Much like everything else, our universe came into being 13.7 billion years ago. But what really happened that made our existence possible?
The universe as we know started out extremely small, a singularity) and expanded into the visible stretch of space of around 46 billion light years radially from the earth. But what happened in between the two? It took around three hundred thousand years
QUARK-LEPTON ERA( 10-32 s)
The temperature during that time were so hot that matter and particle, were practically the same, not just theoretically, as revealed later through the famous equation of relativity E =mc2 . For the first time, matter flickered into existence as tiny glimpses of sub-atomic particles known as gluons which are massless subatomic particles. From gluons, pairs of quarks were created which destroyed one another forming more gluons. On reacting further with short-lived quarks, new quark pairs and gluons were created completing the full circle. Matter and energy were literally interchangeable.
So how did matter, as we know came into existence? For reasons unknown, matter dominated over anti-matter, weighing down the formerly balanced scale on its side. Roughly, for every billion matter and anti-matter pairs, there were an extra matter particle that grew into larger numbers over time.This problem is known as the baryon asymmetry problem ,remains as one the “greatest mysteries of physics” till date.
NATURAL LAWS( 10-9 s)
Before the universe was created, there was a single kind of force that held everything together. During this phase, this was split into more refined versions of force each with its own laws broadly classified today as the gravitational forces, nuclear forces(strong and weak) and electromagnetic forces.
HADRON AND LEPTON ERA(10-6 s)
By this time, the quark-to-energy and energy-to-quark cycle stopped suddenly and the quarks started forming larger particles known as hadrons such as protons and neutrons. Various combinations of these quarks led to the formation of several kinds of hadrons.
THE NUCLEOSYNTHESIS ERA(1 sec)
After expanding sufficiently, the universe started cooling down and neutrons started decaying into proton allowing the formation of first hydrogen atom.
RADIATION ERA/OPAQUE ERA(200 sec)
This era marks the formation of first atoms as known today. Things cooled down rapidly creating suitable conditions for formation of electrically neutral atoms. The hydrogen gas didn’t allow visible light to move around. When hydrogen gas clumped together and gravity put it under pressure, stars and galaxies began to form. Their radiation dissolved hydrogen gas into a plasmic state allowing visible light to move around for the first time. The stable universe, as known today started existing roughly 300,000 years after the first Big Bang.
One interesting trend that can be observed if we progress through the mentioned eras are the fact that with time, things grew more complex and more fundamental particles rearranged into a variety of different things. Everything at one point of time were unified as a single entity. Matter and energy were literally the same thing, until they were separated into different entities.
Our understanding of space, time and consequentially the universe is limited, which several questions unanswered even till date.
But what were the nature of events that led to the occurrence of Big Bang? Perhaps there are forces at play beyond the grand scheme of things, we call our universe. Maybe the universe has a boundary after all(not necessarily in the literal sense of the word), but can’t simply be comprehended by our brains limited by perception through the five senses it was designed for.