Happy Fibonacci Day

Today is Fibonacci Day. But only if you use the American date system (that no one except Americans use) whereby the month is written before the day. So November 23rd is therefore written 1, 1, 2, 3 - the first four numbers in the Fibonacci sequence. However, I'm willing to suspend being irked by this because Fibonacci is worth celebrating. One of the most important mathematicians of the Middle Ages, Leonardo Bonacci - later known as Fibonacci (son of Bonacci) - invented a sequence of numbers that shows up constantly in nature, physics, and design. 

The Fibonacci sequence is created by adding up the two previous numbers to get the next one. So the sequence starts 1, 1, 2, 3, 5, 8 etc. Fibonacci’s original example for his sequence pondered the population growth of rabbits. If starting with one pair, and each month that pair bears a new pair, the number of rabbits will grow at a rate consistent with his pattern of numbers. 

The Golden Ratio, a proportion associated with the Fibonacci sequence and also frequently found in nature, is roughly 1 to 1.6. This ratio shows up in the branching patterns of trees, the distribution of seeds in berries, the spiral arms of galaxies, and many more natural and human-engineered things.

Fibonacci spirals in a Romanesco cauliflower. 

Here's the Golden Ratio applied to the growth pattern of sunflower seeds and a nautilus shell.

Nature has all the best mathematics.