Sir Roger Penrose, from the 7th Edoardo Amaldi Conference on Gravitational Waves
On Friday evening, 13 July 2007, the British physicist, Sir Roger Penrose, gave a mind-expanding and mind-boggling talk at the Darling Harbour Convention Centre. The public lecture was part of the 7th Edoardo Amaldi Conference on Gravitational Waves and it involved the presentation of the Dirac Medal of the University of NSW to Sir Roger.
Until now the official answer to the question of what was there before the Big Bang was that we do not know and we will never know as time only began at the Big Bang. About two years ago Sir Roger thinks he may have found an answer that he presented to a fascinated audience in the Bayside Auditorium. Your humble blogger attended the lecture and attempts a brief summary below:
He started by stressing the importance of the second law of thermodynamics that states that disorder or entropy must always increase. For example, at the Big Bang the Universe began in a low entropy state as illustrated by studies of background radiation left over from shortly after that time, the cosmic microwave background. Since then entropy has always increased.
Sir Roger also mentioned the Weyl curvature. This is a property of space that leads to the bending of light rays from distant galaxies by ones in the foreground – usually referred to as gravitational lensing. His Weyl curvature hypothesis proposes that the Weyl curvature was zero at the big bang.
According to the new theory as the Universe expands all the particles of matter are collected into black holes. These destroy the information content of matter and hence reduce entropy. The black holes radiate Hawkins radiation and after a very very very long time disappear – for instance for a three million solar mass black hole like the one at the centre of the Milky Way the time is 10 to the power of 84 years. When all matter has disappeared and entropy has been reduced a new Big Bang can take place. Sir Roger calls this sequence of one universe being formed after the death of the previous one conformal cyclic cosmology.
There are observational consequences of the theory as the previous Universe may have left behind a faint subtle pattern in the cosmic microwave background. It is now up to observational cosmologists to search for that tell-tale pattern.