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A Universe without expansion

  1. Mar 28, 2013 #1

    Demystifier

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    Today a very unconventional cosmological model has been proposed:
    http://arxiv.org/abs/1303.6878

    Title: A Universe without expansion

    Abstract:
    We discuss a cosmological model where the universe shrinks rather than expands during the radiation and matter dominated periods. Instead, the Planck mass and all particle masses grow exponentially. Together with a preceding inflationary phase and a late dark energy dominated epoch this model is compatible with all observations. It has no big bang singularity. There exist other, equivalent choices of coordinates or field variables for which the universe shows the usual expansion or is static during the radiation or matter dominated epochs. Predictions of this model for primordial density fluctuations created during inflation concern a spectral index n=0.97 and a tensor to scalar ratio r=0.13.

    What do you think?
     
  2. jcsd
  3. Mar 28, 2013 #2

    marcus

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    Dearly Missed

    Just in time for April Fools :biggrin:
     
  4. Mar 28, 2013 #3

    Demystifier

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    It's not April yet. And the paper seems serious to me. :confused:
     
  5. Mar 28, 2013 #4
    seriously messed lol. reduced planch masses yeesh. The math may or may not work but I don't buy into his premise.
     
  6. Mar 28, 2013 #5

    cristo

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    It's definitely a serious paper, written by a reputable author. I've not read it, yet, so hesitate to comment, but it seems an interesting idea.
     
  7. Mar 28, 2013 #6

    Garth

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    This isn't a new idea.

    The question is, "How do we measure mass, length and time over cosmological distances?"

    What happens if our standard masses (the mass of a platinum atom), steel rulers and atomic clocks vary over cosmological distances and time scales?

    The point is that if they vary in a consistent way then there is no way of telling. If atomic particle masses vary as in a mass field theory such as in Fred Hoyle's 1975 attempt to explain the Cosmological Microwave Background in a Steady State or Static universe,
    http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1975ApJ...196..661H&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf [Broken] then atomic clocks would speed up and metal rulers would shrink.

    An expanding universe with fixed rulers is replaced by a static universe with shrinking rulers. There is no difference between the two equivalent representations.

    The conservation of energy-momentum in GR fixes atomic particle (rest) masses to be constant, however in the units of a conformal transformation of the GR metric this will not be so.

    You get the same idea of a static universe with shrinking rulers in the Jordan frame of http://en.wikipedia.org/wiki/Self_creation_cosmology [Broken].

     
    Last edited by a moderator: May 6, 2017
  8. Mar 28, 2013 #7

    Intrastellar

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    Is there an April fool conspiracy going on here ?
     
  9. Mar 28, 2013 #8
    As Garth says this is not new, the paper is serious but the model just trades the awkward singularity problem for the awkward and contrived "incredible shrinking masses and rulers". It doesn't explain anything better than the current model, it's just a worthless curiosity.
     
    Last edited: Mar 28, 2013
  10. Mar 28, 2013 #9
    Wouldn't it be possible to distinguish shrinking objects in static spacetime from objects not changing in size in an expanding spacetime through angular momentum measurements?
     
  11. Mar 30, 2013 #10

    Chronos

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    How do you get a shrinking universe and preserve a constant value for alpha?
     
  12. Mar 30, 2013 #11
    Lol thats a good question. Unfortunately I dont have an answer
     
  13. Mar 30, 2013 #12

    cepheid

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    If I understand correctly, that paper predicts a really large value for r...to the point that we almost ought to have detected it by now.
     
  14. Mar 18, 2015 #13
    If there is no Big Bang singularity, would that mean that the universe has been in existence for trillions and quadrillions of years, long enough for dark matter clouds to have collapsed into black holes?
     
  15. Mar 18, 2015 #14
    Relative to what? What ratio is changing?
     
  16. Mar 18, 2015 #15

    Drakkith

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    No, it does not. The model in question makes no changes to the age of the universe.
     
  17. Mar 18, 2015 #16
    I see. It still has a Big Bang, but no singularity. And it is static. And eternal.
     
    Last edited: Mar 18, 2015
  18. Mar 19, 2015 #17
    [/PLAIN] [Broken]
    http://www.dailygalaxy.com/my_weblo...n-alternate-theory-to-big-bang-cosmology.html
    "In Wetterich's alternative interpretation... the Big Bang stretches out in the past over an essentially infinite period of time."

    http://ic.galegroup.com/ic/scic/Ref...ityType=&scanId=&documentId=GALE|CV2643450887
    "It may be, he said, that the Big Bang about which scientists have written so much, might actually have been preceded by a very long history during which the universe consisted of a huge mass of very cold particles. In Wetterich's theory, it would then be impossible to suggest an age for the universe; it is simply something that has existed forever."
     
    Last edited by a moderator: May 7, 2017
  19. Mar 19, 2015 #18

    Drakkith

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    Hmm. Must have misread the paper then.
     
  20. Mar 19, 2015 #19

    Garth

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    The key is as I said in my post #6 above (now almost exactly two years ago - this is an old thread!)

    The important point in this recent discussion is the expanding universe with a finite age since the BB is replaced by a static universe of infinite age, again there is no physical difference between the two equivalent representations. It is all a matter of what standard masses and clocks you use to measure the universe.

    Garth
     
    Last edited by a moderator: May 7, 2017
  21. Mar 19, 2015 #20
    He seems to consider the inflationary period a "Big Bang", with no singular Big Bang preceding that.
    Given that infinite slowly accelerating expansion period, is there any need for Inflation? There was plenty of time for homogenizing.
     
  22. Mar 19, 2015 #21
    I'm trying to read it...
    So are they correct/coherent in saying their model is symmetric w/respect to the standard model? Does it still include singularity of infinite mass/energy zero scale etc? They seem to be claiming it is p1 para4, but then I also see they are claiming it is singularity free, and that that is not necessarily unusual these days.

    So are they just flipping it (like one of those eye tricks with angels and devils). Mass/energy is somehow a-priori but sort of without any recognizable meaning, but appears to grow and take on it's usual features as the volume containing it shrinks.

    This conversation piques my interest because I've long been confused by what seems like three similar but different descriptions of a big bang.
    • All the same mass/energy was always stuffed into the same changing "volume" - which leads to a really extreme situation if we wind back the change
    • The mass/energy was a-priori but then this "volume" came along and it (the mass/energy) got some (relative) power. But then where did the volume go, or where was it before? And what does that the a-priori mass/energy look like (if at all a coherent notion)
    • The "volume" was a-priori but then mass came along, and things got crowded and noisy. But then where did the mass come from? And what does that a-priori volume look like if anything
    • I suppose there is also the Penrose cyclical case, where the "volume" and mass/energy relation is like a single swinging pendulum
     
    Last edited: Mar 19, 2015
  23. Mar 19, 2015 #22

    Chronos

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    It's a matter of choice. The same observational consequences can be achieved either way. The question thus becomes which is simpler: expansion of empty space or an exquisitely fine tuned conspiracy between the other measurable properties of the universe? The simpler explanation is preferred absent evidence to the contrary.
     
  24. Mar 19, 2015 #23
    On side of my head gets what you mean by "simpler", but there is another side of my head that has no idea which one seems simpler, or rather is alarmed by the way that criterion gets invoked, even as it registers clearly in the first side of my head...

    Which brings back my headache about the difference between the expansion of space and the expansion of the phase space - of space.
     
    Last edited: Mar 19, 2015
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