what is a propagating spiral?

Answer 1

I can't find an exact mathematical definition of a "propagating spiral" or even an explanation of how it differs from a regular spiral.

I did find a webpage with a neat animation that says that the propagating spiral is related to the Fibonacci sequence and the golden mean:

http://www.textism.com/bucket/fib.html

I'll keep looking.

Ahh...found it under "Fibonacci spiral".

It's also called a "logarithmic spiral", and there's a good description here:

http://www.2dcurves.com/spiral/spirallo.html

and the search I used was:

http://www.google.com/search?hl=en&lr=&safe=off&rls=DELA%2CDELA%3A2005-51%2CDELA%3Aen&q=fibonacci+spiral+equation