Developed in the 1920's by great physicists Schrödinger, Pauli, Heisenberg, Bohr, Born,Fermi, Dirac and others, it describes the laws of nature for the subatomic world.
The Principles of Relativity along with Quantum Mechanics are the two most important achievements of the 20th century physics.
The standard models of cosmology -- the big bang theory without the inflationary theory -- had to suffer from the three problems, namely, the smoothness problem, the horizon problem, and the flatness problem.
The concept of string theory is one of the most popular concepts of the last 20 years in theoretical physics. Sometimes referred to as “a theory from the 21st century physics...
The classical Newtonian physics treated space and time as two separate entities and time was believed to be absolute. However, Einstein’s theories of relativity clarified that space and time are interconnected and that time has a shape and has only one direction.
The phrase "Theory of Everything" has been used in the scientific and semi-scientific community within the last 30 years. It usually refers to such a theory that formulates and unifies both quantum mechanics and the general theory of relativity.
One of the hottest topics in science fiction is time travel. The classic H.G. Wells story about time machine fascinated many generations of science fiction enthusiasts.