The Big Bang: a reality or perception?

Edited by Eldrian Tho.

The Big Bang theory, first created by Georges Lemaître, is the most trusted and reputable theory that proves the formation and creation of the universe as we know it today. Ever since Georges Lemaître proposed the idea in 1931, physicists and astronomers have strived to confirm the validity of this statement, which led to multiple occasions where astronomers have questioned the theory and attempted to prove the rationality behind this theory. The most recent news that caused the spark of controversy regarding this topic was the rumour that the JWST disproved the Big Bang theory. “The James Webb Space Telescope has not disproved the Big Bang, despite an article about a pseudoscientific theory that went viral in August 2022, and which mischaracterized quotes from an astrophysicist to create a false narrative that the Big Bang didn't happen.”¹ The controversy sparked when the JWST revealed pictures of galaxies that would have formed within a 100 million years from the Big Bang after finding galaxies billions of light years old, which scientists believed was impossible because the dark age (period of time where no stars or galaxies formed) lasted about 1 billion years. However, this could have been caused due to inaccurate redshift, other forms of radiation or unknown forces that could have altered the form of light waves we received, or most probably that the universe is older than we think it is. Astronomers have only approximated the age of the universe to be 13.7 billion years, though the reality could be a much greater value. Presently, there are two major pieces of evidence that validate the Big Bang theory. Firstly, the constant expansion of the universe. During the 20th century, it was commonly theorised that the universe was static, and its total volume (as it is represented as a sphere) was finite and constant. However, in 1924, Edwin Hubble, regarded as one of the greatest astronomers of all time today, discovered that the recessional velocity of galaxies further from Earth had a much greater velocity as compared to those nearer than us. In simpler terms, this meant that galaxies further away were moving away from Earth at a significantly faster speed as a result of the universe expanding outwards (meaning that they would be even more distanced from us). You could also visualise it as “dots on a surface of an expanding balloon: it doesn’t matter what dot you choose, every other dot is moving away from it, and the dots farthest away are moving the fastest.” ² This would be happening as the balloon continues to inflate. But how did he discover this? A widely known phenomenon in astronomy is redshift, which played a big role in Hubble’s discovery of the expansion of the universe. Redshift is when we receive stretched out waves from a transmitter or object. The further away the object or transmitter, the more the waves we receive will be redshifted, as distance is directly proportional to time. As seen, redshift clearly proves the expansion of the universe because there would be nothing else to stretch the waves out if the universe remained static; we would receive the waves exactly as how they were initially emitted, no matter the distance.

Additionally, astronomers believe that a force is rapidly pushing the universe outward, causing galaxies to be torn apart and pushed away from each other. This hypothetical force is known as dark energy, which exerts “a negative, repulsive pressure, behaving like the opposite of gravity.”³ At this stage, dark energy remains as a thought-provoking, challenging and interesting problem for astronomers to tackle, which astronomers believe has been caused as a result of the Big Bang or type Ia supernovae. This type of supernova takes place when two white dwarfs (the core remnant of main mass sequence stars) in a binary system collide due to gravity and exceed a mass 1.4x greater than our sun.

Fig 1) A diagram showing the expansion of the universe, obtained from Expansion of the universe. (n.d.). Wikipedia. Retrieved January 31, 2023, from https://en.wikipedia.org/wiki/Expansion_of_the_universe

Fig 2) A diagram showing how redshifts and blueshifts (the opposite process) work, obtained from (2013, June 27). Have astronomers ever observed a violet shift like they have blue shifts and red shifts? Retrieved January 31, 2023, from https://www.wtamu.edu/~cbaird/sq/2013/06/27/have-astronomers-ever-observed-a-violet-shift-like-they-have-blue-shifts-and-red-shifts/

Secondly, cosmic microwave background radiation (CMB)⁴ is another key factor that led scientists to believing that the Big Bang is indeed true. Scientists believe that CMB is a remnant of the Big Bang, or a result of a shockwave from the Big Bang which caused this radiation. They have also proven that there is no other reason for why CMB would occur in our universe; even events as big as supernovas and intergalactic collisions would have nowhere near enough force to leave this enormous aftermath of radiation behind. Having said this, many of these theories rely on the fact that the universe’s shape is a sphere, which is an entirely new topic of discussion on its own. Some believe that the universe is in fact a sphere, but other contrasting theories include a flat universe, a 7 dimensional universe, a torus shaped universe, and even a cube / cuboid shaped universe. The search for the origin of the universe will always remain as one of the most engrossing and absorbing topic for cosmologists. All in all, it is widely agreed that the Big Bang happened, though perhaps not when we think it did; many misinterpret the term “bang” as an explosion, which is not necessarily what took place. Cosmologists are constantly searching for galaxies far away in order to trace light from astronomical bodies far away that have reached the Earth, to, eventually, conclude when our universe was born.

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References:

1. Cooper, K. (2022, September 7). The James Webb Space Telescope never disproved the Big Bang. Here's how that falsehood spread. Space.com. Retrieved December 18, 2022, from https://www.space.com/james-webb-space-telescope-science-denial

2. Evidence for the Big Bang. (n.d.). The University of Western Australia. Retrieved December 20, 2022, from https://www.uwa.edu.au/study/-/media/Faculties/Science/Docs/Evidence-for-the-Big-Bang.pdf

3. Dark Energy | COSMOS. (n.d.). Centre for Astrophysics and Supercomputing. Retrieved December 21, 2022, from https://astronomy.swin.edu.au/cosmos/d/Dark+Energy

4. ESA - Cosmic Microwave Background (CMB) radiation. (n.d.). European Space Agency. Retrieved December 21, 2022, from https://www.esa.int/Science_Exploration/Space_Science/Herschel/Cosmic_Microwave_Background_CMB_radiation