Looking into the cause of the ice ages
David posts below about the importance of freedom to scientific enquiry and in particular about the controversy over free enquiry into climate change. The Ingenious Timeline includes the story of climate change explorer James Croll, a 19th century university janitor who taught himself physics, mechanics, and astronomy. Croll eventually sent a number of papers to science editors, who recognized their quality, and published them. (Since his return address was the university, they assumed he was a professor, and were quite surprised to discover he was a janitor.) Croll suggested that changes in the shape of the Earth's orbit from elliptical to nearly circular to elliptical again might explain the onset and retreat of ice ages. His theory finally received proof in the 1970s.