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.

Laws as approximations

Outside the scientific community, it is often assumed that the laws of nature have been proved beyond a doubt, in the same manner that mathematical theorems can be proven. However, this is not so. It is just that no instances have ever been seen where they are repeatably violated. 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 the basic structure of the universe, which would almost certainly make it immediately uninhabitable (see fine-tuned universe); if the laws were to change, we wouldn't be here to notice.

Related Topics:
Theorem - Proven - Fine-tuned universe

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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, 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 approximations.

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A well-known example is that of Newton's law of gravity: while it describes the world accurately for most pertinent observations, such as of the movements of astronomical objects in the solar system, it was found to be inaccurate when applied to extremely large masses or velocities. Einstein's theory of general relativity, however, accurately handles gravitational interactions at those extreme conditions, in addition to the range covered by Newton's law. Newton's formula for gravity is still used in most circumstances, as an easier-to-calculate approximation of gravitational law. A similar relationship exists between Maxwell's equations and the theory of quantum electrodynamics; there are several such cases. This suggests the (unanswered) question of whether there are any ultimately true physical laws, or whether they are all just cases where our sensory and rational apparatus have generated mathematically simple approximations, valid within the range of normal human experience, to unobtainable true formulas.

Related Topics:
Gravity - Solar system - Maxwell's equations - Quantum electrodynamics

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