low salary meant he had to economize on purchases of zinc—a powerful inspiration for devising electromagnets that could work with batteries powered by only the slightest slivers of that expensive metal. I’d also recommend a skim through Nathan Reingold’s edited collection, Science in Nineteenth-Century America: A Documentary History (London: Macmillan, 1966). This has extensive extracts from Henry’s letters, from the difficult days teaching (“my duties in the Academy are not well suited to my taste. I am engaged…in the drudgery of instructing a class of sixty boys”) to his growing showmanship in using the small battery to lift a 750-pound weight.

  H. J. Habakkuk’s American and British Technology in the Nineteenth Century: The Search for Labour-Saving Inventions (Cambridge, England: Cambridge University Press, 1967) is a specialist economic history showing why labor scarcity alone does not lead to innovation. A more hands-on view comes from one young Frenchman who actually visited Albany in 1831 (when Henry was still there) and wrote up his thoughts to a somewhat wider acclaim: Alexis de Tocqueville’s Democracy in America (many editions) is a masterpiece; see particularly part I of volume 2, on the interrelations among innovation, careers, and daily life in Henry’s society.

  The title of The American Leonardo: A Life of Samuel F. B. Morse, by Carleton Mabee (New York: Knopf, 1944) suggests it’s going to be just another book of praise, but it was one of the first serious accounts to debunk Morse—his section showing Morse painfully failing to grasp the idea behind what became labeled the “Morse code” is a nice touch. Pauli Staiti’s Samuel F. B. Morse (Cambridge and New York: Cambridge University Press, 1989) puts Morse’s work in the context of his artistic efforts, showing how Morse’s failure to evangelize America through his art naturally led to his attempting to evangelize through telegraphy. Kenneth Silverman’s Lightning Man: The Accursed Life of Samuel F. B. Morse (New York: Knopf, 2003) is a good recent account; the hagiography by Morse’s son (Samuel F. B. Morse, His Letters and Journals, edited and supplemented by Edward Lind Morse [Boston and New York: Houghton Mifflin, 1914]) shows a touching bewilderment as the son tries to explain his father’s innocence over the fire that destroyed key court documents, the payoff to Congressman Smith (“[my father] was unfortunately not a keen judge of men”), and all the other misadventures in Morse’s long life. Richard Hofstadter’s classic The Paranoid Style in American Politics (London: Cape, 1966) situates Morse’s mania in rich company.