The Big Bang Theory: Revolutionizing Our Understanding of Existence
Throughout history, humans have gazed at the sky, contemplating the celestial lights, including the sun, the moon, and beyond. In those ancient moments, an insatiable curiosity ignited within them, urging them to seek answers about the origins of the cosmos. Over time, this burning curiosity has been passed down, compelling generations to develop theories in pursuit of one timeless question: Where did it all come from?
One of the most complete and widely accepted theories in this regard is the Big Bang Theory. The Big Bang is a scientific theory that proposes that the birth and development of the universe originated from a point in space-time called the singularity. Think of this in a way that all the matter and energy of the universe were trapped in an inconceivably small point of high density and high temperature (Williams & Today, n.d.). It is theorized to be a colossal release of energy that initiated the rapid expansion of the universe over 13.7 billion years that led to the creation of galaxies, stars, planetary systems and eventually humankind. What happened that led to the sudden expansion? This question continues to puzzle cosmologists, as the answer remains unknown to this day (What Is the Big Bang Theory? n.d.).
In 1915, while developing his General Theory of Relativity, Albert Einstein faced a challenge. If gravity were to solely attract all objects, the universe would ultimately collapse under its overwhelming force. However, observations indicated that the universe was not collapsing. To address this issue, Einstein introduced a cosmological constant into his equations. This constant acted as a counterforce to gravity and proposed a static model of the universe. Little did Einstein know that an astronomer named Edwin Hubble would soon contradict his proposed static model of the universe. Working at Mount Wilson Observatory in California, Hubble made a noteworthy observation in the late 1920s. He noticed a peculiar phenomenon known as redshift, where light emitted by celestial bodies moved toward the red end of the spectrum, indicating that they were moving away from us (Vogel, 2021). Furthermore, Hubble discovered that the farther galaxies were from us, the faster they receded, providing compelling evidence for an expanding universe. These groundbreaking insights provided the earliest understanding of the origins of our universe and laid the foundation for the Big Bang Theory (Vogel, 2021).
In light of these developments, a priest named George Lemaitre explored the implications of the expanding universe. He proposed that if the universe is expanding, it must have originated from a single point in the past, where all matter and energy were concentrated (Georges Lemaitre, n.d.). Using the new quantum theory of matter, Lemaitre put forth the idea that the universe began as a single particle, referred to as the "primeval atom". This point eventually exploded, giving birth to space, time, and the ongoing expansion of the universe. This pivotal concept became the cornerstone of what we now recognize as Big Bang cosmology (Georges Lemaitre, n.d.).
“However, as the cosmos expanded, it cooled and became transparent. Light from that transition could now travel freely, and we see a lot of it today. This light is the cosmic microwave background (CMB), and it carries information about the very early universe. Astronomers use the patterns in CMB light to determine the total contents of the universe, understand the origins of galaxies, and look for signs of the very first moments after the Big Bang” (Cosmic Microwave Background | Center for Astrophysics, n.d.).
In the early universe, the absence of stable atoms rendered it opaque, preventing the transmission of light. For millions of years, as conditions cooled, stable atoms gradually formed through the combination of nuclei and electrons. This led to a significant emission of light. These radiations were now able to traverse the cosmos and cooled down as they traveled vast distances to the expansion of the universe (Cosmology, Theories, n.d.). During the 1960s at Princeton University, Professor Robert Dicke pursued theories related to the Big Bang and postulated that the remnants of the initial explosion would have undergone substantial cooling, manifesting as low-level radiations dispersed throughout the cosmos. In the meantime, Arno Penzias and Robert Wilson, two scientists at Bell Labs, embarked on a project to investigate radio waves in the universe. Penzias and Wilson's telescope detected an unexpected background "noise," akin to radio static, in the form of uniform microwave signals from all directions. Initially thought to be interference from their equipment, they investigated and ruled out various sources, including urban interference, galactic radiation, and even pigeons on the antenna. The persistent nature of the radiation led them to conclude that it was neither machine-related nor random noise. Puzzled by this unwanted noise, they met Robert Dicke to seek its theoretical explanation. When Dicke heard about Penzias and Wilson's noise, he immediately recognized its significance. (Brown, 2015) The noise they had stumbled upon was the Cosmic Microwave Background Radiation (CMBR), a remnant from the explosive birth of the universe. This collaboration between Penzias, Wilson, and Dicke led to a breakthrough of monumental proportions. Penzias and Wilson's accidental encounter with the CMBR not only earned them the Nobel Prize in Physics in 1978 but also solidified the significance of the CMBR as a milestone for the Big Bang Theory and forever transformed our understanding of the universe's origins. (A Science Odyssey: Penzias and Wilson Discover Cosmic Microwave Radiation, n.d.)
Credit: ESA and the Planck Collaboration
The CMB is a snapshot of the oldest light in our Universe, imprinted on the sky when the Universe was just 380 000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities.
The Big Bang theory, with its valuable insights into the origin and evolution of the universe, still confronts scholars and scientists with unresolved challenges and mysteries. The cause of the initial explosion, potentially originating from a singularity, remains an enigma. As physicist, Brian Greene aptly tweeted, Calling something a 'singularity' is a physicist's way of saying ‘we don't know what the heck we're talking about’(Twitter: @bgreene, 2021). Additionally, contrary to expectations, evidence suggests an accelerated expansion of space, attributed to the presence of dark energy (68% of the universe) and dark matter (27%), while ordinary matter comprises a mere 5% (Dark Energy, Dark Matter n.d.).Dark matter does not interact with light so we can neither see nor observe it directly (Hooper, 2020).
The long journey to this explanation has resulted from the collective effort of generations of scientific study. Previous generations were as clueless about the theories of the beginning as we are. While we have made impressive progress in comprehending the universe's history and origin, we are still profoundly puzzled, especially about its earliest moments. Scientific revolutions can fundamentally change our understanding of the universe, but it is difficult to predict when they will occur. The mysteries that cosmologists face today could be harbingers of a new scientific revolution, or they could be the last remaining pieces of a puzzle in our cosmic history.
Works Cited
A Science Odyssey: People and Discoveries: Penzias and Wilson discover cosmic microwave radiation. (n.d.). Retrieved May 31, 2023, from A Science Odyssey: People and Discoveries: Penzias and Wilson discover cosmic microwave radiation
Brown, L. (2015, November 19). Cosmic background: 51 years ago, an accidental discovery sparked a big bang in astrophysics. Discovery: Research at Princeton. Cosmic background: 51 years ago, an accidental discovery sparked a big bang in astrophysics
Cosmic Microwave Background | Center for Astrophysics. (n.d.). Retrieved May 31, 2023, from https://www.cfa.harvard.edu/research/topic/cosmic-microwave-background
Georges Lemaitre: Father of the Big Bang | AMNH. (n.d.). American Museum of Natural History. Retrieved May 30, 2023, from https://www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons-book/georges-lemaitre-big-bang
Hooper, D. (2020, May 14). Is the Big Bang in crisis? Astronomy Magazine. https://www.astronomy.com/science/is-the-big-bang-in-crisis/
Vogel, T. (2021, April 27). About—Story | Edwin Hubble [Text]. NASA. http://www.nasa.gov/content/about-story-edwin-hubble
What is the Big Bang Theory? (n.d.). Retrieved May 29, 2023, from https://phys.org/news/2015-12-big-theory.html
Williams, M., & Today, U. (n.d.). What is the Big Bang Theory? Retrieved May 29, 2023, from https://phys.org/news/2015-12-big-theory.html
