Wittgenstein's ruler: Unless you have confidence in the ruler's reliability, if you use a ruler to measure a table you may also be using the table to measure the ruler.
Any measurement must take into account the position of the observer. There is no such thing as measurement absolute, there is only measurement relative.
... on principle, it is quite wrong to try founding a theory on observable magnitudes alone. In reality the very opposite happens. It is the theory which decides what we can observe.
I belong to those theoreticians who know by direct observation what it means to make a measurement. Methinks it were better if there were more of them.
if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery.
Unless a thing can be defined by measurement, it has no place in a theory. And since an accurate value of the momentum of a localized particle cannot be defined by measurement it therefore has no place in the theory.
Subatomic particles have no meaning as isolated entities, but can only be understood as interconnections between the preparation of an experiment and the subsequent measurement.
In fact any experiment that measures a quantum effect is one in which the quantum effect is aligned with the behavior of some heavy, macroscopic object; that's how we measure it.
If someone separated the art of counting and measuring and weighing from all the other arts, what was left of each (of the others) would be, so to speak, insignificant.
