Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Phil Hobbs Newsgroups: sci.electronics.design Subject: Re: how the laser happened Date: Tue, 25 Jun 2024 20:46:32 -0000 (UTC) Organization: A noiseless patient Spider Lines: 50 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Tue, 25 Jun 2024 22:46:33 +0200 (CEST) Injection-Info: dont-email.me; posting-host="49ed6207776d43b655c4dc8495aa953e"; logging-data="1821489"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19qOTtqel3Q4+AZPK6uVPvf" User-Agent: NewsTap/5.5 (iPhone/iPod Touch) Cancel-Lock: sha1:z0f6U8q1+xTYsrYOx7C+zL0+jMk= sha1:m3br/V5tHESM5bHLwWeodyviFPY= Bytes: 2973 Jeroen Belleman 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. >>> >>> >>> 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 > Of course the Ringworld is dynamically unstable, so it wouldn’t matter that much if it got hit. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics