Back in the mid-1990s, an economist named William Nordhaus conducted a series of simple experiments. One day, for instance, he used a prehistoric technology: he lit a wood fire. Humans have been gathering and chopping and burning wood for tens of thousands of years. But Nordhaus also had a piece of high-tech equipment with him: a Minolta light meter. He burned twenty pounds of wood, kept track of how long it burned, and carefully recorded the dim, flickering firelight with his meter.
Another day, Nordhaus bought a Roman oil lamp—a genuine antique, he was assured—fitted it with a wick, and filled it with cold-pressed sesame oil. He lit the lamp and watched the oil burn down, again using the light meter to measure its soft, even glow. Nordhaus’s open wood fire had burned for just three hours when fueled with twenty pounds of wood. But a mere eggcup of oil burned all day, and more brightly and controllably.1
Why was Nordhaus doing this? He wanted to understand the economic significance of the lightbulb. But that was just part of a larger project. Nordhaus wanted, if you’ll forgive the play on words, to shed light on a difficult issue for economists: how to keep track of inflation, of the changing cost of goods and services.
To see why this is difficult, consider the price of traveling from, say, Lisbon in Portugal to Luanda in Angola. When first made by Portuguese explorers, the journey would have been an epic expedition, taking months via sailing ship. Later, by steam ship, it would have taken a few days. Then by plane, a few hours. An economic historian who wanted to measure inflation could start by tracking the price of passage on the steamer; but then, once an air route opened up, which price do you look at? Perhaps you simply switch to the airline ticket price once more people start flying than sailing. But flying is a different service—faster, more convenient. If more travelers are willing to pay twice as much to fly, it hardly makes sense for inflation statistics to record that the cost of the journey has suddenly doubled. How, then, do we measure changes in inflation when what we’re able to buy changes so radically over time?
This question isn’t simply a technical curiosity. How we answer it underpins our view of human progress over the centuries. The economist Timothy Taylor begins his introductory economics lectures by asking his students: Would you rather be making $70,000 a year now or $70,000 a year in 1900?
At first glance, that’s a no-brainer: $70,000 in the year 1900 is a much better deal. It’s worth about $2 million in today’s terms, after adjusting for inflation. A dollar would buy much more in 1900—enough steak to feed a family; enough bread for a fortnight. For a dollar you could hire a man to work for you all day. Your $70,000 salary would easily pay for a mansion, housemaids, and a butler.
Yet of course, in another way a dollar in 1900 buys much less than today. A dollar today will buy you an international phone call on a portable phone, or a day’s worth of broadband Internet access—or a course of antibiotics. In 1900, none of that was available, not to the richest men in the world.2
And all this may explain why the majority of Timothy Taylor’s students said they’d rather have a decent income now than a fortune a century ago. And it’s not just the high-tech stuff; they also knew their money would buy better central heating, better air-conditioning, and a much better car—even if they had no butler and fewer steak dinners. Inflation statistics tell us that $70,000 today is worth much less than $70,000 in 1900. But people who’ve experienced modern technology don’t see things that way.
Because we don’t have a good way to compare an iPod today with a gramophone a century ago, we don’t really have a good way to quantify how much all the inventions described in this book have really expanded the choices available to us. We probably never will.
But we can try—and Bill Nordhaus was trying as he fooled around with wood fires, antique oil lamps, and Minolta light meters. He wanted to unbundle the cost of a single quality that humans have cared deeply about since time immemorial, using the state-of-the-art technology of different ages: illumination. That’s measured in lumens, or lumen-hours. A candle, for example, gives off 13 lumens while it burns; a typical modern lightbulb is almost a hundred times as bright as that.
Imagine a hard week’s work gathering and chopping wood, ten hours a day for six days. Those sixty hours of work would produce 1,000 lumen-hours of light. That’s the equivalent of one modern lightbulb shining for just fifty-four minutes, although what you’d actually get is many more hours of dim, flickering light instead. Of course, light isn’t the only reason to burn fires: keeping warm, cooking food, and frightening off wild animals are also benefits. Still, if you wanted light and a wood fire was your only option, you might instead decide to wait until the sun comes up before doing what you wanted.
Thousands of years ago, better options came along—candles, from Egypt and Crete, and oil lamps from Babylon. The light they provided was steadier and more controllable, but still prohibitively expensive. In a diary entry of May 1743, the president of Harvard University, the Reverend Edward Holyoke, noted that his household had spent two days making seventy-eight pounds of tallow candles.3 Six months later he noted, stenographically, “Candles all gone.” And those were the summer months.
Nor were these the romantic, clean-burning paraffin wax candles we use today. The wealthiest people could afford beeswax, but most people—even the Harvard president—used tallow candles: stinking, smoking sticks of animal fat. Making such candles involved heating up the animal fat and patiently dipping and redipping wicks into the molten lard. It was pungent and time-consuming work. According to Nordhaus’s research, if you set aside one whole week a year to spend sixty hours devoted exclusively to making candles—or earning the money to buy them—that would enable you to burn a single candle for just two hours and twenty minutes every evening.
Things improved a little as the eighteenth and nineteenth centuries unfolded. Candles were made of spermaceti—the milk-hued oily gloop harvested from dead sperm whales. Ben Franklin loved the strong, white light they gave off, and the way they “may be held in the Hand, even in hot Weather, without softening; that their Drops do not make Grease Spots like those from common Candles; that they last much longer.” While the new candles were pleasing, they were pricey. George Washington calculated that burning a single spermaceti candle for five hours a night all year would cost him eight pounds—well over $1,000 in today’s money.4 A few decades later, gas lamps and kerosene lamps helped lower lighting costs; they also saved the sperm whale from extinction.5 But they, too, were basically an expensive hassle. They tipped, dripped, smelled, and set fire to things.
Then something changed. That something was the lightbulb.
By 1900, one of Thomas Edison’s carbon filament bulbs would provide you with ten days of bright, continuous illumination, a hundred times as bright as a candle, for the money you’d earn with our sixty-hour week of hard labor. By 1920, that same week of labor would pay for more than five months of continuous light from tungsten filament bulbs; by 1990, it was ten years. A couple of years after that, thanks to compact fluorescent bulbs, it was more than five times longer. The labor that had once produced the equivalent of fifty-four minutes of quality light now produced fifty-two years. And modern LED lights continue to get cheaper and cheaper. 6
Switch off a lightbulb for an hour and you’re saving illumination that would have cost our ancestors all week to create. It would have taken Benjamin Franklin’s contemporaries all afternoon. But someone in a rich industrial economy today could earn the money to buy that illumination in a fraction of a second. And of course lightbulbs are clean, safe, and controllable—no flicker or stink of pig fat or risk of fire. You could leave a child alone with one. 7
None of this has been reflected in traditional measures of inflation, which Nordhaus reckons has overstated the price of light by a factor of about 1,000 since 1800. Light seems to have become more expensive over time, but in fact it’s vastly cheaper. Timothy Taylor’s students instinctively feel that they could buy more of what they really want with $70,000 today than $70,000 in 1900. Bill Nordhaus’s investigations suggest that—when it comes to light, at least—they’re quite right.
That’s why I wanted to finish this book with the story of light—not the now familiar development of the incandescent bulb by Thomas Edison and Joseph Swan—but the story of how, over the centuries, humanity has developed innovation after innovation to utterly transform our access to light.
Those innovations have transformed our society into one where we can work whenever we want to work, and read or sew or play whenever we want, regardless of how dark the night has become.
No wonder that the lightbulb is still the visual cliché for “new idea”—literally, the icon for invention. Yet even iconic status underrates it. Nordhaus’s research suggests that however much we venerate it, perhaps we do not venerate it enough. The price of light alone tells that story: it has fallen by a factor of 500,000, far faster than official statistics suggest, and so fast that our intuition cannot really grasp the miracle of it all.
Man-made light was once a thing that was too precious to use. Now it is too cheap to notice. If ever there was a reminder that progress is possible—that amid all the troubles and challenges of modern life, we have much to be grateful for—then this is it.