The Simonyi Professorship

This year's lecture ventures out into the cosmos for a mind-blowing hour with renowned science writer and Royal Society Letter SIR MARTIN REES.

A prolific astrophysicist, Sir Martin holds the honorary title of Astronomer Royal. His published titles on cosmology and otheer subjects include Before the Beginning, Just Six Numbers, Our Cosmic Habitat and Our Final Century.

The lecture will conclude with a question and answer opportunity, and will be followed by a book signing with Sir Martin.

Lecture summary

Sir Martin Rees, Astronomer Royal, gave the fifth annual Charles Simonyi lecture on Friday [7 November] on 'Mysteries of our Complex Cosmos'. The annual lecture series is in honour of Charles Simonyi, who endowed the Professorship for the Public Understanding of Science, currently held by Professor Richard Dawkins, who introduced Friday's lecture. The lecture is intended to contribute to the public understanding of science, and Sir Martin gave the audience an overview of the mysteries of the cosmos – and some of the possible answers to them.

Sir Martin began by discussing one of the first mysteries of the universe: the vastness of time and space compared to the scale of measurements our human brains have evolved to comprehend. 'Stars live so long compared to astronomers that we can only have a snapshot of each one's life. We are, though, able usefully to infer things about the life of stars,' he said. We can also see back in time: the light from distant stars take so long to reach us that what we see of them is an image from the past. Galaxies 10 billion light years away allow us to see 70% of the way back towards the Big Bang.

Sir Martin went on to discuss the question of what other solar systems like ours might exist in the universe. As stars die, they spin faster and faster, throwing out the elements which form planets and everything on them. 'We are stardust – or for the less romantic, the nuclear waste from stars.' Our solar system, then, should not be unusual, and Sir Martin explained that astonomers have already found giant planets like Jupiter orbiting 100 different stars. We do not yet have detailed enough detection techniques to detect smaller, Earth-like planets, but Sir Martin predicted that '20 years from now we will be studying other Earths around other stars.' As a result, 'the night sky will be far more interesting for the next generation of children' – as we look at a star we will know something of the size, and even topographies, of its planets.

The search for extra-terrestrial life on these other planets has long been a source of fascination for humans: in 1900, Sir Martin said, there was a competition in France with a prize of 100,000 francs for the first person to make contact with extra-terrestrials. Martians were excluded, because making contact with Mars was thought to be too easy.

Sir Martin emphasised in his lecture the difference between size and complexity. Stars are vast, but 'a star is much simpler than a butterfly'. He explained that one of the biggest mysteries is how, and why, the universe allows the level of complexity that we see in a butterfly, or in ourselves. Of all the algorithms that could have made up the laws of physics, few would have allowed such complexity. He gave the example of the Mandelbrot set, which is a short algorithm but creates infinitely complex structures, compared to other short algorithms, which produce simple and boring structures. In the same way that we might marvel at the chances that the Earth supports life, we might marvel at the chances that the laws of physics support such a complex universe.

One possible answer, which is currently purely speculative, is that there may be infinite universes – or several universes packed into the same space in such a way that we are unaware of them because of an extra dimension that we cannot perceive. In the same way that, with zillions of stars, it is not surprising to find at least one biofriendly planet, if there had been zillions of big bangs it would not be surprising to find at least one complex universe. 'This is not metaphysics, but science – albeit speculative science.'

Sir Martin also talked about the role of lectures such as the Simonyi lecture in advancing not only the public understanding of science, but scientists' own perception of their work. 'Through a narrow focus on bite-sized details, scientists can lose the broader picture,' and so all scientists should try to communicate the relevance of their work to non-specialists. 'To do so reminds us that our efforts are worthwhile only insofar as they serve to illuminate the whole picture.'