(Oct 26, 2018 11:41 PM)confused2 Wrote: Syne Wrote:The laws of physics could easily be the same in all frames without the speed of light being invariant, just like any other relative speed is not invariant between frames.
My slippery answer is...
From Maxwell's Equations 'we' get
c=1/√(εμ)
See (for example) https://www.wikihow.com/Derive-the-Speed...-Equations
So, unless ε (vacuum permittivity) and μ (vacuum permeability) are the result of something outside the laws of physics it is sufficient for ε and μ to be the same in every frame (which follows from the laws of physics being the same in every frame) for it to follow that the speed of light will be the same in every frame.
This relation can be derived using Maxwell's equations of classical electromagnetism in the medium of classical vacuum, but this relation is used by BIPM (International Bureau of Weights and Measures) and NIST (National Institute of Standards and Technology) as a definition of ε0 in terms of the defined numerical values for c and μ0, and is not presented as a derived result contingent upon the validity of Maxwell's equations.
- https://en.wikipedia.org/wiki/Vacuum_per...omagnetism
IOW, epsilon nought, mu naught, and c are all physical constants, none of which depending on Maxwell's equation for their validity. The equation just expresses the relationship, and any such equation can be rearranged to solve for any of the variables. If the speed of light were not invariant, or even infinite, that would just mean that Maxwell's equation would not hold. You cannot use constants which might not be invariant if c were not to prove that c is. Constants are just brute physical facts.
(Oct 26, 2018 11:30 PM)Jon Bain Wrote: My own first principle is logic.
Example: If A>B then B<A.
So if TA and TB are durations of time that two objects A and B observe
then
we cannot have A>B and B>A
within an equivalent time frame between 2 events that A and B both incur.
NOW!
Consider this:
http://www.flight-light-and-spin.com/rel...medilation
Now what insults were used to convince you of the validity of relativity?
Lets hear them:
Let's start by putting it nicely. Most physics theories that begin with logic alone tend to lacking.
The A and B rockets moving toward C example comes to the wrong conclusion by overtly not allowing any frame to make direct observations of any other, thus not allowing any transformation that would expose the Lorentz factor. It relies solely on what each frame reports about itself, and of course, symmetrically moving frames will "report" identical times to C. The question Special Relativity addresses is how they view other frames, not how they view their own. This example does not even attempt to do that. If it did, it would be obvious that:
From A's frame, A reaches C before B...because A considers itself at rest and B, moving relatively faster than C, has the greater time dilation, taking longer.
From B's frame, B reaches C before A...because B considers itself at rest and A, moving relatively faster than C, has the greater time dilation, taking longer.
From C's frame, the times, AT and BT, reported by each are both shorter than the time as measured by C...because both are moving relative to C.
Every other example from that link suffers from similarly faulty arguments that ignore the relevant experimental evidence in favor of incredulous reasoning. And while it may be someone's honest attempt at understanding, it is unequivocally crackpot.
Oct 26, 2018 11:30 PM
