1 00:00:04,440 --> 00:00:12,400 Speaker 1: Welcome to tech Stuff, a production from iHeartRadio. Hey there, 2 00:00:12,480 --> 00:00:16,080 Speaker 1: and welcome to tech Stuff. I'm your host, Jonathan Strickland. 3 00:00:16,280 --> 00:00:19,479 Speaker 1: I'm an executive producer with iHeart Podcasts and How the 4 00:00:19,520 --> 00:00:22,279 Speaker 1: Tech Are You. It's a Friday. It's time for a 5 00:00:22,360 --> 00:00:25,759 Speaker 1: tech Stuff Classics episode, and that means we go back 6 00:00:25,800 --> 00:00:28,600 Speaker 1: into our archives and pick an episode to play for 7 00:00:28,680 --> 00:00:32,680 Speaker 1: your pleasure. This one originally published way back on June fourteenth, 8 00:00:32,760 --> 00:00:38,800 Speaker 1: twenty seventeen. It has the wonderful title Pew Pew Lasers Enjoy. 9 00:00:39,880 --> 00:00:41,880 Speaker 1: So we're going to talk about some pretty high tech 10 00:00:41,920 --> 00:00:44,360 Speaker 1: stuff today. Actually, I'm going to look at a topic 11 00:00:44,400 --> 00:00:47,600 Speaker 1: that we first addressed way back in twenty eleven with 12 00:00:47,760 --> 00:00:51,000 Speaker 1: the episode how Lasers Work. That's when Chris Palette, my 13 00:00:51,200 --> 00:00:54,360 Speaker 1: original co host, and I sat down and we talked 14 00:00:54,400 --> 00:00:56,640 Speaker 1: about a little bit of the history of lasers and 15 00:00:56,720 --> 00:00:59,880 Speaker 1: how they actually operate. But I thought it'd be better 16 00:01:00,040 --> 00:01:02,760 Speaker 1: to revisit this, explain it again, kind of take a 17 00:01:02,920 --> 00:01:07,880 Speaker 1: different approach to it. So, lasers are awesome and they 18 00:01:07,880 --> 00:01:10,800 Speaker 1: can do tons of different stuff. Right. We can do 19 00:01:10,880 --> 00:01:14,640 Speaker 1: everything from having a little laser pointer to amuse ourselves 20 00:01:14,640 --> 00:01:19,080 Speaker 1: and our pets to having a laser element inside optical 21 00:01:19,200 --> 00:01:22,080 Speaker 1: drive so that we can read information that's been stored 22 00:01:22,120 --> 00:01:26,840 Speaker 1: on a disc. To communications satellites, to propelling spacecraft to 23 00:01:26,920 --> 00:01:29,080 Speaker 1: cutting steel. There's all sorts of things we can do 24 00:01:29,080 --> 00:01:32,679 Speaker 1: with lasers. Oh, we can threaten our enemies. We can 25 00:01:32,680 --> 00:01:35,080 Speaker 1: tie them up and put them on a slab and 26 00:01:35,120 --> 00:01:38,720 Speaker 1: then slowly have a laser creep upward and then laugh 27 00:01:38,800 --> 00:01:41,640 Speaker 1: maniacally as we expect mister Bond to die. We can 28 00:01:41,680 --> 00:01:44,280 Speaker 1: do all that sort of stuff with lasers. So we're 29 00:01:44,280 --> 00:01:46,200 Speaker 1: going to talk about what they are, what they can do, 30 00:01:46,280 --> 00:01:49,400 Speaker 1: their history, and maybe some cool trivia about lasers as well, 31 00:01:49,840 --> 00:01:53,520 Speaker 1: and laser related stuff. So let's get to it now. 32 00:01:53,560 --> 00:01:58,200 Speaker 1: First of all, what is the technical definition of a laser? Well, 33 00:01:58,240 --> 00:02:01,240 Speaker 1: a laser is an acronym that means that it's a 34 00:02:01,280 --> 00:02:04,240 Speaker 1: word that's made up of the initials of other words, right, 35 00:02:04,520 --> 00:02:08,720 Speaker 1: so it stands for light amplification by stimulated emission of radiation. 36 00:02:09,600 --> 00:02:12,240 Speaker 1: But for most of us that doesn't really clear things up. 37 00:02:12,440 --> 00:02:15,239 Speaker 1: That just raises other questions like what do they mean 38 00:02:15,320 --> 00:02:19,480 Speaker 1: by stimulated emission of radiation? And how do you amplify light? 39 00:02:20,080 --> 00:02:22,800 Speaker 1: So I'm going to go in talk about all of 40 00:02:22,800 --> 00:02:25,040 Speaker 1: that kind of stuff because it's really fascinating. It involves 41 00:02:25,040 --> 00:02:28,079 Speaker 1: a lot of science and technology, two things I love 42 00:02:28,160 --> 00:02:33,960 Speaker 1: to talk about. The third thing obviously being Chaucer's Canterbury 43 00:02:34,080 --> 00:02:36,400 Speaker 1: tails one that I plicate with the shoulder asuta, but 44 00:02:36,440 --> 00:02:39,600 Speaker 1: that does not really fit with lasers. They didn't have 45 00:02:39,639 --> 00:02:42,720 Speaker 1: the laser's tail, so we're gonna skip Cannabar retails for 46 00:02:42,800 --> 00:02:45,480 Speaker 1: this episode. Now, a laser is a device that produces 47 00:02:45,520 --> 00:02:50,280 Speaker 1: a very narrow beam of light, and these beams are monochromatic. 48 00:02:50,360 --> 00:02:53,320 Speaker 1: That means they are single color see single wavelength. That's 49 00:02:53,320 --> 00:02:56,680 Speaker 1: a very specific wavelength of light for each laser and 50 00:02:56,720 --> 00:03:01,600 Speaker 1: thus a specific color. So we perceive different wavelengths of 51 00:03:01,680 --> 00:03:03,799 Speaker 1: light as different colors of light. So if you think 52 00:03:03,840 --> 00:03:09,880 Speaker 1: of your roy GVIV, that is actually a spectrum literally 53 00:03:09,960 --> 00:03:12,840 Speaker 1: a spectrum of colors. That's also a spectrum of wavelengths, 54 00:03:12,880 --> 00:03:16,440 Speaker 1: with red being the longest wavelength and violet being the 55 00:03:16,480 --> 00:03:22,799 Speaker 1: shortest wavelength. In the visible spectrum. The wavelength of light 56 00:03:23,320 --> 00:03:27,359 Speaker 1: depends entirely on the amount of energy electrons release within 57 00:03:27,720 --> 00:03:32,200 Speaker 1: the laser itself. So electrons release energy and in the 58 00:03:32,240 --> 00:03:35,520 Speaker 1: form of photons or light particles, and the color of 59 00:03:35,560 --> 00:03:38,520 Speaker 1: laser you get depends upon the amount of energy those 60 00:03:38,560 --> 00:03:41,440 Speaker 1: electrons are releasing, and the amount of energy they release 61 00:03:41,520 --> 00:03:43,960 Speaker 1: is dependent upon the type of atoms that they are 62 00:03:43,960 --> 00:03:47,600 Speaker 1: connected to, because it all has to do with orbits 63 00:03:47,720 --> 00:03:51,040 Speaker 1: of electrons around nuclei. More on that in a second. 64 00:03:51,200 --> 00:03:54,560 Speaker 1: So the light is also coherent. Now, that does not 65 00:03:54,720 --> 00:03:57,160 Speaker 1: mean it is able to hold a conversation and make 66 00:03:57,360 --> 00:04:00,800 Speaker 1: salient points. It's not that kind of co parent. It 67 00:04:00,880 --> 00:04:04,680 Speaker 1: means that the light is made up of organized photons. 68 00:04:05,640 --> 00:04:08,520 Speaker 1: Organized photons in this case means that they're all traveling 69 00:04:09,000 --> 00:04:11,760 Speaker 1: the same pattern of wavelength that are all in the 70 00:04:11,840 --> 00:04:15,440 Speaker 1: same page as it were. If you look at wavelength, 71 00:04:15,480 --> 00:04:18,200 Speaker 1: if you were to draw a series of waves, they 72 00:04:18,200 --> 00:04:21,200 Speaker 1: would all be lined up exactly, so all the crests 73 00:04:21,240 --> 00:04:24,080 Speaker 1: and the troughs would be lined up along the same points. 74 00:04:24,120 --> 00:04:28,160 Speaker 1: At any point along the wavelength, they would match entirely. 75 00:04:28,600 --> 00:04:31,960 Speaker 1: So that is what we mean by coherent. It's what 76 00:04:32,400 --> 00:04:36,279 Speaker 1: helps keep the light organized and moving in that specific 77 00:04:36,320 --> 00:04:38,960 Speaker 1: direction you want it to. And the light is also directional. 78 00:04:39,040 --> 00:04:42,040 Speaker 1: That means the beam is tight and concentrated and remains 79 00:04:42,040 --> 00:04:45,600 Speaker 1: so over great distances. You don't get a lot of 80 00:04:46,680 --> 00:04:51,600 Speaker 1: light diverging from that pathway, and some lasers are able 81 00:04:51,600 --> 00:04:56,080 Speaker 1: to project for miles in miles, like hundreds of thousands 82 00:04:56,120 --> 00:05:00,680 Speaker 1: of miles in some cases, or without having any kind 83 00:05:00,680 --> 00:05:03,160 Speaker 1: of degradation of the beam, which is kind of cool. 84 00:05:03,240 --> 00:05:05,480 Speaker 1: I mean, it's amazingly cool. Now you can trast that 85 00:05:05,520 --> 00:05:09,240 Speaker 1: with something like a flashlight. Flashlights have a beam that 86 00:05:09,440 --> 00:05:11,680 Speaker 1: spreads out as it travels out we're from its source, 87 00:05:11,880 --> 00:05:15,599 Speaker 1: it diffuses, so it's different from a laser. It doesn't 88 00:05:15,640 --> 00:05:18,760 Speaker 1: have the coherence that a laser would have. This is 89 00:05:18,800 --> 00:05:23,159 Speaker 1: typical of most light sources. You don't find lasers in nature. 90 00:05:23,600 --> 00:05:28,360 Speaker 1: Lasers are something that we have caused to happen because 91 00:05:28,400 --> 00:05:31,039 Speaker 1: of the natural laws. If it weren't for the natural laws, 92 00:05:31,120 --> 00:05:34,839 Speaker 1: lasers wouldn't work. Obviously we didn't create that out of 93 00:05:34,880 --> 00:05:39,839 Speaker 1: whole cloth. But it doesn't spontaneously happen in nature because 94 00:05:39,839 --> 00:05:43,080 Speaker 1: you have to have very specific parameters set up in 95 00:05:43,200 --> 00:05:48,279 Speaker 1: order to generate a laser beam. Now, to understand why 96 00:05:48,440 --> 00:05:50,160 Speaker 1: it works the way it does, it helps to know 97 00:05:50,200 --> 00:05:52,760 Speaker 1: how light works. Now, light behaves both as a wave 98 00:05:52,800 --> 00:05:55,520 Speaker 1: and a particle, but for this bit of the explanation, 99 00:05:55,560 --> 00:05:58,159 Speaker 1: we're mostly concerned with wave physics, even though we'll be 100 00:05:58,160 --> 00:06:01,440 Speaker 1: talking about photons, the basic unit of light, the basic 101 00:06:01,480 --> 00:06:04,680 Speaker 1: particle of light a lot in this episode. So a 102 00:06:04,760 --> 00:06:08,200 Speaker 1: light source gives off waves of light, and different colors 103 00:06:08,200 --> 00:06:11,320 Speaker 1: of light have different wavelengths. Like I said, you know, 104 00:06:11,360 --> 00:06:14,479 Speaker 1: those red wavelengths are longer than the orange ones, Infrared 105 00:06:14,520 --> 00:06:18,160 Speaker 1: waves are even longer, Ultraviolet are even shorter than violet, 106 00:06:18,480 --> 00:06:23,360 Speaker 1: So you've got that different spectrum of wavelengths there. When 107 00:06:23,400 --> 00:06:26,360 Speaker 1: you get down to that violet, you're really looking at 108 00:06:26,360 --> 00:06:29,800 Speaker 1: the shortest wavelengths that we can perceive before it just 109 00:06:29,839 --> 00:06:32,880 Speaker 1: becomes invisible to us. So again ultraviolet, we can't see that. 110 00:06:34,520 --> 00:06:38,080 Speaker 1: Certain classes in dungeons and dragons different They can see ultravioletlight, 111 00:06:38,760 --> 00:06:42,760 Speaker 1: not the rest of us. So these waves travel typically 112 00:06:42,960 --> 00:06:46,040 Speaker 1: out of phase from each other from normal light sources. 113 00:06:46,120 --> 00:06:48,800 Speaker 1: So again, if you were to chart those wavelengths, the 114 00:06:48,960 --> 00:06:53,480 Speaker 1: crests and valleys would of each individual photon wouldn't match 115 00:06:53,600 --> 00:06:57,320 Speaker 1: up right, like the crest of one might be matched 116 00:06:57,320 --> 00:07:00,520 Speaker 1: with the valley of another or somewhere else along its waylength. 117 00:07:00,839 --> 00:07:04,120 Speaker 1: They wouldn't be moving in phase, they'd be out of phase. 118 00:07:04,680 --> 00:07:08,960 Speaker 1: So lasers all line up those light waves at the 119 00:07:09,040 --> 00:07:12,240 Speaker 1: same way. So that they are in phase. And that's 120 00:07:12,320 --> 00:07:15,120 Speaker 1: what we mean when we say coherent, that the various 121 00:07:15,160 --> 00:07:18,120 Speaker 1: photons are all in phase with one another. And the 122 00:07:18,160 --> 00:07:22,800 Speaker 1: way you generate lasers makes this happen. It's kind of cool. 123 00:07:22,840 --> 00:07:26,120 Speaker 1: We'll talk about that again a little bit later. But 124 00:07:26,200 --> 00:07:29,760 Speaker 1: all of the photons in the beam have unified wave fronts, 125 00:07:29,880 --> 00:07:33,440 Speaker 1: so they're all moving in exactly the same wavelength at 126 00:07:33,440 --> 00:07:37,520 Speaker 1: exactly the same time. Now, to understand how all of 127 00:07:37,600 --> 00:07:41,600 Speaker 1: this works, it takes a looking at atoms. We have 128 00:07:41,640 --> 00:07:43,960 Speaker 1: to go back to basic science. So let's take a 129 00:07:43,960 --> 00:07:45,800 Speaker 1: look at an atom. Now. Back in the day when 130 00:07:45,840 --> 00:07:50,320 Speaker 1: I was in school, atoms were depicted as being kind 131 00:07:50,320 --> 00:07:52,400 Speaker 1: of like the orbits of planets, where you would have 132 00:07:52,440 --> 00:07:54,640 Speaker 1: a nucleus in the center, kind of like the Sun, 133 00:07:54,880 --> 00:07:59,400 Speaker 1: and electrons would orbit in neat little circles around at 134 00:07:59,400 --> 00:08:03,480 Speaker 1: specific distances from the nucleus. As it turns out, things 135 00:08:03,520 --> 00:08:06,560 Speaker 1: aren't quite so neat, and simple electrons are in an 136 00:08:06,600 --> 00:08:10,600 Speaker 1: electron cloud that are around the nucleus. It is impossible 137 00:08:10,920 --> 00:08:15,920 Speaker 1: to say with complete certainty where an electron is at 138 00:08:15,960 --> 00:08:18,280 Speaker 1: any given moment. You know, you can know a position 139 00:08:18,320 --> 00:08:21,000 Speaker 1: of an electron, but not it's direction. Or vice versa 140 00:08:21,160 --> 00:08:24,480 Speaker 1: with complete certainty. Heisenberg's n certainty principle is a fun thing. 141 00:08:24,960 --> 00:08:29,400 Speaker 1: But you know, when you have a basic atom and 142 00:08:29,440 --> 00:08:32,240 Speaker 1: you haven't added any energy to the atom in its 143 00:08:33,280 --> 00:08:36,320 Speaker 1: ground state energy level, that's when it's just, you know, 144 00:08:36,480 --> 00:08:41,280 Speaker 1: kind of chilling. Atoms are always in motion. You only 145 00:08:41,280 --> 00:08:45,120 Speaker 1: get atoms in no motion at all at absolute zero, 146 00:08:46,000 --> 00:08:48,080 Speaker 1: when you're at zero kelvin. That is when you have 147 00:08:48,960 --> 00:08:52,640 Speaker 1: zero atomic movement. But otherwise, atoms are always in motion. 148 00:08:52,720 --> 00:08:56,600 Speaker 1: Even in solid objects, they're just not moving a lot. 149 00:08:57,040 --> 00:08:59,640 Speaker 1: When you add energy to atoms, they move more. They 150 00:09:00,080 --> 00:09:03,960 Speaker 1: start to get energized. When you energize atoms enough, you 151 00:09:04,000 --> 00:09:06,960 Speaker 1: can boost them to an excited level. Now, typically you 152 00:09:07,000 --> 00:09:11,000 Speaker 1: do this by applying energy like heat, light or electricity 153 00:09:11,040 --> 00:09:14,320 Speaker 1: to the atom, Whereas if you want to excite me, 154 00:09:14,400 --> 00:09:16,640 Speaker 1: you just say, hey, they might be giants's coming to town. 155 00:09:16,640 --> 00:09:18,760 Speaker 1: You want to go see them? And I'm like, yeah, totally. 156 00:09:19,440 --> 00:09:22,160 Speaker 1: So you've got atom which consists of that nucleus, and 157 00:09:22,160 --> 00:09:25,520 Speaker 1: you've got the electron cloud around it. When you apply energy, 158 00:09:25,640 --> 00:09:29,960 Speaker 1: it causes the electrons to move to a higher orbit 159 00:09:30,160 --> 00:09:33,640 Speaker 1: around that nucleus. Again, since we're talking about a cloud, 160 00:09:33,679 --> 00:09:36,839 Speaker 1: and not just a simple orbit circle. You can think 161 00:09:36,880 --> 00:09:39,320 Speaker 1: of it as meaning the electrons move a little further 162 00:09:39,520 --> 00:09:42,960 Speaker 1: away from the nucleus. If you add enough energy, you 163 00:09:43,000 --> 00:09:46,840 Speaker 1: can strip electrons away from the atom entirely. This will 164 00:09:46,880 --> 00:09:52,400 Speaker 1: create a charged atom because you will now have an ion. 165 00:09:53,400 --> 00:09:56,160 Speaker 1: It's going to have a net positive charge because you're 166 00:09:56,160 --> 00:09:58,600 Speaker 1: going to have protons there and you've pulled away some 167 00:09:58,640 --> 00:10:01,360 Speaker 1: of the electrons, so you've taken some of that balance out. 168 00:10:02,400 --> 00:10:05,200 Speaker 1: If you add enough electric enough energy, I was about 169 00:10:05,200 --> 00:10:08,199 Speaker 1: to say electricity, but really energy. Electricity is one form 170 00:10:08,280 --> 00:10:10,240 Speaker 1: of energy you could add to the atom in order 171 00:10:10,280 --> 00:10:12,720 Speaker 1: to do this. But if you didn't add that much, 172 00:10:12,960 --> 00:10:15,600 Speaker 1: like if you added enough to excite the electrons but 173 00:10:15,679 --> 00:10:19,440 Speaker 1: not strip them away from the nucleus. When you remove 174 00:10:19,640 --> 00:10:23,400 Speaker 1: that source of energy, the electrons will move back down 175 00:10:23,440 --> 00:10:27,040 Speaker 1: to their ground state. They do not quote unquote want 176 00:10:27,280 --> 00:10:30,319 Speaker 1: to be at that excited level. They have a ground 177 00:10:30,320 --> 00:10:33,840 Speaker 1: state that they are naturally inclined to be at. But 178 00:10:34,440 --> 00:10:38,760 Speaker 1: they've absorbed energy. So in order to move back down 179 00:10:38,800 --> 00:10:43,080 Speaker 1: to their normal energy level, they have to give up 180 00:10:43,559 --> 00:10:46,120 Speaker 1: some of the energy that they've absorbed, and they do 181 00:10:46,200 --> 00:10:50,600 Speaker 1: this through emitting a photon. That basic unit of light, 182 00:10:51,600 --> 00:10:54,560 Speaker 1: and once they emit that photon, that's what allows them 183 00:10:54,600 --> 00:10:58,200 Speaker 1: to move back to their ground energy state because they 184 00:10:58,360 --> 00:11:02,520 Speaker 1: no longer have that excess energy inside of themselves. So 185 00:11:03,280 --> 00:11:05,280 Speaker 1: you can think of it as almost being like the 186 00:11:05,440 --> 00:11:08,880 Speaker 1: electron is too full, like it's eaten too much, and 187 00:11:08,920 --> 00:11:12,960 Speaker 1: then it has a little belchi belch or something it 188 00:11:13,040 --> 00:11:17,040 Speaker 1: manages to emit some part of that energy. It is absorbed, 189 00:11:17,160 --> 00:11:19,559 Speaker 1: and now it's feeling more like its old self again, 190 00:11:20,080 --> 00:11:21,880 Speaker 1: and then you can just boost it back up again 191 00:11:21,880 --> 00:11:28,120 Speaker 1: if you want to. So photons are emitted this way 192 00:11:28,200 --> 00:11:31,560 Speaker 1: through in lasers, but that's not the only way we 193 00:11:32,040 --> 00:11:36,920 Speaker 1: generate photons, like there are very specific ways of doing 194 00:11:36,960 --> 00:11:40,920 Speaker 1: this in all sorts of applications, and many of them 195 00:11:41,080 --> 00:11:44,280 Speaker 1: are pretty basic. Like your incandescent light bulb uses the 196 00:11:44,360 --> 00:11:48,680 Speaker 1: same principle. You run an electric current through some wire 197 00:11:49,000 --> 00:11:53,160 Speaker 1: a filament, typically in a vacuum sealed tube a bulb, 198 00:11:54,240 --> 00:11:59,200 Speaker 1: and running the electric current causes the filament to heat 199 00:11:59,280 --> 00:12:03,160 Speaker 1: up because as resistance to electrical current, so some of 200 00:12:03,160 --> 00:12:07,240 Speaker 1: that electricity gets converted over into heat. As this heats up, 201 00:12:07,280 --> 00:12:11,240 Speaker 1: it excites the atoms within that filament, and as that 202 00:12:11,480 --> 00:12:15,959 Speaker 1: energy source moves through it allows those electrons to come 203 00:12:16,000 --> 00:12:19,720 Speaker 1: back down, the atoms begin to emit photons, and then 204 00:12:19,760 --> 00:12:22,440 Speaker 1: you get this glow. In the case of light bulbs, 205 00:12:22,440 --> 00:12:24,920 Speaker 1: the glow creates the light you would have from an 206 00:12:24,960 --> 00:12:28,320 Speaker 1: incandescent bulb. You could also see the same thing with 207 00:12:28,400 --> 00:12:30,360 Speaker 1: heating elements, Like if you were to look inside a 208 00:12:30,360 --> 00:12:32,560 Speaker 1: toaster and you see that orange glow, Well, that orange 209 00:12:32,559 --> 00:12:36,199 Speaker 1: glow is coming from the heating elements that have had 210 00:12:36,240 --> 00:12:39,120 Speaker 1: their atoms excited. The electrons got boosted to a higher 211 00:12:39,240 --> 00:12:43,199 Speaker 1: energy level and then they came down and started releasing photons. 212 00:12:43,679 --> 00:12:46,920 Speaker 1: So it's not just lasers that do this, but lasers 213 00:12:47,200 --> 00:12:49,319 Speaker 1: take advantage of it in a very specific way. That's 214 00:12:49,320 --> 00:12:54,560 Speaker 1: pretty cool. I am interrupting this laser focused episode, uh 215 00:12:54,600 --> 00:12:57,440 Speaker 1: huh unintended in order for us to take a quick 216 00:12:57,480 --> 00:13:09,679 Speaker 1: break to think our sponsors. So, a laser uses this 217 00:13:09,720 --> 00:13:12,480 Speaker 1: principle to create those narrow beams of light. And here's 218 00:13:12,800 --> 00:13:15,720 Speaker 1: how they do it. First, you need what is called 219 00:13:15,720 --> 00:13:19,840 Speaker 1: a lasing medium. A laser medium, this is the stuff 220 00:13:20,200 --> 00:13:22,600 Speaker 1: that you're going to use to excite. You know, you're 221 00:13:22,640 --> 00:13:24,840 Speaker 1: gonna excite the atoms in this stuff so that it 222 00:13:25,000 --> 00:13:28,480 Speaker 1: generates the wavelength of light that you want, and so 223 00:13:28,559 --> 00:13:31,440 Speaker 1: the type of stuff you use that's going to determine 224 00:13:31,480 --> 00:13:34,400 Speaker 1: the type of atoms that are present, which in turn 225 00:13:34,600 --> 00:13:38,079 Speaker 1: determines the energy levels of the electrons, which in turn 226 00:13:38,200 --> 00:13:42,480 Speaker 1: determines what color light you're gonna get through the lasing medium. 227 00:13:42,679 --> 00:13:47,400 Speaker 1: All of this is dependent upon, ultimately the source of 228 00:13:47,440 --> 00:13:52,040 Speaker 1: the lasing medium, like what is that material? The lasing 229 00:13:52,080 --> 00:13:55,880 Speaker 1: medium acts like an amplifier, only this is for optics 230 00:13:55,960 --> 00:13:58,800 Speaker 1: rather than for acoustics. So some people call the lasing 231 00:13:58,840 --> 00:14:02,760 Speaker 1: medium the game medium or the source of optical gain 232 00:14:02,840 --> 00:14:06,360 Speaker 1: because it's like a microphone gain setting. It is amplifying 233 00:14:06,400 --> 00:14:09,080 Speaker 1: a signal, but in this case it's amplifying light, not 234 00:14:09,240 --> 00:14:15,079 Speaker 1: amplifying sound. The gain in this case is that stimulated 235 00:14:15,120 --> 00:14:17,679 Speaker 1: emission of photons I was talking about, and the emission 236 00:14:17,760 --> 00:14:23,000 Speaker 1: is stimulated through an interesting series of events. You start 237 00:14:23,560 --> 00:14:28,560 Speaker 1: by initially adding energy to the lasing medium, and then 238 00:14:28,880 --> 00:14:33,520 Speaker 1: the photons it emits end up stimulating other atoms inside 239 00:14:33,520 --> 00:14:36,520 Speaker 1: the lasing medium that have already been excited, and then 240 00:14:36,600 --> 00:14:41,040 Speaker 1: you get a steady stream of photons that create your 241 00:14:41,120 --> 00:14:45,520 Speaker 1: laser beam. But first you have to add energy into 242 00:14:45,520 --> 00:14:47,640 Speaker 1: the system. You do this from what is called a 243 00:14:47,720 --> 00:14:52,640 Speaker 1: pump source because you are pumping energy into the lasing medium. 244 00:14:53,040 --> 00:14:57,120 Speaker 1: So basically, you pump energy into this medium, you excite 245 00:14:57,120 --> 00:15:02,040 Speaker 1: some atoms. Those excited atoms start to emit photons. Those 246 00:15:02,040 --> 00:15:08,920 Speaker 1: photons will start to hit other stimulated atoms and that's 247 00:15:08,920 --> 00:15:13,000 Speaker 1: where you get this stimulated emission. So there are lots 248 00:15:13,040 --> 00:15:16,160 Speaker 1: of different types of lasing media. So, for example, there 249 00:15:16,160 --> 00:15:20,000 Speaker 1: are certain crystals that can serve as a medium. The 250 00:15:20,040 --> 00:15:26,120 Speaker 1: earliest lasers were ruby lasers, so you would get a 251 00:15:26,160 --> 00:15:29,640 Speaker 1: ruby crystal and that would be your lasing medium. You 252 00:15:29,640 --> 00:15:34,480 Speaker 1: would usually introduce some impurities. It's called doping. You add 253 00:15:34,480 --> 00:15:37,840 Speaker 1: some impurities to the material in order to make this 254 00:15:37,920 --> 00:15:41,000 Speaker 1: a more efficient lasing medium. Usually it's some ions of 255 00:15:41,040 --> 00:15:45,360 Speaker 1: some sort and that helps when you are actually getting 256 00:15:45,400 --> 00:15:50,120 Speaker 1: to the part of generating a laser. Those are specifically 257 00:15:50,160 --> 00:15:53,240 Speaker 1: solid state lasers, the ones that use crystals. You're using 258 00:15:53,360 --> 00:15:57,720 Speaker 1: a solid lasing medium. But there are other ones as well. 259 00:15:57,720 --> 00:16:01,440 Speaker 1: There's some that use glasses. Some that you gases, including 260 00:16:01,480 --> 00:16:05,480 Speaker 1: reactive gases like chlorine and fluorine. Those are specific types 261 00:16:05,520 --> 00:16:09,280 Speaker 1: of gas lasers that are called exemer lasers. You have 262 00:16:09,360 --> 00:16:13,480 Speaker 1: semiconductor lasers, which produce in the grand scheme of things. 263 00:16:13,520 --> 00:16:17,200 Speaker 1: Fairly weak lasers, but they also are fairly inexpensive to produce, 264 00:16:18,080 --> 00:16:19,760 Speaker 1: and those are the ones that we use in things 265 00:16:19,800 --> 00:16:23,280 Speaker 1: like CD players, DVD players, blu ray players, that kind 266 00:16:23,280 --> 00:16:26,560 Speaker 1: of stuff. They tend to be semiconductor lasers. They're easy 267 00:16:26,600 --> 00:16:29,200 Speaker 1: to mass produce, they're less expensive, and they aren't so 268 00:16:29,360 --> 00:16:31,800 Speaker 1: powerful as to cause problems. You don't need a CD 269 00:16:31,920 --> 00:16:35,640 Speaker 1: player laser that could burn a hole through the surface 270 00:16:35,640 --> 00:16:39,080 Speaker 1: of the Earth. That would be ridiculous. You can also 271 00:16:39,720 --> 00:16:44,840 Speaker 1: get liquid medium lasers. These are liquids that have various 272 00:16:45,000 --> 00:16:52,320 Speaker 1: organic dyes, special organic dyes, dyes that will allow for 273 00:16:52,360 --> 00:16:57,720 Speaker 1: this stimulated emission of light amplified light. Now, the pump 274 00:16:57,880 --> 00:17:00,040 Speaker 1: is some sort of energy transfer that you use to 275 00:17:00,080 --> 00:17:02,040 Speaker 1: excite those atoms in the first place, so that they'll 276 00:17:02,040 --> 00:17:07,320 Speaker 1: emit those initial photons when the electrons calm the heck down. 277 00:17:08,040 --> 00:17:13,320 Speaker 1: Laser pumps are some form of external source of energy. Typically, 278 00:17:13,480 --> 00:17:17,080 Speaker 1: they supply energy in the form of either electricity or light, 279 00:17:17,240 --> 00:17:21,680 Speaker 1: but there are other means of pumping a lasing medium 280 00:17:21,680 --> 00:17:26,359 Speaker 1: with energy to create lasers. Light and electricity are the 281 00:17:26,400 --> 00:17:29,879 Speaker 1: two most common ones, but they are not the only kinds. 282 00:17:29,880 --> 00:17:32,679 Speaker 1: There are some that use chemical reactions. There are some 283 00:17:32,800 --> 00:17:36,280 Speaker 1: that even use nuclear reactions, which I think is taking 284 00:17:36,320 --> 00:17:39,520 Speaker 1: it a little far if you're asking me, that's me 285 00:17:39,640 --> 00:17:43,199 Speaker 1: mostly being tongue in cheek. But again, most of the 286 00:17:43,240 --> 00:17:46,120 Speaker 1: lasers that we would encounter throughout our day, those are 287 00:17:46,160 --> 00:17:52,479 Speaker 1: generated either through light or through electricity stimulating the lasing medium. So, 288 00:17:54,400 --> 00:17:57,520 Speaker 1: for example, most early lasers were using some form of 289 00:17:57,840 --> 00:18:02,960 Speaker 1: arc or flash lamp to stack emulate that initial reaction 290 00:18:03,520 --> 00:18:07,160 Speaker 1: within the atoms of the lasing medium, like a crystal rod. 291 00:18:08,160 --> 00:18:10,440 Speaker 1: So you got your crystal rod with a few impurities 292 00:18:10,440 --> 00:18:12,359 Speaker 1: in it that you have specifically placed in there. You 293 00:18:12,400 --> 00:18:17,280 Speaker 1: have doped this crystal rod. You would wrap a light 294 00:18:17,840 --> 00:18:24,240 Speaker 1: source around this thing, usually within some sort of mirrored chamber, 295 00:18:25,080 --> 00:18:29,640 Speaker 1: and you would flash light in pulses against the lasing medium, 296 00:18:30,640 --> 00:18:34,560 Speaker 1: and this would actually excite atoms within the medium, which 297 00:18:34,560 --> 00:18:38,959 Speaker 1: would then give off photons. Now, if there were no 298 00:18:39,119 --> 00:18:43,800 Speaker 1: way for you to keep this reaction going, it would 299 00:18:43,840 --> 00:18:47,040 Speaker 1: be such a small emission of photons that you probably 300 00:18:47,040 --> 00:18:49,640 Speaker 1: wouldn't even be able to tell you wouldn't it wouldn't 301 00:18:49,680 --> 00:18:54,040 Speaker 1: be visible to you. However, by tricking it, you can 302 00:18:54,119 --> 00:18:57,160 Speaker 1: totally make it visible. So you typically would use these 303 00:18:57,160 --> 00:19:00,639 Speaker 1: mirrors to reflect light back into the lasing medium. That 304 00:19:00,720 --> 00:19:05,800 Speaker 1: includes photons that were emitted during that initial flash, and 305 00:19:05,840 --> 00:19:08,840 Speaker 1: that's what allows you to create a cascade effect and 306 00:19:09,400 --> 00:19:13,879 Speaker 1: create a laser. Generally speaking, you would probably use mirrors 307 00:19:13,880 --> 00:19:17,320 Speaker 1: that would allow the reflection of any wavelengths of light 308 00:19:17,400 --> 00:19:21,239 Speaker 1: that were shorter than the laser's wavelength would be, and 309 00:19:21,280 --> 00:19:26,760 Speaker 1: allow the transference of light that is longer wavelengths longer 310 00:19:26,800 --> 00:19:30,040 Speaker 1: than the laser's wavelength that you want. The reason for 311 00:19:30,080 --> 00:19:32,320 Speaker 1: that is that if you were to trap all the 312 00:19:32,400 --> 00:19:35,800 Speaker 1: light within the chamber, you could cause things to heat 313 00:19:35,880 --> 00:19:39,480 Speaker 1: up and create what's called thermal lensing. The actual change 314 00:19:39,480 --> 00:19:43,480 Speaker 1: in temperature would create a lens effect that would end 315 00:19:43,560 --> 00:19:47,280 Speaker 1: up affecting the ability of a laser to be directional 316 00:19:47,320 --> 00:19:49,920 Speaker 1: and coherent. And obviously, if that's your intent, you don't 317 00:19:49,920 --> 00:19:53,520 Speaker 1: want that to happen. So, yeah, Thermal lensing occurs when 318 00:19:53,520 --> 00:19:56,000 Speaker 1: a sample absorbs energy from a laser beam, it heats up, 319 00:19:56,040 --> 00:20:00,240 Speaker 1: it creates this refractive lens that causes beam divergence. That's 320 00:20:00,280 --> 00:20:02,400 Speaker 1: not what you want with a laser typically, I mean 321 00:20:02,440 --> 00:20:05,840 Speaker 1: you might want to design a system that creates that 322 00:20:05,920 --> 00:20:09,399 Speaker 1: splits a beam but that's different from beam divergence. You 323 00:20:09,480 --> 00:20:13,560 Speaker 1: want that beam to be nice and tight, typically or 324 00:20:13,240 --> 00:20:19,400 Speaker 1: your average laser applications. So let's imagine that we're building 325 00:20:19,400 --> 00:20:23,440 Speaker 1: a laser and we start with a rod made out 326 00:20:23,720 --> 00:20:26,639 Speaker 1: of ruby. I was gonna say that you could have 327 00:20:26,640 --> 00:20:29,720 Speaker 1: a ruby rod, but we all know that he is 328 00:20:29,760 --> 00:20:33,679 Speaker 1: busy with Corbyn Dallas trying to save the universe. A 329 00:20:33,720 --> 00:20:35,640 Speaker 1: shout out to any of you guys out there who 330 00:20:35,720 --> 00:20:40,600 Speaker 1: understand what that reference means. So you've got ruby rod, 331 00:20:40,840 --> 00:20:44,760 Speaker 1: and you've got a flash tube that is probably wrapped 332 00:20:44,760 --> 00:20:48,520 Speaker 1: around the ruby rod, but at least is shining can 333 00:20:48,600 --> 00:20:51,040 Speaker 1: shine on the ruby rod, and you can use the 334 00:20:51,040 --> 00:20:54,439 Speaker 1: flash tube out of like a camera. In fact, the 335 00:20:54,520 --> 00:20:59,840 Speaker 1: earliest lasers we're using camera flash bulbs as the source 336 00:20:59,840 --> 00:21:02,400 Speaker 1: of light to start this reaction. It's not like it's 337 00:21:02,440 --> 00:21:06,640 Speaker 1: something super high tech. It's actually pretty cool. And you've 338 00:21:06,640 --> 00:21:10,600 Speaker 1: got a mirrored chamber that surrounds the whole thing on 339 00:21:10,760 --> 00:21:13,639 Speaker 1: the on either end of the rod. So think of 340 00:21:13,680 --> 00:21:17,239 Speaker 1: the rod as like a cylinder. You have put a 341 00:21:17,320 --> 00:21:21,399 Speaker 1: silvered mirror on either end. One side is a pure 342 00:21:21,480 --> 00:21:25,040 Speaker 1: silvered mirror, so it just reflects light. The other one 343 00:21:25,119 --> 00:21:28,600 Speaker 1: is a partially silvered mirror, meaning that it can allow 344 00:21:28,680 --> 00:21:31,879 Speaker 1: some light to pass through. Specifically, you want to design 345 00:21:31,960 --> 00:21:35,040 Speaker 1: it so it allows the wavelength of the laser light 346 00:21:35,119 --> 00:21:37,600 Speaker 1: to pass through, but doesn't allow any other light to 347 00:21:37,600 --> 00:21:43,240 Speaker 1: pass through. You turn on the flash tube. This shines 348 00:21:43,280 --> 00:21:45,879 Speaker 1: bright light onto the rod, which causes some of the 349 00:21:45,880 --> 00:21:50,120 Speaker 1: atoms in the rod to excite. Then, as those electrons 350 00:21:50,200 --> 00:21:53,080 Speaker 1: move back down from their excited stage back to the 351 00:21:53,119 --> 00:21:57,800 Speaker 1: ground level stage, they release photons, and with enough energy 352 00:21:57,840 --> 00:22:00,800 Speaker 1: pumped into the medium, you end up with a larger 353 00:22:00,880 --> 00:22:05,080 Speaker 1: population of atoms that are in an excited state than 354 00:22:05,119 --> 00:22:08,040 Speaker 1: there are atoms in the ground state. When you reach 355 00:22:08,160 --> 00:22:12,840 Speaker 1: that point, it is called a population inversion because you've 356 00:22:12,880 --> 00:22:17,720 Speaker 1: inverted the relationship between excited atoms and ground state atoms. 357 00:22:17,760 --> 00:22:21,280 Speaker 1: Typically you would have more ground state atoms than excited ones. 358 00:22:21,760 --> 00:22:23,920 Speaker 1: Once you're able to flip that balance, you can create 359 00:22:23,960 --> 00:22:28,120 Speaker 1: this cascading effect that I've been talking about. So you've 360 00:22:28,160 --> 00:22:31,560 Speaker 1: got more excited atoms than you have ground energy level 361 00:22:31,560 --> 00:22:35,320 Speaker 1: atoms inside of this lazing medium. At that point they 362 00:22:35,320 --> 00:22:39,840 Speaker 1: start giving off photons, and this is pretty cool. What 363 00:22:39,960 --> 00:22:47,160 Speaker 1: happens next is photons from some of those first atoms 364 00:22:47,160 --> 00:22:49,800 Speaker 1: that had been excited and then were calming down. If 365 00:22:49,840 --> 00:22:54,400 Speaker 1: you like, they'll go out and they'll hit other excited atoms. 366 00:22:54,640 --> 00:22:56,720 Speaker 1: So these are atoms that I've already had their energy 367 00:22:56,800 --> 00:23:03,000 Speaker 1: levels boosted by that flash bulb. The photon from the 368 00:23:03,000 --> 00:23:08,240 Speaker 1: first atom, the one that excited and calmed down, has 369 00:23:08,440 --> 00:23:12,200 Speaker 1: just the right amount of energy to cause the electron 370 00:23:12,400 --> 00:23:14,639 Speaker 1: in an excited atom to come back down to its 371 00:23:14,680 --> 00:23:19,119 Speaker 1: ground state and release another photon. So what happens is 372 00:23:19,160 --> 00:23:23,560 Speaker 1: the atom that it it connects with will absorb the photon, 373 00:23:24,080 --> 00:23:27,000 Speaker 1: then it will emit the photon and emit a second 374 00:23:27,080 --> 00:23:31,040 Speaker 1: photon as its own electron comes down an energy level. 375 00:23:31,280 --> 00:23:35,520 Speaker 1: So you get two photons emitted, the initial one that 376 00:23:35,600 --> 00:23:39,320 Speaker 1: you shot the atom with and then the one that 377 00:23:39,320 --> 00:23:42,400 Speaker 1: that atom produced itself. So this is what is called 378 00:23:42,480 --> 00:23:46,959 Speaker 1: light amplification. Right, you have amplified the light. You started 379 00:23:47,000 --> 00:23:50,080 Speaker 1: with one photon. Now you have two photons and they're 380 00:23:50,119 --> 00:23:54,879 Speaker 1: moving in phase with one another because well, because of 381 00:23:54,960 --> 00:23:56,719 Speaker 1: quantum physics, but I don't want to get into that 382 00:23:56,760 --> 00:24:02,879 Speaker 1: too much. So you get this light amplification through that process. 383 00:24:04,720 --> 00:24:07,159 Speaker 1: Now that you have the light amplification, you might as 384 00:24:07,160 --> 00:24:10,240 Speaker 1: well say, like, well, what are we calling this this 385 00:24:10,280 --> 00:24:14,000 Speaker 1: whole process where a photon can cause another atom to 386 00:24:14,119 --> 00:24:17,560 Speaker 1: emit a photon. That's the stimulated emission. You might think 387 00:24:17,560 --> 00:24:20,200 Speaker 1: stimulated emission was when you turned on the flash bulb. 388 00:24:20,240 --> 00:24:24,400 Speaker 1: That's not technically correct. The stimulated emission part technically comes 389 00:24:24,800 --> 00:24:29,200 Speaker 1: from these initial atoms that release photons, and those cause 390 00:24:29,280 --> 00:24:32,600 Speaker 1: this chain reaction in the lasing medium. So this can 391 00:24:32,640 --> 00:24:35,040 Speaker 1: happen over and over and over again. Right, you're not 392 00:24:35,119 --> 00:24:38,440 Speaker 1: really the atoms aren't losing any matter in this. It's 393 00:24:38,600 --> 00:24:41,359 Speaker 1: just a process of electrons being boosted up to an 394 00:24:41,440 --> 00:24:43,920 Speaker 1: energy level and then coming back down again, so they're 395 00:24:43,960 --> 00:24:48,600 Speaker 1: releasing energy. They're not losing anything in this. It's just 396 00:24:48,640 --> 00:24:53,000 Speaker 1: a transfer of energy and really a transformation of it 397 00:24:53,160 --> 00:24:58,600 Speaker 1: from one form of light to another. So it's fascinating 398 00:24:58,880 --> 00:25:01,800 Speaker 1: to me that this is something that not only works, 399 00:25:01,840 --> 00:25:04,399 Speaker 1: but that people were able to figure out would work. 400 00:25:05,680 --> 00:25:11,600 Speaker 1: It's so far into quantum physics and optics and photonics 401 00:25:11,640 --> 00:25:16,120 Speaker 1: that I am amazed that people figured this out. In fact, 402 00:25:16,119 --> 00:25:18,800 Speaker 1: they figured it out way back at the beginning of 403 00:25:18,800 --> 00:25:21,560 Speaker 1: the twentieth century. It would take the middle of the 404 00:25:21,600 --> 00:25:25,240 Speaker 1: twentieth century before anyone built a working laser, but they 405 00:25:25,240 --> 00:25:29,560 Speaker 1: figured out the physics of it decades ahead of time, 406 00:25:29,760 --> 00:25:32,399 Speaker 1: and that still blows my mind to this day. Then again, 407 00:25:32,560 --> 00:25:35,159 Speaker 1: I'm also the guy who can't figure out which remote 408 00:25:35,160 --> 00:25:39,600 Speaker 1: control controls the TV versus the audio system. So what 409 00:25:39,680 --> 00:25:46,200 Speaker 1: do I know? You get this series of photons being 410 00:25:46,200 --> 00:25:50,760 Speaker 1: omitted that are all in phase with one another, and 411 00:25:51,200 --> 00:25:54,440 Speaker 1: they bounce back and forth between these two mirrored ends 412 00:25:54,600 --> 00:25:58,200 Speaker 1: of this ruby rod, but some of them can pass 413 00:25:58,240 --> 00:26:02,960 Speaker 1: through the half silvered or partially silvered end because that 414 00:26:03,000 --> 00:26:05,639 Speaker 1: it allows for that, and this is the source of 415 00:26:05,680 --> 00:26:08,280 Speaker 1: the laser beam. The photons that get out through that 416 00:26:08,440 --> 00:26:11,520 Speaker 1: end become the laser beam, and it's just a steady 417 00:26:11,600 --> 00:26:15,359 Speaker 1: beam of light that will continue to fire as long 418 00:26:15,480 --> 00:26:19,120 Speaker 1: as this reaction is allowed to continue. If you remove 419 00:26:19,200 --> 00:26:23,080 Speaker 1: that source of energy, the pump energy that is allowing 420 00:26:23,160 --> 00:26:26,280 Speaker 1: this to happen in the first place, it will stop, 421 00:26:26,760 --> 00:26:31,879 Speaker 1: right will. The reaction is not sustaining. It can't just 422 00:26:32,000 --> 00:26:35,040 Speaker 1: keep on going. You have to have that external source 423 00:26:35,080 --> 00:26:39,520 Speaker 1: of energy to maintain it throughout the whole process, otherwise 424 00:26:39,560 --> 00:26:46,280 Speaker 1: it just goes dark. So that's basically how your standard 425 00:26:46,760 --> 00:26:50,000 Speaker 1: laser works now if you're using that ruby based laser. 426 00:26:50,040 --> 00:26:53,360 Speaker 1: I was talking about the wavelength of the laser. Light 427 00:26:53,840 --> 00:26:57,320 Speaker 1: could be measured at six hundred and ninety four nanometers. 428 00:26:57,359 --> 00:27:03,399 Speaker 1: That's how long. A wavelength of UBI laser is. Six 429 00:27:03,480 --> 00:27:06,879 Speaker 1: hundred ninety four nanimeters, which is incredibly tiny. The visible 430 00:27:06,920 --> 00:27:10,720 Speaker 1: spectrum of light is between four hundred nanimeters, which would 431 00:27:10,720 --> 00:27:13,600 Speaker 1: be the violet side, up to seven hundred nanometers, which 432 00:27:13,640 --> 00:27:16,200 Speaker 1: is the red side. So this ruby one is right 433 00:27:16,280 --> 00:27:19,120 Speaker 1: up there at the top level of what we can 434 00:27:19,200 --> 00:27:22,960 Speaker 1: see as human beings. Now, you can also have infrared 435 00:27:23,040 --> 00:27:26,320 Speaker 1: or ultraviolet lasers. Obviously those would be invisible to us, 436 00:27:26,359 --> 00:27:28,840 Speaker 1: but they would still exist and you can still do 437 00:27:28,960 --> 00:27:32,560 Speaker 1: some pretty cool stuff with it. In fact, infrared lasers 438 00:27:32,560 --> 00:27:37,040 Speaker 1: are often used to cut steel, for example, which pretty 439 00:27:37,040 --> 00:27:40,840 Speaker 1: serious stuff when you think about it. But we'll talk 440 00:27:40,840 --> 00:27:43,320 Speaker 1: about that more in a little bit. Before we get 441 00:27:43,359 --> 00:27:47,560 Speaker 1: into more about PEWPW lasers, let's take a quick break 442 00:27:48,000 --> 00:27:59,440 Speaker 1: to thank our sponsor. Now. According to the company Wicked Lasers, 443 00:27:59,480 --> 00:28:03,320 Speaker 1: which makes range of laser products, including ones that are 444 00:28:03,359 --> 00:28:09,160 Speaker 1: capable of actually burning stuff if you use them, they 445 00:28:09,200 --> 00:28:11,480 Speaker 1: say that the wavelength of five hundred and fifty five 446 00:28:11,560 --> 00:28:15,159 Speaker 1: nanometers is ideal for brightness compared to other colors that 447 00:28:15,200 --> 00:28:18,400 Speaker 1: are produced at that same amount of power. So lasers 448 00:28:18,440 --> 00:28:22,000 Speaker 1: have a couple of different elements to them. There's the 449 00:28:22,040 --> 00:28:26,040 Speaker 1: wavelength of the laser itself, and then there's the amount 450 00:28:26,080 --> 00:28:30,199 Speaker 1: of power that you are able to generate. You measure 451 00:28:30,320 --> 00:28:34,680 Speaker 1: laser power in milliwatts. Typically for the ones that we 452 00:28:34,800 --> 00:28:38,600 Speaker 1: use day to day as consumers, they can go higher 453 00:28:38,640 --> 00:28:43,160 Speaker 1: than millawatts, but typically the ones we consumers use are 454 00:28:43,200 --> 00:28:48,280 Speaker 1: in the milliwat lange range rather. But you would measure 455 00:28:48,320 --> 00:28:50,640 Speaker 1: them in watts the same way you would with light bulbs. 456 00:28:51,160 --> 00:28:55,640 Speaker 1: But a ten watt laser or a fifty watt laser 457 00:28:56,240 --> 00:28:59,920 Speaker 1: would be much more much brighter than a fifty watt 458 00:29:00,080 --> 00:29:03,200 Speaker 1: light bulb because remember a fifty what light bulb is 459 00:29:03,240 --> 00:29:07,440 Speaker 1: giving out fifty watts of light, but it's emitting that 460 00:29:07,560 --> 00:29:12,200 Speaker 1: in practically all directions, whereas a laser has it very 461 00:29:12,360 --> 00:29:16,360 Speaker 1: much concentrated in a coherent beam. So a fifty watt 462 00:29:16,440 --> 00:29:19,880 Speaker 1: laser would be incredibly bright compared to a fifty watt 463 00:29:19,960 --> 00:29:23,360 Speaker 1: light bulb. And we're mostly talking about millawats. So if 464 00:29:23,360 --> 00:29:30,120 Speaker 1: you have a certain laser pointer of let's say, let's 465 00:29:30,200 --> 00:29:33,880 Speaker 1: just say twenty milawatts, I mean it's incredibly small, but 466 00:29:33,920 --> 00:29:36,560 Speaker 1: this is just for the purposes of an example, twenty 467 00:29:36,560 --> 00:29:41,480 Speaker 1: melawat laser pointer, and it's green, which is closer to 468 00:29:41,520 --> 00:29:45,080 Speaker 1: that five hundred and fifty five nanometers in wavelength, and 469 00:29:45,120 --> 00:29:47,640 Speaker 1: then you've got another one that's red. The green one's 470 00:29:47,640 --> 00:29:49,960 Speaker 1: gonna appear brighter than the red one, even if they're 471 00:29:50,000 --> 00:29:56,280 Speaker 1: both emitting the same wattage of laser light, because our 472 00:29:56,760 --> 00:29:59,440 Speaker 1: visual acuity is closer to that five hundred and fifty 473 00:29:59,480 --> 00:30:04,200 Speaker 1: five nano wavelength range. So violet and blue lasers are 474 00:30:04,200 --> 00:30:07,160 Speaker 1: slightly less powerful than that, but the greens are the 475 00:30:07,200 --> 00:30:10,920 Speaker 1: ones that are gonna show up the best for their 476 00:30:10,920 --> 00:30:14,320 Speaker 1: respective amount of power. Obviously, you can pour more power 477 00:30:14,320 --> 00:30:17,120 Speaker 1: into a laser, and in some cases you can end 478 00:30:17,160 --> 00:30:20,320 Speaker 1: up with a brighter laser because of it, of course, 479 00:30:20,360 --> 00:30:22,440 Speaker 1: depending upon whether or not the laser is within the 480 00:30:22,520 --> 00:30:24,600 Speaker 1: visible spectrum in the first place. It doesn't matter how 481 00:30:24,720 --> 00:30:27,760 Speaker 1: much power you pour into an infrared laser. You're never 482 00:30:27,800 --> 00:30:30,720 Speaker 1: gonna see it. You'll see the results because it'll burn 483 00:30:30,800 --> 00:30:35,120 Speaker 1: through stuff, but you won't see the laser itself. But yeah, 484 00:30:35,120 --> 00:30:38,520 Speaker 1: it's all about those extra things as well, not just 485 00:30:38,560 --> 00:30:41,360 Speaker 1: the wavelength but also the power. So that's really what 486 00:30:41,440 --> 00:30:44,840 Speaker 1: helps determine a laser strength is the wavelength and the 487 00:30:44,840 --> 00:30:47,440 Speaker 1: amount of power that it's putting out. Really, how much 488 00:30:47,440 --> 00:30:49,440 Speaker 1: power are you putting in and getting out of it? 489 00:30:50,160 --> 00:30:54,120 Speaker 1: So if I want to use a death laser in 490 00:30:54,200 --> 00:30:57,040 Speaker 1: order to defeat my arch nemesis who happens to be 491 00:30:57,080 --> 00:31:01,840 Speaker 1: a British secret spy, and I want to also use 492 00:31:01,880 --> 00:31:05,000 Speaker 1: another laser to amuse my cat but not turn it 493 00:31:05,000 --> 00:31:08,240 Speaker 1: into kittycatflombai, what do I need to do to make 494 00:31:08,280 --> 00:31:12,480 Speaker 1: sure about that? Well, one is again that wavelength of light. 495 00:31:13,280 --> 00:31:18,000 Speaker 1: Certain wavelengths are absorbed more readily by a broader variety 496 00:31:18,320 --> 00:31:21,880 Speaker 1: of substances than other wavelengths. So if you pick a 497 00:31:21,880 --> 00:31:26,560 Speaker 1: wavelength that is easily absorbed by lots of different stuff, 498 00:31:27,480 --> 00:31:32,360 Speaker 1: that is going to transfer energy more readily to your target. So, 499 00:31:32,440 --> 00:31:36,520 Speaker 1: as it turns out, infra red lasers can really transfer 500 00:31:36,640 --> 00:31:39,120 Speaker 1: a lot of energy to a broad array of stuff, 501 00:31:39,880 --> 00:31:44,640 Speaker 1: including steel. That's why carbon dioxide megawatt lasers are used 502 00:31:44,680 --> 00:31:49,600 Speaker 1: to cut through stuff like sheets of steel. But other 503 00:31:49,880 --> 00:31:54,080 Speaker 1: colors are not as easily absorbed by as wide a 504 00:31:54,160 --> 00:31:56,600 Speaker 1: variety of materials, and so you would really have to 505 00:31:56,680 --> 00:32:00,440 Speaker 1: pour more energy into the laser in order to get 506 00:32:00,480 --> 00:32:04,000 Speaker 1: a beam strong enough to start cutting through stuff. So 507 00:32:04,520 --> 00:32:06,720 Speaker 1: it depends on both how much power you're putting into 508 00:32:06,760 --> 00:32:10,280 Speaker 1: the laser and the wavelength of the light. Both of 509 00:32:10,320 --> 00:32:14,600 Speaker 1: those together will determine how strong, quote unquote your laser is. Strong. 510 00:32:14,640 --> 00:32:18,320 Speaker 1: Isn't really a meaningful term because there are different ways 511 00:32:18,320 --> 00:32:21,440 Speaker 1: of measuring laser. It's by how much light it gives 512 00:32:21,480 --> 00:32:25,360 Speaker 1: off and also how much energy does it transfer to 513 00:32:25,400 --> 00:32:28,320 Speaker 1: a target. But if you're talking about that energy transfer 514 00:32:28,440 --> 00:32:30,600 Speaker 1: to a target, those are the two things you have 515 00:32:30,640 --> 00:32:34,200 Speaker 1: to worry about, the wavelength and the amount of power 516 00:32:34,360 --> 00:32:37,520 Speaker 1: that it generates. You can use other stuff to help 517 00:32:37,560 --> 00:32:39,960 Speaker 1: with that too, like lenses. You can use lenses to 518 00:32:40,000 --> 00:32:46,360 Speaker 1: help maintain a tighter laser for further distances, but ultimately 519 00:32:46,400 --> 00:32:51,960 Speaker 1: it's power and wavelength that you're really concerned with. Lasers 520 00:32:52,000 --> 00:32:55,280 Speaker 1: can be used for all sorts of things, from optical 521 00:32:55,320 --> 00:32:58,360 Speaker 1: media like DVDs, blu rays, and CD players, to communication 522 00:32:58,440 --> 00:33:02,400 Speaker 1: systems to massive industrial lasers that can cut through steel 523 00:33:02,440 --> 00:33:04,600 Speaker 1: like warm butter and they're really nifty. But I thought 524 00:33:04,600 --> 00:33:07,680 Speaker 1: it might be interesting to learn a little bit more 525 00:33:08,560 --> 00:33:12,440 Speaker 1: about not just how lasers work, but sort of the 526 00:33:13,360 --> 00:33:18,080 Speaker 1: history of lasers as well. Right, because there's a ton 527 00:33:18,080 --> 00:33:22,600 Speaker 1: of different stuff to talk about. I mean, who figured 528 00:33:22,600 --> 00:33:27,040 Speaker 1: out how lasers would even be a thing? Like? Where 529 00:33:27,040 --> 00:33:30,800 Speaker 1: did that come from? So to trace the history of 530 00:33:30,800 --> 00:33:33,760 Speaker 1: the laser, you have to look at the scientists whose 531 00:33:33,760 --> 00:33:37,080 Speaker 1: work provided the foundation for all the people who followed. 532 00:33:37,560 --> 00:33:40,400 Speaker 1: So all the scientists and engineers who actually started building 533 00:33:40,480 --> 00:33:44,200 Speaker 1: lasers in the nineteen fifties, they did this working off 534 00:33:44,280 --> 00:33:47,720 Speaker 1: of the theoretical work of people who came before them. 535 00:33:48,000 --> 00:33:51,840 Speaker 1: So one of those people was Max Planck. So Plank 536 00:33:51,960 --> 00:33:54,760 Speaker 1: was born in eighteen fifty eight in Germany and his 537 00:33:54,800 --> 00:33:57,200 Speaker 1: father was a law professor. And when he was a kid, 538 00:33:58,000 --> 00:34:00,880 Speaker 1: he was really good at studying and stuff. He was 539 00:34:00,920 --> 00:34:03,560 Speaker 1: really interested in tons of different things. He was a 540 00:34:03,600 --> 00:34:08,440 Speaker 1: bit of a polymath, really intelligent, very and very accomplished 541 00:34:08,440 --> 00:34:12,600 Speaker 1: in several fields, including music. And in fact, when he 542 00:34:12,640 --> 00:34:14,920 Speaker 1: turned seventeen, he had to make the tough decision what 543 00:34:15,080 --> 00:34:17,200 Speaker 1: was he going to pursue as a career. Was he 544 00:34:17,280 --> 00:34:21,120 Speaker 1: going to continue to study science or was he going 545 00:34:21,120 --> 00:34:25,640 Speaker 1: to become a musician. And somewhere there's an alternate universe 546 00:34:25,640 --> 00:34:28,600 Speaker 1: where Plank decided to become a musician instead of a physicist. 547 00:34:29,360 --> 00:34:33,240 Speaker 1: And in that alternate universe we had totally different types 548 00:34:33,280 --> 00:34:37,759 Speaker 1: of piano music that Plank would have written. It would 549 00:34:37,760 --> 00:34:41,440 Speaker 1: have been amazing. But I think we're pretty thankful for 550 00:34:41,480 --> 00:34:44,560 Speaker 1: his contributions to science. So ultimately, if we were to 551 00:34:44,600 --> 00:34:46,879 Speaker 1: measure us versus them, I think we get the better 552 00:34:46,960 --> 00:34:49,600 Speaker 1: end of the deal. But still, it's really interesting to 553 00:34:49,640 --> 00:34:52,000 Speaker 1: think that he could have become a musician instead of 554 00:34:52,000 --> 00:34:57,240 Speaker 1: a physicist. And he's sort of the father of quantum physics, 555 00:34:57,640 --> 00:35:01,080 Speaker 1: so if he had not gone and to study physics, 556 00:35:01,160 --> 00:35:05,799 Speaker 1: it might have delayed our study of quantum physics as 557 00:35:05,800 --> 00:35:10,640 Speaker 1: a discipline by at least a decade, potentially more because 558 00:35:10,680 --> 00:35:13,000 Speaker 1: his work would go on to inspire lots of other 559 00:35:13,360 --> 00:35:20,880 Speaker 1: heavy thinkers, including a mister Albert Einstein. So Plank earned 560 00:35:20,880 --> 00:35:25,680 Speaker 1: his doctorate the same year as Einstein's birth, so Plank's 561 00:35:25,760 --> 00:35:30,000 Speaker 1: predecessor to Albert Einstein, obviously, and Einstein would take inspiration 562 00:35:30,080 --> 00:35:33,040 Speaker 1: from several of Plank's ideas, and one of those was 563 00:35:33,080 --> 00:35:36,799 Speaker 1: Plank's idea that energy could only be emitted and absorbed 564 00:35:36,920 --> 00:35:40,719 Speaker 1: in discrete amounts. So if you think about it, it's 565 00:35:40,760 --> 00:35:45,120 Speaker 1: almost more like digital versus analog. If you've listened to 566 00:35:45,160 --> 00:35:49,000 Speaker 1: me talk about digital audio. You know how digital audio 567 00:35:49,080 --> 00:35:55,120 Speaker 1: is made up of tiny little steps of pitch and volume, 568 00:35:55,600 --> 00:36:00,960 Speaker 1: whereas analog is a continuous wave, right is a bunch 569 00:36:01,000 --> 00:36:05,360 Speaker 1: of discrete little moments in time, And the number of 570 00:36:05,360 --> 00:36:08,279 Speaker 1: those moments in time that's your sample rate. The more 571 00:36:08,360 --> 00:36:11,800 Speaker 1: the higher your sample rate is, the closer this looks 572 00:36:11,840 --> 00:36:14,239 Speaker 1: to be a continuous line, but it's not really a 573 00:36:14,239 --> 00:36:21,280 Speaker 1: continuous line, tiny little steps in pitch and volume. Well, 574 00:36:21,760 --> 00:36:25,960 Speaker 1: Plank's point was that energy is sort of similar it. Ultimately, 575 00:36:26,320 --> 00:36:28,600 Speaker 1: when you get down to the very very very tiny 576 00:36:28,600 --> 00:36:34,000 Speaker 1: amounts could only be emitted or absorbed in discrete chunks. 577 00:36:34,239 --> 00:36:40,000 Speaker 1: It's not continuous, not analog, And this was a revolutionary idea. 578 00:36:40,280 --> 00:36:43,759 Speaker 1: Einstein would end up looking at this idea and saying 579 00:36:43,760 --> 00:36:48,280 Speaker 1: this is pretty cool. I'm gonna use this and add 580 00:36:48,280 --> 00:36:51,040 Speaker 1: on to it, and he created his theory about the 581 00:36:51,040 --> 00:36:56,319 Speaker 1: photoelectric effect. Plank, meanwhile, would end up being awarded the 582 00:36:56,360 --> 00:37:00,440 Speaker 1: Nobel Prize in Physics in nineteen eighteen for his his 583 00:37:00,560 --> 00:37:05,160 Speaker 1: working quantum mechanics. Einstein would similarly be honored several times. 584 00:37:05,760 --> 00:37:08,759 Speaker 1: It was Einstein who first suggested that atoms might be 585 00:37:08,800 --> 00:37:13,600 Speaker 1: able to produce photons through stimulated emission so lasers are 586 00:37:13,680 --> 00:37:18,320 Speaker 1: somewhat built upon the theories of Einstein himself. He stated 587 00:37:18,320 --> 00:37:20,840 Speaker 1: that electrons could be stimulated to emit light of a 588 00:37:20,880 --> 00:37:24,120 Speaker 1: specific wavelength, which of course is the very basis of lasers. 589 00:37:24,560 --> 00:37:29,200 Speaker 1: And Einstein published that theory in nineteen seventeen, so it 590 00:37:29,200 --> 00:37:32,840 Speaker 1: would be nearly forty years before anyone could actually build 591 00:37:32,880 --> 00:37:35,920 Speaker 1: something to test out and see if Einstein's theory was 592 00:37:36,160 --> 00:37:41,000 Speaker 1: of practical application. But it turns out he was right, 593 00:37:41,239 --> 00:37:45,160 Speaker 1: which again blows my mind. Forty years before anyone could 594 00:37:45,200 --> 00:37:48,760 Speaker 1: build something, and he's saying, hey, you know what probably 595 00:37:48,840 --> 00:37:54,239 Speaker 1: would work. I'm oversimplifying it and making light of it. 596 00:37:54,280 --> 00:37:56,799 Speaker 1: But I am in awe of people who are able 597 00:37:56,880 --> 00:38:00,319 Speaker 1: to think in these terms, where they're able to work 598 00:38:00,400 --> 00:38:04,440 Speaker 1: out the basic laws of the universe well before we 599 00:38:04,440 --> 00:38:08,080 Speaker 1: could ever make any sort of practical attempt to test 600 00:38:08,239 --> 00:38:11,160 Speaker 1: those ideas. It is phenomenal to me. Now, granted, I 601 00:38:11,160 --> 00:38:13,719 Speaker 1: could make up laws of the universe, but they would 602 00:38:13,719 --> 00:38:17,120 Speaker 1: be completely unsubstantiated and would fail to hold up to 603 00:38:17,160 --> 00:38:19,840 Speaker 1: any testing in the future. I lack the ability to 604 00:38:19,880 --> 00:38:22,400 Speaker 1: have that level of insight into how our universe works, 605 00:38:23,080 --> 00:38:27,040 Speaker 1: but I do appreciate it in others. So let's flash 606 00:38:27,080 --> 00:38:30,480 Speaker 1: forward to nineteen fifty one. So we go from nineteen 607 00:38:30,520 --> 00:38:33,080 Speaker 1: seventeen to nineteen fifty one. That's when a guy named 608 00:38:33,160 --> 00:38:38,680 Speaker 1: Charles H. Towns, who worked at Columbia University in New York, 609 00:38:39,280 --> 00:38:42,160 Speaker 1: was sitting on a park bench, which in itself is 610 00:38:42,200 --> 00:38:45,600 Speaker 1: not that remarkable, but he came up with an idea 611 00:38:45,920 --> 00:38:49,960 Speaker 1: of creating a device that could produce microwaves through stimulated 612 00:38:50,000 --> 00:38:53,279 Speaker 1: emission of radiation, and this idea became the basis of 613 00:38:53,560 --> 00:38:59,640 Speaker 1: the maser maser, which is similar to the laser, but 614 00:38:59,680 --> 00:39:04,520 Speaker 1: obvious amidst microwaves rather than light. Three years later, Towns 615 00:39:04,600 --> 00:39:08,919 Speaker 1: would demonstrate a working maser, So this is nineteen fifty four, 616 00:39:09,280 --> 00:39:13,279 Speaker 1: not a laser, yet still a mazer. So microwaves are 617 00:39:13,320 --> 00:39:16,359 Speaker 1: part of the electromagnetic spectrum, but are not considered part 618 00:39:16,400 --> 00:39:19,320 Speaker 1: of light. Right, you've gone beyond infrared at this point. 619 00:39:19,400 --> 00:39:22,839 Speaker 1: The wavelengths of microwaves are much, much, much longer than 620 00:39:23,080 --> 00:39:26,799 Speaker 1: the wavelengths of light. Towns had actually partnered with a 621 00:39:26,800 --> 00:39:29,440 Speaker 1: couple of people in order to create this working maser 622 00:39:29,520 --> 00:39:32,719 Speaker 1: that included Herbert J. Zeiger and a graduate student named 623 00:39:32,800 --> 00:39:36,920 Speaker 1: James P. Gordon. They used ammonia as their medium for 624 00:39:36,960 --> 00:39:40,799 Speaker 1: the mazer, and the wavelength of the microwave was one centimeter. 625 00:39:41,520 --> 00:39:47,760 Speaker 1: A centimeter is it's almost impossible for me to describe 626 00:39:47,800 --> 00:39:51,560 Speaker 1: how big that is compared to the waves that are 627 00:39:51,600 --> 00:39:55,359 Speaker 1: in the nanometer range, the hundreds of nanometers, but it 628 00:39:55,440 --> 00:39:59,160 Speaker 1: is while centimeter is small to us, it is enormous 629 00:39:59,320 --> 00:40:04,120 Speaker 1: in the quantum world. So they were able to create this, 630 00:40:04,320 --> 00:40:07,000 Speaker 1: They were able to build a working mazer using ammonia 631 00:40:07,040 --> 00:40:13,760 Speaker 1: as their medium. Now in Moscow at around the same time, 632 00:40:14,040 --> 00:40:17,400 Speaker 1: there were a couple of engineers, Nikolai g. Basov and 633 00:40:17,480 --> 00:40:22,239 Speaker 1: Alexander M. Prokhorov, who were working on building oscillators at 634 00:40:22,320 --> 00:40:24,640 Speaker 1: the time, and while they were building oscillators, they came 635 00:40:24,719 --> 00:40:27,960 Speaker 1: up with a method that they thought would work for 636 00:40:28,040 --> 00:40:31,640 Speaker 1: negative absorption while building these things, and they called it 637 00:40:31,680 --> 00:40:36,320 Speaker 1: the pumping method, which would become important for future mazers 638 00:40:36,360 --> 00:40:42,160 Speaker 1: and lasers. In nineteen fifty six, Nicholas Bloembergen at Harvard 639 00:40:42,239 --> 00:40:47,240 Speaker 1: develops the first solid state maser. In September nineteen fifty seven, 640 00:40:47,480 --> 00:40:50,960 Speaker 1: Towns would sketch out an optical mazer design in a 641 00:40:51,080 --> 00:40:54,080 Speaker 1: lab notebook. Also in nineteen fifty seven, there was a 642 00:40:54,080 --> 00:40:57,560 Speaker 1: guy named Gordon Gould, who was a grad student at Columbia, 643 00:40:57,680 --> 00:40:59,600 Speaker 1: who wrote down his own ideas for a device that 644 00:40:59,600 --> 00:41:02,160 Speaker 1: would be similar to a maser, but he called this 645 00:41:02,160 --> 00:41:06,200 Speaker 1: one a laser. So this appears to be the first 646 00:41:06,320 --> 00:41:10,239 Speaker 1: use of the word lasers, the first recorded instance of 647 00:41:10,440 --> 00:41:14,280 Speaker 1: laser as a word. And Gould thought ahead and even 648 00:41:14,360 --> 00:41:18,239 Speaker 1: had his notes notarized. So he had them notarized by 649 00:41:18,280 --> 00:41:21,360 Speaker 1: a notary, where as a date on it and everything, 650 00:41:21,400 --> 00:41:23,440 Speaker 1: so that he could prove that he had come up 651 00:41:23,440 --> 00:41:26,680 Speaker 1: with this notion. He tracked down a notary at a 652 00:41:26,719 --> 00:41:32,280 Speaker 1: candy shop in the Bronx, which is a phenomenal story 653 00:41:32,360 --> 00:41:35,360 Speaker 1: in my mind. I love the idea that this is 654 00:41:35,440 --> 00:41:37,799 Speaker 1: non a joke, This really happened. You had a guy 655 00:41:37,840 --> 00:41:42,880 Speaker 1: come up with what would become a transformative technology, a laser, 656 00:41:43,120 --> 00:41:47,200 Speaker 1: like the idea of creating a light version of what 657 00:41:47,320 --> 00:41:51,000 Speaker 1: had already happened, And so he needs it notarized, so 658 00:41:51,040 --> 00:41:54,640 Speaker 1: he goes to a candy store. It's pretty sweet when 659 00:41:54,640 --> 00:41:57,960 Speaker 1: you think about it. By nineteen fifty eight, Towns was 660 00:41:58,000 --> 00:42:02,920 Speaker 1: working with his brother in law Arthur L. Shallow or Shawlow. 661 00:42:03,120 --> 00:42:07,080 Speaker 1: I guess is the way you would pronounce it Scchawlow 662 00:42:07,360 --> 00:42:10,960 Speaker 1: Shawlow he was a researcher for Bell Labs, which obviously 663 00:42:11,040 --> 00:42:14,279 Speaker 1: has played an enormously important role in the development of 664 00:42:14,320 --> 00:42:19,160 Speaker 1: electronics in general. Together, they proposed developing masers that could 665 00:42:19,160 --> 00:42:21,880 Speaker 1: operate in the infrared and optical parts of the electro 666 00:42:22,000 --> 00:42:26,280 Speaker 1: magnetic spectrum. And meanwhile, over in Russia, Prokhorov and Besov 667 00:42:26,480 --> 00:42:30,719 Speaker 1: were also investigating the possibility of developing optical mazers. So 668 00:42:30,760 --> 00:42:32,960 Speaker 1: the race was on a lot of different people, all 669 00:42:33,000 --> 00:42:37,840 Speaker 1: trying to create an optical maser or laser. In April 670 00:42:37,880 --> 00:42:41,400 Speaker 1: nineteen fifty nine, Gould would apply for patents relating to lasers, 671 00:42:41,680 --> 00:42:46,200 Speaker 1: and in nineteen sixty Towns and Shawlow received a patent 672 00:42:46,320 --> 00:42:50,240 Speaker 1: for the optical mazer, which they now were calling a laser, 673 00:42:50,600 --> 00:42:54,960 Speaker 1: and thus the Great Laser Battle began. Only this laser 674 00:42:55,040 --> 00:42:58,680 Speaker 1: battle wasn't fought with lasers. It was fought over the 675 00:42:58,680 --> 00:43:02,960 Speaker 1: intellectual property represent resented by lasers. And this was a 676 00:43:03,040 --> 00:43:06,399 Speaker 1: legal battle that would stretch for three decades. So an 677 00:43:06,400 --> 00:43:11,400 Speaker 1: incredible laser battle really. But the first working laser was 678 00:43:11,440 --> 00:43:16,320 Speaker 1: built in Malibu, California, in nineteen sixty and almost certainly 679 00:43:16,360 --> 00:43:20,120 Speaker 1: had nothing to do with plastic surgery. Unlike everything else 680 00:43:20,160 --> 00:43:24,640 Speaker 1: in Malibu, California. Theodore H. Mahmon, who worked at Hughes 681 00:43:24,719 --> 00:43:28,200 Speaker 1: Research Labs in Malibu, built this first laser. He used 682 00:43:28,239 --> 00:43:31,399 Speaker 1: a synthetic ruby that was two centimeters long and one 683 00:43:31,440 --> 00:43:34,920 Speaker 1: centimeter in diameter, and he coated the ends in silver 684 00:43:35,120 --> 00:43:39,000 Speaker 1: to make them reflective. He used a photographic flash lamp 685 00:43:39,360 --> 00:43:42,160 Speaker 1: to pump the lasing materials, so he used the exact 686 00:43:42,200 --> 00:43:43,960 Speaker 1: same sort of flash bulbs you would find in a 687 00:43:43,960 --> 00:43:46,920 Speaker 1: cameras flash, which was pretty incredible, and a couple of 688 00:43:46,920 --> 00:43:49,960 Speaker 1: months later, Hughes's Research would hold a press conference to 689 00:43:50,000 --> 00:43:53,480 Speaker 1: announce that they had developed the first working laser. A 690 00:43:53,480 --> 00:43:57,400 Speaker 1: few months after that, scientists at IBM's Thomas J. Watson 691 00:43:57,440 --> 00:44:02,680 Speaker 1: Research Center demonstrated a working uranium laser, which seems like 692 00:44:02,760 --> 00:44:07,880 Speaker 1: a massive show of escalation in my mind. Now at 693 00:44:07,920 --> 00:44:11,320 Speaker 1: this point the developments would come really fast and furious, 694 00:44:11,880 --> 00:44:14,520 Speaker 1: not like the film series within Diesel, but I mean, 695 00:44:14,560 --> 00:44:19,920 Speaker 1: they were just laser development after laser development, tons of advances. 696 00:44:19,920 --> 00:44:21,520 Speaker 1: I'm not going to cover all of them because they're 697 00:44:21,560 --> 00:44:23,400 Speaker 1: way too many, but I'll cover some of the big ones. 698 00:44:23,880 --> 00:44:26,520 Speaker 1: The first helium neon laser debuted at the end of 699 00:44:26,600 --> 00:44:29,560 Speaker 1: nineteen sixty again at Bell Labs, and it was able 700 00:44:29,560 --> 00:44:32,920 Speaker 1: to create a one point one five micrometer wavelength of 701 00:44:33,000 --> 00:44:37,160 Speaker 1: continuous light, so beyond the range of human vision. It 702 00:44:37,200 --> 00:44:40,240 Speaker 1: wasn't light that was visible, but it was in the 703 00:44:40,280 --> 00:44:44,479 Speaker 1: spectrum of light. And in nineteen sixty one companies began 704 00:44:44,560 --> 00:44:48,200 Speaker 1: to manufacture lasers for the market. This is incredible to me. 705 00:44:48,400 --> 00:44:51,279 Speaker 1: It had been only a year since someone had built 706 00:44:51,320 --> 00:44:54,800 Speaker 1: a working laser, and by the following year people were 707 00:44:55,200 --> 00:44:59,279 Speaker 1: making them for sale. Now, granted, they weren't selling them 708 00:44:59,320 --> 00:45:04,920 Speaker 1: to average consumers. It's not like John Smith or John Q. Public. 709 00:45:04,960 --> 00:45:08,800 Speaker 1: If you prefer I could walk into the closest laser 710 00:45:08,880 --> 00:45:11,520 Speaker 1: store and order a laser. These were meant for research 711 00:45:11,560 --> 00:45:15,520 Speaker 1: and development purposes and not for people who wanted to 712 00:45:15,560 --> 00:45:18,720 Speaker 1: amuse their cats. It was also meant for some early 713 00:45:18,760 --> 00:45:21,760 Speaker 1: industrial uses and as it turns out, some early medical uses. 714 00:45:22,600 --> 00:45:24,080 Speaker 1: So again I'm going to jump over some of the 715 00:45:24,080 --> 00:45:27,080 Speaker 1: incremental developments. It wouldn't make sense for me to cover 716 00:45:27,120 --> 00:45:28,319 Speaker 1: all of them, and a lot of them I would 717 00:45:28,320 --> 00:45:31,680 Speaker 1: have to go into even more description about very specific 718 00:45:31,719 --> 00:45:36,759 Speaker 1: types of lasers which only apply to particular cases and 719 00:45:36,800 --> 00:45:38,879 Speaker 1: not to others, and that would just make this kind 720 00:45:38,880 --> 00:45:42,560 Speaker 1: of muddy and directionless. But I do want to point 721 00:45:42,600 --> 00:45:45,680 Speaker 1: out a few really cool moments in history and explain 722 00:45:45,760 --> 00:45:50,239 Speaker 1: some related topics to lasers as a result, such as 723 00:45:50,560 --> 00:45:54,080 Speaker 1: what happened in December of nineteen sixty one. So keep 724 00:45:54,120 --> 00:45:56,120 Speaker 1: in mind it only been a bit longer than a 725 00:45:56,239 --> 00:45:59,480 Speaker 1: year since someone had demonstrated a working laser at all. 726 00:46:00,320 --> 00:46:04,520 Speaker 1: In December nineteen sixty one, doctor Charles J. Campbell and 727 00:46:04,640 --> 00:46:09,600 Speaker 1: Charles J. Kuster, a lot of Charles Jay's, decided that 728 00:46:09,640 --> 00:46:13,120 Speaker 1: they were going to treat a patient, a medical patient, 729 00:46:13,160 --> 00:46:17,279 Speaker 1: a human medical patient using an optical Ruby laser to 730 00:46:17,360 --> 00:46:21,759 Speaker 1: destroy a retinal tumor. Now that's incredible. It had been 731 00:46:21,760 --> 00:46:25,240 Speaker 1: only eighteen months since someone had built the first working laser, 732 00:46:25,680 --> 00:46:28,880 Speaker 1: and you already had people using it in a medical 733 00:46:28,920 --> 00:46:33,880 Speaker 1: procedure on a human patient. I suspect that today it 734 00:46:33,920 --> 00:46:37,800 Speaker 1: would take a bit longer to prove that the methodology 735 00:46:37,840 --> 00:46:41,719 Speaker 1: being used was safe and efficacious before using it on 736 00:46:41,760 --> 00:46:45,000 Speaker 1: a human, but it shows how quickly things were moving 737 00:46:45,080 --> 00:46:47,200 Speaker 1: back then. I think it's pretty incredible that it took 738 00:46:47,719 --> 00:46:50,759 Speaker 1: less than two years to actually use lasers in a 739 00:46:50,800 --> 00:46:55,360 Speaker 1: medical an actual medical procedure. Now, the mid nineteen sixties 740 00:46:55,400 --> 00:46:58,319 Speaker 1: would see advances in the field of fiber optics, which, 741 00:46:58,360 --> 00:47:01,120 Speaker 1: when paired with lasers, allow for low long distance communication 742 00:47:01,280 --> 00:47:04,520 Speaker 1: using light through glass filaments. Now, I've done episodes about 743 00:47:04,520 --> 00:47:06,520 Speaker 1: fiber optics before, so you can go and look at 744 00:47:06,520 --> 00:47:09,040 Speaker 1: the Tech Stuff archives and learn more about that. But 745 00:47:09,080 --> 00:47:11,440 Speaker 1: this still blows my mind too. Just the fact that 746 00:47:11,480 --> 00:47:15,160 Speaker 1: fiber optics are a thing that work, it is incredible 747 00:47:15,200 --> 00:47:19,080 Speaker 1: to me. Meanwhile, Bell Labs would strike again in nineteen 748 00:47:19,120 --> 00:47:21,440 Speaker 1: seventy two with a laser beam cutter they used to 749 00:47:21,480 --> 00:47:26,720 Speaker 1: form electronic circuit patterns on ceramic and on June twenty sixth, 750 00:47:27,080 --> 00:47:31,280 Speaker 1: nineteen seventy four, which just for trivia's sake, is exactly 751 00:47:31,360 --> 00:47:34,759 Speaker 1: one year to the day before I was born. A 752 00:47:34,800 --> 00:47:39,760 Speaker 1: barcode scanner, which typically uses lasers. Read the very first 753 00:47:39,880 --> 00:47:44,560 Speaker 1: product ever registered for real Z's using a UPC code 754 00:47:44,800 --> 00:47:47,440 Speaker 1: and a barcode scanner. The product, by the way, was 755 00:47:47,440 --> 00:47:51,319 Speaker 1: a pack of Wrigley's chewing gum. So how the heck 756 00:47:51,360 --> 00:47:53,960 Speaker 1: do those barcode scanners work? Because you see them on 757 00:47:54,000 --> 00:47:56,040 Speaker 1: everything these days. And here's where I'm going to go 758 00:47:56,120 --> 00:47:58,279 Speaker 1: on a bit of a tangent to talk about barcodes. 759 00:47:58,960 --> 00:48:01,799 Speaker 1: In just a second, and I also just want to 760 00:48:01,840 --> 00:48:04,680 Speaker 1: mention that I think it's really cool that, now you 761 00:48:04,719 --> 00:48:07,680 Speaker 1: know a trivia question that the first product to ever 762 00:48:07,760 --> 00:48:11,239 Speaker 1: be scanned using a barcode scanner was Wrigley's chewing gum. 763 00:48:11,719 --> 00:48:15,000 Speaker 1: Important to remember in case you ever played bar trivia. Now, next, 764 00:48:15,000 --> 00:48:17,319 Speaker 1: I'm going to talk all about UPC codes and how 765 00:48:17,360 --> 00:48:20,640 Speaker 1: they work. But before I jump into that and go 766 00:48:20,840 --> 00:48:23,880 Speaker 1: way off the rails, let's take another quick break to 767 00:48:23,960 --> 00:48:34,759 Speaker 1: thank our sponsor. All Right, so let's talk about barcodes, 768 00:48:34,880 --> 00:48:38,880 Speaker 1: which are I agree, tangentially related to lasers. But I've 769 00:48:38,920 --> 00:48:41,640 Speaker 1: already talked about how lasers work, and I really love 770 00:48:42,160 --> 00:48:45,760 Speaker 1: how barcodes work because I just think they're kind of cool. 771 00:48:46,200 --> 00:48:49,120 Speaker 1: So these are the good old universal product code or 772 00:48:49,239 --> 00:48:53,360 Speaker 1: UPC code things that you would see on products today 773 00:48:53,680 --> 00:48:57,200 Speaker 1: at your average store. They were designed in order to 774 00:48:57,280 --> 00:48:59,800 Speaker 1: help speed up check out and also make it easier 775 00:48:59,840 --> 00:49:04,000 Speaker 1: to keep a working inventory of a store. And you 776 00:49:04,040 --> 00:49:06,719 Speaker 1: can just scan each item and then you use a 777 00:49:06,960 --> 00:49:11,239 Speaker 1: computer database to match the scan with other information like 778 00:49:11,800 --> 00:49:15,080 Speaker 1: what that product is, how much it costs. So the 779 00:49:15,120 --> 00:49:18,800 Speaker 1: scanner all it needs to do is identify which product 780 00:49:19,000 --> 00:49:21,920 Speaker 1: you are actually scanning at any given time. That's its 781 00:49:21,960 --> 00:49:24,920 Speaker 1: only job. It doesn't really have anything to do with 782 00:49:24,960 --> 00:49:28,840 Speaker 1: how much something costs. That is not necessarily represented in 783 00:49:28,880 --> 00:49:31,360 Speaker 1: the code itself. There are codes that do have the 784 00:49:31,400 --> 00:49:35,160 Speaker 1: information in them, but the basic PC code is really 785 00:49:35,239 --> 00:49:38,719 Speaker 1: just to tell a system what the product is, and 786 00:49:38,760 --> 00:49:42,840 Speaker 1: then you have a separate database that links products to prices. 787 00:49:43,600 --> 00:49:47,600 Speaker 1: So what would you do if you were a manufacturer 788 00:49:48,120 --> 00:49:52,200 Speaker 1: and you wanted to put a UPC code on something 789 00:49:52,200 --> 00:49:56,440 Speaker 1: that you yourself were making, your company was making. Here's 790 00:49:56,440 --> 00:49:59,640 Speaker 1: the process. You have a company called the Uniform Code 791 00:50:00,680 --> 00:50:05,840 Speaker 1: or UCC, and they are in charge of UPC codes. 792 00:50:06,560 --> 00:50:08,640 Speaker 1: And to me, the UCC sounds like it should be 793 00:50:08,640 --> 00:50:11,319 Speaker 1: staffed by shadowy figures in robes. But to be fair, 794 00:50:11,480 --> 00:50:13,959 Speaker 1: I did watch Hot Fuzz again not too long ago, 795 00:50:14,000 --> 00:50:17,000 Speaker 1: and that's probably why I'm thinking that. So let's say 796 00:50:17,360 --> 00:50:20,440 Speaker 1: you're a manufacturing company and you make a very specific 797 00:50:20,480 --> 00:50:23,520 Speaker 1: product and you want to get it into stores around 798 00:50:23,560 --> 00:50:28,360 Speaker 1: the world. And since the earliest implementations of the UPC 799 00:50:28,520 --> 00:50:32,080 Speaker 1: codes were for grocery stores, let's say that it's a 800 00:50:32,239 --> 00:50:36,240 Speaker 1: grocery store product. So let's say you're making a really awesome, tasty, 801 00:50:36,360 --> 00:50:41,840 Speaker 1: sugary breakfast cereal for kids and you're calling them crispydus. 802 00:50:42,400 --> 00:50:45,959 Speaker 1: So you make delicious crispydos that are a nutritional part 803 00:50:46,040 --> 00:50:49,320 Speaker 1: of a balanced breakfast. You want to sell Crispy dues 804 00:50:49,480 --> 00:50:53,360 Speaker 1: in grocery stores, so you want to end up selling 805 00:50:53,360 --> 00:50:56,960 Speaker 1: to grocery stores. Grocery stores will sell the crispydos to 806 00:50:57,080 --> 00:51:03,920 Speaker 1: their customers and everyone benefits, presumably assuming that there's enough 807 00:51:04,000 --> 00:51:06,839 Speaker 1: nutritional value in the Crispy dues to not, you know, 808 00:51:07,239 --> 00:51:12,480 Speaker 1: turn your customers into goo. So grocery stores love the 809 00:51:12,560 --> 00:51:15,839 Speaker 1: idea of UPC codes because again, it makes it much 810 00:51:15,840 --> 00:51:19,040 Speaker 1: easier to ring up products and it makes it very 811 00:51:19,120 --> 00:51:22,160 Speaker 1: easy to keep track of the stock that the grocery 812 00:51:22,200 --> 00:51:25,080 Speaker 1: store has. If they notice that they're selling, you know, 813 00:51:25,520 --> 00:51:27,879 Speaker 1: eight pallets of Crispy dues a week, then they might 814 00:51:28,040 --> 00:51:30,759 Speaker 1: up their order and that's good for you. So it 815 00:51:30,840 --> 00:51:34,720 Speaker 1: benefits you to get a UPC code on your product. 816 00:51:35,480 --> 00:51:38,200 Speaker 1: To do that, you would first have to apply for 817 00:51:38,280 --> 00:51:42,800 Speaker 1: a manufacturer identification number from the UCC. This is almost 818 00:51:42,840 --> 00:51:45,080 Speaker 1: like a subscription service. You'd have to pay the UCC 819 00:51:45,640 --> 00:51:50,600 Speaker 1: to get this manufacturer identification number. The UCC would then 820 00:51:50,719 --> 00:51:54,640 Speaker 1: issue you this number. It's a six digit number and 821 00:51:54,680 --> 00:51:56,480 Speaker 1: if you look at a UPC code. You'll see that 822 00:51:56,520 --> 00:52:00,440 Speaker 1: there are twelve digits on a UPC code, So those 823 00:52:00,480 --> 00:52:02,920 Speaker 1: are the human readable digits, right, that's the thing that 824 00:52:02,960 --> 00:52:04,520 Speaker 1: you have to type in. If for some reason the 825 00:52:04,560 --> 00:52:08,520 Speaker 1: scanner's not scanning anything, you might type in the code. Well, 826 00:52:08,600 --> 00:52:13,240 Speaker 1: those first six digits refer to the manufacturer identification number, 827 00:52:14,080 --> 00:52:18,359 Speaker 1: So all the products from that specific manufacturer should have 828 00:52:18,440 --> 00:52:21,719 Speaker 1: those first six numbers the same on all of them 829 00:52:21,960 --> 00:52:27,279 Speaker 1: because it's unique to the company itself. It doesn't matter 830 00:52:27,320 --> 00:52:32,239 Speaker 1: what the product is. The next five digits on that 831 00:52:32,360 --> 00:52:37,520 Speaker 1: UPC code represent the item number, so it's unique to 832 00:52:37,680 --> 00:52:41,759 Speaker 1: the product. So if you make fourteen different products, each 833 00:52:41,800 --> 00:52:44,439 Speaker 1: product is going to have its same or its own 834 00:52:44,760 --> 00:52:48,160 Speaker 1: five digit item code, and it'll be different from the 835 00:52:48,200 --> 00:52:53,239 Speaker 1: other thirteen item codes. So if your company also produces, say, 836 00:52:53,480 --> 00:52:57,279 Speaker 1: flea collars for Kiddi cats, the five digits for the 837 00:52:57,320 --> 00:52:59,239 Speaker 1: flea colors are going to be different than the five 838 00:52:59,239 --> 00:53:01,799 Speaker 1: digits for the Chris which is good because you don't 839 00:53:01,840 --> 00:53:04,399 Speaker 1: want to mix up your flea collars with your Crispy Dues. 840 00:53:04,400 --> 00:53:08,279 Speaker 1: That would be a pr nightmare. And this episode really 841 00:53:08,280 --> 00:53:10,920 Speaker 1: isn't meant to go into that sort of thing. So 842 00:53:12,160 --> 00:53:15,239 Speaker 1: that leaves one digit leftover. Right, You've got the first 843 00:53:15,280 --> 00:53:19,320 Speaker 1: six that's the manufacturer ID number, the next five which 844 00:53:19,400 --> 00:53:23,040 Speaker 1: is the item number. But you have a single digit 845 00:53:23,160 --> 00:53:26,600 Speaker 1: leftover of those twelve. So what as that for. That 846 00:53:26,760 --> 00:53:30,319 Speaker 1: is called the check digit, and the check digit is 847 00:53:30,400 --> 00:53:35,719 Speaker 1: meant to give the scanner the opportunity to verify that 848 00:53:35,840 --> 00:53:40,640 Speaker 1: it has scanned the product properly. And the way you 849 00:53:40,719 --> 00:53:44,560 Speaker 1: do this is through some pretty ridiculous math. It's not difficult, 850 00:53:44,800 --> 00:53:50,759 Speaker 1: it's just tedious. So it's again a verification right to 851 00:53:50,880 --> 00:53:54,719 Speaker 1: say that, yes, the scan went through properly, because if 852 00:53:54,760 --> 00:53:58,040 Speaker 1: the math checks out, if you get the answer you're 853 00:53:58,040 --> 00:54:01,880 Speaker 1: supposed to get, you know that you scanned it properly. 854 00:54:02,080 --> 00:54:04,640 Speaker 1: And by you, I mean the scanner system is able 855 00:54:04,680 --> 00:54:09,120 Speaker 1: to verify that a scan went through correctly. So let's 856 00:54:09,160 --> 00:54:12,359 Speaker 1: take a second to talk about how you arrive at 857 00:54:12,360 --> 00:54:14,799 Speaker 1: the check digit so you can understand what I mean 858 00:54:14,840 --> 00:54:18,040 Speaker 1: when you do some ridiculous arithmetic. It's not difficult. Again, 859 00:54:18,120 --> 00:54:22,880 Speaker 1: it's just ridiculous. So you've got eleven other digits in 860 00:54:22,920 --> 00:54:25,920 Speaker 1: the UPC code and those are what you use to 861 00:54:26,000 --> 00:54:30,080 Speaker 1: do the arithmetic. First, you take all the numbers, all 862 00:54:30,160 --> 00:54:34,000 Speaker 1: the digits, and the UPC codes that are at odd positions, 863 00:54:34,440 --> 00:54:37,440 Speaker 1: so not the odd numbers, just in the odd positions. 864 00:54:37,640 --> 00:54:41,240 Speaker 1: So that would be the position number one, position number three, five, 865 00:54:41,360 --> 00:54:44,680 Speaker 1: et cetera, up to eleven. Because you have eleven other numbers. 866 00:54:46,600 --> 00:54:48,840 Speaker 1: You take all of those and you add them together 867 00:54:49,239 --> 00:54:51,880 Speaker 1: and you get a sum. So you've got that sum 868 00:54:52,280 --> 00:54:56,239 Speaker 1: by adding all the odd position numbers together, and you 869 00:54:56,320 --> 00:54:59,640 Speaker 1: then multiply that by three. Now you look at all 870 00:54:59,800 --> 00:55:04,239 Speaker 1: the digits that are in even positions, so two, four, six, eight, 871 00:55:04,320 --> 00:55:08,440 Speaker 1: and ten, you add all of those together. You then 872 00:55:08,520 --> 00:55:11,680 Speaker 1: take the number you got from all the odd positions 873 00:55:11,760 --> 00:55:15,480 Speaker 1: multiplied by three, and all the even positions added together, 874 00:55:15,680 --> 00:55:19,040 Speaker 1: and you add those two numbers together. And then you 875 00:55:19,080 --> 00:55:23,160 Speaker 1: take a look at this new number, this monstrausity of 876 00:55:23,200 --> 00:55:26,320 Speaker 1: a thing. It's not a huge number. It's just weird 877 00:55:26,560 --> 00:55:28,920 Speaker 1: that you've got it. And you say, all right, how 878 00:55:28,920 --> 00:55:31,839 Speaker 1: many more numbers would I have to add to this 879 00:55:32,520 --> 00:55:38,120 Speaker 1: in order to get a multiple of ten? And as 880 00:55:38,200 --> 00:55:43,600 Speaker 1: long as the last digit is the same as the 881 00:55:43,680 --> 00:55:47,920 Speaker 1: number you need to add to your monstrosity to get 882 00:55:47,960 --> 00:55:50,680 Speaker 1: a multiple of ten, you're good to go. So this 883 00:55:50,800 --> 00:55:54,120 Speaker 1: is easier to understand with an example. So here's our 884 00:55:54,200 --> 00:55:57,840 Speaker 1: UPC code. We've got our crispy dues, and our UPC 885 00:55:57,960 --> 00:56:02,239 Speaker 1: code happens to be six three nine three eight two 886 00:56:02,760 --> 00:56:08,399 Speaker 1: zero zero zero three nine three. Well, that last three 887 00:56:09,040 --> 00:56:11,440 Speaker 1: is the check digit. That's the number we're supposed to 888 00:56:11,480 --> 00:56:13,560 Speaker 1: get at the end of all this other nonsense. So 889 00:56:13,600 --> 00:56:16,160 Speaker 1: we put that aside. We say, three is what we're 890 00:56:16,200 --> 00:56:19,319 Speaker 1: hoping is the outcome. How do we get to that. 891 00:56:19,680 --> 00:56:24,360 Speaker 1: We take all those odd positioned digits, which would be 892 00:56:24,520 --> 00:56:28,120 Speaker 1: six and nine and eight, et cetera, et cetera. We 893 00:56:28,160 --> 00:56:31,000 Speaker 1: add them all up technically at six, nine, eight, two 894 00:56:31,120 --> 00:56:34,600 Speaker 1: zero's in a nine. That gets you thirty two. You 895 00:56:34,680 --> 00:56:38,160 Speaker 1: multiply that number by three, you get ninety six. So 896 00:56:38,200 --> 00:56:40,640 Speaker 1: that's your first number. You set that aside. Your ninety 897 00:56:40,640 --> 00:56:42,879 Speaker 1: six is good to go. Then you take a look 898 00:56:42,920 --> 00:56:46,279 Speaker 1: at all the even positioned numbers and you add those up. 899 00:56:46,560 --> 00:56:48,879 Speaker 1: The even position numbers would be a three, A three, 900 00:56:49,000 --> 00:56:51,880 Speaker 1: a two, a zero, and another three. That gives you eleven. 901 00:56:52,800 --> 00:56:55,160 Speaker 1: So now you add the eleven to the ninety six 902 00:56:55,280 --> 00:56:57,680 Speaker 1: that you arrived at earlier. That gives you one hundred 903 00:56:57,719 --> 00:57:00,000 Speaker 1: and seven. You look at one hundred and seven and say, 904 00:57:00,080 --> 00:57:02,200 Speaker 1: how many digits or how much we need to add 905 00:57:02,200 --> 00:57:05,080 Speaker 1: to this to make a multiple of ten answers three, 906 00:57:05,760 --> 00:57:07,720 Speaker 1: because if you add three to one hundred and seven 907 00:57:07,920 --> 00:57:09,839 Speaker 1: you get one hundred and ten. One hundred and ten 908 00:57:09,920 --> 00:57:14,800 Speaker 1: is a multiple of ten. There you go. Three is 909 00:57:14,840 --> 00:57:17,200 Speaker 1: the number you wanted. Three is the number that's on 910 00:57:17,240 --> 00:57:20,240 Speaker 1: the check digit. You know that you got the right answer. Now, 911 00:57:20,240 --> 00:57:22,800 Speaker 1: the way the scanner does this is not by looking 912 00:57:22,840 --> 00:57:26,760 Speaker 1: at the digits. It's looking at the relationship between the 913 00:57:27,040 --> 00:57:33,120 Speaker 1: thin bars, the gaps between the bars, and how thicker 914 00:57:33,240 --> 00:57:36,000 Speaker 1: thin each of those are. Right. So if you look 915 00:57:36,040 --> 00:57:39,400 Speaker 1: at a UPC bar code, you're looking at just the bars. 916 00:57:39,600 --> 00:57:41,360 Speaker 1: You'll see some of the bars are thin, some of 917 00:57:41,400 --> 00:57:43,880 Speaker 1: the bars are a little thicker, some of the gaps 918 00:57:43,920 --> 00:57:46,280 Speaker 1: between the bars are thinner or thicker than the others. 919 00:57:47,160 --> 00:57:51,040 Speaker 1: That relationship of bars to gaps and the thickness of 920 00:57:51,080 --> 00:57:54,400 Speaker 1: them tells you what the value is of each of those. 921 00:57:54,640 --> 00:57:57,800 Speaker 1: And if you really really wanted to, you could decode 922 00:57:57,800 --> 00:58:01,800 Speaker 1: a barcode just by sight, once you know the basic 923 00:58:01,920 --> 00:58:06,040 Speaker 1: system of coding, and if you're able to determine what 924 00:58:06,400 --> 00:58:10,360 Speaker 1: is a narrow versus a wide bar or gap, because 925 00:58:10,400 --> 00:58:13,800 Speaker 1: that's very important. So the scanner is looking at the 926 00:58:13,920 --> 00:58:17,640 Speaker 1: series of bars and gaps and measuring those those widths, 927 00:58:18,280 --> 00:58:21,520 Speaker 1: and by measuring it, it then is able to match 928 00:58:21,600 --> 00:58:24,760 Speaker 1: that to a numeric code and verify whether or not 929 00:58:25,600 --> 00:58:27,680 Speaker 1: it matches that check digit at the end, and if 930 00:58:27,680 --> 00:58:30,320 Speaker 1: it does, the scan goes through, it gets matched to 931 00:58:30,360 --> 00:58:34,640 Speaker 1: a product and your charge however much for your Crispy dues. 932 00:58:35,760 --> 00:58:37,640 Speaker 1: I'm going to say it's five ninety nine for a bucks, 933 00:58:39,040 --> 00:58:42,400 Speaker 1: so that's what would pop up. There are variations on 934 00:58:42,440 --> 00:58:46,360 Speaker 1: these UPC codes, like zero suppressed number UPC codes, which 935 00:58:46,440 --> 00:58:48,840 Speaker 1: is exactly what sounds like. Any number that is a 936 00:58:48,960 --> 00:58:52,960 Speaker 1: zero that would otherwise appear in the code gets emitted omitted, 937 00:58:53,040 --> 00:58:57,200 Speaker 1: rather not emitted, it's omitted from the code, so it's shorter, 938 00:58:57,440 --> 00:59:00,640 Speaker 1: makes it a shorter barcode. But not everyone does this. 939 00:59:00,760 --> 00:59:06,760 Speaker 1: Only some products have this, and the manufacturing ID numbers 940 00:59:06,800 --> 00:59:09,240 Speaker 1: can have a specific meaning as well, depending on what 941 00:59:09,360 --> 00:59:12,760 Speaker 1: number they start with. So if you're manufacturing ID number 942 00:59:12,760 --> 00:59:15,680 Speaker 1: starts with a two, it means that it is a 943 00:59:15,800 --> 00:59:19,400 Speaker 1: random weight product. And by random weight we mean it's 944 00:59:19,440 --> 00:59:24,520 Speaker 1: something that doesn't come in a specific uniform size and 945 00:59:24,600 --> 00:59:27,800 Speaker 1: weight over and over again, so produce. For example, an 946 00:59:27,840 --> 00:59:31,560 Speaker 1: apple is going to be its own weight, right, You're 947 00:59:31,560 --> 00:59:34,439 Speaker 1: not going to get two apples of the exact same weight. 948 00:59:34,480 --> 00:59:37,040 Speaker 1: They're not all uniform. Whereas if I go out and 949 00:59:37,080 --> 00:59:39,320 Speaker 1: buy a box of Crispy Dues, it should be more 950 00:59:39,440 --> 00:59:44,240 Speaker 1: or less the same as a comparable Crispydoz box. Now, 951 00:59:44,280 --> 00:59:47,560 Speaker 1: if you have different sizes of boxes, then you have 952 00:59:47,600 --> 00:59:50,240 Speaker 1: different item numbers for each of those different sizes. The 953 00:59:50,280 --> 00:59:56,640 Speaker 1: item numbers are specific to a very particular instance of 954 00:59:56,680 --> 00:59:59,720 Speaker 1: an item. So if I've got a large box of 955 00:59:59,800 --> 01:00:02,640 Speaker 1: ch Us and a small box of Crispy Dues, each 956 01:00:02,680 --> 01:00:05,520 Speaker 1: of those will have its own five digit item number, 957 01:00:05,600 --> 01:00:09,200 Speaker 1: and thus the bars that correspond with it will be 958 01:00:09,320 --> 01:00:13,240 Speaker 1: slightly different as well. By the way, if you wanted 959 01:00:13,240 --> 01:00:17,160 Speaker 1: to know, like just as an example, what these bars mean, 960 01:00:17,480 --> 01:00:21,720 Speaker 1: I'm not going to go through the encoding of every 961 01:00:21,760 --> 01:00:24,640 Speaker 1: single number because it would be kind of silly. But 962 01:00:24,720 --> 01:00:26,880 Speaker 1: let me give you an example. If you want to 963 01:00:26,920 --> 01:00:30,919 Speaker 1: represent the number one in a UPC code, the way 964 01:00:30,960 --> 01:00:34,840 Speaker 1: it would work is that you would use first a 965 01:00:34,960 --> 01:00:38,000 Speaker 1: black bar that is two units wide. So in other words, 966 01:00:38,000 --> 01:00:41,000 Speaker 1: you'd have to look at the most narrow bar on 967 01:00:41,240 --> 01:00:46,800 Speaker 1: the UPC code that's probably one unit, right, You would 968 01:00:46,840 --> 01:00:50,320 Speaker 1: want a bar that's twice that width. The bar units 969 01:00:50,360 --> 01:00:55,320 Speaker 1: go up from one to four, so the widest bar 970 01:00:55,920 --> 01:00:58,520 Speaker 1: will probably be four units wide, the thinnest will probably 971 01:00:58,520 --> 01:01:00,920 Speaker 1: be one unit wide. You need one that's two units wide, 972 01:01:01,520 --> 01:01:04,720 Speaker 1: followed by a space that is two units wide, followed 973 01:01:04,720 --> 01:01:07,880 Speaker 1: by another black bar that's two units wide, followed by 974 01:01:07,880 --> 01:01:12,360 Speaker 1: a space that is one unit wide. So that is 975 01:01:12,400 --> 01:01:16,880 Speaker 1: the number one in barcode speak, and each of the 976 01:01:16,960 --> 01:01:20,960 Speaker 1: numerals is encoded in a similar way. Using these bars 977 01:01:21,000 --> 01:01:26,360 Speaker 1: and gaps of varying widths and reading them by sight 978 01:01:26,680 --> 01:01:30,520 Speaker 1: is possible but is not practical. But when you move 979 01:01:30,560 --> 01:01:35,320 Speaker 1: one of those bars across the scanner, the scanner shoots light, 980 01:01:36,000 --> 01:01:40,160 Speaker 1: typically red laser light at the barcode, and then a 981 01:01:40,200 --> 01:01:43,800 Speaker 1: sensor on the scanner is looking for reflected light, and 982 01:01:43,840 --> 01:01:47,600 Speaker 1: it can detect those bars and gaps based upon the 983 01:01:47,680 --> 01:01:51,320 Speaker 1: light that gets reflected back at the sensor. And as 984 01:01:51,400 --> 01:01:55,400 Speaker 1: long again as that last bar or that last digit 985 01:01:55,960 --> 01:01:59,640 Speaker 1: matches up with the math I talked about earlier, it 986 01:01:59,680 --> 01:02:03,240 Speaker 1: can in ring up the product and give you the 987 01:02:03,280 --> 01:02:07,800 Speaker 1: appropriate price for it. So really, the interesting thing here 988 01:02:07,880 --> 01:02:11,000 Speaker 1: is that the laser just makes this incredibly efficient. I 989 01:02:11,040 --> 01:02:14,360 Speaker 1: mean light travels faster than anything else in the world, 990 01:02:14,560 --> 01:02:17,320 Speaker 1: so it's no surprise that you can just swing one 991 01:02:17,360 --> 01:02:19,640 Speaker 1: of these barcodes by it a really good clip and 992 01:02:19,720 --> 01:02:23,840 Speaker 1: still get a really solid scan off of it, because 993 01:02:24,280 --> 01:02:28,120 Speaker 1: that information is going to the code and back to 994 01:02:28,560 --> 01:02:31,280 Speaker 1: the scanner at the speed of light, so it's not 995 01:02:31,320 --> 01:02:33,800 Speaker 1: like you're going to be moving that fast compared to 996 01:02:33,840 --> 01:02:37,240 Speaker 1: the scanner, and as long as it's got that good 997 01:02:37,240 --> 01:02:40,920 Speaker 1: fidelity there, then you're going to get a pretty successful scan. 998 01:02:41,000 --> 01:02:44,960 Speaker 1: That's why you can zoom stuff past that scanner pretty quickly. 999 01:02:47,040 --> 01:02:49,080 Speaker 1: Now let's go back to that timeline that we were 1000 01:02:49,080 --> 01:02:52,880 Speaker 1: talking about earlier. By nineteen seventy five, Laser Diode Labs 1001 01:02:52,920 --> 01:02:56,720 Speaker 1: Incorporated had developed a continuous wave semiconductor laser which would 1002 01:02:56,720 --> 01:03:00,000 Speaker 1: make it possible to transmit telephone conversations via optic fiber, 1003 01:03:00,640 --> 01:03:03,720 Speaker 1: which again blows my mind that you could turn something 1004 01:03:03,800 --> 01:03:08,360 Speaker 1: that's acoustic, not just into electricity, which is already magic 1005 01:03:08,800 --> 01:03:13,160 Speaker 1: in my mind, but into light signals. In nineteen seventy 1006 01:03:13,160 --> 01:03:15,960 Speaker 1: eight we got the laser disc, which was the first 1007 01:03:15,960 --> 01:03:20,280 Speaker 1: commercial use of an optical medium, that being something that 1008 01:03:20,680 --> 01:03:23,520 Speaker 1: could be stored on a device that would be read 1009 01:03:23,600 --> 01:03:26,920 Speaker 1: just by laser light alone. Laser discs were a predecessor 1010 01:03:26,960 --> 01:03:31,880 Speaker 1: to other optical based media like compact discs, akacds and DVDs, 1011 01:03:31,920 --> 01:03:35,760 Speaker 1: and blu rays. The earliest players actually used helium neon 1012 01:03:35,880 --> 01:03:38,200 Speaker 1: laser tubes in order to read the information stored on 1013 01:03:38,280 --> 01:03:41,560 Speaker 1: the discs, but later ones would switch to more affordable 1014 01:03:41,800 --> 01:03:46,720 Speaker 1: infrared laser diodes, so semiconductor based lasers. And as I 1015 01:03:46,760 --> 01:03:52,000 Speaker 1: said earlier, the semiconductor approach was less powerful and less 1016 01:03:52,000 --> 01:03:55,880 Speaker 1: expensive than other methods of generating lasers, so that helped 1017 01:03:55,920 --> 01:03:58,360 Speaker 1: bring the laser disc price down a little bit, but 1018 01:03:58,480 --> 01:04:01,720 Speaker 1: they were pretty expensive of it never really took off. 1019 01:04:01,760 --> 01:04:04,640 Speaker 1: I mean, there were people who loved laser discs, but 1020 01:04:05,440 --> 01:04:10,080 Speaker 1: they never became as popular as vhs or later on 1021 01:04:10,320 --> 01:04:14,120 Speaker 1: DVD players. Now. Later in nineteen seventy eight, Phillips would 1022 01:04:14,120 --> 01:04:17,000 Speaker 1: announce it was working on the compact disc project, Which 1023 01:04:17,040 --> 01:04:18,800 Speaker 1: is kind of funny because I always think of CDs 1024 01:04:18,840 --> 01:04:21,680 Speaker 1: as being either a late eighties or early nineties phenomenon, 1025 01:04:21,720 --> 01:04:25,280 Speaker 1: but its origins date back to the late seventies, and 1026 01:04:25,600 --> 01:04:28,840 Speaker 1: the first actual CD produced would come out in nineteen 1027 01:04:28,920 --> 01:04:31,520 Speaker 1: eighty two. And here's some more trivia for you. If 1028 01:04:31,520 --> 01:04:33,960 Speaker 1: you're ever doing that pub trivia, you remember the first 1029 01:04:33,960 --> 01:04:36,760 Speaker 1: thing with a barcode was Wrigley's Chewing Gum. The first 1030 01:04:36,960 --> 01:04:41,640 Speaker 1: CD to ever be produced was the album fifty Second 1031 01:04:41,720 --> 01:04:46,200 Speaker 1: Street by Billy Joel. That album actually had some pretty 1032 01:04:46,200 --> 01:04:50,240 Speaker 1: good songs on it, including My Life, which would later 1033 01:04:50,320 --> 01:04:52,560 Speaker 1: serve as the original theme song for the Tom Hanks 1034 01:04:52,560 --> 01:04:56,040 Speaker 1: sitcom Bosom Buddies. I guess you could probably tell that 1035 01:04:56,120 --> 01:04:58,960 Speaker 1: I'm patting this episode out a little bit, but this 1036 01:04:59,040 --> 01:05:02,080 Speaker 1: is again useful information if you're ever playing pub trivia. 1037 01:05:02,800 --> 01:05:04,520 Speaker 1: So if you ever hear what was the first album 1038 01:05:04,560 --> 01:05:07,160 Speaker 1: produced on CD, you now know it's fifty second Street 1039 01:05:07,240 --> 01:05:11,760 Speaker 1: by Billy Joel. In nineteen seventy nine, Gould would finally 1040 01:05:11,920 --> 01:05:14,920 Speaker 1: receive a patent that covered a pretty wide range of 1041 01:05:15,000 --> 01:05:17,680 Speaker 1: laser applications, so that meant that he finally won the 1042 01:05:17,760 --> 01:05:21,440 Speaker 1: laser battle. You'll remember that in the previous section I 1043 01:05:21,480 --> 01:05:24,320 Speaker 1: talked about how he had applied for a patent but 1044 01:05:24,720 --> 01:05:28,480 Speaker 1: was essentially denied that patent because of a previous application 1045 01:05:29,000 --> 01:05:33,560 Speaker 1: that had taken the intellectual property Gould had created and notarized. 1046 01:05:34,120 --> 01:05:38,360 Speaker 1: So this was the end of a very long battle here, well, 1047 01:05:38,800 --> 01:05:42,080 Speaker 1: at least as far As who has the legal right 1048 01:05:42,160 --> 01:05:46,480 Speaker 1: to claim the intellectual property of lasers, but it would 1049 01:05:46,520 --> 01:05:49,360 Speaker 1: be Shawlohe who was one of the parties who had 1050 01:05:49,560 --> 01:05:53,720 Speaker 1: filed the other patent back in a couple decades earlier, 1051 01:05:53,760 --> 01:05:57,000 Speaker 1: three decades earlier, and Bloembergen, who had actually received the 1052 01:05:57,040 --> 01:05:59,240 Speaker 1: Nobel Prize in Physics in nineteen eighty one for their 1053 01:05:59,280 --> 01:06:04,600 Speaker 1: work in laser spectroscopy. So people were doing well all 1054 01:06:04,640 --> 01:06:07,880 Speaker 1: around in the laser world. In the mid nineteen eighties, 1055 01:06:07,880 --> 01:06:11,840 Speaker 1: research laboratories began to use lasers to manipulate individual atoms, 1056 01:06:12,000 --> 01:06:15,200 Speaker 1: which is really cool. It opened up a brand new 1057 01:06:15,240 --> 01:06:19,720 Speaker 1: world in quantum science as well as just physical science. 1058 01:06:20,080 --> 01:06:24,240 Speaker 1: You may have seen the infamous picture of IBMS spelling 1059 01:06:24,240 --> 01:06:27,600 Speaker 1: out its name in individual atoms. It used lasers to 1060 01:06:27,640 --> 01:06:31,560 Speaker 1: position them. It's really pretty awesome. And by the late 1061 01:06:31,640 --> 01:06:34,400 Speaker 1: nineteen eighties Gould began to get royalties for his patents, 1062 01:06:34,400 --> 01:06:38,360 Speaker 1: so better late than never. In nineteen eighty seven, doctor 1063 01:06:38,560 --> 01:06:42,080 Speaker 1: Stephen Trockel became the first doctor to use an exemer 1064 01:06:42,160 --> 01:06:46,160 Speaker 1: laser to perform corrective surgery on a patient's eyes. This 1065 01:06:46,240 --> 01:06:51,960 Speaker 1: method was called the photorefractive keroatectomy or PRK surgery. That 1066 01:06:51,960 --> 01:06:54,240 Speaker 1: would start a line of research and development in laser 1067 01:06:54,240 --> 01:06:57,680 Speaker 1: eye surgery in general, with laser surgery debuting in nineteen 1068 01:06:57,760 --> 01:07:01,960 Speaker 1: ninety one, and I had laser surgery done just a 1069 01:07:02,040 --> 01:07:05,600 Speaker 1: few years ago. It corrected my vision. I talked about 1070 01:07:05,640 --> 01:07:08,120 Speaker 1: it on a podcast. Chris Pullett was on that one too, 1071 01:07:08,200 --> 01:07:10,520 Speaker 1: So you can do a search on tech Stuff's archives 1072 01:07:10,560 --> 01:07:13,040 Speaker 1: and hear all about laser eye surgery. And I think 1073 01:07:13,040 --> 01:07:15,680 Speaker 1: if you listen carefully enough you can actually hear Chris 1074 01:07:15,720 --> 01:07:20,280 Speaker 1: Pollette turn green. In the episode. He does a lot 1075 01:07:20,320 --> 01:07:25,320 Speaker 1: of unpleasant sounds because it was clear he was not 1076 01:07:25,400 --> 01:07:28,439 Speaker 1: comfortable in that episode. I might have taken a little 1077 01:07:28,480 --> 01:07:31,920 Speaker 1: extra glee from that. Now, skipping way ahead to two 1078 01:07:31,960 --> 01:07:35,040 Speaker 1: thousand and three, that was when researchers from NASA demonstrated 1079 01:07:35,080 --> 01:07:38,880 Speaker 1: that you could power an aircraft using lasers. The aircraft 1080 01:07:38,880 --> 01:07:43,040 Speaker 1: in question weighed just three hundred and eleven grams, not kilograms, 1081 01:07:43,680 --> 01:07:46,840 Speaker 1: just grams. It had a balsa wood frame and had 1082 01:07:46,880 --> 01:07:50,400 Speaker 1: a wingspan of one and a half meters that used 1083 01:07:50,400 --> 01:07:54,440 Speaker 1: an electric motor that was powered by a photovoltaic cell, 1084 01:07:54,600 --> 01:07:57,080 Speaker 1: so like a solar cell, but in this case it 1085 01:07:57,120 --> 01:08:02,040 Speaker 1: was specifically accepting light from this laser which was firing 1086 01:08:02,040 --> 01:08:04,760 Speaker 1: in an invisible spectrum, so you couldn't see the laser, 1087 01:08:05,160 --> 01:08:07,320 Speaker 1: but you can direct it at the cell that would 1088 01:08:07,320 --> 01:08:10,440 Speaker 1: provide the energy needed to convert it over into electricity 1089 01:08:10,800 --> 01:08:14,200 Speaker 1: and thus propel the aircraft, which is pretty cool. And 1090 01:08:14,240 --> 01:08:16,280 Speaker 1: today there are tons of uses of lasers, and some 1091 01:08:16,360 --> 01:08:19,439 Speaker 1: of them are really silly, like you know, they're being 1092 01:08:19,479 --> 01:08:22,120 Speaker 1: sold as cat toys and dog toys at this point, 1093 01:08:22,560 --> 01:08:25,400 Speaker 1: but some are really serious or things that are used 1094 01:08:25,400 --> 01:08:28,960 Speaker 1: in the medical field, for engineering, for industry, and we're 1095 01:08:29,000 --> 01:08:31,400 Speaker 1: looking at the possibility of even using them to propel 1096 01:08:31,479 --> 01:08:34,160 Speaker 1: spacecraft to other star systems, which is a really neat idea. 1097 01:08:35,080 --> 01:08:38,439 Speaker 1: This is based on the idea of the solar sail, 1098 01:08:39,240 --> 01:08:43,799 Speaker 1: where you have a spacecraft and it has a sale 1099 01:08:44,280 --> 01:08:49,800 Speaker 1: that you can direct light toward, and light has momentum. 1100 01:08:50,560 --> 01:08:54,320 Speaker 1: It's got relativistic momentum, So a photon does not have 1101 01:08:54,320 --> 01:08:57,400 Speaker 1: a lot of momentum by itself, but a stream of 1102 01:08:57,439 --> 01:09:01,519 Speaker 1: photons directed at a surface for long enough does have 1103 01:09:02,120 --> 01:09:04,920 Speaker 1: a physical push to it. And as it turns out, 1104 01:09:04,920 --> 01:09:09,080 Speaker 1: if you build very tiny spacecraft with a decent light 1105 01:09:09,200 --> 01:09:11,960 Speaker 1: sail and you use a laser on Earth, you can 1106 01:09:12,120 --> 01:09:17,960 Speaker 1: continuously accelerate that spacecraft over time so that reaches incredible speeds. 1107 01:09:18,160 --> 01:09:21,360 Speaker 1: Now that acceleration is going to be at a low rate, 1108 01:09:21,640 --> 01:09:25,200 Speaker 1: so it doesn't speed up immediately, but it will over 1109 01:09:25,240 --> 01:09:27,559 Speaker 1: time get faster and faster and faster. And in fact, 1110 01:09:27,640 --> 01:09:30,280 Speaker 1: this is what some people are suggesting we do to 1111 01:09:30,400 --> 01:09:34,679 Speaker 1: send spacecraft to the nearest star system are the one 1112 01:09:34,680 --> 01:09:37,400 Speaker 1: that's nearest to our own That would be the Alpha 1113 01:09:37,479 --> 01:09:40,920 Speaker 1: Centauri system, and Proxima B would be the place we 1114 01:09:40,920 --> 01:09:42,600 Speaker 1: would really want to take a look at. That's the 1115 01:09:44,200 --> 01:09:47,360 Speaker 1: planet around Proximus Centauri that is the closest to our 1116 01:09:47,400 --> 01:09:51,880 Speaker 1: Solar system, that is the most earthlike in nature. And 1117 01:09:51,960 --> 01:09:54,800 Speaker 1: so there's some people saying, why don't we release swarms 1118 01:09:54,840 --> 01:09:58,680 Speaker 1: of tiny spacecraft using these sort of light sails, use 1119 01:09:58,760 --> 01:10:02,920 Speaker 1: lasers to direct toward the Alpha Centauri system, And because 1120 01:10:02,960 --> 01:10:07,000 Speaker 1: of the incredible speeds they can reach, they can get 1121 01:10:07,000 --> 01:10:11,440 Speaker 1: to the Centari system within about twenty years. That's incredible 1122 01:10:11,520 --> 01:10:15,040 Speaker 1: because the Centauri system's four light years away. That means 1123 01:10:15,040 --> 01:10:18,519 Speaker 1: it takes four years for light to get there to hear. 1124 01:10:19,080 --> 01:10:23,000 Speaker 1: So to get there in twenty years using a physical spacecraft, 1125 01:10:23,640 --> 01:10:26,280 Speaker 1: you're moving at a really good clip Now, granted, at 1126 01:10:26,280 --> 01:10:29,719 Speaker 1: that speed, you're also just zooming by the Centauri system. 1127 01:10:29,720 --> 01:10:32,759 Speaker 1: You're not stopping for tea or anything, but still pretty 1128 01:10:32,760 --> 01:10:35,920 Speaker 1: cool idea that lasers could play an instrumental role in 1129 01:10:35,960 --> 01:10:38,400 Speaker 1: getting us to a different star system, or at least 1130 01:10:38,400 --> 01:10:41,360 Speaker 1: getting our eyes to a different star system. No humans 1131 01:10:41,400 --> 01:10:45,519 Speaker 1: would be traveling on those spacecraft, all right. That was 1132 01:10:45,560 --> 01:10:49,519 Speaker 1: our classic episode from June fourteenth, twenty seventeen, called Pew 1133 01:10:49,560 --> 01:10:53,120 Speaker 1: Pew Lasers. I hope you enjoyed it, and as always, 1134 01:10:53,160 --> 01:10:55,840 Speaker 1: I also hope that you are all well and I 1135 01:10:55,880 --> 01:11:05,280 Speaker 1: will talk to you again really soon. Tech Stuff is 1136 01:11:05,280 --> 01:11:09,840 Speaker 1: an iHeartRadio production. For more podcasts from iHeartRadio, visit the 1137 01:11:09,880 --> 01:11:13,519 Speaker 1: iHeartRadio app, Apple Podcasts, or wherever you listen to your 1138 01:11:13,560 --> 01:11:14,280 Speaker 1: favorite shows.