How do fireworks work?

Daniel and Jorge blow your mind with the physics and chemistry of how fireworks sparkle and entertain.

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:08):
Hey, Daniel, I have an explosive question for you. Oh
are you gonna ask me about how to blow things up?
Isn't that what you do every day anyways at the
particle Collider. I mean, like on a more everyday basis.
How do you feel about summer fireworks? M I used
to love fireworks as a kid. I used to love him.
You don't like him anymore. I guess I just used
to have a more sparkling personality. Well, you can be

(00:31):
a real fire cracker, trust me. I'm hoping one day
that all blows over. Very bright and ploughing personality. Also,
you seem to make a lot of noise. So far,
I've never been fired from work for setting off fireworks.

(00:59):
I am hor I'm a cartoonist and the creator of
PhD comics. Hi. I'm Daniel. I'm a particle physicist and
a professor at U C Irvine, and I really do
love blowing things up. Oh yeah, do you do that
as a hobby, not just in your work. Yeah, I'm
pitching a new reality show called Will It Explode? Interesting?

(01:19):
I guess if you don't like your fingers or hands,
that sounds like a great show to join. I think
everybody would want to tune in and see how much
T and T does it take to blow up this
or that, a banana, a watermelon, a coconut. You remind
me of my cousin when we were a little I
could love to blow things up with and had that
work out for your cousin. All right, he's still alive,

(01:42):
still has all his fingers, he managed to survive success,
And I hope his job lets him blow things up
on a regular basis like mine actually fixes planes now,
so I hope, I hope it doesn't blow things up.
His job is the opposite now of his childhood passion.
That's keep things are blowing up, please because but anyways,

(02:03):
Welcome to our podcast, Daniel and Jorge Explain the Universe,
a production of our Heart Radio. We're the only thing
we want to blow up is your mind. As we
delve into the secrets of the universe and try to
understand how it all works. We take apart the very
fabric of space and time and reality and seek to
understand it at the smallest level. How does the universe

(02:24):
really work? What are its most fundamental bits, and how
do those weave themselves together to make this incredible exciting
and explosive universe that we enjoy every summer. Yeah, it
is an exploding universe. As we know, dark energy is
making the universe accelerated and expand faster and faster each day. Literally,
it is sort of exploding, and it's also full of sparkly,

(02:44):
amazing and colorful things for us to wonder about. That's right,
although thinking about the Big Bang and the expansion of
the universe as an explosion does tend to lead people
to thinking about things the wrong way. A lot of
people think about the Big Bang is like this tiny
dot of matter which then blew up into space which
already existed. So these days our vision of the early
universe isn't as much like a firecracker as it is

(03:07):
like a big rubber sheet getting stretched everywhere. Then maybe
you shouldn't have called it the Big Bang. I mean,
it's in the name Dead Hill. The Big Bang sounds
like an explosion. It does indeed sound like an explosion,
and so we'll add to the list of horribly named
astronomical concepts. I mean, you just misnamed the entire universe.
I mean, just a small error there. We should have

(03:27):
called it the Big Stretch. But it is interesting. Do
you see your job as blowing things up? You said
earlier you like blowing things up, and you're a particle physicist,
which means you collide things, because that is that also
the same thing as blowing things up. Yeah, Well, the
reason we collide things is to blow them up. Like
you want to know what's inside a proton, you can't

(03:48):
like put it on the table and tease it apart
with pliers. What you gotta do is smash two of
them together, blow them up, and see what comes out
from that explosion. So every collision inside the large Hadron
collider is like mini explosion, and we do millions of
them per second. Also, it's more like a smashing. I
don't know if it's exploding. Really, well, what happens if

(04:09):
you smash two watermelons together? They explode? Don't they know?
They're just mash If you put a grenade inside of
a watermelon, that's an explosion. Well, if I could put
a grenade inside a proton, I would totally do it.
But what would the grenade be made out of? Daniel
grenade on obviously delicious dessert explosions. But I'm also a

(04:29):
big fan of aerial explosions, though maybe more so as
a kid. Yeah, you mentioned that before, So you don't
like fireworks anymore. Like you go to display and what
either you close your ears or you close your eyes.
I used to be really amazed by them. I thought
they were fantastic when I was a kid, And now
I don't know if I've just gotten old and grumpy,
but they're just sort of less impressive. They're beautiful now,
and they're they're getting more complicated now, right Like now

(04:51):
they can you know, like sync them up with music
and do all kinds of things like multiple explosions that
make different formations up there in the sky. And as
we come up on July four, it reminds me that
the best fireworks display I ever saw for July four
for American Independence Day was actually in Switzerland. Oh yeah,
they make everything better out there, more precise. There's a

(05:14):
huge American population in Switzerland, and so in Geneva they
have an incredible July fourth fireworks display. In Geneva. It's
like outside the US, but they go all out and
have a life orchestra which plays music and coordination with
the fireworks. It really was pretty impressive. So you do
like fireworks then, Yeah, occasionally I've been known to enjoy
them occasionally. I mean it, who doesn't like fireworks? Many dogs,

(05:40):
dogs and physicists, dogs and jaded physicists. Well, when you
blow things up for a living, you know you expect
the higher standard. I guess right, right, when you smash
things for a living, you mean you know you said
you got the name for the origin of the universe wrong.
Maybe you should be a little more careful. Yeah, point taken.
But anyways, fireworks are pretty amazing and incredible and part

(06:02):
of our tradition and part of how the world celebrates
big events like independence and New Year's But it's kind
of interesting to think about how that actually works. Yeah,
it's an example of how we have put our knowledge
of how the universe works to work for us. We
manipulate these things and take advantage of them to create
these incredible bright displays. But to do so you have

(06:22):
to know some physics and some chemistry. Yeah. So today
on the program, we're we tackling the question how the
fireworks work, or I guess more technically, how the fireworks
fire and work? And can you set off fireworks at
work without getting fired? It is a bit of an oxymoron.

(06:44):
It is, isn't it? In one word, you have the firing.
You can fire someone and they can also work exactly fireworks.
It's like we works, but we don't work. Yeah, firecrashed. Yeah,
it's pretty interesting to think about how far works work.
But I think you sort of said earlier that it's
the result of our knowledge at the universe, But really,

(07:05):
sort of fireworks weren't you know? It didn't come from
us understanding anything about the universe, right, I think it
was mostly just people playing around with and maybe figuring
out that some things blew up. You're absolutely right that
fireworks have been with us for a lot longer than
our understanding of the chemistry and the physics of them,
that's for sure. In fact, I think they're invented in China,
like more than a thousand years ago. So firework has

(07:28):
been a part of a human existence for a very
very long time, longer than we've had modern chemistry, that's
for sure. How they were invented, do you think someone
would just falling around with things and then that they
blew up on them, and then the person next to
them was like, oh, that's interesting. I love thinking about
how people stumbled into understanding of how things work. You
think about like think about like the metallurgy of swords.

(07:50):
People have really refined techniques for exactly how to make
very hard steal well before we had any understanding of
the chemistry of it. And I think that must have
just been accidentally disc covered people making mistakes and then discovering,
oh wow, look this is pretty awesome. So yeah, I
think gunpowder probably discovered accidentally. Interesting what we'll get into
what how it works and how it was discovered. But

(08:11):
as you said, the history of it is that it
was invented in China about a thousand years ago. People
are not sure. I guess there are no records of it.
There are some records of it, and you can look
at like Chinese historical drawings and visitors who went to
China of course to see evidence of it for more
than a thousand years. It's pretty cool. Do you think
they were they invented as a like a celebration display

(08:31):
or more for warfare. They were initially invented for celebration,
they think, and then later applied for war. Like everything now,
it's usually the other way around these days, right, the
Internet was started for the military darpened it. Yeah, it
was originally darpen it and then it became you know,
cat videos and podcasts. I see, so you're saying fireworks,

(08:54):
eventually we'll just turn into cat videos. That would be
super impressive. If they can do a cat video with explosives,
engineers could get to it. That is the goal. The
way every life form eventually evolves into a crab, every
form of weapon eventually evolves into a cap video. Well,
and then eventually it came to Europe, but not until
much later. That's right, in the fourteenth century is when

(09:14):
Europe started to use fireworks and developed the same sort
of technology, and then somehow it made it to American
and became part of July fourth our celebrations. Yeah, but
blowing things up have been part of how people celebrate
things for a long long time. Watermelons, fireworks, hopefully not cats,
the beginning of the universe with a big bang. Well,
it's interesting because it's something that's in our everyday lives,

(09:36):
almost or at least once or twice a year. But
I mean, not a lot of people know how it works.
And so as usual, we were wondering what would happen
if you ask people on the street or on the
internet how fire works work. So thanks very much to
everybody out there who answers random questions about the Big Bang,
the origin of the universe, and how fireworks work without
any chance to repair. We really love you participating. And

(09:57):
if you're out there and you've never joined in leaves,
don't be shy right to us. Two questions at Daniel
and Jorge dot com. You want to hear from you,
So think about it for a second. How do you
think fireworks work? Here's but to say, there's some small
amount of gunpowder in a tube that two explodes, creating
a big old pressure wave in a tiny, little enclosed area.
So that exerts a force on something that's gonna get

(10:20):
shot into the air or or I guess whichever way
you point it at a friend or a building or
a car. And if it's one of those big fireworks,
it probably has a second charge in it. You can
put a bunch of different metals in there that are
gonna burn at different colors, and that would be what
makes all the pretty colors in the sky after that
second charge goes off. It's my understanding that you have

(10:43):
a shell that is made up of black powder or
gunpowder or something explosive, surrounded by a little things, little
balls of something that is dipped in as salt, like
a strontium or um, you know, some sort of metal
that when it heats up, it glows in a specific color.

(11:05):
Fireworks show differently because I think they're chemicals within each
display that ones exploded will reflect light differently, and that's
what produces all of the beautiful colors. Fireworks are like
an amazing confluence of chemistry and physics. There's all of

(11:26):
this energy that you have stored in the in the
propellant and the explosive that you're using, and then once
you get it up there, you're using different chemicals to
create all the wild colors and effects. It's early rockets
and payloads of joy. Oh, I'm so excited if you
are talking about fireworks. I love them, and yet I
am not sure how they work. There's something explosive and

(11:50):
different elements create different colors, I think, though I have
no idea how they make those really cool ones with
the different sparkles and sounds that sound like they're crackling.
I love those. I think fireworks work by firing stuff
out in the back of them. Um due to one
of the two lads, which I can't remember. That means

(12:11):
that due to the oppositey action, the firework will go
up and then I guess some dynamite explodes. It makes
it nice color in shape. Well. I always imagine fireworks
as like a tiny, little colorful controlled bomb that exploded
only once you reach the sky. But maybe it works differently.

(12:32):
Fireworks work by oxidizing flammables with a specific chemical that
emits light at a certain frequency, creating the different colors
we see. All right, some pretty technical sounding answers. I
like this one that said the confluence of chemistry and physics.
That sounds almost poetic. Little do they know chemists and
physicist never confluenced exactly. I was like, that's so naive, man,

(12:54):
They're like all the way it went together. They're on
the other side of campus, man, Like they do totally
different physics from us. Chemistry might as well be sociology
from our perspective. Is there a stereotype of like a
chemist and physicist? Like one of them were are sandals?
The other ones? Where where's socks and slippers? I don't know.
Eye protection chemistry always wearing eye protection when I see

(13:15):
them around the building. I see interesting the chemistry, you see.
I have these huge labs of like thirty grad students
pumping a different synthesis of this and that and the
other thing. It's really amazing and impressive. No, I don't
understand most of it. You sound a little jealous there. Well,
you see I chemistry. Don't you have like thirty grads
fouds yourself. I only have eight grad students right now,
thank you. But the u CE chemistry department is top notch.

(13:38):
Somebody who graduated from here won the Nobel Prize in
chemistry last year. I think always an opportunity to plug
u C. I. But yeah, it's pretty interesting. Everyone seems
to have an idea that it's about exploding things, which
sort of makes sense, and it may be a little obvious.
There's an explosion involved in gunpowder. Yeah, but fireworks are
much more than just an explosion. Right. If you've been

(13:59):
to a recent fire work display, you've seen that they
can do incredible stuff. They're sparkly, they're shimmery, they have
different colors, they can make smiley faces. I've seen butterflies,
I've seen palm trees. It's really amazing and what they
can do up there in the sky. Yeah, Well for today,
let's break it down maybe a little bit further, right,
because when we think about fireworks and you know, celebrations

(14:21):
like New Year's or July fourth, there's really sort of
three things that people think about. Right. There's the firecrackers,
the kind of just explode and make noise that they
usually the kind of people throughout in the middle of
the street. There are sparklers, which are the you know
sticks that you hold and they had a lot of sparkles.
And then there's a big fireworks displays that go up
in the sky and give us all these amazing colors. Yeah,

(14:43):
and those things are actually all connected. So that's a
great order to tackle them in. All right, Well we'll
start with the firecrackers, Daniel, How what is the what
are the basics of a fire cracker? Firecracker is really
pretty simple stuff. It's essentially just gunpowder in a little
tube with a fuse, so it's just like a mini bomb, right,
and all it does is rapidly burn the gunpowder, the

(15:04):
black powder, and explode and give you a loud noise
and a little bit of smoke. M M. But I
guess the question is what is gunpowder? Yeah, I've wondered
this for a long time. Actually gunpowder is this weird
mixture of stuff. So it's got some charcoal in it,
like of it is sulfur, and then seventy of it
is this stuff called saltpeter, which I always thought was

(15:26):
really weird, like who is Peter and why is he
so salty? But it's basically just like a funny historical
name for a chemical potassium nitrate. Interesting, maybe salt Peter
is the cousin of Sweet John. I think they're both
blues singers. Sounds like, you know, Mississippi Saltpeter or something. Alright,
So to make gunpowder, you just need charcoal, sulfur and

(15:49):
potassium nitrate. Now what what's potassium nitrate? It's like p
K can end something. Yeah, So the chemical formula is
k N O three. So got potassium, it's got nitrogen,
it's got oxygen, and it occurs in nature as a
mineral and it's a useful source of nitrogen and it's
used in fertilizers and also for like obviously rocket propellants

(16:12):
and fireworks, and they also put some of it in
process meats. Wait what, Oh, that's right, like a curing agent.
And like the reason that like red hot dogs are
red is because the potassium nitrate. Well, does that mean
hot dogs are flammable and they'll explode? I can light
them up? Is that why they're called hot dogs? I

(16:33):
don't know. But the first thing I would do is
take two hot dogs and accelerate them together. See if
that can generate a nice hot dog smash. Yeah, that
sounds like a great use of a billion dollar facility
in Geneva. Maybe for July July four party smash hot
dogs and so and sell them to little kids. Okay,
so that's gunpowder, charcoal, sulfur and potassium nitrate. Now why

(16:54):
does that light up? Why does that explode? Mm? And
so what's happening anytime you have an explosion is just
a rapid release of energy and like one shell of
exploding material and sets off the next one. It's sort
of just like a fire in the sense of like
the way one piece of wood ignites the next piece,
but here it happens very very rapidly, So you have
a rapid emission of energy, usually faster than the speed

(17:16):
of sound. That's what an explosive is. It's usually supersonic.
So that's the basics of an explosion. The details depend
on exactly what you have in there, how rapidly it oxidizes,
how rapidly it releases that energy. Wait, so maybe it
take us through that process then, like what's what's going on?
What is oxidizing? Name what do you need like a
flame to get it started? Right? So fundamental process that's

(17:37):
happening here chemically is something called combustion, right, which technically
is just like high temperature exothermic, which means it's releasing energy.
So you're doing some chemical change to what's going on inside.
You're changing the molecules and their bonds in a way
that releases some stored energy, the same way like when
you burn gasoline, right, it releases energy that used to

(17:57):
be stored inside the fuel. So here it's an exothermic
reaction is called a redox reaction because it reacts with
some oxidant. Often that's atmospheric oxygen. Like fire needs oxygen, right,
it's part of the chemical process to release the energy
that's bound inside the wood. Here, you also need some
source of oxygen, but there's not enough oxygen in the
atmosphere to get this reaction going and to have it

(18:19):
happen so fast. You wanted to start in the center
and then explode outwards. And you know they can't access
enough oxygen to just take that from the air, so
you have to provide a source of oxygen to make
this whole explosion happen. But I guess you know, like
what's the actual reaction, Like why do you need potassium, nitrogen, charcoal, carbon,

(18:41):
and sulfur? Like what's going on? Is something transforming into
something else or something breaking apart? What do you need
those three ingredients? You start with potassium, nitrate and carbon
and sulfur, and then you get out the same bits
but arrange it in a different pattern, So you get
carbon dioxide, you get atmospheric nitrogen, which is into and
then you get put passium sulfide. So you end up

(19:02):
with the same bits but just rearranged in different molecules
in a way that takes less energy. So you've released
some of the energy. WHOA, that's a pretty that sounds
like a pretty complicated reaction. They're like you put in
three things and then three other things come out, but
they're totally different. The fire somehow triggers that. Yeah, it's
actually a complicated multi stage reaction. Doesn't all happen at once,

(19:23):
and it's something people are still sort of studying and
trying to optimize, and they've come up recently with more
fancy versions of gunpowder or like don't release any smoke.
So it's a complicated multi stage reaction. Well, what you
mean multistage, Like the first the potassium nitrate reacts with this,
and then something else, then the charcoal comes in or
what exactly, it's multi steps. You don't have all three

(19:44):
things happening at the same time. First you have the
potassium nitrate, which breaks down and releases the oxygen, and
then that oxygen is crucial for the next stages of
the reaction. But I guess you need something to start
it right, Like you need that spark. And so when
you light up a match, you're burning the stuff in
the match, which is creating temperature I guess heat, right,

(20:04):
then high kinetic energy things that are moving really fast,
and then when you put it close to the gunpowder,
that's amount triggers the reaction. Well, these things are in
a stable state as is, right, Gunpowder just sitting on
the table doesn't give off the energy that's stored in
it the same way gasoline doesn't or wood doesn't. But
if you can trigger this reaction, if you can get
it hot enough to trigger this reaction, you will release

(20:26):
some of its internal energy. So it's sort of like
a ball trapped on a shelf. You gotta give it
a little push so it'll fall off and release all
of that potential energy. And so this is all trapped
stored inside these chemicals. If you provide some heat to
kick it off, then it will release a lot of
that internal stored energy, and that release will then trigger
more release from the adjacent molecules, so it builds on itself.

(20:47):
It's a chain reaction that way, right, And I imagine
it's also you need like a certain amount of heat, right,
Like I'm sure if it's sitting there out there in
the open, there are air molecules hitting it, and some
of them are partly hitting it be fast, and it
is maybe causing some reactions, but maybe not enough to
really get that snowball of rolling exactly, Although you can
have that happen naturally from like lightning strikes. Fires can

(21:09):
start in the woods from lightning strikes. But you're right,
air molecules don't trigger this because they don't deposit enough
energy to get over that hump. It's in a stable state,
which means, like you perturb it a little bit, it's
just gonna go back to hanging out in the molecules
it was in. It needs a big push to get
it out of its little local stable equilibrium and over
the hump, to release a lot of that energy and
fall into a different stable equilibrium of these products of

(21:32):
the chemical reaction. All right, well, those are the basics
of gunpowder. Let's get into how they figure into firecrackers, sparklers,
and fireworks. But first let's take a quick break. Al Right,

(21:55):
we are lighting up the podcast guy, I guess, and
celebrating your life forth here in the US and or
whenever you want to listen to this episode, and we're
talking about fireworks and gunpowder and how that all works
for me. I guess. Physico chemists perspective are re forcing
you to be a chemist in this episode, Daniel, as

(22:16):
much as that can possibly be. You know, my natural
state is thinking about like one fundamental particle maybe interacting
with another one. And one of the reasons I didn't
end up in chemistry is that it's so many particles
to keep track of all at once. It seems to
be like impossible to really ever understand what's going on.
You always have to zoom out and think about things statistically,
which makes me less comfortable. You're like a one thing

(22:37):
at a time kind of guy. Yeah, like drill down
the fundamental nature and look at it, you know. All right, Well,
we talked about gunpowder and how it's a mixture of charcoal, sulfur,
and potassium nitrate, and that's somehow when you put a
flame to it, it starts a chain reaction that transforms
the elements and also I guess releases energy. Now, um,
how is this energy released just kinetic energy or photons

(22:59):
or what's going Well, the energy is released both as heat, right,
because one shell of exploding gunpowder heats up the next
one and sets it off. And but I hate you
mean just like kinetic energy of the particles, right, Like
the molecule breaks apart and the pieces fly off in
different directions, and they're flying off with higher speeds. Exactly.
That's a good rough idea for what temperature is. What

(23:20):
heat is, It's the spedometer of the particles that are
inside it, so you release this energy, meaning that instead
of being bound into some molecule where you have like
springs that are compressed and tightly wound, now you release
those particles and they're flying out. The springs have released
their energy and they're zooming out and hitting other particles,
and that creates a shock wave, right, because you're hitting

(23:41):
other particles which then hit other particles. And that's what
sound is. Sound is a traveling compression wave. And so
as this explodes, it creates pressure in the air and
that pressure hits your ear and you hear it. So
the reason the firecracker sounds like a boom is because
it's a little bomb. It's created this pressure wave which
travels out and hits your ear, all right, So that's

(24:03):
the band that we hear when when a fire cracker
goes off. But what about the flash, Like where does
that light come from? That's again just from the energy
that's released. Some of it gets converted into sounds, some
of it gets converted into heat, and some of it
is released as photons, right, And so just like when
you're looking at a fire, it's releasing heat, but it's
also releasing visible light. You're gonna see some of that
with your eyes. Remember, anything that gets hot is going

(24:25):
to release photons. It's impossible to warm up without glowing.
Everything in physics we can think of as a black
body radiator, meaning that the temperature you are determines the
frequency in which you glow. So things that get hot
enough are going to glow in the visible light. Right.
I think we covered this in a previous episode. Like
when things are hot, the molecules are moving really fast,

(24:46):
and somehow that causes the electrons to drop down levels, right,
and then that's what releases the photons. The universe doesn't
like to have high energy density, likes to spread that
energy out. So if a bunch of molecules with energy,
either because there's a tron's have energy, or because the
molecules themselves a high kinetic energy, or maybe they have
vibrational energy in their bonds, that likes to spread out.

(25:08):
So anything that's excited will release that energy in terms
of photons, and that's how things are basically glowing. I
see when things are excited, they release photons, and an
explosion things are super exciting, the way kids get excited
in holidays and their faces glow. All right, Well, um,
I guess one question I had was how does gunpowder

(25:29):
relate to bad poop? Because I remember thinking or hearing
about how, you know, originally or maybe to make fireworks
or gunpower, you just need like um, bad poop, guana
or maybe seagull poop. I think I've heard that too.
It requires people used to mind guano because guano has
exceptionally high amounts of nitrogen, phosphate and potassium, and so

(25:51):
you need that potassium and that nitrogen to make gunpowder.
So I mean, gunpowder is not like something you find underground.
You don't like mind gunpowder that you mind, you know, salt,
for example, You have to put it together the chemical
mixture of other various elements. You need to find those
ingredients to manufacture gunpowder. The bats basically have concentrated a
lot of these things for you and delivered it to

(26:12):
you in the form of poop. That's super interesting, right,
isn't it Like it's a biological process that actually kind
of makes gunpowder, right, meaning like the poop is kind
of explosive. Well, they're essential ingredients in gunpowder. It's not
like they have really you know, explosive farts or something
like that. Well, you don't know the bats that I do,

(26:32):
but yeah, these are essential ingredients, and you know, we
rely on biological processes all the time to capture energy
to produce chemicals that we find important. You know, basically
everybody on the planet is eating the results of biological
processes that have stripped out energy from the sun and
taking carbon dioxide and do this essential chemical processing for us.
So yeah, we're all building on top of this huge

(26:54):
pyramid of photosynthesis and bath poop production. Yeah, it's interesting. Yeah, us,
when you eat a solid, you're kind of ingesting you know,
prepacked energy packets, right, prepacked by another biological being. Yeah, exactly,
it's this like pyramid of energy processing and chemical conservation
to take that energy and stored it in a useful way.
And it's much more economically feasible and easier to just

(27:17):
gather this from biological processes than to synthesize this in
the laboratory in a pure way. That could be done,
but then you have to do the bat's job for them. Yeah, no, thanks,
I wouldn't want to be, you know, poop for a living.
I guess. I think bats eat a lot of fruit, right,
so that doesn't sound too bad. There you go. I
guess I wouldn't want to, you know, go to that

(27:38):
fireworks display featuring fireworks made only from a cartoonist poop.
No bats or cartoonists were hurt in the making of
this fire But anyways, one thing that's interesting here that
you wrote down is that gunpowder and firecrackers and fireworks
in general are slow explosives. What is I mean? So

(28:00):
the speed at which the explosion happens determines a lot
about how useful it is and what it can be
used for. T and T and other related chemicals. Those
are actually more explosive, and so the speed at which
this thing blows up determines whether you're getting like a
big shock wave or a bang. And it's interesting that
black powder is better for fireworks because it blows up

(28:21):
more slowly than dynamite. Yeah, by a lot, right, Yeah,
black powder blows up at like a hundred yards per second,
that's the detonation velocity, and dynamite has a velocity of
detonation more than a thousand yards per second, so ten
times as strong. Yeah. It's super interesting because you know,
I think to us as humans that are limited kind
of capacity to these to see things and perceive things.

(28:45):
You know, to us, they're both just explosions. But I
guess if you had like a super duper fast camera,
you would see the difference between a T and T
explosion and a fireworks explosion, right, Like, one of them
would be ten times lower. So does that mean that
then firecracker explosions are less dangerous, but they'll still blow
up your fingers, or if you put enough of them,
they'll still blow up a tank for example. Right, Yeah,

(29:06):
they're both explosives, and you definitely don't want to mess
around with either of them. They're both definitely dangerous, but
they produce a different sort of character of explosion. So
you get like a longer duration of the explosion, and
I think you get a different mixture of light and
sound because the explosion is slower, so I think there's
more time for the stuff to heat up. And I
guess if it's faster too, it's also more destructive, right, Like,

(29:26):
you're concentrating more energy in a smaller place, which is
probably better for you know, destroying things. Yeah, when you
want to crack open a rock, then you want to
convert most of the energy into high pressure waves, whereas
with the firework. You don't want to produce as much
pressure because you don't want to pop people's ear drums.
So you want more the energy to produce bright flashes
of light, which requires heating this stuff up. So you

(29:47):
actually want to lower explosion velocity so that the stuff
actually gets hotter. Interesting. And so that's what a gunpowder is,
and that's what a firecracker is. You just take a
bunch of gunpowder, put in a little package and I
guess how attach a fuse twit, right, which is really
just a string, and so when you light up the string,
the fire kind of travels along the string and then
eventually it hits the gunpowder. And one nice thing about

(30:10):
black powder and gunpowder is that it's sort of insensitive
to friction. Like if you have a pile of it
and it rubs against itself, it doesn't just set itself off,
which is good. You wanted to only blow when you
want it to blow. And so what that's what the
fuse does, is it delivers that first spark of energy
to get the reaction going. Right. Oh, I see, well,
by friction, I think you mean like dropping it, Like

(30:30):
you don't want to drop a firecracker and have it explode.
But like I think, if you drop a stick of TNT,
it could blow up. Right, Yeah, TNT is much less stable.
Gunpowder if it rubs against itself, won't blow up. That.
You can blow up gunpowder without a spark, right, you
can just use percussion. That's how a gun works, right
black powder. Gunpowder is in the back of the bullet,
and then the hammer comes back and hits the back

(30:51):
of the bullet and that actually sets off the gunpowder.
So you can set off gunpowder without a spark. Oh interesting, Well,
I think these days and bullets they a little like
the back of the bullet has something that causes a spark.
But I think maybe you're thinking like way before when
they would use like they would literally pour gunpowder into
the gun. Then just hitting it, hitting gunpowder makes it ignite. Yea,

(31:12):
Some fire and guns just have a hammer, right, there's
no spark. You know a lot of those guns huge
range of technologies though. All right, well, those are firecrackers
that kind of go pop up up, um. But now
let's talk about sparklers. I think these are my favorite
from when I was a kid. I'm still a fan
of sparklers. Sparklers are super fun because you can hold
them right. It makes them feel much more immediate. Like

(31:32):
a firecracker, you said it in your run, it goes bang.
But a sparkler you can hold it. You could wave
it around and you can like draw in the air
with a light because the impression stays and your retina
for a while and also lasts for a while. You know,
you can burn for like thirty seconds or a minute.
So this are definitely one of my favorite childhood memories. Also, yeah,
they're pretty cool. And if you're not familiar, I guess
they're like a stick. There's usually like a metal stick

(31:54):
and the top half of it is covered in some
sort of gray stuff that makes it sort of look
like a corn dog. I guess, right, like a great
long corn dog. Although you don't know what a sparkler
looks like, you probably don't know what a corn dog
looks like either. It looks really gross. It does not
look like a corn dog. It's like totally gray and metallic.
It's completely unappetizing. Oh boy, did I just salt corn dogs?

(32:19):
Are you're a big fan of corn dots? It doesn't
matter how much mustard you put on that thing, it's
not gonna taste good, it's gonna it's gonna sparkle though
in your mouth. So the way these works is, um,
you take a sparkler and then you light up one end,
but it takes it. Sometimes it takes a while to
light up, right, Like, it's not like you put the
flame to it and it immediately starts sparkling. You kind
of have to wait a little bit. It's not like

(32:39):
a fuse that immediately goes. You've got to get it
like hot enough to really start. And a sparkler is
sort of like a slow motion firecracker. Like it's got
the same basic material inside of it. Again, it's black
powder doing a lot of the work releasing energy. That's
like the fuel that powers the sparkler. But then it's
got stuff inside of it which sparkles, and all of

(33:00):
the stuff that slows down the reaction so it doesn't
just like blow your hand off, right, it's sort of
diluted in a way, right, Like that's the idea to
slow down you do you mix it with other things
that don't explode exactly. You modify this mixture of like
potassium nitrate and sulfur and charcoal so that you get
a slower explosion. Sometimes adding more sulfur or more charcoal

(33:20):
reduces how fast the oxygen is released, and so you
can tinker with those mixtures to get a different speed
of the reaction essentially. And then for the sparkler, you
actually mix it with sugar, right like their sugar on
that thing. There is sugar in there. That's mostly just
to hold it together, to make it like a goop
and not just like a powder. But the reason that
it's sparkles is sort of weird. They have metal powder

(33:42):
in there, like you put aluminum or steel or something
in there, and then that steel gets really really hot
and it glows for the same reason we talked about earlier.
You take metal, you heat it up, it's gonna glow.
And so here you have metal powder which gets heated up,
and that's what's actually making those little sparkle that shoot out.
Oh interesting, that's the as the metal that heats it. Well,

(34:04):
if there's a central flame in the middle, right, and
then that's the big bright thought that you see in
a sparkler. But then there's other things shooting off of it,
these sparkles basically, and you're saying the sparkles are metal
that's getting super heat up by this central kind of flame.
It's basically tiny bullets, and a sparkler is shooting super

(34:27):
tiny little pellets of hot metal. It sounds like a
terrible idea, right now, give this to kids and let
them run around. But these things are so small they
burn up quickly and basically vaporize. But if you do
put your hand really close to a sparkler, you will
feel these tiny little hot pellets hitting your hand. It's
not a great idea. Well, what's interesting is sometimes it
sort of looks like almost like a snowflake pattern, right,

(34:48):
like do You'll see a big stream of sparkle and
then that will divide, and then those will then divide
in itself, making sort of like this beautiful tree like
almost snowflake like pattern. It's sort of like dolls, right.
They keep breaking down into smaller and smaller pieces, and
that's those little bits of metal getting heated up, and
if they're big enough, they will split in half before
they completely vaporize, and then maybe split it half again.

(35:10):
So you get these really cool patterns and their ephemeral. Right,
they don't last very long. It all happens very very quickly,
but long enough for the pattern to remain in your eye.
So it's really a beautiful effect. And I guess why
does it need to be metal that heats up like
white as metal give off light when it gets heat
up more than other things like carbon. That's a good question.
I think you use metal because it doesn't burn, right,

(35:33):
It just heats up and vaporizes, so like absorbs the
energy and then gives it off as light rather than
like contributing to the explosion itself. So it's fairly inert
that way. Chemically, it's not getting modified, it's just getting
heated up and vaporized, all right. Well, and and so
you heard it from Daniel, sparkers have sugar in them,
so um, don't give him a dry too close to

(35:58):
one of your little child. We just give the bad
advice here today. Then. But they are super fun and
they are super cool, and so the next time you
look at one, you know, think about all the processes
that are going on in there. Right. Let's get into
now how far works, the big ones, the ones that
light up the sky and have all these amazing displays
and colors. How they work. We'll dive into that, but

(36:19):
first let's take another quick break. Al Right, we are
celebrating I guess July fourth, Dannel. This episode will come
out around July four. Yeah, and all the summer holidays,

(36:42):
you know, in France, this bestial day, and it feels
like a lot of cultures have a reason to set
off fireworks in the summer, right right, Who doesn't love
a good explosion? The particle physicist us, well, all right,
I won't get into it anymore and explode, Daniel, I'm
just trolling. You. Make sure to call it the big

(37:05):
smash and put the big bank, since it all means
the same to you anyways, Let's be more confusing. Sounds good,
let's do how about the small the small smash that
needs to be extra extra confusing, the micro smash that
started it all, the small smash, formerly known as the
big bang. That's what we need to change the name

(37:27):
of something everybody already knows the name of now, so
that some people can say, actually, it's now called Are
you Are you mocking chemists or physicists with that, boy? Physicists.
I would never mock chemists, because they're better at making
poison gas and bombs than I am. I see, you

(37:47):
don't want to lose that chemistry with them. But all right,
so now let's get into now fireworks. Now, this is
the question we started off at the beginning. So these
are the ones that most people think of, you know,
July four or Steel Day. They throw these up in
this They light up the sky. There's all kinds of
colors nowadays there's all kinds of shapes too. Yeah, they're
very dramatic. And fireworks are basically a combination of everything

(38:08):
we've talked about so far. Their combination of sparklers and
firecrackers and then all wrapped together in a little mini rocket.
One of the essential components in fireworks are these things
called stars, which again are not the burning balls of
plasma and the sky. There's something totally different. They're like
sparkler like stuff formed into little balls. Oh interesting, you're

(38:29):
saying a firework. It's like a bunch of sparklers stuffed
in with an explosion. Exactly when you see the fireworks
in the sky and you see it's sparkling, it's a
sparkler up there. And so the way you make a
firework is that you pack a bunch of little balls
of sparkler together into a little tube. And then you
also fill it with black powder, which sprays all the
sparklers out when it explodes, and that's what makes your

(38:51):
pattern in the sky. Oh interesting, really, so I guess.
I mean, I'm not saying you should do this, but
you could do this. Like if you put a bunch
of sparklers in with a firecracker, you can make your
own firework kind of. That's what a firework is exactly.
It's just sparkler stuff packed in with black powder that
was high precision in order to get it to explode
in just the right way and at the right time,

(39:12):
and then you also have to somehow launch it up
into the air. So it's a bit of a complicated construction,
but those are the essential ingredients, black powder and sparkler stuff.
I see. Well, let's break it down. How does the
rocket launching part work. Is it like a rocket rocket? No,
it's more like a gun. You have like a steel
tube with black powder in the bottom, and then the

(39:32):
firework is sitting on top of that. So you light
some black powder in the bottom of the tube and
that explosion like a firecracker inside of it sets off
the firecracker to fly up into the sky and at
the same time lights the fuse at the bottom of it.
So that's how you launched the thing up. It's just
like a little gun. But it's not like a gun. Like,
it's not an explosion that propels it upward. Right, It's

(39:54):
more like a controlled you know, like a real rocket right. Like.
It's not like a big bang. It's like a right
like it has to expel the propellant slowly kind of. Well, though,
the explosion happens at the bottom of the tube. It's
like our mortar, right, and that explosion pushes the firework up.
It's not like the firework is burning on its way
up and pushing itself up. It's more like it's gotten

(40:15):
thrown up. It's not a projectile motion, just from the
initial explosion that pushed it out of the tube. A
rocket is like continuous burning that's pushing it up, has thrust,
but a firework doesn't. It's just like thrown up by
this too, more like a mortar. Well, maybe that's some
of them, right, I think some of them. How do
you sort of a rocket like a thing? Yeah, you
can definitely buy some fireworks that you can light off

(40:37):
yourself that are like bottle rockets, right, that are propelled
by those the kind of I'm thinking about, you know,
the big ones you see at the displays, those are
almost all just projectiles that are fired up by an
initial explosion. But yeah, there are some versions that are
like more like rockets that have a continuous explosion. M
I see, Well, I guess it's it's gonna be tricky
because you want to explode something a rocket something at

(41:00):
the bottom, but you don't want it to somehow, you know,
burn up your gunpowder and sparklers that are at the
front exactly, So they pack it very carefully, and they
have like multiple stages, and they have fuses that have
time delays, so they have materials that burn at very
well known rates. So you light this fuse and you
have like four seconds before it gets to the top

(41:20):
of the firework and sets off the rest of it.
So you're right, it's a very delicately balanced system. Yeah,
and it's interesting what you said. You got a time
it right, because you want the fireworks to explode and
give you all the sparkles like at the very top,
not as it's going up or right as soon as
it takes off. Yeah, and some of these things have
like two or three different stages, so they'll blow up
once and then they blow up again at the top,

(41:41):
and then on the way down they blow up one
more time. So people have gotten really advanced with the
technology for how to put these things together to make
the most spectacular displays in the sky. But it's all
about how you package this stuff so the explosions happen
at the right time. Right. They can even make things
like a smiley face. Right, they can make a firework
that blows up into a smiley face. Yeah, you can.
You can make all sorts of crazy shapes. And the

(42:02):
way they do this is by very carefully arranging those stars,
these pieces of sparkler inside that tube and arranging the
black powder around them in just the right way, so
when it blows up from the center, it ends up
shooting those things out in just that right pattern, because
when that black powder goes off, it then sets off
the sparklers, which then glow. But it must take a

(42:23):
lot of experimentation exactly how to arrange those stars inside
the firework to give you that reaction. I imagine they
must fail a lot that or they've done some really
complicated computer simulations to figure out exactly how to build
these things interesting? What do you think it is? Well,
I think these things have been around for a lot
longer than fancy computers, so initially it must have just
been trial and error. You know, people like have an

(42:45):
artistic skill at this, you know, coming up with clever
things that you can do with your limited ability to
arrange the stars inside the fireworks, and then people being
creative and discovering new stuff these days. I bet they
could use computers, but I'm not sure if anybody's doing that. Yeah,
I guess you. You know, to get a circle, for example,
for a smile of phase, you just kind of arranged
the sparklers a circle around your explosion, right, your explosive,

(43:08):
and then when they blows up, it will come out
in the circle. And if what you want is a heart,
then you move some of those a little bit further
away and some of those a little closer in so
they burn up sooner. And some of these things are
not like a circle or a heart, they're like a
big flower, like a chrysanthemum, right, and from that you
just have like stars everywhere, all right, So then how
do they how do the colors work? How do you
get different colors of sparklers, So the colors come from

(43:32):
the different kinds of metal inside the sparkler. Remember the
reason the sparkler sparkle is because you have metal powder.
That metal gets really hot and then it glows. But
these metals are made of different elements, so they tend
to glow at different frequencies because these metals have different
energy levels that they like to release photons at. So
different kinds of metals will glow in different colors. And

(43:53):
you know, for example, if you sprinkle copper powder into
a flame, the flame turns green, and so different metals
give you different colors. Where does that come from? I guess?
I guess because when it's when the photon comes out
of the metal, that comes with a specific frequency which
is related to its energy. Just like if you look
at a star, you can tell what it's made out

(44:13):
of based on the frequency of light that's coming to
you from the star. And that's because different elements glow
with different fingerprints, and that comes from the energy levels
of the electrons going around the atom and also in
more complicated situations, from rotational or vibrational modes of a molecule.
But usually it's just from the energy levels of the atom,
and those are all different for different elements, and so

(44:35):
you get different mixtures of colors for different elements. So,
for example, if I wanted an orange fire work, what
would I use? Then you'd use calcium. Calcium. Oh, that's
a metal, right, And these things don't have to be metals, right,
They just have to be elements that can accept heat
and not participate in the reaction. What about like red red?

(44:55):
You can either use lithium, which is going to give
you like a medium red or strawn ty them for
like a really intense red col What what are some
other colors? So you can get like yellow from sodium
or green from barium. Copper actually gives you more of
a blue than a green. You can get violet from
potassium or rubidium. You can even get gold colors from

(45:16):
charcoal or iron. Things like aluminum or titanium tend to
give you white. So you have a whole palette to
play with if you're the person designing these fireworks. Interesting,
it's almost like you're painting with materials, right, And a
lot of these things are made sort of by hand,
like they are these fireworks masters that pack these things
together and very carefully mix the ingredients to get exactly

(45:39):
what they want, you know, magnesium or aluminum or whatever.
And so they tend to make these things sort of
by hand and cut them into these pieces. And that's
why some of these things are very expensive because they're
like fabricated by artisans whoa it's like organic, you know,
artisan works. Somebody with like a wax mustache and a
long beard and make this out in Brooklyn warehouse. Right now,

(46:01):
you're you're assuming they're hipsters for a word, hipsters, But
I wonder if that's a stressful job, you know, dealing
with explosives because you're you're sort of crafting this thing
by hand of something that can explode at any moment.
I'm sure they have good insurance. I don't know if
having good insurance, but it made me want to do
something dangerous. It's almost the opposite. If you need good

(46:24):
insurance or something, maybe you should be doing it. Maybe not.
But you know how it is, everybody gets inspired by
something different, and for some folks this must be like
a deep passion. You know. The mixture of chemistry and
artistry together probably really satisfying for a lot of folks.
And then you get to display your works. Everybody goes, oh, right,
almost everybody loves fireworks, so you must be very popular.

(46:45):
That's right, almost everybody except you, I guess. But what
about the ones that you know? Sometimes you see these
like they explode and then the little bits explode themselves,
you know, like like a multi tier explosion almost like
it explodes and it gets us sparkles, but then the
sparkles after a little bit, explode themselves into other colors.
How do they do that? Yeah, that's all in the packaging.

(47:06):
You can make like little cardboard packages that have sparklers
inside them, and they're surrounded by sparklers, and so initially
the outside sparklers go and then when those burn after
a while, they heat up what's inside, which can then burn.
So it's all about timing these multi stage reactions. You
do that based on how you're packaging this firework right, right,
And something interesting you just said is that these things
are made out of cardboard, right, Like you kind of

(47:28):
have to make him out of materials that burn up, right, Like,
you can't make a firework out of put like a
steel to or a steel plate on it, because that
thing's gonna fall back down and maybe hurt somebody. Everything
has to be made out of paper, and it has
to be the right strength to hold the stuff together,
but not so strong that it can't explode. Right, And
so cardboard and paper is actually just about the perfect strength. Wow,

(47:48):
so you need to be like a paper artisan too. Yeah.
I don't think we're like three D printing fireworks or anything,
but not yet. You just am up with an interesting
idea there. I wonder if you can get more precise
sculptures if you if you do three D print them. Yeah,
you might be able to guide the sparklers in exactly
the right direction. You could have like tubes or sparkler

(48:10):
guides or something that they get them to do crazy stuff.
I think three D printing and computer modeling probably the
future of artisanal fireworks. Wow. Yeah, you could have like
a firework that explodes into a photo of your face
or something. Yeah, or the cat video that everybody's been
wanting and waiting for. Oh my gosh, that would be
next level, like animated fireworks. Can you imagine like fireworks

(48:33):
and move? Yeah, that would be pretty incredible. It sounds
like something out of Harry Potter. Maybe. Yeah, four D fireworks, Well,
nowadays it kind of seems like the future of these
displays that are drones. They're using drones more and more
and they're almost kind of as and you can't do
cat videos with drones. Yeah, you actually can, and they're
not explosive and they don't release toxic chemicals into the
air and nobody gets blown up. So drones are pretty

(48:55):
nice alternative, or like the green alternative to artisanal organic
fire works. They got out greened. And I love a
fireworks display like anybody else. The thing that I wonder
sometimes when I watch fireworks displace is all those people
taking videos of fireworkers place. What was wondering, like, what
percentage of those videos is anybody ever watching? You can

(49:16):
ask about any video ever taken. Then you'll you take
a video of your kid eating a pizza slice. You
know you're not gonna watching that later, but you want
to capture the moment. I do go back and watch
silly videos of everyday moments of my kids back when
they were really young, and I think, oh, that's nice
to get transported back to that day. You remember what
they were like. But I don't watch fireworks videos, you know,

(49:39):
with nobody in them, and go, oh, yeah, I remember
that explosion. That was really cool. M Well that's because
your firework scrub, Daniel. Nobody would explain you to you
watch something it's something you don't like. Fac More people
would probably say oh to that video than to your
kids eating pizza. Honestly, if I invited people over there,
probably rather see a fireworks video than an old video

(50:01):
of my kids eating pizza. Especially your kids didn't want
to see that stuff. All right, Well, that was an
explosive conversation, full of sparkling conversation. Yeah, and we hope
that illuminated for you how people have been using physics
and chemistry to brighten up their lives and their celebrations
even before they understood how it worked. And I hope
that confluence of physics and chemistry I really add a

(50:22):
little pop to your day there for night. And I
hope my distaste for fireworks it doesn't blow up your experience.
What's not to like, Daniel? They're big, they're explosive, and
they're bright, sort of like the universe, right, the big smash?
All right, I give up, you win? Yes? All right? Well,
we hope you enjoyed that. Thanks for joining us, and
we hope the next time you look up at the

(50:44):
fireworks display, you kind of think about all of the
physics and chemistry arts that's going on than all the
artisanal skill that went into making those fireworks. And have
a happy summer fireworks season everybody, and stay safe. Take
a video and send it to Daniel Ramp to enjoy it.
I'll d them all together and put them on my
website for somebody to download and watch. Twelve hours of fireworks.

(51:05):
That does sound pretty good. I think it's called the screensaver.
Maybe I think they invented that already. Anyways, thanks for
joining us, see you next time. Thanks for listening, and
remember that Daniel and Jorge Explain the Universe is a
production of I Heart Radio. For more podcast for my

(51:28):
Heart Radio, visit the i heart Radio app, Apple Podcasts,
or wherever you listen to your favorite shows. Ye