Chapter S2, Problem 1EAP

To determine

The definition of theory of relativity and explain how does special relativity differ from general relativity.

Explanation of Solution

Introduction:

Albert Einstein developed two theories of relativity that is general relativity and special relativity. These two interrelated theories are combiningly called theory of relativity. General theory of relativity deals geometric theory of gravitation and its relation with other forces of nature. It will be applicable to cosmological and astrophysical realm, including astronomy.Special theory of relativity speaks about relation between space and time. It mainly describes interaction and all other physical phenomena related to elementary particles except gravity.

General relativity and special relativity are combiningly called as Theory of relativity.

Special relativity is based on two postulates, they are:

1. Laws of physics are invariant in all inertial frames of reference
2. The speed of light in vacuum will remain constant for all observers, irrespective of the motion of light source.

Based on these postulates Einstein theorized that time must vary according to the speed of the moving object in order to keep the velocity of light invariant and this holds true in special case, the absence of gravitational field.

General relativity generalizes special relativity and Newton’s law of universal gravitation giving unified explanation of gravity as a geometric property of space-time. It proposes gravity is not a force as understood by Newtonian physics, but a curved field in space-time continuum that is created by presence of mass. In specific curvature of space-time is directly related to energy and momentum of matter/radiation present.

Conclusion:

General relativity explains the curvature of space-time with the help of laws of gravity and special relativity is a special case of general relativity that is when gravity is absent. These two theories together known as general theory of relativity.