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  • So what is human existence?

  • How can you actually sum it up?

  • It turns out it's really pretty simple.

  • We are dead stars, looking back up at the sky.

  • Everything you are, I mean literally the iron in your blood, comes from the instant before a star dies.

  • You cut yourself, and you see that red from that oxygenated hemoglobin.

  • That was the instant of the death of a solar system.

  • The universe began with only the element hydrogen,

  • the very very simplest atom that exists.

  • And the only thing in the universe that can make a bigger atom is a star.

  • The entire periodic table, every element you ever heard of was processed inside the body of a star.

  • That star then unravelled or exploded.

  • And here we are.

  • All a star is, is a dust cloud that is collapsing under the force of gravity.

  • That's it. And when you compress gas together, it actually heats up.

  • There's a time when that's hot enough to set off a nuclear fusion reaction.

  • That actually supports the star.

  • This nuclear explosion inside supports the star against further collapse.

  • But that nuclear fusion reaction is using fuel, it's using hydrogen.

  • And so eventually, that will burn out, and the collapse of gravity will keep going.

  • In the case of a more massive star, the gravity crushes more and more tightly.

  • Things get hotter inside, you create things like carbon, oxygen, nitrogen,

  • until finally, you get to the element iron.

  • It fuses iron together, and instead of energy coming out, energy is actually absorbed.

  • And the core of the star collapses.

  • And that sets off the most violent, brilliant reaction we know of called a supernova reaction.

  • Everything outside the element of iron, everything heavier.

  • All the gold, all the silver, all the lead, all the uranium.

  • That's formed in that supernova explosion.

  • A single star will glow as brightly as entire galaxies, that's hundreds of billions of stars, in that moment of death.

  • And that's what you are.

  • That literally what your body is...

  • Is that instant of death.

  • You know, it's so tempting. Humans have done this before, for literally tens of thousands of years.

  • They think of the stars as eternal.

  • Stars will all burn out someday.

  • There's only a certain amount of stellar fuel, hydrogen.

  • Stars are burning through it.

  • And the stars, as we know them, will all die out in some trillions of years.

  • And the universe will be dark, for the rest of time. Whatever that means.

  • But think about that, we're actually living in Eden right now.

  • We're living in a time when this ten-billion-year-lived thing, the sun,

  • is pouring down free energy, we are using it, we are evolving,

  • we are becoming sentient, we are looking out at the universe.

  • And what an amazing thing to think that that's for a tiny little brief part of the universe's history.

  • And everything else will be dark.

  • It does give you an ownership, about how wonderful this time is.

  • How wonderful your life is right now. Your literal life.

  • But also how wonderful this time of the universe is.

  • Someday I wonder, if people will have myths about the days when stars rained down free sunlight, free energy.

So what is human existence?

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