Special RelativityQUESTION: What is Special Relativity?ANSWER:
Special relativity or what is better know as The Theory of Special Relativity was born in 1905 by Albert Einstein. The theory took our understanding of the physics of our world from a simple, easily comprehensible, intuitive absolute frame of reference to a relative frame of reference where everything seems more like science fiction than real science. To add insult to injury, all subsequent experiments have supported his theory and left our intuition in a pile of rubble. Although, this really has little effect on our daily lives, it effects our perception of time, space, our universe and its origins. It is with great difficulty that we grasp completely what the theory is about and with more difficulty its implications on our worldview.
Although Newton knew well that velocity could be described in relative terms between two inertial (constant velocity) reference frames, he believed in the existence of some kind a fixed inertial reference frame that was stationary. This view had as its foundation a fixed medium referred to as ether on which the motion of bodies, light and other electromagnetic waves could propagate. This is similar to the necessity of air to transmit sound waves. One discovery blew this absolute reference frame out of the water.
The discovery was, although all other velocities are relative, the velocity of light was absolute. This was learned by a series of Michelson-Morley experiments. The tests showed that regardless of whether the speed of light was measured with the measuring device going toward or away from a light source at a great speed, the speed of light was measured to be the same value of 186,000 miles per second. This result was a huge shock to the scientific world. This discovery formed the main basis for special relativity.
The other primary postulate used as a basis for special relativity was that the same laws of physics apply in any and all inertial reference frames.
Using these postulates and the Lorenz transform equations to mathematically equate two relative inertial reference frames, Einstein's theory resulted in some very strange and difficult to believe outcomes. Some of these include shrinking of lengths, slowing down of time, clocks aging, etc. and warping of the space-time continuum. A space traveler could travel in space at high rates of speed and return younger than his twin brother.
One of the strangest parts of special relativity is the conclusion that two observers who are moving relative to one another, will get different measurements of the length of a particular object or the time that passes between two events. Consider two observers, each in a space-ship laboratory containing clocks and meter sticks. The space ships are moving relative to each other at a speed close to the speed of light. Based upon Einstein's theory each observer will see the meter stick of the other as shorter than their own, by the same factor. This is called length contraction. Also each observer will see the clocks in the other laboratory as ticking more slowly than the clocks in his/her own, by the same factor. This is called time dilation. The fact that the clock differences are the same would not appear to support an aging difference. However, this paradox is resolved with either a Doppler analysis or using the Lorenz transform equations.
It is true that the speed of light is the maximum speed a body can travel within an inertial reference frame. However, without considering time dilation effects, no limit on speed applies. Since the speed of light is the maximum speed of information transfer, we can never view anything going faster than the speed of light in our inertial reference frame. Although, special relativity normally applies to non-accelerating bodies, an example of an accelerating spaceship can illustrate this point. If a spaceship would leave earth with a constant acceleration of gravity, based upon the time elapsed in the spaceship and the distance to points far away in space based upon original measurements on earth, the speed of the spaceship would not be limited to the speed of light. One implication of special relativity is that it is easier to understand how a transcendent God could exist that is beyond space and time.