just like ours?

With an infinite number of Earths?

With uncountable versions of you?

What if we don't have to look too far

to find them?

Maybe a mirror version of our reality

Our Universe began

when a small, but very hot singularity

exploded in the Big Bang

13.7 billion years ago.

But maybe it wasn't the only one to be born then.

In physics, space and time

fuse into one four-dimensional continuum,

If this space-time is flat

and stretches far beyond the limits of our observation,

there is a possibility that it holds

uncountable disconnected universes.

But for all we know,

there are a limited number of ways

the particles in those other universes can be put together.

At some point the realities

will have to start repeating themselves.

That means, in theory,

our reality is only a small part of what's out there,

and someone just like you

might be living in a parallel universe

similar to our own.

And that universe may be as close

as a million trillion trillionth of a centimeter away.

Although the wall between the universes

might be incredibly small,

traveling between them won't be easy.

But it could be done.

All you'd need is an 85-megawatt nuclear reactor

capable of firing billions of neutrons on command.

That's how a team of physicists,

working in Tennessee's Oak Ridge Laboratory,

are trying to open the gates

of a mirror universe.

Of course, they have to find it first.

It all comes from a theory that says,

if you beam neutrons at a wall,

none should pass through.

If some do manage to make it to the other side,

it would mean that they've transformed

into mirror images of themselves

as they went through the wall between the two worlds.

There is one odd thing about neutrons.

In particle beams, on average,

they last for 14 minutes and 48 seconds

before they decay into protons.

But if you place neutrons in a lab bottle,

they'll break down 10 seconds faster.

It's not something we can explain with physics yet.

Neutrons are all the same,

and there shouldn't be any

10-second difference in their lifespan,

regardless of where they are stored.

Could it be possible

that the neutron experiments didn't go as expected

because physicists accidentally opened

a portal to a mirror world?

That would be the first evidence

that a mirror universe exists right next to our own.

A mirror world with mirror atoms,

maybe even a mirror Earth.

An entire mirror world

almost totally cut off from ours.

Could you meet another version of yourself

in that mirror world?

Now it gets a little complicated.

Even though particle configurations can repeat themselves,

the odds of finding a portal to a parallel universe

that's exactly the same as ours

are close to zero.

Think about it.

There are a novemvigintillion particles in the Universe.

That's the number 1 followed by 90 zeros.

Every single one of them

would need to have had the same interactions

for 13.7 billion years to create

an identical universe to what we have now.

The mirror universe would most likely have

its own mirror laws of physics.

But it's hard to know for sure,

because nobody's detected a single mirror particle yet.

Maybe, we shouldn't be searching for answers in a lab.

Perhaps we should be looking in space itself.

Our Universe is full of dark matter.

We can't observe it directly,

and we have no idea what it's made of

or how it works, but...

we know that dark matter is strong enough

to stop galaxies from flying apart.

Yet, we can't find it.

Perhaps the reason is that dark matter

is leaking from a mirror world into ours.

If we could detect that,

it would confirm that a mirror universe exists.

Because we know that there is five times more dark matter

than there is visible matter in the Universe,

you've gotta think that a mirror universe

is much more massive than the one we live in.

Even if we did manage to open up a gate into another world,

the portal would be incredibly small —

too small for you to see anything

without some very powerful lab equipment.

We'd still be dealing with neutrons and protons, remember?

You could only enter that realm

if you had the ability to shrink yourself

to the size of an atom.

But that's a story for another WHAT IF.