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- A political and philosophical feud between Pavel Nekrasov and Andrey Markov spawned math for dependent events—Markov chains.
- Those chains plus Monte Carlo simulations now power nuclear modeling, PageRank, and how AIs predict your next word.
- Oh, and yes: ~7 riffle shuffles ≈ random; sloppy overhand shuffles need thousands.
From Tsars to Search Engines: How Markov Chains Took Over the Modern World
How many shuffles does it take to truly randomize a deck of cards? Seven riffles. How much uranium makes a bomb tick? That answer came from statistical simulations. How does Google magically know the page you meant? That’s a Markov chain flex. And how do chat apps guess your next word? Yep—descendants of the same idea.
Here’s the plot twist: the math behind all that didn’t fall from the sky. It came out of a messy, very human feud in early-1900s Russia—politics, ego, and some world-class shade included.
Act I: When Probability Met Politics
Russia, 1905. The empire’s boiling over. Tsarists on one side, socialists on the other. Even mathematicians picked teams. On Team Tsar: Pavel Nekrasov, devout, powerful, and nicknamed the “Tsar of Probability.” On Team Socialist: Andrey Markov, razor-sharp atheist with a reputation for flaming sloppy reasoning. (His colleagues literally called him Andrey the Furious. Mood.)
Everyone agreed on the big law of the day: the law of large numbers. Flip a fair coin a lot, and the average heads/tails ratio settles near 50/50. But historically, that law assumed each trial was independent. One flip doesn’t sway the next.
Nekrasov doubled down on that idea—and then overreached. He stared at tidy 19th-century stats like yearly marriage counts and crime rates and said, “Look, they stabilize. Therefore, the decisions behind them must be independent acts of free will.” As in: convergence ⇒ independence ⇒ free will. That’s not just math; that’s theology teeing up a proof.
Markov was not having it.
Act II: Markov's "Hold My Vodka" Moment
To break Nekrasov’s logic, Markov needed to show that dependent events can still converge. He picked a target that’s obviously dependent: text. Letters don’t wander randomly—what comes next depends on what came before. Using Pushkin’s Eugene Onegin, he counted vowels and consonants, then measured how often letters followed each other. The dependencies were real and strong.
Next, Markov built a tiny prediction machine with “states” (vowel/consonant) and transition probabilities (vowel→consonant, consonant→vowel, etc.). Run that chain long enough, and the vowel/consonant ratio still converged to the observed frequencies.
Mic. Drop.
Translation: you can see neat convergence without independence, and certainly without proving “free will.” Markov essentially invented a tool for the messy world—the Markov chain—where tomorrow depends on today, and that’s fine.
Act III: From Poetry to Plutonium
Fast-forward to the 1940s. Stanislaw Ulam, recovering from encephalitis, was burning hours on Solitaire and wondering, statistically, how often a randomly shuffled game is winnable. Analytic math was hopeless, but sampling lots of random deals? That gives an estimate. When he got back to Los Alamos, Ulam and John von Neumann leveled this idea up: simulate hard physical processes by randomly sampling outcomes. They dubbed it the Monte Carlo method (casino vibes and all).
Here’s the catch: neutrons in a reactor aren’t independent like card deals. A neutron’s fate depends on where it is and what just happened. Enter the hero from Act II: Markov chains. Stitch Monte Carlo randomness onto Markov-style transitions and—boom—you can estimate the multiplication factor (k) of a chain reaction. Less than 1? The reaction fizzles. Greater than 1? Runaway energy. That’s how we answered “how much fissile material is enough?”
So yes, nuclear design, reactor safety, medical imaging, finance, weather—Monte Carlo + Markov chains became a Swiss Army knife.
Act IV: Why Google Beats Keyword Spam
The web’s early search engines mostly matched keywords. Easy to game: hide a term a thousand times in white-on-white text and voilà—top result. Then two Stanford students, Larry Page and Sergey Brin, reframed the internet as a Markov chain. Pages are states; links are transitions. If a “random surfer” wanders by link, occasionally “teleporting” (the damping factor), where do they spend the most time over the long run? Those steady-state probabilities are PageRank.
It crushed spammy tricks because quantity of links mattered less than quality—high-authority pages pass stronger votes. That one idea, essentially a Markov steady state, helped Google leapfrog everyone.
Act V: Your Inbox Autocomplete and the Next-Word Game
Claude Shannon—the father of information theory—played the Markov game with letters and words: predict the next symbol based on a short history. Modern language models go much further (using “tokens” and attention to weigh context), but the skeleton is familiar: estimate the distribution of “what comes next” from “where we are now.” Markov’s spirit lives inside your phone’s autocomplete and the AI writing your bedtime email.
One cautionary loop: if models train mostly on model-generated text, quality can collapse into a bland echo chamber. Not every system is well-modeled as Markovian, especially when feedback loops dominate (think climate tipping points). But for huge swaths of reality, the “memoryless” approximation is insanely useful.
Bonus Round: So… How Many Shuffles?
Treat each deck arrangement as a state and each riffle shuffle as a step in a Markov chain. The “mixing time” for a standard 52-card deck is about seven good riffle shuffles to get “close enough” to random (in total-variation distance terms—yes, we brought receipts). But sloppy overhand shuffles? You’ll need thousands to approach the same randomness. So when your friend mushes the cards twice and says “we’re good,” you’re legally allowed to raise an eyebrow.
The Big Takeaway
A philosophical knife fight about free will and independence ended up gifting us the math of dependency. From Pushkin to PageRank, from ENIAC to Gmail, from reactors to random decks—Markov chains and Monte Carlo let us reason about the next step without drowning in the entire past. It’s the simplest kind of wizardry: just enough memory to matter, not enough to paralyze.
Next time Google nails your query on the first try or your phone finishes your sentence, give a tiny nod to Andrey the Furious. The man didn’t just win an argument—he gave the modern world a playbook.
Keep your curiosity shuffling and your brain in the loop with more math-meets-geek culture deep dives at Land of Geek Magazine!