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Are you alone in the universe?

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Or are you connected to anything?

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

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but we can make YouTube[br]videos already,

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and build Large Hadron Colliders!

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We’ve also split the atom and[br]invented Pokémon.

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We stem from an ancient lifeform

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

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

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

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to kill us off for good!

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Humanity credits itself with being[br]able to destroy the planet,

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but even with all our nuclear toys,

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

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

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Big deal!

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

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Most microscopic life and[br]life below the surface

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wouldn’t even be disturbed[br]that much, probably.

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On a geological timescale,[br]our impact on Earth

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is kind of laughable.

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We’re actually not that powerful.

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We live on this tiny wet rock[br]that speeds through space

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following a massive ball of[br]burning plasma.

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One day, this ball of plasma[br]will stop burning

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and most likely kill us in the process.

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If we survive the death of the Sun[br]and colonize the galaxy,

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theoretically, we could survive until

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the last star in the universe goes out.

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After that, life becomes[br]pretty impossible.

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Okay, so everything has an end.

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Where does this leave you[br]as an individual?

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

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

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A creature just 0.1 mm in diameter.

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Today, you consist of about[br]50 trillion cells.

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50 trillion incredibly complex[br]little biological machines

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

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They operate by the laws of[br]physics and chemistry

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

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transport resources, transmit information,[br]or reproduce.

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They communicate, duplicate, commit[br]suicide, fight off intruders, and fulfil

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

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so you can have babies.

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

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

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a molecule that encodes[br]the genetic instructions

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

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

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

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

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That’s pretty long!

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

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Take a second to think about this:

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

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

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It evolved, it mutated, it[br]duplicated trillions of times,

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

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

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with your DNA.

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But you are more than your DNA.

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Your body is made of[br]seven octillion atoms.

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That’s seven billion billion billions.

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

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oxygen, carbon, and hydrogen.

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Oxygen and hydrogen are predominantly[br]found in water,

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

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Carbon is, maybe, the most[br]important element for life.

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

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

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

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nitrogen, calcium, phosphorus, potassium,[br]sulfur, sodium, chlorine, magnesium,

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iron, fluorine, zinc, copper, iodine,[br]selenium, chromium, manganese,

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molybdenum, cobalt, lithium, strontium,[br]aluminum, silicon, lead, vanadium,

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arsenic, and bromine… phew!

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

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no matter what your favorite music is.

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Anyway, these elements perform[br]various functions like

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enabling oxygen transport,[br]building of bones and cell structures,

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carrying signals, driving chemical[br]reactions, and a lot more.

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Your body is in a constant[br]state of transition.

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

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

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

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

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weren’t there five years ago.

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

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But where did these atoms come from?

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

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Enormous gas clouds formed over millenia[br]and grew denser and denser,

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

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In the cores of these stars,

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hydrogen was converted into helium[br]under extreme conditions.

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After millions of years, the[br]hydrogen became exhausted,

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and the stars began dying.

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Under super-extreme conditions,[br]all elements we know today

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

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They shot most of their[br]contents into space,

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while the cores collapsed and[br]became black holes.

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

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

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our Sun.

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These elements, that once[br]were the insides of a star,

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formed planets and found[br]their way onto Earth,

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where they enabled life to begin.

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

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We are part of the universe.

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

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is really mindblowing.

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

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We know that we are made of little[br]parts that connect us

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to everything in the universe, to[br]the beginning of everything.

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Then this is kind of a nice thought:

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you are not alone; you never[br]were; you never will be.