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Re: energy and mass

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Bill Sloman <bill.sloman@ieee.org> wrote:

> On 22/03/2026 7:37 pm, J. J. Lodder wrote:
> > john larkin <jl@glen--canyon.com> wrote:
> > 
> >> On Sat, 21 Mar 2026 11:13:30 -0700, Ross Finlayson
> >> <ross.a.finlayson@gmail.com> wrote:
> >>
> >>> On 03/21/2026 10:17 AM, john larkin wrote:
> 
> <snip>
> 
> >> One of Einstein's great misses was predicting secondary emission, and
> >> then declaring the laser to be impossible for some thermodynamic
> >> reason.  A good neon sign shop could have made a laser in 1930.
> > 
> > ??? looks like a garbled popularisation.
> > Do you have a serious source for this?
> 
> https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Supplemental_Modu
les_(Analytical_Chemistry)/Instrumentation_and_Analysis/Lasers/Laser_Theory
> 
> It doesn't address Einstein's reasoning, but it does explain how we get
> around the problem that Einstein imagined to be fatal.

It doesn't say anything about Einstein's possible imaginings either.
Neither does it say anything about 'secondary emission'
which is an entirely different phenomenon.
Summary: irrelevant.

> For a laser to work, it has to host a population excited atoms or 
> molecules, where there are more atoms or molecules in the excited high
> energy state than in the ground state - an inverted population. Such a
> population is thermodynamically unstable and decays to the non-inverted
> state, usually pretty rapidly. Einstein didn't happen to think of any
> way you could get an inverted population, but others were luckier.

For perspective: Einstein derived stimulated emission
**in the context of the Old Quantum Mechanics**.
Lifetimes of states and transition rates just were not part of that.
There was nothing but the unexplained 'quantum jumps',
which were assumed to be instantaneous.

Einstein deriving his coefficints nevertheles was a masterpiece
of thermodynamics based on statistical mechanics.

> > What I do know is that serious attempts were made in the thirties
> > to demonstrate simulated emission in neon gas discharges.
> > (so verifying Einstein's B coefficient)
> > IIRC the experiments were difficult, and the results not conclusive.
> > (would have to search).
> 
> They needed a different point of view.

Yes. All blaming of Einstein for not inventing the laser is hogwash.
There just was no basis for it at the time.
All you might 'blame' him for is not returning to the subject
after quantum mechanics became a settled subject,
(which he was fed up with, by then)

Jan

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Re: energy and mass Thomas Heger <ttt_heg@web.de> - 2026-03-14 09:55 +0100
  Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-15 02:02 +1100
    Re: energy and mass Thomas Heger <ttt_heg@web.de> - 2026-03-15 10:08 +0100
      Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-15 20:52 +1100
        Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-16 20:50 +1100
        Re: energy and mass Thomas Heger <ttt_heg@web.de> - 2026-03-19 10:38 +0100
          Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-19 23:18 +1100
            Re: energy and mass Thomas Heger <ttt_heg@web.de> - 2026-03-20 10:36 +0100
              Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-21 00:06 +1100
                Re: energy and mass Thomas Heger <ttt_heg@web.de> - 2026-03-21 10:06 +0100
                Re: energy and mass john larkin <jl@glen--canyon.com> - 2026-03-21 07:31 -0700
                Re: energy and mass Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-03-21 09:35 -0700
                Re: energy and mass john larkin <jl@glen--canyon.com> - 2026-03-21 10:17 -0700
                Re: energy and mass Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-03-21 11:13 -0700
                Re: energy and mass john larkin <jl@glen--canyon.com> - 2026-03-21 14:15 -0700
                Re: energy and mass nospam@de-ster.demon.nl (J. J. Lodder) - 2026-03-22 09:37 +0100
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-22 20:37 +1100
                Re: energy and mass nospam@de-ster.demon.nl (J. J. Lodder) - 2026-03-22 11:34 +0100
                Re: energy and mass john larkin <jl@glen--canyon.com> - 2026-03-22 07:45 -0700
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-23 02:18 +1100
                Re: energy and mass nospam@de-ster.demon.nl (J. J. Lodder) - 2026-03-22 19:13 +0100
                Re: energy and mass Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-03-22 11:44 -0700
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-22 04:32 +1100
                Re: energy and mass Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-03-21 11:22 -0700
                Re: energy and mass nospam@de-ster.demon.nl (J. J. Lodder) - 2026-03-21 22:32 +0100
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-22 04:27 +1100
                Re: energy and mass john larkin <jl@glen--canyon.com> - 2026-03-21 10:44 -0700
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-22 15:54 +1100
                Re: energy and mass john larkin <jl@glen--canyon.com> - 2026-03-23 10:15 -0700
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-24 22:45 +1100
                Re: energy and mass Thomas Heger <ttt_heg@web.de> - 2026-03-26 13:58 +0100
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-27 01:50 +1100
                Re: energy and mass john larkin <jl@glen--canyon.com> - 2026-03-26 08:08 -0700
                Re: energy and mass Bill Sloman <bill.sloman@ieee.org> - 2026-03-27 17:16 +1100
          Re: energy and mass Ross Finlayson <ross.a.finlayson@gmail.com> - 2026-03-19 06:16 -0700

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