THEORY OF RELATIVITY

The theory of relativity, or simply relativity in physics, usually encompasses two theories by Albert Einstein: special relativity and general relativity.[1] (The word relativity can also be used in the context of an older theory, that of Galilean invariance.)

ATOMIC THEORY

In chemistry and physics, atomic theory is a scientific theory of the nature of matter, which states that matter is composed of discrete units called atoms, as opposed to the earlier[citation needed] concept which held that matter could be divided into any arbitrarily small quantity. It began as a philosophical concept in ancient Greece (Democritus) and entered the scientific mainstream in the early 19th century when discoveries in the field of chemistry showed that matter did indeed behave as if it were made up of particles.

BIG BANG THEORY

Big Bang theory is the prevailing cosmological model that describes the early development of the Universe.According to the theory, the Big Bang occurred approximately 13.798 billion years ago, which is thus considered the age of the universe.At this time, the Universe was in an extremely hot and dense state and began expanding rapidly. After the initial expansion, the Universe cooled sufficiently to allow energy to be converted into various subatomic particles, including protons, neutrons, and electrons.

CONTINENTAL DRIFT THEORY

Continental drift is the movement of the Earth's continents relative to each other by appearing to drift across the ocean bed.[1] The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed by Alfred Wegener in 1912. The theory of continental drift was superseded by the theory of plate tectonics, which explains how the continents move.

GEOCENTRIC THEORY

In astronomy, the geocentric model (also known as geocentrism, or the Ptolemaic system), is a description of the cosmos where Earth is at the orbital center of all celestial bodies. This model served as the predominant cosmological system in many ancient civilizations such as ancient Greece. As such, they assumed that the Sun, Moon, stars, and naked eye planets circled Earth, including the noteworthy systems of Aristotle (see Aristotelian physics) and Ptolemy.[1]