The term universe is derived from the latin word ‘Universum’, which was used by the Roman statesman Cicero.
As we know that we usually used to refer to these small things which exist within the universe – the solar system, the milky way, and all known galaxies. Nowadays, the technology is so ahead that everyone can know about the origin of the all known matter, the law of physics and large scale structure of the universe in the big bang theory only. But, the fact is at one point in time, very few are familiar with this fact that universe was also a star.
It all started at a single point in space and suddenly at an instant everything just expanded from a single point of location forming energy, matters, atoms even the stars and galaxies also that we see today. we can say like that, It is a vast bubble of space and time expanding in volume.
This happens at a very high temperature where the universe also seems to be very unstable and takes time to cool down, meanwhile, during this process all subatomic particles and atoms are forming. Giant clouds of these elements later coalesced through the gravity to form stars and galaxies. Now while forming the galaxies and stars, within the observable universe, matter is disturbed in a highly structured fashion. It is because of galaxies which consist of planets, nebulas, and stars. After that also it was left with a lot of space in the large area.
The things are all similar in the larger scale, where the galaxies are separated by the volume of space with the gas and dust filled. In terms of shape, the scientists had found three possibilities because the universe is of four dimensions of space or time. These shapes could be positively-curved, negatively-curved, and flat.
A positively-curved universe sphere that would resemble in four-dimensional sphere that would be finite in space, A negatively-curved universe could be like four-dimensional saddle, and it would be not having ant boundaries in space or time. In the third scenario, A flat universe- in which a critical amount of energy would exist and its expansion would only half after an infinite amount of time. Hence, this began 13.8 billion years ago, and that’s why this is to be considered as the age of the universe.