That little circle is the largest thing in the universe.
The largest known structure in the universe? A huge
empty hole.
The “supervoid”, as it is known, is a spherical blob 1.8 billion light years across that is distinguished by its unusual emptiness. [...]
Its existence only emerged thanks to a targeted astronomical survey, which confirmed that around 10,000 galaxies were “missing” from the part of the sky it sits in.
That's a lot to have gone "missing." The "spot" in our known universe was discovered 10 years ago. Since then it has been a flash point in existing theories on the universe's creation.
Prof Carlos Frenk, a cosmologist at the University of Durham, said: “The Cold Spot raised a lot of eyebrows. The real question was what was causing it and whether it was a challenge to orthodoxy.”
Though this
survey doesn't answer the "cold spot" issue, it is quite a
thing to think about.
The structure may sound unremarkable – hardly a standalone object even – but scientists say it is unprecedented given how evenly distributed the universe normally is at this spatial scale. “This is the greatest supervoid ever discovered,” Kovács said. “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.”
The Cold Spot, as the
Royal Astronomical Society explains, may have far reaching implication in whether or not our universe is expanding at an accelerating rate.
Imagine there is a huge void with very little matter between you (the observer) and the CMB. Now think of the void as a hill. As the light enters the void, it must climb this hill. If the universe were not undergoing accelerating expansion, then the void would not evolve significantly, and light would descend the hill and regain the energy it lost as it exits the void. But with the accelerating expansion, the hill is measurably stretched as the light is traveling over it. By the time the light descends the hill, the hill has gotten flatter than when the light entered, so the light cannot pick up all the speed it lost upon entering the void. The light exits the void with less energy, and therefore at a longer wavelength, which corresponds to a colder temperature.
Exactly how I would have said it.