April marks the 50th anniversary of SETI, or the search for extraterrestrial intelligence. So what do we know today? Is there life in the cosmos, waiting to be found? Or is Earth the only harbour of life as we know it? And if life exists elsewhere, what about intelligence, technology and civilisation? Science journalist Wilson da Silva updates the Drake Equation, science’s attempt to determine the number of extraterrestrial civilisations out there today.