Re: Hobba's misconceptions

Ilja Schmelzer:
>
>Happy New Year,
>
>"Bilge" <dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> schrieb
>> Ilja Schmelzer:
>> >"Bilge" <dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> schrieb
>> >> Ilja Schmelzer:
>> >> >"Bilge" <dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> schrieb
>> >> >> Except that it won't be considered a relativistically correct
>result
>> >> >> without a proof that the result is manifestly covariant.
>> >> >
>> >> >without a proof that the observables results are covariant.
>> >> >Manifest covariance is not that important.
>> >>
>> >> It's not important to _you_.
>> >
>> >It's not important to obtain correct predictions about observable
>> >(physical) effects. Which is what is important for physics.
>>
>> You seem to be under the mistaken impression that it's ok to
>> violate the premises of the theory to get the right answer and
>> then claim the answer is predicted by the theory.
>
>No.

Then why have yu been arguing otherwise?

>> >If this would be the case, relativity would be falsified. But, because
>> >you are wrong, SR is not considered to be falsified.
>>
>> As usual, you provide no evidence for your claims.
>
>There is no manifestly covariant version of the wave function of
>standard quantum theory.

The wavefunction is not a relativistic quantity. That's why
field theories are field theories. You can't describe relativistic
theories by coupling to potential energy functions.

>There are (AFAIK) no manifestly
>covariant regularizations for the standard model, therefore we
>have no manifestly covariant (in a sufficiently strong sense)
>quantum theories at all.
>
>What can be computed in manifest covariant ways is only
>the scattering matrix, which is an infinit limit. This infinit limit
>is a very good approximation for the observations, but,
>last not least, all our experiments are, in principle, finite,
>and for finite distances we have no manifestly covariant
>quantum field theory.

You are confused. The qed lagrangian is obviously manifestly
covariant:

L = \Psibar(i\gamma^u D_u - m)\Psi + (1/4)F^uvF_uv

The issue of covariance only comes up when one makes an explicitly
non-covariant separation of the momentum into the the electron momentum
and the electromagnetic interaction in order to use perturbation theory,
and in particular, to quantize it using a hamiltonian that is not
manifestly lorentz covariant, but happens to be convenient (or at least
is intuitive, since it most resembles newtonian mechanics). The lagrangian
certainly starts out as a lorentz scalar.

However, there are other choices for quantizing the theory and in
particular, the point form hamiltonian _is_ manifestly covariant.
It also happens to be very difficult to work with and as a result,
not much work appears in the literature. On the other hand, you
might ponder the reason that any result requires the summing of
non-covariant diagrams to obtain a covariant result.

>> >LOL. In SR it is impossible to give a mathematically consistent
>> >description of reality.
>>
>> It's impossible to give a mathematically consistent description of
>> _your_ idea of reality using special relativity.
>
>Which follows Einstein (EPR) and Bell.

Is that supposed to add any reality to the description?

>> However, it's also
>> impossible to give a mathematically consistent description of your
>> idea of reality, period,
>
>Nonsense. Mathematically consistent descriptions of reality
>which fit with my ideas about realism exist, for example,
>Bohmian mechanics.

Somehow, inventing imaginary entities that violate the physics that
applies to everything else in the universe, to maintain a newtonian
picture of a non-newtonian universe at the expense of understanding the
actual physics, is not my idea of reality. Bohmian mechanics is an
ill-conceived insult to bohm.

[...]
>> You are deliberately being dishonest by conflating a particular
>> definition of reality with the reality of how nature works.
>
>I'm not dishonest at all. To describe my concepts, I use the
>words realism (a philosophical theory), realistic explanation
>(something done by humans), or, in the above quote, "description
>of reality" (which is also something done by humans).

You use the word ``realism'' to avoid having to come up with
something concrete.

>It's you who tries to conflate this.
>
>> Fine,
>> on that basis, nature is falsified, since nature doesn't fit your
>> definition.
>
>Nonsense. My definition is not about nature, but about
>theories about Nature, which may be realistic theories about
>Nature or non-realistic theories about Nature. If there exists
>no viable realistic theory of Nature, my concept of realism
>would be falsified, but not Nature.

>
>BTW, viable realistic theories exist, thus, nor Nature nor
>my concept of realism are falsified.
>
>> Since you don't really demand reality to have any
>> direct relationship to measurements, that shouldn't be a problem.
>
>The relationship between realistic theory and measurement is
>well-defined and sufficiently direct, given by the basic formula
>of realism:
>
>E(f|c) = int f(m(x,c)) rho(x) dx
>
>Here, E(f|c) is the observable expectation value of the function
>f(m) defined on the set of measurement results m, depending on
>control parameters c.
>The requirement of realism is that for _every_ observation there
>should be a realistic explanation of this form.
>
>Ilja
>
>
.

Relevant Pages

  • Re: Hobbas misconceptions
    ... >>> If a manifestly covariant theory cannot describe the observables, ... > _your_ idea of reality using special relativity. ... > definition of reality with the reality of how nature works. ... words realism, ...
    (sci.physics.relativity)
  • Re: Hobbas misconceptions
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  • Re: Two EPR questions
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