- Physical system
physicsthe word system has a technical meaning, namely, it is the portion of the physical universechosen for analysis. 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 environment is a free choice, generally made to simplify the analysis as much as possible. An "isolated system" is one which has 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 decoherencethe "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.
Complexity in physical systems
complexityof a physical system is equal to the probabilityof its being in a particular state vector.
If one considers a classical Newtonian ball situation with a number of perfectly moving physical bodies bouncing off the walls of a container, the system-state probability does not change over time. The entropy of the system changes over time, but the probability of the state vector does not change. One can periodically evaluate the complexity of this system, and the complexity of this system does not change.
In a physical system, a lower probability state vector is equivalent to a higher complexity. A self sustaining low probability state vector allows the physical system to remain in a higher complexity state. The study of such systems as applied to our universe is in its infancy and speculative in nature, but it appears that there are some low probability systems that are able to sustain themselves through time.
mathematical systems, one can consider the complexity of particular states more easily. For example, if one considers a Turing machinethat generates random symbols and then utilizes these symbols as an algorithmto create a new series of symbols, the complexity of the final string of symbols is nearly mathematically equivalent to the minimum size of a string required to produce a larger string on a Turing machine as defined by algorithmic information theory.
The closed systems concepts in physics
Heisenbergnotes that in physics, there are actually four, possibly five, different conceptual developments of closed systems concepts:
* the first began with reference to Newtonian mechanics,
* the second with nineteenth century thermodynamics,
* the third throughout the twentieth century with Lorentz, Einstein, and Minkowski,
* and finally with conceptual developments in quantum theory and wave mechanics. The third and fourth stages eventually led to more open systems concepts, [ Heisenberg (1999) "Physics and Philosophy", New York: Prometheus Books, pp. 93-109.] but closed/open system concepts really need be considered in relation to work since that time if one were to define further conceptual developments.
* [http://ratjed.com/index.php?systems Conceptual vs Physical Systems]
* [http://www.nsf.gov/cise/kdi/ideas/algorithms.html Research in simulation and modeling of various physical systems]
Wikimedia Foundation. 2010.
Look at other dictionaries:
physical system — fizikinė sistema statusas T sritis Standartizacija ir metrologija apibrėžtis Materialieji objektai, sąlygiškai izoliuoti nuo aplinkos. atitikmenys: angl. physical system vok. physikalisches System, n rus. физическая система, f pranc. système… … Penkiakalbis aiškinamasis metrologijos terminų žodynas
physical system — fizikinė sistema statusas T sritis fizika atitikmenys: angl. physical system vok. physikalisches Einheitensystem, n; physikalisches System, n rus. физическая система, f pranc. système physique, m … Fizikos terminų žodynas
physical system — fizikinė sistema statusas T sritis chemija apibrėžtis Materialūs objektai, sąlygiškai izoliuoti nuo aplinkos. atitikmenys: angl. physical system rus. физическая система … Chemijos terminų aiškinamasis žodynas
physical system — noun The portion of the physical universe chosen for analysis, with everything outside the system known as the environment … Wiktionary
Cyber-physical system — A cyber physical system (CPS) is a system featuring a tight combination of, and coordination between, the system’s computational and physical elements. Today, a pre cursor generation of cyber physical systems can be found in areas as diverse as… … Wikipedia
physical science — physical scientist. 1. any of the natural sciences dealing with inanimate matter or with energy, as physics, chemistry, and astronomy. 2. these sciences collectively. [1835 45] * * * Introduction the systematic study of the inorganic world … Universalium
System of Physical Quantities — of Nikolay A. Plotnikov (SPQ) the classification of physical quantities or physical operators, that makes it possible to reveal their dependence on the geometry of space time and fundamental physical constants in the form of differential… … Wikipedia
Physical computing — Physical computing, in the broadest sense, means building interactive physical systems by the use of software and hardware that can sense and respond to the analog world. While this definition is broad enough to encompass things such as smart… … Wikipedia
physical science, principles of — Introduction the procedures and concepts employed by those who study the inorganic world. physical science, like all the natural sciences, is concerned with describing and relating to one another those experiences of the surrounding… … Universalium
Physical information — In physics, physical information refers generally to the information that is contained in a physical system. Its usage in quantum mechanics (i.e. quantum information) is important, for example in the concept of quantum entanglement to describe… … Wikipedia