To estimate a distribution of values instead, he created a computer model of the Milky Way’s stars, generated planets around them, and assigned life to some planets in the habitable zones of their stars. Then he used equations that take into account the random nature of evolution to determine if that life went on to develop intelligence. By running the model again and again, he came up with a range of values, and put errors on the various estimates.
The first scenario assumes that it is difficult for life to be formed but easy for it to evolve, and suggests there are 361 intelligent civilisations in the galaxy.
A second scenario assumes that life is easily formed, but it struggles to develop intelligence, and suggests that as many as 31,513 other forms of life are estimated to exist.
Finally, he examined the possibility that microbial life could be passed from one planet to another during asteroid collisions, which gave a result of 37,964 intelligent civilisations in existence.
Nature never makes one of anything.
Other civilizations are out there, and while we can’t see them, we’re competing with them.
Those who get control of themselves first, make stable but upward bound societies, and so create the technology to explore the stars, win.
The others serve as their slaves, or their food, or simply extinguish themselves on overpopulated, warming, polluted, violent, ghetto-laced planets.
Like Earth, at this point.