Something which perplexes physicists is why the fundamental physical constants are what they are, why is the speed of the light about 300 000km/s, why is the charge on an electron 1.6 x 10-19C etc. and for that matter are they actually constant. This boils down to why does physics behave as it does, and is it the same everywhere?
The problem is that we can only do experiments to measure them precisely where we can get an experiment to - essentially just in our solar system. Otherwise we are limited to what we can observe. One fundamental constant we can observe very accurately is called the fine structure constant – this is a combination of the charge of an electron, the plank constant and the speed of light, and measures how electric field and quantum mechanics interact to create energy levels in an atom. And it can be measured by looking at the spectra of atoms, so it is very convenient for astronomers.
Close to the earth this seems to be constant, but John Webb and collegues from the university of New South Wales have been looking at some of the most distant sources we can see – quasars which are thought to be huge black holes accreting material billions of light years away. In 2003 they discovered that the fine structure constant appears to have increased about 1 part in 200 000 since the light left the quasars.
But this study was only done in the northern hemisphere, they have recently done a simlar study in the southern hemisphere using the Very Large Telescope in Chile, which has found something possibly even more interesting - the result was that to the south the fine structure constant was changing by about the same amount as you go back in time but it was decreasing rather than increasing.
They have found a fairly strong signal but only time and more experiments will tell if it continues to hold up. If it does it might explain why fundamental physics is so well suited to life, essentially because it varies throughout the universe and our form of life has only developed in the part of the universe where it can survive.
Wait a minute! There's obviously some sort of scientific Three-card Monte going on 'ere. You're expecting me to say,
They aren't constant, Geezer. For example the fine structure constant alpha is a running constant, and thus isn't actually constant, see NIST where you can read:
"a combination of the charge of an electron, the plank constant and the speed of light" So what exactly 'falls out of order' there, all three :) You sure? And was it the same type of discrepancy shown on both sides, decreasing in the southern hemisphere and raising in the northern? one part in 200 000 it seems, on both sides, and we in the middle :)
Even if our current theory's of redshift was incorrect the discrepancy would still exist, right? As a measurable imbalance. But it is based on measuring red-shifted waves from very far away if I get it right.
I've read that paper carefully, yor-on. It's good stuff. I also had a look at that interesting explanation, but it isn't so good. Charged particles don't actually exchange photons - people talk of virtual photons, but they're something different. As for the anthropic principle, that's junk science. There's no supporting evidence whatsoever, and it peddles the mythology of "fundamental constants", relying on people not knowing that alpha is a running constant. Hence we get this "big surprise" when Webb et al report cosmological variations in alpha. Farsight, Thu, 16th Sep 2010
To me photons are photons though :)
Strictly speaking, imatfaal, the equivalence principle only applies in an infinitesimal region. Some say because of that, it doesn't apply at all. I take the view that it's a good principle and some minor infringement doesn't make it a bad principle. Standing on the surface of the earth still equates to accelerating through space even if you manage to spot some part-in-a-billion discrepancy. It's the same for Lorentz invariance. Some seem to want to say "Aha! The whole of relativity must be wrong!". IMHO it isn't, because relativity is full of first approximations anyway. Farsight, Fri, 17th Sep 2010
I will have to bow to your superior knowledge on this but GR is remarkably accurate for a theory that you say is crammed full of first order approximations. imatfaal, Fri, 17th Sep 2010
"Strictly speaking, imatfaal, the equivalence principle only applies in an infinitesimal region." I lost you there Farsight? Are you thinking of the equivalence between acceleration and gravity, or? And in what way is it applied only to infinitesimal regions?
No, I'm talking about the equivalence principle we all know and love. There quite a lot of discussion of infinitesimal regions in the mathspages link you gave:
I'm still not sure what you meant Farsight? You wrote "Strictly speaking, imatfaal, the equivalence principle only applies in an infinitesimal region." And referring me to Kevin Brown that interpretation gets refuted by Einstein in that same paper?
"If you're in a windowless room and you can feel "gravity", you might in fact be in a room in a spaceship accelerating through space. You can't tell the difference, hence the principle of equivalence. However if there's a room above yours, and another and another, you can tell the difference between being in a very tall tower and a very long spaceship."
I was showing you the discussion, yor_on. Read the Pete Brown paper too.
Ahh, you're using the absolute mass of the Earth against the mass of the spaceship moving uniformly at one G? A new one to me, can you prove it?
Peter Brown as well as Hans C. Ohanian seems to share the same view there. As Hans was the first one to share his misgivings about Einstein's theory's I will assume that Peter's pdf build on what Hans wrote. The general conclusion of Ohanian seems to be that he was wrong in most of his views, and that it was more blind luck than any genius that he got it as right as he did :) A rather smug and unpleasant attitude to the physics he introduced it seems to me?
I just want to point out that the results from the southern hemisphere are opposite to the one from the northern hemisphere. Could it be an effect from the earth magnetic field (or ionosphere)? Could the light from these far away quasars posess special chromatic polarization properties? I guess we have to wait... CPT ArkAngel, Sun, 19th Sep 2010
Do physicists understand what constants are in the mathematical sense? constants are numbers added to a function containing one or more known variables that results in the production of a result. Constants represent unknown factors that apparently don't change sufficiently to be detected. These factors could be variables that only change slowly or in which the change is so small that existing equipment lacks sufficient sensitivity to detect the change.
That's one way of expressing it, but if a constant was proofed to change it wouldn't be a constant anymore. "Constants are the terms in the algebraic expression that contain only numbers. That is, they're the terms without variables. We call them constants because their value never changes, since there are no variables in the term that can change its value. ."