Where better to start than with the definition of physics from the Oxford English Dictionary: The Definitive Record of the English Language:

Most twenty-first-century physicists would find this definition sufficiently allencompassing to describe what physics is about.Many, including the present author, would argue that the extensive nature of the subject and its emphasis upon model-building and problem-solving enables it to embrace a vastly wider range of cognate fields, including chemistry, biology, medicine and economics. But the mid-nineteenth-century scientist, and in particular one associated with Cambridge University, would have formed a very different view.

Discoveries in physics, 1687 to 1874

It is enlightening to study a time-line of major discoveries and advances in what we would now call physics, as well as selected topics from cognate disciplines such as chemistry, mathematics and particularly technology. The items in Table 1.1 span the period from the date of publication of Isaac Newton's Philosophiæ Naturalis Principia Mathematica (Newton, 1687) to the opening of the Cavendish Laboratory in 1874. The contents of the table are necessarily subjective but provide a broad-brush picture of the standard history of physics. The country and location where the advances were made, as well as those which originated in Cambridge, are also indicated.

There are a number of striking features of Table 1.1. There is no question about the overwhelming impact of Newton's laws of motion and of gravity of 1687. Newton and his followers promoted vigorously the corpus of Newton's great works in the sciences of mechanics, statics, dynamics, gravity and optics. Nowhere was this more assiduously practiced than in his alma mater, Cambridge University, where, well into the nineteenth century, Newton's approach to the laws of motion were taught to the exclusion of the more powerful mathematical methods of analysis which had been developed in continental Europe.