On Wednesday, October 30, 2024 at 11:47:05 PM UTC-6 Brent Meeker wrote:
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 a material 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 vacuum then 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. *You assume I didn't like your answer. In fact I don't understand it sufficiently to use it in a way that satisfies you. AG* 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. *I doubt it will happen. If it did, it would invalidate a geometric interpretation of gravity, which IMO is unlikely. AG* 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. A -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/everything-list/88e08990-4e16-4e9e-900c-f1fe206c02e3n%40googlegroups.com.
