The light bulb that has brightened the fire-department garage in Livermore, California, for the past hundred and fifteen years will not burn out. Instead, it will “expire.” When it does, it certainly won’t be thrown out. It will be “laid to rest.”

“You have to use the correct terminology,” Tom Bramell, a retired deputy fire chief who has become the Livermore light’s leading historian, told me. The bulb has been on almost continuously since 1901, he said; in 2015, it surpassed a million hours in service, making it, according to Guinness World Records, the longest-burning in the world.

Bramell so cuts the figure of a firefighter that he has smoke-colored eyes and hair, and a permanent hack from smoke inhalation (“I do a bag of cough drops a day”). His circumlocution around the bulb’s eventual, inevitable end reflects the reverence in which it is held by Livermoreans and its more far-flung fans, who keep vigil over the light online. The bulb, he said, has outlived three webcams so far. It was manufactured sometime around 1900 by Shelby Electric, of Ohio, using a design by the French-American inventor Adolphe Chaillet. Its essential makeup is something of a mystery, because it is hard to dissect a light that is always on. (Shelby bulbs of the same vintage have been studied, but the company was experimenting with a variety of designs at the time.) What’s known for sure about the Livermore bulb is that it has a carbon filament of about the same human-hair thickness as the ones, typically made of tungsten, that are found in modern bulbs. It was made to be a sixty-watt bulb, though it currently illuminates the Fire Department Station 6 garage with only about the brightness of a nightlight.

More intriguingly, the light bulb is of the incandescent variety—the same type that many consumers now revile for its short life span. Had you plugged in a typical drugstore incandescent on January 1st of this year and left it on full time, it would likely have died by around February 12th. These bulbs commonly burn for about a thousand hours, or approximately half as long as the average bulb did in the early nineteen-twenties. “We don’t build things today to last,” Bramell said—speaking for, I would guess, almost all of us.

Building bulbs to last poses a vexing problem: no one seems to have a sound business model for such a product. Paradoxically, this is the very problem that the short life span of modern incandescents was meant to solve. Photograph by David Paul Morris / Bloomberg / Getty

That truism has lately come into question, however, thanks to the widespread adoption of durable, light-emitting-diode light bulbs. L.E.D.s use semiconductor technology to achieve long life spans—bulbs that promise a fifty-thousand-hour design life are not uncommon. Current penetration in the consumer-lamps market (as the bulb business is known) is seven per cent worldwide, and is expected by lighting analysts to reach fifty per cent by around 2022. In the first quarter of 2016, according to the National Electrical Manufacturers Association, L.E.D.-lamp shipments in the U.S. were up three hundred and seventy-five per cent over last year, taking more than a quarter of the market for the first time in history.

This would seem to be a good thing, but building bulbs to last turns out to pose a vexing problem: no one seems to have a sound business model for such a product. And, paradoxically, this is the very problem that the short life span of modern incandescents was meant to solve.

The thousand-hour life span of the modern incandescent dates to 1924, when representatives from the world’s largest lighting companies—including such familiar names as Philips, Osram, and General Electric (which took over Shelby Electric circa 1912)—met in Switzerland to form Phoebus, arguably the first cartel with global reach. The bulbs’ life spans had by then increased to the point that they were causing what one senior member of the group described as a “mire” in sales turnover. And so, one of its priorities was to depress lamp life, to a thousand-hour standard. The effort is today considered one of the earliest examples of planned obsolescence at an industrial scale.

When the new bulbs started coming out, Phoebus members rationalized the shorter design life as an effort to establish a quality standard of brighter and more energy-efficient bulbs. But Markus Krajewski, a media-studies professor at the University of Basel, in Switzerland, who has researched Phoebus’s records, told me that the only significant technical innovation in the new bulbs was the precipitous drop in operating life. “It was the explicit aim of the cartel to reduce the life span of the lamps in order to increase sales,” he said. “Economics, not physics.”

Phoebus is easily cast as a conspiracy of big-business evildoers. It even makes an appearance as such in Thomas Pynchon’s weird-lit classic “Gravity’s Rainbow”: the shadowy organization sends an agent in asbestos gloves and seven-inch heels to seize diehard bulbs as they approach their thousandth hour of service. (“Phoebus discovered—one of the great undiscovered discoveries of our time—that consumers need to feel a sense of sin,” Pynchon writes.) In its day, however, the shift to planned obsolescence was in keeping with the views of a growing body of economists and businesspeople who felt that, unless you dealt in coffins, it was bad business and unsound economics to sell a person any product only once. By the late nineteen-twenties, the repetitive-sales model had become so popular that Paul Mazur, a partner at Lehman Brothers, declared obsolescence the “new god” of the American business élite.

Giles Slade, in his book “Made to Break,” traces the term “planned obsolescence” to a 1932 pamphlet, circulated in New York, titled “Ending the Depression through Planned Obsolescence.” The term gained currency in 1936, through a similarly themed essay in Printer’s Ink, “Outmoded Durability: If Merchandise Does Not Wear Out Faster, Factories Will Be Idle, People Unemployed.”

This Depression-era argument, which one marketing writer of the era summed up as a “sound and genuine philosophy in free spending and wasting,” became the foundation of the modern consumer economy, so much so that we heard it again during the Great Recession, in 2007, when prominent political leaders suggested that shopping presented a solution to the crisis. The prospect of repetitive consumption is now built into almost everything we buy, and obsolescence has become, as Slade puts it, “a touchstone of the American consciousness.”

With the advent of L.E.D. bulbs, we now have perhaps the first mass-consumer product of the twenty-first century to challenge planned obsolescence. After a long technological incubation, L.E.D.s surpassed the energy efficiency of comparably bright incandescent lighting in the nineteen-nineties. Today, hardware-store-variety L.E.D. bulbs are commonly advertised at a twenty-five-thousand-hour design life, which is also the benchmark for federal Energy Star labelling; after that length of time they will have lost more than thirty per cent of their brightness. Plug one in on January 1st and it will wane by about May 15th the following year. Under more ordinary usage—each of the sixty-seven bulbs in a typical American household is turned on for an average of only 1.6 hours daily—it would, in theory, at least, stay bright for more than forty-two years. Incentives for the purchase of L.E.D.s are now offered in forty-eight states, and the U.S. Department of Energy considers the widespread adoption of the technology to offer the greatest potential impact on energy conservation in the country.