23 November 21

Mathematicians around the world count on 23 November to celebrate the Fibonacci Sequence. The digits in the date, 1-1-2-3, are the early members of the sequence. Start with the numbers zero and one (0, 1). Add them together and continue the pattern, so that you get 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, . . . That seems like a simple arithmetic game, but the spiraling sequence turns out to have enormous significance in the natural world, in mathematics and throughout science. (Do you remember learning about the "binomial expansion"?) The properties of the "Fibonacci sequence" were first explored in Europe by "Fibonacci, also known as Leonardo Bonacci, Leonardo of Pisa, or Leonardo Bigollo Pisano" who was born around 1170 and who was "an Italian mathematician from the Republic of Pisa, considered to be the most talented Western mathematician of the Middle Ages." My tie is one from Jerry Garcia's "Snail Garden" collection, and I'm wearing it today because the spirals on snail shells are among the simplest examples of how the Fibonacci sequence shows up in natural objects.