Not so empty after all

A recent study suggests that the giant blob of coldness billions of light-years away that has puzzled cosmologists probably isn’t a “supervoid” after all:

This blob of coldness is nearly 1 billion light-years across. Brrr

Since the 1960s, astronomers have been aware of the electromagnetic background radiation that pervades the Universe. Known as the Cosmic Microwave Background, this radiation is the oldest light in the Universe and what is left over from the Big Bang. By 2004, astronomers also became aware that a large region within the CMB appeared to be colder than its surroundings.

Known as the “CMB Cold Spot”, scientists have puzzled over this anomaly for years, with explanations ranging from a data artifact to it being caused by a supervoid. According to a new study conducted by a team of scientists from Durham University, the presence of a supervoid has been ruled out. This conclusion once again opens the door to more exotic explanations – like the existence of a parallel Universe! […]

For the sake of their study, the Durham team relied on data from the Anglo-Australian Telescope to conduct a survey where they measured the redshifts of 7,000 nearby galaxies.

Based on this high-fidelity dataset, the researchers found no evidence that the Cold Spot corresponded to a relative lack of galaxies. In other words, there was no indication that the region is a supervoid.

So what is it? From the press release:

Mackenzie commented: “The voids we have detected cannot explain the Cold Spot under standard cosmology. There is the possibility that some non-standard model could be proposed to link the two in the future but our data place powerful constraints on any attempt to do that.”

If there really is no supervoid that can explain the Cold Spot, simulations of the standard model of the universe give odds of 1 in 50 that the Cold Spot arose by chance.

Shanks added: “This means we can’t entirely rule out that the Spot is caused by an unlikely fluctuation explained by the standard model. But if that isn’t the answer, then there are more exotic explanations.

‘Perhaps the most exciting of these is that the Cold Spot was caused by a collision between our universe and another bubble universe. If further, more detailed, analysis of CMB data proves this to be the case then the Cold Spot might be taken as the first evidence for the multiverse – and billions of other universes may exist like our own.”

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