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Odds of Finding an Alien Species

Odds of Finding an Alien Species
(Credit: Pixabay)

Aliens and their types, as well as visitors to our planet,  has been a matter of study for scientists and many other researchers for a number of years now. It has been a subject of interest for the movie-makers as well as the common public, and that is why from various corners of our planet frequent news of the visit of aliens and their various proofs of presence come forward.

A quote by Michio Kaku

All think of human being, as the most intelligent, technologically advanced species in the whole universe. But when you see things upside down, there are more than 400 billion stars in our own galaxy – Milky Way only, and there are more than two trillion galaxies in the whole universe. Now it may seem that life can be inevitable in some of these places.

So, let us discuss all the prospects of possible alien life in the universe and what all we know about it. Let us go through different theories and findings around extraterrestrial life.


  1. Number of possible technologically advanced civilizations – Drake’s Equation
  2. Seager’s Equation
  3. The Fermi Paradox
  4. The types of civilizations that can exist – Kardashev Scale
  5. The Search for Aliens
  6. Conclusion
  7. An Infographic on Odds of Finding Aliens

Number of possible technologically advanced civilizations – Drake’s Equation

What do we need to know about to discover life in this huge cosmos? How can we estimate the number of technologically advanced civilizations that might exist among the stars? While working as a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr. Frank Drake conceived an approach to give limits to the terms involved in estimating the number of technological civilizations that may exist in our galaxy. The Drake Equation, as it has become known, was first presented by Frank Drake in 1961 and identifies specific factors which are thought to play a role in the development of such civilizations. Although there is no unique solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors.

Drake's Equation
Drake’s equation (Credit: SETI Institute)


N = The number of civilizations in the Milky Way Galaxy whose electromagnetic emissions are detectable.

R* = The rate of formation of stars suitable for the development of intelligent life.

fp = The fraction of those stars with planetary systems.

ne = The number of planets, per solar system, with an environment suitable for life.

fl = The fraction of suitable planets on which life actually appears.

fi = The fraction of life-bearing planets on which intelligent life emerges.

fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.

L = The length of time such civilizations release detectable signals into space.

So, these magnitudes that were indefinite in the past are now quite definite to an incredible degree of precision. For beginners, the understanding of the extent and measure of the cosmos has been enhanced dramatically. This is only being possible with the state of the art space and ground laboratories, that jackets the complete scale of the wavelengths, and can determine, how many galaxies are present within it and how many beyond.

The number this equation gives is quite huge. It can range from tens of thousands to hundreds of thousands. This big number signifies the probability of the existence of extraterrestrial intelligence the universe has ever had, over the past 13.8 billion years, the age of its existence. Certain things can overturn as well. The key ingredients of the very first start come augmented with the heavy elements and constituents that are necessary for life.

Though this equation predicts the existence of such a big number, we haven’t found even one alien species. Seeing this, there is a possibility that this equation might be wrong or we might be missing something. The Drake Equation: Could It Be Wrong?

Seager’s Equation

Sara Seager, a Canadian-American astronomer developed a parallel version of the Drake equation to estimate the number of habitable planets in the galaxy. Instead of aliens with radio technology, Seager has revised the Drake equation to focus on simply the presence of any alien life detectable from Earth. The equation focuses on the search for planets with biosignature gases, gases produced by life that can accumulate in a planet atmosphere to levels that can be detected with remote space telescopes.

Seager’s Equation is

Sara Seager equation 

where: N = the number of planets with detectable signs of life

N* = the number of stars observed

FQ = the fraction of stars that are quiet

FHZ = the fraction of stars with rocky planets in the habitable zone

Fo = the fraction of those planets that can be observed

FL = the fraction that has life

FS = the fraction on which life produces a detectable signature gas

Seager’s equation predicts that there is a probability that we should at least detect 2 exoplanets with biosignatures.

[bctt tweet=”If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans.—Stephen Hawking” username=”Sciencehook”]

All these predictions aside, if at all aliens are there, where are all of them? This is when the Fermi Paradox comes into the picture.

The Fermi Paradox

The observable universe is 90 billion years in diameter and there are at least 100 billion galaxies each with 100 to 1000 billion stars. With these huge numbers in place, there is nothing wrong in expecting the existence of extraterrestrial intelligence and there should be many of them out there. The Universe is as old as 13.8 billion years. We know that a technologically advanced civilization has existed on earth for the last 300 years only. There is an obvious possibility that some civilization would have started way before us and in that case, they had a lot more time to develop and become a super-powerful civilization. But if such civilization exists in the observable universe, we would have observed them by now. But we didn’t yet. Here comes the Fermi Paradox.

There are many possible explanations for the paradox:

  1. The development of life is not as easy as we think: We don’t yet know how life has evolved on earth and it is a possibility that this process is pretty complex and is very rare especially in the case of intelligent life.
  2. Intelligent life is there only on earth and nowhere else (this is pretty scary)
  3. Intelligent life eventually destroys itself and it is its nature: If this is the case, then we might be getting closer to the end of human civilization.
  4. The Universe kills intelligent life periodically: Probably, the universe kills life periodically by natural extinction events like a meteor shower. In this case, we might have a danger in the near future. To overcome this, we should start expanding our civilization into the cosmos.
  5. Life has formed too far to observe: The universe is too big and is expanding and it is going very fast. So, life might have simply formed too far to observe or detect.
  6. The aliens are too different from us: We hope that aliens also understand the radio signals we transmit but what if aliens have evolved differently. They might be existing in some other dimension and we can’t see them. The sky is the end for such imaginations.

The types of civilizations that can exist – Kardashev Scale

Nikolai Kardashev, a Russian astrophysicist gave the Kardashev civilization classification scale.This scale classifies civilizations depending on the basis of their energy harvesting and consuming capabilities.

On that basis, the civilizations are classified into three categories namely Type 1, Type 2 and Type 3 but Type 4 and Type 5 civilization can also be imagined.

Carl Sagan suggested a rough formula to rate the civilization on the basis of their energy consumption (Note: this formula is not a part of Kardashev theory). The formula is:

Kardashev formula by carl sagan
(Credit: ScienceHook)


K = Rating of civilization

P = Power used by the civilization

Putting our energy use as P = 17.54 Tera Watt we get a rating as 0.7244 but according some researchers human civilization is not even at 0.7 and would take around 150 more years to reach Type-1 level.

So let us know about each type of civilization:

Type 1 Civilization: This civilization can use and store all the energy of its planet and is thus known as a planetary civilization

Type 2 Civilization:  This civilization can control the energy of its solar system. They would be able to build megastructures like Dyson Spheres around there star and harness energy. They might also produce antimatter and harness energy from it. This type of civilization is known as Stellar civilization.

Type 3 civilization: This type of civilization can harness energy at the scale of its galaxy. Just imagine the amount of energy they could access. They can harness energy from neutron stars. They may also be able to tap energy released by supermassive black holes. This type of civilization is called a galactic civilization.

And below are some research papers and articles that you can read to get a much deeper understanding of things like the Kardashev scale and Dyson sphere:

  1. Paper on Kardashev Scale and improvements in it
  2. Dyson Sphere
  3. Energy from Black holes
  4. Kardashev Scale

Apart from these three types of civilizations, we can also imagine the existence of Type 4 civilization which might be operating at the scale of the universe.

The Search for Aliens

Now, after knowing about the odds of finding aliens, possibilities, fermi paradox, Kardashev scale, we also need to know a few things about the search for aliens. Researchers around the world are working day and night to find some clue of extraterrestrial intelligence. There are many non-profit organizations like SETI who are spending millions in this. So, let us move through some missions, programs and their findings related to extraterrestrial intelligence.

[bctt tweet=”A time will come when men will stretch out their eyes. They should see planets like our Earth. ― Christopher Wren” username=”Sciencehook”]

Kepler Space Telescopes

The Kepler space telescope was launched on March 7 2009. These space telescopes monitor the light coming from distant stars and a periodic drop in the light indicates the presence of a planet there. From the amount of light drop, we can estimate the properties of that planet. By, this we can estimate the distance of the planet from its star and predict whether life can exist there or not. Kepler has found close to 3000 exoplanets during its 9.5 years of spaceflight and there are many potential candidates in there.

One star has baffled the science community, known as the Tabby star or KIC 8462852. The Kepler data from this star was so weird that scientists started imagining that there was a Dyson Sphere built around this star and there was an extraterrestrial civilization around there. But astronomers now claim that that light block was due to dust and all.

Huge Radio Telescopes

Humans have built a lot of radio telescopes for detecting radio telescopes coming from the cosmos. We have been doing this in a hope to detect some signal from some civilization trying to contact from deep space. We have really big radio telescopes like China’s National Astronomical Observatories. These radio telescopes can detect extremely weak signals also.

There were a few mysterious signals we detected, like the famous ‘Wow signal‘. We never again received a similar signal, so researchers thought that it might be an alien signal. But recently the mystery of was solved

Wow! mystery signal from space finally explained


Researchers are trying very hard to find aliens by trying all the possible methods. We have gigantic radio telescopes, powerful space telescopes. There are many non-profit organisations like SETI which are spending millions of dollars on several exploration programs. But still, we don’t even have a single clue about any extraterrestrial civilization. Things again come back to the Fermi Paradox.

Let us hope that future missions like the James Webb space telescope give us at least a few signs of extraterrestrial intelligence.

An Infographic on Odds of Finding Aliens

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Odds of finding aliens infographic


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