When we look around at the universe we live in, we’re really seeing its state after
some 13.7 billion years.
Thanks to scientific advances, we’ve been able to trace time all the way backwards to
the event that started our universe in the first place.
So, what did the universe look like in its earliest moments?
This is Unveiled and today we’re answering the extraordinary question; What did the First
20 Minutes of the Universe Look Like?
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Scientists have a good idea of what happened in the first seconds and minutes of the universe.
What came before that, however, is more complicated.
For example, was there even time before the big bang?
It might sound like a strange question, but many scientists think that the answer is no.
That’s because if we reverse back time to the big bang, we encounter an area of spacetime
that’s infinitely dense - a singularity.
Unfortunately, in a singularity, space and time break down, according to our best theories.
Stephen Hawking likened the question of time before the Big Bang to asking someone in the
North Pole which way north is; the question just loses meaning.
Some scientists disagree, however, and say that there was cosmic inflation before even
the Big Bang, with quantum physics taking over at such a small scale.
Regardless, there’s no definitive answer for now.
But we CAN see back close to the moments AFTER the Big Bang.
When we’re dealing with the universe's beginning, our normal standards for time are too long.
A lot happened within a very short amount of time, and scientific theories cover even
one trillionth of a trillionth of a trillionth of a second after the Big Bang.
The study of this early period is known as Quantum Cosmology.
Before the universe expanded too much, the four primary forces of the universe - gravity,
the strong and weak nuclear force, and electromagnetism - were united as one cosmic force.
In the earliest moments, matter was also inseparable from energy.
Inflation started rapidly, however, with the universe doubling in size many times within
a tiny fraction of the first second.
Fast forward by another tiny fraction of a second.
Matter and energy decouple in a process called baryogenesis.
Key to the creation of matter are photons.
When photons collide they can form subatomic particles and antiparticles in a process called
Pair Production.
But the laws of nature are formatted in such a way that slightly more particles than antiparticles
are created, so the universe now has matter.
At about .0001 seconds after the Big Bang, the temperature of the universe has dropped
enough to stop pair production.
The fundamental forces also separated early in the formation of the universe, in a process
called spontaneous symmetry breaking - and this has caused problems for scientists trying
to understand it ever since.
We have yet to create an equation or theory that’s able to unify these forces.
Gravity in particular poses special problems.
One second after the Big Bang, neutrinos decouple from other forms of matter, and form something
called the cosmic neutrino background.
If primordial black holes exist, which we aren’t sure about, then they form now too.
Electrons don’t stop being produced until 4 seconds after the big bang, when the temperature
drops low enough - to about 6 billion degrees Kelvin.
So about 4 seconds into the universe we have photons, neutrons, electrons, and protons;
there are a lot more photons than anything else, though.
Despite this, the universe is too dense to allow light, so everything is dark.
Two minutes into the birth of the universe, things start to get interesting.
The temperature drops below 1.2 billion kelvin and Deuterium nucleus, or “heavy hydrogen,”
is able to form.
Fusion forms more complex nuclei in a process called Nucleosynthesis.
Only nuclei are formed, however, because it’s still too hot for electrons to be attracted
and form atoms.
After three minutes, the temperature drops yet again to below 1 billion kelvin due to
constant expansion, and it’s now cool enough to allow helium nuclei to form.
This happens when two deuterium nuclei are fused together, with excess energy being released
in the form of photons.
Now the universe is finally able to start building different forms of matter, though
it’s still 75% hydrogen and 24% helium.
During this productive period, other nuclei are able to form as well.
Helium, lithium, and beryllium nuclei are produced.
Nothing heavier is able to fuse, however.
That’s because there are no stable nuclei containing five protons and neutrons, and
trying to add a proton to helium generally results in it being spit back out.
So the universe comes to a standstill in terms of nuclei production.
And twenty minutes after the formation of the universe, nucleosynthesis comes to halt
altogether.
It’s still too hot to allow proper atoms to form or photons to travel too far, so the
universe exists in a kind of dark plasma state.
And at this point, the universe falls into a kind of equilibrium.
The temperature is still too hot to allow anything else meaningful to happen, and for
the most part, the next 2,500 years are fairly uneventful.
The universe is pretty nearly flat and is dominated by large amounts of radiation.
It takes some fast forwarding if we want to see what happens next.
The universe continues to expand and cool, but the temperature has to drop pretty drastically
for the next phase.
But after about 2,500 years, matter finally starts to dominate the universe.
The next interesting thing that happens takes another 322,000 years or so.
At this point, the temperature has dropped sufficiently, to about 3,000 kelvin.
Now protons and electrons are able to be attracted and form the actual atoms that we’re all
so familiar with.
This is called the epoch of recombination, and marks a major point in the universe’s
formation, because atoms are necessary to form everything else in the universe.
This is also when Cosmic Microwave Radiation formed, which researchers still use today
to peer into the universe’s past.
Yet the universe will remain dark until 380,000 years after its initial formation.
At that point light is finally able to shine.
That being said, it’s still really dark, and won’t start to become light until the
first stars begin to form.
But if you want to see star formation, that’s not until 100 million years after the Big
Bang.
A lot has happened to our universe, but a surprisingly great many things happened even
within its first minutes of existence.
It’s first twenty minutes were a pretty hectic time, but it was one that laid the
foundation of everything we see today.
And that’s what the first 20 minutes of the universe looked like.
What do you think?
Is there anything we missed?
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