Zero gravity conditions and the fish pond I get a lot of comments about the fish in the pond and the zero gravity conditions. Here's the physics: if there is only a pond and calm water nothing will happen, because you always need a force to change something in zero gravity. The cat Goldie is moving upward only because because of her movements (paws pushing downwards) which create a vertical force. In the scene I assumed that the carp are only creating horizontal forces, but admittedly that might be a bit unrealistic. In any case they would certainly send drops of water upward and it's possible that even a fish could come out floating depending on their direction of movement. Why does the spaceship Perennial use hydrogen (isotopes) as fuel instead of helium-3? Nuclear fusion based on helium-3 is certainly a better choice. The reason was not to complicate matters too much as helium-3 raises the question of mining it on the Moon or other planets in sufficient quantities. I thought that in 50 years' time speech-based interfaces would be commonplace. Why use keyboards? When people talk to an android this implies speech recognition, so my book reflects that. However, I doubt that the prediction of speech as the ubiquitous interface to computers will really come true. When you surf the Net it's much faster to use a mouse (it might be convenient in a car, though). When you correct someone else's text document or spreadsheet it's much faster to use the keyboard. Do you really think that first names change much over the decades? Well, actually most of the names do exist even today (Julara, Ronyo etc.) and I think that over time the popularity of names will always change. Perhaps Julara is amoung the ten most popular names in the year 2061. Why not? Can large scale projects as the one you describe in your book really kept secret for so many years? I do. I believe there's much more going on (even today) than what will end up in the news.