As the Cambridge Science Festival enters its final two days people will have an opportunity to consider the history of the universe and the future of the planet in public lectures given by leading Cambridge scientists.

The current model of the universe starts with a hot big bang about 14 billion years ago. But there are many puzzling questions about the big bang theory. Did time really "begin"? And will the future really be a cold, eternal void? Tonight (Friday 21 March) Professor Neil Turok, of the Department of Applied Mathematics and Theoretical Physics, will address these questions in a public lecture entitled The Search for the Complete Theory of the Cosmos.

The hour-long talk, which is the final lecture in Cambridge Science Festival's Spotlight on Science series, will take place in the Babbage Lecture Theatre on Cambridge University's New Museums Site at 7.30pm. The lecture is free and aimed at an audience of 14 years old and above.

The lecture will start with a review of recent satellite measurements, confirming theoretical predictions. They include the polarisation of the microwave sky, predicted a decade ago by Professor Turok and colleagues.

These observations have established a `standard model' for cosmology, in which a mysterious `dark energy' has recently come to dominate the density of the Universe and is driving an acceleration of its expansion.

Professor Turok has proposed a new theory, called the `cyclic Universe'. According to the theory, dark energy drives an eternal series of cycles, each consisting of a big bang followed by a period of activity. This, in turn, is followed by accelerating expansion, which `cleans up' the debris, restoring the Universe to a smooth, pristine state ready for the next bang.

It was a love for nature during an African childhood, and a passion for beetle-collecting in particular, that introduced Prof Turok to the excitement of science.

"When I first arrived at Cambridge, I intended to study mathematical biology and ecology," he says, "But the lure of fundamental physics, with its extraordinary precise predictions, proved too much to resist, and I was drawn to study particle physics, which was just beginning to be connected to the big bang theory."

Could we reorganise our lives to recycle or re-use everything we throw away? Microscopic sea creatures could help to dispose of carbon dioxide - but what is global warming doing to them? And how can we design eco-friendly buildings and cities for a green future?

These are some of the questions that researchers working at the Cambridge-MIT Institute (CMI) will be discussing in a series of talks being held tomorrow (Saturday 22 March) at the BP Institute, Madingley Rise.

Part of the final day of Cambridge Science Festival, the five lectures have been organised under the environmental banner Extremely Green. All are free and open to members of the public, including children aged 14 and over - or, in the case of the first talk, as young as eight.

CMI - which brings together researchers from Cambridge University and the Massachusetts Institute of Technology - hopes the event will show the public how its projects are developing sustainable energy technologies to meet targets for reduced greenhouse emissions.

The scientists contributing to the day will look at how we live - in terms of the air we breath, the packaging we throw away, and the buildings we inhabit - and make suggestions for radical solutions.

"We hope to show our audiences, particularly young people, that science can transform our world and the way we live," said Professor Harry Elderfield from the Department of Earth Sciences, one of the five speakers.

"In my talk, Greenhouse Gas and Acid Sea, I want to explain how, if we have a better understanding of the way nature moves carbon dioxide around our planet, it could help us find new ways of tackling the worrying levels of greenhouse gas."

The five talks are: Every Breath You Take, given by Prof Nick Collings, 10.30-11.30am (recommended for ages eight and over); Think No Waste, by Prof Peter Guthrie, 11.45am-12.45pm; Greenhouse Gas and Acid Sea, by Prof Harry Elderfield, 1-2pm; The Physics of Low Energy Buildings, by Prof Andrew Woods, 2.15-3.15pm; and Designing Cities for the Future, by Prof Marcial Enchenique, 3.30-4.30pm (all aimed at ages 14 and above).

Other highlights of the final Saturday include a Maths Public Open Day at the Centre for Mathematical Sciences (Wilberforce Road), where mathematicians working on everything from prime numbers to volcanoes are staging displays, interactive demonstrations and talks to illustrate the huge range of their work. And at Addenbrooke's visitors will have the chance to take a closer look at the human body with tours of the Magnetic Resonance Imaging facilities at the Herschel Smith Laboratories and the Wolfson Brain Imaging Centre.

Space for many events will be limited: please arrive early to avoid disappointment.

For more information on Cambridge Science Festival phone 01223 766766 or go to www.cambridgescience.org

Image courtesy of NASA

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