How the Universe Works

The universe...

Vast, dynamic, and explosive.

But this huge cosmos, with its billions of galaxies

and countless stars,

isn't the only one... We share our lives with

another universe.

The world of the small,

of the viruses, of the bacteria.

We call this strange hidden kingdom the microcosmos.

The microcosmos is incredibly important.

Even though we can't see it, it's everywhere.

It's almost like another universe

or another world all in its own.

It guided our evolution...

We wouldn't be here without the microcosmos.

...and it keeps us alive.

The microcosmos is responsible for

the very oxygen that we breathe.

And it will influence our future as we venture out

into space.

And if we were ever to find a place where

there is life, potentially a new microcosmos,

we would have no immunity if they're bad.

We share our world with the microcosmos.

Will we coexist in an uneasy peace,

or will it destroy us?

A strange invisible assassin stalks its prey.

It attacks and hijacks the cell,

forcing it to produce hundreds of new raiders.

This is what happens when the microcosmos turns on us.

In 2020, we experienced this invasion

of the body snatchers first-hand.

A tiny virus caused a global pandemic... COVID-19.

This pandemic makes me see the world completely

differently, because there was an invisible universe,

one that covers me and is within me

that I pretty much ignored for the most part.

Maybe we ignore this other universe

because it's invisible to the naked eye.

We live in a largely invisible universe.

We can't see everything that's going on.

Some of the biggest stuff we can't see very well,

and, in fact, a lot of the littlest stuff we can't either.

Just because something is too small to see

doesn't mean it's not important.

In fact, very, very tiny things

have a huge impact on our lives.

Some of these impacts are beneficial,

but they're overshadowed by the devastating effects

of disease.

The longest-running conflict that humanity has been

engaged in is that against

the microcosmos, our long running battle against

the bacteria and viruses

that are trying to kill us.

A century ago, we faced the Spanish flu.

This absolutely annihilated Europe at the time.

It caused millions upon millions of death.

So this is definitely not the first pandemic,

quite frankly, probably isn't the last one.

In a way, the coronavirus has forced us to come

to a greater understanding of the microscopic world.

The microcosmos is complex.

While some parts kill us, others keep us alive.

Microcosmos is important for us to survive,

in order for us to do all of the things

that our body does, in order for us to live

and grow and thrive.

Our lives depend on the microcosmos.

The air we breathe and the surface of the Earth around

us has been profoundly affected by the microcosmos.

Three invisible microcosmos operates

in every part of the world.

This world that you can't see is everywhere,

from geothermal hot springs to glaciers

to deep sea hydrothermal vent systems.

We have discovered that every cubic foot of

Earth's atmosphere and its oceans contain millions

of viruses.

There are more viruses here on Earth

than there are stars in the universe.

That's incredible.

Even though they're around 1/400th

the thickness of human hair, stuck end to end,

all the viruses on Earth would stretch

100 million light-years.

That's 40 times the distance to our neighboring

galaxy, Andromeda.

That really makes us ask,

"Whose planet is this anyway?"

If you just added this up by sheer numbers,

you would say, "This is the virus planet."

The microcosmos has also taken over

our bodies... We're only partly human.

The fact that so little of my own body, of everyone's body,

is human cells kind of leaves you wondering

what's the rest of it made of, right?

It is astonishing that we share our bodies with over

380 trillion viruses.

And over 39 trillion bacterial cells.

The average human has more bacterial cells

inside their body than there are human cells inside their body.

So what are we really?

There are moments in the history of science that I actually

remember where I was when they happened... when,

for example, we detected two colliding black holes

or something like that.

But another one was when I realized that

almost half our body is actually not human.

- I mean, that is crazy. - For people that are

scared of bacteria, that's a really interesting

thing to know, right?

Bacteria help us digest food,

produce vitamins, and even influence our mood.

But what are they?

Bacteria are single-celled organisms with a cell wall

and a central nucleus containing genetic material,

RNA or DNA.

They can move around and replicate.

Viruses are completely different.

In the universe,

there are some mysteries that have actually personally made

me kind of pause,

give me goosebumps, and strangely enough,

one of them is viruses.

The mystery is how viruses can

have so much impact on the world,

despite their tiny size and apparent simplicity.

Most are just a strand of genetic material,

sometimes encased in a shell of protein.

I mean, compared to bacteria,

which behave kind of like other normal cells that we're

used to, to some degree, viruses are very strange.

We don't really understand viruses.

We... we don't even know if they're alive or not.

The question are viruses alive is actually

more difficult to answer than you might think.

What is the definition of life?

What does it mean to be alive?

NASA's definition of life is a self-sustained

chemical system capable of Darwinian evolution.

Entities that feed make energy and reproduce.

Viruses can't do that on their own.

They have to have a host cell to do that.

They have the genetic material that they need,

but none of the machinery.

So they really have to infect a host.

If not, they're useless.

Inside a host's body, viruses latch

onto the surface of cells

and then take control.

A virus's life cycle is effectively to hack

another cell.

They have to inject that genetic material

into a living cell.

And then the cell is hijacked and starts making copies of

the virus.

Which then have to burst out of this cell almost literally

like that gory, grotesque scene in "Aliens."

They burst out from the inside.

That's like a cellular level horror movie.

This method of replicating is chilling

and doesn't answer the question of whether

they're alive.

That uncertainty may influence our search for life in space.

One of the interesting things to think about is

if we found a virus on another planetary surface,

would we classify that as life?

Would we say that we have found life?

We don't know, but space viruses could be

a sign of other extraterrestrial life forms.

Viruses have to have a host cell to replicate,

so if you find a virus, in essence, you've found life.

Viruses might lead us to extraterrestrial life.

Now, new research suggests that life

on Earth may have come from space,

brought to us in a cosmic bombardment

when our planet was young.

We find the microcosmos in every feature of Earth.

But where did this strange kingdom of the very small

come from?

Some of its members are so weird, they look like aliens.

Could they have come from space?

There's this idea that microbes could have hitched

a ride on a chunk of an asteroid

that would fall to Earth.

They could form on a different planet.

Something hits that planet.

The rock that they're sitting on gets lifted

and then hits the Earth as a meteorite.

The idea of hitchhiking bugs sounds a bit wild,

but we have found chunks of Mars on Earth.

Perhaps these space rocks brought life.

It's not completely ridiculous.

We know that rocks, for example,

could come from Mars and land on Earth.

A giant asteroid impact on Mars could blow

shrapnel into space that could land on Earth.

To learn how we must return to the early

solar system, 4.5 billion years ago.