|Francis Hauksbee, Nikola Tesla physics
Francis Hauksbee knew the empty space in a thermometer could glow when it was handled, so he put a little mercury in a glass globe, pumped out some of its air, rubbed and touched the globe, and found it emitted a light bright enough to read by.
In 1894, Nikola Tesla invented a lamp without an internal electrode. He subjected an evacuated glass tube to a high-frequency alternating current, starting an avalanche of electrons causing excited atoms to emit photons.
Did Tesla know what he was doing? Does it matter? Did he know what he had found? Did he know he didn’t need high voltage; he didn’t need alternating current? Obviously he knew about the light, but three years later Thomson discovered electrons and Townsend discovered electron avalanches.
Saint Elmo’s fire, mercury gas lit by static, Geissler and Crookes tubes, Geiger counters, fluorescent lamps, neon, metal halide, mercury vapor, deuterium arc, xenon arc, sodium, and plasma lamps.