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Comment Threads

• Sean Eric Fagan commented on "These Aren't the Worlds You're Looking For"
  That's quite a trick, given that the generally accepted age of the earth is 4.5 billion years old....
• https://www.google.com/accounts/o8/id?id=AItOawlNCQ69-zALiIBb87L1PQ6ZpJ-tEHsWtzc commented on "These Aren't the Worlds You're Looking For"
  On the topic of providing oxygen to an otherwise Earth-like planet that has little or none in its atmosphere: behold the power of exponential growth. Assuming the comparatively trivial* power to make a robotic solar panel factory that can build copies of itself and a few other bits of machinery, you can produce as much oxygen as currently exists in Earth's atmosphere in mere centuries. Assumptions: Average surface insolation of 5 kilowatt hours per square meter. Target oxygen production: 10^18 kilograms (approx. 1/5 of total atmospheric mass of Earth). Photovoltaic conversion efficiency of 15%. Panel lifetime of 27 years. Panel...
• Sean Eric Fagan commented on "These Aren't the Worlds You're Looking For"
  Pretty tangential, but I'll also point out -- as a native Southern Californian -- that the main reputation eucalyptus has for me is... it burns. Easily. And often. And quickly. And hotly. And then it's back in a couple of years to do the same thing....
• https://www.google.com/accounts/o8/id?id=AItOawlNCQ69-zALiIBb87L1PQ6ZpJ-tEHsWtzc commented on "These Aren't the Worlds You're Looking For"
  Even if self-replicating tech like this is possible, supplying the raw materials means creating another set of mining and refining robots, which also need to self-replicate and which also need raw materials. Sure, solar cells are mostly silicon, but you also need various metals and other materials, some of which are likely to be at least somewhat rare. The machines you are creating need to both self-replicate and move, so 1 cm seems like a probable minimum thickness. So, to cover the planet you need 1,400 cubic km worth of raw materials to make these machines (not counting the mass...
• https://www.google.com/accounts/o8/id?id=AItOawlNCQ69-zALiIBb87L1PQ6ZpJ-tEHsWtzc commented on "These Aren't the Worlds You're Looking For"
  You only need continuous energy supplied for the share of it that goes to non-interruptible manufacturing activities, like refining aluminum and silicon. Even then you do not necessarily need full power at night, just enough to (e.g.) keep your electrolytic aluminum cells above their freezing point. The lion's share of energy goes to the water-splitting atmospheric conversion project and there's no problem with running that on an intermittent basis whenever sunlight is available. How about high-temperature fuel cells and chemical energy storage for the minority share of energy that does need to be supplied continuously? You don't need any rare...