“A manifestly artificial signal – even a message as boring as a set of prime numbers or the digits of pi – would convey the momentous message that intelligence wasn’t unique to the Earth and had evolved elsewhere. And it could take a very different form from us. Seemingly artificial signals could come from super-intelligent (though not necessarily conscious) computers, created by a race of alien beings that had already died.”
Even if intelligence were widespread in the cosmos, continues famed astronomer Lord Martin Rees in The Guardian, we may only ever recognize a small and atypical fraction of it. Some “brains” may package reality in a fashion that we can’t conceive. Others could be living contemplative lives, perhaps deep under some planetary ocean, doing nothing to reveal their presence. The only type of intelligence we could detect would be the (perhaps small) subset that used a technology attuned to our own parochial concepts. It makes sense to focus searches first on Earth-like planets orbiting long-lived stars. But science fiction authors remind us that there are more exotic alternatives.
The great philosopher Ludwig Wittgenstein famously said: “If a lion could speak, we couldn’t understand him.” Even if signals were being transmitted, we may not know how to decode them – just as an old-fashioned radio engineer familiar only with amplitude-modulation might have a hard time decoding modern digital communications.
But the culture gap with aliens need not be unbridgeable. After all, if the aliens had the technology to generate signals that we could detect, they would share with us an understanding of physics, maths and astronomy. They may come from planet Zog and have seven tentacles, but they would be made of similar atoms to us. They would, like us, trace their origins back to the big bang 13.7bn years ago. So we could develop a language that describes the things we have in common, and then move on to other subjects.
It makes sense to listen, rather than transmit. (Any two-way exchange would take decades, so there would be time to plan a measured response – and no scope for snappy repartee).
There are three reasons why an expanded search is timely. First, technical advances in electronics and signal processing allow much more sensitive searches. Second, we’ve now discovered some Earth-like planets that are obvious targets. And a third reason is that the advent of social media and citizen science would enable a global community of young and old to participate in this cosmic quest.