To me it’s amazing some of the things that
we actually do know.
There’s plenty of things that are conjecture
or theories but there’s a lot of stuff that
we have real observations and real knowledge
of.
And amazingly, to me, one of the things is:
where did all the atoms in our body come from?
And it is actually a real fact, not a theory,
that when you look back at how the universe
looked about, say, 13 billion years ago, the
chemistry was very, very different.
We can actually see so far away out into space
that the light we’re looking at took billions
and billions of years to get to us even at
the speed of light.
And the farthest away we can see is to a time
that was about 400,000 years after the Big
Bang.
That’s pretty impressive.
That’s about 13.5 billion years ago.
And when you look back that far the only thing
you see is very hot hydrogen gas, a little
bit of helium, a tiny bit of lithium, but
that’s it.
That’s not a theory.
That’s actually an observation.
And as you look at galaxies very far away
in space and therefore very far back in time,
you can actually watch the chemistry change.
You watch different atoms get built up.
And the only thing in the universe that we
know that can make a large atom—by large
I mean something like oxygen or carbon or
calcium or anything that makes up our bodies—is
actually the very core of a star.
That’s where nuclear fusion reactions ram
hydrogen together.
The hydrogen was formed during the Big Bang.
You take these hydrogen atoms, you smash them
together and you build larger and large atoms
until you build something like the carbon
that makes up most of my body.
And so we’ve known for a while that the
only way you get these large atoms is stars.
But even with something as powerful as the
core of a star there were some atoms that
were a little bit more slippery; we couldn’t
quite figure out how you get the energy needed
to make something really big like a gold atom.
That should take even higher temperatures,
even more energy than what you typically find
in the core of a massive star.
So what is even more violent than an exploding
mass of star, which makes a lot of heavy elements
of the universe?
One of the things we discovered recently is
that two dead cores of stars called neutron
stars can actually spiral together and collide.
And when they collide instead of a normal
death of an exploding star you basically have
something like that on steroids.
You have an explosion that’s so big and
so violent people have really seen nothing
like it since the Big Bang.
Sometimes they call this a hyper nova, sometimes
they call it gamma ray burst because of the
burst of high energy radiation that comes
out.
But wonderfully we’ve been observing more
and more of these colliding neutron stars
and they are just pumping out gold atoms,
platinum atoms and, interestingly enough,
bismuth—but these very, very large, difficult-to-form
atoms.
And there’s so much gold created in one
of these explosions that if you just look
at the rate, you know, how many of these explosions
do we observe—amazingly we observe about
one a day—and how much gold is created in
one of those?
And you can actually account for the entire
abundance of gold in the universe just from
that one thing, those colliding neutron stars.
So the gold you have, I mean yes, you have
gold in your jewelry.
That’s really cool.
I’ve got a gold ring.
But interestingly enough our neurons don’t
work without a tiny, little bit of gold to
help our brain actually charge the neurons
in our brain.
We need a little bit of gold and a little
bit of copper.
So your brain wouldn’t work without a little
bit of gold, a couple of gold atoms in the
neurons.
So the reason we’re here thinking and moving
and actually existing the way we do is intimately
connected to these colliding dead stars, these
colliding neutron stars that most likely created
all of the gold in this room.
