The profound question of why something exists rather than nothing lies at the core of both science and philosophy, prompting us to explore the origins of our existence.

Figure 1. Why the Big Bang Might Not Have Been the Start of Our Universe.

In evolutionary theory, we trace all life on Earth to a common ancestor known as the last universal common ancestor (LUCA). The search for LUCA fuels the quest to understand the origin of life. Our curiosity doesn’t stop there, though; it extends to the very origins of Earth and the Universe. Figure 1 shows Why the Big Bang Might Not Have Been the Start of Our Universe

Thus, our cosmic origin story begins with a fundamental question: What caused the expanding spacetime of the Universe to come into being?

The prevailing model of the expanding Universe, known as Big Bang Cosmology, was first coined by the English astronomer Fred Hoyle in a 1949 BBC Radio broadcast. This theory suggests that all matter in the Universe originated from a massive explosion at a specific moment in the distant past.

Einstein’s well-tested theory of general relativity supports the idea of an expanding Universe, portraying spacetime as a flexible medium that can bend, expand, and collapse. If we were to rewind the cosmic timeline, we would see the Universe contracting into an infinitely small point of infinite temperature, energy, and spacetime curvature—a state known as the Big Bang singularity [1].

Stephen Hawking and his colleagues dedicated much of their careers to understanding the enigmatic nature of this singularity. After all, if everything, including time itself, began at the Big Bang, how can we even discuss events before time existed?

Fortunately, cosmologists have ventured beyond the Big Bang singularity in search of alternative explanations that transcend the paradoxes of infinities and the origin of time [2].

One intriguing idea proposes that a cosmic era preceding the Big Bang led to a new paradigm of physics, effectively replacing the singularity.

Since Einstein’s theory adheres to classical physics, one potential escape route involves a quantum ‘bridge’ connecting an expanding Universe to one that collapses into a Big Bang—an event often referred to as the Big Bounce.

In a previous article, I discussed the concept of cosmic inflation—a period of rapid expansion with intriguing links to the cosmic microwave background and the origin of the Universe’s structure. However, mathematical theorems from Hawking and Roger Penrose demonstrate that inflation itself doesn’t escape the singularities inherent in the Big Bang [3].

In fact, inflation falls prey to its own Big Bang singularity!

One idea that fascinates me is cyclic inflation—a model that combines cosmic inflation with the concept of cyclic collapse and expansion, or bounces.

This captivating theory, proposed by Dr. Tirthabir Biswas and me, suggests that the Universe goes through infinite cycles of collapse and expansion.

After a critical cycle, once enough entropy has accumulated, the Universe undergoes a rapid acceleration of spacetime known as inflation. By incorporating cycles of bounces, cyclic inflation combines the benefits of inflation while offering a potential way out of the Big Bang singularity.

With cosmologists daring to look beyond the Big Bang, an exciting challenge lies ahead: identifying observational predictions that distinguish these competing models of the early Universe and its origins. These predictions could help determine which model most accurately describes the origins of our existence.

Personally, I’m intrigued by the observation that supermassive black holes appear to form earlier than our current cosmological model would predict. Perhaps a specific bouncing or cyclic model could elegantly explain this cosmic anomaly.

As we continue on this intellectual journey, the mysteries of our cosmic origins unfold, inviting deeper exploration into the complex tapestry of the Universe.

Reference:

1. https://www.sciencefocus.com/news/big-bang-not-beginning
2. https://www.quora.com/Was-the-Big-Bang-the-beginning-of-our-universe-or-was-it-the-end-of-the-previous-one
3. https://astronomy.stackexchange.com/questions/55667/was-the-big-bang-an-event-within-a-preexisting-universe-or-did-it-mark-the-begi

Cite this article:

Priyadharshini S(2024), Why the Big Bang May Not Have Marked the Beginning of Our Universe,AnaTechmaz, pp. 143