Like Schrödinger’s cat, it was only supposed to be a thought experiment to elucidate the strange mathematics of quantum mechanics.Now, the 46-year-old Kochen–Specker theorem, which describes the quantum dance of observer and observed,has passed its toughest test yet in the real world. The test, published in February (V. D’Ambrosioet al. Phys. Rev. X  3, 011012; 2013), is indicative of growing interest in the theorem, triggered by new capabilities for manipulating photons and cold atoms
For the full story in Nature, click here.