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

[twofish-quant]

However, to construct a theory of time-variable alpha
compatible with SR seems impossible, since this means that there would be a way to distinguish between inertial frames by doing local non-gravitational experiments, even in vacuum.

But you can already. Look at the doppler shift with respect to CMB. If the difference in alpha is due to some big-bang field that is weakening over time, then I don't see any problems that are worse than the fact that the CMB creates a preferred reference frame.

(In particular, there might be a "preferred" inertial frame where alpha varies only in time, not in space.)

Sure. The preferred reference frame of the CMB.

I'm still not seeing out a time shifting alpha is worse than dark energy. You could in principle measure the space time curvature that is caused by dark energy, and that is going to change over time.

I can see no obvious way to circumvent said argument, but maybe you do.

I still don't see how a time varying alpha field is worse than dark energy or anything else that is already in the standard model, and none of those is considered to break GR. One thing that should be pointed out is that in the 1960's these sorts of arguments were taken pretty seriously as reasons why the BB could not be correct. The BB creates a preferred reference frame.

For example, you can come up with a theory in which dark energy creates some sort of shielding effect on electric charge and as the universe expands, changes in dark energy causes observable effects in alpha.

 

[twofish-quant]

I said any given non-gravitational experiment. In your example, two different choices of electric field would give two different experiments.

And if you attribute the change in time of alpha over time is due to the X-field, which you can set differently for different parts or space by increasing or decreasing the strength of the X-field.

Yes this means that we could create a device that could change electron masses and charges which could destroy the earth, but we've already created Earth destroying devices before, and the fact that this is a possibility is why the generals keep funding this research.

If you view alpha as some fundamental property of the universe then I can see the issue, but most high energy physicists don't. In most HEP theories, the charge of the electron is due to GUT fields which can change from place to place just like the mass is due to the strength of the Higgs field which can change from place to place. The fact that we seem to observe electrons having constant mass and charge is explained by cosmic inflation. Under current theories, none of these properties are fundamental, which is why anthropic arguments have suddenly gotten popular.

Yes this sounds a lot like the return of ether, but so what? Among the theoretical cosmological community there isn't this idolatry of mathematical principles that you seem to think exists.

 

[twofish-quant]

One reason I find this sort of experiment exciting is that if you find nothing, you have a lot to explain. If GUT theories are correct, then a constant alpha is weirder than one that varies over space-time.

 

[twofish-quant]

Sure, what I wrote does not make sense, sorry about that. But the crucial question is how to construct a theory of time-varying alpha compatible with SR.

It depends on what you mean by "compatible with SR". Most physicists will require that your field equations are Lorenz covariant, but that's not hard to satisfy, and the reason that is required is that we know of no violations of Lorenz covariance, and if you break that then a 100 other things break.

The condition of "no preferred inertial frames" is not a condition that a strongly constrains what people will accept because we have examples of preferred inertial frames (namely the CMB background).

 

[VelocideX]

Something that I'd look at is to see how much of a doppler shift would be needed to cause the results that you see, and if it's anywhere close to the movement of the earth, then alarm bells should go off. Also something that would be useful would be to take a spectrum of laboratory values, doppler shift it by the movement of the Earth's orbit and then see what the program spits out. I get your point that a general doppler shift shouldn't affect your results, but I'd be interested to see if it does.

The program has been thoroughly tested with rounds of simulations on synthetic spectra over many years. In all cases, the input value of da/a is recovered with the expected statistical errors.

da/a of 10^(-5) corresponds to shifts of between ~100 and ~230 m/s for the Fe II lines of interest. The shifts are extremely small. The size of the pixels is of the order of 1 to 2 km/s. This is the reason the wavelength calibration has to be so good.

 

[Haelfix]

One reason I find this sort of experiment exciting is that if you find nothing, you have a lot to explain. If GUT theories are correct, then a constant alpha is weirder than one that varies over space-time.

I don't follow.

That alpha (or any coupling constant) runs under renormalization group flow is of course not in dispute. That is I think *not* what is meant by these experiments, which presumably accounts for these effects by taking appropriate ratios.

This seems to be a stronger claim, namely that alpha truly does vary with position in spacetime in a nontrivial way (eg decoupled from the thermal background).

You can write down a simple model for this, by simply promoting alpha to be the expectation value of a scalar field (a moduli). Of course this type of theory is troubled from the getgo and is very much unlike the standard GUT picture.

 

[VelocideX]

For example, it may (or may not be) that a magnetic field or charged environment would be described in terms of a higher or lower effective electron charge.

Large scale electric fields cannot build up in the plasma; the electric field gradient would rapidly cause mixing of charges.

Magnetic fields in galaxy clusters typically have strength of ~ microGauss, which is roughly 9 orders of magnitude below the strength required to cause significant effects.

 

[Jonathan Scott]

Given the extraordinary weirdness of this result, I'm tempted to consider controversial explanations.

Consider for example the suggestion that gravitational collapse doesn't actually occur (for which there is some recent evidence) for some unknown reason. In that case, quasars could for example be huge star-like objects with an extremely intense magnetic field, rapid spin and an intrinsically redshifted luminous surface, as in the "MECO" model. That would mean that much of the redshift range, and hence most of the absorbing clouds, would be close to the quasar, and hence potentially affected by its intense magnetic field in a way which would increase with proximity to the quasar and hence with redshift.

Can we rule that out, or at least find some observational constraints on that possibility?

 

[Andy Resnick]

q depends on the value of the fine structure constant in the atom. From the formula above, you can see that it is given by d omega / d x, where x = [(alpha_z - alpha_0)/alpha_0]^2.

To the best of my knowledge, the q values can only be calculated, not measured. In principle, if you could go to high enough energies (where alpha is higher) then you could do it. But most of our measurements are in singly ionised species. At those energies, electrons aren't exactly well bound to atoms :) This is one source of criticism of the experiment, although the q values have been reproduced by independent groups and so they are regarded as reliable.

Thank you so much for your explanation- best of luck with the review process!

 

[TrickyDicky]

Consider for example the suggestion that gravitational collapse doesn't actually occur (for which there is some recent evidence) .

Can you give some reference about this evidence?

 

[granpa]

Can you give some reference about this evidence?

I would be curious to read about this too.

 

[Jonathan Scott]

Can you give some reference about this evidence?

I'm referring to the recent news from ESO about a star in the Westerlund 1 cluster with a mass of at least 40 times that of the sun having apparently unexpectedly collapsed into a magnetar instead of a black hole. Here's a link:http://www.eso.org/public/news/eso1034/"

 

[TrickyDicky]

I'm referring to the recent news from ESO about a star in the Westerlund 1 cluster with a mass of at least 40 times that of the sun having apparently unexpectedly collapsed into a magnetar instead of a black hole. Here's a link:http://www.eso.org/public/news/eso1034/"

Fascinating stuff, thanks.

 

[twofish-quant]

Large scale electric fields cannot build up in the plasma; the electric field gradient would rapidly cause mixing of charges.

But you could have a situation where there are lots of small electric fields. Say caused by black holes.

Magnetic fields in galaxy clusters typically have strength of ~ microGauss, which is roughly 9 orders of magnitude below the strength required to cause significant effects.

That's the overall field. If the objects are 10 pc to 100 pc and an area of active star formation, it's very easy to imagine large numbers of black holes generating very strong magnetic fields.

 

[twofish-quant]

In that case, quasars could for example be huge star-like objects with an extremely intense magnetic field, rapid spin and an intrinsically redshifted luminous surface, as in the "MECO" model.

MECO is just a name for black holes by people that don't understand general relativity and don't understand that black holes can have strong magnetic fields. Quasars *are* huge star-like objects with an extremely intense magnetic field, rapid spin and an intrinsically redshifted luminous surface.

That would mean that much of the redshift range, and hence most of the absorbing clouds, would be close to the quasar, and hence potentially affected by its intense magnetic field in a way which would increase with proximity to the quasar and hence with redshift.

Can we rule that out, or at least find some observational constraints on that possibility?

The fact that the objects are uniformly distributed suggests otherwise. Also you can tell the temperature from the clouds and if they are rapidly moving with respect to a magnetic field, you should seem massive synchrontron radiation.

 

[twofish-quant]

I'm referring to the recent news from ESO about a star in the Westerlund 1 cluster with a mass of at least 40 times that of the sun having apparently unexpectedly collapsed into a magnetar instead of a black hole. Here's a link:http://www.eso.org/public/news/eso1034/"

It's not that unexpected. Given that we have no idea how supernovas actually explode, the fact that you can have a 40 solar mass star turn into a neutron star is not *that* unexpected. Also the MECO paper is pretty much non-sense. The people writing it don't understand GR.

Also a varying alpha isn't that weird.

 

[turbo]

Quasars *are* huge star-like objects with an extremely intense magnetic field, rapid spin and an intrinsically redshifted luminous surface.

Don't say that too loudly. Intrinsic redshifts in quasars are the third rail of astronomy/cosmology. Any hint that two physically-associated astronomical bodies might have widely discordant redshifts will get you marginalized in short order.

 

[twofish-quant]

That alpha (or any coupling constant) runs under renormalization group flow is of course not in dispute. That is I think *not* what is meant by these experiments, which presumably accounts for these effects by taking appropriate ratios.

Right, and alpha happens to be the value of coupling constant when the energy scale is zero. The thing is that the fact that the energy scale is zero is quite arbitrary. Zero is the energy that you have when you are in a vacuum, and there is no particular reason that the vacuum ended up at this energy level rather than at some other one.

One thing that you could argue in 1995, is that the energy level would settle at some value that would level space time "flat" but the discovery of the accelerating universe calls that into question.

This seems to be a stronger claim, namely that alpha truly does vary with position in spacetime in a nontrivial way (eg decoupled from the thermal background).

It would. If alpha happens to be the result of the vacuum energy level being what it is, then you don't expect causally different parts of space time to settle necessarily to the same energy level.

 

[VelocideX]

Consider for example the suggestion that gravitational collapse doesn't actually occur (for which there is some recent evidence) for some unknown reason. In that case, quasars could for example be huge star-like objects with an extremely intense magnetic field, rapid spin and an intrinsically redshifted luminous surface, as in the "MECO" model. That would mean that much of the redshift range, and hence most of the absorbing clouds, would be close to the quasar, and hence potentially affected by its intense magnetic field in a way which would increase with proximity to the quasar and hence with redshift.

Can we rule that out, or at least find some observational constraints on that possibility?

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.

 

[twofish-quant]

Don't say that too loudly. Intrinsic redshifts in quasars are the third rail of astronomy/cosmology. Any hint that two physically-associated astronomical bodies might have widely discordant redshifts will get you marginalized in short order.

That's funny because I don't recall anyone asking me to turn in my astrophysics card when we talk about this sort of stuff at lunch.

Suggesting that associated astronomical bodies *might* have discordant redshifts won't get you looked at funny. It's when you telling that the person you are talking to that they are an idiot and part of an evil conspiracy that will get you problems.

 

[twofish-quant]

No-one takes the gravitational redshift explanation for quasar sources seriously anymore.

Yup.

And one point that I'm trying to make here is that while "quasars are caused by gravitational redshift" is considered a nutty idea by people in the field, the idea that "the fine structure constant may be varying in space and time" isn't, and there are theoretical reasons why you are getting telescope time to look at this whereas as the gravitational redshift people aren't.

 

[turbo]

That's funny because I don't recall anyone asking me to turn in my astrophysics card when we talk about this sort of stuff at lunch.

Suggesting that associated astronomical bodies *might* have discordant redshifts won't get you looked at funny. It's when you telling that the person you are talking to that they are an idiot and part of an evil conspiracy that will get you problems.

What do you think of NGC 7603? Cosmic coincidence, chance projection, or a real viable example of 4 interacting astronomical bodies (excluding the bridge as an entity) having a wide range of redshifts.

My co-conspirators and I are taking baby-steps, studying redshift differentials in M-51 type galaxy associations. Getting published is easy. Getting people to think about the implications is a bit more problematic.

 

[twofish-quant]

Large scale electric fields cannot build up in the plasma; the electric field gradient would rapidly cause mixing of charges.

Magnetic fields in galaxy clusters typically have strength of ~ microGauss, which is roughly 9 orders of magnitude below the strength required to cause significant effects.

One other question. Have you tested your code to see what happens if you do have stray electric and magnetic fields? The general electric and magnetic field in the IGM might be microGauss, but if you have a large number of black holes and neutron stars in the cloud, you can easily get tesla level magnetic fields within the cloud.

Not to say this is a bad thing. Discovering that clouds are highly magnetized is as interesting as finding a varying alpha.

 

[VelocideX]

One other question. Have you tested your code to see what happens if you do have stray electric and magnetic fields? The general electric and magnetic field in the IGM might be microGauss, but if you have a large number of black holes and neutron stars in the cloud, you can easily get tesla level magnetic fields within the cloud.

What would be the origin of large numbers of neutron stars and black holes in the IGM?

 

[Old Smuggler]

But you can already. Look at the doppler shift with respect to CMB. If the difference in alpha is due to some big-bang field that is weakening over time, then I don't see any problems that are worse than the fact that the CMB creates a preferred reference frame.

It seems that I did not express myself clearly enough. What I had in mind, was a theory of varying
alpha in flat space-time. How do you construct such a theory compatible with SR? Even if you
could declare a preferred inertial frame in flat space-time, it would be arbitrary.

Sure. The preferred reference frame of the CMB.

That is not a preferred frame in the sense we are discussing here.

A preferred frame could be part of the gravitational physics of some metric theory of gravity without
violating the EEP (but the SEP would be violated). In that case, the preferred frame cannot be
detected by doing local non-gravitational experiments. If it can, the the preferred frame must be part
of some flat space-time theory to fulfil the EEP.

Of course, according to GR, the frame of the CMB is preferred in neither way, it is just a frame where
a lot of stuff is at rest, on average.

I'm still not seeing out a time shifting alpha is worse than dark energy. You could in principle measure the space time curvature that is caused by dark energy, and that is going to change over time.

That's part of the gravitational physics, and is consistent with GR with an exotic energy field as
source. A time-shifting alpha raises more fundamental problems.

I still don't see how a time varying alpha field is worse than dark energy or anything else that is already in the standard model, and none of those is considered to break GR. One thing that should be pointed out is that in the 1960's these sorts of arguments were taken pretty seriously as reasons why the BB could not be correct. The BB creates a preferred reference frame.

A preferred frame that can be detected locally, by gravitational or non-gravitational experiments,
does indeed break GR.

For example, you can come up with a theory in which dark energy creates some sort of shielding effect on electric charge and as the universe expands, changes in dark energy causes observable effects in alpha.

This seems too speculative for my taste. Anyway, the problem is also how alpha varies in vacuum.

 

[Old Smuggler]

And if you attribute the change in time of alpha over time is due to the X-field, which you can set differently for different parts or space by increasing or decreasing the strength of the X-field.

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.

If you view alpha as some fundamental property of the universe then I can see the issue, but most high energy physicists don't.

I am inclined to believe that the universe has some fundamental properties. The reason why alpha
does/does not vary might well be one of them. And I cannot really see that you have answered my
specific concerns regarding varying alpha. Note that I do not say that the idea of varying alpha is
"nutty" or something like that, I just claim that it is radical, and with no particular theoretical motivation
how to change the mainstream framework to implement it. To me, this seems to signify another dead end.

Yes this sounds a lot like the return of ether, but so what? Among the theoretical cosmological community there isn't this idolatry of mathematical principles that you seem to think exists.

We seem to have very different philosophies how to do science. I prefer parsimonity combined
with a careful assessment of observational results. That is, any extra assumptions specifically made
to make observational results fit theory, is regarded with strong suspicion. Besides, I am well aware
that what is presented as observational "facts" may well depend crucially on theoretical assumptions
made when analyzing the data. Therefore it is important to analyze data within different frameworks.

Since our views do not seem to converge, I think it's just as well to stop here, and just agree to
disagree.

 

[twofish-quant]

What would be the origin of large numbers of neutron stars and black holes in the IGM?

You said yourself that the clouds were likely to be in the halo of galaxies. You have a self-gravitating cloud of hydrogen. It's likely that you will have massive star formation. In any case you know that there has had to have been some star formation in the clouds. Otherwise how did the Mg and Fe get there?

So what I'm proposing is that you have these clouds of Mg and Fe because they were undergoing massive star formation, and if that's the situation then you should have large numbers of black holes and neutron stars in the clouds.

I think it's going to be rather difficult for you to come up with a scenario in which you have strong Mg and Fe lines in which you don't have some neutron stars or black holes floating around somewhere from the supernova that produced those elements.

Also should I infer from the line of questioning that you haven't done an experiment to see if stray magnetic or electric fields will cause some effects mimicking a change in the fine structure constant? If you haven't or if you have and it turns out it does, then I think you should mention in the paper that you are assuming that the clouds don't have strong magnetic or electric fields in them.

 

[twofish-quant]

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.

At that point we are in the world of string theory, and supersymmetry in which you can make up a dozen fields, and no one will mind.

We seem to have very different philosophies how to do science. I prefer parsimonity combined with a careful assessment of observational results. That is, any extra assumptions specifically made to make observational results fit theory, is regarded with strong suspicion.

Maybe it's because we are in different fields. The problem is that in my field (supernova research) parsimonity just doesn't work. There are about twenty different things happening and they all interact with each other.

When you are in the world of GR, you can get away with parsimonity, but that comes at the cost of ignoring much of the rest of the universe. Once you get out of the nice clean world of GR into the messy real work, then parsimonity just doesn't work.

 

[VelocideX]

Also should I infer from the line of questioning that you haven't done an experiment to see if stray magnetic or electric fields will cause some effects mimicking a change in the fine structure constant? If you haven't or if you have and it turns out it does, then I think you should mention in the paper that you are assuming that the clouds don't have strong magnetic or electric fields in them.

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

As I noted earlier, our paper only has 4 pages. Even the long forthcoming paper doesn't describe everything in detail. All our current papers refer to the 2003 paper on systematics, which itself refers to the 2001 paper on systematics.

 

[twofish-quant]

Just for some more of the theory of what is going on...

There are not only papers on varying constants, there are also textbooks and conferences

https://www.amazon.com/dp/1402011385/?tag=pfamazon01-20

http://www.springerlink.com/content/e5ukm4rty3k93c28/

Also some papers

http://arxiv.org/PS_cache/hep-ph/pdf/0204/0204142v2.pdf

* Indeed, it is well known that in string theory any coupling constant is promoted to a vacuum expectation value (vev) of a scalar field such as the dilaton or some other modulus. If this scalar field is extremely light, m  10−33 eV, its expectation value could be still evolving in the recent past (or even today.)

Here is a very interesting paper "Questioning the Equivalence Principle"

http://arxiv.org/PS_cache/gr-qc/pdf/0109/0109063v1.pdf

* The Equivalence Principle (EP) is not one of the “universal” principles
of physics (like the Action Principle). It is a heuristic hypothesis
which was introduced by Einstein in 1907, and used by him to construct
his theory of General Relativity.

* An experimental “violation” of the EP would not at all shake the foundations of physics
(nor would it mean that Einstein’s theory is basically “wrong”). Such a violation
might simply mean that the gravitational interaction is more complex
than previously assumed, and contains, in addition to the basic Einsteinian
spin-2 interaction, the effect of another long-range field.

• String theory suggests the existence of new gravitational-strength
fields, notably scalar ones (“dilaton” or “moduli”), whose couplings
to matter violate the equivalence principle. These fields can induce a
spacetime variability of the coupling constants of physics (such as the
fine-structure constant).