So many science fiction books, films and television series involve other life forms – often lots of of them – but what are the scientific chances that we are, or we are not, alone in this huge (and expanding) universe? Two of the greatest thinkers on this subject have been the Italian physicist Enrico Fermi and the American astrophysicist Frank Drake.<\/p>\n
The first of these men posed what is known as the Fermi paradox<\/a> which can be summarised as follows:<\/p>\n And yet, as Fermi noted, there has been no convincing evidence of other life forms, leading him to ask: “Where is everybody?”<\/p>\n The second of our thinkers devised what is known as the Drake equation<\/a>. This equation attempts to calculate the likelihood of life outside our planet using seven variables:<\/p>\n The first attempt to put figures into the Drake equation in 1961 resulted in the conclusion that there were probably between 1,000 and 100,000,000 civilisations in the Milky Way galaxy. But the most recent attempt to populate the variables in the equation in 2018 – by three philosophers at Oxford University – has come to a radically different conclusion.<\/p>\n If you want to read the Oxford paper of 19 pages, you can access it here<\/a>. If you want to read a layperson’s summary, you can go here<\/a>.<\/p>\n If you can’t be bothered to look at either analysis, I can tell you that the latest calculations suggest that, based upon the current state of astrobiological knowledge, there\u2019s a 53 to 99.6 per cent chance we are the only civilisation in this galaxy and a 39 to 85 per cent chance we are the only one in the observable universe.<\/p>\n\n
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