|May20-08, 03:50 PM||#1|
Big hole wasn't there, it seems
Last year Rudnick et al thought they saw a big hole in the sky, a billion lightyears wide.
It had some galaxies in it, they said, but significantly fewer than equalsize volumes in other parts of the sky.
That was around November 2007. There was some silly talk about it's being the "gateway to another universe", and it suited some people's "multiverse" ideas. The NewScientist had a coverstory about it.
Kendrick Smith at Cambridge says that the notion of a void probably resulted from inadequate statistical analysis. He and Dragan Huterer have found regions of higher-than-average density contained within the supposed "hole". They are getting a paper ready to submit to the Monthly Notices of RAS.
David Spergel at Princeton has given Smith and Huterer's work a nod of approval. Spergel is a WMAP chief and the lead author of many of the official WMAP reports. Authority and professional consensus do NOT ultimately decide scientific truth, right? But they can be useful straws in the wind. I'd guess this particular gateway to another universe is destined for the dump. If any corroboration turns up later, please tell me about it. Love to be wrong
|May20-08, 04:05 PM||#2|
Here is the said paper:
No evidence for the cold spot in the NVSS radio survey
Authors: Kendrick M. Smith, Dragan Huterer
(Submitted on 18 May 2008)
Abstract: We revisit recent claims that there is a "cold spot" in both number counts and brightness of radio sources in the NVSS survey, with location coincident with the previously detected cold spot in WMAP. Such matching cold spots would be difficult if not impossible to explain in the standard LCDM cosmological model. Contrary to the claim, we find no significant evidence for the radio cold spot, after including systematic effects in NVSS, and carefully accounting for the effect of a posteriori choices when assessing statistical significance.
|May21-08, 12:34 AM||#3|
I agree, cristo. A lengthy stream of random numbers will inevitably produce statistically improbable sequences. The 'a posteriori' objection is well founded.
|May21-08, 02:20 AM||#4|
Big hole wasn't there, it seems
Looks like this issue isn't resolved yet, have a look at this paper which has looked at a great number of hot and cold spots and their relationships to voids and clusters seen in the Sloan Digitial Sky Survey. They claim there is a highly significant correlation, for these spots in general, including the 'extreme Cold Spot' under question in this thread.
It doesn't say where the paper is submitted too, but looks to be in the Nature format. That would be odd though, since Nature doesn't permit you to post to arXiv before publication. In any case it's clear that this is a tricky question that may be debated for a while yet!
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