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GR and piezoelectricity?
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Ken S. Tucker
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Joined: 30 Apr 2005
Posts: 1230

PostPosted: Sun May 21, 2006 3:45 pm    Post subject: GR and piezoelectricity? Reply with quote

I have a question about piezoelectricity in GR...

In conserving energy in GR, it's accepted Div T =0 , i.e.
T^uv;v=0.

That is also an exchange between the mechanical
energy density I'll denote M^uv and the EM energy
density I'll denote E^uv such that,

M^uv;v + E^uv;v = 0,
and
M^uv;v = - E^uv;v

I think that's standard text book stuff,
and a good demonstration of that is used
in piezo-electrically based electronic weigh
scales, where a mass (pressure) deforms
a piezoelectric-crystal which in turn produces
a voltage, and then that voltage is measured
and displayed.

1) What is the maximum accuracy of the
measurement of the voltage output?

1a) Is it infinite or does the Heisenberg Uncertain
Principle (HUP) apply and thus quantizing the
measurement?

I'll assume (1a) is true and assume HUP applies,
but then I get into trouble with the continuous
transfer given by,

M^uv;v = - E^uv;v (2)

which is not quantized.
2) Should it be quantized?

I would reword (2) to ask, if the generation of
electricity by mechanical action, (hydroelectric
power) is quantized, to which I would think yes.
The reasoning for the quantization of power is
because voltage causing a current flowing through
a resistor produces heat, and that heat in turn
appears as infared radiation, and thus photons.

So I'll try modifying Eq.(2) to a quantized form,

M^uv - Delta M^uv = E^uv + Delta E^uv , (2a)

where the deduction of Mechanical M^uv
denoted -Delta M^uv generates Electricity
by +Delta E^uv, with the "Delta's" being a
quanta exchange, in place of a continuous
exchange of energy density in (2).

What I imagine is Eq.(2) describes a power
transfer, but because power is quantized,
Eq.(2a) is suggested in place of (2).

Using Eq.(2a) every covariant derivative in the
4 terms therein now vanish, because there is no
*continuous* transfer of energy, from the stand
point of the application of the Quantum Theory.

IMO, an outstanding issue that needs resolution
is whether Lorentz force vanishes as AE suggests
in GR1916 Eq.(65a), denoted therein by
kappa_sigma = 0.
If the affirmative is presumed, then the predicted
(from Eq.(2a) above)

E^uv,v=0 == kappa_sigma=0,

is also true, thereby uniting GR with QT, at least
removing some outstanding issues that seem to
separate these seemingly distinct theories.
Regards
Ken S. Tucker
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Igor Khavkine
science forum Guru


Joined: 01 May 2005
Posts: 607

PostPosted: Tue May 23, 2006 5:45 pm    Post subject: Re: GR and piezoelectricity? Reply with quote

Ken S. Tucker wrote:

[... M and E are, respectively, the mechanical
and EM stress energy tensors ...]

Quote:
1) What is the maximum accuracy of the
measurement of the voltage output?

1a) Is it infinite or does the Heisenberg Uncertain
Principle (HUP) apply and thus quantizing the
measurement?

I'll assume (1a) is true and assume HUP applies,
but then I get into trouble with the continuous
transfer given by,

M^uv;v = - E^uv;v (2)

which is not quantized.
[...]


Quantum mechanics does not imply quantization of measurements. It only
implies non-commuting observables, which then may not be simultaneously
observable. All your questions seem to be of the form "what of this
classical equation when quantum effects become important?". That's the
wrong question to ask.

If quantum effects are important, then classical equations are a priori
inapplicable and the situation of interest has to be treated quantum
mechanically from the start. However, it is not clear what particular
physical situation you are interested in and hence it is not clear what
kind of answer can be given.

Igor
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