Physical law

A physical law or scientific law is a theoretical statement "inferred from particular facts, applicable to a defined group or class of phenomena, and expressible by the statement that a particular phenomenon always occurs if certain conditions be present." Physical laws are typically conclusions based on repeated scientific experiments and observations over many years and which have become accepted universally within the scientific community. The production of a summary description of our environment in the form of such laws is a fundamental aim of science. These terms are not used the same way by all authors.

The distinction between natural law in the political-legal sense and law of nature or physical law in the scientific sense is a modern one, both concepts being equally derived from physis, the Greek word (translated into Latin as natura) for nature.

Several general properties of physical laws have been identified. Physical laws are:

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 in 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.

Many scientific laws are couched in mathematical terms (e.g. Newton's Second law F =  ^dp⁄_dt, or the uncertainty principle, or the principle of least action, or causality). While these scientific laws explain what our senses perceive, they are still empirical, and so are not "mathematical" laws. (Mathematical laws can be proved purely by mathematics and not by scientific experiment.)

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