The Mysterious Case of the 113-Year-Old Light Bulb

In the United States, the average incandescent light bulb (that is, a bulb heated with a wire filament) has a lifespan of about 1,000 to 2,000 hours. Light emitting diode (LED) bulbs, which are increasingly replacing incandescent bulbs, are said to last between 25,000 and 50,000 hours -- an incredible bump.

But dangling from the ceiling of a California firehouse is a bulb that’s burned for 989,000 hours -- nearly 113 years. Since its first installation in 1901, it has rarely been turned off, has outlived every firefighter from the era, and has been proclaimed the “Eternal Light” by General Electric experts and physicists around the world.

Tracing the origins of the bulb -- known the Centennial Light -- raises questions as to whether it is a miracle of physics, or a sign that new bulbs are weaker. Its longevity still remains a mystery.