How Did Everything Begin? – The Big Bang Theory
Hello everyone!
We’re starting a brand-new series: The Formation of the Universe Series. In this series, we’ll have your eyes fixed on the stars and your minds embarking on an intergalactic journey. If you’re ready, today we’re going back to the very beginning of everything in the universe: The Big Bang Theory. But we won’t just gloss over it with a simple “it exploded and that’s it.” What really happened? Why did it happen? How do we know? Together, we’ll explore all these questions.
The Moment Everything Began: What is the Big Bang?
The Big Bang is an event that occurred about 13.8 billion years ago, when the universe began expanding from a point of nearly zero volume but infinite density (which we call singularity). The word “bang” here is actually a bit misleading because it wasn’t like a bomb exploding in space. On the contrary, it was the expansion of space itself. From the moment it began expanding, time, space, matter, and energy came into existence. So, as you can see, the Big Bang wasn’t just an explosion—it was the birth of everything.
What Was There Before Time and Space?
Yes, perhaps one of the deepest questions that everyone wonders: “What was there before time?” While the philosophical and physical side is complicated, scientifically, we can say this: Before time, there was no “before.” Because time itself began with the Big Bang.
Thanks to Einstein’s theory of relativity, we know that time and space are interconnected (this is called spacetime). Therefore, time was born alongside space. In other words, before the Big Bang, there was no time, so the question “What was there before?” may be meaningless. Shocking, right?
How Did the Big Bang Happen?
The exact “how” of the Big Bang is still not known. However, we have some strong ideas and observations. In the early moments, the universe was extremely hot and dense. The energy was too dense to transform into matter. During the first 10⁻³⁵ seconds (yes, 34 zeros after the decimal point!), the universe expanded incredibly quickly in a process known as inflation. It was like a snowflake suddenly expanding to the size of the Solar System.
During this expansion, energy began to cool down. As it cooled, energy started transforming into particles—protons, neutrons, electrons. And then the atoms, stars, and galaxies we know began to form. Everything started to take shape slowly.
So How Do We Know This?
Okay, my friend, how do we know about something that happened 13.8 billion years ago? Great question! Here’s where scientific observations come into play:
The Expansion of the Universe (Redshift) In 1929, Edwin Hubble discovered that galaxies are moving away from us, and this can be measured by the redshift of their light. This shows that the universe is expanding and that it was smaller in the past. Although it caused a lot of debate back then, it’s now an accepted fact.
Cosmic Microwave Background Radiation (CMB) In 1964, Arno Penzias and Robert Wilson discovered a faint microwave signal coming from all directions in space. This was the “heat signature” left over from the Big Bang—the baby picture of the universe. Today, CMB is one of the greatest pieces of evidence we have about the early universe.
The Distribution of Light Elements In the first moments of the universe, only hydrogen, helium, and small amounts of lithium were formed. The ratios of these elements today surprisingly match the predictions made by the Big Bang theory.
Does the Big Bang Explain Everything?
No. While the Big Bang does an excellent job of explaining the origin and development of the universe, there are still some unanswered questions. For example: Why is the universe almost perfectly uniform? What is dark matter and dark energy? What happened in the early moments? (We can’t explain the physical events during the tiny time known as Planck Time.) But the beauty of this is: There’s still so much to discover.
Conclusion: The Big Bang—A Story of Beginnings
The Big Bang doesn’t just tell us how the universe began. It also opens the door to big questions about ourselves: Who are we? Where are we in the universe? Are we alone? Does the universe have a purpose? The answers to these questions may come through science, philosophy, or perhaps from a place we never expected. But one thing is certain: Everything began at one point. And that beginning has sparked in us an endless curiosity.
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How do we know that this was the actual beginning of the universe?
We know that space is expanding faster than light can travel. How do we know that the Universe isn’t trillions of years old, but we just can’t ever see it because it’s beyond the distance that the faintest detectable light can travel?
How do we know that this was the actual beginning of the universe?
We don’t. It is “the beginning” in that it is the farthest back the laws of physics can be “rewound” before they break down (in the sense that once you rewind the clock back far enough, there’s enough matter and energy in a small enough space that the interactions between quantum mechanics and gravity become increasingly relevant, and we just don’t know how those play together; see Quantum gravity)
We know that space is expanding faster than light can travel. How do we know that the Universe isn’t trillions of years old, but we just can’t ever see it because it’s beyond the distance that the faintest detectable light can travel?
We don’t. But there’s no evidence to suggest that the universe outside of what we can see might be different from the parts we do see. We can’t really speak much about what’s outside of our light cone (what we can see). All we can say is that the parts we do see all looks basically the same (homogeneous, astronomically speaking).
near-zero volume and infinite density – what was outside this? are there other “spaces” elsewhere?
and will we ever return to this singular state?
and will we ever return to this singular state?
This is the “big crunch” question, and I think the current theory is that no, there’s enough energy, and space is curved in such a way that it won’t crunch back down. At least not all at once? We do have black holes that are sort of similar in that they pack so much stuff into small spaces that the current laws of physics are unable to completely describe them.
