The Drake Equation was developed in 1961 by Dr. Frank Drake.
It can determine how many possible intelligent, communicating civilizations there are in our galaxy.
The equation represents the following:
N* represents the number of stars in the Milky Way Galaxy Question: How many stars are in the Milky Way Galaxy? Answer: Current estimates are 200 to 400 billion. fp is the fraction of stars that have planets around them Question: What percentage of stars have planetary systems? Answer: Current estimates range from 20% to 50%. ne number of planets per star that are capable of sustaining life Question: For each star that has a planetary system, how many planets are capable of sustaining life? Answer: estimates range from 1 to 2. fl is the fraction of planets in ne where life evolves Question: On what percentage of the planets that are capable of sustaining life does life actually evolve? Answer: Current estimates are 100% (where life can evolve it will) . fi is the fraction of fl where intelligent life evolves Question: On the planets where life does evolve, what percentage evolves intelligent life? Answer: Estimates are 50% . fc is the fraction of fi that communicate Question: What percentage of intelligent life forms have the means and the desire to communicate? Answer: 10% to 20% fL is fraction of the planet's life during which the communicating civilizations may survive Question: For each civilization that does communicate, for what
fraction of the planet's life does the civilization survive?
Answer: This is the most vague question. Using the Earth as our model, the expected lifetime
of our Solar System is approximately 10 billion years. Already communication by radio has
been for less than 100 years. How long can our civilization survive without destroy ourselves
as some predict or will we overcome our problems and survive indefinately? If doomsday came
today this figure would be 1/100,000,000th. If we survive for 10,000 more years this figure
would be 1/1,000,000th.
When all of these variables are multiplied, we get:
- Nc, the number of communicating civilizations in the galaxy.
Use the Drake Equation Yourself
Calculate the possible number of communicating civilizations within our own galaxy using the Drake Equation.
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