When I was a 12-year-old living in Chicago, my school class went on a field trip to a museum, and at one point our teacher started talking about how great Albert Einstein was. We were all impressed. Then I remember Melissa Gorman, who was quite attentive, asking our teacher what exactly it was that Einstein invented.
The teacher had no idea.
I was shocked, and not just because I still believed that teachers knew everything. I found it hard to imagine that someone could be so famous without having invented something, or pitched in a World Series, or in some other way actually done something concrete. I knew that Einstein was smart: Several parents in my neighborhood had a picture of him taped up on their refrigerator. A lot of Jewish families in the 1950s and 1960s had photos of Einstein hanging in the house. In those photos it was always clear that Einstein was thinking deeply and perhaps even that he was sad. I wondered, What exactly had he done?
When I was an undergraduate at the University of Chicago, I learned more about Einstein’s great theories and read some of his comments about the impersonality of what he’d achieved—his feeling that although he had been granted the opportunity to see something of how our universe was built, his own role would in time be forgotten. As a teenager, I found Einstein’s acknowledgment of his own mortality hard to accept. But years later when I was teaching at Oxford, I had an epiphany while watching the rowing teams out on the river early one morning. I realized that as one generation of undergraduates took over from the next, they were beginning to blur in my mind. I was startled, and at the same moment pleased, by the thought that my contributions to their education would also blur in their minds, just as on a far higher level we have begun to take for granted Einstein’s role in expanding our understanding of the universe.
Decades after that childhood museum field trip roused my curiosity about Einstein and his work, I was surprised to discover that he did invent something—actually quite a few things, including a refrigerator with no moving parts. Over the years I had also come to recognize that Einstein’s theories are so far-reaching that he literally helped invent our modern world.
Spend the better part of a day pondering the technological marvels that are now an integral part of ordinary life and you’ll encounter Einstein wherever you turn.
Oh, What a Beautiful Morning
As you head to the kitchen for your coffee, pause for a moment and contemplate the smoke detector operating silently overhead, a small quantity of the radioactive substance americium-241 pouring out energy to create a thin beam of charged particles. Any smoke from a fire would interfere with that beam, setting off an alarm. The nucleus of the americium atom is unstable. When it breaks apart, mass seems to disappear, for the fragments weigh less than the original nucleus. But it’s not truly lost, and we know that because of Einstein.
In one of the seminal papers Einstein published in 1905, he destroyed a central belief of 19th-century science: the notion that there was a domain of energy and a domain of mass, and ne’er the twain shall meet. Instead, he showed that any mass whatsoever could be considered a very compressed form of energy. To find out exactly how much energy can pour out from a given amount of mass, one measures the disappearing mass and simply multiplies it by c squared, the speed of light multiplied by itself—a truly enormous number.
Chemists and engineers use calculations based on Einstein’s famous
E = mc^2
equation to design even our humble smoke detectors. But it goes further. Medical specialists use similar calculations when giving cancer patients radiation treatments or when they need to estimate how much damage X-rays might produce in DNA. And, of course, when Manhattan Project physicists were computing blast powers for the atomic bombs to be dropped over Japan, they used Einstein’s
E = mc^2
Even beyond medical and military technology, our world is suffused by Einstein’s insights into the relationship between mass and energy. Look up at the sky from your kitchen window and the sun you see is actually a great pumping station, converting millions of tons of mass into billowing energy at a rate prodigious enough to light up our planet. Go for a morning jog over hilly terrain and the very landscape is likely to be the result of tectonic plate movements, powered deep under our feet in great part by radioactive decays like that of the humble americium writ large.
On the Road Again
The Global Positioning System satellites that guide us—on the highways we drive along to work as well as in the passenger jets overhead and on boats at sea—depend on more of Einstein’s insights. In another of his 1905 papers, Einstein showed that the conventional definition of time “is indeed sufficient if a time is to be defined exclusively for the place at which [a] watch is located, but the definition is no longer satisfactory when series of events occurring at different locations have to be linked temporally.” GPS satellites are equipped with precision atomic clocks, but the GPS signals beamed down to us would veer well over a mile out of kilter each day unless they were adjusted for the relative difference in time measured by atomic clocks on the ground.
The roads under our wheels also depend on Einstein’s work. Einstein had failed to get an academic job after he graduated from his technical university in Switzerland, not, as myth would have it, because he was a poor student—he actually got good grades—but because he couldn’t resist telling his professors what he thought about their teaching dry, out-of-date facts from the books, rather than trying to explore the implications of the latest research. This is how he got stuck in his patent office job while he wrote his Ph.D. thesis.
The thesis introduced ingenious ways of measuring molecules in diverse solutions, and that became fundamental to the chemistry of colloids. When cement engineers fabricate the roads we drive on, they’re using Einstein’s results.
Taking Care of Business
Look inside that computer sitting on your desktop at work and with the right
equipment you’ll be able to detect the electrons shooting out of the cathode in the picture tube. They’re accelerating so rapidly that they seem to gain mass during their flight before they hit the glass screen in front—exactly in accord with Einstein’s predictions of special relativity. The engineers who build the computer monitors have to correct for that relativistic effect. Otherwise, the magnets controlling the electrons’ flight would produce a blur rather than a crisp image on the monitor.
The fiber-optic cables that carry your e-mail or Google searches also depend on Einstein’s work. Late in 1916, despite the exhaustion of just having completed his grand papers on general relativity, Einstein told his close friend Michele Besso that “a splendid light has dawned on me about the absorption and emission of radiation.” Einstein showed how electrons in particular elevated states could be stimulated by incoming photons to release photons identical to the incoming ones—the key insight that physicists Charles Townes and Arthur Schawlow built on 40 years later when they sketched out how cascades of such releases could very quickly accumulate to produce what we now know as a laser. The optical flashes that carry our messages are generated by such lasers, whose core workings Einstein envisioned in those distant World War I years; the bar codes on every object we purchase also depend on Einstein’s lasers being able to accurately read those coded spacings.
Watching the Sun Go Down
All through a sunny day, through the diing evening hours, photovoltaic cells on the roof of an energy-efficient house with supplementary solar power convert the energy of sunlight into electricity. This depends on an effect first properly analyzed in another of Einstein’s 1905 papers, one that he thought of as even more revolutionary than his relativity work. This was the paper in which he proposed that light is concentrated in traveling energy packets, which later came to be called photons. Some of those photons carry enough energy to overcome the “stickiness” holding electrons to a metal.
This phenomenon, known as the photo-electric effect, is central to all our technologies that involve making electrons scoot loose from metals or other substances. For example, turn on your digital camera to snap a picture of the setting sun and photons flying in through the lens make electrons move out from semiconductors located where the film would be in conventional cameras.
Later in the evening, as you get ready for bed, you’ll find Einstein lurking in the medicine cabinet. Many of the pharmaceuticals we take, from statins to Viagra, were fabricated using techniques that draw on Einstein’s 1905 paper on Brownian motion. With his great desire to link hitherto separated realms, Einstein used botanist Robert Brown’s old observation that small particles randomly jostle in a fluid to create statistical techniques for linking micro quantities, such as molecular mass, with macro quantities, such as overall temperature. Those techniques are now second nature to chemists at pharmaceutical firms worldwide.
It’s fading now, this knowledge of what Einstein bequeathed us, and in a few more generations I suppose all that will survive will be a vague awareness that he did something with nuclear weapons. But I don’t think he would have minded—and that’s what I finally understood at Oxford. The highest form of charity is not to insist others know what you’re giving; rather, it’s to donate freely and let those who receive your giving move on. In science we get to see what existed before we were born, and we get to envision what will exist long after our death. There’s no need for arrogance here, none of the desperate hunt for eternity that many of us crave when we are young. Instead, there’s something else—what for me has been the greatest gift my study of Einstein has produced.