Editing Observation (section)

==Paradoxes==
In some specific fields of science, the results of observation differ depending on factors that are not important in everyday observation.  These are usually illustrated with apparent "[[paradox]]es" in which an event appears different when observed from two different points of view, seeming to violate "common sense".
* ''' Relativity:''' In [[relativistic physics]] which deals with velocities close to the [[speed of light]], it is found that different observers may observe different values for the length, time rates, mass, and many other properties of an object, depending on the observer's velocity relative to the object. For example, in the [[twin paradox]] one twin goes on a trip near the speed of light and comes home younger than the twin who stayed at home.  This is not a paradox: time passes at a slower rate when measured from a frame moving concerning the object.{{clarify|What does "a frame moving concerning the object" mean?|date=January 2023}}  In relativistic physics, an observation must always be qualified by specifying the state of motion of the observer, its [[Frame of reference|reference frame]].{{cn|date=January 2023}}
* '''Quantum mechanics:''' In [[quantum mechanics]], which deals with the behavior of very small objects, it is not possible to [[observer (quantum physics)|observe a system]] without changing the system, and the "observer" must be considered part of the [[system]] being observed. In isolation, quantum objects are represented by a [[wave function]] which often exists in a [[quantum superposition|superposition]] or mixture of different [[quantum state|states]]. However, when an observation is made to determine the actual location or state of the object, it always finds the object in a single state, not a "mixture". The interaction of the observation process appears to "[[wave function collapse|collapse]]" the wave function into a single state. So any interaction between an isolated wave function and the external world that results in this wave function collapse is called an ''observation'' or ''measurement'', whether or not it is part of a deliberate observation process.