3 ms·

I am curious How did you get to this number ?

• jonknee 14y ago
  If there are 17 billion Earth sized planets out there and we're "one in a billion" that would mean there are 17 planets as perfect as ours that there is life. 17 - 1 = 16. The billion figure was just pulled out of thin air, "one in a X" is a common expression and for this purpose billion seemed appropriate. If we're actually only one in a million, we'll be busy meeting our new friends.
  • mistercow 14y ago
    >If we're actually only one in a million, we'll be busy meeting our new friends. The Milky Way is roughly a disk, so let's think in two dimensions, and for the sake of being reasonable, let's just talk orders of magnitude. The area of the Milky Way disc is on the order of 10^9 square light years. If there are 10^4 civilizations in the Milky Way, that means we should expect one other civilization within a 10^5 square light year neighborhood, meaning that we would expect the nearest civilization to be on the order of 100 light years from us. Over that distance, it would be plausible for two civilizations to transmit information to each other, but "conversations" would take generations. And that's if we ever managed to find them.