WEBVTT - Understanding and Detecting Radiation 0:00:04.240 --> 0:00:07.240 Welcome to tech Stuff, a production of I Heart Radios 0:00:07.320 --> 0:00:13.760 How Stuff Works. Hey there, and welcome to tech Stuff. 0:00:13.800 --> 0:00:16.919 I'm your host, Jonathan Strickland. I'm an executive producer with 0:00:16.960 --> 0:00:20.079 iHeart Radio and a love of all things tech, and 0:00:20.200 --> 0:00:25.000 inspired by my last episode about smoke detectors, I thought 0:00:25.040 --> 0:00:28.560 I would do an episode about radiation and radiation detectors. 0:00:29.160 --> 0:00:32.479 And I want to define terms like radiation and radioactivity, 0:00:32.520 --> 0:00:35.479 to talk about the different types of radiation there are, 0:00:35.960 --> 0:00:40.400 and to differentiate between ionizing and non ionizing radiation and 0:00:40.479 --> 0:00:46.680 chat about the technology around it. So first, what is radiation. Well, 0:00:47.120 --> 0:00:50.080 it's a fairly broad term with lots of different meanings 0:00:50.240 --> 0:00:52.960 as it turns out, but I think that's part of 0:00:53.000 --> 0:00:55.960 why there's frequently a lot of confusion around the concept 0:00:55.960 --> 0:00:59.040 of radiation. But there are a couple of definitions that 0:00:59.200 --> 0:01:01.800 for our purpose as we want to focus on, and 0:01:01.920 --> 0:01:04.880 really the one that we're truly interested in is the 0:01:04.920 --> 0:01:09.119 process of admitting radiant energy in the form of waves 0:01:09.240 --> 0:01:12.240 or particles as a definition I took from the Miriam 0:01:12.360 --> 0:01:16.959 Webster Dictionary. By the way, so radiation can involve electromagnetic 0:01:17.040 --> 0:01:20.959 waves or it might involve sub atomic particles. Uh, some 0:01:21.160 --> 0:01:25.200 radiation has the potential to be harmful, even deadly in 0:01:25.240 --> 0:01:30.200 sufficient intensities and length of exposure. Some radiation is relatively safe, 0:01:30.400 --> 0:01:35.600 particularly under specific controls. So let's start with some early 0:01:35.720 --> 0:01:40.640 discoveries of electro magnetic radiation, as those predate our understanding 0:01:40.800 --> 0:01:46.120 of particle based radiation. So our story begins in eighteen 0:01:46.240 --> 0:01:50.960 hundred with an early scientist named William Herschel. And Willie 0:01:51.080 --> 0:01:53.600 was interested in learning more about the spectrum of light, 0:01:54.200 --> 0:01:56.400 and it was already understood that if you were to 0:01:56.400 --> 0:02:00.000 pass light through a prism, you could separate light into 0:02:00.040 --> 0:02:03.720 different colors. You know, the good old roy g BIV spectrum, 0:02:03.800 --> 0:02:07.920 which stands for red, orange, yellow, green, blue, indigo, and violet. 0:02:08.480 --> 0:02:11.440 The spectrum will always be in that order. Anytime you 0:02:11.480 --> 0:02:14.720 pass light through a prism, it's going to break into 0:02:14.760 --> 0:02:19.480 those bands in that order, and those bands actually represent 0:02:19.880 --> 0:02:24.760 bands of frequencies of light waves. Herschel was wondering if 0:02:24.800 --> 0:02:28.640 the different colors of light produced different amounts of heat, 0:02:29.160 --> 0:02:32.720 So is one type of light warmer than another, So 0:02:32.760 --> 0:02:36.160 he set up a system in which he positioned thermometers 0:02:36.200 --> 0:02:40.560 at each color displayed from light passing through a prism. 0:02:40.720 --> 0:02:43.040 So he sets up a prism in his window, lights 0:02:43.040 --> 0:02:46.800 coming through it, and it's hitting a table, and it 0:02:46.880 --> 0:02:50.720 divides up into different bands of color. He sets the 0:02:50.360 --> 0:02:53.720 thermometers in each band of color, and he happened to 0:02:53.760 --> 0:02:57.000 have an extra thermometer just beyond the red end of 0:02:57.040 --> 0:02:59.440 the spectrum, so it's actually in the dark. It was 0:02:59.480 --> 0:03:02.560 beyond the range of the visible light. He had no 0:03:02.600 --> 0:03:05.920 way of knowing it, but he had, by happy coincidence, 0:03:06.280 --> 0:03:10.920 placed a thermometer right where the infrared band was. And 0:03:10.960 --> 0:03:15.840 we can't see infrared light, but that light does transmit heat. 0:03:16.400 --> 0:03:19.080 In fact, Herschel was surprised to see that it was 0:03:19.200 --> 0:03:21.880 that thermometer, the one that was in the darkness, just 0:03:22.000 --> 0:03:25.720 beyond the red range, that actually registered the highest temperature 0:03:25.760 --> 0:03:28.600 out of all the thermometers he had set out. And 0:03:28.639 --> 0:03:32.200 we often talked about heat radiating outward from a source. 0:03:33.240 --> 0:03:37.480 In eighteen o one, another big thinker named Johann Wilhelm 0:03:37.560 --> 0:03:41.760 Ritter built upon Herschel's experiment. He decided to see if 0:03:41.760 --> 0:03:45.440 perhaps there was anything beyond the other end of the spectrum, 0:03:45.480 --> 0:03:48.120 a k a. The violet end. In fact, he really 0:03:48.160 --> 0:03:52.880 discovered it sort of by accident. Ritter experimented by using 0:03:52.920 --> 0:03:56.320 a substance called silver chloride, and this is a chemical 0:03:56.400 --> 0:04:00.800 that turns black if it's exposed to sunlight. Ritter built 0:04:01.160 --> 0:04:05.080 on the understanding that blue light would produce a greater 0:04:05.160 --> 0:04:09.800 reaction in silver chloride than red light, so he did 0:04:09.800 --> 0:04:12.920 a variation on Herschel's experiment. He again used a prism 0:04:12.960 --> 0:04:16.200 to break the light into bands of color, and then 0:04:16.279 --> 0:04:19.480 within each band of color he placed a vile a 0:04:19.600 --> 0:04:23.839 silver chloride to see if the reactions were different across 0:04:23.920 --> 0:04:27.760 the spectrum of light. He could see that, indeed, the 0:04:27.800 --> 0:04:31.360 reaction did vary across the spectrum. The closer you got 0:04:31.400 --> 0:04:35.440 to the violet side of the spectrum, the more intense 0:04:36.000 --> 0:04:40.600 the reaction was, and it was most evident just beyond 0:04:41.160 --> 0:04:43.600 the violet side, in an area where there was no 0:04:43.720 --> 0:04:47.920 visible light at all. So clearly there was something going 0:04:47.960 --> 0:04:50.400 on on that end of the spectrum. So on the 0:04:50.400 --> 0:04:53.599 red end you were getting some sort of heat which 0:04:53.640 --> 0:04:56.240 we now know is infrared, and on the violet end 0:04:56.360 --> 0:04:59.920 there's something else that was really reacting to silver chloride. 0:05:00.400 --> 0:05:04.120 So Ritter would call this chemical raise, which to this 0:05:04.240 --> 0:05:07.680 very day we don't do anymore. Now today we call 0:05:07.720 --> 0:05:11.560 it ultraviolet light. Herschel and Ritter had made the first 0:05:11.600 --> 0:05:15.599 steps to increase our understanding of the electromagnetic spectrum, of 0:05:15.640 --> 0:05:19.680 which visible light is just one tiny part, and as 0:05:19.680 --> 0:05:22.000 we would build on that understanding, we'd also gain more 0:05:22.000 --> 0:05:25.480 information about what effects these types of radiation can have 0:05:25.680 --> 0:05:28.680 on us. Some of them have very little effect on us, 0:05:29.000 --> 0:05:32.680 some of them can have a drastic effect on us. 0:05:33.480 --> 0:05:35.520 And it would take a lot more time, but we 0:05:35.560 --> 0:05:38.360 would gradually begin to understand that if you look at 0:05:38.360 --> 0:05:42.720 the spectrum, it includes everything from radio waves on one 0:05:42.760 --> 0:05:45.880 extreme end of it to gamma raise on the other 0:05:46.040 --> 0:05:50.720 end of it, and these waves vary in wavelength, frequency, 0:05:50.800 --> 0:05:55.240 and energy. So on one extreme end you've got those 0:05:55.360 --> 0:06:00.400 radio waves. These can have really long wavelengths, measuring hens 0:06:00.400 --> 0:06:03.520 of miles, like sixty two miles or a hundred kilometers 0:06:03.600 --> 0:06:07.840 for wavelengths of certain radio frequencies. So if you had 0:06:07.880 --> 0:06:11.240 a perfectly steady radio wave, like just imagine, it's a 0:06:11.240 --> 0:06:13.920 perfect signal you. If you were to map it out, 0:06:13.920 --> 0:06:17.200 it would be a beautiful sign wave. If you measured 0:06:17.360 --> 0:06:20.960 from the peak at one point to the next peak, 0:06:21.600 --> 0:06:24.760 that's the wavelength. That's what would have been a hundred 0:06:24.880 --> 0:06:30.279 kilometers in distance an enormous wave. The frequency of a 0:06:30.360 --> 0:06:35.480 wave refers to how frequently a specific point on a wavelength, 0:06:35.800 --> 0:06:39.239 you know, like that peak, how frequently you could see 0:06:39.279 --> 0:06:43.159 that point on each wave pass a given reference point 0:06:43.320 --> 0:06:47.240 within a second. So with the longest radio waves at 0:06:47.240 --> 0:06:50.599 the lowest frequencies, you're talking about a frequency of around 0:06:51.000 --> 0:06:55.599 three thousand cycles per second, meaning that in one seconds time, 0:06:56.240 --> 0:07:00.440 three thousand peaks past that given point of reference. Now, 0:07:00.440 --> 0:07:03.560 one thing to keep in mind is that this is 0:07:03.680 --> 0:07:08.600 electromagnetic radiation. An electromagnetic radiation all travels at the same speed, 0:07:08.839 --> 0:07:11.480 that being the speed of light. Now, we do have 0:07:11.480 --> 0:07:15.080 to remember the speed of light isn't a constant across 0:07:15.200 --> 0:07:20.280 all media. It's a constant within each media. So we 0:07:20.280 --> 0:07:21.840 we usually when we're talking about the speed of light, 0:07:21.880 --> 0:07:24.440 we're talking about within the vacuum of space. But if 0:07:24.520 --> 0:07:28.280 light is traveling through an atmosphere or through water or something, 0:07:28.440 --> 0:07:31.080 it actually does travel at a different speed than that 0:07:31.680 --> 0:07:36.040 because it it's all dependent upon the medium. Still, electromagnetic 0:07:36.320 --> 0:07:42.800 radiation travels at that speed. So a wavelength of uh, 0:07:42.880 --> 0:07:45.600 you know, one wavelength of of a radio wave is 0:07:45.600 --> 0:07:48.600 traveling at the speed of light, as is one wavelength 0:07:48.640 --> 0:07:53.000 of gamma radiation. However, because the radio waves are so 0:07:53.080 --> 0:07:57.800 long and the gamma rays are so short in wavelength, 0:07:58.400 --> 0:08:02.160 the frequency has to be different, right. The frequency of 0:08:02.200 --> 0:08:04.680 the radio waves has to be lower than the frequency 0:08:04.760 --> 0:08:07.760 of gamma rays because you get way more gamma rays 0:08:07.880 --> 0:08:11.480 passing within a frame of a second, even though they're 0:08:11.520 --> 0:08:14.400 both traveling at the same speed. All right, That gets confusing, right, 0:08:14.440 --> 0:08:17.280 So I like to explain this with an analogy. Imagine 0:08:17.320 --> 0:08:22.560 you've got two identical straight roads, one lane wide, and 0:08:22.640 --> 0:08:25.560 they're right next to each other. Down one road, you 0:08:25.560 --> 0:08:29.480 have a series of buses, and each bus super long, 0:08:29.800 --> 0:08:33.640 measures eighteen meters in length, traveling down the road at 0:08:33.679 --> 0:08:37.240 fifty KOs per hour, and there's one meter of space 0:08:37.320 --> 0:08:41.680 in between each bus. So bus number one eighteen meters 0:08:41.760 --> 0:08:43.760 long than you have a meter, and a bus number 0:08:43.800 --> 0:08:45.680 two is eighteen meters long than you have a meter. 0:08:46.760 --> 0:08:49.760 That's dangerous, but whatever, they're traveling down at fifty an hour, 0:08:49.880 --> 0:08:52.760 perfectly in sync with each other. On the other road, 0:08:53.160 --> 0:08:55.800 do you have a series of zippy little smart cars 0:08:55.840 --> 0:08:59.040 and each smart car measures just three meters in length. 0:08:59.440 --> 0:09:01.720 They're also going down the road at fifty kilometers per 0:09:01.720 --> 0:09:04.360 hour with a meter of space in between each pair 0:09:04.400 --> 0:09:08.199 of cars. Now, individual vehicles are all traveling at the 0:09:08.240 --> 0:09:10.920 same speed, they're all traveling at fifty kilometers per hour. 0:09:11.040 --> 0:09:14.040 But the smart cars aren't as long as the buses. 0:09:14.440 --> 0:09:18.760 So if you were to have a accounter, there's someone 0:09:18.800 --> 0:09:21.360 standing by the bus lane and there's someone standing by 0:09:21.360 --> 0:09:23.800 the smart car lane, and they're holding a little counter 0:09:23.920 --> 0:09:27.040 in their hands. The person next to the smart cars 0:09:27.080 --> 0:09:29.360 is going to count way more smart cars in the 0:09:29.360 --> 0:09:32.240 same amount of time as the person counting the buses. 0:09:32.640 --> 0:09:35.520 And it's not because smart cars are traveling faster. They're not. 0:09:35.640 --> 0:09:38.200 They're just smaller, so more of them can go by 0:09:38.280 --> 0:09:40.600 within that given amount of time. The same thing is 0:09:40.640 --> 0:09:45.840 true with wavelengths of the electromagnetic spectrum red light, blue light, 0:09:46.080 --> 0:09:48.679 X rays, radio waves. They're all traveling at the same speed. 0:09:48.679 --> 0:09:50.920 They just have different wavelengths, so they have to have 0:09:51.000 --> 0:09:54.280 different frequencies. Now, as I said earlier, in those early 0:09:54.400 --> 0:09:58.360 days in the nineteenth century, we didn't have this level 0:09:58.440 --> 0:10:02.920 of understanding. We weren't aware of different wavelengths and frequencies, 0:10:03.200 --> 0:10:06.360 and we didn't know that longer wavelengths and lower frequencies 0:10:06.400 --> 0:10:11.280 of electromagnetic radiation carry less energy, whereas high frequencies and 0:10:11.480 --> 0:10:17.160 very small wavelengths of electromagnetic radiation can pack way more energy. 0:10:17.280 --> 0:10:19.200 If you were to look at the experiments of Herschel 0:10:19.240 --> 0:10:22.000 and Ritter, you might actually think that that's not the case, 0:10:22.080 --> 0:10:24.960 because the invisible light off the red end of the 0:10:25.000 --> 0:10:28.600 spectrum was carrying a lot of heat. It was heating 0:10:28.679 --> 0:10:31.200 up a thermometer more than the others, so maybe it 0:10:31.200 --> 0:10:34.560 carries more energy. And whereas the violet side you just 0:10:34.600 --> 0:10:37.800 saw silver chloride change color. So it would take a 0:10:37.840 --> 0:10:40.640 lot more experimentation to get a deeper understanding of the 0:10:40.679 --> 0:10:44.040 actual nature of electromagnetic radiation. Now to go into the 0:10:44.040 --> 0:10:48.480 full history of how that understanding would unfold is the 0:10:48.520 --> 0:10:51.720 stuff of college lecture series, So I'll just give very 0:10:51.800 --> 0:10:54.520 brief summaries to get us kind of closer to our objective. 0:10:54.960 --> 0:10:58.920 In the nineteenth century you had numerous scientists and inventors 0:10:58.960 --> 0:11:01.520 who were observing all sorts of interesting stuff that would 0:11:01.600 --> 0:11:06.240 later become integrated into our knowledge of electromagnetism. So Michael 0:11:06.240 --> 0:11:09.720 Faraday did a great deal of work exploring the relationship 0:11:09.800 --> 0:11:14.160 between electric and magnetic fields. For example, his work would 0:11:14.200 --> 0:11:19.120 inspire a Scottish physicist named James Clerk Maxwell to look 0:11:19.120 --> 0:11:23.160 into the matter further, and Maxwell made predictions about electromagnetic 0:11:23.240 --> 0:11:27.160 radiation based on those early experiments and observation, saying, well, 0:11:27.960 --> 0:11:30.720 based on what we know, I expect that will eventually 0:11:30.760 --> 0:11:36.200 find something that fits this mathematical uh example of what 0:11:36.440 --> 0:11:39.280 should be there, and his predictions proved to be accurate, 0:11:39.440 --> 0:11:41.800 and they in turn would serve as an important foundation 0:11:41.800 --> 0:11:45.120 for Albert Einstein's special theory of relativity, as the one 0:11:45.120 --> 0:11:48.600 that gives us the famous equation equals mc squared, which 0:11:48.640 --> 0:11:51.520 tells us that energy and mass are related at an 0:11:51.559 --> 0:11:56.480 intrinsic level. And Maxwell's observations about electromagnetic radiation would lead 0:11:56.480 --> 0:12:00.240 to a theory about heat radiation that in turn would 0:12:00.280 --> 0:12:06.240 be overturned by Max Planck, whose formulation of quantum hypothesis 0:12:06.240 --> 0:12:09.000 to describe how heat radiates would become the predominant one. 0:12:09.360 --> 0:12:11.560 But all of that is a little outside of our scope. 0:12:11.640 --> 0:12:14.200 So the point I wanted to make is that the 0:12:14.280 --> 0:12:18.840 nineteenth century was a boom time for scientific observations and discoveries, 0:12:19.080 --> 0:12:21.040 and the things we would learn would serve us well 0:12:21.080 --> 0:12:23.720 as we moved into the next phase of understanding of radiation. 0:12:23.760 --> 0:12:26.760 And what it's all about. So the other big discoveries 0:12:26.800 --> 0:12:29.800 that relate to this episode came about at the end 0:12:30.160 --> 0:12:32.280 of the nineteenth century, so we get to look at 0:12:32.280 --> 0:12:36.520 both ends of the eighteen hundreds. In eight Vilhelm runjeon 0:12:36.880 --> 0:12:39.760 which I mentioned him in the last episode, he was 0:12:39.800 --> 0:12:42.920 experimenting with a cathode ray tube, and I talked about 0:12:43.160 --> 0:12:46.559 that again in the Smoke Detective episode. Essentially, these are 0:12:46.640 --> 0:12:49.480 devices that produce streams of electrons by heating up a 0:12:49.520 --> 0:12:52.080 filament inside a glass vacuum tube, kind of similar to 0:12:52.120 --> 0:12:56.719 a light bulb. Runjen found that as he applied an 0:12:56.720 --> 0:13:00.520 electric voltage to the cathode ray tube a light detection 0:13:00.640 --> 0:13:04.080 screen in his lab that was made out of barium 0:13:04.280 --> 0:13:09.600 platina cyanide fluorest, it actually lit up. It detected light 0:13:09.640 --> 0:13:12.080 even though there was no visible light there. So he 0:13:12.120 --> 0:13:16.400 began to experiment with this phenomenon, this invisible light that 0:13:16.520 --> 0:13:19.880 was causing this this detector to light up, and that 0:13:19.960 --> 0:13:25.440 included putting objects between the cathode ray tube and the screen, 0:13:25.520 --> 0:13:27.080 and he saw that whatever was coming out of the 0:13:27.120 --> 0:13:30.200 tube seemed to be penetrating through objects and it was 0:13:30.240 --> 0:13:33.040 still hitting the screen on the other side. He found 0:13:33.040 --> 0:13:38.320 that if he put photographic film, the energy would interact 0:13:38.360 --> 0:13:40.280 with the photographic film, and if you put something in 0:13:40.320 --> 0:13:43.760 between the film and the cathode ray tube, he could 0:13:43.760 --> 0:13:48.160 get a really interesting image of it. Uh, it's like 0:13:48.240 --> 0:13:52.679 you could see through certain stuff pretty clearly. So, for example, 0:13:52.880 --> 0:13:55.480 his hand, he put his hand in front of it 0:13:55.720 --> 0:13:58.839 and he took a photo. Then the picture would show 0:13:59.240 --> 0:14:04.160 the skeleton in hand. It would it would show through 0:14:04.520 --> 0:14:07.920 the soft tissues of his hand, and he thought, well, 0:14:07.960 --> 0:14:12.080 this is interesting. He discovered a new type of radiation 0:14:12.120 --> 0:14:14.480 and he called it the X ray because what the 0:14:14.480 --> 0:14:17.559 heck was going to call it? It was an unknown quantity, 0:14:17.760 --> 0:14:21.960 and in mathematics we often refer to unknown quantities as X, 0:14:22.040 --> 0:14:24.680 like solve for X. So it was meant to be 0:14:24.720 --> 0:14:29.640 a placeholder. X rays just it turned into the permanent 0:14:29.720 --> 0:14:32.640 name for the stuff. Now. Initially, no one was aware 0:14:32.880 --> 0:14:36.200 that X ray radiation was potentially dangerous with its shorter 0:14:36.320 --> 0:14:41.360 wavelength and higher frequency and energy than visible light. In fact, 0:14:41.400 --> 0:14:43.840 no one was even sure that was another form of light. 0:14:44.120 --> 0:14:46.320 They thought it might be, but they weren't certain, and 0:14:46.400 --> 0:14:50.240 that wouldn't be proven until nineteen twelve. But people began 0:14:50.280 --> 0:14:54.560 to understand that there was some potential danger the X 0:14:54.640 --> 0:14:59.040 rays fairly early on. In eighteen nineties six, the year 0:14:59.160 --> 0:15:05.360 after Runton's UH discovery, the journal Nature published an article 0:15:05.400 --> 0:15:08.560 with the title The Harmful Effects of X rays. And 0:15:08.600 --> 0:15:11.240 in that article there was a story about a guy 0:15:11.280 --> 0:15:14.920 who had worked as an X ray demonstrator in London, 0:15:15.480 --> 0:15:19.960 and he described the effects of X ray exposure that 0:15:20.400 --> 0:15:25.800 he experienced, particularly on his hands, after working for a 0:15:25.840 --> 0:15:29.440 full summer doing demonstrations with X ray machines for several 0:15:29.440 --> 0:15:33.320 hours a day, I'm going to quote an excerpt. In 0:15:33.360 --> 0:15:37.240 the first two or three weeks, I felt no inconvenience, 0:15:37.560 --> 0:15:40.000 but after a while appeared on the fingers of my 0:15:40.160 --> 0:15:44.320 right hand many dark spots which pierced under the skin, 0:15:44.760 --> 0:15:48.280 and gradually they became very painful. The rest of the 0:15:48.280 --> 0:15:52.760 skin was red and strongly inflamed. My hand was so 0:15:52.840 --> 0:15:56.160 bad that I was constantly forced to bathe it in 0:15:56.400 --> 0:16:01.040 very cold water. An ointment momentarily on the pain. But 0:16:01.160 --> 0:16:05.000 the epidermist had dried up, had become hard and yellow 0:16:05.280 --> 0:16:09.600 like parchment, and completely insensible, so I was not surprised 0:16:09.840 --> 0:16:15.320 when my hand began to peel. From that point, the 0:16:15.360 --> 0:16:17.920 guy goes on to describe how things got even worse, 0:16:18.320 --> 0:16:21.160 like he began to lose fingernails and stuff. But I'm 0:16:21.160 --> 0:16:24.240 gonna leave out the rest of the grizzly details. The 0:16:24.280 --> 0:16:26.880 point is people are starting to notice that the longer 0:16:26.920 --> 0:16:30.680 someone was exposed to X rays, the more severe the 0:16:30.760 --> 0:16:34.640 consequences seemed to be. Short exposures did not appear to 0:16:34.640 --> 0:16:38.080 be as serious, but this was something that people were 0:16:38.080 --> 0:16:41.080 starting to get a little concerned about that would grow 0:16:41.720 --> 0:16:43.920 in the years to come. But first, let's take a 0:16:44.000 --> 0:16:54.560 quick break before we jump into that discussion. Okay, so 0:16:55.120 --> 0:16:57.240 before we took our break, I was talking about how 0:16:57.280 --> 0:17:01.120 people were beginning to understand that X rays could be dangerous. 0:17:01.880 --> 0:17:07.160 That didn't stop early irresponsible implementations of X ray machines. However, 0:17:07.359 --> 0:17:10.399 people thought of these as curiosities. They were things to 0:17:10.480 --> 0:17:14.919 be celebrated and experienced. Thomas Edison thought everyone would have 0:17:15.000 --> 0:17:17.399 one in their own home and thought perhaps they should 0:17:17.480 --> 0:17:20.280 have them, because again, they didn't understand the dangers yet. 0:17:20.600 --> 0:17:23.880 People would even have X ray parties in which guests 0:17:23.920 --> 0:17:27.359 would take X ray photos of themselves, you know, of 0:17:27.440 --> 0:17:31.600 their foot, or their hand, or even their face, and 0:17:31.760 --> 0:17:34.359 they would get to keep the photographs at the end 0:17:34.400 --> 0:17:38.800 of the party. Shoe stores installed X ray fluoroscopes to 0:17:38.840 --> 0:17:41.280 get a look at a person's foot, And while a 0:17:41.320 --> 0:17:44.440 person visiting the store wouldn't likely walk away with a 0:17:44.560 --> 0:17:47.960 lethal dose of radiation, the folks who were working at 0:17:47.960 --> 0:17:52.080 the store were exposed to X rays much more frequently 0:17:52.160 --> 0:17:55.919 and for longer durations, and many of them would suffer 0:17:55.960 --> 0:17:59.360 the consequences. But all of those awful discoveries would take 0:17:59.480 --> 0:18:04.320 some times, so people didn't immediately notice the issues. Meanwhile, 0:18:04.680 --> 0:18:07.720 let's get back to the discovery of radioactivity by talking 0:18:07.760 --> 0:18:12.600 about the other kind of radiation, not the electro magnetic type. 0:18:12.960 --> 0:18:15.560 So in eighteen ninety six, which was that same year 0:18:15.720 --> 0:18:18.600 that the Nature article about the dangers of X rays 0:18:18.680 --> 0:18:22.240 came out, there was a physicist named al Marie Beccarel 0:18:22.640 --> 0:18:25.840 who was wondering if some materials he was working with 0:18:25.960 --> 0:18:30.040 might produce the same sort of energy that Rundgen's X 0:18:30.160 --> 0:18:33.920 rays seemed to create. One of those materials that Beckerel 0:18:34.040 --> 0:18:37.800 was working with was a crystal made up of uranium salts. Now, 0:18:37.840 --> 0:18:41.959 the various materials Beccarel had interest in all shared a 0:18:42.000 --> 0:18:45.959 common trait. They were all phosphorescent, so they could all glow, 0:18:46.840 --> 0:18:49.560 and he wondered if they were giving off the same 0:18:49.600 --> 0:18:52.920 sort of invisible light stuff that run Gen was observing 0:18:52.920 --> 0:18:56.119 with X rays. So Beckarel set up an experiment. He 0:18:56.200 --> 0:18:59.679 put down a photographic plate. He totally covered it so 0:18:59.720 --> 0:19:01.720 that one of it would be exposed to light because 0:19:01.720 --> 0:19:05.639 that would activate the photoreactive chemicals on the plate. And 0:19:05.720 --> 0:19:08.760 on top of the covering he put a selection of 0:19:08.840 --> 0:19:13.720 his phosphorescent crystals to see if any of them would 0:19:13.720 --> 0:19:17.159 interact with the photo reactive chemicals. And he exposed the 0:19:17.160 --> 0:19:19.399 whole thing to the sun, you know, thinking that the 0:19:19.440 --> 0:19:23.800 sun would charge these various crystals. And at the end 0:19:23.840 --> 0:19:26.000 of the experiment he discovered that out of all the 0:19:26.000 --> 0:19:28.280 different things he was testing, only one seemed to have 0:19:28.320 --> 0:19:31.040 any effect at all, and that was the rock crystal 0:19:31.080 --> 0:19:34.199 that was actually made up of uranium salt, and that 0:19:34.280 --> 0:19:36.200 was the only one that seemed to have fogged up 0:19:36.280 --> 0:19:40.199 the the photoplate. So he thought, well, I'll do a 0:19:40.240 --> 0:19:43.240 longer test. I'll leave it out in the sun longer, 0:19:43.320 --> 0:19:45.960 see if I get a bigger, more clear result. But 0:19:46.040 --> 0:19:49.040 the weather at that point wasn't cooperating. It had gotten cloudy, 0:19:49.119 --> 0:19:50.760 so he couldn't put it out in the sun. So 0:19:51.119 --> 0:19:55.200 he takes his photographic plates and his uranium salts and 0:19:55.400 --> 0:19:58.119 he stores them away and waits for the weather to 0:19:58.160 --> 0:20:00.560 get better. So they were actually stored next to each 0:20:00.600 --> 0:20:03.960 other in a dark cabinet. Several days later, as the 0:20:03.960 --> 0:20:06.879 weather was starting to finally clear out, he was getting 0:20:06.880 --> 0:20:10.040 ready to conduct his experiment, but he decided, you know what, 0:20:10.240 --> 0:20:12.840 before I do this, I better make sure these photographic 0:20:12.880 --> 0:20:16.720 plates are still good, because the chemicals can actually expire, 0:20:17.040 --> 0:20:20.800 and I'd be wasting my time if they aren't working anymore. 0:20:21.119 --> 0:20:24.160 So he picks one and develops it, and it happened 0:20:24.200 --> 0:20:27.040 to be one that was close to the iranium salts. 0:20:27.320 --> 0:20:30.439 Rock He was surprised to discover that the bits of 0:20:30.440 --> 0:20:33.080 the photographic plate that had been close to those uranium 0:20:33.080 --> 0:20:36.119 salts had images on them, even though the salts had 0:20:36.160 --> 0:20:38.320 not been exposed to sunlight. They've been stored in a 0:20:38.440 --> 0:20:42.400 dark cupboard, and he concluded that the uranium salts themselves 0:20:42.560 --> 0:20:45.000 were giving off some sort of emission that was being 0:20:45.080 --> 0:20:48.920 captured on this photographic plate. Henri Becarel had a couple 0:20:48.920 --> 0:20:54.280 of enterprising and brilliant assistants. One was Pierre Curie and 0:20:54.359 --> 0:20:58.560 the other was Marie Sklodowska, who would marry Pierre and 0:20:58.600 --> 0:21:04.840 become Marie Curie. She uh really was fascinated by radioactivity, 0:21:05.000 --> 0:21:07.119 and together with her husband, they began to study the 0:21:07.240 --> 0:21:11.000 ranium salts as well as looking for other similar materials 0:21:11.040 --> 0:21:15.760 that seemed to display this radioactive phenomena. They tested some 0:21:15.840 --> 0:21:19.439 mining operation waste. It's called a pitch blend. The mining 0:21:19.680 --> 0:21:21.600 operations were happy to get rid of it because it 0:21:21.680 --> 0:21:25.480 was just run off from their operations, and they found 0:21:25.520 --> 0:21:28.720 that it could contained traces of radioactive material, and eventually 0:21:28.720 --> 0:21:31.080 they were able to separate a small amount of it 0:21:31.200 --> 0:21:33.600 from the rest of the pitch blend, and it would 0:21:33.680 --> 0:21:38.200 later be called radium. It was far more radioactive than 0:21:38.280 --> 0:21:42.320 the uranium salts they had already worked with. The Curies 0:21:42.400 --> 0:21:44.960 and Beckrel would receive the Nobel Prize in Physics for 0:21:45.000 --> 0:21:49.160 their discoveries. Runen also received one earlier for his discovery 0:21:49.160 --> 0:21:52.800 of X rays, and then Pierre Curie would later tragically 0:21:52.920 --> 0:21:55.919 die in a traffic accident. Marie would go on to 0:21:56.000 --> 0:22:00.159 discover another radioact development, this one called polonium, and she 0:22:00.200 --> 0:22:03.360 would receive a second Nobel Prize, though that second one 0:22:03.440 --> 0:22:06.240 was in chemistry. She's one of only a few people 0:22:06.240 --> 0:22:09.760 who have ever received more than one Nobel Prize. Now, 0:22:09.760 --> 0:22:13.240 one thing Beckerel did with his own research was proved 0:22:13.640 --> 0:22:16.639 that the energy coming out of this uranium salt was 0:22:16.720 --> 0:22:19.600 not the same thing as X rays, and he did 0:22:19.640 --> 0:22:23.040 this by testing the uranium salts against X rays with 0:22:23.080 --> 0:22:26.480 a device that could generate a magnetic field. So X 0:22:26.560 --> 0:22:30.440 rays would pass through the magnetic field unimpeded. And that's 0:22:30.440 --> 0:22:33.920 because X ray radiation has no electric charge, and thus 0:22:33.920 --> 0:22:36.320 it has no magnetic field of its own, so it's 0:22:36.320 --> 0:22:38.800 not affected by magnetic field. It just passes through. Is 0:22:38.840 --> 0:22:41.959 that there's nothing else there but the radiation coming from 0:22:42.000 --> 0:22:46.679 the uranium salts bent upon encountering the magnetic field, and 0:22:46.720 --> 0:22:48.800 that told Beckarel that whatever was coming out of the 0:22:48.880 --> 0:22:52.280 uranium salts had an electric charge to it, because it 0:22:52.359 --> 0:22:53.879 had to have an electric charge in or to have 0:22:53.920 --> 0:22:57.240 its own magnetic field and thus be either attracted or 0:22:57.280 --> 0:23:00.840 repelled by the magnetic field and his testing vice. So 0:23:00.920 --> 0:23:05.359 Beckerel tested numerous types of radioactive substances using this approach 0:23:05.720 --> 0:23:10.160 and observed three basic results. Either radiation would bend one 0:23:10.200 --> 0:23:15.399 way using certain radioactive materials, and he would conclude, this 0:23:15.520 --> 0:23:19.919 is a positive radiation material because it is being attracted 0:23:19.960 --> 0:23:22.240 to the negative side of the magnetic field and repelled 0:23:22.240 --> 0:23:25.200 by the positive side, or it would bend the other way, 0:23:25.359 --> 0:23:27.639 so he would have the opposite conclusion. Okay, this is 0:23:27.760 --> 0:23:31.159 negative radiation because it's being attracted to the positive side 0:23:31.200 --> 0:23:34.480 and repelled by the negative side, or it passed straight 0:23:34.520 --> 0:23:37.200 through like X rays, and it would have no electrical 0:23:37.240 --> 0:23:39.280 charge at all, so it would be neutral. So you 0:23:39.320 --> 0:23:44.040 had positive, negative, and electrically neutral radiation. In their work, 0:23:44.240 --> 0:23:48.199 the Curies and Beckarel noted that prolonged exposure to some 0:23:48.240 --> 0:23:51.880 of these radioactive materials would result in injuries and ailments, 0:23:53.080 --> 0:23:55.480 like if you handled some of the more radioactive stuff 0:23:55.480 --> 0:23:57.840 like radium for any length of time, you could actually 0:23:57.880 --> 0:24:02.280 get burns on your skin, and you could suffer radiation sickness, 0:24:02.320 --> 0:24:06.919 which includes symptoms like nausea, but the extent of the 0:24:07.040 --> 0:24:12.200 damage was unknown for years. Marie cry died in nineteen 0:24:12.320 --> 0:24:16.680 thirty four of a plastic anemia, which was probably a 0:24:16.720 --> 0:24:20.639 consequence of her exposure to radioactive material over the years. 0:24:21.200 --> 0:24:24.720 It certainly would have increased the odds of her developing that, 0:24:25.280 --> 0:24:28.000