Big Bang Theory UPSC - Overview & Origin for Geography UPSC Notes!

Big Bang Theory UPSC is about the origin of the Universe. It suggests that about 1370 crore (13.7 billion) years ago, all matter and energy in the universe was concentrated in an area that is smaller than an atom. At this instant, matter, energy, space, and time were not existent.

Big Bang Theory UPSC is one of the most important topics for the UPSC IAS exam. It covers a significant part of the Geography subject in the General Studies Paper-1 syllabus. In this article, we shall study the overview, understanding, misconceptions, and proofs of the Big Bang Theory. 

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An Overview of our Universe

The universe is a large region of space that houses everything that has ever existed. All the galaxies, stars, and planets are in the cosmos. The precise size of the universe is still unknown. According to scientists, the universe is still growing. The contemporary explanation for how the earth came to be is the big bang theory.

The Big Bang theory explains the early evolution of the Universe. In accordance with this theory, the Universe began in a very small, very hot, and very dense state. It has since grown, gotten less dense, and gotten cooler. The Big Bang is astronomers’ best theory for how matter, space, and time were formed 13.7 billion years ago.

Apart from Big Bang Theory, there were 2 more theories of the universe to explain the origin and evolution of the universe; the Steady-State Theory and Pulsating Theory.

What is Big Bang Theory?

According to the Big Bang theory, the universe’s present and past matter both originated at the same time. At this point, all matter had been gathered into a singularity, which was a tiny small ball with infinite density and extreme heat. The cosmos as we know it began when the Singularity suddenly started to grow.

While there are other contemporary explanations for how the universe formed, such as the Oscillating Universe Theory or the Steady State Theory, the Big Bang theory is the most well-liked and accepted. The model accounts for the expansion of the Universe as well as a wide variety of other events, in addition to explaining the genesis of all known matter, the laws of physics, and the large-scale structure of the Universe.

Big Bang Theory: Claims and Postulates

According to the Big Bang theory, the universe was once so hot that protons, neutrons, and electrons were present everywhere. The Big Bang theory goes on to claim that as the universe expanded, temperature and density decreased.

• Darwin Theory: In another interesting sense, the expansion of the universe is similar to Darwinian evolution: while most scientists believe they comprehend it, there is disagreement on its true significance.
  • A century and a half after the publication of On the Origin of Species, biologists continue to argue the methods and consequences of Darwinism, while a large portion of the general public continues to be ignorant of pre-Darwinian concepts. Similar to how the expansion of the cosmos is still poorly understood even 75 years after its initial discovery.

Also, study Earth – Origin & Evolution NCERT Notes For UPSC with this link!

Efforts to study Big Bang

There were many efforts to study the Big Bang Theory. Some of the important ones are listed below.

Cosmic Background Explorer (COBE)

• NASA launched COBE, the first mission in order to study cosmic background radiation, which captures “baby images” of the universe just 400,000 years after it was created.
• The goal of COBE was to measure the diffuse radiation with an accuracy of 1 micrometer to 1 cm throughout the entire celestial sphere.
• The electromagnetic radiation from the Big Bang is still present in the cosmos today. These tiny temperature changes are related to slight density variations in the early cosmos, which are portrayed in the image below as various colours of blue and purple.
• The structures that make up the cosmos today, such as galaxy clusters and large, empty spaces, are thought to have developed as a result of these fluctuations.

Image Credit: NASA

Wilkinson Microwave Anisotropy Probe (WMAP)

• The Wilkinson Microwave Anisotropy Probe (WMAP), which was launched in 2001, was the second mission to investigate cosmic background radiation.
• WMAP examined the whole sky, measuring temperature variations of the microwave radiation that is almost uniformly dispersed throughout the Universe, with significantly better resolution than COBE.

Planck

In 2009, the European Space Agency and NASA jointly launched the third mission, code-named Planck. The microwave background radiation maps being produced by Planck are the most precise ones ever. It measures the variations in the CMB’s temperature with an accuracy limited only by fundamental astrophysical restrictions owing to detectors sensitive to temperature variations of a few millionths of a degree and mapping of the entire sky over 9 wavelength bands.

Also, study in detail about the Universe and Solar System with this link!

Proofs of the Big Bang

Let’s discuss the two major scientific discoveries that provide evidence of the big bang theory

Hubble’s Discovery (1920)

• Relationship between the distance of a galaxy from Earth and its speed. Hubble plotted these objects’ speeds against their distance from Earth using spectroscopic red-shift data to determine their velocities. He found that the rate of separation between celestial objects is related to their separation.
• In other words, objects are traveling away from us more quickly the further they are from Earth. Hubble’s law came to be known as a result.
• Hubble’s discovery of the connection was eventually utilised to demonstrate the expansion of the universe.
• Hubble also understood that the far-off objects he had been studying were located outside the Milky Way. This was the first time that people realised there were buildings outside of the Milky Way.
• The Big Bang theory was first proposed by Georges Lemaître first in 1927 and was further supported by Hubble’s discovery. It was a significant development for astronomy.

The Discovery in the 1960s of Cosmic Microwave Background Radiation

• The Big Bang theory states that the universe was hot and dense at its beginning.
• It cooled as it increased. For instance, just a refrigerator works on the same idea, expanding a liquid into a gas to cool the inside.
• The theoretical temperature of the universe as it exists today was calculated by cosmologists, who then started looking for proof of it.
• Arno Penzias and Robert Wilson eventually made the unintentional discovery of it in 1964 while investigating how radio signals could be reflected off circling satellites using an antenna they had constructed.
• They initially believed it to be radio interference from the nearby city of New York, but they eventually realised it was radiation coming from outside the Milky Way.

Misconceptions of Big Bang Theory

The Big Bang Theory is subject to a number of misconceptions. It is totally misleading to say that the big bang was “little.” Space itself might be endless as a whole. An infinite space can be reduced by any amount and remain infinite. The quantitative depiction of expansion gives rise to yet another set of misconceptions.

American astronomer Edwin Hubble identified a peculiar pattern in 1929: the recession velocity of a galaxy away from us (v) is precisely proportional to its distance from us (d), or v = Hd. This pattern describes the pace at which the distance between galaxies increases. The Hubble constant, or proportionality constant, H, measures how quickly space is expanding around all observers in the cosmos, not just humanity. There are also misconceptions that Hubble’s law is not applicable to all galaxies.

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