Physics is a branch of study that examines the composition of matter and the interactions between its basic elements. Physics, which derives from the Greek word physikos, is the study of nature in all its manifestations, both on a macroscopic and microscopic scale. Its field of study includes the nature and genesis of gravitational, electromagnetic, and nuclear force fields in addition to the behavior of things when subjected to certain forces. The creation of a few broad principles that unite and explain all of these different occurrences is its ultimate goal.
The foundation of physical science is physics. The science whose goal is the discovery and articulation of the fundamental laws of nature has been referred to as physics or natural philosophy up until quite recently. Modern physics now refers to the branch of physical science that is not covered by astronomy, chemistry, geology, or engineering as the modern sciences have developed and become more specialized. However, physics plays a significant part in all of the natural sciences, and each of these subjects has subfields that focus specifically on physical principles and measurements. These subfields go by titles like astrophysics, geophysics, biophysics, and even psychophysics. The fundamental definition of physics is the study of matter, motion, and energy. Mathematical language is often used to convey its laws concisely and precisely.
In order to develop physics, it is vital and complimentary for both theory and experiment, which involves the observation of phenomena under as precisely controlled conditions as possible, to be conducted. Measurements from physical experiments are compared to the results predicted by theory. A theory is considered to include a physical law when it can accurately anticipate the outcomes of tests to which it is applicable. A law is, however, always open to being changed, replaced, or restricted to a smaller area if a subsequent experiment deems it essential.
Finding a coherent set of principles regulating matter, motion, and energy at small (microscopic) subatomic distances, at the human (macroscopic) scale of daily life, and out to the biggest distances is the ultimate goal of physics (e.g., those on the extragalactic scale). This challenging objective has been substantially achieved. A relatively small collection of fundamental physical principles seems to be able to explain all known events, despite the fact that a totally unified theory of physical phenomena has not yet been reached (and likely never will be). The branch of physics known as classical physics, which was established up until roughly the turn of the 20th century, can largely explain the motions of macroscopic objects that move slowly in relation to the speed of light as well as phenomena like heat, sound, electricity, magnetism, and light. Insofar as they apply to faster moving objects, extremely heavy objects, and the small elementary building blocks of matter like electrons, protons, and neutrons, the current breakthroughs of relativity and quantum mechanics change these principles.
