# Define Physical Law

Not all formulas are called physical laws. For example, regularities found by curve adjustment are called empirical formulas. In physics, a formula is called a law precisely when it meets the following conditions: it is part of a theory and has been satisfactorily confirmed by measurement or experiment at least within a certain range (e.g. for small mass densities or high field intensities). Therefore, the basic assumptions of all standard physical theories are laws, as are their logical consequences. In particular, the usual principles of variation, such as Hamilton`s, are fundamental laws. However, the equations of motion and field equations that these principles imply are derived laws (theorems); These are the laws of conservation caused by equations of motion and field equations. However, the distinction between fundamental and derived laws is contextual: what is a principle in one theory can be a theorem in another. For example, Newton`s second law of motion is a theorem in analytic dynamics, and the first principle of thermodynamics is a theorem of statistical mechanics. See Conservation Laws (Physics), Hamilton Principle, Physical Theory, Statistical Mechanics, Thermodynamic Principles, Methods of Variation (Physics) Physical laws differ from scientific theories in their simplicity. Scientific theories are generally more complex than laws; They have many components and are increasingly likely to change as the body of experimental data and analysis available evolves.

Indeed, a law of physics is a summary observation of strictly empirical questions, while a theory is a model that takes observation into account, explains it, links it to other observations, and makes verifiable predictions based on it. Simply put, while a law states that something is happening, a theory explains why and how something is happening. Well-established laws have indeed been declared invalid in some particular cases, but the new wording created to explain the discrepancies can be described as generalizing the originals rather than overturning them. That is, invalid laws have turned out to be only close approximations (see examples above), to which other terms or factors must be added to cover conditions not previously considered, such as: very large or very small scales of time or space, enormous velocities or masses, etc. Therefore, physical laws are not seen as immutable knowledge, but better as a series of improved and more accurate generalizations. Natural laws are different from law, whether religious or civil, and should not be confused with the concept of natural law. The “physical law” should also not be confused with the “physical law” – the term “physical law” usually also includes the laws of other sciences (e.g. biology). A universal declaration on nature and society, based on empirical observations of physical behavior, tested with scientific methods. A physical law, a scientific law, or a law of nature is a scientific generalization based on empirical observations of physical behavior. Empirical laws are usually conclusions based on repeated scientific experiments over many years that have been widely accepted in the scientific community. The creation of a summary description of nature in the form of such laws is a fundamental goal of science.

A physical law or objective model of type 1 is a constant relationship between two or more properties of a physical entity. In principle, each of these models can be conceptualized in different ways, i.e. as alternative laws of type 2. The history of theoretical physics is to a large extent a consequence of type 2 laws. Each of them is intended to provide a more accurate representation of the corresponding objective model or Type 1 law, which is considered constant and, in particular, unaffected by human efforts to capture it. Similarly, the history of engineering is, to some extent, a sequence of Type 3 laws or law-based rules of action, of which there are at least two for each Type 2 law. As for type 4 laws or laws of laws, they are of two types: scientific and philosophical. The general principle of covariance is of the first type, while the assumption that all events are lawful is a philosophical thesis.

Unlike the first, the truth of which can be verified, the principle of legality is irrefutable. See Theoretical Physics Often, those who understand mathematics and concepts well enough to understand the essence of physical laws also feel that they possess inherent intellectual beauty. Many scientists claim that they use intuition as a guide in the development of hypotheses because laws reflect 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 seemed to imply it. Several general properties of physical laws have been identified (see Davies (1992) and Feynman (1965), although not each of the characterizations is necessarily original for them. Physical laws are :* True, at least in their regime of validity. By definition, there have never been reproducible contradictory observations. *Universal. They seem to apply everywhere in the universe. (Davies, 1992:82) * Simply.

They are usually expressed as a single mathematical equation. (Davies)* Absolutely. Nothing in the universe seems to affect them. (Davies, 1992:82) * Stable. Unchanged since the first discovery (although they turned out to be approximations of more precise laws – see “Laws as approximations” below), * Almighty. Everything in the universe must seem to agree with them (according to observations). (Davies, 1992:83) * Generally conservative in the crowd. (Feynman, 1965: 59) * Often expression of existing homogeneities (symmetries) of space and time.

(Feynman)* Typically theoretically reversible in time (if not quantum), although time itself is irreversible. (Feynman) Often, those who understand mathematics and concepts well enough to understand the essence of physical laws also feel that they possess an inherent intellectual beauty. Many scientists claim that they use intuition as a guide in the development of hypotheses because laws reflect 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 seemed to imply it. Several general properties of physical laws have been identified (see Davies (1992) and Feynman (1965) as mentioned, although not each of the characterizations is necessarily original for them). Physical laws are: A physical law or a scientific law, according to the Oxford English Dictionary, “is a theoretical principle derived from certain facts, applicable to a group or class of defined phenomena, and can be expressed by the assertion that a particular phenomenon always occurs when certain conditions are present.” Physical laws are usually conclusions based on repeated scientific experiments and observations over many years that have been widely accepted in the scientific community. Creating a rough description of our environment in the form of such laws is a fundamental goal of science. These terms are not used in the same way by all authors. The distinction between natural law in the political-legal sense and natural law or physical law in the scientific sense is modern, both terms also being derived from physis, the Greek word for nature.

Most other laws are mathematical consequences of different mathematical symmetries (see Emmy Noether`s theorem as proof). For example, the conservation of energy is a consequence of the symmetry of time displacement (no moment of time is different from another), while the preservation of momentum is a consequence of the symmetry (homogeneity) of space (no place in space is different from another). The indistinguishability of similar particles (e.g. electrons or photons) leads to Dirac and Bose statistics, which leads to the Pauli exclusion principle for fermions and Bose condensation for bosons. The symmetry between time and the axis of spatial coordinates leads to Lorentz transformations, which in turn lead to the theory of special relativity. Symmetry between inertial and gravitational masses leads to the theory of general relativity and so on. Some laws are low (or high) limits of other more general laws (or, as scientists say, more fundamental laws). For example, Newtonian dynamics (which is based on Galilean transformations) is simply the low-velocity limit of the laws of special relativity (simply because the Galilean transformation arises from the Lorentz transformation at the low-velocity limit). Similarly, Newton`s law of gravity derives from general realism at the limit of low gravitational potential (relative to the square of the speed of light), and Coulomb`s law follows QED at great distances (relative to the range of weak interactions). In such cases, we naturally use simpler legislative approximations instead of more precise basic laws. Some of the most famous laws of nature can be found in Isaac Newton`s theories of (now) classical mechanics, presented in his Principia Mathematica, and Albert Einstein`s theory of relativity.

Other examples of natural laws include Boyle`s law of gas, conservation laws, the four laws of thermodynamics, etc. Despite the secular belief that natural laws are somehow given to God(s), there is no scientific evidence for this – because most laws are either simply definitions or statements of identity (or symmetry), regardless of their causes. Some extremely important laws are only definitions. For example, the central law of mechanics F = dp/dt (the second “law” of Newton`s mechanics) is not at all a law, but a mathematical definition of force (first introduced by Newton himself). The principle of least action (or principle of the stationary effect), the Schroedinger equation, the Heisenberg uncertainty principle and other laws fall into this category.

Posted on