“The three-body problem”, the real scientific enigma on which the successful Netflix series is based

An unsolved scientific problem gives the title to the hit Netflix series, which portrays a utopian China and humanity's first contact with an extraterrestrial intelligence.

The three body problem.
The successful Netflix science fiction series consists of 8 episodes and is an adaptation of the first book of the complex and award-winning trilogy published by Liu Cixin in 2008.

Game of Thrones show-runners David Benioff and D.B. Weiss together with Alexander Woo, screenwriter of True Blood, set out to adapt a complex piece of Chinese science fiction: Liu Cixin's trilogy of science fiction novels entitled "The Memory of the Earth's Past" and whose first book is, precisely, "The three-body problem."

Together they have given television form to this attractive mix of enigmatic virtual reality games, strange worlds, exotic cults, shadowy billionaires and tormented scientists, all set in a utopian revolutionary China of the 1960s.

Liu establishes as the protagonist of the plot one of the most complex questions that involves both physics and astronomy and that, after several centuries, still has no solution: the problem of the three bodies.

What is the three-body problem about?

To enrich his science fiction work, Liu uses concepts and foundations such as artificial intelligence (AI), astrophysics, quantum mechanics, chaos theory and nanotechnology to establish the three-body problem as the central element of the plot.

3 body problem.
The successful Netflix series shows us an epic virtual world, full of dark characters.

Almost at the beginning of the series, the problem that gives its title to the Netflix adaptation is presented: it is that it is necessary to predict the movements of a planet that orbits more than one star. And here known factors come into play, such as gravity, and others not so much, such as the unpredictability of complex systems such as the star system around which the planet in question orbits.

Departing from fiction, the three-body problem is an open problem in physics that addresses the complexities of the movement of celestial bodies.

It is that thanks to the discovery of some fundamental principles of the universe and the establishment of a couple of laws that govern bodies, such as Newton's laws and Kepler's laws, a physicist can determine the positions of two bodies in space through equations, since whether in the past or in the future.

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But in the universe, gravitational connections are not limited to just two bodies. In our solar system, a star is related to at least eight planets. Although in size the influence of the planets is minimal, if a small change occurs in the initial conditions of any of these bodies, this apparent stability can be broken and trigger chaotic movements, something similar to what is explained by the butterfly effect, or chaos theory.

Chaos that is not explained by chaos theory

It is common to find systems with two or three suns. In the case of two bodies that gravitationally attract each other, such as the two suns of a binary system, both suns rotate around each other in a regular and orderly manner.

But if instead of two suns, there were three, their movements can be chaotic, unpredictable. As unpredictable as those of the planets that orbit them. Below is a simulation of the three body problem

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So if a body with considerable mass enters a balanced system, it breaks this balance, causing the situation to tend towards chaos, assuming an extremely complex scenario, with infinite variables that cannot be predicted as a whole. The field of astrophysics recognises this problem as the three-body problem.

Although the three-body problem can be related to chaos theory, they do not imply the same thing. The first is a conception that only applies to celestial mechanics through gravitational interactions, while chaos theory is used for nonlinear dynamic systems, such as the atmosphere.