Why physicists refuse to measure the one-way speed of light directly?
in [Relativity]
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From: Tom Roberts on 5 Feb 2010 17:37 Rock Brentwood wrote: > The correct statement is: the speed of light in a "vacuum" (i.e. a > boost-invariant, rotation-invariant, translation-invariant medium) in > a flat Minkowski space is a constant. > > Correct though this may be, it is not physically relevant for two main > reasons: (1) there is no such thing as a vacuum, not even outer space, > and (2) the cosmos is not flat, as a space-time geometry. Nonsense. You need to learn how to think like an experimental physicist. Yes, Minkowski spacetime is a MODEL, not some "absolute truth" (or somesuch). To apply it one must COMPUTE how accurately the model applies to a given experiment. For EVERY ONE of the relevant experiments measuring the speed of light in vacuum, your claims are irrelevant. That is, the effect due to the residual gas in the vacuum, and the effect due to the curvature of spacetime, are both NEGLIGIBLE. Minkowski spacetime is a highly accurate model for many situations and experiments. That makes it "physically relevant" to them. Tom Roberts
From: PD on 5 Feb 2010 17:39 On Feb 5, 4:23 pm, glird <gl...(a)aol.com> wrote: > On Jan 22, 10:50 am, Tom Roberts <tjrob...(a)sbcglobal.net> wrote: > > >< Einstein described two basic methods to synchronize two clocks A and B at rest in a given inertial frame: > > A) Place a light source exactly midway between them. Arrange so the > source simultaneously sends a light pulse (propagating in > vacuum) > direct to each clock, and make the clocks start ticking at the > same indicated value when they receive the light pulse. > B) Send a light pulse from A to B, and have B immediately return it > to A (e.g. with a mirror). Adjust the clocks so the reflection > at B occurs at an indicated time midway between the two times at > A. > {snip} > Given one-way isotropy in the speed of light (guaranteed in SR by the > second > postulate), these two methods are equivalent, and always yield clocks > that > measure the speed of light to be isotropic. As no mention of which > inertial > frame was used, this applies in any inertial frame, thus ensuring > invariance of > the one-way speed of light.> > > Exercise 1 for readers: Find where he wrote item A in his 1905 STR > paper. > (Clue: It wasn't there.) > Exercise 2 for readers: Without using his method of "synchronizing" > the two > clocks, show that the 2nd postulate suffices > to > assure isotropy in the speed of light in > all > directions. > (Clue: If you adhere to his Minkowski- > denied > assumption, this is impossible,) > > glird The 1905 paper is not the be-all, end-all of relativity. If you were expecting that one paper to be the comprehensive compendium and reference for SR, I'm afraid you're barking up the wrong tree.
From: glird on 5 Feb 2010 20:44 On Feb 5, 5:39 pm, PD <thedraperfam...(a)gmail.com> wrote: > On Feb 5, 4:23 pm, glird <gl...(a)aol.com> wrote: ><> Exercise 2 for readers: Without using his method of "synchronizing" the two clocks, show that the 2nd postulate suffices to assure isotropy in the speed of light in all directions. (Clue: If you adhere to his Minkowski-denying assumption, this is impossible,) > > > The 1905 paper is not the be-all, end-all of relativity. If you were > expecting that one paper to be the comprehensive compendium and > reference for SR, I'm afraid you're barking up the wrong tree. Woof!! P--...leeze try to do exercise 2 anyway... f u can gird
From: spudnik on 5 Feb 2010 20:53 Herman Minkowski was a great geometer, but he totally ****-up the simple idea of phase-spaces (a la Hamiltonians, Lagrangians etc.); then, he died. > (Clue: If you adhere to his Minkowski-denying assumption, this is > impossible,) > thus: the gist seems to be that Schoenfeld did prove that his thing was equivalent (iff) to RH; so, what are you going to do about it? thus: problem is that the Arhcimedean Valuation has its own daffynition of "inductive versus deductive" proofs, although they are strictly isomorphic. the real problem seems to be one of an unacknowledged attainment in English as a Second Language; thereby, most of his reults are pidgin (like Korbyzinski's joke- language, E-prime .-) thus: well, that seems rather to dyspoze of the whole issue, viz-a-vu. and, like I said, in January, like that Magadin said, about primes of the form 4n +/- 1 (-1 is not a second power mod 4 ?-) thus quoth: Mertens's Theorem is in fact a rigorous proof that they're not independent in the sense you need them to be). --les OEuvres! http://wlym.com --Stop the quagmire retread in Afghanistan; see "The Most Dangerous Man" on Feb.12 opening at Music Hall Theater on Wilshire in Beverley Hills! http://www.laemmle.com/viewmovie.php?mid=5177
From: spudnik on 5 Feb 2010 20:59
and, remember, Michelson & Morely and their successors did NOT get "null results." thank you! |