Path: ...!local-4.nntp.ord.giganews.com!Xl.tags.giganews.com!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Tue, 25 Jun 2024 15:19:02 +0000 From: john larkin Newsgroups: sci.electronics.design Subject: Re: how the laser happened Date: Tue, 25 Jun 2024 08:19:03 -0700 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: 56 X-Trace: sv3-CB51ljNVQ2oDrJHXQX9D/g08w71g+fVofOP9KBwjNPNpik6nhfQEgvx+plbYwI8J33YSwuLPhYtilsE!fTMnzbnOmycqpxA8WU7vsf99JB9kViNCyVo3QIEIL8dkIngLIel84KMrMmKuBwreAg9U8ipflkhU!9BX7bQ== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/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: 3391 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.