Nextbigfuture | Feb 22, 2018 | ~ Interstellar travel and biosphere reboots means there are a lot of aliens in the galaxy ~ | Blogger: Excerpts: ".. In 1961, radio astronomer Frank Drake developed a pedagogy for analyzing the question of the frequency of extraterrestrial civilizations. Robert Zubrin shows a couple of significant mistaken assumptions by Drake. Robert Zubrin wrote this for Centauri Dreams. ..(..).. Estimating the Galactic Population. There are 400 billion stars in our galaxy, and about 10 percent of them are good G and K type stars which are not part of multiple stellar systems. Almost all of these probably have planets, and it’s a fair guess that 10 percent of these planetary systems feature a world with an active biosphere, probably half of which have been living and evolving for as long as the Earth. That leaves us with two billion active, well-developed biospheres filled with complex plants and animals, capable of generating technological species on time scales of somewhere between 10 and 40 million years. As a middle value, let’s choose 20 million years as the “regeneration time” tr .. " |
