WEBVTT 00:00:00.000 --> 00:00:01.919 I have to be honest with you. When I saw the 00:00:01.919 --> 00:00:05.459 topic for today's deep dive, I had this visceral 00:00:05.459 --> 00:00:08.900 physical reaction, and it was not a good one. 00:00:08.960 --> 00:00:12.560 It was that feeling, you know, sitting in a hard 00:00:12.560 --> 00:00:15.880 plastic chair in ninth grade, staring at a whiteboard 00:00:15.880 --> 00:00:18.280 and just having absolutely zero idea what was 00:00:18.280 --> 00:00:21.160 going on. Let me guess. You saw the word algebra. 00:00:21.379 --> 00:00:23.969 I saw the word algebra. And then right below 00:00:23.969 --> 00:00:26.589 it, I saw the word algorithm. And I just thought, 00:00:26.670 --> 00:00:28.949 OK, are we punishing the listeners today? Is 00:00:28.949 --> 00:00:31.929 this remedial summer school? Because, I mean, 00:00:31.949 --> 00:00:35.070 for most people, those two words are just the 00:00:35.070 --> 00:00:36.890 bane of their existence. It's funny you say that 00:00:36.890 --> 00:00:39.409 because you're right. For most of us, those words 00:00:39.409 --> 00:00:42.789 represent stress. Tests. Confusing computer code, 00:00:42.869 --> 00:00:45.270 we're told, runs our lives. Exactly. But when 00:00:45.270 --> 00:00:47.369 you actually dig into the stack of research we 00:00:47.369 --> 00:00:49.950 have today, you realize they aren't just dry 00:00:49.950 --> 00:00:53.729 academic terms. They are, in fact, the legacy 00:00:53.729 --> 00:00:56.250 of one specific guy. And see, that was the part 00:00:56.250 --> 00:00:58.149 that actually hooked me. I always assumed algebra 00:00:58.149 --> 00:01:00.450 was just, I don't know, a Greek word for headache 00:01:00.450 --> 00:01:03.450 or algorithm with some modern tech speak. But 00:01:03.450 --> 00:01:06.269 you're telling me they both trace back to a single 00:01:06.269 --> 00:01:10.189 human being. A single human being. And not, you 00:01:10.189 --> 00:01:13.030 know, a Greek philosopher in a toga and not a 00:01:13.030 --> 00:01:15.590 coder in a hoodie in Silicon Valley. We are talking 00:01:15.590 --> 00:01:18.909 about a Persian scholar, a librarian living in 00:01:18.909 --> 00:01:21.409 Baghdad in the ninth century. The idea that the 00:01:21.409 --> 00:01:24.390 source code for our entire modern world, literally 00:01:24.390 --> 00:01:26.849 the math that lets us stream this audio to you 00:01:26.849 --> 00:01:29.390 right now, was written down by a guy with a quill 00:01:29.390 --> 00:01:32.909 pen and a scroll that is just wild. It really 00:01:32.909 --> 00:01:35.790 is. We are diving into the life of Mohammed ibn 00:01:35.790 --> 00:01:38.090 Musa al -Khwarizmi. And I think we really do 00:01:38.090 --> 00:01:39.849 that by the end of this, you're going to stop 00:01:39.849 --> 00:01:42.670 seeing X as this letter that haunts your nightmares. 00:01:42.969 --> 00:01:44.890 I'm not making any promises. And start seeing 00:01:44.890 --> 00:01:47.310 it as the tool that really unlocked the modern 00:01:47.310 --> 00:01:49.629 world. That is a very tall order, but I'm here. 00:01:49.640 --> 00:01:51.659 I'm here for it. I'm ready to be convinced. So 00:01:51.659 --> 00:01:53.519 let's set the scene. We're not in ancient Greece. 00:01:53.620 --> 00:01:55.299 We're not in Renaissance Europe. We are in the 00:01:55.299 --> 00:01:58.739 Islamic Golden Age. Who was this man? So al -Khwarizmi 00:01:58.739 --> 00:02:02.640 is born around 780 CE. And to really get a handle 00:02:02.640 --> 00:02:05.200 on him, you have to understand the vibe of the 00:02:05.200 --> 00:02:08.439 era. The vibe. I like that. Yeah. The Abbasid 00:02:08.439 --> 00:02:11.120 Caliphate had just taken over a few decades earlier. 00:02:11.360 --> 00:02:13.800 The capital had moved to the brand new purpose 00:02:13.800 --> 00:02:16.500 -built city of Baghdad. And there was this... 00:02:17.269 --> 00:02:19.469 This explosion of intellectual energy. It wasn't 00:02:19.469 --> 00:02:21.289 just about conquering land anymore. It was about 00:02:21.289 --> 00:02:24.430 conquering knowledge. Right. This is a major 00:02:24.430 --> 00:02:27.110 pivot in history. And his name, Al -Khwarizmi, 00:02:27.169 --> 00:02:28.770 that's not a first name, is it? It's more of 00:02:28.770 --> 00:02:32.610 a descriptor. Exactly. In that era, names often 00:02:32.610 --> 00:02:36.370 functioned like GPS coordinates for your identity. 00:02:36.830 --> 00:02:39.090 Al -Khwarizmi pretty clearly implies he came 00:02:39.090 --> 00:02:41.430 from a place called Khwarizm. Which, if I'm looking 00:02:41.430 --> 00:02:43.490 at a modern map, is where exactly? It's a region 00:02:43.490 --> 00:02:46.199 south of the Aral Sea. Today, it's essentially 00:02:46.199 --> 00:02:48.759 split between modern Uzbekistan and Turkmenistan. 00:02:48.900 --> 00:02:51.080 But back then, it was part of what we'd call 00:02:51.080 --> 00:02:54.520 Greater Iran, a place with very deep, very old 00:02:54.520 --> 00:02:56.580 Persian cultural and scientific roots. But I 00:02:56.580 --> 00:02:58.159 remember reading in the notes that there's a 00:02:58.159 --> 00:03:00.759 bit of a historical whoops regarding his identity, 00:03:01.000 --> 00:03:04.620 something about a typo that messed up his biography 00:03:04.620 --> 00:03:07.759 for centuries. Oh, this is a classic historian's 00:03:07.759 --> 00:03:09.500 headache. That's a great little detective story. 00:03:09.819 --> 00:03:12.259 So there was a later historian, a very famous 00:03:12.259 --> 00:03:15.120 one named Altabari, who was cataloging all the 00:03:15.120 --> 00:03:18.240 famous scholars. Right. He writes out Al -Khwarizmi's 00:03:18.240 --> 00:03:20.840 full name, but then he adds this other tag at 00:03:20.840 --> 00:03:24.060 the end, Al -Qatrubali. Which means? It means 00:03:24.060 --> 00:03:26.259 someone from Quatrubal. which was a district 00:03:26.259 --> 00:03:28.599 right outside Baghdad, a sort of wine -growing 00:03:28.599 --> 00:03:31.199 suburb. Wait, he's from Central Asia and from 00:03:31.199 --> 00:03:33.780 a Baghdad suburb. Exactly the problem. For a 00:03:33.780 --> 00:03:35.819 long, long time, historians were scratching their 00:03:35.819 --> 00:03:38.080 heads. They were thinking, okay, is he the guy 00:03:38.080 --> 00:03:40.759 from Khwarazm or is he the guy from Khartoubal? 00:03:41.210 --> 00:03:43.090 because you can't really be from both places 00:03:43.090 --> 00:03:45.490 at once unless you have a very, very complicated 00:03:45.490 --> 00:03:47.530 commute. It's like being called the New Yorker 00:03:47.530 --> 00:03:49.650 from Texas. It doesn't make sense. Precisely. 00:03:49.650 --> 00:03:52.430 But modern scholars, people like Rashi Rasht, 00:03:52.430 --> 00:03:54.870 went back to the original manuscripts, and they 00:03:54.870 --> 00:03:57.629 realized something. It's highly, highly probable 00:03:57.629 --> 00:04:01.370 that a scribe somewhere down the line just missed 00:04:01.370 --> 00:04:05.110 a single tiny letter, the letter wa. Which is 00:04:05.110 --> 00:04:08.710 just the word for and? Just the word and. It 00:04:08.710 --> 00:04:14.539 should likely have read... meaning Al -Tabari 00:04:14.539 --> 00:04:16.420 was probably listing two completely different 00:04:16.420 --> 00:04:19.100 people in his catalog. Wow. But because someone 00:04:19.100 --> 00:04:21.819 a thousand years ago forgot a conjunction, we've 00:04:21.819 --> 00:04:24.100 spent centuries debating where this one guy was 00:04:24.100 --> 00:04:26.279 born. Yeah. It's a humbling lesson in history. 00:04:26.439 --> 00:04:29.019 That is terrifying. One typo and your entire 00:04:29.019 --> 00:04:31.600 identity gets merged with your neighbor. But 00:04:31.600 --> 00:04:33.720 you mentioned another name there, Al -Majuzi. 00:04:33.819 --> 00:04:35.720 That's another interesting tag, isn't it? It 00:04:35.720 --> 00:04:38.410 is. Very interesting one. Al -Majuzi translates 00:04:38.410 --> 00:04:42.290 to the Magian, or more specifically, the Zoroastrian. 00:04:42.449 --> 00:04:44.350 Wait, hold on. I thought al -Khwarizmi was this 00:04:44.350 --> 00:04:46.910 prominent scholar working for the Islamic caliph 00:04:46.910 --> 00:04:49.149 in the capital of the Islamic world. He was, 00:04:49.310 --> 00:04:51.189 absolutely. And if you read the preface to his 00:04:51.189 --> 00:04:53.509 book on algebra, it's incredibly orthodox. He 00:04:53.509 --> 00:04:55.410 praises Allah. He blesses the Prophet Muhammad. 00:04:55.629 --> 00:04:57.949 There is absolutely no doubt he was a practicing, 00:04:58.089 --> 00:05:00.850 devout Muslim. So why call him the Zoroastrian? 00:05:00.990 --> 00:05:03.589 Is it an insult? It's more likely a reference 00:05:03.589 --> 00:05:06.449 to his heritage. You have to remember, the Muslim 00:05:06.449 --> 00:05:08.629 conquest of Persia had happened a century or 00:05:08.629 --> 00:05:11.709 so before, but the cultural transition was still 00:05:11.709 --> 00:05:15.470 ongoing. It's very possible his ancestors, or 00:05:15.470 --> 00:05:18.370 maybe even al -Khwarizmi himself as a young child, 00:05:18.490 --> 00:05:21.629 were Zoroastrian before converting to Islam. 00:05:21.910 --> 00:05:24.529 It just paints such a rich picture of a melting 00:05:24.529 --> 00:05:27.029 pot, doesn't it? You have this person with... 00:05:27.209 --> 00:05:29.870 Persian heritage and Islamic faith, living in 00:05:29.870 --> 00:05:32.610 this new Arab capital, and he ends up working 00:05:32.610 --> 00:05:35.009 at the most famous think tank in history. The 00:05:35.009 --> 00:05:37.769 house of wisdom, Beit al -Hikmah. Yeah, and I 00:05:37.769 --> 00:05:40.709 think calling it a library really, really undersells 00:05:40.709 --> 00:05:42.990 it. It absolutely does. When I hear library, 00:05:43.170 --> 00:05:45.509 I think of a quiet room with a lady shushing 00:05:45.509 --> 00:05:48.050 me. This sounds more like, I don't know, Bell 00:05:48.050 --> 00:05:50.490 Labs meets the British Museum. That's a much 00:05:50.490 --> 00:05:52.430 better comparison. This was a government -funded 00:05:52.430 --> 00:05:55.189 super lab. The caliph at the time, Amal Moon. 00:05:55.639 --> 00:05:57.980 was obsessed and i mean completely obsessed with 00:05:57.980 --> 00:06:00.019 science and philosophy i heard there was a story 00:06:00.019 --> 00:06:02.600 about a dream the story goes that he had a dream 00:06:02.600 --> 00:06:05.100 where aristotle himself appeared to him no yes 00:06:06.029 --> 00:06:08.589 And after this dream, he became convinced that 00:06:08.589 --> 00:06:11.250 he needed to gather and translate all the wisdom 00:06:11.250 --> 00:06:14.389 of the ancients into Arabic. He sent emissaries 00:06:14.389 --> 00:06:17.529 to Byzantium, to India, everywhere, paying in 00:06:17.529 --> 00:06:20.790 gold to bring back manuscripts. And al -Khwarizmi's 00:06:20.790 --> 00:06:24.490 job, starting around 820 CE, was to be a lead 00:06:24.490 --> 00:06:27.290 scholar in this massive operation. He was the 00:06:27.290 --> 00:06:29.009 head astronomer and the head of the library, 00:06:29.129 --> 00:06:31.269 the collection of books. His job wasn't just 00:06:31.269 --> 00:06:33.399 to stamp books and put them on a shelf. It was 00:06:33.399 --> 00:06:36.639 to take Greek geometry, Indian numbers, Persian 00:06:36.639 --> 00:06:39.220 astronomy, and somehow make them all talk to 00:06:39.220 --> 00:06:41.019 each other. He wasn't just a translator. He was 00:06:41.019 --> 00:06:44.259 a synthesizer. That is the absolute key to understanding 00:06:44.259 --> 00:06:46.740 him. He's sitting at the crossroads of all these 00:06:46.740 --> 00:06:48.839 civilizations with all this knowledge flowing 00:06:48.839 --> 00:06:51.819 into Baghdad. And that unique position is what 00:06:51.819 --> 00:06:54.019 allowed him to write the book that changed everything. 00:06:54.420 --> 00:06:56.079 Okay, let's get into the book, the big one. I'm 00:06:56.079 --> 00:06:58.420 going to say the name. Al -Kitab al -Muqtarfavi 00:06:58.420 --> 00:07:01.300 sab al -Jabru wal -Muqabba. Which just rolls 00:07:01.300 --> 00:07:03.519 right off the tongue. Hidden in that very long 00:07:03.519 --> 00:07:07.720 title is that one little word, aljab. Yes, aljab. 00:07:07.740 --> 00:07:09.240 And that is, of course, where we get our word 00:07:09.240 --> 00:07:12.319 algebra. Now, I have always associated algebra 00:07:12.319 --> 00:07:14.819 with solving for X. That's what it is to me. 00:07:15.040 --> 00:07:18.100 But what did the word aljabr actually mean to 00:07:18.100 --> 00:07:20.480 a 9th century Persian scholar? It couldn't have 00:07:20.480 --> 00:07:23.240 meant math class. No, no, it didn't. It's actually 00:07:23.240 --> 00:07:25.620 a very practical, almost physical term. It means 00:07:25.620 --> 00:07:29.279 restoration or reunion of broken parts. I think 00:07:29.279 --> 00:07:31.860 I read it was a medical term. It was. The person 00:07:31.860 --> 00:07:35.579 who set broken bones was a Mujabir. So al -Jab 00:07:35.579 --> 00:07:37.720 is the act of setting a bone. Setting a bone. 00:07:37.779 --> 00:07:39.519 How does that relate to math? How do you set 00:07:39.519 --> 00:07:43.060 the bone of an equation? Okay, so visualize a 00:07:43.060 --> 00:07:46.860 scale, a balancing scale, or just a simple equation. 00:07:47.060 --> 00:07:49.480 Let's say you have something like x squared equals 00:07:49.480 --> 00:07:52.600 40x minus 4x squared. Okay, I'm visualizing, 00:07:52.620 --> 00:07:55.279 and I see a problem. We have a negative term 00:07:55.279 --> 00:07:57.779 on that right side, that minus 4x squared. It's 00:07:57.779 --> 00:08:00.220 messy. It's broken, to use your term. It's a 00:08:00.220 --> 00:08:02.920 deficiency. In Al -Khruizmi's mind, a negative 00:08:02.920 --> 00:08:04.759 term is a hole in the equation that needs to 00:08:04.759 --> 00:08:07.139 be filled. So you perform all -job restoration. 00:08:07.560 --> 00:08:09.660 You add 4x squared to the right side to get rid 00:08:09.660 --> 00:08:11.660 of the negative. But then the scale is unbalanced. 00:08:12.040 --> 00:08:14.660 Exactly. So to keep the balance, you must also 00:08:14.660 --> 00:08:16.699 add it to the left side. You are restoring the 00:08:16.699 --> 00:08:19.660 term by moving it over. So you're healing the 00:08:19.660 --> 00:08:22.759 negative number. The equation becomes 5x squared 00:08:22.759 --> 00:08:25.959 equals 40x. Everything is positive and whole 00:08:25.959 --> 00:08:29.370 again. You've restored it. that's al job okay 00:08:29.370 --> 00:08:31.870 that makes so much sense so what about the second 00:08:31.870 --> 00:08:35.409 part of the title the wall mukabala that means 00:08:35.409 --> 00:08:38.490 balancing or confronting it's basically reduction 00:08:39.049 --> 00:08:41.230 The next cleanup step. Okay, give me an example. 00:08:41.429 --> 00:08:44.230 So say you have x squared plus 14 equals x plus 00:08:44.230 --> 00:08:47.350 5. You have plain numbers, constants on both 00:08:47.350 --> 00:08:50.649 sides. Mookabala is canceling them out. You subtract 00:08:50.649 --> 00:08:53.610 5 from the 14 and also from the 5 on the other 00:08:53.610 --> 00:08:56.309 side. So you're left with x squared plus 9 equals 00:08:56.309 --> 00:08:58.450 x. You've simplified it. You've balanced it. 00:08:58.509 --> 00:09:00.409 It's just housekeeping, like you said, tidying 00:09:00.409 --> 00:09:02.529 up the equation. But why was this considered 00:09:02.529 --> 00:09:04.409 so revolutionary? I mean, the Greeks had been 00:09:04.409 --> 00:09:07.370 doing math for a thousand years. Didn't Euclid 00:09:07.370 --> 00:09:09.690 or Pythagoras figure this stuff out? This is 00:09:09.690 --> 00:09:11.629 the absolute crux of his genius. The Greeks were 00:09:11.629 --> 00:09:13.769 brilliant, but they had a self -imposed limitation. 00:09:14.190 --> 00:09:16.769 They were obsessed with geometry. Meaning shapes, 00:09:16.950 --> 00:09:19.370 lines, circles, triangles. Meaning physical shapes. 00:09:19.629 --> 00:09:22.330 For a Greek mathematician, a number wasn't just 00:09:22.330 --> 00:09:24.370 an abstract concept. It had to be something you 00:09:24.370 --> 00:09:27.370 could draw on the sand. So x squared wasn't just 00:09:27.370 --> 00:09:29.710 a number multiplied by itself. It was literally 00:09:29.710 --> 00:09:33.990 a square. A physical shape with four sides. And 00:09:33.990 --> 00:09:37.909 X was a line. Okay. I'm with you. So now imagine 00:09:37.909 --> 00:09:41.629 trying to add X squared plus X. In the Greek 00:09:41.629 --> 00:09:44.549 mindset, you are asking to add a flat two -dimensional 00:09:44.549 --> 00:09:47.210 square shape to a one -dimensional straight line. 00:09:47.559 --> 00:09:49.519 You can't do that. You can't. It's physically 00:09:49.519 --> 00:09:51.740 impossible. It's like asking a construction worker 00:09:51.740 --> 00:09:54.620 to add a square foot of carpet to a linear foot 00:09:54.620 --> 00:09:57.120 of fence. It's nonsensical. They're just different 00:09:57.120 --> 00:09:59.279 categories of things. Exactly. They exist in 00:09:59.279 --> 00:10:03.120 different dimensions. But Al -Khwarizmi, he didn't 00:10:03.120 --> 00:10:05.679 care. He had this incredible insight. He realized 00:10:05.679 --> 00:10:07.659 that if you strip away the geometry, if you just 00:10:07.659 --> 00:10:10.720 treat these things as abstract objects, you can 00:10:10.720 --> 00:10:12.539 add them. You can manipulate them according to 00:10:12.539 --> 00:10:15.289 a set of rules. So he basically created a virtual 00:10:15.289 --> 00:10:19.049 reality for numbers. He said, forget the carpet 00:10:19.049 --> 00:10:21.070 and the fence for a second. In this abstract 00:10:21.070 --> 00:10:23.230 world I'm building, we can combine these things. 00:10:23.490 --> 00:10:25.850 That is the aha moment. That's the paradigm shift. 00:10:26.070 --> 00:10:28.929 He liberated mathematics from the physical world. 00:10:29.230 --> 00:10:32.789 He created a unifying theory that allowed rational 00:10:32.789 --> 00:10:35.610 numbers, irrational numbers, and geometric magnitudes 00:10:35.610 --> 00:10:38.090 all to be treated as the same kind of thing, 00:10:38.509 --> 00:10:40.509 algebraic objects. But here's the thing that 00:10:40.509 --> 00:10:42.210 really blew my mind when I was reading the research. 00:10:42.750 --> 00:10:46.490 If I went back in time to 825 CE and opened his 00:10:46.490 --> 00:10:49.850 book, the compendious book on calculation, I 00:10:49.850 --> 00:10:51.590 wouldn't recognize it as a math book. No, you 00:10:51.590 --> 00:10:53.169 absolutely would not. You'd think you're reading 00:10:53.169 --> 00:10:56.169 a book of logic puzzles or maybe a legal text. 00:10:56.409 --> 00:10:58.850 Because there are no symbols. None. Not a single 00:10:58.850 --> 00:11:01.409 one. No plus sign, no minus sign, no division 00:11:01.409 --> 00:11:04.110 symbol, no equal sign, and definitely, definitely 00:11:04.110 --> 00:11:07.250 no X or Y. So how on earth do you write an equation? 00:11:07.470 --> 00:11:09.330 How do you even do this? He used what we now 00:11:09.330 --> 00:11:11.710 call rhetorical algebra. He wrote everything 00:11:11.710 --> 00:11:13.769 out in full descriptive sentences. Okay, give 00:11:13.769 --> 00:11:15.370 me an example. How would you write something 00:11:15.370 --> 00:11:19.870 simple, like x squared plus 10x equals 39? He 00:11:19.870 --> 00:11:22.250 would write, and I'm quoting a translation here, 00:11:22.909 --> 00:11:26.169 a square and 10 of its roots are equal to 39 00:11:26.169 --> 00:11:30.429 birams. Roots? Birams? What are those? The root, 00:11:30.610 --> 00:11:34.090 or shea in Arabic, which means thing, is the 00:11:34.090 --> 00:11:37.039 unknown. It's rx. The thing you're looking for. 00:11:37.159 --> 00:11:39.559 Yes. The square is, of course, that thing multiplied 00:11:39.559 --> 00:11:43.000 by itself, rx squared. And dirham, which was 00:11:43.000 --> 00:11:44.639 the local currency, was just used to represent 00:11:44.639 --> 00:11:47.559 a simple unit, a plain number. That sounds absolutely 00:11:47.559 --> 00:11:50.139 exhausting to read and write. It is incredibly 00:11:50.139 --> 00:11:52.100 dense. There's a famous problem in the book that 00:11:52.100 --> 00:11:54.500 goes something like this. If someone says... 00:11:54.830 --> 00:11:57.330 I have divided 10 into two parts and have multiplied 00:11:57.330 --> 00:12:00.049 one of them by itself. It is equal to the other 00:12:00.049 --> 00:12:02.950 taken 81 times. My brain just short -circuited 00:12:02.950 --> 00:12:05.090 trying to parse that sentence. Right. You have 00:12:05.090 --> 00:12:07.370 to hold the entire logical structure in your 00:12:07.370 --> 00:12:09.429 head just to figure out what the equation even 00:12:09.429 --> 00:12:12.649 is. 10 less thing multiplied by itself. But what's 00:12:12.649 --> 00:12:14.429 amazing is that despite the lack of symbols, 00:12:14.590 --> 00:12:17.639 his logic was flawless. He categorized every 00:12:17.639 --> 00:12:20.360 possible linear and quadratic equation into six 00:12:20.360 --> 00:12:23.519 standard forms. And for each one, he gave a step 00:12:23.519 --> 00:12:26.200 -by -step recipe for solving it. He created the 00:12:26.200 --> 00:12:28.860 first instruction manual for solving these things. 00:12:28.980 --> 00:12:31.059 The first algorithm, really. Which brings up 00:12:31.059 --> 00:12:33.500 a bit of a title fight. We call Alcorazmi the 00:12:33.500 --> 00:12:35.940 father of algebra. But I've had people tell me, 00:12:35.980 --> 00:12:38.379 actually, no, it was Diophantus. He was a Greek 00:12:38.379 --> 00:12:40.320 mathematician living in Alexandria centuries 00:12:40.320 --> 00:12:43.899 earlier. Why does Alcorazmi get the trophy? It's 00:12:43.899 --> 00:12:46.789 a debate that gets... Pretty heated in math history 00:12:46.789 --> 00:12:49.070 circles, but it comes down to purpose. Okay. 00:12:49.429 --> 00:12:52.090 Diophantus wrote a brilliant book called Arithmetica, 00:12:52.190 --> 00:12:55.490 and he definitely solved some very complex algebraic 00:12:55.490 --> 00:12:58.409 type problems. But here is the key distinction. 00:12:59.210 --> 00:13:02.029 Diophantus was interested in number theory. He 00:13:02.029 --> 00:13:04.769 was solving specific puzzles. He wanted to find 00:13:04.769 --> 00:13:08.620 specific, elegant... integer solutions to specific 00:13:08.620 --> 00:13:11.340 riddles. So he was like a guy who is incredibly 00:13:11.340 --> 00:13:13.720 good at doing the Sunday crossword or Sudoku. 00:13:13.879 --> 00:13:15.840 That's a great analogy. He's a master puzzle 00:13:15.840 --> 00:13:18.559 solver. But Alcrisis wasn't just solving puzzles. 00:13:18.759 --> 00:13:21.220 He was teaching a method. He was the first to 00:13:21.220 --> 00:13:23.299 treat algebra as a discipline in its own right, 00:13:23.399 --> 00:13:26.179 for its own sake. He wasn't looking for one specific 00:13:26.179 --> 00:13:28.539 answer. He was showing you the general theory 00:13:28.539 --> 00:13:30.779 of how all equations of a certain type work. 00:13:31.039 --> 00:13:34.830 So Diophantus gave you a fish. But Al -Khwarizmi 00:13:34.830 --> 00:13:37.850 taught you how to fish. Perfectly put. He wrote 00:13:37.850 --> 00:13:41.370 the textbook, not the puzzle book. The historian 00:13:41.370 --> 00:13:43.830 Carl B. Boyer said that Al -Khwarizmi's work 00:13:43.830 --> 00:13:46.370 is much closer to the elementary algebra of today 00:13:46.370 --> 00:13:49.090 than the works of either Diophantus or the Indian 00:13:49.090 --> 00:13:51.309 mathematician Brahmagupta. And it was a textbook 00:13:51.309 --> 00:13:53.529 with a purpose. This wasn't just ivory tower 00:13:53.529 --> 00:13:55.830 theory. The caliph encouraged him to write this 00:13:55.830 --> 00:13:58.250 book because people had real everyday problems 00:13:58.250 --> 00:14:00.610 to solve. Very real problems. The book is full 00:14:00.610 --> 00:14:02.509 of practical examples. What kind of problems 00:14:02.509 --> 00:14:05.210 are we talking about? Things like digging canals 00:14:05.210 --> 00:14:07.750 of a certain volume, measuring the area of different 00:14:07.750 --> 00:14:10.509 shapes of land for farming or taxation, business 00:14:10.509 --> 00:14:13.649 deals, trade. But the biggest one, and the one 00:14:13.649 --> 00:14:15.289 that takes up a huge chunk of the second half 00:14:15.289 --> 00:14:17.909 of the book, is inheritance. Inheritance. You 00:14:17.909 --> 00:14:20.509 need algebra to figure out who gets grandma's 00:14:20.509 --> 00:14:23.870 antique lamp. In 9th century Islamic law, oh 00:14:23.870 --> 00:14:27.529 yes, it was notoriously complex. The Quran lays 00:14:27.529 --> 00:14:30.110 out very specific fractional shares for every 00:14:30.110 --> 00:14:33.279 relative. For example. A wife gets one -eighth 00:14:33.279 --> 00:14:34.860 of the estate if there are children, but one 00:14:34.860 --> 00:14:36.980 -fourth if there aren't. A daughter gets half 00:14:36.980 --> 00:14:39.600 of what a son gets. Parents get one -sixth each. 00:14:39.759 --> 00:14:42.320 It goes on and on. Okay, I can see how that gets 00:14:42.320 --> 00:14:45.139 messy really, really fast. Especially if you 00:14:45.139 --> 00:14:47.620 have a wife, two daughters, a mother, and a brother, 00:14:47.720 --> 00:14:50.580 and the estate is, I don't know, a farm and 30 00:14:50.580 --> 00:14:52.980 camels. It gets incredibly messy. You end up 00:14:52.980 --> 00:14:55.580 with these really complex fractional equations 00:14:55.580 --> 00:14:57.820 where you have to find a common denominator and 00:14:57.820 --> 00:14:59.740 solve for an unknown share to make sure everyone 00:14:59.740 --> 00:15:02.019 gets their exact legal right without You know, 00:15:02.019 --> 00:15:04.700 having to cut a camel in half. Alcor Rizmi showed 00:15:04.700 --> 00:15:08.899 step by step how algebra could solve these disputes 00:15:08.899 --> 00:15:11.639 fairly and logically. So he wasn't just a mathematician. 00:15:11.860 --> 00:15:14.860 He was essentially an estate lawyer, a surveyor, 00:15:14.960 --> 00:15:17.320 a trade consultant. He was providing the foundational 00:15:17.320 --> 00:15:20.200 tools for the entire legal and economic system 00:15:20.200 --> 00:15:22.879 to function. It's the ultimate example of applied 00:15:22.879 --> 00:15:26.299 mathematics. OK, so he gives us algebra. He liberates 00:15:26.299 --> 00:15:29.000 numbers from shapes. He solves inheritance law. 00:15:29.450 --> 00:15:32.350 That alone is a Hall of Fame career. But we started 00:15:32.350 --> 00:15:34.570 this whole deep dive with two words, algebra 00:15:34.570 --> 00:15:38.690 and algorithm. Yes, and it's fascinating. While 00:15:38.690 --> 00:15:41.129 algebra comes from the title of his book, the 00:15:41.129 --> 00:15:44.110 word algorithm comes from the man himself. It's 00:15:44.110 --> 00:15:46.990 a corruption of his name, Al -Khwarizmi. It is. 00:15:47.090 --> 00:15:49.710 His second great masterpiece was a book on arithmetic. 00:15:50.549 --> 00:15:53.309 The original Arabic text is actually lost to 00:15:53.309 --> 00:15:55.610 history, but it survived in Latin translations. 00:15:56.450 --> 00:15:59.730 The most famous one was titled Algoritmo de Numero 00:15:59.730 --> 00:16:02.190 Indorum. Which means? Al -Khwarizmi on the Hindu 00:16:02.190 --> 00:16:05.090 art of reckoning. And the author's name, Al -Khwarizmi, 00:16:05.210 --> 00:16:08.110 was Latinized into algorithm. And over time, 00:16:08.149 --> 00:16:11.090 algorithm just morphs into algorithm. It does. 00:16:11.330 --> 00:16:14.309 And in Spanish and Portuguese, it became Gorizmo, 00:16:14.409 --> 00:16:18.259 which still means digit. His name literally became 00:16:18.259 --> 00:16:20.720 the word for a number. So what was in this book 00:16:20.720 --> 00:16:23.080 that was so revolutionary that his name became 00:16:23.080 --> 00:16:25.840 synonymous with calculation itself? Because he 00:16:25.840 --> 00:16:27.779 introduced the killer app of the Middle Ages 00:16:27.779 --> 00:16:30.620 to the Western world, the Hindu -Arabic numeral 00:16:30.620 --> 00:16:33.620 system. Our numbers, one through nine, and the 00:16:33.620 --> 00:16:36.620 big hero of the story, zero. The one and only. 00:16:36.720 --> 00:16:38.779 We take this completely for granted, but you 00:16:38.779 --> 00:16:40.639 have to try to imagine doing math before this. 00:16:40.740 --> 00:16:42.519 You're in Europe. You're a merchant in, say, 00:16:42.519 --> 00:16:45.220 11th century Italy. You're using Roman numerals. 00:16:45.299 --> 00:16:47.659 Ugh. I can barely read the Super Bowl number 00:16:47.659 --> 00:16:50.139 in Roman numerals. It's a mess. Now try doing 00:16:50.139 --> 00:16:55.379 long division. Divide MCMXLV by 14th. I wouldn't 00:16:55.379 --> 00:16:57.059 even know where to begin. Is that even possible? 00:16:57.480 --> 00:16:59.899 It's basically impossible. It's a complete nightmare. 00:17:00.159 --> 00:17:02.659 The Roman system was okay for recording a number 00:17:02.659 --> 00:17:04.960 once you had it, but it was terrible for actually 00:17:04.960 --> 00:17:08.380 calculating with it. Al -Khwarizmi's book explained 00:17:08.380 --> 00:17:11.299 the Indian system of place value. The idea that 00:17:11.299 --> 00:17:14.059 a 1 in the tens column is worth 10 times as much 00:17:14.059 --> 00:17:16.839 as a 1 in the ones column? Yes. And that system 00:17:16.839 --> 00:17:19.539 only works because of the zero. It's the placeholder 00:17:19.539 --> 00:17:21.539 that makes the whole thing click. The ultimate 00:17:21.539 --> 00:17:23.480 game changer. And he didn't just explain the 00:17:23.480 --> 00:17:26.500 numbers. He described a specific way to do these 00:17:26.500 --> 00:17:29.980 calculations using a tool called ATTACK. A dust 00:17:29.980 --> 00:17:32.400 board. Tell me about the dust board because this 00:17:32.400 --> 00:17:34.720 is where I think the connection to modern computers 00:17:34.720 --> 00:17:38.299 really becomes clear. So paper or parchment was 00:17:38.299 --> 00:17:40.259 incredibly expensive. You didn't want to waste 00:17:40.259 --> 00:17:43.019 it on scratch work. So people used a wooden board 00:17:43.019 --> 00:17:45.740 covered in a thin layer of fine sand or dust. 00:17:46.160 --> 00:17:48.359 You would write your numbers in the sand with 00:17:48.359 --> 00:17:50.380 a stylus. Okay, like a primitive whiteboard. 00:17:50.559 --> 00:17:53.619 Sort of. But here's the key feature. When you 00:17:53.619 --> 00:17:55.940 did a step of a calculation, Let's say you're 00:17:55.940 --> 00:17:58.200 carrying the one in addition. You would physically 00:17:58.200 --> 00:18:01.000 erase the old number with your finger and write 00:18:01.000 --> 00:18:03.019 the new result in its place. You're overwriting 00:18:03.019 --> 00:18:05.819 the data in its memory location. You are literally 00:18:05.819 --> 00:18:08.920 overwriting the data. Unlike in Abacus, where 00:18:08.920 --> 00:18:11.140 all the beads stay there, the dust board had 00:18:11.140 --> 00:18:14.490 a dynamic updating state. You erase the input 00:18:14.490 --> 00:18:17.369 to create the output step by step. That is precisely 00:18:17.369 --> 00:18:19.589 how computer RAM works. You have a memory address, 00:18:19.789 --> 00:18:21.890 you write a value to it, you perform an operation, 00:18:22.109 --> 00:18:24.630 and you overwrite that address with the new value. 00:18:24.869 --> 00:18:27.609 The parallel is astounding. He was teaching people 00:18:27.609 --> 00:18:30.190 how to process information in a step -by -step, 00:18:30.250 --> 00:18:33.630 mechanical, repeatable way. Step one, write the 00:18:33.630 --> 00:18:36.130 numbers. Step two, add the rightmost column. 00:18:36.329 --> 00:18:38.670 Step three, erase the operands and write the 00:18:38.670 --> 00:18:42.900 result. Step four, carry the one. That recipe. 00:18:43.640 --> 00:18:46.140 That is an algorithm. And the people who adopted 00:18:46.140 --> 00:18:48.039 this newfangled method in Europe were actually 00:18:48.039 --> 00:18:51.079 called algarists? They were. And for a while, 00:18:51.140 --> 00:18:52.920 they were the rebels. They were the cool kids 00:18:52.920 --> 00:18:54.839 with the new tech. Was it controversial? Oh, 00:18:54.859 --> 00:18:57.400 hugely. For centuries, there was a war between 00:18:57.400 --> 00:19:00.079 the algarists and the abacists, the people who 00:19:00.079 --> 00:19:02.000 were masters of the abacus and wanted to stick 00:19:02.000 --> 00:19:04.599 to the old ways. I absolutely love the idea of 00:19:04.599 --> 00:19:07.220 a medieval turf war between math nerds, guys 00:19:07.220 --> 00:19:09.539 with beads versus guys with sandboards. It was 00:19:09.539 --> 00:19:12.039 real. The abacists argued their method was more 00:19:12.039 --> 00:19:15.119 reliable. less prone to error. But the Algarists 00:19:15.119 --> 00:19:17.119 eventually won because their system was just 00:19:17.119 --> 00:19:19.339 so much more powerful and efficient, especially 00:19:19.339 --> 00:19:21.720 for multiplication and division. And it all came 00:19:21.720 --> 00:19:24.259 from this one source. So much so that in the 00:19:24.259 --> 00:19:26.140 Latin manuscripts that spread through Europe, 00:19:26.299 --> 00:19:28.759 the text often began with the powerful phrase, 00:19:29.000 --> 00:19:33.700 Dixit Algarismi. Thus spake Alquarismi. It sounds 00:19:33.700 --> 00:19:35.720 biblical, doesn't it? It has the weight of a 00:19:35.720 --> 00:19:38.099 commandment from a prophet. Do it this way because 00:19:38.099 --> 00:19:41.289 Alquarismi, the master, said so. His name itself 00:19:41.289 --> 00:19:43.529 became the authority on calculation. So every 00:19:43.529 --> 00:19:45.630 single time a programmer writes a line of code 00:19:45.630 --> 00:19:48.190 today or Amazon servers recommend me a pair of 00:19:48.190 --> 00:19:51.170 shoes I don't need, they are unknowingly invoking 00:19:51.170 --> 00:19:53.769 the name of this ninth century Persian librarian. 00:19:54.269 --> 00:19:56.549 It is a direct line of descent. No question. 00:19:56.750 --> 00:19:58.690 But he didn't stop at math. I mean, if you suddenly 00:19:58.690 --> 00:20:01.589 have this new superpower, this ability to calculate 00:20:01.589 --> 00:20:04.269 things that no one else could before. You're 00:20:04.269 --> 00:20:05.769 going to want to apply it to everything. And 00:20:05.769 --> 00:20:08.089 he did. He looked up at the sky. Astronomy. His 00:20:08.089 --> 00:20:11.730 third major work was the Zei Asyntind. Zei is 00:20:11.730 --> 00:20:14.069 basically a book of astronomical tables. And 00:20:14.069 --> 00:20:17.470 that word syntynd, it sounds Indian. It is. It's 00:20:17.470 --> 00:20:20.150 a corruption of the Sanskrit word satanta, which 00:20:20.150 --> 00:20:22.569 means a similar kind of astronomical treatise. 00:20:22.569 --> 00:20:25.029 So again, you see Al -Khwarizmi as the synthesizer. 00:20:25.089 --> 00:20:28.069 So he's not inventing astronomy. He's upgrading 00:20:28.069 --> 00:20:31.150 it. He's taking Indian astronomical methods and 00:20:31.150 --> 00:20:33.849 data, mixing them with the great Ptolemaic model 00:20:33.849 --> 00:20:36.509 of the universe and Persian observational traditions, 00:20:36.589 --> 00:20:39.190 and creating this massive comprehensive guide. 00:20:39.410 --> 00:20:43.569 It had 37 chapters and 116 tables with data for 00:20:43.569 --> 00:20:46.009 the sun, the moon, and the five known planets. 00:20:46.210 --> 00:20:48.630 But wasn't everyone doing star charts back then? 00:20:48.809 --> 00:20:51.750 They were. But Al -Khwarizmi Zee introduced something 00:20:51.750 --> 00:20:54.410 new and powerful to the Islamic world in this 00:20:54.410 --> 00:20:58.160 book, trigonometry. Sines and cosines. Oh no, 00:20:58.339 --> 00:21:01.380 more high school math trauma. Huh. But this was 00:21:01.380 --> 00:21:04.079 a huge deal. For the first time, he included 00:21:04.079 --> 00:21:06.460 accurate tables for the sine and cosine functions. 00:21:06.920 --> 00:21:09.819 This allowed for much, much more precise calculations 00:21:09.819 --> 00:21:13.500 of planetary positions, the timing of eclipses, 00:21:13.500 --> 00:21:16.019 you name it. So this was another level -up moment. 00:21:16.220 --> 00:21:19.180 A huge one. Before this, Islamic astronomy was 00:21:19.180 --> 00:21:21.559 mostly just translating and preserving older 00:21:21.559 --> 00:21:25.539 texts. After Al -Khwarizmi Zee, it became a true 00:21:25.539 --> 00:21:28.619 research field. Later, astronomers started using 00:21:28.619 --> 00:21:30.740 his methods to check the math of the ancients, 00:21:30.759 --> 00:21:33.599 and they began finding errors. And once you start 00:21:33.599 --> 00:21:35.660 correcting the ancients about the heavens, you 00:21:35.660 --> 00:21:37.339 probably start wondering if they were wrong about 00:21:37.339 --> 00:21:40.140 the earth, too. Exactly. Which leads us to his 00:21:40.140 --> 00:21:43.119 fourth great work, his geography. He wrote the 00:21:43.119 --> 00:21:46.039 Kitab Oryat Alar, the image of the earth. And 00:21:46.039 --> 00:21:48.180 the ancient he was correcting here was the big 00:21:48.180 --> 00:21:50.799 one, Ptolemy. Ptolemy was the gold standard for 00:21:50.799 --> 00:21:53.900 geography for over a thousand years. But his 00:21:53.900 --> 00:21:57.220 maps had some pretty serious problems. Al -Khwarizmi, 00:21:57.359 --> 00:22:00.400 under the patronage of the caliph, oversaw a 00:22:00.400 --> 00:22:03.559 massive state project, a team of 70 geographers, 00:22:03.559 --> 00:22:07.400 to revise and remap the known world. 70 geographers. 00:22:07.400 --> 00:22:09.160 That's a serious budget. What was the biggest 00:22:09.160 --> 00:22:11.269 thing they fixed? The number one error was the 00:22:11.269 --> 00:22:14.289 size of the Mediterranean Sea. Ptolemy had estimated 00:22:14.289 --> 00:22:16.569 the length of the Mediterranean from the Pillars 00:22:16.569 --> 00:22:18.930 of Hercules to the eastern shore to be about 00:22:18.930 --> 00:22:21.710 63 degrees of longitude. And is that wrong? It's 00:22:21.710 --> 00:22:24.230 way, way too long. It stretches Europe and Africa 00:22:24.230 --> 00:22:26.230 out like they're made of taffy. It completely 00:22:26.230 --> 00:22:29.309 discords the shape of the continents. Al -Khwarizmi's 00:22:29.309 --> 00:22:32.619 team recalculated it to about 50 degrees. That's 00:22:32.619 --> 00:22:35.980 a massive correction, more than 20%. It is. The 00:22:35.980 --> 00:22:38.519 modern value is about 42 degrees, so he wasn't 00:22:38.519 --> 00:22:41.019 perfect, but he was so much closer than the Greeks, 00:22:41.140 --> 00:22:43.299 he got the scale of the world much more correct. 00:22:43.579 --> 00:22:45.279 And I read something about the oceans that really 00:22:45.279 --> 00:22:48.420 struck me. Ptolemy thought the Indian Ocean was 00:22:48.420 --> 00:22:52.460 a lake. That's right. In Ptolemy's world, the 00:22:52.460 --> 00:22:54.700 Indian Ocean and the Atlantic were depicted as 00:22:54.700 --> 00:22:57.710 giant... landlocked seas. They were surrounded 00:22:57.710 --> 00:23:00.890 by unknown lands, terra incognita. Which is such 00:23:00.890 --> 00:23:02.970 a confining worldview. It means you're trapped. 00:23:03.130 --> 00:23:05.009 There's nowhere else to go. It means there is 00:23:05.009 --> 00:23:07.849 no sea route around Africa. It means the world 00:23:07.849 --> 00:23:10.890 is fundamentally a closed system. Al -Khwarizmi 00:23:10.890 --> 00:23:13.309 corrected this. In his work, he depicted them 00:23:13.309 --> 00:23:16.230 as open bodies of water. And that's a total paradigm 00:23:16.230 --> 00:23:19.170 shift. If the ocean is open, you can sail it. 00:23:19.210 --> 00:23:21.730 You can explore it. You can trade across it. 00:23:21.809 --> 00:23:24.049 It completely changes the economic and political 00:23:24.049 --> 00:23:26.230 imagination of the world. And what's so cool 00:23:26.230 --> 00:23:29.390 is that even though the original maps from his 00:23:29.390 --> 00:23:32.210 book were lost to history, we still have his 00:23:32.210 --> 00:23:35.289 data. Just the raw numbers. Yes. The book contains 00:23:35.289 --> 00:23:38.930 a list of 2 ,402 coordinates. Just pages and 00:23:38.930 --> 00:23:41.269 pages of latitudes and longitudes for cities, 00:23:41.390 --> 00:23:44.230 mountains, rivers. And in the 20th century... 00:23:44.480 --> 00:23:47.059 A scholar named Hubert Donick plugged all those 00:23:47.059 --> 00:23:49.700 numbers into a computer to reconstruct the map. 00:23:49.839 --> 00:23:52.319 Wow. And when you see it, it looks recognizable. 00:23:52.319 --> 00:23:54.400 You can see the coastline of India, the Mediterranean. 00:23:54.640 --> 00:23:57.079 It looks like our world, but seen through the 00:23:57.079 --> 00:23:59.339 mathematical lens of the 9th century. It's amazing. 00:23:59.500 --> 00:24:01.299 He's fixing the map of the earth, the map of 00:24:01.299 --> 00:24:03.779 the heavens. He's fixing the legal code. I even 00:24:03.779 --> 00:24:05.960 saw he did work on the Jewish calendar. He did. 00:24:06.200 --> 00:24:08.339 He wrote a separate treatise on the Hebrew calendar 00:24:08.339 --> 00:24:13.000 called Risalafi Istiklash Tarek Ayahud. He calculated 00:24:13.000 --> 00:24:15.299 the metonic cycle, that's the 19 -year cycle 00:24:15.299 --> 00:24:17.599 used to align the lunar and solar calendars, 00:24:17.660 --> 00:24:20.140 and determined the rules for when the first day 00:24:20.140 --> 00:24:22.529 of the month of Tishrei would fall. That just 00:24:22.529 --> 00:24:24.690 speaks to his incredible intellectual curiosity. 00:24:25.069 --> 00:24:27.910 Here he is, an Orthodox Muslim working for the 00:24:27.910 --> 00:24:30.930 caliph, but he's diving deep into Hebrew timekeeping, 00:24:31.170 --> 00:24:34.609 Indian numbers, Greek geometry. He really didn't 00:24:34.609 --> 00:24:36.230 care where the truth came from, did he? He was 00:24:36.230 --> 00:24:38.630 the ultimate pragmatist. If a tool worked, he 00:24:38.630 --> 00:24:41.410 used it. If a number system was better, he adopted 00:24:41.410 --> 00:24:44.130 it. And that open, synthetic attitude is what 00:24:44.130 --> 00:24:45.890 ultimately saved this knowledge for the rest 00:24:45.890 --> 00:24:48.240 of the world. So let's talk about that survival, 00:24:48.460 --> 00:24:50.980 that transmission, because Baghdad, well, Baghdad 00:24:50.980 --> 00:24:53.460 has a rough few centuries coming up. The Mongols 00:24:53.460 --> 00:24:56.279 sack the city in 1258. The House of Wisdom is 00:24:56.279 --> 00:24:59.420 destroyed. The Tigris River supposedly runs black 00:24:59.420 --> 00:25:01.859 with the ink of all the books thrown into it. 00:25:01.920 --> 00:25:04.140 How do we know any of this? We got incredibly 00:25:04.140 --> 00:25:07.430 lucky. Before the destruction... the knowledge 00:25:07.430 --> 00:25:09.829 had already leaked out. In the 12th century, 00:25:09.910 --> 00:25:12.190 there was a massive translation movement in Europe, 00:25:12.289 --> 00:25:15.349 specifically in Spain. Right, because much of 00:25:15.349 --> 00:25:17.329 Spain was under Muslim rule for a long time. 00:25:17.349 --> 00:25:19.450 It was a cultural bridge. Toledo, especially, 00:25:19.650 --> 00:25:23.559 was a hub where Christian... Muslim and Jewish 00:25:23.559 --> 00:25:26.240 scholars all mixed. And you had these ambitious 00:25:26.240 --> 00:25:28.579 European scholars, guys like Robert of Chester 00:25:28.579 --> 00:25:31.799 and Adelard of Bath, both Englishmen, traveling 00:25:31.799 --> 00:25:34.380 to Spain specifically to hunt for these Arabic 00:25:34.380 --> 00:25:37.180 manuscripts. It's a reverse intellectual commute. 00:25:37.339 --> 00:25:39.180 We usually think of knowledge flowing from Europe 00:25:39.180 --> 00:25:41.559 outwards. Here you have Englishmen going to Spain 00:25:41.559 --> 00:25:44.059 to translate a Persian's book written in Arabic 00:25:44.059 --> 00:25:46.240 so they can learn how to do basic math back home. 00:25:46.380 --> 00:25:48.819 And when Robert of Chester translated Al -Jab 00:25:48.819 --> 00:25:52.500 into Latin around 1145, it just... Just, it exploded. 00:25:52.799 --> 00:25:55.119 It became the principal mathematics textbook 00:25:55.119 --> 00:25:58.019 in the new European universities. For how long? 00:25:58.099 --> 00:25:59.980 Until the 16th century. Wait, say that again? 00:26:00.180 --> 00:26:04.900 For 400 years. That is just, it's almost impossible 00:26:04.900 --> 00:26:06.599 to wrap your head around. That's like us today 00:26:06.599 --> 00:26:08.940 using a science textbook written in the early 00:26:08.940 --> 00:26:12.380 1600s. It just shows you how completely foundational 00:26:12.380 --> 00:26:16.039 and revolutionary his work was. You literally 00:26:16.039 --> 00:26:18.460 could not do the advanced science of the Renaissance 00:26:18.460 --> 00:26:21.369 without it. You don't get Copernicus. You don't 00:26:21.369 --> 00:26:24.250 get Kepler. You certainly don't get Newton without 00:26:24.250 --> 00:26:26.569 Al -Khwarizmi first providing the basic language 00:26:26.569 --> 00:26:28.930 of calculation. And the world has recognized 00:26:28.930 --> 00:26:31.069 this, right? I mean, we talked about his name 00:26:31.069 --> 00:26:34.109 becoming the word algorithm, but there are actual 00:26:34.109 --> 00:26:37.109 physical monuments. There are. There is a crater 00:26:37.109 --> 00:26:39.170 on the far side of the moon named Al -Khwarizmi. 00:26:39.309 --> 00:26:41.309 Which is very fitting for an astronomer. There 00:26:41.309 --> 00:26:43.150 are a couple of asteroids named after him. There 00:26:43.150 --> 00:26:45.990 are statues of him in his ancestral homeland 00:26:45.990 --> 00:26:49.170 of Uzbekistan, where he's a national hero. And 00:26:49.170 --> 00:26:52.809 even one in Madrid. But I think his real monument 00:26:52.809 --> 00:26:55.269 is invisible. What do you mean by that? I mean 00:26:55.269 --> 00:26:57.109 the layer of abstraction that he placed over 00:26:57.109 --> 00:27:00.150 the entire world. Explain that idea. Before him, 00:27:00.250 --> 00:27:03.130 math was tied to the ground. It was about counting 00:27:03.130 --> 00:27:05.930 sheep or measuring a physical field. It was concrete. 00:27:06.910 --> 00:27:08.690 Alcorizmi was the one who built a layer above 00:27:08.690 --> 00:27:11.710 that. A layer of pure symbols, of pure logic. 00:27:11.990 --> 00:27:15.190 Thing and root and square. He separated the software 00:27:15.190 --> 00:27:17.509 from the hardware. That is the perfect analogy. 00:27:18.039 --> 00:27:21.019 He separated the logical software from the physical 00:27:21.019 --> 00:27:23.920 hardware of the world. He was the first to show, 00:27:24.039 --> 00:27:26.920 in a systematic way, that you can understand 00:27:26.920 --> 00:27:29.339 and manipulate the world not by moving rocks, 00:27:29.480 --> 00:27:33.140 but by manipulating symbols. That is the essence 00:27:33.140 --> 00:27:35.160 of computer science. It's the essence of modern 00:27:35.160 --> 00:27:37.779 physics. It's the essence of everything. It brings 00:27:37.779 --> 00:27:39.980 us right back to that phrase, dixit algorithm. 00:27:40.460 --> 00:27:43.720 Thus spake algorithm. It really is a provocative 00:27:43.720 --> 00:27:46.400 thought to end on then. If those books hadn't 00:27:46.400 --> 00:27:49.339 been translated in the 12th century, if Robert 00:27:49.339 --> 00:27:51.460 of Chester had decided to stay home in England, 00:27:51.700 --> 00:27:54.099 would we even have had a digital revolution? 00:27:54.519 --> 00:27:57.099 It's the great what if of scientific history. 00:27:57.359 --> 00:27:59.819 We might still be using the abacus. We might 00:27:59.819 --> 00:28:01.619 still be stuck with Roman numerals struggling 00:28:01.619 --> 00:28:04.660 to calculate simple interest on a loan. The incredible 00:28:04.660 --> 00:28:06.900 acceleration of human progress over the last 00:28:06.900 --> 00:28:09.859 500 years depends so heavily on these synthesizers. 00:28:10.059 --> 00:28:12.799 These unique people who can stand at a crossroads 00:28:12.799 --> 00:28:15.160 take disconnected ideas from different cultures 00:28:15.160 --> 00:28:17.859 and forge them into a single, powerful, usable 00:28:17.859 --> 00:28:20.119 tool. So the next time you open your laptop, 00:28:20.359 --> 00:28:22.519 or you get frustrated with an algorithm that 00:28:22.519 --> 00:28:25.000 feeds you the wrong song, or, God forbid, you 00:28:25.000 --> 00:28:27.839 actually have to solve for X. Maybe just take 00:28:27.839 --> 00:28:30.740 a second to nod to the librarian from 9th century 00:28:30.740 --> 00:28:33.619 Baghdad. Muhammad ibn Musa al -Khwarizmi. The 00:28:33.619 --> 00:28:35.299 man who wrote the source code for the modern 00:28:35.299 --> 00:28:37.559 world. Thanks for diving deep with us. We'll 00:28:37.559 --> 00:28:38.279 catch you on the next one.