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On 21/06/2024 14:05, john larkin wrote:[...]There was a thread somewhere above about photon wave/particle duality.More interesting still nature beat him to it.
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This is worth reading:
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https://www.amazon.com/How-Laser-Happened-Adventures-Scientist/dp/0195153766
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Einstein, in one of his fits of genius, predicted in around 1916 that
under the right conditions, a photon could pass by an excited atom and
the atom would kick in another photon, or add to the wave amplitude,
depending on how you feel about these things. He called it stimulated
emission. He also declared that the laws of thermodynamics made this
effect impossible to use in practical situations.
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In 1951, Charles Townes invented a work-around trick and built the
maser, a gaseous microwave oscillator. His superiors thought he was
crazy to dispute Einstein and almost threw him out of grad school, but
it worked.
The natural source W3(OH) dense molecular cloud which has hydroxyl masers pumped by UV bright young stars embedded in it.
Very bright ultra narrow band point sources on a fuzzy nebulous object.
https://articles.adsabs.harvard.edu/pdf/1981MNRAS.194P..25S
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