The universe is huge in time and in space and in contents. So the good thing about the universe is extraordinarily rare phenomena happen every day, someplace in the universe. And so, however rare we might calculate it would be up here for life as we know it, you multiply up the numbers—the stars in the galaxy, galaxies in the universe—these are staggeringly huge numbers. 10^21, a thousand times bigger than the number of grains of sand on an average beach, itself a hundred times bigger than the number of words ever spoken or uttered by all humans who have ever lived. These are staggeringly large—stupendously large numbers… that give us the confidence that even if intelligence life is only short-lived (grows up and then becomes so smart it can kill itself), that there’s bound to be one out there that we’re hitting it right at the right time that they are happy to have a conservation with us if we’re smart enough to have a conversation with them.
— Neil deGrasse Tyson