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Encyclopedia > Physical law

A physical law, scientific law, or a law of nature is a scientific generalization based on empirical observations of physical behavior. Empirical laws are typically conclusions based on repeated scientific experiments over many years, and which have become accepted universally within the scientific community. The production of a summary description of nature in the form of such laws is a fundamental aim of science. In science, there are a specific number of established scientific laws, or physical laws as they are sometimes called, that are considered absolute and inarguable facts of the physical world. ... For the scientific journal named Science, see Science (journal). ... In philosophy generally, empiricism is a theory of knowledge emphasizing the role of experience in the formation of ideas, while discounting the notion of innate ideas. ... For other uses, see Observation (disambiguation). ... Part of a scientific laboratory at the University of Cologne. ... In the scientific method, an experiment (Latin: ex- periri, of (or from) trying) is a set of observations performed in the context of solving a particular problem or question, to support or falsify a hypothesis or research concerning phenomena. ... This article does not cite any references or sources. ...


Laws of nature are distinct from the law, either religious or civil, and should not be confused with the concept of natural law. Nor should 'physical law' be confused with 'law of physics' - the term 'physical law' usually covers laws in other sciences (e.g. biology) as well. For other uses, see Law (disambiguation). ... In the religious sense, law can be thought of as the ordering principle of reality; knowledge as revealed by God defining and governing all human affairs. ... Natural law or the law of nature (Latin: lex naturalis) is an ethical theory that posits the existence of a law whose content is set by nature and that therefore has validity everywhere. ... This is a discussion of a present category of science. ...

Contents

Description

Several general properties of physical laws have been identified (see Davies (1992) and Feynman (1965) as noted, although each of the characterizations is not necessarily original to them). Physical laws are:

  • True. By definition, there have never been repeatable contradicting observations.
  • Universal. They appear to apply everywhere in the universe. (Davies, 1992:82)
  • Simple. They are typically expressed in terms of a single mathematical equation. (Davies)
  • Absolute. Nothing in the universe appears to affect them. (Davies, 1992:82)
  • Stable. Unchanged since first discovered (although they may have been shown to be approximations of more accurate laws—see "Laws as approximations" below),
  • Omnipotent. Everything in the universe apparently must comply with them (according to observations). (Davies, 1992:83)
  • Generally conservative of quantity. (Feynman, 1965:59)
  • Often expressions of existing homogeneities (symmetries) of space and time. (Feynman)
  • Typically theoretically reversible in time (if non-quantum), although time itself is irreversible. (Feynman)

Often those who understand the mathematics and concepts well enough to understand the essence of the physical laws also feel that they possess an inherent intellectual beauty. Many scientists state that they use intuition as a guide in developing hypotheses, since laws are reflection of symmetries and there is a connection between beauty and symmetry. However, this has not always been the case; Newton himself justified his belief in the asymmetry of the universe because his laws appeared to imply it. This article or section is in need of attention from an expert on the subject. ... In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves. ... Symmetry is a characteristic of geometrical shapes, equations and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ... Space has been an interest for philosophers and scientists for much of human history. ... Look up time in Wiktionary, the free dictionary. ... Look up time in Wiktionary, the free dictionary. ... Fig. ... This article or section does not cite its references or sources. ... For beauty as a characteristic of a persons appearance, see Physical attractiveness. ... Sphere symmetry group o. ...


Physical laws are distinguished from scientific theories by their simplicity. Scientific theories are generally more complex than laws; they have many component parts, and are more likely to be changed as the body of available experimental data and analysis develops. This is because a physical law is a summary observation of strictly empirical matters, whereas a theory is a model that accounts for the observation, explains it, relates it to other observations, and makes testable predictions based upon it. Simply stated, while a law notes that something happens, a theory explains why and how something happens. The word theory has a number of distinct meanings in different fields of knowledge, depending on their methodologies and the context of discussion. ...


Examples

Main article: List of laws in science. See also: scientific laws named after people This is a list of physical laws discovered by science. ... This is a list of scientific laws named after people (eponymous laws). ...


Some of the more famous laws of nature are found in Isaac Newton's theories of (now) classical mechanics, presented in his Philosophiae Naturalis Principia Mathematica, and Albert Einstein's theory of relativity. Other examples of laws of nature include Boyle's law of gases, conservation laws, the four laws of thermodynamics, etc. Sir Isaac Newton FRS (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ... Classical mechanics (commonly confused with Newtonian mechanics, which is a subfield thereof) is used for describing the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. ... Newtons own copy of his Principia, with handwritten corrections for the second edition. ... “Einstein” redirects here. ... Two-dimensional analogy of space-time curvature described in General Relativity. ... Boyles law (sometimes referred to as the Boyle-Mariotte law) is one of the gas laws and basis of derivation for the Ideal gas law, which describes relationship between the product pressure and volume within a closed system as constant when temperature remains at a fixed measure; both entities... In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves. ... Thermodynamics (from the Greek θερμη, therme, meaning heat and δυναμις, dunamis, meaning power) is a branch of physics that studies the effects of changes in temperature, pressure, and volume on physical systems at the macroscopic scale by analyzing the collective motion of their particles using statistics. ...


Laws as definitions

Those laws which are just mathematical definitions (say, fundamental law of mechanics - second Newton's law  F = frac{dp}{dt}), or uncertainty principle, or least action principle, or causality - are absolutely correct (simply by definition). They are extremely useful - because they can not be violated nor falsified. For other uses, see Mechanic (disambiguation). ... Newtons laws of motion are the three scientific laws which Isaac Newton discovered concerning the behaviour of moving bodies. ... In quantum physics, the outcome of even an ideal measurement of a system is not deterministic, but instead is characterized by a probability distribution, and the larger the associated standard deviation is, the more uncertain we might say that that characteristic is for the system. ... The principle of least action was first formulated by Pierre-Louis Moreau de Maupertuis, who said that Nature is thrifty in all its actions. See action (physics). ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ...


Laws being consequences of mathematical symmetries

Other laws reflect mathematical symmetries found in Nature (say, Pauli exclusion principle reflects identity of electrons, conservation laws reflect homogeneity of space, time, and rotational symmetry of space-time). Laws are constantly being checked experimentally to higher and higher degree of accuracy. The fact that they have never been seen repeatably violated does not preclude testing them at increased accuracy, which is one of main goals of science. It is always possible for them to be invalidated by repeatable, contradictory experimental evidence, should any be seen. However, fundamental changes to the laws are unlikely in the extreme, since this would imply a change to experimental facts they were derived from in the first place. The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925. ... Look up homogeneity in Wiktionary, the free dictionary. ... Space has been an interest for philosophers and scientists for much of human history. ... Look up time in Wiktionary, the free dictionary. ... In special relativity and general relativity, time and three-dimensional space are treated together as a single four-dimensional pseudo-Riemannian manifold called spacetime. ...


Well-established laws have indeed been invalidated in some special cases, but the new formulations created to explain the discrepancies can be said to generalize upon, rather than overthrow, the originals. That is, the invalidated laws have been found to be only close approximations (see below), to which other terms or factors must be added to cover previously unaccounted-for conditions, e.g., very large or very small scales of time or space, enormous speeds or masses, etc. Thus, rather than unchanging knowledge, physical laws are actually better viewed as a series of improving and more precise generalisations.


Laws as approximations

Some laws only are approximations of other more general laws, and are good approximations with a restricted domain of applicability. For example, Newtonian dynamics (which is based on Galilean transformations) is the low speed limit of special relativity (since the Galilean transformation is the low-speed approximation to the Lorentz transformation). Similarly, the Newtonian gravitation law is a low-mass approximation of general relativity, and Coulomb's law is an approximation to Quantum Electrodynamics at large distances (compared to the range of weak interactions). In such cases it is common to use the simpler, approximate versions of the laws, instead of the more accurate general laws. “Gravity” redirects here. ...


Origin of laws of nature

Some extremely important laws are simply definitions. For example, the central law of mechanics F = dp/dt (Newton's second "law" of mechanics) is often treated as a mathematical definition of force. Although the concept of force predates Newton's law [1], there was no mathematical definition of force before Newton. The principle of least action (or principle of stationary action), Schroedinger equation, Heisenberg uncertainty principle, causality and a few other laws also fall into this category (of mathematical definitions). Sir Isaac Newton FRS (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ... The principle of least action was first formulated by Pierre-Louis Moreau de Maupertuis, who said that Nature is thrifty in all its actions. See action (physics). ... The principle of stationary action for the Action (physics) S (a measure of the energy of the system under study) states that the variation in S is at an extremum, in symbols: where the independent variables are denoted by a set of acting at some time t. ... In physics, the Schrödinger equation, proposed by the Austrian physicist Erwin Schrödinger in 1925, describes the time-dependence of quantum mechanical systems. ... Werner Heisenberg Werner Karl Heisenberg (December 5, 1901 – February 1, 1976) was a celebrated German physicist and Nobel laureate, one of the founders of quantum mechanics. ... In quantum physics, the outcome of even an ideal measurement of a system is not deterministic, but instead is characterized by a probability distribution, and the larger the associated standard deviation is, the more uncertain we might say that that characteristic is for the system. ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ...


Most of the other fundamental physical laws are mathematical consequences of various mathematical symmetries. Specifically, Noether's theorem connects the fundamental conservation laws to symmetries. For example, conservation of energy is a consequence of the shift symmetry of time (no moment of time is different from any other), while conservation of momentum is a consequence of the symmetry (homogeneity) of space (no place in space is special, or different than any other). The indistinguishability of all particles of each fundamental type (say, electrons, or photons) results in the Dirac and Bose statistics which in turn result in the Pauli exclusion principle for fermions and in Bose-Einstein condensation for bosons. The partial symmetry between time and space coordinate axes results in Lorentz transformations which in turn results in special relativity theory. Symmetry between inertial and gravitational mass results in general relativity, and so on. Symmetry is a characteristic of geometrical shapes, equations and other objects; we say that such an object is symmetric with respect to a given operation if this operation, when applied to the object, does not appear to change it. ... Noethers theorem is a central result in theoretical physics that shows that a conservation law can be derived from any continuous symmetry. ... Dirac is a prototype algorithm for the encoding and decoding (see codec) of raw video and sound. ... Bose or Bosé may refer to: People: (Bose is a Bengali, German, or Italian surname) Amar Bose, MIT professor; founder of the Bose Corporation Jagdish Chandra Bose, Indian physicist Rahul Bose, Indian actor Satyendra Nath Bose, 20th century physicist Subhash Chandra Bose (aka Netaji), a leader of the Indian independence... The Pauli exclusion principle, commonly referred to simply as the exclusion principle, is a quantum mechanical principle formulated by Wolfgang Pauli in 1925, which states that no two identical fermions may occupy the same quantum state. ... In particle physics, fermions are particles with half-integer spin, such as protons and electrons. ... A Bose–Einstein condensate is a phase of matter formed by bosons cooled to temperatures very near to absolute zero. ... In particle physics, bosons, named after Satyendra Nath Bose, are particles having integer spin. ... Look up time in Wiktionary, the free dictionary. ... Space has been an interest for philosophers and scientists for much of human history. ... The Lorentz transformation (LT), named after its discoverer, the Dutch physicist and mathematician Hendrik Antoon Lorentz (1853-1928), forms the basis for the special theory of relativity, which has been introduced to remove contradictions between the theories of electromagnetism and classical mechanics. ... For a less technical and generally accessible introduction to the topic, see Introduction to special relativity. ... In physics, an inertial frame of reference, or inertial frame for short (also descibed as absolute frame of reference), is a frame of reference in which the observers move without the influence of any accelerating or decelerating force. ... This article or section is in need of attention from an expert on the subject. ... For a less technical and generally accessible introduction to the topic, see Introduction to general relativity. ...


The inverse square law of interactions mediated by massless bosons is the mathematical consequence of the 3-dimensionality of space. In physics, an inverse-square law is any physical law stating that some quantity is inversely proportional to the square of the distance from a point. ... Space has been an interest for philosophers and scientists for much of human history. ...


So to large extent laws of nature are not laws of nature per se, but mathematical expressions of certain simplicities (symmetries) of space, time, etc. In other words, there are quantities (e.g. the origin of the coordinates for time and space, the identity of a specific electron) upon which nothing depends. Currently the search for the most fundamental law(s) and most fundamental object(s) of nature is synonymous with the search for the most general mathematical symmetry group that can be applied to the fundamental interactions.


The application of these laws to our needs has resulted in spectacular efficacy of science – its power to solve otherwise intractable problems, and made increasingly accurate predictions. This in turn resulted in design and implementation of variety of reliable transportation and communication means, in building more quality and affordable shelters, in creating variety of drugs, in finding new energy sources, in developing variety of entertainments, etc.


History and religious influence

Compared to pre-modern accounts of causality, laws of nature fill the role played by divine causality on the one hand, and accounts such as Plato's theory of forms on the other. Pre-industrial society refers to specific social attributes and forms of political and cultural organization that were prevalent before the advent of the Industrial Revolution and the rise of Capitalism. ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... PLATO was one of the first generalized Computer assisted instruction systems, originally built by the University of Illinois (U of I) and later taken over by Control Data Corporation (CDC), who provided the machines it ran on. ... Theory of Forms typically refers to Platos belief that the material world as it seems to us is not the real world, but only a shadow of the real world. ...


In all accounts of causality, the idea that there are underlying regularities in nature dates to prehistoric times, since even the recognition of cause-and-effect relationships is an implicit recognition that there are laws of nature. Prehistory (Greek words προ = before and ιστορία = history) is the period of human history prior to the advent of writing (which marks the beginning of recorded history). ...


Progress in identifying laws per se, though, was limited by the belief in animism, and by the attribution of many effects that do not have readily obvious causes—such as meteorological, astronomical and biological phenomena— to the actions of various gods,spirits, holy ghosts, supernatural beings, etc. Early attempts to formulate laws in material terms were made by ancient philosophers, including Aristotle, but suffered both from lack of definitions and lack of accurate observations (experimenting), and hence had various misconceptions - such as the assumption that observed effects were due to intrinsic properties of objects, e.g. "heaviness," "lightness," "wetness," etc - which were results lacking accurate supporting experimental data. Per se is a latin phrase used in english arguments. ... The term Animism is derived from the Latin anima, meaning soul.[1][2] In its most general sense, animism is simply the belief in souls. ... Meteorology is the scientific study of the atmosphere that focuses on weather processes and forecasting. ... Astronomy, which etymologically means law of the stars, (from Greek: αστρονομία = άστρον + νόμος) is a science involving the observation and explanation of events occurring outside Earth and its atmosphere. ... Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology is the science of life (from the Greek words bios = life and logos = word). ... Look up deity in Wiktionary, the free dictionary. ... The English word spirit comes from the Latin spiritus (breath). // The English word spirit comes from the Latin spiritus, meaning breath (compare spiritus asper), but also soul, courage, vigor, ultimately from a PIE root *(s)peis- (to blow). In the Vulgate, the Latin word translates Greek (πνευμα), pneuma (Hebrew (רוח) ruah), as... Holiness means the state of being holy, that is, set apart for the worship or service of a god or gods. ... For other uses, see Ghost (disambiguation). ... A legendary creature is a mythical or fantastic creature (often known as fabulous creatures in historical literature). ... Aristotle (Greek: AristotélÄ“s) (384 BC – 322 BC) was a Greek philosopher, a student of Plato and teacher of Alexander the Great. ... Look up definition in Wiktionary, the free dictionary. ... A physical property is any aspect of an object or substance that can be measured or perceived without changing its identity. ... For other uses, see Data (disambiguation). ...


The precise formulation of what are today recognized as correct statements of the laws of nature did not begin until the 17th century in Europe, with the beginning of accurate experimentation and development of advanced form of mathematics (see scientific method). (16th century - 17th century - 18th century - more centuries) As a means of recording the passage of time, the 17th century was that century which lasted from 1601-1700. ... For other uses, see Europe (disambiguation). ... Scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. ...


Despite widespread lay belief that laws of nature are somehow "god-given," there is no scientific evidence of this, because practically all laws are either simply definitions, or statements of independence of anything on certain quantities like time, space, phase, etc - see laws and symmetry above. Sphere symmetry group o. ...


In essence, modern science aims at minimal speculation about metaphysics, and laws of nature are the result. This results in spectacular efficiency of science both in explaining how universe works and in making our life better, longer and more interesting (via building effective shelters, transportation, communication and entertainment as well as helping to feed population, cure diseases, etc). Plato (Left) and Aristotle (right), by Raphael (Stanza della Segnatura, Rome) Metaphysics is the branch of philosophy concerned with explaining the ultimate nature of reality, being, and the world. ...


Significance, and renown of discoverers

Because of the understanding they permit regarding the nature of our existence, and because of their above-mentioned power for problem-solving and prediction, the discoveries or defining (creation) of the new laws of nature are considered among the greatest intellectual achievements of humanity. Due to their subtlety, their discovery has typically required extraordinary powers of observation and insight, and their discoverers are typically considered among the best and brightest by others in their fields, and, notably in the cases of Newton, Einstein, Emmy Noether, in the general populace as well. Sir Isaac Newton FRS (4 January 1643 – 31 March 1727) [ OS: 25 December 1642 – 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ... “Einstein” redirects here. ... Amalie Emmy Noether [1] (March 23, 1882 – April 14, 1935) was a German-born mathematician, said by Einstein in eulogy to be [i]n the judgment of the most competent living mathematicians, [...] the most significant creative mathematical genius thus far produced since the higher education of women began. ...


Other fields

Some mathematical theorems and axioms are referred to as laws because they provide logical foundation to empirical laws. Euclid, Greek mathematician, 3rd century BC, as imagined by by Raphael in this detail from The School of Athens. ... Look up theorem in Wiktionary, the free dictionary. ... This article is about a logical statement. ...


Examples of other observed phenomena sometimes described as laws include the Titius-Bode law of planetary positions, Zipf's law of linguistics, Moore's law of technological growth. Many of these laws fall within the scope of uncomfortable science. Other laws are pragmatic and observational, such as the law of unintended consequences. By analogy, principles in other fields of study are sometimes loosely referred to as "laws". These include Occam's razor as a principle of philosophy and the Pareto principle of economics. The Titius-Bode law (or Bodes law) is the observation that orbits of planets in the solar system closely follow a simple geometric rule. ... Originally, Zipfs law stated that, in a corpus of natural language utterances, the frequency of any word is roughly inversely proportional to its rank in the frequency table. ... Gordon Moores original graph from 1965 Growth of transistor counts for Intel processors (dots) and Moores Law (upper line=18 months; lower line=24 months) For the observation regarding information retrieval, see Mooers Law. ... Uncomfortable science is the term coined by statistician John Tukey for cases in which there is a need to draw an inference from a limited sample of data, where further samples influenced by the same cause system will not be available. ... Unintended consequences can be either positive, in which case we get serendipity or windfalls source of problems, according to the Murphys law definitively negative: perverse effect, which is the opposite result to the one intended The Law of unintended consequences holds that almost all human actions have at least... For the House episode, see Occams Razor (House episode) Occams razor (sometimes spelled Ockhams razor) is a principle attributed to the 14th-century English logician and Franciscan friar William of Ockham. ... The philosopher Socrates about to take poison hemlock as ordered by the court. ... The Pareto principle (also known as the 80-20 rule, the law of the vital few and the principle of factor sparsity) states that, for many events, 80% of the effects comes from 20% of the causes. ... ‹ The template below is being considered for deletion. ...


See also

Philosophy of science is the study of assumptions, foundations, and implications of science, especially in the natural sciences and social sciences. ... Scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. ... Aristotle appears first to establish the mental behaviour of induction as a category of reasoning. ... In physics, a physical constant is a physical quantity of a value that is generally believed to be both universal in nature and not believed to change in time. ...

References

  1. ^ E.g. in the science of statics, as propounded by Galileo and his predecessors.

Statics is the branch of physics concerned with physical systems in static equilibrium, that is, in a state where the relative positions of subsystems do not vary over time, or where components and structures are at rest under the action of external forces of equilibrium. ... Galileo can refer to: Galileo Galilei, astronomer, philosopher, and physicist (1564 - 1642) the Galileo spacecraft, a NASA space probe that visited Jupiter and its moons the Galileo positioning system Life of Galileo, a play by Bertolt Brecht Galileo (1975) - screen adaptation of the play Life of Galileo by Bertolt Brecht... For the member of the National Assembly for Wales, see Paul Davies (Welsh politician). ... The Mind of God is a 1992 non-fiction book by Paul Davies. ... This article is about the physicist. ...

External links


  Results from FactBites:
 
Physical law - Wikipedia, the free encyclopedia (1504 words)
A physical law, scientific law, or a law of nature is a scientific generalization based on empirical observations of physical behavior.
Laws of nature are distinct from the law, either religious or civil, and should not be confused with the concept of natural law.
Inverse square law of interactions mediated by massless bosons is the mathematical consequence of 3-dimensionality of space.
Physics - Crystalinks (3771 words)
Physics is the science that deals with the structure of matter and the interactions between the fundamental constituents of the observable universe.
Physics plays an important role in all the natural sciences, however, and all such fields have branches in which physical laws and measurements receive special emphasis, bearing such names as astrophysics, geophysics, biophysics, and even psychophysics.
Taken together, these mechanical laws in principle permit the determination of the future motions of a set of particles, providing their state of motion is known at some instant, as well as the forces that act between them and upon them from the outside.
  More results at FactBites »

 
 

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