Ned Latham

2020-04-14 09:23:19 UTC

From http://www.einstein-online.info/spotlights/redshift_white_dwarfs

"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. It is,

therefore, perhaps best regarded as a test of that principle rather

than as a test of general relativity."

That last sentence must surely be a non-contentious way of saying

that the gravitational red shift is not a definitive test of general

relativity.

The writer has apparently not considered that the same combination of

factors applies also to the gravitational deflection of light, which

implies that it too is not a definitive test of general relativity.

With two of the three classical tests of GR thus seen as inconclusive,

the question arises as to whether a similar combination could provide

the correct prediction for the relativistic perihelion shift. At first

glance, the idea would seem preposterous: a particle theory of light

must surely eschew Lorentz transforms and Einstein's second postulate,

and in that case an alternative way to the relationships implied by

the gamma() factor must be found. But as it happens, there is one:

postulating that gravity propagates through a field the energy of

which varies as the gamma() factor gives us F = G M m / d² * gamma(v),

which does indeed correctly predict the relativistic perihelion shift.

And yes, the above *is* speculative, but if the math produces the

correct prediction, can it be regarded as fanciful, or in some way

illegitimate? Shouldn't we keep such alternatives in mind when theory

is being tested?

"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. It is,

therefore, perhaps best regarded as a test of that principle rather

than as a test of general relativity."

That last sentence must surely be a non-contentious way of saying

that the gravitational red shift is not a definitive test of general

relativity.

The writer has apparently not considered that the same combination of

factors applies also to the gravitational deflection of light, which

implies that it too is not a definitive test of general relativity.

With two of the three classical tests of GR thus seen as inconclusive,

the question arises as to whether a similar combination could provide

the correct prediction for the relativistic perihelion shift. At first

glance, the idea would seem preposterous: a particle theory of light

must surely eschew Lorentz transforms and Einstein's second postulate,

and in that case an alternative way to the relationships implied by

the gamma() factor must be found. But as it happens, there is one:

postulating that gravity propagates through a field the energy of

which varies as the gamma() factor gives us F = G M m / d² * gamma(v),

which does indeed correctly predict the relativistic perihelion shift.

And yes, the above *is* speculative, but if the math produces the

correct prediction, can it be regarded as fanciful, or in some way

illegitimate? Shouldn't we keep such alternatives in mind when theory

is being tested?