A team led by researchers at ETH Zurich’s Institute for Particle Physics and Astrophysics studied what insights can be gained from a ‘no life detected’ scenario in future exoplanet surveys.
What if humanity’s search for life on other planets returns no hits? A team of researchers led by Dr Daniel Angerhausen, a physicist in Professor Sascha Quanz’s Exoplanets and Habitability Group at ETH Zurich and a SETI Institute affiliate, tackled this question by considering what could be learned about life in the universe if future surveys detect no signs of life on other planets.
The study, which has just been published in The Astronomical Journal and was carried out within the framework of the Swiss National Centre of Competence in Research PlanetS, relies on a Bayesian statistical analysis to establish the minimum number of exoplanets that should be observed to obtain meaningful answers about the frequency of potentially inhabited worlds.
The study concludes that if scientists were to examine 40 to 80 exoplanets and find a “perfect” no-detection outcome, they could confidently conclude that fewer than 20 to 10% of similar planets harbour life. In the Milky Way, this 10% would correspond to about 10 billion potentially inhabited planets. This type of finding would enable researchers to put a meaningful upper limit on the prevalence of life in the universe, an estimate that has so far remained out of reach.
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