There's a crime wave
sweeping the world right now. - [Newsreader] The troubling trend targeting a key car component. - [Newsreader 2] Thieves targeting cars for their catalytic converters. - These thefts that take
just minutes to carry out. - And a thief can remove one from your car in 60 seconds or less. - You feel violated. - [Joe] The thieves are
on the hunt for something that fetches big bucks
on the black market. - [Newsreader 3] A nearly
$7 million theft ring. - [Newsreader 4] They
want the valuable metals inside the converters. - [Interviewee] This
would be a very quick way for them to make a quick buck. - [Joe] Numbers are
absolutely skyrocketing and public officials are
scrambling for answers. - We're trending in the wrong direction. - And people are getting tired of it. - This is a growing problem,
there's no excuse for it. - Turns out we can blame it all on this: (stars whirring) (curious music) Hey smart people, Joe here. So back in the '70s, air
pollution was out of control. Many U.S. cities were
completely blanketed in smog and people were getting sick, all these warnings about acid rain, and one of the big
culprits was car exhaust. So the U.S. passed these
huge, new environmental laws like the Clean Air Act, which led to one of the most
monumental innovations ever in cleaning up the way that we drive: the catalytic converter. A catalytic converter is basically an extra little chamber along
your car's exhaust pipe, EV owners, this doesn't apply to you. This magical little box takes dangerous chemicals
and engine exhaust and transforms them into
relatively harmless gases that are better for the
environment and public health. I mean, car exhaust still
causes global warming but at least this solved
that whole smog thing. But in recent years, catalytic converters have become one of the
most stolen items on cars. Thefts have risen almost 4000% since 2018 (burglar cackles) and numbers are still on the rise and that's all because of what's inside. That little thing on your exhaust that you've probably never looked at, is a literal treasure chest
full of valuable metals, platinum, palladium and this one, rhodium, the most expensive metal on planet earth. But why do we need this
crazy-expensive metal in something that cleans literally the dirtiest stuff that
comes outta your car? Well, because of the very unique chemistry that happens inside of
a catalytic converter. Rhodium belongs to a family of metals that are extremely resistant to oxidation and corrosion and heat. So it can stand up to conditions inside
your car's exhaust system and all of the junk that comes through it, but it also has another
super important property: it's a catalyst, which means it can speed up
certain chemical reactions. Here's an example: burning gasoline creates harmful chemicals like nitrogen oxides, which
can damage the ozone layer, contribute to acid rain,
and warm up our planet. But the rhodium in a catalytic converter turns it into harmless
nitrogen and oxygen gas and it can do this over
and over and over again, as long as nobody saws it off your car in the middle of the night. A catalytic converter has something like a couple
of grams of rhodium in it, which has a street value of almost $1,000. To put this in perspective, right now, a one kilogram bar of gold is worth around $57,000. That's a lot of money, but
that same amount of rhodium would be worth more than
half a million dollars. Here's a little periodic table I have that has actual samples of all of the non-dangerous,
non-deadly elements. This little microscopic piece
of rhodium I have in here, hold on, we're gonna need to enhance. Let's move... Grab the
macro lens or something. So this tiny little piece
is worth almost $10. So why is this stuff so expensive? When we look at rhodium and it's neighbors on the periodic table we find a lot of stuff
that's ridiculously rare, at least in Earth's crust
where we can get to it easily. If we represent the total of all the elements in Earth's crust by a roll of toilet paper
stretching from here to London, rhodium would make up just this much. To figure out why these
precious metals are so rare, we have to talk about
how elements are made. And to understand how elements are made and where they come from, we have to spend a little
bit of time with this. Every box on the periodic
table represents one element. And the type of element you are is determined by the
number of protons you have. If you're an atom with just one proton, you're hydrogen, here at
the upper-left corner. If we add a proton, we have
element two, helium, instead. Six protons, carbon. Eight, you're oxygen, and so on. Protons are positively charged, but like charges repel each other like identical ends of a magnet. So why doesn't that repulsion
make a nucleus fall apart? Well, because there's
another fundamental force at play inside a nucleus,
the nuclear force. You can think of the
nuclear force as Velcro that only works when protons or neutrons are pushed very close together. See, atoms contain both
protons and neutrons. Neutrons also have this
sticky nuclear force Velcro, but unlike protons they're uncharged, they don't repel other stuff. So neutrons act like an atomic glue that can help hold a nucleus together. Adding or subtracting neutrons
can change an atoms mass but not what type of element it is. It's only when we add
or take away a proton along with enough neutrons to keep a nucleus from falling apart that we make a new chemical element. And to get protons and
neutrons close enough together for that nuclear Velcro to do its thing requires a lot of heat and energy. Amounts that we only
find in special places and at special times. The hot, dense universe that
existed just after the Big Bang created the perfect conditions to squish protons and neutrons together. That's how the lightest, most abundant elements on the
periodic table were created. Stuff like hydrogen and helium. In fact, all of the hydrogen
that exists in the universe was created in those first few
minutes after the Big Bang. But to create heavier and heavier nuclei, you need more and more energy. Unfortunately, the Big
Bang only happened once, 13.8 billion years ago. And all of its energy
has been spreading out as the universe continues to expand. So where else can we find enough energy to squish nuclei together? The fusion reactions that make stars burn turn lighter elements into heavier ones by smashing nuclei together. Two atoms of hydrogen
make one atom of helium, smash three helium nuclei
together, you get carbon, add one more helium
nucleus, you get oxygen, you get the idea. But cooking up these
different elements gets harder as we move down and
across the periodic table. If a nucleus gets big enough,
even the immense pressures and energies inside the core of a star aren't enough to keep
sticking on new protons. It turns out that iron
is the heaviest element that can be made in a star. So what about the rest
of the periodic table? Well, everything after
uranium was made by humans but we still need a way
to make all of these. Luckily, there is one more way
to add protons to a nucleus: by adding neutrons. Because neutrons don't have a charge, it takes less energy to get
them to stick to a nucleus but adding neutrons can also
make a nucleus unstable. That's why radioactive
isotopes spontaneously decay and eject subatomic particles
and radiation in the process. Sometimes a neutron that's
been captured by a nucleus can decay into a proton. And since that's one more
proton that wasn't there before we've created a new element. If that seems weird and confusing, well, welcome to physics. This way of adding protons to a nucleus by actually adding neutrons is how most elements on the
periodic table are born. But in this story, every answer seems to bring
us to one more problem. Where do you go to find
big piles of neutrons just waiting to get smashed onto nuclei? Before I answer that, first I wanna take a quick
moment to thank our patrons, because while we're on the
subject of making new things, your support helps us make these videos. We can't thank you enough. And if you wanna join our
community of supporters, just check out the link
down in description. I also wanna let you know that another great way to
support the show for free is by watching new episodes
when they're first released. This helps spread the show to other subscribers and to new viewers. If you are already part of
the early squad, thank you. And if not, hit the bell icon
next to the subscribe button, our whole community of curious
learners will thank you. So where do you go to
find big piles of neutrons waiting to get smashed onto nuclei? Well, one place is dying low-mass stars. The ones that don't go out
in those violent explosions like their more massive cousins. They've got lots of free
neutrons floating around so every so often a nucleus can grab one, it decays into a proton and becomes a slightly heavier element. That new element can grab
neutron after neutron, some occasionally decaying
into protons along the way, forming heavier and heavier elements. This is a slow process that basically walks box by
box along the periodic table. But it takes billions of
years for these stars to die so it's not like they've
got anything better to do. But there's another way to add
a bunch of neutrons at once. And one place that we
find it is in a supernova, the explosive end of a massive dying star, which is full of free neutrons and a whole bunch of stellar junk. In the immense energy of
a supernova explosion, lots of neutrons can be
slapped onto a nucleus at once before they have time to decay. Then when that decay finally does happen, you've effectively added a whole bunch of protons all at once. So instead of tiny steps, we can take big leaps
across the periodic table and end up with really
heavy elements, super quick. We used to think a
supernova was the only place that this rapid neutron
capture could happen. Today, we know that's not true. After they collapse and
go boom, exploding stars often leave unthinkably dense
neutron stars in their wake. Unsurprisingly, neutron
stars are full of neutrons and if two neutron stars
come close enough together, spiral together and merge, they release tidal waves
of these free neutrons. Exactly the ingredients to take those big leaps
across the periodic table. Creating new elements
and merging neutron stars used to be purely theoretical, but in recent years we've actually witnessed these collisions and felt their gravitational aftershocks. The light given off by one merger 900 million light-years away confirmed that heavy elements like gold do form during these violent events. Sometimes enough to make
10 Earth's worth of gold in a single merger. Is this same process true for rhodium too? Well, we don't really
know, but scientists think that it's likely colliding
neutron stars could, in fact, be where most
of the heavy metal end of the periodic table is born. But there's still much
about these processes that scientists don't fully understand. Rhodium and some of its rare neighbors, they likely form in other ways too, perhaps somewhere in between
these rapid and slow processes. But even in a universe that's experienced several
generations of dying stars across nearly 14 billion
years of existence, these explosive atomic nurseries are rare and pretty spread out. Across the universe, elements
made in these processes are about a million times more scarce than elements like carbon and oxygen. So that's why this strange
crime wave is taking over and why people are sawing
catalytic converters off of your Prius. There's just not very
much rhodium anywhere because the universe
is a really big place. Two neutron stars colliding and spewing all of their
heavy metals into space is like putting a drop
of ink in the ocean. The cloud of stellar dust that condensed into our solar system and eventually this little rocky planet, that was like taking
a bucket of that ocean and making a whole world from it. Maybe in the future as
car technology evolves, catalytic converters filled with the most expensive
substances on Earth won't even be a thing, but for now, this is one crime wave that
you can blame on the universe. Stay curious. And one more thing, history lovers, we need to tell you about
a brand new series from PBS called "The Bigger Picture." It's hosted by Harvard
professor Vincent Brown and it's a show that
examines famous photographs, unpacks all of the historical context and stories around them. Their latest episode gives the backstory about "The Blue Marble," one of the most iconic images
of planet Earth ever captured. You can check out that episode and the first episode at
the link in the description and be sure to tell them
"Be Smart" sent you. A neutron walks into a bar and says, "Hey how much for a drink?" The bartender says, "For you, no charge." 'Cause they don't have a charge. Why is this so hard to cut? (crew member laughs) This is so hard to cut.
