What are the basic laws of physics

Physical law

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A physical law describes (mostly in mathematical form) states and their changes in a physical system by means of measurable, clearly defined physical quantities (parameters, variables).

Physical laws usually formulate relationships of change: They describe how an initial situation is changed into an end situation by a progressive function.

A physical law must be compatible with reproducible physical experiments. In common parlance, it is then also considered confirmed.

A physical law is always part of a physical theory, which must be uniform and free of contradictions and must be confirmed by practice. A theory whose predictions have not yet been confirmed can be more precisely characterized using the term hypothesis (such as string theory).

A closed theory is the set of laws that fully describe an entire field, such as: B. Maxwell's equations describe the entire classical electrodynamics. However, this only applies within the defined limits and models (ideal conductor, ideal vacuum, etc.).

Physical laws are mostly written in the language of mathematics, as this has the necessary logical and conceptual clarity. In addition, there are linguistic descriptions and illustrations of the relationships. Both the individual terms and the scope must be defined here.

The scientifically accepted laws of physics determine the material worldview prevailing in the 20th century. It is in contrast to a worldview in which nature is not exclusively behaves according to observable regularities, but also according to other (unobservable) principles, such as B. according to the will of higher beings or confinement.

Laws of nature as a mirror of scientific progress

Over time, seemingly independent laws have been traced back to an underlying context. An example of this are the numerous forces described in mechanics and the laws of their action, which in the end can all be traced back to electromagnetic interactions and gravity between and in the bodies involved.

The transition from classical mechanics to the theory of relativity shows that laws believed to be irrefutable can only prove to be a model for a special case (in this case: for small speeds and masses).

This consideration leads to the search for “ultimate” and fundamental laws, a world law with which “everything” can be explained and built up, comparable to the mathematical axioms. String Theory, Quantum Gravity, and Large Unified Theory are examples of these efforts.

Every natural law that can be reduced to a more general law only has the status of a model. This is an argument for the assumption that all the laws of nature known to us are in fact only constructs of the human mind.

The designation nature “law” suggests that nature behaves similarly to persons under the compulsion of laws; In fact, physics is an empirical science, and the “laws” it establishes are only descriptions of the behavior found.

Formulation scheme

In order to describe the processes exactly, laws of nature are usually formulated mathematically. An example of this is Isaac Newton's law of gravity. It reads: the attraction F. between two masses $ m_1 $ and $ m_2 $ is proportional to the size of the masses and inversely proportional to the distance square $ r ^ 2 $.

$ F = G \ frac {m_1 m_2} {r ^ 2}. $

G is a proportionality factor that sets the masses $ m_1 $ and $ m_2 $ and the inverse of the square of the distance $ 1 / {r ^ 2} $ in relation to one another. Since this factor, known as the gravitational constant, has exactly the same value in all examined physical systems and describes a fundamental physical interaction (the attraction of masses to one another), one speaks of a natural constant.

Examples of natural laws


The demarcation between natural laws and other confirmed or proven theorems is not always very sharp.

Many mathematical theorems have implications and applications that are central to science or engineering. That's the sentence The sum of the angles in the triangle in the plane is 180 degrees correct; but it is not a law of nature, but a mathematical theorem based on certain basic axioms of geometry.

In the applied branches of science and technology, numerous formulas are also used that describe certain relationships between physical measured variables with sufficient accuracy, without the underlying relationships being unambiguously clear. For all known applications, they can be used to successfully approximate result values ​​with an accuracy that is sufficient for the application purpose (empirical values). Such formulas are empirical or formulas empirical laws called. These formulas are not laws in the physical sense, they lack a theoretical basis. In some cases, however, these are ideal cases or simplifications of natural laws, the inaccuracy of which is kept within known limits and is sufficiently precise for a specific application. On the other hand, empirical formulas or formula sets do not necessarily have to take the correct units into account and often also use empirical parameters (dimensionless parameters). So-called rules of thumb are an extreme case of this.


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Popular literature

  • Richard P. Feynman: On the nature of physical laws. Piper, Munich 1990 ISBN 3-492-03321-0

Web links

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  • Nancy Cartwright: Philosophy of Science: Laws
  • Antony Eagle: Laws of Nature (Seminar materials: Causation and Explanation, Oxford 2005)
  • W. Russ Payne: What a Law of Nature is
  • Jonathan Schaffer: Causation and Laws of Nature: Reductionism, in: Hawthorne / Sider / Zimmerman 2007
  • Markus Schrenk: Bibliography on Laws of Nature, AHRC, Nottingham 2011.
  • Norman Swartz:Laws of Nature in the Internet Encyclopedia of Philosophy (English, including references)
  • Joe LoVetri: On the Metaphysics of Laws of Nature, Diss. Winnipeg, Manitoba 1993
  • Essays on the subject Laws of Nature in PhilSci Archive