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Physical phenomenon
From Wikipedia, the free encyclopedia
A physical phenomenon is a phenomenon that is describable by physics and involved with some form of matter, energy, or spacetime. Physical phenomena are usually regarded as, at least in theory, subjects of observation - Niels Bohr, one of the founding fathers of quantum mechanics, is quoted as saying "no phenomenon is a phenomenon until it is an observed/observable phenomenon."
Phenomena are usually associated with change, but not necessarily immediately visible change. One of the goals of physics is to group phenomena into classes with common causes and patterns. For example, Isaac Newton observed that while an apple might fall from a tree, and the moon, very large and massive, does not fall from the sky, both phenomena are caused by gravity. A related observation, made by Johannes Kepler after painstaking observations, was that the planet Mars also travels in an elliptical orbit due to gravity. Another related observation, first made by James Bradley, an astronomer, is that by carefully plotting the position of a nearby star it appears to move in an ellipse over the course of a year.
- Jeremy Bernstein, A Theory for Everything, Copernicus, An imprint of Springer-Verlag, New York, 1996, hardback, ISBN 0-387-94700-0