Lets see, 130 years ago Edison electrically heated a filament of carbon, beating out candles and kerosene lanterns and it was good... for about 20 hours. But switching to Tungsten and using Argon gas boosted the lifetime to 1000 hours and an output of about 17 lumens per watt in a 100 watt 1700 lumen bulb. Cost per bulb, $1. Bulbs per 25,000 hours
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