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Lyman Page new idea for CMB observations

  1. Jun 27, 2007 #1

    marcus

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    Lyman Page is a senior observational cosmologist who publishes in good company like with Charles Bennett, Joanna Dunkley, David Spergel and Ned Wright.
    He and an associate have a new idea about getting information from the CMB

    http://arxiv.org/abs/0706.3908

    to me it seems conceptually novel, and it is apt to be sound if you simply go by who it comes from
     
    Last edited: Jun 27, 2007
  2. jcsd
  3. Jun 27, 2007 #2
    I am slowly working my way through their paper.
    I integrated equation (1) and found the same result they did. c*tau = 14373 Mpc.
    What does conformal time/distance mean physically?
    Is that the same thing as the comoving radial distance?


    thanks
     
  4. Jun 28, 2007 #3

    marcus

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    a *pictorial* explanation of relation of comoving distance, conformal time, and other measures is in Figure 1 and some later figures in this paper

    http://arxiv.org/abs/astro-ph/0305179

    My guess is that you basically understand these terms and would benefit by having someone at the same level read the paper along with you----all grad students learn that it is more efficient to read papers together with other people than to read them solo.

    my problem is I'm pre-occupied with other stuff and cant get to Lyman Page paper right now

    I just know that he is a highly respectable guy and so this is probably an interesting OBSERVATIONAL astronomy proposal. and AFAICS it is obviously novel. so I figured somebody here at PF cosmology might be interested.

    I hope you can find a reading partner.
     
  5. Jun 29, 2007 #4

    Chronos

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    Conformal time is time as we perceive it. The opposing concept is universal time [time as god sees it].
     
  6. Jun 29, 2007 #5

    marcus

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    That is a different idea of conformal time than what I'm familiar with from the scientific literature in cosmology. We may have a semantic fracture and be running the risk of confusion
     
  7. Jun 29, 2007 #6

    marcus

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    If anyone wants to get an intuitive grasp of what mainstream cosmologists mean by conformal time just go to that Lineweaver 2003 article I mentioned and turn to page 6
    where there is Figure 1

    and look at the third diagram where the first two diagrams are re-plotted using conformal time on the time axis.

    conformal time is highly distorted and helps to make some things easier to study (like the LOG SCALE is a good way to plot data sometimes because you get straight lines and can see intersections easier)

    in conformal time CLOCKS RUN INCREDIBLY FAST AT THE BEGINNING and gradually slow down.

    So you can see that in conformal time THE EXPANDING UNIVERSE IS ALREADY 47 BILLION YEARS OLD because the clocks were running so fast in early days.

    my advice is study the picture in Lineweaver.

    and then he gives formulas (reference to Davis and Lineweaver), and so does Ned Wright. but the picture should come first.
     
    Last edited: Jun 29, 2007
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