…we have three wildly disparate time scales in play: millions, billions and trillions. Rounding to the nearest 20, we have:
- Time for intelligent life to fill a galaxy: super short 20 million years
- Time for intelligent life to evolve in a galaxy: moderate 20 billion years
- Time of universe to keep having stars: super long 20 trillion years
The first perspective shift is to step back in time, and realize the universe is very young. With 20 trillion years of star generation ahead, the universe has only covered 13.7 billion years or roughly .07% of its life span. Compare this to a person who expects to live 70 years, and youd get .07% * 70 years = roughly 18 days. So in human terms the universe is a three week old baby. No wonder theres not too much life out there yet.