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Light Bulbs: The Race to Replace Fire
Light bulbs make it almost too easy to just flip a switch and ignore the darkness. Check out Groupon’s guide to the invention that made dusk obsolete.
One of the most life-altering inventions in human history, the light bulb relies on a deceptively simple design. A tiny, coiled strip of metal—known as a filament and commonly made of tungsten—stretches between two electrodes within a sealed glass chamber. As a current passes through the filament its atoms become excited. Some of this excess energy is released in the form of photons. Roughly 90% of these photons are in the infrared spectrum, meaning we only ever sense them as heat; only 10% is actually visible light. Crucially, this whole reaction takes place within a vacuum, since the filament would quickly burn up if a current were to pass through it in the open air. Modern bulbs go one step further by filling the sealed glass with pressurized inert gas, which allows the filament to reach higher temperatures and prevents the glass from blackening everywhere except its top-most point.
Today, the very image of the light bulb is synonymous with invention, and rightfully so, since many people can claim to have invented it. Thomas Edison is often credited with the discovery, but the idea was hardly his. After a British inventor, Frederick de Moleyns, patented a short-lasting version of the incandescent lamp in 1841, his fellow Europeans rushed to perfect the design. Finally, in 1879, a breakthrough: a filament that could burn for hours, invented by none other than Sir Joseph Swan, a Brit. However, Edison’s bulb—created the same year—was much more reliable, and his design endured as the touchstone of modern lighting. Within a century, the vacuum-sealed glass bulbs became the second-most-common light sources in the world, outranked only by the ubiquitous fluorescent bulbs found in office buildings and supermarkets’ glowing milk jugs.