On 4/30/2025 4:29 AM, John Clark wrote:
On Tue, Apr 29, 2025 at 8:09 PM Brent Meeker <[email protected]>
wrote:
*>> If you place two macroscopic conductive plates close to
each otherthe Casimir Effect will cause the two plates to
attract each other; this occurs regardless of if you make any
measurements or not. It happens because there are fewer
virtual particles between the two plates than there are
outside the plates. And virtual particles exist because it's
impossible for the energy in the electromagnetic field to be
exactly zero for any arbitrary length of time; and the shorter
the time the greater the deviation from zero it's likely to be. *
/>That's why the qualification about measure like interactions.
The two conductive plates exclude longer wavelengths. /
*Yes.*
*
*
/> I don't recall that the effect depended on duration. /
*Heisenberg's uncertainty principle is not just about the relationship
between momentum and position, it also insists there is a similar
relationship between energy and time; the shorter amount of time the
greater the random variation from a zero value there is. *
In quantum mechanics /*energy*/ and the /*time per unit change of a
variable*/ are conjugate variables. So they satisfy an Heisenberg
uncertainty relation, often written $\Delta E \Delta t \geq \hbar$ .
This is sloppy though and not quite right. What is right is given any
operator $A$ and the Hamiltonian $H$ defining the time evolution of $A$,
then $\Delta A \Delta H \geq \frac{1}{2} \hbar [d<A>/dt]$ . In this case
I don't see what is the time per unit change in the expected value of
the energy density between the plates? The plates are assumed stationary.
Brent
*And without that there wouldn't be any wavelengths (or virtual
particles) inside or outside those plates and the Casimir Effect would
not exist. *
**
*John K Clark See what's on my new list at Extropolis
<https://groups.google.com/g/extropolis>*
*
*
6tc
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