The universe is vast and old, with billions of Sun-like stars and billions of years for life to arise — so by rights the galaxy should be humming with civilisations. Yet we see and hear nothing. That contradiction is the Fermi paradox, and this episode explores the unsettling gap between what we'd expect and the silence we actually find.

You'll come away understanding why the numbers suggest we shouldn't be alone, what the Drake equation really is, the leading explanations from the “Great Filter” to the possibility that we're simply early, and why honest scientists say we genuinely don't know.

Talking Science is sponsored by Kinsoft. Visit www.kinsoft.com.au

Further reading: SETI Institute – “The Drake Equation”; NASA Astrobiology – “Are we alone?”;  ...