Daniel and Jorge Explain the UniverseDaniel and Jorge blow your mind with the physics and chemistry of how fireworks sparkle and entertain.
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Hey, Daniel, I have an explosive question for you.
Uh 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 every day basis. How do you feel about summer fireworks?
M I used to love fireworks as a kid.
You used to love them. You don't like them anymore.
I guess I just used to have a more sparkling personality.
Well, you can be a real firecracker, trust me.
Well, I'm hoping one day that all blows over.
Yeah, very bright and popping's personality. Also, you seem to make a lot of noise.
So far, I've never been fired from work for setting off fireworks.
I am Hooreham, a cartoonist and the creator of PhD comics.
Hi, I'm Daniel. I'm a particle physicist and a professor at UC 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? 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 little that can love to blow things up with far correctly.
And how'd that work out for your cousin?
All right, he's still alive, 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 it doesn't blow things open.
His job is the opposite now of his childhood passion.
That's right, keep things are blowing up, please Gus. But anyways, welcome to our podcast, Daniel and Jorge Explain the Universe, a production of Iurheart 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 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 accelerate and expand faster and faster each day. Literally, it is sort of exploding, and it's also full of sparkly, 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. Though these days our vision of the early universe isn't as much like a firecracker as it is like a big rubber sheet getting stretched everywhere.
Maybe you shouldn't have called it the Big Bang. I mean it's in the name Da Hill. The Big Bang sounds like an explosion.
It does, indeed sound like an explosion, and so we'll added 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 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. But does that is 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 like put it on the table and tease it apart with plyers. What you got to 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 a mini explosion, and we do millions of them per.
Second, although it's more like a smashing. I don't know if it's exploding.
Really, Well, what happens if you smash two watermelons together? They explode, don't they.
They just smash. If you put a grenade inside of a watermelon, that's an explosion.
Well, if I could put a grenade inside of proton. I would totally do it, But what would.
The grenade be made out of?
Danium? Grenadons obviously a delicious dessert. Explosions, but I'm also a 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 do you do? 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 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.
Mm hmm. And as we come up on July fourth, it reminds me that the best fireworks display I ever saw for July fourth, for American Independence Day was actually in Switzerland.
Oh yeah, they make everything better out there, more precise.
There's a 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 live orchestra which plays music and coordination with the fireworks. It really was pretty impressive.
Well, so you do like fireworks then.
Yeah, occasionally I've been known to enjoy them.
Yeah, occasionally. I mean, who doesn't like fireworks, Daniel? Maybe dogs? Dogs and physicists, dogs and jaded physicists.
Dan. 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 I you said you got the big name for the origin of the universe. Wrong, Maybe you should be.
A little more careful yep, point taking.
But anyways, fireworks are pretty amazing and incredible and part 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 to know some physics and some chemistry.
Yeah, so today on the program we'll be tackling the question how do fireworks work, or I guess more technically, how the fire works fire and work?
And can you set off fireworks at work without getting fired?
It is a bit of an oxymorn, isn't it. In one word, you have firing, you can fire someone and they can also work exactly fire works.
It's like we works, but we don't work.
Yeah, fire crashed. Yeah, it's pretty interesting to think about how fireworks work. But I think you sort of said earlier that it's the result of our knowledge of the universe, But really 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 blow up.
You're absolutely right that fireworks have been with us for a lot longer than like 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 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 foolling around with things and then that 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, like, think about like the metallurgy of swords. 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 discovered people making mistakes and then discovering, oh wow, look this is pretty awesome. So yeah, I think gunpowder probably discovered accidentally.
Interesting. Well, we'll get into how it works and how it was discovered, but 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 or more for warfare.
They were initially invented for celebration, they think, and then later applied for war like everything.
No, it's usually the other way around these days.
Right.
The Internet was started for the military darpnet. Yeah, it was originally darpnet, and then it became you know, cat videos and podcasts.
I see. So you're saying fireworks eventually would just turn into cat videos.
That would be super impressive. If they can do a cat video with explosives.
Engineers can 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 cat video.
Well, and then eventually it came to Europe, but not till much later.
That's right. In the fourteenth century is when Europe started to use fireworks and developed the same sort of technology.
And then somehow it made it to America and it became part ofly 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 almost least once or twice a year, but a bit 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 fireworks 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 prepare. We really love you participating. And if you're out there and you've never joined in, please don't be shy right to us two questions at Danielandjorge dot com. We want to hear from you, So.
Think about it for a second. How do you think fireworks work? Here's a people had 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 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 a shell that is made up of black powder or gunpowder or something explosive, surrounded by little things, little balls of something that is dipped in a salt, like a strontium or you know, some sort of metal that when it heats up, it glows in a specific color.
Fireworks show differently because I think there are chemicals within each display that, once 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 this energy that you have stored 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. In effect, 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 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 at the back of them, and due to one of Neuter's laws, which I can't remember, that means that due to the opposite reaction, the firework will go up and then I guess some dynamite explodes and makes a 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 works differently.
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 physicists never confluence exactly.
I was like, that's so naive, man, They're like all the way in fluence 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 chemists and physicists. Like one of them will were sandals, the other ones were were's socks and slippers.
I don't know eye protection. Chemistr are always wearing eye protection when I see them around the building. I see interesting the chemistry, you see, I have these huge labs of like thirty grad students pumping out different synthesis of this and that and the other thing. It's really amazing and impressive, though I don't understand most of it.
You sound little jealous there, Well, the chemistry do you have like thirty grad students yourself?
I only have eight grad students right now, thank you. But the uichemistry department is top notch. Somebody who graduated from here won the Nobel Prize in chemistry last year.
I think always an opportunity to plug you, ciz. But yeah, it's pretty interesting. Everyone seems to have an idea that it's about exploding things, which sort of makes sense and maybe a little obvious. There's an explosion involved and gunpowder.
Yeah, but fireworks are much more than just an explosion. Right. If you've been to a recent fireworks 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 like New Year's or July fourth, there's really sort of three things that people think about.
Right.
There is the firecrackers that kind of just explode and make noise that 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 to pr out a lot of sparkles. And then there is a big fireworks display that go up in the sky and give us all these amazing colors.
Yeah, and those things are actually all connected. So that's a great order to tackle them in.
Right. Well, we'll start with the firecrackers, Daniel, How what is that? 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 black powder, and explode and give you a loud noise and a little bit of smoke.
Now, 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 fifteen percent, ten percent of it is sulfur, and then seventy five percent of it is this stuff called saltpeter, which I always thought was 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.
All Right, So to make gunpowder, you just need charcoal, sulfur, and potassium nitrate. Now, what's potassium nitrate? It's like p K can N something.
Yeah, So the chemical formula is k no three. So it's 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 and fireworks, and they also put some of it in processed meats.
Wait what, Oh, that's right, let's get 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 will explode if you light them up? Is that why they're called hot dogs?
I don't know. But the first thing I would do is take two hot dogs and accelerate them together. See if that can general a nice hot dog smash.
Yeah, that sounds like a great use of a billion dollar facility in Geneva. Maybe for July fourth parties smash hot dogs and sell them too little kids. Okay, so that's gunpowder, charcoal, sulfur, and potassium nit rate. Now why does that light up? Why does that explode?
Mm hm? And so what's happening anytime you have an explosion is just a rapid release of energy, and like one shell of exploding material then 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 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 take us through that process then, like what's what's going on? What does oxidizing mean? What do you need like a flame to get it started?
Right? So fundamental process. What's 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 be stored inside the fuel. So here it's an exothermic reaction, and it's 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 because there's not enough oxygen in the atmosphere to get this reaction going and to have it happen so fast. You want it 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, and sulfur? Like what's going on? Is something transforming into something else or something breaking apart? Why 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 end two, and then you get potassium sulfide. So you end up 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 that sounds like a pretty complicated reaction there, Like you put in three things and then three other things come out, but they're totally different. The fire somehow trigger set.
Yeah, it's actually a complicated multi stage reaction. Doesn't all happen at once, 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 that like don't release any smoke. So it's a complicated multi stage reaction.
Well, what do you mean multi stage? Like the first the potassium nitrate reacts with this, and then something else and then the charcoal comes in or what exactly.
It's multi steps. You don't have all three things happening at the same time. First you have the potassium nitrate, which it breaks down and releases the oxygen, and then that oxygen's 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, then high kinetic energy things that are moving really fast. And then when you put it close to the gunpowder that somehow 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, it will release some of its internal energy. So it's sort of like a ball trapped on a shelf. You got to 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, and 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. 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 pretty fast and it is maybe causing some reactions, but maybe not enough to really get that snowball.
Rolling exactly, although you can have that happen naturally from like lightning strikes. Fires can 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 going to 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 the chemical reaction.
All right, well, those are the basics of gunpowder. Let's get into how they figure into fire crackers, sparklers, and fireworks. But first let's take a quick break. All right, we are lighting up the podcast guy I guess, and celebrating July fourth here in the US and or whenever you want 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 we forcing you to be a chemist in this episode, Daniel?
As much as I 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 one thing at a time kind of guy.
Yeah, like drill down to the fundamental nature and look at it, you know.
All right, Well we talked about gunpowder. 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, how is this energy released just kinetic energy or photons or what's going on?
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 by heat you mean just like kinetic energy of the particles. Right, Like a mole, like it 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 heat is. It's the sphadometer 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 other particles which then hit other particles. And that's what sound is. Sound is a traveling compression wave. So as this explodes, it creates pressure in the air, and that pressure hits your ear and you hear it. So the reason a fire cracker sounds like a boom is because it's a little bomb. It's created this little pressure wave which travels out and hits your.
Ear, all right, So that's the band that we hear when a firecracker goes off. And 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 sound, 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 going to see some of that with your eyes. Remember, anything that gets hot is going to release photons. It's impossible to warm up without glowing. Everything in physics we 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, 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 those electrons have energy, or because the molecules themselves have high kinetic energy, or maybe they have vibrational energy in their bonds, that likes to spread out. 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, I guess one question I had was how does gunpowder relate to batpoop? Because I remember thinking or hearing about how, you know, originally or maybe to make fireworks or gunpower, you just need like bat poop, guano or maybe seagull poop. I think I've heard that too. It requires poop.
People used to mine guano because guano has exceptionally high amounts of nitrogen, phosphate and potassium, and so 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 mine gunpowder the way you mind. You know, salt, for example, You have to put it together. It's a 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 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, I meaning like their poop is kind of explosive.
Well, they're essential ingredients in gunpowder. It's not like they have really you know, explosive arts or something like that.
Well, you don't know the bats that I do, 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 taken carbon dioxide and do this essential chemical processing for us. So, yeah, we're all building on top of this huge pyramid of photosynthesis and bapoop production.
Yeah, that's interesting. Yeah, I guess when you eat a solid, you're kind of ingesting you know, pre packed 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 store it in a useful way. And it's much more economically feasible and easier to just 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.
Oh, there you go, I guess I wouldn you know, go to that fireworks display featuring fireworks made only from a cartoonist poop.
No bats or cartoonists were hurt in the making of this.
Fires 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 does that mean?
So the speed at which the explosion happens determines a lot about how useful it is and what it can be used for. HE 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 more slowly than dynamite.
Yeah by a lot, right, Yeah, black.
Powder blows up at like one 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 with our limited kind of capacity to see things and perceive things, 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 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, 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, you're concentrating more energy in a smaller place, which is probably better for you know, destroying things.
Yeah, when you want to like crack open a rock, then you want to convert most of the energy into high pressure waves, whereas with a 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 of the energy to produce bright flashes of light, which requires heating this stuff up. So you actually want a 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 it in a little package, and I guess have an attach of fuse to it, 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 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 want it 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, bifrictionating. I think you mean like dropping it, Like 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. You can blow up gunpowder without a spark, right, you can just use percussion. That's how gun works, right, black powder. Gunpowder is in the back of the bullet, and then the hammer comes back and hits the back 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 in bullets they use 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 agnight.
Yeah, sunfire and guns just have a hammer, right, there's no spark in a lot of those guns. There's a huge range of technologies though.
All right, Well, those are firecrackers that kind of go pop up up. 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 a firecracker, you set it and you run, it goes bang. But a sparkleer you can hold it. You could wave it around and you can like draw in the air with a light. Because the impression stays in you're retina for a while, and it also lasts for a while. You know, it can burn for like thirty seconds or a minute. So this is 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 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 sparkle looks like, you probably 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 in salt corn dogs? Are you a big fan of corn dogs?
It doesn't matter how much must did you put on that thing, It's not gonna taste good.
It's gonna it's kinda sparkle though in your mouth. So the way these works is that you take a sparkler and then you light up one end, but it takes it's sometimes it takes a while to light up, right Like, It's not like you put the flame to it and it immediately starts sparking and you kind of have to wait a little bit.
It's not like a fuse that immediately goes. You 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 also 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 it down. 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 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 there's 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 sparkles is sort of weird. They have metal powder in there, like you put aluminium 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 sparkles that shoot out.
Oh interesting, the metal that heats it. Well, if there's a central flame in the middle, right, and then that's the big bright dot 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, right, A sparkler is shooting super 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 Like you'll see a big stream of sparkle and then that will divide, and then those people then divide in itself, making sort of like this beautiful tree like almost snowflake like pattern.
It's sort of like fractals, right They heat 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'll split in half before they completely vaporize, and then maybe split in half again. You get these really cool patterns, and they're aphemarol, 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 why does 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, 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.
Cool, all right. Well, and so you hear it from Daniel, sparklers have sugar in them, so I'm just kidding. They don't give them a dry and don't put your head and you're too close to one if you're a little child. We just give them bad advice here today, Daniel. 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 farworks. 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 first let's take another quick break.
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All right, we are celebrating I guess July fourth, Daniel. This episode will come out around July fourth.
Mm hmmm, yeah, and all the summer holidays. 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 physicists in us.
All well, all right, I won't get into it anymore. I'm a baiting you go backing and exploding, Daniel.
I'm just trolling you.
Make sure to call it the big smash in the Big Bang, since it all means the same to you anyway, Let's be more confusing.
Sounds good.
How about the small the small smash. It 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 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?
Boys, physicists. I would never mock chemists because they're better at making poison gas and bombs than I am. I see right.
You 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 fourth or Bestiel Day. They throw these up in the sky, 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 we've talked about so far. There's a 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 in the sky. There's something totally different. They're like sparkler like stuff formed into little balls.
Oh interesting, you're seeing a firework. It's like a bunch of sparklers stuffed in with an explosion.
Exactly when you see the firework in the sky and you see it 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 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 could make your own firework kind of.
That's what a firework is exactly. It's just sparkler stuff packed in with black powder those high precision in order to get it to explode in just the right way and at the right time, 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 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 launch the thing up. It's just like a little gun.
Oh, but it's not like a gun. Like, it's not an explosion that propels it upward. Right, It's more like a controlled you know, like a real rocket, right, Like, it's not like a big bang. It's like a show, right, like it has to you know, expel the propellant slowly kind of.
Well, no, the explosion happens at the bottom of the tube. It's like a 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 thrown up. It's on a projectile motion, just from the initial explosion that pushed it out of the tube. A rocket has like continuous burning that's pushing it up as thrust, but a firework doesn't. It's just like thrown up by this tube, more like a mortar.
Well, maybe that's some of them, right, I think some of them, how do use sort of a rocket like a thing doing.
Yeah, you can definitely buy some fireworks that you can light off yourself that are like bottle rockets, right, that are propelled by those the kind 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.
Hmmm, I see well, I guess it's it's going to be tricky because you want to explode something or rocket something at 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 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 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 get to 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 happen like two or three different stages, so they'll blow up once and then they'll blow up again at the top, 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 way they do this is by very carefully arranging those stars, these pieces of spararkler 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 lot of experimentation exactly how to arrange those stars inside the fireworks to give you that reaction. I imagine they must fail a lot that or they have done some like really complicated computer simulations to figure out exactly how to build these things.
Hmm 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 had an 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 smiless phase, you just kind of arrange the sparklers in a circle around your explosion, right explosive, and then when it blows up, it'll 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 for that you just have like stars everywhere.
All right. So then how do the colors work? How do you get different colors of sparklers?
So the colors come from the different kinds of metal inside the sparkler. Remember the reason the sparkl or 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 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 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 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 you get different mixtures of colors for different elements.
So for example, if I wanted an orange firework, 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.
Hmmm, what about like red red?
You can either use lithium, which is going to give you like a medium red, or a strontium for like a really intense red.
Oh cool. 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 charcoal or iron. Things like aluminium 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 what they want, you know, magnesium or aluminium 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 farworks.
Somebody with like a wax mustache and a long beard is making this out in Brooklyn warehouse.
Right now, you're assuming they're hipsters, so Farward hipsters. But I wonder if that's a stressful job, you know, with explosives, because you're you're sort of crafting this thing by hand. There was something that can explode at any moment.
I'm sure they have good insurance.
I don't know. Having good insurance it makes me want to do something dangerous. It's almost the opposite. If you need good insurance for something, maybe you shouldn't be doing it.
Yeah, 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. 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 ooh, right, almost everybody loves fireworks, so you must be very popular.
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 gives 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. You can make, Like little cardboard packages 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 have to make them out of materials that burn up, right, Like, you can't make a farwork put like a steel too or a steal plate on it, because that thing's going to 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, So you need to be like a paper artisan too.
Yeah, I don't think we're like three D printing fireworks or anything.
Ooh, but not yet. You just came up with an interesting idea there. I wonder if you can get more precise sculptures if if you do three D print them.
Yeah, you might be able to guide the sparklers and exactly they're right direction. You could have like tubes or sparkler 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 wandering and waiting for.
Oh my gosh, that would be next level, like animated fireworks. Can you imagine like fireworks and move?
Yeah, that would be pretty incredible.
Sounds like something out of Harry Potter.
Maybe, Yeah, four D fireworks.
Well, nowadays it kind of seems like the future of these displays are drones. They're using drones more and more and they're almost kind of as And you can 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 nice alternative there, like.
The green alternative to artisical organic fireworks. 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 fireworks displace. I'm always wondering, like, what percentage of those videos is anybody ever watching?
Well, you can ask about any video ever taking, Daniel. If 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, all 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, with nobody in them, and go, oh, yeah, I remember that explosion that was really cool.
M Well that's because your fireworks grump, Daniel. Nobody would explain you to where he'd watched something something you don't like. Find more people would probably say ooh to that video than your kids eating pizza.
Honestly, if I invited people over there probably rather see a fireworks video than an old video of my kids eating pizza.
Yeah, 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 little pop to your day there or night.
And I hope my dis days for fireworks 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 exactly?
All right, I give up?
You win?
Yes, all right, Well, we hope you enjoyed that. Thanks for joining us, and we hope that next time you look up at the fireworks display you kind of think about all of the physics and chemistry that's going on then, all the artisanal skill that went into making those fireworks.
And how a happy summer fireworks season everybody, and stay safe.
Yeah, take a video and send it to Daniel. We're haad to enjoy it.
I'll edit them all together and put them on my website for somebody to download and watch.
Twelve hours of fireworks. That does sound pretty good. I think that's called the screen saver. Maybe I think they invented that already. Anyways, Thanks for joining us, see you next time.
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