Path: ...!Xl.tags.giganews.com!local-1.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Tue, 25 Jun 2024 22:41:47 +0000 From: john larkin Newsgroups: sci.electronics.design Subject: Re: how the laser happened Date: Tue, 25 Jun 2024 15:41:48 -0700 Message-ID: <3ihm7j9kruqmsg57svadl10araoahldqrn@4ax.com> References: User-Agent: ForteAgent/8.00.32.1272 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 77 X-Trace: sv3-PLRaBNYwkN4nVkfcVyXYHG6pldMHEM5VvsY60M34EwaZTa+4/Zhy9AVuR2JHj9+haBSp7k1nvhwWwb2!jun+cC5DD5lpz9+VWQaHXzdzcklMvpmlAndxWwFr0mAH1iYTQE/5um9siB4eWpwsjXHijiAyxXv2!4FUWGA== 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: 4297 On Tue, 25 Jun 2024 17:43:56 -0400, Joe Gwinn wrote: >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 I see the same thing in electronic design. People favor accepted practice, validated in textbooks, and apply all their intelligence to showing how new ideas won't work. A recent case is deciding that the LC's at the output of a switching power supply are "a filter" so must follow classical filter theory, pole-zeros and Butterworths and such. I tell them "It's just a power supply."