Fine structure constant probably doesn't vary with direction in space

[Haelfix]

But what does the variation of the X-field depend on? Is there a theory of the X-field in flat
space-time? It seems that all you have done, is to transfer the problems of varying alpha to the X-field.

The problem isn't introducing this field, indeed such things show up in HEP theories all the time, as Quant explained. The problem is explaining why it's natural.

If the field is massive and cosmological in origin, you expect that the physics that originated it occurred sometime in the very early universe. The typical mass scale would be, say grand unification or Planck scales. The problem is that such a field would give totally negligable contributions in experimental searches in ordinary galactic physics, so that probably isn't what is responsible.

Really, what you need is a field that is massless or almost massless, and you want it to be very slowly varying (so that it doesn't produce completely ridiculous physics). Now if the field was massless or almost massless, you do run the risk of introducing new (real or apparent) long range forces that would *likely* start running afoul of solar system equivalence principle tests.

http://arxiv.org/abs/hep-ph/0111282

However there is a bit of a tightrope that you can walk in this sort of game, but typically it comes with steep phenomenological baggage and or arbitrary tweaking. All this is general, the additional problem faced with changing alpha, is to explain why the physics only targets this coupling constant and not the others. Prima facie, it requires a terribly adhoc and explicit symmetry breaking term but anyway I digress.

The point is, if the result is true (and I am skeptical of course given the dirty business and complications in measuring quasar spectral line's and controlling the possible systematics), it's goign to be rather unlovely to explain theoretically.

 

[Jonathan Scott]

How do you explain the fact that the host galaxies of the quasar absorbers can be identified in many cases?
e.g. http://adsabs.harvard.edu/abs/2008A&A...487..583B

Also, this does also does nothing to explain the Lyman-alpha forest -- the dense series of Lyman alpha transitions along the line of sight to the quasar which all occur below the Lyman alpha emission peak. High column density Lyman alpha absorbers have been identified with host galaxies at cosmological redshifts. Hydrodynamic Lambda-CDM simulations reproduce the observed statistical properties of the forest as far as I know. No-one takes the gravitational redshift explanation for quasar sources seriously anymore.

Thanks for the reference. I think the suggestion is only that part of the redshift is intrinsic, by no means all of it, so identification of intervening host galaxies provides limits on the amount of intrinsic redshift, but does not rule it out.

Also, Arp's controversial observations have always indicated that quasars which appear to be closer to their "parent galaxy" have higher redshifts, which suggests that quasars lose their intrinsic redshift as they age and "mature" into new galactic cores.

From what I've heard (although I admit I don't have any references to hand), the Lyman-alpha forest is not actually uniform with redshift, so any explanation involves some sort of evolution, usually expressed as a power law, and I've heard that although the number density towards different objects of similar redshift is often statistically similar, there is a surprising amount of variation, and it is difficult to match up the varying densities consistently with different redshifts.

 

[twofish-quant]

Thanks for the reference. I think the suggestion is only that part of the redshift is intrinsic, by no means all of it, so identification of intervening host galaxies provides limits on the amount of intrinsic redshift, but does not rule it out.

It's not inconceivable that quasars have some intrinsic redshift, but no one has suggested a mechanism that gives you redshifts that have anything close to the Hubble flow.

Also, Arp's controversial observations have always indicated that quasars which appear to be closer to their "parent galaxy" have higher redshifts, which suggests that quasars lose their intrinsic redshift as they age and "mature" into new galactic cores.

No one takes Arp's observations seriously now. As we've gotten better and better observations of quasars, Arp's ideas are taken less and less seriously.

From what I've heard (although I admit I don't have any references to hand), the Lyman-alpha forest is not actually uniform with redshift, so any explanation involves some sort of evolution, usually expressed as a power law

That's correct, but the problem for people that assert that quasars are not cosmological need to explain why there is a lyman alpha forest at all.

 

[twofish-quant]

One thing to remember is that I'm a theorist, so my job involves coming up with explanations. If you start seeing independent confirmations of varying alpha over the next year or two none of this matters, and you can collect your Nobel prize without worrying about any of this. (That's not sarcastic, if this observation holds, then someone will be in line for a Nobel.)

What I'm interested right now is imagining what the possibilities are if people continue to get null results.

Large scale electric fields have never been observed in astrophysics AFAIK.

Neither have time varying alphas until now. :-) :-)

The issue of magnetic fields was dealt with in a 2001 paper on systematic effects and the statements made were uncontroversial then. The magnetic field strength in the strong absorbers has been inferred from Faraday rotation and is just too small.

I'll look at the 2001 paper, but something to realize is that people in doing Faraday studies have been looking at microgauss strengths, and if the light goes through a reason of tens of gauss oriented in random directions, the likely outcome is that any preexisting polarization is going to get lost, and so what you'll see is something unpolarized.

 

[cristo]

This thread has strayed too far from the PF rules of allowing discussion on only published, peer-reviewed articles. Thus, I'm locking this thread now. This topic can be reopened when the paper is published.