The same light bulb has been illuminating a California firehouse for 113 years (and counting)

How many people does it take to screw in a light bulb? For one light fixture in one firehouse in California, the answer is irrelevant — because the original light bulb hasn't burnt out in more than a century.

Known as the Centennial Light — or, to baffled General Electric engineers, the "Eternal Light" — the age-defying illumination was screwed into its socket sometime in 1901, and has rarely been touched since. In fact, the extremely infrequent switching on and off of the Centennial Light might be one of the secrets to the light's longevity, since the lifespan of bulbs is directly correlated with the frequency of switching.

But the true source of the Centennial Light's quasi-immortality is probably the built-to-last nature of the bulb itself, made by the Shelby Electric Company in the late 1890s and marketed as the "brightest and longest lasting" bulb in existence at the turn of the 20th century. The bulb's filament technology was seen as an improvement over flimsier competitors, and Shelby Electric insisted its bulbs would burn 30 percent longer and 20 percent brighter than others.

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You can watch the Centennial Light's "Is it still on?" live stream — or if you don't want to spend the next 113 years waiting for the light to go out, see the miracle light below. --Mike Barry