From Nothing to Everything: The Origin of the Universe

By: Tanisha Grover

Our existence and what we call reality remains to be the largest mystery. What sparked the universe? How did it come into existence? How did it evolve into such a vast expanse? No one knows.

The Birth of the Universe & The Big Bang Theory

Humans are unable to comprehend the massive size and continuous growth of the universe. However, it didn't always start this large. The universe essentially birthed from nothing. Absolutely nothing. Zero. The Big Bang theory states the universe began about 13.8 billion years ago from a singularity—an infinitely dense point. Take a pen and make a small dot on a piece of paper. At one point, the universe was trillions of times smaller than your dot. This explosive event marks the beginning of both space and time as we understand them. The dot was infinitesimally small and incredibly hot (over 100 billion degrees) - more than anything to have ever existed. After the Big Bang, the universe began to cool which allowed for the formation of matter through subatomic particles and atoms.

As space expanded, it had to cool down. This allowed protons and neutrons to combine and form the first atomic nuclei in a process known as nucleosynthesis. The universe was finally cool enough to form neutral atoms after 380,000 years. This then allowed light to travel through the universe, resulting in what is observed as Cosmic Microwave Background Radiation (CMB). The CMB is the oldest light scientists could find which is the faint heat left over from the Big Bang.

The Creation of Galaxies

After the Big Bang, gravity formed stars and galaxies by pulling celestial objects and particles together. Einstein states that gravity is due to a massive object bending the fabric of space and time. About a billion years later, the first galaxies popped up. The galaxies had their own components to create everything inside. For example, when massive stars exploded at the end of their lives, they scattered new elements across space. This recycling allowed new stars and planets to form.

In our Milky Way, there are over 100 billion stars, many created from these eruptive events. The ongoing interactions between stars and gas keep new stars forming, making the universe a lively and changing place. Everything we see today comes from this cosmic cycle.

The Role of Dark Energy

Dark energy is responsible for the accelerating expansion of the cosmos. It is yet another unknown. This mysterious force accounts for about 68% of the entire universe. (Dark matter fills the other 27% and matter is less than 5% of the universe.) Simply, dark energy is anti-gravity. It is creating, forcing, and accelerating the universe's constant growth. The universe's expansion rate is 73 km/s per megaparsec. Despite the similar sounding names, dark energy is different from dark matter which is an unseen mass that helps hold galaxies together (while dark energy opposes gravity and pushes galaxies apart).

Numerous theories seek to explain dark energy's nature. One prominent idea suggests it relates to the cosmological constant proposed by Albert Einstein in his theories regarding general relativity. Alternatively, it might be connected to concepts from quantum mechanics and the very nature of spacetime. The fate of our universe depends on dark energy.

The Future of the Universe

Everything must eventually come to an end. The universe has experienced several distinct phases since its inception, and with dark energy's presence, questions arise about its future. One potential outcome is the "Big Freeze," where the universe continues to expand forever, resulting in a gradual cooling of stars until they no longer form.

Another possibility is known as the "Big Rip," where the universe's expansion accelerates so rapidly that it tears apart galaxies, stars, and even atoms.

Conversely, the "Big Crunch" predicts that gravitational forces could eventually overpower dark energy, collapsing the universe back into a singularity. However, current evidence leans toward the idea that such a reversal is unlikely.

No one knows for sure. We will likely never find out, but the quest for understanding continues to inspire our exploration of the cosmos.