Rockets, the Earth, and an escape from Egypt

Never mind what I've written here recently. These three pieces are far more fascinating, so read them first:

• Neal Stephenson (via Kottke) reveals why we're still using rockets to send things into space, when more efficient ways could be developed. (Quick summary: blame Hitler.)
  
  
• John Baez (also via Kottke) discusses four great and important catastrophes in the history of the Earth: the formation of the Moon by a collision with another planet 4.53 billion years ago; the Late Heavy Bombardment of the Earth's surface, probably because of gravitational interactions between Jupiter and Saturn between 4 and 3.8 billion years ago; the poisoning of our atmosphere by oxygen after plants evolved photosynthesis 2.5 billion years ago; and the "snowball Earth" global glaciation 850 million years ago.
  
  
• Pioneering podcaster Doug Kaye visited Egypt as a tourist and just got back: somehow he and his wife just threaded the needle of having a completely uneventful Egyptian vacation and being embroiled in the current political turmoil. They witnessed quite a bit, without being in danger themselves. It's quite a story.