Is the Universe Missing a Chunk of Matter?

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    Hole Universe
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Discussion Overview

The discussion revolves around the discovery of a large void in the universe, often referred to as a "hole," and its implications for cosmology, dark energy, and the cosmic microwave background (CMB) radiation. Participants explore various aspects of this observation, including its size, significance, and relation to existing cosmological models.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question whether the void represents a true absence of matter or is simply a region beyond observational limits.
  • There are discussions about the size of the void, with comparisons to previously known voids, such as the Southern Local Supervoid, and calculations suggesting it is significantly larger.
  • Some participants express skepticism about the implications of the void for dark energy, suggesting that the observations may not be compelling or that the sources of information are vague.
  • A participant mentions the probability of such a void existing in the Lambda Cold Dark Matter (LCDM) model, noting that it is considered rare based on current cosmological statistics.
  • There are references to the Sachs-Wolfe effect and how it relates to the observed cold spot in the CMB, with some arguing that this finding aligns with standard cosmological theories.
  • Some participants express curiosity about the void's depth and its potential relationship to other cosmic phenomena, such as the "warm spot" in the CMB.
  • Others propose that the void could be related to ongoing discussions about the "axis of evil" in cosmology and the work of specific researchers.
  • One participant emphasizes the need for further study to determine whether the void represents new physics or can be explained by existing theories.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the significance of the void, with multiple competing views regarding its implications for cosmology, dark energy, and the nature of the universe. Some express skepticism about the findings, while others support their relevance to standard cosmological models.

Contextual Notes

Limitations in the discussion include the dependence on observational data and the challenges of extrapolating findings from smaller voids to larger scales. There are also unresolved questions about the void's characteristics and its relationship to other cosmic structures.

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The inability to detect dark matter without visible light sources in the vicinity is not surprising. Is the void a 'pocket' of empty space, or a zone empty beyond observational limits? How large is this region compared to the observable universe at the same scale? What is it's CMB temperature? I'm not convinced this is a compelling observation.
 
Does the void means a part of the space where there's no matter, planets or stars? The source for this observation seems rather vague.
 
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Good find!
Here is an earlier paper about this
http://arxiv.org/abs/0704.0908

Your BBC article has new information. This article is a previous one by Rudnick who was quoted in the BBC article

In case anyone is interested here is the space.com piece on it as well
http://www.space.com/scienceastronomy/070823_huge_hole.html

I think this finding is consistent with standard cosmology. At least as Rudnick presents it, what it does is demonstrate the Sachs-Wolf effect and (more generally) the presence everywhere of dark energy---equivalently a small positive cosmological constant Lambda.

Light passing through clusters of galaxies picks up energy by the socalled Integrated Sachs Wolf mechanism
and that partly offsets the inevitable LOSS of energy due to expansion of distance, which lengthens wavelengths.
Because of expansion, light traveling over cosmological distance is getting COLDER on average, but by passing thru clusters of matter it picks up a little energy so it doesn't come off so cold. If it goes for a very long time without passing thru any crowds of galaxies----in this case the void is a billion lightyear across---then it reaches us unusually cold. They saw a cold spot on the CMB temperature map and figured that it might be due to a void, so they looked for the void and there it was.

I think it tends to confirm the standard picture----which not all the news does these days: there have been some surprises, like the MAGIC result about gammaray going different speeds (see the IACT thread)
https://www.physicsforums.com/showthread.php?t=181602
 
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I notice several articles mention that "voids" have been found before, but none this size. It's much bigger than normal. Nobody's mentioning how big is normal? How much "bigger than normal" is this? Twice as big? A thousand times?
 
Nevrmind; calculated it myself. Southern Local Supervoid; 158Mpc. 1 pc=3.26 ly. 158mpc=474,000,000 ly. The newly-found void is about twice the size of the SLS.

Is that right?
 
LURCH said:
Nevrmind; calculated it myself. Southern Local Supervoid; 158Mpc. 1 pc=3.26 ly. 158mpc=474,000,000 ly. The newly-found void is about twice the size of the SLS.

Is that right?

Lurch your arithmetic is at least as good as mine
and I like your detail knowledge in a number of areas :approve:
Looks right to me!
 
  • #10
Have to find the reference but I read somewhere that the probability for such a void in LCDM is under 10^-5. IIRC there is a recent work of Peebles about void distributions. Anyway, one should be careful inferring about cosmological models based on single observations.
 
  • #11
Yeah it does seem very vague, I was hoping someone else had heard more about it...
 
  • #12
I'm rather intrigued by this, as I know people who work on structure formation are quite busy thinking about this atm.

I don't think the full details have been made public yet, so we have to wait for the paper.
 
  • #14
Well, it is actually mentioned in the paper :rolleyes::

How likely is such a large underdense region in a concordance cosmology? Suppose there is only one such large underdense region in the whole volume up to z=1. The corresponding void frequency is then the ratio of the comoving volume of the void to the comoving volume of the Universe to z=1, which is roughly 3 × 10−5. Is this consistent with LCDM? Void statistics have been done for a number of optical galaxy surveys, as well as numerical structure formation simulations. Taking the most optimistic void statistics (filled dots in Fig. 9 of Hoyle & Vogeley, 2004) which can be approximated by log P = −(r/Mpc)/15, a 140 Mpc void would occur with a probability of 5 × 10−10, considerably more rare than our estimate for our Universe (3×10−5) based on the existence of the cold spot. One must keep in mind, however, that observational and numerical void probability studies are limited to rc  30 Mpc; it is not yet clear how these should be extrapolated to rc > 100 Mpc.

Therefore they conclude:
Voids this large currently seem improbable in the concordance cosmology,...
 
  • #15
It is http://arxiv.org/abs/0704.0908

Extragalactic Radio Sources and the WMAP Cold Spot
Authors: Lawrence Rudnick, Shea Brown, Liliya R. Williams
 
  • #16
Thanks for the link, Brad. The void appears to be explicable without invoking ATM physics. It is, however, an interesting observation that merits further study. The fundamental question is whether this an example of new physics, or an unforeseen interaction within the bounds of existing physics. I admittedly lean toward the unforeseen side of existing physics.
 
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  • #17
could this hole or void be paint in the picture of axis of evil (fimngers of god) story be present in the work where of Joào Magueijo. He is working on this am i wright ?..
 
  • #18
They have said how wide the void is.
I'm curious about how deep it goes or is there any data on this?
 
  • #19
emanaly
Astrnomers, have found a great cosmic nothingness which as I understood from the link below is considered as an evidence of dark energy.
http://news.bbc.co.uk/2/hi/science/nature/6962185.stm
Does the "cold spot" relate in any way (like in its geometry) to the previously discovered "warm spot" other than their size, and magnitude of deviation from mean CMB temperature? Can we tell if it or its surroundings are accelerating in expansion? What might be at the center of this void?
 
  • #20
this is hardly a 'hole'. it's just a large region deviod of matter. rare, I'm sure, but it is not a hole.
 

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