Ekpyrotic model and CMB observations?

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In summary, the article discusses possible signatures on the CMB that could be indicative of different models of dark energy. It is unclear when data from these models might be detectable, but it is worth keeping an eye out for.
  • #1
branebrain
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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.

bb
 
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  • #2
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
https://www.physicsforums.com/showthread.php?s=&threadid=15078
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

http://arxiv.org/abs/astro-ph/0402503

or its at that other thread.
I don't know how branes get into it for Linder, but he is a well-known cosmologist and generally has something interesting to say.
 
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  • #4
Your 3rd link is to the Caltech HTML version of Lineweaver's great article
If you ever want PDF it is at
http://arxiv.org/astro-ph/0305179 [Broken]
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 can't 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 can't respond more cogently

Nereid often knows things. Try to get her attention.
 
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1. What is the Ekpyrotic model?

The Ekpyrotic model is a cosmological theory that proposes the universe was created through the collision of two branes (higher-dimensional objects) in a pre-existing higher-dimensional space. This model suggests that the Big Bang was not the beginning of the universe, but rather a transition from a previous contracting phase.

2. How does the Ekpyrotic model explain the observed fluctuations in the cosmic microwave background (CMB)?

The Ekpyrotic model predicts that the collision of the two branes would have caused ripples in the fabric of space-time, resulting in density fluctuations that were imprinted on the CMB. These fluctuations are consistent with the observed patterns in the CMB, providing evidence for the Ekpyrotic model.

3. Can the Ekpyrotic model explain the existence of dark matter and dark energy?

Yes, the Ekpyrotic model proposes that dark matter and dark energy are actually a single substance called "dark radiation". This substance is created during the collision of the two branes and can account for the missing mass and energy in the universe.

4. What are the main criticisms of the Ekpyrotic model?

One of the main criticisms of the Ekpyrotic model is the lack of direct evidence for the existence of higher-dimensional branes. The model also faces challenges in explaining the observed isotropy and homogeneity of the universe, as well as the observed rate of expansion.

5. Are there any ongoing experiments or observations that can support or disprove the Ekpyrotic model?

Currently, there are no specific experiments or observations that can directly prove or disprove the Ekpyrotic model. However, ongoing studies of the CMB and other cosmological data may provide further insights and evidence for or against this model.

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