How Lasers Work | STUFF YOU SHOULD KNOW

[music]. >> Welcome to Stuff You Should Know, a. production of iHeart Radio. >> [music]. >> And welcome to the podcast. I'm Josh and. there's Chuck and [music] Jerry's here, too. And she was making too many laser. noises, so we asked her to please go on. mute. She did. And I assume she's still. making laser [music] noises, we just. can't hear her right now. She had a. little attitude about it, too. She did. I mean, I was really mean and curt, but.

she didn't have to be that way back. Yeah. This is a one-way street. Right. >> [laughter]. >> It's my way or the highway. You know what? It's about time we did an. episode on lasers. Mhm. This seems like. something that we would have tackled in. those first formative in that first. formative decade. And I'm glad we didn't cuz I think it's. good to still do like a traditional, you. know, how X works. episode. We should do one on how X.

works. It depends on what kind of X you're. talking about. Ruby used to give us an X when she was. little. When she was like 2 years old, if she didn't like something, she would. do her fingers as an X. >> [laughter]. >> And she just keeps getting cooler and. cooler. She forgot that she lost that. one along the way. I need to tell her to. bring that back. Yeah, that's a good. one. >> Uncle Josh likes it. That's like talk to the hand, but way. better. >> Yeah, exactly. All right, so we're talking lasers. today, not necessarily X. Um, maybe we.

will do X someday. Let's find out. Okay. >> And everybody knows what a laser is, right? Yeah, I mean, I I feel like it's. one of the more like one of those. acronyms like scuba that you learn when. you're like on the playground. Mhm. So, in this case, it stands for. light amplification by stimulated. emission of radiation. And now that I. know what a laser is and how it works, they kind of nailed it with that. acronym. They did. You You can totally. forgive them for the bi and the of.

because that's a world-class acronym. Yeah, that would be lab. scior. if they included those. Laser is so much. cooler. >> Lab scior doesn't Yeah, it doesn't have. that same ring to it as laser. >> Throw me the lab scior gun. >> [laughter]. >> Then someone would say, "No.". >> Yeah. So, um. lasers are everywhere, everybody. They're all around you. A lot of them. are pointed at you right now. You just. can't see them. >> Mhm. Um but like a UPC code scanner at a.

supermarket checkout, they still have. supermarkets, right? Uh yeah. >> that's right. Everyone goes in and. empties all of their bank accounts into. them every week. >> Right, to get sustenance. Well, when you check out, boop boop boop. like that, that's actually a laser being. triggered. Your It's scanning your UPC. code. So, lasers are everywhere. They're. at the supermarket, at least. That. doesn't necessarily mean you understand. them. I didn't understand them until we. started to research this. Did you? No,

and it's really not that like hard to. wrap your head around, actually. I was I. was kind of dreading this, but it's Dave. did a great job with this article, sort. of like he's in the traditional sense, like he said. >> Yep. Uh and he does a good job initially. by sort of laying the groundwork of. regular light compared to a laser light. And I think that's a great way to start. Well, yeah, if we're going to talk about. lasers, we really I mean, we're talking. about light. We kind of need to go back. a couple of steps and say, "Okay, there's different kinds of light, you. know? Like the light we think of as.

sunlight or a light bulb or something. like that, what we would call generally. white light. >> Mhm. is as a lot of people know, a all. of the colors of the spectrum, the. visible light spectrum together, coming. together to form white light. That's. right. Many different wavelengths, uh. but just like, you know, elementary. school science, when you get that prism. and and your little mind is blown, it. still kind of blows my mind. You scatter. that light into its different. wavelengths. It's so beautiful.

>> And it's the colors of the rainbow. there, but and this is something that. like I don't think I even realized this. Even those different wavelengths, it's. not a single wavelength. It's still a. spectrum of different wavelengths. creating the red or the blue or the. yellow or whatever, and that's kind of. where we find ourselves um. you know, departing in what a laser ends. up being. Yeah, because so for example, the the. yellow band, what we see as yellow in. the visible spectrum occupies the 570.

nanometer to 590 nanometer range. >> Show off. >> Below that, I think you got what? Red, orange, something like that. Roy G Biv. Yeah. I can't remember. Uh above that, you've got blue. Green. Roy G. Green. And those just have different. wavelengths. They're all electromagnetic. light. It's the same thing as a. microwave. It's the same thing as a. radio wave. It's the same thing as a. gamma ray. It's just the different. frequencies make them different kinds of.

energy. What we call the visible. spectrum. The point is is within all. those different nanometer wavelengths, say from 570 to 590, there's different. kinds of yellow. There's different. different shades of yellow in there. across that the spectrum within the. spectrum, I guess. >> Yeah, spectrum within the spectrum. Mhm. Also a great album title. That is a great album title. >> Jazz fusion. >> Maybe you could have like a prism with a. beam of light coming in and then the. rainbow coming out the other side. Yeah, this 1960s for sure. Yeah. A pyramid.

even. Is a prism. Yeah, with. uh Isaac Hayes's head floating above it. I'm describing the Dark Side of the Moon. album cover. I know, I was just kidding. Okay, well, you were really throwing me. off. You were That was some meta joking. right there. >> a great pressing of Dark Side of the. Moon, by the way. You do? Yeah, you know, I had a record. presser, a guy who does that for a. living, uh I was hanging out with him in. New York with our friend Joey Sierra, and these two guys who did that. And he.

said, yeah, some pressings, like it's. done by a human, so you might have some. records that just sound really awesome. Oh, neat. >> Cuz it was well done. And I was like, yeah, and they're, you. know, 180 g. He was like, that's all. bunk, by the way. He's like, it just makes you feel better. that it's heavier. And I was like, um. man, that's disappointing. Yeah, I do. like the heft of a 880 g one. Apparently, they said it's that's all. just for you to make you think it is. better cuz it's heavier. It's heavier, so it's worth more. All. right, so back to lasers. Uh you what. you just described, very well, by the.

way, was regular light. uh wavelength within the wavelength. If. you talk about the differences of a. laser light, you're talking about three. main differences, and the first of which. is that single wavelength. It's mono. like truly monochromatic, that beam of. light that a laser is, or I guess, you. know, produces. Well, no, it's what it. is. Is is just a very it's a single. wavelength, highly highly concentrated. Yeah, so rather than, say, a wavelength. between 570 and 590 for being yellow,

this is a 572 nm wavelength that is that. specific yellow. That's right. >> And it's it's not it's made up entirely. of yellow light on the exact same. wavelength. That is incredibly. important. That's a huge huge. difference. Lasers don't occur. naturally, we've figured out how to make. them, and by we, I'm including myself. and you. That's right. Uh the second big. difference between laser light and. regular light is that it's coherent. So,

not only is it just a single wavelength, but the photons of the light, and we're. going to talk about where where they. come into play here in a second, thanks. to Mr. Einstein, or Dr. Einstein. >> Uh the photons are perfectly in phase. with one another. So, if you look at. that wavelength, the the peaks and the. troughs are all perfectly in sync. Yeah, and not like they're following the. same plane and they're just kind of in. sync like that. Like they're up right. above each other, right below each. other. They're not interfering with one. another in any way whatsoever. That's.

right. And then the last one is that they're. collimated, meaning they're all. traveling in the exact same direction. Yeah, I mean that's that's important. I. mean collimated sort of a fancy way of. saying directional, but. as we'll see they all have to be. traveling that same direction to pick up. their little photon buddies. Yeah, so essentially what you've got is. a very specific kind of the exact same. kind of light. None of which are interfering with the. other photons that are coming out of the. laser. All of which are traveling in the.

same direction. So, they do not get in. one another's way and they can be. combined very, very tightly. And that's. essentially what a laser does. Yeah, for sure. And it all goes back to. that acronym stimulated emission. The SE in laser, you can't make a laser. without SE. That's true. >> spell laser without SE and you can't. have a laser without stimulated. emission. And our buddy Einstein is the. guy who. sort of laid the theoretical groundwork. He didn't go out and build a laser, that.

came later. But he laid the theoretical. groundwork for all of this back in the. ridiculously in the early 1900s. Yeah, so back in 1905, most people were. like light's a continuous wave and by. proxy the universe is one smooth. continuous thing. And Einstein was like, I don't think that's true. I think if. you zoom in far enough, close enough. into the fabric of the universe, you're. going to see it's actually made of. discrete little. little things. You can call them pixels, right?

And. he's like if that's true, then light. can't be one continuous wave either. So, I think they're actually made up of. those little tiny packets that I'm going. to call photons. And he turned out to be. right. He had a great equation for it, too. It's It's so elegantly simple. That's the thing about Einstein, he. could come up with like three different. things and could completely change our. understanding of the universe. >> Yeah, for sure. Uh this is the. Planck-Einstein Einstein. What just. happened?

I was concentrating so heavily on not. saying Planck. I've heard Planck. I think that's how. most people say it. Oh, I've always. heard uh Planck. Okay. >> I've heard both, but most of the people. I've ever heard say Planck, but I mean I. run in pretty lowbrow crowds. >> I. I think the uh probably the correct is. Planck, but most people do say Planck, you're right. I like the way that you. said it the first time, the. Planck-Einstein. >> No one says Einstein, though. Uh yeah, the Planck-Einstein relation, um which is uh the energy of each photon.

is equal to its frequency times. Planck's constant. E equals HF. Yeah, and all Planck's constant is all it is, it's the smallest possible measurement. of energy that any anything can have on. like the quantum level, right? And so, Einstein was like, "Hey, I want. to figure out how all this stuff kind of. interacts because I know that photons. interact with electrons. I'm just. positive of it.". >> Mhm. Wow. They were fig- That's pretty good. [laughter].

They were figuring out he was figuring. out, and I think other people were at. the same time, that when you have. subatomic particles like an electron. orbiting an atom, which if you go listen. to our periodic table episode, I think. we did a pretty decent explanation of. how that that, you know, that symbolism. or that visualization of it is not very. correct. >> Mhm. But for all intents and purposes for. this, let's say that these electrons. orbit in different orbits around the. atom, and when a photon hits it, that.

orbit that electron goes up in energy I. think for like a. 100 nanoseconds typically. >> Yeah. And then it says, "Okay, I want to. get back to my resting state, it's. ground state." And it goes back to its. previous orbital, but when it does, it. poops out a photon. You know what's. funny? What? >> As earlier when I was going over this in. my head, I said poops out a photon. Sure. I mean, you and I, >> [laughter]. >> we share a brain and when it comes to. toilet humor. >> Yeah, that's true. Uh that's exactly right. So, an atom is. going to absorb that energy and it can.

do that in a lot of ways, but let's just. say in this case it's like some it gets. heated up, you know, like literally. heated up. Mhm. Uh those electrons are. going to jump around and get excited, but once they that makes it unstable, but it wants to be stable. So, when it. goes back to that state, you're right, it poops out that photon. Einstein saw this, called it spontaneous emission. Yeah. And this happens all the time all over. the place in in nature. Uh it these photons are getting pooped. out all over the place, but Einstein was.

like, "Well, hey, if it happens all the. time naturally, he theorized maybe we can. we can stimulate it to do this. Maybe we. can make this happen and control that. emission.". Yeah, because here's the thing, right? Like you say you have a photon that hits. an atom and and knocks an electron into. the higher energy state, then that. electron poops out a photon. Well, that. electron has just absorbed the photon. So, another way of looking at it is the. photon essentially goes into the um. electron and comes back out the other. side Mhm.

but there's only one photon ever. One. gets absorbed, one's produced. What. Einstein figured out is with stimulated. emission, you can use a photon to create. another photon without losing the first. photon. And if you do that a bunch of. times, buddy, you can have like. like you could make a basket with your. shirt and fill it with photons if you do. it right. Yeah, I mean, he he realized. that photons like to hang out with one. another. So, it it doesn't take a lot to get. them, uh you know, traveling in a direction.

and saying, "Hey, buddy, come with me.". And it creates this sort of sort of like. a snowball, like a cascading effect. Uh. where if you can get them in an excited. state and stimulate them. and have them pick up other photons and. have them all travel in the same. direction, Mhm. you're like halfway. toward lasertown. Pretty pretty [laughter] much. You can. see the outskirts of town in the light. shooting up in the sky. >> Yeah, you can. So, um yeah, so that's stimulated.

emission. And the the key here is you. don't have to spend a photon to get a. photon, right? You can excite the atom. in other ways. As long as it's already. in its excited state when the photon. comes along, it's going to produce. another photon. Now, for the purposes of. lasers, what's really really important. here is it is going to produce an. exactly identical photon as the first. one that passes by. Going in the same. direction. >> it's yeah, in the same direction and. it's not it's not going to interfere. with the first one. So, they're cohesive.

and they're collimated and they're. exactly the same. They're monochromatic, which as we said before, those are the. things you need for a laser. So, Einstein figured out back in 1917. how to make a laser and then was like, "You guys figure it out. I'm going to. think about some other stuff." Yeah, and. if you say, "Well, wait a minute. I. thought you said 1905." Like it even. took Einstein a little while to get. there, you know. That's right. Took a. little while. So, should we take a. break? Yeah, I feel like a break is imminent. All right. We'll be right back with more.

lasers. >> [music]. >> All right. So, when we left Einstein did. some some great work um kind of laying. the groundwork, the theoretical.

foundation of a laser. And then he was. like. guys, I like to to think of things with. my brain and say them out loud and write. them on chalkboards. Right. >> if you want to build this thing, fine. Maybe slide me some cash. But uh. but I don't do that kind of work. So, people did though that followed in his. footsteps. And in the 1950s there was a. physicist named Charles Townes. He. worked at Bell Labs. And who he was. doing research on. microwaves, microwave radiation.

And he was trying to. he didn't know it yet, but he was he was. halfway to laser town because he was. trying to find ways. to concentrate a beam of microwaves in. this case. What's nuts is this guy figured it out. He just basically tinkered around and. made his own version of a laser, but. rather than using light, he used. microwave beams, right? >> Yeah. He built like a thing. Yeah. He just he used ammonia atoms. He. put them in a sealed chamber. Um and he. got them to essentially emit microwave.

radiation that he was able to um. concentrate into a beam, right? So, that cascading effect happened just. like we discussed before. And. essentially the only difference is it. wasn't a light, it was a microwave beam. And to test it, he aimed it at the front. pocket of a passing colleague, Percy. Spencer, who happened to have a. chocolate bar in the front pocket of his. shirt. >> about this, I think. >> it. And Percy Spencer never forgave him.

because that was his favorite. short-sleeve button-down shirt. I think. we talked about this. Did we do one on. microwaves? Yeah. Okay. Well, that would. be exactly where we talked about it. then, probably. Yeah, and they weren't. colleagues. I just made that part up, but that was a. that was for you, buddy. Oh, no, wait. There was a chocolate thing, though, what? Right? Yeah, yeah, yeah. That. happened, but separately. I think Percy. Spencer was in the presence of some. microwave generator and his chocolate. bar melted and he went on to invent. microwaves. This thing was totally. different. It's just It just brought.

Percy Spencer to mind. >> Yeah, I like it. Uh so, he literally. called this. a maser. A microwave amplified stimulated. emission of radiation. Uh. he teamed up with a guy, it was a. colleague named Arthur uh Schawlow. And he said, "Let me see if we can do. the same thing with light and we'll call. it an optical maser.". And everyone was like, "Buddy, it's. right there in front of your face. Like. Exactly. >> Come on. Just get there.". I think it was Theodore Maiman. Um I.

like to call him my man. Who actually came up with the the laser. Uh he built the first functional laser. in 1960. And came up with the name? I think he did. >> Okay. Up to this point, um they were uh they. were all theoretical. And my man was the. first one to actually build one. And he used a ruby crystal. Which um at the time, I think, had. already been dismissed. People were. like, "You can't use that to to make a.

laser." And he's like, "Let me try. again." And he did some more. calculations. He's like, "The ruby's. actually going to be great." So, he used. a pink ruby crystal as what's called the. gain medium. Yeah. That's like the material lasing material. that you would use. Exactly. That's where the atoms that you. get excited are all stored. Yeah, so he. surrounded that crystal uh with a. um with a flash, it was a coil-shaped. flash bulb. So, that's that's going to. be the thing that, you know, the heat or. whatever or the light that stimulates.

the initial reactions. The pump. Sure. And then the two ends of that crystal. were painted reflective silver, so. everything is sort of um kind of trapped. in there together, encouraging all those. photons to bounce around and get a. little wild and create more photons and. say, "Hey, you know, we're we're doing. something here, guys.". And all yeah, all of these photons came. out at 694 nm, which I guess is the precise wavelength. of ruby red. >> Yeah, I guess so. And he showed that like there there.

here's a laser, check it out. Um, let me. see your face, basically, I think was. how he showed it off. >> Right. He would just wave it in people's faces. >> That's why he's my man. So, um, that was it. I mean, that was the first. laser. That and it was I I you want to. say like it was as easy as that. Of. course, that's not easy, but the. principle of it is kind of like you. said, it's simple to understand, which. is great. Like we did one on the. breathalyzer and it is so ridiculously. complicated. It's It's more complicated.

than a laser by far. >> I I hated that one. I did, too. >> That was a long long time ago. >> I remember we picked it, we started. researching, and I was like, This sucks. >> Wait, why am I not understanding this? It was just so complex. Let's never talk. about it again. >> I think we just wanted the explanation. to be like, blow into tube, smells beer. Exactly. And just make a bunch of like. drunk jokes. >> Exactly. Uh, all right. So, that that was the. first laser. Um, like you said, he used. that ruby to begin with, but there are.

all sorts of gain mediums. Uh, there can. be liquids, there can be. uh, gases. And we should probably go. over the five main types of laser now. Starting with, um, like if you've ever. been for tattoo removal or um, like had. a skin cancer with laser removal, they're using a solid state laser in. that case and it's called solid state. because they're using a solid crystal or. a glass or something like that. Mix it. up with a little. uh, with a gain medium like um,

well, it's it's they're all rare earth. elements like chromium or something like. that. Mhm. >> Uh, neodymium is that one? Yeah. There's also ytterbium. ytterbium. Man, I even looked it up. Ytterbium ytterbium. Ytterbium I bet is. right. That's a that looks funny. It it. it is great though. Y T T E R B I U M. ytterbium. I got it. And all of those basically they dope. that say like you could still use ruby.

but you would create like a ruby crystal. that's doped with these impurities that. you've selected based on their say like. reflective properties or their. phosphorescent properties. These things. can generate some photons really. efficiently and they're going to. generate them in exactly the wavelength. that you want. That's a solid state. laser. It follows in the tradition of. that original Maiman's laser from 1960. You know, Emily knows not much about. football, doesn't care, but there's. always a few players that she knows of.

and it's always very funny. Um. Patrick Mahomes is one of them. Mhm. And. every time she hears of him or anything. she just goes Mahomes. Very nice. Sort of like my man. Oh no, I'm with you. It's a great way to say. it. Okay, it's nice. Uh one thing I want. to point out though about these. different types of lasers is all of them. are they use different types of lasers. according to whatever application they. want to use it for. So it's not just. like hey these are cool. Let's use let's use this crystal with.

this. doping agent because we just think it. sounds awesome. It it's all highly. specific to what you want to end up. using it for. Yeah, like even like tattoo removal you. said which I'm in the process of. I'm. getting toward the end there buddy. How's it looking? Pretty pretty gone? Pretty light. Yeah, it's start yeah. I. mean you can still see it especially if. you walk up to it but you could also. miss it if you weren't looking for it. It's getting like that. Just like wow. that guy's got mildew on his arm. I took the other tack as you have seen.

recently when we were on tour. I had a. probably 2-in by 2-in tattoo that I. covered with half of an arm sleeve. I didn't see it. You haven't shown it to. me. Oh, how was Was I always in long. sleeves? Yeah, and I forgot to ask. I. actually thought about that when we were. researching this. I was like, "I haven't. seen Chuck's new tattoo." Well, I'll. I'll take my shirt off in front of you. soon. Okay. But even with the tattoo removal ones, they have different types of solid-state. lasers. The The The gain medium is. different, right? There's one called the.

ND. YAG laser? Yeah. That's a really common. one. Neodymium-doped yttrium. Yeah. Aluminum garnet. That's the That's. the gain. medium. And that's for I don't remember. what that one's for. I think different. color like regular color tattoos, whereas like if it's green, you have to. use a different kind of gain medium. Yeah, so it is [clears throat] extremely. specific. All right. Well, can we move.

on to gas lasers? I think it's time, yeah. So, obviously they're going to use. gases as their gain medium. Could be a. carbon dioxide laser. Could be argon, could be krypton if you're really into. comic books. And these are different than solid-state. lasers, obviously. Uh. In solid state, the atoms are excited by. a light source. In this case, it's an. electrical current that's going to get. them going. Yeah, it gets them excited. Um there's all sorts of stuff you can. use with gas lasers, but probably one of.

the. the most famous one is using a carbon. dioxide as the gain medium, and those. things can get those photons going. You. can weld with it. That's how That's how. powerful these lasers can be. You can. weld metal with that stuff. And then at. the same time, if you use a different. gas, you might have a excimer laser. You. can actually break the bonds that hold. molecules together. You can alter cells. you can destroy tissue, but it it uses.

UV light, so it doesn't produce heat. So, that's how you can use that on. someone's skin without burning them, but. still say removing like a a. squamous cell or something. Yeah, or if. you've ever um heard of something being. laser cut, uh then it's probably going. to be a gas laser doing that business. Yeah, hopefully that you didn't hear. about that from a squamous cell being. removed. Right. There's also fiber lasers. These are. very special lasers. Uh. I don't know how they found this out, but scientists concluded that the um.

the cloaks usually or the textiles found. with bog bodies have some sort of. magical properties that if you use them. as a gain medium, they make really great. lasers, hence fiber lasers. Right, but. in this case, they're used in. conjunction with a fiber optic cable. So, these are obviously have long been. used in telecommunications and stuff. like that. Uh and because they are used. in conjunction with an actual cable, uh they're very, very efficient. So, they convert more than 50% of the.

electricity that's input into light, but. that ND. YAG laser has about a 3% efficiency. rate. Yeah, that's pretty efficient. Um that's. another way that lasers are part of your. everyday life. Um. the if you have fiber internet, like you have a laser on one end that. your ISP is using to send um. communications or encoded information.

along a fiber optic cable, and your. modem is basically a laser receiver that. translates it into whatever your router. needs to explain it to you. Yeah, that. man, that uh. breaks my brain like vinyl records. does, you know? Yeah, it's pretty cool. though. And that's the thing. So, it's. just like when radio um with radio. waves, we figured out how to encode. information in radio waves. We figured. out how to do that with light. It's just. lasers are way more efficient. They can. travel way longer than radio waves can.

And apparently, they're starting to look. into this to to transmit information. between the Earth and the Moon. >> Oh, boy. So, you'll just be able to you'll have. basically not even fiber optic internet. You'll have laser internet on the Moon. Wow. I thought I think that's wild. Yeah. Uh. what about liquid lasers or dye lasers? I should probably say because you played. that so straight, my explanation of what. the gain medium is for fiber lasers, that's I just made that up everybody.

Oh, I fall victim again. Did you? You thought that they used the. cloaks from bog bodies for that? Man, I don't All of this stuff is so. brain-breaking. Nothing Nothing would. You could say human feces and I'd be. like, "Yeah, of course." That'd be Man, that'd be gross, but I'll bet you could. >> [laughter]. >> I think you could use anything with. atoms that's excitable to potentially. make a laser. You You've become such a. good straight person that it's just hard. to tell anymore. It's hard to tell with you, too. Hey,

thanks. Yeah. Thank you. Uh liquid. lasers or dye lasers, these are sort of. brain-breaking, too. They use organic. dyes as the gain medium, Mhm. which is. kind of crazy to think about, but each. dye like will produce a different laser. light because you're going to have, you. know, cuz it's a color like a different. wavelength. Right. And these are really. cool cuz you can actually tune them to a. very You can manipulate them and tune. them within a very specific range for. specific uses. Yeah, so one laser can be used for all. sorts of different things, which is I'm.

sure quite cost-efficient. >> Yeah. I think that's one of the. downsides of solid-state lasers. It's. like one thing you can do with one. laser. >> Yeah. Although, it'd be cool if like it's just. a cartridge you can pop out and put in a. new a new crystal. Yeah. >> That'd be sweet. should. >> on that. They have to be, you know? Like the cost. of lasers have come down tremendously. I'm sure we'll eventually get there. Yeah, just ask my cats. My cats with an S. Well, let's talk. about that. We're kind of at that point.

Do you play with your cats with laser um. pointers? No, I have, but I I they. always get lost cuz they're always. small. Oh, got you. Got you. Um well, that is. actually a kind of laser. That's why. they call them laser pointers. They're. the weakest laser, but they use diodes, which are two different materials that. when you put them together with a place. where they interface creates a. electronic exchange and hence a flow of. electrons and that creates electricity. So, that's what these things are powered.

by. This is the the way that the um. the light photons get made from the. excited atoms. And they're super cheap. They're not. very powerful and that means that over a. fairly short distance, I think like. hundreds of meters, they basically. they're not a tiny point any longer. Yeah. >> And I was [clears throat] looking into. this because when I hear laser pointers, I think of jerks like trying to shine it. in the light of a airline pilot. >> Oh, sure. That's a real problem, actually. I think it happens a couple. thousand times a year in the US alone.

Yeah, concerts, too. People do that. stuff. Sure. The reason you're not supposed to do. that with airline pilots is because by. the time it reaches the cockpit, it is. spread out so much that it's just it's. like a huge ball of light that is so. bright in the cockpit that they can't. even see the instruments anymore. Yeah. So, it's not like you're just putting. like a little dot on somebody's cheek. You are blinding everybody in the. cockpit right then. It's it's a huge. problem that you really should not do. Yeah, and also. what's funny about messing with someone.

doing a very important, dangerous job. where hundreds and hundreds of lives are. at stake? Yeah. What's the mess with. that person? Yes, and I think everyone's. parents should sit them down and say, "Let's talk about laser pointers because. you probably aren't grasping what a. problem this is." Agreed. Uh well, that's a that's a weak one. Those diode lasers are semiconductor. lasers, but um since the very beginning, uh science has tried to make the like. more powerful lasers. Mhm. Uh and they. have done a pretty great job at it.

We'll go over some of these, but um you. measure and uh a laser by how quickly. that laser is emitting the energy. So, it's joules of energy emitted per. second. Right. They measure that in. watts. And uh. they figured out pretty early on that a. continuous beam of light emits a. constant amount of energy over time. So, they were like, "Hey, I bet we can make. these even more powerful if we cut that. off very quickly over and over and over. and admit pulses of energy.

because it builds up and it just gets. stronger and stronger." And they tried. it out and it really worked. Yeah, pulsed lasers, right? Cuz like you said, a traditional laser, it's the same. amount of energy the whole time the beam. is on. With a pulsed laser, it's kind of. like stopping up the uh the beam of. light so that it just the energy builds. up behind it and then you open it up. again and when you release it, it's this. ultra-concentrated. beam of energy. And it's it's. mind-boggling how fast this happens. So.

fast that your puny brain just sees it. as one constant beam of light. Yeah. And. we we don't have the technology to slow. it down enough, I don't think, to see. the pulsing because we're talking. billions, trillions, quadrillions, quintillions of a second how frequently. those that thing is pulsing. Yeah, it's incredible. Uh I think they. first demonstrated that in 1961 with. that ruby laser. And uh I think they ended up with. 100-nanosecond burst in 1961, which is.

pretty impressive. >> Yeah, for sure. Cuz a nanosecond is a. billionth of a second. Yeah. So, in 1961. they were able to get that first laser. by pulsing it up to 1,000 times more. powerful than my man's device. Yeah, this is a year after he built that. first laser, right? Yeah. So, um I think. that was, what did you say, 100. nanosecond bursts? I saw that with the. the tech that they're using now, nanosecond pulses are called giant.

pulses. Yeah. Seriously, that's what. they consider them. Yeah, and those are. quintillionths of a second, which is. hard to even wrap your head around. For. sure, right? So, these things these. pulses are just like that's It also, Chuck, I think goes to show you. how quickly energy builds up in the. chamber where that where the beam is. released from, that it's it's like. creating the thousand times or 10,000. times or however many times stronger. beam just from backing it up in like one. quintillionth of a second.

Yeah. Sure. You want to take a break? Yeah, let's take a break and let's talk. about just sort of real-world uses and. what's going on out there. Okay. >> [music].

>> So, Chuck, there's some um there's some. lasers that are just super powerful that. are being built right now. Of course, physicists are like, let's see how. powerful we can make something. There's. one at the University of Michigan called. Zeus, Z Petawatt Equivalent Ultra Short. Pulse Laser System. And then there's one in the UK that's. being built called the Vulcan laser. Yeah, and these I mean, the one in the. UK has a power. of 500 million 40-W light bulbs. Oh,

40-W? Well, yeah, that's true. That's not. much. Uh and the Zeus can generate a. pulse of light that's uh. 25 quintillionths of a second long. Mhm. And so But wait, how much energy does it. release? Uh three petawatts, baby, which. is 100 times the total electrical output. of the entire world in one quick burst. So these things are they're like um.

they're so powerful and energetic that. what they're one of the main things. they're going to be used for is to study. what it's like inside a black hole or a. star or something like that. That's. that's like what they're able to. recreate and see what happens when it. bounces off of an apple or something. like that. What happens when you bounce. a black hole off of an apple? >> Yeah, that's that's basically. why they're trying to create these this. powerful. It's not so they can blow up. the Death Star, even though that's a. good case use. Uh it's it's so Yeah, so they can.

recreate like. the energy in the inside of a star and. find out the mysteries of the universe, basically. Exactly. There's another. thing you can use really, really. powerful lasers for, and that's nuclear. fusion. And we did a whole episode on nuclear. fusion, I think in 2019. That was one of my favorites of all. time. And it's this whole thing that's the the. promise of basically free, unlimited. energy that you can power anything with. with almost. like what you're getting out is way more.

than what you're putting in. And um it's essentially where you take. light nuclei and fuse them together to. create a heavy nuclei and a lot of. energy is released. It's just we haven't. quite figured it out. Well, you need. like plasma concentrations. These are. plasma lasers. And apparently in 2022 at. the Lawrence Livermore Lab, they used. 192 of of lasers um to essentially. create the world's first nuclear fusion.

reaction that produced more energy than. was put in. There was a net gain. Yeah. Uh. they called that the the Wright brothers. moment as far as lasers go. Sure. Because you got a net gain for the first. time. They focused those lasers at a. capsule the size of a peppercorn. And that did it. And I I bet that was a. great day in that lab. I'm sure. I mean, once we get to nuclear fusion, that's. that's going to change absolutely. everything. Yeah, for sure. Um so, you can use it to for nuclear.

fusion, you can use really great lasers. to recreate different crazy exotic. aspects of the universe. There's also. way more pedestrian uses for lasers. Like we said, barcodes, fiber optic. communication. Um but there like when. you start to look around, lasers are. everywhere. Essentially, anything you. can bounce light off of. or that you can um that will absorb uh. light, Uh-huh. you can use a laser for. for some application or other. Yeah, for.

sure. Uh they're all over the medical. industry for in all kinds of ways. Uh I. think pretty early on, they were like, "Hey, these. uh using a laser to cut into the human. body is way better than a scalpel.". Sure. Um it's way more precise. Uh. there's less damage on the tissue. It. self kind of self-cauterizes as it goes. So, it's going to be sterilizing the. tissue that surrounds it. It's going to. be less blood loss. You're going to heal. up quicker. So, that's they're I mean, scalpels are still around, but they you.

know, lasers are the way to go. I saw. that there's a uh brain tumor laser. procedure. that uses a 5-mm hole in the skull, and. you get discharged the next day. That's how accurate and amazing these. things are. Plus also, it's way easier. to attach to a robot than to give a. robot a scalpel to use. Yeah. Uh I hate to bring it up again, but that was just on an episode of The. Pit. That exact case use that you just. mentioned. The laser tumor? Yeah, the tiny hole in the skull. Uh we. started watching it. I gave it another.

try, you me and I did, and it's it is. pretty good and engrossing. Yeah, and. gross. It is. Yeah, and I figured out too we were. watching last night. I kind of forgot. the reason why I was saying there's so. much of like. of Noah Wyle over-explaining everything. to all the younger doctors and residents. is because it's a teaching hospital. Yeah, there you go. Which is a great. vehicle to explain whatever the heck is. going on to the viewer at home, you. know? Yep, for sure. Uh all right, so back to medicals, since.

we're talking about The Pit, have you. ever had an endoscope? Um that's, you. know, when they put a long flexible. tube, uh. down your throat a lot of times or up. your nose or who knows what holes they. can put them into these days. >> It depends if it's a rubber hose, you. know where that goes. That's right, Vinnie. Uh essentially, you can access these. tough-to-reach areas with these tiny. little tubes, and in this case, you can. have a laser attached to it and send it. in there to shrink a tumor, like you.

were talking about. >> Right. Um and then you can also use them. to do things like destroy the epidermis. and then heat up the dermis underneath. to get rid of like spots or something. like that for all sorts of um aesthetic. dermatological applications. Yeah, cosmetic stuff. Yep. Uh tattoo removal, that kind of thing. LASIK? What about. LASIK? Yeah, LASIK is a big one. Um that. has become vastly improved as lasers and. robots have improved. I think it was. first started first became approved in.

the US in 1999. And since then, it's gotten really good. I think 90% of people who get LASIK uh. have between 20/20 and 20/40 vision. afterward. And it's like the pool of people who are. um. candidates for it are is pretty wide. It's not like, "Yeah, if you can if you. need just like those magnifying readers. that you buy at the pharmacy, Right. >> you're going to LASIK's going to benefit. you." No, you can have like pretty bad. myopia and still.

benefit from it. Yeah, in this case they. use the laser to reshape the cornea. Uh didn't you debate LASIK at one point? Yeah, I'm I'm still thinking about it, but my vision we're we're basically at. an age where the your vision changes. fairly rapidly and you want it to. stabilize or else you would get LASIK. once and then you'd end up needing. glasses when your vision degrades again. I think Emily has been debating it, too, a little bit lately. I'm not sure why. I. looked into it and I was convinced like.

this is this is pretty safe and. effective and yeah, I would do it. I'm. just not there yet. I feel like when. I've seen you lately, you're having. trouble with the the contact lens. It. because it's been wintertime and dry and. it makes them It makes it easier for it. to like fold over or something like. that. Pop out. It sucks. Sorry. Uh there's also weapons. Of course, you. can use lasers for weapons. Apparently, the Army, the Navy, and the Air Force. are developing laser weapons to.

different different levels of success. But they're definitely working on them. not to necessarily like, you know, mow down troops, but to say. blow up a drone or something like that. Yeah, they're called directed energy. systems. Uh some of them attach to like a. turret on a ship. Um those seem to work. pretty well for like you said, like. taking down a drone or something like. that. Um they have others. I think the Army. has one. Uh a 50 kW that's on an armored.

fighting vehicle, but that hasn't done. so well because you know, for a laser weapon to be pretty. effective, it has to be super tightly. focused and pretty um. locked down and they're like, "Hey, we're driving this thing around and it's. not very accurate.". >> Right. And that's the Striker armored fighting. vehicle. Striker with a Y. Yeah. >> It's like they looked to GI Joe stuff to. come up with names for it. For sure. There's also this one's pretty sweet, too. Laser cooling. And there's also so.

many different applications. Like you. can you can um. track soil moisture from space to see. how bad a drought is. You can uh track. how badly ice is receding in the in the. polar areas. You can You can do. everything with with lasers. They're. really great. In case that hasn't gotten. across so far. But this one to me is. just amazingly cool. Yeah, no pun intended. Laser cooling. Uh. what they're doing is basically kind of. freezing an atom or molecule in place.

Uh it's also called a particle trap. Mhm. And it's it's the same sort of. physics of stimulated emission, but kind. of in reverse. Yeah, when a when a an atom poops out a. photon, that kind of pushes it in the opposite. direction that the photon's traveling. They figured out that they can use. lasers to keep to basically balance that. out. So these things are still producing. photons. They're still doing their.

thing. They're They're in energetic. states and oscillating and doing all. sorts of stuff like they're supposed to, but they're just not moving around in. space while they're doing it. Yeah. So they're essentially they're just. It's like a tractor beam holding it. where you want it. Yeah, it just slows. it down such that it's basically. stopped. Yeah, but it's still doing its. thing. It's just not moving around while. it's doing it, right? So now that you. have an atom trapped, um you can do. something like like this is the future.

of atomic clocks. You can measure the. oscillations oscillations of that one. specific atom so precisely that atomic. clocks are about to be just ridiculously. more reliable than the atomic clocks. today, which I think we can all agree. are pretty reliable. So, that's a huge. groundbreaking use for that. Yeah, for. sure. I mean, it's easier to study. something that's sitting still. Exactly. Yeah. Um yeah, now that I think about. it, that basically overcomes. Heisenberg's uncertainty principle where.

you can't measure something and know. where it is at the exact same time. Apparently, Heisenberg didn't think of. lasers. That's the nerdiest sentence you've ever. said. >> [laughter]. >> Well, come to think of it. You got anything else? I got nothing else. You know, there's. obviously a lot more, but I think that. was a good good old-fashioned. overview of lasers. >> Agreed, man. Uh and since Chuck said old-fashioned, he just accidentally triggered listener. mail.

Uh I'm going to call this an answer to a. question. I love it when we put out a. question, we get answers. We were. talking about color psychology, and I. wondered because I have a. African-American church around the. corner from me. Oh, yeah, the purple. Actually, yeah, purple. And we heard from a listener, "Hey guys, I'm writing to share some insight. regarding the morning colors at at the. nearby church. While traditions can vary. between African-American churches, I. hope the following information is. helpful. In the 21st century. African-American traditions, it is. common for individuals attending a.

funeral to wear the deceased person's. favorite color, which is what I thought. might be happening.". >> Oh, neat. Uh in some cases, all in. attendance are encouraged to do so, while in others, it's reserved for. family members. Uh regarding the use of. purple specifically, this color is. typically associated with royalty and. Jesus Christ. If you consistently see. purple at the church, it may be. it may signify recognition of the. deceased returning to God. Mhm. Uh or. maybe just the person's favorite color. So, I truly appreciate your program, allows me to stay present, and provides.

a welcome escape from the daily news. cycle. I look forward to becoming just a. tad bit smarter as I continue to be an. enthusiastic listener. Cordially, Teresa. What a lovely email. That was a great email, Teresa. Thank. you very much for it. And now your mystery's solved, Chuck. That's right. We love emails that solve. mysteries that we were wondering about. So, if you've got a solution to one of. our mysteries, we would love to hear it. You can also write in for any other. reason. Just send your email to. stuffpodcast@iheartradio.com.

Stuff You Should Know is a production of. iHeartRadio. >> [music]. >> For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple. Podcasts, or wherever you listen to your. favorite [music] shows.