One day I had the idea of radiation implosion. As in all ideas that have ever popped up in my head, there is no way I can trace the source. - John Clive Ward

Dynamical variables are what count in physics, not coordinate or gauge transformations.

<math> (\left|x\right\rang \left|y\right\rang- \left|y\right\rang \left|x\right\rang) </math>... was my first lesson in quantum mechanics, and in a very real sense my last, since the rest is mere technique, which can be learnt from books.

The inner mysteries of quantum mechanics require a willingness to extend one’s mental processes into a strange world of phantom possibilities, endlessly branching into more and more abstruse chains of coupled logical networks, endlessly extending themselves forward and even backwards in time.