200 most important Astronomy topics - Sykalo Eugen 2023

The Big Bang Theory

What if everything—time, space, matter, your thoughts, this sentence—began with a silence so loud it tore itself apart?

I know. That sounds absurd. But that’s the paradox we find ourselves orbiting when we talk about the Big Bang. It wasn’t a bang, and it wasn’t big in the way we imagine explosions. No mushroom cloud. No boom in space. There wasn’t even space to begin with.

Instead, there was... nothing. And then suddenly, everything.

I remember the first time I saw the Cosmic Microwave Background—this faint, ghostly afterglow from 13.8 billion years ago, etched across the sky like a fossilized firework. I was staring at a map made by the Planck satellite, and it looked like static. Just blotchy heat. But it was cosmic static. The echo of the universe’s first breath. I felt dizzy. Like someone had pulled the floor out from beneath time.

Let’s walk into that dizziness together. Let’s follow the thread of spacetime all the way back to the beginning—not to understand everything (we’re still stumbling forward in the dark), but to marvel at the fact that we can understand anything at all.

The Day Time Began: What Was the Big Bang, Really?

Let’s start with the wrong idea: that the Big Bang was an explosion in space, like a cosmic grenade going off in some vast empty room. But here’s the twist: the Big Bang wasn’t an explosion in space—it was the explosion of space.

There was no “outside” to explode into. No emptiness waiting. The Big Bang was the birth of space and time themselves. It’s as if the Universe woke up inside its own dream and started expanding it from within.

We use the word singularity to describe the beginning. A point of infinite density, infinite temperature, and zero volume. But that’s just math-speak for “our physics breaks down here.” It’s a placeholder. A humble one.

What we do know is that at a moment we call t = 0, the observable universe was packed into something unimaginably tiny—smaller than a proton—and within a trillionth of a second, it began expanding at an exponential rate. This rapid inflation was not a fireball spreading out into space. It was space, stretching like dough as yeast activates.

According to NASA and ESA's joint analysis of WMAP and Planck data, this period of cosmic inflation happened roughly between 10−3610^{-36}10−36 and 10−3210^{-32}10−32 seconds after the Big Bang. That’s so fast and brief, it’s difficult to even simulate in a computer. Yet without it, the Universe wouldn’t be as smooth or structured as we observe today.

But why did it start? What “caused” the Big Bang?

We don’t know. Maybe we never will.

And yet... maybe we will.

A Universe That Remembers: Cosmic Clues in the Sky

The most astonishing thing about the Big Bang isn’t that it happened—but that we can still see it.

Imagine this: every time you tune an old TV to static, a tiny fraction of that white noise is leftover radiation from the early Universe. That’s the Cosmic Microwave Background (CMB), discovered accidentally in 1965 by Arno Penzias and Robert Wilson, who thought their radio antenna had pigeon droppings interfering with the signal. It didn’t. It was hearing the echo of creation.

The CMB is a nearly uniform glow in the microwave part of the spectrum, now cooled to just 2.7 Kelvin—colder than Pluto’s shadow. But in its faint irregularities lie the seeds of everything: stars, galaxies, you. Like fingerprints on a newborn’s face, they tell us how matter first clustered.

The Planck satellite gave us the most precise map of these variations. Cosmologists, like those at the Max Planck Institute and Caltech, have used them to calculate the age of the Universe (13.8 billion years), its geometry (flat, to within 0.4% error), and its composition: 5% normal matter, 27% dark matter, 68% dark energy.

Wait—what?

Yes. Most of what exists, we still don’t understand.

And yet, we can measure it. Isn't that... hauntingly beautiful?

Before the Beginning? Quantum Foam and the Problem of "Nothing"

Here’s a question that probably lives in your mind already:

What happened before the Big Bang?

Well. Let me be blunt. We don’t know.

But not for lack of trying.

Some theories suggest that the Big Bang wasn’t the beginning at all. That it was a bounce—a rebound from a previous collapsed universe. This idea, explored in models like Loop Quantum Cosmology, implies a cyclical cosmos: expansion, collapse, repeat. Others lean into the notion of a multiverse, where our universe is just one bubble in a frothy sea of inflating spacetime.

Quantum physics complicates things. At Planck scales, time and space lose meaning. They blur into what physicists call quantum foam—a jittery realm where particles pop in and out of existence like fireflies in fog.

Could our Universe have emerged from one of these fluctuations? Maybe. There’s even a hypothesis that says the total energy of the Universe is zero: matter balanced by gravity, like a cosmic checkbook. If that’s true, perhaps the Universe didn’t cost anything to create. Just a ripple in the nothing.

But then… what is “nothing”?

Try imagining absolute nothingness. Not blackness. Not silence. Not emptiness.

Just—not anything.

I can’t do it. Can you?

The Timeline of Everything: From Fireball to Flesh

After inflation settled, the Universe cooled enough for particles to stabilize. This period is known as recombination, around 380,000 years after the Big Bang, when electrons and protons combined to form hydrogen atoms. Light could finally travel freely—this is the moment the CMB was released.

Then came the Dark Ages, not in medieval terms, but literally: no stars, no galaxies, just hydrogen and helium atoms in a dark, silent cosmos.

But gravity was at work.

Over millions of years, tiny fluctuations in density caused clouds of gas to clump. The first stars ignited in what are poetically called stellar nurseries. These first lights—Population III stars—were giants, short-lived, and fierce. They forged heavier elements in their cores, exploded as supernovae, and seeded the cosmos with carbon, oxygen, iron.

You and I? We’re the children of these stars.

Carl Sagan wasn’t being metaphorical when he said, “We are made of star stuff.”

It’s literal. The calcium in your teeth, the iron in your blood, the gold in your ring—they all came from exploding stars. The Big Bang gave us hydrogen and helium. Everything else came later.

Does the Universe Have an Edge? And Will It Ever End?

Another question I hear a lot: Is the Universe infinite?

Current data suggest that the Universe is spatially flat and likely infinite in extent. But observable space—the part light has reached us from—is finite: about 93 billion light-years across. Beyond that? We don’t know. Maybe more of the same. Maybe not.

And then there’s the future.

Thanks to work from teams analyzing supernovae brightness—like the Nobel Prize-winning research from Perlmutter, Schmidt, and Riess—we know that the Universe’s expansion is accelerating. The force behind this acceleration is called dark energy, and it’s the dominant component of the cosmos.

What does this mean?

If dark energy keeps working as it does now, galaxies will drift farther and farther apart. Eventually, the night sky may go dark, save for the stars of our own galaxy. Then even stars will burn out. Black holes will evaporate. And the Universe may slide into heat death—a cold, dark eternity of low-energy particles.

Bleak? Maybe.

But also strangely poetic.

Because we are here now, briefly, in the only window when life can exist and ask questions.

Why It All Matters (Even If We Don’t Understand It Yet)

Look—I get it. The Big Bang is confusing. It bends the mind into shapes it doesn’t want to hold. There’s math, quantum weirdness, missing matter, contradictory theories.

But also—don’t you feel something deep in your ribs when you stare at the stars, knowing they’re messages from a past older than human memory? Don’t you wonder why this universe, of all possible ones, gave birth to eyes that could see it and minds that could contemplate it?

I don’t have the answers. Not all of them. Maybe not even most.

But I know this: the more we learn, the more wondrous and strange the Universe becomes.

We went looking for simplicity. We found elegance. And mystery.

A Question Rather Than an Answer

So maybe the Big Bang wasn’t the beginning of everything—but just the beginning of our understanding. Maybe it’s not a "bang" but a whisper from another realm. Maybe, someday, a new theory will emerge from a mind not yet born and rewrite the story entirely.

But until then, I find comfort in the uncertainty. In the dance between knowing and not knowing. In the silence between stars.

Because in that silence, you can hear something remarkable:

We are the Universe, finally able to ask where it came from.