Human-level intelligence is familiar in biological hardware – you’re using it now. Science and technology seem to be converging, from several directions, on the possibility of similar intelligence in non-biological systems. It is difficult to predict when this might happen, but most artificial intelligence (AI) specialists estimate that it is more likely than not within this century.

Freed of biological constraints, such as a brain that needs to fit through a human birth canal (and that runs on the power of a mere 20W lightbulb), non-biological machines might be much more intelligent than we are. What would this mean for us? The leading AI researcher Stuart Russell suggests that, for better or worse, it would be ‘the biggest event in human history’. Indeed, our choices in this century might have long-term consequences not only for our own planet, but for the galaxy at large, as the British Astronomer Royal Martin Rees has observed. The future of intelligence in the cosmos might depend on what we do right now, down here on Earth.