What happened before the Big Bang facts for kids

I am so excited that you asked this question! It is one of the most profound and mind-bending questions anyone can ask. When we look up at the stars, we are looking back in time, and your question takes us back to the very first second—and then tries to peek behind the curtain to see what was there before the show even started.

To answer this, we have to travel through the worlds of physics, mathematics, and even a bit of philosophy.

What was the Big Bang?

Artist's conception of gravity pulling mass away from a star and into a black hole

Before we look at what happened "before," we need to make sure we understand what the Big Bang actually was. Many people imagine a giant explosion, like a firework in the middle of a dark room. But that’s not quite right.

The Big Bang wasn't an explosion in space; it was the explosion of space itself. Imagine a tiny, microscopic balloon. Inside that balloon is everything: all the atoms that make up your body, all the water in the oceans, all the planets, and all the billions of galaxies. About 13.8 billion years ago, that "balloon" began to expand incredibly fast.

In the very beginning, the universe was a singularity. This is a mathematical term for a point that is infinitely small, infinitely dense, and infinitely hot. At this point, our current laws of physics—the rules that tell us how gravity works or how light moves—simply break down. They stop making sense. This is why looking "before" that moment is so difficult.

The "North Pole" Argument

Stephen Hawking holding a public lecture on 24 August 2015

One of the most famous scientists in history, Stephen Hawking, had a very specific answer to your question. He suggested that asking "What happened before the Big Bang?" is exactly like asking "What is north of the North Pole?"

Think about a globe of the Earth. If you start at the equator and walk north, you eventually reach the North Pole. Once you are standing exactly on that point, you can’t go any further north. Every direction you look is south. It’s not that there is a "wall" at the North Pole; it’s just that the very definition of "north" ends there.

Hawking argued that Time itself began at the Big Bang. If time is a dimension that started at that singularity, then there simply was no "yesterday" before the Big Bang. In this view, the universe didn't pop into an existing timeline; it created the timeline as it expanded. It’s a hard concept to wrap your head around because we are used to time flowing like a river, but in physics, time is a "fabric" that can be stretched or even started from zero.

The Big Bounce: A Never-Ending Cycle

An animation of the Big Bounce

Not every scientist agrees with Hawking. Some think that our Big Bang wasn't the beginning, but rather a transition. This idea is called Cyclic Cosmology, or more funnily, the Big Bounce.

Imagine a universe that behaves like a giant accordion or a bouncing rubber ball. In this theory, before our universe existed, there was another universe. That previous universe might have been expanding just like ours is now. However, eventually, gravity might have become so strong that it pulled everything back together.

Instead of expanding forever, that old universe began to shrink. This is called the Big Crunch. Everything—stars, black holes, and galaxies—got crushed back into a tiny point. But instead of staying crushed, it "bounced." The pressure became so intense that it triggered a new Big Bang.

If this theory is true, we are just one link in an infinite chain of universes. There could have been trillions of universes before ours, each with its own stars and maybe even its own people, all ending in a crunch and starting over in a bounce.

Eternal Inflation: The Multiverse Bubble Bath

Another mind-blowing theory is called Eternal Inflation. To understand this, imagine a giant, ever-growing ocean of "energy foam."

In this ocean, space is constantly expanding at a speed much faster than light. But every now and then, a small part of this foam "decays" or slows down. When it slows down, it forms a bubble. Inside that bubble, a Big Bang happens, and a universe is born.

In this model, our Big Bang was just the moment our specific bubble formed in the "Multiverse."

Before our Big Bang the cosmic foam was already there, expanding and churning. Outside our universe other bubbles are forming right now, creating other universes with different laws of physics. Some might have ten dimensions; some might not have gravity at all!

In this scenario, the "before" is a state of eternal expansion that has been going on forever and will never stop. We are just a tiny, quiet bubble in a very loud, busy multiverse.

Mirror Universes: The World of Anti-Matter

An idea of a twin universe, with the beginning of time in the middle.

Some physicists have proposed a very strange idea: what if the Big Bang created two universes at once?

Imagine the Big Bang as a mirror. On our side, time moves forward, and we are made of regular matter. But on the other side of the "mirror," a twin universe was created that moves backward in time and is made of anti-matter.

In this theory, the "before" isn't really "before"—it’s just the other side of the starting line. It’s like two runners starting at the same point but running in opposite directions. From our perspective, the other runner is going "backward," but from their perspective, we are the ones going backward! This would mean the universe is perfectly symmetrical.

Brane Theory: Clashing Dimensions

A simplified drawing of two "branes," which are like membranes in a higher dimension

An animation of the expected behavior of a Big Crunch

If you like science fiction, you’ll love String theory. String theory suggests that we don't live in a world with just three dimensions (up-down, left-right, forward-back). Instead, there might be 10 or 11 dimensions that we just can't see.

In a version of this called Brane Cosmology (short for "membrane"), our entire universe is like a flat sheet of paper floating in a higher-dimensional space called "the bulk."

Imagine two sheets of paper hanging near each other. Usually, they just float there. But if they happen to drift toward each other and collide—BAM! The energy from that collision is so massive that it creates a Big Bang on the surface of the sheets.

According to this idea, "before" the Big Bang, our "brane" was simply drifting through a higher-dimensional void, waiting to bump into another one. These collisions might happen over and over again every few trillion years.

Quantum Fluctuations: Something from Nothing

One of the weirdest rules of the universe comes from Quantum mechanics. It says that on a microscopic level, "nothing" is never actually empty. Even in a perfect vacuum, there is a tiny bit of energy that "jitters."

Scientists have observed that in empty space, pairs of tiny particles can pop into existence out of nowhere and then disappear a fraction of a second later. These are called quantum fluctuations.

Some physicists, like Lawrence Krauss, suggest that the entire Big Bang was just one giant quantum fluctuation. Imagine a flat, calm ocean. Suddenly, a single, massive wave leaps up for no reason other than the water was "jittering." Our universe might be that wave. In this case, "before" the Big Bang was a state of "Quantum Nothingness"—a sea of potential energy just waiting for a random spark to start a universe.

How Do We Find Out?

Two-dimensional representation of gravitational waves generated by two neutron stars orbiting each other.

Photograph shows the 60-inch cyclotron at the University of California Lawrence Radiation Laboratory, Berkeley, in August, 1939. The machine was the most powerful atom-smasher in the world at the time.

You might be wondering, "Kiddle, how can we possibly know any of this if it happened billions of years ago?"

We use three main tools:

• The CMB (Cosmic Microwave Background): This is the "afterglow" of the Big Bang. It’s a faint glow of light that fills the entire sky. By looking for tiny patterns or "bruises" in this light, scientists can look for clues of what happened in the first trillionth of a second.
• Gravitational Waves: These are ripples in the fabric of space itself, caused by massive events. Unlike light, gravitational waves can travel through almost anything. If we can detect "primordial" gravitational waves, we might be able to "hear" the Big Bang and see what triggered it.
• Particle Accelerators: Machines like the Large Hadron Collider in Switzerland smash atoms together to create temperatures and pressures similar to those just after the Big Bang. This helps us understand the "ingredients" of the early universe.

So, what happened before the Big Bang?

• Maybe nothing, because time hadn't started yet.
• Maybe a previous universe that collapsed and bounced.
• Maybe we are just a bubble in a giant multiverse.
• Maybe two dimensions collided like giant cymbals.

The truth is, we don't know for sure yet—and that is the most exciting part! Science is a work in progress. Right now, there are astronomers and physicists using giant telescopes and supercomputers to solve this exact puzzle. Maybe one day, you will be the one to find the missing piece of the puzzle and tell the world exactly how our journey began.