The Lightbulb

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Bettmann / Corbis

Thomas Edison exhibits a replica of his first successful incandescent lamp, which gave 16 candlepower of illumination. Today there is a 50,000-watt, 150,000-candlepower lamp

Let there be light! Oct. 22 marks the 130th anniversary of Thomas Edison's first test of the incandescent lightbulb, the initial spark of a revolution that would electrify the world.

Though Edison is usually cited as the father of the lightbulb, it's more accurate to give Edison credit as the creator of the first commercially viable lightbulb. As early as 1820, inventors were homing in on the principles that would lead to the first electric illumination. An English inventor, Joseph Swan, took their early work and developed the basis of the modern electric lightbulb in 1879 — a thin paper or metal filament surrounded by a glass-enclosed vacuum. When electricity runs through the filament, the bulb glows. Edison refined the design, trying filaments made out of platinum and cotton before eventually settling on carbonized bamboo, capable of burning for more than 1,200 hours. With Edison's design — and the settlement of a lawsuit with Swan that resulted in the two inventors' joining forces in 1883 — electric lighting became viable for the first time.

The development of the lightbulb sparked the spread of electric power in the U.S. Edison was behind the creation of the first commercial power plant in 1882; New York City had electricity 10 years later. By the late 1930s, the Rural Electrification Administration, one of President Franklin D. Roosevelt's New Deal programs, had delivered electric lighting to nearly every corner of the country. Development on the bulb didn't stop either: researchers have modified Edison and Swan's design further, refining the filament by using tungsten and filling the vacuum with gas, both of which increase the life span of a bulb. Still, even modern bulbs are inefficient — less than 6% of the energy used by a bulb goes into producing light. The rest is given off as heat.

That fact explains the effort under way to drive consumers toward a better bulb: compact fluorescent lamps (CFLs), which last 10 times as longer as their incandescent counterparts while consuming less than one-third the electricity. The European Union began phasing out incandescents on Sept. 1, banning stores from buying new stock. At up to $10 each, CFLs are more expensive, but experts say they pay for themselves in energy savings within just a few months. The E.U. is even touting the switch as an economic stimulus; experts estimate that the swap to CFLs will save customers €5 billion annually.

But the decision to regulate which bulbs consumers can use has drawn some criticism. CFLs emit light in a different spectrum than that of their incandescent counterparts. Light produced by CFLs is "cooler" — tinged a light blue or green — than the yellowish glow of an incandescent, and many people complain that the effect is less aesthetically pleasing. CFLs raise concerns because there is a danger of mercury exposure if the bulbs break, which makes disposal tricky. And some people allege that long-term use of fluorescent light causes health problems, though experts are largely skeptical of the claim.

These concerns, however, take a backseat to those over lightbulbs' environmental impact. Replacing a single incandescent bulb with a CFL in every U.S. household would be the environmental equivalent of taking 7.5 million cars off the road, according to the U.S Department of Energy. The U.S. plans to follow Europe's lead and outlaw incandescents in 2012. Still, at least one light will stay on: the Centennial Light in Livermore, Calif., has been shining continuously in the same firehouse since 1901, making it the longest-burning bulb on the planet.