- [Narrator] In this world on the day
this video launches,
it's November 6th,
the same day Will Byers goes missing
in the first episode,
and Eleven opens a portal to the Upside Down,
a parallel dimension
filled with unbelievable horrors.
But what I still find kind of unbelieveable
is that there's some real science
to this notion of parallel worlds.
- Once you open up that curiosity door,
anything is possible.
- [Narrator] But don't worry about them
being too much like the upside down,
because we'll probably never be able to
interact with them.
Hmm, probably.
Here's how multiverse theory allows
for mind-blowing cosmic weirdness,
(suspenseful instrumental music)
and maybe even the parallel-dimensions
of "Stranger Things."
(upbeat instrumental music)
(suspenseful instrumental music)
(pages turning)
- The Vale of Shadows
is a dimension that is a dark reflection
or echo of our world.
- [Narrator] That's the Dungeons and Dragons
version of the multiverse.
And depending on which theory you use,
it's honestly not that far off from the science.
The theory of the multiverse
is that our universe doesn't exist alone,
but is part of an ocean
of unimaginably large expanses,
which may have different physical rules
from one another.
And through the years,
different scientists have proposed
at least four theories of how we could be
one of many universes,
some of which get us closer
to the Upside Down than others.
And while you'll need
a really good science teacher
to understand the details,
the basics you can get,
like why even start thinking about this?
It's partly because scientists,
including the likes of Stephen Hawking
were troubled by how suspiciously perfect
the conditions for life are in our universe.
Everywhere you look,
universal constants defy predictions
to fall within ranges that allow life,
like how--and I could have found 15 examples
of this--specific quirks of carbon,
allow it to be abundant in our universe.
The very building blocks of life.
For some the multiverse is a potential solution
to this and other problems.
- So basically there are parallel universes.
- [Narrator] Think of clothes in a store.
It might not make sense to have a bright yellow
universe all alone,
but what if it were with an entire
multi-colored rack,
it starts to fit in more, right?
That doesn't mean the theories aren't weird,
even the simplest version
of the multiverse is weird.
See models predict that our universe is infinite.
I know it's crazy,
but matter can only arrange itself
in so many ways.
Imagine a deck of cards,
any given card order may seem unique,
but given enough shuffles,
it will appear again.
So our universe, too,
could repeat itself somewhere out in infinity,
beyond the limits of what we can now see.
And that has strange implications
because not only will there be an exact copy
of our Dustin in another universe's version
of "Stranger Things."
There will be billions of mirror Dustins.
- Mental.
- Just like our world,
but just infinite variations of it.
- [Narrator] Some will be small variations,
maybe a different outfit in a scene.
And sometimes they'll become demodog breeders
or start dating Nancy after their dance.
Fan-fiction becomes real people.
It stands to reason that
in this infinite chowder,
pictured charmingly here in "Cosmos,"
there could be a real world,
which just happens to be exactly like
the fictional Upside Down.
(ominous instrumental music)
(alien chitter)
Even in our universe within the universe,
scientists have proposed that radioactive planets
would be capable
of sustaining very hardy lifeforms.
(gunshots)
Of course your nearest identical twin
would be 10 to the 10,
to the 118 meters away--unimaginably far.
So even if this theory is true,
the chances that they're going
to bust through your wall are nil.
(soft instrumental music)
A different kind of multiverse
is predicted by the theory of cosmic inflation,
which isn't a fringe theory by the way.
At the beginning of everything,
the universe expanded far faster
than the speed of light.
It was an explosion of space, not in space,
but that explosion wasn't uniform.
Fluctuations meant that some parts
stopped inflating early creating bubble universes
like our own while other parts kept going.
Scientists like to use
Swiss cheese for this,
but this is a "Stranger Things" video
so we're gonna use Dig Dug.
These pockets patrolled by Pookas,
and Fygars are universes.
The soil is the space between universes,
which is rapidly inflating.
Once bubbles form,
they get pushed farther apart
at faster than light speed.
So under this theory,
the Upside Down isn't likely
to come knocking either.
The really weird part though,
is that the bubble universes
can have different laws of physics.
So maybe transmuting hive-mind life forms
are more likely there... possibly.
Which leads us to the most controversial
of all multiverses,
but also maybe the most alluring.
- You guys have been thinking
about Hugh Everett's,
"Many Worlds Interpretation"
haven't you?
- [Narrator] Yes!
So far we've started from the big end
of the scale,
but the "Many Worlds Interpretation"
gets to the multiverse through
the smallest parts of existence.
The big problem is that the physics
of small stuff, quantum mechanics is kooky,
even physicists say
they don't really understand it.
One conundrum is how really small objects
like photons behave in experiments.
They appear to act as waves,
multiple possible places at the same time
until we measure or observe them.
Then all their possibilities collapse
into a particle.
So the mere fact that we're looking
changes reality.
It causes an inanimate insensate beam of light
to make a choice.
(air explosion)
If you remember Schrodinger's cat,
(cat meowing)
that's what it's about.
But scientists don't like this
because it makes no sense.
I mean,
planets don't change because we look at them,
the physicist, Hugh Everett III
had a simple yet mind-boggling
way out of this awkwardness.
"The wave doesn't collapse."
He said.
We see one result here,
but in other universes that split off
from our own,
other Uses see the other outcomes.
An easier way to understand it
might be through the telepathic,
spin the bottle game
that Max and Eleven play in season three.
While the bottle is spinning,
there's a number of probable outcomes,
but we all see it collapse into one: Billy.
But according
to the "Many Worlds Interpretation,"
in another universe,
the bottle would tell other versions
of Eleven and Max to spy on Mr. Clarke
or Steve or whoever.
With universes branching off
at every quantum measurement
creating infinite YOUs,
it's suddenly crowded in here, right?
Plus they all occupy the same physical space
at the same time,
sort of like the Upside Down does.
But before you go taking an axe to your walls,
the universes are according to most,
completely sealed off from another
after the split.
(air swooshing)
And finally there's M-Theory.
The most mind-boggling of all.
Einstein spent the back half of his life
looking for a grand unifying theory of physics.
And some think they found it in M-Theory.
It says that everything from quarks on up
is composed of infinitely thin loops
vibrating at certain frequencies.
But one peculiarity is that M-Theory
requires seven more dimensions
to work, dimensions
which normal humans can't see,
a concept helpfully explained
by Mr. Clark in the show.
- Here's where things get really interesting.
The flea can also travel this way along
along the side of the rope.
He can even go underneath the rope.
- [Narrator] But M-Theory also envisioned
strings attaching to structures
called branes like membranes,
which we'll need special help demonstrating.
You can think of them as multi-dimensional
space waffles floating
in stacks of higher dimensional syrupy
space-time called the bulk.
Branes hold universes including ours.
And those other branes could actually
be traveling through hyperspace mere millimeters
from us theoretically,
they could interact with us.
It would account for mysteries
like the weakness of gravity for instance,
as foreign branes siphoned particles away
from our world.
If a neighboring brane brushed up against us,
it could even unleash something
like the big bang.
- Science is neat,
but I'm afraid it's not very forgiving.
- [Narrator] So maybe this is the theory
we've been searching for after all?
- But again.
- This is all-
- Theoretical.
- [Narrator] Look.
No one has successfully tested
any of these theories.
In fact,
some are criticized for being untestable,
and therefore unscientific.
So in the end multiverse theory
is partly a thought exercise
on the grand scale and strangeness of the cosmos.
But still,
if the Demogorgons do break through,
don't say we didn't warn you.
(upbeat instrumental music)
Okay.
I know I said that universes
in Hugh Everett's "Many Worlds Interpretation"
wouldn't interact with each other,
but some believe that quantum computers,
the beginnings of which we are already seeing
actually get their otherworldly speed
because their calculations are simultaneously
carried out in other universes.
We hope you know what you're doing scientists.
(upbeat instrumental music)
(alien roaring)