WEBVTT 00:00:00.000 --> 00:00:03.000 Okay, let's get into this. We are doing a deep 00:00:03.000 --> 00:00:06.320 dive today into the story of a physicist whose 00:00:06.320 --> 00:00:09.619 work, I mean, it didn't just contribute to science, 00:00:09.720 --> 00:00:11.900 it fundamentally redefined our understanding 00:00:11.900 --> 00:00:15.039 of the universe. And yet her name is often, you 00:00:15.039 --> 00:00:17.539 know, kind of an afterthought when people list 00:00:17.539 --> 00:00:20.399 the greats. Exactly. We're talking about Dr. 00:00:20.559 --> 00:00:23.859 Chen Shengwu. If you look at the real heavy hitters 00:00:23.859 --> 00:00:26.739 in 20th century physics, her name has to be right 00:00:26.739 --> 00:00:28.780 at the top. She had all these powerful nicknames, 00:00:28.820 --> 00:00:31.260 almost like titles. Like what? Things like the 00:00:31.260 --> 00:00:34.579 First Lady of Physics, the Chinese Marie Curie, 00:00:34.619 --> 00:00:37.679 and maybe most importantly, the Queen of Nuclear 00:00:37.679 --> 00:00:40.259 Research. And those aren't just, you know, empty 00:00:40.259 --> 00:00:42.539 praise. They really point to the incredible scope 00:00:42.539 --> 00:00:44.820 of her work. We're talking about everything from 00:00:44.820 --> 00:00:47.520 nuclear fission to quantum entanglement. And 00:00:47.520 --> 00:00:50.780 her work on beta decay was foundational. Absolutely. 00:00:50.820 --> 00:00:53.259 She was, first and foremost, an experimentalist. 00:00:53.280 --> 00:00:55.119 I mean, a master experimentalist. When she got 00:00:55.119 --> 00:00:57.420 a result, it was meticulous, it was rigorous, 00:00:57.640 --> 00:00:59.479 and you just couldn't argue with it. Her precision 00:00:59.479 --> 00:01:01.500 was basically the gold standard for particle 00:01:01.500 --> 00:01:04.959 physics. It was. But her story isn't just about 00:01:04.959 --> 00:01:08.170 scientific genius. Is it? It's also a story of, 00:01:08.269 --> 00:01:12.219 well, profound injustice. And that really brings 00:01:12.219 --> 00:01:14.560 us to the central puzzle of her career. And it's 00:01:14.560 --> 00:01:17.159 really the core of our deep dive today. The Nobel 00:01:17.159 --> 00:01:20.019 Prize. The missing Nobel Prize. Right. If she 00:01:20.019 --> 00:01:23.180 was this master experimentalist, why do we always 00:01:23.180 --> 00:01:26.319 hear about the theorists? Why did Dr. Wu, who 00:01:26.319 --> 00:01:28.500 performed an experiment that some called the 00:01:28.500 --> 00:01:30.799 most important since the one that led to Einstein's 00:01:30.799 --> 00:01:34.340 relativity, why did she not get the 1957 Nobel 00:01:34.340 --> 00:01:38.000 Prize in physics? It's a huge question. The prize 00:01:38.000 --> 00:01:40.530 went to her colleagues, Tung Dao Lee. and Chen 00:01:40.530 --> 00:01:44.209 Ningyang for their theoretical idea. They predicted 00:01:44.209 --> 00:01:46.549 that a fundamental symmetry to the universe might 00:01:46.549 --> 00:01:49.189 be broken. And she's the one who proved it. She 00:01:49.189 --> 00:01:52.370 provided the physical definitive proof. And yet 00:01:52.370 --> 00:01:54.750 she was left out. It was a huge failure by the 00:01:54.750 --> 00:01:56.989 Nobel Committee to follow what was, you know, 00:01:56.989 --> 00:01:59.170 a pretty firm tradition of giving the prize to 00:01:59.170 --> 00:02:01.349 the experimentalists who actually confirm a theory. 00:02:01.549 --> 00:02:03.629 It's a massive oversight. I mean, other Nobel 00:02:03.629 --> 00:02:05.750 winners, like Jack Steinberger, have called it 00:02:05.750 --> 00:02:07.390 the biggest mistake the committee ever made. 00:02:07.510 --> 00:02:10.219 He did, yeah. So our mission for you today is 00:02:10.219 --> 00:02:12.099 to unpack her life, and we're going to do it 00:02:12.099 --> 00:02:14.900 chronologically. We want to focus on three huge 00:02:14.900 --> 00:02:18.039 scientific pillars that make this Nobel omission 00:02:18.039 --> 00:02:22.460 so, so staggering. First, her secret, absolutely 00:02:22.460 --> 00:02:25.060 vital work on the Manhattan Project. Then, her 00:02:25.060 --> 00:02:27.919 incredibly careful work that finally established 00:02:27.919 --> 00:02:30.719 Enrico Fermi's theory of beta decay. And of course, 00:02:30.759 --> 00:02:34.389 the big one. the famous high -stakes Wu experiment 00:02:34.389 --> 00:02:38.110 that shattered a law of nature. We want you to 00:02:38.110 --> 00:02:40.270 understand not just what she proved, but the 00:02:40.270 --> 00:02:43.490 sheer genius it took, experimentally and logistically, 00:02:43.729 --> 00:02:46.210 to actually pull it off. So to get that, we have 00:02:46.210 --> 00:02:48.770 to start at the beginning, in China. To understand 00:02:48.770 --> 00:02:51.090 the precision physicist, we have to go back to 00:02:51.090 --> 00:02:54.759 Luhe, Jiangsu province, in 1912. What's amazing 00:02:54.759 --> 00:02:56.780 right from the start is the environment she grew 00:02:56.780 --> 00:02:59.699 up in. Her father, Wu Zongyi, was just incredibly 00:02:59.699 --> 00:03:02.039 progressive. He really was. I mean, for a girl 00:03:02.039 --> 00:03:04.199 born in rural China in the early 20th century, 00:03:04.419 --> 00:03:06.620 her upbringing was extraordinary. Her father 00:03:06.620 --> 00:03:08.699 was an engineer and he was a social progressive 00:03:08.699 --> 00:03:11.159 who really believed in education for everyone, 00:03:11.280 --> 00:03:13.180 especially for women. And he didn't just believe 00:03:13.180 --> 00:03:16.099 it. He acted on it. That's the key. This wasn't 00:03:16.099 --> 00:03:18.400 just, you know, passive support. He went out 00:03:18.400 --> 00:03:20.879 and founded... The Mingda School for Girls. Yeah. 00:03:20.939 --> 00:03:22.840 That's where Wu got her primary education. He 00:03:22.840 --> 00:03:24.740 surrounded her with books and scientific journals. 00:03:25.080 --> 00:03:28.539 He was actively feeding her curiosity. And that 00:03:28.539 --> 00:03:31.060 encouragement just lit a fire in her. There's 00:03:31.060 --> 00:03:33.819 this incredible anecdote about her ambition when 00:03:33.819 --> 00:03:36.469 she was just 11 years old. Right. Applying for 00:03:36.469 --> 00:03:39.469 secondary school. She chose the Suzu Women's 00:03:39.469 --> 00:03:41.729 Normal School number two. And she picked the 00:03:41.729 --> 00:03:45.009 hardest path. The absolute hardest. The teacher 00:03:45.009 --> 00:03:46.949 training track. Yeah. Her family could have paid 00:03:46.949 --> 00:03:49.530 for an easier school, but she chose this highly 00:03:49.530 --> 00:03:52.469 competitive tuition -free program that would 00:03:52.469 --> 00:03:55.629 guarantee her a job. And to get in, she was ranked 00:03:55.629 --> 00:04:00.650 ninth out of about 10 ,000 applicants. Wow. Ninth 00:04:00.650 --> 00:04:03.289 out of 10 ,000. That kind of drive, that desire 00:04:03.289 --> 00:04:05.830 for rigor, it was there from the very beginning. 00:04:06.090 --> 00:04:07.930 And it wasn't just about books. She had this 00:04:07.930 --> 00:04:10.129 incredible capacity for political conviction, 00:04:10.289 --> 00:04:13.169 even while she was deep in her studies. At National 00:04:13.169 --> 00:04:15.229 Central University, where she started in math 00:04:15.229 --> 00:04:17.509 but switched to physics, she became a student 00:04:17.509 --> 00:04:20.029 leader. And this was during a really tense time 00:04:20.029 --> 00:04:22.610 with Japan. We're not talking about minor campus 00:04:22.610 --> 00:04:26.069 politics here. No, not at all. This was the volatile 00:04:26.069 --> 00:04:29.589 period right before the Sino -Japanese War. For 00:04:29.589 --> 00:04:31.529 a female physics student to get elected as a 00:04:31.529 --> 00:04:34.990 leader then was remarkable. She led these huge 00:04:34.990 --> 00:04:38.189 political protests, even a sit -in at the presidential 00:04:38.189 --> 00:04:40.730 palace in Nanjiang. And she met with Chiang Kai 00:04:40.730 --> 00:04:43.550 -shek. The students did, yes. But here's what's 00:04:43.550 --> 00:04:46.519 so telling about her character. The sources say 00:04:46.519 --> 00:04:49.060 she was incredibly disciplined. She never let 00:04:49.060 --> 00:04:51.199 all that political turmoil distract her from 00:04:51.199 --> 00:04:53.819 her studies. That balancing act, intense scientific 00:04:53.819 --> 00:04:57.060 focus on one hand and deep moral courage on the 00:04:57.060 --> 00:05:00.060 other that really drains her whole life. She 00:05:00.060 --> 00:05:02.740 also had a key female mentor early on, which 00:05:02.740 --> 00:05:05.920 must have been so rare. Her supervisor, Gu Jingwei. 00:05:06.060 --> 00:05:08.500 She was a female professor who had a Ph .D. from 00:05:08.500 --> 00:05:10.459 the University of Michigan. And she's the one 00:05:10.459 --> 00:05:13.019 who really pushed Wu to study abroad. And that 00:05:13.019 --> 00:05:15.300 advice basically set the stage for her move to 00:05:15.300 --> 00:05:18.079 the U .S. in 1936. Yeah, she sailed on the S 00:05:18.079 --> 00:05:19.920 .S. President Hoover, landed in San Francisco. 00:05:20.079 --> 00:05:22.279 The plan was to go to the University of Michigan, 00:05:22.360 --> 00:05:24.620 just like her mentor. But that's not what happened. 00:05:25.000 --> 00:05:28.500 No. That's when she ran into the first big shock 00:05:28.500 --> 00:05:31.449 of American academia. And it changed her entire 00:05:31.449 --> 00:05:34.350 career path. The Berkeley shock? What was that 00:05:34.350 --> 00:05:37.029 about? Well, she was just horrified by the sexism 00:05:37.029 --> 00:05:39.610 at Michigan. It was incredibly conservative back 00:05:39.610 --> 00:05:41.949 then. Women weren't even allowed to use the front 00:05:41.949 --> 00:05:43.649 entrance of the physics building. You're kidding. 00:05:43.949 --> 00:05:45.930 Nope. And that was an immediate deal breaker 00:05:45.930 --> 00:05:48.310 for her. She pivoted and chose the University 00:05:48.310 --> 00:05:50.790 of California, Berkeley instead, which was much 00:05:50.790 --> 00:05:53.250 more liberal and frankly was the place to be 00:05:53.250 --> 00:05:55.459 for physics at that time. Right. Berkeley was 00:05:55.459 --> 00:05:58.439 the epicenter of innovation. It really was. She 00:05:58.439 --> 00:06:01.019 was immediately immersed in the radiation laboratory 00:06:01.019 --> 00:06:04.360 run by Ernest O. Lawrence, you know, the inventor 00:06:04.360 --> 00:06:06.800 of the cyclotron. She met her future husband, 00:06:06.939 --> 00:06:09.899 Luke Yuan, there. It was just a hotbed of cutting 00:06:09.899 --> 00:06:12.220 -edge physics. And her colleagues there, they 00:06:12.220 --> 00:06:14.660 recognized her talent instantly. Oh, immediately. 00:06:15.230 --> 00:06:17.750 Luis Alvarez, who would go on to win a Nobel 00:06:17.750 --> 00:06:20.670 Prize himself, called her the most talented and 00:06:20.670 --> 00:06:23.329 most beautiful experimental physicist I've ever 00:06:23.329 --> 00:06:26.410 met. Emilio Segre, another giant, compared her 00:06:26.410 --> 00:06:29.490 to Marie Curie. He did. But he added that Wu 00:06:29.490 --> 00:06:33.829 was more worldly, elegant, and witty. Even Lawrence, 00:06:34.089 --> 00:06:36.230 the head of the lab, said she was the most talented 00:06:36.230 --> 00:06:38.769 female experimental physicist he'd ever known. 00:06:39.160 --> 00:06:41.360 But even with all that praise, she still ran 00:06:41.360 --> 00:06:44.100 into prejudice from the institution itself. The 00:06:44.100 --> 00:06:46.600 department head, Raymond Burge, he respected 00:06:46.600 --> 00:06:48.939 her talent enough to let her enroll late, but 00:06:48.939 --> 00:06:50.980 he was on record opposing Asian students getting 00:06:50.980 --> 00:06:53.399 scholarships. So she was in this weird position 00:06:53.399 --> 00:06:55.959 where her talent was undeniable, but the system 00:06:55.959 --> 00:06:58.319 was still pushing back against her. That talent. 00:06:58.620 --> 00:07:01.079 really came to a head with her PhD thesis in 00:07:01.079 --> 00:07:04.620 1940. It was incredible, not just for its content, 00:07:04.720 --> 00:07:08.779 but for its unforeseen historical importance. 00:07:08.980 --> 00:07:10.480 It had two parts, right? Two distinct parts. 00:07:10.579 --> 00:07:13.100 The first was on something called Remstralum. 00:07:13.439 --> 00:07:15.240 Which is what exactly? It's the x -rays that 00:07:15.240 --> 00:07:17.319 are produced when charged particles, in this 00:07:17.319 --> 00:07:20.560 case electrons, slow down really fast as they 00:07:20.560 --> 00:07:23.019 pass by atomic nuclei. She was studying this 00:07:23.019 --> 00:07:25.560 using phosphorus -32, which emits beta particles. 00:07:25.920 --> 00:07:28.519 This was her first really deep dive into beta 00:07:28.519 --> 00:07:30.899 decay, the field that she would just come to 00:07:30.899 --> 00:07:33.060 dominate. And the second part? The second part 00:07:33.060 --> 00:07:36.860 was on radioactive xenon isotopes that are produced 00:07:36.860 --> 00:07:38.899 during nuclear fission. And this is where things 00:07:38.899 --> 00:07:41.009 get really interesting. One of the physicists 00:07:41.009 --> 00:07:43.790 on her thesis committee was J. Robert Oppenheimer. 00:07:43.930 --> 00:07:46.569 The Oppenheimer. The Oppenheimer. And he was 00:07:46.569 --> 00:07:49.029 so blown away by this second part of her thesis 00:07:49.029 --> 00:07:51.589 that he apparently believed she knew everything 00:07:51.589 --> 00:07:53.870 there was to know about something called the 00:07:53.870 --> 00:07:56.930 neutron absorption cross -section of xenon. That 00:07:56.930 --> 00:07:59.529 sounds incredibly specific. It is incredibly 00:07:59.529 --> 00:08:02.129 specific. It's a tiny, esoteric piece of data 00:08:02.129 --> 00:08:06.029 buried in an unpublished PhD thesis. But that 00:08:06.029 --> 00:08:08.410 specific number, that little piece of knowledge, 00:08:08.569 --> 00:08:12.250 would just four years later become the key to 00:08:12.250 --> 00:08:14.990 saving the entire Manhattan Project from a catastrophic 00:08:14.990 --> 00:08:17.589 failure. It's amazing that Oppenheimer was so 00:08:17.589 --> 00:08:20.209 impressed. And yet, after she finishes this incredible 00:08:20.209 --> 00:08:22.790 thesis with recommendations from giants like 00:08:22.790 --> 00:08:26.009 Lawrence and Segre, what happens? Well, this 00:08:26.009 --> 00:08:28.149 is where that institutional genius wasn't enough 00:08:28.149 --> 00:08:30.910 to overcome the institutional barriers. She couldn't 00:08:30.910 --> 00:08:32.789 get a faculty position. Because she was a woman. 00:08:32.950 --> 00:08:36.110 An Asian. It was a combination of both. So she 00:08:36.110 --> 00:08:38.230 stayed at Berkeley for a bit as a postdoc and 00:08:38.230 --> 00:08:40.149 then eventually moved to the East Coast with 00:08:40.149 --> 00:08:43.309 Luke Ewan, who she married in 1942. She took 00:08:43.309 --> 00:08:45.830 a job at Smith College, I read. She did, and 00:08:45.830 --> 00:08:47.870 she found it deeply frustrating. It was a teaching 00:08:47.870 --> 00:08:50.830 -only position, and she had zero opportunity 00:08:50.830 --> 00:08:52.889 for the research that she was so passionate about. 00:08:53.190 --> 00:08:55.990 It got so bad, she had to write to Lawrence and 00:08:55.990 --> 00:08:58.450 ask for letters of recommendation just to get 00:08:58.450 --> 00:09:00.950 out of there. Did Smith try to keep her? They 00:09:00.950 --> 00:09:03.169 did. They upped her salary and made her an associate 00:09:03.169 --> 00:09:06.669 professor. But the lack of research was the real 00:09:06.669 --> 00:09:09.730 problem. So she moved on. She did. She took a 00:09:09.730 --> 00:09:11.370 much better position at Princeton University. 00:09:11.710 --> 00:09:14.309 And she actually made history there as the first 00:09:14.309 --> 00:09:17.110 female faculty member ever in their physics department. 00:09:17.370 --> 00:09:19.789 She was teaching Navy officers because, you know, 00:09:19.830 --> 00:09:22.769 it was wartime. But her very specific, very niche 00:09:22.769 --> 00:09:25.730 expertise was needed somewhere else, somewhere 00:09:25.730 --> 00:09:29.289 much more important. The Manhattan Project. In 00:09:29.289 --> 00:09:32.710 March of 1944, Dr. Wu joined what were called 00:09:32.710 --> 00:09:35.289 the Substitute Alloy Materials Laboratories, 00:09:35.330 --> 00:09:38.309 or SAM Labs, at Columbia. That's a great codename. 00:09:38.450 --> 00:09:40.850 It is. She was initially working on radiation 00:09:40.850 --> 00:09:44.389 detectors, but her role was about to become much, 00:09:44.409 --> 00:09:47.610 much bigger because of a sudden, terrifying crisis 00:09:47.610 --> 00:09:49.830 that was unfolding out in Washington state. This 00:09:49.830 --> 00:09:52.149 is the famous xenon crisis. It's one of those 00:09:52.149 --> 00:09:55.289 amazing stories where... A theoretical disaster 00:09:55.289 --> 00:09:59.429 is completely averted by this one specific piece 00:09:59.429 --> 00:10:02.070 of experimental data that almost no one knew 00:10:02.070 --> 00:10:05.009 existed. That's it. Exactly. In September 1944, 00:10:05.610 --> 00:10:07.909 Colonel Kenneth Nichols gets in touch with Wu 00:10:07.909 --> 00:10:10.149 about a massive problem they're having at the 00:10:10.149 --> 00:10:12.529 brand new B Reactor at the Hanford site. And 00:10:12.529 --> 00:10:14.490 the B Reactor was this was the big one, right? 00:10:14.529 --> 00:10:17.350 The first full scale nuclear reactor in the world. 00:10:17.450 --> 00:10:20.409 The very first. Its whole purpose was to produce 00:10:20.409 --> 00:10:23.629 plutonium 239 for the atomic bomb. It was supposed 00:10:23.629 --> 00:10:25.830 to sustain a controlled nuclear chain reaction. 00:10:25.990 --> 00:10:27.889 And at first it worked. It worked brilliantly. 00:10:28.070 --> 00:10:30.610 The chain reaction started up. It was self -sustaining. 00:10:30.750 --> 00:10:32.889 And then after just a few hours, the reaction 00:10:32.889 --> 00:10:34.570 rate would just plummet to zero. The reactor 00:10:34.570 --> 00:10:38.789 would shut itself down to stop. Then, hours later, 00:10:39.029 --> 00:10:41.870 it would mysteriously start back up on its own, 00:10:41.929 --> 00:10:45.690 only to shut down again a short time later. They 00:10:45.690 --> 00:10:47.909 were caught in this totally useless cycle, and 00:10:47.909 --> 00:10:50.149 nobody could figure out why. The whole project 00:10:50.149 --> 00:10:52.230 is on the line. What did they suspect was happening? 00:10:52.600 --> 00:10:54.960 Well, the top theorists, John Archibald Wheeler 00:10:54.960 --> 00:10:57.299 and the great Enrico Fermi, they suspected a 00:10:57.299 --> 00:10:59.820 specific byproduct of the fission process was 00:10:59.820 --> 00:11:03.679 the culprit, an isotope called xenon -135. Xenon 00:11:03.679 --> 00:11:05.879 -135. They theorized that it was acting as a 00:11:05.879 --> 00:11:08.379 neutron poison. It was just sucking up all the 00:11:08.379 --> 00:11:10.200 free neutrons that were needed to keep the chain 00:11:10.200 --> 00:11:13.000 reaction going. So it was poisoning its own reaction. 00:11:13.360 --> 00:11:15.899 That was the theory. But they needed proof. More 00:11:15.899 --> 00:11:17.879 than that, they needed the exact number. They 00:11:17.879 --> 00:11:20.759 needed to know precisely how likely xenon -135 00:11:20.759 --> 00:11:23.659 was to capture a neutron. That's its neutron 00:11:23.659 --> 00:11:25.899 absorption cross -section. If that number was 00:11:25.899 --> 00:11:27.720 big enough, their theory was right. And how did 00:11:27.720 --> 00:11:29.860 they find that number? This is the crucial part. 00:11:30.399 --> 00:11:33.299 Emilio Segre, who had been on Wu's PhD committee 00:11:33.299 --> 00:11:36.440 back at Berkeley, remembered her thesis. He remembered 00:11:36.440 --> 00:11:38.419 that unpublished second part about radioactive 00:11:38.419 --> 00:11:42.500 xenon isotopes. No way. Yes. Fermi immediately 00:11:42.500 --> 00:11:45.700 contacted Wu. She provided them with her typewritten 00:11:45.700 --> 00:11:49.009 draft. And there it was. Her paper, based on 00:11:49.009 --> 00:11:52.429 work she did years earlier, confirmed it. Xenon 00:11:52.429 --> 00:11:55.830 -135 had an absurdly, catastrophically large 00:11:55.830 --> 00:11:58.929 neutron absorption cross -section, much larger 00:11:58.929 --> 00:12:01.269 than anyone had predicted. So the reactor design 00:12:01.269 --> 00:12:04.570 was just wrong. It didn't account for this super 00:12:04.570 --> 00:12:06.470 poison. It was being poisoned by its own waste 00:12:06.470 --> 00:12:09.389 product. The xenon would build up, kill the reaction, 00:12:09.669 --> 00:12:12.350 then it would decay away over a few hours, which 00:12:12.350 --> 00:12:14.419 allowed the reactor to restart. and then the 00:12:14.419 --> 00:12:16.559 cycle would begin all over again. And Wu's data 00:12:16.559 --> 00:12:18.460 was the key to fixing it. It was everything. 00:12:18.620 --> 00:12:20.919 Her precise number allowed Wheeler to calculate 00:12:20.919 --> 00:12:23.340 exactly how much more uranium fuel they needed, 00:12:23.460 --> 00:12:25.940 and critically, how many extra control rods they 00:12:25.940 --> 00:12:28.120 had to build into the reactor to overcome the 00:12:28.120 --> 00:12:30.100 poisoning effect and keep it running continuously. 00:12:30.419 --> 00:12:33.220 So an unpublished thesis by a young female physicist, 00:12:33.480 --> 00:12:35.860 based on work done years before the project even 00:12:35.860 --> 00:12:38.480 began, literally rescued the most critical part 00:12:38.480 --> 00:12:40.840 of the war effort. That's not an exaggeration. 00:12:41.529 --> 00:12:43.990 Her findings were then used across the project 00:12:43.990 --> 00:12:46.570 to build the standard model for producing enriched 00:12:46.570 --> 00:12:49.309 uranium at Oak Ridge and even to design better 00:12:49.309 --> 00:12:51.929 Geiger counters. She was a true pioneer of the 00:12:51.929 --> 00:12:54.750 nuclear age. But she had reservations about it 00:12:54.750 --> 00:12:56.769 later, didn't she? She did. Like a lot of the 00:12:56.769 --> 00:12:59.070 scientists involved, she distanced herself from 00:12:59.070 --> 00:13:01.649 the destructive outcome. She said later she was 00:13:01.649 --> 00:13:04.529 glad her family in China was safe, but she expressed 00:13:04.529 --> 00:13:07.570 a hope that humankind could eventually live in 00:13:07.570 --> 00:13:10.549 peace. Her life's work really turned away from 00:13:10.549 --> 00:13:12.730 bombs and towards understanding the fundamental 00:13:12.730 --> 00:13:16.070 laws of nature. Okay, so the war ends in 1945. 00:13:16.710 --> 00:13:20.269 She accepts a position at Columbia. And in 1952, 00:13:20.309 --> 00:13:22.629 she becomes the first woman to get tenure in 00:13:22.629 --> 00:13:25.210 their physics department. Right. And she immediately 00:13:25.210 --> 00:13:27.269 starts working on these foundational experiments 00:13:27.269 --> 00:13:29.730 that show the same level of genius she brought 00:13:29.730 --> 00:13:32.220 to the xenon problem. For instance, her work 00:13:32.220 --> 00:13:34.740 on quantum entanglement. Yeah, this was in 1949. 00:13:34.779 --> 00:13:37.100 She was the first person to experimentally confirm 00:13:37.100 --> 00:13:40.080 the validity of quantum entanglement, that thing 00:13:40.080 --> 00:13:42.799 Einstein famously called spooky action at a distance. 00:13:43.039 --> 00:13:45.259 The idea that two particles can be linked no 00:13:45.259 --> 00:13:48.100 matter how far apart they are. Exactly. She observed 00:13:48.100 --> 00:13:50.919 the angular correlation of two photons, which 00:13:50.919 --> 00:13:53.299 proved the calculations of a couple of theorists. 00:13:53.340 --> 00:13:56.639 It was a really critical early confirmation of 00:13:56.639 --> 00:13:59.529 this bizarre quantum reality. But the work that 00:13:59.529 --> 00:14:01.789 really set the stage for her biggest breakthrough 00:14:01.789 --> 00:14:05.210 was her complete mastery of beta decay. Right. 00:14:05.330 --> 00:14:08.429 This goes back to Enrico Fermi's famous 1934 00:14:08.429 --> 00:14:12.009 theory that describes how beta decay works. A 00:14:12.009 --> 00:14:14.629 neutron turns into a proton, and it spits out 00:14:14.629 --> 00:14:17.250 an electron and a neutrino. But by the 1940s, 00:14:17.250 --> 00:14:19.230 there were problems. The experimental results 00:14:19.230 --> 00:14:22.049 just weren't quite matching the theory. There 00:14:22.049 --> 00:14:24.490 were these small, frustrating variances. Even 00:14:24.490 --> 00:14:26.429 a brilliant experimentalist like Luis Walter 00:14:26.429 --> 00:14:28.730 Alvarez was getting results that didn't quite 00:14:28.730 --> 00:14:31.169 line up. So Wu set out to figure out what was 00:14:31.169 --> 00:14:33.350 going on. And her conclusion was that the problem 00:14:33.350 --> 00:14:36.389 wasn't with Formy's theory. No. The problem was 00:14:36.389 --> 00:14:38.610 with the experiments themselves. She had this 00:14:38.610 --> 00:14:40.690 hunch that the issue was the way they were preparing 00:14:40.690 --> 00:14:42.750 the radioactive source material. People were 00:14:42.750 --> 00:14:45.149 using a thick, uneven film of something like 00:14:45.149 --> 00:14:47.669 copper sulfate. And why would that matter? Think 00:14:47.669 --> 00:14:50.289 of it like this. If the source is too thick, 00:14:50.730 --> 00:14:53.250 The electrons, the beta particles that are emitted, 00:14:53.470 --> 00:14:56.250 lose some of their energy just trying to escape 00:14:56.250 --> 00:14:58.990 the material itself before they even get to the 00:14:58.990 --> 00:15:02.090 detector. Ah, so that energy loss was distorting 00:15:02.090 --> 00:15:04.090 the measurements. Precisely. It was making the 00:15:04.090 --> 00:15:06.549 results look inconsistent with Fermi's beautiful, 00:15:06.850 --> 00:15:10.090 elegant theory. So what was her solution? This 00:15:10.090 --> 00:15:12.990 seems like a purely practical, experimental genius 00:15:12.990 --> 00:15:15.889 kind of problem. It was. She first took an old 00:15:15.889 --> 00:15:18.919 solenoidal spectrometer. a device that uses a 00:15:18.919 --> 00:15:21.019 magnetic field to measure the energy of electrons, 00:15:21.320 --> 00:15:23.500 and she modified it to be much more precise. 00:15:23.919 --> 00:15:26.519 Then she developed a new method using detergent 00:15:26.519 --> 00:15:29.179 to create an incredibly thin, perfectly even 00:15:29.179 --> 00:15:31.700 film of the radioactive source. So no more energy 00:15:31.700 --> 00:15:34.440 loss. Almost zero. And when she ran the experiment 00:15:34.440 --> 00:15:36.539 with her new, pristine setup... The results were 00:15:36.539 --> 00:15:39.440 perfect. Perfectly consistent with Fermi's model. 00:15:39.720 --> 00:15:42.860 She proved, definitively, that all those other 00:15:42.860 --> 00:15:45.500 discrepancies were just due to experimental error. 00:15:46.320 --> 00:15:49.179 By fixing the apparatus, she validated Fermi's 00:15:49.179 --> 00:15:51.740 physics, and in the process, she established 00:15:51.740 --> 00:15:54.559 herself as the world's leading authority on beta 00:15:54.559 --> 00:15:57.919 decay. And that mastery was the absolute prerequisite 00:15:57.919 --> 00:15:59.940 for the experiment that was about to change everything. 00:16:00.279 --> 00:16:03.080 This complete mastery of the beta decay really 00:16:03.080 --> 00:16:05.240 does set the stage perfectly for the experiment 00:16:05.240 --> 00:16:08.000 that defines her legacy, shattering the law of 00:16:08.000 --> 00:16:10.620 parity conservation. We're now in the mid -1950s. 00:16:10.639 --> 00:16:12.889 That's right. And two of her colleagues at Columbia, 00:16:13.090 --> 00:16:15.669 the theoretical physicists Sung Dao Lee and Tianning 00:16:15.669 --> 00:16:17.490 Yang, they were wrestling with something called 00:16:17.490 --> 00:16:20.029 the Veda Tau puzzle. OK, before we dive into 00:16:20.029 --> 00:16:21.889 the puzzle, let's make sure we're all clear on 00:16:21.889 --> 00:16:24.389 what parity even is. What did physicists mean 00:16:24.389 --> 00:16:27.169 by conservation of parity and why was it considered 00:16:27.169 --> 00:16:30.169 such a core, unshakable law? Think of that like 00:16:30.169 --> 00:16:32.809 a mirror. Parity conservation means that the 00:16:32.809 --> 00:16:35.370 laws of physics are the same for an event as 00:16:35.370 --> 00:16:38.370 they are for its mirror image. The universe fundamentally 00:16:38.370 --> 00:16:40.899 doesn't distinguish between left and right. So 00:16:40.899 --> 00:16:43.000 if I watch a video of a baseball game and then 00:16:43.000 --> 00:16:45.580 I watch a mirror image of that video, all the 00:16:45.580 --> 00:16:48.200 physics, the way the ball flies, the way the 00:16:48.200 --> 00:16:51.139 bat hits it, all of that should still work. Exactly. 00:16:51.259 --> 00:16:53.919 Physics was assumed to be spatially symmetrical. 00:16:54.639 --> 00:16:57.679 And this wasn't just a minor idea. It was considered 00:16:57.679 --> 00:17:00.360 a fundamental principle that applied to all four 00:17:00.360 --> 00:17:04.099 forces of nature. Gravity, electromagnetism, 00:17:04.240 --> 00:17:06.960 the strong force, and the weak force. It was 00:17:06.960 --> 00:17:09.319 an assumed truth. It was elegant. It was very 00:17:09.319 --> 00:17:11.839 elegant. But these two particles, the theta -misson 00:17:11.839 --> 00:17:14.480 and the tau -misson, were causing a huge problem 00:17:14.480 --> 00:17:16.720 for this elegant idea. The theta -tau puzzle. 00:17:17.019 --> 00:17:19.039 Right. These two particles seemed completely 00:17:19.039 --> 00:17:21.500 identical. They had the same mass, the same lifetime, 00:17:21.640 --> 00:17:25.079 the same charge. But they decayed into completely 00:17:25.079 --> 00:17:27.720 different final states. and those final states 00:17:27.720 --> 00:17:29.779 had different parodies. Okay, that is a puzzle. 00:17:29.920 --> 00:17:32.220 It's like having two identical billiard balls, 00:17:32.460 --> 00:17:34.319 but when you hit them in exactly the same way, 00:17:34.359 --> 00:17:36.119 one shatters and the other one just rolls away. 00:17:36.420 --> 00:17:38.900 That's a great analogy. If parity was conserved, 00:17:39.059 --> 00:17:41.559 as everyone believed, then these had to be two 00:17:41.559 --> 00:17:43.019 different particles. They just happened to look 00:17:43.019 --> 00:17:45.960 identical. But if they were, in fact, the same 00:17:45.960 --> 00:17:49.099 particle, then parity had to be violated. So 00:17:49.099 --> 00:17:53.140 Li and Yang had this radical idea. What if, just 00:17:53.140 --> 00:17:55.890 for the weak interaction, the force governing 00:17:55.890 --> 00:17:59.809 this strange decay, what if parity isn't conserved 00:17:59.809 --> 00:18:02.349 at all? That was their theory, but it was scientific 00:18:02.349 --> 00:18:04.609 heresy. They designed a kind of pencil and paper 00:18:04.609 --> 00:18:07.049 experiment to test it, but they were terrified. 00:18:07.369 --> 00:18:09.710 If the experiment failed, their careers would 00:18:09.710 --> 00:18:11.750 be ruined. So they needed someone to perform 00:18:11.750 --> 00:18:13.890 the experiment whose results would be absolutely 00:18:13.890 --> 00:18:16.410 beyond question. And there was only one person 00:18:16.410 --> 00:18:18.009 in the world with that reputation for that kind 00:18:18.009 --> 00:18:21.569 of work, Dr. Wu. The master of beta decay. Exactly. 00:18:21.950 --> 00:18:24.660 They went to her. and she immediately saw the 00:18:24.660 --> 00:18:27.460 importance of the question. She chose to test 00:18:27.460 --> 00:18:30.619 their theory using radioactive cobalt -60, which 00:18:30.619 --> 00:18:32.740 is a beta particle emitter. It was her specialty. 00:18:33.259 --> 00:18:36.440 But the experiment itself, it was almost impossible 00:18:36.440 --> 00:18:39.319 with the technology of the 1950s. A logistical 00:18:39.319 --> 00:18:41.740 and technical nightmare, I've heard. A complete 00:18:41.740 --> 00:18:44.519 nightmare. She needed to achieve two extreme 00:18:44.519 --> 00:18:46.799 conditions at the same time, and she spent a 00:18:46.799 --> 00:18:49.079 whole year on this, putting all her other research 00:18:49.079 --> 00:18:51.240 on hold. Okay, let's break it down. Condition 00:18:51.240 --> 00:18:55.220 one. Cryogenics. She needed to get the Cobalt 00:18:55.220 --> 00:18:59.000 -60 sample incredibly cold. Why? She had to get 00:18:59.000 --> 00:19:01.740 the atoms to stop wiggling around? At normal 00:19:01.740 --> 00:19:03.779 temperatures, the nuclei in the cobalt are all 00:19:03.779 --> 00:19:06.220 spinning in random directions. If you're trying 00:19:06.220 --> 00:19:08.599 to measure a directional preference, all that 00:19:08.599 --> 00:19:11.079 randomness just averages out to zero. So you 00:19:11.079 --> 00:19:12.779 wouldn't see anything even if the effect was 00:19:12.779 --> 00:19:15.259 there. Correct. So she had to cool the sample 00:19:15.259 --> 00:19:17.819 down to just fractions of a degree above absolute 00:19:17.819 --> 00:19:22.400 zero, about 0 .003 Kelvin. She used these specialized 00:19:22.400 --> 00:19:25.160 liquid helium refrigerators to basically freeze 00:19:25.160 --> 00:19:27.960 the atoms in place. Once they were frozen, she 00:19:27.960 --> 00:19:30.450 could move on to condition two. Magnetic alignment. 00:19:30.730 --> 00:19:32.269 How did she get them all to spin in the same 00:19:32.269 --> 00:19:35.250 direction? She used a powerful, uniform magnetic 00:19:35.250 --> 00:19:37.970 field. She put the sample inside a solenoid magnet, 00:19:38.210 --> 00:19:40.490 which acted like a giant compass for the atomic 00:19:40.490 --> 00:19:43.170 nuclei, lining up all their spin axes in the 00:19:43.170 --> 00:19:44.809 same direction. And then the detectors were set 00:19:44.809 --> 00:19:47.170 up to measure... What? They were set up to count 00:19:47.170 --> 00:19:49.450 the beta particles that were emitted along the 00:19:49.450 --> 00:19:52.480 direction of the spin. And the particles... emitted 00:19:52.480 --> 00:19:55.440 against the direction of the spin. If the numbers 00:19:55.440 --> 00:19:58.240 were the same, symmetry holds. If the numbers 00:19:58.240 --> 00:20:01.160 were different, symmetry is broken. And she couldn't 00:20:01.160 --> 00:20:02.839 do this at Columbia. She had to go somewhere 00:20:02.839 --> 00:20:05.420 else. Right. She had to travel to the National 00:20:05.420 --> 00:20:08.299 Bureau of Standards in Maryland, which had the 00:20:08.299 --> 00:20:11.859 specialized cryogenic equipment she needed. This 00:20:11.859 --> 00:20:14.720 adds a layer of drama because she's now physically 00:20:14.720 --> 00:20:17.440 separated from Li and Yang during the most critical 00:20:17.440 --> 00:20:20.069 part of the experiment. So Li and Yang's prediction 00:20:20.069 --> 00:20:22.390 was that the emission would be asymmetrical. 00:20:22.769 --> 00:20:26.029 Yes. They predicted that more beta particles 00:20:26.029 --> 00:20:28.829 would be ejected in one direction, say, opposite 00:20:28.829 --> 00:20:31.069 to the nuclear spin, than in the other. And when 00:20:31.069 --> 00:20:33.109 she finally ran the experiment, what did the 00:20:33.109 --> 00:20:35.829 detector show? The result was immediate, and 00:20:35.829 --> 00:20:38.460 it was dramatic. The asymmetry was there beyond 00:20:38.460 --> 00:20:41.779 any possible statistical doubt. A far, far greater 00:20:41.779 --> 00:20:44.400 number of electrons were emitted in the direction 00:20:44.400 --> 00:20:46.660 opposite to the spin of the nucleus. Parity was 00:20:46.660 --> 00:20:49.640 violated. Parity was not conserved under the 00:20:49.640 --> 00:20:53.420 weak nuclear force. This beautiful, elegant principle 00:20:53.420 --> 00:20:57.359 that everyone had assumed was true was not. The 00:20:57.359 --> 00:20:59.559 universe at this fundamental level actually does 00:20:59.559 --> 00:21:02.059 have a preference. It prefers left over right. 00:21:02.240 --> 00:21:05.039 She called Lee immediately. She did. And he asked 00:21:05.039 --> 00:21:07.220 her, are you sure? Because the implications were 00:21:07.220 --> 00:21:09.660 just so massive. This wasn't just a small correction. 00:21:09.920 --> 00:21:12.500 This was shattering a core belief of physics. 00:21:12.759 --> 00:21:15.710 And the impact was huge. It meant the theta and 00:21:15.710 --> 00:21:18.009 tau mesons were, in fact, the same particle. 00:21:18.210 --> 00:21:21.250 Which we now call the kion, yes. And her results 00:21:21.250 --> 00:21:23.970 were so clean, so definitive, they were confirmed 00:21:23.970 --> 00:21:26.849 by other labs almost instantly and published 00:21:26.849 --> 00:21:29.230 right alongside Li and Yang's theoretical paper 00:21:29.230 --> 00:21:31.490 in the same issue of the journal. The physics 00:21:31.490 --> 00:21:34.349 community was just stunned. Completely stunned. 00:21:34.650 --> 00:21:36.650 Otto Frisch said that physicists at Princeton 00:21:36.650 --> 00:21:38.069 thought it was the most impactful experiment 00:21:38.069 --> 00:21:40.769 since the Michelson -Morley experiment. The experiment 00:21:40.769 --> 00:21:43.329 that inspired Einstein's theory of relativity. 00:21:43.569 --> 00:21:46.390 That's an incredible comparison. It is, because 00:21:46.390 --> 00:21:49.190 this discovery really did set the stage for all 00:21:49.190 --> 00:21:52.009 of modern particle physics. It showed that fundamental 00:21:52.009 --> 00:21:55.650 symmetries could be broken, and that idea is 00:21:55.650 --> 00:21:58.029 the absolute foundation of the Standard Model. 00:21:58.410 --> 00:22:00.089 OK, let's connect the dots here to something 00:22:00.089 --> 00:22:03.130 even bigger. You mentioned this discovery led 00:22:03.130 --> 00:22:05.109 to understanding something called CP violation 00:22:05.109 --> 00:22:07.869 and that this helps explain why the universe 00:22:07.869 --> 00:22:11.349 even exists. That's a huge leap. How do we get 00:22:11.349 --> 00:22:14.529 from wiggling cobalt atoms to the Big Bang? It 00:22:14.529 --> 00:22:16.950 is hugely, but it follows directly from Wu's 00:22:16.950 --> 00:22:19.789 result. You see, once physicists realized that 00:22:19.789 --> 00:22:22.460 parity. The P and CP could be violated. They 00:22:22.460 --> 00:22:24.539 started looking at other symmetries. They looked 00:22:24.539 --> 00:22:26.660 at the combined symmetry of charge conjugation, 00:22:26.759 --> 00:22:29.559 C, which is swapping a particle for its antiparticle, 00:22:29.660 --> 00:22:32.279 and parity P. So CT symmetry. Right. And the 00:22:32.279 --> 00:22:35.019 theory was, if CP symmetry was perfectly conserved, 00:22:35.160 --> 00:22:37.140 the Big Bang should have created equal amounts 00:22:37.140 --> 00:22:39.500 of matter and antimatter. And if that happened, 00:22:39.619 --> 00:22:41.579 they would have all met and annihilated each 00:22:41.579 --> 00:22:44.000 other, leaving a universe of just energy. No 00:22:44.000 --> 00:22:47.289 planets, no stars, no us. Precisely. The fact 00:22:47.289 --> 00:22:49.890 that we are here in a universe full of matter 00:22:49.890 --> 00:22:52.970 means that symmetry must have been broken. There 00:22:52.970 --> 00:22:55.309 must have been a tiny violation of CP symmetry 00:22:55.309 --> 00:22:57.430 in the early universe that allowed a little bit 00:22:57.430 --> 00:23:00.289 more matter to survive than antimatter. And the 00:23:00.289 --> 00:23:03.210 idea that a fundamental symmetry could be broken 00:23:03.210 --> 00:23:06.410 at all started with Wu's experiment. Her experiment 00:23:06.410 --> 00:23:09.289 opened that door. It quite literally provides 00:23:09.289 --> 00:23:11.789 the foundation for explaining why we have a universe 00:23:11.789 --> 00:23:14.089 of structure instead of just a void of light. 00:23:14.430 --> 00:23:16.150 Which brings us back to the great controversy. 00:23:16.569 --> 00:23:20.230 Li and Yang get the Nobel Prize in 1957 for the 00:23:20.230 --> 00:23:23.410 theory. Wu, who did the incredibly difficult 00:23:23.410 --> 00:23:27.210 experiment that proved it, gets nothing. It's 00:23:27.210 --> 00:23:29.539 just indefensible. As you said, Jack Steinberger 00:23:29.539 --> 00:23:31.619 called it the Nobel Committee's biggest mistake. 00:23:31.880 --> 00:23:34.779 Even Wolfgang Polly, who had famously wagered 00:23:34.779 --> 00:23:37.039 against parity violation, he was shaken by what 00:23:37.039 --> 00:23:39.259 he called the sudden death of parity, and he 00:23:39.259 --> 00:23:41.359 couldn't believe Wu was denied the prize. The 00:23:41.359 --> 00:23:43.740 decision was also made incredibly fast, wasn't 00:23:43.740 --> 00:23:46.500 it? The confirmation was in late 1956, and the 00:23:46.500 --> 00:23:48.799 prize was awarded less than a year later. It 00:23:48.799 --> 00:23:51.660 was very rushed. It's very likely the committee 00:23:51.660 --> 00:23:54.039 didn't fully appreciate the immense technical 00:23:54.039 --> 00:23:56.819 difficulty of what she had accomplished. But 00:23:56.819 --> 00:23:59.660 we know her peers did. We know now that she received 00:23:59.660 --> 00:24:03.099 20 different Nobel nominations between 1958 and 00:24:03.099 --> 00:24:06.079 1973. She did eventually get major international 00:24:06.079 --> 00:24:09.180 recognition, though. Yes. In 1978, she was awarded 00:24:09.180 --> 00:24:11.680 the very first Wolf Prize in physics, which is 00:24:11.680 --> 00:24:13.619 often seen as an award for people who deserved 00:24:13.619 --> 00:24:16.190 a Nobel but never got one. The parity experiment 00:24:16.190 --> 00:24:18.990 was her most famous, but her work was far from 00:24:18.990 --> 00:24:21.309 over. Not at all. In fact, shattering parity 00:24:21.309 --> 00:24:23.630 just opened up a whole new set of questions about 00:24:23.630 --> 00:24:26.029 the weak interaction. Which brings us to the 00:24:26.029 --> 00:24:29.069 conserved vector current, or CVC, hypothesis. 00:24:29.609 --> 00:24:32.130 That sounds a bit technical. What were Richard 00:24:32.130 --> 00:24:33.990 Feynman and Murray Gell -Mann trying to do with 00:24:33.990 --> 00:24:36.309 that? They were trying to build a universal framework. 00:24:36.950 --> 00:24:39.670 After parity was broken, everyone realized that 00:24:39.670 --> 00:24:41.990 Fermi's original theory of beta decay needed 00:24:41.990 --> 00:24:45.440 an upgrade. CDC was basically Feynman and Gell 00:24:45.440 --> 00:24:47.240 -Mann's attempt to show that the rules for beta 00:24:47.240 --> 00:24:50.279 decay weren't some random isolated thing. They 00:24:50.279 --> 00:24:53.140 followed a predictable, conserved pattern. Sort 00:24:53.140 --> 00:24:55.900 of like how electric charge is conserved. A universal 00:24:55.900 --> 00:24:58.200 law for the weak force. That's what they were 00:24:58.200 --> 00:25:00.440 after. And once again, to prove their theory, 00:25:00.640 --> 00:25:04.180 they needed an experimentalist with unparalleled 00:25:04.180 --> 00:25:07.839 precision. They needed Dr. Wu. Of course. There's 00:25:07.839 --> 00:25:10.220 a story that Gell -Mann went up to her and asked, 00:25:10.279 --> 00:25:13.180 sort of jokingly, how long did Yang and Li pursue 00:25:13.180 --> 00:25:17.059 you to follow up on their work? It was this universal 00:25:17.059 --> 00:25:19.299 acknowledgement that if you had a foundational 00:25:19.299 --> 00:25:22.019 theory about the weak force, you had to go to 00:25:22.019 --> 00:25:24.079 her to prove it. So she took on the challenge. 00:25:24.299 --> 00:25:26.299 She did. She worked with her team at Columbia, 00:25:26.460 --> 00:25:31.000 and in December of 1962, she confirmed the CVC 00:25:31.000 --> 00:25:34.200 hypothesis. This was another huge piece of the 00:25:34.200 --> 00:25:36.440 puzzle for the standard model. It provided a 00:25:36.440 --> 00:25:38.599 complete solid foundation for Fermi's theory 00:25:38.599 --> 00:25:41.259 and also supported the theory of the two -component 00:25:41.259 --> 00:25:43.539 neutrino, which her parity experiment had actually 00:25:43.539 --> 00:25:45.519 established in the first place. Feynman must 00:25:45.519 --> 00:25:48.359 have been thrilled. He was ecstatic. He called 00:25:48.359 --> 00:25:50.559 the confirmed CVC theory one of his greatest 00:25:50.559 --> 00:25:52.779 scientific achievements, which shows you how 00:25:52.779 --> 00:25:55.460 much he valued her experimental proof. And during 00:25:55.460 --> 00:25:57.359 all this, her work ethic was just legendary. 00:25:57.980 --> 00:26:00.500 It was. She was made a full professor in 1958 00:26:00.500 --> 00:26:04.299 and got an endowed chair in 1973. She worked 00:26:04.299 --> 00:26:06.859 from 8 in the morning until 7 or 8 at night most 00:26:06.859 --> 00:26:09.559 days. Her students called her the Dragon Lady. 00:26:09.819 --> 00:26:12.920 That sounds intimidating. She was definitely 00:26:12.920 --> 00:26:14.900 demanding. But you have to understand, in her 00:26:14.900 --> 00:26:17.819 field, one tiny flaw in preparing a radioactive 00:26:17.819 --> 00:26:21.000 source could completely invalidate months of 00:26:21.000 --> 00:26:23.940 work. She knew that better than anyone. But the 00:26:23.940 --> 00:26:25.980 sources also say she treated her students like 00:26:25.980 --> 00:26:27.900 family. She'd have lunch with them every day, 00:26:27.980 --> 00:26:30.319 talk through their problems, personal and professional. 00:26:30.599 --> 00:26:33.099 It was a balance of extreme rigor and genuine 00:26:33.099 --> 00:26:36.279 care. And her scientific curiosity went way beyond 00:26:36.279 --> 00:26:39.140 just particle physics. Oh, absolutely. She co 00:26:39.140 --> 00:26:41.220 -wrote the definitive textbook on beta decay 00:26:41.220 --> 00:26:43.539 in 1966, which is still a standard reference 00:26:43.539 --> 00:26:46.039 today. And she even ventured into biology. She 00:26:46.039 --> 00:26:48.059 did. She used a technique called must -power 00:26:48.059 --> 00:26:50.839 spectroscopy to study the molecular changes in 00:26:50.839 --> 00:26:53.240 hemoglobin that cause sickle cell disease. And 00:26:53.240 --> 00:26:54.799 she did these incredibly detailed experiments 00:26:54.799 --> 00:26:57.400 on a rare poropsis called double beta decay, 00:26:57.700 --> 00:27:00.079 working 2 ,000 feet underground in a salt mine 00:27:00.079 --> 00:27:03.099 to shield her detectors from cosmic rays. All 00:27:03.099 --> 00:27:05.160 this work kept her in the U .S., though, far 00:27:05.160 --> 00:27:08.200 from her family in China, which was going through 00:27:08.200 --> 00:27:11.140 immense turmoil. That's one of the tragic parts 00:27:11.140 --> 00:27:13.599 of her story. Because of travel restrictions, 00:27:13.960 --> 00:27:16.579 she couldn't go back to mainland China until 00:27:16.579 --> 00:27:20.220 1973 after Nixon's visit started to open things 00:27:20.220 --> 00:27:22.740 up. And it was a difficult return. Heartbreaking. 00:27:22.960 --> 00:27:25.019 She learned that her uncle and her brother had 00:27:25.019 --> 00:27:27.559 died during the Cultural Revolution and her parents' 00:27:27.680 --> 00:27:30.500 tombs had been destroyed. It's a measure of her 00:27:30.500 --> 00:27:34.039 global stature, though, that the premier, Zhou 00:27:34.039 --> 00:27:37.460 Enlai, personally apologized to her for the destruction. 00:27:37.740 --> 00:27:40.759 As her career went on, she became much more outspoken, 00:27:40.759 --> 00:27:43.059 not just about science, but about social issues. 00:27:43.359 --> 00:27:45.299 She really started to leverage her scientific 00:27:45.299 --> 00:27:48.539 authority for advocacy. She successfully protested 00:27:48.539 --> 00:27:50.440 for the human rights of journalists and academics 00:27:50.440 --> 00:27:53.079 imprisoned in Taiwan, using her international 00:27:53.079 --> 00:27:55.400 reputation to pressure the government. And she 00:27:55.400 --> 00:27:57.579 spoke out forcefully against gender discrimination. 00:27:57.980 --> 00:28:00.140 Her most famous quote on that came at an MIT 00:28:00.140 --> 00:28:03.019 symposium in 1964. She just asked the audience, 00:28:03.160 --> 00:28:06.519 I wonder whether the tiny atoms and nuclei or 00:28:06.519 --> 00:28:08.680 the mathematical symbols or the DNA molecules 00:28:08.680 --> 00:28:11.880 have any preference for either masculine or feminine 00:28:11.880 --> 00:28:14.099 treatment. I read that it got huge applause. 00:28:14.420 --> 00:28:16.799 It did. It just perfectly captured the absurdity 00:28:16.799 --> 00:28:18.940 of gender bias in a field that's supposed to 00:28:18.940 --> 00:28:21.599 be purely about merit and intellect. She also 00:28:21.599 --> 00:28:24.500 insisted on being called Professor Wu, not Professor 00:28:24.500 --> 00:28:27.440 Yuan, her husband's name. She was very particular 00:28:27.440 --> 00:28:30.019 about that professional respect. And in 1975, 00:28:30.319 --> 00:28:33.500 the chairman of her department at Columbia realized 00:28:33.500 --> 00:28:36.339 she was being paid less than her male colleagues 00:28:36.339 --> 00:28:38.740 of the same rank, and he immediately fixed it. 00:28:38.819 --> 00:28:40.900 Her advocacy even reached the White House. It 00:28:40.900 --> 00:28:43.990 did. 1975, she became the first female president 00:28:43.990 --> 00:28:46.390 of the American Physical Society. And in that 00:28:46.390 --> 00:28:48.630 role, she formally asked President Gerald Ford 00:28:48.630 --> 00:28:51.430 to create a permanent scientific advisory body 00:28:51.430 --> 00:28:54.849 for the president. And he did it. He did. Ford 00:28:54.849 --> 00:28:57.269 signed a law creating the Office of Science and 00:28:57.269 --> 00:29:01.250 Technology Policy, the OSTP, which institutionalized 00:29:01.250 --> 00:29:03.490 scientific advice at the highest level of government. 00:29:03.930 --> 00:29:06.410 That's a direct result of her leadership. She 00:29:06.410 --> 00:29:09.549 retired in 1981, but her influence didn't wane. 00:29:10.000 --> 00:29:12.960 Her name was synonymous with quality. The director 00:29:12.960 --> 00:29:15.559 general of CERN said that if Wu didn't experiment, 00:29:15.940 --> 00:29:18.119 everyone in physics just believed it must be 00:29:18.119 --> 00:29:21.779 correct. Her reputation was truth. Maurice Goldhaber 00:29:21.779 --> 00:29:23.859 had that great quote about her. Oh, it's the 00:29:23.859 --> 00:29:27.079 best. He quipped that people avoid doing experiments 00:29:27.079 --> 00:29:29.880 in beta decay simply because they know that Wu 00:29:29.880 --> 00:29:31.900 Qiancheng will do a better job than anybody. 00:29:32.400 --> 00:29:34.339 That's the ultimate sign of respect from your 00:29:34.339 --> 00:29:37.200 peers. The honors she received are just incredible. 00:29:37.500 --> 00:29:39.839 First woman to get an honorary doctorate from 00:29:39.839 --> 00:29:41.980 Princeton, the National Medal of Science, induction 00:29:41.980 --> 00:29:44.440 into the National Women's Hall of Fame. And in 00:29:44.440 --> 00:29:47.319 2020, Time magazine finally named her Woman of 00:29:47.319 --> 00:29:50.039 the Year for 1945. For her role in the Manhattan 00:29:50.039 --> 00:29:52.619 Project, a long overdue recognition. And in the 00:29:52.619 --> 00:29:55.319 end, her story came full circle. It did. Her 00:29:55.319 --> 00:29:57.980 ashes were interred at the Mingda School in China, 00:29:58.220 --> 00:30:01.039 the very school her father founded for girls, 00:30:01.160 --> 00:30:03.920 where her whole journey began. So after this 00:30:03.920 --> 00:30:06.200 deep dive, What does it all mean? What's the 00:30:06.200 --> 00:30:09.359 big takeaway from her life and work? I think 00:30:09.359 --> 00:30:11.380 the sources show us she wasn't just a scientist. 00:30:11.440 --> 00:30:15.259 She was this force of nature, a triple threat. 00:30:15.599 --> 00:30:18.619 How so? Well, first, she was a scientific genius 00:30:18.619 --> 00:30:20.880 who dragged physics from the comfortable, elegant 00:30:20.880 --> 00:30:23.960 world of perfect symmetry into the more complex, 00:30:24.079 --> 00:30:26.140 more interesting reality of the standard model. 00:30:26.460 --> 00:30:29.160 Second. She was a pioneer who literally rescued 00:30:29.160 --> 00:30:31.579 a critical part of the war effort. with knowledge 00:30:31.579 --> 00:30:35.200 from her unpublished PhD thesis. And third, she 00:30:35.200 --> 00:30:37.380 was a fearless advocate who used the authority 00:30:37.380 --> 00:30:39.700 she earned in the lab to fight for human rights 00:30:39.700 --> 00:30:42.799 and for gender equality. Her entire legacy is 00:30:42.799 --> 00:30:45.940 this blend of unwavering precision and deep moral 00:30:45.940 --> 00:30:48.000 conviction. She looked at something everyone 00:30:48.000 --> 00:30:50.720 just assumed was a fundamental truth, the conservation 00:30:50.720 --> 00:30:53.140 of parity, and she had the courage and the skill 00:30:53.140 --> 00:30:55.119 to prove that the universe was actually more 00:30:55.119 --> 00:30:57.900 complicated and, frankly, more interesting than 00:30:57.900 --> 00:31:00.029 we had ever imagined. Which leaves us with a 00:31:00.029 --> 00:31:02.470 final, really provocative thought for you to 00:31:02.470 --> 00:31:05.170 consider. The discovery of parity violation meant 00:31:05.170 --> 00:31:07.650 that on a fundamental level, the universe literally 00:31:07.650 --> 00:31:10.789 distinguishes between left and right. That tiny 00:31:10.789 --> 00:31:13.230 asymmetry, that small preference, is the reason 00:31:13.230 --> 00:31:16.509 we exist. So, if the most fundamental rules that 00:31:16.509 --> 00:31:18.549 govern the smallest particles can be broken, 00:31:18.750 --> 00:31:21.529 what does that imply about all the other rules 00:31:21.529 --> 00:31:24.009 and assumed symmetries that govern our own reality? 00:31:24.670 --> 00:31:27.109 What other impossible symmetries, in physics, 00:31:27.269 --> 00:31:29.190 in biology, maybe even in our social structures, 00:31:29.369 --> 00:31:32.089 are just waiting out there for another meticulous, 00:31:32.089 --> 00:31:34.250 dedicated, and courageous experimentalist like 00:31:34.250 --> 00:31:36.589 Jianxiong Wu to come along and shatter them? 00:31:36.970 --> 00:31:39.630 It's a compelling thought to mull over as we 00:31:39.630 --> 00:31:41.589 move through a universe that, it turns out, just 00:31:41.589 --> 00:31:42.730 might have a preferred hand.