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Consequences of a varying alpha

  1. Apr 12, 2005 #1
    First off I should mention physics is not my expertise and the class I am presenting this argument to knows not much more of physics than Newton's laws. Anyway, for this English class, we were supposed to pick a topic and write a well-constructed research paper, and of course I picked something I knew the instructor would be less likely to criticise being the humanities person that he is. The paper is due in a week or so and I have to give an oral summary of the paper, but as I've not finished the paper I would like to get some opinions on this (moot) discussion: What ramifications on physics might there be should the fine structure constant be found to vary slightly with time, as suggested by some experiments of absorption lines of far-away quasars? (see information presented by Webb et al here http://arxiv.org/PS_cache/astro-ph/pdf/0210/0210531.pdf )

    Here are some of the conclusions I have personally made, and some I used in my research discussed by Rich here http://scitation.aip.org/getpdf/ser...d=AJPIAS000071000010001043000001&idtype=cvips )

    Please tell me if the links don't work because my University subscribes to several services that I get automatically logged into. I tried to choose the most direct link possible. I would like criticisms on any conclusions you think I am unfounded in making:

    If alpha varies with respect to time

    1. Since alpha is a dimensionless quantity in all known dimensions, it must be affected by an unreferenced dimension, and that the time variation is just an indirect result of the variance in this unseen dimension (I'm told string theory allows for this sort of conclusion but I don't plan on mentioning that in the paper since I don't understand it at all)

    2. Since many fundamental constants with dimensions to them (G, c, etc) may be written in partial terms of alpha, these values would then be predicted to change with time.

    3. Going off of 2 and 1, relativistic equations, which make liberal use of planck's constant as well as c, are only approximations that fail to take into account the dimensions referred to in 1. An important consequence (that I take out of context a little) would be the violation of the Einstein Energy Principle without appropriate reform to the equation (the first part of which ZapperZ and Crosson pointed out in https://www.physicsforums.com/showthread.php?t=64313&highlight=light+variable
    )

    I think those three are the crux of what I had to say. The rest of the paper discusses a variation in standards used to measure alpha to explain a perceived change in alpha over time, such as a very slight deviation of the second or the meter, as well as the possibility of scientists jumping on bandwagons to confirm crazy theories and fudging results in order to agree with the temper of the times. Any criticisms would be greatly appreciated, even if they include "This is the most incorrect set of sentences I have ever laid eyes on". I understand most of what I'm trying to understand is way out of my league, but it's a learning process and I wouldn't want to pass on my misunderstandings to others.
     
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  3. Apr 12, 2005 #2

    rbj

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    it might not be a good idea to write a paper on something one knows little about because of a hope that readers or evaluators or critics might know less about it. could be embarrassing.

    there's also some data from the Oklo natural reactor that has suggested a very small movement in [tex] \alpha [/tex] over the billions of years.

    here are some other papers/links to look at

    http://www.arxiv.org/abs/hep-th/0208093
    http://xxx.lanl.gov/pdf/physics/0110060

    http://en.wikipedia.org/wiki/Fine-structure_constant
    http://en.wikipedia.org/wiki/Planck_units
    http://en.wikipedia.org/wiki/Variable_speed_of_light
    http://en.wikipedia.org/wiki/Talk:Variable_speed_of_light#candidate_for_deletion.3F.3F

    i couldn't read this since i am not a subscriber and i do not choose to pay.


    [tex] \alpha = \frac{e^2}{\hbar c 4 \pi \epsilon_0} [/tex] is a dimensionless quantity which means that the numerical value of it is independent of the system of physical units one would use to measure the dimensionful quantities that define [tex] \alpha [/tex]. what this means is that it doesn't matter whether you measure stuff using the SI system or the cgs system or the "English" system (that only americans seem to still use) or Planck units or some system that aliens on the planet Zog would use. [tex] \alpha [/tex] is still 1/137.03599911 or thereabouts.

    this differs from the dimensionful quantities in which we end up measuring or describing them in terms of some previously defined standards or units. the speed of light (and other E&M propagation) in a vacuum is 299792458 meters/second but it wouldn't be that number if we chose some other unit of length or unit of time. problem is that our choice of units are decidedly anthropocentric (Planck units is an important exception), so the numerical measure of these dimensionful quantities have little salient meaning.

    but [tex] \alpha [/tex] = 1/137.03599911 is different. the aliens on the planet Zog can measure it also and it comes out the same number for them. or if it didn't, that would really mean something because physics and their physical world would be somewhat different than it would be for us. but even if the physical speed of light was the same for them as for us, we could not know the difference in our communication with them (but we both could refer to the speed of light as a speed reference, presuming it to be the same). this makes [tex] \alpha [/tex] more of a fundamental universal value handed down by God, if that's something you want to believe. but, even for the agnostic, it is clearly an intriguing number that we think is the same everywhere and we know has profound effect on how things are in the universe.

    your language about "in all known dimensions" and "unreferenced dimension" is curious and i don't really know what you're talking about there.

    you should take a look at http://en.wikipedia.org/wiki/Fine-structure_constant to get an idea about fundamentally what [tex] \alpha [/tex] means physically. originally it was the ratio of the velocity of the electron of the Bohr model of the hydrogen atom in the lowest energy state to the speed of light. that affected the "fine-structure" splitting of spectral lines (about 1 1/2 angstrom splitting in a 6000 something angstrom wavelength line in the spectral decay of hydrogen) hence the name "fine-structure constant".

    later, probably the most fundamental meaning of the number is a measure of the strength of the electromagnetic force between charged particles relative to all of the other forces. if [tex] \alpha [/tex] increases, E&M increases proportionately relative to gravity, and to the weak and strong nuclear forces.

    one way i like to think about it is that one interpretation is that [tex] \alpha [/tex] is the square of the ratio of the electron charge to the Planck charge (sometimes considered to be the "natural unit of charge") which is [tex] \sqrt{ \hbar c 4 \pi \epsilon_0} [/tex]. if [tex] \alpha [/tex] increases, then all of the charged particles in the universe (assuming the value of [tex] \alpha [/tex] is universal) or in the vicinity controlled by this increasing [tex] \alpha [/tex], all of those charges (which are made up of electrons, protons, positrons, whatever) appear to increase by [tex] \sqrt{ \alpha } [/tex], thus increasing the electromagnetic force between them by [tex] \alpha [/tex] since that force is proportional to the product of their charges. that's one interpretation of what might happen.

    another interpretation is that some other dimensi


    [tex] G [/tex] is not a factor in [tex] \alpha [/tex]. but [tex] \hbar [/tex], [tex] c [/tex], [tex] \epsilon_0 [/tex], and [tex] e [/tex] are.

    Planck's Constant, [tex] \hbar [/tex], is the main scaling constant in Quantum Mechanics (incl. relativistic quantum mechanics) but is not used in the theory of relativity. [tex] c [/tex] is used in Special Relativity and both [tex] c [/tex] and [tex] G [/tex] go into General Relativity.

    that was a caveat of changing the speed of light, [tex] c [/tex]. i added that a more fundamental caveat was simply, we really can only measure, in our physical experiments or in our everyday perception and experience of reality, dimensionless numbers (such as [tex] \alpha [/tex]). if [tex] G [/tex] or [tex] \hbar [/tex] or [tex] c [/tex] or [tex] \epsilon_0 [/tex] changed, in and of themselves, we would not know the difference. that is the main point that Michael Duff is trying to make in the papers referenced above. and that point really is, essentially, a tautology which makes me wonder why a few folks (even big famous physicists) like to suggest that a variable speed of light is meaningful for any of us mortals. that's the main problem with that interpretation of a changing [tex] \alpha [/tex] (which would be meaningful in our existence).

    it's just that if [tex] \alpha [/tex] changes (say increases), we sense a change (an increase) in the electromagnetic interaction relative to other interactions (and that has other effects on dimensionless quantities, such as the fine-structure splitting) and i might say it appears that the charge of electrons and protons appear to have increased, someone else might say it's because [tex] c [/tex] or [tex] \hbar [/tex] has decreased, but neither of us is right over the other and it cannot be known who really is because, which component of [tex] \alpha [/tex] that has changed depends solely upon what system of physical units you choose to measure things, not on some absolute. to say that [tex] \alpha [/tex] changing must absolutely mean that [tex] c [/tex] has changed, is incorrect. we cannot know. all we know, if these measurements about Oklo and quasars are accurate, is the ratio [tex] \alpha = \frac{e^2}{\hbar c 4 \pi \epsilon_0} [/tex] is not what it used to be. (there is some degree of uncertainty that it is true. it might very well be that [tex] \alpha [/tex] remains constant. it would still be useful to know why it happened to take on the value that it does. one can appeal to the anthropic principle as a reason i.e. all the other universes with different [tex] \alpha 's [/tex] didn't survive or have the necessary order to create life such as ours to measure this and wonder why it takes on the value that it does.)

    i believe there has been that (i'll leave the names out). this is what Michael Duff has been reacting to, in his comments in the above cited papers.

    i want to do the former (learning process) and not the latter (pass on my misunderstandings to others), also. even if one is Albert Einstein, we are all lifelong students.

    r b-j
     
  4. Apr 12, 2005 #3
    It was a dryly-presented joke, sorry! I chose it because I was interested in it, not because the professor would be more likely to grade me easier because of lack of expertise in the area :)

    Sometimes my lack of language skills kind of gets in the way of what I'm trying to say. What I meant was is perhaps a dimension we don't know about yet may explain the slight deviation in value rather than time causing it (because no units of time are present in the constant). The closest idea I can come up with is say how would we begin to explain the distance between an object and a fixed point if that object's position changes over time? I would think if the object was moving at say a 45 degree angle with respect to some reference point, that without time we would determine the position in the y direction to be a function of the position in the x direction, when it could be better expressed as a function of time (which we aren't aware of). I'm not sure if that makes any sense

    Also, thanks for spelling everything out for me. I don't have time to respond to more right now but I have definitely made new considerations in light of what you said, Rbj, and changed somewhat what a plan to present.
     
  5. Apr 12, 2005 #4

    ZapperZ

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    If you intend to pursue this line for your essay (I tend to agree with rbj that this may not be the best topic for you to choose), then you should also include all the recent experimental results that challenge Webb et al. results. New results have put a very severe constraint to any possible variation in the fine structure constant, at levels even lower than what Webb et al. claimed to observe.

    Rather than repeat all the arguments and citations, I'll just refer you to a site where I've written all this....

    http://groups.yahoo.com/group/undernetphysics/message/1224

    Zz.
     
  6. Apr 13, 2005 #5

    ZapperZ

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    There appears to be a VERY recent development in this. Michael Murphy, an astrophysicist at Cambridge University, has just reported in the 11 April Physics2005 conference in Warwick, U.K that a more sensitive measurement of the quasars have "clearly" showed the shift in the fine structure constant over time. Supposedly, the new measurement is 10 times more sensitive than the atomic clock experiments that have contradicted his previous results. I'm guessing that publication of this work should appear within the year.

    So while this is still a controversial result, it appears to be a long way from settled. And that, folks, is the nature of physics at the research front edge.

    Zz.
     
  7. Apr 13, 2005 #6

    rbj

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    ... or the bleeding edge.

    thanks for the previous link, Z. if there is any online references to this recent Murphy thing, i would be interested in taking a look.

    even though i am strongly opinionated regarding the meaningfulness of changing dimensionful constants, i am agnostic about the changing dimensionless "constants". maybe some are changing very slowly, maybe not. it's just that if there is a change, that change has salient meaning and physicists can actually measure it. i just don't have much respect for the VSL or varying G theories.

    r b-j
     
  8. Apr 13, 2005 #7

    ZapperZ

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    So far, I haven't come across any other than the April 12th daily science report from Science webpage. So this was only reported.

    So we must be twins separated at birth! :) I share EXACTLY the same sentiments that you have on this. While I certainly won't rule out that they could be changing, I find that the evidence isn't there yet to make this even worth considering, especially considering the slew of experiments that have contradicted such things.

    Nevertheless, it is rather exciting to be following this saga, and for most people who aren't familiar with it, it shows how new ideas in science progress and goes through the painful birthing process.

    Zz.
     
  9. Apr 13, 2005 #8

    rbj

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    is there a link? i might like to read it.

    while i would have some skepticism about varying [itex] \alpha [/itex] or [itex] m_p / m_e [/itex] or some of these little dimensionless numbers in the Standard Model, i don't view they're changing as meaningless or necessarily impossible. we can measure these numbers repeatedly and they do change a little due to tightening experimental error ([itex] 1 / \alpha [/itex] used to be 137.03599976, now it's believed to be 137.03599911 which was a little outside the standard deviation of the previous value. but it's conceivable that these measures could change way outside of the error tolerances. that might mean something really has changed.

    but these guys hawking the VSL or changing G theories just don't seem to get it. changing c or G with respect to what?? that's the number (the ratio) to be watching. varying c or G or [itex] \hbar [/itex] all by itself has no meaning.

    r b-j
     
  10. Apr 13, 2005 #9

    ZapperZ

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    If you have a subscription (either personally or site-wide), or a registered user (I think registration is free), you can read the ScienceNow dailly report at the Science journal website:

    http://www.sciencemag.org/

    I think the J.K. Webb et al. claim of varying alpha is over time with respect to the current value. So alpha was different earlier in the period of our universe, and it has been increasing to its current value. I don't think this has anything to do with a more refined measurement.

    Zz.
     
  11. Apr 26, 2005 #10

    ZapperZ

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    Even MORE development on this thing that came out of the APS April Meeting.

    As reported on Apr. 21st in ScienceNow, the recent APS April Meeting produced ANOTHER report that contradicts the possibility of a variation in the fine-structure constant.

    Michael Murphy, who earlier made the "confirmation" in the variation of the fine-structure constant using observation from quasars, claim that the DEEP2 survey has a smaller precision than the quasar studies. However, the DEEP2 members believe that the galaxy studies are "... simple and robust enough that a bigger survey of galaxies can use it to settle the matter once and for all."

    Place your bets now... The windows are open!

    Zz.
     
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