The scientists have discovered that the universe has originated from a single point at a finite time and infinite density. After the initial expansion, the temperature goes down enough to form subatomic particles and atoms. The phenomenon of expansion and formation of the universe is known as the Big Bang theory. The big bang theory started 13.7 billion years ago, and the universe has passed through many different epochs. Due to the extreme conditions and sudden change in temperature and density, the universe drastically changed during the first second rather than billions of years.
From the understanding of the big bang theory, the following events happened during the formation of the universe:
The epoch lasted from 0 to 10-43 seconds, and all the matters were compacted in a small ball. At this time, the universe was in the form of singularity. All the matters and fundamental forces are in the form of a compacted, tiny ball. During this epoch, the universe is in the region of 10-35 meters and has a temperature of 1032 degrees celsius.
Grand Unification Epoch
The age lasted from 10-43 to 10-36 seconds, and all the fundamental forces started to separate and remain unified. The earliest sub-particles and particles begin to form during the time.
It lasts from 10-36 to 10-32 seconds, and in the period, due to high temperature and pressure, all the matters experienced rapid expansion and cooling. The elementary particles that formed during the grand unification epoch have distributed thinly across the universe.
The period lasts from 10-32 to 10-12 seconds, and the universe supports the things that have mass. The strong nuclear forces separate from the other, and the particle interaction creates a large number of particles.
The era continues from 10-12 to 10-6 seconds, and quarks, electrons, and neutrons started to form in large numbers, and the four fundamental forces come to existence. The formation of electrons and neutrons results in the formation of matter.
During this time, the universe began to take its shape and grow even denser. The formation of astronomical structures takes place during the epoch. The matter had distributed in different structures, from stars to galaxies.