How Imaginary Numbers Were Invented

Veritasium

Veritasium

23 min, 29 sec

A detailed exploration of the history and implications of imaginary numbers, from their inception in solving cubic equations to their fundamental role in modern physics.

Summary

  • Mathematics evolved from quantifying the real world to solving seemingly impossible problems by inventing imaginary numbers.
  • The cubic equation posed a problem for millennia until separate solutions by del Ferro and Tartaglia led to the general cubic formula.
  • Imaginary numbers, once seen as useless, were crucial for solving certain cubic equations and later became fundamental in quantum mechanics.
  • The Schrödinger equation, which is central to quantum physics, features imaginary numbers, indicating their essential role in describing the universe.

Chapter 1

The Emergence of Mathematics

0:00 - 37 sec

Mathematics originated to quantify the world and tackle commerce, geography, and astronomy, leading to the challenge of solving cubic equations.

Mathematics originated to quantify the world and tackle commerce, geography, and astronomy, leading to the challenge of solving cubic equations.

  • Mathematics began as a means to quantify the world for practical purposes such as land measurement, planetary motions, and commerce.
  • Cubic equations presented an 'impossible' problem that required the separation of algebra from geometry and the creation of imaginary numbers.
  • Ironically, these imaginary numbers became central in the best physical theory of the universe centuries later.

Chapter 2

Renaissance Italy and the Cubic Equation

0:38 - 48 sec

Renaissance Italy's mathematics, as summarized in 'Summa de Arithmetica', faced the unsolved challenge of the cubic equation.

Renaissance Italy's mathematics, as summarized in 'Summa de Arithmetica', faced the unsolved challenge of the cubic equation.

  • Luca Pacioli, da Vinci's math teacher, published 'Summa de Arithmetica', summarizing known mathematics including the unsolved cubic equation.
  • Ancient civilizations attempted to solve the cubic for over 4,000 years but failed, leading Pacioli to conclude a solution was impossible.

Chapter 3

Quadratic Equations and Geometric Solutions

1:27 - 2 min, 39 sec

Ancient mathematicians used geometric methods to solve quadratic equations, revealing a disconnect with negative solutions.

Ancient mathematicians used geometric methods to solve quadratic equations, revealing a disconnect with negative solutions.

  • Quadratic equations were solved by ancient civilizations through geometric approaches, such as completing the square.
  • Mathematicians were oblivious to negative solutions as they did not have a real-world geometric interpretation.

Chapter 4

The Journey to Solving the Cubic

4:06 - 3 min, 36 sec

The journey to solve the cubic equation began with Scipione del Ferro's secretive solution, leading to a mathematical duel between Fior and Tartaglia.

The journey to solve the cubic equation began with Scipione del Ferro's secretive solution, leading to a mathematical duel between Fior and Tartaglia.

  • Scipione del Ferro solved depressed cubics but kept his method secret for job security, later passing it to his student Fior.
  • Fior's challenge to Tartaglia prompted Tartaglia to solve the depressed cubic using a geometric algorithm, which he summarized in a poem.

Chapter 5

Cardano's Pursuit and Publication

7:42 - 5 min, 54 sec

Cardano's pursuit of Tartaglia's method led to the discovery of del Ferro's prior solution and the publication of the general cubic formula.

Cardano's pursuit of Tartaglia's method led to the discovery of del Ferro's prior solution and the publication of the general cubic formula.

  • Cardano, a polymath, obtained Tartaglia's method under oath not to publish it, but later found del Ferro's prior solution and published the general cubic formula.
  • Cardano's 'Ars Magna' was a major mathematical achievement, pushing geometry to its limits and acknowledging Tartaglia, del Ferro, and Fior.

Chapter 6

Imaginary Numbers and Geometric Paradoxes

13:36 - 3 min, 30 sec

The appearance of imaginary numbers in solving certain cubic equations led to new mathematical and geometric paradoxes.

The appearance of imaginary numbers in solving certain cubic equations led to new mathematical and geometric paradoxes.

  • Complex cubic equations with real solutions sometimes produced imaginary numbers, leading to a geometric paradox involving negative areas.
  • Bombelli embraced these imaginary numbers, creating a new type of number that could lead to real solutions when manipulated correctly.

Chapter 7

The Birth of Modern Mathematics

17:07 - 43 sec

The 17th century saw the birth of modern mathematics with algebraic symbolism and the acceptance of imaginary numbers.

The 17th century saw the birth of modern mathematics with algebraic symbolism and the acceptance of imaginary numbers.

  • With the development of algebraic symbolism by Viete and Descartes' use of imaginary numbers, mathematics began to detach from geometry.
  • Imaginary numbers became integral to complex numbers, which are essential in the description of wave functions in physics.

Chapter 8

Imaginary Numbers in Quantum Mechanics

17:50 - 4 min, 31 sec

Imaginary numbers, once a mathematical oddity, turned out to be essential in describing the quantum world through the Schrödinger equation.

Imaginary numbers, once a mathematical oddity, turned out to be essential in describing the quantum world through the Schrödinger equation.

  • The Schrödinger equation, featuring the square root of negative one, described quantum behavior, revolutionizing chemistry and physics.
  • Despite initial resistance, imaginary numbers showed nature operates with complex numbers, a startling discovery for physicists.

Chapter 9

Learning and Engagement with Mathematics

22:21 - 1 min, 6 sec

Interactive learning experiences like those offered by Brilliant can deepen understanding of complex mathematical concepts.

Interactive learning experiences like those offered by Brilliant can deepen understanding of complex mathematical concepts.

  • The video's sponsor, Brilliant, offers interactive STEM learning that aligns with the video's content, such as courses on complex numbers.
  • Brilliant's approach to learning through doing can enrich one's grasp of mathematics and other STEM fields.

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