Ready for your mind to be blown? There are roughly 10,000,000,000,000,000,000,000,000 (Thats 10 septillian) stars in the observable universe. Which means that for every grain of sand on Earth, there are 10,000 stars out there. The science world isnt in total agreement about what percentage of those stars are sun-like (similar to our sun in size, temperature, and luminosity)—opinions typically range from 5% to 20%. Going with the most conservative side of that (5%), gives us 500 quintillion, or 500 billion billion sun-like stars. Theres also a debate over what percentage of those sun-like stars might be orbited by an Earth-like planet (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Some say its as high as 50%, but lets go with the more conservative 22% that came out of a recent PNAS study. That suggests that theres a potentially-habitable Earth-like planet orbiting at least 1% of the total stars in the universe—a total of 100 billion billion Earth-like planets. So there are 100 Earth-like planets for every grain of sand in the world. Think about that next time youre on the beach. Moving forward, we have no choice but to get completely speculative. Lets imagine that after billions of years in existence, 1% of Earth-like planets develop life (if thats true, every grain of sand would represent one planet with life on it). And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth. That would mean there were 10 quadrillion, or 10 million billion intelligent civilizations in the observable universe. Moving back to just our galaxy, and doing the same math on the lowest estimate for stars in the Milky Way alone (100 billion), wed estimate that there are 1 billion Earth-like planets and 100,000 intelligent civilizations in our galaxy alone. From: gizmodo/the-fermi-paradox-where-the-hell-are-the-other-earths-1580345495
Posted on: Mon, 02 Jun 2014 22:09:09 +0000
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