How Everything Began: A Journey Through Cosmic History

 How Everything Began: A Journey Through Cosmic History

This question is one of humanity's oldest inquiries. Various sources have attempted to answer it, from the myths and legends of different cultures to religions and their interpretations, and finally, science. Among these, science offers an irrefutable answer backed by evidence and mathematical laws. In this article, I will attempt to simplify these answers and explore how everything began.

1. The Big Bang

It is hard to find someone living today who hasn’t heard of the Big Bang Theory, the most scientifically supported explanation for the origin of the universe. The theory can be summarized as follows: everything in the universe was once concentrated in an infinitely small point, known as a singularity. This singularity contained all the energy and matter in existence. Suddenly, it exploded, began expanding at an incredible rate, and has continued to expand since then. From this event emerged everything we know.

2. Heinrich Wilhelm Olbers and the Eternal Universe

For centuries, different cultures had their interpretations of the universe’s origin. However, the concept of an eternal, infinite universe was widely accepted until the 17th century when Heinrich Wilhelm Olbers challenged this notion. He imagined an eternal universe with infinite stars. If this were true, the night sky should be perpetually illuminated by countless stars, regardless of distance. This paradox laid the groundwork for understanding that our universe has limits and is not eternal.

3. Edwin Hubble and the Expanding Universe

Following Olbers’ paradox, the problem of the universe’s expansion emerged. At this time, Einstein had already developed his groundbreaking Theory of Relativity but faced a challenge: why doesn’t the universe collapse under its own gravity? To resolve this, Einstein introduced a constant into his equations, which implied a force counteracting gravity to prevent collapse. While this idea was later dismissed, we now recognize this force as "dark energy."

Later, Alexander Friedmann and Georges Lemaître worked on Einstein’s equations and proposed the concept of an expanding universe. However, it wasn’t until Edwin Hubble observed the redshift of light from distant galaxies that the theory gained empirical support. Hubble’s observations showed that these galaxies were moving away from us at a consistent rate, indicating that it wasn’t just the galaxies moving but the universe itself expanding.

4. Cosmic Radiation and the Evidence of the Big Bang

In the 1960s, American scientists Arno Penzias and Robert Wilson stumbled upon a puzzling cosmic noise while working with a large telescope. After ruling out all possible sources of interference, they discovered that this noise was cosmic microwave background radiation (CMB), the remnant heat of the Big Bang.

Their discovery confirmed the earlier theoretical work of Ralph Alpher and Robert Herman, who had predicted that the universe was initially composed of 75% hydrogen and 25% helium. This composition resulted from nuclear fusion in the early universe when the temperature was millions of degrees Kelvin. Over time, as the universe expanded, the temperature dropped, halting the process of hydrogen-to-helium conversion.

5. The Hot Vacuum and the Formation of Atoms

By 1960, Robert Dicke and Jim Peebles predicted that if the early universe was as hot as theorized, its leftover heat should still exist, albeit at a much lower temperature of about 3 Kelvin. Their calculations eventually led to the understanding that the universe cooled down enough after 300,000 years to allow for the formation of neutral atoms, enabling light to travel freely. This event marked the "decoupling" of light from matter, leading to the universe becoming transparent.

6. Matter Formation and the Building Blocks of the Universe

In the first second after the Big Bang, the universe was incredibly hot and dense. Energy was rapidly converting into matter and antimatter. Quarks emerged, which combined to form protons and neutrons. Within three minutes, the universe had cooled enough for atomic nuclei to form. Over hundreds of thousands of years, these nuclei captured electrons to form the first neutral atoms: hydrogen and helium.

7. The Birth of Stars and Elements

The universe was not homogenous, with slight variations in density and gravity. These variations allowed regions of higher density to attract surrounding matter, forming the first stars. Within stars, nuclear fusion began, creating heavier elements like carbon, oxygen, and eventually iron.

Massive stars ended their lives in spectacular explosions known as supernovae, scattering heavier elements across space. These elements combined to form planets and other celestial bodies, eventually giving rise to galaxies, solar systems, and, ultimately, life as we know it.

This journey from the Big Bang to the formation of galaxies and elements underscores the incredible complexity and beauty of the universe. It also highlights the power of human curiosity and ingenuity in uncovering the secrets of existence.