Re: The speed of gravity revisited

Juan R. González-Álvarez wrote:
It is really ironic now i am revising a published work by a colleague where he proposes an experiment to differentiate between GR and alternative theory of gravity by measuring one specific effect on the gravitational force on orbiting bodies!

Especially "ironic" is the fact that you cannot meet my challenge to describe how to measure it. Actually, the irony is that you do not understand WHY this challenge cannot be met, and yet you think you are an "expert".


Tom Roberts wrote:
So prove [your claim that I am "completely wrong"], by describing precisely how one MEASURES the "gravitational
force" on an orbiting satellite.

[...complete failure to do so]

If you were actually familiar with this subject and able to meet my challenge, it would be MUCH EASIER to simply describe how to measure "gravitational force" on an orbiting satellite, than doing all the evasion and obfuscation you write to avoid facing the fact that you cannot meet my challenge.


To avoid wasting time now, it would be good to define first the expression for the gravitational force that astronomers working in celestial mechanics measure for an orbiting body.

More evasion -- YOU are the one "wasting time". My challenge is clear and concise. Why is it that you cannot meet the challenge? Even though you claim to be an expert (and are "revising" a colleague's work). (of course _I_ know why you cannot do it, I'm trying to get YOU to understand why this challenge cannot be met)


You claimed that one cannot possibly measure the gravitational force. Before discussing your claim, it may be a good thing if you write first the expression for the gravitational force for an orbiting body (e.g. Mercury planet).

Still more evasion -- Don't evade the challenge, use whatever expression you wish. Use whatever definition of "gravitational force" you wish. But be sure to meet the challenge: describe how to MEASURE the "gravitational FORCE" on an orbiting satellite, not any indirect or model-dependent implications of it (such as orbit parameters, which are geometrical, not any sort of force).

From the nature of this challenge I would expect the answer
to be an English description of an experimental technique,
and not need any equations at all. But however you phrase
your response is up to you.

EXAMPLE: when one whirls a stone on a string around
one's head, it is easy to measure the centripetal force on
the stone -- it is tension and one can simply put a spring
scale between stone and string. But it simply is not possible
to measure the "centrifugal force" -- there is no place to
put the scale. HINT: there is a deep relationship between
this inability and the inability to measure "gravitational
force". HINT2: both "centrifugal force" and "gravitational
force" are coordinate dependent (this is true in both GR and
Newtonian mechanics).


Tom Roberts
.

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