Generally, when most of us study Space-time the most common question that arises in our minds is that what is the origin of this miraculous happening, and how did the whole universe come to be in its present complex form?
Well, today we are going to look at some of the most satisfying answers about all of this fictional stuff.
“Before the great inception the heavens and the earth were joined together as one unit”, basically there was no time or space; in their absence, there was void or chaos. Today most of the theories constructed by human brains have postulated a state of formlessness before the existence of the universe.
The Big Bang Theory is the leading explanation of how the universe began. Briefly, it states that the cosmos we know today is the result of the inflation of an infinitely dense singularity. This was the “Big bang” that happened 13.8 billion years ago.
Now that space and time were made after the “Big Bang” and science does not know that what could be before the big bang. Various theories are explaining to us about the singularity or infinitely dense black hole that expanded after the Big Bang with infinitely large speed, so let’s drive through some of the events following the big bang.
After the big bang following happenings made possible the life, we know today.
Idea Of Inflation
Theory of Inflation — to be short — states that after the big bang, “Universe” or to say space-time expanded faster than the speed of light. During this period, the universe doubled in size at least 90 times, going from subatomic-sized to golf-ball-sized almost instantaneously. After this, the rate of expansion decreased down.
Following this enormous expansion, some parts of the universe grew denser (fraction 1/100000) than others and dense places grew larger, and the universe started to cool down. As the universe cooled down the energy turned into a matter which in turn assembled into denser parts. All of this happened due to the existence of physical laws because now the whole scenario is going towards the formation of the very first galaxy.
“Matter bends space and time”. Yes, we all know that Newton didn’t believe that objects in space can affect it but Einstein did. Einstein says that space-time has geometry, has its own life, has dynamics; these dynamics are what we call gravity. To explain Einstein’s General Theory of Relativity — that he published 10 years after his Special Theory which explains the link between space and time — I will give an example: “If you move up the hill and then down the hill, the shape of the surface of the earth determines how you travel across the earth in the same way the geometry of the space-time determines how light and matter travels through it.” This is the wrapping of space-time and this wrapping produces the force we know as Gravity.
Birth of our Planet
This means that gravity and geometry of space-time tell matter how to move in orbits and how to clump together to form various structures. This happened because of different densities of matter in space-time. Denser regions had more density and greater gravity thus, attracting more and more matter and becoming denser and denser and denser, and this resulted in the formation of the first star, then a bundle of stars, then the first galaxy, and then this unimaginably large cosmos.
Our Earth, along with the other planets, is believed to come into existence as a solidified cloud some 4.5 billion years ago.
Sir James Jeans writes in “The Dying Sun”, “We believe, however, that some two thousand million years ago this rare event took place, and that another star wandering blindly through space, happened to come near the sun. Just as the sun and the moon raise tides on the earth, so this second star must have raised tides on the surface of the sun, an immense tidal wave must have traveled over the surface of the sun, at last forming a mountain so high that we could hardly imagine it. As the star came nearer and nearer the wave rose higher and higher, and when the star began to move away, its tidal pull had become so powerful that this mountain was torn into pieces and threw off small parts of itself into space. These small pieces have been going around the sun ever since, they are the planets, great and small, of which our earth is one.”
The origin of life on earth is another matter but the origin of our planet is explained by the above-mentioned incidents.
Distortion of Time
As far as time is concerned, we know that it is “Space-Time”, so when matter influences space-time it not only distorts the space but also affects the flow of time (this does not change the way we perceive time but the rate at which the time flows). Greater is the gravity; for instance, near a black hole; slower is the rate of flow of time. To be reasonable this means the way we perceive the time depends on our frame of reference and it can flow slower or faster if we move to another frame.
Black Holes warped the space-time large enough that the ultimate sci-fi fantasy became reality. We can understand after this that light can also bend its way (gravitational lensing) if it moves close to very dense objects like say a cluster of galaxies of very dense black holes and this turns to a conclusion that even the stars we see in the sky are a sight of past because light takes many light years to reach our eyes.
After the Inflation, during the first 7 billion years, the rate of expansion of the universe was slower but something crazy happened; now it is expanding faster and faster, it is as if the gravity had become the opposite; instead of attracting the galaxies it was pushing them apart.
Is it the gravity, losing its power? Or there is another mysterious ingredient in our universe? Yes, there is, the Dark Energy.
It is just a hypothetical form of energy (like dark matter) and has never been directly observed but makes 70% of our universe. We don’t know that what it exactly is but it is pouring down energy into the universe causing it to expand. Dark energy behaves mysteriously, ordinary matter is attractive but dark energy is repulsive, ordinary matter feels the gravity and comes together but this stuff doesn’t.
Due to this reason universe is expanding at a much faster rate, it’s becoming lonelier and lonelier, galaxies are going far apart, everything is becoming darker and darker and colder and colder.
Eventually, the universe may… may rip or freeze and that would be the endgame of the universe.
But does the big bang actually happen?
The Quantum Space-Time
According to quantum mechanics, nothing can be infinitely small and infinitely dense; that is what the big bang says about the beginning of the universe, then if the singularity does not exist how does the universe come into existence?
The theory Quantum Space-Time works with both general relativity and quantum mechanics.
According to this theory, the universe was not formed by the bang of a singularity but was formed by remnants (the left part when most of the greater part has been used) of another dying universe.
It is possible that before the big bang there was a universe, a space-time but rather than expanding it was contracting. Perhaps the universes don’t end in rips or freezes due to expansion but they collapse, an ancient universe expands but begins to collapse under its own gravity crunching space-time into a spec but instead of forming a singularity space-time once again explodes.
So, is there any absolute beginning? to be fair, no but it could be one of the firm theories postulated by human minds. Being humans, we cannot know the hidden truths about our universe but we should be inspired by seeing that the capacity of our human brain was able conclude this much about the complexity of space-time.
To end the talk, I would say that we still know very little about the absolute truths of our mystical universe but we should try out best to unlock the full potential of our minds to get past the boundaries of the covered beauty of space-time.