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Re: Ectoplasm

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On 10/09/2018 18:05, Michael Moroney wrote:
> Keith Stein <keithstein111@gmail.com> writes:
> 
>> On 10/09/2018 13:07, Michael Moroney wrote:
> 
>>> The only problem with that is that Maxwell's Equations just
>>> come up with the speed of light = constant. Never constant
>>> relative to anything, just the same constant everywhere.
>>> Part of the motivation for Einstein's SR later, which raised
>>> the speed of light=c to all inertial observers to a postulate.
> 
>> Clearly you have never read Maxwell's "Treatise on Electricity
>> and Magnetism", Michael. If you had you would surely know that
>> Maxwell did NOT come up with the speed of light = constant, but
>> rather a speed which depended on the electric permitivity and
>> magnetic permeability OF THE MEDIUM. Not only did he NOT
>> introduce the constants epsilon0 and mu0, but it is obvious
>> that he would have reject such concepts, since the final
>> chapter of his famous Treatise is headed "A MEDIUM NECESSARY".
> 
> The modern Maxwell's Equations (modified by Heaviside, Hertz and others)
> have two forms: an unwieldy form where you essentially have to account for
> every single charge and current but applies to all situations, and a
> simpler/integral form where materials of a bulk form have a displacement
> field D replacing the electric field E, and the H magnetizing field
> replacing the magnet field B. The difference between D and E is D contains
> a permittivity of a material which is E_r*E_0, and H is B divided by the
> magnetic permeability mu of the material, which is mu_r*mu_0.
> 
> The first form does not involve materials (except as a whole bunch of
> charges/currents that have to be accounted for) and produces the vacuum
> speed of light c=1/sqrt(mu_0*E_0). The second form can produce the speed
> of light in a material with permittivity E_r*E_0 and permeability
> mu_r*mu_0.
> 
> Maxwell did not know E_0 and mu_0 individually, but he did know their
> product, and noticed that 1/square root of it was very close to the known
> speed of light. This is why Maxwell suggested light was electromagnetic
> radiation. The product E_0*mu_0 was discovered in an 1855 experiment by
> Weber and Kohlrausch.
> 
> In empty space (no charges, no currents, no materials) the first form is
> used and E_0*mu_0 is constant, so the speed of light c=1/sqrt(E_0*mu_0) is
> also constant.  It does not (cannot) depend on the velocity of anything
> since in empty space there is nothing there to move!


No one ever measured E_0 or mu_0, Michael, for the very simple reason
that THERE ISN'T ANY VACUUM. If you measure the appropriate values for
a low pressure gas then you obtain the velocity of light RELATIVE TO
THAT LOW PRESSURE GAS. It is really very simple. You make difficulties
where there aren't any, Michael.

keith stein




> 

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Ectoplasm xip1415926@gmail.com - 2018-09-08 09:37 -0700
  Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-10 09:51 +0100
    Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-10 10:12 +0100
      Re: Ectoplasm moroney@world.std.spaamtrap.com (Michael Moroney) - 2018-09-10 12:07 +0000
        Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-10 13:32 +0100
          Re: Ectoplasm moroney@world.std.spaamtrap.com (Michael Moroney) - 2018-09-10 17:05 +0000
            Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-10 18:42 +0100
              Re: Ectoplasm Odd Bodkin <bodkinodd@gmail.com> - 2018-09-10 17:53 +0000
                Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-10 19:16 +0100
                Re: Ectoplasm moroney@world.std.spaamtrap.com (Michael Moroney) - 2018-09-10 18:27 +0000
                Re: Ectoplasm "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-09-10 12:23 -0700
                Re: Ectoplasm Odd Bodkin <bodkinodd@gmail.com> - 2018-09-10 19:27 +0000
                Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-11 08:16 +0100
                Re: Ectoplasm Odd Bodkin <bodkinodd@gmail.com> - 2018-09-11 11:52 +0000
                Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-11 14:54 +0100
                Re: Ectoplasm (Whoops! Typos eh!) Keith Stein <keithstein111@gmail.com> - 2018-09-11 16:00 +0100
                Re: Ectoplasm (Whoops! Typos eh!) xip1415926@gmail.com - 2018-09-11 08:27 -0700
                Re: Ectoplasm ( and Epistemology and Einstein's Nefarious Practices.) Keith Stein <keithstein111@gmail.com> - 2018-09-11 16:57 +0100
                Re: Ectoplasm Tom Roberts <tjroberts137@sbcglobal.net> - 2018-09-16 08:56 -0500
                Re: Ectoplasm xip1415926@gmail.com - 2018-09-16 12:48 -0700
                Re: Ectoplasm xip1415926@gmail.com - 2018-09-16 13:01 -0700
                Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-17 18:38 +0100
                Re: Ectoplasm moroney@world.std.spaamtrap.com (Michael Moroney) - 2018-09-17 18:04 +0000
                Re: Ectoplasm Tom Roberts <tjroberts137@sbcglobal.net> - 2018-09-17 14:00 -0500
                Re: Ectoplasm "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-09-17 20:59 -0700
                Re: Ectoplasm "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-09-17 21:16 -0700
                Re: Ectoplasm "Ross A. Finlayson" <ross.finlayson@gmail.com> - 2018-09-23 20:07 -0700
              Re: Ectoplasm moroney@world.std.spaamtrap.com (Michael Moroney) - 2018-09-10 18:16 +0000
                Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-11 07:52 +0100
                Re: Ectoplasm moroney@world.std.spaamtrap.com (Michael Moroney) - 2018-09-11 12:01 +0000
            Re: Ectoplasm Thomas Heger <ttt_heg@web.de> - 2018-09-14 21:16 +0200
              Re: Ectoplasm Thomas Heger <ttt_heg@web.de> - 2018-09-16 20:23 +0200
      Re: Ectoplasm xip1415926@gmail.com - 2018-09-10 07:03 -0700
      Re: Ectoplasm Tom Roberts <tjroberts137@sbcglobal.net> - 2018-09-10 09:39 -0500
        Re: Ectoplasm Keith Stein <keithstein111@gmail.com> - 2018-09-10 16:18 +0100
        Re: Ectoplasm Wilbur Foley <boue@eywffl.uf> - 2018-09-10 17:07 +0000
  Re: Ectoplasm (or History and Foundations of the LT) Keith Stein <keithstein111@gmail.com> - 2018-09-13 16:24 +0100
    Re: Ectoplasm (or History and Foundations of the LT) xip1415926@gmail.com - 2018-09-14 03:45 -0700

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