1 00:00:00,120 --> 00:00:07,230 Welcome to this afternoon's colloquium. It's a great pleasure today to welcome Professor Tom Mccreesh to be our speaker. 2 00:00:07,830 --> 00:00:17,070 I first got to know Tom when he was in Cambridge, but his career subsequently has taken on roles in Sheffield and Leeds and now in Durham. 3 00:00:17,080 --> 00:00:24,120 He's a professor of physics there. He's also been to vice chancellors research and his area of speciality is all about the reality of fluids. 4 00:00:24,120 --> 00:00:29,680 But he's not talking about that today. He has many side interests, but one of them, far too much, 5 00:00:29,910 --> 00:00:37,620 has come about through his interaction with some people in Oxford because he also did principally some medieval historians. 6 00:00:37,620 --> 00:00:45,210 That's not who we normally collaborate with. It's just to suggest that some medieval historians have been working in Durham and together they've 7 00:00:45,480 --> 00:00:50,130 uncovered some rather interesting things that connects physics with a 13th century history. 8 00:00:50,550 --> 00:00:54,000 So I think it's going to be a very interesting book by colloquium. Thank you very much. 9 00:00:54,510 --> 00:00:57,420 Oh, thank you so much. It's great to be back in Oxford. 10 00:00:57,600 --> 00:01:01,589 And as you can see, this is going to be a talk which involves Oxford, an Oxford Durham collaboration. 11 00:01:01,590 --> 00:01:04,710 So for many reasons, it's it's very, very suitable. 12 00:01:05,440 --> 00:01:12,310 As you may know, the Oxford Durham is a picture of a now the medieval University of the North up there. 13 00:01:12,330 --> 00:01:17,520 It goes back many centuries. A couple of Durham colleges were actually funded from Oxford, sorry. 14 00:01:17,520 --> 00:01:27,389 All the way round of Oxford Colleges were funded from Durham when, when Durham was a parliamentary forbidden from funding a university itself. 15 00:01:27,390 --> 00:01:28,770 So we just helped you. 16 00:01:30,210 --> 00:01:37,710 The other link here is that we will meet a character I've become fascinated with, namely the 13th century polymath Robert Ross Teste, 17 00:01:37,980 --> 00:01:43,980 who's become a personal hero of mine, an English mind of extraordinary capacity. 18 00:01:44,160 --> 00:01:51,270 There ought to be far better known. He might well have been this university's first chancellor. 19 00:01:51,540 --> 00:01:56,850 But your records, to be frank, are are little ropey back in the 13th century. 20 00:01:56,970 --> 00:02:03,180 And I don't think we'll ever quite, quite know. I think I probably hurled enough insults from the Durham verse to Oxford. 21 00:02:03,360 --> 00:02:07,349 William Barford is looking at me askance so well. We'll press on so upset, he said. 22 00:02:07,350 --> 00:02:13,950 Giles Gospel. This is a very large collaboration. Other names will pop up is my colleague, historian, 23 00:02:14,130 --> 00:02:21,360 medieval historian how Smithson was a Dom she's experimental psychologist now in your department of Experimental Psychology, 24 00:02:21,360 --> 00:02:25,409 if of course, no longer in your building of experimental psychology here in Oxford. 25 00:02:25,410 --> 00:02:29,340 But she's currently on sabbatical with us in Durham. Sigg is Norwegian. 26 00:02:29,340 --> 00:02:32,969 He's a Latinised Richard is a cosmologist. Neil Lewis is a Georgetown. 27 00:02:32,970 --> 00:02:37,320 He's a he's a medieval philosopher. My constable is an English from Durham. 28 00:02:37,890 --> 00:02:42,650 Expert on middle or middle English to the Pantheon is a talking after it. 29 00:02:42,660 --> 00:02:49,080 Rome is probably the leading cross test physics scholar currently, and Ron Tan is another physicist at Durham. 30 00:02:49,080 --> 00:02:56,790 So you can see that this is a very interdisciplinary team and I hope to explain to you why that is the case. 31 00:02:57,150 --> 00:03:02,970 Many thanks to both our universities funding this from time to time and currently the Arts and Humanities Research Research Council. 32 00:03:03,120 --> 00:03:07,679 So let me just jump straight with no further ado into the business. 33 00:03:07,680 --> 00:03:15,390 And here is Manuscript and Annexe 12 three in Durham's medieval library. 34 00:03:15,570 --> 00:03:17,430 It's our growth test manuscript. 35 00:03:17,610 --> 00:03:27,150 And you can see straightaway why a physicist might have a little activation barrier before she or he gets very far with this material. 36 00:03:27,780 --> 00:03:29,549 This is our principal reference. 37 00:03:29,550 --> 00:03:37,650 It's a collection, of course, test dicta, although I have to say we don't some we don't possess any of his scientific corpus. 38 00:03:37,650 --> 00:03:40,440 They are mostly held in Oxford College libraries these days. 39 00:03:40,740 --> 00:03:49,620 The Cathedral Library catalogue at Durham says that we should possess a copy of cross tests scientific treatise. 40 00:03:49,620 --> 00:03:55,319 But someone checked it out in 1349 and doesn't seem to have checked it back in again. 41 00:03:55,320 --> 00:04:04,590 Never mind. But you see, the point is that medieval paleo graffiti or wine tasting for manuscripts ability to read this highly abbreviated medieval 42 00:04:04,590 --> 00:04:14,100 Latin to understand its its philosophical background is the gateway set of disciplines to getting anywhere with this material. 43 00:04:14,700 --> 00:04:22,529 So let's just jump in and say what does a medieval natural philosopher say when he's writing a document about light? 44 00:04:22,530 --> 00:04:27,840 So this is the first treatise that I read across the state UK on Light about 1224. 45 00:04:29,610 --> 00:04:34,290 Now I thought, actually, this is Oxford, so that should work fine. 46 00:04:34,530 --> 00:04:37,530 So I'll just leave you to translate that as we go. 47 00:04:40,020 --> 00:04:47,819 I, when I was moving from Leeds to I should say I was first found out about this extraordinary 48 00:04:47,820 --> 00:04:52,049 13th century mind through the history philosophy of science department at Leeds, 49 00:04:52,050 --> 00:04:59,220 for whom at that point there was a ghost scholar, Jim Ginter, who was more interested in his philosophy and theology than his his science. 50 00:04:59,220 --> 00:05:03,160 But I always. To read his side. So this was the document I read this summer. 51 00:05:03,310 --> 00:05:16,480 I went to Durham and the first principle form which which is called the form of karate, I declare to be light. 52 00:05:16,840 --> 00:05:27,880 What's going on here? For light diffuses in every direction from a point of light into a sphere, however large it might be, might be generated. 53 00:05:28,090 --> 00:05:38,829 Unless, of course, something gets in the way and causes a shadow. For true, cooperative and extension of materials into three dimensions. 54 00:05:38,830 --> 00:05:41,920 Follow. Now. Okay. This is rather interesting. 55 00:05:42,550 --> 00:05:48,490 I expected when I first came across this guy, something rather mystical, rather theological. 56 00:05:49,780 --> 00:05:56,080 What I did not expect was a discussion of what we now call material stability. 57 00:05:56,980 --> 00:06:05,290 This is an essay, an extended essay in the mid the early 13th century, written by Christian natural philosopher, 58 00:06:05,470 --> 00:06:12,910 pointing out the classical atomism does not explain this, the three dimensional extension and solidity of matter. 59 00:06:14,590 --> 00:06:18,730 Well, this is a really interesting observation, because the point is it doesn't. 60 00:06:19,130 --> 00:06:25,370 And because this is saying that the point is that classical atoms are atoms, they are that which cannot be divided. 61 00:06:25,390 --> 00:06:29,950 They are point like a points, Michael, which of course, has by definition no extension. 62 00:06:30,730 --> 00:06:35,980 And what you're saying is, however large, a number of point like objects I have, I still have no extension. 63 00:06:35,980 --> 00:06:42,610 I still have zero volume because zero multiplied by however a larger number I choose be that number finite still gives me no value. 64 00:06:43,390 --> 00:06:47,890 Now, I'm really enjoying myself by now because of course we know classical is indeed, 65 00:06:48,190 --> 00:06:52,990 it doesn't explain this unless because I mean you can always declared your atoms if a billion balls but it 66 00:06:53,000 --> 00:06:57,820 hasn't got you anywhere because you you require stuff with extension and you don't know what that is yet. 67 00:06:57,850 --> 00:07:00,970 It's just formed. You have recursion, which is something he points out. 68 00:07:01,420 --> 00:07:04,480 And so he set himself a problem. 69 00:07:04,570 --> 00:07:07,629 And it's a it's a seriously scientific problem. 70 00:07:07,630 --> 00:07:14,700 One of the delights of science I know about you, I'm often finding like pointing this out in the yeah. 71 00:07:14,800 --> 00:07:19,360 Whenever I have a cultural, half halfway cultural discussion, I try and sell science with, 72 00:07:19,960 --> 00:07:24,250 with this that science differentiates between the familiar and the understood. 73 00:07:25,450 --> 00:07:32,560 Yeah. I mean, just because we're familiar with the fact we sit on our chairs, we don't fall through does not mean we understand them fall through. 74 00:07:32,590 --> 00:07:42,819 Here is two galaxies in collision, and a classical view of matter, as you know, is still more or less classical. 75 00:07:42,820 --> 00:07:46,240 It's a cloud of points, a mostly empty space, two galaxies. 76 00:07:46,240 --> 00:07:50,500 When they collide, they look like clouds. You know, when you jump out of an aeroplane onto a cloud, you expect you're going to. 77 00:07:50,500 --> 00:07:55,270 But it looks as if you can bounce up and down the cotton wool, but you can't because it's mostly empty space. 78 00:07:55,420 --> 00:08:02,140 Galaxies pass straight through each other. Processes say the same thing would have would be the case with three dimensional matter. 79 00:08:02,320 --> 00:08:05,650 So where does this property of stability and extension come from? 80 00:08:06,340 --> 00:08:11,860 Now, you know, this is a problem which is not really solved until the advent of quantum mechanics. 81 00:08:11,860 --> 00:08:13,770 Goodness sake. Some of you work on this stuff, right? 82 00:08:15,070 --> 00:08:20,410 So what he says is there is a property that is a phenomenon I know that has this property of filling space. 83 00:08:20,410 --> 00:08:24,309 It is light in that first sentence is encapsulated. 84 00:08:24,310 --> 00:08:31,719 This is later informed by my Arabist colleagues. We have an important Arabist on the project, you know, just prior to the 13th centuries, 85 00:08:31,720 --> 00:08:36,070 this extraordinary century of the translation movement, when thanks to the Muslim tradition, 86 00:08:36,070 --> 00:08:38,830 Islamic tradition of North Africa and Spain, 87 00:08:38,830 --> 00:08:46,600 particularly Aristotle was being reintroduced in Arabic and then Latin translation from the Greek into Northern Europe. 88 00:08:46,600 --> 00:08:53,910 And that's really what got all natural philosophy going again. Avicenna, who pointed out the need for this sort of first form, 89 00:08:54,400 --> 00:09:01,000 not a need something like first form to give you an extension, but just as is the first to say, I think it's light. 90 00:09:01,840 --> 00:09:07,480 So for him, he makes this hypothesis that not a sort of amalgam of atoms and light, 91 00:09:07,660 --> 00:09:11,620 and that infinitely multiplying light provides this thing called stability. 92 00:09:12,160 --> 00:09:17,380 Or even says here, if it's not light, it could be something that has the same properties of light. 93 00:09:18,310 --> 00:09:21,880 So this one really falling off my chair. Okay, what else does he do? 94 00:09:22,060 --> 00:09:26,020 He then starts to mathematics, his his physics. 95 00:09:26,590 --> 00:09:32,980 He puts this argument about infinities and infinite into into a finite form. 96 00:09:33,100 --> 00:09:37,629 He starts saying, well, actually the there are greater and lesser infinities. 97 00:09:37,630 --> 00:09:45,310 Now, he's not being Cantor here. He's not, of course, identifying a proper classified hierarchy of infinities. 98 00:09:45,520 --> 00:09:52,270 What he's saying is, I know I can't get extension if I multiply these infinitesimal atoms by a finite number, 99 00:09:52,450 --> 00:09:59,440 but suppose I could multiply by them infinite number. Then the mathematical description of my physics would be. 100 00:09:59,680 --> 00:10:03,220 An infinite divide by inferential input, multiplied by infinitesimal. 101 00:10:03,490 --> 00:10:08,500 And I think I can explain not only finite volumes, 102 00:10:08,500 --> 00:10:15,160 but all possible finite numbers of volumes by by comparing by taking the ratio of different infinities. 103 00:10:15,790 --> 00:10:19,210 So we discuss is the ratio of the natural numbers to the even numbers. 104 00:10:19,450 --> 00:10:20,859 And of course, you know, 105 00:10:20,860 --> 00:10:29,170 he's you can feel him groping at limits here and that proper analysis but not getting at it but you know goodness, this is 1224. 106 00:10:29,650 --> 00:10:34,360 He thinks this is greater than one. Of course, we can easily imagine that by changing limits, it could be less than one. 107 00:10:34,360 --> 00:10:36,270 But you feel you know what he's getting at. 108 00:10:36,520 --> 00:10:42,700 He actually does states that the powers of some of the powers are two divided by the halves, must still be two, must be two. 109 00:10:42,700 --> 00:10:46,569 Because each term is twice the the the the term it can be compared to. 110 00:10:46,570 --> 00:10:54,070 So that there are some interesting things going on here. But the point is that he's he's also deciding that physics needs to be mathematical physics. 111 00:10:55,750 --> 00:10:58,000 And as you said, this is the translation. 112 00:10:58,000 --> 00:11:02,709 Like you said, whatever sustained extension matches either like or participates in some part in the properties of rights, 113 00:11:02,710 --> 00:11:12,880 I thought I would gratuitously, gratuitously put up pictures of the Hodgkin wave function to point out just what we are not saying. 114 00:11:14,230 --> 00:11:21,520 What is, of course, awfully easy to do at this point is and you know, if I were writing an article for New Scientist or something, 115 00:11:21,520 --> 00:11:25,750 it would be so easy to say, oh, you know, a quantum mechanism in eight centuries before his time. 116 00:11:26,770 --> 00:11:35,650 No, of course not. Of course not. This is a medieval thinker with a medieval mind thinking of his own, his own period. 117 00:11:35,830 --> 00:11:44,229 However, what is extraordinary is that whenever we've added a new scientist to our team and we started to engage 118 00:11:44,230 --> 00:11:52,180 with this and his contemporaries writing We We are scientists don't find themselves in alien company. 119 00:11:52,750 --> 00:11:56,820 It's strange, it's very different. But there is an intellectual fellow feeling. 120 00:11:56,850 --> 00:12:00,970 I hope I can. I've been able to persuade you why that is. But first. 121 00:12:01,360 --> 00:12:10,659 So let me see. So what has happened? When I got to Durham, I was kind of to point out it was in order to have the provost chancellor for research. 122 00:12:10,660 --> 00:12:16,560 So I was spending my first few weeks knocking around the university, different faculties, different departments asking, 123 00:12:16,570 --> 00:12:21,879 you know, what's good, what's going on, what little sign on can I do to help people join up? 124 00:12:21,880 --> 00:12:32,770 And, and I found that the Institute for Medieval Studies being of course yeah thoroughly humanities and doing things things 125 00:12:32,770 --> 00:12:41,440 properly had this charming Tuesday evening seminar with a glass of wine at 5:00 where they talked about medieval authors. 126 00:12:41,440 --> 00:12:46,030 And I said, looking at, Would you like me to come? I love to find out what you're doing and would you like me to come? 127 00:12:46,030 --> 00:12:51,180 We just talk very naively about what a contemporary scientist how with with, 128 00:12:51,190 --> 00:12:59,440 without more than a smattering of cognisance of the history of the medieval history of science, how he reacts to reading some of this stuff. 129 00:12:59,440 --> 00:13:05,080 So I've told them what I've just told you, and we had a conversation afterwards. 130 00:13:05,890 --> 00:13:09,610 Is it worth is it worth taking this methodology a little further? 131 00:13:09,790 --> 00:13:15,129 Of getting humanities scholars and scientists together, reading these these texts? 132 00:13:15,130 --> 00:13:21,190 And does this add anything or is it does it just risk anachronistically modernising these people? 133 00:13:21,910 --> 00:13:23,680 And the answer was no. We'd like to take this further. 134 00:13:24,070 --> 00:13:32,050 And the reason we took this further is because you have asked us questions about this text that we've not asked ourselves, 135 00:13:32,410 --> 00:13:36,309 and we don't think they're silly questions. They're quite interesting questions. 136 00:13:36,310 --> 00:13:41,910 They might we might phrase them in different ways, but let's that's set up. 137 00:13:41,920 --> 00:13:49,960 So the Old Universe Project was born and it now consists of historians, panellists, scientists, all sorts. 138 00:13:50,830 --> 00:14:00,700 We are producing new translation editions of the texts. So what we hoped is that by by working together collaboratively on these documents, 139 00:14:00,910 --> 00:14:07,270 we would be able to identify more of the intellectual contribution they were making. 140 00:14:07,480 --> 00:14:14,230 A crude I would say, you know, the way I put it is if you're good enough at Latin to translate this stuff and read it, 141 00:14:14,350 --> 00:14:16,870 you probably gave up science when you about 13 years old. 142 00:14:17,230 --> 00:14:21,790 And so when it gets serious, the mathematical and physical, you know, you just you sort of miss it. 143 00:14:22,360 --> 00:14:26,380 And that's what the humanities scholars kind enough, enough to say as well. 144 00:14:26,650 --> 00:14:34,420 So we've produced these new editions and then what we've called functional analysis of the texts through modern eyes, not modernising the writer, 145 00:14:34,720 --> 00:14:44,350 but using the inheritors of the subsequent centuries to to re-evaluate and analyse what step it was logically and mathematically he was 146 00:14:44,350 --> 00:14:55,150 taking a we've also had fun inventing and this is a radical in this very project and actually getting medieval Latin artists and physicists, 147 00:14:55,210 --> 00:14:59,410 psychologists into a room talking with each other. It doesn't happen easily, just like. 148 00:14:59,490 --> 00:15:04,590 That and this Hannah Smithson who's here notes I said before, puts it When we first got together around the table, 149 00:15:04,890 --> 00:15:09,840 all the humanities scholars sat on one side of the table and all the scientists sat down the other side of the table. 150 00:15:10,500 --> 00:15:12,140 And it was all a little bit delicate. 151 00:15:12,180 --> 00:15:18,930 But as we got to know each other and have meals with each other and go on conferences together and so on, it got rather easier. 152 00:15:19,680 --> 00:15:22,950 And we do have a publication series actually. This is now changed. 153 00:15:22,950 --> 00:15:27,660 It's not the Pontifical Institute, it's Oxford University Press are now publishing. 154 00:15:27,990 --> 00:15:35,760 We are pushing with them a series of of commentaries and reappraising appraisals of this extraordinary polymath science. 155 00:15:35,760 --> 00:15:42,270 But there's a little bit more to that. This is what we didn't expect, and this has been the unexpected delight. 156 00:15:42,540 --> 00:15:47,700 Our great hope was that we could produce rather finer editions countries. 157 00:15:48,540 --> 00:15:55,320 What we did not expect was that at some point in the reading of every one of these 13th century treaties, 158 00:15:55,830 --> 00:15:59,520 one of the scientists will say, Well, that's an interesting question. 159 00:16:00,120 --> 00:16:05,640 It's a strange hypothesis. Does anyone ever revisit that? Did they want to do that calculation or this experiment? 160 00:16:06,180 --> 00:16:13,770 And because science is so redefined and rich, some of these questions have not been followed up. 161 00:16:14,250 --> 00:16:17,430 So as well as the humanity's series of papers, 162 00:16:17,430 --> 00:16:24,870 we've also managed to to spin out some papers that have been published in journals like the Journal of the Optical Society of America, 163 00:16:25,020 --> 00:16:32,309 Proceedings of the Royal Society, Nature and Nature Physics. You may have heard of some of these journals of science, which is contemporary science, 164 00:16:32,310 --> 00:16:38,010 which has been stimulated methodologically, all substantially by this medieval encounter. 165 00:16:38,010 --> 00:16:44,010 So that's been a real delight. So here's one the actual court space from the 13th century, we'll be visiting that before the end, 166 00:16:44,010 --> 00:16:50,850 if we're lucky and precocious, makes extraordinary insight into rainbows. 167 00:16:50,850 --> 00:16:58,670 The History of the Rainbow. Yeah, I think you could probably write the history of science around the Rainbow alone, actually. 168 00:16:59,310 --> 00:17:02,430 Michael Brooks, science writer, has taken this project, his fall in love. 169 00:17:02,430 --> 00:17:10,649 With this, he writes for New Scientist. He's had a number of articles from him and others, and there's now lots of YouTube clips and things. 170 00:17:10,650 --> 00:17:19,320 So let's just go briefly into cross test and then we'll look at some of the some of the science that he is he became after his period writing science, 171 00:17:19,320 --> 00:17:26,370 he became a bishop of Lincoln. And as you know, the 13th century, the Diocese of Lincoln was huge. 172 00:17:26,370 --> 00:17:31,589 Oxford was in it. Some of you might might know this, but one of very humble origins. 173 00:17:31,590 --> 00:17:35,610 So as typical for the time, I don't really know quite when he was born somewhere in East Anglia. 174 00:17:36,480 --> 00:17:44,400 We know that by the end of the 12th century, he was a deacon for William de Vere, bishop of Hereford. 175 00:17:44,400 --> 00:17:47,760 Hereford, a very important centre of scholarly learning. 176 00:17:47,970 --> 00:17:49,530 Then we really didn't know. 177 00:17:49,590 --> 00:17:58,710 We know he was Oxford and the scholarly community are divided to the point of being at loggerheads about whether he was ever in Paris or not, 178 00:17:59,700 --> 00:18:03,989 which is southern. So some of you will have heard that that name very now, now deceased. 179 00:18:03,990 --> 00:18:08,910 But an established English medievalist has a personal crusade to make cross test 180 00:18:09,090 --> 00:18:13,080 the great medieval English philosopher and wouldn't have it that he was in Paris. 181 00:18:13,380 --> 00:18:18,450 I think, frankly, he probably was. But it's some of our textual analysis helping to solve that problem. 182 00:18:18,450 --> 00:18:25,770 He was actually obviously here he was tutor to the brand new early Franciscan movement, and that's when it got intellectually interesting. 183 00:18:26,370 --> 00:18:36,090 It was during the 1220s that he was writing most of his science and as I said, 1235 Bishop Lincoln He takes several missions to the Pope. 184 00:18:37,170 --> 00:18:43,920 Leo And not quite sure why Leo has become plural, but so he's often recruited as of early reformer. 185 00:18:44,130 --> 00:18:50,850 He stands up for good pastoral behaviour in the church and, and, and, and good editions of Scripture. 186 00:18:51,060 --> 00:18:58,080 So you, you read, you go back to the, the Hebrew and the Greek and he dies in 1253. 187 00:18:58,080 --> 00:19:02,040 So he was extraordinary scholar. And here there's the there are two pictures of him. 188 00:19:02,190 --> 00:19:04,470 No idea whether they're like this or not. This is this is the other one. 189 00:19:04,830 --> 00:19:08,610 He he writes about the whole curriculum, the medieval curriculum, the liberal arts. 190 00:19:08,820 --> 00:19:12,000 He writes about many science. You write you, of course, write theology. 191 00:19:12,900 --> 00:19:18,690 And it's not the same thing. He's perfect. You can tell he's he knows when he's doing science and he knows when he's doing theology. 192 00:19:18,690 --> 00:19:23,970 It's different. As I said before, he's interested in going back to original languages to improve the quality of a text. 193 00:19:24,210 --> 00:19:26,040 He's passionate for proper pastoral care. 194 00:19:26,340 --> 00:19:32,489 He writes for agriculture, he's interested in farming practices, and he spent some time as a bishop and a politician. 195 00:19:32,490 --> 00:19:42,150 So very rich, medieval career. What's going on at the time contextually to say in this is very important to understand and I don't know about you. 196 00:19:42,180 --> 00:19:50,370 One of the drivers for me in this project is I've never really quite bought the sort of coffee table history of science story, 197 00:19:50,370 --> 00:19:57,089 which told me when I was a teenager that, you know, signed the origin of proper science was around 1600. 198 00:19:57,090 --> 00:20:00,360 It was in the Enlightenment. And that nothing before that. Really counted. It was. 199 00:20:00,690 --> 00:20:04,139 It was, you know, mysticism and alchemy and still magic and stuff. 200 00:20:04,140 --> 00:20:09,390 And and because I'm a kind of gradualist at heart, I don't really think everything comes from nothing. 201 00:20:09,810 --> 00:20:13,740 Really believe that. And, well, you shouldn't believe it because it's not true. 202 00:20:14,160 --> 00:20:18,270 And there's all sorts of mathematical fuss and physical and scientific development. 203 00:20:19,290 --> 00:20:26,669 To me, this is what's going on for me. The blue touch paper for the scientific revolution was lit in the 12th century when I said 204 00:20:26,670 --> 00:20:30,990 most of Aristotle and Plato was rediscovered by the scholarly communities of North Europe. 205 00:20:31,230 --> 00:20:35,580 Thank you. Thanks to the Arab transmission and and people started reading it. 206 00:20:35,580 --> 00:20:44,040 So people like other easy Arabic named Ibn Rushd of Cordoba, just as Aristotle at the time is, tends to be called as the philosopher. 207 00:20:44,040 --> 00:20:48,300 If you saw the was the philosopher, it's almost always means Aristotle in 13th century, 208 00:20:48,480 --> 00:20:55,650 if you ever saw the words of the commentator fundament averroes who commentated and developed Aristotle science 209 00:20:56,220 --> 00:21:03,210 going on all over the the Middle East and Constantinople of course Sicily but particularly said before Spain, 210 00:21:03,330 --> 00:21:11,159 talking about Toledo and Cordoba, great performance of intellectual interdisciplinary awakening in the 12th and then the 13th century. 211 00:21:11,160 --> 00:21:17,129 So girls just inherits all this ancient science, this then the 12th intellectual revival, 212 00:21:17,130 --> 00:21:21,690 this reconquest of Aristotle, this a copy of Aristotle's Opera Logic. 213 00:21:21,810 --> 00:21:23,400 I think it's in a library in Oxford, actually, 214 00:21:23,400 --> 00:21:33,420 that one that and he develops a rather nuanced natural science and scientific method get in talking in his commentary and as to Aristotle's 215 00:21:33,420 --> 00:21:43,170 posterior analytics about how we induce knowledge of the universe in an opposite way from how we did use mathematics from its axioms. 216 00:21:43,350 --> 00:21:48,900 It's a very advanced and subtle philosophy of a scientific methodology. 217 00:21:49,050 --> 00:21:53,160 But of course he is in a Christian theological world and he knows. 218 00:21:53,170 --> 00:21:56,969 So these are the the the the era as well. 219 00:21:56,970 --> 00:22:05,400 When once we when he's asking questions about science, what might we know about the way the material universe works? 220 00:22:05,470 --> 00:22:06,270 We don't know. 221 00:22:06,270 --> 00:22:14,909 Now, this is where the intellectual connection for theology comes from, because it's clear that it's because of the audience of God's creation. 222 00:22:14,910 --> 00:22:17,400 That's where the universe or universe label comes from. 223 00:22:17,580 --> 00:22:27,090 That one can therefore logically hope to do something about only entangling creation with reason and rationality and and all of us. 224 00:22:27,450 --> 00:22:33,090 And if we're not experimenting, we are most certainly observing. 225 00:22:33,300 --> 00:22:34,800 And that's a rather subtle issue. 226 00:22:35,550 --> 00:22:46,980 Some of you will know that there's an historian of science who first wrote about Columbia, S.C. Crombie wrote about ghost science in the 1560s, 227 00:22:47,310 --> 00:22:55,740 had a very strong opinion that it was just to establish the beginnings of experimental science tradition in in England. 228 00:22:55,760 --> 00:23:00,170 That's probably overthinking the pudding. But you'll see he gets pretty close to it. 229 00:23:00,480 --> 00:23:03,810 Observation, however, is certainly important. 230 00:23:03,990 --> 00:23:06,420 And for those of you interested in the background philosophy, 231 00:23:06,420 --> 00:23:14,579 there's a theological transition going on here from Augustine to acquires mean by that from from a theology that some based on divine light. 232 00:23:14,580 --> 00:23:20,430 You know we are inspired to know things from Aquinas who would say no we by our own hard work, 233 00:23:20,430 --> 00:23:28,180 we can do science and we can work things out that we didn't know before. So from a doctrine of, well, we're just fallen beings, 234 00:23:28,180 --> 00:23:33,569 so we can't hope to do anything from a sense of actually we might recover a sort 235 00:23:33,570 --> 00:23:38,310 of knowledge of creation that a divine creator might contain this to to have. 236 00:23:38,810 --> 00:23:46,110 We're going on. Of course, Aristotle was being adopted into the philosophical question that the physics of of of of the time. 237 00:23:46,290 --> 00:23:49,710 And of course that creates some very delicate questions. 238 00:23:49,980 --> 00:23:53,820 You know, how far does a Christian philosopher take on arrest and arrest? 239 00:23:53,820 --> 00:23:59,550 Aristotle, a pagans, is thinking, where do you go? Where do you stop when you see some interesting points in the science there? 240 00:24:00,330 --> 00:24:06,330 And he's clearly motivated by his biblical theology to look at science as well. 241 00:24:06,600 --> 00:24:12,959 And we've got to now get to a European transmission. So this is not a sort of static, intellectual time. 242 00:24:12,960 --> 00:24:16,410 It's a fervent of you. Thoughts? What does he write about in science? 243 00:24:17,220 --> 00:24:23,670 He writes about sounds. His early, early, early text is about how sound is made and how we perceive it. 244 00:24:24,210 --> 00:24:31,380 And he writes about the heavenly spheres. It's a sort of undergraduate text of the Aristotelian heavens and how to calculate eclipses. 245 00:24:31,380 --> 00:24:38,730 And someone talks about comets and how elements work in the universe, how this sky moves on light colour. 246 00:24:39,060 --> 00:24:45,420 He comments out in Aristotle's physics. He writes a sort of spatial geometry of the nature of lines and place, 247 00:24:45,630 --> 00:24:52,230 and he finishes with a treatise on the rainbow before he he himself, which will visit bye bye bye by the end. 248 00:24:53,130 --> 00:24:56,670 So I think I'll just skip over the sources actually, and we'll. 249 00:25:00,700 --> 00:25:04,180 Just wanted you to just look at this little bit because he's he's. 250 00:25:04,960 --> 00:25:09,550 There are echoes that the sort of reflection that Einstein had on the almost 251 00:25:09,550 --> 00:25:14,320 miraculous way we can do science is he has these these these thoughts as well. 252 00:25:14,320 --> 00:25:22,180 And I rather loved this description of of what he's trying to do. 253 00:25:22,330 --> 00:25:28,840 He's trying to use sense perception in the world to re create an imaginative 254 00:25:28,840 --> 00:25:35,889 grasp of the inner structure of matter of the sky and of the incorruptible, 255 00:25:35,890 --> 00:25:42,340 universal fast essences. The first causes effects. Okay, I said before. 256 00:25:42,340 --> 00:25:43,389 So we've got authorities. 257 00:25:43,390 --> 00:25:54,310 We've got these ideas to explain nature, rationality and text on the rainbow and the introduction of mathematics into into science. 258 00:25:54,310 --> 00:26:04,810 So there's a lot going on. He does something extraordinary with the treatise on on on Light. 259 00:26:04,900 --> 00:26:08,380 So we'll go back to that. 260 00:26:08,530 --> 00:26:09,730 It's the next thing we do. 261 00:26:10,570 --> 00:26:19,240 He he's established this I explained that his observation that light has the property of space can might explain the solidity of matter. 262 00:26:20,440 --> 00:26:24,960 He then does this a second extraordinary thing he says, well, actually does it. 263 00:26:25,420 --> 00:26:32,680 If this explains matter on the scales around us, might it also explain the largest objects we can conceive of? 264 00:26:32,710 --> 00:26:39,120 They move the universe as a whole. This is another one that I think he's almost a medieval version of what Newton 265 00:26:39,120 --> 00:26:42,719 does when he looks at the app of Apple Fall or imagines the Apple fall and says, 266 00:26:42,720 --> 00:26:48,780 I wonder if there's a connection between that force by that tendency and the orbit of the moon. 267 00:26:49,200 --> 00:26:56,460 So I was just saying, look, we've got a theory of the activity of light in ordinary matter. 268 00:26:57,030 --> 00:27:00,510 Might that account for the structure of the cosmos as we see it? 269 00:27:02,100 --> 00:27:06,750 And he come, he says he says, I think it might, because we know, of course, what is the cosmos he's thinking about? 270 00:27:06,960 --> 00:27:10,790 He's thinking of the Aristotelian cosmos. The geocentric cosmos, of course. 271 00:27:11,670 --> 00:27:14,020 You know, we can't blame him for that. He didn't have a telescope. 272 00:27:14,020 --> 00:27:20,130 But without a telescope, there is really insufficient evidence to establish anything but the geocentric theory and. 273 00:27:22,950 --> 00:27:29,910 So this is the universe that he wants to account for. Why does he think he needs to account for us at all? 274 00:27:30,210 --> 00:27:38,970 After all, for Aristotle, the question of how the universe got there doesn't arise because there can be no first, cause there's no first. 275 00:27:39,060 --> 00:27:41,340 Aristotle was the first city state cosmologist. 276 00:27:42,720 --> 00:27:49,530 But GROSS says although he embraces Aristotle, science in almost its entirety, says that actually because Aristotle, 277 00:27:49,530 --> 00:27:55,090 because he's a pagan, you know, he doesn't know everything as he thinks the universe always was. 278 00:27:55,110 --> 00:28:00,720 Of course, within the Christian metaphysics there is a creative moment, so one has to account for that. 279 00:28:02,100 --> 00:28:08,730 But what he does not do, and I think there are some people in churches today who would who would do well to listen to him. 280 00:28:08,880 --> 00:28:12,550 He doesn't say answers in Genesis. He doesn't. Of course he doesn't. 281 00:28:12,570 --> 00:28:19,350 No one has ever for the centuries taken taken the first chapter of Genesis as being anything other than metaphorical, these great, great thinkers. 282 00:28:19,380 --> 00:28:22,590 If it was metaphorical, he does the same thing. But he does. 283 00:28:22,590 --> 00:28:28,390 No, it talks about a creative moment. So he says no. What we need to do is to take the science we've inherited from Aristotle. 284 00:28:28,410 --> 00:28:36,959 With Aristotle, but against him. You need to account for the the cosmology that we see is fascinating. 285 00:28:36,960 --> 00:28:42,870 What he's saying is the structures we see in the sky when we look into the night sky are 286 00:28:43,020 --> 00:28:51,330 patterns and consequences of the dynamic moments of the early stages of the universe. 287 00:28:51,640 --> 00:28:56,600 So remarkable insight, because that's more or less what cosmologists do today, right? 288 00:28:57,060 --> 00:28:59,460 That's the microwave background, the pattern of the early movements. 289 00:28:59,790 --> 00:29:05,130 And he uses this light idea to do it, you know, light at the beginning of time, extended matter, which you could not believe, 290 00:29:05,340 --> 00:29:14,470 drawing out along with itself into a mass the size of the world machine, the universe itself, he says, who's a kind of medieval big. 291 00:29:15,630 --> 00:29:22,700 And it has extraordinary consequences. 292 00:29:22,860 --> 00:29:26,729 He has a density feel. 293 00:29:26,730 --> 00:29:32,730 This is where this is where the scientists sort of start resonating with this text, because he describes this expanding sphere. 294 00:29:33,220 --> 00:29:36,810 And he says this will be more dense in the middle than the outside. 295 00:29:37,950 --> 00:29:44,190 And he then starts and starts imagining simple axioms, 296 00:29:44,520 --> 00:29:53,640 a set of simple axioms that can that would would result in the universe of nested celestial spheres that he thinks he observes. 297 00:29:54,570 --> 00:29:59,850 So if this expansion is great, as you probably know, the idea was that these were perfected matter out of the orbit of the moon. 298 00:29:59,850 --> 00:30:05,370 Everything was perfect. He is, he says, look, suppose because nature never abhors a vacuum. 299 00:30:06,210 --> 00:30:09,360 If I'm never going to get to a vacuum, there must be a minimum density. 300 00:30:11,190 --> 00:30:18,180 Look at that minimum density. I can't verify further. Therefore, there must be a minimum density which the universe somehow crystallises and freezes. 301 00:30:18,810 --> 00:30:22,830 Okay. Point. So far it's quite intricate. 302 00:30:23,310 --> 00:30:26,549 So this expanding sphere has its lowest density at the outside. 303 00:30:26,550 --> 00:30:30,330 So it's at the outside points where this minimum crystallisation density must be reached. 304 00:30:30,630 --> 00:30:36,930 And when it's reached, of course, the expansion stops and that's the fun that surfaces this thing ferment is purified matter. 305 00:30:36,930 --> 00:30:46,590 Pure matter also radiates. So we now have an inward light pressure, if you like, that then starts exciting matter from the outside in. 306 00:30:47,410 --> 00:30:56,370 If we have a sort of luminous centric cosmology, uh, that, that the light starts radiating from the outward spheres inwards, 307 00:30:57,000 --> 00:31:02,310 and there's this excessive compression and the series of moments at which, 308 00:31:02,850 --> 00:31:08,250 which this critical density is, is retained actually is a series of multiples of the integers. 309 00:31:08,520 --> 00:31:13,350 And that is his theory for how the forces were formed. 310 00:31:13,660 --> 00:31:16,800 And actually, there's even something rather more remarkable than that. 311 00:31:17,880 --> 00:31:21,690 If you know anything about this medieval cosmos, you'll know that, as I said before, 312 00:31:21,870 --> 00:31:25,380 above the orbit of the moon was this perfected crystalline matter. 313 00:31:26,280 --> 00:31:31,190 Below the orbit of the moon was this impure matter above the sun when everything was in circles, 314 00:31:31,680 --> 00:31:35,759 below the moon is where the elements are vertical motion precipitation of wind and fire. 315 00:31:35,760 --> 00:31:37,590 Goodness knows what. And the earth is in the middle. 316 00:31:39,780 --> 00:31:48,540 Until this point, this this phase transition or the symmetry breaking, if you like, had never been explained, his body language never been explained. 317 00:31:49,260 --> 00:31:55,170 But think about gross hysteria. He has a ability to explain it because at some point nature is getting more and more compressed. 318 00:31:55,740 --> 00:31:59,729 The light filtering down through these spheres is getting weaker and weaker. At some points. 319 00:31:59,730 --> 00:32:05,010 There's no more compression to do. You can't reach that purification crystallisation position anymore. 320 00:32:06,180 --> 00:32:19,110 That's what the orbit moves. So he has a unified theory for the the the very that's a two phase structure of the apparent medieval cosmos. 321 00:32:19,140 --> 00:32:23,750 Now, I hope with me so far the point is. Not that this is complete baloney. 322 00:32:24,080 --> 00:32:25,010 Obviously, it's wrong. 323 00:32:25,020 --> 00:32:35,090 We know this is wrong, but that he's going about it in that sort of constructive, theoretical, physical way that we do things today. 324 00:32:35,560 --> 00:32:36,680 And here are his laws. 325 00:32:37,010 --> 00:32:44,480 You know, this like expansive states tend to think we have multiple multiplication that is conserved is a minimum density and perfection. 326 00:32:44,900 --> 00:32:48,760 It's like for those six, it turns out you construct a cosmology. 327 00:32:48,770 --> 00:32:52,370 Well, that's what we did. So this is a bit of fun. 328 00:32:55,300 --> 00:33:02,830 But it turns out we did all the fun. So Richard Dyer from the Institute of Cosmological Computing, I went to say, Would you like to join this project? 329 00:33:03,130 --> 00:33:07,000 We've discovered something that looks rather cosmological, both up your street. 330 00:33:07,510 --> 00:33:13,930 Would you like to. Would you like to discover what the cosmological cosmologists competition cosmologist was thinking eight centuries ago? 331 00:33:14,380 --> 00:33:18,910 Actually, I am. I think there's a him. I went to the whole seminar, to the whole institute. 332 00:33:20,260 --> 00:33:29,410 And all but one were looking at me with the same with expressions that number of you are now asking What on earth is this supposed to be about? 333 00:33:29,620 --> 00:33:32,620 But Richard was absolutely either fixed. 334 00:33:33,190 --> 00:33:40,450 I have the first question. So he actually translated we translated together cross tests. 335 00:33:44,030 --> 00:33:51,590 Six axioms. I mean, this is clear. They're actually quite easy to turn into differential equations, and it turns out that you can you can solve them. 336 00:33:51,840 --> 00:33:56,690 And so, you know, we can now this is now the point is this may sound anachronistic, 337 00:33:56,690 --> 00:34:04,920 but if we if we promise ourselves to translate the Latin into English. I mean, translating the texts into mathematics is just one more step. 338 00:34:04,930 --> 00:34:08,970 So we're making a mathematical translation of this medieval model. 339 00:34:09,190 --> 00:34:13,919 It's you know, this is the this is the light field. 340 00:34:13,920 --> 00:34:20,639 It's generated by matter. It's absorbed by matter. And this says that the like the velocity of the matter follows the radiation field. 341 00:34:20,640 --> 00:34:26,490 And so this is a continuity equation. So you will know these things. It's great to talk about this in the physics department more often. 342 00:34:26,490 --> 00:34:31,560 This is just more paper. But, you know, this this is these are the critical, critical ratios. 343 00:34:31,740 --> 00:34:37,230 So let me give you some idea what we've done. This layer here is the Latin behind the English. 344 00:34:37,440 --> 00:34:42,000 And we've sort of layered this with with with mathematics and started to compute with it. 345 00:34:42,300 --> 00:34:46,380 So you can compute with it what that is going for, be we at the outset. 346 00:34:47,160 --> 00:34:50,790 Oh yeah. Yes. He says there is. 347 00:34:51,630 --> 00:34:55,450 Okay. There are parameters we have to allow ourselves. He says there is a minimum density. 348 00:34:56,520 --> 00:34:59,940 So the boundary condition is that there is a minimum density. 349 00:34:59,940 --> 00:35:05,790 And when you hit that medium density, that's the boundary condition. And there's nothing beyond that. 350 00:35:05,850 --> 00:35:13,540 No, there's nothing. There's nothing. There's nothing. Nothing beyond that. Yes. 351 00:35:14,180 --> 00:35:19,090 If you like. Yes. How do the shells and lies of the Group of Eight come out? 352 00:35:19,360 --> 00:35:22,240 Okay. So actually they come up. Very good question. 353 00:35:22,790 --> 00:35:30,460 He what's interesting is that he in the text, he's aware that although he's thought through carefully this minimum set of principles, 354 00:35:30,760 --> 00:35:35,230 he kind of feels that though he can't prove that that hasn't specified the number of shells. 355 00:35:35,920 --> 00:35:42,900 So he the text finishes with this weird Pythagorean argument that there must be ten, because ten is the fourth triangular number. 356 00:35:43,730 --> 00:35:48,920 Um, there is this kind of cute, but, but, but he kind of knows that something else sets the number of shells. 357 00:35:49,180 --> 00:35:54,690 And I'm going to show you, but I'm just trying to run this through. 358 00:35:54,700 --> 00:35:58,219 This is a. Moving his calculations. 359 00:35:58,220 --> 00:36:03,010 I think this will probably run. Should run. Yes. 360 00:36:03,400 --> 00:36:09,190 So this is the the computation of the incoming lumen from the outer sphere. 361 00:36:11,650 --> 00:36:19,000 It turns out that if if he doesn't ostensibly mention anything through his opacity and absorption, 362 00:36:19,540 --> 00:36:23,470 when you don't have any absorption of the light coming in from the outside, 363 00:36:23,650 --> 00:36:28,810 as you can see, the light pressure actually increases and increases because you get concentrated in this one overall squared way. 364 00:36:29,770 --> 00:36:33,850 And when ends up actually with an infinite cascade of integer shells. 365 00:36:36,110 --> 00:36:40,010 So what we liked, what we wanted to do was to put in the absorption term. 366 00:36:40,910 --> 00:36:49,820 That actually the very process of doing this through as back into the text and it got got everyone looking at the text a lot harder. 367 00:36:50,090 --> 00:36:56,180 It turns out that we had overlooked the point at which he explicitly writes 368 00:36:56,420 --> 00:37:01,820 that this light cascade is being weakened as it descends through the shell. 369 00:37:02,420 --> 00:37:09,530 Obviously, he didn't have access to this computation, but but that does illustrate some of the textual and humanities advantage of 370 00:37:09,530 --> 00:37:15,200 doing this crazy stuff that by asking these apparently anachronistic questions, 371 00:37:15,290 --> 00:37:19,760 one is actually forced to look at the texts in different, different ways, and they like that. 372 00:37:20,150 --> 00:37:27,920 So this was the solar system solution. So in fact, it turns out that there's a whole phase space of of different shell numbers. 373 00:37:27,920 --> 00:37:33,230 So perfect. You set me up for this one sort of loop that there are three there are three parameters to this. 374 00:37:33,650 --> 00:37:39,650 Um, the opacity that the, the original strength of light and the, 375 00:37:39,680 --> 00:37:45,290 and the transparency of the purified material and if you want, it is a number of shells. 376 00:37:45,290 --> 00:37:46,489 If you want ten shells, 377 00:37:46,490 --> 00:37:54,530 which is our solar system or know what he thinks is you're living in this this red shell there in terms of the parameter space. 378 00:37:54,530 --> 00:38:01,820 So great. Great question. So there are parameters which which is no, I mean, just reception. 379 00:38:03,790 --> 00:38:04,480 As you probably know, 380 00:38:04,690 --> 00:38:13,959 the first attempts to attempt to solve Einstein's gravitation gravitation general relativity field equations in in spherical symmetry 381 00:38:13,960 --> 00:38:22,300 for the entire cosmos was performed simultaneously by Friedman in Soviet Union and and George Schmidt Belgian Catholic priest. 382 00:38:22,300 --> 00:38:29,110 And when he was actually working in Cambridge with Eddington and what later was called the Big Bang, 383 00:38:29,110 --> 00:38:32,590 but not by these people, the expanding universe was was, was the result. 384 00:38:32,920 --> 00:38:39,430 Now, we don't know for sure that gross test was aware of that. 385 00:38:39,730 --> 00:38:41,230 The that was aware of gross yes. 386 00:38:41,230 --> 00:38:55,510 We do actually know that a that an Oxford humanities scholar of gross test who loved this text gave a lecture at the British Academy in April of 1922, 387 00:38:56,500 --> 00:38:58,660 at which course we still have the transcript. 388 00:38:58,870 --> 00:39:05,230 He said that he believes that were a contemporary physicist who had mathematics beyond his own capabilities 389 00:39:05,440 --> 00:39:09,819 to look at this text and be inspired from it that it might have something to say about the cosmos. 390 00:39:09,820 --> 00:39:20,350 Today we know that a party of academics from Cambridge, including people who work with Eddington, went on to London by train to attend the lecture. 391 00:39:20,620 --> 00:39:25,480 We do not know whether Lavarch was was one of them, but it would kind of make a go just to. 392 00:39:25,490 --> 00:39:31,450 I'm still hoping that St Edmunds College might serve up a diary where he he comments this would not be it would be lovely. 393 00:39:31,720 --> 00:39:37,030 And I think we should look briefly at colour before we put before we stop because this is important 394 00:39:37,450 --> 00:39:41,890 and gave us another of our lives onto the rainbow and other things I like to tell you about. 395 00:39:42,760 --> 00:39:52,149 This lecture needs to be transportable across the Atlantic so that when he writes a jewel of a treatise after The Theory of Light, 396 00:39:52,150 --> 00:40:01,540 he writes about colour. It's 400 Latin words is the first one we actually looked at in detail and produced an edition of Because it was so short. 397 00:40:02,650 --> 00:40:11,740 And for him the colour is important because it's the validation of his theory that matter is atoms with light amalgamated with it. 398 00:40:12,900 --> 00:40:21,450 So the consequence that is common. So when he sees colours, he sees his idea of light upholding and giving space to matter. 399 00:40:21,630 --> 00:40:26,550 So short takes 11 manuscripts. There's one in the British library, rather damaged by the fire of London. 400 00:40:27,030 --> 00:40:33,690 This one, it fits between the look which you've just looked at and the Rainbow text written at 1255. 401 00:40:34,700 --> 00:40:38,850 And so let's set off and see what the gallery is all about. 402 00:40:39,060 --> 00:40:45,210 I could almost put the text up on one one slide. It's very, very short and it's very precise and condensed. 403 00:40:47,540 --> 00:40:51,720 He starts saying like colour is like embodied in the. That's okay. 404 00:40:51,740 --> 00:40:56,030 So it's linked to his like hypothesis. He's like metaphysics. Then he says something extraordinary. 405 00:40:56,030 --> 00:41:03,709 Identifies three bi polar qualities of colour. Colour, he says, can either be the last, is pure and impure, or somewhere in between or obscure, 406 00:41:03,710 --> 00:41:06,940 perhaps bright and then or somewhere in between or copious gifts. 407 00:41:06,950 --> 00:41:08,960 Not all great or little or somewhere in between. 408 00:41:09,800 --> 00:41:17,690 And he then goes on to insist that the purity, impurity that's dominated by the material and these two other dimensions, 409 00:41:17,690 --> 00:41:24,260 if I may call it, are properties of light themselves and a particular oddly for trees on colour. 410 00:41:24,270 --> 00:41:30,110 No colours are mentioned in the ecology apart from black and white, but it's, it's a theatre for colour. 411 00:41:30,710 --> 00:41:34,940 And he starts doing combinatorics with these three different axes. 412 00:41:35,660 --> 00:41:36,379 What can you see. 413 00:41:36,380 --> 00:41:42,410 What kind of Smithson or experimental psychologist who's one of the world's colour experts actually might have been rather intrigued by this, 414 00:41:42,410 --> 00:41:48,380 which is, of course, because I'm sure you know that our perception of colour is three dimensional. 415 00:41:49,370 --> 00:41:55,219 And that's because in the rest of our eyes there are three different physiological types of cone cells. 416 00:41:55,220 --> 00:42:01,070 They have different three different pigments in them. Imagine he called the short, medium and long wavelength cones. 417 00:42:01,670 --> 00:42:08,480 And so an arbitrary, high dimensional spectral content is filtered by our perceptive apparatus by three numbers. 418 00:42:08,840 --> 00:42:12,620 And the neural fine rates from these three different cones into what's called the 419 00:42:12,620 --> 00:42:15,769 confocal and captures and it starts it's neurologically processed by the brain. 420 00:42:15,770 --> 00:42:23,450 So that's why this is an LGB field, because with a red and green and blue light, you can construct any colour scheme you want. 421 00:42:23,450 --> 00:42:31,250 And there it is on the retina. And here is a retina imaged by Hannah and her team and here they've coloured in the 422 00:42:31,760 --> 00:42:36,290 if one can identify now where the short to the medium and the longer cones are. 423 00:42:36,290 --> 00:42:40,160 It's a rather interesting random array with excitable bits from time to time. 424 00:42:40,880 --> 00:42:45,450 So you can what you do mathematically. You would think about colour today in a sort of kind of cute. 425 00:42:45,470 --> 00:42:49,250 One way of doing it is project this this mathematical structure, 426 00:42:49,250 --> 00:42:54,290 this vector space structure into colour cubes and plot the long way, medium and short with, you know, a comb. 427 00:42:54,290 --> 00:42:57,380 And when they're all turned off, 000 is black. 428 00:42:57,860 --> 00:43:00,610 And when they're all turned on, the opposite corner is the white colour. 429 00:43:00,980 --> 00:43:10,310 Okay, so this is the normal, normal human human vision and I can fill that coat, that space in with all the colours that we can expect, as we can see. 430 00:43:11,490 --> 00:43:17,879 So. No, this is excluded because what's beginning to emerge is something that looks like a 431 00:43:17,880 --> 00:43:21,120 description of the three dimensional mathematical space in which colour results. 432 00:43:21,240 --> 00:43:27,479 Is this really what's going on or is the three there because of the Trinity or something like that? 433 00:43:27,480 --> 00:43:31,350 And we're just projecting a sort of wistfulness back onto on the cross test. 434 00:43:32,190 --> 00:43:40,050 Well, Moore is true. He then starts doing combinatorics with this text and it becomes a highly mathematical text. 435 00:43:40,350 --> 00:43:45,900 So there's no algebra in it because algebra was being invented at the time, was being adopted here in Europe at the time. 436 00:43:46,200 --> 00:43:52,529 He starts counting colours and he says that there are seven colours exactly from these three quantities and that seven 437 00:43:52,530 --> 00:44:00,060 turns out to be too cute on this one because he says that from white there are seven colours close to what is known. 438 00:44:00,380 --> 00:44:02,640 No more, no fewer. What's he doing? 439 00:44:02,880 --> 00:44:11,610 Turns out he describes this by saying these three quantities, which are 111 white one can now reduce them either by reducing one at a time, 440 00:44:12,300 --> 00:44:15,960 which is equivalent to moving down the edges of the key or two at a time, 441 00:44:16,470 --> 00:44:23,640 holding one fixed, which is equivalent to moving across the diagonals of the phases or three all at once, which is moving down the diagonal. 442 00:44:23,640 --> 00:44:28,910 So that's. Seven different colour directions in this colour states. 443 00:44:29,210 --> 00:44:32,810 There they are with Cartesian coordinates, as we call them today. 444 00:44:33,680 --> 00:44:40,820 Now note that this is most definitely not, as some of the current literature was saying, just a recapitulation of Aristotle. 445 00:44:41,060 --> 00:44:47,150 Aristotle has that colour does. The colours are between black and white, but they're on a linear line. 446 00:44:47,270 --> 00:44:51,980 This is a ladder of descent from colours of white towards toward towards black. 447 00:44:52,910 --> 00:44:59,540 In his descent, Switzerland since R2. So it looks as though we're really onto something. 448 00:45:00,650 --> 00:45:11,650 There was one little flaw, however, and I told you that because this is white is Malta chloro Puram not all three together. 449 00:45:12,620 --> 00:45:18,829 So given that he also knows about Black, you'd expect him to discuss Black as being the opposite of those three. 450 00:45:18,830 --> 00:45:22,760 That would be polka interior and obscure, wasn't it? 451 00:45:23,950 --> 00:45:29,529 But the sentence we get to at that point reads looks impure. 452 00:45:29,530 --> 00:45:33,340 Negrito is thus black. The word obscura is not there. 453 00:45:34,360 --> 00:45:41,620 It's in the current position. It's a pity because everything was looking so mathematically tight. 454 00:45:42,040 --> 00:45:44,050 Of course, there's no grammatical problems with this. 455 00:45:44,240 --> 00:45:49,959 With this text, it didn't look problematic, but the scientists were beginning to be convinced that he was thinking highly, 456 00:45:49,960 --> 00:45:53,860 mathematically and abstractly about this thing with some surprised. 457 00:45:54,040 --> 00:46:02,909 This one flaw is that. Now, this is where we learned about the history of of scholarship about this manuscript, 458 00:46:02,910 --> 00:46:07,460 because the last edition of this we're working on from Bauer edited German scholar. 459 00:46:08,160 --> 00:46:13,770 And it is all across the songs at about 1910. He only had access to rather late manuscripts. 460 00:46:14,340 --> 00:46:19,590 Um. Here is his the family tree of manuscripts. 461 00:46:19,590 --> 00:46:23,970 You can do this just as you just the biologists do phylogeny, by the way, because it was always nice. 462 00:46:24,010 --> 00:46:25,860 Kids get copied by scribes one from another. 463 00:46:26,100 --> 00:46:31,650 So if any scribe introduces an error, any subsequent copying will typically copy the error and not reverse it. 464 00:46:31,920 --> 00:46:36,110 So one can reconstruct all the family tree. Just this one reconstructs mutations in several features. 465 00:46:36,120 --> 00:46:44,460 And so the point is that that that was editing from this one down here, he didn't have access, which just cascades in cascades of error. 466 00:46:45,210 --> 00:46:52,650 Charles pointed out this manuscript here in Madrid was unknown to him, but that he happened to be going to Madrid that July. 467 00:46:52,650 --> 00:46:56,940 Would he like us to check on that early manuscript from a different branch to see whether perhaps 468 00:46:57,210 --> 00:47:02,460 our hypothesis that the original full three dimensions of blackness had been written down? 469 00:47:02,460 --> 00:47:06,780 You know where this story is going now? I don't think so. He came this is actually what he did. 470 00:47:06,780 --> 00:47:14,220 And and the PDF winged its way back there where we said we expect it to be as the word you put it very obscure. 471 00:47:14,670 --> 00:47:22,020 Yeah. So this is our Da Vinci Code moment where, you know, by doing by doing some mathematical physics on this. 472 00:47:24,000 --> 00:47:26,060 This is the manuscript we were somehow able to predict. 473 00:47:26,230 --> 00:47:35,530 Were you to enter the vaults of a museum in Madrid you would find in Latin on a 13th century document the word obscura at this point there. 474 00:47:37,180 --> 00:47:41,979 But but. But it kind of does validate what validates the project. 475 00:47:41,980 --> 00:47:46,330 So why isn't that? Yes, there are other other textual problems emerge of some interest. 476 00:47:47,860 --> 00:47:52,120 The text goes on to say that the seven colours from whiteness, as I said before. 477 00:47:52,390 --> 00:47:56,980 Similarly, he says, there are seven colours. Augmenting from blackness. 478 00:47:59,290 --> 00:48:00,910 And then so he says there are nine altogether. 479 00:48:02,490 --> 00:48:10,740 Now, those who know me will know that getting Matt's right is not my strong point, which is kind of unfortunate for a theoretical physicist. 480 00:48:11,160 --> 00:48:15,120 But even I know that seven plus seven doesn't usually equal nine. 481 00:48:16,770 --> 00:48:23,850 So we run this. We had all sorts. It turns out this is a rather simple explanation if you can go through the manuscript tradition. 482 00:48:24,300 --> 00:48:26,640 Cross Test was looking at Arab manuscripts the first time. 483 00:48:26,640 --> 00:48:31,410 He was one of the first to adopt what we now call known of as Arabic numerals rather than Roman numerals. 484 00:48:31,710 --> 00:48:40,740 So he wrote his 14 as we would but but was rather open for the medieval four is a is 485 00:48:40,740 --> 00:48:45,690 a modern meaning of X of this scribe who doesn't know numerals sees a written 14. 486 00:48:45,870 --> 00:48:51,569 He thinks he sees a one and then across. And then of course, the next one translate that says no. 487 00:48:51,570 --> 00:48:56,430 Then because he thinks he's looking at the latter nine and that's that's that's that's how it happens. 488 00:48:57,090 --> 00:49:06,300 So the translation issues as well. We'll just finish with the Rango because we still haven't answered the question. 489 00:49:07,020 --> 00:49:15,780 Does cross test's three dimensional colour scheme map onto our RGV colour scheme any way at all? 490 00:49:16,050 --> 00:49:19,590 Don't forget, the problem was he didn't mention any colours. 491 00:49:20,910 --> 00:49:27,720 Oh, for a TARDIS to go back with a colour deluxe colour chart, you know, do not sell the charts back to the 13th century. 492 00:49:27,900 --> 00:49:32,880 Bishop Robert, would you mind telling us which of these colours you refer to as Flora Obscura? 493 00:49:33,410 --> 00:49:33,950 Whatever. 494 00:49:35,220 --> 00:49:44,610 Then we come across to everything on the rainbow, most of which is about the geometric optics of lines and clouds forming an arc and so forth. 495 00:49:44,820 --> 00:49:48,360 Actually, he's the first to identify refraction as the source of the rainbow, 496 00:49:48,480 --> 00:49:53,390 but right at the end he talks of the rainbow in that same colour space language of glory. 497 00:49:53,430 --> 00:49:57,000 Aha. Because rainbows in the 13th century is very much like the rainbows here. 498 00:49:58,050 --> 00:50:07,980 He talks about greatness and less, but not our Parker as being strangely not bright or dim colours, but the different colours in the rainbow. 499 00:50:08,210 --> 00:50:13,410 Oh, that's a bit of a surprise. But he then says, Consider the space, not a one rainbow. 500 00:50:13,500 --> 00:50:18,450 Consider all possible rainbows in all different clouds, sophisticated for itself. 501 00:50:18,450 --> 00:50:25,320 Consider all possible rainbows. And if you have a if you see rainbows made by different droplet sizes, 502 00:50:25,770 --> 00:50:31,140 the only difference so his artificial rainbows created by this golden spray large droplets give intense colours, 503 00:50:31,410 --> 00:50:37,530 smaller droplets because there's more diffraction from them cause more desaturated, more hazy colours. 504 00:50:37,830 --> 00:50:41,640 And this is what he says is pure, impure, irritating. 505 00:50:42,240 --> 00:50:49,500 And then so we could have done, of course is to use the HLC money to send this all around the world and take photographs and colour measurements, 506 00:50:49,510 --> 00:50:51,540 all different types of rainbows, which would be very nice. 507 00:50:51,720 --> 00:50:56,640 But actually now we're in a position to do a quick job on that and that's do the full theory of the rainbow, 508 00:50:57,460 --> 00:51:01,200 uh, is the rainbow colours are not prismatic colours. 509 00:51:01,200 --> 00:51:02,100 Of course they're not at all. 510 00:51:02,310 --> 00:51:09,629 They of course caused by refraction but it's a caustic effect is a subtle, subtle effect of of rays of different coming into a droplet, 511 00:51:09,630 --> 00:51:16,500 different points bouncing out at different times, but forming a maximum and the angle at which they emerge causing the caustic. 512 00:51:16,500 --> 00:51:20,819 So you have to do some other subtle calculations of what colours you get for different 513 00:51:20,820 --> 00:51:28,530 droplet radii in rainbows and then project those rainbow coordinates onto the colour space. 514 00:51:28,530 --> 00:51:35,130 So this is this plane across that colour cube and in which this is the red green axis and this is the blue yellow one. 515 00:51:35,430 --> 00:51:39,329 Turns out that the colours of the rainbow, when projected onto the three triple cone, 516 00:51:39,330 --> 00:51:47,220 captures form a spiral coordinate system and different rainbows cause different spirals. 517 00:51:47,820 --> 00:51:55,800 And indeed this conjecture, that's the space of all possible rainbows map or net colour space is more or less true. 518 00:51:56,280 --> 00:52:01,580 It's related to a coordinate system, which is a generalisation of the Polar Gordon system. 519 00:52:01,790 --> 00:52:11,160 But no, actually the political system is only one extreme of a set of polar transformation, of conformal transformations of a of the Euclidean grids. 520 00:52:11,730 --> 00:52:18,330 Under each of these are the Z, and there are a whole set of orthogonal transformations which provide coordinate 521 00:52:18,330 --> 00:52:23,729 systems like this openness of which the rainbow is a sort of distorted rainbow, 522 00:52:23,730 --> 00:52:26,430 Cohen says, sort of distorted example. 523 00:52:26,640 --> 00:52:35,430 So his third coordinate was was the different types of spectrum from the sun, so that the sun also can give different, different lights. 524 00:52:35,430 --> 00:52:39,180 And those are his three different colours of the rainbow, different clouds, different sunlight. 525 00:52:39,360 --> 00:52:46,980 So the third coordinate we had to do by calculating the absorption of light, by the sunlight, by the atmospheres, quite a lot of data on that. 526 00:52:48,180 --> 00:52:50,940 And this is the this is the, 527 00:52:52,110 --> 00:53:01,290 the net of that spiral coordinate system for one rainbow taken through as the sun gets redder and the original illumination hits, it gets red. 528 00:53:01,590 --> 00:53:10,200 So here's the rainbow in colour space and his that linguistic the linguistic space it turns out that therefore this is this is one of the clues 529 00:53:10,200 --> 00:53:20,730 we've taken for a serious piece of experimental psychology on on how rainbows also span most of the important area of perceptual colour space. 530 00:53:21,690 --> 00:53:25,370 So we've. Created. 531 00:53:25,370 --> 00:53:32,560 I hope you see the link between as a fundamental link between matter and light in this extraordinary man. 532 00:53:32,570 --> 00:53:38,680 He has a combinatorial three dimensional space of of colour. A theatre in which colour can be manipulated. 533 00:53:38,690 --> 00:53:46,160 And the very end of that colour, treatise says, leaves a fascinating point hanging, which will which will leave him. 534 00:53:46,430 --> 00:53:54,200 He says, Look, if you don't believe what I'm saying, then you yourselves can do this by manipulating different kinds of light in darkness, 535 00:53:54,200 --> 00:54:00,410 materials of different kinds, and see if you can't make all the colours that there are. 536 00:54:01,310 --> 00:54:02,780 So with with that, 537 00:54:02,780 --> 00:54:15,169 we'll leave this tantalising idea that the beginnings of an experimental series of science might have begun right here in Oxford around 1320. 538 00:54:15,170 --> 00:54:18,080 Wouldn't that be a nice thought? Thanks very much.