<human>:  Can you explain the theory of relativity?
<bot>: The theory of relativity, put simply, states that the laws of physics are the same for all observers, regardless of their relative motion. This means that if two objects are moving relative to each other, they will each measure the same physical laws. For example, time will pass at the same rate for each observer regardless of their relative motion. The most famous example of this is the idea that time runs slower the faster an observer moves. This phenomenon is known as 'time dilation'. It is a consequence of the fact that light always moves at the same speed, regardless of the motion of the observer. This is because light, as a massless particle, is not affected by the same forces of gravity and acceleration that affect other particles. As a result, two observers moving at different speeds will measure different lengths of time for the same distance traveled. This is the major idea behind the theory of relativity.