observables

In physics, an observable is any property of a system that can be measured, such as position, momentum, or energy. Think of it as a property that, when measured, provides specific information about the system's state. Observables are represented mathematically by operators in quantum mechanics, which act on the system's state to give possible measurement outcomes. The key idea is that before measurement, properties can exist in a range of possibilities, but measurement (observation) reveals definite values, often influenced by the system’s quantum nature.