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GEOMETRIZED GRAVITY: THE FUNDAMENTAL RED HERRING IN EINSTEINIANA



 
 
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  #1  
Old June 12th 13, 07:21 AM posted to sci.astro
Pentcho Valev
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Default GEOMETRIZED GRAVITY: THE FUNDAMENTAL RED HERRING IN EINSTEINIANA

http://philsci-archive.pitt.edu/9825...etrization.pdf
Why Einstein did not believe that general relativity geometrizes gravity, Dennis Lehmkuhl: "I argue that, contrary to folklore, Einstein never really cared for geometrizing the gravitational or (subsequently) the electromagnetic field; indeed, he thought that the very statement that General Relativity geometrizes gravity "is not saying anything at all". Instead, I shall show that Einstein saw the "unification" of inertia and gravity as one of the major achievements of General Relativity."

Then why do Einsteinians refer to geometrization of gravity any time the speed of light in a gravitational field is discussed? In order to camouflage the simple fact that the speed of light varies with the gravitational potential like the speed of any material body:

http://sethi.lamar.edu/bahrim-cristi...t-lens_PPT.pdf
Dr. Cristian Bahrim: "If we accept the principle of equivalence, we must also accept that light falls in a gravitational field with the same acceleration as material bodies."

http://www.wfu.edu/~brehme/space.htm
Robert W. Brehme: "Light falls in a gravitational field just as do material objects."

That, in a gravitational field, the speed of light varies like the speed of any material body (as predicted by Newton's emission theory of light) has been confirmed by the Pound-Rebka experiment:

http://courses.physics.illinois.edu/...ctures/l13.pdf
University of Illinois at Urbana-Champaign: "Consider a falling object. ITS SPEED INCREASES AS IT IS FALLING. Hence, if we were to associate a frequency with that object the frequency should increase accordingly as it falls to earth. Because of the equivalence between gravitational and inertial mass, WE SHOULD OBSERVE THE SAME EFFECT FOR LIGHT. So lets shine a light beam from the top of a very tall building. If we can measure the frequency shift as the light beam descends the building, we should be able to discern how gravity affects a falling light beam. This was done by Pound and Rebka in 1960. They shone a light from the top of the Jefferson tower at Harvard and measured the frequency shift. The frequency shift was tiny but in agreement with the theoretical prediction. Consider a light beam that is travelling away from a gravitational field. Its frequency should shift to lower values. This is known as the gravitational red shift of light."

http://www.einstein-online.info/spot...t_white_dwarfs
Albert Einstein Institute: "One of the three classical tests for general relativity is the gravitational redshift of light or other forms of electromagnetic radiation. However, in contrast to the other two tests - the gravitational deflection of light and the relativistic perihelion shift -, you do not need general relativity to derive the correct prediction for the gravitational redshift. A combination of Newtonian gravity, a particle theory of light, and the weak equivalence principle (gravitating mass equals inertial mass) suffices. (...) The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..."

If, in a gravitational field, the speed of light varies like the speed of any material body, then, in gravitation-free space, it varies with the speed of the observer, as predicted by Newton's emission theory of light and in violation of Einstein's relativity:

http://www.youtube.com/watch?v=FJ2SVPahBzg
"The light is perceived to be falling in a gravitational field just like a mechanical object would. (...) The change in speed of light with change in height is dc/dh=g/c."

Integrating dc/dh=g/c gives:

c' = c(1 + gh/c^2)

Equivalently, in gravitation-free space where a rocket of length h accelerates with acceleration g, a light signal emitted by the front end will be perceived by an observer at the back end to have a speed:

c' = c(1 + gh/c^2) = c + v

where v is the speed the observer has at the moment of reception of the light relative to the emitter at the moment of emission. Clearly, the speed of light varies with both the gravitational potential and the speed of the observer, just as predicted by Newton's emission theory of light.

Pentcho Valev
  #2  
Old June 12th 13, 05:04 PM posted to sci.astro
Pentcho Valev
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Default GEOMETRIZED GRAVITY: THE FUNDAMENTAL RED HERRING IN EINSTEINIANA

A javelin graduated in centimeters is thrown downwards from the top of a tower of height h. Initially the centimeter marks pass an observer at the top of the tower with frequency f, speed s and "wavelength" L (1cm):

f = s/L

What are the frequency f', speed s' and "wavelength" L' as measured by an observer on the ground? Newton's theory gives a straightforward answer (it is assumed that ss'-s):

f' = f(1+gh/s^2) = (s+v)/L
s' = s(1+gh/s^2) = s+v
L' = L

where v=s'-s is the increase in speed.

Then the observer at the top of the tower emits light towards the ground. Relative to this observer, the light has frequency f, speed c and wavelength L:

f = c/L

What are the frequency f', speed c' and wavelength L' as measured by an observer on the ground? Newton's emission theory of light gives a straightforward answer again:

f' = f(1+gh/c^2) = (c+v)/L
c' = c(1+gh/c^2) = c+v
L' = L

where v=c'-c is the increase in speed. The Pound-Rebka experiment confirmed the predictions of Newton's emission theory of light:

http://www.einstein-online.info/spot...t_white_dwarfs
Albert Einstein Institute: "One of the three classical tests for general relativity is the gravitational redshift of light or other forms of electromagnetic radiation. However, in contrast to the other two tests - the gravitational deflection of light and the relativistic perihelion shift -, you do not need general relativity to derive the correct prediction for the gravitational redshift. A combination of Newtonian gravity, a particle theory of light, and the weak equivalence principle (gravitating mass equals inertial mass) suffices. (...) The gravitational redshift was first measured on earth in 1960-65 by Pound, Rebka, and Snider at Harvard University..."

Pentcho Valev
  #3  
Old June 18th 13, 06:02 PM posted to sci.astro
Pentcho Valev
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Posts: 8,078
Default GEOMETRIZED GRAVITY: THE FUNDAMENTAL RED HERRING IN EINSTEINIANA

In 1920 Divine Albert said the speed of light is variable in a gravitational field - his interpretation was perfectly valid and made good physical sense. However later the speed of light became constant so nowadays it does not make any sense to say that it varies:

http://math.ucr.edu/home/baez/physic..._of_light.html
Steve Carlip: "Einstein went on to discover a more general theory of relativity which explained gravity in terms of curved spacetime, and he talked about the speed of light changing in this new theory. In the 1920 book "Relativity: the special and general theory" he wrote: "...according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position." Since Einstein talks of velocity (a vector quantity: speed with direction) rather than speed alone, it is not clear that he meant the speed will change, but the reference to special relativity suggests that he did mean so. This interpretation is perfectly valid and makes good physical sense, but a more modern interpretation is that the speed of light is constant in general relativity. (...) Finally, we come to the conclusion that the speed of light is not only observed to be constant; in the light of well tested theories of physics, it does not even make any sense to say that it varies."

Pentcho Valev
 




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