continued.......

 It was all space stretching everywhere all at once.

The universe started very, 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 gluons, pairs of 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,

it was so hot they were practically the same stuff.

Somewhere around this time, matter won over antimatter.

Today, we’re left with almost all matter and nearly no antimatter at all.

Somehow, one billion and one matter particles were formed

for every one billion particles of antimatter.

Instead of one massive ultimate force in the universe,

there were now several refined versions of it acting under different rules.

By now the universe has stretched to a billion kilometers in diameter,

which leads to a decrease in temperature.

The cycle of quarks being born and converted back to energy

suddenly stops.

Quarks begin forming new particles, hadrons, like protons and neutrons.

There are many, many combinations of quarks that can form all sorts of hadrons,

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 everything.

The universe, which has grown to one hundred billion kilometers,

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 minutes, things cooled and settled down very fast.

Atoms formed out of hadrons and electrons,

making for a stable and electrically neutral environment.

Some call this period the Dark Age, because there were no stars

and the 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 light to pass.

Finally, there was light!