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Re: Ballistic Theory and the Sagnac Experiment

Subject: Re: Ballistic Theory and the Sagnac Experiment
From: "George Dishman"
Date: Mon, 6 Mar 2006 22:16:05 -0000
Newsgroups: sci.astro, sci.physics.relativity, sci.physics
"Henri Wilson" <HW@..> wrote in message 
news:m8uj02dpulac61k3hlms3p2m552b2ihkb1@xxxxxxxxxx
> On Sat, 4 Mar 2006 17:58:53 -0000, "George Dishman" 
> <george@xxxxxxxxxxxxxxxxx>
> wrote:
>>"Henri Wilson" <HW@..> wrote in message
>>news:c7ed025e5vd6a89j2s36aure3fi3464c5n@xxxxxxxxxx
>>> On Tue, 28 Feb 2006 21:38:55 -0000, "George Dishman"
>>> <george@xxxxxxxxxxxxxxxxx>
>>> wrote:
>>>>"Henri Wilson" <HW@..> wrote in message
>>>
>>>>>>> Since we have established that nothing happens to the rotaing object
>>>>>>> or the rod
>>>>>>> after an acceleration, we must also assume that the two quantities 
>>>>>>> ARE
>>>>>>> indeed absolute and invariant.
>>>>>>
>>>>>>Again you make the same mistake, we can assume they
>>>>>>are constant but that does not imply they are
>>>>>>invariant. You need to learn the difference.
>>>>>
>>>>> No...you need to learn that the universe functioned perfectly well 
>>>>> long
>>>>> before
>>>>> observers evolved.
>>>>
>>>>Prior to baryogenesis? I wouldn't like to
>>>>comment, but after that every particle that
>>>>aborbed a photon was "an observer".
>>>
>>> I understand your point...but what I'm saying is that there is a 
>>> physical
>>> universe that doesn't rely on observers at all.
>>
>>I was making the same point actually. Pythagoras
>>Theorem tells us the relationship between length
>>in a right-angle triangle but that relationship
>>would apply to three rocks that happened to form
>>a right angle, lying on a flat plain of lava when
>>the Earth first cooled. It didn't need Pythagoras
>>or even anyone to measure the lengths. The same
>>is true for light, it's speed was invariant in
>>the early universe because of the geometry of
>>spacetime even though there were no observers
>>there to measure it. The Doppler shift between
>>atoms affected say Lyman alpha absorbtion by the
>>same amount as Ives and Stilwell measured in the
>>lab in 1938.
>
> George, Einstein's second postulate is just a postulate no matter what 
> geometry
> you use to represent it.

Henry, the Earth is round even if you represent
it on a flat sheet to hang on your wall. The
geometry of spacetime is Riemann and that is
the physical reason why the speed of light is
invariant.

>>> Observers only 'interpret' what
>>> they observe.
>>
>>You can look at it that way as long as you
>>understand that "observer" can equally well mean a
>>hydrogen atom absorbing light during the dark ages
>>before the first stars formed.
>
> Of course. Any 'target' is an observer. Every frame has an observer.
> My point George is that measurements buy those observers are not 
> fundamental to
> the operation of the universe.

We agree the point then, the speed of light was
invariant long before life arose to observe it.

George



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