Variable Speed of Light

[Progenitor A]

A Professor from the University of Toronto has proposed that the speed of light has decreased over thousands of light years
He proposes this to explain away the anomaly (that some on this board fully 'understand' anyway) that the diametre in light years of the universe is greater than the age in light years of the universe. (This is 'understood' by some in the context that it is space that is expanding, not the galaxies themselves moving apart - something that I have repeatedly challenged to the usual cries of derision - one of the most laughable being that my definition of speed is ds/dt which has been described as 'kindergarte stuff' even though no alternative definition of speed is available)

Could the Professor be right?

[speakertoanimals]

Why can't some people provide decent references?

www.magazine.utoronto.ca/leading-edge/cosmic-speed-limit-john-moffat-challenges-to-theory-of-relativity/

This says:

tries to find an answer to a paradox that bedevils our understanding of the early history of the universe. More and more measurements and theories indicate that if everything in the visible universe exploded outward from a single point (the so-called Big Bang), and if nothing moves faster than light, then our universe is impossibly big.

Which is just plain WRONG. Exploding outwards from a single point is wrong for starters, but then so is the statement about 'nothing moving faster than light', given that in relativity, we can have nothing moving faster than light, yet the universe still be bigger than speed of light times the age......................

something that I have repeatedly challenged to the usual cries of derision - one of the most laughable being that my definition of speed is ds/dt which has been described as 'kindergarte stuff' even though no alternative definition of speed is available

There are various definitions of speed apart from the simple ds/dt (WHICH s and WHICH t for starters), but since you're too dim to even understand the significance of this statement, then you're also unable to understand why your supposed objections are laughable.

Just because some people have proposed alternative cosmological theories to relativity, and just because university magazines publish grossly simplified statements of the supposed motivation behind this work, doesn't mean that your own simplistic and naive supposed objections to standard relativistic cosmology have any more validity than they did when you first stated them..................

I might also point out the paper referred to is rather old -- 1999, which is hardly cutting-edge cosmology, and perhaps naymissus might like to investigate what has been said on the matter in the last ten years............

M.A. Clayton, J.W. Moffat, Dynamical mechanism for varying light velocity as a solution to cosmological problems, Physics Letters B (460)3-4 (1999) pp. 263-270. ABSTRACT: A dynamical model for varying light velocity in cosmology is developed, based on the idea that there are two metrics in spacetime. One metric g(m nu) describes the standard gravitational vacuum, and the other (g) over cap(m nu) = g(m nu) + beta psi(m)psi(nu) describes the geometry through which matter fields propagate. Matter propagating causally with respect to (g) over cap(m nu) can provide acausal contributions to the matter stress-energy tensor in the field equations for g(m nu), which, as we explicitly demonstrate with perfect fluid and scalar field matter models, provides a mechanism for the solution of the horizon, flatness and magnetic monopole problems in an FRW universe. The field equations also provide a 'graceful exit' to the inflationary epoch since below an energy scale (related to the mass of psi(m)) we recover exactly the standard FRW field equations.

Specialists might note that according to this abstract, this seems also to be a metric-based theory, hence we don't get around the usual naive objections to empty spacetime having a structure................

[Progenitor A]

Well, no knowlegable contributions to this topic.
What the board really needs is a physicist - not necessarily a professor (though that would be nice) but just some one who reliably knows what they are speaking about.

[speakertoanimals]

So, yet more daft attempts to bait me. Why do I bother? (Perhaps in the vain hope that SOMEONE out there is actually interested in the physics..................).

Seems that Clayton and Moffat produced at least 5 more papers in the same vein, from 2000 to 2003. Related to the doubly-special relativity stuff which also predicts a variable speed of light (VSL is you like abbreviations!).

Bi-metric gravity is a good phrase to google on............

The problem with some of this is that early proponents of a sort of VSL theory were nut-job creationists, who needed a fix to try and explain how what we see fits within the 6 thousand years that their adherence to holy writ and bishop Usher seems to demand.

This quote about Moffat is interesting:

Pekka Sinervo, who served as chairman of the U of T physics
department in the late 1990s, says Dr. Moffat's ideas "have been
unorthodox and, in various ways, quite creative. The fact that he
hasn't stumbled upon a revolutionary concept that clearly 'works
better' doesn't take away from the impact his ideas have had. He has
shown that many things that looked promising don't work. This has
been hard work, and he hasn't received, in my opinion, the
appropriate recognition for it."

Which is kind of sad -- someone that does the very necessary work of eliminating things that looked promising (but maybe doesn't come upon the great new idea themselves) seems to get trounced in the celebrity stakes by the upstart that does -- but physicsts have always known that, just that the science press and the public prefer the -- and then I had the great idea that -- plot, rather than the more plodding -- after others had done the hard work in eliminating many strands of enquiry that at first glance might have appeared promising, then I was lucky enough to pick one of the few remaining ones that happened to work.

[speakertoanimals]

not necessarily a professor (though that would be nice) but just some one who reliably knows what they are speaking about.

Just to point out:

1) In the US system, everyone is some sort of professor (associate, assistant etc), whereas in the UK, we have research student, research assistant, research associate (depending on institution), or post-doctoral researcher, lecturers, senior lecturers, and then finally professors and readers.

Mind you, everyone knows that if you want the actual details the professor is the LAST person to ask, you want instead the post-doc or grad student that actually did the work, not the prof that might have been mostly managerial...................

Someone who reliably knows what they are talking about? If cutting-edge research, again the grad students and post-docs. If standard, undergrad stuff, lecturers and senior lecturers that probably do most of the teaching anyway. What are profesors for then? We often ask that ourselves, somewhere to put people when they end up doing more management and admin than actual research, in some cases.......................

But hoping to get one on a message board? Rarer then hens teeth, I'd guess.....................