The beginning of everything, the big bang. They claimed here that the universe was suddenly born and is not infinite. Up until the middle of the 20th century most scientists thought of the universe as infinite and ageless.  Until Einstein’s theory of relativity gave us a better understanding of gravity and Edward Hubble discovered that the galaxies are moving apart from another in a way that fits previous predictions.

In 1964 by accident cosmic ground radiation was discovered in relic of the early universe which together with other observational evidence, made the big bang the accepted theory in science. Since then, improved technology like the Hubble Telescope has given us a pretty good picture of the big bang and the structure of the cosmos.

Recent observations even seem to suggest that the expansion of the universe is accelerating, but how can this big bang work?  How can something come from nothing?  Let’s explore what we know.

We can ignore the beginning part for now but first of all the big bang was not an explosion. It was all space stretching everywhere all at once. The universe started very, very small and quickly expanded to the size of a football. The universe didn’t expand into anything, space was just expanding into itself. The universe cannot expand into anything because the universe has no borders. There is by definition, no outside the universe. The universe is all there is.

In this hot, dense environment energy manifested itself in particles that existed only for the tiniest glimpses of time. From a glance, quarks were created which destroyed one another perhaps after giving off more gluons. These found other short lived quarks to interact with forming new quark pairs and gluons again. Matter and energy were not just theoretically equivalent, they were so hot they were practically the same stuff.

Somewhere around this time matter won over anti-matter. Today we’re left almost with all matter and maybe no anti-matter at all. Somehow one billion and one particles were formed for every one billion particulates of anti-matter.  Instead of one massive ultimate force in the universe, there were now several refined versions of it acting under different roles.

By now the universe has stretched to a billion kilometres in diameter which leads to a decrease in temperature. The cycle of quarks being born and converted back to energy suddenly stops. From now one we work with what we have. Quarks begin forming new particles, petrons like protons and neutrons. There are many, many combinations of quarks that can form all sort of petrons but only very few are reasonably stable for any length of time.

Please take a moment to appreciate that by now only one second has passed since the beginning of anything. The universe which has grown to 100 billion kilometres is now cold enough to allow most of the neutrons to decay into protons and form the first atom hydrogen. Imagine the universe at this point as an extremely hot soup, ten billion degrees Celsius filled with countless particles and energy.

Over the next few moments things cooled and settled down very fast.  Atoms formed out of hydrons and electrons making for a stable and electrically neutral environment. Some call this area the dark age because there were no stars, hydrogen gas didn’t allow visible light to move around.  But what’s the meaning of visible light anyway when there’s nothing alive yet that could have eyes.

When the hydrogen gas clumped together after millions of years, and gravity put it under great pressure stars and galaxies began to form. Their radiation dissolved the stable hydrogen gas into a plasma that still permeates the universe today and allows visible night to pass. Finally there was light.

Okay but what about the part we didn’t talk about? What happened right at the beginning?  This part can be defined as the big bang.  We don’t know at all what happened here, at this point our tools break down. Natural laws stop making sense, time itself becomes completely wobbly. To understand what happened here we need a theory that unifies Einstein’s relativity and quantum mechanics, something countless scientists are working on right now.

But this leaves us with lots of unanswered questions.  Were there universes before our own? Is this the first and only universe? What started the big bang or did it just occur naturally based on laws we don’t understand yet?  We don’t know and maybe we never will, but what we do know is that the universe as we know it started here and gave birth to particles, galaxies, stars, the earth and you.

Since we ourselves and made of dead stars we are not separate from the universe, we are part of it. you could even say that we are the universes’ way of experiencing itself. So let’s keep on experiencing it until there are no more questions to ask.

From Kurzgesagt