Re: Is general relativity incompatible with the Newtonian limit?

Juan R. wrote:
> In one of his last works Mathematical Foundations of
> Quantum Theory. (Academic Press, Inc., 1978) Dirac claimed:
>
> Most physicists are very satisfied with this situation [refer to
> divergences of QFT]. They argue that if one has rules for doing
> calculations and the results agree with observation, that is all that
> one requires. But it is not all that one requires. One requires a
> single comprehensive theory applying to all physical phenomena. Not one
> theory for dealing with non-relativistic effects and a separate
> disjoint theory for dealing with certain relativistic effects.
> Furthermore, the theory has to be based on sound mathematics, in which
> one neglects only quantities that are small. One is not allowed to
> neglect infinitely large quantities [...]

However great a theorist was Dirac, he was wrong about this assesment
of renormalization. Perturbative renormalization is based on sound
mathematics *and* is capable of produce correct veriable (and verified)
predictions.

> The agreement [QED] with observation is presumably a coincidence, just
> like the original calculation of the hydrogen spectrum with Bohr
> orbits. Such coincidences are no reason for turning a blind eye to the
> faults of a theory. One must seek a new relativistic quantum mechanics"

The derivation of the Hydrogen spectrum by Bohr was no coincidence. It
has been put on solid footing on by topological aspects of the
semiclassical WKB approximation. If one is allowed to say that the
agreement of QED with observation is merely an coincidence, then the
same can be said about each and every successful theory in physics.

> When one ask by the Newtonian limit of GR one heard in Baez page
>
> http://math.ucr.edu/home/baez/RelWWW/wrong.html
>
> that "The theorem stating that gtr does indeed go over to Newtonian
> gravitostatics in the very weak field, very slow motion limit is proven
> in detail in almost every gtr textbook."

That is indeed true.

[...]
> Then one discovers that the so called 'derivation' given in textbook is
> incorrect.

It is completely unclear to me what your objection to these derivations
is. Having looked through such derivations in a few books, I can't
admit to having found any objections myself.

Without support for the this claim of yours, the rest of the
speculations in your post fall through and perhaps disapear in a black
hole.

Igor

.

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