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I'm here in Washington D.C. on the National Mall, and the first thing you notice is you're
surrounded by monuments, all these buildings to commemorate our nation's history, but why
do we build these monuments?
if we took all of Earth's 4.5 billion years and stuffed it into a single year, humans
only show up on the afternoon of December 31st, and the United States doesn't show up
until the last seconds.
So maybe we build these things to extend beyond the now, the short little time that we're
here, and when you look at what they're made of, well we go beyond now, we go beyond humans,
and we even go into the depths of space.
The rock that the Vietnam War Memorial is built of was born in a hot and violent place,
it's called gabbro, and if you look deep inside the Earth's crust you find a ton of this stuff.
It's formed from the slow cooling of magma down there, and that's what gives us those
beautifully large crystals.
The gabbro in the Vietnam wall was formed something like 2 billion years ago, that's
a piece of the Earth from before North America was even around, back when almost all life
on Earth was single-celled.
Speaking of single celled life, well, not Lincoln, he's multi-cellular, but he's made
of marble.
Before that marble was marble, it was limestone, that chalky stuff, and before it was that
chalky stuff, it was alive.
The marble that the Lincoln Memorial is made of comes from Colorado, and hundreds of millions
of years ago, North America was covered by an ancient ocean.
It was filled with these single celled plankton called coccolithophores, which have these
beautiful shells that are ornate.
The Cliffs of Dover are made of these dead remnants that pile up over time.
Even though these coccolithophores are microscopic, you can see them bloom from space.
I'm standing here in front of the Smithsonian Castle, it's made of this beautiful red Seneca
sandstone.
It gets that red color in it from all the iron in it.
And that iron, in fact all the iron in the universe from our blood to the buildings that
we're surrounded by, was born in dying stars.
[carousel music]
So there's something really special about that iron.
Take a star like our sun, it's filled with hydrogen, and those hydrogen atoms are flying
around, and when they get really close the electromagnetic force usually repels them
apart, but every once in a while they get close enough with enough energy that they
snap together into a helium atom, and that fusion releases a ton of energy, and that's
the energy that we live off of here on Earth.
After a while, our star is gonna run out of hydrogen, and then it's going to collapse
a little bit, and those helium atoms are going to become larger and larger atoms, that process
is going to continue until we get to iron.
That castle, the Smithsonian Castle, is built from the iron that was born deep in space,
in the center of dying stars.
That is even more amazing, than this carousel ride.