# Relativity

During the opening years of the 20th Century, a clerk by the name of Albert Einstein submitted a theory called Relativity. This nifty piece of science has four main principles at its core:

1. There is no universal clock.
2. Mass and energy are equivalent.
3. Light is as fast as things can go.
4. Your relative speed affects how things are perceived.

### The Power and the Glory

The most familiar area of Relativity for most people is the famed equation E=mc2. This is the equation that describes the fundamental relationship between the energy gained by an object as its mass increases. Used to great effect in nuclear weapons and power plants, its impact on society is one of the greatest known. The fact that we can obtain such huge quantities of energy from the nuclei of atoms has changed the course of history. Never before had one discovery brought so much hope for an end to the energy crisis but also threatened the planet with the extinction of almost all life. Such is the power of this single equation in two variables.

It has been worked out that three main areas are affected by speed and these are the rate of time flow, length in direction of travel and mass of object. People say that these factors are only noticed at high relativistic velocities1 but they are seen more than you'd expect. Take mass for example, no matter how fast you run, you still seem to have gained in weight when it comes to the bathroom scales later. Time is the same in a way, no matter how slowly you are moving relative to the teacher at school time seems to be painfully slow. Conversely it seems to go very fast when you want it to slow down.

It can be concluded that either the speed of light is slower than we thought and is just going fast while the experiment is going on.

1This is the cool way of saying 'very, very fast'