1 00:00:07,040 --> 00:00:10,399 Speaker 1: Hey, Daniel, let's talk about acronyms. Acronyms are actually a 2 00:00:10,520 --> 00:00:13,240 Speaker 1: really really important part of science. Whenever you have a 3 00:00:13,240 --> 00:00:15,880 Speaker 1: good idea, you have to come up with an acronym 4 00:00:15,960 --> 00:00:17,480 Speaker 1: or it's not going to be catchy. Well, I heard 5 00:00:17,480 --> 00:00:21,240 Speaker 1: there have been some pretty unfortunate acronyms in the history 6 00:00:21,280 --> 00:00:24,880 Speaker 1: of science. There are I googled for worst acronyms ever, 7 00:00:25,000 --> 00:00:27,200 Speaker 1: and I came up with some that you gotta wonder, 8 00:00:27,320 --> 00:00:31,240 Speaker 1: like people must have known what was going on, you know. So, um, 9 00:00:31,280 --> 00:00:37,479 Speaker 1: one of my favorites is Phase one Observing Proposal System. 10 00:00:37,479 --> 00:00:40,120 Speaker 1: So for those of you filing along at home, that's 11 00:00:40,240 --> 00:00:43,800 Speaker 1: p O O P S. So yeah, you can put 12 00:00:43,800 --> 00:00:47,279 Speaker 1: that together yourself. But but I heard that one day 13 00:00:47,320 --> 00:00:51,160 Speaker 1: actually grabbed the y from system, like they consciously made 14 00:00:51,159 --> 00:00:54,240 Speaker 1: the choice not to be called poops but to be 15 00:00:54,280 --> 00:00:58,480 Speaker 1: called poop. See, well, there is one acronym that's a 16 00:00:58,520 --> 00:01:02,000 Speaker 1: famous acronym for a physics topic. But I think we 17 00:01:02,120 --> 00:01:05,360 Speaker 1: think maybe most people don't even know it's an acronym. Yeah, 18 00:01:05,360 --> 00:01:08,000 Speaker 1: And maybe that means it's really successful, right, because it's 19 00:01:08,040 --> 00:01:10,600 Speaker 1: become a word in its own right. You know, people 20 00:01:10,640 --> 00:01:14,200 Speaker 1: actually use the word yeah, and that word is laser 21 00:01:14,440 --> 00:01:17,959 Speaker 1: camp to do. So, do you know what it stands for? Horror? Hey, 22 00:01:18,000 --> 00:01:19,480 Speaker 1: don't look it up. Do you know what it stands for? 23 00:01:20,360 --> 00:01:24,839 Speaker 1: Test NERD CREB test, I do it. It stands for 24 00:01:25,000 --> 00:01:32,360 Speaker 1: UM light amplification through stimulated emission radiation. Being we have 25 00:01:32,480 --> 00:01:35,080 Speaker 1: a winner, folks, give him a laser. But I heard 26 00:01:35,120 --> 00:01:37,640 Speaker 1: that the acron could have been different. It could have 27 00:01:37,680 --> 00:01:42,959 Speaker 1: been light oscillation by stimulated emission radiation. That's right, And 28 00:01:42,959 --> 00:01:44,800 Speaker 1: I don't think that one would have caught on quite 29 00:01:44,800 --> 00:01:47,240 Speaker 1: as well. That would be l o s E er 30 00:01:47,640 --> 00:01:50,800 Speaker 1: has some obvious disadvantages. You don't want to be a 31 00:01:50,800 --> 00:02:14,120 Speaker 1: loser scientist. That would be That would be obvious him 32 00:02:14,800 --> 00:02:17,600 Speaker 1: and I'm Daniel, and welcome to our podcast Daniel and 33 00:02:17,680 --> 00:02:21,840 Speaker 1: Jorge Explain the Universe, in which we talk about all 34 00:02:21,919 --> 00:02:24,280 Speaker 1: kinds of cool things about the universe. Yeah, and we 35 00:02:24,480 --> 00:02:27,320 Speaker 1: take the universe apart, we disassemble its acronyms, and we 36 00:02:27,360 --> 00:02:29,920 Speaker 1: tell you what it actually means. All the cool things 37 00:02:29,919 --> 00:02:33,840 Speaker 1: you see in science fiction movies, books, laser guns, stuff 38 00:02:33,880 --> 00:02:35,960 Speaker 1: like that. We break it down and make sense of 39 00:02:35,960 --> 00:02:38,240 Speaker 1: it for you. So, if you have ideas for what 40 00:02:38,320 --> 00:02:40,920 Speaker 1: you'd like us to talk about, send them into feedback 41 00:02:40,960 --> 00:02:44,200 Speaker 1: at Daniel and Jorge dot com. We love hearing your 42 00:02:44,200 --> 00:02:46,840 Speaker 1: topic suggestions. Today on the program, we're going to be 43 00:02:46,840 --> 00:02:56,920 Speaker 1: talking about lasers, lasers. How does a laser work? What 44 00:02:57,080 --> 00:02:59,680 Speaker 1: is a laser? Who came up with a laser? Where 45 00:02:59,680 --> 00:03:02,840 Speaker 1: can I at my laser death ray? These are important questions. 46 00:03:02,880 --> 00:03:04,720 Speaker 1: How can I make it my living to laz about? 47 00:03:06,960 --> 00:03:12,200 Speaker 1: Here a cartoonist, you're already laser by which I mean 48 00:03:12,240 --> 00:03:17,720 Speaker 1: you are brilliant and cutting. That's right, and very um focused, 49 00:03:18,600 --> 00:03:24,280 Speaker 1: very focused exactly. So, Yeah, lasers are. Lasers are awesome. 50 00:03:24,360 --> 00:03:26,799 Speaker 1: Everyone knows what a laser is. My kids know what 51 00:03:26,919 --> 00:03:31,160 Speaker 1: lasers are. Yeah, I mean they're they're in science fiction everywhere. Um, 52 00:03:31,320 --> 00:03:34,480 Speaker 1: people have laser pens, right, lasers there. You probably have 53 00:03:34,600 --> 00:03:38,320 Speaker 1: dozens of lasers in your house, right, Lasers used for everything? Yeah, 54 00:03:38,360 --> 00:03:41,200 Speaker 1: they're in our everyday lives. Like every time you go 55 00:03:41,360 --> 00:03:43,680 Speaker 1: buy something at a store. Assume you still go to 56 00:03:43,760 --> 00:03:47,080 Speaker 1: physical store. But if they scan your product in they're 57 00:03:47,160 --> 00:03:50,040 Speaker 1: using a laser, that's right. And if you still have 58 00:03:50,080 --> 00:03:52,400 Speaker 1: a CD player, that thing is read by a laser. 59 00:03:52,840 --> 00:03:56,440 Speaker 1: A CD what you're too young to understand those things? 60 00:03:56,480 --> 00:03:59,440 Speaker 1: For he For those of you under forty we used 61 00:03:59,440 --> 00:04:02,839 Speaker 1: to store music on these shiny little disks. Yeah, they'd 62 00:04:02,880 --> 00:04:06,680 Speaker 1: use lasers. So they were literally everywhere. I mean, there 63 00:04:06,680 --> 00:04:09,680 Speaker 1: are optical drives, right, anything that reads the disc. So 64 00:04:09,720 --> 00:04:12,000 Speaker 1: if you pop in a disk to your PlayStation, that's 65 00:04:12,080 --> 00:04:14,320 Speaker 1: using a laser in there, that's right. And lasers have 66 00:04:14,320 --> 00:04:17,560 Speaker 1: an enormous variety of applications, you know, from tiny laser 67 00:04:17,600 --> 00:04:22,240 Speaker 1: pointers to world size lasers that people are experimenting with 68 00:04:22,320 --> 00:04:26,200 Speaker 1: to try to deflect asteroids that might blow up the Earth. Yeah, 69 00:04:26,279 --> 00:04:29,680 Speaker 1: like in the Dead Star and in Star Wars, right, 70 00:04:29,880 --> 00:04:32,480 Speaker 1: that's right. Those that's the fiction, of course, But the 71 00:04:32,520 --> 00:04:36,640 Speaker 1: group building a laser to disflect asteroids, that's real. They 72 00:04:36,680 --> 00:04:39,440 Speaker 1: might save the planet. They might save the planet exactly. 73 00:04:39,680 --> 00:04:43,000 Speaker 1: So lasers are everywhere. They're definitely an important part of 74 00:04:43,000 --> 00:04:46,560 Speaker 1: our culture and of our technology and of everything you do. 75 00:04:47,080 --> 00:04:49,760 Speaker 1: But the question we had was how do they do 76 00:04:49,839 --> 00:04:52,320 Speaker 1: what they do? What does it mean to lazy? How 77 00:04:52,320 --> 00:04:55,120 Speaker 1: do you build a laser? Could you assemble one from 78 00:04:55,120 --> 00:04:57,520 Speaker 1: the stuff in your kitchen? Yeah? Can you shoot it 79 00:04:57,560 --> 00:05:00,680 Speaker 1: in the movies like to destroy other specihopes? That's right? 80 00:05:00,720 --> 00:05:04,080 Speaker 1: Do they really make the pew pew pew sound. That's 81 00:05:04,160 --> 00:05:05,880 Speaker 1: that's the question. I want to know the answer to 82 00:05:07,080 --> 00:05:09,520 Speaker 1: what sound does a laser make? Is it like pure 83 00:05:09,880 --> 00:05:16,279 Speaker 1: or it's definitely one of those? How good? I hit 84 00:05:16,360 --> 00:05:19,960 Speaker 1: it on my first three talk tries. But we were 85 00:05:20,000 --> 00:05:23,240 Speaker 1: wondering how many people out there know what a laser 86 00:05:23,680 --> 00:05:26,200 Speaker 1: is and how it works. I walked around on campus 87 00:05:26,200 --> 00:05:28,520 Speaker 1: and I asked people, do you know how a laser works? 88 00:05:28,680 --> 00:05:30,680 Speaker 1: Does of you listening think about it for a second. 89 00:05:31,920 --> 00:05:38,400 Speaker 1: Here's what people had to say, mate, Sorry, uh, focused light, 90 00:05:39,720 --> 00:05:46,280 Speaker 1: light gets multiplied and focused? Okay, cool light? All right. 91 00:05:46,440 --> 00:05:49,239 Speaker 1: I guess not a lot of deep knowledge about lasers 92 00:05:49,279 --> 00:05:52,000 Speaker 1: out there. I had the impression people think lasers are 93 00:05:52,040 --> 00:05:54,120 Speaker 1: like you have a light bulb and then maybe you 94 00:05:54,200 --> 00:05:56,440 Speaker 1: have a lens to focus it, and that's your laser. 95 00:05:57,080 --> 00:05:58,760 Speaker 1: I like the person who said, how did how do 96 00:05:58,839 --> 00:06:03,279 Speaker 1: lasers work? By light? Technically? You're right, you can go 97 00:06:03,360 --> 00:06:06,359 Speaker 1: wrong with that answer. That's right. Yeah, go with a 98 00:06:06,520 --> 00:06:09,760 Speaker 1: very very general answer, how does this work? Physics? Right? 99 00:06:09,760 --> 00:06:12,640 Speaker 1: You could just say physics to any question to ask people? Really, 100 00:06:12,680 --> 00:06:17,479 Speaker 1: even math? Can I say how does math work? No? 101 00:06:17,640 --> 00:06:20,719 Speaker 1: But that's not a topic for our podcast, right because 102 00:06:20,760 --> 00:06:24,479 Speaker 1: math is outside the universe. Beyond the scope of this podcast. 103 00:06:25,440 --> 00:06:28,320 Speaker 1: That's right. But maybe it's the only thing more fundamental 104 00:06:28,360 --> 00:06:31,520 Speaker 1: in physics is math. Maybe. I like how you say, maybe, 105 00:06:31,760 --> 00:06:34,400 Speaker 1: is there is there anything else? Maybe philosophy. I guess 106 00:06:34,480 --> 00:06:37,760 Speaker 1: philosophy and math, you know, down there at the at 107 00:06:37,760 --> 00:06:40,559 Speaker 1: the down in the dirt and the roots of human 108 00:06:40,600 --> 00:06:47,320 Speaker 1: intellectual exploration. Yeah, so lasers are pretty interesting, right, They 109 00:06:47,320 --> 00:06:51,520 Speaker 1: have an interesting history, Like apparently historians don't really know 110 00:06:51,839 --> 00:06:55,040 Speaker 1: who invented the laser, or they haven't settled on who 111 00:06:55,120 --> 00:06:58,000 Speaker 1: invented laser. That's right. And I heard that one really 112 00:06:58,040 --> 00:07:00,880 Speaker 1: important science historian actually wrote a him about it once. 113 00:07:01,200 --> 00:07:04,120 Speaker 1: Oh really is that true? Yeah? His name is Um. 114 00:07:04,160 --> 00:07:06,560 Speaker 1: Hold on, I have it here. Let me check Jorge him. 115 00:07:06,800 --> 00:07:13,400 Speaker 1: Oh yeah, that comic laureate of the Internet. Should we um? 116 00:07:13,400 --> 00:07:17,280 Speaker 1: Should we read the poem? Sure? Go for it. I'm 117 00:07:17,320 --> 00:07:19,680 Speaker 1: not sure if this is supposed to be set to 118 00:07:19,840 --> 00:07:23,560 Speaker 1: music or rhyme. Yeah, it's supposed to be said to 119 00:07:23,640 --> 00:07:31,120 Speaker 1: laser music. So you think, think eighties here and then 120 00:07:31,200 --> 00:07:34,040 Speaker 1: go for it. Um. So, I wrote this when the 121 00:07:34,160 --> 00:07:37,520 Speaker 1: laser turned fifty about eight years ago, was the anniversary 122 00:07:37,520 --> 00:07:39,480 Speaker 1: of the laser. I'll read it and you make the 123 00:07:39,480 --> 00:07:42,920 Speaker 1: pu pu sounds all right. The laser turns fifty this week, 124 00:07:43,360 --> 00:07:46,800 Speaker 1: an important event in history. But who developed this amazing 125 00:07:46,840 --> 00:07:51,520 Speaker 1: technique that's still kind of a mystery. Was it Ted 126 00:07:51,800 --> 00:07:54,680 Speaker 1: my mom who built the first laser? Or was it 127 00:07:54,720 --> 00:07:58,320 Speaker 1: Towns in Shacklow who wrote the seminal paper and it 128 00:07:58,360 --> 00:08:03,520 Speaker 1: goes on like that role beautifully crafted versus oh thanks, 129 00:08:04,120 --> 00:08:06,240 Speaker 1: Yeah it was you know what happened? I was in 130 00:08:06,320 --> 00:08:09,120 Speaker 1: Ottawa and I went to visit they have a laser 131 00:08:09,160 --> 00:08:12,040 Speaker 1: institute at one of the university there, and they explained 132 00:08:12,040 --> 00:08:14,160 Speaker 1: to me that the anniversary of the laser was coming up, 133 00:08:14,440 --> 00:08:16,440 Speaker 1: and so they explained to me how the laser works. 134 00:08:17,000 --> 00:08:18,960 Speaker 1: And in fact, I think that's kind of related to 135 00:08:19,000 --> 00:08:21,720 Speaker 1: how you and I started working together, right, Yeah, you 136 00:08:21,800 --> 00:08:25,240 Speaker 1: just reminded me of this today. Apparently your comic about 137 00:08:25,280 --> 00:08:27,800 Speaker 1: the laser is one of the ones that I read 138 00:08:27,920 --> 00:08:31,320 Speaker 1: and uh and induced me to write you an email. 139 00:08:31,480 --> 00:08:34,080 Speaker 1: So yeah, the history is kind of funny because the 140 00:08:34,120 --> 00:08:38,600 Speaker 1: Nobel Prize for the laser, the first prototype for the laser, 141 00:08:38,880 --> 00:08:42,960 Speaker 1: and the first paper about the laser are all credited 142 00:08:42,960 --> 00:08:46,760 Speaker 1: to different people, Like, nobody knows who invented this really, yeah, 143 00:08:46,840 --> 00:08:48,640 Speaker 1: it might have been one of these things where like 144 00:08:48,800 --> 00:08:51,240 Speaker 1: an idea that whose time has just come, you know, 145 00:08:51,559 --> 00:08:53,360 Speaker 1: we're on the cusp is sort of the next thing 146 00:08:53,360 --> 00:08:56,400 Speaker 1: to happen, and a few people contribute bits and pieces here, 147 00:08:56,520 --> 00:08:59,319 Speaker 1: and some other person puts these things together first there, 148 00:08:59,400 --> 00:09:01,640 Speaker 1: and uh, it's a bit of a mess. Yeah, it's 149 00:09:01,640 --> 00:09:03,400 Speaker 1: a bit of a mess. I think it's fascinating. Also 150 00:09:03,640 --> 00:09:06,560 Speaker 1: how important it is to assign credit for things like 151 00:09:07,000 --> 00:09:09,720 Speaker 1: we have the laser. It's awesome. Are people just fighting 152 00:09:09,720 --> 00:09:12,439 Speaker 1: about the money, like who earns a penny every time 153 00:09:12,480 --> 00:09:14,640 Speaker 1: they make a laser pointer? Or is it about like 154 00:09:14,679 --> 00:09:18,079 Speaker 1: the credit and scientific history? You know, it's it's interesting 155 00:09:18,080 --> 00:09:20,680 Speaker 1: to me how how long and nasty this battle is. 156 00:09:20,880 --> 00:09:23,880 Speaker 1: You mean you wouldn't fight to have that in your tombstone? 157 00:09:24,320 --> 00:09:28,960 Speaker 1: Daniel Whiteson invented the laser? Who would? Oh, I'm definitely 158 00:09:28,960 --> 00:09:30,800 Speaker 1: putting that on my tombstone. True or not? I mean, 159 00:09:30,840 --> 00:09:32,920 Speaker 1: you can put anything you wanted your trimstone. Nobody fact 160 00:09:33,000 --> 00:09:41,199 Speaker 1: checks tombstones. It's like fake news applied to tombstones. I'm 161 00:09:41,240 --> 00:09:43,600 Speaker 1: taking credit for all sorts of stuff in my tombstone. Well, 162 00:09:43,640 --> 00:09:48,080 Speaker 1: let's get into what Daniel is a laser? Right? So 163 00:09:48,520 --> 00:09:52,160 Speaker 1: a laser is different from a flashlight, right, It's not 164 00:09:52,280 --> 00:09:54,920 Speaker 1: just a flashlight with a lens, Okay. A laser is 165 00:09:54,960 --> 00:09:59,280 Speaker 1: something that produces a bunch of light, usually of the 166 00:09:59,360 --> 00:10:02,480 Speaker 1: same color or so, like all a bunch of photons 167 00:10:02,480 --> 00:10:05,880 Speaker 1: of the same energy, and they should all be going 168 00:10:05,960 --> 00:10:09,079 Speaker 1: in the same direction, right, So they're perfectly parallel. Meaning 169 00:10:09,400 --> 00:10:12,880 Speaker 1: if they're like, you know, a tiny distance apart now, 170 00:10:13,040 --> 00:10:16,360 Speaker 1: then a hundred meters away or a kilometer away, or 171 00:10:16,360 --> 00:10:19,080 Speaker 1: a million miles away, they'll still be the same distance apart, 172 00:10:19,240 --> 00:10:24,839 Speaker 1: perfectly parallel, perfectly parallel photons, right, yeah, exactly, So photons 173 00:10:24,920 --> 00:10:28,920 Speaker 1: usually of the same color, shot perfectly parallel, and also 174 00:10:29,520 --> 00:10:33,120 Speaker 1: wiggling the same way. Right. Remember, the photons are waves, 175 00:10:33,760 --> 00:10:36,040 Speaker 1: and they're like all other particles. They're governed by their 176 00:10:36,040 --> 00:10:38,640 Speaker 1: wave equation, and waves wiggle, right, they go up and 177 00:10:38,640 --> 00:10:40,440 Speaker 1: they go down, they go up and they go down. 178 00:10:40,760 --> 00:10:43,480 Speaker 1: And if you have two waves, if they're wiggling in 179 00:10:43,559 --> 00:10:46,600 Speaker 1: opposite directions, one wiggles up the other one wiggles down, 180 00:10:46,679 --> 00:10:49,720 Speaker 1: then they can cancel each other out. Right, So we 181 00:10:49,760 --> 00:10:51,920 Speaker 1: want our photons all wiggling the same way, so they 182 00:10:51,960 --> 00:10:54,800 Speaker 1: all sort of pushed together. It's like folks, on a 183 00:10:54,880 --> 00:10:57,520 Speaker 1: boat rowing at the same time. They all push together 184 00:10:57,760 --> 00:11:01,199 Speaker 1: for constructive interference to make a strong when they hit 185 00:11:01,280 --> 00:11:04,440 Speaker 1: something at the end. You want them to be perfectly synchronized. 186 00:11:04,480 --> 00:11:08,160 Speaker 1: Otherwise they might cancel each other out when they hit something. Yeah, 187 00:11:08,200 --> 00:11:10,320 Speaker 1: that's right, or they might you know, cancel each other 188 00:11:10,400 --> 00:11:12,600 Speaker 1: out part of the way. Um. You know these things, 189 00:11:12,640 --> 00:11:16,080 Speaker 1: these interference effects depend on the phase, and so yeah, 190 00:11:16,120 --> 00:11:18,800 Speaker 1: you want them all pushing in the same direction, um 191 00:11:18,840 --> 00:11:21,880 Speaker 1: at the same time. And so that's what a laser produces. Right. 192 00:11:21,920 --> 00:11:23,880 Speaker 1: That's that's what it means to be a laser. And 193 00:11:23,880 --> 00:11:26,080 Speaker 1: that's an important distinction of people to understand. That's not 194 00:11:26,200 --> 00:11:29,520 Speaker 1: just like a powerful flashlight or of uh flashlights somebody 195 00:11:29,600 --> 00:11:31,920 Speaker 1: put a lens in front of. It's a It's really 196 00:11:31,960 --> 00:11:34,200 Speaker 1: a very different kind of source of light. It's not 197 00:11:34,280 --> 00:11:37,439 Speaker 1: just a really bright light. It's like a perfectly ordered, 198 00:11:37,800 --> 00:11:40,880 Speaker 1: perfectly parallel beams of light. That's right. And there's two 199 00:11:40,960 --> 00:11:43,280 Speaker 1: kinds of lasers. One kind is the kind we're talking 200 00:11:43,320 --> 00:11:45,840 Speaker 1: about where all the photons have the same color, so 201 00:11:45,880 --> 00:11:48,880 Speaker 1: it's monochromatic, right, it's a single color of light, all 202 00:11:48,880 --> 00:11:51,400 Speaker 1: the photons of the same energy, the same color. UM. 203 00:11:51,520 --> 00:11:53,800 Speaker 1: That's the kind that you make to produce beams. You 204 00:11:53,840 --> 00:11:57,480 Speaker 1: can also produce laser pulses, right. These are short bursts, 205 00:11:57,840 --> 00:12:00,800 Speaker 1: and those require having lots of different colors so that 206 00:12:00,880 --> 00:12:03,720 Speaker 1: you add they add up and cancel out in just 207 00:12:03,760 --> 00:12:06,440 Speaker 1: the right way to have a localized burst. And you 208 00:12:06,480 --> 00:12:08,640 Speaker 1: can add up all the different wiggles together to make 209 00:12:09,200 --> 00:12:11,240 Speaker 1: the burst of any shape you want, right. And that's 210 00:12:11,360 --> 00:12:15,320 Speaker 1: different than a flashlight, because a flashlight it's just pumping 211 00:12:15,320 --> 00:12:19,400 Speaker 1: out photons with all kinds of colors and all kinds 212 00:12:19,400 --> 00:12:22,400 Speaker 1: of phases, and they're all out of sync with each other, 213 00:12:22,440 --> 00:12:24,599 Speaker 1: all these photons, that's right. And also they go in 214 00:12:24,840 --> 00:12:28,920 Speaker 1: in all different directions, right. Um, a flashlight usually has 215 00:12:28,960 --> 00:12:31,560 Speaker 1: like a tungsten filament bulb or something, right, and that's 216 00:12:31,600 --> 00:12:34,160 Speaker 1: just glowing and it's sending light in every direction. And 217 00:12:34,200 --> 00:12:35,800 Speaker 1: even if you have it, you know, coming out of 218 00:12:35,800 --> 00:12:38,560 Speaker 1: the front, so it's a little bit um shaped. You know. 219 00:12:38,600 --> 00:12:40,760 Speaker 1: You can take, for example, a flashlight and you can 220 00:12:40,760 --> 00:12:43,680 Speaker 1: point it at the moon, right, and as as you 221 00:12:43,720 --> 00:12:45,880 Speaker 1: get further away from the source of the light, the 222 00:12:46,040 --> 00:12:49,480 Speaker 1: size of the beam grows. Right. Flashlight makes a cone, 223 00:12:49,720 --> 00:12:52,240 Speaker 1: and the cone grows with distance, So you can point 224 00:12:52,240 --> 00:12:54,320 Speaker 1: it to the Moon, and you basically cover the whole 225 00:12:54,400 --> 00:12:57,559 Speaker 1: Moon with your flashlight, because by the time you get 226 00:12:57,559 --> 00:12:59,640 Speaker 1: to the distance of the Moon, the cone is huge. 227 00:12:59,760 --> 00:13:01,720 Speaker 1: Even if you focus it with like a lens and 228 00:13:01,800 --> 00:13:05,239 Speaker 1: try to get them parallel, they won't be perfectly parallel 229 00:13:05,480 --> 00:13:07,720 Speaker 1: exactly right. There's always going to be some spread there. 230 00:13:08,040 --> 00:13:10,720 Speaker 1: Whereas with a laser. If you take a laser and 231 00:13:10,800 --> 00:13:13,240 Speaker 1: you point it at the moon, if you if it's 232 00:13:13,240 --> 00:13:15,440 Speaker 1: a good laser, when it gets there, should have the 233 00:13:15,440 --> 00:13:17,520 Speaker 1: beam should have the same with is when is when 234 00:13:17,559 --> 00:13:22,160 Speaker 1: it left. So that's how that's why lasers are powerful, right, 235 00:13:22,200 --> 00:13:25,960 Speaker 1: because with just a few photons they can go a 236 00:13:26,080 --> 00:13:29,439 Speaker 1: great distance together and so they can transmit that information. 237 00:13:29,679 --> 00:13:31,520 Speaker 1: But they're also kind of in sync so they can 238 00:13:31,600 --> 00:13:34,360 Speaker 1: deliver all that power when they get there. That's right. 239 00:13:34,800 --> 00:13:36,760 Speaker 1: And that example about a laser to the Moon is 240 00:13:36,800 --> 00:13:39,400 Speaker 1: not just like a made up example. I don't know 241 00:13:39,400 --> 00:13:41,480 Speaker 1: if you know, but the astronauts who visited the Moon 242 00:13:41,600 --> 00:13:44,160 Speaker 1: left mirrors on the surface of the Moon so that 243 00:13:44,200 --> 00:13:46,880 Speaker 1: we can bounce lasers off of them and use that 244 00:13:46,920 --> 00:13:48,920 Speaker 1: to measure the distance from the Earth to the Moon. 245 00:13:50,000 --> 00:13:52,280 Speaker 1: I think that's pretty cool. The Earth's beak is selfie. 246 00:13:52,520 --> 00:13:57,200 Speaker 1: You can think we can take a selfie by shooting 247 00:13:57,200 --> 00:13:59,760 Speaker 1: the laser at the moon. And that's right. Even though 248 00:13:59,760 --> 00:14:02,840 Speaker 1: this is decades before the concept of selfies, it was 249 00:14:03,080 --> 00:14:06,240 Speaker 1: it was prescient that way, right. They were forward, forward looking. 250 00:14:06,320 --> 00:14:09,560 Speaker 1: NASA is always looking into the future. NASA invented the selfie. 251 00:14:10,160 --> 00:14:12,840 Speaker 1: We just we just give credit. We just give credit 252 00:14:12,880 --> 00:14:15,240 Speaker 1: to them. They can put it on the Actually the first, 253 00:14:15,320 --> 00:14:18,160 Speaker 1: the first selfie comes from decades and decades before that. 254 00:14:18,240 --> 00:14:21,680 Speaker 1: But but yeah, the first astronomical selfie for sure, first 255 00:14:21,760 --> 00:14:30,920 Speaker 1: laser selfie, that's right. Okay, So that's what the laser is. 256 00:14:31,000 --> 00:14:34,480 Speaker 1: It's like, it's like something that makes light, that shoots 257 00:14:34,560 --> 00:14:37,760 Speaker 1: light that's perfectly in sync and perfectly parallel and that's 258 00:14:37,760 --> 00:14:41,400 Speaker 1: really powerful. Okay, so what why is it called laser? 259 00:14:41,480 --> 00:14:45,160 Speaker 1: Like what what? What does that acronym mean? Light amplified 260 00:14:45,440 --> 00:14:49,480 Speaker 1: by stimulated emission radiation. That's right, let's break that down, right. 261 00:14:49,520 --> 00:14:52,120 Speaker 1: The first one is just light. Okay, so photons are light, 262 00:14:52,240 --> 00:14:57,680 Speaker 1: that's obvious. The last one, the last one is radiation, right, 263 00:14:58,360 --> 00:15:04,240 Speaker 1: and radiation in this case also it just means light. Yeah. 264 00:15:04,560 --> 00:15:05,960 Speaker 1: I think that's because they didn't want to call it 265 00:15:06,000 --> 00:15:09,400 Speaker 1: a laser that would have been more awkward with an 266 00:15:09,560 --> 00:15:16,720 Speaker 1: l So both of those words light and radiation just 267 00:15:16,800 --> 00:15:19,320 Speaker 1: refer to the photons, right, Okay. So it's something that 268 00:15:19,400 --> 00:15:23,280 Speaker 1: makes light, something that makes light and um and it 269 00:15:23,360 --> 00:15:26,160 Speaker 1: makes it in this special way using this process called 270 00:15:26,320 --> 00:15:30,280 Speaker 1: stimulated emission. Okay. And that's the really the guts of 271 00:15:30,320 --> 00:15:32,760 Speaker 1: the laser. That's what's going on inside, is that it's 272 00:15:32,800 --> 00:15:35,680 Speaker 1: a system that creates this stimulated emission. So we should 273 00:15:35,680 --> 00:15:38,640 Speaker 1: dig into that. The A and laser beings amplified, meaning 274 00:15:39,320 --> 00:15:42,240 Speaker 1: you're not just making that use sort of amplifying it somehow. 275 00:15:42,600 --> 00:15:44,600 Speaker 1: That's right. The basic principle of the laser is you 276 00:15:44,640 --> 00:15:47,320 Speaker 1: start with one photon of the color that you want, 277 00:15:47,680 --> 00:15:50,640 Speaker 1: you know, and you amplify use that to use this 278 00:15:50,720 --> 00:15:52,720 Speaker 1: system to multiply you. So I want to start with 279 00:15:52,760 --> 00:15:55,200 Speaker 1: one photon and then you create a chain reaction that 280 00:15:55,240 --> 00:15:57,960 Speaker 1: gives you ten photons, and then a hundred photons, and 281 00:15:57,960 --> 00:16:01,720 Speaker 1: then a thousand photons, etcetera, etcetera. Grows exponentially until you 282 00:16:01,760 --> 00:16:04,640 Speaker 1: have a very very intense beam of photons all the 283 00:16:04,680 --> 00:16:08,120 Speaker 1: same kind. And the key is the stimulated emission. That's 284 00:16:08,120 --> 00:16:10,880 Speaker 1: the thing that basically copies the photon. It says, if 285 00:16:10,920 --> 00:16:13,680 Speaker 1: you have one of the right wavelength or to all 286 00:16:13,720 --> 00:16:16,000 Speaker 1: the right attributes, then I can make more for you. 287 00:16:16,200 --> 00:16:20,120 Speaker 1: That's this process called stimulated emission. Okay, let's get stimulated 288 00:16:20,200 --> 00:16:36,760 Speaker 1: by stimulated emission. But first let's take a quick break. Okay, 289 00:16:36,800 --> 00:16:40,200 Speaker 1: So laser is something that makes light that's all the 290 00:16:40,280 --> 00:16:46,200 Speaker 1: same color, the same wavelength, the same direction, the same wiggle, 291 00:16:46,720 --> 00:16:49,600 Speaker 1: and it's all done by something called stimulated emission. What 292 00:16:49,640 --> 00:16:51,720 Speaker 1: does that mean? Right? So the thing that's doing the 293 00:16:51,760 --> 00:16:54,680 Speaker 1: emission is just an atom, and so you have some 294 00:16:54,800 --> 00:16:57,080 Speaker 1: medium in your laser. Maybe it's a crystal, maybe it's 295 00:16:57,120 --> 00:16:58,960 Speaker 1: a gas that doesn't really matter, but it's a bunch 296 00:16:58,960 --> 00:17:03,520 Speaker 1: of atoms. And atoms can emit light, right, any atom, 297 00:17:03,720 --> 00:17:05,600 Speaker 1: any atom can emit light. Right, you make you get 298 00:17:05,640 --> 00:17:09,440 Speaker 1: things hot and they glow, right, that's something emitting light. 299 00:17:09,480 --> 00:17:12,920 Speaker 1: So if you pump energy into some material, right, it 300 00:17:12,960 --> 00:17:15,920 Speaker 1: will absorb that energy and bring it internally into itself. 301 00:17:17,000 --> 00:17:19,440 Speaker 1: But then sometimes it gets rid of that energy. That's 302 00:17:19,480 --> 00:17:22,760 Speaker 1: called emission, and it turns that energy into light. And 303 00:17:22,800 --> 00:17:25,560 Speaker 1: the way that it does that is it has inside 304 00:17:25,560 --> 00:17:27,960 Speaker 1: it, it it has these electrons. Right, So every atom has 305 00:17:27,960 --> 00:17:31,720 Speaker 1: electrons whizzing around it, and there's electrons have a few 306 00:17:31,880 --> 00:17:35,120 Speaker 1: certain orbits that they can use around the atom. It's 307 00:17:35,160 --> 00:17:37,879 Speaker 1: like a bunch of different energy levels. Electrons can't just 308 00:17:37,920 --> 00:17:41,320 Speaker 1: have any random energy level around it atom. Based on 309 00:17:41,359 --> 00:17:44,920 Speaker 1: the shape of the atom and the configuration of the protons, etcetera. 310 00:17:45,040 --> 00:17:47,400 Speaker 1: There's a few places the electrons are allowed to live, 311 00:17:47,520 --> 00:17:50,160 Speaker 1: so they're called energy levels. And you can imagine sort 312 00:17:50,160 --> 00:17:52,679 Speaker 1: of a ladder of these energy levels. And that's kind 313 00:17:52,680 --> 00:17:56,840 Speaker 1: of related to their wave nature of electrons, right, because 314 00:17:56,840 --> 00:18:00,000 Speaker 1: their waves they can only fit in so many ways 315 00:18:00,280 --> 00:18:02,840 Speaker 1: around the atom. Right, It's sort of related to that, right, 316 00:18:03,040 --> 00:18:06,000 Speaker 1: It's very closely related. Yeah. Um, the reason that there 317 00:18:06,040 --> 00:18:10,480 Speaker 1: are discrete energy levels, right, quantized energy levels, is precisely 318 00:18:10,520 --> 00:18:13,240 Speaker 1: because of those waves and the way the waves fit 319 00:18:13,280 --> 00:18:15,840 Speaker 1: together around the atom. So a simple way to think 320 00:18:15,880 --> 00:18:18,679 Speaker 1: about it is when the electron goes around the atom, 321 00:18:18,720 --> 00:18:21,240 Speaker 1: it's going to do it's wiggling, and you wanted to 322 00:18:21,280 --> 00:18:23,520 Speaker 1: build on itself. You don't want it to cancel itself out, 323 00:18:23,960 --> 00:18:27,280 Speaker 1: and so when it comes around one orbit, you need 324 00:18:27,359 --> 00:18:29,080 Speaker 1: to be in the same place in its wiggle either 325 00:18:29,119 --> 00:18:31,399 Speaker 1: it's wiggling up or it's wiggling down. It has to 326 00:18:31,480 --> 00:18:35,399 Speaker 1: fit a very specific number of wiggles in an orbit. 327 00:18:35,600 --> 00:18:38,320 Speaker 1: You can just do like three and a half that's right. 328 00:18:38,359 --> 00:18:42,320 Speaker 1: It has to wiggle once or twice or three times. Right. 329 00:18:42,359 --> 00:18:45,040 Speaker 1: If it wiggles one and a half times, then it's 330 00:18:45,040 --> 00:18:47,120 Speaker 1: going to get out of sync with itself and eventually 331 00:18:47,160 --> 00:18:50,159 Speaker 1: cancel itself out. So those are not stable solutions. So 332 00:18:50,160 --> 00:18:53,320 Speaker 1: you can't have an electron hanging out and wiggling one 333 00:18:53,359 --> 00:18:55,399 Speaker 1: and a half times around the atom. So each of 334 00:18:55,400 --> 00:18:57,359 Speaker 1: those is a different level. It's not like the Earth 335 00:18:57,480 --> 00:18:59,760 Speaker 1: going around the Sun, like if something moves as a 336 00:18:59,760 --> 00:19:02,920 Speaker 1: little bit, our orbit will increase a little bit. That's 337 00:19:02,920 --> 00:19:06,520 Speaker 1: not how electrons work. They have very specific orbits that 338 00:19:06,560 --> 00:19:09,320 Speaker 1: can fit around the nucleus of the atom. Yeah, that's 339 00:19:09,359 --> 00:19:13,920 Speaker 1: actually a really interesting deep question. Is the Earth's orbit quantized? 340 00:19:14,440 --> 00:19:17,399 Speaker 1: Are there an infinite number of orbits? That's not a 341 00:19:17,440 --> 00:19:21,480 Speaker 1: one with a simple answer. If gravity is not quantum mechanical, 342 00:19:21,840 --> 00:19:24,119 Speaker 1: then you're right, so there's an infinite number of orbits 343 00:19:24,119 --> 00:19:26,840 Speaker 1: the Earth can take. However, if the gravity is quantized, 344 00:19:27,359 --> 00:19:31,280 Speaker 1: then then you're wrong, and there are energy levels around 345 00:19:31,320 --> 00:19:33,400 Speaker 1: the Sun, but those energy levels would be so tiny 346 00:19:33,440 --> 00:19:35,800 Speaker 1: we could probably not even see them anyway. That might 347 00:19:35,840 --> 00:19:40,320 Speaker 1: be the subject of a different podcast. Yeah, exactly. Yeah. 348 00:19:40,359 --> 00:19:42,440 Speaker 1: So the energy, So the electron has these energy levels 349 00:19:42,440 --> 00:19:44,520 Speaker 1: it has on these ladder. This ladder can go up 350 00:19:44,520 --> 00:19:47,640 Speaker 1: and it can go down. Yeah, people use the ladder analogy, right, 351 00:19:47,680 --> 00:19:49,720 Speaker 1: like electrons can be here or it can go up 352 00:19:49,800 --> 00:19:53,359 Speaker 1: a level or another level. Right, It's like very discrete steps. 353 00:19:54,080 --> 00:19:56,399 Speaker 1: And just like with the ladder, what happens when you 354 00:19:56,440 --> 00:19:58,800 Speaker 1: go up a level? Will you It takes some energy 355 00:19:58,840 --> 00:20:01,320 Speaker 1: to do that, right, put some energy into your thigh 356 00:20:01,359 --> 00:20:03,880 Speaker 1: muscle to push you up, and then you're storing more 357 00:20:04,040 --> 00:20:07,000 Speaker 1: energy or you have more gravitational energy because you're higher up. 358 00:20:07,400 --> 00:20:09,280 Speaker 1: The same thing happens with the electron. How does it 359 00:20:09,280 --> 00:20:12,359 Speaker 1: go up a level? It needs to get energy from somewhere, right, 360 00:20:12,359 --> 00:20:15,040 Speaker 1: it needs to get heated up or absorb some light 361 00:20:15,160 --> 00:20:17,760 Speaker 1: or something. So it can go up a level, right, 362 00:20:18,320 --> 00:20:20,159 Speaker 1: and then it can go down a level. And what 363 00:20:20,160 --> 00:20:22,760 Speaker 1: happens when it goes down a level While the energy 364 00:20:22,960 --> 00:20:25,120 Speaker 1: level it was at is fixed and the energy level 365 00:20:25,200 --> 00:20:27,919 Speaker 1: is going to is fixed, so the energy difference between 366 00:20:27,960 --> 00:20:31,399 Speaker 1: them is fixed, meaning every atom has the same levels. 367 00:20:31,400 --> 00:20:34,840 Speaker 1: And if electrons jumped down from one level to the 368 00:20:34,880 --> 00:20:38,520 Speaker 1: lower one. Then they're going to release a photon whose 369 00:20:38,680 --> 00:20:41,320 Speaker 1: energy is exactly the difference between those two levels, right, 370 00:20:41,400 --> 00:20:45,080 Speaker 1: conservation of energy. The electron loses energy, goes down a level, 371 00:20:45,119 --> 00:20:47,879 Speaker 1: and it gives off that missing that extra energy in 372 00:20:48,000 --> 00:20:50,880 Speaker 1: terms of a photon. Okay, so the electron goes down 373 00:20:50,920 --> 00:20:53,520 Speaker 1: a level, it will shoot out a photon with that 374 00:20:53,680 --> 00:20:56,720 Speaker 1: energy that it doesn't need anymore. That's right, exactly. So 375 00:20:57,040 --> 00:20:59,400 Speaker 1: how do you get a bunch of photons of all 376 00:20:59,440 --> 00:21:01,400 Speaker 1: the same color in the same direction. When you get 377 00:21:01,400 --> 00:21:03,960 Speaker 1: a bunch of atoms, You get them all to have 378 00:21:04,080 --> 00:21:06,720 Speaker 1: their electrons up one level, right, You heat them up, 379 00:21:06,840 --> 00:21:09,520 Speaker 1: you pump some energy into them somehow, and then you 380 00:21:09,520 --> 00:21:11,840 Speaker 1: get them to come down all about the same time. 381 00:21:12,000 --> 00:21:14,560 Speaker 1: You get them excited. You get him excited, right, and 382 00:21:14,560 --> 00:21:17,800 Speaker 1: then you get them the big let down. Yeah, all, 383 00:21:19,280 --> 00:21:22,200 Speaker 1: And when they get the let down, that's when they 384 00:21:22,280 --> 00:21:24,520 Speaker 1: give off a photon, and each one will give off 385 00:21:24,840 --> 00:21:30,359 Speaker 1: the same color photon. The photon is determined exactly by 386 00:21:30,600 --> 00:21:33,200 Speaker 1: its energy, which is determined by its wavelength. Right, those 387 00:21:33,200 --> 00:21:35,320 Speaker 1: things things are all connected, right, But they don't all 388 00:21:35,359 --> 00:21:37,080 Speaker 1: in a laser. They don't all give them out at 389 00:21:37,080 --> 00:21:39,399 Speaker 1: the same time, it's it's kind of like how you 390 00:21:39,440 --> 00:21:42,639 Speaker 1: said earlier. You want to cause a chain reaction that 391 00:21:42,760 --> 00:21:45,560 Speaker 1: will make all the atoms in your laser shoot all 392 00:21:45,560 --> 00:21:49,480 Speaker 1: these photons perfectly saying exactly so that chain reaction is key, 393 00:21:49,640 --> 00:21:52,000 Speaker 1: and you can have an atom and you can give 394 00:21:52,000 --> 00:21:54,600 Speaker 1: it energy. So the electron goes up one level and 395 00:21:54,640 --> 00:21:56,840 Speaker 1: then it's happened to just hang out there for a while, right, 396 00:21:57,320 --> 00:22:00,960 Speaker 1: But what happens when another photon just the right energy 397 00:22:01,040 --> 00:22:03,800 Speaker 1: level comes by, Like if you're an electron, you're an 398 00:22:03,800 --> 00:22:07,280 Speaker 1: excited state, um, and there's like a ladders step ladder 399 00:22:07,320 --> 00:22:10,080 Speaker 1: step below you, or you could go down. If a 400 00:22:10,080 --> 00:22:13,600 Speaker 1: photon comes by just that right energy level, it has 401 00:22:13,680 --> 00:22:16,480 Speaker 1: exactly the energy that's between you and that lower level, 402 00:22:16,840 --> 00:22:19,720 Speaker 1: then you're more likely to emit. You get pushed sort 403 00:22:19,720 --> 00:22:22,280 Speaker 1: of out of that energy level. And the reason is 404 00:22:22,320 --> 00:22:25,760 Speaker 1: that that photon changes the way the environment works. Right. 405 00:22:25,880 --> 00:22:29,880 Speaker 1: Photons are electromagnetic waves, so it creates a little electromagnetic 406 00:22:29,920 --> 00:22:32,600 Speaker 1: field there that makes what you were doing a little 407 00:22:32,760 --> 00:22:35,080 Speaker 1: less stable, so sort of pushes you out of that 408 00:22:35,119 --> 00:22:37,399 Speaker 1: state down to a lower state, and you end up 409 00:22:37,400 --> 00:22:41,360 Speaker 1: emitting another photon. So the bottom line is if you're 410 00:22:41,400 --> 00:22:44,879 Speaker 1: capable of emitting that photon, and one photon just like 411 00:22:44,960 --> 00:22:46,879 Speaker 1: that comes by, then you're gonna give it up and 412 00:22:46,920 --> 00:22:51,159 Speaker 1: emit that photon. And that's why it's called stimulated emission. Right, Like, 413 00:22:51,280 --> 00:22:55,119 Speaker 1: if you're an excited atom, you could just spontaneously have 414 00:22:55,240 --> 00:22:59,880 Speaker 1: your electron drop and admit a photon. That's called spontaneous emission. Yeah, 415 00:23:00,200 --> 00:23:03,760 Speaker 1: But stimulated emission is when you're excited and you get 416 00:23:03,840 --> 00:23:07,720 Speaker 1: hit by another photon and that causes you to drop 417 00:23:07,760 --> 00:23:10,960 Speaker 1: a level and emit another photon. Yeah. It's sort of 418 00:23:10,960 --> 00:23:13,639 Speaker 1: like peer pressure and you're like, hey, everybody's emitting that 419 00:23:13,680 --> 00:23:17,159 Speaker 1: red photon. I got one, I could emit one, and yeah, 420 00:23:17,240 --> 00:23:19,440 Speaker 1: yeah I could, and so I will. This is the 421 00:23:19,560 --> 00:23:22,200 Speaker 1: right time, you know. And so that's what the stimulated 422 00:23:22,240 --> 00:23:25,080 Speaker 1: part is. Right, Um, it's not. This is not nocturnal emissions. 423 00:23:25,080 --> 00:23:30,200 Speaker 1: People were talking about photons stimulating electrons into a emitting 424 00:23:30,240 --> 00:23:41,359 Speaker 1: war photons. What's the acronym for that one? Leaner? Um? 425 00:23:41,440 --> 00:23:44,120 Speaker 1: So to review, right, you start, you get some material, 426 00:23:44,400 --> 00:23:46,800 Speaker 1: you gotta pump it with energy. It's not free energy, right, 427 00:23:46,800 --> 00:23:48,879 Speaker 1: you gotta pump it with energy somehow. You gotta get 428 00:23:48,880 --> 00:23:53,359 Speaker 1: the atoms excited in your media and lock of stuff. Yeah, 429 00:23:53,400 --> 00:23:55,280 Speaker 1: it's like you know your comedy routine. You need somebody 430 00:23:55,320 --> 00:23:57,359 Speaker 1: go out there and warm up the crowd. Right, So 431 00:23:57,480 --> 00:23:59,960 Speaker 1: first you warm up the crowd, you get it's called 432 00:24:00,040 --> 00:24:03,520 Speaker 1: population inversion. Maybe've heard that phrase by everyone a beer, 433 00:24:05,000 --> 00:24:08,040 Speaker 1: that's right, We've discovered alcohol makes people laugh at the 434 00:24:08,119 --> 00:24:13,160 Speaker 1: jokes more. And so the physics equivalent for lasers, right, 435 00:24:13,760 --> 00:24:17,040 Speaker 1: is you pump the room with with energy and you 436 00:24:17,080 --> 00:24:19,920 Speaker 1: get all those electrons up at that level, and then 437 00:24:20,000 --> 00:24:23,199 Speaker 1: one of them will one of them will pop, right, 438 00:24:23,359 --> 00:24:25,880 Speaker 1: and that will cause the chain reaction. Having one photon 439 00:24:25,920 --> 00:24:28,439 Speaker 1: around will make all these other atoms which you know 440 00:24:28,600 --> 00:24:31,600 Speaker 1: are holding that photon inside them. Basically, birds didn't get 441 00:24:31,680 --> 00:24:33,800 Speaker 1: rid of it. They'll start emitting and then and then 442 00:24:33,880 --> 00:24:35,640 Speaker 1: more and more will admit. But they have to get 443 00:24:35,720 --> 00:24:40,159 Speaker 1: hit by a photon for them to release a photon, right, Like, 444 00:24:40,200 --> 00:24:43,240 Speaker 1: it doesn't just yeah, it's not because your neighbor shot 445 00:24:43,240 --> 00:24:45,840 Speaker 1: out a photon, then you shoot out a photon. It's 446 00:24:45,880 --> 00:24:47,280 Speaker 1: like you got you have to get hit by a 447 00:24:47,280 --> 00:24:50,159 Speaker 1: photon for you to get stimulated. Yeah, you don't have 448 00:24:50,240 --> 00:24:53,560 Speaker 1: to absorb it, but having the photon nearby close enough 449 00:24:53,560 --> 00:24:56,920 Speaker 1: to interact with the atom will change the electromagnetic vicinity 450 00:24:57,040 --> 00:24:59,520 Speaker 1: essentially and cause it to do that. And that's why 451 00:24:59,560 --> 00:25:02,040 Speaker 1: you usually you also put this block of atoms in 452 00:25:02,040 --> 00:25:04,600 Speaker 1: a resonant cavity. Basically you put two mirrors on either 453 00:25:04,640 --> 00:25:08,200 Speaker 1: side so that you capture the photons and you sort 454 00:25:08,240 --> 00:25:10,320 Speaker 1: of bounce them around inside. It's the same reason why 455 00:25:10,320 --> 00:25:12,720 Speaker 1: you have like walls in your oven, right, you want 456 00:25:12,720 --> 00:25:16,280 Speaker 1: to reflect the energy back so that it builds on itself. Right. 457 00:25:16,359 --> 00:25:20,080 Speaker 1: But that that whole process I heard is still even 458 00:25:20,119 --> 00:25:24,440 Speaker 1: a mystery for physicists, Like why exactly does the stimulated 459 00:25:24,560 --> 00:25:29,000 Speaker 1: atom shootout a photon that's exactly exactly like the one 460 00:25:29,080 --> 00:25:31,760 Speaker 1: that just went by closely or that hit it. Why 461 00:25:31,800 --> 00:25:34,720 Speaker 1: does it create a photon that's exactly identical to the 462 00:25:34,760 --> 00:25:37,879 Speaker 1: one that it saw with the same like wiggle and 463 00:25:37,960 --> 00:25:41,320 Speaker 1: the same timing in this exact same direction. That's still 464 00:25:41,400 --> 00:25:43,400 Speaker 1: kind of a mystery, right. Well, I think there's some 465 00:25:43,520 --> 00:25:47,199 Speaker 1: quantum mechanical arguments that that suggested. I think there's a 466 00:25:47,200 --> 00:25:50,679 Speaker 1: lot of the details are not perfectly understood. But you know, 467 00:25:50,720 --> 00:25:55,080 Speaker 1: the photon creates destabilizes the atom a tiny bit, right, 468 00:25:55,440 --> 00:25:57,880 Speaker 1: and so we can understand that there's something called firms 469 00:25:57,920 --> 00:26:00,679 Speaker 1: Golden rule, which tells us about how how things like 470 00:26:00,800 --> 00:26:04,320 Speaker 1: to decay, and so having that photon around definitely helps 471 00:26:04,400 --> 00:26:08,600 Speaker 1: us understand how the electron would be more likely to 472 00:26:08,680 --> 00:26:12,000 Speaker 1: jump down. Um. But yeah, why why it comes out 473 00:26:12,000 --> 00:26:14,119 Speaker 1: in exactly the same phase for example, I think it's 474 00:26:14,160 --> 00:26:16,120 Speaker 1: more likely too, but not guaranteed. So I think there 475 00:26:16,119 --> 00:26:20,000 Speaker 1: definitely are some some open questions there before we keep going, 476 00:26:20,119 --> 00:26:36,159 Speaker 1: Let's take a short break. Okay, So that's the S 477 00:26:36,240 --> 00:26:39,239 Speaker 1: E N L A S E R and so we 478 00:26:39,320 --> 00:26:41,400 Speaker 1: we tried. We covered all the letters. So it's light 479 00:26:41,800 --> 00:26:47,240 Speaker 1: amplified by stimulated emission radiation, that's right, and um. And 480 00:26:47,280 --> 00:26:48,720 Speaker 1: so you have it in this box and you have 481 00:26:48,800 --> 00:26:51,719 Speaker 1: these residents. You have a resident cavity. You have either mirrors, right, 482 00:26:51,800 --> 00:26:54,320 Speaker 1: bounce it back and forth, so the photons you emit 483 00:26:54,800 --> 00:26:57,520 Speaker 1: more photons to emit and um. You know, you can 484 00:26:57,560 --> 00:26:58,879 Speaker 1: have a little hole in the side so that some 485 00:26:58,960 --> 00:27:01,320 Speaker 1: of them leak out, and that's basically your laser. That's 486 00:27:01,320 --> 00:27:03,320 Speaker 1: how you produce it, right. But it can be a 487 00:27:03,320 --> 00:27:06,199 Speaker 1: constant thing. You can be constantly pumping it with energy, 488 00:27:06,480 --> 00:27:08,720 Speaker 1: pushing the electrons up and then they come down. You 489 00:27:08,760 --> 00:27:11,080 Speaker 1: get photon, you push them back up right so it 490 00:27:11,080 --> 00:27:13,920 Speaker 1: can be a continual thing. Um. One of the most 491 00:27:14,000 --> 00:27:16,560 Speaker 1: interesting lasers I ever saw was actually here on on 492 00:27:16,680 --> 00:27:19,440 Speaker 1: campus at U SEE. I as a professor here Franklin 493 00:27:19,480 --> 00:27:22,360 Speaker 1: Dollar who does fusion research, and they're trying to create 494 00:27:22,480 --> 00:27:24,639 Speaker 1: fusion by focusing a bunch of lasers all in the 495 00:27:24,720 --> 00:27:27,879 Speaker 1: same place. And he had this amazing setup where had 496 00:27:27,920 --> 00:27:30,879 Speaker 1: a bunch of lasers all overlapping in his lab and 497 00:27:31,000 --> 00:27:34,920 Speaker 1: he created a ball of plasma that was just floating 498 00:27:35,000 --> 00:27:38,960 Speaker 1: there in empty space. It was incredible. You can trap 499 00:27:39,160 --> 00:27:42,639 Speaker 1: atoms with lasers basically, right, you can do that, but 500 00:27:42,760 --> 00:27:45,080 Speaker 1: here he was just basically heating the air with a 501 00:27:45,119 --> 00:27:47,440 Speaker 1: bunch of lasers. By pointing a bunch of lasers so 502 00:27:47,720 --> 00:27:50,919 Speaker 1: they overlapped in one place in space. He heated up 503 00:27:50,960 --> 00:27:53,640 Speaker 1: the air hot enough to ionize and create a floating 504 00:27:53,720 --> 00:27:56,240 Speaker 1: ball of plasma. It was like looking at stable lightning. 505 00:27:56,720 --> 00:27:59,040 Speaker 1: It was pretty incredible. But these are These mirrors are 506 00:27:59,119 --> 00:28:02,200 Speaker 1: pretty cool because they're not just any mirrors that you 507 00:28:02,280 --> 00:28:06,200 Speaker 1: put on both sides of your stimulated stuff. It's like 508 00:28:06,320 --> 00:28:08,560 Speaker 1: one of them has to be a one way mirror. 509 00:28:09,320 --> 00:28:11,760 Speaker 1: One of them is a regular mirror, but the other 510 00:28:11,800 --> 00:28:14,600 Speaker 1: one is like a half mirror, meaning that it reflects 511 00:28:14,640 --> 00:28:16,440 Speaker 1: some of the light, but it also lets through some 512 00:28:16,560 --> 00:28:18,439 Speaker 1: of the light. Right, that's right. If both of them 513 00:28:18,480 --> 00:28:20,800 Speaker 1: were perfect mirrors, then you would never get anything out 514 00:28:20,840 --> 00:28:23,119 Speaker 1: of your laser. You just they would all stay inside 515 00:28:23,160 --> 00:28:25,280 Speaker 1: the cavity. So you have to have one of them 516 00:28:25,320 --> 00:28:27,640 Speaker 1: being imperfect mirrors that some of them leak out. Yeah, 517 00:28:27,720 --> 00:28:29,520 Speaker 1: So that that's kind of where the laser is. It's 518 00:28:29,600 --> 00:28:33,480 Speaker 1: kind of like a light echo chamber. Meaning you get 519 00:28:33,560 --> 00:28:36,520 Speaker 1: you get all your atoms excited, and then you set 520 00:28:36,600 --> 00:28:41,280 Speaker 1: one one of them off and then that will, for example, 521 00:28:41,360 --> 00:28:43,920 Speaker 1: go to the right, bounce off the mirror, go to 522 00:28:44,000 --> 00:28:48,240 Speaker 1: the left, hit another atom, cause it to also admit 523 00:28:48,280 --> 00:28:51,200 Speaker 1: an exact copy of that photon hit the other mirror. 524 00:28:51,280 --> 00:28:53,200 Speaker 1: Then both of them come back to the stuff, and 525 00:28:53,280 --> 00:28:55,720 Speaker 1: then they stimulate two other atoms, and then that creates 526 00:28:55,760 --> 00:28:59,640 Speaker 1: four photons and that just kind of builds and multiplies 527 00:28:59,680 --> 00:29:02,160 Speaker 1: within your echo chamber. But because one of the mirrors 528 00:29:02,680 --> 00:29:06,080 Speaker 1: is one way or semi transparent, that's where the laser 529 00:29:06,160 --> 00:29:08,800 Speaker 1: shoots out. Right, Yeah, yeah, exactly. Did I just make 530 00:29:08,880 --> 00:29:11,200 Speaker 1: that up? You should be the physicist on this podcast, man, 531 00:29:15,320 --> 00:29:17,080 Speaker 1: But I mean that's that's an important part of it. Right. 532 00:29:17,120 --> 00:29:19,240 Speaker 1: It's like you have you want to develop an echo chamber, 533 00:29:19,360 --> 00:29:21,080 Speaker 1: but you have to let some of the light out, 534 00:29:21,560 --> 00:29:23,680 Speaker 1: that's right. Yeah, If you don't let some of that out, 535 00:29:23,720 --> 00:29:27,360 Speaker 1: then it's pretty quickly going to get overheated. You're gonna 536 00:29:27,440 --> 00:29:31,120 Speaker 1: laser your own laser, right, And it's for all those 537 00:29:31,320 --> 00:29:33,440 Speaker 1: for all of us who have ever built a death star. 538 00:29:33,600 --> 00:29:36,600 Speaker 1: You know that you want it to blow up your 539 00:29:36,880 --> 00:29:39,280 Speaker 1: enemies basis, you don't want it to destroy your own. 540 00:29:45,840 --> 00:29:48,560 Speaker 1: But then it's stimulating the stuff in between. You can 541 00:29:48,600 --> 00:29:51,120 Speaker 1: do that several ways. Like your stuff can be a 542 00:29:51,200 --> 00:29:54,760 Speaker 1: gas or it can be crystal to right, that's right. 543 00:29:54,920 --> 00:29:57,719 Speaker 1: And if you want a laser to give you light 544 00:29:57,800 --> 00:30:00,000 Speaker 1: of a certain wavelength, like you want a red laser 545 00:30:00,080 --> 00:30:02,840 Speaker 1: or a green laser, or an X ray laser or something, 546 00:30:03,360 --> 00:30:07,160 Speaker 1: you have to find a material that has steps in 547 00:30:07,240 --> 00:30:10,320 Speaker 1: the ladder, their steps in their electron ladder that are 548 00:30:10,400 --> 00:30:12,680 Speaker 1: just the right size. Right. You can't just tune it 549 00:30:12,800 --> 00:30:14,920 Speaker 1: up to anything you want, right, You can't say I 550 00:30:15,000 --> 00:30:18,120 Speaker 1: want photons of this frequency. You have to find some 551 00:30:18,360 --> 00:30:22,440 Speaker 1: material that has electrons um that have an energy level 552 00:30:22,520 --> 00:30:25,200 Speaker 1: that has just the right size and that's why some 553 00:30:25,400 --> 00:30:27,160 Speaker 1: of these things are easy, and some of these things 554 00:30:27,200 --> 00:30:30,080 Speaker 1: are hard, like X ray lasers are really difficult to build, 555 00:30:31,240 --> 00:30:33,720 Speaker 1: and they're really everywhere, right, Like I was thinking, like 556 00:30:34,040 --> 00:30:36,040 Speaker 1: if you have a mouse in your computer and it's 557 00:30:36,040 --> 00:30:38,560 Speaker 1: an optical mouse that has a little laser in it, right, 558 00:30:38,760 --> 00:30:42,760 Speaker 1: that's right, Yeah, yeah, lasers are everywhere, and uh, it's 559 00:30:42,800 --> 00:30:46,080 Speaker 1: amazing how influential they have become. You know. And if 560 00:30:46,120 --> 00:30:47,680 Speaker 1: you look back at the history of the lasers, not 561 00:30:47,760 --> 00:30:50,080 Speaker 1: only is it a big mess nobody can agree about 562 00:30:50,480 --> 00:30:53,400 Speaker 1: who invented them, but in the early days there was 563 00:30:53,440 --> 00:30:57,040 Speaker 1: a lot of skepticism that it was even useful at all. Right, 564 00:30:57,440 --> 00:31:01,480 Speaker 1: some scientists thought it was impossible to make a laser, right, Yeah, 565 00:31:01,520 --> 00:31:03,400 Speaker 1: it was Neil's bore. He tried to make an argument 566 00:31:03,480 --> 00:31:06,080 Speaker 1: using the Heisenberg and certainty principle. He was like, you 567 00:31:06,200 --> 00:31:09,560 Speaker 1: can't have that many atoms in a specified state. He 568 00:31:09,640 --> 00:31:12,280 Speaker 1: thought it would just be impossibly that quantum mechanics would 569 00:31:12,360 --> 00:31:14,600 Speaker 1: make it not possible to make a laser, when in fact, 570 00:31:14,960 --> 00:31:17,480 Speaker 1: you need quantum mechanics to build a laser. Right, So 571 00:31:17,480 --> 00:31:20,680 Speaker 1: it works the other direction, So sometimes famous scientists get 572 00:31:20,720 --> 00:31:23,640 Speaker 1: it wrong. What was his argument for saying that it 573 00:31:23,720 --> 00:31:26,240 Speaker 1: was impossible, Well, you know, the Heisenberg and certainty principle 574 00:31:26,320 --> 00:31:29,040 Speaker 1: tells you that there's a certain there's a limit to 575 00:31:29,040 --> 00:31:31,920 Speaker 1: how much information you can have, right, And so he 576 00:31:32,120 --> 00:31:35,560 Speaker 1: was arguing that having all these atoms in the same state, 577 00:31:35,880 --> 00:31:40,560 Speaker 1: that you're specifying their energy um too tightly, right, you 578 00:31:40,680 --> 00:31:43,520 Speaker 1: can't the same way the Heisenberger and certainty principle tells 579 00:31:43,560 --> 00:31:46,720 Speaker 1: you that you can't know the position and momentum um 580 00:31:47,600 --> 00:31:50,200 Speaker 1: of a particle at the same time. It also applies 581 00:31:50,240 --> 00:31:54,680 Speaker 1: to the energy and timing information, and so a laser 582 00:31:54,880 --> 00:31:57,160 Speaker 1: is trying to isolate a bunch of particles have the 583 00:31:57,240 --> 00:31:59,680 Speaker 1: same energy all at the same time. And so he 584 00:31:59,800 --> 00:32:01,480 Speaker 1: thought that that was going to violate the Heisenberg on 585 00:32:01,520 --> 00:32:06,000 Speaker 1: certainly principle. But clearly it doesn't. We shot that down 586 00:32:06,040 --> 00:32:11,240 Speaker 1: with a laser's right, with our fully operational battle station. 587 00:32:12,640 --> 00:32:14,880 Speaker 1: So so there's, uh, it's interesting that there are all 588 00:32:15,000 --> 00:32:17,640 Speaker 1: kinds of different kinds of laser right, Right, Like your 589 00:32:17,720 --> 00:32:19,640 Speaker 1: mouse can have a laser on it, but you can 590 00:32:19,680 --> 00:32:22,960 Speaker 1: also use a laser to cut through steel, right, Like, 591 00:32:23,160 --> 00:32:26,200 Speaker 1: what's the difference between the laser and my mouse and 592 00:32:26,280 --> 00:32:29,120 Speaker 1: the laser that can cut through things nothing, you're a mouse. 593 00:32:29,240 --> 00:32:33,320 Speaker 1: Laser can cut through steel, horrey, you just never tried. Know. 594 00:32:33,480 --> 00:32:35,800 Speaker 1: The difference is just the intensity, right, the number of 595 00:32:35,880 --> 00:32:39,880 Speaker 1: photons per second. Photons have energy, and when something is 596 00:32:39,960 --> 00:32:42,480 Speaker 1: hit by a laser, they deposit their energy into whatever 597 00:32:42,600 --> 00:32:45,080 Speaker 1: is hit by it. If it's not a very bright laser, 598 00:32:45,360 --> 00:32:46,760 Speaker 1: then you're not I don't have a whole lot of 599 00:32:46,800 --> 00:32:50,280 Speaker 1: photons per second, then you're not depositing a lot of energy, right. 600 00:32:50,320 --> 00:32:52,960 Speaker 1: So that's why you can shine you know, a simple 601 00:32:53,080 --> 00:32:56,560 Speaker 1: laser pointer and as your skin and it doesn't burn, right, 602 00:32:57,080 --> 00:33:00,200 Speaker 1: But if you had ten thousand laser point and you 603 00:33:00,320 --> 00:33:01,840 Speaker 1: hit them all at the same place in your skin, 604 00:33:02,160 --> 00:33:05,040 Speaker 1: that would be the same as having one really powerful laser, 605 00:33:05,360 --> 00:33:07,280 Speaker 1: and yeah, you could cut a hole in yourself. So 606 00:33:07,520 --> 00:33:11,239 Speaker 1: cutting lasers are just lasers with a higher intensity UM 607 00:33:11,560 --> 00:33:13,719 Speaker 1: and they can have more photons per second and they 608 00:33:13,800 --> 00:33:15,760 Speaker 1: do that. How do you create more intensity? Do you 609 00:33:15,800 --> 00:33:19,000 Speaker 1: just pump the material more or do you do you 610 00:33:19,040 --> 00:33:20,640 Speaker 1: know what I mean? Like, what's the difference. If I 611 00:33:20,720 --> 00:33:23,320 Speaker 1: had the same material, how do I get more laser 612 00:33:23,360 --> 00:33:25,080 Speaker 1: out of it? Yeah, you can pump the material more, 613 00:33:25,120 --> 00:33:27,960 Speaker 1: you can have more material. Um you're gonna have you 614 00:33:28,360 --> 00:33:30,440 Speaker 1: must be must also have to do with how you 615 00:33:30,560 --> 00:33:34,320 Speaker 1: tune the one wayness of your one way mirror how much, 616 00:33:34,360 --> 00:33:37,080 Speaker 1: And that's that's some fracture of the energy out per second. 617 00:33:37,840 --> 00:33:39,600 Speaker 1: So there's probably lots of ways to do it. Well. 618 00:33:39,720 --> 00:33:42,840 Speaker 1: Lasers are everywhere in our lives. But I heard somebody 619 00:33:42,920 --> 00:33:46,240 Speaker 1: once told me that the biggest impact lasers have had 620 00:33:46,560 --> 00:33:50,520 Speaker 1: is in science, helping us make instruments to measure things 621 00:33:50,840 --> 00:33:54,800 Speaker 1: so that we can expand our knowledge about the universe. Um. Yeah, 622 00:33:55,560 --> 00:34:02,440 Speaker 1: lasers everywhere. Um, but I thought you were going to 623 00:34:02,480 --> 00:34:05,600 Speaker 1: say something about like laser lithography, like we can all 624 00:34:05,680 --> 00:34:08,920 Speaker 1: design our own cutting board logos and have lasers burn 625 00:34:09,000 --> 00:34:12,120 Speaker 1: them out. Yeah. No, the maker, the maker movement is 626 00:34:12,239 --> 00:34:15,239 Speaker 1: very grateful for lasers, but in the sense that you know, 627 00:34:15,400 --> 00:34:18,239 Speaker 1: like that's how we know for example, or initially that's 628 00:34:18,280 --> 00:34:21,520 Speaker 1: how we kind of figured out that the gravitational waves 629 00:34:21,600 --> 00:34:24,800 Speaker 1: measurement that depends on lasers, right, absolutely. Yeah. That uses 630 00:34:24,920 --> 00:34:28,160 Speaker 1: two lasers um in two different directions, and then you 631 00:34:28,239 --> 00:34:30,600 Speaker 1: shoot them away and they bounce back and use that 632 00:34:30,640 --> 00:34:32,480 Speaker 1: as a way to measure the distance. You count the 633 00:34:32,560 --> 00:34:35,400 Speaker 1: number of wiggles the laser has had. Yeah, Yeah, and 634 00:34:35,520 --> 00:34:38,520 Speaker 1: that's how they do a lot of like DNA studies, 635 00:34:38,640 --> 00:34:43,640 Speaker 1: and you can use lasers to figure out what materials 636 00:34:43,719 --> 00:34:46,360 Speaker 1: are made out of. So it's kind of in scientific 637 00:34:46,440 --> 00:34:49,960 Speaker 1: instrumentation has been a huge Lasers have had had a 638 00:34:50,200 --> 00:34:54,200 Speaker 1: huge impact, not just in like consumer products and death 639 00:34:54,320 --> 00:34:57,200 Speaker 1: rays that were never made, it's in science, right, it's 640 00:34:57,239 --> 00:35:01,000 Speaker 1: in its Lasers have really kind of boosted and amplified 641 00:35:01,440 --> 00:35:03,640 Speaker 1: what science can do. And that's right. Yeah, we're all 642 00:35:03,719 --> 00:35:07,759 Speaker 1: emitting more papers thanks to lasers. We're stimulated to emit 643 00:35:07,800 --> 00:35:10,279 Speaker 1: more papers. Yeah. Lasers also play a big role in 644 00:35:10,360 --> 00:35:13,239 Speaker 1: fusion research, as we were mentioning earlier. Um, you know 645 00:35:13,320 --> 00:35:16,080 Speaker 1: it's a powerful device, right, you have you have light 646 00:35:16,200 --> 00:35:18,600 Speaker 1: with a specific wavelength. You can focus at a very 647 00:35:18,640 --> 00:35:21,960 Speaker 1: specific spot and so it uh, and that's what scientists do, 648 00:35:22,040 --> 00:35:24,160 Speaker 1: you know, They think, how can I answer this question 649 00:35:24,239 --> 00:35:27,839 Speaker 1: with the tools I have? And that's a very specific tool. 650 00:35:27,880 --> 00:35:31,320 Speaker 1: It's like a tiny little science scalpel, right, and that 651 00:35:31,440 --> 00:35:34,520 Speaker 1: lets you sometimes cut problems open that you otherwise couldn't. Yeah. 652 00:35:35,000 --> 00:35:37,799 Speaker 1: So the next time you are at the grocery store 653 00:35:37,880 --> 00:35:41,040 Speaker 1: and are checking out and you hear that people, that's 654 00:35:41,040 --> 00:35:42,920 Speaker 1: a that's a laser at work. There there's a little 655 00:35:43,680 --> 00:35:49,160 Speaker 1: tiny death ray death ray to scan your your bananas. 656 00:35:49,680 --> 00:35:54,560 Speaker 1: That's right, you're fully operational grocery store uses lasers. Yeah, 657 00:35:55,040 --> 00:35:58,600 Speaker 1: all right. Well, I hope this discussion stimulated you and 658 00:36:00,160 --> 00:36:03,320 Speaker 1: made you focus with laser pocisition. And if you have 659 00:36:03,440 --> 00:36:06,080 Speaker 1: any questions, you can admit them to us. We'd love 660 00:36:06,160 --> 00:36:16,319 Speaker 1: to hear him see you next time. If you still 661 00:36:16,440 --> 00:36:19,360 Speaker 1: have a question after listening to all these explanations, please 662 00:36:19,680 --> 00:36:21,680 Speaker 1: drop us a line. We'd love to hear from you. 663 00:36:22,000 --> 00:36:24,799 Speaker 1: You can find us at Facebook, Twitter, and Instagram at 664 00:36:25,120 --> 00:36:28,239 Speaker 1: Daniel and Jorge that's one word, or email us at 665 00:36:28,560 --> 00:36:30,879 Speaker 1: Feedback at Daniel and Jorge dot com.