Are you alone in the universe?

Or are you connected to anything?

First of all, you’re part of a group of
mammals that’s still very young,

but we can make YouTube
videos already,

and build Large Hadron Colliders!

We’ve also split the atom and
invented Pokémon.

We stem from an ancient lifeform

that began living about
three and a half billion years ago.

We feel like we’re in control of this
planet, but we aren’t really.

One little asteroid or one creative virus
is really all it would take

to kill us off for good!

Humanity credits itself with being
able to destroy the planet,

but even with all our nuclear toys,

we would probably just cause a
huge mass extinction, at best.

Maybe we could kill 90% of
everything living on this planet.

Big deal!

A few million years later, life
would be back everywhere.

Most microscopic life and
life below the surface

wouldn’t even be disturbed
that much, probably.

On a geological timescale,
our impact on Earth

is kind of laughable.

We’re actually not that powerful.

We live on this tiny wet rock
that speeds through space

following a massive ball of
burning plasma.

One day, this ball of plasma
will stop burning

and most likely kill us in the process.

If we survive the death of the Sun
and colonize the galaxy,

theoretically, we could survive until

the last star in the universe goes out.

After that, life becomes
pretty impossible.

Okay, so everything has an end.

Where does this leave you
as an individual?

At one point in your life,
for about half an hour,

you were only one single cell
inside your mother’s womb.

A creature just 0.1 mm in diameter.

Today, you consist of about
50 trillion cells.

50 trillion incredibly complex
little biological machines

that are much bigger and more complex
than the average bacteria!

They operate by the laws of
physics and chemistry

and use micromachines to build proteins,
make energy usable, devour food,

transport resources, transmit information,
or reproduce.

They communicate, duplicate, commit
suicide, fight off intruders, and fulfil

super-specialized duties for the
greater good of keeping you alive

so you can have babies.

But where is the “you” part in this, if
you’re made of trillions of little things?

The basic information for “you”
is stored in the DNA,

a molecule that encodes
the genetic instructions

used in the development and functioning
of all known living things.

If you were to unravel it,
it would be two meters long!

If you combined all the little
DNA strings in all your cells,

you’d get a string so long that it would
stretch to Pluto and back to Earth.

That’s pretty long!

And your DNA is a direct connection
to your very first ancestor.

Take a second to think about this:

in every cell of your body,
there’s a little string of stuff

that’s been there in various forms
for 3.4 billion years.

It evolved, it mutated, it
duplicated trillions of times,

but it directly connects you to the
first living being on this planet.

We could say you “touched” every living
being that came before you

with your DNA.

But you are more than your DNA.

Your body is made of
seven octillion atoms.

That’s seven billion billion billions.

Roughly 93% of the mass the human body
is made up of just three elements:

oxygen, carbon, and hydrogen.

Oxygen and hydrogen are predominantly
found in water,

which makes up about 60%
of the body by weight.

Carbon is, maybe, the most
important element for life.

It can easily bond with other atoms,
which allows for the building of long

complex chains of molecules,
which make up the solid part of you.

The remaining 7% is a tour of
the periodic table of elements:

nitrogen, calcium, phosphorus, potassium,
sulfur, sodium, chlorine, magnesium,

iron, fluorine, zinc, copper, iodine,
selenium, chromium, manganese,

molybdenum, cobalt, lithium, strontium,
aluminum, silicon, lead, vanadium,

arsenic, and bromine… phew!

By the way, this also means
you’re about 0.5% metal,

no matter what your favorite music is.

Anyway, these elements perform
various functions like

enabling oxygen transport,
building of bones and cell structures,

carrying signals, driving chemical
reactions, and a lot more.

Your body is in a constant
state of transition.

Every 16 days, 75% of “you”
has been replaced,

because a healthy human exchanges about
100% of their water in that time period.

Each year, about 98% of your atoms are
replaced by new ones,

and every 5 years, close to all of the
atoms that make up your body

weren’t there five years ago.

So, you could call yourself
a temporary collection of atoms.

But where did these atoms come from?

In the beginning of the universe, there
were mostly hydrogen and helium atoms.

Enormous gas clouds formed over millenia
and grew denser and denser,

until they collapsed under their own
gravity, giving birth to the first stars.

In the cores of these stars,

hydrogen was converted into helium
under extreme conditions.

After millions of years, the
hydrogen became exhausted,

and the stars began dying.

Under super-extreme conditions,
all elements we know today

were created a fraction of a second before
they died and exploded in supernovas.

They shot most of their
contents into space,

while the cores collapsed and
became black holes.

All these elements traveled through space
for who knows how long.

Until they arrived at a different cloud
that was slowly forming a new star—

our Sun.

These elements, that once
were the insides of a star,

formed planets and found
their way onto Earth,

where they enabled life to begin.

So we are directly connected to
the first stars ever born in the universe.

We are part of the universe.

The idea of being a deeply connected
minuscule part of an enormous structure

is really mindblowing.

We don’t know what all this means,
or if it means anything at all.

We know that we are made of little
parts that connect us

to everything in the universe, to
the beginning of everything.

Then this is kind of a nice thought:

you are not alone; you never
were; you never will be.