The article entitled “Astronomers Find Enormous Hole in the Universe” discusses the August 2007 discovery of the hole. It is located at the National Radio Astronomy Observatory website.
Dr. Laura Mersini-Houghton is a theoretical physicist and cosmologist at the University of North Carolina (Chapel Hill).
The hole is estimated to be almost one billion light-years across, where one light-year is about 9.5 trillion kilometers (5.9 trillion miles) and is located within the constellation Eridanus.
The Mersini-Houghton team states that the hole is another universe at the edge of our own universe. Such an explanation, if true, would be the first experimental evidence of such an exo-universe, or a universe outside of our own universe.
Several teams of astronomers have used data from the NASA Wilkinson Microwave Anisotropy Probe (WMAP) satellite and the Sloan Digital Sky Survey to make examinations of this large hole. The hole first showed up in images of the cosmic microwave background (CMB) radiation, the radiation left over from the formation of the universe (what we call the big bang).
In images made by WMAP back in 2004, the volume of the hole showed up as being of a colder temperature than surrounding volumes of space because of less energy being ejected from the region.
The hole is not actually devoid of matter, only has far fewer galaxies and galactic clusters than normally found in a comparable volume of space. It is estimated that the hole has about 20 to 45% less galaxies than normal, which contributes to it being colder than other volumes of space.
Not knowing how far away the hole was located astronomers then began looking at the Sloan data to make comparisons with galaxies. They found that the hole was about 900 million light-years across and about 8 billion light-years away. This hole is the largest one ever found, and is difficult to explain, with current models of the universe, as to why it exists. Standard cosmology theory says that such a large void in space is exceedingly unlikely.
Several teams have made claims at to the explanation for this hole. Some cosmologists say that large hole in space is a “topological defect,” a large knot in space.
The Mersini-Houghton team, however, says it is another universe at the edge of our own. They looked at string theory for the explanation. In string theory, 10500 universes (or string vacuums) are described, each with unique properties. They contend that the largeness of our universe is due to its vacuum counterbalancing gravity. This counter-gravity of the vacuum keeps our universe very large (rather than shrinking due to gravity)—larger than the other multitude of universes. The team says that smaller universes are positioned at the edge of our universe, and because of this interaction they are seen by us.
The team predicts that another giant void will eventually be found. The already found void is in the northern hemisphere. They contend another one will be found in the southern hemisphere.
Cosmologists are mixed as to the conclusions from the Mersini-Houghton team. Some call it very interesting, while others call it very speculative. Future tests will be made that will probably validate or reject their conclusion.
This article is based on the New Scientist article “The void: Imprint of another universe.” [subscription required]. It is a very interesting article and, if you have access to it, should provide you with some very thought-provoking reading.
[Author's Note: Yes, the reader is correct. There was a typographical error. I forgot to include "million" behind "900 light-years across." It should read "900 million light-years across". The mistake has been corrected.]