Preparation (physics) experienced in quantum mechanics. Preparation (physics) Generally, measuring instruments are meant to get the (pre-)existent value of a physical quantity of a system with as little change of, or interaction with the system as possible. — If a measuring instrument fixes a physical quantity of a physical system for further use (post-existent), then the measurement process is called preparation. For example, a graduated cylinder filled to a definite mark prepares a certain volume of the liquid for further use. Though preparation measures a physical quantity — at least by fixing it — it often destroys previous states of the physical
Time in physics Time in physics Time in physics is defined by its measurement: time is what a clock reads. In classical, non-relativistic physics it is a scalar quantity and, like length, mass, and charge, is usually described as a fundamental quantity. Time can be combined mathematically with other physical quantities to derive other concepts such as motion, kinetic energy and time-dependent fields. "" is a complex of technological and scientific issues, and part of the foundation of "recordkeeping". Before there were clocks, time was measured by those physical processes which were understandable to each epoch of civilization: Eventually, it became possible to