Where are all the Aliens?

The Fermi paradox, The Three-Body Problem, and the great silence of the universe.

Every time we look up at the night sky, we’re faced with a staggering, unsettling truth: the universe is vast—maybe infinite—but it’s dead silent. An impenetrable hush; cold metal wrapped around velvet.
No noise. No sound. Nothing.
But we know there are billions of potentially habitable planets in our galaxy; statistically, intelligent life should have emerged somewhere else.¹
So, where is everyone?
This is the heart of the Fermi paradox²—one of the most haunting questions in astrophysics and the philosophy of science. Is the universe teeming with life, hidden just beyond our reach? Or, more unsettling, is there a reason the cosmos remains silent? I know there are countless tales of close encounters, stories of visitors from the stars. But let’s set them aside for a moment.

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In the Dark Forest

I think about it often. Contact with an alien civilization could be humanity’s greatest breakthrough—or our ultimate downfall. We live in a vast universe, full of mysteries and possibilities, but assuming that other civilizations are peaceful and eager to cooperate might be dangerously naive. Just look at us here on Earth: we wage war over scraps of land, over fleeting resources, over ideologies. Why should we expect anything different from an alien species? The universe could be a “dark forest”, a place where every civilization is a hunter, lurking in the shadows, waiting to strike at anyone foolish enough to reveal themselves. This chilling concept is at the heart of The Three-Body Problem science fiction series³. The author, Liu Cixin,⁴ challenges the rosy assumptions of the Principle of Mediocrity⁵—the idea that humanity is unremarkable and that other civilizations must be more advanced and benevolent. Instead, he presents a universe where survival means staying hidden. It’s fascinating. Or terrifying.

The Three-Body Problem

The three-body problem is a term from classical mechanics, referring to the difficulty of predicting the motions of three celestial bodies under mutual gravitational attraction. Unlike the simpler two-body problem—where a planet orbits a star in a stable, predictable path—introducing a third body creates chaos. The system becomes unstable, its movements unpredictable. Mathematically, there’s no general solution to determine their long-term trajectories; the bodies can drift apart, fall into erratic orbits, or even collide. In Liu Cixin’s novels, the problem isn’t just mathematical—it’s the core of the story. The alien civilization of the Trisolarans (or Sun-Ti) lives in a solar system with three suns, turning their planet into an unpredictable hellscape. Sometimes, the world is scorched by relentless heat; other times, it freezes in the abyss of deep space. With no way to foresee their planet’s future, the Trisolarans make a desperate decision: they must find a new, stable home. And Earth, naturally, becomes their target. Which brings us back to the novel’s central question: in the vast, dangerous universe, is it safer to be seen or to remain hidden?

3 body problem | What trisolarans might look like - Choking Jokes Youtube

The Dark Forest and the Silence of the Aliens

Liu Cixin’s Dark Forest theory forces us to rethink how we approach first contact with extraterrestrial life. If he’s right, our attempts to search for alien signals (SETI)⁶ or broadcast messages into space might be a fatal mistake. Think about it. Plus, as we said, we now know there are billions of habitable planets in our galaxy alone. And yet… nothing. No signals, no messages, no undeniable proof of alien civilizations. Just an endless, impenetrable silence.
Why?
This eerie contradiction between the overwhelming probability of intelligent life and the complete absence of evidence is the Fermi paradox I mentioned earlier.

Enrico Fermi and his question

The Fermi Paradox emerged from a conversation between Enrico Fermi, Edward Teller, Emil Konopinski and Herbert York at Los Alamos in the summer of 1950. The group was discussing flying saucers and the likelihood of interstellar travel. The conversation moved on to other topics, but Fermi brought the discussion back to aliens with the question: “Where are they all?”

In his arguments for the likelihood of intelligent civilizations, Fermi anticipated the Drake equation, which states the number of intelligent civilizations N is

N = R*f_pn_ef_lf_if_cL.

The factor R* is the mean rate of star formation in the Galaxy, f_p the fraction of stars with planetary systems, n_e the number of planets in such systems that are ecologically suitable for the origin of life, f_l the fraction of such planets on which life in fact develops, f_i the fraction of such planets on which life evolves to an intelligent form, f_c the fraction of such worlds in which the intelligent life-form invents high technology capable at least of interstellar radio communication, and L the average lifetime of such advanced civilizations. The first three numbers are the best known, with R* = 10 per year and f_pn_e = 0.1. The uncertainty increases progressively with each factor on the right-hand side of the equation.

As I said, I won’t delve into UFO sightings, conspiracy theories, or Area 51. I respect these theories, and TBH they fascinate me at times, but let’s frame the question as scientifically as possible—grounded in evidence, not speculation. If the universe is as vast and ancient as we believe, and if life is supposed to emerge on multiple worlds, then why don’t we see any clear signs of advanced civilizations? This great silence has led scientists to propose several possible explanations for why the universe appears so empty:

1. Intelligent life is rare or unique—and maybe we really are alone;

2. Civilizations die out before they expand—and technology might doom them before they reach us;

3. Aliens are silent because they’re cautious—here we go in The Dark Forest theory: survival depends on staying hidden;

4. We are too small to be noticed—and advanced civilizations might see us as insignificant (Principle of Mediocrity);

5. Interstellar communication is impossible or unlike anything we imagine—maybe we’re just looking the wrong way.

Should We Be Worried?

I don’t know about you, but I can’t help but wonder. Looking up at the stars is a resizing act—it shrinks our material significance but also expands our consciousness. We may be small, physically bound to this one planet, but our minds can reach far beyond. The proof is we can write about other worlds as if we’re living in them, like they’re real. And maybe they kind of are.
If the universe is full of intelligent life, there may be a universal danger preventing civilisations from contacting us. A great filter. A silent, invisible threat. So what does this mean for us? Either we’re incredibly lucky to be alive and should avoid attracting unwanted attention, or we’re among the first to reach this level of technology. But the silence of space remains, pressing against us with an unspoken question—one we may not be ready to answer: If there are aliens out there, do we really want them to find us?

1. Drake equation purports to yield the number N of technically advanced civilizations in the Milky Way Galaxy as a function of other astronomical, biological, and psychological factors. Formulated in large part by the U.S. astrophysicist Frank Drake, it was first discussed in 1961 at a conference on the “search for extraterrestrial intelligence” (SETI), held at the National Radio Astronomy Observatory in Green Bank, W.Va. [Here]

2. Fermi paradox, contradiction between the seemingly high likelihood for the emergence of extraterrestrial intelligence and the lack of evidence for its existence. The paradox has two broad forms: (1) Why has Earth not already been visited? and (2) Why is there no evidence for extraterrestrial intelligence at all? [Here]

3. Set against the backdrop of China’s Cultural Revolution, a secret military project sends signals into space to establish contact with aliens. An alien civilization on the brink of destruction captures the signal and plans to invade Earth. Meanwhile, on Earth, different camps start forming, planning to either welcome the superior beings and help them take over a world seen as corrupt, or to fight against the invasion. The result is a science fiction masterpiece of enormous scope and vision [Go deeper].

4. CIXIN LIU is the most prolific and popular science fiction writer in the People’s Republic of China. Liu is a winner of the Hugo Award, an eight-time winner of the Galaxy Award (the Chinese Hugo) and a winner of the Chinese Nebula Award. Prior to becoming a writer, he worked as an engineer in a power plant. His novels include The Three-Body Problem, The Dark Forest, and Death's End. [Here]

5. The principle of mediocrity.

6. Search for Extraterrestrial Intelligence: NASA and the Search for Extraterrestrial Intelligence.