Are we alone in the Universe

Source: The Hitavada      Date: 28 Aug 2018 10:40:18


I believe alien life is quite common in the Universe, although intelligent life is less so. Some say it has yet to appear on planet Earth.

- Stephen Hawking

WHAt do we know about the Universe? The answer is, Very less. Actually, 4% of the total. Rest 96% is still unknown. So there is a higher possibility that we are not alone in the Universe.

Keep the whole Universe aside and just look at the observable part which itself is 90 billion light years wide. In here, we have nearly 100 billion galaxies like our Milky Way. Each galaxy on an average contains at least 100 to 1,000 billion stars. Each star having planets revolving around it. So, if we go by Drake’s equation, we nearly have about trillions of planets in Habitable Zone. Thus there is a fair chance of finding intelligent life form in our Universe.

Now, if we just focus on the Milky Way, we have about 400 billion stars. In those 400 billion we have 20 billion Sun-like stars which can support life. So, if we just consider 0.1% of planets are in the Habitable Zone, we would have not billion but about a million of planets in the Habitable Zone. This itself gives us a reason to search for life in Universe.

If we take a look at the beginning of the Universe, it all started with the Big Bang. After the big quantum fluctuations and the big explosion, the Universe expanded very quickly. After years it started cooling, the atoms started combining with each other, gas clouds started getting denser and denser. Thus, nearly 100 million years after the Big Bang, first star was born.
Now, the Universe is 13.7 billion years old.

After 1 to 2 billion years the Universe had cooled enough to life to start. The life history on earth dates back to just 4 billion years. So, what happened in the 7 billion years gap? Life may have existed or may not have.
This is known as The Fermi Paradox.
We have three possibilities in this scenario:

1) There are great filters which the planets have to face and we were the only one to pass through all the filters successfully.

2) The filters are yet to come and if someone else exists has faced all the filters and either has been vanished or passed the filters successfully.

3) Or the Universe was very hostile and violent earlier and because of which other life forms could not survive so it makes us one of the first rather than the first.
If we consider that civilisations other than ours exist then why haven’t we found them yet?

This question can be answered is a way that the other civilisations are too advanced to collect our signals and for them we do not exist. It’s like in today’s generation we are using Morse code to communicate with people. Because we have the modern communication facilities for just a century long. So, even if we meet them it will be difficult for us to communicate with them.

If we consider the ‘Kardashev scale’, which tells the technological advancement a civilisation can achieve, then the other life forms may be Type 3 civilisation, who are intergalactic species. We are far behind them as for humans to reach Type 1 we still need couple of 100 years. We are now at 0.73 on the scale. Thus, for a Type 3 civilisation we are just like nobody.

In a recent discovery of a star by Kepler mission, a citizen scientist who was looking for an Earth-like planet found out something interesting about a star called as KIC8462852, commonly known as TABBYS STAR. He found mysterious dipping in the light curve of star. There are various theories which claim the explanation of the mysterious dipping, one of the interesting theories is that the KIC8462852 star system contains a Type 2 civilisation which is trying to construct a mega structure called as the ‘Dyson’s Sphere’ around their star for harnessing the sun’s resources. It might not be the proper explanation for that phenomenon, but is the most interesting one.

The ‘Kardashev scale’ is a method of measuring a civilisation’s level of technological advancement, based on the amount of energy a civilisation is able to use for communication. The scale has three designated categories:
A Type I civilisation - also called a planetary civilisation- can use and store all of the energy which reaches its planet from its parent star.

A Type II civilisation - also called a stellar civilisation - can harness the total energy of its planet’s parent star (the most popular hypothetical concept being the ‘Dyson Sphere’, a device which would encompass the entire star and transfer its energy to the planet(s).

A Type III civilisation - also called a galactic civilisation - can control energy on the scale of its entire host galaxy.
One last thought. May be we are alone as we don’t have a proof of alien life existing but the Universe is yet to be explored totally. The truth is out there we just need to find it.













Atharva Pimpalgaonkar
Co-coordinator GCOEN Astronomy Club