Re: QFT question

"Bjoern Feuerbacher" <bjoern.feuerbacher@xxxxxxxxxxxxxxxxxxxxx> wrote in
message news:d7p7a9$c1$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| FrediFizzx wrote:
| > "Bjoern Feuerbacher" <bjoern.feuerbacher@xxxxxxxxxxxxxxxxxxxxx>
wrote in
| > message news:d7mgun$aj6$1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| > | FrediFizzx wrote:
|
| [snip]
|
|
| > | Au contraire, that is precisely the point here: that in states of
the
| > | electromagnetic field with a given number of photons (including
the
| > | ground state!) the electromagnetic field strength is not zero,
| > | although the expectation values are zero.
| >
| > We are talking about *no* photons.
|
| Err, if you didn't notice: *no* photons is just a special case of
| "a state with a given number of photons". So the above is right on the
| point.

You are talking double-talk again. Measure the EM field strength and
tell me what it is. Bet you get zero EM field strength. ;-) No photons
= zero EM field strength.

| > Give me a reference where someone
| > has measured this non-zero EM field strength when n = 0.
|
| Ever heard of the Casimir effect? That's not a direct measurement, but
| closely related to that.

Sure. However, not everyone is buying the QV explanation. The Casimer
effect is still somewhat speculation as I am sure it has also been
explained via Van der Waals forces.

| Do you deny that QED *predicts* a non-zero field for n=0?

Your question makes no sense. QED predicts an expectation value of zero
for the E(r, t) and B(r, t) EM fields for n = 0. We are talking about
the E and B fields aren't we? So how do we find your "non-zero" EM
fields? You are the one making the claim so show us. How do we find
and measure these fluctuations?

| > | > | > However, the expectation value of the square of the electric
| > | > | > field <E^2(r, t)> is non-zero.
| > | > |
| > | > | Indeed. Don't you think that that's a clear indication that
there
| > | > | still
| > | > | is an electromagnetic field, although the expectation values
of E
| > | > | and B themselves are zero?
| > |
| > | I notice you chose to ignore that.
|
| You essentially still ignore that argument. Do you admit that the
| fact that the expectation value of E^2 is not zero indicates that
| there still is an electromagnetic field, or not?

The result that E^2 is not zero is still speculation. It leads to the
result that the EM vacuum state has infinite energy. Contrary to what
is observed. I highly suspect that the EM spectral energy density of
the quantum "vacuum" is how much energy there could be in the "vacuum"
per mode per a certain volume. Not how much energy the vacuum really
has as far as EM fields go. Now the energy density of the "vacuum" with
respect to fermionic vacua might be a different story, IMHO. Volovik
has the bosonic vacuum and fermionic vacuum canceling each other out. I
don't think that is what is really happening. I think they self cancel
independently *macroscopically*. Microscopically, it is a whole
different story. And quite a long story.

| > Is it really still an EM field?
|
| There is a non-zero probability to measure a non-zero electric and/or
| magnetic field. What else do you want to call that than an
| electromagnetic field?

How could the probability be non-zero to measure non-zero EM fields of
the quantum "vacuum" if the expectation values are zero? I would like
to see that trick. Show your math please.

| Have you ever heard of the "field representation" of the states of the
| electromagnetic field? Of wave "functionals"?

I have heard of them. Your point regarding them is what?

| > Try to measure it. Or show me a
| > reference where someone else measured it.
|
| See above.

See what above? Casimir effect? Not good enough.

| > No photons; no EM field. Period.
|
| Non sequitur.
|
|
| > If there is an EM field then there are photons and n > 0.
|
| Non sequitur.

Non sequitur to your non sequiturs. ;-)

| > | > If you want to claim the
| > | > quantum vacuum has an EM field that photons are excitations of,
then
| > | > measure it and tell me what its value is. Bet you get zero.
| > |
| > | Do you *really* want to claim that in the vacuum state, the
| > | electromagnetic field is exactly zero? You *do* know that the
| > | electromagnetic field is described in QED as an infinite set of
| > | coupled harmonic oscillators, and that harmonic oscillators in
quantum
| > | theory have a non-zero oscillation amplitude even in the ground
state,
| > | don't you?
| >
| > Whoa! Where do you get this "coupled" from? That is my line. ;-)
| > Reference for that, please.
|
| For the "coupled"? That should be in all books discussing the
| quantization of the electromagnetic field. Try e.g. Ryder.

Milonni claims the bosonic QHO's of the quantum "vacuum" are un-coupled
on page 45 and I am sure that they are. Don't have Ryder. Please give
a specific reference or withdraw your claim. Now "vacuum" fermionic
QHO's could be "coupled". And that is how I have them in our quantum
"vacuum" charge theory.

| > Yes, I know about quantum harmonic
| > oscillators just fine.
|
| So you do know that in the ground state, their amplitude is non-zero?
| How can you claim then that in the ground state, the electromagnetic
| field is zero?

Once again, please try to measure this amplitude and tell me what it is.
Ya know ya can't do it. But maybe I can cheat and get a mathematical
result. You should be able to also. So let's see yours. Pretend I am
from Missouri, the "Show Me" state. ;-)

FrediFizzx

http://www.vacuum-physics.com/QVC/quantum_vacuum_charge.pdf
or postscript
http://www.vacuum-physics.com/QVC/quantum_vacuum_charge.ps

.

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