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

  1. bcrowell

    bcrowell 5,683
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    The thread "Fine Structure Constant Varies With Direction in Space!" was locked because it didn't cite papers published in refereed journals. Actually all of this stuff has been published in refereed journals. The list of references below is cut and pasted from http://en.wikipedia.org/wiki/Fine_structure_constant . Quite a few of the papers are also on arxiv.

    My own opinion is that Webb et al. are wrong. Extraordinary claims require extraordinary evidence. Their evidence is statistically significant if you (a) believe their error bars, (b) believe that there were no unidentified systematic errors, and (c) believe that, as claimed by Webb, the Chand group's failure to reproduce the result is due to statistical mistakes by Chand et al., rather than being due to the nonexistence of the purported effect. Even if I believed a, b, and c, I wouldn't consider it statistically significant at the level that would make me believe such an extraordinary claim. It would be interesting to hear whether the Chand group has ever responded to the statistical criticisms. If you buy the idea that the fine structure constant varies over time, then it's actually not much of a leap to believe that it varies spatially as well. If it only varied with time in one frame of reference, it would vary in both time and space in another frame that was moving relative to the first. If it depended on cosmological parameters, I suppose it would be surprising to see an anisotropy that was observable in the frame of our own galaxy, which is more or less moving with the Hubble flow.

    J.K. Webb et al. (2001). "Further Evidence for Cosmological Evolution of the Fine Structure Constant". Physical Review Letters 87 (9): 091301. doi:10.1103/PhysRevLett.87.091301. arXiv:astro-ph/0012539. PMID 11531558.
    M.T. Murphy, J.K. Webb, V.V. Flambaum (2003). "Further evidence for a variable fine-structure constant from Keck/HIRES QSO absorption spectra". Monthly Notices of the Royal Astronomical Society 345: 609. doi:10.1046/j.1365-8711.2003.06970.x.
    H. Chand et al. (2004). "Probing the cosmological variation of the fine-structure constant: Results based on VLT-UVES sample". Astron. Astrophys. 417: 853. doi:10.1051/0004-6361:20035701.
    R. Srianand et al. (2004). "Limits on the Time Variation of the Electromagnetic Fine-Structure Constant in the Low Energy Limit from Absorption Lines in the Spectra of Distant Quasars". Physical Review Letters 92: 121302. doi:10.1103/PhysRevLett.92.121302.
    M.T. Murphy, J. K. Webb, V.V. Flambaum (2007). "Comment on “Limits on the Time Variation of the Electromagnetic Fine-Structure Constant in the Low Energy Limit from Absorption Lines in the Spectra of Distant Quasars”". Physical Review Letters 99: 239001. doi:10.1103/PhysRevLett.99.239001.
    M.T. Murphy, J.K. Webb, V.V. Flambaum (2008). "Revision of VLT/UVES constraints on a varying fine-structure constant". Monthly Notices of the Royal Astronomical Society 384: 1053. doi:10.1111/j.1365-2966.2007.12695.x.
     
  2. jcsd
  3. I'm *really* unconvinced by this paper......

    What the paper is saying is that they've been doing all these studies that say that the fine structure constant is changing with time. O.K. Then they take a dataset from a different telescope pointing in a different direction and they find that the fine structure constant is changing in a *different* way. So the explanation they come up with is that the fine structure constant changes with direction, but it seems more likely to me that there is a calibration issue.

    Something that would be interesting is to try to do the analysis of the same object with different telescopes and see if you get the same result.

    Also, something else to look at would be systemic differences in things like deuterium abundance with respect to angle. If you looked in different parts of the sky, and saw different elemental abundances that match the differences in the fine structure constant, then there might be something there.
     
  4. Also, finding a cosmological dipole dependency is really problematic from a theory point of view. If you look at the CBM, you do see a dipole variation, but that's the result of the earth's moving.

    You can see the problems if you assume that there really *is* a dipole variation in the fine structure constant. OK, you observe a dipole variation from earth. Let's assume its real. Now ask yourself what it's going to look like from a point that's 10 billion light years in some given direction of earth. Something that looks like a dipole from Earth is not going to look like a dipole from a different part of the universe, so you have to explain why earth is somehow special.

    Also if you think of the time evolution of the fine structure constant, you run into a lot of problems. If the results were real, that would suggest that you have the universe start off with different fine structure constant values in different parts of the universe, and then magically everything converges as you are getting closer to the current time.

    This gets you to the horizon problem. How do different parts of the universe that aren't casually connected manage to coordinate their fine structure constants?
     
  5. many people dont know that the fine structure constant is simply the speed of the electron in a bohr atom expressed as a fraction of the speed of light.
     
  6. This actually seems to be a hot topic at the moment, on account of recent new data.

    [arXiv blog]

    This is certainly a legitimate area of physics, and is frequently published in peer-reviewed journals. It may be controversial, but it isn't crack-pottery.
     
  7. There is crack pot stuff published in astrophysics journals all the time. At least in astrophysics, the publication philosophy is to err on the side of letting nutty stuff in.
     
  8. Chronos

    Chronos 9,856
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    I object to that paper because of 'cherry picking'. They select a tiny, skewed data set and attempt to assert 'statistically valid' conclusions. [Oh, the stories I could tell you about that] But, I have no problem with allowing papers like this to be published. It's fun, and who knows - they might be on to something. But I second quaint's sentiments. Journal papers are not gospel. If this paper is seminal and well received, it should get many cites.
     
    Last edited: Sep 2, 2010
  9. I think it's a pretty desperate reaction to the data they are getting. They've been trying for the last several years to show that there is some time variation in the fine structure constant. They then use another telescope, and the results from that other telescope show that the fine structure constant evolves in a different direction.

    The obvious result is that there is some observational error that they aren't taking into account. But they pretty then desperately come up with a model that says that the direction of the fine structure constant varies with direction. The problem is that the fact that they get this nice dipole variation very strongly suggests to me that they are seeing something but it's *not* the variation of the fine structure constant.

    Basically, if the fine structure constant is varying with direction then this doesn't work with an isotropic universe (i.e. it means that the universe has a preferred direction). That's fine, but then you should see something *other* than the fine structure constant vary.

    Things are often worse in the social sciences.

    One reason I tend to be polite about this is that 1) I don't want to look like an total fool if it turns out that the fine structure constant is changing 2) I want them to be nice to me if I do a major *whoops* and 3) they have real data.
     
  10. Curiously I don't have that much respect for peer review, and I don't care much for the idea that peer-review=good and non-peer-reviewed=bad.

    Part of this is because I've seen what peer review looks like in some other fields (finance, economics, and management) and in those areas I'd consider the peer review system to be seriously dysfunctional, and basically worthless as anything other than a political game.

    One reason that I don't think that astrophysics suffers from the dysfunctions that you see in economics is that astrophysics publication is a lot more "crackpot friendly."
     
  11. bcrowell

    bcrowell 5,683
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    I agree with you that it's almost certainly bogus. However, I don't think arguments about anisotropy and the horizon problem add that much to the evidence of bogosity.

    It's true that a dipole would be strange for the reasons you stated, but the whole effect probably doesn't exist in the first place. If it does exist, it's barely significant compared to random and systematic errors, and therefore any attempt to map variation across the celestial sphere is going to be extremely iffy. Since the significance of the whole effect is crap, their claim that it has the specific form of a dipole shouldn't be taken seriously.

    Anisotropy in the laws of physics would be revolutionary, and presumably would have shown up already in laboratory tests of Lorentz invariance. But anisotropy of the physical state of the universe is known to exist at some level; isotropy is just an assumption we make for convenience in constructing models. If the fine-structure constant varies, then it's just one more dynamical field like the electromagnetic field or the gravitational field. If there's a horizon problem for this new dynamical field, then it's no more of a horizon problem than the one that exists for all the other fields. It's true that you'd think that spatial variation of the field would be correlated with something else observable, but to me that's not such a significant issue compared to the fact that the whole thing is a crock.
     
  12. One thing that is something that is very useful from a teaching point of view is to compare the paper that says that fine structure constant is changing from the paper that first claimed that the expansion of the universe is accelerating, which is an equally extraordinary claim.

    The reaction I had when I first read the paper was similar to that of a lot of people. This is a nutty idea. It's obvious that what they are seeing is because of ..... Oh wait, on page such and such they should it can't be this. Well then, it must be because of .... Oh wait, they thought of that too .... Well if the universe really is accelerating, then you should see X, and we don't and so..... Oh wait, we actually do see X....

    What the authors of the accelerating universe paper did was to start out with 'odd observations" and they obviously showed to lots of people that trying to come up with plausible explanations other than the accelerating universe, before they were able to convince themselves that this is what they were seeing.

    I'm coming at this from a theorist point of view. If there really is a anisotropic variation in the fine structure constant then we ought to be able to see evidence of that in something totally unrelated. The problem with making claims from one set of observations is that you run the risk that there is some systematic bias that you don't know about. You can get around this by pulling in observations that are totally unrelated.

    To relating this to the accelerating universe. Yes, there *might* be something wrong with type Ia supernova observations, and yes it *might* be something that we haven't thought of. So in that situation, you try to come up with evidence that the universe is accelerating using observations that have nothing to do with supernova Ia observations (say CMB background variations).

    Now if the paper said, we looked at these quasar lines and they show some evidence of the fine structure constant changing, and we also looked at this other thing (and the obvious thing for me is nuclear abundances) and it's also changing in the same places, then that would be interesting. As it is, my explanation for their observations is that there is some systemic bias that they haven't taken into account, and you can't refute that by listing all the possible biases, because a bias that you haven't thought about or that you don't know can still mess up your numbers.

    What you really want is something just totally independent that gives you the same results. If they were seeing evidence of fine structure constant change from X-ray observations it would make it more interesting.

    Also, I should point out that the reason for being careful with these things is that a lot of the big discoveries of science happen when people look for X but find Y.
     
  13. turbo

    turbo 7,366
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    And that is why blanket dismissals of observations are dangerous to good science. I don't know why the WMAP data took so blasted long to be released, but I have an idea that it was due to the unexpected anisotropy that "should not have" been observed. Checking and re-checking for systematic errors and brain-storming for possible sources of the observed anisotropy was most likely the cause of the delays in the release of the early data-sets.

    In this case, the observed anisotropy is very small, and it is observed in some of the oddest most distant outliers in the cosmos - quasars. It may very well due to unmodeled systematic errors or some statistical anomaly. In either case, it would be a good argument for follow-up observations. Cosmology is a mostly theoretical field, but it must explain observations if it is to be a true science (hearkening back to Michael Disney, here).
     
  14. It is. But coming up with premature theoretical explanations also is troublesome. If you look for X, you stop looking for Y. Also part of the job of an observationalist is to come up with observations that are so obviously discordant that you can't easily dismiss them.

    No it wasn't. They were just overwhelmed with data.
     
  15. Chronos

    Chronos 9,856
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    The WMAP dataset was not only huge, but, contaminated by artifacts due to instrument and software issues. It took time to subtract these errors from the final data release. Given NASA was besieged by funding shortfalls during this time the delay was inevitable, not conspiratorial.
     
  16. If the initial interpretation of the distances of quasars is seriously erroneous (in other words if their distances are very much closer than originally thought) what does that do to the model presented in the paper(s)? How could you alternatively interpret the anisotropy?
     
  17. turbo

    turbo 7,366
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    Even if the Arp-Burbidge crowd is right (intrinsic redshift), an observed anisotropy that varies with direction would still be a real head-scratcher.
     
  18. This is starting to sound very interesting and I suppose it's time to dig into the papers. One thing that might produce an anisotropy, that to my understanding is mathematically completely unparameterized starting from the Lorentz/Heavyside version of Maxwell's Equations and hence rippling up through the Lorentz Transformations and SR, is the velocity change relationship between EM fields and a sink.
     
  19. Can string theory accommodate fundamental constants varying in space/time, by allowing the underlying Calabi-Yau manifold to change shape? Or by a dilaton wave which messes up the physics wherever it goes?
     
  20. But what, exactly, is an "extraordinary claim"? The truth is that this is a subjective concept, i.e., if any
    specific claim is extraordinary or not is in the eye of the beholder. Even more subjective is the
    concept "extraordinary evidence". This is why the old saying "extraordinary claims need extraordinary
    evidence" is not part of the scientific method, but rather a way of dismissing results that do not fit well
    with mainstream theory. IMO, any talk about "extraordinary claims" and "extraordinary evidence" is
    just pseudo-scepticism that is frequently put forward when one has run out of scientific arguments.

    The claims of an accelerating universe versus a varying fine structure constant is a good example of
    this subjectivity. That is, first notice the fact that the accelerating universe is easy to model within
    mainstream theory without any change of the basic underlying theoretical framework. Second, notice
    that a varying fine structure constant, on the other hand, would violate the Einstein Equivalence
    Principle (EEP), and thus falsify one of the fundamental principles underlying modern gravitational
    theory. This is why, IMO, claims of an accelerating universe should be treated as far less
    extraordinary than claims of a varying fine structure constant. In other words, IMO, claims of an
    accelerating universe were never extraordinary, and neither were the evidence for it. On the other
    hand, IMO, claims of a varying fine structure constant are indeed extraordinary, and the evidence for
    it is weak. In other words, IMO, to claim that the claims of an accelerating universe and a varying fine
    structure constant are equally extraordinary, is an extraordinary claim!

    But some people obviously think every claim is extraordinary that does not agree 100% with the party line at any given time, and this proves my point.
     
  21. One thing that I saw with WMAP was "semi-conspiratorial."

    People working on WMAP were extremely tight-lipped about their data, so only a very small select group of people were allowed to touch the original data before general release. What this meant was that they weren't in a position to pull in more people and resources to get the analysis done quickly, because pulling in more people increased the chances that some of the results would have leaked out early. Personally, I don't think there was anything wrong with them doing this.

    This had to also do with funding because the people that had priority access to WMAP data were able to get priority access, because they were willing and able to put in the resources to make WMAP happen.

    There's also the general administrative problem with large projects is that if you state schedules in real time with real delays built in, you aren't going to get funding for them. One way around this involves using "business time" and "business money" which is different from "real time" and "real money."
     
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