WEBVTT 00:00:00.000 --> 00:00:02.379 Welcome back to the Deep Dive. You've brought 00:00:02.379 --> 00:00:05.219 us a truly monumental stack of sources today, 00:00:05.379 --> 00:00:08.699 and it's all focused on a figure who often feels, 00:00:08.900 --> 00:00:12.019 I don't know, more like a legend than a real 00:00:12.019 --> 00:00:14.890 person. Ellen Turing. He really does. We're not 00:00:14.890 --> 00:00:16.250 just talking about a mathematician here. We're 00:00:16.250 --> 00:00:18.710 talking about really the theoretical architect 00:00:18.710 --> 00:00:22.010 of the entire digital age. Yeah. And it's almost 00:00:22.010 --> 00:00:24.570 impossible to overstate his importance. Turing 00:00:24.570 --> 00:00:27.629 was a polymath in, you know, the truest sense 00:00:27.629 --> 00:00:30.730 of the word. A mathematician, logician, cryptanalyst, 00:00:30.929 --> 00:00:33.049 philosopher, and then later in life, a theoretical 00:00:33.049 --> 00:00:35.789 biologist. Right. But his most immediate impact, 00:00:36.090 --> 00:00:38.210 the thing we have to start with, was on the survival 00:00:38.210 --> 00:00:41.299 of the free world. I think the cognitive scientist 00:00:41.299 --> 00:00:43.759 Douglas Hofstadter framed it perfectly. He said, 00:00:43.799 --> 00:00:46.100 I'm quoting here, we owe much to Alan Turing 00:00:46.100 --> 00:00:48.299 for the fact that we are not under Nazi rule 00:00:48.299 --> 00:00:50.679 today. Wow. OK, that sets the bar incredibly 00:00:50.679 --> 00:00:55.320 high. So our mission today is to, I guess, synthesize 00:00:55.320 --> 00:00:57.380 the timeline of that genius. We need to trace 00:00:57.380 --> 00:01:01.530 this trajectory of his mind from. creating these 00:01:01.530 --> 00:01:04.450 abstract theories in an ivory tower to his role, 00:01:04.549 --> 00:01:07.370 saving millions of lines in world war two. And 00:01:07.370 --> 00:01:10.799 then finally to the tragic, just. agonizing irony 00:01:10.799 --> 00:01:13.719 of how the country he saved later turned on him. 00:01:13.819 --> 00:01:16.459 Exactly. And I think we can structure this deep 00:01:16.459 --> 00:01:18.560 dive around what you could call the three pillars 00:01:18.560 --> 00:01:21.640 of his genius. They really define his core identity. 00:01:21.959 --> 00:01:25.060 First, formalizing the concept of the algorithm 00:01:25.060 --> 00:01:27.439 with what we now call the universal Turing machine. 00:01:27.760 --> 00:01:30.560 Second, designing the mechanical and crucially 00:01:30.560 --> 00:01:33.640 the statistical methods that cracked the enigma 00:01:33.640 --> 00:01:36.159 cipher, the ultra intelligence. Right. And third, 00:01:36.239 --> 00:01:38.900 creating the foundational blueprint for the stored 00:01:39.079 --> 00:01:41.560 program computer, the automatic computing engine, 00:01:41.719 --> 00:01:46.519 or ACE. So let's journey back to his beginnings. 00:01:46.719 --> 00:01:49.959 Let's do it. Turing was born in 1912 in Maida 00:01:49.959 --> 00:01:52.079 Vale, London, but under these kind of peculiar 00:01:52.079 --> 00:01:55.260 circumstances where his father, Julius, was serving 00:01:55.260 --> 00:01:57.180 in India with the civil service. Right. And his 00:01:57.180 --> 00:01:59.200 parents were adamant they strongly believed their 00:01:59.200 --> 00:02:01.379 children had to be raised and educated in Britain, 00:02:01.480 --> 00:02:03.719 which, you know, set him up for a very traditional, 00:02:03.799 --> 00:02:06.500 if often conflicting, English education. And 00:02:06.500 --> 00:02:08.300 the signs that he was different, that he was 00:02:08.300 --> 00:02:10.599 exceptional, they were there almost immediately. 00:02:10.840 --> 00:02:13.500 Oh, right away. His headmistress at St. Michael's 00:02:13.500 --> 00:02:16.139 Precatory School saw this unique mind and explicitly 00:02:16.139 --> 00:02:20.120 called him a genius. But then as soon as he enters 00:02:20.120 --> 00:02:22.759 the formal system at Sherbourne School, you know, 00:02:22.759 --> 00:02:25.800 at age 13, that genius immediately starts to 00:02:25.800 --> 00:02:27.680 clash with tradition. Sherbourne at the time 00:02:27.680 --> 00:02:31.740 was what? deeply invested in the classics. Latin 00:02:31.740 --> 00:02:35.199 Greek. All of it. Latin Greek, history. The whole 00:02:35.199 --> 00:02:38.240 focus was on rhetoric and the traditional humanities, 00:02:38.300 --> 00:02:40.759 not the hard sciences that just fascinated Turing. 00:02:40.939 --> 00:02:43.280 So his interests were seen as a problem. Precisely. 00:02:43.280 --> 00:02:45.960 His dedication to, you know, these unauthorized 00:02:45.960 --> 00:02:48.460 self -directed science experiments and deep mathematical 00:02:48.460 --> 00:02:51.780 puzzles, it put him constantly at odds with the 00:02:51.780 --> 00:02:54.379 schoolmasters. His brilliance was seen more as 00:02:54.379 --> 00:02:57.219 a distraction than a virtue. It got so bad that 00:02:57.219 --> 00:02:59.280 the headmaster actually expressed this genuine 00:02:59.280 --> 00:03:01.539 worry, fearing that Turing might fall between 00:03:01.539 --> 00:03:04.379 two stools. Meaning what exactly? Meaning he'd 00:03:04.379 --> 00:03:06.400 failed to become a proper classical scholar, 00:03:06.520 --> 00:03:08.800 but also failed to succeed academically because 00:03:08.800 --> 00:03:11.240 he just wouldn't conform. It's an incredible 00:03:11.240 --> 00:03:13.860 thing to say about a genius. It speaks volumes 00:03:13.860 --> 00:03:16.199 that even with that deliberate discouragement, 00:03:16.400 --> 00:03:19.979 his aptitude just broke through anyway. We read 00:03:19.979 --> 00:03:22.900 that by 1927, he was already tackling advanced 00:03:22.900 --> 00:03:25.530 mathematical problems on his own. on his own 00:03:25.530 --> 00:03:27.590 without the benefit of formal instruction he 00:03:27.590 --> 00:03:29.669 was even solving problems that needed a grasp 00:03:29.669 --> 00:03:32.270 of elementary calculus which he hadn't been taught 00:03:32.270 --> 00:03:35.759 and that's just the beginning At age 16, he encounters 00:03:35.759 --> 00:03:38.000 Albert Einstein's work. Yeah, and the sources 00:03:38.000 --> 00:03:40.280 highlight this really astonishing example of 00:03:40.280 --> 00:03:43.240 his intuitive leap. Just from reading the text, 00:03:43.479 --> 00:03:45.740 he was able to deduce the fundamental questions 00:03:45.740 --> 00:03:48.900 Einstein was posing about the limits of Newton's 00:03:48.900 --> 00:03:51.120 laws of motion. Questions the textbook didn't 00:03:51.120 --> 00:03:53.219 even state. Exactly. He wasn't just processing 00:03:53.219 --> 00:03:56.259 information. He was seeing the next step, the 00:03:56.259 --> 00:03:59.099 deeper problem underneath. But before that intellectual 00:03:59.099 --> 00:04:01.919 journey could really mature, his life was just 00:04:01.919 --> 00:04:04.639 completely upended. by a deeply personal tragedy. 00:04:05.000 --> 00:04:06.939 We have to talk about his relationship with Christopher 00:04:06.939 --> 00:04:10.580 Morecambe at Sherbourne. We do. It was, by all 00:04:10.580 --> 00:04:12.879 accounts, an all -consuming relationship for 00:04:12.879 --> 00:04:15.500 him. Biographers often describe it as his first 00:04:15.500 --> 00:04:18.300 love. They were intellectual kindred spirits. 00:04:18.600 --> 00:04:22.500 They shared a passion for science, math. Science, 00:04:22.500 --> 00:04:25.379 mathematics, astronomy. Morecambe was probably 00:04:25.379 --> 00:04:28.319 the only person at Sherbourne who truly understood 00:04:28.319 --> 00:04:30.860 and appreciated Turing's mind on its own terms. 00:04:31.160 --> 00:04:34.290 So the loss, then. When Morecambe died so suddenly 00:04:34.290 --> 00:04:37.370 in February 1930, must have been just devastating. 00:04:37.709 --> 00:04:39.889 It was shattering. Morecambe died from complications 00:04:39.889 --> 00:04:42.990 of bovine tuberculosis, which he probably contracted 00:04:42.990 --> 00:04:46.430 years earlier from infected milk. And Turing, 00:04:46.610 --> 00:04:49.430 reeling, he tried to cope by intellectualizing 00:04:49.430 --> 00:04:52.110 the loss, just pouring himself entirely into 00:04:52.110 --> 00:04:54.370 their shared scientific interests. There's that 00:04:54.370 --> 00:04:56.149 poignant letter he wrote to Morecambe's mother, 00:04:56.290 --> 00:04:59.050 Frances. It's heartbreaking. He vows to put as 00:04:59.050 --> 00:05:01.149 much energy, if not as much interest, into their 00:05:01.149 --> 00:05:03.139 shared work as if Christopher were still there. 00:05:03.279 --> 00:05:05.160 He believed that was the tribute Morcombe would 00:05:05.160 --> 00:05:06.899 have wanted. And what's fascinating is how that 00:05:06.899 --> 00:05:09.899 grief seems to have, I don't know, redirected 00:05:09.899 --> 00:05:11.899 his whole philosophical compass, especially on 00:05:11.899 --> 00:05:14.480 the concept of mind and matter. Yeah, that loss 00:05:14.480 --> 00:05:17.740 was a major catalyst. It pushed him toward atheism 00:05:17.740 --> 00:05:20.560 and materialism. He had previously held this 00:05:20.560 --> 00:05:22.660 belief, you see it in his letters, in the idea 00:05:22.660 --> 00:05:25.160 of a spirit surviving the body and finding a 00:05:25.160 --> 00:05:27.660 new body sooner or later. But the reality of 00:05:27.660 --> 00:05:30.689 Morcombe's death changed that. the sudden brutal 00:05:30.689 --> 00:05:33.689 reality of it seems to have focused his mind 00:05:33.689 --> 00:05:36.829 away from metaphysics and toward the purely scientific 00:05:36.829 --> 00:05:39.569 seeking explanations in the mechanics of the 00:05:39.569 --> 00:05:42.730 material world it demanded a scientific framework 00:05:42.730 --> 00:05:46.110 for how ideas could persist which led him really 00:05:46.110 --> 00:05:49.069 directly toward the idea of computation and that 00:05:49.069 --> 00:05:52.810 framework arrives in his 1936 paper on computable 00:05:52.810 --> 00:05:54.829 numbers. This is the paper with the foundation 00:05:54.829 --> 00:05:56.810 of the Turing machine. He wrote it right after 00:05:56.810 --> 00:05:58.910 getting a fellowship at King's College, Cambridge. 00:05:59.189 --> 00:06:01.589 He did. And it's a slightly amusing historical 00:06:01.589 --> 00:06:04.290 footnote that his dissertation, which proved 00:06:04.290 --> 00:06:06.589 a version of the central limit theorem, was later 00:06:06.589 --> 00:06:08.290 found to have already been proven by someone 00:06:08.290 --> 00:06:10.550 else years earlier. Oh, so he wasn't the first. 00:06:10.769 --> 00:06:13.610 Not on that specific theorem, no. But his fellowship 00:06:13.610 --> 00:06:16.230 was secured based on the sheer originality of 00:06:16.230 --> 00:06:18.569 his methodology. The real breakthrough, though, 00:06:18.589 --> 00:06:21.680 came in that 1936 paper. It was published right 00:06:21.680 --> 00:06:24.540 after Alonzo Church's work on the same problem. 00:06:24.660 --> 00:06:27.319 Right, on the question of decidability in mathematics. 00:06:27.759 --> 00:06:30.620 But where Church used the really abstract language 00:06:30.620 --> 00:06:34.199 of lambda calculus, Turing introduced this concrete, 00:06:34.360 --> 00:06:37.019 formal, hypothetical device. Okay, let's pause 00:06:37.019 --> 00:06:38.439 there because the difference between those two 00:06:38.439 --> 00:06:41.560 approaches is so critical. What made the Turing 00:06:41.560 --> 00:06:43.939 machine... and not Church's lambda calculus, 00:06:44.259 --> 00:06:47.480 the intuitive jump -off point for modern computers? 00:06:47.839 --> 00:06:49.600 That's a great question because mathematically 00:06:49.600 --> 00:06:52.420 they both define the same class of computable 00:06:52.420 --> 00:06:54.360 functions. That's the Church -Turing thesis. 00:06:54.759 --> 00:06:58.220 But Church's lambda calculus, it approaches computability 00:06:58.220 --> 00:07:00.779 through formal logic, manipulating functions. 00:07:00.819 --> 00:07:04.540 It's purely abstract. And Turing's was... Mechanical. 00:07:04.620 --> 00:07:07.379 He provided a mechanical, almost physical analogy. 00:07:07.620 --> 00:07:10.180 He imagined a machine that followed simple, finite 00:07:10.180 --> 00:07:12.819 rules, reading and writing symbols on an infinitely 00:07:12.819 --> 00:07:15.240 long strip of tape. So the genius wasn't just 00:07:15.240 --> 00:07:17.480 the logic. It was the embodiment of the logic 00:07:17.480 --> 00:07:19.899 in a machine you could actually picture. Exactly. 00:07:20.139 --> 00:07:22.600 The Turing machine immediately gave people the 00:07:22.600 --> 00:07:25.259 conceptual blueprint for a physical device that 00:07:25.259 --> 00:07:28.120 could perform any calculation. And within that, 00:07:28.199 --> 00:07:31.060 he proposed the single most important concept 00:07:31.060 --> 00:07:34.810 of all. The universal Turing machine. The universal 00:07:34.810 --> 00:07:37.610 machine. Yeah. What's the fundamental idea there 00:07:37.610 --> 00:07:39.730 that makes it more than just a fancy calculator? 00:07:40.129 --> 00:07:42.069 Well, a standard machine is designed to do one 00:07:42.069 --> 00:07:45.389 specific thing, say, multiply two numbers. The 00:07:45.389 --> 00:07:47.610 universal machine is a machine that could perform 00:07:47.610 --> 00:07:51.209 the task of any other Turing machine. How? Simply 00:07:51.209 --> 00:07:53.389 by reading the other machine's program description 00:07:53.389 --> 00:07:56.209 from its tape. So instead of needing a thousand 00:07:56.209 --> 00:07:58.730 different specialized machines, you only need 00:07:58.730 --> 00:08:01.029 one machine, which can be reprogrammed over and 00:08:01.029 --> 00:08:02.990 over again. That is the conceptual foundation 00:08:02.990 --> 00:08:06.069 of the modern stored program computer. The software 00:08:06.069 --> 00:08:08.410 is separate from the hardware. Absolutely. The 00:08:08.410 --> 00:08:10.209 universal Turing machine provided that conceptual 00:08:10.209 --> 00:08:12.889 link between abstract math and physical reality. 00:08:13.110 --> 00:08:15.389 It basically solved the philosophical problem 00:08:15.389 --> 00:08:17.689 of what computation actually is. And the paper 00:08:17.689 --> 00:08:19.449 did something else, something equally profound. 00:08:19.920 --> 00:08:22.279 It did. It established the limits of computation 00:08:22.279 --> 00:08:24.639 by tackling Hilbert's and Scheiding's problem 00:08:24.639 --> 00:08:26.939 or the decision problem. And this is where we 00:08:26.939 --> 00:08:29.139 get the famous halting problem. Right. Turing 00:08:29.139 --> 00:08:31.000 proved that there are fundamental mathematical 00:08:31.000 --> 00:08:34.080 questions that an algorithm simply cannot decide, 00:08:34.360 --> 00:08:38.080 specifically the halting problem. There is no 00:08:38.080 --> 00:08:40.620 universal algorithm that can look at any given 00:08:40.620 --> 00:08:43.840 computer program and determine in a finite amount 00:08:43.840 --> 00:08:45.960 of time whether that program will eventually 00:08:45.960 --> 00:08:48.899 finish or just run forever in an infinite loop. 00:08:49.200 --> 00:08:51.879 So in one paper, he defines the entire potential 00:08:51.879 --> 00:08:53.899 of computation, everything that can be calculated. 00:08:54.179 --> 00:08:56.879 And at the same time, he defines the fundamental 00:08:56.879 --> 00:09:00.179 unshakable boundary of what cannot. That is the 00:09:00.179 --> 00:09:02.779 ultimate so was of this single paper. John von 00:09:02.779 --> 00:09:04.639 Neumann, when he was designing America's first 00:09:04.639 --> 00:09:06.559 computers after the war, he acknowledged that 00:09:06.559 --> 00:09:08.559 the entire conceptual framework of the modern 00:09:08.559 --> 00:09:12.220 computer was owed directly to Turing's 1936 paper. 00:09:12.480 --> 00:09:15.360 It stands as arguably the most influential single 00:09:15.360 --> 00:09:17.919 mathematical paper of the 20th century. And we 00:09:17.919 --> 00:09:20.159 transition now from those abstract limits of 00:09:20.159 --> 00:09:23.899 calculation to the massive real world computation 00:09:23.899 --> 00:09:27.450 needed to crack the German war machine. Turing's 00:09:27.450 --> 00:09:29.990 theoretical knowledge immediately becomes the 00:09:29.990 --> 00:09:32.289 world's most critical military asset. Right. 00:09:32.429 --> 00:09:34.529 He starts working for the government common cipher 00:09:34.529 --> 00:09:38.490 school, GCNCS, part time in 1938 and reports 00:09:38.490 --> 00:09:42.350 full time on September 4th, 1939, the day after 00:09:42.350 --> 00:09:45.090 Britain declares war. The transition from King's 00:09:45.090 --> 00:09:48.190 College fellow to wartime cryptanalyst was immediate. 00:09:48.409 --> 00:09:50.629 Immediate and incredibly demanding. And critically, 00:09:50.830 --> 00:09:54.470 his work was cloaked in absolute secrecy. Like 00:09:54.470 --> 00:09:56.570 everyone at Bletchley Park, he signed the Official 00:09:56.570 --> 00:09:59.169 Secrets Act, with the condition that his silence 00:09:59.169 --> 00:10:01.789 had to continue indefinitely after the war ended. 00:10:01.970 --> 00:10:04.690 Which explains the decades of historical anonymity 00:10:04.690 --> 00:10:06.570 and contributes to the ultimate tragedy we'll 00:10:06.570 --> 00:10:09.110 get to later. But his first task was the Enigma 00:10:09.110 --> 00:10:12.080 Machine. What made that thing so fiendishly difficult 00:10:12.080 --> 00:10:15.399 to crack? Well, the German Enigma used this complex 00:10:15.399 --> 00:10:18.299 system of rotors and a plug board. The number 00:10:18.299 --> 00:10:20.320 of possible settings, the combination of rotor 00:10:20.320 --> 00:10:22.179 order, ring settings, plug board connections. 00:10:22.399 --> 00:10:24.799 It was just astronomical. We're talking numbers 00:10:24.799 --> 00:10:27.179 that are hard to even imagine. I mean, the basic 00:10:27.179 --> 00:10:29.440 three rotor Enigma had something on the order 00:10:29.440 --> 00:10:33.120 of 10 to the 19 possible states. Checking every... 00:10:33.450 --> 00:10:35.490 Possibility manually was just utterly impossible. 00:10:35.889 --> 00:10:38.850 And the four -rotor naval version was even worse, 00:10:39.070 --> 00:10:42.269 reaching 10 to the 22. Yeah, that's more than 00:10:42.269 --> 00:10:45.570 grains of sand on many beaches. So how did Turing 00:10:45.570 --> 00:10:48.230 even start to approach bringing those numbers 00:10:48.230 --> 00:10:51.269 down to a manageable size? His solution, the 00:10:51.269 --> 00:10:54.409 bomb, was an electromechanical machine, a huge 00:10:54.409 --> 00:10:57.870 improvement on a pre -war Polish design. And 00:10:57.870 --> 00:11:00.110 its genius, which he specified within weeks of 00:11:00.110 --> 00:11:02.750 arriving, was based on exploiting a fundamental... 00:11:02.730 --> 00:11:05.490 weakness of the Enigma machine. Which was? An 00:11:05.490 --> 00:11:07.529 encoded letter could never be the same as the 00:11:07.529 --> 00:11:09.850 original letter. An A could never be enciphered 00:11:09.850 --> 00:11:12.389 as an A. Ah, okay. So the bomb didn't try to 00:11:12.389 --> 00:11:14.169 find the solution. It tried to find the settings 00:11:14.169 --> 00:11:16.230 that could possibly be the solution. Exactly. 00:11:16.389 --> 00:11:18.889 The core of the bomb's function was the logical 00:11:18.889 --> 00:11:21.429 principle of contradiction. Cryptanalysts would 00:11:21.429 --> 00:11:24.639 first get a crib. a fragment of probable plaintext 00:11:24.639 --> 00:11:26.720 they suspected might be in the message. Like 00:11:26.720 --> 00:11:29.120 a weather report or hail Hitler or something? 00:11:29.340 --> 00:11:32.720 A predictable phrase, exactly. The bomb would 00:11:32.720 --> 00:11:36.179 then run through potential Enigma settings. And 00:11:36.179 --> 00:11:38.399 if a setting caused a contradiction like that 00:11:38.399 --> 00:11:41.220 A turning into an A, that said, it was instantly 00:11:41.220 --> 00:11:43.600 ruled out. It performed thousands of these logical 00:11:43.600 --> 00:11:46.240 deductions per second, just dramatically reducing 00:11:46.240 --> 00:11:48.659 the number of possibilities. But even with this 00:11:48.659 --> 00:11:51.220 groundbreaking machine, we get to a point in 00:11:51.220 --> 00:11:55.679 1941 where progress is being stifled not by complexity, 00:11:55.820 --> 00:11:59.460 but by, well, bureaucracy. Yes. And this is a 00:11:59.460 --> 00:12:02.799 critical moment. By late 1941, the German military 00:12:02.799 --> 00:12:04.779 is increasing message traffic. They're adding 00:12:04.779 --> 00:12:06.799 new procedures. procedures and Bletchley needs 00:12:06.799 --> 00:12:09.720 to move faster. Turing and his colleagues, Gordon 00:12:09.720 --> 00:12:11.860 Welchman, Hugh Alexander, Stuart Milner -Berry, 00:12:11.940 --> 00:12:14.179 they felt they had the scientific answer, but 00:12:14.179 --> 00:12:15.759 they were just critically short of resources. 00:12:16.100 --> 00:12:18.179 Not enough staff, not enough new bombs being 00:12:18.179 --> 00:12:20.179 built. And their internal appeals were just going 00:12:20.179 --> 00:12:22.340 nowhere. So they decided to go around the chain 00:12:22.340 --> 00:12:25.379 of command. They bypassed the entire command 00:12:25.379 --> 00:12:28.120 chain. They wrote a letter directly to Prime 00:12:28.120 --> 00:12:30.799 Minister Winston Churchill. They argued that 00:12:30.799 --> 00:12:32.840 while their requirements in money and staff were 00:12:32.840 --> 00:12:35.240 tiny compared to the overall military budget, 00:12:35.480 --> 00:12:37.360 the assistance they could offer could potentially 00:12:37.360 --> 00:12:40.220 save the entire war effort. And Churchill's response? 00:12:40.600 --> 00:12:43.580 Legendary. And absolutely immediate. Churchill 00:12:43.580 --> 00:12:47.320 wrote the now famous memo, action this day. And 00:12:47.320 --> 00:12:50.279 then he continued, make sure they have all they 00:12:50.279 --> 00:12:52.899 want on extreme priority and report to me that 00:12:52.899 --> 00:12:55.679 this has been done. Wow. That must have cut through 00:12:55.679 --> 00:12:58.960 years of potential bureaucratic delay in a single 00:12:58.960 --> 00:13:01.850 day. Milner -Berry later said that almost from 00:13:01.850 --> 00:13:04.690 that day, the rough ways began miraculously to 00:13:04.690 --> 00:13:06.970 be made smooth. Production scaled up rapidly. 00:13:07.149 --> 00:13:09.169 They had over 200 bombs running by the end of 00:13:09.169 --> 00:13:11.110 the war, providing that constant intelligence 00:13:11.110 --> 00:13:13.669 flow. And Turing himself took on one of the toughest 00:13:13.669 --> 00:13:16.350 challenges at Bletchley, working in Hut 8 on 00:13:16.350 --> 00:13:19.250 the German naval Enigma. Why was the naval code 00:13:19.250 --> 00:13:21.950 so much harder? The naval Enigma used stricter 00:13:21.950 --> 00:13:24.590 security procedures and a much more complex indicator 00:13:24.590 --> 00:13:27.649 system for transmitting the message key. The 00:13:27.649 --> 00:13:29.690 traffic was often sparse, and the consequences 00:13:29.690 --> 00:13:32.129 of failure U -boat attacks in the Atlantic were 00:13:32.129 --> 00:13:34.470 catastrophic. And he tackled this particularly 00:13:34.470 --> 00:13:38.370 difficult problem largely by himself. He did. 00:13:38.509 --> 00:13:41.110 He cracked the essential part of the naval indicator 00:13:41.110 --> 00:13:45.149 system in December 1939. And this led to one 00:13:45.149 --> 00:13:47.129 of his most critical statistical innovations, 00:13:47.389 --> 00:13:51.299 a technique with a very unusual name. Ban Burismas. 00:13:51.299 --> 00:13:53.600 Ban Burismas. It sounds strange. It's one of 00:13:53.600 --> 00:13:56.100 his most underrated contributions because it 00:13:56.100 --> 00:13:58.299 stayed secret for so long. It was a sequential 00:13:58.299 --> 00:14:02.320 statistical technique. To put it simply. It wasn't 00:14:02.320 --> 00:14:05.480 just brute force trial and error. It was a way 00:14:05.480 --> 00:14:07.879 of managing probability based on overlapping 00:14:07.879 --> 00:14:10.740 letters in pairs of messages. So he was quantifying 00:14:10.740 --> 00:14:12.940 uncertainty. Yes. He was assigning numerical 00:14:12.940 --> 00:14:15.539 weights of evidence to potential settings. He 00:14:15.539 --> 00:14:17.879 called the unit of this evidence the ban, which 00:14:17.879 --> 00:14:19.980 is basically a logarithmic measure of probability. 00:14:20.639 --> 00:14:22.639 what we might now call a decibin in information 00:14:22.639 --> 00:14:24.799 theory. So it made the bombs more efficient. 00:14:25.019 --> 00:14:28.100 Drastically. It accelerated the process, made 00:14:28.100 --> 00:14:30.179 the search for the cribs more efficient, and 00:14:30.179 --> 00:14:33.139 cut down the required machine time. The fact 00:14:33.139 --> 00:14:35.179 that his papers on this weren't declassified 00:14:35.179 --> 00:14:39.139 by GCHQ until 2012 tells you just how foundational 00:14:39.139 --> 00:14:42.480 this concept was. In this high -spakes, hyper 00:14:42.480 --> 00:14:45.179 -secret, just mentally exhausting environment, 00:14:45.759 --> 00:14:48.620 Turing developed some legendary quirks. The nickname 00:14:48.620 --> 00:14:51.509 Prof. Oh, he was deeply eccentric. There's the 00:14:51.509 --> 00:14:53.669 famous image of him cycling around Bletchley 00:14:53.669 --> 00:14:56.090 wearing a gas mask. Not because of gas attacks, 00:14:56.289 --> 00:14:58.970 but to ward off hay fever pollen. Yeah. And then 00:14:58.970 --> 00:15:01.289 there was his bicycle. The chain would fall off 00:15:01.289 --> 00:15:03.789 at mathematically predictable intervals. So rather 00:15:03.789 --> 00:15:06.370 than fix it, he calculated precisely how many 00:15:06.370 --> 00:15:08.370 pedal rotations he could get before the break. 00:15:08.509 --> 00:15:11.610 And he would just stop, hop off, manually adjust 00:15:11.610 --> 00:15:14.059 the chain and continue on his way. That is the 00:15:14.059 --> 00:15:16.740 ultimate example of a genius applying a rigorous 00:15:16.740 --> 00:15:18.759 mathematical solution to a simple mechanical 00:15:18.759 --> 00:15:20.799 problem. Exactly. And of course, there's the 00:15:20.799 --> 00:15:23.500 story of the mug chained to the radiator. He 00:15:23.500 --> 00:15:25.940 just decided the only logical solution to a disappearing 00:15:25.940 --> 00:15:28.379 mug was to secure it with a padlock. But beyond 00:15:28.379 --> 00:15:31.580 the quirks, he maintained this incredible physical 00:15:31.580 --> 00:15:35.220 regimen. He was a serious, almost world -class... 00:15:35.500 --> 00:15:38.139 A phenomenally gifted long -distance runner. 00:15:38.320 --> 00:15:41.200 He often ran the 40 miles from Bletchley to London 00:15:41.200 --> 00:15:43.919 for meetings. His marathon time was competitive 00:15:43.919 --> 00:15:47.080 on a global level. He was only 11 minutes slower 00:15:47.080 --> 00:15:50.580 than the 1948 British Olympic silver medalist. 00:15:50.759 --> 00:15:52.759 And his reason for training with that level of 00:15:52.759 --> 00:15:55.679 intensity was so telling. It really was. He said, 00:15:55.840 --> 00:15:58.179 I have such a stressful job that the only way 00:15:58.179 --> 00:16:00.480 I can get it out of my mind is by running hard. 00:16:00.639 --> 00:16:03.940 It's the only way I can get some release. Running 00:16:03.940 --> 00:16:06.039 wasn't just a hobby. for him, it was a critical 00:16:06.039 --> 00:16:09.039 psychological coping mechanism. And his work 00:16:09.039 --> 00:16:11.960 went beyond just Enigma. He also made critical 00:16:11.960 --> 00:16:14.360 contributions to tackling the superior Lorenz 00:16:14.360 --> 00:16:17.519 cipher codenamed Tunney. Right. The Lorenz cipher 00:16:17.519 --> 00:16:20.240 was even more complex, used for high level communications. 00:16:20.460 --> 00:16:24.080 In 1942, Turing devised Turingery, which was 00:16:24.080 --> 00:16:26.179 another statistical technique designed to crack 00:16:26.179 --> 00:16:29.080 the underlying wheel patterns of the Lorenz machine. 00:16:29.259 --> 00:16:31.519 And while others went on to use that foundation 00:16:31.519 --> 00:16:34.100 to build Colossus, the world's first programmable 00:16:34.100 --> 00:16:36.769 digital electronic computer. Turingery provided 00:16:36.769 --> 00:16:39.809 that essential conceptual framework for finding 00:16:39.809 --> 00:16:42.190 the patterns in the first place. And then there 00:16:42.190 --> 00:16:45.529 was Delilah, his attempt at secure voice communications. 00:16:45.990 --> 00:16:49.330 Yes, lay in the war. A portable, secure voice 00:16:49.330 --> 00:16:52.549 scrambler. He managed a successful demonstration, 00:16:53.029 --> 00:16:56.090 famously encrypting and decrypting a recording 00:16:56.090 --> 00:16:59.070 of a Winston Churchill speech. But it was just 00:16:59.070 --> 00:17:01.509 completed too late, and its distance limitations 00:17:01.509 --> 00:17:04.009 made it impractical, so it was never adopted. 00:17:04.670 --> 00:17:06.890 So when we look at the totality of his wartime 00:17:06.890 --> 00:17:10.009 achievements, what is the ultimate verdict from 00:17:10.009 --> 00:17:12.930 the official historians? The official war historian, 00:17:13.329 --> 00:17:15.390 Harry Hinsley, gave the definitive estimate. 00:17:15.690 --> 00:17:18.269 The ultra -intelligence, which was driven by 00:17:18.269 --> 00:17:20.990 Turing's core advances, shortened the war in 00:17:20.990 --> 00:17:23.069 Europe by more than two years. More than two 00:17:23.069 --> 00:17:25.309 years. It's a staggering metric that confirms 00:17:25.309 --> 00:17:27.809 he wasn't just a contributor. He was a central 00:17:27.809 --> 00:17:30.440 pillar of the Allied victory. It's astounding 00:17:30.440 --> 00:17:32.539 that immediately after winning the war, Turing 00:17:32.539 --> 00:17:34.619 just pivots right back to the theory he loved, 00:17:34.759 --> 00:17:37.549 applying his insights to design the future. His 00:17:37.549 --> 00:17:39.849 first post -war project was the blueprint for 00:17:39.849 --> 00:17:42.710 the first stored program computer. From 45 to 00:17:42.710 --> 00:17:45.089 47, he was at the National Physical Laboratory, 00:17:45.450 --> 00:17:48.309 the NPL, and there he delivered the first really 00:17:48.309 --> 00:17:51.569 comprehensive, detailed design for a stored program 00:17:51.569 --> 00:17:54.829 computer, the Automatic Computing Engine, or 00:17:54.829 --> 00:17:57.130 ACE. This was happening around the same time 00:17:57.130 --> 00:17:59.250 as John von Neumann's work in the U .S. It was, 00:17:59.329 --> 00:18:01.690 but the ACE design... was generally considered 00:18:01.690 --> 00:18:04.170 to be far more specific and technically detailed, 00:18:04.410 --> 00:18:07.650 but it got delayed. And here we find this tragic 00:18:07.650 --> 00:18:10.289 irony that ties right back to the secrecy of 00:18:10.289 --> 00:18:12.750 Bletchley Park. The Official Secrets Act. The 00:18:12.750 --> 00:18:15.650 irony is just profound. The act that demanded 00:18:15.650 --> 00:18:18.369 his silence about code breaking now actively 00:18:18.369 --> 00:18:20.970 crippled his peacetime work. When Turing tried 00:18:20.970 --> 00:18:23.369 to explain the rationale for certain design choices, 00:18:23.650 --> 00:18:26.289 why the machine needed a certain speed or how 00:18:26.289 --> 00:18:28.650 it should interact with operators, that knowledge 00:18:28.650 --> 00:18:31.089 came directly from his wartime experience. And 00:18:31.089 --> 00:18:32.990 he couldn't explain the why. He couldn't explain 00:18:32.990 --> 00:18:35.890 why he knew these things. So the NPL administration 00:18:35.890 --> 00:18:38.950 was slow to grasp the novelty and the necessity 00:18:38.950 --> 00:18:41.769 of his design. The delays were just maddening 00:18:41.769 --> 00:18:44.079 for him. So he's designing the future based on 00:18:44.079 --> 00:18:46.079 lessons he's legally forbidden from sharing. 00:18:46.480 --> 00:18:49.480 Exactly. The delays were maddening, and he got 00:18:49.480 --> 00:18:52.039 disillusioned. By the time he left NPL for good, 00:18:52.319 --> 00:18:54.599 they'd only managed to build a scaled -down version, 00:18:54.900 --> 00:18:57.779 the Pilot ACE. Which still proved the concept. 00:18:57.980 --> 00:19:01.240 Oh, absolutely. The Pilot ACE executed its first 00:19:01.240 --> 00:19:05.569 program in May 1950. Even as a smaller version, 00:19:05.769 --> 00:19:08.650 its principles were hugely influential. So in 00:19:08.650 --> 00:19:11.569 1948, Turing joins the University of Manchester. 00:19:11.869 --> 00:19:14.190 He becomes deputy director of the Computing Machine 00:19:14.190 --> 00:19:16.750 Laboratory, working on software for the Manchester 00:19:16.750 --> 00:19:19.410 Mark I. Right, so the focus shifts from pure 00:19:19.410 --> 00:19:21.710 hardware design to the practical challenges of 00:19:21.710 --> 00:19:24.150 programming. He wrote the first programmer's 00:19:24.150 --> 00:19:26.990 manual for the Mark I. He was essentially translating 00:19:26.990 --> 00:19:29.920 the theoretical machine into physical code. And 00:19:29.920 --> 00:19:31.779 while he's in Manchester, we find this wonderful 00:19:31.779 --> 00:19:34.960 anecdote that ties his wartime paranoia to a 00:19:34.960 --> 00:19:38.599 very personal failure of cryptanalysis. The buried 00:19:38.599 --> 00:19:40.839 silver story. It's a classic. It reflects the 00:19:40.839 --> 00:19:43.779 lasting mental toll of the war. In the 40s, he 00:19:43.779 --> 00:19:46.039 got consumed by this fear that Germany might 00:19:46.039 --> 00:19:47.940 invade. The banks would collapse. So he bought 00:19:47.940 --> 00:19:50.740 two massive silver bars. A small fortune. About 00:19:50.740 --> 00:19:53.519 48 ,000 pounds in today's money. He wrapped them 00:19:53.519 --> 00:19:55.779 up and buried them in a wood near Bletchley Park. 00:19:56.250 --> 00:19:59.170 And he didn't just mark the location, he coded 00:19:59.170 --> 00:20:02.430 it. He used cryptography to code the location. 00:20:02.430 --> 00:20:05.329 And later, when he tried to retrieve them, he 00:20:05.329 --> 00:20:07.609 discovered that either the landscape had changed 00:20:07.609 --> 00:20:10.990 or, in a perfect piece of irony, he couldn't 00:20:10.990 --> 00:20:14.150 break his own complex location cipher. He lost 00:20:14.150 --> 00:20:16.529 them forever. Lost them forever. A testament 00:20:16.529 --> 00:20:19.970 to the secrets he was forced to keep. Okay, let's 00:20:19.970 --> 00:20:22.329 jump to the concept that made him famous outside 00:20:22.329 --> 00:20:25.839 of military history. The Turing Test and the 00:20:25.839 --> 00:20:29.160 Foundation of Artificial Intelligence. This was 00:20:29.160 --> 00:20:32.680 his landmark 1950 paper, Computing Machinery 00:20:32.680 --> 00:20:35.119 and Intelligence. This paper just changed the 00:20:35.119 --> 00:20:37.240 whole conversation. Instead of asking the loaded 00:20:37.240 --> 00:20:39.779 question, can machines think, which he just dismissed 00:20:39.779 --> 00:20:42.180 as being too vague, he proposed an operational 00:20:42.180 --> 00:20:45.359 substitute, the imitation game. What we now call 00:20:45.359 --> 00:20:47.200 the Turing Test. Can you walk us through it? 00:20:47.319 --> 00:20:49.940 Sure. The test involves three participants, a 00:20:49.940 --> 00:20:52.259 human interrogator, another human, and a machine. 00:20:52.869 --> 00:20:54.750 The interrogator communicates with the other 00:20:54.750 --> 00:20:57.569 two only through text, like a chat. If the interrogator 00:20:57.569 --> 00:20:59.730 can't reliably tell the machine apart from the 00:20:59.730 --> 00:21:02.049 human... Then the machine passes. It passes. 00:21:02.250 --> 00:21:04.390 And Turing suggested we should then be willing 00:21:04.390 --> 00:21:07.130 to call that machine intelligent. But what's 00:21:07.130 --> 00:21:09.369 so insightful is the development strategy he 00:21:09.369 --> 00:21:11.970 proposed. He didn't suggest programming an adult 00:21:11.970 --> 00:21:14.329 genius. That's the brilliant part that's often 00:21:14.329 --> 00:21:17.009 overlooked. He argued that trying to simulate 00:21:17.009 --> 00:21:19.910 a fully formed adult mind was too difficult. 00:21:20.150 --> 00:21:22.710 Instead, he proposed that developers should create 00:21:22.710 --> 00:21:25.230 a relatively simple program that simulates a 00:21:25.230 --> 00:21:28.150 child's mind, a machine child, and then subject 00:21:28.150 --> 00:21:30.309 that program to a rigorous course of education. 00:21:30.730 --> 00:21:33.750 The learning process, he believed, was the key. 00:21:33.950 --> 00:21:36.190 It's astonishing that this is still central to 00:21:36.190 --> 00:21:39.579 AI discussions today. and we see a reverse application 00:21:39.579 --> 00:21:42.460 of his test every single time we log in online. 00:21:42.890 --> 00:21:46.450 We do. The TPCA chest, completely automated public 00:21:46.450 --> 00:21:48.670 Turing test to tell computers and humans apart, 00:21:48.789 --> 00:21:52.089 is a direct inverse application. Its sole purpose 00:21:52.089 --> 00:21:54.430 is to prove that you are the human and not the 00:21:54.430 --> 00:21:56.730 sophisticated computer. We can't leave this section 00:21:56.730 --> 00:21:58.970 without talking about Turochamp, his chest program. 00:21:59.250 --> 00:22:01.150 It gives us one of the most endearing images 00:22:01.150 --> 00:22:03.789 of early computing struggles. Turochamp was developed 00:22:03.789 --> 00:22:06.690 by Turing and his colleague D .G. Champernown 00:22:06.690 --> 00:22:10.640 in 1948. It was a theoretical program, an algorithm 00:22:10.640 --> 00:22:13.039 written down with rules for piece values, board 00:22:13.039 --> 00:22:15.700 evaluation, and so on. But they had no physical 00:22:15.700 --> 00:22:17.740 machine that could actually run it. And when 00:22:17.740 --> 00:22:19.940 they finally tried to run it on the Ferranti 00:22:19.940 --> 00:22:23.779 Mark I in 1952, it was still too primitive. So 00:22:23.779 --> 00:22:26.839 Turing did the only logical thing. He became 00:22:26.839 --> 00:22:29.859 the processor. He ran the TuraChamp program manually. 00:22:30.119 --> 00:22:32.200 He would flip through the pages of the algorithm, 00:22:32.380 --> 00:22:34.839 calculate the outcomes of potential moves according 00:22:34.839 --> 00:22:37.400 to the program's rules, and carry out the instructions 00:22:37.400 --> 00:22:39.839 on a chessboard. How long did that take per move? 00:22:40.099 --> 00:22:43.279 About half an hour for every single move. A monumental 00:22:43.279 --> 00:22:45.700 commitment to proving a concept. He eventually 00:22:45.700 --> 00:22:48.240 lost the game to a colleague, but the point was 00:22:48.240 --> 00:22:50.519 made. Garry Kasparov later reviewed the game 00:22:50.519 --> 00:22:53.039 and confirmed the algorithm played a recognizable 00:22:53.039 --> 00:22:56.200 game of chess, proving that a rule -based system 00:22:56.200 --> 00:22:59.619 could indeed approach complex human tasks. Just 00:22:59.619 --> 00:23:02.180 when we think we have the measure of him, Turing 00:23:02.180 --> 00:23:06.460 makes this dramatic late career pivot. In 1951, 00:23:06.559 --> 00:23:09.880 he shifts his focus from computing to the mechanics 00:23:09.880 --> 00:23:13.650 of life itself. His final major paper, The Chemical 00:23:13.650 --> 00:23:16.869 Basis of Morphogenesis. It's fascinating. He 00:23:16.869 --> 00:23:19.089 was applying his understanding of complex self 00:23:19.089 --> 00:23:21.730 -organizing systems knowledge from designing 00:23:21.730 --> 00:23:24.750 computers to solve a fundamental biological problem. 00:23:25.569 --> 00:23:27.930 Morphogenesis is the process of how patterns 00:23:27.930 --> 00:23:30.710 and shapes develop. Essentially, why do zebras 00:23:30.710 --> 00:23:33.069 have stripes and leopards have spots? And he 00:23:33.069 --> 00:23:35.490 proposed a completely counterintuitive explanation. 00:23:36.400 --> 00:23:38.640 based on chemistry. He proposed the reaction 00:23:38.640 --> 00:23:41.599 -diffusion system. This mathematical model suggests 00:23:41.599 --> 00:23:44.140 that patterns can spontaneously emerge in a completely 00:23:44.140 --> 00:23:46.619 uniform homogenous system if you have two chemicals, 00:23:46.859 --> 00:23:49.559 an activator and an inhibitor, and they diffuse 00:23:49.559 --> 00:23:51.839 across space at different rates. Okay, break 00:23:51.839 --> 00:23:53.700 that down for us. The activator and the inhibitor. 00:23:53.819 --> 00:23:56.700 Right. Chemical A is the activator. It's an autocatalyst, 00:23:56.900 --> 00:23:59.019 meaning when it reacts, it produces more of itself. 00:23:59.339 --> 00:24:02.279 A positive feedback loop. Chemical B is the inhibitor, 00:24:02.319 --> 00:24:04.599 which slows down the production of A, but the 00:24:04.599 --> 00:24:07.059 crucial part is... the diffusion rate. They have 00:24:07.059 --> 00:24:09.339 to be different. Why? If they diffused at the 00:24:09.339 --> 00:24:11.279 same rate, the system would just stay uniform. 00:24:11.759 --> 00:24:15.559 But if the activator A is short range, it diffuses 00:24:15.559 --> 00:24:19.059 slowly, and the inhibitor B is long range, it 00:24:19.059 --> 00:24:21.920 diffuses much faster, then a pattern emerges. 00:24:22.420 --> 00:24:25.019 The activator creates a spot, but the faster 00:24:25.019 --> 00:24:27.380 moving inhibitor moves out and suppresses other 00:24:27.380 --> 00:24:29.799 spots from forming nearby. Which creates a regular 00:24:29.799 --> 00:24:32.549 predictable spacing. A regular predictable spacing. 00:24:32.869 --> 00:24:35.170 It was revolutionary, especially since it was 00:24:35.170 --> 00:24:37.349 published before the structure of DNA was even 00:24:37.349 --> 00:24:40.190 fully understood. His model even predicted phenomena 00:24:40.190 --> 00:24:42.930 that hadn't been observed yet, like oscillating 00:24:42.930 --> 00:24:46.109 chemical reactions. And how seminal is this work 00:24:46.109 --> 00:24:48.910 in modern biology? It's extremely seminal. It 00:24:48.910 --> 00:24:51.069 showed that self -organization could be explained 00:24:51.069 --> 00:24:53.589 by local chemical interactions creating a global 00:24:53.589 --> 00:24:56.990 structure. Today, it's used across biology. Professor 00:24:56.990 --> 00:24:59.769 James Murray used Turing principles to model 00:24:59.769 --> 00:25:01.960 the specific space basing of spots on cat fur. 00:25:02.099 --> 00:25:04.200 It's linked to everything from the growth of 00:25:04.200 --> 00:25:06.640 feathers to the branching in our lungs. So has 00:25:06.640 --> 00:25:09.160 this theory been proven in a real living context? 00:25:09.579 --> 00:25:11.160 That's the most exciting recent development. 00:25:11.420 --> 00:25:14.880 In 2023, researchers published a detailed verification. 00:25:15.339 --> 00:25:18.539 They conducted an experiment using growing chia 00:25:18.539 --> 00:25:21.779 seeds in a uniform layer. By manipulating moisture 00:25:21.779 --> 00:25:24.460 levels, which acted as the diffusion factors, 00:25:24.920 --> 00:25:27.880 they were able to reliably reproduce Turing -type 00:25:27.880 --> 00:25:31.349 patterns using living vegetation. Wow. A real 00:25:31.349 --> 00:25:33.829 world confirmation 70 years later. A definitive 00:25:33.829 --> 00:25:37.269 one. It's a difficult and essential transition 00:25:37.269 --> 00:25:40.210 to move from the sheer intellectual triumph of 00:25:40.210 --> 00:25:42.930 that last paper to the stark reality of the national 00:25:42.930 --> 00:25:45.170 tragedy that followed. We have to address his 00:25:45.170 --> 00:25:47.990 conviction for gross indecency. The legal background 00:25:47.990 --> 00:25:49.750 is just crucial to understanding the cruelty 00:25:49.750 --> 00:25:52.369 of the time. In the UK, homosexual acts were 00:25:52.369 --> 00:25:55.029 serious criminal offenses under an 1885 law. 00:25:55.529 --> 00:25:57.589 This was the discriminatory framework that ultimately 00:25:57.589 --> 00:25:59.869 shattered Turing's life. And the actual events 00:25:59.869 --> 00:26:01.730 that led to his prosecution didn't even start 00:26:01.730 --> 00:26:04.150 with a morality sting. It started with a simple 00:26:04.150 --> 00:26:07.829 crime. That's right. In late 1951, Turing, who 00:26:07.829 --> 00:26:10.529 was 39, began an intimate relationship with a 00:26:10.529 --> 00:26:13.470 19 -year -old man, Arnold Murray. The catastrophe 00:26:13.470 --> 00:26:17.150 began in January 1952 when Turing's home was 00:26:17.150 --> 00:26:20.259 burgled. When he reported it, Murray was implicated. 00:26:20.519 --> 00:26:22.799 And during the police investigation, Turing, 00:26:22.980 --> 00:26:25.359 who was always brutally honest. He just admitted 00:26:25.359 --> 00:26:27.799 it. He felt compelled to admit that he had a 00:26:27.799 --> 00:26:30.099 sexual relationship with Murray. And that admission 00:26:30.099 --> 00:26:32.240 led directly to charges against both of them 00:26:32.240 --> 00:26:35.400 for gross indecency. Yes. He was facing a society 00:26:35.400 --> 00:26:38.000 that just didn't distinguish between a consensual 00:26:38.000 --> 00:26:40.720 private relationship and a criminal act. He was 00:26:40.720 --> 00:26:42.779 advised to plead guilty, which he did in March 00:26:42.779 --> 00:26:46.039 1952. And he was given this terrible choice by 00:26:46.039 --> 00:26:49.119 the judge. two years in prison, or one year of 00:26:49.119 --> 00:26:51.200 probation if he underwent hormonal treatment. 00:26:51.380 --> 00:26:53.589 What we now call chemical castration. Correct. 00:26:53.710 --> 00:26:55.690 Turing, terrified of what prison time would do 00:26:55.690 --> 00:26:58.250 to his mind, chose the probation. For a year, 00:26:58.250 --> 00:27:00.549 he received regular injections of stillburstrol, 00:27:00.650 --> 00:27:02.990 a synthetic estrogen. The treatment had devastating 00:27:02.990 --> 00:27:05.769 physical consequences, impotence, the growth 00:27:05.769 --> 00:27:08.309 of breast tissue. It was a state -mandated violation 00:27:08.309 --> 00:27:10.509 of his body. There's that heartbreaking quote 00:27:10.509 --> 00:27:12.710 from a letter he wrote during this time. Yeah, 00:27:12.789 --> 00:27:14.750 he tried to maintain a clinical distance, writing, 00:27:14.910 --> 00:27:17.309 No doubt I shall emerge from it all a different 00:27:17.309 --> 00:27:20.009 man, but quite who I've not found out. It's just 00:27:20.009 --> 00:27:23.250 a chilling statement of profound forced change. 00:27:23.569 --> 00:27:26.009 And the professional damage was immediate, especially 00:27:26.009 --> 00:27:29.450 considering the timing. This was the height of 00:27:29.450 --> 00:27:32.730 the Cold War. The Cambridge Five spy defections 00:27:32.730 --> 00:27:36.089 had caused massive paranoia. Anyone identified 00:27:36.089 --> 00:27:38.829 as homosexual was flagged as a potential security 00:27:38.829 --> 00:27:41.589 risk on the assumption they could be blackmailed. 00:27:41.609 --> 00:27:44.069 So Turing, the man who provided the most critical 00:27:44.069 --> 00:27:46.869 intelligence of the war, suddenly loses his security 00:27:46.869 --> 00:27:50.069 clearance. Instantly. He's barred from any consultancy 00:27:50.069 --> 00:27:53.549 work for GCHQ. He was suddenly viewed not as 00:27:53.549 --> 00:27:56.190 a genius, but as a security threat to the very 00:27:56.190 --> 00:27:58.569 nation he had saved. An unbelievable betrayal. 00:27:58.950 --> 00:28:01.730 It was. He was marginalized, monitored, and cut 00:28:01.730 --> 00:28:03.750 off from the work that was his passion. And this 00:28:03.750 --> 00:28:06.450 period of immense humiliation and trauma brings 00:28:06.450 --> 00:28:09.990 us to his controversial death in 1954. He died 00:28:09.990 --> 00:28:14.809 on June 7, 1954, at his home, aged 41. The cause 00:28:14.809 --> 00:28:17.640 was cyanide poisoning. The inquest ruled it a 00:28:17.640 --> 00:28:20.380 suicide. And the enduring image is that of the 00:28:20.380 --> 00:28:22.980 half -eaten apple found beside his bed, which 00:28:22.980 --> 00:28:25.059 was speculated to have been dipped in cyanide. 00:28:25.140 --> 00:28:27.599 But the suicide verdict is heavily disputed. 00:28:27.640 --> 00:28:30.200 There are significant arguments against it. The 00:28:30.200 --> 00:28:32.960 philosopher Jack Copeland noted the autopsy findings 00:28:32.960 --> 00:28:35.380 were more consistent with cyanide inhalation 00:28:35.380 --> 00:28:38.900 rather than ingestion. Turing had a gold electroplating 00:28:38.900 --> 00:28:41.779 apparatus in his spare room, which used potassium 00:28:41.779 --> 00:28:44.039 cyanide, and he was often careless with it. And 00:28:44.039 --> 00:28:46.359 his demeanor just before his death didn't really 00:28:46.359 --> 00:28:48.279 align with someone planning to end his life. 00:28:48.400 --> 00:28:51.039 Not at all. His nephew, Dermot Turing, and others 00:28:51.039 --> 00:28:53.259 said he'd endured the treatment with good humor. 00:28:53.460 --> 00:28:56.299 He was making cheerful plans. Crucially, he had 00:28:56.299 --> 00:28:58.460 left a list of tasks he intended to complete 00:28:58.460 --> 00:29:00.400 when he returned to his office after the holiday. 00:29:00.660 --> 00:29:02.640 That kind of planning is highly inconsistent 00:29:02.640 --> 00:29:05.500 with suicide. So some biographers even suggest 00:29:05.500 --> 00:29:07.660 he might have staged it. That's the theory from 00:29:07.660 --> 00:29:10.960 his biographer, Andrew Hodges. He theorized Turing 00:29:10.960 --> 00:29:13.319 might have deliberately staged the scene, the 00:29:13.319 --> 00:29:15.619 famous apple, to look like a science accident, 00:29:15.819 --> 00:29:18.819 a casual mistake specifically to protect his 00:29:18.819 --> 00:29:21.779 mother, who was deeply religious and never accepted 00:29:21.779 --> 00:29:23.940 the suicide verdict. The shadow of this injustice 00:29:23.940 --> 00:29:27.319 hung over his legacy for decades until the 21st 00:29:27.319 --> 00:29:29.160 century brought this campaign for redemption. 00:29:29.400 --> 00:29:32.000 It began in earnest with a public petition in 00:29:32.000 --> 00:29:35.059 2009. Prime Minister Gordon Brown responded, 00:29:35.400 --> 00:29:38.059 releasing an official public apology on behalf 00:29:38.059 --> 00:29:40.559 of the government for the appalling way he was 00:29:40.559 --> 00:29:43.539 treated. He called it utterly unfair. But an 00:29:43.539 --> 00:29:45.940 apology isn't legal absolution. That required 00:29:45.940 --> 00:29:48.980 years of further campaigning. Right. Led by figures 00:29:48.980 --> 00:29:51.859 like MP John Leach, supported by Stephen Hawking, 00:29:52.039 --> 00:29:55.119 the campaign sought a royal pardon. It was granted 00:29:55.119 --> 00:29:58.460 by Queen Elizabeth II in December 2013. Which 00:29:58.460 --> 00:30:01.000 is exceptionally rare. Only the fourth such pardon 00:30:01.000 --> 00:30:03.460 granted since World War II. It was a rare use 00:30:03.460 --> 00:30:05.759 of royal prerogative to correct a moral historical 00:30:05.759 --> 00:30:08.279 wrong. And the final act of societal redress 00:30:08.279 --> 00:30:12.609 was the Alan Turing Law in 2017. Yes. The law, 00:30:12.670 --> 00:30:15.509 informally named in his honor, went far beyond 00:30:15.509 --> 00:30:18.930 just Turing. It retroactively pardoned or exonerated 00:30:18.930 --> 00:30:20.789 thousands of other men and women who had been 00:30:20.789 --> 00:30:23.650 convicted under those same historical laws. It 00:30:23.650 --> 00:30:25.910 was a monumental acknowledgement that the state's 00:30:25.910 --> 00:30:32.309 failure was systemic. From the abstract power 00:30:32.309 --> 00:30:35.250 of the universal machine, through his role shortening 00:30:35.250 --> 00:30:37.950 World War II by two years, to his late -life 00:30:37.950 --> 00:30:40.710 pioneering work, we are looking at a singular 00:30:40.710 --> 00:30:43.779 intellectual force. His contribution spans every 00:30:43.779 --> 00:30:46.619 major field of 20th century science. He left 00:30:46.619 --> 00:30:48.960 a seminal foundational paper in every field he 00:30:48.960 --> 00:30:51.339 touched. The recognition is finally visible. 00:30:51.519 --> 00:30:54.019 His portrait is on the 50 pound note released 00:30:54.019 --> 00:30:56.799 on his birthday in 2021. He was the essential 00:30:56.799 --> 00:30:59.319 architect of the digital world we all now inhabit. 00:30:59.519 --> 00:31:02.180 And yet that triumph is forever intertwined with 00:31:02.180 --> 00:31:04.460 the tragic fact that the very nation he protected 00:31:04.460 --> 00:31:06.980 subjected him to a state mandated persecution 00:31:06.980 --> 00:31:09.059 that contributed directly to his early death. 00:31:09.200 --> 00:31:12.240 That tension persists. Just last year, Defense 00:31:12.240 --> 00:31:14.519 Secretary Ben Wallace suggested Turing should 00:31:14.519 --> 00:31:16.720 get a permanent statue on the fourth plinth of 00:31:16.720 --> 00:31:19.160 Trafalgar Square, calling him probably the greatest 00:31:19.160 --> 00:31:21.880 war hero. He's being championed as a national 00:31:21.880 --> 00:31:24.380 hero and a national martyr at the same time. 00:31:24.519 --> 00:31:26.500 So given the scale of his achievements and the 00:31:26.500 --> 00:31:28.599 scale of the injustice, this deep dive really 00:31:28.599 --> 00:31:31.400 leaves you with this question. When you look 00:31:31.400 --> 00:31:33.940 back at his life, where do you draw the line 00:31:33.940 --> 00:31:36.039 between the genius who helped us win the war 00:31:36.039 --> 00:31:39.059 and the individual that nation failed in peacetime? 00:31:39.630 --> 00:31:42.289 What part of his extraordinary, tragic story 00:31:42.289 --> 00:31:45.329 should history remember most clearly? And maybe, 00:31:45.450 --> 00:31:47.730 what would the landscape of science, computing, 00:31:47.849 --> 00:31:50.710 and even biology look like today if that genius 00:31:50.710 --> 00:31:53.029 had been permitted to live out his full potential 00:31:53.029 --> 00:31:55.750 without prejudice? We'll leave you to ponder 00:31:55.750 --> 00:31:57.930 those profound questions. Thank you for joining 00:31:57.930 --> 00:31:58.910 us for this deep dive.