Path: ...!local-3.nntp.ord.giganews.com!Xl.tags.giganews.com!local-2.nntp.ord.giganews.com!news.giganews.com.POSTED!not-for-mail NNTP-Posting-Date: Tue, 25 Jun 2024 21:43:57 +0000 From: Joe Gwinn Newsgroups: sci.electronics.design Subject: Re: how the laser happened Date: Tue, 25 Jun 2024 17:43:56 -0400 Message-ID: References: User-Agent: ForteAgent/8.00.32.1272 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 64 X-Usenet-Provider: http://www.giganews.com X-Trace: sv3-8pPsAyUVo8+7L7ETofn/og0Sln54+GnCLJP3JeaBT8SaR69Pg1i2h5J5tGPnI8EhIpaLw4Ff4WoHATO!RntP7WS/3Vu0lAXZhmdrR6UtMk69GUDq0hz6HLI56/SGwH8BCobazN8zQtuo5O6NnI8tvf8= X-Complaints-To: abuse@giganews.com X-DMCA-Notifications: http://www.giganews.com/info/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 3718 On Tue, 25 Jun 2024 08:19:03 -0700, john larkin 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. .. This is often paraphrased as "Science progresses one funeral at a time". Joe Gwinn