Parameter Selection

Param	Description	Number	Slider
R*	Number of new stars born in the Galaxy, per year
	OBSERVABLE: Based on the estimated age of the galaxy and the number of stars observed in the Milky Way, Astrophysicists estimate that 6-7 new stars in the galaxy each year.
Fp	Percentage of Stars with Planets
	CONFIDENT: It is widely believed that all stars have planets. A star not having planets is very improbable.
Ne	Average number of planets, per Star, in the Goldilocks Zone
	CONFIDENT: Realistic numbers are 1-5 planets per solar system. In our Solar System, Earth and Mars are in the Goldilocks zone.
Fl	% of Planets (in the Goldilocks Zone) where life exists
	SPECULATIVE: If the conditions exist, life will always find a way = 100%
Fi	% of Planets with life where Intelligent life exists
	VERY SPECULATIVE: Is intelligence inevitable if there’s life + time to evolve, or is it very difficult to achieve? We haven’t detected any civilizations yet, so maybe it is difficult.
Fc	% of Planets with Intelligent life that develop radio communication
	SPECULATIVE: Will any intelligent civilization discover radio communications? Again, probably, with time.
L	Number of years an intelligent, communicating civilization lasts
	VERY SPECULATIVE: On Earth, radio communications were discovered in 1901, and the largest nuclear weapon ever detonated was dropped 60 years later. Humanity may continue thriving for many years, but as technological capabilities develop there are existential risks that threaten to end it all.

Relevant Background

– The Milky Way is 13.6 billion years old.

– The Milky way is around 100,000 light years across and 1000 light years thick.

– The Solar System and Earth are 4.5 billion years old.

– Current estimates for traversing the galaxy at speeds currently possible is 1 billion years.

– Astrophysicists estimate that the sun will make life inhabitable on Earth within 500-600 million years.

– Radio communication was invented in 1901.

– The first radio signal sent from Earth that could be detected from another star was sent in 1936.

– Tsar Bomba, the largest nuclear detonation ever recorded, was dropped in 1961.

– 90 stars have been discovered within a distance of 7 light years from Earth.

– The Great Filter could be preventing us from detecting any intelligent civilization, but the question is – at what stage in the development of an advanced civilization is the Great Filter applicable? Have humans already passed through the Great Filter and survived, or is the Great Filter looming in our future?