Epilogue: Relativity and Quantum Theory

Abstract

Classical mechanics is superseded as a physical theory by relativity and quantum theory, but it still has a critical part to play in our understanding of the world. First, and most obviously, as an approximation. The fact that tests of relativity and quantum theory require delicate experiment and very precise observation is testament to the great precision of the Newtonian theory as a description of everyday phenomena. It still underpins a huge range of engineering and scientific applications.

Second, as a paradigm of a good theory. Other applications of mathematics, in economics, biology, and so forth, seek to emulate its self-consistency, clear mathematical framework, and strong predictive power.

Third, even in the areas in which we now know that it is inapplicable, classical mechanics is still very important as a source of technical tools and, in quantum theory, as the framework for interpretation.