Re: QM without "photons" or Schr?dinger's wave equation

Andrey Akhmeteli wrote:

"Arnold Neumaier" <Arnold.Neumaier@xxxxxxxxxxxx> wrote:

[Barut's theory ] agrees with QED to low order, but - if I remember
correctly - fails to account for some higher order effects; see, e.g.,
Phys. Rev. A 42, 3703--3717 (1990).

Sorry, it took me long to get this interesting article by M.D. Crisp and
even longer to sort out what the author claims with respect to the Barut's
theory (and it is quite possible that I got it wrong:-) ).

The Barut's theory is mentioned in the article in several places. The idea
is that, while in the nonrelativistic limit the Barut's theory should yield
results parallel to those of the NCT [neoclassical theory] , the Barut's
theory gives more satisfactory results, presumably due to the use of the
causal (and, therefore, complex) Green's functions in the Barut's theory for
elimination of electromagnetic field. The latter may be viewed as a
conceptual drawback of the Barut's theory (Bialynicki-Birula [Phys. Rev. v.
A 34, p. 3500 (1986)] believes this is where second quantization is
covertly introduced by Barut), but this does not affect the following
conclusion: it is my understanding that the Crisp's article does not claim
that the Barut's article fails to account for higher-order effects.

My opinion is otherwise, but I have nothing new to contribute except the
following, though not strongly supported argument.

I don't think Barut's theory can be equivalent to QED, since he lacks
explicit photons. For example, I wonder how he could possibly describe
the experiments with squeezed states of light, which are in accordance
with QED.

So his theory _should_ deviate at higher orders from QED,
even if the above article should not display this fact.
This also explains why the mainstream did not pick up the matter.


Arnold Neumaier

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