There have been great improvements in the energy content and storage capacity of rechargeable batteries, driven by the need for external power supplies in consumer electronics. In a battery the electrodes should be able to readily give up or accept electrons. Examination of the periodic table of the elements shows that lithium, similar in electronic structure to sodium and hydrogen, has one electron in an unpaired energy level (shown in Figure 31c) that it easily surrenders, leaving it positively charged. Batteries that make use of these lithium ions, with a lithium-cobalt-oxide electrode,77 and with the other electrode typically composed of carbon, produce nearly twice the open-circuit voltage of alkaline batteries. These batteries are lighter than those that use heavy metals as the electrodes, and a lithium-ion battery weighing eight ounces can generate more than 100,000 Joules of energy, compared to 50,000 Joules from a comparable-weight nickel-metal-hydride battery or 33,000 Joules from a half-pound lead-acid battery. These lightweight, high-energy-capacity, rechargeable batteries are consequently ideal for cell phones, iPods, and laptop computers.
As all the electrochemical action in a battery takes place when the electrolyte chemical comes onto physical contact with the electrode surface, the greater the surface area of the electrode, the more available sites for chemical reactions to proceed. One way to increase the surface area is to make the electrodes larger, but this conflicts with the desire for smaller and lighter electronic devices. Another way to increase the capacity of these batteries is to structure the electrodes differently. Nanotextured electrodes are essentially wrinkly on the atomic scale, dramatically increasing the surface area available for electrochemical reactions without a corresponding rise in electrode mass. Recent research on electrodes composed of silicon nanoscale wires finds that they are able to store ten times more lithium ions without appreciable swelling than carbon electrodes can. While not quite in the league of Iron Man’s arc reactor, the ability to fabricate and manipulate materials on these nanometer-length scales is yielding batteries with properties worthy of the science fiction pulps.
This nanostructuring is also helping out with the laundry. Nanoscale filaments woven into textiles yield fabrics that are wrinkle resistant and repel staining. In addition to giving us whiter whites, nanotechnology is helping keep us healthy. A five-nanometer crystal contains only thirty-three hundred atoms, and such nanoparticles are excellent platforms for highly refined pharmaceutical delivery systems, able to provide, for example, chemotherapy drugs directly to cancerous cells while bypassing healthy cells.
We are only beginning to exploit the quantum mechanical advantages of nanostructured materials. There are ninety-two stable elements in the periodic table, and the specific details of the configuration of their electrons determines their physical, optical, and chemical properties. Crystalline silicon has a separation between its lowest filled states and first empty states of about one electron Volt, and if you want a semiconductor with a different energy gap, you must choose a different chemical element. Many technological applications would become possible, or would be improved, if the energy separation in crystalline silicon could be adjusted at will, without alloying with other chemicals that may have unintended deleterious effects on the material’s properties. Recent research indicates that we can indeed make silicon a “tunable” semiconductor, provided we make it tiny.
Whether the energy separation between the filled orchestra and the empty balcony in our auditorium analogy is one electron Volt (in the infrared portion of the spectrum), two electron Volts (red light), or ten electron Volts (ultraviolet light) is determined by the elements that make up the solid and the specific details of how each atom’s quantum mechanical wave function overlaps and interacts with its neighbors. In large crystals, big enough to see with the naked eye or with an optical microscope, the electrons leaving one side of the solid will suffer many scattering collisions, so any influence from the walls of the crystal on the electron’s wave function will have been washed out by the time the electron makes it to the other side. If the size of the solid is smaller than the extent of the electron’s de Broglie wavelengths, then the electrons in the small crystal in essence are able to detect the size of the solid in which they reside. The smaller the “box” confining these electrons, the smaller the uncertainty in their location and—thanks to Heisenberg—the larger the uncertainty in their momentum. Consequently, “nanocrystals” can have an energy band gap that is determined primarily by the size of the solid and that we can control, freeing designers of solid-state devices from the “tyranny of chemistry.”
The discoveries by a handful of physicists back in the 1920s and 1930s, explicating the rules that govern how atoms interact with light and each other, continue to shape and change the world we live in today and tomorrow.
AFTERWORD
Journey into Mystery
Every morning when I look out the window, I am reminded that we do not live in the world promised by science fiction pulp magazines, as I note in the skyline the absence of zeppelins. However, before I arise, the programmable solid-state timer on my coffee maker begins brewing my morning java. I thus literally do not get up in the morning without enjoying the benefits of a world informed by quantum mechanics.
As noted in the introduction, the pulps and science fiction comic books of fifty years ago certainly missed the mark (sometimes by a wide margin) in their prognostications of the technological innovations we would enjoy in the far-off future of the twenty-first century, a chronological milestone we have now reached. While their crystal balls may have been foggy, these errors concerning technology seem presciently accurate compared to how far off their sociological predictions were. For example, few science fiction writers in the 1950s anticipated how much public and private space would be designated smoke-free, and it was generally expected that in the year 2000, as in the year 1950, a universal truth would remain that all scientists smoke pipes.
Predicting the evolution of language is another challenge for those trying to create visions of life in the distant future. It is amusing to read old Buck Rogers newspaper strips from 1929 on, and see, amid the descriptions of rockets ships, disintegration rays, and levitation belts, that colloquial expressions of early-twentieth-century 2 America remain vibrant and comprehensible in the twenty-fifth century. Buck, who fell asleep in the 1920s and awoke five hundred years later, can be excused for his use of slang, but apparently everyone in the future speaks this way. When facing an overwhelming robot army, warriors of a besieged city lament, “They’ve got us licked!” while another counsels, “Let’s fade!” Gender equality appears set to move in reverse in the next five hundred years as well. Buck’s fiancée leads a scouting team into enemy territory on Mars and gets separated from the rest of the group (cell phones appear to be a lost technology in the future). At the base ship Buck complains, “This is what comes of trusting a Woman with a Man’s responsibility!” to which his lieutenant agrees, “They’re all alike! They can drive a man crazy!” Just another reason why life as envisioned in science fiction isn’t all it’s cracked up to be.
Some of the writers of science fiction of fifty or more years ago had great optimism regarding the coming future. Those who were not proposing dystopian futures of atomic warfare and unceasing hostilities between nations (and alien species) were confident that many if not all of the ills that plague humankind would be defeated in the coming years thanks to . . . Science!
Science would free the housewife of the 1950s from the drudgery of housework and food preparation. The May 1949 issue of Science Illustrated speculated that a “New Wiring Idea May Make the All-Electric House Come True.” The wiring idea involved dropping the operating voltage from 110 volts to 24 volts, using a small transformer.78 The article argues that the benefit of using the lower voltage is that it enables the safe operation of many consumer items, and by adopting an “all-electric” household, the five-dollar cost of the transformer becomes a reasonable expense when amortized over a dozen household helpers. A photo s
pread shows that “a young housewife [...] from a single bedside panel with remote control switches [...] can turn on the percolator in the kitchen, turn radios on and off, light up a flood lamp in the yard for a late-home-coming husband [...] control the electric dishwasher and toaster [and] control every light and electrical outlet in and around a house from one single point.” Little did the writer imagine that wireless technology, and semiconductor-based sensors whose operations could be preprogrammed, would remove the need for remote control switches on a bedside panel. No wonder social theorists worried about how the young housewife would fill the hours of the day in such a homemaker utopia.
Similarly, science has indeed revolutionized the workplace. Forget about inquiring, here in the twenty-first century, as to the location of our jet packs; what many want to know is: Where’s our four-hour workday? It was a general expectation that by the year 2000, people would have so much leisure time that the pressing challenge would be to find ways to keep the populace entertained and occupied. Instead, for too many of us, the de facto workday has lengthened, thanks to the modern electronics that flowered from the development of quantum mechanics; the ability to be in constant contact has evolved into the necessity to be always connected.
Youngsters fifty years ago may not have been reading Modern Mechanics or Popular Science, but they learned of the brighter future to be delivered by scientific research and innovation in the pages of their comic books. While nowadays a best-selling comic book may have sales of a few hundred thousand copies, in 1960 sales of Superman comics were over eight hundred thousand per issue, and studies found that a single issue was shared and read by up to ten other kids. Lifelong attitudes about better living through technology were fostered in the four-color pages of these ten-cent wonders.
The Man of Tomorrow, in particular, starred in many classic stories describing the world of tomorrow. Superman was so popular in the 1940s and 1950s that at times he appeared in up to seven comics published by National Allied Periodicals (the company that would become DC Comics). In addition to his own stories in Action and Superman, the Man of Steel could be found in Lois Lane, Superman’s Girlfriend; Jimmy Olsen, Superman’s Pal; World’s Finest (where he would team up every month with Batman and Robin); and Superboy and Adventure Comics (these latter two were filled with tales of Superman’s teenage years as Superboy).
In 1958’s Adventure Comics # 247, the Teen of Steel encounters three superpowered teenagers who, after playing some fairly harmless pranks on him, reveal to Superboy that they are from one thousand years in the future. These superteens have traveled back in time to offer Superboy membership in their club—the Legion of Superheroes. Apparently, one thousand years from now, a group of teenagers with a wide variety of powers and ability, from Earth and other planets, would band together to fight crime and evil throughout the United Planets. These young heroes were inspired by history tapes of the adventures of Superboy, and between their mastery of time travel and the Teen of Tomorrow’s ability to fly so fast that he could “break the time barrier,” Superboy would become a regular member of the Legion. Stories featuring the Legion would prove so popular with readers that they became a regular feature in Adventure and eventually squeezed Superboy out of the comic, aside from his appearances with the Legion in the thirtieth century.
According to these Legion tales, the promise of the space program and the race to the moon under way in the 1960s would culminate, in the thirtieth century, in a society ruled by and dedicated to science! In the world of the Legion of Superheroes, if you found yourself in trouble, you didn’t call the police; you sent for the science police!
While evil despots and warlike alien races would still bedevil humanity in the year 2958, the Legion of Superheroes tales featured a general sense of progress and hope that may have, in part, accounted for their popularity. A thousand years hence, intelligence and knowledge would be honored and rewarded. In Adventure # 321, when Lightning Lad, one of the Legion’s founding members, was sentenced to life in prison for “betraying” the Legion by “revealing” the secret of the Concentrator,79 his cell featured buttons that when pressed would provide the three basic necessities of life: food, water, and . . . books! The writers of the Legion of Superheroes stories promised that in the future, we would live in a golden age of science.
Similarly, over at Marvel Comics (though in the mid- to late 1950s the company was known as Atlas), scientists were also given pride of place in society. Stan Lee and Jack Kirby would not begin recounting the adventures of a quartet who took an ill-fated rocket trip “to the stars” and returned as the superpowered Fantastic Four until November 1961. Prior to this reintroduction of superheroes to the Marvel Comics universe in the 1960s, there were still plenty of menaces to be dealt with, as Tales to Astonish, Amazing Fantasy, Strange Tales, Journey into Mystery, and Tales of Suspense documented the near continuous onslaught of monstrous invaders from space, time, and other dimensions, all seeking global conquest. These would-be conquerors would regularly prove too much for local law enforcement and the military and often could be thwarted only by the lone efforts of a scientist!
And it’s a good thing scientists were on the case, as Earth had to contend with the likes of Pildorr, Rorgg, Sporr, Orggo, Gruto, Rommbu, Bombu, Moomba, Dragoom, and Kraggoom. These creatures were rarely less than twenty feet tall and when not generic bug-eyed monsters or monstrously oversized bugs, they were composed of stone, smoke, fire, water, electricity, wood, mud, or “oozing paint.” But none of these were as fearsome as Orgg, the Tax Collector from Outer Space!
Figure 51: Cover from Tales to Astonish # 13, describing the adventures of scientist Leslie Evans, who relates how “I Challenged Groot! The Monster from Planet X!” Such monstrous invaders from outer space threatened our planet several times a month in pre-superhero Marvel Comics.
Fairly typical was the November 1960 issue of Tales to Astonish # 13 (Figure 51), where we hear the firsthand testimonial “I Challenged Groot! The Monster from Planet X!” This is presumably the same Planet X that is home to Goom (and his son Googam); the Thing from Planet X; and Kurrgo, the Master of Planet X.80 Groot was a giant treelike creature who came to Earth intending to steal an entire village and bring it back to his home planet for study. Bullets did not harm Groot, and his wooden hide was “too tough to burn.” Groot’s ability to mentally command other trees to move and do his bidding quickly disabled the town’s defenses, and all seemed lost until the timely intervention of Leslie Evans, scientist. Working nonstop for several days, Evans developed the one weapon capable of immobilizing Groot—mutated termites. As shown in Figure 52, when the town’s sheriff is chagrined that he “never even thought of that,” a relieved villager points out, “That’s why Evans is a scientist—and you’re only a sheriff!” Meanwhile, Evans’s wife hugs her husband, declaring, “Oh, darling, forgive me! I’ve been such a fool! I’ll never complain about you again! Never!!” Personally, I can’t tell you how many times I’ve heard those very same words from my own wife!81
While the scientist as world-saving hero is a caricature, I hope that I have convinced you that the scientist as world-changing hero is a pretty apt description for the physicists who developed the field of quantum mechanics. In this, these investigators followed a trail blazed hundreds of years ago. For science has always changed the future. Technological innovations, from movable type to steam engines to wireless radio to laptop computers, have time and again profoundly altered interactions among people, communities, and nations.
Discoveries in one field of science enable breakthroughs in oth- ers. The elucidation of the structure of DNA resulted from the interpretation of X-ray scattering data. This technique of X-ray spectroscopy was developed, through the application of quantum mechanics, to facilitate the study of crystalline structures by solid-state physicists. The deciphering of the human genome is inconceivable without the use of high-speed computers and data storage that rely on the transistor, invented over fifty years ago by scientists at Bell
Labs. Using the tools developed by physicists in the last century, biologists in this century are poised to enact their own scientific revolution. Time will tell whether years from now another book will describe how “biologists changed the future.” But one thing is for sure—we will not be able to embrace and participate in that future without the discipline, curiosity, questioning, and reasoning that science requires. And if Orrgo the Unconquerable (Strange Tales # 90) ever returns, we’ll be ready!
Figure 52: The final panel from Tales to Astonish # 13, showing Evans’s reward for challenging Groot—the beginning of a “new, and better life” in which his wife “would never complain about [him] again!”
ACKNOWLEDGMENTS
Sometimes, as the saying goes, the very best plan is to be lucky. I have been fortunate to have excellent professors when learning quantum mechanics, statistical mechanics and solid-state physics in college and graduate school. The first course I had in quantum physics was taught by Prof. Timothy Boyer, whose classroom instruction provided an excellent foundation in the topic while his research in developing a non-quantum explanation for atomic behavior (involving classical electrodynamics coupled with a zero-point radiation field) demonstrated that there was more than one way to view and account for natural phenomena. I am also happy to thank Herman Cummins, Fred W. Smith, Kenneth Rubin, William Miller, Robert Alfano, Robert Sachs, Leo Kadanoff, Hellmut Fritzsche, Sidney Nagel, and Robert Street, who taught me, in the classroom and out, about this fascinating field of physics and its many applications. My students at the University of Minnesota have been the inspiration and motivation for many of the examples presented here.
The Amazing Story of Quantum Mechanics Page 27
