Correlated noise in the two LIGO gravitational-wave detectors may provide evidence that the universe is governed by conformal cyclic cosmology (CCC). That is the claim of Roger Penrose of the University of Oxford, who is proposing that the apparent noise is actually a real signal of gravitational waves generated by the decay of hypothetical dark-matter particles predicted by CCC.

Last month, physicists at the Niels Bohr Institute pointed out that some of the noise in the two LIGO detectors appears to be correlated – with a delay that corresponds to the time it takes for a gravitational wave to travel the more than 3000 km between the instruments.

Writing in a preprint on arXiv, Penrose argues that a significant amount of this noise could be a signal of astrophysical or cosmological origin – and specifically CCC.

Infinite aeons

First proposed over a decade ago by Penrose, CCC assumes that the universe consists of a succession of aeons. Each aeon begins with a big bang and proceeds into an unending future in which the universe expands at an accelerating rate. As this expansion becomes infinitely large, Penrose argues that it can be transformed back into the next big bang.

He says that a "reasonably robust implication of CCC" is that dark matter consists of particles called erebons – the name deriving from the Greek god of darkness Erebos. As dark matter goes, erebons are extremely heavy and have masses of about 10–5 g. This is roughly the Planck mass and on a par with a grain of sand and about 22 orders of magnitude heavier than a proton.

Near-instantaneous impulses

Penrose says that when an erebon decays, it deposits all its energy into a gravitational wave. While such waves have frequencies well above the detection capabilities of LIGO, their arrival at the detectors would be recorded as near-instantaneous impulses that could be mistaken for noise.