Credit: Bill Watterson, “The Complete Calvin and Hobbes”
There are many Earth-like planets. Most Earth-like of all (so far), Kepler 452b, was discovered just a few days ago1. It is thought that there are 1 billion Earth-like planets in our galaxy, 100,000 of them with intelligent civilizations.
With so many intelligent civilizations, why haven't we heard from any of them? Some possibilities:
● there are many technically advanced civilizations out there, but they all subscribe to a Star Trek-like "prime directive" which prevents them from making contact with civilizations which haven't mastered space travel
● technologically advance civilizations obliterate themselves early in their history — as we seemed poised to do during the cold war — climate change — pollution
● we are the first — maybe there are many intelligent civilizations, but none more technically advanced than us
● intelligent life is uncommon
● technological, intelligent life is uncommon
● life itself is uncommon
More discussion at:
http://waitbutwhy.com/2014/05/fermi-paradox.html
http://listverse.com/2014/09/30/10-reasons-that-we-still-havent-found-aliens/
http://www.dailymail.co.uk/sciencetech/article-3112426/Where-aliens-Video-explores-paradox-haven-t-contact-civilisation-yet.html
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1 "Discovery of ‘Habitable’ Earth-Like Planet Announced", http://observer.com/2015/07/breaking-discovery-of-habitable-earth-like-planet-announced/ / starry place good starry night scale of the universe physicist Enrico Fermi where is everybody starry sky vast very local neighborhood 2,500 stars our galaxy less than 1,000 light years away 1% of the diameter of the Milky Way stars galaxies humans intelligent life out there stars galaxy 100 – 400 billion galaxies observable universe star colossal Milky Way galaxy every grain of sand on every beach on Earth 10,000 stars stars are sun-like similar in size temperature luminosity number of total stars 500 quintillion 500 billion billion sun-like stars orbited by Earth-like planet similar temperature conditions liquid water potentially support life similar to that on Earth recent PNAS study Proceedings of the National Academy of Sciences potentially-habitable Earth-like total stars in the universe 100 billion billion Earth-like planets beach after billions of years in existence Earth-like planets develop life life advances intelligent level Earth 10 quadrillion 10 million billion intelligent civilizations observable universe our galaxy lowest estimate stars in the Milky Way100 billion estimate 1 billion Earth-like planets 100,000 intelligent civilizations in our galaxy SETI Search for Extraterrestrial Intelligence listening for signals other intelligent life 100,000 or more intelligent civilizations our galaxy sending out radio waves laser beams attempting to contact others SETI’s satellite array signals our sun relatively young lifespan of the universe far older stars far older Earth-like planets civilizations far more advanced 4.54 billion-year-old Earth hypothetical 8 billion-year-old Planet X civilization technology knowledge civilization 1,000 years ahead of us civilization 1 million years ahead of us human culture chimpanzees Kardashev Scale intelligent civilizations amount of energy they use Type I Civilization Carl Sagan formula Type 0.7 Civilization Type II Civilization harness energy host star Type I brains Dyson Sphere Type III Civilization accessing power mastered inter-stellar travel colonizing galaxy hypothesis galactic colonization creating machinery travel to other planets self-replicating raw materials new planet replicas speed of light colonize colonize speculate intelligent life survives galaxy-colonizing Fermi Paradox Fermi Paradox scientists humans possible explanations Fermi Paradox higher civilizations no higher civilizations in existence non-exclusivity problem higher civilizations contact with us exception to the rule become aware of their existence Group 1 explanations no super-advanced civilizations mathematics math our own galaxy The Great Filter The Great Filter theory pre-life to Type III intelligence long evolutionary process The Great Filter timeline where The Great Filter We’re rare, we’re first, or we’re fucked We’re Rare The Great Filter is Behind Us hope we have we managed to surpass it extremely rare life our level of intelligence no Type III Civilizations few exceptions Earth is the center of the universe we’re special scientists observation selection effect pondering their own rarity is inherently part of an intelligent life success story rare or quite common being special which step it might be incredibly unusual for life to begin at all tried replicate The Great Filter intelligent life there may be no other life at all jump from the simple prokaryote cell complex eukaryote cell prokaryotes evolutionary jump being complex having a nucleus The Great Filter universe is teeming with simple prokaryote cells almost nothing beyond that other possibilities most recent leap we’ve made our current intelligence semi-intelligent life chimps intelligent life humans miraculous step inevitable climb upward evolution evolution does not strive for a goal Earth technological intelligence natural selection rare evolution tree of life because it has occurred as many as fossilized eukaryote Mars Rare Earth Hypothesis, Universe Big Bang intelligent life develop gamma-ray bursts astrobiological phase transition future search extraterrestrial intelligence /
