Science glossary film: Observer

In physics, an observer is a person or system that records some observable property of a system, such as the velocity of an object. We usually assume that the observer will not affect the system, but in fact this is often not true. In particle physics, it is impossible to detect a particle without interacting with it, so the observer does affect the system.

We usually assume that the observer will not affect the system, but in fact this is often not true. In particle physics, it is impossible to detect a particle without interacting with it, so the observer does affect the system.