O paradoxinfermi, named after the Italian physicist Enrico Fermi, it is a contradiction related to our total lack of information about the existence of extraterrestrial civilizations in the face of an infinitely large number in stars and planets possibly capable of supporting intelligent life.
See too: Flat Earth - everything you need to know about it
How did the Fermi paradox arise?
Around 1940, a group of scientists were discussing at the table about the existence of other intelligent civilizations. During the discussion, Fermi would have asked: — Where is everyone? According to Fermi's reasoning, if there are billions of planets in the Universe capable of supporting life and millions of intelligent species, what are the chances that none of them have visited the Earth at some point in your history?
Fermi reasoned that any intelligent civilization, equipped with some propulsion technology, such as rockets or spacecraft, would be "quickly" able to colonize a galaxy completely. This idea may seem controversial and is, in fact, impractical given our finite lifetime. However,
Fermi was based on a concept developed bymathematician John Von Neumman, circa 1950: the universal builder.Universal Constructor was the name given by Neumann to his project, which consisted of a sequence of logical requirements necessary for the building a self-replicating machine capable of producing identical copies of itself, which in turn would produce new copies identical. Even though it sounds fanciful, the concept of self-replication detailed by Neumman already exists and is present in the formation of crystals and in the replication of the DNA.
Based on the high probability of there being intelligent beings, due to the huge amount of planets in our galaxy alone, which exists for more than 10 billions of years, and in the idea that there are beings capable of designing rockets and systematically replicating themselves, Fermi developed complex mathematical models and then estimated that a galaxy like ours could have been colonized several times since its formation.
Even taking into account the vast interplanetary distances and speed limitations, a civilization endowed with technologies similar to ours would take no more than four million years do it.
In short, the Fermi paradox debates that, given the age of our galaxy, many technologically advanced civilizations have already should have arisen and colonized other planets, however, within our observable Universe, which contains at least two trillion galaxies, neverwe detectanysignalof intelligent life off Earth.
See too: 7 questions that Physics still hasn't been able to answer
Drake Equation
Drake's equation was developed by astronomer and astrophysicist Frank Drake, in 1961. Drake's goal was not to calculate the number of intelligent civilizations or even to solve the paradox of Fermi, but rather foment the debate on the existence of intelligent lives during the first related congress to the SETI (in Portuguese: Search for extraterrestrial intelligence). To do so, Drake based himself on the main concepts contemplated by scientists who theorized the existence of life outside Earth.
Despite its fame, Drake's equation isn't exactly useful for estimating the number of intelligent civilizations in our galaxy, since several terms in this equation are arbitrary or imprecise. However, its original objective, which was to heat up the debate and the search for intelligent life outside the Earth, has been accomplished over the past few years, since the equation has served as a "conceptual compass" for investigating life outside from the earth.
By Rafael Hellerbrock
Physics teacher
Source: Brazil School - https://brasilescola.uol.com.br/geografia/paradoxo-de-fermi.htm