Daniel and Kelly’s Extraordinary Universe - How Does A Laser Work?

Episode Date: March 5, 2019

What makes a laser a laser? Pew Pew Pew!? Zap Zap Zap!? Learn more about your ad-choices at https://www.iheartpodcastnetwork.comSee omnystudio.com/listener for privacy information.

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No, I didn't audition. I haven't auditioned in like over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We'll talk about all that's viral and trending with a little bit of a little bit of. achievement and a whole lot of laughs. And of course, the great Vibras you've come to expect.

Listen to the new season of Dresses Come Again on the IHeartRadio app, Apple Podcasts, or wherever you get your podcast. Hey, Daniel, let's talk about acronyms. Acronyms are actually a really, really important part of science. Whenever you have a good idea, you have to come up with an acronym or something. It's not going to be catchy. Well, I heard there have been some pretty unfortunate acronyms in the history of science. There are. I Googled for worst acronyms ever, and I came up with some that you got to wonder, like,

people must have known what was going on, you know. So one of my favorites is phase one observing proposal system. So for those of you falling along at home, that's P-O-O-P-S. So, yeah, you can put that together yourself. But I heard that one, they actually grabbed the why from system. Like they consciously made the choice not to be called poops, but to be called poopsie. Well, there is one acronym that's a famous acronym for a physics topic, but I think we think maybe most people don't even know it's an acronym.

Yeah, and maybe that means it's really successful, right, because it's become a word in its own right. People actually use the word. Yeah, and that word is laser. So do you know what it stands for, Jorge? Don't look it up. Do you know what it stands for? Ooh, test.

NerdCredit test. I do. It stands for light amplification through stimulated emission radiation. Bing, we have a winner, folks. Give him a laser. But I heard that the acronym could have been different. It could have been light oscillation by stimulated emission radiation. That's right.

And I don't think that one would have caught on. quite as well. That would be L-O-S-E-R. That has some obvious disadvantages. Yeah, you don't want to be a loser, scientist. That would be, that would be too obvious. I loosed. Too obvious. Jorge. And I'm Daniel. And welcome to our podcast, Daniel and Jorge. Explain the universe. In which we talk about all kinds of cool things about the universe. Yeah. And we take the universe

apart. We disassemble its acronyms and we tell you what it actually means. Yeah, all the cool things you see in science fiction movies, books, laser guns, stuff like that. We break it down and make sense of it for you. So if you have ideas for what you'd like us to talk about, send them in to feedback at Daniel and Jorge.com. We love hearing your topic suggestions. Today on the program, we're going to be talking about lasers. Lasers. How does a laser work? What is a laser? Who came up with a laser? Where can I get my laser death ray? These are important questions. How can I make it my living to

laze about? You're a cartoonist. You're already lazery. Oh. By which I mean you are brilliant and cutting. That's right. And very focused. Very focused. Exactly. So, yeah, lasers are awesome.

Everyone knows what a laser is. My kids know what lasers are. Yeah, I mean, they're in science fiction everywhere. People have laser pens, right? Lasers, you probably have dozens of lasers in your house, right? Lasers used for everything. Yeah, they're in our everyday lives. Like, every time you go buy something at a store,

assuming you still go to a physical store but if they scan your product in they're using a laser that's right and if you still have a CD player that thing is read by a laser a CD what you're too young to understand these things

Jorge for those of you under 40 we used to store music on these shiny little discs yeah they use lasers so they were literally everywhere I mean there are optical drives right anything that reads a disc

so if you pop in a disc to your PlayStation that's using a laser in there. That's right. And lasers have an enormous variety of applications, you know, from tiny laser pointers to world-sized lasers that people are experimenting with to try to deflect asteroids that might blow up the Earth. Yeah, like in the Dead Star and in Star Wars, right? That's right. That's fiction, of course, but the group building a laser to deflect asteroids, that's real. They might save the planet. They might save the planet, exactly. So lasers are everywhere. There are definitely an important. part of our culture and of our technology and of everything you do. But the question we had was, how do they do what they do?

What does it mean to lays? How do you build a laser? Could you assemble one from the stuff in your kitchen? Yeah. Can you shoot it in the movies, like to destroy other spaceships? That's right. Do they really make the pew, pew, pew, pew sound? That's the question I want to know the answer to it.

What sound does a laser make? Is it like, puk, or fjoo, or... It's definitely one of those. How good, I hit it on my first three tries. But we were wondering, how many people out there know what a laser is and how it works? I walked around on campus and I asked people, do you know how a laser works? Those of you listening, think about it for a second. Here's what people had to say.

Heat. I'm absolutely not it. Sorry. Focus light. Light gets multiplied. and focused. Okay, cool. By light. All right, I guess not a lot of deep knowledge about lasers out there.

I had the impression people think lasers are like, you have a light bulb, and then maybe you have a lens to focus it, and that's your laser. I like the person who said, how do lasers work by light? Technically, you're right. You can't go wrong with that answer. That's right, yeah. Go with a very, very general answer. How does this work?

Physics. You can just say physics to any question. people really even math can I say how does math work no but that's not a topic for our podcast right because math is outside the universe beyond the scope of this podcast that's right maybe it's the only thing more fundamental than physics is math maybe I like how you say maybe is there is there anything else maybe philosophy I guess philosophy and math you know down there at the at the down in the dirt and the the the roots of human intellectual exploration Yeah. So lasers are pretty interesting, right? They have an interesting history. Like, apparently, historians don't really know who invented the laser, or they haven't settled on who invented the laser.

That's right. And I heard that one really important science historian actually wrote a poem about it once. Oh, really? Is that true? Yeah, his name is, hold on, I have it here. Let me check my name is Jorge Cham. Oh, yeah, that comic laureate of the Internet. Should we read the poem? Sure, go for it. I'm not sure if this is supposed to be set to music or rhyme. Yeah, it's supposed to be set to laser music.

So think 80s here, and then go for it. So I wrote this when the laser turned 50, about eight years ago, was the anniversary of the laser. I'll read it and you make the pew-poo sounds, right? The laser turns 50 this week, an important event in history. But who developed this amazing technique? That's still kind of a mystery. Was it Ted Maimon who built the first laser?

Or was it Townsend Shacklow who wrote the seminal paper? And it goes on like that. Several beautifully crafted verses. Oh, thanks. Yeah, it was, you know what happened? I was in Ottawa. And I went to visit, they have a laser institute at one of the universities. there and they explained to me that the anniversary of the laser was coming up and so they

explained to me how the laser works and in fact i think that's kind of related to how you and i started working together right yeah you just reminded me of this today apparently your comic about the laser is one of the ones that i read and and induced me to write you an email so yeah the history is kind of funny because the noble prize for the laser the first prototype for the laser and the first paper about the laser are all credited to different people. Like, nobody knows who invented this, really. Yeah, it might have been one of these things where, like, an idea whose time has just come, you know, we're on the cusp is sort of the next thing to happen, and a few people

contribute bits and pieces here, and some other person puts these things together first there, and it's a bit of a mess, yeah, it's a bit of a mess. I think it's fascinating also how important it is to assign credit for things. Like, we have the laser, it's awesome. are people just fighting about the money like who earns a penny every time they make a laser pointer? Or is it about like the credit in scientific history?

Right. You know, it's interesting to me how long and nasty this battle is. You mean you wouldn't fight to have that in your tombstone? Daniel Weissan invented the laser. Who wouldn't? Oh, I'm definitely putting that on my tombstone, true or not. I mean, you can put anything you want on your tombstone.

Nobody fact checks tombstones, do they? It's like fake news applied to tombstones. Fake advertising. Oh, I'm taking credit for all sorts of stuff in my tombstone. Well, let's get into it. What, Daniel, is a laser? Right. So a laser is different from a flashlight, right?

It's not just a flashlight with a lens, okay? A laser is something that produces a bunch of light, usually of the same color. So like a bunch of photons of the same energy. And they should all be going in the same direction, right? So they're perfectly parallel, meaning if they're, like, you know, a tiny distance apart, now, then 100 meters away or a kilometer away or a million miles away, they'll still be the same distance apart. Perfectly parallel. Perfectly parallel. Photons, right?

Yeah, exactly. So photons usually have the same color, shot perfectly parallel, and also wiggling the same way, right? Remember the photons are waves, and they're like all other particles. They're governed by their wave equation. and waves wiggle, right? They go up and they go down. They go up and they go down. And if you have two waves,

if they're wiggling in opposite directions, one wiggles up and the other one wiggles down, then they can cancel each other out, right? So we want our photons all wiggling in the same way, so they all sort of push together. It's like folks on a boat rowing at the same time. They all push together for constructive interference to make it stronger.

When they hit something at the end, you want them to be perfectly synchronized, otherwise they might cancel each other out. when they hit something. Yeah, that's right. Or they might, you know, cancel each other out part of the way. You know, these things, these interference effects depend on the phase. And so, yeah, you want them all pushing in the same direction at the same time.

And so that's what a laser produces, right? That's what it means to be a laser. And that's an important distinction for people to understand. That's not just like a powerful flashlight or a flashlight that somebody's put a lens in front of. It's really a very different kind of source of light. It's not just a really bright light. It's like a perfectly ordered, perfectly parallel beams of light. That's right.

And there's two kinds of lasers. One kind is the kind we're talking about where all the photons have the same color. So it's monochromatic, right? It's a single color of light. All the photons have the same energy, the same color. That's the kind that you make to produce beams. You can also produce laser pulses, right? These are short bursts.

And those require having lots of different colors so that you add up and cancel out in just the right way to have a localized burst. You can add up all the different wiggles together to make the burst of any shape you want. Right, and that's different than a flashlight because a flashlight is just pumping out photons with all kinds of colors and all kinds of phases, and they're all out of sync with each other, all these photons. That's right.

And also they go in all different directions, right? A flashlight usually has like a tungsten filament bulb or something, right? And that's just glowing and it's sending light in every direction. Right. And even if you have it, you know, coming out of the front, so it's a little bit shaped. You can take, for example, a flashlight, and you can point it at the moon, right?

And as you get further away from the source of the light, the size of the beam grows, right? Flashlight makes a cone, and that cone grows with distance. So you can point it at the moon, and you basically cover the whole moon with your flashlight, right? Because by the time you get to the distance of the moon, the cone is huge. Even if you focus it with, like, a lens and try to get them parallel,

they won't be perfectly parallel. Exactly, right? There's always going to be some spread there. Whereas with a laser, if you take a laser and you point it at the moon, if it's a good laser, when it gets there, the beam should have the same width as when it left. So that's why lasers are powerful, right? Because with just a few photons, they can go a great distance together,

and so they can transmit that information. But they're also kind of in sync, so they can deliver all that power. when they get there. That's right. And that example about a laser to the moon is not just like a made-up example. I don't know if you know, but the astronauts who visited the moon left mirrors on the surface of the moon so that we can bounce lasers off of them and use that to measure the distance

from the Earth to the moon. I think that's pretty cool. The Earth's biggest selfie. You can take a selfie by shooting a laser at the moon. That's right. even though this was decades before the concept of selfies, it was prescient that way, right? They were forward-looking.

NASA is always looking into the future. NASA invented the selfie. We just gave credit to them. They can put it on their tombstone. I think actually the first selfie comes from decades and decades before that. But, yeah, the first astronomical selfie, for sure. The first laser selfie. That's right.

Okay, so that's what a laser is. It's like something that makes light, that shoots light, that's perfectly in sync and perfectly parallel. And that's really powerful. Okay. So why is it called a laser? Like, what does that acronym mean? Light amplified by stimulated emission radiation.

That's right. Let's break that down, right? The first one is just light. Okay, so photons are light. That's obvious. That's the L and laser. The last one, the L and Lays. The last one is radiation, right?

and radiation in this case also just means light I think that's because they didn't want to call it a laizal right that would have been more awkward or an azer or an azer or an acer so both of those words light and radiation just refer to the photons

right okay so it's something that makes light something that makes light and it makes it in this special way using this process called stimulated emission okay and that's the really the guts of the laser that's what's going on inside is that it's a system that creates this stimulated emission so we should dig into that the a in laser means amplified meaning you're not just making that you're sort of amplifying it somehow that's right the basic principle of the laser is you start with

one photon of the color that you want you know and you amplify it you use that to use the system to multiply you say I want to start with one photon then you create a chain reaction that gives you 10 photons and then 100 photons and then 1,000 photons, et cetera, et cetera, grows exponentially until you have a very, very intense beam of photons all the same kind. And the key is the stimulated emission. That's the thing that basically copies the photon. It says, if you have one of the right wavelength or all the right attributes, then I can

make more for you. That's this process called stimulated emission. Okay, let's get stimulated by stimulated emission. But first, let's take a quick break. Hello, it's Honey German, and my podcast, Grazacus come again, is back. This season, we're going even deeper into the world of music and entertainment with raw and honest conversations with some of your favorite Latin artists and celebrities.

You didn't have to audition? No, I didn't audition. I haven't audition in, like, over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We've got some of the biggest actors, musicians, content creators, and culture shifters sharing their real.

stories of failure and success. You were destined to be a start. We talk all about what's viral and trending with a little bit of chisement, a lot of laughs, and those amazing Vibras you've come to expect. And of course, we'll explore deeper topics dealing with identity, struggles, and all the issues affecting our Latin community.

You feel like you get a little whitewash because you have to do the code switching? I won't say whitewash because at the end of the day, you know what I'm me? Yeah. But the whole pretending and cold. You know, it takes a toll on you. Listen to the new season of Grasas Has Come Again as part of my Cultura podcast network

on the IHartRadio app, Apple Podcasts, or wherever you get your podcast. A foot washed up a shoe with some bones in it. They had no idea who it was. Most everything was burned up pretty good from the fire that not a whole lot was salvageable. These are the coldest of cold cases, but everything is about to change. Every case that is a cold case that has DNA right now. in a backlog will be identified in our lifetime. A small lab in Texas is cracking the code on DNA.

Using new scientific tools, they're finding clues in evidence so tiny you might just miss it. He never thought he was going to get caught, and I just looked at my computer screen. I was just like, ah, gotcha. On America's Crime Lab, we'll learn about victims and survivors, and you'll meet the team behind the scenes at Othrum, the Houston Lab that takes on the most hopeless cases.

cases to finally solve the unsolvable. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. I'm Dr. Joy Harden Bradford. And in session 421 of therapy for black girls, I sit down with Dr. Othia and Billy Shaka to explore how our hair connects to our identity, mental health, and the ways we heal. Because I think hair is a complex language system, right? In terms of it can tell how old you are.

your marital status, where you're from, you're a spiritual belief. But I think with social media, there's like a hyper fixation and observation of our hair, right? That this is sometimes the first thing someone sees when we make a post or a reel. It's how our hair is styled. We talk about the important role hairstylists play in our community, the pressure to always look put together, and how breaking up with perfection can actually free us. Plus, if you're someone who gets anxious about flying,

Don't miss session 418 with Dr. Angela Neil Barnett, where we dive into managing flight anxiety. Listen to Therapy for Black Girls on the IHeart Radio app, Apple Podcasts, or wherever you get your podcast. Okay, so a laser is something that makes light that's all the same color, the same wavelength, the same direction, the same. a wiggle, and it's all done by something called stimulated emission. What does that mean? Right. So the thing that's doing the emission is just an atom. And so you have some medium in your laser. Maybe it's a crystal, maybe it's a gas, it doesn't really matter, but it's a bunch of atoms.

And atoms can emit light, right? Any atom. Any atom can emit light, right? You get things hot and they glow, right? That's something emitting light. So if you pump energy into some material, right, It'll absorb that energy, it'll bring it internally into itself. But then sometimes it gets rid of that energy. That's called emission, and it turns that energy into light.

And the way that it does that is it has inside of it has these electrons, right? So every atom has electrons whizzing around it. And those electrons have a few certain orbits that they can use around the atom. It's like a bunch of different energy levels. Electrons can't just have any random energy level around an atom based on the shape of the atom and the configuration of the protons, et cetera, there's a few places the electrons are allowed to live. So they're called energy levels.

And you can imagine sort of a ladder of these energy levels. And that's kind of related to the wave nature of electrons, right? Because they're waves, they can only fit in so many ways around the atom, right? It's sort of related to that, right? It's very closely related, yeah. The reason that there are discrete energy levels, right, quantized energy levels, is precisely because of those waves. and the way the waves fit together around the atom.

So a simple way to think about it is when the electron goes around the atom, it's going to do its wiggling, and you want it to build on itself. You don't want it to cancel itself out. And so when it comes around one orbit, you need to be in the same place in its wiggle. Either it's wiggling up or it's wiggling down.

It has to fit a very specific number of wiggles in an orbit. It can't just do like three and a half. That's right. It has to wiggle once or twice or three. three times, right? If it wiggles one and a half times, then it's going to get out of sync with itself and eventually cancel itself out. So those are not stable solutions. You can't have an electron hanging out and wiggling one and a half times around the atom. So each of those is a different level. It's not like the Earth going around the sun. Like if something moves us a little bit,

our orbit will increase a little bit. That's not how electrons work. They have very specific orbits that can fit around the nucleus of the atom. Yeah, that's actually a really interesting deep question, is the Earth's orbit quantized, right? Are there an infinite number of orbits? That's not a one with a simple answer. If gravity is not quantum mechanical, then you're right. There's an infinite number of orbits the Earth can take. However, if the gravity is quantized, then you're wrong, and there are energy levels around the sun. But those energy levels would be so tiny, we could probably not even see them. Anyway. That might be a subject of a different podcast. Yeah, exactly. Yeah. So the energy levels.

So the electron has these energy levels. It has on these ladder. This ladder can go up and it can go down. Yeah, people use the ladder analogy, right? Like electrons can be here or it can go up a level or another level, right? It's like very discrete steps. And just like with the ladder, what happens when you go up a level? It takes some energy to do that, right?

You have to put some energy into your thigh muscle to push you up. And then you're storing more energy, right? You have more gravitational energy because you're higher up. The same thing happens with the electron. How does it go up a level? it needs to get energy from somewhere, right? It needs to get heated up or absorb some light or something. So it can go up a level, right?

And then it can go down a level. And what happens when it goes down a level? Well, the energy level it was at is fixed, and the energy level it's going to is fixed. So the energy difference between them is fixed, meaning every atom has the same levels. And if electrons jump down from one level to the lower one, then they're going to release a photon whose energy is exactly the

difference between those two levels, right? Conservation of energy. So the electron loses energy, goes down a level, and it gives off that missing, that extra energy in terms of a photon. Okay, so the electron goes down a level, it'll shoot out a photon with that energy that it doesn't need anymore. That's right, exactly. So how do you get a bunch of photons of all the same color in the same direction? Well, you get a bunch of atoms, you get them all to have their electrons up one level, right? You heat them up, or you pump some energy into them somehow. Right. And then you get them to come down all about the same time. You get them excited. You get them excited, right? And then you get them the big

letdown. Yay! Oh! And it's when they get the letdown, that's when they give off a photon. Each one will give off the same color photon. The same energy. The color of the photon is determined exactly by its energy, which is determined by its wavelength, right? Those things are all connected. Right. But they don't, in a laser, they don't all give them out at the same time. It's kind of like how you said earlier, you want to cause a chain reaction

that will make all the atoms in your laser shoot all these photons perfectly insane. Exactly. So that chain reaction is key. And you can have an atom and you can give it energy so the electron goes up one level. And then it's happy to just hang out there for a while, right? But what happens when another photon of just the right energy level comes by?

Like, if you're an electron, you're an excited state and there's like a ladder, the latter step, ladder step below you, or you could go down, if a photon comes by of just that right energy level, it has exactly the energy that's between you and that lower level, then you're more likely to emit. You get pushed sort of out of that energy level. And the reason is that that photon changes the way the environment works, right? Photons are electromagnetic waves, so it creates a little electromagnetic field there that makes

what you were doing a little less stable. So it sort of pushes you out of that state down to a lower state. and you end up emitting another photon. So the bottom line is, if you're capable of emitting that photon, and one photon just like that comes by, then you're going to give it up and emit that photon. And that's why it's called stimulated emission, right? Like, if you're an excited atom,

you could just spontaneously have your electron drop and emit a photon. That's called spontaneous emission, yeah. But stimulated emission is when you're excited and you get hit by another photon, and that causes you, to drop a level and emit another photon. Yeah, it's sort of like peer pressure. And you're like, hey, everybody's emitting that red photon.

I got one. I could emit one. I could, yeah. Yeah, I could, and so I will. This is the right time, you know? And so that's what the stimulated part is, right? This is not nocturnal emissions, people. We're talking about photons stimulating electrons into emitting more photons. What's the acronym for that one?

Liener. So to review, right, you get some material. You've got to pump it with energy. There's not free energy, right? You've got to pump it with energy somehow. You've got to get the atoms excited in your media, in your, like, block of stuff. Yeah, it's like, you know, you're a comedy routine. You need somebody to go out there and warm up the crowd, right?

So first you warm up the crowd. It's called population inversion. Maybe you've heard that phrase. You buy everyone a beer. That's right. we've discovered alcohol makes people laugh at your jokes more and so the physics equivalent for lasers is you pump the room with energy

and you get all those electrons up at that level and then one of them will pop right and that will cause a chain reaction having one photon around will make all these other atoms which are holding that photon inside them basically or burst in and get rid of it they'll start emitting and then more and more will emit But they have to get hit by a photon for them to release a photon, right?

Like, it doesn't just... Yeah. It's not because your neighbor shot out a photon that you shoot out a photon. It's like you have to get hit by a photon for you to get stimulated. Yeah, you don't have to absorb it, but having the photon nearby close enough to interact with the atom will change the electromagnetic vicinity, essentially, and cause it to do that. And that's why usually you also put this block of atoms in a resonant cavity. Basically, you put two mirrors on either side.

so that you capture the photons and you sort of bounce them around inside. It's the same reason why you have like walls in your oven, right? You want to reflect the energy back so that it builds on itself. Right. But that whole process I heard is still even a mystery for physicists. Like why exactly does a stimulated atom shoot out a photon that's exactly exactly like the one that just went by closely or that hit it? Why does it create a photon that's exactly identical to the one?

that it saw with the same like wiggle in the same timing in this exact same direction that's still kind of a mystery right well I think there's some quantum mechanical arguments that suggested I think there's a lot of the details are not perfectly understood but you know the

photon creates destabilizes the atom a tiny bit right and so we can understand that's something called Fermi's golden rule which tells us about how things like to decay and so having that photon around definitely helps us understand understand how the electron would be more likely to jump down. But, yeah, why it comes out in exactly the same phase, for example?

I think it's more likely to, but not guaranteed. So I think there definitely are some open questions there. Before we keep going, let's take a short break. Hola, it's HoneyGerman. And my podcast, Grasias Come Again, is back. This season, we're going even deeper into the world of music and entertainment With raw and honest conversations with some of your favorite Latin artists and celebrities. You didn't have to audition?

No, I didn't audition. I haven't audition in like over 25 years. Oh, wow. That's a real G-talk right there. Oh, yeah. We've got some of the biggest actors, musicians, content creators, and culture shifters sharing their real stories of failure and success. You were destined to be a start.

We talk all about what's viral and trending with a little bit of chisement, a lot of laughs and those amazing vivas you've come to expect. And of course, we'll explore deeper topics dealing with identity, struggles, and all the issues affecting our Latin community. You feel like you get a little whitewash because you have to do the code switching? I won't say whitewash because at the end of the day, you know, I'm me. But the whole pretending and cold, you know, it takes a toll on you. Listen to the new season of Grasasasas Come Again as part of My Cultura Podcast Network

on the IHart Radio app, Apple Podcast, or wherever you get your podcast. A foot washed up. A shoe with some bones in it. They had no idea who it was. Most everything was burned up pretty good from the fire that not a whole lot was salvageable. These are the coldest of cold cases, but everything is about to change. Every case that is a cold case that has DNA. Right now in a backlog will be identified in our lifetime.

A small lab in Texas is cracking the code on DNA. Using new scientific tools, they're finding clues in evidence so tiny you might just miss it. He never thought he was going to get caught, and I just looked at my computer screen. I was just like, ah, gotcha. On America's Crime Lab, we'll learn about victims and survivors, and you'll meet the team behind the scenes at Othrum,

the Houston Lab that takes on the most hopeless cases to finally solve the unsolvable. Listen to America's Crime Lab on the IHeart Radio app, Apple Podcasts, or wherever you get your podcasts. I'm Dr. Joy Harden. Bradford. And in session 421 of therapy for black girls, I sit down with Dr. Afea and Billy Shaka to explore how our hair connects to our identity, mental health, and the ways we heal. Because I think hair is a complex language system, right? In terms of it can tell how old you are,

your marital status, where you're from, you're a spiritual belief. But I think with social media, there's like a hyperfixation and observation of our hair, right? That this is sometimes the first thing someone sees when we make a post or a reel. It's how our hair is styled. We talk about the important role hairstylists play in our communities, the pressure to always look put together, and how breaking

up with perfection can actually free us. Plus, if you're someone who gets anxious about flying, don't miss Session 418 with Dr. Angela Neil Barnett, where we dive into managing flight anxiety. Listen to therapy for black girls on the IHeart Radio app, Apple Podcast

or wherever you get your podcast. Okay, so that's the S-E-N-L-A-S-E-R. That's right. We covered all the letters. So it's light amplified by stimulated emission radiation. That's right. And so you have it in this box, and you have a resonant cavity. You have the mirrors, right, bounce it back and forth.

So the photons you emit, make more photons. to emit, and you know, you can have a little hole in the side so that some of them leak out, and that's basically your laser. That's how you produce it, right? But it can be a constant thing. You can be constantly pumping it with energy, pushing the electrons up, and then they come down, you get photon, you push them back up, right? So it can be a continual thing.

One of the most interesting lasers I ever saw was actually here on campus at UCI. There's a professor here Franklin Dollar, who does fusion research, and they're trying to create fusion by focusing a bunch of lasers all in the same place. And he had this amazing setup where he had a bunch of lasers all overlapping in his lab. And he created a ball of plasma that was just floating there in empty space. It was incredible. You can trap atoms with lasers, basically, right? You can do that.

But here he was just basically heating the air with a bunch of lasers. By pointing a bunch of lasers so they overlapped in one place in space, he heated up the air hot enough to ionize and create a floating ball of plasma. It was like looking at stable lightning. It was pretty incredible. But these mirrors are pretty cool because they're not just any mirrors that you put on both sides of your stimulated stuff.

It's like one of them has to be a one-way mirror. That's right. One of them is a regular mirror, but the other one is like a half-mirror, meaning that it reflects some of the light, but it also lets through some of the light, right? That's right. If both of them were perfect mirrors,

then you would never get anything out of your laser. They would all stay inside the cavity. so you have to have one of them be an imperfect mirror so that some of them leak out. Yeah, so that's kind of what the laser is. It's kind of like a light echo chamber, meaning you get all your atoms excited, and then you set one of them off,

and then that will, for example, go to the right, bounce off the mirror, go to the left, hit another atom, cause it to also emit an exact copy of that photon, hit the other mirror, then both of them come back to the stuff, and then they stimulate two other atoms and then that creates four photons and that just kind of builds and multiplies

within your echo chamber but because one of the mirrors is one way or semi-transparent that's where the laser shoots out, right? Yeah, yeah, exactly. Did I just make that up? You should be the physicist on this podcast, man. But I mean, that's an important part of it, right?

It's like you want to develop an echo chamber but you have to let some of the light out. That's right, yeah. If you don't let some of it out, then it's pretty quickly going to get overheated. You're going to laser your own laser. And for all of us who have ever built a Death Star, you know that you want it to blow up your enemies' bases. You don't want it to destroy your own. But then it's stimulating the stuff in between.

You can do that several ways. Like, your stuff can be a gas or it can be a crystal, too, right? That's right. And if you want a laser to give you light of a certain wavelength, like you want a red laser or a green laser or an x-ray laser or something, you have to find a material that has steps in the ladder, there are steps in their electron ladder that are just the right size, right? You can't just tune it up to anything you want, right? You can't say, I want photons of this frequency.

You have to find some material that has electricity. electrons that have an energy level that has just the right size. And that's why some of these things are easy and some of these things are hard. Like, x-ray lasers are really difficult to build. And they're really everywhere, right? Like I was thinking, like, if you have a mouse in your computer and it's an optical mouse, that has a little laser in it, right? That's right, yeah.

Yeah, lasers are everywhere. And it's amazing how influential they have become, you know. And if you look back at the history of the lasers, not only is it a big mess, Nobody can agree about who invented them. But in the early days, there was a lot of skepticism that it was even useful at all. Right. Some scientists thought it was impossible to make a laser, right? Yeah, it was Niels Bohr.

He tried to make an argument using the Heisenberg uncertainty principle. He was like, you can't have that many atoms in a specified state. He thought it would just be impossible. He thought quantum mechanics would make it not possible to make a laser. When, in fact, you need quantum mechanics to build a laser, right? So it works the other direction. So sometimes famous scientists get it wrong. What was his argument for saying that it was impossible?

Well, you know, the Heisenberg uncertainty principle tells you that there's a certain, there's a limit to how much information you can have, right? And so he was arguing that having all these atoms in the same state, that you're specifying their energy too tightly, right? You can't, the same way the Heisenberg uncertainty principle tells you that you can't know the position and momentum of the particle at the same time, it also applies to the energy and timing information. And so a laser is trying to isolate a bunch of particles

to have the same energy all at the same time. And so he thought that that was going to violate the Heisenberg Uncertainty principle. But clearly, it doesn't. We shot that down with a laser. That's right. With our fully operational battle station. So it's interesting that there are all kinds

of different kinds of lasers, right? Like your mouse can have a laser. on it, but you can also use a laser to cut through steel, right? Like, what's the difference between the laser in my mouse and the laser that can cut through things? Nothing. Your mouse laser can cut through steel, Jorge. You just never try it.

No, the difference is just the intensity, right? The number of photons per second. Photons have energy, and when something is hit by a laser, they deposit their energy into whatever is hit by it. If it's not a very bright laser, then you're not, I don't have a whole lot of photons per second, then you're not depositing a lot of energy, right? So that's why you can shine, you know, a simple laser pointer and at your skin and it doesn't burn, right?

But if you had 10,000 laser pointers and you hit them all at the same place in your skin, that would be the same as having one really powerful laser. And yeah, you could cut a hole in yourself. So cutting lasers are just lasers with a higher intensity. And they can have more photons per second. And they do that. How do you create more intensity? Do you just pump the material more?

Or do you, do you know what I mean? Like, what's the difference? If I had the same material, how do I get more laser out of it? Yeah, you can pump the material more. You can have more material. You must also have to do with how you tune the one-wayness of your one-way mirror, right? How much, that's some fraction of the energy out per second. So there's probably lots of ways to do it.

Well, lasers are everywhere in our lives. But I heard somebody once told me that the biggest impact lasers have had is in science. helping us make instruments to measure things so that we can expand our knowledge about the universe. Yeah, lasers play a lot, a role everywhere. I thought you were going to say something about, like, laser lithography, like we can all design our own cutting board logos and have lasers burn them out.

Yeah, no, the maker movement is very grateful for lasers. But in the sense that, you know, like that's how we know, for example, or initially, that's how we kind of figured out, that the gravitational waves measurement, that depends on lasers, right? Absolutely, yeah, that uses two lasers in two different directions, and then you shoot them away, and they bounce back and use that as a way to measure the distance.

You count the number of wiggles the laser has had, yeah. Yeah, and that's how they do a lot of, like, DNA studies, and you can use lasers to figure out what materials are made out of. So it's kind of in scientific instrumentation, has been a huge, it's lasers have had had a huge impact, not just in like consumer products and death rays that were never made. It's in science, right? It's in, it's lasers have really kind of boosted and amplified what science can do.

That's right. Yeah, we're all emitting more papers, thanks to lasers. We're stimulated to emit more papers. Yeah, lasers also play a big role in fusion research, as we were mentioning earlier. You know, it's a powerful device, right? You have light with a specific wavelength. You can focus at a very specific spot. And so that's what scientists do.

They think, how can I answer this question with the tools I have? And that's a very specific tool. It's like a tiny little science scalpel, right? And that lets you sometimes cut problems open that you otherwise couldn't. Yeah. So the next time you are at the grocery store and are checking out and you hear that, beep, that's a laser at work. There's a little tiny...

Death ray. Death ray being used to scan your bananas. That's right. Your fully operational grocery store uses lasers. Yeah. All right. Well, I hope this discussion stimulated you and made you focus with laser precision.

And if you have any questions, you can emit them to us. We'd love to hear them. See you next time. If you still have a question after listening to all these explanations, please drop us a line. We'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge. That's one word.

Or email us at Feedback at Danielandhorpe.com. I'm Dr. Scott Barry Kaufman. host of the Psychology Podcast. Here's a clip from an upcoming conversation about how to be a better you. When you think about emotion regulation, we're not going to choose an adaptive strategy which is more effortful to use

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