I just read through wikipedia's entry on emergence, and wanted to recommend it. There's a section explaining emergence in physics - phenomenon such as color and temperature are emergent properties of lower-level conditions that don't display those qualities but create them on a larger scale. Fascinating stuff. Anyway, it comes close to but doesn't actually say something I was thinking as I read through this section: that emergence might explain why Einstein's Grand Unification Theory has been so elusive. Emergence in physical laws would explain why quantum physics governs particles, why electromagnetic & weak forces govern atoms (composed of particles), and why mechanical laws govern larger bodies composed of those atoms. I am by no means a physicist (it's more of a passing interest), but it did seem to me that studying emergent phenomenon in the field of physics might shed a lot of light on that pursuit.