The Big Bang

After a hiatus of weeks and weeks, the space junkie is back. Is he back with a bang? You bet. In this edition of Journey to Outer Space we shall discuss the reason why we're here, the reason
you're holding this copy of The Funday Times in your hands and reading this very
column… It is the reason why everything came into existence and we all came into being. It is one of the most discussed topics in astronomy… It is…

The Big Bang.

Let's go back in time, to a period of about 13 and a half billion years ago. A time when there was no Earth, there was no solar system and there were no stars. There was, quite simply, nothing. What is 'nothing' in the first place? Does it mean the lack of things that can be seen, touched or felt? Does it mean emptiness?

We shall go with that for now: emptiness. Between 13.3 to 13.9 billion years ago, there was no universe, at least not the way we see it now… There was nothing (which begs the question, isn't 'nothing' also
something?)

Unfortunately, though, it's not as simple as that. There WAS something there that triggered the Big Bang.
But before we go there, let's talk about something that is taking place right now, as we speak.
The universe is expanding, and it's expanding fast. Galaxies and clusters of galaxies are drifting apart from each other at an accelerated rate, which means that the gap between them keeps
widening, everyday.

If this is true then, quite clearly, the expansion today is greater than what it was yesterday. And so,
obviously, a few billion years ago, the galaxies were much closer together than they are today. With that in mind, if you keep going back in time, you will reach a point when all the galaxies and everything else were so close together that it was all condensed into one single point.

That was roughly 13.7 billion years ago. Everything was together in the same place. And it was a very, very hot place. See, as the universe expands, it becomes cooler.

Therefore, when everything was much closer together, things were obviously a lot hotter. So much hotter, in fact, that it makes our sun look no more threatening than an everyday matchstick.

So, what exactly happened?

It was the biggest fireworks display in the history of time… probably. Why probably? Because we just don't know what happened before that, or what was there before that, if there was anything at all.
No cosmologist (a scientist who studies the origin of the universe) is in complete agreement about the very early stages of the Big Bang. The generally accepted hypothesis, or theory, is that the fledgling universe was filled with a high energy density, huge temperatures and pressures, and was
expanding and cooling at a very rapid rate. Less than a second later (and by less, I mean a 1 followed by
36 zeros after 0.0), what is known as 'cosmic inflation' took place in which the universe grew
exponentially. (Think of it as a staircase or a mountain that grows steadily steeper).

Then the inflation stopped. Temperatures were unbelievably high and things were moving fast – really fast. All of this happened in less than a second. Just a few minutes into the expansion, protons and neutrons (sub-atomic particles) combined to form helium nuclei. Most protons remained uncombined to form hydrogen. (Hydrogen and helium are among the most common elements in the universe – our sun too is composed of these two lighter than air gases).

Any guesses as to what the temperature must have been like at this point?

A whopping 1 billion degrees Celsius! Good luck going anywhere near THAT. The universe then began to gradually cool down and a little less than 400,000 years later electrons and nuclei combined into atoms, most of which were hydrogen.

Over a period of millions of years, the denser regions of the newly formed universe began to attract each other and other nearby matter gravitationally, and thus gave rise to gas clouds, stars and later galaxies. That is how the universe we see around us today came into being. (This, of course, being a highly simplified account).

But not everyone agrees that this is how it all began. Some say that time itself began with the Big Bang. Some say time was always there, and the Big Bang was NOT the starting point and /or there was a universe before it ever happened. Maybe that universe was vastly different to our own. Maybe it looked exactly the same. We may never know.

If the Big Bang theory is correct, what's in store for the universe in the future? Will it continue to expand forever? Or will the size and expansion reach their limit and the universe suddenly begin to collapse, going back to a hot, dense state (this scenario is known as the Big Crunch). Or will all matter, including stars, galaxies, planets and atoms be torn apart in what is predicted to be the Big Rip?
We shall find out, next time.

Till then, happy star gazing!