[elblanco]

I'm surprised classical mechanics would be the weed out course. I found discrete mathematics quite a bit harder than that.

But then again I found field physics and quantum physics quite a bit harder than discrete mathematics (and relativistic physics relatively straightforward no pun intended). I could probably still derive most of the equations for classical mechanics if I really sat down and worked at it (it's been many years since I looked at any of that material) but would definitely have a hard time with Maxwell's equations.

I didn't create the hierarchy, but I think it was the perceived hardness of the applied calc in field physics and applied dif-EQ in quantum that led the Comp Sci folks to hold the Physics majors in higher esteem (since we had to take like 9 credits of Physics and at least 2 lab courses at my school).

[hga]

I'm sure it depends on the student; I sure remember my physics major girlfriend struggling with Lagrangian mechanics in her advanced classical mechanics course. 3 decades after doing basic classic mechanics I can see the utility of Hamiltonian mechanics but I'm not at all sure I'd want to tackle it (chemistry major here ... I wonder where we fit in the hierarchy).

[elblanco]

I can't remember where chem majors fit in. I think it was higher than bio majors.

[hga]

That's what I remember as well; if you limit it to science, I've always heard Math > Physics > Chemistry > Biology.

I've never heard of a ranking that mixes science and engineering before the one you mentioned; at my school, at least, there was generally mutual admiration, with math and physics ranking above any engineering field.