A = (100 – 300)·10⁹ = Number of Suns in the Galaxy

F_X is the probability of the occurrence of a set of stars belonging to a certain spectral class. There are 13 spectral classes (chapter 12.1)

There is the set of sun-like G stars, with a yellow spectral color and the probability of F_s = 0,28 = 7:25.
There is the set of red dwarfs, i.e. M stars with a red-orange spectral color and a probability of F_RZ = 0,7 = 7:10.
The two spectral classes G and M make up 98% of the total stars in the galaxy.
The spectral types O, B, A, F, K, i.e. the blue, blue-white, white, white-yellow and orange spectral colours make up about 1% of the total stars.
The brown dwarfs and the red giants, i.e. the spectral classes L, T, Y, R, N, S, also make up 1% of the total stars.

According to equation 12.1.1, the set of civilizations of a set of stars, each caused by a spectral class, applies.

Equation 12.2.2 gives the total number of civilizations in the galaxy in sum across all spectral classes:

	NzivGal = ∑ Nzx = A·∑ (Fx · Fph · Fk · FLiz)
12.2.3.2 Equation

F_p = 0,014.4 = 201:14.000 star systems with planets
F_h = 0,016.6 = 10:603 planets in habitable zones

By definition 8.2.1: F_ph = F_p · F_h

F_ph = 201:14.000 · 10:603
F_ph = 1:4.200

By equation 12.5.1 applies:; F_k = F_gae
with 0,001 < F_k < 0,004.7 and 0,000.927 < F_gae < 0,004.672
The probability F_gae for the similarity of the Earth is of the same order of magnitude as the observation probabilitiesF_k.with which all models are equivalent.


By definition 6.3.2: F_Liz = F_L · F_i · F_z

Then equation 12.2.3.2 can also be written like this:

12.2.3.3 Equation

According to equation 4.1.4.5, the probability of life applies:

In particular:
There are n = 8 components called for life to become possible.
It applies to the single probability: f_j = 1:72

This can also cause 8 failures.

For weighting factors, approach 4.1.4.6 applies.: a_j = 1
Thus, the chance of life arises F_L= 1:(n+1) = 1:9.



According to equation 5.2.2.5, the probability of intelligence applies:

In particular:
There are k = 13 causes listed that can destroy life on earth globally.
It applies to the single probability:: f_j = 1:182

Only every 14th planet on which there is life could produce a conscious species.

For the weighting factors, the approach 5.2.2.6 applies: b_j = 1
Thus, the chance of intelligence arises F_i= 1:(n+1) = 1:14.



This results in the number of civilizations, of one civilization level, in the galaxy:

12.2.3.4 Equation

According to equation 6.2.4, the following probability can be established for one civilization level:

Technological civilizations form the levels 6,7 and 8. Therefore the total probability for a technological civilization is:

F_z = 14.400/7.301 · (1:36+1:49+1:64)
F_z= 405.225/3.218.741 = 1:7,943 ¤ 1:8

This results in the number of technological civilizations in the galaxy:

12.2.3.5 Equation

Adapted to the model used so far:

A, F_x, F_ph, F_k are empirically determined factors that are expected to increase in the future.

For the factors F_L and F_i there is enough leeway to capture any set of prerequisites and therefore try different models.

There are n components so that life can be made weighted with the a_j.
There are k components that can prevent the intelligence weighted with the b_j.

The probability of F_z can be applied to a level of civilization as well as a number of stages of civilization. m is the stage of civilization and &sum m is a set of civilization levels.


Equations 12.2.3.4 and 12.2.3.5 include all the cosmic, planetary, and evolutionary influences that a species is exposed to until it has developed a technological civilization.

Equations 12.2.3.4 and 12.2.3.5 build a matrix of variables into which all impacts, from development to civilization, can be assessed and estimated.