According to an article recently published on Nature’s website, there would not be any evidence of time before Big Bang.
The idea that something could have existed before our Universe came from Vahe Gurzadyan of Yerevan Physics Institute in Armenia and Roger Penrose of the University of Oxford, UK. In their opinion, circular ripples in the cosmic microwave background would be the signatures of black holes colliding in a previous cosmic ‘aeon’ that existed before our Universe.
Gurzadyan used seven years of data from the WMAP (Wilkinson Microwave Anisotropy Probe) experiment, and indeed observed these circular patterns, supposedly corresponding to black holes colliding before our Universe.
Uniformity
The idea of something existing before our Universe comes from the need to explain why the Universe is apparently so uniform. Today, this uniformity is explained by the inflation theory, describing an extremely fast expansion during a brief period of time, which would have happened just a fraction of second after the Big Bang.
However, Penrose thinks that this uniformity could have originated from before the Big Bang, from the end of a previous aeon, which itself was born from the end of a previous one. This would create an infinite cycle, with no beginning and no end.
Recently, three independent teams of researchers reproduced Gurzadyan’s analysis of the WMAP data and all agree with his observations. However, they do not agree with their possible origin.
Evidence
Gurzadyan, in his simulations, considered the microwave sky is isotropic, and that’s where the other teams do not agree. They ran simulations of the cosmic microwave background assuming the basic properties of the inflationary Universe, and were able to observe similar circular patterns, concluding that Gurzadyan and Penrose’s results do not provide any evidence for the cyclical model of the Universe.
Gurzadyan has since argued that Penrose’s model might fit the data even better than the standard cosmological model, but also said that these circles do not constitute evidence of Penrose’s model, but that these signatures carry properties predicted by his model.