The Three-Body Problem trilogy is a science fiction series that will keep you hooked until the end (if you love science fiction). This is a hardcore science fiction work by Liu Cixin.

⚠️ This article contains spoilers. Here are a few cool concepts from the books.

Humanity figures out a way to amplify a radio signal using the Sun and broadcast our existence to the universe. The signal is picked up by an advanced alien civilization in the Alpha Centauri system. Their home planet orbits around Alpha Centauri’s three stars, which makes their planetary orbital pattern unpredictable. Because of these chaotic three‑body dynamics, multiple civilizations on their world were destroyed by extremes of heat and cold or by the excessive gravitational pull of a nearby star. They also cannot reliably predict their planet’s orbit far into the future. Seeking to migrate to another habitable world, they view Earth as a rare opportunity given the relatively short distance on a cosmic scale. Their spacecraft can accelerate to about 10% of the speed of light. Accounting for acceleration and deceleration, their journey to Earth will take roughly four centuries.

Sophon

From the broadcast signal containing details and history of human civilization, they learn that humanity’s scientific development is happening at an exponential rate, while theirs is more linear due to environmental constraints. This poses a massive challenge for them: although their current technology exceeds ours, in four centuries humanity could surpass them, and their fleet would encounter a more advanced civilization when it finally arrives.

They build Sophon—a supercomputer inside a proton. By unfolding higher dimensions into two‑dimensional space, a proton becomes a vast two‑dimensional circular surface. On this surface they construct a computer within the proton. They create two quantum‑entangled sophons, keep one for themselves, and send the other to Earth. The sophon travels at light speed, taking about four years to arrive. Using the entanglement between the pair, they communicate instantaneously. With these sophons, they spy on humanity and tamper with fundamental physics experiments, effectively blocking progress in fundamental physics.

Photoid

A Photoid is a solar‑system‑destroying weapon used by a more advanced alien civilization. It’s essentially a small mass accelerated to near light speed. When fired at a star, it can destroy it due to its relativistic mass and tremendous kinetic energy.

Two‑dimensional vector foil

Besides the Photoid, another weapon used by advanced civilizations to destroy star systems is a two‑dimensional vector foil. When a Photoid is not viable—for example, if planets in the system could survive a stellar explosion, or an intelligent species could hide behind a planet as a shield—the vector foil becomes the option of choice. It is a two‑dimensional sheet that, upon contact with three‑dimensional space, consumes it and collapses it into two dimensions, continuing to spread and convert three‑dimensional space as it goes. Even a tiny vector foil, fired into a solar system, could flatten the entire system into two dimensions, destroying everything.

Higher dimensions

During humanity’s voyage into deep space, we discover evidence that the universe once included higher dimensions, with ancient structures built within them. Those higher‑dimensional civilizations suffered attacks from lower‑dimensional incursions and were ultimately destroyed by dimensionality strikes.

Droplet

The Droplet is a small autonomous spaceship (roughly the size of a truck) shaped like a water droplet. Its outer shell is made of a super‑strong material that appears perfectly smooth even under atomic‑level magnification—no molecular structure is visible. This makes the Droplet a terrifying weapon that can penetrate structures without taking damage.

Dark Forest Hypothesis

The Dark Forest Hypothesis addresses the Fermi Paradox—why we don’t observe alien civilizations despite the vastness of the universe. It suggests that every advanced civilization hides by not broadcasting its location. Revealing oneself invites invasion or destruction by a more advanced species.

Transparent communication

The aliens here have a very interesting way of communicating: they cannot separate their thoughts from external communication. Whatever they think is what they communicate, like telepathy or thinking out loud. There is no hiding of information or deception. This makes them poor at understanding human strategy, trickery, and lies.

This is a very interesting parallel with the current state of AI. LLMs are excellent at generating text and can achieve a lot. But humans, with richer sensory systems and embodied experience, remain superior in strategy and overall reasoning—even if LLMs can outperform us in some narrow domains.