RELATIVITY - I

An introduction to special relativity

Albert Einstein developed the special theory of relativity (or special relativity) in 1905. Before special relativity, there were a number of problems with the classical explanations of electromagnetism which in Einstein's view contradicted the principle of relativity.

Special relativity is based on two simple postulates:

1. The special principle of relativity: The laws of physics are the same for all observers, regardless of their velocity.

2. The speed of light in a vacuum (c) is constant: That is, everyone will always measure the speed of light as being the same (i.e. c = 299,798,458 m/s), regardless of their own velocity.

The important point here is that the speed of light is the same for all observers. Suppose you measure the speed of a beam of light travelling towards you and record it's speed as c. According to Newtonian (or classical) physics, if someone else travelling at 1 m/s (relative to you) were then to measure the speed of a beam of light travelling towards them, then they would measure the speed of light to be c + 1 m/s. However, this does not prove to be the case in practice - everyone records the same speed of light regardless of their velocity relative to each other. Einstein explained this by proposing that the way you view space and time to be different from the way the other person views space and time. The mathematical description of this became the special theory of relativity.

Special relativity remained controversial for many years after it's first publication. However, as experiments became more accurate, special relativity was accepted by the scientific community. Despite this, Einstein did not recieve a Nobel prize for this work - he was granted that honour for his work on the photo-electric effect.

The special relativity simulator, Warp, is an attempt to explain some of the strange consequences of special realativity. What does it mean that my view of space and time is different to your view? Well, if you follow the next few lessons and have a play with Warpthen hopefully you will understand...