The meaning of the joke is critical to the story of 3 Body Problem. If you do want to know, continue on. If you want to avoid spoilers, leave.

The new Netflix adaptation of 3 Body Problem is a very serious, intense adaptation of Cixin Liu’s acclaimed sci-fi novel. So it probably threw some viewers off when one of the show’s most intense and mystifying scenes ends with a joke.

Here’s that joke and what it means.

The Joke From 3 Body Problem

3 Body Problem Joke

So, Einstein dies. He finds himself in heaven and he has his violin. He’s overjoyed. He loves his violin. More than physics. Even more than women.

He’s excited to find out how well he can play in heaven. He imagines he’ll be pretty damn good. So he starts tuning up, and the angels rush at him.

“What are you doing?” they say.

“I’m getting ready to play.”

“Don’t do that, God won’t like it. He’s a saxophonoist.”

So Einstein stops. He doesn’t play, but it’s difficult. He loves music, and there’s actually not much to do in heaven. And sure enough, from high above, he hears a saxophone. It’s playing “Take The A Train”.

Einstein knows it too, and he thinks: “I’m going to do it. I’m going to play with Him. We’re going to sound great together.” So he starts playing “Take the A Train”.

The saxophone stops, and God appears.

He marches over to Einstein and kicks him in the balls, which hurts, even in heaven. Then he smashes Einstein’s beloved violin to bits.

Eternity without music. Heaven has become hell for Einstein.

And, as he writhes on the ground, holding his smashed balls, an angel comes over and says: “We warned you. Never play with God.”

When Ye Wenjie (Rosalind Chao) tells Saul Durand (Jovan Adepo) the joke, he doesn’t laugh. He doesn’t think it’s very funny. It seems like a very half-hearted play on words.

Ye Wenjie answers that humor is very subjective. It’s very personal. Not everyone finds the same things funny. Then she leaves.

What Happens Before And After Ye Wenjie Tells Her Joke Offers Clues

Ye Wenjie's final moments
First, as should be obvious, read no further if you don’t want to be spoiled. The meaning of the joke is critical to the story of 3 Body Problem. If you do want to know, continue on.

The joke is told in Episode 7 of 3 Body Problem shortly before Ye Wenjie is killed by the San-Ti, the show’s alien protagonists. Before telling the joke, Ye Wenjie tells us she’s looking for a way to stop the San-Ti. Later, we see her reading two books.

The first is Game Theory, one of the most respected books on the subject of strategy. The second is Fermi Paradox: Cosmology and Life. That second book examines the question of why, if aliens exist, haven’t we seen or heard from them yet?

Fermi Paradox in 3 Body Problem
At the same time, Ye Wenjie and the entire world now knows that the San-Ti see and hear everything. There are no secrets from them. The only secrets anyone has is what’s in their own mind. If you came up with a plan to stop them and told someone else about it, the San-Ti would then know that plan and sabotage it.

Given these factors, it’s clear Ye Wenjie has come up with a plan for defeating the San-Ti and wants to communicate it to Saul Durand. Her only method of doing so is in some sort of code that the aliens cannot understand.

She tries to hint at this to Saul by saying humor is very personal. She’s hoping that the San-Ti, being aliens, won’t understand jokes and that since they don’t understand jokes, they won’t be able to figure out the meaning hidden in hers.
Saul Durand after hearing the joke in 3 Body ProblemSaul Duran narrowly escapes death in 3 Body Problem
After Ye Wenjie tells Saul Durand the joke, she is killed. Soon after that, the San-Ti begin trying to kill Saul Durand. They’re afraid of him, confirming that what Ye Wenjie told Saul is absolutely as important as it seems.

The Dark Forest And How It Explains 3 Body Problem’s Joke

The Dark Forest
The meaning of Ye Wenjie’s joke is explained in the second book in Cixin Liu’s 3 Body Problem series; in fact, the joke’s meaning is the very title of that book. The book is called The Dark Forest.

The Dark Forest hypothesis is a theorized solution to the Fermi Paradox. The Fermi Paradox asks, if alien life is plentiful in the universe, why haven’t we seen it? Cixin Liu takes an existing theoretical answer to this question, refines it, and dubs it “the dark forest hypothesis” for use in his sci-fi books.

The Dark Forest Hypothesis theorizes that the reason we don’t see signals or get visits from aliens is one of survival. If you think it through, contact with an alien species is inherently risky. Any civilization contacting another alien civilization risks its destruction because you have no way of knowing what those aliens will do.

In the face of possible species annihilation, the most logical choice is to destroy every alien species you encounter rather than risk contact. It only takes one or two alien species to reach this conclusion, and once they do, those species will immediately destroy any other species they encounter and others will realize they should be quiet lest they be attacked

That creates a situation where the universe is a “dark forest” filled with alien civilizations that are both silent and hostile hiding in it. Any civilization that makes itself known will immediately be destroyed by other alien civilizations unwilling to risk their own safety by interacting with them.

What 3 Body Problem’s Joke Means

The Dark Forest and 3 Body Problem's joke
We already know that in the world of 3 Body Problem, The Dark Forest is a reality. The first message humanity received was a warning, advising us to stop broadcasting our presence to the universe for our own safety. Ye Wenjie ignored that warning, because her desperation was so great she was willing to risk anything for the sake of change.

Ye Wenjie’s joke is an attempt to alert Saul Durand to the fact that The Dark Forest exists.

In the joke, Einstein alerted God to his presence by playing music, causing God to destroy his violin and assault him. If Einstein had remained silent, he would not have been harmed.

How can The Dark Forest save humanity from the San-Ti? If humans alert the universe to the presence of the San-Ti, the San-Ti will be destroyed. Thanks to Ye Wenjie’s discovery that the sun can be used as a signal amplifier, humanity already has the technology to shout into the forest.

Is that solution enough to save Earth from invasion? Expect that to be the focus of where 3 Body Problem goes next.