WE & UNIVERSE

 

Super Old

The universe is hella old. It's about 13.8 billion years old, give or take a few hundred million years.

That's a lot of time for stuff to happen, right? But how did it all start?

There's this theory called cosmic inflation that says that the universe expanded faster than the speed of light for a fraction of a second, right after the big bang.

That's when all the matter and energy in the universe came into being.

After the big bang, the universe was super hot and dense, like a giant soup of particles and light.

In the first few minutes, some of the particles smashed together and formed the first elements: hydrogen, helium, and traces of lithium and beryllium.

These are the building blocks of everything we see today. But it took a while for them to cool down and form atoms.

Until then, the universe was like a foggy mess that light couldn't get through.

About 380,000 years after the big bang, the universe had cooled enough that atoms could form.

Things get interesting now.

The fog cleared and light could travel freely for the first time. This light is still around today, and we can see it as the cosmic microwave background.

It's like a snapshot of the baby universe . It also shows us how uneven the universe was back then. Some parts were denser than others, and these density differences eventually grew into galaxies and stars.

How big is the universe now?

Well, that's a tricky question. We can only see as far as light has traveled since the big bang.

That's called the observable universe, and it's about 93 billion light-years across.

But that doesn't mean that's the whole thing.

The universe could be much bigger than that, maybe even infinite. We just don't know for sure.

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So, let's say we stick to what we can see. How many stars and planets are there in the observable universe?

There are about 100 billion galaxies in the observable universe, and each galaxy has about 100 billion stars on average. That means there are about 10 sextillion stars in total.

That's a 1 followed by 22 zeros.

And that's not even counting planets. There could be trillions of planets in the observable universe, maybe even more.

Drake equation

It's a formula that takes into account various factors, like how many stars have planets, how many planets are habitable, how many planets have life, how many planets have intelligent life, and so on.

The problem is, we don't know most of these factors for sure. We only have guesses based on our own experience and observations.

We haven't found any conclusive evidence of life beyond Earth so far, but we haven't looked everywhere either.

• Maybe one day we will find out for sure if we are alone or not.
• Maybe we will make contact with another civilization out there.
• Maybe they will be friendly and share their knowledge with us. Or maybe they will be hostile and try to destroy us. Or maybe they will ignore us completely. Who knows?