What is Pi?

Pi (π) is one of the most fascinating and mysterious numbers in mathematics.
It's the ratio of a circle's circumference to its diameter — and it's everywhere.

From ancient geometry to modern algorithms, from quantum physics to pop culture, Pi continues to captivate mathematicians, scientists, and curious minds alike. Let's dive deep into what makes this number so strange, so beautiful, and so endlessly important.

🌀 The Basics: What Exactly Is Pi?

Imagine you have a perfect circle — maybe a pizza, a vinyl record, or a planet. If you measure the distance around the circle (the circumference) and divide it by the distance across the circle (the diameter), you'll always get the same number:

π = Circumference ÷ Diameter

That number is approximately:

π ≈ 3.1415926535...

It's a constant. That means it's always the same, no matter the size of the circle. From a marble to the orbit of Mars — Pi is Pi.

But unlike many other constants, Pi is irrational. That means it can't be written as a simple fraction and its decimal representation never ends or repeats. It just keeps going. Forever.

Try this at home:

Grab a circular object, a string, and a ruler. Wrap the string around the circle, then measure it. Divide that by the diameter.
You'll get something very close to Pi.

Historically, people used simple approximations like 22/7 or 3.14. These are great for everyday use but only scratch the surface of Pi's true depth.

📜 A Brief History of Pi

Pi has been known — and pursued — for thousands of years. Here's a whirlwind tour through the ages:

  • Babylonians (c. 1900 BC): Estimated Pi as 3.125
  • Egyptians (c. 1650 BC): Approximated Pi as 3.16049 using geometric formulas
  • Archimedes (c. 250 BC): Used inscribed polygons to estimate Pi between 3.1408 and 3.1429 — a groundbreaking method
  • Zu Chongzhi (c. 480 AD, China): Calculated Pi to 7 digits: 3.1415927
  • Ludolph van Ceulen (1600s): Devoted his life to calculating Pi to 35 digits by hand — they engraved it on his tombstone
  • 1700s onward: With calculus and infinite series, mathematicians like Newton and Euler pushed Pi further
  • Modern era: Algorithms like the Gauss-Legendre and Chudnovsky formulas allow supercomputers to calculate trillions of digits

Fun fact:

In 2021, a Swiss team calculated Pi to 62.8 trillion digits — it took 108 days of computation.

🧠 Why Is Pi So Strange (and So Awesome)?

Pi is an irrational number — it can't be written as a fraction of two integers. Even more bizarre: it's transcendental, which means it's not the solution to any algebraic equation with rational coefficients.

So what?

  • It never ends: 3.1415926535…
  • It never repeats: No predictable pattern, ever
  • It contains everything: The digits of Pi are believed to be "normal" — meaning every possible number sequence appears eventually
Your birthday, your phone number, the complete works of Shakespeare — all hidden somewhere in Pi? Maybe.

Mathematicians have searched for patterns in Pi for centuries — and found nothing. That's part of its mystery:
It feels like chaos, but it's a very specific kind of chaos.

✨ Where Pi Appears (Besides Circles)

Pi is not just about circles — it's everywhere in math, science, and even art:

π in Math and Physics:

  • Trigonometry: sin(x), cos(x), and their relationships all involve Pi
  • Geometry: Area of a circle = πr²
  • Probability: The bell curve (normal distribution) uses Pi in its formula
  • Relativity: Einstein's field equations contain Pi
  • Quantum mechanics: Wave functions and Planck's law involve Pi

π in the Real World:

  • Nature: Patterns in DNA, tree rings, ocean waves, planetary motion
  • Engineering: Signal processing, electronics, structural dynamics
  • Music: Some compositions use the digits of Pi as notes or rhythm
  • Art & Design: Spiral art, golden ratio approximations, Pi-based aesthetics

π in Pop Culture:

  • Pi Day: Celebrated every year on March 14th (3/14)
  • "Pi" the movie (1998): A mathematical psychological thriller
  • Pi tattoos, Pi-themed songs, even Pi in "The Simpsons" and "Star Trek"

🔍 How Many Digits Do We Need?

Let's be honest: you don't need a million digits to do anything useful.

  • For everyday use? 3.14 is fine.
  • For NASA-level precision? 15 digits get you around the solar system.
  • For most scientific needs? 39 digits are enough to measure the observable universe to atom-level accuracy.
So why compute more?

Because it's a challenge. Because it's beautiful. Because it's there.

The pursuit of Pi is like climbing a mathematical Everest — an exploration of human ingenuity and computational power.

📖 Why We Printed a Million Digits

Some people climb mountains. Some run ultra-marathons. We printed a million digits of Pi.

Not because it's practical. Not because it's necessary. But because it's wonderful nonsense.

We don't need Pi to a million digits. We don't even need most things.
But sometimes, doing something just because it's absurdly possible is reason enough.

We made this book because it's a monument to curiosity, obsession, and the strange beauty of the infinite.
And now you can own a piece of that madness.

👉Get the print book ($14,99)

Pi is more than a number.
It's a question. A fingerprint. A mystery that's somehow everywhere and nowhere.

And the deeper you go, the weirder it gets.