Monday, November 09, 2015 by Greg White
Astronomers have discovered the largest known structure in the universe. “Structure” is a bit of a misnomer, since “it” is devoid of physical properties. Rather, scientists have found the largest void, dubbed supervoid, to permeate the cosmos.
The supervoid stretches 1.8 billion light years across and is distinguished by its atypical vacancy. István Szapudi, who led the work at the University of Hawaii at Manoa, states that the supervoid is “the largest individual structure ever identified by humanity.”
The supervoid was discovered due to a targeted astronomical survey, which confirmed that nearly 10,000 galaxies were missing from the region. The researchers were intentionally looking for the void. They believed its existence could help explain why parts of the sky were observed to be unusually cool.
Cold Spot and the Big Bang Theory
According to The Guardian, “The so-called Cold Spot was discovered 10 years ago and has proved a sticking point for the best current models for how the universe evolved following the Big Bang.” In particular, according to the theory of inflation, space underwent a rapid expansion during the early universe, which explains the locked uniformity of the cosmic microwave background radiation. Cosmological models permit slight fluctuations in the background temperature but nothing as cold and large as the supervoid.
“The Cold Spot raised a lot of eyebrows. The real question was what was causing it and whether it was a challenge to orthodoxy,” Prof. Carlos Frenk, a cosmologist at the University of Durham, told sources.
The latest hypothesis to explain the Cold Spot suggests their exists a giant region of emptiness at the center of the supervoid that is depleting energy as photons travel through it.
This particular explanation could verify the existence of exotic physics, a mysterious, unverified branch of physics that suggests normal matter has “exotic” properties.
The supervoid isn’t actually devoid of stuff, as the name suggests. Galaxies are sprinkled throughout the region. What makes the supervoid “empty” is that it contains 20 percent less stuff than our neck of the woods. While this may dilute the impressiveness of the supervoid, scientist are saying that it is unprecedented in comparison to how the rest of the universe is distributed.
“This is the greatest supervoid ever discovered,” said András Kovács, a co-author at the Eötvös Loránd University in Budapest. “In combination of size and emptiness, our supervoid is still a very rare event. We can only expect a few supervoids this big in the observable universe.”
How nothingness sheds light on dark energy
The most recent study used the Hawaii’s Pan-STARRS1 (PS1) telescope located in Haleakala, Maui, and NASA’s Wide Field Survey Explorer (WISE) satellite, to count the number of galaxies in a region of space three billion light years away, which is relatively close by astronomical standards.
The survey verified that there was a spherical region of the sky that contained fewer galaxies centered on the cold spot.
While the survey helped verify the existence of the supervoid, it simply unlocked another mystery; namely, how on Earth did this massive void form in the first place? Even more paradoxical is the fact that the supervoid only accounted for a 10 percent dip in the Cold Spot’s temperature.
An empty patch would explain the Cold Spot and verify the existence of dark matter, a mysterious repulsive force that increases with distance. Assuming the universe is expanding, photons would lose energy as they travel across the super void, converting kinetic energy into negative gravitational potential energy.
In a static universe, photons would regain lost energy as they travel out of the void. In a rapidly expanding universe, however, the universe becomes diluted over time, which explains why the void has become shallower.
The conjunction of the Cold Spot and supervoid verify that the expansion of the universe is indeed accelerating. “This is independent evidence, in case anyone doubts it, for the existence of dark energy,” said Frenk.