An interview with Sir Roger Penrose

British scientist Sir Roger Penrose was announced today as winner of the 2020 Nobel Prize in Physics, along with Reinhard Genzel and Andrea Ghez, for their work in seeking to understand black holes.

Sir Roger, of the University of Oxford, has long been famed for his ability to “think outside the box” and to come up with new ideas about the nature of the cosmos.

In 2010, Skymania’s Paul Sutherland interviewed Sir Roger to discover his thoughts about the origin of our Universe. He had just published a new book, Cycles of Time. Conventionally, the Big Bang is seen as the moment space and time began. But Sir Roger had been imagining a different scenario.

What came before the Big Bang?

By Sir Roger Penrose

Our conventional idea of the history of the universe starts with the Big Bang after which the universe expands in an accelerating way.

The second law of thermodynamics tells us, roughly speaking, that randomness is increasing all the time, something we call entropy. If you go back in time this should mean that randomness decreases so that in the very beginning you should find a highly organised state.

But what we find back at the beginning is the Big Bang, an explosion as chaotic as you can imagine. What more or less killed the model of a steady-state universe was the discovery of microwave radiation coming from all directions in space which can be interpreted as the flash of the Big Bang which has been cooled down by the expansion of the universe.

An image from a NASA animation visualising the conventional view of the Big Bang. See the animation here. Image credit: NASA’s Goddard Space Flight Center/CI Lab

I used to hold the standard view that the Big Bang was a singularity which means that the very question of anything happening before it is meaningless. But evidence shows the Big Bang was not just a walloping explosion but a completely random walloping explosion.

This paradox is almost unaddressed by cosmologists. They all know of it but don’t worry about it for some reason. I always thought this was a great puzzle. Why do we see this apparently random initial state when we know it should be the most organised state we’ve seen in the universe?

So I thought, let’s suppose there was something before the Big Bang. And in my new book, I’m suggesting that the Big Bang is the remote future of a previous aeon.

This is real physics, not just hypothetical mathematics. There was a universe, or an aeon let’s say, and a cycle of time with one aeon followed by the next aeon. The remote future of each aeon is followed by the Big Bang of the next.

It could be an infinite sequence of Big Bangs. I’m not making any claims for that but the picture I have at the moment is that it is really an infinite sequence. So there is no beginning and it is like the Steady State in that respect.

This theory is quite different to the idea of parallel universes. I’m not a fan of the multiverse model but the two ideas could exist together.

My model for a succession of universes can be tested observationally. Let’s suppose the previous aeon is like ours. You will have galaxies formed, clusters of galaxies in which are found large black holes. The clusters will hang together even though the universe expands and individual galaxies will collide, their black holes will swallow each other up until we are left with one big black hole that will sit there for an awful long time – think in terms of 10 to the power of 100 years, or a googol – slowly evaporating.

But each time those black holes collide and swallow each other up there is a huge burst of gravitational waves, the ripples in space time that are the gravitational analogue of light.

Gravitational waves have not yet been observed * – detectors are not sensitive enough – but we know they are there. The dynamics of neutron stars when they go round each other can only be explained by their presence. I’m saying that the huge encounters between these enormous black holes in galactic centres will produce waves which, if they are in the previous aeon, will influence our aeon. (* Gravitational waves were subsequently detected for the first time in 2015 from the merger of two black holes.)

We will, in principle, be able to see these events as slightly warmer or cooler irregularities in the cosmic microwave background. I want to encourage people to look for them!

I talk to other cosmologists about my theory and they nod their heads and say it sounds interesting. I can’t see any theoretical reason against it apart from the fact it is a crazy idea. But maybe a crazy idea is what we need!


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