In his eyes shone the reflection of the most beautiful planet in the Universe---a planet that is not too hot and not too cold; that has liquid water on the surface and where the gravity is just right for human beings and the atmosphere is perfect for them to breathe; where there are mountains and deserts and oceans and islands and forests and trees and birds and plants and animals and insects and people---lots and lots of people. Where there is life. Some of it, possibly, intelligent.
Stephen HawkingIn the last 200 years the population of our planet has grown exponentially, at a rate of 1.9% per year. If it continued at this rate, with the population doubling every 40 years, by 2600 we would all be standing literally shoulder to shoulder.
Stephen Hawking