Physics is the branch of science that deals with the structure of matter and the interactions between the fundamental particles of the universe.
In the wide sense, physics is concerned with all aspects of nature on both macroscopic and microscopic levels.
Its scopes of study encircle not only the behavior of objects under the action of acting forces but also the origin and nature of nuclear force, gravitational and electromagnetic fields.
Its objective is the formulation of a few comprehensive principles that bring together and explain all such phenomena.
What is physics?
It is the basic physical science. Even in recent researches physics and natural philosophy were used interchangeably for the science whose aim is the discovery and mathematically values of the fundamental laws of nature. As the modern sciences developed and became highly specialized, physics came to denote that part of physical science not included in engineering, astronomy, chemistry, and geology.
Physics plays a special role in all-natural sciences and such fields in which physical laws and values receive importance, bearing such names as psychophysics, biophysics, astrophysics, and geophysics. Physics can, at the base, be defined as the science of energy, matter, and motion. Its laws are typically expressed with precision and economy in the language of math.
In both experiments, the observation of phenomena under conditions that are controlled as precisely as possible and theoretical values, the formulation of a unified conceptual framework, play very special and complementary roles in the development of physics. The experimental result in measurements, which are compared with the outcome predicted by theory. A theory that easily predicts the results of experiments to which it is appropriate is said to incorporate a law of physics. However, a law is always subject to restriction modification or replacement to a limited domain, if a later experiment makes it compulsory.
The main aim of physics is to find a unified set of laws that governing matter, energy, and motion at the small subatomic level, at the macroscopic scale and out to the largest distances. This valuable goal has been realized to a notable extent. Although a completely unified theory about physics has not yet been achieved, a noticeably small set of physical laws appears able to account for all known phenomena. The field physics developed up to about the turn of the 20th century, known as classical physics, can largely account for the movement of macroscopic objects that move slowly with respect to the speed of light and for such phenomena as light, heat, sound, electricity and magnetism. The modern developments in theory of relativity and quantum mechanics that modify these laws insomuch as they move to higher speeds, very heavy massive objects, and to the small elementary particles of matter, such as electrons, protons, and neutrons.
The Scope of Physics
The organized branches of classical and modern physics are defined below.
Mechanics is defined as the study of the motion of objects under the action of applied forces. Classical mechanics is considered as a branch of applied mathematics. It consists of dynamics, kinematics and the description of motion. It also defines the study of the action of forces in producing either motion or static equilibrium. The subjects of quantum mechanics, neutron stars, subatomic particles, superfluidity, superconductivity, and other major phenomena, and relativistic mechanics, important when speeds approach to the 3×108 m/s.
In classical mechanics, the laws are initially considered for point particles in which the shapes, dimensions and other intrinsic properties of bodies are ignored. Thus in the first approximation, even the body is large as planets and the Sun is treated as point-like e.g., in calculating the orbital motion of planet. In rigid-body dynamics, the expending of bodies and their mass distributions are considered, but they are imagined to be incapable of deformation. The mechanics of deformable solids is elasticity; hydrodynamics and hydrostatics treat, respectively, fluids at rest or in motion.
It is a branch of physics that define the relationship of temperature and heat, and their relation to energy, radiation, work and properties of matter
Laws of Thermodynamics
The first law of thermodynamics tells us about the energy conservation principle of mechanics generalized to include heat. It tell us about all changes in an isolated system and energy remains constant
The second law of thermodynamics defines that heat will not flow from cooler place to the hotter place without the intervention of an external device (e.g., a refrigerator). The concept of entropy involves the measurement of the disorder of the particles through which to system is build. For example, if tossing a coin many times results in a random sequence of heads and tails, the result has a higher entropy than if heads and tails tend to appear in clusters. Another calculation of the second law is that the entropy of an isolated system never decreases with time.
The third law of thermodynamics define that the entropy is zero at the absolute zero temperature, corresponding to the most sequence possible state.
3. Statistical mechanics
The effect of statistical mechanics derives large properties of systems from the mechanical properties of their molecular components, assuming molecular chaos and the laws of probability.
4. The study of electricity and magnetism
Electricity and magnetism are known as the components of the unified field of electromagnetism. Particles with an electric charges that interact by an electric force and charged particles in motion produce magnetic forces as well. Many subatomic particles, like electron and proton and neutral neutron, behave like magnets.
As light consists of electromagnetic waves, the propagation of light can be considered as the branch of electromagnetism. However, it is usually studying with as a separate subject called optics. The data that deals with the tracing of light rays is known as geometrical optics, while the data that deal with the distinctive wave phenomena of light is called physical optics.
6. Atomic and chemical physics
It is the field of physics that studies the atoms as an isolated system of electrons and nucleus. It concerned with the arrangement pattern of electrons and the methods by which these arrangements change.