How Lasers Work

Summary

Stuff You Should Know – "How Lasers Work"

Podcast: Stuff You Should Know
Hosts: Josh & Chuck
Release Date: February 12, 2026
Episode Theme:
A deep dive into the science, history, and practical applications of lasers. The hosts break down what lasers are, how they differ from ordinary light, the principles that make them work (including Einstein’s theoretical groundwork), the main types of lasers, and how they show up in everyday life and cutting-edge research. Their trademark blend of curiosity, friendship, and playful humor keeps the episode accessible and fun.

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Main Discussion Points & Insights

1. What Is a Laser? (03:05–04:21)

• Definition & Acronym:
  • LASER = Light Amplification by Stimulated Emission of Radiation.
  • The word is an acronym, much like SCUBA, and accurately describes the process.
  • Chuck: “Now that I know what a laser is and how it works, they kind of nailed it with that acronym.” (03:16)
• Lasers in Everyday Life:
  • Found everywhere—from supermarket UPC scanners (that “boop boop” noise) to entertainment and communications tech.
  • Most people are surrounded by invisible lasers daily.

2. Ordinary Light vs. Laser Light (04:51–10:17)

• Spectra and Wavelengths:
  • White light (like sunlight or a bulb) is a mix of many wavelengths/colors.
  • When a prism splits this, you see a spectrum—rainbow colors.
  • Josh: “Within all those nanometer wavelengths…there’s different kinds of yellow. There's a spectrum within the spectrum, I guess.” (06:03)
• Key Differences of Laser Light:
  1. Truly Monochromatic – Light is of a single specific wavelength.
     • “Rather than…570 and 590 for yellow, this is a 572 nanometer wavelength.” (08:35)
  2. Coherent – Photons (light particles) are perfectly in phase, peaks and troughs align.
     • “The photons are perfectly in phase with one another.” (09:09)
  3. Collimated – All light travels the exact same direction.
     • “They’re all traveling in the exact same direction.” (09:40)

3. Einstein’s Theoretical Groundwork (10:28–16:27)

• Planck-Einstein Relation:
  • Einstein proposed that light consists of discrete packets (photons) rather than a continuous wave.
  • Energy of photon = frequency × Planck’s constant (E = hf).
• Spontaneous and Stimulated Emission:
  • Atoms absorb energy, electrons jump up, then return to ground state and “poop out a photon” (prompting laughter from both hosts at this phrasing).
    • Chuck: “Earlier, when I was going over this in my head, I said, poops out a photon.” (13:25)
  • Einstein theorized you could stimulate the process deliberately: “With stimulated emission, you can use a photon to create another photon without losing the first photon.” (14:19)

4. From Theory to Reality – The Birth of the Laser (19:03–23:20)

• Charles Townes and the Maser (1950s):
  • Created a “maser” (Microwave Amplification by Stimulated Emission of Radiation) for microwaves. Later, he and others sought to apply the process to visible light.
• The First Laser (1960):
  • Built by Theodore Maiman using a ruby crystal as the gain medium.
  • The design: sapphire rod “doped” with chromium, surrounded by a flashlamp, reflective end caps.
  • Output: precise ruby-red laser at 694 nm.
    • Josh: “He used a pink ruby crystal as what’s called the gain medium...That’s where the atoms that you get excited are all stored.” (22:20)

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5. Five Main Types of Lasers (24:03–34:51)

a. Solid-State Lasers

• Use a solid medium (crystals/doped glass).
• Applications: tattoo and skin cancer removal.
• Doping with rare earth elements (chromium, neodymium, ytterbium) to tweak properties.
  • Josh: “They dope that...to generate photons really efficiently, and they’re gonna generate them in exactly the wavelength you want.” (25:00)

b. Gas Lasers

• Medium: gases like CO₂, argon, krypton.
• Applications: industrial welding, laser cutting, medical surgery (excimer lasers for UV, no heat).
• Pumped by electrical currents.

c. Fiber Lasers

• Use optical fibers as the gain medium, incredibly efficient (>50% electricity conversion).
• Backbone of modern fiber optic communications.
  • Josh: “If you have fiber Internet, you have a laser on one end...sending communications along a fiber optic cable.” (29:52)

d. Liquid (Dye) Lasers

• Use organic dyes in liquid form as the gain medium.
• Tunable over various wavelengths—versatile for specific uses.

e. Diode Lasers (Semiconductors)

• Produce light using electricity flowing across a junction between two materials.
• Most common (laser pointers, barcode scanners, cheap and not powerful).
• Discussion of safety issues: Shining pointers at pilots poses real dangers.
  • Josh: “You are blinding everybody in the cockpit...It’s a huge problem you really should not do.” (33:27–34:06)

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6. Amplifying Laser Power: Pulsed Lasers (34:51–37:15)

• Continuous vs. Pulsed:
  • Continuous: steady energy output.
  • Pulsed: Cut the beam to build up energy, then release it in bursts—produces far higher peak power.
  • Early pulsed lasers (1961): produced 100-nanosecond bursts, making beams up to 1000x stronger than the first continuous lasers.
  • Josh: “Your puny brain just sees it as one constant beam of light...we’re talking billions, trillionths, quadrillions quintillionths of a second.” (36:00)

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7. The World’s Most Powerful Lasers (39:12–40:47)

• ZEUS (Univ. of Michigan) and Vulcan (UK):
  • Pushing peak power to study black-hole-like environments and fusion.
  • Vulcan: as powerful as “500 million 40 watt light bulbs.” (39:33)
  • ZEUS: 3 petawatts in 25 quintillionths of a second—“100 times the total electrical output of the entire world in one quick burst.” (39:56)

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8. Lasers in Nuclear Fusion (40:47–42:10)

• Breakthrough at Lawrence Livermore (2022):
  • 192 lasers used to initiate fusion, achieving “net gain” (more energy out than in)—called “the Wright brothers moment” of fusion.
  • Chuck: “They focused those lasers at a capsule the size of a peppercorn, and that did it.” (41:51)
  • If scalable, this could change energy forever.

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9. Real World Applications (42:10–46:32)

Everyday Uses

• Barcodes, CD/DVD players, fiber optics—“Lasers are everywhere.”
• Anything that can absorb/bounce light could use lasers.

Medical Industry

• Surgical Lasers: Precision cutting, cauterization, self-sterilizing, reduced blood loss, quicker healing.
• Tiny Incisions: Brain tumor removal with a 5mm hole; discharge possible the next day. (43:11)
• Endoscopy: Lasers on fiber-optic tubes reach tough spots—tumor shrinking, ablation.
• LASIK Eye Surgery: Laser reshapes cornea for improved vision.
  • 90% achieve 20/20–20/40.
  • Josh: “It’s pretty safe and effective...I would do it, I’m just not there yet.” (46:09)

Weapons Development

• Military developing “directed energy systems” for drones, not personnel.
• Deployment on ships (turrets) and vehicles (e.g., Stryker vehicle)—with mixed efficacy due to the need for stability and focus.

Science & Research

• Laser Cooling/Particle Traps:
  • Lasers can “freeze” atoms in space using the recoil from emitted photons—enabling ultra-precise measurement (e.g., atomic clocks).
  • “It’s like a tractor beam holding it where you want it.” (48:49)
• Environmental Monitoring: Soil moisture, ice cap recession tracked from space via lasers.

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Notable Quotes & Memorable Moments

• Chuck: “Uncle Josh likes it. That’s like talk to the hand, but way better.” (02:59) — On a niece’s hand gesture, showing the hosts’ trademark wit.
• Josh: “Labseor doesn’t… have the same ring to it as laser. Throw me the labseor gun.” (03:51) — Goofing on acronyms.
• Chuck (regarding photons): “It poops out that photon.” (13:25) — Silly, memorable phrasing.
• Josh: “When you have subatomic particles, like an electron orbiting an atom...when a photon hits it, that electron goes up in energy, I think for like 100 nanoseconds, typically.” (12:16)
• Josh (on pulsed lasers): “Your puny brain just sees it as one constant beam of light.” (36:00)
• Josh: “If you have fiber Internet, you have a laser on one end…” (29:52)
• Chuck: “You’re blinding everybody in the cockpit. It’s a huge problem you really should not do.” (34:06) — On dangers of laser pointers.
• Josh: “Once we get to nuclear fusion, that’s going to change absolutely everything.” (42:07)
• Chuck: “Turns out using a laser to cut into the human body is way better than a scalpel.” (42:53)

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Timestamps for Key Segments

• 03:05–04:21 – What is a Laser? Acronym and real-life presence
• 04:51–10:17 – Ordinary vs. laser light, three key differences
• 10:28–16:27 – Einstein, Planck, and the physics behind lasers
• 19:03–23:20 – Charles Townes, masers, the first ruby laser
• 24:03–34:51 – Five main types of lasers and real-world examples
• 34:51–37:15 – Pulsed lasers, their power and mechanics
• 39:12–40:47 – ZEUS, Vulcan: mind-bogglingly powerful lasers
• 40:47–42:10 – Lasers making nuclear fusion possible
• 42:10–46:32 – Medical, industrial, communication, and research uses

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Language & Tone

The hosts keep it conversational, accessible, and witty—even when tackling technical subjects. Jokes about “pooping out photons,” playful banter, and self-deprecating humor (admitting past ignorance of how lasers actually work) are threaded throughout.

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Conclusion

Josh and Chuck deliver a thorough yet entertaining overview of lasers, from the physics basics to applications as mundane as supermarket scanners and as world-changing as nuclear fusion. You’ll leave knowing not only “how lasers work” but also how this technology has shaped, and will continue to shape, our daily lives and most ambitious scientific pursuits.

If you’ve ever taken a laser pointer for granted or had your mind blown by a fiber connection, this episode will make you appreciate the elegant, Einstein-paved science and engineering behind all those beams of light.

Transcript

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[Chuck]

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Stuff youf Should Know, a production of iHeartRadio.

[Josh]

And welcome to the podcast. I'm Josh. And there's Chuck. And Jerry's here too. And she was making too many laser noises, so we asked her to please go on. She did. And I assume she's still making laser noises. We just can't hear her right now.

[Chuck]

She had a little attitude about it too.

[Josh]

She did. I mean, I was really mean and curt, but she didn't have to be that way back.

[Chuck]

Yeah, this is a one way street, right?

[Josh]

It's my way or the highway.

[Chuck]

You know, it's about time we did an episode on lasers. This seems like something that we would have tackled in those first formative. In that first formative decade.

[Josh]

And I'm glad we didn't because I think it's good to still do, like a traditional, you know, how X works episode.

[Chuck]

We should do one on how X works.

[Josh]

It depends on what kind of X you're talking about.

[Chuck]

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.

[Josh]

And she just keeps getting cooler and cooler.

[Chuck]

She forgot that she lost that one along the way. I need to tell her to bring that back.

[Josh]

Yeah, that's a good one.

[Chuck]

Uncle Josh likes it.

[Josh]

That's like talk to the hand, but way better.

[Chuck]

Yeah, exactly.

[Josh]

All right, so we're talking lasers today, not necessarily X. Maybe we will do X someday. Let's find out.

[Chuck]

Okay.

[Josh]

And everybody knows what a laser is, right?

[Chuck]

Yeah, I mean, 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. 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.

[Josh]

They did. You can totally forgive them for the by and the of because that's a world class acronym.

[Chuck]

Yeah. That would be labseor if they included those lasers. So much cooler.

[Josh]

Labseor doesn't. Yeah. It doesn't have that same ring to.

[Chuck]

It as laser throw me the labseor gun.

[Josh]

That someone would say no. Yeah. So 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. But like a UPC code scanner at a supermarket checkout. They still have supermarkets, right?

[Chuck]

Yeah.

[Josh]

Oh, yeah, that's right. Everyone goes in and empties all of their bank accounts into them every week.

[Chuck]

Right. To get sustenance.

[Josh]

Well, when you check out, boop, boop, like that, that's actually a laser being triggered. You're 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?

[Chuck]

No. And it's really not that, like, hard to wrap your head around, actually. I was kind of dreading this. But it's. Dave did a great job with this article. Sort of like in the traditional sense, like he said.

[Josh]

Yeah.

[Chuck]

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.

[Josh]

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 is, as a lot of people know, all of the colors of the spectrum, the visible light spectrum, together coming together to form white light.

[Chuck]

That's right. Many different wavelengths. But just like elementary school science, when you get that prism and your little mind is blown, it still kind of blows my mind. You scatter that light into its different wavelengths.

[Josh]

So beautiful.

[Chuck]

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, you know, departing in what a laser ends up being.

[Josh]

Yeah, because so, for example, the yellow band, what we see is yellow in the visible spectrum, occupies the 570 nanometer to 590 nanometer range. Below that, I think you've got what, red, orange, something like that. ROY G. Biv. Yeah, I can't remember 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.

[Chuck]

Yeah. Spectrum within the Spectrum. Also a great album title.

[Josh]

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.

[Chuck]

Yeah, this 1960s for sure.

[Josh]

Yeah. A pyramid even is a prism.

[Chuck]

Yeah. With Isaac Hayes's head floating above it.

[Josh]

I'm describing the Dark side of the Moon album cover.

[Chuck]

I know, I was just kidding.

[Josh]

Okay, well, you were really throwing me off. That was some meta joking right there.

[Chuck]

I Have a great pressing of Dark side of the Moon, by the way.

[Josh]

You do?

[Chuck]

Yeah. You know, I had a record presser, a guy who does that for a living. I was hanging out with him in New York with our friend Joey Ciara 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 because it was well done. And I was like, yeah, and they're, you know, 180 gram. 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, oh, man, that's disappointing.

[Josh]

Yeah, I do like the heft of a 880 gram. Apparently.

[Chuck]

They said that's all just for you to make you think it is better because it's heavier.

[Josh]

It's heavier, so it's worth more.

[Chuck]

All right, so back to lasers. What you just described very well, by the way, was regular light 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 truly monochromatic. That beam of light that a laser is, or I guess, you know, produces. Well, no, that's what it is, is, is just a very. It's that single wavelength. Highly, highly concentrated.

[Josh]

Yeah. So rather than say a wavelength between 570 and 590 for being yellow, this is a 572 nanometer wavelength that is that specific yellow.

[Chuck]

That's right.

[Josh]

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 in you.

[Chuck]

That's right. 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, the photons are perfectly in phase with one another. So if you look at that wavelength, the peaks and the troughs are all perfectly in sync.

[Josh]

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.

[Chuck]

That's right.

[Josh]

And Then the last one is that they're collimated, meaning they're all traveling in the exact same direction.

[Chuck]

Yeah, I mean, that's, that's important. I mean, collimated's 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.

[Josh]

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, and they can be combined very, very tightly. And that's essentially what a laser does.

[Chuck]

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.

[Josh]

That's true.

[Chuck]

You can't 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.

[Josh]

Yeah. So back in 1905, most people were like lights, 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. Yeah, 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 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.

[Chuck]

Yeah, for sure. This is the Planck. Einstein, Einstein. What just happened? I was concentrating so heavily on not saying plank.

[Josh]

I've heard plank. I think that's how most people say it.

[Chuck]

Oh, I've always heard Planck.

[Josh]

Okay, I've heard both, but most of the people I've ever heard say plank. But I mean, I run in pretty low brow crowds.

[Chuck]

I think probably the correct is Planck. But most people do say plank. You're right.

[Josh]

I like the way that you said it the first time. The Planck, Einstein.

[Chuck]

No one says Einstein, though. Yeah. The Planck Einstein relation, which is the energy of each photon is equal to its frequency times Planck's constant E equals hf.

[Josh]

Yeah. And all Planck's constant is all it is. It's the smallest possible measurement of energy that 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. But because I know that photons interact with electrons, I'm just positive of it. And they were fig. That's pretty good. They were figuring out, or he was figuring out. 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. 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 100 nanoseconds, typically.

[Chuck]

Yeah.

[Josh]

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.

[Chuck]

You know what's funny?

[Josh]

What is?

[Chuck]

Earlier, when I was going over this in my head, I said, poop's out of photon.

[Josh]

Sure. I mean, you and I, we share a brain when it comes to toilet humor.

[Chuck]

Yeah, that's true. Yeah, 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 it gets heated up, you know, like literally heated up. 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.

[Josh]

Yeah.

[Chuck]

And this happens all the time, all over the place in nature. 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 stimulate it to do this. Maybe we can make this happen and control that emission.

[Josh]

Yeah. Because here's the thing, right? Like you say you have a photon that hits an atom and knocks an electron into the higher energy state, and then that electron poops out a photon. Well, that electron has just absorbed the photon Right. So another way of looking at it is the photon essentially goes into the electron and comes back out the other side, kind of. But there's only one photon ever. One gets absorbed, one's produced. What Einstein figured out is, 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, you could make a basket with your shirt and fill it with photons if you do it right.

[Chuck]

Yeah. I mean, he realized that photons like to hang out with one another, so it doesn't take a lot to get them, 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, 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, you're like halfway toward Lasertown, pretty much.

[Josh]

You can see the outskirts of town and the light shooting up in the sky.

[Chuck]

Yeah, you can.

[Josh]

So, yeah. So that stimulated emission. And 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, traveling 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.

[Chuck]

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?

[Josh]

That's right.

[Chuck]

Took a little while. So should we take a break?

[Josh]

Yeah, I feel like a break is imminent.

[Chuck]

All right, we'll be right back with more lasers.

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Make it quick, young man.

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[Chuck]

All right, so when we left, Einstein did some, some great work kind of laying the groundwork this theoretical foundation of a laser. And then he was like, guys, I like to think of things with my brain and say them out loud and write them on chalkboards. If you want to build this thing, fine, maybe slide me some cash, 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 he was doing research on microwave radiation. And he was trying to, he didn't know it yet, but he was halfway to Lasertown because he was trying to find ways to concentrate a beam of microwaves in this case.

[Josh]

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?

[Chuck]

Yeah. He built like a thing.

[Josh]

Yeah, he just. He used ammonia atoms. He put them in a sealed chamber, and he got them to essentially emit microwave radiation that he was able to 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 machine. We talked about this ahead and melted it. And Percy Spencer never forgave him because that was his favorite short sleeve, button down shirt.

[Chuck]

I think we talked about this. Did we do one of microwaves?

[Josh]

Yeah.

[Chuck]

Okay, well, that would be exactly where we talked about it then, probably.

[Josh]

Yeah. And they weren't colleagues. I just made that part up. But that was a. That was for you, buddy.

[Chuck]

Oh, no, wait. There was a chocolate thing, though. What? Right.

[Josh]

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. Yeah, it just brought Percy Spencer to mind.

[Chuck]

Yeah, I like it. So he literally called this amazer a microwave amplified stimulated emission of radiation. He teamed up with a guy, it was a colleague named Arthur Shawlow. 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, come on, just get there.

[Josh]

I think it was Theodore Miman. I like to call him my man, who actually came up with the. The laser. He built the first functional laser in.

[Chuck]

1960 and came up with a name.

[Josh]

I think he did okay up to this point. They were. They were all theoretical. And my man was the first one to actually build one. And he used a ruby crystal, which at the time, I think had already been dismissed. People were like, you can't use that 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.

[Chuck]

Yeah, that's like the material. Lasing material that you would use.

[Josh]

Exactly. That's where the atoms that you get excited are all stored.

[Chuck]

Yeah. So he surrounded that crystal with a. With A flash. It was a coil shaped flash bulb. So that's gonna be the thing that, you know, the heat or whatever or the light that stimulates the initial reactions.

[Josh]

The pump. Sure.

[Chuck]

And then the two ends of that crystal were painted reflective silver. So everything is sort of 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 doing something here, guys.

[Josh]

And yeah, all of these photons came out at 694 nanometers, which I guess is the precise wavelength of ruby red.

[Chuck]

Yeah, I guess so.

[Josh]

And he showed that, like, there, there, here's a laser. Check it out. Let me see your face. Basically, I think, was how he showed it off.

[Chuck]

Right.

[Josh]

He would just wave it in people's faces.

[Chuck]

That's why he's my man.

[Josh]

So that was it. I mean, that was the first laser. And it was, 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.

[Chuck]

Yeah, it's.

[Josh]

It's more complicated than a laser by far.

[Chuck]

I hated that one.

[Josh]

I did too.

[Chuck]

That was a long, long time ago.

[Josh]

I remember we picked it, we started researching. I was like, this sucks. Wait, why am I not understanding this? It was just so complex. Let's never talk about it again.

[Chuck]

I think we just wanted the explanation to be like, blow in tube, tube smells beer.

[Josh]

Exactly. And just make a bunch of like, drunk jokes.

[Chuck]

Exactly. All right, so that was the first laser, like you said. He used that ruby to begin with. But there are all sorts of gain mediums. There can be liquids, there can be gases. And we should probably go over the five main types of laser now, starting with, like, if you've ever been for tattoo removal or 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. With a gain medium. Like. Well, they're all rare earth elements, like chromium or something like that. Neodymium. Is that one?

[Josh]

Yeah. There's also. Man, I even looked it up. Ytterbium. Ytterbium.

[Chuck]

Ytterbium I bet is right. That looks funny.

[Josh]

It is. It's 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 gonna generate them in exactly the wavelength that you want. That's a solid state laser. It follows in the tradition of that original My man's laser from 1960.

[Chuck]

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. Patrick Mahomes is one of them. And every time she hears of him or anything, she just goes, mahomes.

[Josh]

Very nice.

[Chuck]

Sort of like my man.

[Josh]

Oh, no, I'm with you. That's a great way to say it. Guy's nice.

[Chuck]

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 this crystal with this doping agent, because we just think it sounds awesome. It's all highly specific to what you want to end up using it for.

[Josh]

Yeah, like, even like tattoo removal, you said, which I'm in the process of. I'm getting toward the end there, buddy.

[Chuck]

How's it looking? Pretty, pretty gone.

[Josh]

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.

[Chuck]

I took the other tack. As you have seen recently when we were on tour, I had a probably 2 inch by 2 inch tattoo that I covered with half of an arm sleeve.

[Josh]

I didn't see it. You haven't shown it to me.

[Chuck]

Oh. How was. Was I always in long sleeves?

[Josh]

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.

[Chuck]

Well, I'll. I'll take my shirt off in front of you soon.

[Josh]

Okay. But even with the tattoo removal ones, they have different types of solid state lasers. 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.

[Chuck]

Yeah, yeah.

[Josh]

So it is extremely specific.

[Chuck]

All right, well, can we move on to gas lasers?

[Josh]

I think it's time. Yeah.

[Chuck]

So obviously they're going to use gas 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. Later, obviously, 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.

[Josh]

Yeah, it gets them excited. There's all sorts of stuff you can use with gas lasers, but probably one of the most famous one is using 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 an excimer laser. You can actually break the bonds that hold molecules together. You can alter cells, you can destroy tissue. But 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 a squamous cell or something.

[Chuck]

Yeah. Or if you've ever heard of something being laser cut, then it's probably going to be a gas laser doing that business.

[Josh]

Yeah. Hopefully that you didn't hear about that from a squamous cell being removed.

[Chuck]

Right.

[Josh]

There's also fiber lasers. These are very special lasers. I don't know how they found this out, but scientists concluded that the cloaks usually, or the textiles found with bog bodies, have some sort of magical properties that if you use them as a gain, they make really great lasers. Hence fiber lasers.

[Chuck]

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. And because they are used in conjunction with an actual cable, 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.

[Josh]

Yeah, that's pretty efficient. That's another way that lasers are part of your everyday life. If you have fiber Internet, like you have a laser on one end that your ISP is Using to send 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.

[Chuck]

Yeah, man, that breaks my brain like vinyl records does, you know.

[Josh]

Yeah. It's pretty cool though. And that's the thing. So it's just like when radio. 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. And apparently they're starting to look into this to. To transmit information between the earth and the moon.

[Chuck]

Oh boy.

[Josh]

So you'll just be able to. You'll have basically not even fiber optic Internet. You'll have laser Internet on the moon.

[Chuck]

Wow.

[Josh]

I think that's wow too.

[Chuck]

Yeah.

[Josh]

What about liquid lasers or dilators, 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.

[Chuck]

Oh, I fall victim again.

[Josh]

Did you. You thought that they used the cloaks from bog bodies for that?

[Chuck]

Man, I don't. All of this stuff is so brain breaking. Nothing would. You could say human feces and I'd be like, yeah, of course that'd be.

[Josh]

Man, that'd be gross. But I'll bet you could. I think you could use anything with atoms that's excitable to potentially make a laser.

[Chuck]

You've become such a good straight person that it's just hard to tell anymore.

[Josh]

It's hard to tell with you too.

[Chuck]

Hey, thanks.

[Josh]

Yeah, thank you.

[Chuck]

Liquid lasers or dye lasers. These are sort of brain breaking too. They use organic dyes as the gain medium, which is kind of crazy to think about. But each dye like will produce a different laser light because they're going to have, you know, because it's a color like a different wavelength.

[Josh]

Right.

[Chuck]

And these are really cool because you can actually tune them to a very. You can manipulate them and tune them within a very specific range for specific uses.

[Josh]

Yeah. So one laser can be used for all sorts of different things, which is I'm sure quite cost efficient.

[Chuck]

Yeah.

[Josh]

I think that's one of the downsides of solid state lasers. It's like one thing you can do with one laser.

[Chuck]

Yeah.

[Josh]

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.

[Chuck]

They should work on that.

[Josh]

They have to be, you know, like the cost of lasers have Come down tremendously. I'm sure we'll eventually get there.

[Chuck]

Yeah, just ask my cat. My cat's with an S. Well, let's talk about that.

[Josh]

We're kind of at that point. Do you play with your cats with laser pointers?

[Chuck]

No. I have, but they always get lost because they're always small.

[Josh]

Oh, gotcha. Gotcha. Well, that is actually a kind of laser. That's why they call them laser pointers. They're the weakest laser.

[Chuck]

Yeah.

[Josh]

But they use diodes, which are two different materials that, when you put them together with a place where they interface, creates an electron 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. 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.

[Chuck]

Yeah.

[Josh]

And I was looking into this because when I hear laser pointers, I think of jerks, like trying to shine it in the light of an airline pilot.

[Chuck]

Oh, sure.

[Josh]

That's a real problem, actually. I think it happens a couple thousand times a year in the US Alone.

[Chuck]

Yeah. Concerts, too. People do that stuff.

[Josh]

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 a huge problem that you really should not do.

[Chuck]

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, let's mess with that person.

[Josh]

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.

[Chuck]

Yeah, agreed. Well, that's a weak one, those diode lasers or semiconductor lasers. But since the very beginning, science has tried to make the more powerful lasers, and they have done a pretty great job at it. And we'll go over some of these. But you measure a laser by how quickly that laser is emitting the energy. So it's joules of energy emitted per second.

[Josh]

Right.

[Chuck]

They measure that in watts and 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.

[Josh]

Yeah. Pulsed lasers. Right. Because 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. 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, 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, trillionths, quadrillions quintillionths of a second how frequently the thing is pulsing.

[Chuck]

Yeah. It's incredible. I think they first demonstrated that in 1961 with that ruby laser, and I think they ended up with 100 nanosecond burst in 1961, which is pretty impressive.

[Josh]

Yeah, for sure. Because a nanosecond is a billionth of a second.

[Chuck]

Yeah. So in 1961, they were able to get that first laser by pulsing it up to 1000 times more powerful than my man's device.

[Josh]

Yeah. This was a year after he built that first laser, Right?

[Chuck]

Yeah.

[Josh]

So I think that was, what'd you say, 100 nanosecond bursts. I saw that. With the tech that they're using now, nanosecond pulses are called giant pulses.

[Chuck]

Yeah.

[Josh]

Seriously, that's what they consider them.

[Chuck]

Yeah. And those are quintillionths of a second, which is hard to even wrap your head around for.

[Josh]

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 like creating a ousand times or ten thousand times or however many times stronger beam just from backing it up in like one quintillionth of a second.

[Chuck]

Yeah, sure.

[Josh]

You want to take a break?

[Chuck]

Yeah, let's take a break and let's talk about just sort of real world uses and what's going on out there.

[Josh]

Okay.

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[Chuck]

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[Josh]

So, Chuck, there's some. 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, Zetawatt equivalent Ultra Short pulse laser system. And then there's one in the UK that's being built called the Vulcan laser.

[Chuck]

Yeah. And these. I mean, the one in the UK has a power of 500 million 40 watt light bulbs.

[Josh]

Well, 40 watt.

[Chuck]

Well, yeah, that's true. That's not much. And the Zeus can generate a pulse of light that's 25/ quintillionths of a second long. And so.

[Josh]

But wait, how much energy does it release?

[Chuck]

3 petawatts, baby. Which is 100 times the total electrical output of the entire world in one quick burst.

[Josh]

So these things are. They're like, they're so powerful and energetic that 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?

[Chuck]

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 it.

[Josh]

So.

[Chuck]

Yeah, so they can recreate like the energy and the inside of a star and find out the mysteries of the universe, basically.

[Josh]

Exactly. There's another thing you can use really, really powerful lasers for, and that's nucle 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 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 use 192 of these lasers to essentially create the world's first nuclear fusion reaction that produced more energy than was put in. There was a net gain.

[Chuck]

Yeah, they called that the Wright brothers moment. As far as lasers go.

[Josh]

Sure.

[Chuck]

Because you got a net gain for the first time. They focus those lasers at a capsule the size of a peppercorn, and that did it. And I bet that was a great day in that lab.

[Josh]

I'm sure. I mean, once we get to nuclear fusion, that's going to change absolutely everything.

[Chuck]

Yeah, for sure.

[Josh]

So you can use it 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. But they're like, when you start to look around, lasers are everywhere. Essentially. Anything you can bounce light off of or that you can. That will absorb light, you can use a laser for, for some application or other.

[Chuck]

Yeah, for sure. They're all over the medical industry in all kinds of ways. I think pretty early on, they Were like, hey, using a laser to cut into the human body is way better than a scalpel.

[Josh]

Sure.

[Chuck]

It's way more precise. There's less damage on the tissue. It kind of self cauterizes as it goes. So it's gonna be sterilizing the tissue that surrounds it. It's gonna be less blood loss. You're gonna heal up quicker. So that's. They're. I mean, scalpels are still around, but they, you know, lasers are the way to go.

[Josh]

I saw that there's a brain tumor laser procedure that uses a 5 millimeter 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.

[Chuck]

Yeah. 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.

[Josh]

The laser tumor.

[Chuck]

Yeah, the tiny hole in the skull.

[Josh]

We started watching it. I gave it another try. Yumi and I did. And it is pretty good and engrossing.

[Chuck]

Yeah. And gross.

[Josh]

It is.

[Chuck]

Yeah. And I figured out too, watching last night, I kind of forgot the reason why I was saying there's so much of like of Noah Wiley over explaining everything to all the younger doctors and residents is because it's a teaching hospital.

[Josh]

Yeah, there you go.

[Chuck]

Which is a great vehicle to explain whatever the heck is going on to the viewer at home, you know.

[Josh]

Yep. For sure.

[Chuck]

All right, so back to medicals, since we're talking about the Pit. If you ever had an endoscope, that's, you know when they put a long flexible tube down your throat a lot of times or up your nose, or who knows what holes they can put them into these days.

[Josh]

It depends. If it's a rubber hose, you know where that goes.

[Chuck]

That's right, Vinnie. 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.

[Josh]

Right. 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 aesthetic, dermatological applications.

[Chuck]

Yeah. Cosmetic stuff.

[Josh]

Yep. Tattoo removal, that kind of thing.

[Chuck]

Lasik. What about lasik?

[Josh]

Yeah, LASIK is a big one that has become vastly improved as lasers and robots have improved. I think it was first started. It first became approved in the US in 1999. And since then it's gotten really good. I think 90% of people who get LASIK have between 2020 and 2040 vision afterward. And it's like the pool of people who are 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 gonna. Lasik's gonna benefit, you know, you can have, like, pretty bad myopia and still benefit from it.

[Chuck]

Yeah. In this case, they used a laser to reshape the cornea. Didn't you debate LASIK at one point?

[Josh]

Yeah, I'm still thinking about it, but my vision, we're. We're basically at an age where 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.

[Chuck]

I think Emily has been debating it, too, a little bit lately. I'm not sure why.

[Josh]

I looked into it, and I was convinced, like, this is pretty safe and effective. And, yeah, I would do it. I'm just not there yet.

[Chuck]

I feel like when I've seen you lately, you're having trouble with that contact.

[Josh]

Lens because it's been wintertime and dry. It makes them, like. It makes it easier for it to fold over or something like that, pop out. Sucks.

[Chuck]

I'm sorry.

[Josh]

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.

[Chuck]

Yeah, they're called directed energy systems. Some of them attach to, like, a turret on a ship. Those seem to work pretty well for, like, you said, like, taking down a drone or something like that. They have others. I think the army has one, a 50 kilowatt 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 locked down. And they're like, hey, we're driving this thing around. It's not very accurate.

[Josh]

Right. And that's the Stryker armored fighting vehicle. Stryker with a Y. It's like they look to GI Joe stuff to. To come up with names for it, for sure. There's also. This one's pretty sweet, too. It's laser cooling. And there's also so many different applications. Like, you can. You can track Soil moisture from space to see how bad a drought is. You can 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, just amazingly cool.

[Chuck]

Yeah. No pun intended. Laser cooling. What they're doing is basically kind of freezing an atom or a molecule in place. It's also called a particle trap. And it's the same sort of physics of stimulated emission, but kind of in reverse.

[Josh]

Yeah. When 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.

[Chuck]

Yeah.

[Josh]

So they're essentially. They're just. It's like a tractor beam holding it where you want it.

[Chuck]

Yeah. It just slows it down such that it's basically stopped.

[Josh]

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, 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 reduced. 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.

[Chuck]

Yeah, for sure. I mean, it's easier to study something that's sitting still.

[Josh]

Exactly.

[Chuck]

Yeah.

[Josh]

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.

[Chuck]

That's the nerdiest sentence you've ever said.

[Josh]

Oh, come to think of it, you got anything else?

[Chuck]

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.

[Josh]

Agreed. Man. And since Chuck said old fashioned, he just accidentally triggered listener mail.

[Chuck]

I'm gonna call this an answer to a question. I love it when, when we put out a question, we get answered. We were talking about color psychology, and I wondered because I have a African American church around the corner for me. Oh yeah, purple actually. Yeah, purple. And we heard from a listener. Hey guys, I'm writing to share some insight regarding the morning colors 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.

[Josh]

Oh, neat.

[Chuck]

In some cases, all in attendance are encouraged to do so, while in others it's reserved for family members. Regarding the use of purple specifically, this color is typically associated with royalty in Jesus Christ. If you consistently see purple at the church, it may signify recognition of the deceased returning to God 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, Theresa. What a lovely email.

[Josh]

That was a great email, Teresa. Thank you very much for it. And now your mystery 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 stuffpodcastheartradio.com.

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[Chuck]

If you were to try two zero sugar colas with their labels removed and make the decision based on taste alone, do you know which one you'd choose?

[Josh]

Well, last year Pepsi put that to the test for tens of thousands of people across the country in a revival of the iconic Pepsi challenge. And the results were clear. 66% of people preferred the taste of Pepsi Zero Sugar over Coke Zero Sugar. That's the idea behind the Pepsi paradox, that when labels and bias disappear, people prefer the taste of Pepsi Zero sugar.

[Chuck]

It really makes you wonder, are you choosing the zero sugar cola that you actually prefer or are you settling for the label that you think you prefer?

[Josh]

Go out and try Pepsi Zero sugar. Today you deserve taste. You deserve Pepsi.

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[Chuck]

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This podcast is supported by FX's love story, John F. Kennedy Jr. And Carolyn Bessette, the new limited series from executive producer Ryan Murphy. It explores the complex courtship of the iconic couple considered to be American royalty, whose love story captured the attention of the nation. Their fairytale romance would unfold in front of the public eye, where their private love would also become a national obsession. FX's love story, John F. Kennedy Jr. And Carolyn Bessette premieres tonight on FX, Hulu and Hulu on Disney plus for bundle subscribers.

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