How did the universe begin?

Simulation of the Big Bang using a controlled collision in the laboratory.

We are not sure how the universe began, as we are with many other things in astronomy.

But there are several theories and the Big Bang is the one with the largest number of followers among astronomers.

This is so thanks to the evidence we have and the observations that support that this theory is valid.

The Big Bang theory tells us that just under 14 billion years ago, the universe was something very, very different from what we know now.

It's hard to imagine, but we can make an effort.

It was a region of a miniscule size, much smaller the head of a pin.

And in that space there was a very high temperature and density.

In other words, it had very extreme conditions, nothing that we know of or that exists in our universe today is not even similar.

And then something happened that sparked the beginning of what later became our universe.

What happened is that for some reason that tiny, very hot and very dense region began to expand.

The way one can imagine this is as a deflated balloon with some dots painted on its surface.

When you start to inflate it, those points are moving away from each other.

Basically what caused that expansion is that the extreme conditions that existed in the beginning were softening, the temperature and the density were decreasing.

Several crucial stages occurred, but let's say that the conditions were given for protons and neutrons to appear first.

Protons are subatomic particles, that is, they are smaller than the atom, have a positive electric charge and are formed by the union of three elementary particles called quarks.

Neutrons are also subatomic particles, they have no electrical charge and are also made up of three quarks.

After the formation of protons and neutrons, three minutes after the Big Bang, the first nuclei appeared

After the formation of protons and neutrons, three minutes after the Big Bang, the first nuclei appeared.

A little later, electrons were able to associate with protons and neutrons and gave rise to neutral atoms.

This took a while, until the first atoms about 300,000 years passed.

And actually only hydrogen could be formed, almost all the hydrogen in the universe comes from the Big Bang, helium and a little lithium.

All the rest of the chemical elements come from a later stage, when the first stars and the first galaxies formed.

But that hydrogen and that helium were the raw material from which everything we know was generated.

There were dark stages from which we cannot receive any information.

And that is why we are not 100% sure that the Big Bang is the correct theory.

But in addition to those dark stages, there are others that did allow photons, the light that was produced at that time, to leave there and reach today.

And that light we can study today and it gives us information about what was happening at the time it was formed.

In fact there is something called the cosmic microwave background which is radiation that comes to us from those early stages of the universe.

With that information we can know that there were times when this universe allowed conditions to exist, for example, for galaxies to form.

As I explained to you, in the origin that first region was very uniform but when it began to expand, small differences began to occur between some regions and others, and these small differences made it easier for galaxies and stars to form later.

If everything had remained equally uniform, perhaps the conditions for galaxies and stars to form would not have occurred because, in the end, their formation comes from inhomogeneities in temperature or we could call them irregularities in the universe.

And that's the way our cosmos began.

The theory of multiple universes argues that the region from which everything began may not be the only one, that is, there could have been different similar regions that also began to expand and that each gave rise to a universe.

There are some theories that speculate with the idea that the region from which everything started might not be the only one, that is, there could have been different similar regions that also began to expand and that each one of them gave rise to A universe.

This is the multiple universe theory.

There are astronomers who have this hypothesis as a field of research.

But in reality, there is no evidence about this, as we do have, of the Big Bang theory as the beginning of our cosmos.

In astronomy, as in the rest of science, theory and observations must go hand in hand.

There are many things that make sense mathematically and this of the multiple universes can make mathematical and physical sense but until it is observed and we obtain a proof even if it is indirect, it cannot be affirmed.

But basically what this idea says is that if everything that I have explained to you before happened in our universe, what does it tell us that the same thing could not happen many times?

Gloria Delgado Inglada

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