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For many years our place in the universe was the subject of theologians and philosophers - not scientists.

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But in 1960 one man changed all that. Dr Frank Drake was one of the leading lights in the new science of Radio Astronomy when he did something that was not only revolutionary but could have cost him his career. Working at the National Radio Astronomy Observatory in Greenback in Virginia he pointed one of their brand new 2 5metre radio telescopes at a star called Tau Ceti 12 light years from earth.

His mission? To listen for signs of extra terrestrial intelligence – quite literally listening for ET talking.

Although project Ozma, as he called it, resulted in silence, it did result in one of the most seminal equations in the history of science - the Drake Equation.

Examining seven key elements necessary for extra terrestrial intelligence to exist from the formation of stars to the likely length a given intelligent civilisation may survive. When Frank and his colleagues entered the figures, the equation suggested there were a staggering 50,000 civilisations capable of communicating across the galaxy at this very moment.

But, in the 50 years of listening that has followed, not one single bleep has been heard from ET. So were Drake and his followers wrong? Is there no life form out there capable of communicating? No one is really sure as the search itself is so difficult. Drake's own calculations are that we’d have to scan the entire radio spectrum of 1,0000,000 stars to be sure of contact.

But what the equation and the search for life has done is focus science on some of the other questions about life in the universe – specifically biogenesis, the development of multi-cellular life and the development of intelligence itself.

The answers to those questions are increasingly suggesting that, far from being a one off, life may not only be common in the universe but, once started, will lead inevitably towards intelligent life.

To find out how the Drakes Equation has influenced scientists around the world, Bang Goes The Theory’s Dallas Campbell goes on a worldwide journey to meet the men and women who have dedicated their lives to focusing on different aspects of the equation – finding out, as he travels, just how the equation has changed our view of life the universe and our place within it.

More on the search for other life

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