Test your knowledge of the Drake Equation, a probabilistic argument used to esti...

Drake Equation and estimating the number of alien civilizations in the galaxy

• The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy.
• The equation summarizes the main concepts which scientists must contemplate when considering the question of other radio-communicative life.
• The estimated values for several of its factors are highly conjectural, making the uncertainty associated with any derived value so large that the equation cannot be used to draw firm conclusions.
• The equation amounts to a summary of the factors affecting the likelihood that we might detect radio-communication from intelligent extraterrestrial life.
• The usefulness of the Drake equation is in the contemplation of all the various concepts which scientists must incorporate when considering the question of life elsewhere, and it gives the question of life elsewhere a basis for scientific analysis.
• Estimates for the parameters of the Drake equation include the rate of star creation in this galaxy, fraction of those stars that have planets, average number of planets that might support life per star that has planets, fraction of the above that actually go on to develop life, and fraction of the above that develops intelligent life.
• NASA and the European Space Agency indicate that the rate of star formation in this Galaxy is about 0.68–1.45 M☉ of material per year, and fp (fraction of those stars that have planets) may approach 1.
• Astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of sun-like stars and red dwarf stars within the Milky Way Galaxy.
• Geological evidence from the Earth suggests that fl (fraction of the above that actually go on to develop life) may be high.
• Those who favor higher values for fi (fraction of the above that develops intelligent life) note the generally increasing complexity of life over time, concluding that the appearance of intelligence is almost inevitable.
• Estimates of fi have been affected by discoveries that the Solar System's orbit is circular in the galaxy, at such a distance that it remains out of the spiral arms for tens of millions of years (evading radiation from novae).
• The consensus at the Green Bank meeting was that N (number of civilizations in the Milky Way Galaxy) had a minimum value between 1,000 and 100,000,000 planets with civilizations.The Drake equation is a probabilistic argument used to estimate the number of communicative civilizations in the Milky Way galaxy. The equation includes variables such as the rate of star formation, the fraction of stars with planets, and the fraction of those planets that could support life. The fraction of those planets that could develop life, the fraction of those that could develop intelligent life, and the fraction of those civilizations that release detectable signs of their existence are also included. The fraction of civilizations that have a lifetime long enough to communicate with other civilizations is another variable. The equation has been modified several times to account for uncertainties and other factors relevant to the odds of contacting other civilizations. The equation has been criticized for its speculative nature, especially for the terms that are largely based on conjecture. The Fermi paradox, which states that there are no confirmed signs of civilizations or intelligent life elsewhere, leads to the Great Filter hypothesis. This hypothesis suggests that one or more steps in the process of developing communicative civilizations must be acting as a filter to reduce the final value.