The Origin Of Universe

"I seem to have been only like a boy playing on the seashore and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."

Sir Isaac Newton

Fifteen billion years ago, the entirety of our universe was compressed into the boundaries of an atomic nucleus. Known as the cosmic egg, or nutshell, or, more scientifically, as singularity, this is the moment before creation when space and time did not yet exist. According to the general cosmological models that explain our universe, an indescribable explosion, trillions of degrees in temperature on any measurement scale, created not only fundamental subatomic particles and thus matter and energy, but also space. Precisely at that point, the counter variable time started increasing, i.e. time was created. At this point in space and time the universe was extremely compact, dense, and hot, and the first three minutes determined the drastic change to what previously was the eggshell.

Because of the big explosion, the universe, as a unity of four dimensions, started to expand in every direction. This explosion is explained specifically by the famous theory of Big Bang. This is the most credible theory, as it is the only one supported by Einstein's General Theory of Relativity, and Hubble's Law on the Expansion of the Universe. Big Bang explains the initialization of space and time, the two main factors that did actually give a form to the universe. Nonetheless, the main problem arose when scientists started arguing about the structure of the universe basing their arguments on the Big Bang. As the universe started expanding because of the big explosion, it must have given a certain form or structure to the universe. A simple question was asked: "What is that structure like?" At that point, three main theories arose: the theories supporting the open structure, the flat structure, and the closed structure of the universe.

All of the three theories are well supported, but before contrasting them and showing which one is the most accurate, two essential definitions need to be provided. To understand the structure as a physical determinant of the universe, the concept of time as a dimension must be first comprehended. Time is the name of the mathematically defined real variable that calculates the units of the moments elapsed by any body in movement since when it started to move. By this definition, time can somehow be evidence for the behavior of the moving body at every point it has elapsed, defining so how the structure of the motion at that particular point was. Moreover, time is a dimension, as it returns the value of the measurement of any object's motion.

In addition to the definition of time, the notion of space-time must be considered as well. We live on an almost spherical planet, but, when we walk on a straight line, we assume it is not a curvature, whilst it is. On any celestial object, the distance between any two randomly chosen points is not a straight line, but a curve. For instance, earth is one out of many celestial bodies that have three dimensions. Mathematically, we name these dimensions as x, y, and z. These three real variables take values from an imaginary coordinative system we create in the space to refer to any object. If we take earth as a reference point, x, y, and z will all be set to zero. On earth, we measure time as uniquely changing for every moving body, but in the universe it's quite different. Every celestial object in the universe forms a certain curvature, i.e. if that object were not there, then the space at those coordinates would be a straight line, as observed horizontally, not a curve. Hence, the mass of every celestial body forms this curvature we refer to as universal gravity. For example, the mass of the sun is greater than that of the nine planets. Logically, the sun forms a larger curvature in its space, and all the nine planets are supposed to move around the sun, but, thanks to the action-reaction force, not towards the sun. The same way, our galaxy, the Milky Way, forms a very large curvature on the space and time it isÐ'... It may sound strange at first, but time may be curved as well. I mentioned that time is a dimension, a quantity: it returns a value of the measurement of motion. As x, y, and z are dimensions that return the values of the position of every object in space, and as they may determine the position of the curvature in that particular space (i.e. as they are curved), so is time. Einstein, in his General Theory of Relativity, unified time and space into a single geometrical concept: the space-time. Therefore, space-time may be curved just like the surface of a ball as it is kicked or as any other mass is placed on its surface. (Refer to the Appendix, picture 1-A for a visual understanding.)

The concept of time and space-time is important and philosophical, but mathematically derived. Going deeper into the space with modern telescopes, scientists fell into an on-going debate: what the structure of the universe is actually like. Nowadays, scientists, believers, or others are divided into three main groups: those that believe that the universe has boundaries, i.e. it has no relation with whatever is out of these boundaries (actually nothing), those that consider the universe a flat-open structure, and those that unite the two other theories. Before contrasting and comparing these theories, a prÐ"©cis defining both of them should be first considered.

One group believes in what they refer to as "the closed structure of the universe." This theory is mathematically supported, and contains many discrete and difficult-to-understand assumptions. The entire hypothesis is based on the state of the universe before the Big Bang, i.e. before the explosion, when the universe was inside the "egg shell." The shell is actually the boundary of the egg at every point around the egg. As the explosion occurred, this flexible shell started to expand in different directions, and the boundary (the shell) is still there. Hence, the universe, which is actually expanding non-stop, has no link with its external part, even though out of the boundaries there is no time and space (nothing).

The structure per se as explained by this theory is somewhat simple: because of the strong gravity in the universe, space is bent onto itself, making it rather like the surface of earth. If you start traveling at one point on earth and move straight, after some time you will reach the same point again. More scientifically, think of the universe as a sphere, and draw imaginary horizontal and vertical lines, like we do for planet earth. It is obvious that at every point you chose, the sphere has constant positive