Theories On Origin of the Universe

As far back as recorded history goes, there have been two sets of opposing ideas, beliefs, theories, or teachings about the origin of the universe. It has either existed eternally with no beginning or end, or it was created at some point in time and will eventually come to an end. In the first part we examined the early cultural, religious, and somewhat philosophical views of how the universe began. We've also spent a little time looking at some ideas about our own beginnings from a religious and scientific point of view. In this section, we're going to take a brief excursion through the various theories that science has put forth to explain the origin of the universe.
By far the most popular theory in science today is the big bang theory, the idea that the universe came into existence at a certain point in time roughly 15 to 20 billion years ago. In the last 25 years this theory has moved to the forefront of cosmology. You'll meet some of the key figures whose theories have laid the foundation for the big bang. However, as you'll see as we move through this section, this theory is not only a product of science but also of the times in which we live. And although science would like to consider itself removed from outside influences, it can't help but be affected by the people who work in the field.

Science as a methodology likes to see itself as a revealer of the true nature of the universe, as sort of a seer that can look beneath the veil of appearance. Yet science is practiced by scientists, human beings who bring with themselves a whole set of predispositions, values and beliefs. And as in any cross section of our society, some will be seriously invested in their positions and viewpoints, taking themselves rather seriously and purporting the “correctness” of their views. Of course, there are as many who don't take this stance and seek to move beyond any personal attachment to who they are and what they've discovered

One of the theories about the origin of the Universe is
"THE BIG BANG"

Once it was understood that the Universe had a beginning, scientists began to ask “ how did it come into existence, and what existed before it?”
Most scientists now believe that the answer to the first part of the question is that the Universe sprang into existence from a singularity -- a term physicists use to describe regions of space that defy the laws of physics. We know very little about singularities, but we believe that others probably exist in the cores of black holes.
The second part of the question, as to what existed before the Big Bang, has scientists baffled. By definition, nothing existed prior to the beginning, but that fact creates more questions than answers. For instance, if nothing existed prior to the Big Bang, what caused the singularity to be created in the first place?
Once the singularity was created (however it happened), it began to expand through a process called inflation. The Universe went from very small, very dense, and very hot to the cool expanse that we see today. This theory is now referred to as the Big Bang, a term first coined by Sir Fred Hoyle during a British Broadcasting Corporation (BBC) radio broadcast in 1950.
Interestingly, there really wasn’t any sort of explosion (or bang) as the name suggests, but rather the rapid expansion of space and time. It is like blowing up a balloon, as you blow air in, the exterior of the balloon expands outward