observerindependence

Observer independence is the idea that certain properties, facts, or laws of a system are the same for all observers or do not depend on the act of observation. In science, an objective claim is typically thought to be observer-independent, while some statements may be observer-dependent or theory-laden.

In classical physics, properties such as mass, charge, and position in an inertial frame are considered to exist independently of observation; measurement merely reveals them. In special and general relativity, the laws of physics are Lorentz-invariant, expressing the same relationships in all inertial frames; predictions are independent of perspective even though measured values can differ by transformation.

In quantum mechanics, the notion of observer independence is debated. The measurement problem raises questions whether properties have definite values before measurement. The existence of contextuality and nonlocal correlations challenges noncontextual, observer-independent realism. The Kochen-Specker theorem shows that noncontextual hidden-variable theories cannot reproduce quantum predictions; Bell's theorem shows conflict with local realism. Experiments testing Leggett-Garg inequalities, Kochen-Specker tests, and Bell tests probe to what extent observer-independent descriptions are possible.

Philosophically, observer independence relates to realism vs anti-realism and the theory-ladenness of observation; in practice, science aims to minimize dependence on the observer by using objective procedures, standards, and invariants.