Since Galileo and Kepler, physics has been written in the language of mathematics. Physical laws formalize experimental results and observations. Over the following centuries, the various branches of natural science were studied separately, as distinct disciplines, each with its own characteristics and laws. But physicists soon began seeking a "unified" understanding of nature. In the 17th century, Isaac Newton reconciled celestial and terrestrial mechanics. In the 19th century, James Clerk Maxwell, building on Michael Faraday's experimental research, unified optics with the theories of electricity and magnetism. From 1905 to 1916, Albert Einstein brought together the geometric theory of spacetime and gravitation. Toward the end of his life, he searched unsuccessfully for a unified field theory that would combine general relativity and electromagnetic theory in a single model. Yet the path taken by 20th-century physics diverged from the course Einstein had charted.
Toward the Standard Model
=========================================================================
Quantum physics focused on the behavior of microscopic objects conventionally known as particles. After the first theory of quantum physics was developed in the late 1920s, a number of physicists turned their attention to the structure of atomic nuclei. The discovery of more or less elementary particles involved in transformations of the constituents of matter revealed several types of interaction beyond those already known.
