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- [Narrator] The universe is everything.
to the very existence of\nspace, time, and life.
The origin of the universe\nis the origin of everything.
plus creation myths from around the world
have tried to explain\nits mysterious genesis.
However, the most widely\naccepted explanation
The Big Bang theory states\nthat the universe began
as a hot and infinitely dense point.
Only a few millimeters\nwide, it was similar
this tiny singularity violently exploded.
And it is from this explosion, this bang
that all matter, energy,\nspace, and time were created.
What happened next were two major stages
Called the radiation and matter eras
that helped shape the universe.
named for the dominance of radiation
This era is made of\nsmaller stages call epochs
that occurred within the universe's
first tens of thousands of years.
The earliest is the Planck epoch.
No matter existed in the\nuniverse at this time
to the four forces of\nnature, the superforce.
At the end of this stage, however
a key event occurred in which gravity
split away from the superforce.
Next came the grand unification epoch
named for the three remaining\nunified forces of nature.
This epoch ended when one of those forces
called strong, or strong\nnuclear, broke away.
Then the inflationary epoch began
during which the universe\nrapidly expanded.
Almost instantly it grew\nfrom the size of an atom
The universe at this time was piping hot
and it churned with electrons,\nquarks, and other particles.
Then came the electroweak epoch
when the last two forces,\nelectromagnetic and weak
During the next stage, the quark epoch
all of the universe's\ningredients were present
however, the universe was\nstill too hot and dense
for subatomic particles to form.
Then, in the hadron epoch, the\nuniverse cooled down enough
for quarks to bind together\nand form protons and neutrons.
In the lepton and nuclear epics
the radiation era's last two stages
the protons and neutrons\nunderwent a significant change.
And in doing so, they created the first
chemical element in the universe, helium.
The universe's new\nability to form elements
Much as the name suggests,\nthe matter era's defined
by the presence and predominance
It features three epochs\nthat span billions of years.
The vast majority of the\nuniverse's life span
In this stage, the universe's temperature
cooled down enough for electrons
to attach to nuclei for the first time.
Called recombination,\nthis process helped create
the universe's second element, hydrogen.
This hydrogen, along with helium atoms
dotted the universe with atomic clouds.
Within the clouds, small pockets of gas
may have had enough gravity\nto cause atoms to collect.
These clusters of atoms, formed\nduring the galactic epoch
became the seedlings of galaxies.
Nestled inside those\ngalaxies, stars began to form.
And in doing so, they queued the latest
and current stage of the\nuniverse's development
The formation of stars then caused
and helped shape the\nuniverse as we know it.
Heat within the stars\ncaused the conversion
of helium and hydrogen into almost all
the remaining elements in the universe.
In turn, those elements\nbecame the building blocks
This ecosystem of\neverything was only possible
because of the many stages in\nthe universe's development.
While countless questions\nabout the origins
of our universe remain,\nit's only a matter of time
for some long-sought answers to emerge.