Fermi Paradox

What is Fermi Paradox?

The Fermi Paradox answers the question about the existence of aliens. The sun and our Earth are part of a young planetary system. It is much younger as compared to the rest of the universe. 

This gives rise to a theory that says that aliens may have already visited Earth, as interstellar travel might be very easy to achieve for them.

In the year 1950, an Italian physicist Enrico Fermi, who also created the first nuclear reactor, gave the theory of Fermi Paradox. Since then, his implications made extraterrestrial researchers scratch their heads for decades.

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Fermi Paradox Explained

Enrico Fermi realized that any civilization which has a significant amount of high-tech technologies is capable of colonizing the entire galaxy. SETI (Search For Extraterrestrial Institute), an institute located in Mountain View, California, has mentioned in its website that, "Within ten million years, every star system can be brought under the same empire. 

The million years is a short time as compared to the age of the galaxy, which is approximately a thousand million years. The colonization of the Milky Way Galaxy can be done in a short period."

Here Are Some of the Facts That Highlight the Apparent Contradiction

  • Milky Way Galaxy is a dwelling place to billions of stars similar to the sun.

  • There is also a high probability for the existence of Earth-like planets in any of the star systems.

  • Many of these star systems and their planets are older than our sun. Some planets may also have developed intelligent life long ago.

  • Some of these civilizations may have also achieved interstellar travel, a step that the human race is investigating now.

  • Even with a slow pace of interstellar travel, within a few million years, the Milky Way Galaxy could be completely traversed.

  • Since these star systems are billions of years older, the extraterrestrial civilizations may already have visited our Earth, or at least they may send their probes.

  • However, there is no proof that this has occurred, or perhaps we aren't comprehensible enough to understand it.

Drake Equation

The Drake equation is an argument that generates a probability to estimate and calculate the number of active and communicative extraterrestrial civilizations present in the Milky Way galaxy.

Sir Frank Drake gave this equation in 1961. The purpose of this equation was not actually to quantify the number of civilizations, but to stimulate the scientific dialogue at the first scientific meeting on the search for extraterrestrial intelligence (SETI). 

The Drake equation summarizes the key concepts that scientists consider while dealing with radio-communicative life. 

It is considered an approximate approach rather than a serious attempt to determine the number of extraterrestrial star systems precisely.

The drake equation formula is:

N = fi × fc x R × fp × ne × fl × L


N = the number of extraterrestrial civilizations in our galaxy with which communication might be possible.

R= it is the average rate of formation of stars in our galaxy.

fp = the fraction stars that have planets.

ne = the average number of planets capable to support life.

fl = it is the fraction of planets that have developed life at some point.

fi = the fraction of planets with life, which has developed intelligent life forms(civilizations)

fc = the fraction of civilizations that are capable of developing a technology that can release detectable signs of their existence into space.

L = the length or duration of time for which such civilizations can release detectable signals into space.

Drake Equation Values

There is considerable disagreement on the values obtained by the Drake experiment, but the values obtained by Drake and his colleagues in 1961 were:

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R∗ = 1 year, (1 star is formed per year, on the average throughout the life of the galaxy)

fp = 0.2 to 0.5 (20 to 50 percent of all stars formed will have planets)

ne = 1 to 5 (star systems with planets will have between 1 to 5 planets that are capable of developing life)

fl = 1 (100% of these planets will surely develop life)

fi = 1 (100% of them will also develop intelligent life)

fc = 0.1 to 0.2 (10–20% of those planets will communicate by sending signals in space)

L = 1000 to 100,000,000 years (the signals will last somewhere in between 1000 years and 100,000,000 years)

Now, putting all those values in the above equation, we get the values of N as:

N (minimum) = 20

N (maximum) = 50000000

According to Drake's, for the original meeting, there were probably between 1000 and 100,000,000 advanced civilizations in the Milky Way Galaxy, and so N ≈ L.

There Are Some Possible Solutions for the Fermi's Paradox, and They Fall in the Following Categories

  • Extraterrestrial beings are here.

  • They exist but have not yet communicated with us.

  • They have never existed.

  • Planets with suitable conditions are rare.

  • Life is rare.

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In general, the solutions of Fermi's paradox come down to either of the two parts, i.e., either life is much difficult to start and evolve, or advanced civilizations destroy themselves within a short period of time. 

Thus, this is the most significant issue to solve this case, and hope that it's the first part and not the second part.

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FAQ (Frequently Asked Questions)

1. What Are the Variables in the Drake Equation?

SETI defines the variables as:

N = number of active communicative extraterrestrial civilizations.

R= average rate of star formation.

fp = fraction of stars that have planets.

ne = the average number that potentially supports life.

fl = fraction that developed life at some point.

fi = the fraction of planets that developed intelligent life.

fc = fraction releasing detectable signals into space.

L = the length of time releasing detectable signals into space.

2. How Many Planets in the Universe Have a Life?

Till this day, only about a dozen planets have been detected that are capable of being habitable. Scientists claim that the universe is filled with alien worlds that could support life. 

The Milky Way Galaxy alone may have around 60 billion such planets, including red dwarfs.

3. What is the Drake Equation Purpose?

The purpose of Drake Equation is to estimate the number of communicating civilizations that are present in the cosmos. It develops a probability of finding intelligent life in the universe.

4. What is the Date of Star Creation in Our Galaxy, R∗?

Latest calculations from NASA and the European Space Agency reveal that the current rate of formation of stars in our galaxy is about 0.68–1.45 M☉ of material per year.