Estimating Galactic Population – The Model
(See the Introduction here.)
Ever since I found out about the Drake Equation from Sagan’s Cosmos, I have played around with and updated the various factors as new information became available. More or less. I haven’t updated my estimates for over a decade now. With the recent discoveries of exoplanets, larger galaxy, and now the increased possibility of life on Mars, I am past due.
Over on the right sidebar, I have my current estimates – number of stars, planets, planets with life, intelligent technological life, and number of advanced technological worlds we could detect. As you can see my estimates pretty much resolve the Fermi Paradox – Drake overestimates several parameters, by a lot. Of course, I am hardly the first to suggest this.
I depart from the Drake equation immediately, it is a great concept, but for my own understanding several factors need to be expanded. My model is:
Np = N* x Fp
Nl = N* x Fp x Frv x Nrv x Fl
Ni = N* x Fp x Frv x Nrv x Fl x Fh x Fi
Nc = N* x Fp x Frv x Nrv x Fl x Fh x Fi x Fc
Nd = N* x Fp x Frv x Nrv x Fl x Fh x Fi x Fc x Fd
Np is the number of planetary systems.
Nl is the number of planets with life.
Ni is the number of planets with intelligent, technological life.
Nc is the number of planets with technological life who are not hiding their communications.
Nd is the number of Nc who are detectable from our Solar System.
On the left side:
N* is the number of stars in the galaxy.
Fp is the frequency stars have planets.
Frv is the frequency that planetary systems include substantial rocky bodies with plenty of the right volatiles for life.
Nrv is the average number of rocky bodies with volatiles in the planetary system.
Fl is the frequency life occurs on those rocky planets.
Fh is the frequency of surface habitable planets.
Fi is the frequency of intelligent (equivalent to the Homo genus) life.
Fc is the frequency intelligent species become technologically advanced – wireless electromagnetic communication.
Fd the frequency the technologically advanced species is “in range” – we can detect them from the Solar system.
In future parts, I’ll explain why I chose the particular numbers I did.