A law of physics is a mathematical relationship between
measurable quantities that describe the physical state and
properties of bodies. This is a fundamental concept in physics.
Collectively, the laws of physics are those physical theories which
have been widely published and tested, and are considered by the
scientific community in general to be valid. They also tend to be very
general, basic theories: instead of having a large list of laws governing
many different phenomena in different circumstances, special cases are
arrived at through a particularization of basic ideas. Well-known laws of physics include
Einstein's theory of general relativity, Newton's laws of motion,
Maxwell's equations for electricity and magnetism, and the theory of
Quantum mechanics.
Interestingly, these so-called "laws" can essentially be viewed as a
series of approximations: well-established physical laws are found to be
invalid in some special cases, and the new theory created to explain these
discrepancies can be said to have generalized the original, rather than
superseded it. One well-known example is that of Newton's law of
gravity: while it described the world accurately in most normal
circumstances, such as the movement of the planets around the sun, it was
found to be inaccurate when applied to very large masses or very high
velocities. Einstein developed the theory of general relativity, which
accurately handled gravitational interactions both those extreme conditions
and in the range occupied by Newton's law. However, Newton's formula for
gravity is still used in most circumstances, as an easier-to-calculate
approximation of gravitational interaction. The same phenomena can be
observed when comparing Maxwell's Equations with the theory of
quantum electrodynamics, and in other cases.
It would be nice to guarantee that some law in physics is 100% correct for all possible situations. But in physics, laws cannot be proven in the same fashion a mathematical theorem can. They can always be invalidated, however, by experimental evidence.
