The Cold Spot is only about three billion light-years away from Earth, a relatively short distance in the cosmic scheme of things.
Scientists now believe trillions of universes may exist – the multiverse theory CREDIT: RICHARDDAWKINS.NET
The whole universe is covered in cosmic microwave background (CMB), a relic of the Big Bang which can be detected by telescopes on Earth. But while the temperature of most of the CMB is 2.73 degrees above absolute zero (or -270.43 degrees Celsius), the Cold Spot is about 0.00015 degrees colder than its surroundings.
Until the new research was published, most scientists thought the colder temperature in the space might be caused by a literal trick of the light.
They speculated that the colder area was actually a ‘supervoid’ which had 10,000 fewer galaxies and was so barren that it sucked energy out of light travelling through it, shifting its wavelength it to the red end of the spectrum, which telescopes mistook for coldness.
The 3-D galaxy distribution in the foreground of the Cold Spot (black points) compared to the galaxy distribution in an area with no background Cold Spot (red points). The number and size of low galaxy density regions in both areas are similar, making it hard to explain the existence of the Cold Spot by the presence of voids. CREDIT: DURHAM UNIVERSITY
But the Durham team found that the area actually is made up of clusters of smaller voids, all of which are too little to shift light enough for that explanation to work.
Doctoral student Ruari Mackenzie of Durham University added: “The voids we have detected cannot explain the Cold Spot.”
Prof Shanks said there had to be another explanation. “Perhaps the most exciting explanation is that the Cold Spot was caused by collision between our universe and another bubble universe, believe it or not.
“I remember some scientists suggesting that there could be detectable effects on the galaxy distribution after this ‘cosmic shunt’ of two universes colliding.
“Basically colliding universes could leave a slightly anisotropic galaxy distribution in our own universe – a bit like a pile-up on the motorway. So we can look for this to test how seriously to take these ideas.”
The results were published in Monthly Notices of the Royal Astronomical Society.