I am presently taking an online astrophysics class taught by Paul Francis and Brian Schmidt out of ANU and the math is a bit like a foreign language to me. Its the lack of familiarity that crosses my wires. I just joined PF and look forward to learning some real formulas, equations, their histories and their explanations. I am 65 and have not been involved in any math in any way except what was necessary to run a CNC and pay the bills. I have been a lover of science and have read "pop" science all my life. Some of my favorite books are written by people such as E.O Wilson, Jared Diamond, Timothy Ferris, Richard Dawkins, Christopher Wills and anyone who popularizes Cosmology in the fashion of Carl Sagan. The course is at EDx and is called Greatest Unsolved Mysteries of the Universe. Its the first in a series of four I signed up for. Right off the bat it was theta, radians, flux, luminosity, scale factors, redshift, emission and absorption lines, ionization and reionization so I was caught off guard by the math and found myself actually having to work my little gray cells hard. So here I am, ready to grasp it!