What is Physics

Physics is always defined to be the science of explaining laws of nature and its mysteries. Physics is the most fundamental discipline of basic sciences. Since its evolution as a field of study, it keeps on changing every other day. This is because it always arises new questions and enforce logical thinking which ultimately leads to new discoveries. It is one of the most dynamic disciplines to study in modern days.

Central to the study of physics is energy and matter. It is also described as the science dealing with physical quantities. Physics is closely related to many other discipline like mathematics, chemistry etc. Mathematics is said to be the language of Physics. Numerical values, units etc are mathematical in nature and thus used to describe physical quantities accurately and precisely.

Theories of physics is supposed to evolve from natural philosophy. Since ancient times, people used to argue about matter and spirituality. Democritus, Thales, Aristotle, Ptolemy and Archimedes to name a few. Among them Democritus, Ptolemy and Archimedes theories are important to mention. Democritus was the first to put forward the idea of atom (derived from Greek word – TOM means “not to cut”). Archimedes is popularly known for his Eureka moment when he found the reasoning behind buoyancy while taking bath. Later he propounded his great principle of buoyancy. Furthermore, he is the one who gave the principle of density, invented simple machines like lever and pulley. Ptolemy was a great astronomer of his time. His work in ancient physics and astronomy in understanding universe passed on to great Islamic scholars of medieval period to scholars of china and India.

According to development of Physics theories, it is categorized in two category:

• Classical Physics (1600 – 1900):

Classical Physics starts with theories of great scientists Galileo and Newton. One of the most fundamental theories was propounded by Galileo Galilei called Law of inertia. Inertia is the most basic property of matter. Law of inertia compelled Newton to think differently that led him put forward his theories of mechanics popularly known as Newton’s Laws of Motion.

Isaac Newton is known as father of classical physics.

Topics which are generally studied under classical physics are:

• Newton’s Laws of Motion
• Universal law of Gravitation
• Hamiltonian Mechanics
• Lagrangian Mechanics
• Waves & Oscillation
• Laws of Thermodynamics
• Heat Engine
• Entropy of system
• Joule’s Law of Heating
• Coulomb’s Law
• Gauss’ Law
• Ohm’s Law
• Lenz’s Law
• Electromagnetic Induction

Areas of Classical Physics are:

1. Classical Mechanics: It deals with the study of motion of particle and fluids.
2. Thermodynamics: It deals with the study of temperature, heat transfer and properties of aggregation of particles.
3. Electromagnetism: It deals with the study of electricity, magnetism, waves and Optics.

The era of modern physics started with the theories of Relativity and Quantum mechanics. Limitations of classical physics to understand some natural phenomena led the path of modern physics. For example, Newton’s laws of motion explain dynamics of objects moving far less than speed of light perfectly to a good approximation but it fails to explain motion of object moving compared to speed of light. Maxwell-Boltzmann distribution explain clearly the behavior of gas at room temperature but at absolute zero it fails to explain and Bose-Einstein or Fermi-Dirac distribution is used to understand the behavior.

Below are the topics generally considered to be included as central to study of Modern Physics.

• Black Body Radiation
• Maxwell’s Electromagnetic theory of light
• Oil Drop Experiment
• Franck-Hertz Experiment
• Geiger – Marsden Experiment
• Gravitational lensing
• Michelson – Morley experiment
• Photoelectric effect by Albert Einstein
• Quantum Thermodynamics
• Radioactive Phenomena
• Theory of Relativity
• Wave – Particle duality
• Uncertainty Principle
• Solid State Physics

       Areas of Modern Physics are:

1. Quantum Mechanics
2. Relativity
3. Particle Physics
4. Atomic and Molecular Physics
5. Cosmology