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Special Theory of Relativity

Special Theory of Relativity

Today when I visit a school some students come to near me. They were asking me about the special theory of relativity. One of the boys told me that he tried to understand the special theory of relativity but he was unable to understand. This article I am writing to especially those students who are interested in the special theory of relativity. But don’t know how to approach the subject.

The special theory of relativity is given by Einstein and it is valid for a special frame of reference. Special means frame of reference should be inertial. There are 2 postulates in the special theory of relativity. 1: All the laws of physics remain the same in all inertial frames. 2: The speed of light is a constant in all frame of reference.

Both the laws are incompatible with the old Galilean transformation of motion. So Einstein use knew Lorentz transformation. In Lorentz transformation, it becomes necessary to put space and time into the equal footing. Einstein uses 4 dimension space-time structure known as Minkowskian space-time or 4 dim geometry. Before Einstein Newtonian theory was compatible with 3 dim Euclidean space geometry.

To understand the idea behind 4-dimensional space-time, students should understand the motivation behind this theory. The problem arises due to Michelson Morley experiment and unsatisfactory explanation of motion of charged bodies.

Michelson Morley experiment and theory of electromagnetic waves propagating in ether mismatched with each other. To explain the negative result of Morley experiment Einstein use the special theory of relativity.

So students should have an idea about the Michelson Morley experiment. Actually it all due to the mysterious behavior of light. Today we know that light is an electromagnetic wave and it does not require any medium to propagate from one point to another point in the space. But initially, when physicists were trying to understand the light they don’t know at that time what is the nature and speed of light.

In the Michelson Morley experiment, scientists tried to calculate the speed of light with respect to the ether. We can say this experiment was for the detection of ether. But the result of the Michelson Morley experiment proves that there is no relative motion between ether and light. It means either ether is dragging with light or ether does not exist.

Many scientists give a different explanation and hypothesis to this result. But Einstein idea was breakthrough, in which he gives more importance to the light instead of absolute space-time structure. He gives the idea that space and time are not separate entities and not absolute. He used Lorentz transformation to verify his postulates.


Rahul Aggrawal      

The frame of Einstein       





Rahul Aggrawal

I am a teacher and a theoretical physicist. Physics gives me pleasure and teaching physics gives me stable happiness. For More info visit

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