The first thought on Extraterrestrial life would be aliens that are intelligent like humanity, but...

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Extraterrestrial Life

The term 'Extraterrestrial Life' refers to the kind of life that doesn't exist on Earth. Broadly saying, It is a kind of life that doesn't exist on Earth, doesn't develop because of the conditions of Earth, and doesn't evolve like the life on earth. The first thought on Extraterrestrial life would be aliens that are intelligent like Humanity, but there are three types of Extraterrestrial life. Microbial life is alien microbes living on the planet. Alien animals would be an ideal kind of species but won't be as intelligent as humans. The rarest of them is Alien intelligent life which we deem as aliens. 

Our galaxy, The Milky way is 120,000 light-years wide. It feels strange that this unimaginably huge expanse of space has only 1 species in a system of a star and planets located in a small section of the galaxy. Research has been made for finding the number of aliens. One of the most known equations for this is Drake's equation created by astronomer Frank Drake in 1961.

Drake's Equation

The parts of the equation are as follows -:

1. N - The number of active alien civilizations in our galaxy.
2. R* - The number of new stars created in our galaxy every year.
3. Fp - The fraction of such stars that have a system of planets.
4. Ne - The fraction of such planets that have the right conditions for life or have an ESI (Earth Similarity Index) of 8 and above.
5. Fl - The fraction of such planets where life develops.
6. Fin - The fraction of such kind of life that evolves into an intelligent species.
7. Fc - The fraction of such kind of intelligent species that develops radio technology. 
8. L - The lifespan of each civilization is judged by the duration of radio transmission.

 The answer? Well, as you may or may not guess, the value of N would vary because of the creation and destruction of an alien civilization.

In other research, we have estimated that there are about 36 civilizations in our galaxy alone. This means we are living with 35 other species in 120,000 light-years expanse.

This brings us to the next point. If we have a new neighbour here on Earth, we can communicate with them. But with other aliens? 

The answer is radio transmission. This has two advantages. First, we can send our messages over long distances for aliens to receive and send another message to us. Secondly, radio transmission would make the conversation intact. 

Electromagnetic Spectrum (By Google)

This is because as stated in the post, 'Big Bang', the doppler effect is created by the expansion of the universe. If we were to send a message in light radiation, the doppler effect would stretch the message into longer waves. The message would be changed and distorted. Because radio waves are the longest of the waves, the doppler effect can't stretch it to longer waves because no longer waves exist. So the message would be intact.

In our history, kings said that they were stronger and more advanced than the others. It stated that they had more powerful, new, and efficient attacking systems. But for the aliens? Is there any scale where we can compare the technologies of aliens like the kings?

One scale in the universe is used commonly by all aliens - Energy. Hence, in 1964, Russian Astrophysicist Nikolai Kardashev founded the Kardashev scale. 

The Kardashev scale shows the Type of civilizations that are advanced by the other in the terms of energy use. Kardashev originally thought of 3 types of civilizations.

1. Type 1 Civilization - This civilization, better known as a planetary civilization, is capable of harnessing energy in the form of natural sources all over the home planet. Technically, these types of civilizations have already found the solution for global warming (if they already have global warming started) - Geoengineering. 
2. Type 2 Civilization - Better known as stellar civilization, the species can control and harness the energy of their parent star and other planets. This means they can alter the orbits of asteroids, and comets, and shift the orbits of planets as much as they please. A fully functional Type 2 civilization would have already started the biggest megastructure of a type 2 civilization, A Dyson sphere or a Dyson swarm.
3. Type 3 Civilization - This type of civilization is known as Galactic civilization. These species can control and harness the entire energy of their host galaxy. What makes them so strong is that not only they can go easily between stars and steal their mass for their uses, they can control the energy of the supermassive black hole. This means they can understand the meaning of the dark matter, time travel, and the formation of a black hole. Basically, to any civilization of the galaxy, they are the ultimate gods.

Geoengineering - The kind of engineering that makes daily life machines and stuff, but makes them in such a way and with such materials that the environment is not polluted. However, this idea is still hypothetical and is at the same level as terraforming.

Terraforming - This is a hypothetical process that can change the composition of the atmosphere and surface of a bare planet. We may or may not have heard the term 'Terraforming mars'. This states that we want to change the atmosphere of mars (currently 95% Carbon Dioxide) into an oxygenated atmosphere to settle on it.

Dyson Sphere and Dyson swarm - The Dyson Sphere is a sphere of a shell of materials orbiting the sun closer than the planets. This is because the energy from the sun is coming in different wavelengths. If we were to capture the energy, we can use it to convert it to new energies. But the materials need to be fire and blast-resistant. Also, comets can nudge the sphere closer to the sun, making it vulnerable to burning. Instead, we can use a Dyson swarm. It is a series of energy-capturing materials in orbit around the sun. There would be a lot of space for comets and the engineering would be cheap.

Coming back, Nikolai Kardashev didn't add more types than type 3 because the science and machines required for intergalactic travel and travel beyond the Milky way are way too far beyond the current human capabilities and even our imagination. But to represent our civilization, which wouldn't fit in the scale and more civilizations, astronomers added more civilizations to it.

• Type 0 Civilization - This species generates energy only through fossil fuels. Since humans have already constructed dams and windmills to get electricity, humanity today ranks as a Type 0.72 civilization.
• Type 4 Civilization - This civilization that can control its entire supercluster of galaxies is termed a Type 4 civilization.
• Type 5 Civilization - This civilization can control the entire universe. Hence, we can say these are our gods and the creators of our 93,000,000,000 light-years wide expanse.

Hope you readers have enjoyed the post and learned something new. 

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Thank you for reading.

Aditya VN Kadiyala