is our Universe.

And it's about to collide with another universe.

It might be fascinating to watch, but

we should probably be worried about

what's going to happen when they crash.

The only potential evidence

of a universal collision

that we've ever discovered

is in the form of a "cold spot" in our Universe.

In 2013, the European Space Agency's

Planck satellite confirmed that this area

is 1.8 billion light-years across,

it's much colder than the rest of space,

and it seems to be missing 10,000 galaxies.

At first, scientists were baffled by its existence,

but now some have theorized

that this spot might be a kind of scar or bruise

left from colliding with another universe.

But how can we know for sure?

And if this is the case, how long before it happens again?

Before we go any further, let me take a second

to address something that might have some of you scratching your heads.

Usually, when we refer to the universe,

we're talking about all space and time,

including planets, stars, galaxies,

and all other forms of matter and energy.

So if the universe basically means everything in existence,

then logically there can only be one of them, right?

Not necessarily.

Some scientists believe in the concept of the multiverse.

This theory states that our Universe wasn't the only one

that popped into existence during the Big Bang,

that there is an infinite number of other universes out there too,

and we just haven't found a way to see or measure them yet.

If this theory is right, then it's possible that all these other universes

could've grown at the same rate, at the same time, after the Big Bang.

If that's the case, then they might have banged into each other as they expanded.

And that brings us back to the cold spot.

The cold spot is a region of our Universe that's 0.00015 °C

colder than everywhere else.

That might not seem like a big deal, but

when the rest of the Universe's temperature is so consistent,

scientists have started to think it's something more than an anomaly.

They think that the cold spot might be a scar left over from a collision between universes,

and the crash might have moved a bit of energy out of that spot in our Universe,

causing the colder temperature.

But what would a collision of that magnitude look like?

Well, we can't say for sure, but there are some pretty cool ideas out there.

According to one physicist at the University of California,

if another universe came crashing into ours,

it would look like a giant mirror in the sky rushing towards us,

because its wall would reflect light.

If this other universe collided with our own,

we could inherit a whole new set of governing laws of physics.

Gravity could weaken or disappear,

resulting in a slew of planets escaping the gravity of their stars,

sending them flying off into space at ridiculous speeds.

Without gravity, stars would cease to exist, and we'd be left in perpetual darkness.

This would make life on Earth, and throughout most of the universe, nearly impossible.

With no shining stars, we'd lose any means of nourishment or breathable air,

as plants would no longer be capable of transforming

starlight into energy through photosynthesis.

But as bad as that all sounds, it's not something we have to worry about,

since the chances of our universe colliding with another one

are slim to none.

For one thing, we're not even sure that there are other universes out there to collide with.

And even if there are,

any collisions would've happened at that point when they were expanding,

380,000 years after the Big Bang,

which would mean there's little to no chance of it happening again.

If you're going to worry about colliding with anything,

maybe you should pick something a little more realistic,

like an asteroid.

But that's a story for another WHAT IF.