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1. June–July 2026 · Version 1

   Merit or Math?

   On June 12, Forbes reported that Elon Musk had become the world's first trillionaire. A question occurred to me: Is it merit, or math?

   I had been thinking about Michael Sandel's The Tyranny of Merit. How much of success is deserved? How much is luck? And how much comes from the rules of the game?

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   Merit or Math? became the first title of this project.

   

   Then I came across the Yard-Sale model. It is astonishingly simple: people trade, the stake is limited by the poorer person's wealth, and a fair coin decides who wins. Repeated trades can concentrate wealth in very few hands. Add a wealth tax and redistribution, and the behaviour can change dramatically.

   Nobody has to cheat.

   I thought: The world needs to see this. A good intuition about a mathematical model can sometimes teach you more than a whole library of economics and philosophy books. I wanted to make that intuition visible.

   From an essay to a little world

   I began writing. Then I remembered why I became a physicist. I have a thing for simple rules that produce unexpectedly complex behaviour.

   In 2006, with Ginestra Bianconi and Matteo Marsili, I published Scale-free networks with an exponent less than two in Physical Review E. We studied a simple model producing networks with exceptionally broad degree distributions, with an exponent γ smaller than 2. The free arXiv version is still there.

   Different subject, same fascination: simple microscopic rules, surprising collective consequences. Why explain this model in a long essay when I could build a little world in which people could watch it happen?

   • Kept: the question and the mathematics.
   • Let go: most of the essay.
2. July · Version 2

   A room full of shapes

   There is an old joke about a physicist who approaches a problem involving a cow by assuming the cow is spherical.

   My first agents were circles. One number, the radius, determines the shape. Area could represent wealth. Add eyes and a mouth, and it begins to resemble a person.

   

   I wanted diversity. But I also wanted to play with our habit of explaining success after seeing who succeeds. Perhaps the triangle became rich because it pointed upward. Perhaps the circle lost because it rolled too much.

   

   We are remarkably good at inventing explanations for outcomes that might have been mostly luck.

   But I had a practical problem. Histograms, Lorenz curves, and other statistical pictures didn't emerge naturally from these shapes. I had to draw separate charts.

   And then something clicked.

   The discovery

   Let the squares become the charts

   What if every agent were a square?

   If a square's area represents wealth, its side represents the square root of wealth. But I can change the representation so its side represents wealth. Then its area represents wealth squared.

   That small change made several statistical measures suddenly intuitive. For wealth shares s_i, the effective number of participants is:

   N_eff = 1 / ∑s_i²

   Make each square's side its wealth share. The total area of the squares is the denominator. Now the question becomes: how many such piles add up to the area of a unit box?

   The same squares could become stairs for the Lorenz curve. A cumulative distribution could become a physical transformation. The complementary cumulative distribution turned out to be more natural to construct than a conventional histogram.

   The charts weren't pictures about the agents anymore. The agents themselves became the charts.

   Each chart became a group photo: the same squares, striking a different pose.

   I think this was my favourite discovery in the entire project.

   • Kept: the room, and a visual language made of squares.
   • Let go: the other shapes, and charts disconnected from their agents.
3. August · Version 3

   A spherical cow and a cast of scientists

   For a while, I imagined a cast of scientists discussing the model. The spherical cow made an appearance, too.

   

   The joke captures something I love about physics. Simplify an overwhelming phenomenon until an essential mechanism becomes visible. Learn something from that simpler world. Then remember what you left out.

   The Yard-Sale model isn't the whole economy. It doesn't contain everyone's talents, institutions, histories, or opportunities. It isn't proof that all real inequality comes from luck. But it shows that some consequences can arise from the mechanics of exchange alone.

   I wanted visitors to understand that distinction without enduring a lecture.

   • Kept: the physicist's habit of simplifying.
   • Let go: the scientists explaining everything.
4. September · Version 4

   Blue, Red, and Galileo

   The storytelling plan was inspired by Galileo's dialogues. Two characters would discuss the world; the reader would listen to their arguments and make up their own mind.

   Blue and Red became my protagonists. One might defend the fairness of the coin. The other might ask why the same square kept getting richer.

   

   I tried different conversations and stories. But the more the characters talked, the more I felt I was giving a lecture. Worse, I was telling people which conclusions to reach.

   That wasn't what I wanted. I wanted people to experiment, become surprised, disagree, ask questions, and reach their own conclusions.

   I decided to remove the narrator, including myself.

   The colours stayed. Most of the talking didn't.
   • Kept: Blue, Red, and the possibility of questions.
   • Let go: the lecture.
5. Early October · Version 5

   Little squares with feelings

   Although I had abandoned the dialogue, I couldn't abandon the characters. I wanted the squares to have emotions.

   I liked Lisa Feldman Barrett's How Emotions Are Made, and I wanted a systematic approach instead of simply drawing a few happy and sad faces.

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   I experimented with valence and arousal: pleasant or unpleasant, calm or excited. These are the dimensions of James A. Russell's circumplex model of affect, which inspired the characters.

   

   The squares could look anxious, excited, furious, delighted, or smug. A tiny face made an enormous difference. Losing half your wealth wasn't merely a numerical operation anymore. Someone looked unhappy about it.

   • Kept: emotional little squares.
   • Let go: seven other styles.
6. 10 October · Version 6

   One room, two dials

   

   Marx flips a coin

   During development, I found something irresistible: a gold coin bearing Karl Marx's face.

   A Marx coin determining who gets richer through a fair coin toss in a wealth inequality simulation. I couldn't resist the joke. It became the coin that decides the outcome of a trade.

   

   Build your own world

   The Yard-Sale model is only one of many simple models with interesting collective behaviour. I started thinking: why stop at one? What if people could change the rules themselves?

   That led to a Blockly-based interface in which rules become blocks that people arrange and modify. Instead of merely watching my experiment, visitors could build their own.

   

   Changing the stake and the tax can produce very different worlds. And that made another philosophical question suddenly practical.

   Be Born

   The veil of ignorance

   One of my favourite ideas in political philosophy comes from John Rawls. Imagine choosing the rules of society without knowing who you'll be within it.

   Rich or poor. Powerful or powerless. Lucky or unlucky.

   This is the veil of ignorance. It inspired the Be born button.

   First, build a world with the rules you prefer. Then be born into it as a randomly chosen participant.

   Would you still choose the same rules?

   

   • Kept: the dials, the coin, and the freedom to change the rules.
   • Let go: the idea that I had to choose everyone's experiment for them.
7. 18 October · Version 7

   Fair and Square

   Once I chose squares, the name practically chose itself. In English, fair and square means honestly and fairly. My game was about fairness. And the little agents were literally squares.

   That pun was too good to pass up.

   I kept simplifying. No long lectures. No narrator. No charts disconnected from the world they describe. Just a coin, some squares, a few rules, and statistical pictures made of the squares themselves.

   Everyone starts equal.
   Every trade is fair.
   What happens next?

   • Kept: the question, and room to find your own answer.
   • Let go: the narrator.