Have you ever thought about how the universe had created? How did it become so vast and infinite? And how was it ages ago? These are some of the questions that confuse scientists and philosophers for a long time. The questions also result in some interesting theories. One such theory is the big bang theory. For a century, the theory has been widely accepted around the world. But why is the theory so popular, and what does it mean? How was the universe involved in such a massive explosion, and how can a theory explain this?
The primary conclusion of the big bang theory is simple. In short, the theory states that all of the past and current matters in the universe came into existence at the same time, i.e., 13.8 billion years ago. Earlier, all matters compacted in a tiny ball with infinite density and heat, known as Singularity. But suddenly, it started expanding and later formed the widely known universe. The fact is that the theory explains the origin of all known matters, laws of physics, and the high scale structure of the universe. It also accounts for a vast range of other phenomena and expansion of the universe.
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Timeline of the Big Bang Theory
Working from the current state of the universe, scientists have discovered that the universe must have originated at a single point of finite time and infinite density to expand. After the initial expansion, it states that the universe cooled enough to form subatomic particles and later atoms. Giant clouds of the elements later merge through gravity to form stars and galaxies.
The incidents roughly began 13.8 billion years ago, which is also the age of the universe. However, the earliest times of the universe lasted from approximately 10-43 to 10-11 seconds after the big bang. The following events take place in the timeline of big bang theory before the formation of the universe.
Singularity Epoch
Singularity Epoch, also known as Planck Epoch, was the earliest known period of the universe. In this era, all Matter had compacted in a single point of infinite density and extreme heat. During this time, the quantum effects of gravity dominated physical interactions. No other physical forces have equal strength to gravitation. The period extends to 0 to 10-43 seconds. The period got its name Planck Epoch because the duration can only be measured in Planck time.
Approximately, from 10-43 to 10-36 seconds, the universe starts to cross transition temperatures. It is the estimated time that the fundamental forces that govern the universe began to separate from each other.
From 10-36 to 10-32 seconds, the temperature of the universe was sufficiently low to separate electromagnetism and weak nuclear forces. The separation forms the two distinct effects.
Inflation Epoch
Inflation Epoch first began with the formation of fundamental forces. The period lasts for 10-32 seconds to an unknown point in Planck time. The cosmological models show that during the epoch, the universe filled with high-energy-density. The astounding high temperatures and pressure result in rapid expansion and cooling.
At 10-37 seconds, the phase transition that causes the separation of forces showed a period where the universe grows exponentially. The particle-antiparticle pairs of all kinds continuously being created and destroyed in collisions. The phenomena led to the predominance of particles over sub-particles in the present universe.
Cooling Epoch
In the cooling epoch, the universe continued to decrease in temperature and density. As a result, the energy of each particle began to decline, and phase transition continued until the particles changed into their present form. The particle values had dropped to the point where the particle physics experiments can estimate it.
Scientists believed that 10-11 seconds after the big bang, matters energy dropped significantly. About 10-6 seconds, quarks and gluons merged to form protons and neutrons. A phenomenon occurs in a few minutes in the expansion known as big bang nuclear-synthesis began. The temperature dropped to 1 billion kelvin, and energy densities declined about the equivalent of air, neutrons and protons started to combine. The combination formed the first atoms of deuterium and helium. However, most of the protons remained separated.
The electrons combined with hydrogen nuclei to form atoms after about 379,000 years. The radiation decoupled Matter from particles and continued expanding through space. The radiation is known as Cosmic Microwave Background, which is the oldest light in the universe.
Structure Epoch
It was during the time that the modern universe started to take shape. The universe began to grow even denser, form gas clouds, stars, galaxies, and other astronomical structures. The visible matter distributed in structures of different sizes, which range from stars and planets to galaxies, galaxy clusters, and superclusters.
The details of the process depend upon the amount and type of Matter in the universe. The widely known model for this epoch is the Lambda-Cold Dark Matter model, which shows
- Dark Matter—the dark matter particles move slowly compared to the speed of light
- Cold Dark Matter—it makes up about 23% of the universe’s energy
- Baryonic Matter—it makes up about 4.6% of the universe’s energy
The lambda here is the cosmological constant that shows the balance of mass-energy in the universe was static. The theory was initially proposed by Albert Einstein and considered to be the standard model of Big Bang cosmology.
Long-Term Predictions: Future of the Universe
A hypothesis states that the universe had a starting point that raises questions about the possible endpoint. The explanation gives rise to the following questions: If the universe began from a point and starting to expand, will it expand continuously? Or one day, all the expansive force comes to an end and starts to shrink into that small point again? These questions give rise to the two conclusions.
First, the Big Crunch scenario states that the universe will reach a maximum size and then begins to collapse on itself. The situation will only be possible if the mass density of the universe is higher than the critical density.
In the second case, if the density of the universe were equal to or below the critical mass, the expansion would slow down but never stop. The scenario is known as “Big Freeze.” The universe would continue until star formation with the consumption of all interstellar galaxies in each galaxy. Meantime, all the real stars would burn out and become white dwarfs, black holes, and neutron stars.
So, from here, the universe came into existence. Many incidents took place in the formation of the universe; that’s why the name of the theory is the big bang. We can understand how the universe comes to be. Scientists still research more accurate data for the big bang theory. There are still some things that are still unknown and need to be discovered in the big bang theory.
