Neutron stars are the densest things that are not black holes.

In their cores, we might find the most dangerous substance in existence:

In their cores, we might find the most dangerous substance in existence:

strange matter᠎.

A bizarre thing so extreme that it bends the rules of the universe

A bizarre thing so extreme that it bends the rules of the universe

strange matter᠎.

and could infect and destroy everything it comes into contact with.

and could infect and destroy everything it comes into contact with.

Or, it could teach us about how the universe began.

Or, it could teach us about how the universe began.

Maybe both.

Maybe both.

To understand how extreme strange matter really is,

To understand how extreme strange matter really is,

we first need to get a few basics.

we first need to get a few basics.

What is a neutron star, and how does strange matter break the rules of the universe?

What is a neutron star, and how does strange matter break the rules of the universe?

To get all of this into one video, we'll grossly oversimplify a few things

To get all of this into one video, we'll grossly oversimplify a few things

but we'll provide you with further reading, if you want more details.

but we'll provide you with further reading, if you want more details.

A neutron star is what remains after a very massive star explodes in a supernova.

A neutron star is what remains after a very massive star explodes in a supernova.

When this happens, the star's core collapses under its own gravity,

When this happens, the star's core collapses under its own gravity,

with such a strong inward force

with such a strong inward force

that it squeezes nuclei and particles together violently.

that it squeezes nuclei and particles together violently.

Electrons are pushed into protons, so they merge, and turn into neutrons.

Electrons are pushed into protons, so they merge, and turn into neutrons.

All the ᠎nothing inside of atoms᠎ ᠎is suddenly completely filled with particles

All the ᠎nothing inside of atoms᠎ ᠎is suddenly completely filled with particles

that really don't want to be close to each other but have no choice.

that really don't want to be close to each other but have no choice.

They desperately push back against gravity, against the collapse.

They desperately push back against gravity, against the collapse.

If gravity wins, they will become a black hole.

If gravity wins, they will become a black hole.

If they win, they become a neutron star.

If they win, they become a neutron star.

This makes neutron stars like giant atomic nuclei the size of a city,

This makes neutron stars like giant atomic nuclei the size of a city,

but holding the mass of our Sun.

but holding the mass of our Sun.

And here, things get weird.

And here, things get weird.

The environment in the core of neutron stars is so extreme

The environment in the core of neutron stars is so extreme

that the rules of nuclear physics change.

that the rules of nuclear physics change.

And, this could lead to a strange and extremely dangerous substance.

And, this could lead to a strange and extremely dangerous substance.

But, let's not get ahead of ourselves.

But, let's not get ahead of ourselves.

We first need to know the rules before we learn how they can be broken.

We first need to know the rules before we learn how they can be broken.

Protons and neutrons, the particles making up the nuclei of atoms,

Protons and neutrons, the particles making up the nuclei of atoms,

are made up of smaller particles called ᠎quarks.

are made up of smaller particles called ᠎quarks.

Quarks really don't want to be alone.

Quarks really don't want to be alone.

They are what we call ᠎confined.

They are what we call ᠎confined.

You can try to separate them, but the harder you pull,

You can try to separate them, but the harder you pull,

the harder they try to pull themselves back together.

the harder they try to pull themselves back together.

If you use a lot of energy, they just use this energy to create new quarks.

If you use a lot of energy, they just use this energy to create new quarks.

Quarks only exist together as the building blocks of other particles,

Quarks only exist together as the building blocks of other particles,

and have never been observed by themselves.

and have never been observed by themselves.

They come in many types, but only two appear to make stable matter:

They come in many types, but only two appear to make stable matter:

the ᠎up and down quarks found in protons and neutrons.

the ᠎up and down quarks found in protons and neutrons.

All other quarks seem to decay away quickly.

All other quarks seem to decay away quickly.

But, this may be different inside neutron stars.

But, this may be different inside neutron stars.

The forces operating in ᠎their cores are so extreme,

The forces operating in ᠎their cores are so extreme,

that they are actually similar to the universe shortly after the Big Bang.

that they are actually similar to the universe shortly after the Big Bang.

Neutron star cores are like fossils

Neutron star cores are like fossils

which can let us peer back in time to the beginning of everything.

which can let us peer back in time to the beginning of everything.

So, learning how quarks behave inside a neutron star

So, learning how quarks behave inside a neutron star

is a way of understanding the very nature of the universe itself.

is a way of understanding the very nature of the universe itself.

One hypothesis, is that inside a neutron star core

One hypothesis, is that inside a neutron star core

protons and neutrons ᠎deconfine.

protons and neutrons ᠎deconfine.

All the particles cram shoulder-to-shoulder,

All the particles cram shoulder-to-shoulder,

dissolve, and melt into a sort-of bath of quarks.

dissolve, and melt into a sort-of bath of quarks.

Uncountable numbers of particles become one giant thing made purely from quarks:

Uncountable numbers of particles become one giant thing made purely from quarks:

quark matter᠎.

quark matter᠎.

A star made from this is called a ᠎quark star.

A star made from this is called a ᠎quark star.

Though, from the outside, it may not look any different than a regular neutron star.

Though, from the outside, it may not look any different than a regular neutron star.

Now, we can finally talk about the most dangerous substance.

Now, we can finally talk about the most dangerous substance.

If the pressure inside a quark star is great enough

If the pressure inside a quark star is great enough

it may get stranger.

it may get stranger.

Literally.

Literally.

In the cores of neutron stars, some of the quarks᠎ ᠎may be converted into ᠎strange quarks.

In the cores of neutron stars, some of the quarks᠎ ᠎may be converted into ᠎strange quarks.

Strange quarks have bizarre nuclear properties and they are heavier

Strange quarks have bizarre nuclear properties and they are heavier

and, for the lack of a better word, stronger.

and, for the lack of a better word, stronger.

If they turn up, they could create strange matter.

If they turn up, they could create strange matter.

Strange matter might be the ideal state of matter;

Strange matter might be the ideal state of matter;

perfectly dense, perfectly stable, indestructible.

perfectly dense, perfectly stable, indestructible.

More stable than any other matter in the universe.

More stable than any other matter in the universe.

So stable, that it can exist outside neutron stars.

So stable, that it can exist outside neutron stars.

If this is the case, we have a problem:

If this is the case, we have a problem:

it might be infectious.

it might be infectious.

Every piece of matter it touches might be so impressed by its stability

Every piece of matter it touches might be so impressed by its stability

that it would immediately turn it into strange matter, too.

that it would immediately turn it into strange matter, too.

Protons and neutrons would dissolve and become part of the quark bath

Protons and neutrons would dissolve and become part of the quark bath

which frees energy and creates more strange matter.

which frees energy and creates more strange matter.

The only way to get rid of it would be to throw it into a black hole.

The only way to get rid of it would be to throw it into a black hole.

But, then again, who cares?

But, then again, who cares?

All of it is inside neutron stars.

All of it is inside neutron stars.

Except when neutron stars collide with other neutron stars,

Except when neutron stars collide with other neutron stars,

or black holes,

or black holes,

they spew out tremendous amounts of their insides

they spew out tremendous amounts of their insides

some of which could include little droplets᠎ ᠎of strange matter called ᠎strangelets.

some of which could include little droplets᠎ ᠎of strange matter called ᠎strangelets.

Strangelets are as dense as the core of a neutron star.

Strangelets are as dense as the core of a neutron star.

They could be really small, maybe even subatomic,

They could be really small, maybe even subatomic,

but even the largest strangelets wouldn't be any bigger than a rocket.

but even the largest strangelets wouldn't be any bigger than a rocket.

These strangelets would drift through the galaxy for millions or billions of years

These strangelets would drift through the galaxy for millions or billions of years

until they meet a star or planet by chance.

until they meet a star or planet by chance.

If one were to strike Earth, it would immediately start converting it into strange matter.

If one were to strike Earth, it would immediately start converting it into strange matter.

The more it converts, the more it would grow.

The more it converts, the more it would grow.

Ultimately, all of the atoms making up Earth would be converted.

Ultimately, all of the atoms making up Earth would be converted.

Earth would become a hot clump of strange matter, the size of an asteroid.

Earth would become a hot clump of strange matter, the size of an asteroid.

If a strangelet strikes the Sun, it would collapse into a strange star,

If a strangelet strikes the Sun, it would collapse into a strange star,

eating through it like fire through a dry forest.

eating through it like fire through a dry forest.

This would not change the Sun's mass much, but it would become way less bright,

This would not change the Sun's mass much, but it would become way less bright,

so Earth would freeze to death.

so Earth would freeze to death.

And, like a tiny virus, we'd have no way to see a strangelet coming.

And, like a tiny virus, we'd have no way to see a strangelet coming.

Worse still, some theories suggest strangelets are more than common

Worse still, some theories suggest strangelets are more than common

outnumbering all stars in the galaxy.

outnumbering all stars in the galaxy.

These strangelets could have formed very early after the Big Bang

These strangelets could have formed very early after the Big Bang

when it was as hot and dense as a neutron star core everywhere.

when it was as hot and dense as a neutron star core everywhere.

They might be clumping around the gravity of galaxies,

They might be clumping around the gravity of galaxies,

as the universe expanded and evolved.

as the universe expanded and evolved.

Strangelets could even be so numerous and massive,

Strangelets could even be so numerous and massive,

that they might actually be the dark matter we suspect holds galaxies together.

that they might actually be the dark matter we suspect holds galaxies together.

But, then again, maybe not.

But, then again, maybe not.

This is speculation, and the Earth and Sun and planets

This is speculation, and the Earth and Sun and planets

haven't been consumed in a wildfire of strangelets in the past few billion years

haven't been consumed in a wildfire of strangelets in the past few billion years

so the odds seem good that it won't happen anytime soon.

so the odds seem good that it won't happen anytime soon.

Understanding these strange objects today may be the key to understanding the birth of our universe