WEBVTT - Invention Playlist: The Camera Obscura 0:00:08.880 --> 0:00:12.239 Hey, welcome to Invention. My name is Robert Lamb and 0:00:12.360 --> 0:00:14.680 I'm Joe McCormick and Robert. Today, I want to start 0:00:14.720 --> 0:00:16.799 by doing something that we often try to do on 0:00:16.840 --> 0:00:18.800 Stuff Flow Your Mind and on this show too, which 0:00:18.840 --> 0:00:21.920 is trying to make something that's familiar weird again. Yes, 0:00:22.200 --> 0:00:24.480 the thing that I want to take from your familiar 0:00:24.520 --> 0:00:27.480 world and make you face the weirdness of it again 0:00:28.240 --> 0:00:31.160 is that we live in a techno culture that has 0:00:31.200 --> 0:00:38.080 the ability to create relatively objective, fixed media records of 0:00:38.600 --> 0:00:43.320 reality itself. And an example of this, of course, is 0:00:43.360 --> 0:00:47.080 the photograph. Think about the difference between a photograph and 0:00:47.120 --> 0:00:50.199 the real world. Uh so, you know, we're so used 0:00:50.240 --> 0:00:52.440 to photos at this point that we take them for granted, 0:00:52.479 --> 0:00:56.120 but try again to feel the weirdness and appreciate how 0:00:56.160 --> 0:00:59.240 strange it is and how mystical it is that that 0:00:59.320 --> 0:01:02.520 we have these objects around us. Like the physical world, 0:01:03.080 --> 0:01:07.640 you know, is this ongoing transient, always moving, always lightning 0:01:07.680 --> 0:01:12.520 and darkening, always transforming three dimensional space full of objects. 0:01:13.520 --> 0:01:16.040 But then you've got the photograph, which is a fixed 0:01:16.200 --> 0:01:20.319 two dimensional image on on a flat surface. And yet 0:01:20.360 --> 0:01:23.240 we think of the photograph as an objective or sort 0:01:23.280 --> 0:01:25.840 of semi objective. We can explore that distinction and a 0:01:25.840 --> 0:01:30.600 bit record of physical reality. It's definitely a record of something, 0:01:30.600 --> 0:01:34.640 but it's not exactly physical reality, is it. It's physical 0:01:34.720 --> 0:01:40.280 reality interpreted through this transformation process that partially resembles and 0:01:40.319 --> 0:01:44.720 partially does not resemble animal vision. Yeah, I mean and 0:01:44.720 --> 0:01:49.040 and and this is even without getting into modern or 0:01:49.040 --> 0:01:53.760 even twentieth century. Uh, you know, photo editing techniques, just 0:01:53.800 --> 0:01:58.840 like the raw photographic image that results. Yeah, is this 0:01:58.920 --> 0:02:01.800 thing that is it's really you can't think of it 0:02:01.920 --> 0:02:07.960 as as an approximation of of animal site of biological site. Uh, 0:02:08.000 --> 0:02:11.600 it's it's more like it's almost like a form of 0:02:11.720 --> 0:02:14.160 language in the same way that we've discussed them this 0:02:14.240 --> 0:02:16.760 and stuff to bully your mind before. How written language 0:02:16.800 --> 0:02:20.520 is like a thought that has taken and frozen so 0:02:20.560 --> 0:02:23.720 that it can retain the same form for the most 0:02:23.760 --> 0:02:27.400 part with some interpretations. And and that's sort of what 0:02:27.440 --> 0:02:31.800 we're doing with with photography. We're kind of freezing, uh, 0:02:31.919 --> 0:02:34.760 the mental image or some version of the mental image. 0:02:34.880 --> 0:02:38.080 Except it can also be misleading because I think photography 0:02:38.120 --> 0:02:41.560 has contributed to us having a skewed idea of what 0:02:41.720 --> 0:02:45.200 mental imagery is. It's actually led to us I think, 0:02:45.240 --> 0:02:49.359 having an idea that our mental imagery is like a 0:02:49.680 --> 0:02:53.920 fixed record that has full resolution at every you know, 0:02:54.000 --> 0:02:56.760 from corner to corner of the image, which, as we'll 0:02:56.760 --> 0:02:59.080 discuss also a little bit more in this episode, is 0:02:59.120 --> 0:03:01.480 not the case at all. Our vision is something more 0:03:01.560 --> 0:03:08.120 like a an interpretive illusion based on key bits of 0:03:08.320 --> 0:03:12.399 light data entering through the eyes. Yeah. And and yet, 0:03:12.720 --> 0:03:16.280 especially for you know, for us modern humans, we we 0:03:16.400 --> 0:03:20.680 often reinterpret our memories in the forum of photos, uh 0:03:20.760 --> 0:03:23.920 and and motion pictures. I know, I catch myself doing 0:03:24.000 --> 0:03:25.800 this all the time. I'll think back to, say, a 0:03:25.840 --> 0:03:28.560 moment from my childhood, and what I'm kind of doing 0:03:28.600 --> 0:03:32.239 is I'm kind of picturing a photograph, a photograph that 0:03:32.320 --> 0:03:35.160 might exist, because sometimes I am referring back to actual 0:03:35.200 --> 0:03:37.640 photographs that serve as kind of like a uh, you know, 0:03:38.320 --> 0:03:41.760 a bookmark for that memory, perhaps even the source of 0:03:41.760 --> 0:03:44.480 a memory, where I'm really remembering a picture of something 0:03:44.560 --> 0:03:47.040 rather than the experience. But other times I'm kind of 0:03:47.080 --> 0:03:50.840 forming some sort of how you know, half realized, half 0:03:50.840 --> 0:03:54.720 imaginary photo of what happened. But think about how different 0:03:54.720 --> 0:03:58.240 our memories of our childhood would be if there were 0:03:58.360 --> 0:04:02.960 no photographs whatso ever, like no even semi objective visual 0:04:03.080 --> 0:04:05.520 record of the world that we lived in. Back then, 0:04:05.600 --> 0:04:09.080 all we had was mental imagery and memory. Yeah, what 0:04:09.120 --> 0:04:12.119 if you were like most people and when a when 0:04:12.120 --> 0:04:16.560 I loved, when grew older or certainly passed away, you 0:04:16.680 --> 0:04:20.040 had no longer any real physical reminder of what they 0:04:20.080 --> 0:04:23.000 looked like. You could forget the face of your your 0:04:23.040 --> 0:04:25.160 father in a in a very real way. So I 0:04:25.200 --> 0:04:28.240 think it's absolutely clear that photography is one of the 0:04:28.240 --> 0:04:32.479 most revolutionary technologies that's ever been created. It has probably 0:04:32.560 --> 0:04:35.359 not just changed what humans are able to do, but 0:04:35.560 --> 0:04:38.400 has fundamentally in some ways altered the way we think, 0:04:38.480 --> 0:04:41.400 in the way we envision our own lives. But there 0:04:41.440 --> 0:04:44.960 was a long time before there was photography, and it's 0:04:44.960 --> 0:04:48.400 probably pretty tempting to think, well, you know, before photography, 0:04:48.600 --> 0:04:51.719 we just had imagination. We had drawing, we had painting. 0:04:51.720 --> 0:04:53.760 People could like look at the world around them and 0:04:53.760 --> 0:04:56.120 try to interpret it in paintings, but would be the 0:04:56.160 --> 0:04:59.520 closest thing we had to a visual, uh sort of 0:04:59.760 --> 0:05:03.520 sy my objective record of what the world looked like. 0:05:04.040 --> 0:05:07.000 But that's not exactly right, because there was a sort 0:05:07.040 --> 0:05:11.120 of stepping stone before we had photography, we had the 0:05:11.160 --> 0:05:13.919 camera obscura. That's right, and that is going to be 0:05:13.960 --> 0:05:17.640 what we're going to focus this episode on. Basically, the 0:05:17.640 --> 0:05:21.720 the approach here is we want to devote like three episodes. Uh, 0:05:21.920 --> 0:05:24.719 first the camera obscura, and then do an episode on 0:05:25.000 --> 0:05:27.680 on the origins of photography, and then do an episode 0:05:27.800 --> 0:05:31.839 on the motion picture, so you know, basically climbing ascending 0:05:31.880 --> 0:05:35.880 the ladder to still photography, then the moving picture and 0:05:35.920 --> 0:05:38.120 talk about you know, how these changes came about, how 0:05:38.160 --> 0:05:41.320 these inventions came about, and how they changed our world. Yeah, 0:05:41.360 --> 0:05:44.320 so the camera obscura is not a camera in the 0:05:44.360 --> 0:05:48.919 sense you're thinking of. It doesn't actually constitute photography, meaning 0:05:48.960 --> 0:05:53.400 making a fixed record of a visual scene. A camera obscura. 0:05:53.440 --> 0:05:56.120 That's literally it's Latin and it means what dark room, 0:05:56.320 --> 0:05:59.520 dark chamber, dark chamber. Yeah, which is a wonderful name. 0:05:59.560 --> 0:06:02.000 It's one of the reasons that that at times doing 0:06:02.080 --> 0:06:05.479 research on camera obscura can be so difficult because it 0:06:05.520 --> 0:06:08.520 seems like camera obscura has been the name of so 0:06:08.600 --> 0:06:14.320 many different like literary journals, horror movies, movies, bands. It's 0:06:14.400 --> 0:06:17.960 just such a cool title. But yeah, it means dark chamber, 0:06:18.040 --> 0:06:20.240 because one of the key elements here is that that's 0:06:20.320 --> 0:06:22.719 necessary and would have been necessary in ancient times as well, 0:06:22.800 --> 0:06:24.839 is that you have to have a dark chamber to 0:06:24.960 --> 0:06:29.400 create a camera obscura. And the weird thing about camera 0:06:29.480 --> 0:06:32.479 obscure is this that they do services kind of bridge 0:06:32.560 --> 0:06:39.240 between like natural optics and photographic technology, and yet it 0:06:39.279 --> 0:06:42.919 feels magic in a way like even today as a 0:06:42.960 --> 0:06:45.400 modern user using it, like it feels magic in a 0:06:45.400 --> 0:06:48.440 way that photography no longer feels magic. It feels magical 0:06:48.520 --> 0:06:51.400 in a way that site no longer feels magical, even 0:06:51.400 --> 0:06:54.520 though when you break down what's exactly is happening biologically 0:06:54.600 --> 0:06:57.839 and and and and neurologically during side, I mean that's 0:06:57.839 --> 0:07:00.640 it's it's a pretty fantastic process as well. But yeah, 0:07:00.640 --> 0:07:04.359 the camera obscura still has this um this this this 0:07:04.440 --> 0:07:07.159 kind of eerie feel to it. Yes, the camera obscure. 0:07:07.279 --> 0:07:11.680 So the principle is extremely simple, but the implications are fascinating, 0:07:11.760 --> 0:07:15.160 and the way it's been processed throughout human history and 0:07:15.160 --> 0:07:18.160 in the history of optics leading up to photography is 0:07:18.200 --> 0:07:21.280 also fascinating. So the basic principle, as we say, is 0:07:21.360 --> 0:07:24.960 mechanically extremely simple. You have a darkened chamber. And this 0:07:25.000 --> 0:07:28.080 can be a room in a building or a tent, 0:07:28.320 --> 0:07:30.240 or this could even be a small box. It could 0:07:30.280 --> 0:07:32.240 even just be like a shoe box or a can 0:07:32.680 --> 0:07:35.240 something that is a chamber that doesn't allow light in 0:07:35.720 --> 0:07:39.600 except through a single small aperture on one side, right, 0:07:39.840 --> 0:07:43.000 and and we have to stress with this aperture. More 0:07:43.120 --> 0:07:48.040 recent camera obscuras, like for instance, my my wife um Bonnie, 0:07:48.040 --> 0:07:50.720 who is a photographer in the Atlanta area, she recently 0:07:51.040 --> 0:07:53.400 made a camera obscura as part of an open house 0:07:54.320 --> 0:07:58.679 for for the studio that she has, and they used 0:07:58.720 --> 0:08:02.280 a lens to service the aperture. But you don't need 0:08:02.320 --> 0:08:05.800 to use a lens. All you need is a hole. Yeah, now, 0:08:05.840 --> 0:08:08.400 the lens. The lens is an important development that comes 0:08:08.440 --> 0:08:10.600 to later in the history of the camera obscura. But yeah, 0:08:10.600 --> 0:08:12.760 all you need is a whole. And what you get 0:08:12.920 --> 0:08:15.040 when you have a darkened room with a small hole 0:08:15.120 --> 0:08:17.680 that's the right size and the right position away from 0:08:17.720 --> 0:08:21.760 the wall opposite it is that an inverted image from 0:08:21.840 --> 0:08:25.440 the world outside this this box or this room will 0:08:25.480 --> 0:08:29.720 be projected onto the wall of the darkened chamber. So, 0:08:29.840 --> 0:08:32.280 just as an example, if your camera obscura is a 0:08:32.360 --> 0:08:35.280 room with the right kind of small hole in the 0:08:35.280 --> 0:08:38.200 wall facing a view of the Pyramids of Giza, you 0:08:38.240 --> 0:08:41.800 will see an image of the pyramids upside down and 0:08:41.880 --> 0:08:45.719 inverted projected against the wall opposite the whole, as if 0:08:45.720 --> 0:08:49.480 there were an upside down film slide projector shining against 0:08:49.520 --> 0:08:52.480 a screen. Right. It's just it's it's maddening to kind 0:08:52.480 --> 0:08:55.000 of see one in action because it feels like there 0:08:55.000 --> 0:08:58.240 should be a projector there, there should be some man 0:08:58.240 --> 0:09:01.840 made mechanism that is make ing this possible, and and 0:09:01.920 --> 0:09:05.319 it's not. It's it's basically just a hole. Yeah. Now 0:09:05.400 --> 0:09:08.600 you might wonder, okay, wait a second, why does this happen? Like, 0:09:08.640 --> 0:09:11.439 why don't the windows in my house do that? Right? 0:09:11.520 --> 0:09:14.440 That my house is a closed chamber, I've got holes 0:09:14.480 --> 0:09:17.040 in the walls that light can pass through the windows. 0:09:17.360 --> 0:09:19.560 And so there are a few reasons the windows in 0:09:19.600 --> 0:09:21.640 your house probably don't work this way. Number one, your 0:09:21.640 --> 0:09:24.440 house is not dark enough. Number two, you've got too 0:09:24.440 --> 0:09:27.840 many sources of light probably that are you know, coming 0:09:27.840 --> 0:09:30.800 from different directions. And number three, normal windows are generally 0:09:30.840 --> 0:09:33.960 too wide, letting in light from too many different angles 0:09:34.559 --> 0:09:38.040 to actually cast an image with any resolution. So let's 0:09:38.040 --> 0:09:40.760 think about the reasons why a pinhole or a small 0:09:40.920 --> 0:09:44.320 lens projects an image of the outside world inverted on 0:09:44.360 --> 0:09:47.520 an inner wall, while a larger hole or lens does not. 0:09:48.520 --> 0:09:51.079 A few main principles here and number one, pretty much 0:09:51.120 --> 0:09:54.080 all the light in an outdoor scene is reflected sunlight, 0:09:54.160 --> 0:09:57.960 so it's the sunshines down. Light bounces off everything out there. 0:09:58.760 --> 0:10:02.640 Number two, when reflects off of an object, the wavelength 0:10:02.720 --> 0:10:05.280 is changed unless its color has changed, so you've got 0:10:05.320 --> 0:10:08.440 different colored rays of light beaming all over the place. 0:10:09.000 --> 0:10:11.960 Number three, light is reflected off surfaces at all angles, 0:10:12.000 --> 0:10:13.840 so it's going to go in all kinds of directions. 0:10:14.000 --> 0:10:17.320 But once it's reflected, and this is number four, it 0:10:17.440 --> 0:10:21.000 travels in a straight line. And because light travels in 0:10:21.000 --> 0:10:24.000 a straight line, and because the aperture in the in 0:10:24.000 --> 0:10:27.600 the camera obscurit is small rays. Striking the bottom of 0:10:27.640 --> 0:10:30.200 the projected image will come from the top of the 0:10:30.200 --> 0:10:33.600 original image, and raise striking the top of the projected 0:10:33.600 --> 0:10:36.240 image will come from the bottom of the original same 0:10:36.280 --> 0:10:39.400 thing goes left to right. You've got uh light rays 0:10:39.600 --> 0:10:42.040 entering in all directions through a sort of you can 0:10:42.040 --> 0:10:46.120 imagine a filtering cone that focuses the image and makes 0:10:46.160 --> 0:10:49.400 it sharp that then forms a cone of projection on 0:10:49.480 --> 0:10:51.440 the other side of the wall. I think the first 0:10:51.440 --> 0:10:55.240 place I saw a camera scirit was the Royal Museum, Greenwich. Oh, 0:10:55.240 --> 0:10:57.400 I haven't been there. Yeah, it's it's a great place 0:10:57.400 --> 0:10:59.880 to check one out because it also has like his 0:11:00.000 --> 0:11:03.840 storical context because there's there's been a camera obscura at 0:11:03.880 --> 0:11:06.719 Greenwich from like the late seventeenth century on through the 0:11:06.760 --> 0:11:09.480 mid nineteenth century, and the current one was a believe 0:11:09.520 --> 0:11:13.319 installed in n and it shows a close up moving 0:11:13.559 --> 0:11:17.559 panorama of Greenwich and the and the Thames, the National 0:11:17.600 --> 0:11:21.280 Maritime Museum and the Royal Naval College. So it's it's 0:11:21.280 --> 0:11:24.800 really cool. Yeah, anybody, any of our British listeners out there, 0:11:24.960 --> 0:11:28.360 or anyone who finds themselves visiting that area, it's a 0:11:28.360 --> 0:11:30.800 great place to check out the camera obscura in action. 0:11:30.920 --> 0:11:32.719 I mean, what does it look like. It's so it's 0:11:32.720 --> 0:11:35.720 projected on a wall, like a stone wall or a screen. Yeah. 0:11:36.000 --> 0:11:38.800 I mean this was over a decade ago when I 0:11:38.840 --> 0:11:40.320 when I saw it, but I remember it had kind 0:11:40.360 --> 0:11:42.559 of it has kind of a ghostly quality to it. 0:11:42.920 --> 0:11:45.800 That's one of the striking things about my experiences with 0:11:45.880 --> 0:11:50.000 camera obscuras is that in both cases there is this 0:11:50.000 --> 0:11:53.800 this ethereal nature to it, Like you wouldn't, at least 0:11:53.800 --> 0:11:56.080 the ones I've experienced, you wouldn't like walk into it 0:11:56.120 --> 0:11:59.000 and like smack into the wall thinking it's it's reality, 0:12:00.120 --> 0:12:02.760 but like there's a feeling of the allusion to it, 0:12:02.840 --> 0:12:06.160 and yet it yet has this magical property. Yeah, I 0:12:06.160 --> 0:12:08.560 know what you're talking about, and you can vary, you 0:12:08.559 --> 0:12:11.599 can sort of like tweak those magic feeling properties or 0:12:11.640 --> 0:12:15.120 the qualities of the projected image by changing things about 0:12:15.200 --> 0:12:17.840 the aperture that lets the light in. For example, a 0:12:17.920 --> 0:12:21.360 smaller aperture you shrink the whole, that will generally produce 0:12:21.360 --> 0:12:24.600 a sharper image on the projection with less blurring, but 0:12:24.679 --> 0:12:27.040 it will also be dimmer, of course, because less light 0:12:27.120 --> 0:12:29.960 is getting through the hole. A wider aperture, on the 0:12:29.960 --> 0:12:33.400 other hand, will produce a brighter but blurrier picture generally. 0:12:33.840 --> 0:12:36.520 And in fact, you can imagine just taking this principle 0:12:37.080 --> 0:12:39.439 uh to the extreme, because this is how if you 0:12:39.559 --> 0:12:42.840 just keep widening the aperture more and more, eventually the 0:12:42.880 --> 0:12:45.640 picture would get brighter and brighter and blurrier and blurrier. 0:12:45.880 --> 0:12:48.360 Until eventually what you have is simply a window. Again, 0:12:48.760 --> 0:12:52.760 you're just admitting white light with no definition in the image. Now, 0:12:52.800 --> 0:12:55.480 one other technological way to mess with this that you know, 0:12:55.559 --> 0:12:58.040 you mentioned that when Bonnie made one had a lens 0:12:58.120 --> 0:13:00.760 in it. The lens is a really wharton upgrade on 0:13:00.800 --> 0:13:03.680 the simple hole in the wall camera obscura. A lens 0:13:03.840 --> 0:13:07.080 is of course transparent and has a convex outer surface, 0:13:07.120 --> 0:13:09.480 and this allows you to get more of the best 0:13:09.600 --> 0:13:13.240 qualities of a smaller aperture combined with a larger aperture. 0:13:13.320 --> 0:13:17.520 The convex lens gathers more light from more angles because 0:13:17.520 --> 0:13:19.920 of the way it bends, so it literally admits more 0:13:20.000 --> 0:13:22.480 light and creates a brighter picture, while at the same 0:13:22.520 --> 0:13:25.280 time it focuses that light toward a point by the 0:13:25.320 --> 0:13:28.240 refraction that the lens does, allowing you to get a sharper, 0:13:28.320 --> 0:13:31.920 more focused, and brighter image. It's a pretty impressive trick, 0:13:32.000 --> 0:13:35.160 and there are a number of really cool illustrations from 0:13:35.240 --> 0:13:39.000 old texts illustrating this. So where you you'll see like 0:13:39.000 --> 0:13:41.800 a figure figure A, and then there's a you know, 0:13:41.800 --> 0:13:44.559 a second figure inside of the box, and that that 0:13:44.840 --> 0:13:48.200 figures upside down, and then you have the lines drawing. 0:13:48.559 --> 0:13:52.520 How the the the optical image is inverted. It's it's 0:13:52.520 --> 0:13:54.920 pretty cool. I mean focusing light like this through a 0:13:55.000 --> 0:13:57.960 lens that goes through an aperture and then projects inverted 0:13:58.040 --> 0:14:02.160 on a screen is actually similar to how our eyes work. 0:14:02.600 --> 0:14:05.400 You think about this like so the human eye, of course, 0:14:05.640 --> 0:14:08.200 light is gathered and refracted through a lens. You've got 0:14:08.240 --> 0:14:11.439 a lens in your eye, and then its focus projected 0:14:11.559 --> 0:14:14.679 onto a light sensitive membrane at the back of the eye, 0:14:14.720 --> 0:14:17.360 and this is called the retina. These are our retinas, 0:14:17.400 --> 0:14:20.480 and the light sensing cells in the retina then transmit 0:14:20.560 --> 0:14:23.040 the image, or maybe not the image, you could say 0:14:23.080 --> 0:14:25.600 the data from the image to the brain to be 0:14:25.680 --> 0:14:29.880 interpreted into the experience we call vision. And just like 0:14:29.920 --> 0:14:32.520 with the camera obscura, just like the projection on the 0:14:32.520 --> 0:14:35.320 wall at the back of the camera obscura, the images 0:14:35.400 --> 0:14:37.840 of the world that we see every day are projected 0:14:37.960 --> 0:14:42.400 onto our retinas in an inverted form, upside down and reverse. 0:14:42.520 --> 0:14:45.560 That's how they hit those light sensitive cells, and it's 0:14:45.640 --> 0:14:48.320 up to the brain to create the perception of the 0:14:48.400 --> 0:14:51.960 visual field that we interpret as right side up. Now, 0:14:51.960 --> 0:14:54.160 one thing I way I've often seen this I think 0:14:54.240 --> 0:14:58.400 perhaps mis explained is that this fact is sometimes communicated 0:14:58.440 --> 0:15:02.080 by saying that our brains quote flip or quote rotate 0:15:02.160 --> 0:15:05.320 the retinal image back to the format it was in. 0:15:05.640 --> 0:15:08.920 But that's not quite right because there's nothing for the 0:15:09.000 --> 0:15:12.040 brain to flip it onto. You know. You think about 0:15:12.120 --> 0:15:15.040 like the perception of the visual field. Uh, the image 0:15:15.080 --> 0:15:18.040 that you actually think you see in your brain is 0:15:18.040 --> 0:15:21.600 not a physical space mapping one for one from reality, 0:15:21.960 --> 0:15:25.320 but a sort of perceptual illusion created by the brain. 0:15:26.520 --> 0:15:28.920 A great example of this, if you've never tried it, 0:15:29.760 --> 0:15:33.240 you probably think you can see color in your peripheral vision, 0:15:33.400 --> 0:15:36.840 right you just assume you can see color everywhere, but 0:15:36.960 --> 0:15:39.120 you can. You can play a really fun game to 0:15:39.160 --> 0:15:43.320 break this illusion. Have somebody whole different colored flags right 0:15:43.360 --> 0:15:45.600 at the edge of your peripheral vision where you can 0:15:45.680 --> 0:15:48.120 just see motion and you think you can see color, 0:15:48.360 --> 0:15:50.360 and then try to say what color the flags are, 0:15:50.760 --> 0:15:53.720 you will probably fail. Another good thing to use our 0:15:54.200 --> 0:15:57.200 identical markers with different colored tops, like you have a 0:15:57.200 --> 0:15:58.960 bunch of sharpie's like we have in the office, where 0:15:59.040 --> 0:16:01.520 some of green tops, some of red tops all virtually 0:16:01.600 --> 0:16:04.240 the same looking. So get somebody to sneak up behind 0:16:04.320 --> 0:16:07.800 you with much of them and experiment with optics that way. 0:16:07.840 --> 0:16:11.040 I think I just noticed you sort of trying. Yeah, 0:16:11.080 --> 0:16:12.840 I have a green one in my hand, and I 0:16:12.840 --> 0:16:14.840 mean it's difficult to do to yourself because you, of 0:16:14.840 --> 0:16:16.720 course have so much of our vision is about like 0:16:16.760 --> 0:16:20.080 the memory and knowledge of the thing exactly. Yeah, but 0:16:20.160 --> 0:16:23.120 that's because like you're seeing with your brain as much 0:16:23.160 --> 0:16:25.320 as you're seeing with your eyes. Your eyes, actually you 0:16:25.360 --> 0:16:28.360 know you're you're not seeing color over here, even though 0:16:28.400 --> 0:16:31.000 you strongly have the perception that you're seeing color in 0:16:31.040 --> 0:16:34.400 your periphery. So your brain creates a sensation of an 0:16:34.440 --> 0:16:37.880 image simulating a kind of one to one relationship with 0:16:37.920 --> 0:16:40.360 the outside physical world that you can prove in a 0:16:40.440 --> 0:16:43.760 number of ways does not actually, uh you know, it 0:16:43.800 --> 0:16:46.120 does not actually capture that world in a one to 0:16:46.200 --> 0:16:49.800 one way. Another example is our complete unawareness moment to 0:16:49.880 --> 0:16:52.400 moment of the blind spot created in each eye by 0:16:52.440 --> 0:16:54.880 the optic nerve. Do you ever play that game, Oh, 0:16:54.920 --> 0:16:57.880 this is where the basically there's that that spot where 0:16:57.960 --> 0:17:01.360 you cannot see, but your vision kind of stitches everything together. Yeah, 0:17:01.360 --> 0:17:03.760 you don't notice that you have blind spots right in 0:17:03.800 --> 0:17:06.840 front of your face. Right. That reminds me of our 0:17:06.960 --> 0:17:09.720 chat with the author or Scott Baker on Stuff to 0:17:09.720 --> 0:17:12.040 Bluw your Mind, where you talked about having an eye condition, 0:17:12.640 --> 0:17:15.679 uh that he had corrected, but it it caused him 0:17:15.720 --> 0:17:18.200 to have an extra blind spot and so if he 0:17:18.240 --> 0:17:20.800 looked at, say his dog's face, he would see like 0:17:20.840 --> 0:17:24.040 a faceless dog. Yes, but that that's the fascinating thing. 0:17:24.080 --> 0:17:26.280 The way he described it was it wasn't like he 0:17:26.800 --> 0:17:30.680 saw a like black hole there where there was nothing. Instead, 0:17:30.960 --> 0:17:33.160 he just did not see in that area. And it's 0:17:33.240 --> 0:17:36.439 just no vision. And yet the brain stitches together a 0:17:36.480 --> 0:17:39.480 picture anyway, giving you the impression that you're seeing your 0:17:39.520 --> 0:17:42.320 surroundings in a one to one way, which we are not. Right. 0:17:42.359 --> 0:17:45.440 It's more it's less like like we are the observer 0:17:45.760 --> 0:17:48.560 and more like we're given a we're given a version 0:17:48.600 --> 0:17:50.119 of it. We're so kind of like the head of 0:17:50.119 --> 0:17:53.040 a big company or state and somebody like gives us 0:17:53.080 --> 0:17:56.159 a memo, uh like telling us what the situation is, 0:17:56.240 --> 0:17:58.399 and we we agree with it because it seems like 0:17:58.400 --> 0:18:01.359 it's all properly a symbol. Yeah, So I think the 0:18:01.400 --> 0:18:04.320 way the brain puts together the idea of what's right 0:18:04.359 --> 0:18:06.959 side up and upside down. Is cognitively that's going on 0:18:07.080 --> 0:18:10.240 in processing somewhere in the brain based on all kinds 0:18:10.280 --> 0:18:12.600 of sense data, visual data, but also I think, just 0:18:12.640 --> 0:18:15.760 like balance data and stuff like that, the retina senses. 0:18:15.840 --> 0:18:19.320 The brain perceives based on the senses, including this retinal data, 0:18:19.359 --> 0:18:22.600 but the perception created is not a photograph inverted from 0:18:22.640 --> 0:18:25.080 the retinas, but more like an interpretation based on it. 0:18:25.119 --> 0:18:28.800 But anyway, it is true that the projector screen of 0:18:28.880 --> 0:18:32.680 light sensitive cells that send information to your brain, that 0:18:32.840 --> 0:18:36.680 those retinas, they receive an image inverted from its orientation 0:18:36.720 --> 0:18:40.040 in physical space. So ironically, when we look at an 0:18:40.080 --> 0:18:43.320 image projected onto the back wall of a camera obscura 0:18:43.480 --> 0:18:47.480 upside down and reversed, it's then reflected and refracted through 0:18:47.560 --> 0:18:50.440 the lenses of our eyes projected on our retina's right 0:18:50.480 --> 0:18:54.240 side up again, and of course our brains, being doing 0:18:54.280 --> 0:18:58.000 what they do, they seamlessly correct or interpret this input, 0:18:58.119 --> 0:19:01.679 flipping it upside down again and option. Another interesting thing 0:19:01.680 --> 0:19:03.680 about the camera obscure in the history of how people 0:19:03.680 --> 0:19:06.040 have thought about what the eyes do is that a 0:19:06.160 --> 0:19:09.040 very common view among scholars throughout the ages is that 0:19:09.560 --> 0:19:13.760 light is not an external input on the eyes, but 0:19:13.960 --> 0:19:17.560 rather the many scholars throughout history believed that the eyes 0:19:17.680 --> 0:19:22.840 would beam out some kind of retrieving ray which grabs 0:19:22.920 --> 0:19:26.119 images from the world and pulls them back in. This is, 0:19:26.160 --> 0:19:29.320 of course extremely wrong. Eyes are input and that output. 0:19:29.480 --> 0:19:32.720 But it's funny how captivating that kind of a way 0:19:32.720 --> 0:19:35.800 of viewing the world can be. Yeah, it's easy just 0:19:35.840 --> 0:19:39.960 to sort of subconsciously think of it that way. Um, 0:19:40.080 --> 0:19:42.240 you know, think if your your eyes sort of yet 0:19:42.320 --> 0:19:45.000 reaching out and touching the world and reporting back like 0:19:45.040 --> 0:19:48.080 they're like like they're they're they're they're touching the side 0:19:48.080 --> 0:19:51.160 of an elephant or something and reporting back. And of course, 0:19:51.160 --> 0:19:53.480 as we mentioned on the show before, our our various 0:19:54.080 --> 0:19:56.879 romantic pop songs are always getting it wrong talking about 0:19:57.080 --> 0:20:01.320 my eyes touch you physically, that sort of thing where 0:20:01.320 --> 0:20:05.159 it's like, no, don't, don't touch eyeballs lovers of the Oh, 0:20:05.440 --> 0:20:08.240 Peter Gabriel is the worst offenders. Oh yeah, what was 0:20:08.280 --> 0:20:10.760 his line from he wants to touch the light the 0:20:10.760 --> 0:20:13.639 heat in your eyes. He's literally advocating the touching of 0:20:13.680 --> 0:20:18.040 eyeballs with you know, salty, greasy fingertips. Very bad. Yeah, 0:20:18.080 --> 0:20:22.400 there's no there's no reason for that. Uh, but but anyway, Okay, 0:20:22.440 --> 0:20:24.399 so the camera scare. We we know it was this 0:20:24.520 --> 0:20:27.080 important development in the history of optics, but it does 0:20:27.160 --> 0:20:31.199 not constitute photography because it does not fix the image 0:20:31.200 --> 0:20:33.920 it captures to be observed later. So so what did 0:20:33.960 --> 0:20:35.960 it do? I think we should take a break and 0:20:36.000 --> 0:20:38.640 then come back and look at possible in this sort 0:20:38.680 --> 0:20:42.399 of possible invention history of the camera obscure and what 0:20:42.520 --> 0:20:52.000 it did. Alright, we're back. So this is another one 0:20:52.040 --> 0:20:55.760 of those cases where when you look at the technology 0:20:55.840 --> 0:20:58.359 that is required for the simplest version of the of 0:20:58.720 --> 0:21:01.560 the invention the camera scare, in this case, you really 0:21:01.560 --> 0:21:05.080 don't need much. You need the ability to have to 0:21:05.280 --> 0:21:09.480 build or manipulate an enclose dark space, and you need 0:21:09.560 --> 0:21:12.760 whole technology. I mean. The funny thing is a camera 0:21:12.800 --> 0:21:15.000 obscura doesn't even have to be created by humans. They 0:21:15.000 --> 0:21:19.879 can exist totally naturally. Imagine a tree that's hollow in 0:21:19.880 --> 0:21:21.680 the middle and it's got a hole in the bark. 0:21:22.240 --> 0:21:25.959 Or imagine a cave that's got a the correctly sized 0:21:26.000 --> 0:21:29.600 hole in the wall that projects against an opposite wall. Yeah, 0:21:29.720 --> 0:21:32.879 so we have to imagine our our Gary Larsen's far side. 0:21:33.040 --> 0:21:38.280 Um prehistoric human encountering some some some form of camera 0:21:38.320 --> 0:21:41.640 obscura and reacting to it in in ancient times. Well, 0:21:41.680 --> 0:21:44.600 that's really interesting because we don't know who created the 0:21:44.600 --> 0:21:47.200 first camera obscure on purpose. We don't know who encountered 0:21:47.240 --> 0:21:50.480 the first camera obscura. Uh. We do have some early 0:21:50.600 --> 0:21:53.520 descriptions of how it works or how people thought it worked. 0:21:53.880 --> 0:21:57.320 But once uncertain and very intriguing possibility is what you're 0:21:57.320 --> 0:22:00.720 talking about. The prehistoric people's actually discuss heard the use 0:22:01.080 --> 0:22:03.640