>Basically, you can't exceed the power per steradian of the sun with mirrors. This is something I've wondered about. It seems like one should be able to make a

>Basically, you can't exceed the power per steradian of the sun with mirrors. This is something I've wondered about. It seems like one should be able to make a counterexample by focusing an enormous area on a tiny one. Is it just because due to "fuzzy focus," the concentrated focus volume unavoidably grows as the mirror size grows?