Cosmology: Lore of lonely regions

August 16, 2016, Ludwig Maximilian University of Munich
The simulation pictured shows the distribution of dark matter in our universe: The galaxies are not distributed uniformly, but rather along the edges of vast empty regions. These massive structures resemble a cosmic web, as Hamaus showed in a model in 2014, describing the density profile of cosmic voids. Credit: Nico Hamaus, LMU

A research group led by Ludwig-Maximilians-Unversitaet (LMU) in Munich physicist Nico Hamaus is calculating the dynamics of cosmic voids and deriving new insights into our entire universe.

Much of our is taken up by vast, hollow regions of empty space, which we call cosmic voids. They are forever expanding as the tiny amounts of matter they contain are striving to reach the outer edges, attracted by the gravity of the denser regions surrounding them. The large-scale universe therefore resembles a , with immense, vacuous bubbles surrounded by filaments of matter in which the galaxies are distributed. LMU physicist Dr. Nico Hamaus and colleagues analyzed data from the Sloan Digital Sky Survey (SDSS), in which scientists are mapping the structure of the universe through a telescope, and have computed the composition and geometry of the voids.

The researchers' analyses show how rapidly the voids are expanding. "By analyzing the cosmic voids, Nico Hamaus has succeeded for the first time in narrowing down cosmological models," says Professor Jochen Weller of the University Observatory of LMU. Hamaus has published his findings in the journal Physical Review Letters. His calculations demonstrate that the analysis of cosmic voids is a suitable approach to investigating gravity in the empty regions of the universe, and at the same time determining the total density of matter in the universe.

His study thus provides important clues to the question of why the universe is expanding at an increasing rate. So far, cosmology has proposed two possible answers to this: It could be due to the that makes up almost 70 percent of our universe, and which some believe exerts a kind of anti-gravitational force, or it could be that Einstein's General Theory of Relativity is only partly correct, and we need a new theory of gravity. "If there were any deviations from the General Theory of Relativity in the universe, those would be particularly prominent in cosmic voids. However, we detected no significant deviations in our analyses," says Hamaus. The results therefore corroborate the prevailing notion of gravity in the universe, which had never been tested on voids before, and so supports the assumption that there must be some form of dark energy that equates to a cosmological constant. "Our study shows that we can learn a lot more about the origin and evolution of our universe from analyzing cosmic voids."

Explore further: Much ado about nothing: Astronomers use empty space to study the universe

More information: Physical Review Letters, journals.aps.org/prl/accepted/ … 9e15eafa65551505cbae

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Reg Mundy
not rated yet Aug 16, 2016
the universe is expanding at an increasing rate. So far, cosmology has proposed two possible answers to this: It could be due to the dark energy that makes up almost 70 percent of our universe, and which some believe exerts a kind of anti-gravitational force, or it could be that Einstein's General Theory of Relativity is only partly correct, and we need a new theory of gravity.

So which is it? Dark Energy that is only theoretical and like Dark Matter has never been detected, or the theory of gravity is wrong?
My money is on the latter.....
malapropism
not rated yet Aug 17, 2016
@Reg Mundy
So which is it? Dark Energy that is only theoretical and like Dark Matter has never been detected, or the theory of gravity is wrong?
My money is on the latter.....

From the article above - '"If there were any deviations from the General Theory of Relativity in the universe, those would be particularly prominent in cosmic voids. However, we detected no significant deviations in our analyses," says Hamaus. The results therefore corroborate the prevailing notion of gravity in the universe...'
Reg Mundy
not rated yet Aug 17, 2016
@MrsMalaprop
@Reg Mundy
So which is it? Dark Energy that is only theoretical and like Dark Matter has never been detected, or the theory of gravity is wrong?
My money is on the latter.....

From the article above - '"If there were any deviations from the General Theory of Relativity in the universe, those would be particularly prominent in cosmic voids. However, we detected no significant deviations in our analyses," says Hamaus. The results therefore corroborate the prevailing notion of gravity in the universe...'

some believe exerts a kind of anti-gravitational force

Are you a believer?
malapropism
not rated yet Aug 17, 2016
@Reg Mundy
Two comments:
Are you a believer?

1. I *believe* in only a few things. Unproved science is not one of them. Religion is another.
@MrsMalaprop

2. Why, when I civilly responded to your first post in which you posed a question that I provided an answer to, would you then reply with something vaguely, and probably intended to be, insulting? Is there something wrong with you that makes you incapable of interacting within socially acceptable norms?
Reg Mundy
not rated yet Aug 18, 2016
@malapropism
Please accept my apologies if you thought my nickname for you was insulting. It was not intended to be, merely amusing, as Mrs. Malaprop is one of my favorite literary character inventions.
By the way, the reference to "belief" was an extract from the article, not my intro. As I understand from the article, either you "believe" in anti-gravity or you don't. So, instead of "believe", what do you think?
malapropism
not rated yet Aug 18, 2016
@Reg Mundy
Ok, thanks for the apology. I was unaware of the Mrs Malaprop character - after a quick Google, she sounds almost Wodehouse-ian. I guess I was hypersensitised due to the nature of some commenters' diatribes in these forums; sorry for that.

Like Agent Mulder, I would like to believe (in many things that would be desirable if they happened to be true) - I try to keep an open mind (except on the topic of religion, I admit) certainly anti-gravity would be nice to have as well as extremely useful however, similarly to FTL space travel and/or "hyperspace", it seems disappointingly unlikely. I suppose that if the recent theorising about a possible new 5th physical force, and an associated "dark sector", actually does come true then potentially all bets are off because that would represent a major aspect of the universe of which we've been totally unaware; who could tell what might be discovered resulting from it. In the meantime I remain something of a hopeful sceptic.
Reg Mundy
not rated yet Aug 19, 2016
@malapropism
Mmm...., indecisive, like most of us...
Unfortunately, the vast majority do not keep an open mind, as you try to do, and cling doggedly to disproven or unproven interpretations of how the universe works (which require Dark Matter, Dark Energy, etc., and offer no explanations for quantum entanglement, aberrations in the laws of gravity, etc.), but refuse to consider perfectly logical alternatives.
I have long had the opinion that we need a complete rethink of the basic tenets on which our current view of the universe is based, and have floated a few alternatives which have been rejected out of hand by the establishment accolytes without any effort to consider them seriously or, in many cases, without even bothering to read them cursorily before taking to phys.org and the like to dismiss them out of hand.
So, in the meantime, impasse, and I remain like you something of a hopeful sceptic.

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