Swirling聽patterns in the sky may聽be signs of black holes that survived the destruction of a universe before the big bang.
鈥淲hat we claim we鈥檙e seeing is the final remnant after a black hole has evaporated away in the previous aeon,鈥� says Roger Penrose, a mathematical physicist at the University of Oxford.
He is co-creator of a theory called conformal cyclic cosmology (CCC). It states that, rather than having started in the big bang, the universe infinitely cycles through periods of ballooning up and compressing back to a tiny point.
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This could let electromagnetic radiation pass unscathed from one aeon to the next. And Penrose and his colleagues see these remnants in the cosmic microwave background (CMB), the faint radiation that fills the universe.
Hawking points
They have named these spots in the sky Hawking points, after the late Stephen Hawking.
Hawking predicted that black holes should emit small amounts of electromagnetic radiation. We have never seen this Hawking radiation, but it should shrink black holes until they evaporate.
Penrose is saying that we may be able to see signs of Hawking radiation left over from a previous universe. 鈥淚 think he would have been delighted to see the actual effect he predicted in an observation,鈥� says Penrose.
These Hawking points pop up in a map created by BICEP2, a radio telescope at the South Pole, say Penrose and his colleagues. In 2014, BICEP2 found distinctive swirls of polarised light in the CMB. The BICEP2 team said these swirls, known as B-modes, were caused by gravitational waves from inflation 鈥� the universe鈥檚 growth spurt after the big bang.
Data from the Planck spacecraft later showed that the B-modes were probably created by interstellar dust, but Penrose and his colleagues have another explanation.
They noticed a point in the BICEP2 map surrounded by a ring of polarised light, indicating a vast temperature difference between the inner and outer part. They suggest these are magnetic fields from black holes in the previous aeon that have spewed Hawking radiation.
According to CCC, all the energy of an evaporating black hole would be compressed into one tiny point as the universe shrank before expanding again in a new aeon. We don鈥檛 see the Hawking points themselves in the data, Penrose says, because the CMB measurements only go back to 380,000 years after the big bang, but we do see the rings.
Penrose and his colleagues saw 20 of these areas of temperature increase in the BICEP2 maps. So far, they think one of those is from a Hawking point, but Penrose says simulations show four or five more that warrant investigation.
Bold claims
Other effects could mimic this signal, says Olivier Dore at NASA鈥檚 Jet Propulsion Laboratory in California. 鈥淚 love the fact that their cosmological model predicts specific signatures in the data,鈥� he聽says. 鈥淏ut I would need to see more details to be convinced by their claim, as it would certainly be very interesting.鈥�
Brian Keating at the University of California, San Diego, a member of the BICEP2 team, says the B-mode spot in question is likely to be due to the bending of light by massive objects in space. 鈥淭hey鈥檙e not interpreting our results the way that we do,鈥� he says. 鈥淏ut the photons don鈥檛 come with a sign that says, 鈥業 came from a black hole鈥� or 鈥業 came from a dust grain鈥�.鈥�
A bigger problem is that the BICEP2 team hasn鈥檛 released its raw data, so Penrose鈥檚 team is working from images. Each pixel averages data over very wide swathes of the cosmos, so it is difficult to make claims about a single point, says Keating.
Penrose and his team used maps of the CMB from the Planck space telescope to check that these points weren鈥檛 a fluke of the聽BICEP2 map. They also ran 4000 simulations of a developing universe and found that these anomalous points still arise.
鈥淭hat means they were probably caused not by chance, but by some physical phenomenon,鈥� says Daniel An at聽SUNY Maritime College in New York, one of Penrose鈥檚 colleagues. As CCC predicts the signals they see, perhaps the theory is correct, he says.
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This article appeared in print under the headline 鈥淎 glimpse of a previous universe鈥�
