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Re: Variable Time and the Variable Speed of Light

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<consequently7990662@gmail.com> wrote:
> On Thursday, September 6, 2018 at 8:08:43 PM UTC-7, Thomas 'PointedEars' Lahn wrote:
>> numbernumber1964@gmail.com wrote:
>>> How can you measure the velocity of light with a laser. Where in the
>>> beginning and ending the the pulse?
>> 
>> _Speed_, not velocity.  Velocity is a *vector*; speed is its magnitude.
>> 
>> Put a mirror a known distance D away from the laser emitter. Point the laser
>> at the mirror such that it hits it at an angle of approximately 90°.
>> Measure the time T that it takes for the laser pulse to leave the emitter
>> and return from the mirror.  Divide twice the distance by the time obtained
>> to calculate the two-way speed of light:
>> 
>> c = 2D/T
>> 
>> It helps if D is large, but not so large that gravity matters (otherwise you
>> have to consider that, too).  For example, a large interferometer like LIGO
>> or an earth-based emitter and a mirror on the Moon work well.
>> 
>> Precision can be increased if you let the laser pulse bounce forward and
>> back a few times:
>> 
>> <https://en.wikipedia.org/wiki/Speed_of_light#Time_of_flight_techniques>
>> 
>> If you have a laser interferometer with movable mirrors, you can also
>> calculate c from the interference of a laser beam of known frequency f
>> with itself:
>> 
>> c = λ f,
>> 
>> where λ is the measured wavelength.
>> 
>> <https://en.wikipedia.org/wiki/Speed_of_light#Interferometry>
>> 
>> -- 
>> PointedEars
>> 
>> Twitter: @PointedEars2
>> Please do not cc me. / Bitte keine Kopien per E-Mail.
> 
> _________________________________________________________________
> 
> 
> This c = λ f,  is a wave equation but the formation of a wave requires a
> medium (ether) composed of matter 

That is incorrect 

> yet light produces the interference effect in vacuum that is void of
> matter which nullifies your measurement of the velocity of light using an interferometer.
> 
> 
> 
> 
> 
> 



-- 
Odd Bodkin — Maker of fine toys, tools, tables

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Re: Variable Time and the Variable Speed of Light numbernumber1964@gmail.com - 2018-09-06 15:12 -0700
  Re: Variable Time and the Variable Speed of Light Odd Bodkin <bodkinodd@gmail.com> - 2018-09-06 22:43 +0000
    Re: Variable Time and the Variable Speed of Light numbernumber1964@gmail.com - 2018-09-06 16:18 -0700
      Re: Variable Time and the Variable Speed of Light Odd Bodkin <bodkinodd@gmail.com> - 2018-09-07 00:52 +0000
      Re: Variable Time and the Variable Speed of Light Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-09-07 05:08 +0200
        Re: Variable Time and the Variable Speed of Light consequently7990662@gmail.com - 2018-09-06 20:18 -0700
          Re: Variable Time and the Variable Speed of Light Odd Bodkin <bodkinodd@gmail.com> - 2018-09-07 11:34 +0000
    Re: Variable Time and the Variable Speed of Light numbernumber1964@gmail.com - 2018-09-06 16:53 -0700
      Re: Variable Time and the Variable Speed of Light Odd Bodkin <bodkinodd@gmail.com> - 2018-09-07 00:52 +0000
    Re: Variable Time and the Variable Speed of Light moroney@world.std.spaamtrap.com (Michael Moroney) - 2018-09-07 01:25 +0000
      Re: Variable Time and the Variable Speed of Light consequently7990662@gmail.com - 2018-09-06 20:07 -0700
  Re: Variable Time and the Variable Speed of Light Tom Roberts <tjroberts137@sbcglobal.net> - 2018-09-06 18:15 -0500

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