# No Definite Properties Before Measurement

Mass, Charge, Spin has definite properties before measurement.

What else aside from position, momentum that have NO definite
properties before measurement. Is it only position and momentum?

Fredrik
Staff Emeritus
Gold Member
The first quantities you mention are the type of numbers that define a particle species. If you change one of those numbers, we'd be dealing with a different type of particle. Every other quantity is of the "doesn't have a definite value before measurement" kind.

In the non-relativistic theory of a single spin-0 particle, every observable is a function of x and p (the expressions that define them may include other numbers, but no other operators), e.g. energy ($\vec p\,^2/2m$) and angular momentum ($\vec x\cdot\vec p$).

Last edited:
tom.stoer