Quantum Physics Interference Quotes

“If you don't have any observation to show which hole the electrons go through, them you get interference between the effects of the two holes. If you do observe the electrons, then you find that indeed they are in one place or the other, not both, but in that case they also act as you would expect if they had come through one hole only and you do not get any interference. The problem is that there is no way in which you can look at the electrons without disturbing them. . . .”
― Robert Gilmore, Alice in Quantumland: An Allegory of Quantum Physics