When you believe strongly in an idea, how do you shepherd it into being? As senior editor Trent Gilliss explains, sometimes it takes years of perseverance and framing.
Gates shares with us a scientist's rich, connected way of looking at the universe, and we've captured him in Twitter form.
The complete twitterscript of our interview with Lord Martin Rees.
Comments from two cosmologists and NASA's images from a refurbished Hubble.