Sujet : Re: how the laser happened
De : jeroen (at) *nospam* nospam.please (Jeroen Belleman)
Groupes : sci.electronics.designDate : 25. Jun 2024, 23:20:55
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <v5fc78$1nr4t$1@dont-email.me>
References : 1 2 3 4
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On 6/25/24 22:46, Phil Hobbs wrote:
Jeroen Belleman <jeroen@nospam.please> wrote:
On 6/25/24 12:50, Martin Brown wrote:
On 21/06/2024 14:05, john larkin wrote:
There was a thread somewhere above about photon wave/particle duality.
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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.
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More interesting still nature beat him to it.
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The natural source W3(OH) dense molecular cloud which has hydroxyl
masers pumped by UV bright young stars embedded in it.
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Very bright ultra narrow band point sources on a fuzzy nebulous object.
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https://articles.adsabs.harvard.edu/pdf/1981MNRAS.194P..25S
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[...]
The idea has been around for a while. Scifi writer Larry Niven
used it in his Ringworld series of stories. (A ringworld meteorite
defence system strips bare the hull of a space ship on a collision
course with the ringworld surface.)
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Jeroen Belleman
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Of course the Ringworld is dynamically unstable, so it wouldn’t matter that
much if it got hit. ;)
Cheers
Phil Hobbs
Yes indeed. Niven invented a plot twist to fix that in "The Ringworld
Engineers". Dyson spheres aren't stable either. We're making some
headway into making a Dyson swarm though. ;-)
Jeroen Belleman