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

Ekpyrotic model and CMB observations?

  1. Feb 25, 2004 #1
    Hello folks,

    I'm new to this fine forum and wondered if anyone here knows which present or future spacecraft (perhaps even balloon borne mission?) are capable of discriminating the effects of the strongly blue shifted gravitational spectrum that should be evident in the CMB as the Ekpyrotic model predicts? What exactly are the signatures in the CMB? Microwave polarizations? Any info on the latest data in this area would be greatly appreciated.

  2. jcsd
  3. Feb 25, 2004 #2


    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    Hello branebrain, welcome from one of the rank-and-file,
    one or more of the PF Mentors will probably be saying hello
    and may respond to your question

    I can't reply specifically but I just happened across a
    new paper by Eric Linder that suggests the possibility of
    testing various models by their signature on the history
    of accelerated expansion.

    I started a thread about Linder's article
    and called the thread "different kinds of dark energy"

    He was comparing a "braneworld" hypothesis with a "cosmological constant" hypothesis and seeing if they predicted detectably different grow curves for the size of the universe. (His braneworld model may not be your ekpyrotic picture but could interest you all the same.)

    Can you provide a link to some article about how the ekpyrotic model would leave a signature effect on the CMB? It is interesting to know about proposed means for testing these various models.

    Linder's article is not about the CMB but about the supernova redshift-distance data, but in case you are interested in looking at it Linders is


    or its at that other thread.
    I dont know how branes get into it for Linder, but he is a well-known cosmologist and generally has something interesting to say.
    Last edited: Feb 25, 2004
  4. Feb 25, 2004 #3
    Hello marcus,

    Here are three links that may help regarding the stochastic gravitational background and its signature on the CMB:


    I'm enjoying your links regarding Type 1a supernova results and the constraints placed on Inflation and cyclic models.

  5. Feb 25, 2004 #4


    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    Your 3rd link is to the Caltech HTML version of Lineweaver's great article
    If you ever want PDF it is at
    your link is to page 19 of the PDF print-out
    section "6. The Status of Inflation"

    I'm a fan of Lineweaver

    there are more lineweaver links and other goodies
    at the "Reference Shelf" sticky

    (you may know all this and I may not be telling you anything"

    I looked at your first link

    Koury, Steinhardt, and Turok

    I cant figure out how soon anything will be testable from
    the CMB spectrum, regarding these different models.
    something to keep alert to, I guess, but not to expect results soon.
    sorry cant respond more cogently

    Nereid often knows things. Try to get her attention.
    Last edited: Feb 25, 2004
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Ekpyrotic model and CMB observations?
  1. CMB primer (Replies: 8)

  2. Anisotropy in the cmb (Replies: 2)