If you aren't confused by quantum physics, you really haven't understood it. (Neils Bohr)
To explain very puzzling quantum phenomena Neils Bohr and Werner Heisenberg provided our world with the 1927 Copenhagen Interpretation of the double slit experiment (see Schrödinger's Cat, 2 January). The Interpretation still stands. It regards as meaningless questions like, Where was the particle before I measured its position?
