I came across this very intriguing statement in another thread: I vaguely recall seeing this elsewhere, and there is something extremely seductive about it -- if nothing else, its ratio of simplicity to explanatory / predictive power is pretty massive. However, I'm having trouble with the interpretation / ramifications, and I think it comes back to uncertainty relations / Fourier duality -- and maybe also wave/particle duality. For instance, even the statement that there is a "rate of change of phase" poses some difficulty -- because what is it that "has" this phase? I suppose if you took the integral of a wavefunction's energy over any region at time t=a, you could say that this is the instantaneous rate of change of that wavefunction's "phase in that region", but can you even define "phase" in a region -- or for that matter, at an instant? I suppose you can take it a step further and integrate over a 4-volume, and then somehow have an "average" phase / energy over that 4-volume, but being an average, the value it would necessarily be less precise the larger the volume (and therefore, the more 'confident' you can be of the value)? Or am I totally over-complicating this?