For a recent question of mine, an answer was provided suggesting that since there is a limited amount of sapient species in the galaxy, we ourselves would be valuable. This got my gears turning and made me wonder, how many sapient species can I expect to find in the galaxy?
Lets make some fair assumptions;
- The planet must exist in the habitable zone
- The solar system must be in the galactic habitable zone
- The planet must be terrestrial
- Only 5 percent of the planets above have the possibility of life.
- Of the 5% with life, only ones older than 4 billion years will have sapient life
Assuming the above is true, how many planets with sapient life can I expect to find in a random Galaxy, where I do not know the exact number of stars?