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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: how the laser happened
Date: Tue, 25 Jun 2024 20:09:30 +0200
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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.
>>
>>
>> This is worth reading:
>>
>> https://www.amazon.com/How-Laser-Happened-Adventures-Scientist/dp/0195153766
>>
>> 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.
>>
>> 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.
> 
> More interesting still nature beat him to it.
> 
> 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
> 
[...]
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.)

Jeroen Belleman