Matteo Cantiello added Let_s_recap_we_are__.tex  about 9 years ago

Commit id: c65206060a2d4660905ef603331457b5ebf05eda

deletions | additions      

         

Let's recap: we are thinking creatures living on planet orbiting a pretty common star. Our home planet has been around for about 4.5 billion years, while the Universe has about 13.7 billion years. We just learned that there are some other 1~000~000~000~000~000~000~000 = $10^{21}$ planets potentially similar to the Earth in the cosmos, a number larger that the \href{http://www.npr.org/blogs/krulwich/2012/09/17/161096233/which-is-greater-the-number-of-sand-grains-on-earth-or-stars-in-the-sky}{ grains of sand} found in every beach and every desert on Earth.\textbf{ Are we alone?}