Question

Write an Essay of 300 words escribing one of the followin physiist. Be sure to include their big contribution to science and explain the theory or theories they propose.

1. Albert Einstein/ theory of relativity

2. Sir Isaac Newton / theory of gravity

3. Johannes Kepler / law of planetary motion

Answer 1

Albert Einstein was one of the great physicists of 20th century. He borned in Germany at 14 March 1879. Einstein developed one of the major breakthroughs of 20th centuty as "Theory of Relativity". He also developed theory behined the Photoelectric effect which helped in development of Quantum mechanics. He received Nobel prize for Physics in 1921 for Photoelectric effect explanation. In his early days of research Einstein realized that Newtonian Machanics is not enough to explain motion of the objects moving with very high speed. This led to the development of Special Theory of Relativity. In this theory he successfully exolained the phenomena of mass variation, length contraction, Time dilation, spontaneity etc. in the absence of gravity. Later he realized that this theory could be extended to the gravitational fields. He then constructed " GENERAL THEORY OF RELATIVITY".

In Special Theory of Relativity he developed a famous equation named " Mass Energy formula" E=Mc^2.

Postulates of Special theory of relativity are

1. The laws of physics are invarient in all inertial frames.

2. Speed of light is frame independent. In vacuum it has a value equal to 3×10^8 irrespective of the motion of source or observer.

Based on these two postulates he successfully developed the Mathematical form of Special Theory of relativity which led to construction of the Nuclear Fission and fusion.

In General theory of relativity Einstein explained the stucture of universe. General theory of relativity says that gavity is a geometric property of spacetime. The curvature of Spacetime has a direct relation with the momentum and energy present.