It’s the 1, 1, 2, 3, 5, 8/13 Day Thread!

Were you told there would be no math?


The Fibonacci Sequence may have been known by 200 BC, but is now named for a 12th century Italian mathematician.1 It’s when you start with two numbers (Either 1 and 1 or 0 and 1, depending on who you ask) and add them together to create the next number in the sequence. Then you add that last number of the sequence and repeat, ad infinitum (or, “for freaking ever, dummies”). 1+1 is 2, 1+2 is 3, 2+3 is 5, 3+5 is 8, 5+8 is 13, and 8/13 is today!


You may have heard of the Fibonacci Spiral or “Golden Spiral“. It’s made by putting squares in the sizes of the numbers of the Fibonacci Sequence next to each other and kind of just drawing a spiral that you think looks good. It’s also called the Golden Spiral because the ratio of the sides of the rectangle that you make approximates the Golden Ratio, which is also kind of a big deal.

Also it was on Mathnet. Mathnet, people!


You may have heard that the Fibonacci Sequence is “natural” and “universal” and “special” and “mysterious” because it shows up all the time in nature because pinecones or something. This is pseudomystical DRIVEL! While you do sometimes see Fibonacci numbers in the phyllotaxis (or, “leaf places”) of plants, you sometimes also see other sequences, such as Lucas Numbers or no sequence at all! It is more related to geometry and the Golden Angle2 (which is the angle that splits a circle according to the Golden Ratio that I mentioned before. It wasn’t that long ago, sheesh, try to keep up!) than the actual numerical sequence.

If you’re interested in learning more, I recommend Vi Hart’s “Spirals” sequence: