WEBVTT 00:00:00.000 --> 00:00:02.040 Welcome to the Deep Dives, where we take a monumental 00:00:02.040 --> 00:00:04.980 stack of history, science, and philosophy and 00:00:04.980 --> 00:00:07.299 distill it into the knowledge you need, fast. 00:00:07.599 --> 00:00:10.480 Today, we're embarking on one of the most astonishing 00:00:10.480 --> 00:00:13.560 journeys through 17th century intellectual history. 00:00:13.859 --> 00:00:17.539 We are unpacking the life of Blaise Pascal. French 00:00:17.539 --> 00:00:20.280 polymath who, well, fundamentally shaped the 00:00:20.280 --> 00:00:22.679 modern world in mathematics, physics, computing, 00:00:22.800 --> 00:00:25.660 and literature. And he did it all before his 00:00:25.660 --> 00:00:28.640 life was tragically cut short at the age of 39. 00:00:28.980 --> 00:00:31.940 39 years. I mean, it's barely enough time for 00:00:31.940 --> 00:00:33.979 most of us to figure out a career path. And yet 00:00:33.979 --> 00:00:37.380 Pascal was an inventor, a physicist who disproved 00:00:37.380 --> 00:00:39.880 ancient philosophy, a profound religious writer, 00:00:40.000 --> 00:00:42.969 and a literary revolutionary. all at once. So 00:00:42.969 --> 00:00:45.450 our mission today with this huge stack of sources 00:00:45.450 --> 00:00:48.710 is to unpack how one person could lay the groundwork 00:00:48.710 --> 00:00:52.740 for modern calculus, probability theory, public 00:00:52.740 --> 00:00:55.140 transit, and computer engineering. And then after 00:00:55.140 --> 00:00:58.200 all that, pivot his immense genius entirely toward 00:00:58.200 --> 00:01:00.420 theology. It's an incredible story. And what's 00:01:00.420 --> 00:01:02.539 so fascinating is that his genius was never just 00:01:02.539 --> 00:01:05.159 abstract, was it? Not at all. His origins were 00:01:05.159 --> 00:01:08.319 very practical. His father, Etienne Pascal, was 00:01:08.319 --> 00:01:10.299 part of the administrative class, the noblesse 00:01:10.299 --> 00:01:12.939 de robe. He was a royal tax commissioner. Ah, 00:01:12.939 --> 00:01:14.980 so that environment, that world of numbers and 00:01:14.980 --> 00:01:17.579 administration. Exactly. It was steeped in the, 00:01:17.719 --> 00:01:21.540 um... the excruciating reality of manual, often 00:01:21.540 --> 00:01:24.859 chaotic calculations. And that's what directly 00:01:24.859 --> 00:01:27.560 pushed Pascal toward finding a better way, a 00:01:27.560 --> 00:01:30.140 radical automated solution. It really is the 00:01:30.140 --> 00:01:32.040 ultimate example of necessity birthing invention. 00:01:32.459 --> 00:01:35.299 We're going to see how financial chaos in 17th 00:01:35.299 --> 00:01:38.500 century France literally drove him to invent 00:01:38.500 --> 00:01:40.500 the mechanical calculator. And how a challenge 00:01:40.500 --> 00:01:42.700 from an aristocratic gambler sparked the entire 00:01:42.700 --> 00:01:45.299 field of propodacty. It's a recurring theme, 00:01:45.400 --> 00:01:47.959 isn't it? intensely practical problems leading 00:01:47.959 --> 00:01:50.859 to these huge world -changing abstract solutions. 00:01:51.200 --> 00:01:53.219 We'll start with his astonishing beginnings as 00:01:53.219 --> 00:01:56.120 a child prodigy, trace his path through his inventions, 00:01:56.340 --> 00:01:58.280 then move to his foundational physics experiments 00:01:58.280 --> 00:02:00.700 that really settled the centuries -old debate 00:02:00.700 --> 00:02:03.519 over the vacuum. And finally, we'll get into 00:02:03.519 --> 00:02:05.900 the dramatic religious conversion that birthed 00:02:05.900 --> 00:02:08.860 two of the most influential literary and philosophical 00:02:08.860 --> 00:02:12.080 masterpieces in the French language. Okay, so 00:02:12.080 --> 00:02:14.479 let's start at the beginning. Pascal was born 00:02:14.479 --> 00:02:17.300 in Clermont -Ferrand in 1623. His mother died 00:02:17.300 --> 00:02:19.939 when he was just three, and his father, Etienne, 00:02:20.159 --> 00:02:22.780 made this really pivotal decision. He decided 00:02:22.780 --> 00:02:24.960 to educate Blaise and his two sisters himself 00:02:24.960 --> 00:02:28.180 when they all moved to Paris in 1631. And the 00:02:28.180 --> 00:02:30.680 sources are all very clear on this. Young Pascal 00:02:30.680 --> 00:02:33.659 had an extraordinary, almost alarming intellectual 00:02:33.659 --> 00:02:37.000 ability, especially for math. But the defining 00:02:37.000 --> 00:02:39.479 anecdote of his childhood is the story of restriction. 00:02:40.400 --> 00:02:42.919 His father... who was a decent mathematician 00:02:42.919 --> 00:02:45.280 himself, actually tried to keep math away from 00:02:45.280 --> 00:02:47.979 him. Which sounds completely counterintuitive. 00:02:48.139 --> 00:02:50.080 Right. Why would you do that? Was he afraid his 00:02:50.080 --> 00:02:52.199 son would become, I don't know, too specialized 00:02:52.199 --> 00:02:54.819 too early? It seems to be a bit of that. Etienne 00:02:54.819 --> 00:02:57.599 had this idea that a proper classical education 00:02:57.599 --> 00:03:00.479 language as literature had to come first. So 00:03:00.479 --> 00:03:02.460 he actually removed all the math textbooks from 00:03:02.460 --> 00:03:04.379 the house. He locked them away. Locked them away 00:03:04.379 --> 00:03:07.300 and refused to even discuss the subject. The 00:03:07.300 --> 00:03:10.199 plan was he'd teach Blaise math when he turned 00:03:10.199 --> 00:03:13.419 15. But a mind like that, well, it finds a way, 00:03:13.479 --> 00:03:15.800 doesn't it? It absolutely does. The story goes 00:03:15.800 --> 00:03:18.800 that Blaze, who was only about 12... just started 00:03:18.800 --> 00:03:21.560 figuring it out on his own. He was using charcoal 00:03:21.560 --> 00:03:24.719 on a tile floor. Drawing shapes. Drawing shapes, 00:03:24.979 --> 00:03:27.599 making up his own names for them, like bar for 00:03:27.599 --> 00:03:30.599 a line and round for a circle. And by the time 00:03:30.599 --> 00:03:33.539 his father found him, he had independently rediscovered 00:03:33.539 --> 00:03:36.620 Euclid's first 32 propositions. Without any books. 00:03:36.719 --> 00:03:38.759 Without any books. He had essentially reverse 00:03:38.759 --> 00:03:41.300 engineered the fundamentals of geometry up to 00:03:41.300 --> 00:03:43.199 the point of proving that the angles in a triangle 00:03:43.199 --> 00:03:46.300 add up to two right angles. All on his own. That 00:03:46.300 --> 00:03:50.020 is just... It's a hallmark of a mind operating 00:03:50.020 --> 00:03:51.840 on a completely different level. He didn't just 00:03:51.840 --> 00:03:54.300 learn geometry. He recreated it. And that led 00:03:54.300 --> 00:03:57.180 just four years later to his first serious mathematical 00:03:57.180 --> 00:04:01.360 work, the essay on conics. In 1640, he was 16. 00:04:01.599 --> 00:04:04.139 16 years old and publishing serious mathematics. 00:04:04.379 --> 00:04:07.240 What was the core idea in that work? The cornerstone 00:04:07.240 --> 00:04:09.439 was something he called the mystic hexagram. 00:04:09.699 --> 00:04:13.000 We know it today as Pascal's theorem. And what 00:04:13.000 --> 00:04:15.580 does that state? It's an incredibly elegant proof. 00:04:15.960 --> 00:04:19.019 Basically, if you draw any random hexagon inside 00:04:19.019 --> 00:04:21.480 a conic section, a circle, an ellipse, whatever, 00:04:21.740 --> 00:04:24.240 the three points where the opposite sides intersect 00:04:24.240 --> 00:04:27.639 will always lie on a single straight line. The 00:04:27.639 --> 00:04:30.220 Pascal line. It's one of those things that sounds 00:04:30.220 --> 00:04:34.660 complex, but is visually just... Yeah. perfect 00:04:34.660 --> 00:04:36.680 once you see it drawn out. And the reaction at 00:04:36.680 --> 00:04:39.120 the time tells you everything. The great Rene 00:04:39.120 --> 00:04:41.639 Descartes. The father of modern philosophy. He 00:04:41.639 --> 00:04:44.160 was so astounded he was convinced that Pascal's 00:04:44.160 --> 00:04:46.560 father had written it. He simply couldn't believe 00:04:46.560 --> 00:04:48.879 a 16 -year -old was capable of that kind of original 00:04:48.879 --> 00:04:51.220 thought. So he basically accused him of fraud. 00:04:51.439 --> 00:04:53.759 Pretty much. When he was assured it really was 00:04:53.759 --> 00:04:57.329 the son's work. Descartes gave this backhanded 00:04:57.329 --> 00:04:59.350 compliment, saying it was impressive, but that 00:04:59.350 --> 00:05:01.610 other related topics would scarcely occur to 00:05:01.610 --> 00:05:03.769 a 16 -year -old child. Incredible. So he's already 00:05:03.769 --> 00:05:05.449 fighting for recognition just because he's so 00:05:05.449 --> 00:05:07.949 far ahead of his age. And from this very abstract 00:05:07.949 --> 00:05:10.509 theoretical brilliance, his journey takes a very 00:05:10.509 --> 00:05:13.029 practical turn. And that brings us to the financial 00:05:13.029 --> 00:05:15.509 crisis the Pascal family faced. Right, because 00:05:15.509 --> 00:05:17.129 they were initially quite comfortable when they 00:05:17.129 --> 00:05:19.949 moved to Paris. Very. Etienne had sold his official 00:05:19.949 --> 00:05:23.589 position for over 65 ,000 livres, a huge sum. 00:05:24.029 --> 00:05:27.649 But then, in 1638, Cardinal Richelieu, who was 00:05:27.649 --> 00:05:29.649 desperate for money for the Thirty Years' War, 00:05:29.870 --> 00:05:32.430 defaulted on government bonds. And that just 00:05:32.430 --> 00:05:34.350 wiped them out. It wiped out most of their wealth. 00:05:34.410 --> 00:05:37.029 Their fortune plummeted. It was a crippling blow. 00:05:37.350 --> 00:05:40.290 So to recover, Etienne gets a new job. He's appointed 00:05:40.290 --> 00:05:42.550 the king's commissioner of taxes in Rouen in 00:05:42.550 --> 00:05:46.810 1639, and Rouen was a mess. Tax revolts, chaotic 00:05:46.810 --> 00:05:49.389 records. And his job was to sort through it all. 00:05:49.449 --> 00:05:51.689 We're talking endless, grueling calculations. 00:05:52.189 --> 00:05:54.149 Just endless. He was completely overwhelmed. 00:05:54.509 --> 00:05:57.329 And this is where Blaze, seeing his father struggling, 00:05:57.629 --> 00:06:00.430 applies his mind to the problem. This is the 00:06:00.430 --> 00:06:03.170 origin of the Pascaline, around 1642. He's not 00:06:03.170 --> 00:06:07.149 even 19 yet. It's not. And he builds this mechanical 00:06:07.149 --> 00:06:10.699 calculator. It was a box with a series of geared 00:06:10.699 --> 00:06:13.300 wheels. You'd dial in the numbers, and the machine 00:06:13.300 --> 00:06:15.779 would perform addition and subtraction, even 00:06:15.779 --> 00:06:18.040 handling the carryover automatically. It's one 00:06:18.040 --> 00:06:20.939 of the very first mechanical calculators in history. 00:06:21.240 --> 00:06:24.500 The other was Wilhelm Schickard's, but his was 00:06:24.500 --> 00:06:27.699 lost in a fire. So Pascal's is the one that survives 00:06:27.699 --> 00:06:30.560 and evolves. He spent a decade perfecting it, 00:06:30.620 --> 00:06:33.560 building about 20 finished machines. He even 00:06:33.560 --> 00:06:35.879 presented one to Christina, queen of Sweden. 00:06:36.120 --> 00:06:38.670 But here's the friction point. If it was such 00:06:38.670 --> 00:06:41.310 a pioneering invention, why didn't it take off? 00:06:41.529 --> 00:06:44.170 Well, it was a mix of things. First, it was mechanically 00:06:44.170 --> 00:06:46.709 very complex. It could jam, especially if you 00:06:46.709 --> 00:06:48.670 tried to use it too quickly. And the accountants 00:06:48.670 --> 00:06:50.649 said they were already very fast with their manual 00:06:50.649 --> 00:06:53.730 methods. Exactly. Second, it was a bit cumbersome 00:06:53.730 --> 00:06:56.430 to use. The process wasn't as intuitive as, say, 00:06:56.529 --> 00:06:58.850 an abacus for people who are already trained 00:06:58.850 --> 00:07:01.069 experts. And the third factor, I'm guessing, 00:07:01.170 --> 00:07:04.939 was cost. The cost. It was extraordinarily expensive 00:07:04.939 --> 00:07:08.060 to build and maintain. You could hire a whole 00:07:08.060 --> 00:07:11.040 room of clerks for less. So it failed as a commercial 00:07:11.040 --> 00:07:13.519 product. It didn't become a widespread tool. 00:07:13.699 --> 00:07:16.980 It became what? A status symbol. A sophisticated 00:07:16.980 --> 00:07:19.459 toy and a status symbol for the wealthy elite. 00:07:19.879 --> 00:07:22.899 It was a brilliant technological leap, but the 00:07:22.899 --> 00:07:25.199 world just wasn't economically ready for it. 00:07:25.339 --> 00:07:27.560 It's a classic story in the history of technology. 00:07:27.959 --> 00:07:31.149 You could be right, but right too early. So after 00:07:31.149 --> 00:07:34.449 this foray into mechanical engineering, Pascal's 00:07:34.449 --> 00:07:37.410 work pivots back into abstract mathematics. But 00:07:37.410 --> 00:07:39.829 again, it's triggered by a very practical problem. 00:07:40.089 --> 00:07:42.069 And this time it's not taxes. It's gambling. 00:07:42.250 --> 00:07:45.490 Gambling. In 1654, he starts this now famous 00:07:45.490 --> 00:07:48.009 correspondence with Pierre de Fermat, another 00:07:48.009 --> 00:07:50.290 giant of French mathematics. And the whole thing 00:07:50.290 --> 00:07:52.189 gets started because a guy named Chevalier de 00:07:52.189 --> 00:07:55.029 Marais, an aristocratic gambler, has a couple 00:07:55.029 --> 00:07:57.050 of puzzles he can't solve. And one of them, the 00:07:57.050 --> 00:07:59.290 one that really ignited this new field, was the 00:07:59.290 --> 00:08:01.600 problem of points. OK, can you break down the 00:08:01.600 --> 00:08:04.060 scenario for us? Certainly. Imagine you and I 00:08:04.060 --> 00:08:06.339 are playing a game of coin flips. The first person 00:08:06.339 --> 00:08:08.759 to win five rounds gets the whole prize pot. 00:08:09.019 --> 00:08:11.519 OK. But let's say we have to stop early. I've 00:08:11.519 --> 00:08:14.100 won four rounds and you've won three. The game's 00:08:14.100 --> 00:08:17.279 not over. How do we divide the prize money fairly? 00:08:17.540 --> 00:08:19.500 The old way was just to divide it based on the 00:08:19.500 --> 00:08:21.560 rounds we'd already won, right? So like a four 00:08:21.560 --> 00:08:24.879 to three ratio. Exactly. And that's wrong. Pascal 00:08:24.879 --> 00:08:27.699 and Fermat's breakthrough was realizing the division 00:08:27.699 --> 00:08:30.439 has to be based on the future. on the probability 00:08:30.439 --> 00:08:32.960 each of us has of winning from that point forward. 00:08:33.159 --> 00:08:35.820 So you calculate all the possible ways the rest 00:08:35.820 --> 00:08:37.740 of the game could play out. Precisely. And that 00:08:37.740 --> 00:08:40.840 correspondence, that back and forth, gave birth 00:08:40.840 --> 00:08:43.720 to the mathematical theory of probability. The 00:08:43.720 --> 00:08:46.980 impact of that is just. It's hard to overstate. 00:08:47.019 --> 00:08:49.240 It goes so far beyond the gambling table. Oh, 00:08:49.240 --> 00:08:51.559 absolutely. The core concept they developed, 00:08:51.740 --> 00:08:54.799 what we call expected value, it's the foundation 00:08:54.799 --> 00:08:58.129 for how we quantify risk and uncertainty. So 00:08:58.129 --> 00:09:00.250 you're talking about insurance, financial markets, 00:09:00.490 --> 00:09:03.269 modern economics. All of it. Actuarial science. 00:09:03.470 --> 00:09:06.350 The roots trace directly back to Pascal and Fermat 00:09:06.350 --> 00:09:08.809 trying to solve a gambler's dilemma in 1654. 00:09:09.110 --> 00:09:10.750 And it also leads some of the groundwork for 00:09:10.750 --> 00:09:12.649 Leibniz and the later development of calculus. 00:09:13.230 --> 00:09:16.789 It did. The focus on infinitesimals and approaching 00:09:16.789 --> 00:09:19.870 limits was a key step. So again, you have a mechanical 00:09:19.870 --> 00:09:22.889 calculator leading towards computing and a gambling 00:09:22.889 --> 00:09:25.370 problem leading towards higher analysis. And 00:09:25.370 --> 00:09:29.049 that same year, 1654, was just incredibly productive 00:09:29.049 --> 00:09:31.409 for him. That's also when he wrote his treatise 00:09:31.409 --> 00:09:33.549 on the arithmetical triangle. Right, the work 00:09:33.549 --> 00:09:36.169 that details what we all know as Pascal's triangle. 00:09:36.509 --> 00:09:38.809 Now, he didn't invent the triangle itself, did 00:09:38.809 --> 00:09:42.080 he? No, the pattern was known for centuries in 00:09:42.080 --> 00:09:46.639 China, India, Persia. Pascal's contribution was 00:09:46.639 --> 00:09:49.419 to systematically explore its properties and 00:09:49.419 --> 00:09:52.000 apply them to his new work on probability. And 00:09:52.000 --> 00:09:54.139 in that same treatise, he did something else. 00:09:54.590 --> 00:09:56.690 something methodologically revolutionary. This 00:09:56.690 --> 00:09:59.669 was the really huge leap. He provided the first 00:09:59.669 --> 00:10:02.409 explicit, formalized statement of the principle 00:10:02.409 --> 00:10:04.809 of mathematical induction. Okay, for those of 00:10:04.809 --> 00:10:05.929 us who haven't thought about that since high 00:10:05.929 --> 00:10:08.110 school, can you give us a simple analogy? Think 00:10:08.110 --> 00:10:10.649 of it like a line of dominoes, an infinite line. 00:10:11.070 --> 00:10:12.690 Mathematical induction is how you prove that 00:10:12.690 --> 00:10:14.909 all the dominoes will fall. You only have to 00:10:14.909 --> 00:10:17.090 do two things. Okay, what's the first? First 00:10:17.090 --> 00:10:19.710 is the base case. You have to prove you can knock 00:10:19.710 --> 00:10:22.379 over the very first domino. that the statement 00:10:22.379 --> 00:10:24.559 is true for the first instance simple enough 00:10:24.559 --> 00:10:26.519 and the second part that's the inductive step 00:10:26.519 --> 00:10:29.379 you have to prove that if any given domino falls 00:10:29.379 --> 00:10:31.720 it will always knock over the next one that if 00:10:31.720 --> 00:10:34.179 the statement is true for some number k it must 00:10:34.179 --> 00:10:37.590 be true for k plus one so If you can knock over 00:10:37.590 --> 00:10:39.909 the first one, and you know each one knocks over 00:10:39.909 --> 00:10:42.649 the next, you've proven it for the entire infinite 00:10:42.649 --> 00:10:45.830 line. Exactly. It's a way to formalize absolute 00:10:45.830 --> 00:10:48.429 certainty in mathematics, which is, as you said, 00:10:48.490 --> 00:10:50.610 incredibly ironic given what else happens in 00:10:50.610 --> 00:10:54.389 1654. Because right at this peak of his mathematical 00:10:54.389 --> 00:10:57.029 powers, he just stops. That's the great pivot. 00:10:57.750 --> 00:11:00.210 1654 is the year of his definitive religious 00:11:00.210 --> 00:11:03.360 conversion, the Night of the Memorial. After 00:11:03.360 --> 00:11:05.440 that, he mostly gave up work in mathematics. 00:11:05.759 --> 00:11:08.039 But not entirely. There's one last kind of bizarre 00:11:08.039 --> 00:11:11.080 mathematical episode a few years later. In 1658. 00:11:11.399 --> 00:11:14.120 And it was prompted by a severe toothache. A 00:11:14.120 --> 00:11:16.940 toothache? He was in agony. And to distract himself 00:11:16.940 --> 00:11:18.559 from the pain, he started thinking about the 00:11:18.559 --> 00:11:21.639 cycloid. That's the curve traced by a point on 00:11:21.639 --> 00:11:24.220 a rolling circle. It was a huge mathematical 00:11:24.220 --> 00:11:26.720 puzzle at the time. And as he's deep in thought... 00:11:26.720 --> 00:11:30.029 His toothache just vanished. Completely. And 00:11:30.029 --> 00:11:32.769 Pascal, being in this new religious frame of 00:11:32.769 --> 00:11:36.470 mind, took it as a heavenly sign. Divine approval 00:11:36.470 --> 00:11:39.590 to keep working on the math problem. Yes. He 00:11:39.590 --> 00:11:42.529 worked furiously and wrote an entire essay on 00:11:42.529 --> 00:11:45.309 the area and volume of the cycloid in just eight 00:11:45.309 --> 00:11:48.590 days. He even proposed a public contest with 00:11:48.590 --> 00:11:51.629 cash prizes to solve related problems. So even 00:11:51.629 --> 00:11:55.009 a brief return to his first passion yielded significant 00:11:55.009 --> 00:11:57.240 results. It did. It showed that the mind was 00:11:57.240 --> 00:11:59.600 still there, even if his focus had shifted heavenward. 00:11:59.720 --> 00:12:02.019 It's just staggering that this same person, at 00:12:02.019 --> 00:12:04.559 the same time, was also revolutionizing our understanding 00:12:04.559 --> 00:12:07.019 of the physical world. I mean, this is the work 00:12:07.019 --> 00:12:08.919 that gave us the scientific unit, the Pascal. 00:12:09.179 --> 00:12:11.299 His physics work was also incredibly practical. 00:12:11.440 --> 00:12:13.720 It led to two inventions we still use every day, 00:12:13.879 --> 00:12:16.919 the syringe and the hydraulic press. The hydraulic 00:12:16.919 --> 00:12:19.190 press is based on Pascal's law, right? Can you 00:12:19.190 --> 00:12:21.769 break that down? Sure. Pascal's law says that 00:12:21.769 --> 00:12:24.509 if you apply pressure to a fluid in a closed 00:12:24.509 --> 00:12:27.610 container, that pressure is transmitted equally 00:12:27.610 --> 00:12:30.669 to every part of the fluid. More importantly, 00:12:30.830 --> 00:12:32.750 the pressure depends on the height of the fluid 00:12:32.750 --> 00:12:35.509 column, not its total weight. And that's how 00:12:35.509 --> 00:12:38.210 you get force multiplication, like in a car jack. 00:12:38.590 --> 00:12:41.090 That's the perfect modern analogy. You apply 00:12:41.090 --> 00:12:44.409 a small force on a small piston, and that pressure 00:12:44.409 --> 00:12:46.929 is transmitted to a much larger piston, which 00:12:46.929 --> 00:12:49.429 magnifies the force and lets you lift a two -ton 00:12:49.429 --> 00:12:52.169 car with ease. And he had this very dramatic 00:12:52.169 --> 00:12:54.450 way of demonstrating this, the Pascal's barrel 00:12:54.450 --> 00:12:57.529 experiment. A fantastic illustration. He took 00:12:57.529 --> 00:12:59.990 a sturdy, water -filled barrel and attached a 00:12:59.990 --> 00:13:02.750 very long, very thin tube to the top. A tube 00:13:02.750 --> 00:13:04.570 that went all the way up to the third story of 00:13:04.570 --> 00:13:06.190 a building? Right, and then he started pouring 00:13:06.190 --> 00:13:09.429 water into just that tiny tube. The volume of 00:13:09.429 --> 00:13:11.789 water he added was minuscule. But the height 00:13:11.789 --> 00:13:13.769 of the water column created immense pressure. 00:13:14.070 --> 00:13:16.470 So much pressure that the barrel burst. It proved 00:13:16.470 --> 00:13:18.509 that pressure depends on height, not volume. 00:13:18.629 --> 00:13:21.409 It was a spectacular way to shatter common sense 00:13:21.409 --> 00:13:24.029 intuition. But his biggest contribution to physics 00:13:24.029 --> 00:13:26.730 was settling a debate that had been raging since 00:13:26.730 --> 00:13:29.769 ancient Greece. The vacuum. This was a battle 00:13:29.769 --> 00:13:33.049 against dogma. The Aristotelian view, which Descartes 00:13:33.049 --> 00:13:36.649 also held, was horror vacuum. Nature abhors a 00:13:36.649 --> 00:13:40.019 vacuum. The belief was that true nothingness 00:13:40.019 --> 00:13:42.620 couldn't exist. Any space had to be filled with 00:13:42.620 --> 00:13:45.220 some kind of invisible matter. But then evangelists 00:13:45.220 --> 00:13:47.639 of Torricelli's experiments with mercury barometers 00:13:47.639 --> 00:13:50.879 started to suggest otherwise. Torricelli's work 00:13:50.879 --> 00:13:53.940 was the spark. Pascal picked it up and ran with 00:13:53.940 --> 00:13:57.620 it. In 1647, he published a paper arguing that 00:13:57.620 --> 00:14:00.120 a true vacuum did exist above the mercury in 00:14:00.120 --> 00:14:02.320 a barometer tube, and it was the weight of the 00:14:02.320 --> 00:14:05.120 air pressing down that held the mercury up. But 00:14:05.120 --> 00:14:07.470 the old guard, the Cartesians... They weren't 00:14:07.470 --> 00:14:09.769 convinced. No, they argued that some invisible 00:14:09.769 --> 00:14:12.389 vapor or substance was filling that space, so 00:14:12.389 --> 00:14:15.029 Pascal needed definitive, irrefutable proof. 00:14:15.350 --> 00:14:18.009 And his hypothesis was brilliantly simple. Just 00:14:18.009 --> 00:14:20.350 beautiful. He reasoned that if air has weight, 00:14:20.450 --> 00:14:22.409 then there must be less of it on top of a mountain 00:14:22.409 --> 00:14:24.990 than at the bottom, so atmospheric pressure should 00:14:24.990 --> 00:14:27.149 decrease as you go up. And he had the perfect 00:14:27.149 --> 00:14:29.830 laboratory right there. The Puy -de -Dôme Mountain. 00:14:29.990 --> 00:14:32.450 The only problem was his own health was terrible. 00:14:32.769 --> 00:14:36.039 He was often too sick to do things himself. So 00:14:36.039 --> 00:14:38.379 he recruited his brother -in -law, Florent Perrier, 00:14:38.600 --> 00:14:42.240 to conduct the experiment in 1648. And the methodology 00:14:42.240 --> 00:14:45.200 they used was so rigorous for its time. It really 00:14:45.200 --> 00:14:47.980 was. Perrier gathered a bunch of credible witnesses, 00:14:48.360 --> 00:14:51.519 prepared two identical barometers, and took a 00:14:51.519 --> 00:14:53.620 baseline reading at the lowest point in town. 00:14:54.220 --> 00:14:56.879 Critically, he left one barometer there as a 00:14:56.879 --> 00:14:59.279 control. To make sure the weather didn't just 00:14:59.279 --> 00:15:02.100 change during the day. Exactly. Then he and his 00:15:02.100 --> 00:15:05.179 party climbed the mountain. Almost 5 ,000 feet. 00:15:05.320 --> 00:15:07.279 And when they got to the summit? The result was 00:15:07.279 --> 00:15:10.120 immediate and decisive. The Mercury column was 00:15:10.120 --> 00:15:12.120 more than three inches lower than it was at the 00:15:12.120 --> 00:15:15.720 base. A huge drop. A massive drop. He repeated 00:15:15.720 --> 00:15:18.120 the experiment five times, all with the same 00:15:18.120 --> 00:15:20.600 result. When he got back down, the Mercury was 00:15:20.600 --> 00:15:22.980 back to its original height. It was conclusive 00:15:22.980 --> 00:15:25.289 proof. The weight of the air was real and the 00:15:25.289 --> 00:15:27.950 vacuum was real. It permanently settled the debate. 00:15:28.190 --> 00:15:30.610 And Pascal immediately replicated it on a smaller 00:15:30.610 --> 00:15:33.309 scale in Paris by carrying a barometer up the 00:15:33.309 --> 00:15:34.990 bell tower of a church and seeing the mercury 00:15:34.990 --> 00:15:38.049 drop. And his response to his critics from this 00:15:38.049 --> 00:15:40.789 period is one of the clearest statements of the 00:15:40.789 --> 00:15:43.330 modern scientific method. It's a fantastic quote 00:15:43.330 --> 00:15:46.509 on falsifiability. He said essentially that for 00:15:46.509 --> 00:15:48.889 a hypothesis to be true, it's not enough that 00:15:48.889 --> 00:15:51.490 all the phenomena fit it. If it leads to something 00:15:51.490 --> 00:15:54.850 that contradicts even a single phenomenon, that's 00:15:54.850 --> 00:15:57.490 enough to prove it's false. Science progresses 00:15:57.490 --> 00:16:01.669 by seeking disproof, not just confirmation. A 00:16:01.669 --> 00:16:04.649 profound idea. And of course, the legacy of all 00:16:04.649 --> 00:16:07.250 this work is the SI unit for pressure, the Pascal. 00:16:07.590 --> 00:16:10.049 Which brings us to that great turning point. 00:16:10.429 --> 00:16:13.409 The same rigorous mind that insisted on empirical 00:16:13.409 --> 00:16:16.110 proof in the physical world is the one that would 00:16:16.110 --> 00:16:18.470 soon turn away from reason in the realm of faith. 00:16:18.730 --> 00:16:20.389 The seeds for that were planted a bit earlier, 00:16:20.450 --> 00:16:23.529 weren't they, in 1646? Yes, during a family crisis. 00:16:23.809 --> 00:16:26.029 His father broke his hip, and the two doctors 00:16:26.029 --> 00:16:28.590 who treated him were devout followers of Jansenism. 00:16:28.769 --> 00:16:30.769 Jansenism. That was a very austere, rigorous 00:16:30.769 --> 00:16:33.169 movement within Catholicism, right? Very much 00:16:33.169 --> 00:16:36.250 so. It stressed human sinfulness and the absolute 00:16:36.250 --> 00:16:39.929 necessity of divine grace for salvation. Pascal 00:16:39.929 --> 00:16:42.490 was deeply influenced by talking with these doctors 00:16:42.490 --> 00:16:45.330 and reading Jansenist works. That was his first 00:16:45.330 --> 00:16:48.009 conversion. But it didn't fully stick at first. 00:16:48.210 --> 00:16:50.350 After his father died, he went through what's 00:16:50.350 --> 00:16:53.809 called his worldly period. And this led to a 00:16:53.809 --> 00:16:56.149 really intense conflict with his sister, Jacqueline, 00:16:56.169 --> 00:16:58.230 who he was very close to. She wanted to join 00:16:58.230 --> 00:17:00.409 the Jansenist convent at Port Royal. She was 00:17:00.409 --> 00:17:04.319 resolute. But Pascal resisted fiercely. He relied 00:17:04.319 --> 00:17:06.880 on her, and he was also deeply suspicious of 00:17:06.880 --> 00:17:09.319 the convent. The sources suggest he felt that 00:17:09.319 --> 00:17:11.559 it had begun to smell like a cult. And the fight 00:17:11.559 --> 00:17:13.240 was over her inheritance, which she had signed 00:17:13.240 --> 00:17:15.339 over to the convent. He eventually gave in, but 00:17:15.339 --> 00:17:17.859 it caused him... immense turmoil and led to a 00:17:17.859 --> 00:17:20.400 period of spiritual isolation which all builds 00:17:20.400 --> 00:17:23.420 up to the main event november 23rd 1654. that 00:17:23.420 --> 00:17:26.539 night between 10 .30 and 12 30 pascal had an 00:17:26.539 --> 00:17:29.339 intense two -hour mystical experience that changed 00:17:29.339 --> 00:17:31.359 him forever and we only know about it because 00:17:31.359 --> 00:17:33.700 of the note he scribbled down the memorial it 00:17:33.700 --> 00:17:36.880 starts with just one word fire and the key line 00:17:36.880 --> 00:17:39.579 rejects the intellectualized god of philosophy 00:17:39.579 --> 00:17:44.140 fire God of Abraham, God of Isaac, God of Jacob, 00:17:44.380 --> 00:17:47.019 not of the philosophers and the scholars. It 00:17:47.019 --> 00:17:49.440 was a direct, overwhelming experience of God. 00:17:49.519 --> 00:17:51.400 And the personal detail of what he did with that 00:17:51.400 --> 00:17:54.200 note is just mind -blowing. It is. He sewed it 00:17:54.200 --> 00:17:57.279 into the lining of his coat. And every time he 00:17:57.279 --> 00:17:59.299 got a new coat, he would unpick the stitches 00:17:59.299 --> 00:18:01.579 and sew it into the new one. No one knew it existed. 00:18:01.900 --> 00:18:04.579 It was a completely private covenant, a secret 00:18:04.579 --> 00:18:07.119 he kept until a servant found it after he died. 00:18:07.440 --> 00:18:09.660 From that point on, his work is almost entirely 00:18:09.660 --> 00:18:12.180 religious. He immediately starts writing his 00:18:12.180 --> 00:18:14.859 first great literary work, The Provincial Letters. 00:18:15.059 --> 00:18:17.019 Which was a blistering attack on something called 00:18:17.019 --> 00:18:19.720 casuistry. What exactly was that? Casuistry was 00:18:19.720 --> 00:18:21.880 a method of moral reasoning, especially popular 00:18:21.880 --> 00:18:23.799 with the Jesuits, that tried to resolve ethical 00:18:23.799 --> 00:18:26.700 dilemmas by applying general principles to very 00:18:26.700 --> 00:18:29.279 specific cases. And Pascal saw this as just a 00:18:29.279 --> 00:18:31.380 way to create moral loopholes. He thought it 00:18:31.380 --> 00:18:33.579 was using complex reasoning to justify moral 00:18:33.579 --> 00:18:36.819 laxity, to excuse sin. and he attacked it with 00:18:36.819 --> 00:18:39.000 devastating effect. The letters were published 00:18:39.000 --> 00:18:41.640 under a pseudonym, and they were brilliant. He 00:18:41.640 --> 00:18:45.119 used humor, mockery, vicious satire. They became 00:18:45.119 --> 00:18:48.019 a masterpiece of French prose. They were so powerful 00:18:48.019 --> 00:18:50.400 that King Louis IV ordered the book to be burned. 00:18:50.539 --> 00:18:53.440 And yet, even the Pope... while publicly condemning 00:18:53.440 --> 00:18:56.579 them, was supposedly privately convinced by Pascal's 00:18:56.579 --> 00:18:58.519 arguments. That's what the sources say. They 00:18:58.519 --> 00:19:00.740 were just that persuasive. And one of the most 00:19:00.740 --> 00:19:03.119 famous quotes comes from these letters, his apology 00:19:03.119 --> 00:19:05.400 for one of them being too long. I have made this 00:19:05.400 --> 00:19:07.700 letter longer than usual only because I have 00:19:07.700 --> 00:19:10.640 not had the time to make it shorter. Iconic line. 00:19:11.109 --> 00:19:14.369 And that leads into his unfinished magnum opus, 00:19:14.390 --> 00:19:17.609 the pensées, or thoughts. This was meant to be 00:19:17.609 --> 00:19:20.210 his great defense of Christianity. An apology. 00:19:20.430 --> 00:19:22.930 And he had a very specific philosophical strategy 00:19:22.930 --> 00:19:26.750 to convert the unbeliever. A brilliant one. He 00:19:26.750 --> 00:19:29.289 planned to trap the reader between two opposing 00:19:29.289 --> 00:19:32.049 philosophies, Pyrrhonism, which is radical skepticism, 00:19:32.230 --> 00:19:34.789 and Stoicism, which is radical self -sufficiency 00:19:34.789 --> 00:19:37.569 through reason. So he would use one to dismantle 00:19:37.569 --> 00:19:40.900 the other. Exactly. He'd use the skeptic Montaigne 00:19:40.900 --> 00:19:43.400 to show the flaws in the Stoic's confidence and 00:19:43.400 --> 00:19:46.140 use the Stoic Epictetus to show the contradictions 00:19:46.140 --> 00:19:49.140 in the skeptic's position. The goal was to drive 00:19:49.140 --> 00:19:52.160 the reader to despair. To show that human reason 00:19:52.160 --> 00:19:55.579 on its own fails when it comes to the big questions. 00:19:55.819 --> 00:19:58.380 And that failure creates the need for a divine 00:19:58.380 --> 00:20:01.420 answer. And within this framework is his most 00:20:01.420 --> 00:20:04.720 famous idea. Pascal's Wager. This is where his 00:20:04.720 --> 00:20:07.440 work on probability theory crashes into his theology. 00:20:07.779 --> 00:20:10.960 He argues that since reason can't prove or disprove 00:20:10.960 --> 00:20:13.660 God's existence, you have to make a bet. You 00:20:13.660 --> 00:20:15.859 bet that God exists or you bet that he doesn't. 00:20:15.900 --> 00:20:18.180 And then you calculate the stakes. If you bet 00:20:18.180 --> 00:20:20.740 on God and you're right, your gain is infinite 00:20:20.740 --> 00:20:23.359 eternal salvation. If you're wrong, your loss 00:20:23.359 --> 00:20:25.460 is finite. A few earthly pleasures. What if you 00:20:25.460 --> 00:20:28.039 bet against God and you're wrong? Your loss is 00:20:28.039 --> 00:20:31.960 infinite. Eternal damnation. So from a purely 00:20:31.960 --> 00:20:34.579 probabilistic standpoint, the only rational bet 00:20:34.579 --> 00:20:37.960 is to believe. The infinite payoff just dominates 00:20:37.960 --> 00:20:40.319 the entire equation. It's a pragmatic argument. 00:20:40.359 --> 00:20:41.799 He's not saying it will make you believe, but 00:20:41.799 --> 00:20:43.619 it gives you a reason to start acting as if you 00:20:43.619 --> 00:20:47.200 do. And this preference for faith over pure reason 00:20:47.200 --> 00:20:50.259 is why he clashed so strongly with Descartes. 00:20:50.420 --> 00:20:53.099 He famously wrote, I cannot forgive Descartes 00:20:53.099 --> 00:20:55.640 because Descartes used God to get his system 00:20:55.640 --> 00:20:58.599 started and then, you know, didn't need God anymore. 00:20:58.720 --> 00:21:01.849 For Pascal. God wasn't a philosophical premise. 00:21:02.029 --> 00:21:03.990 God had to be felt in the heart. Which is all 00:21:03.990 --> 00:21:06.450 captured in that perfect, timeless quote, thought 00:21:06.450 --> 00:21:10.150 number 200. Man is only a reed, the weakest in 00:21:10.150 --> 00:21:13.609 nature, but he is a thinking reed. We are fragile 00:21:13.609 --> 00:21:16.210 and mortal, but our consciousness, our ability 00:21:16.210 --> 00:21:19.049 to think, gives us infinite dignity. It's the 00:21:19.049 --> 00:21:22.049 ultimate summary of human misery and human greatness. 00:21:22.250 --> 00:21:24.509 And even with all this going on, he had one last 00:21:24.509 --> 00:21:27.130 practical invention left in him. One last one. 00:21:27.500 --> 00:21:30.380 In 1661, less than a year before he died, he 00:21:30.380 --> 00:21:32.900 inaugurated one of the world's first public transportation 00:21:32.900 --> 00:21:36.180 systems. The Carousel Saint -Saul in Paris. Horse 00:21:36.180 --> 00:21:38.720 -drawn carriages, like buses, that ran on fixed 00:21:38.720 --> 00:21:41.380 routes for a fixed price of five souls. And he 00:21:41.380 --> 00:21:43.619 established the core principles we still use. 00:21:43.799 --> 00:21:46.980 Fixed route, fixed price, and crucially, a fixed 00:21:46.980 --> 00:21:49.519 schedule. The carriages left on time, even if 00:21:49.519 --> 00:21:52.640 they were empty. That reliability is key. Now, 00:21:52.660 --> 00:21:54.700 like the Pascaline, it wasn't a long -term commercial 00:21:54.700 --> 00:21:58.900 success. The lines closed down by 1675. But the 00:21:58.900 --> 00:22:01.180 concept, the invention of the system of public 00:22:01.180 --> 00:22:04.240 transit, is all his. It's a final testament to 00:22:04.240 --> 00:22:06.940 the sheer breadth of his mind. But his time was 00:22:06.940 --> 00:22:09.279 running out. His lifelong health problems were 00:22:09.279 --> 00:22:12.480 getting much, much worse. And he embraced a severe 00:22:12.480 --> 00:22:15.400 ascetic lifestyle. He came to believe that... 00:22:15.640 --> 00:22:18.220 Sickness is the natural state of Christians and 00:22:18.220 --> 00:22:21.180 often refuse doctors seeing suffering as something 00:22:21.180 --> 00:22:23.660 to be endured. He died in Paris on August 19, 00:22:24.039 --> 00:22:28.019 1662. He was only 39. His last words were, may 00:22:28.019 --> 00:22:30.940 God never abandon me. The autopsy revealed just 00:22:30.940 --> 00:22:33.579 how much he had suffered physically. Grave problems 00:22:33.579 --> 00:22:35.799 with his stomach and other organs, along with 00:22:35.799 --> 00:22:37.799 damage to his brain, which likely caused the 00:22:37.799 --> 00:22:39.980 chronic, debilitating headaches he had his whole 00:22:39.980 --> 00:22:42.559 life. An incredibly short life. But the legacy 00:22:42.559 --> 00:22:45.180 is just immense. His name is everywhere. It really 00:22:45.180 --> 00:22:48.119 is. In science, the Pascal unit of pressure. 00:22:48.319 --> 00:22:50.700 In technology, the Pascal programming language, 00:22:50.920 --> 00:22:53.579 NVIDIA's Pascal microarchitecture. And in culture, 00:22:53.619 --> 00:22:56.039 too. The chameleon in the movie Tangled is named 00:22:56.039 --> 00:22:58.819 Pascal, the otter in Animal Crossing. And just 00:22:58.819 --> 00:23:01.920 last year, in 2023, Pope Francis dedicated an 00:23:01.920 --> 00:23:05.319 entire apostolic letter to him. He remains this 00:23:05.319 --> 00:23:08.480 towering figure, a scientific giant whose ultimate 00:23:08.480 --> 00:23:11.180 conclusions were theological. The man who started 00:23:11.180 --> 00:23:13.160 out trying to help his father with tax ledgers 00:23:13.160 --> 00:23:16.180 ended up systematizing chaos itself with probability 00:23:16.180 --> 00:23:18.960 and then arguing the greatest truths can't be 00:23:18.960 --> 00:23:21.539 calculated at all. It's a remarkable story of 00:23:21.539 --> 00:23:23.980 synthesis. Tax calculations gave us the calculator. 00:23:24.299 --> 00:23:27.039 A gambler's problem gave us probability. A toothache 00:23:27.039 --> 00:23:29.599 gave us a key insight into the psychoid. His 00:23:29.599 --> 00:23:31.740 life was a relentless pursuit of truth wherever 00:23:31.740 --> 00:23:34.529 it led. He truly was the great synthesizer of 00:23:34.529 --> 00:23:36.650 math, science, and faith. We have to go back 00:23:36.650 --> 00:23:39.029 to that quote. Man is only a reed, the weakest 00:23:39.029 --> 00:23:41.750 in nature, but he is a thinking reed. His physical 00:23:41.750 --> 00:23:44.250 form was weak, but his mind changed our world. 00:23:44.490 --> 00:23:47.130 And that profound tension in his own life between 00:23:47.130 --> 00:23:49.970 rational certainty and spiritual submission leaves 00:23:49.970 --> 00:23:51.490 us with a final thought for you to consider. 00:23:52.210 --> 00:23:55.049 Pascal. the brilliant mind who codified certainty 00:23:55.049 --> 00:23:57.650 in math and science, ultimately conclude that 00:23:57.650 --> 00:23:59.710 certainty in life's biggest questions can only 00:23:59.710 --> 00:24:03.069 be grasped through intuition and a wager. So 00:24:03.069 --> 00:24:05.309 what fundamental questions in your own life do 00:24:05.309 --> 00:24:08.309 you rely on intuition or a wager to answer, knowing 00:24:08.309 --> 00:24:10.309 that reason alone can't give you the proof you 00:24:10.309 --> 00:24:12.609 might want? That's a deep dive for another day. 00:24:12.730 --> 00:24:14.869 Thank you for joining us. We hope you feel thoroughly 00:24:14.869 --> 00:24:16.910 informed and perhaps profoundly curious.