Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Arto Annila - Universe's expansion may be understood without dark energy

  1. Oct 24, 2011 #1
  2. jcsd
  3. Oct 24, 2011 #2


    User Avatar
    Science Advisor
    Gold Member

    This has been proposed before for a variety of reasons, but, dark energy is still considered the best fit to observational evidence to date.
  4. Oct 24, 2011 #3


    User Avatar
    Gold Member

    Looks like a terrible fit. At z=1, the least-action predicted bightness is ~2/5 of a mag low, which is 1.4x too bright. If I remember right, the observed brightness deviation (cf a matter-dominated Universe) is only ~1.5x at z=1.
  5. Oct 24, 2011 #4


    User Avatar
    Science Advisor

    If I understand correctly, he is also saying that gravitational lensing in underpredicted by 5X (p 2947). But we've measured the gravitational deflection of the sun, and there's no way we're off by 5X. Or am I missing something?
  6. Oct 25, 2011 #5


    User Avatar
    Science Advisor

    Indeed, it is an absolutely terrible fit. Note how the line is below almost all of the data points.
  7. Oct 26, 2011 #6
    As far as I can tell, he is proposing a "tired light" model which doesn't work for lots of reasons (look up wikipedia and google).

    Looking on his webpage, Arto Annila main expertise is in complex systems. He has no background in astrophysics and obviously has not read the wikipedia pages or done a google search on "tired light."

    If you cut out the section in which he talks about supernova, then the paper is actually rather interesting.
  8. Oct 26, 2011 #7
    Just FYI for why tired light models have problems.

    1) If you have light change speed, it's like going through a lens. If you go through a lens then there are a ton of effects that we don't see. In particular, if you are moving through a lens then things that are far away get blurry.

    2) More to the point if there is something that causes supernova light to go funny on the way to the earth, that whatever causes the light to go funny will also affect anything beyond the supernova. Which will result in all sorts of lensing effects.
  9. Oct 27, 2011 #8


    User Avatar
    Science Advisor
    Gold Member

    This is merely populist bull, IMO. IOW, I agree with twofish.
    Last edited: Oct 27, 2011
  10. Oct 27, 2011 #9
    How do (1) and (2) prove that light can't change speed?

    How do we know "anything beyond the supernova" is not affected?
  11. Oct 27, 2011 #10


    User Avatar
    Science Advisor

    Well, we know that the speed of light doesn't change to a high degree of accuracy. This doesn't necessarily mean it can't, but it certainly doesn't (at least not by any significant amount).

    Because when you have a change in the speed of light it impacts everything we see whose light was en-route to us before the change in speed. So, if there were changes that started to be detectable at, say, 1 billion light years, they would be even more apparent at 2 billion light years, and so on. But the speed of light is highly uniform all the way out to the CMB.
  12. Nov 11, 2011 #11


    User Avatar
    Science Advisor

    I posted this on another thread today, but it's relevant here, so ...

    I did a fit using his version of mu (Eq 4 in Mon. Not. R. Astron. Soc. 416, 2944–2948 (2011)) over linearized Union2 Compilation data (http://supernova.lbl.gov/Union/) and compared it to LCDM and the flat, dust-filled model (which is just LCDM minus Lambda). First, let me show you how his mu vs z looks compared to LCDM (Ho = 70, OmegaM = 0.3) when I use T = 14Gy in his mu (T is age of the universe, his only parameter, and in his Fig 3 caption he says he used T = 13.7Gy):

    http://users.etown.edu/s/stuckeym/Plot 14Gy.pdf [Broken]

    Red is LCDM, green is Annila. Now look at this same comparison using T = 15Gy:

    http://users.etown.edu/s/stuckeym/Plot 15Gy.pdf [Broken]

    Much improved, but he still could've given us some fit info. The 14Gy plot shows why his curve in his Fig 3

    http://users.etown.edu/s/stuckeym/Annila Figure 3.jpg

    is a little low at high z, since LCDM doesn't suffer that fate. Anyway, here is what I have for (mu/5 - 8) vs log(z) with Union2 data:

    Best fit line SSE = 1.95, R = .9955
    Best fit flat, dust-filled SSE = 2.68 using Ho = 60.9
    Best fit LCDM SSE = 1.79 using Ho = 69.2, OmegaM = 0.29, OmegaL = 0.71
    Best fit Annila SSE = 1.95 using T = 14.9Gy
    Annila SSE = 2.69 using T = 13.7Gy

    So, I think he would've been better served to show his fit using T = 14.9Gy rather than T = 13.7Gy. Anyone else run numbers? It would be nice to double check.
    Last edited by a moderator: May 5, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook