Big Bang | Problem of Nothingness | 05th November 2022 | Virtual Wire
Today, the consensus among scientists, astronomers and cosmologists is that the Universe came into existence due to a massive explosion called the “ Big Bang”.
The theory was first proposed by George Lemaitre. He was a catholic priest and a Belgian cosmologist. According to the theory, around 13.8 billion years ago, there existed an infinitely dense and intensely heated ball containing all matter known as “the Big Bang singularity”. Suddenly, the singularity started expanding. The period from 0 to 10−43 seconds into the expansion was a phase in which the four fundamental forces (the electromagnetic force, the strong nuclear force, the weak nuclear force and the gravitational force) were unified as one.
Now, just think for a second, only 10^-32 seconds have passed and the universe has already expanded by a factor of 10^78 Let us proceed further. About 3 minutes after the Big Bang, the temperature was about 1 billion K and protons and neutrons combined to form deuterium (an isotope of hydrogen) and helium nuclei. Most protons remained uncombined as hydrogen nuclei After approximately 3,79,000 years, the electrons and nuclei combined into atoms (mostly hydrogen), which were able to emit radiation. These radiations are known as cosmic microwave backgrounds.
Over an enormous period of time, the slightly denser regions of the uniformly distributed matter attracted nearby matter gravitationally and thus grew even denser, forming gas clouds, stars, galaxies, and the other astronomical structures observable today. But wait a minute, did you ever think about how could the universe be ‘created’? Does it not violate the law of conservation of energy which states that matter can neither be created nor be destroyed? If there was nothing before the Big Bang then how did they appear? Is the law of conservation of energy wrong?
The answer is no, it is not wrong. The total sum of all energy in the universe is exactly zero. This is because all the positive energy in the form of matter is exactly equal to the negative energy in the form of gravitational force created by the mass of that matter.
So, their total sum is zero (just from where it began).
The Fate of the Universe
Just like the origin of the universe, the fate of the universe is also unknown. Many leading cosmologists have come up with several theories to determine the ultimate fate of the universe. Before observing dark energy, cosmologists had two possible scenarios for the future of the universe. If the mass density of the universe were greater than the critical density, then the universe would reach a maximum size and then begin to collapse. It would become denser and hotter again, ending in a state similar to it’s initial one. This would be known as a Big Crunch. Alternatively, if the density in the universe were equal to or below the critical density, the expansion would slow down but never stop.
Star formation would cease with the consumption of interstellar gas in each galaxy; stars would burn out, leaving white dwarfs, neutron stars, and black holes. Collisions between these would result in mass accumulating into larger and larger black holes. This would significantly affect the average temperature of the universe as well as it would then reach -273℃ or Absolute Zero, the temperature at which molecular motion ceases. This would be known as the Big Freeze. So, in conclusion, although people commonly say that the Big Bang is the origin of the universe, it actually describes the emergence of the present universe from an ultra-dense and high-temperature initial state. The Big Bang does not describe how space, time and energy were created. Let’s leave that for you to think about.