On 10/30/2024 4:29 PM, Alan Grayson wrote:
On Wednesday, October 30, 2024 at 4:39:04 PM UTC-6 Brent Meeker wrote:
On 10/30/2024 10:09 AM, Alan Grayson wrote:
On Wednesday, October 30, 2024 at 5:18:26 AM UTC-6 John Clark wrote:
On Wed, Oct 30, 2024 at 1:17 AM Alan Grayson
<[email protected]> wrote:
/> What are you measuring that you call permeabiliy and
permativity? AG /
*Permeability is a measure of how easily a material (or a
vacuum) allows a_magnetic_ field to be established within it,
and permittivity is a measure of how easily amaterial allows
an _electric_ field to be established within it. For the
numerical values of the vacuum, neither value can be found by
theory alone, but both values were found by experimental
means in the 19th century. And if you know the permeability
(μ₀) and permittivity (ε₀) of the vacuumthen you can
calculate the speed of light because **Maxwell gave us a
simple formula for doing so:*
*
*
*c = 1/√(μ₀ε₀)*
**
*What I'd like to know is how EM wave motions can exist absent a
medium which was thought to be necessary for it to be manifested.
IOW, when repeated MM experiments had null results, what model
was developed, if any, to explain the existence of EM wave
motions? AG
*
I'm always curious about people who ask "how" questions. Like how
does mass make a gravitational field? I wonder what you would
consider a possible answer to your question?
Brent
And I'm curious how nothing can have properties, such as permeability
and permativity.
You didn't like my answer that it just unit matching? Imagine they had
been set to 1 in the early 1800s. All it would have taken was a
different choice of units. Then we'd have c=1 and no
sqrt{\epsilon_0\mu_0} would appear in the wave equation...and no one
would wonder why.
Scholastic thinking is no longer popular, but some of its questions
are worthwhile. I sometimes raise these questions to see if they're
still being asked. As for your question, I prefer the question, How
does mass/energy curve spacetime?
That's a good question, but I think it'll take the quantum theory of
gravity to answer.
Brent
Since it's a postulate of GR, the answer, if there is one, would lie
in a theory which supercedes GR. I'd like to offer such a theory, but
at present I am unable. AG
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