The Theory Of Special Relativity, By Alexander Einstein

Introduction
Over the past century science, physics in particular, has developed beyond any reasonable expectation. Some of the best work was done by the great minds such as James Clerk Maxwell, Niels Bohr, Werner Heisenberg, Alexander Friedmann, etc. The list goes on but some of the best work was from Albert Einstein. Much of his work was done during the beginning of the 20th century and then later on he was joined by other great minds to form a new field in physics called cosmology.
In 1905 Albert Einstein published four papers, two of which were on The Photoelectric Effect and another on The Theory of Special Relativity (The latter being highly inspired by Maxwell’s work on electrodynamics). Special Relativity is basically the theory of
Everybody until that point had believed that the universe was static, even Albert Einstein himself tried to modify the equations of General Relativity to allow for a static universe. They were all wrong! In 1929 an American astronomer named Edwin Hubble was (1) studying the redshift from other galaxies when he noticed that they were moving away from ours. Alexander Friedmann had earlier solved the equations of General Relativity to show models of the universe where the universe was actually expanding despite Einstein modifying them to allow for a static universe. Combining the Friedmann models with Hubble’s observations, it was concluded that the universe was in fact expanded. Einstein changed back the equations and called the earlier modification the biggest blunder of his
In actuality the the big bang refers to the time the universe started expanding but the expansion was so quick that to an observer (don’t ask where the observer would be) it would look like a huge explosion. The big bang theory is based on the Friedmann models, according to these models there are three possible geometries the universes could have taken when it started: a closed, open and flat geometry. (2)
A closed universe would expand for some time and then after some time the expansion would eventually stop and it would start contracting. It would contract until it it reaches the singularity. Some people have gone as far as suggesting that perhaps the universe has been expanding and contracting for a long time. A closed universe would also be finite in size, though it wouldn’t have any edges. This means that if one was to get on a spaceship and go upwards and keep going, they would eventually return to the same place from the bottom due to the curvature. In a closed geometry (2) some rules of mathematics would be different, for example, in the picture above the angles inside a triangle do not add up to