Gravity is so strong that space is bent round onto itself, making it rather like the surface of the earth. If one keeps traveling in a certain direction on the surface of the earth, one never comes up against an impassable barrier or falls over the edge, but eventually comes back to where one started.
Stephen HawkingThe universe and the Laws of Physics seem to have been specifically designed for us. If any one of about 40 physical qualities had more than slightly different values, life as we know it could not exist: Either atoms would not be stable, or they wouldn't combine into molecules, or the stars wouldn't form heavier elements, or the universe would collapse before life could develop, and so on...
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