13.8 billion years ago,
the entire Universe emerged
from one single point in space.
This theory is known as the Big Bang,
and it's the most widely accepted story
of the creation of our Universe.
Scientists came up with this universal origin story
when they observed that every single galaxy in space
is moving away from us,
even today.
That means that at one point in time,
everything could have been condensed
into an infinitely dense spot,
known as a singularity.
This singularity was really hot too.
Other evidence of the Big Bang
is something known as Cosmic Microwave Background.
It's radioactive remnants from the early days of our Universe.
Remnants that you can only see with the help of a telescope.
But what if we have this all wrong?
What if the Universe didn't start like this?
What else were we wrong about?
I'm sure you're not looking forward
to the end of the Universe.
But glancing at its future demise
could flip your understanding of the Universe
and its origins.
Before we unravel the mysteries of the Universe,
let's talk about something serious.
March is Mental Health Awareness Month,
and it's time to fight the old stigma
that you have to struggle in silence.
Especially when 40% of American adults
report living with symptoms of anxiety and depression.
You know, on average,
it takes about 11 years for someone
to seek treatment after symptoms occur,
mostly because people can’t afford help.
Now, while these numbers are scary,
it does mean one thing.
You’re not alone.
Right now, this administration is working
to make mental healthcare more accessible,
like through schools, expanding telehealth support
and providing more funding for CDC programs.
Let’s break the silence, and if you’re in need,
check out the resources available to you in your area.
The Universe is a lot better with you in it.
OK, so you know that our Universe is continually expanding outward.
So you might assume
that it would likely continue expanding forever.
Well, this could be true.
And this is why the most widely accepted theory
involves the Universe doing just that.
It's called the Big Freeze.
And what's really cool about this is a mysterious
and invisible force that makes the Universe expand.
It's called dark energy,
and it makes up 69% of the Universe's mass.
Another 26% of it is made of dark matter.
And only 5% of the Universe
is plain, old ordinary matter.
If all this material originated
from one point and just kept expanding,
eventually, all this heat and energy
would be very, very spread out.
At a certain point,
everything would be so far away from each other
that the entire Universe
would reach a ridiculously frigid temperature.
Absolute zero.
Absolute zero is the lowest temperature possible.
It translates into zero Kelvin,
or if you prefer a more familiar temperature scale,
-273 °C (-460 °F).
By the time the Universe reaches
this super low temperature,
you wouldn't be able to see any distant galaxies
from your vantage point in the Milky Way.
Don't worry, though,
that would be at least a couple of trillion years from now.
Now, that's just one theory.
It's also possible that the death of the Universe
will be the exact opposite of this.
Instead of expanding forever,
the Universe could shrink back together.
Time for the Big Crunch.
All of the matter in the Universe, taken as a whole,
has an unimaginable amount of gravity.
It might be enough gravitational force
to battle the mysterious dark energy.
And win!
If this big crunch were to happen,
the Universe would start to contract in on itself.
Galaxy clusters far away would merge.
Eventually, stars and planets in our own galactic neighborhood
would clump together too.
And this increasing density
would heat up the whole Universe.
All that Cosmic Microwave Background radiation
from the Big Bang
would get so heated that it would be hotter than stars.
We're talking 5,000 °C (9,000 °F) hot.
The Universe would become a scorching, chaotic mess.
As temperatures continued to rise
and more mass got crushed into a teeny-tiny region,
atoms would start to break apart.
The Universe would be turning into the densest
black hole possible.
While that would certainly be the end of the Universe
as we know it,
it might just be the beginning of a new one.
And that would be proof that our Universe
is much, much older than we thought.
The Universe may have formed itself
over and over again.
In this violent cycle of contraction and expansion.
You wouldn't have the slightest chance
of surviving to witness
this epic event first-hand.
No one would.
So for now,
all of this is just an end-of-times theory.
And it has a big name.
The Big Bounce.
It suggests that the Universe expands
and contracts all the time.
Just like a lung that breathes in and out,
only in slow motion.
And not just once or twice.
According to this theory,
there may have been billions,
trillions, or even an infinite number of Universes,
both before and after hours.
Each time the Universe reforms,
it could create completely different laws of physics.
This would create all kinds of strange possibilities.
There could be universes with no life,
no stars, and not even an atom in sight.
Now, this is all pretty wild.
And it gets wilder from here.
Some scientists debate that everything we know
about our Universe is wrong.
What we know about the cosmos is based on
what we can see and study
in our galactic neighborhood.
Then we assume that
it works like that everywhere else in the Universe.
The idea is old, and it's called the cosmological principle.
But we may have been wrong all along.
It could be that the way our Milky Way
galaxy moves through the Universe
is distorting our data.
I mean, we've never had any hard evidence
to confirm our theories,
so there's no way of seeing the bigger picture
from where we stand.
This is where you could be starting to doubt
whether any of this is real to begin with.
Surely our Universe, the one we can see,
must exist, right?
Well, not so fast.
You have quantum mechanics to thank for
what I'm going to tell you next.
Scientists who study quantum mechanics
theorize about the nature of the Universe
on an atomic level.
And according to some scholars in this field,
the Universe must be one of two things.
Real or local.
Bear with me here.
I know this can be mind-numbing.
If the Universe is real,
that would mean that it has specific properties
like color and mass that exist
even when you're not looking at them.
For example, take a red ball.
If it's real, the ball is red
even when there's no one around to look at it.
On the other hand,
the Universe could be local.
This means that the Universe can only exist because
we are there to observe it through our telescopes.
So if you think about the red ball again,
without anyone around to observe it,
it could have any color
or no color at all.
Only when you look at it and see that it's red,
does it actually become red.
That's quantum physics 101.
But there's a catch.
The Universe could be either real or local.
It can't be both.
And remember that the Universe is ridiculously big.
It could be infinite.
Our telescopes just aren't powerful enough
to observe all of it.
So that means we can't know for sure
if the Universe is even real.
You didn't see that coming,
did you?
Well, that should be enough of a head scratcher
to keep you pondering
about how everything really came to be,
where it all could eventually go
and what's the meaning of it all, anyway.
But hey, why stop there?
Wouldn't it be cool if the Universe
were actually like a giant brain?
Well, that's a story
for another WHAT IF.