{"id":61655,"date":"2022-08-01T01:00:35","date_gmt":"2022-08-01T05:00:35","guid":{"rendered":"https:\/\/quotulatiousness.ca\/blog\/?p=61655"},"modified":"2022-07-31T10:22:19","modified_gmt":"2022-07-31T14:22:19","slug":"qotd-fermis-paradox-and-the-great-filters","status":"publish","type":"post","link":"https:\/\/quotulatiousness.ca\/blog\/2022\/08\/01\/qotd-fermis-paradox-and-the-great-filters\/","title":{"rendered":"QotD: Fermi’s Paradox and the Great Filter(s)"},"content":{"rendered":"

\"\"<\/a>Though what he really said is open to doubt, the nuclear physicist Enrico Fermi<\/a> gave his name to a short and possibly final argument against the existence of intelligent life on other planets. There are 200 billion stars in our galaxy alone. 20 billion of these are like our own sun. Let us assume that one in five of these has planets \u2013 and we find new exoplanets<\/a> every year \u2013 and let us assume that one in a hundred of these one in five has one planet with liquid water: that gives us 40 million Earth-like planets. I will not carry on with the assumptions, but it seems reasonable that there should be around a hundred thousand other advanced civilisations in our galaxy alone.<\/p>\n

This being so, the “Fermi Paradox<\/a>” asks, where are they?<\/em> So many other civilisations \u2013 so many of them presumably older and more advanced than our own \u2013 and they have not visited us. Nor, after generations of scanning with radio telescopes, have we detected any unambiguous signals from them. Either intelligent life on other planets does not exist, or it is so rare and so far apart in time or distance or both, that we shall never find it.<\/p>\n

Writing in 2008, Nick Bostrom<\/a> of Oxford University takes the argument to conclusions that are either depressing or exhilarating. He proposes a set of Great Filters, each of which limits the emergence of intelligent and technologically-advanced life. The most obvious filters are in the past. We shall soon be able to estimate how many planets in our galaxy have liquid water. We still have do not know how life begins. Obviously, it began here. But we have never been able to create a self-replicating organic process in our laboratories. It may be very unusual. It may also be very unusual, once begun, for this process to evolve beyond the very simple. Then it may be very unusual for larger and more complex living structures to evolve, and hardest of all for anything to emerge with the right combination of mind and appendages to enable the birth of a technological civilisation.<\/p>\n

Or the Great Filter may be in the future. It may be that civilisations like our own are reasonably common \u2013 but that they invariably blow themselves up shortly after finding how to split the atom.<\/p>\n

Bostrop’s conclusion is to hope that, when we get there, we shall find that Mars is, and always has been, a sterile rock. Independent life of any kind on a neighbouring planet would suggest a universe teeming with life, and some probability of civilisations like our own. This being so, the lack of contact would put his Great Filter in the future, and would suggest that we are, on the balance of probabilities, heading for self-extinction. No life at all on Mars, now or in the past, would let him keep hoping that the Great Filter is in the past, and that we may have a splendid progress before us.<\/p>\n

Sean Gabb, “Do Flying Saucers Exist?”, Sean Gabb<\/em><\/a>, 2020-11-15.<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"

Though what he really said is open to doubt, the nuclear physicist Enrico Fermi gave his name to a short and possibly final argument against the existence of intelligent life on other planets. There are 200 billion stars in our galaxy alone. 20 billion of these are like our own sun. Let us assume that […]<\/p>\n","protected":false},"author":1,"featured_media":35193,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[41,44],"tags":[454,1468],"class_list":["post-61655","post","type-post","status-publish","format-standard","hentry","category-quotations","category-space-science","tag-astronomy","tag-seangabb"],"jetpack_featured_media_url":"https:\/\/quotulatiousness.ca\/blog\/wp-content\/uploads\/2016\/06\/favicon.png","jetpack_shortlink":"https:\/\/wp.me\/p2hpV6-g2r","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/posts\/61655","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/comments?post=61655"}],"version-history":[{"count":4,"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/posts\/61655\/revisions"}],"predecessor-version":[{"id":75395,"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/posts\/61655\/revisions\/75395"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/media\/35193"}],"wp:attachment":[{"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/media?parent=61655"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/categories?post=61655"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/quotulatiousness.ca\/blog\/wp-json\/wp\/v2\/tags?post=61655"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}