Was There Really a Billion Lightyear-Wide Void in the Sky?

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SUMMARY

The discussion centers on the controversial claim of a billion lightyear-wide void in the sky, initially proposed by Rudnick et al. in 2007. Kendrick Smith and Dragan Huterer from Cambridge University challenge this notion, asserting that their analysis reveals regions of higher-than-average density within the supposed void. Their findings, which are set to be submitted to the Monthly Notices of the Royal Astronomical Society, have received endorsement from David Spergel, a prominent figure in cosmology. The debate continues, particularly regarding the existence of a "cold spot" in the NVSS radio survey, with ongoing research suggesting no significant evidence for such a phenomenon.

PREREQUISITES
  • Understanding of cosmological models, specifically LCDM (Lambda Cold Dark Matter).
  • Familiarity with statistical analysis methods in astrophysics.
  • Knowledge of the NVSS (NRAO VLA Sky Survey) and WMAP (Wilkinson Microwave Anisotropy Probe) data.
  • Awareness of academic publishing standards, particularly regarding arXiv submissions.
NEXT STEPS
  • Research the implications of Kendrick Smith and Dragan Huterer's findings on the LCDM model.
  • Study the methodologies used in the NVSS and WMAP surveys for a deeper understanding of cosmic voids.
  • Examine the statistical significance of cold and hot spots in cosmology, referencing the Sloan Digital Sky Survey.
  • Explore the academic publishing process, particularly the protocols for submitting to journals like Nature.
USEFUL FOR

Astronomers, astrophysicists, and researchers in cosmology interested in the analysis of cosmic structures and the ongoing debates surrounding voids and cold spots in the universe.

marcus
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http://www.eurekalert.org/pub_releases/2008-05/ns-hhi051408.php

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 :biggrin:
 
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Here is the said paper:

http://arxiv.org/abs/0805.2751

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.
 
I agree, cristo. A lengthy stream of random numbers will inevitably produce statistically improbable sequences. The 'a posteriori' objection is well founded.
 
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Looks like this issue isn't resolved yet, have a look at http://arxiv.org/abs/0805.2974" 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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