Physical law

A physical law or a law of nature is a scientific generalization based on empirical observations. Laws of nature are conclusions drawn from, or hypotheses confirmed by scientific experiments. The production of a summary description of nature in the form of such laws is the fundamental aim of science. Laws of nature are distinct from legal code and religious Law, and should not be confused with the concept of natural law.

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:

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• true. By definition, there have never been repeatable contradicting observations.
• universal. They appear to apply everywhere in the universe. (Davies)
• simple. They are typically expressed in terms of a single mathematical equation. (Davies)
• absolute. Nothing in the universe appears to affect them. (Davies)
• eternal. Unchanged since first discovered (although they may have been shown to be approximations of more accurate laws—see "Laws as approximations" below), they appear to be unchanged since the beginning of the universe. It is thus presumed that they will remain unchanged in the future. (Davies)
• omnipotent. Everything in the universe apparently must comply with them. (Davies)
• "omniscient" (loosely speaking). The behavior of everything in the universe is automatically and immediately "known" to the laws. (Davies)
• generally conservative of quantity. (Feynman)
• often examples of symmetry. (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 there seems to be a connection between beauty and truth.

Related Topics:
Beauty - Truth

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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 strictly empirical. It is a summary observation of things as they are. A theory is 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 attempts to deal with why or how it happens.

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