How would we recognise other life in the universe?

We’d detect ‘alien-made’ signals

Even if primitive life were ubiquitous, ‘advanced’ life may not be, as our emergence on Earth may have depended on many contingencies, such as the phases of glaciation, the planet’s tectonic history and the presence of the Moon. But Search for Extraterrestrial Intelligence (SETI) research is surely worthwhile.

We are searching for non-natural radio transmissions from nearby and distant stars, the plane of the Milky Way, the galactic centre and from nearby galaxies. But even if the search succeeded, it’s unlikely that the ‘signal’ would be a decodable message. A radio engineer familiar with amplitude modulation might have a hard time decoding modern wireless communications. Indeed, compression techniques aim to make the signal as close to noise as possible – insofar as a signal is predictable, there’s scope for more compression. Then again, many think ‘organic’ intelligence is a brief interlude before the machines take over, so if we were to detect life, it’s more likely that it would be inorganic.