Relativity Theory
Relativity Theory is a branch of modern physics made famous by Albert Einstein ( pictured left ). Relativity theory accepts that current technology has no way of providing an absolute frame of reference from which to determine objective movement or location. Therefore it describes the relationships between all things in the universe using comparative or relative terms.

For example, depending upon your frame of reference, the Earth is moving through space at different speeds. Relative to the Sun, it is traveling at an orbital velocity of about 106,000 km/h. However the Sun is orbiting the center of our galaxy at about 792,000 km/h and the galaxy as a whole is moving at 2,160,000 km/h relative to the cosmic background radiation. The only constant by which the speed of anything can be compared is that of the speed of light, often symbolized by the letter C. By measuring the Doppler Effect of light emitted by a moving object such as a distant star, astronomers can estimate its speed and direction.