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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: how the laser happened
Date: Wed, 26 Jun 2024 14:04:56 +1000
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On 26/06/2024 7:43 am, Joe Gwinn wrote:
> On Tue, 25 Jun 2024 08:19:03 -0700, john larkin <jl@650pot.com> wrote:
> 
>> On Tue, 25 Jun 2024 11:50:05 +0100, Martin Brown
>> <'''newspam'''@nonad.co.uk> 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
>>>
>>>> What's interesting is that any decent neon sign shop could have built
>>>> a HeNe laser in 1920.
>>>
>>> They would have needed to make the mirror just cavity right though.
>>
>> I know a guy who built a HeNe. It wasn't hard.
>>
>> T>
>>> A nitrogen gas UV pulsed laser is possible just by getting the pressure
>>> right and creating the  population inversion. Self starting - there was
>>> a (dangerous) experiment in SciAm Amateur Scientist column to do it
>>> sometime in the 1970's. June 1974 in fact - cover shows the BZ reaction.
>>>
>>> https://www.scientificamerican.com/article/the-amateur-scientist-1974-06/
>>>
>>> The failure to discover fullerenes in soot was a lot more surprising
>>> since they were there all the time since the invention of fire just
>>> waiting to be extracted by benzene. For a long time space dust had a
>>> spectrum that could not be reproduced on Earth by any known compound.
>>>
>>> Much like Helium was in the sun but more pervasive.
>>
>> Too many powerful old farts declare things to be impossible.
> 
> .<https://en.wikipedia.org/wiki/Planck%27s_principle>
> 
> This is often paraphrased as "Science progresses one funeral at a
> time".

https://en.wikipedia.org/wiki/Planck%27s_principle

The irony is that Max Planck wasn't that kind of powerful old fart.

He published Einstein's four 1905 papers without bothering to get them 
refereed.

https://en.wikipedia.org/wiki/Annus_mirabilis_papers

Science does have a hierarchy problem, but it frequently surmounts it.

-- 
Bill Sloman, Sydney

-- 
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