Special Theory of Relativity

In 1905, Albert Einstein published the special theory of relativity (deals only with the “special” case where gravity is ignored).

In 1916, he stunned the scientific world with the publication of his general theory of relativity. It illustrates how spacetime can be used to describe the behavior of how mass and light interact - it is an explanation of how gravity works.

Special theory deals with speeds close to the speed of light. It accurately describes how things look when something is moving at (or close to) the speed of light. It also explains the mass-energy equivalence (E = mc^2). The general theory of relativity is “general” because it applies to the physical laws that govern the universe with or without gravity.

Notice that it took Einstein 11 years to come up with how our universe works, i.e., the general theory of relativity. During the 11 years he worked diligently and consulted frequently with other pundits in the field of physics and mathematics.

Absolutes of Relativity

There are two “absolutes” of relativity and all of relativity follows from these two ideas:

1) “The laws of nature are the same for everyone.” [1]

There is no absolute frame of reference, and no absolute state of rest.

2) “The speed of light is the same for everyone.”[1]

The speed of light is the maximum possible speed, and it is always measured to have the same value by all observers.

Key Ideas of Special Relativity

  1. No material object can travel faster than light.

If you observe an object moving near light speed:

  1. Its time slows down - time dilation
  2. length contracts in direction of motion – length contraction
  3. Its mass increases .
  4. Whether or not two events are simultaneous depends on one’s perspective .
  5. ​Mass – Energy Equivalence, E = mc2 .

From a perspective of our “real life” experience, these sound pretty strange. How could time change? How could things look shorter in the direction of their motion? Is it really possible that mass of an object increases when that object moves close to the speed of light? Simultaneous events are not even simultaneous!

All of these phenomena have been verified experimentally!

“Relativity does not violate common sense because we have no common experience with speeds at which the effects of relativity become noticeable.” [1]