Open main menu


Physical System



  • (Wikipedia, 2014) ⇒ Retrieved:2014-3-7.
    • In physics, the word system has a technical meaning; namely, a physical system [1] is the portion of the physical universe chosen for analysis. [2] [3] Everything outside the system is known as the environment, which in analysis is ignored except for its effects on the system. The cut between system and the world is a free choice, generally made to simplify the analysis as much as possible. An isolated system is one which is supposed to have negligible interaction with its environment.

      Often a system in this sense is chosen to correspond to the more usual meaning of system, such as a particular machine. But physical systems are often more esoteric: an atom, the water in a lake, or indeed the water in the left-hand half of a lake can all be considered as physical systems. In the study of quantum decoherence the "system" may refer to the macroscopic properties of an object (e.g. the position of a pendulum bob), while the relevant "environment" may be the internal degrees of freedom, described classically by the pendulum's thermal vibrations.

  1. An Essay on the Investigation of the First Principles of Nature. By Felix O'Gallagher. J. Hill, at the College Printing-House, 1784.
  2. The Newtonian Revolution. By I. Bernard Cohen. Cambridge University Press, Apr 29, 1983.
  3. Papers on Mechanical and Physical Subjects: The sub-mechanics of the universe. By Osborne Reynolds, Arthur William Brightmore, William Henry Moorby. The University Press, 1903.


  • SUMO
    • "Intuitively, the class of things that happen and have temporal parts or stages. Examples include extended events like a football match or a race, actions like Pursuing and Reading, and biological processes. The formal definition is: anything that lasts for a time but is not an Object. Note that a Process may have participants 'inside' it which are Objects, such as the players in a football match. In a 4D ontology, a Process is something whose spatiotemporal extent is thought of as dividing into temporal stages roughly perpendicular to the time-axis.")