Previously I posted about just how hard it is to predict new phases of matter, particularly in a specific material. I more or less claimed this has never be done. I was incorrect. Ben Powell pointed out to me two significant counter examples: Bose Einstein Condensates (BECs) and Topological Insulators. Both represent monumental and profound achievements. But, how impressed (or smug) should we be?
After all, both these examples involve non-interacting particles, or at least particles just interacting at the mean-field level. Hence, this just further underscores to me just how hard it is to actually predict truly emergent phenomena, involving "non-trivial" quantum many-body physics.