Prepared by Abid Iqbal Choon
Have you ever wondered in our vast universe, given the billions of stars in the galaxy, why have we never made any contact with extraterrestrial beings? Enter Fermi’s paradox, named after the Italian physicist Enrico Fermi. The basic points of the paradox are as follows:
- There are billions of stars (which are billions of years older than Earth) in the galaxy which are similar to the Sun.
- These stars with a high probability, will have Earth-like planets. Assuming the Earth is typical, it might develop intelligent life.
- Some of these civilisations might be developing interstellar travel, a step the Earth is investigating now.
- Even if the interstellar travel is developing at a slow pace, the Milky Way could be completely traversed in about a million years.
According to this line of thinking, the Earth should
have been visited by aliens by now. The fact that we have not (no concrete evidence of this has been found), makes it a paradox (a self-contradictory or a logically unacceptable conclusion) which leads to the famous “Where is everybody?” line from Fermi in the paper “Where is everybody?” An account of Fermi’s question by Eric M. Jones. 
Maybe the significance of the number “billions” does not register immediately with us, so let’s take a deeper look at the numbers for a better understanding. In just the Milky Way galaxy alone, there is 100-400 billion (a billion has 9 ‘0’s) stars in which there is the same amount of galaxies in the observable universe. We also know that there is a total of 1022 to 1024 stars in the universe. What this means is that for each grain of sand on Earth, there are 10,000 stars out there. It is projected in a study by PNAS (Proceedings of the National Academy of Sciences of the United States of America) , 22% of the sun-like stars might be orbited by Earth-like planets (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Taking the lower number of sun-like stars, which is 500 quintillion, or 500 billion billion sun-like stars, we have 100 quintillion Earth-Like planets. Or in simple terms, we have 100 Earth-like planets for each grain of sand on Earth. Just contemplate about that the next time you are on the beach.
Speculating if only 1% of these Earth-like planets develop life and a further 1% of these develop intelligent life, we would have 10 quadrillion or million billion intelligent civilisations in the observable universe. Maybe talking in the grandiose scale of the observable universe is not that appropriate, so let’s
look in terms of our galaxy. In our galaxy alone, applying the same maths, there would be 1 billion Earth-like planets and 100,000 intelligent civilisations in our galaxy.
Also, we know that Earth is just 4.54 billion years old which is relatively young in the grand scheme of the universe. Given that there are so many possible Earth-like with intelligent species planets, it can be safely assumed that there are many of them that are way older than our planet, which means they would have billions of years ahead of us to progress in terms of technology. They should have been able to contact us by now, no?
In the Kardashev scale, which groups intelligent civilisations into 3 groups by the type of energy they are able to harness from:
- Type 1
Has the ability to use all types of energy in their own planet (Earth is only at Type 0.73 at the moment)
- Type 2
Can harness all the energy in their host star (that would be the Sun for us Earthlings). Dyson Sphere is one hypothetical structure of how we can capture and harness the Sun’s energy.
- Type 3
Since civilisations in this group are able to harness the whole energy in the galaxy, it can be said that they reach god-like status at this stage.
One way of any intelligent civilisation can actually be at this level of utilizing energies in the galaxy, is by self-sustained galaxy colonization. By creating machinery that can automatically detect planets to colonize and self-replicating by using the raw materials or resources on the planet, this is possible. This process would take 3.75 million years without traveling at the speed of light which is relatively fast compared to the time scale of the universe.
So what is the answer of the Fermi’s paradox? There is no concrete answer as of now, but there are definitely some possible explanations to it:
We are the first intelligent beings in the universe
There are simply no other intelligent beings, let alone civilisations in the universe to make contact with.
Intelligent aliens lack the technology
Maybe they are still primitive and have not developed enough to have the technology to make contact with us.
Humans have not existed long enough
Humans have only developed radio telescope recently, radio transmissions have only been propagated since 1895 and Homo sapiens as a species is relatively new on a cosmological scale. Therefore, it can be concluded that we have neither existed long enough nor made ourselves to be sufficiently detectable for any extraterrestrial species.
Earth is deliberately not contacted
The Zoo hypothesis  states that highly technologically advanced intelligent extraterrestrial life exists but does not contact us for the sake of allowing us to develop further up to a point where we are on par with them.
Everyone is listening, but not transmitting
All intelligent lifeforms in the universe are so eager for contact, therefore are just listening for any signals transmitted by others, but none are actually transmitting signals to make contact. (It’s like when two people who are in love with each other are just waiting for the other to make a move first, protip: Y.O.L.O)
They are here undetected
Since they might be very much more technologically advanced than us, it might be possible to suggest that they are already here, but with their superior technology, doing so without being detected by us.
There are still more possible explanations but I shall stop here. Whatever the true explanation may be, it is scary to either think we are alone or not alone in the universe. Let that sink in to you. If we are the only intelligent beings in the universe, we are just a lonely, tiny fraction of this massive universe, mostly consisting of empty spaces. Meanwhile talking about the latter, it is scary to think that there might be some advanced, Type 3 civilisations out there, just waiting for the right time to destroy or to conquer us.