The classical Theories are phenomenological theories. A phenomenological theory attempts to describe and summarize experimental facts within some limited domain of physics. It is not intended to describe everything in physics, but if it is a good phenomenological theory. It does not describe everything within the limited domain very accurately. The philosophically minded reader may want to remark that ultimately every physical theory is “phenomenological”, and that the difference between a basic theory and a, phenomenological theories is only a question of degree. As physics we recognize, however, a clear difference between the two kind of theories.
Our basic laws of nature are distinguished by their great generality; we are not aware of any exceptions to what they state. We regard them as true and exact and universally valid there is clear experimental evidence to the contrary. In contract to this, the laws contained in a phenomenological theory are recognized not to be of universal validity; We know that they are valid (i.e., sufficiently accurate) only in some limited domain of physics, and that outside this domain the, phenomenological theory may be completely Meaningless.

Written by : Rohit Dubey, Class: XII, School: D.H.T Saraswati Vidya Mandir, Nehru Nagar Ghaziabad 201001
Reference: Berkeley Physics Course.