“Where is everybody?”

The famous question by physicist Enrico Fermi. People may ask it in different ways: “Are we alone in the Universe?” “Is there any intelligent life in the Universe?” “If there is an intelligent life form, where are they? Why can’t we find them?” The search for the answer begins with cold probability and statistics and ends up with great philosophical questions.

We usually wonder at the beauty of the night sky. The twinkling glitters of the sky, the big lovely Moon, and the scorching Sun, which we usually avoid admiring. We definitely wonder about the vastness of space and think about the empty and silent cosmos. And in those pleasant moments, a lot of us have the same question as Fermi:

“Is there aliens?”

Let’s dive into the vast ocean of information and try to find the answer.

What are the most amazing night sky objects we can see with our bare eyes? Five planets, the Moon, Betelgeuse, Sirius, Orion’s Belt, and with a very clear sky, we can even see a faint trace of the Milky Way. Most of the sky is covered with the objects of our stellar neighbourhood. At most, the stars visible in the night sky are at distances of 2,500 to 3,000 light-years. This neighbourhood of stars covers less than 1 percent of the Milky Way’s area. And the majority of visible stars are bigger than the Sun and have much shorter lifespans compared to the Sun, allowing us to easily eliminate them from potential alien-hosting stars.

How many stars are in the Universe? Sorry, the observable Universe? There are 100 billion to 400 billion stars in a typical galaxy. Let’s consider 150 billion stars. And there are approximately 2 trillion galaxies, and rough estimates suggest 10^22 to 10^24 stars are in our observable Universe. Let’s take the minimum number, 10^22 stars.

There is a 5–20% chance for yellow dwarf stars like the Sun, whose lifespans are approximately similar. Five percent of 10^22 is approximately 500 quintillion stars. A recent PNAS study suggests that 22% of these stars have planets similar to Earth orbiting them. That’s 100 quintillion Earth-like planets.

Consider that 1 percent of those doppelgänger Earths are in the habitable zone of their stars, which gives us 1 quintillion Earths. Of those Earths, only 1 percent may actually have alien life, which is 10 quadrillion Earths. And even if we assume a very, very small probability, we can still have 10 to 100 trillion advanced alien life forms in our Universe. At least we can expect 10 to 15 intelligent alien life forms in our Galaxy that originated from yellow dwarf star systems. And orange dwarf star systems can provide even longer-lasting and better support for life in their habitable zones.

We have a high possibility of alien life forms in our Universe.

But why are we not seeing or observing any of them?

Where is everybody?

For reference, the Sun is a very young star, only 4.6 billion years old, while our Universe is nearly 13.8 billion years old.

Consider a star system that is approximately 7 billion years old, with an orange dwarf star at its centre that has a lifespan of nearly 100 billion years. And suppose we have a planet orbiting the star within its habitable zone. It has water, a good atmosphere, and a powerful magnetosphere. Let’s name it Hestia, the dream planet of the Kurzgesagt birb. Thank you, birb, for inspiring us. If you are interested in seeing the dreams of our senior bird, watch it here.

Similar to Earth, Hestia’s ecosystem also started with small single-celled organisms, evolved into multicellular life, then into insects and reptiles, and later into mammals. The evolutionary duration is similar to Earth’s and takes the first 4.6 billion years. At the end of this period, Hestia has powerful intelligent species.

The resources and productive forces of Hestia result in the rise and fall of multiple empires, kingdoms, and republics. It experiences three major Hestian wars. It explores the Hestian system using ground-level technologies. Hestians reach their Moon and build a base there. Eventually, they conquer their entire star system.

All of this happens when Earth is still populated by primitive life forms.

So, by now, in a 7-billion-year-old system, how much transformation could the Hestians have undergone? How should they evolve? Are the Hestians conquering galaxies? Have they stopped and settled into a normal and simple civilization that is efficient enough to satisfy the basic needs of its people? What possible transformations could the Hestians have experienced? Or did the civilization wipe itself out through its own mistakes? Or through natural causes?

If it became a multiplanetary civilization, how did it get wiped out?

There are multiple unanswerable questions that pop up.

There is a concept called the Kardashev Scale, which classifies intelligent civilizations into four parts.

One is Type 0 Civilization, which only uses the energy of its immediate neighbourhood, like cave men. Even humanity’s position on the Kardashev Scale is approximately 0.73.

Two is Type 1 Civilization, which completely utilizes the energy of its planet by fully harnessing solar, wind, geothermal, and volcanic energy. It has full control over the planet’s weather and climate.

Third is Type 2 Civilization, which utilizes the energy of its home star. It can harvest the energy of its home star through technologies such as a Dyson Sphere, completely capturing its radiant energy.

Fourth is Type 3 Civilization, which can control the energy of its entire galaxy. It has the capability to harvest the energy of billions of star systems.

There are some extensions of the Kardashev Scale as well: Types 4, 5, 6, and beyond, which seem more like Marvel comic concepts, capable of harvesting and controlling the energy of the Universe, Multiverse, and Omniverse.

Think about Hestia. This 2.4-billion-year leap could provide enough time for them to become a Type 3 Civilization. And the fun fact is that our Milky Way has the possibility of hosting such planets within it.

But so far, we haven’t seen any aliens or any clear evidence of their existence.

Where are they?

Are we alone?

But saying we are alone is not logical because our search is very limited and very recent. We have only covered a tiny part of the Milky Way itself. I remember one of the good comparisons from Hawking’s book, Brief Answers to the Big Questions:

We take a spoon of seawater and say there are no sharks in the ocean because there are no sharks in my spoon.

Just like that.

What if they are hiding from us? What if they are not sending any signals because, if someone finds them, their planet and civilization could be destroyed?

If that’s the case, we are doomed. We have been sending signals for nearly a century, and we are revealing our location.

Are we the first intelligent life in the Universe?

The Fermi Paradox is one of the ideas that tries to explain the possibilities of other civilizations and their behaviour, while also arguing about the future of humanity itself. It contains lots of questions and scientific explanations behind them.

Let’s explore it in detail in the upcoming parts.

Stay tuned.

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