WEBVTT 00:00:00.000 --> 00:00:01.639 Welcome back to the Deep Dive. It's great to 00:00:01.639 --> 00:00:05.019 be here. Today we're pointing our lens, our most 00:00:05.019 --> 00:00:07.480 powerful lens, at a name that I think everyone 00:00:07.480 --> 00:00:10.099 knows. A name that's basically synonymous with 00:00:10.099 --> 00:00:12.839 space itself. Oh, absolutely. The Hubble Space 00:00:12.839 --> 00:00:15.300 Telescope. Exactly. But we're not just talking 00:00:15.300 --> 00:00:16.899 about the telescope. We're talking about the 00:00:16.899 --> 00:00:19.839 man, Edwin Hubble. And his personal story is 00:00:19.839 --> 00:00:24.879 just full of these incredible detours and remarkable 00:00:24.879 --> 00:00:27.699 turns. It really is. It's a common mistake to 00:00:27.699 --> 00:00:29.600 sort of conflate the man and the machine. But 00:00:29.600 --> 00:00:33.600 Edwin Hubble, the man, is, well, he's arguably 00:00:33.600 --> 00:00:36.100 the most important observational astronomer since 00:00:36.100 --> 00:00:38.799 Galileo. That's a huge statement. Since Galileo. 00:00:38.820 --> 00:00:40.399 I think it holds up. You have to understand, 00:00:40.539 --> 00:00:44.280 before his work. Our own galaxy, the Milky Way, 00:00:44.420 --> 00:00:46.799 was the entire cosmos. That was it. The whole 00:00:46.799 --> 00:00:49.780 universe. The whole thing. After him, we suddenly 00:00:49.780 --> 00:00:52.399 lived in this vast ocean of billions of other 00:00:52.399 --> 00:00:55.619 galaxies. He laid the groundwork, the observational 00:00:55.619 --> 00:00:58.359 foundation, for what we now call modern cosmology 00:00:58.359 --> 00:01:01.229 and extragalactic astronomy. Okay, so let's unpack 00:01:01.229 --> 00:01:04.670 that. That is a monumental legacy. Our mission 00:01:04.670 --> 00:01:08.069 for this deep dive is to synthesize his life 00:01:08.069 --> 00:01:12.109 and the foundational discoveries that really 00:01:12.109 --> 00:01:14.329 made that transformation possible. We've got 00:01:14.329 --> 00:01:16.590 our shared sources here, and they detail his, 00:01:16.730 --> 00:01:20.189 well, highly unusual path to science, some crucial 00:01:20.189 --> 00:01:22.709 detours during wartime, and most importantly, 00:01:22.950 --> 00:01:25.969 two primary revolutionary scientific discoveries. 00:01:26.209 --> 00:01:28.730 That's right. The first one is maybe the easiest 00:01:28.730 --> 00:01:31.760 to grasp. But it's no less profound. It's the 00:01:31.760 --> 00:01:35.739 conclusive proof that those nebulae, those fuzzy 00:01:35.739 --> 00:01:37.620 patches in the sky. Yeah, that everyone thought 00:01:37.620 --> 00:01:40.420 were just gas clouds. Exactly. He proved they 00:01:40.420 --> 00:01:42.239 weren't gas clouds inside our galaxy at all. 00:01:42.340 --> 00:01:44.739 They were entirely separate stellar systems, 00:01:44.819 --> 00:01:48.260 other galaxies, far, far outside the Milky Way. 00:01:48.420 --> 00:01:50.340 And the second discovery, which really launched 00:01:50.340 --> 00:01:52.819 us into the Big Bang era, is the empirical proof 00:01:52.819 --> 00:01:55.459 of what we now call Hubble's Law. The stunningly 00:01:55.459 --> 00:01:58.239 simple linear relationship between a galaxy's 00:01:58.239 --> 00:02:00.099 distance from us and its apparent speed moving 00:02:00.099 --> 00:02:02.780 away from us this was the first real observation 00:02:02.780 --> 00:02:05.120 that implied the expansion of the entire universe 00:02:05.120 --> 00:02:09.439 though as we'll get into hubble himself was famously 00:02:09.439 --> 00:02:13.219 and perhaps surprisingly skeptical of that interpretation 00:02:13.219 --> 00:02:15.860 he was and we absolutely have to explore that 00:02:15.860 --> 00:02:18.900 along with the complex history and you know the 00:02:18.900 --> 00:02:20.900 controversies around who discovered what first 00:02:20.900 --> 00:02:23.580 it's a fascinating story It seems like it's essential 00:02:23.580 --> 00:02:25.560 because his personal history really provides 00:02:25.560 --> 00:02:27.680 the context for his scientific rigor, doesn't 00:02:27.680 --> 00:02:30.240 it? It absolutely does. Before Hubble became 00:02:30.240 --> 00:02:33.099 the man who expanded the universe, he was a star 00:02:33.099 --> 00:02:35.360 athlete and, believe it or not, a reluctant law 00:02:35.360 --> 00:02:38.099 student. The journey to the top of Mount Wilson 00:02:38.099 --> 00:02:40.340 and that 100 -inch telescope was anything but 00:02:40.340 --> 00:02:42.159 a straight line. Okay, let's start there. Let's 00:02:42.159 --> 00:02:44.340 start with the unexpected prodigy. Edwin Powell 00:02:44.340 --> 00:02:47.860 Hubble, born 1889, Marshfield, Missouri. His 00:02:47.860 --> 00:02:52.419 family moves to Illinois in 1900. Mm -hmm. And 00:02:52.419 --> 00:02:54.560 when you look at his early years, high school, 00:02:54.680 --> 00:02:58.060 college, the sources are overwhelming. He was 00:02:58.060 --> 00:03:00.319 famous for being physically dominant, not some 00:03:00.319 --> 00:03:02.599 kind of intellectual prodigy. Right, which is 00:03:02.599 --> 00:03:05.240 so counterintuitive for a figure like this. What's 00:03:05.240 --> 00:03:07.099 fascinating is that the records actually highlight 00:03:07.099 --> 00:03:09.120 his spelling issues, which is a surprisingly 00:03:09.120 --> 00:03:12.240 human detail for a cosmic giant. I love that. 00:03:12.400 --> 00:03:14.180 But otherwise, he was a great student. It's just 00:03:14.180 --> 00:03:16.599 that the public recognition, the fame, it was 00:03:16.599 --> 00:03:18.780 all about his physical prowess. He was a phenomenon 00:03:18.780 --> 00:03:21.520 in high school sports. And that physical discipline, 00:03:21.599 --> 00:03:24.879 you can see how he later translated it into astronomical 00:03:24.879 --> 00:03:27.080 dedication. And we're not just talking about, 00:03:27.080 --> 00:03:28.800 you know, playing on a team. We're talking about 00:03:28.800 --> 00:03:32.789 elite. truly dominant performance. Oh, absolutely. 00:03:32.969 --> 00:03:35.129 The sources say he excelled in baseball, football, 00:03:35.250 --> 00:03:37.710 and track and field. This wasn't a hobby. This 00:03:37.710 --> 00:03:40.409 speaks to a kind of underlying drive and focus 00:03:40.409 --> 00:03:42.990 that's just off the charts. You give us an example. 00:03:43.229 --> 00:03:44.849 Well, there's this one detail that just jumps 00:03:44.849 --> 00:03:48.050 out. At a single high school track meet in 1906, 00:03:48.349 --> 00:03:52.659 one meet. He won seven first place finishes and 00:03:52.659 --> 00:03:55.340 a third place. Seven firsts in one day. In one 00:03:55.340 --> 00:03:58.020 day. Think about the sheer scale of that in all 00:03:58.020 --> 00:03:59.860 these different disciplines, running, jumping, 00:04:00.120 --> 00:04:03.259 throwing. It's just a hyper -focused, incredibly 00:04:03.259 --> 00:04:06.469 driven personality. And he carried that right 00:04:06.469 --> 00:04:08.669 into college at the University of Chicago. He 00:04:08.669 --> 00:04:11.090 wasn't just on the basketball team. No, he was 00:04:11.090 --> 00:04:13.490 leading it. He played multiple positions, center, 00:04:13.669 --> 00:04:16.350 shooting guard, whatever was needed. And in 1907, 00:04:16.490 --> 00:04:19.350 he led the university's team to their first ever 00:04:19.350 --> 00:04:22.610 Big Ten conference title. It's just a bizarre 00:04:22.610 --> 00:04:25.389 juxtaposition, isn't it? You have... one of the 00:04:25.389 --> 00:04:27.670 foundational figures of 20th century science. 00:04:27.889 --> 00:04:30.529 And at the same time, he's a Big Ten basketball 00:04:30.529 --> 00:04:33.370 champion. It is strange, but I think that competitive 00:04:33.370 --> 00:04:35.730 rigor, that ability to perform under pressure 00:04:35.730 --> 00:04:38.730 and just focus on a goal, that's the same trait 00:04:38.730 --> 00:04:41.430 we see resurface years later when he's locked 00:04:41.430 --> 00:04:44.129 in the freezing cold dome at Mount Wilson, staring 00:04:44.129 --> 00:04:46.629 through an eyepiece for hours. That makes sense. 00:04:47.009 --> 00:04:49.670 The discipline to endure those long nights of 00:04:49.670 --> 00:04:51.709 observation is probably the same kind of mental 00:04:51.709 --> 00:04:53.610 muscle you need for high -level athletics. I 00:04:53.610 --> 00:04:56.439 think so, yes. But okay. Despite this huge focus 00:04:56.439 --> 00:04:59.639 on sports, his academic interests were still 00:04:59.639 --> 00:05:02.459 pointing in the right direction. His undergraduate 00:05:02.459 --> 00:05:05.399 studies were in mathematics, astronomy, and philosophy. 00:05:05.579 --> 00:05:08.079 Right, so the intellectual foundation was definitely 00:05:08.079 --> 00:05:10.800 being built. He got his Bachelor of Science in 00:05:10.800 --> 00:05:13.779 1910. And there's another really important connection 00:05:13.779 --> 00:05:16.360 here that often gets missed. What's that? His 00:05:16.360 --> 00:05:19.339 exposure to truly rigorous experimental physics. 00:05:20.040 --> 00:05:22.939 For a year during his undergrad, Hubble served 00:05:22.939 --> 00:05:25.379 as a student laboratory assistant for Robert 00:05:25.379 --> 00:05:27.920 Millikan. Wow. Robert Millikan, who, of course, 00:05:27.959 --> 00:05:31.180 went on to win the Nobel Prize for his oil drop 00:05:31.180 --> 00:05:34.199 experiment for measuring the charge of an electron. 00:05:34.560 --> 00:05:37.240 The very same. Yeah. That experience had to have 00:05:37.240 --> 00:05:40.579 profoundly shaped Hubble's methodology. It would 00:05:40.579 --> 00:05:43.540 have emphasized precise measurement, empirical 00:05:43.540 --> 00:05:46.139 evidence above all the theoretical guesswork. 00:05:46.300 --> 00:05:48.279 It must have embedded this philosophy of show 00:05:48.279 --> 00:05:50.560 me the data. Absolutely. He was learning from 00:05:50.560 --> 00:05:52.540 one of the best experimentalists on the planet 00:05:52.540 --> 00:05:54.800 how to design observations that minimized error 00:05:54.800 --> 00:05:57.800 and maximize certainty. That training is so crucial 00:05:57.800 --> 00:06:00.319 because later in his life, Hubble becomes the 00:06:00.319 --> 00:06:03.500 ultimate empiricist. He trusts what he observes 00:06:03.500 --> 00:06:05.459 through the telescope far more than what any 00:06:05.459 --> 00:06:07.980 theorist predicts on a blackboard but then right 00:06:07.980 --> 00:06:10.540 when he's on this path comes this huge confusing 00:06:10.540 --> 00:06:13.740 detour the promise and the pivot his path was 00:06:13.740 --> 00:06:16.160 just abruptly shifted by a promise he made to 00:06:16.160 --> 00:06:19.019 his dying father right his father passed away 00:06:19.019 --> 00:06:22.899 in 1913 and hubble feeling this deep sense of 00:06:22.899 --> 00:06:26.199 duty followed his father's wish that he pursues 00:06:26.199 --> 00:06:29.480 a career in law So this leads him to accept a 00:06:29.480 --> 00:06:32.160 Rhodes Scholarship. At the Queen's College, Oxford. 00:06:32.319 --> 00:06:34.939 And instead of focusing on physics or astronomy, 00:06:35.139 --> 00:06:38.079 which was clearly his passion, he studies jurisprudence. 00:06:38.220 --> 00:06:41.339 Law school in England. It seems so completely 00:06:41.339 --> 00:06:44.079 opposed to celestial mechanics. It was a total 00:06:44.079 --> 00:06:46.040 abandonment of his passion, at least for a time. 00:06:46.220 --> 00:06:48.459 While he was there, he did broaden his studies. 00:06:48.500 --> 00:06:50.959 He added literature and Spanish, eventually got 00:06:50.959 --> 00:06:53.959 an MA degree. But the core focus was legal training. 00:06:54.620 --> 00:06:56.839 It's just hard to imagine the man who discovered 00:06:56.839 --> 00:06:59.360 the expanding universe arguing torts. It really 00:06:59.360 --> 00:07:02.019 is. Though maybe that legal training, that focus 00:07:02.019 --> 00:07:04.480 on evidence and logical argument, maybe that 00:07:04.480 --> 00:07:07.319 subtly reinforced his scientific approach. That's 00:07:07.319 --> 00:07:09.160 a great point. It's all about examining evidence, 00:07:09.399 --> 00:07:11.620 building a case, and avoiding claims you can't 00:07:11.620 --> 00:07:13.660 substantiate. That's good science and it's good 00:07:13.660 --> 00:07:15.980 law. So when he comes back to the Midwest after 00:07:15.980 --> 00:07:19.000 his father's death, his lack of passion for law 00:07:19.000 --> 00:07:23.620 becomes, well, pretty obvious. His actions speak 00:07:23.620 --> 00:07:26.240 volumes. Instead of opening a legal practice, 00:07:26.579 --> 00:07:29.100 he takes what you might call a teaching interlude. 00:07:29.360 --> 00:07:33.079 He ends up teaching Spanish, physics, and math 00:07:33.079 --> 00:07:35.660 at a high school in Indiana. New Albany High 00:07:35.660 --> 00:07:38.920 School. And, of course. And, of course, he coached 00:07:38.920 --> 00:07:40.600 the boys' basketball team. You can't keep him 00:07:40.600 --> 00:07:43.040 away from the court. It's just a wonderful image, 00:07:43.180 --> 00:07:46.360 isn't it? The future titan of cosmology explaining 00:07:46.360 --> 00:07:49.579 the quadratic formula and then diagramming a 00:07:49.579 --> 00:07:51.779 pick -and -roll play. It is. But thankfully for 00:07:51.779 --> 00:07:53.600 the history of science, this was a very short 00:07:53.600 --> 00:07:55.839 -lived phase. Right. This period probably just 00:07:55.839 --> 00:07:58.360 solidified for him how much he wanted to be doing 00:07:58.360 --> 00:08:01.079 research. I think so. And the academic community 00:08:01.079 --> 00:08:03.199 saw it too. A former professor from the University 00:08:03.199 --> 00:08:05.899 of Chicago basically intervened, using Hubble's 00:08:05.899 --> 00:08:08.319 clear talent to guide him back onto the scientific 00:08:08.319 --> 00:08:10.959 track. And that brings us to his formal return 00:08:10.959 --> 00:08:13.660 to astronomy. He enters graduate school at the 00:08:13.660 --> 00:08:16.519 University of Chicago's Yerkes Observatory. And 00:08:16.519 --> 00:08:19.519 this time, the focus is absolute. He earns his 00:08:19.519 --> 00:08:22.980 Ph .D. in 1921. And listen to the title of his 00:08:22.980 --> 00:08:26.060 dissertation, Photographic Investigations of 00:08:26.060 --> 00:08:29.540 Faint Nebulae. It's prophetic. It's the exact 00:08:29.540 --> 00:08:32.340 subject that would define his entire life's work. 00:08:32.879 --> 00:08:35.659 His intention was already centered on figuring 00:08:35.659 --> 00:08:38.500 out what those fuzzy patches really were. Precisely. 00:08:38.500 --> 00:08:41.000 What was it about Yerkes Observatory that made 00:08:41.000 --> 00:08:42.899 it the perfect place for him to start this work? 00:08:43.059 --> 00:08:45.580 What kind of tools did they have? Yerkes was 00:08:45.580 --> 00:08:48.500 a world -class institution established by George 00:08:48.500 --> 00:08:51.139 Ellery Hale, a name we'll hear again. It had 00:08:51.139 --> 00:08:54.100 groundbreaking equipment. The most famous instrument 00:08:54.100 --> 00:08:56.720 was the 40 -inch refractor telescope, which was 00:08:56.720 --> 00:08:59.799 enormous. But critically, he also got experience 00:08:59.799 --> 00:09:02.730 with an innovative... 26 -inch reflector telescope. 00:09:03.149 --> 00:09:05.750 And reflectors, which use mirrors instead of 00:09:05.750 --> 00:09:08.370 lenses, are much better for capturing the incredibly 00:09:08.370 --> 00:09:10.409 faint light you need for deep sky photography. 00:09:10.870 --> 00:09:13.750 That gave him a crucial skill set. And just as 00:09:13.750 --> 00:09:15.889 his academic path is getting back on track, it's 00:09:15.889 --> 00:09:18.009 interrupted again by a global conflict, World 00:09:18.009 --> 00:09:20.769 War I. Yes, he actually rushes to finish his 00:09:20.769 --> 00:09:22.809 Ph .D. requirements so he can enlist in the U 00:09:22.809 --> 00:09:25.529 .S. Army. He was commissioned into the 86th Division, 00:09:25.789 --> 00:09:28.529 rises to the rank of major, which again speaks 00:09:28.529 --> 00:09:31.090 to his leadership abilities. Absolutely. The 00:09:31.090 --> 00:09:34.289 division was sent overseas in 1918, but the armistice 00:09:34.289 --> 00:09:37.509 was signed soon after. So our sources say that 00:09:37.509 --> 00:09:39.730 while some of the personnel were used as replacements 00:09:39.730 --> 00:09:42.769 elsewhere, the 86th Division itself never actually 00:09:42.769 --> 00:09:45.730 saw combat. So he served honorably. He got the 00:09:45.730 --> 00:09:48.370 distinction of being a major. But his observational 00:09:48.370 --> 00:09:51.169 career was able to begin pretty much right after 00:09:51.169 --> 00:09:53.450 the war ended. Exactly. And there's one more 00:09:53.450 --> 00:09:56.309 crucial detail. After the war, he actually spent 00:09:56.309 --> 00:09:59.090 a year in the UK at Cambridge sort of reengaging 00:09:59.090 --> 00:10:01.549 with his scientific studies before he accepted 00:10:01.549 --> 00:10:03.789 the one offer that would change astronomy forever. 00:10:04.269 --> 00:10:07.690 The year 1919. This is the pivot point. This 00:10:07.690 --> 00:10:09.590 is the moment Edwin Hubble meets the instrument 00:10:09.590 --> 00:10:12.470 that will define his legacy. The call to California. 00:10:12.750 --> 00:10:15.710 That call came directly from George Ellery Hale, 00:10:15.830 --> 00:10:18.669 the man who built Yerkes. Hale was now the founder 00:10:18.669 --> 00:10:20.929 and director of the Carnegie Institution's Mount 00:10:20.929 --> 00:10:23.730 Wilson Observatory. He recognized Hubble's talent. 00:10:24.009 --> 00:10:27.789 He saw Hubble's rigor and his potential and offered 00:10:27.789 --> 00:10:30.710 him a staff position. Hubble accepted, and he 00:10:30.710 --> 00:10:33.490 stayed at Mount Wilson until he died in 1953. 00:10:33.970 --> 00:10:38.149 And his timing was just perfect. His arrival 00:10:38.149 --> 00:10:40.870 lined up exactly with the completion of the most 00:10:40.870 --> 00:10:43.590 powerful observational tool in human history 00:10:43.590 --> 00:10:46.169 up to that point. It was the perfect storm of 00:10:46.169 --> 00:10:49.470 talent meeting opportunity. The 100 -inch or 00:10:49.470 --> 00:10:53.070 2 .5 -meter Hooker telescope had just been completed. 00:10:53.289 --> 00:10:55.250 And to put that in context... This was the world's 00:10:55.250 --> 00:10:57.929 largest telescope for decades. It gathered so 00:10:57.929 --> 00:11:00.289 much more light than any previous instrument. 00:11:00.389 --> 00:11:03.009 It offered the resolution you needed to finally 00:11:03.009 --> 00:11:05.889 distinguish faint individual stars inside those 00:11:05.889 --> 00:11:08.289 distant nebulae. Without the Hooker telescope, 00:11:08.590 --> 00:11:10.289 Hubble's work would have been impossible. They 00:11:10.289 --> 00:11:12.409 would have just remained fuzzy patches. The 100 00:11:12.409 --> 00:11:15.169 -inch Hooker was his work... It enabled both 00:11:15.169 --> 00:11:16.629 of the revolutionary discoveries we're going 00:11:16.629 --> 00:11:19.230 to talk about. But he didn't stop there. He was 00:11:19.230 --> 00:11:21.309 always at the cutting edge. Absolutely. He was 00:11:21.309 --> 00:11:23.509 always pushing the limits. Shortly before his 00:11:23.509 --> 00:11:26.070 death in 1953, he became the first astronomer 00:11:26.070 --> 00:11:29.029 to use the brand new, even bigger, 200 -inch 00:11:29.029 --> 00:11:31.789 Hale telescope at Palomar Observatory. So there's 00:11:31.789 --> 00:11:34.929 this incredible historical symmetry. His career 00:11:34.929 --> 00:11:38.070 is basically defined by his use of the two most 00:11:38.070 --> 00:11:40.090 powerful instruments built in the first half 00:11:40.090 --> 00:11:42.970 of the 20th century. It is a perfect alignment. 00:11:43.519 --> 00:11:45.480 Okay, let's pivot back now to another one of 00:11:45.480 --> 00:11:48.799 those surprising detours. It really proves the 00:11:48.799 --> 00:11:52.899 versatility of his mind. His skills were so transferable 00:11:52.899 --> 00:11:55.679 that they became vital during the next global 00:11:55.679 --> 00:11:58.360 conflict, World War II. This is a really remarkable 00:11:58.360 --> 00:12:02.009 chapter. During the war... Hubble puts his astronomy 00:12:02.009 --> 00:12:05.289 career on hold and serves as a civilian at the 00:12:05.289 --> 00:12:07.929 U .S. Army's Aberdeen Proving Ground in Maryland. 00:12:08.149 --> 00:12:10.570 He goes from tracking distant galaxies to... 00:12:10.570 --> 00:12:13.330 To tracking high -velocity projectiles. He was 00:12:13.330 --> 00:12:15.509 the chief of the external ballistics branch of 00:12:15.509 --> 00:12:17.710 the Ballistic Research Laboratory. Ballistics, 00:12:17.929 --> 00:12:20.370 the physics of projectiles in flight. It seems 00:12:20.370 --> 00:12:22.509 like a world away from extragalactic astronomy. 00:12:22.830 --> 00:12:25.389 It does, but the underlying skills of observation, 00:12:25.769 --> 00:12:28.330 precise measurement, and calculation are identical. 00:12:28.809 --> 00:12:30.710 That's the key connection. So what was his job? 00:12:31.100 --> 00:12:33.460 He was directing huge amounts of research focused 00:12:33.460 --> 00:12:36.940 on exterior ballistics. His mandate was to apply 00:12:36.940 --> 00:12:40.080 scientific rigor to increase the effective firepower 00:12:40.080 --> 00:12:43.539 of bombs, rockets, and other projectiles. It 00:12:43.539 --> 00:12:46.500 required incredibly detailed high -speed observation 00:12:46.500 --> 00:12:49.159 under very difficult conditions. And he didn't 00:12:49.159 --> 00:12:51.340 just manage the research. He actually used his 00:12:51.340 --> 00:12:54.120 training in optics and photography to invent 00:12:54.120 --> 00:12:57.159 new tools for this. He was a true innovator in 00:12:57.159 --> 00:12:59.100 the lab, just like he was on the mountaintop. 00:12:59.399 --> 00:13:01.620 The most outstanding development that's credited 00:13:01.620 --> 00:13:04.080 to him from this period was the high -speed clock 00:13:04.080 --> 00:13:07.019 camera. A clock camera. That implies extremely 00:13:07.019 --> 00:13:09.840 precise timing. Exactly, which is critical for 00:13:09.840 --> 00:13:11.879 measuring the trajectory and speed of ordnance. 00:13:12.350 --> 00:13:14.909 This invention was a game changer. What did it 00:13:14.909 --> 00:13:17.289 allow them to do? It allowed researchers to precisely 00:13:17.289 --> 00:13:19.889 study the flight characteristics of bombs and 00:13:19.889 --> 00:13:22.509 low -velocity projectiles. By capturing their 00:13:22.509 --> 00:13:24.870 exact movements, their rotation, their stability 00:13:24.870 --> 00:13:27.009 in flight with extremely high time resolution, 00:13:27.370 --> 00:13:29.909 they could gather the empirical data they needed 00:13:29.909 --> 00:13:32.070 to redesign the ordnance for better accuracy 00:13:32.070 --> 00:13:34.389 and performance. So he took the observational 00:13:34.389 --> 00:13:36.970 rigor he used to measure the expansion of space. 00:13:37.389 --> 00:13:40.190 And applied it to the expansion of military might. 00:13:40.639 --> 00:13:43.379 The results of his studies were explicitly credited 00:13:43.379 --> 00:13:45.639 with improving the design and effectiveness of 00:13:45.639 --> 00:13:48.779 the nation's ordinance. It was high impact, practical 00:13:48.779 --> 00:13:51.340 physics, a world away from the philosophical 00:13:51.340 --> 00:13:54.960 debates of cosmology. And this work earned him 00:13:54.960 --> 00:13:58.889 significant recognition. It did. In 1946, he 00:13:58.889 --> 00:14:01.750 received the Legion of Merit Award for his distinguished 00:14:01.750 --> 00:14:05.169 civilian service. It just highlights the incredible 00:14:05.169 --> 00:14:08.370 breadth of his genius. He was capable of calculating 00:14:08.370 --> 00:14:11.070 the size of the universe and, at the same time, 00:14:11.110 --> 00:14:13.850 optimizing the aerodynamics of a bomb. Okay, 00:14:13.909 --> 00:14:15.990 let's return to Mount Wilson and to the work 00:14:15.990 --> 00:14:18.370 that truly defined him. We need to set the scene 00:14:18.370 --> 00:14:21.769 here. Before the 1920s, the astronomical community 00:14:21.769 --> 00:14:23.669 was in the middle of what's often called the 00:14:23.669 --> 00:14:26.440 Great Debate. What was that about? The core of 00:14:26.440 --> 00:14:28.399 the debate was about the size of the universe. 00:14:28.659 --> 00:14:31.399 The established scientific view, which was championed 00:14:31.399 --> 00:14:33.580 by figures like Harlow Shapley, was that the 00:14:33.580 --> 00:14:36.179 entire cosmos was contained within our own Milky 00:14:36.179 --> 00:14:38.019 Way galaxy. That was it. That was the universe. 00:14:38.340 --> 00:14:40.679 That was the universe. And all those blurry, 00:14:40.759 --> 00:14:43.039 fuzzy patches you could see in telescopes, the 00:14:43.039 --> 00:14:46.519 nebulae, like Andromeda, they were believed to 00:14:46.519 --> 00:14:49.659 be gas clouds or maybe forming star systems, 00:14:49.860 --> 00:14:53.700 but inside our galaxy. Distant, but internal. 00:14:54.440 --> 00:14:56.080 It's important to note, though, that the idea 00:14:56.080 --> 00:14:59.620 of external galaxies or island universes wasn't 00:14:59.620 --> 00:15:02.860 new. Immanuel Kant had suggested it back in 1755. 00:15:03.159 --> 00:15:05.100 Right. But without empirical proof, it was just 00:15:05.100 --> 00:15:07.340 philosophy. That is the crucial distinction here. 00:15:07.539 --> 00:15:09.460 Hubble is the one who turned that philosophy 00:15:09.460 --> 00:15:12.740 into hard observational fact. And to do that, 00:15:12.779 --> 00:15:15.419 he needed a reliable measuring stick for cosmic 00:15:15.419 --> 00:15:18.740 distance. And that stick was the cepheid variable 00:15:18.740 --> 00:15:21.440 star. Exactly. Can you walk us through the genius 00:15:21.440 --> 00:15:24.220 of using cepheids? They were discovered by Henrietta 00:15:24.220 --> 00:15:27.200 Swan Leavitt in 1908. How do they work as a standard 00:15:27.200 --> 00:15:29.019 candle? Cepheid variables are extraordinary. 00:15:29.179 --> 00:15:31.460 They're a type of star that pulsates, it regularly 00:15:31.460 --> 00:15:34.299 expands and contracts, and that causes its brightness 00:15:34.299 --> 00:15:36.940 to oscillate, to go up and down. Leavitt's brilliant 00:15:36.940 --> 00:15:39.379 discovery was that there is a direct lockstep 00:15:39.379 --> 00:15:42.059 relationship between how long it takes for the 00:15:42.059 --> 00:15:44.879 star to complete one pulsation cycle, its period, 00:15:45.139 --> 00:15:48.330 and how bright that star truly is. its intrinsic 00:15:48.330 --> 00:15:50.669 luminosity. So the longer the period, the brighter 00:15:50.669 --> 00:15:52.889 the star. Exactly. So they become a standard 00:15:52.889 --> 00:15:55.350 candle. Because as soon as you measure the period 00:15:55.350 --> 00:15:57.909 of its pulse, which is easy to do, you know its 00:15:57.909 --> 00:15:59.509 inherent brightness. You know how bright it's 00:15:59.509 --> 00:16:01.450 supposed to be. Okay, so if you know how bright 00:16:01.450 --> 00:16:04.090 the star should be, and you measure how dim it 00:16:04.090 --> 00:16:06.529 appears from Earth, the difference is purely 00:16:06.529 --> 00:16:09.570 a function of distance. The dimmer it is, the 00:16:09.570 --> 00:16:11.909 farther away it must be. Precisely. It's a simple 00:16:11.909 --> 00:16:14.029 geometric principle. The challenge was applying 00:16:14.029 --> 00:16:16.399 it. The older telescopes just couldn't gather 00:16:16.399 --> 00:16:19.019 enough light to resolve these individual, very 00:16:19.019 --> 00:16:21.679 faint, sephiide stars in those distant nebulae. 00:16:21.740 --> 00:16:24.539 The 100 -inch Hooker telescope was the first 00:16:24.539 --> 00:16:26.700 instrument powerful enough to do it. And this 00:16:26.700 --> 00:16:30.379 brings us to the great revelation of 1924. Hubble 00:16:30.379 --> 00:16:32.940 is meticulously photographing Andromeda, the 00:16:32.940 --> 00:16:35.620 Triangulum Nebula. What happens when he finally 00:16:35.620 --> 00:16:38.720 finds and measures a septide in Andromeda? In 00:16:38.720 --> 00:16:42.340 late 1923 and early 1924, he finally manages 00:16:42.340 --> 00:16:45.379 to resolve individual stars and confirm a Cepheid 00:16:45.379 --> 00:16:47.919 in what was then called the Andromeda Nebula. 00:16:48.159 --> 00:16:51.960 He famously scrawled VAR for variable right next 00:16:51.960 --> 00:16:54.039 to the star on his photographic plate. And then 00:16:54.039 --> 00:16:56.139 he measured its period. The distance calculation 00:16:56.139 --> 00:16:59.200 must have been instantly shocking. It was. When 00:16:59.200 --> 00:17:01.299 he plugged the numbers into the period luminosity 00:17:01.299 --> 00:17:03.860 formula, the calculated distance was staggering. 00:17:04.099 --> 00:17:07.059 It was millions of light years away. At the time, 00:17:07.079 --> 00:17:09.079 the entire Milky Way was thought to be maybe 00:17:09.079 --> 00:17:11.519 a few hundred thousand light years across. This 00:17:11.519 --> 00:17:14.059 object was far, far outside the known boundary 00:17:14.059 --> 00:17:16.839 of our galaxy. So that single observation proved, 00:17:17.180 --> 00:17:19.720 conclusively, that the Andromeda Nebula was not 00:17:19.720 --> 00:17:22.339 a nebula at all. It was a separate, colossal 00:17:22.339 --> 00:17:25.299 collection of stars. An entire galaxy outside 00:17:25.299 --> 00:17:27.880 our own. It dismantled the existing cosmological 00:17:27.880 --> 00:17:30.559 model overnight. The universe instantly expanded 00:17:30.559 --> 00:17:33.000 from one single stellar system, the Milky Way, 00:17:33.160 --> 00:17:36.039 to this vast, multi -galactic archipelago. It 00:17:36.039 --> 00:17:38.619 is the definition of a scientific paradigm shift. 00:17:38.799 --> 00:17:41.660 This was seismic news, and it faced strong resistance 00:17:41.660 --> 00:17:43.859 from the old guard, didn't it? Particularly from 00:17:43.859 --> 00:17:46.079 Harlow Shapley at Harvard. Oh, the resistance 00:17:46.079 --> 00:17:49.339 was fierce. Shapley's model of the Milky Way 00:17:49.339 --> 00:17:51.640 was the established view, and Hubble's finding 00:17:51.640 --> 00:17:54.660 completely undermined it. But the empirical evidence 00:17:54.660 --> 00:17:57.539 from Mount Wilson was just too robust to ignore. 00:17:57.779 --> 00:18:00.000 And Hubble, interestingly, took his findings 00:18:00.000 --> 00:18:02.789 to the public. pretty quickly. He did. His findings 00:18:02.789 --> 00:18:04.670 for Andromeda were first published in the New 00:18:04.670 --> 00:18:08.569 York Times on November 23rd, 1924. It ensured 00:18:08.569 --> 00:18:10.369 immediate public awareness that the universe 00:18:10.369 --> 00:18:12.829 had just gotten a whole lot bigger. And then 00:18:12.829 --> 00:18:14.809 he presented the results formally to the American 00:18:14.809 --> 00:18:18.910 Astronomical Society on January 1st, 1925. And 00:18:18.910 --> 00:18:21.430 that cemented it. He was the man who discovered 00:18:21.430 --> 00:18:24.369 the external galaxies. The speed at which this 00:18:24.369 --> 00:18:26.630 discovery changed the course of science is almost 00:18:26.630 --> 00:18:29.490 unprecedented. And beyond just proving they existed. 00:18:29.980 --> 00:18:32.579 Hubble brought order to this new cosmic zoo. 00:18:32.759 --> 00:18:35.460 He created a classification system. That's right, 00:18:35.500 --> 00:18:38.039 the Hubble sequence. It's often visualized as 00:18:38.039 --> 00:18:40.730 the tuning fork diagram. He categorized galaxies 00:18:40.730 --> 00:18:43.430 based on how they looked, their morphology. You 00:18:43.430 --> 00:18:45.589 had ellipticals, which were smooth and featureless, 00:18:45.789 --> 00:18:49.009 spirals with their beautiful arms, barred spirals, 00:18:49.009 --> 00:18:51.130 which have a central bar structure, and then 00:18:51.130 --> 00:18:54.069 irregulars. And that classification system is 00:18:54.069 --> 00:18:55.930 still the foundation we use today, isn't it? 00:18:56.009 --> 00:18:58.589 It is. Despite all the refinements over the years, 00:18:58.670 --> 00:19:00.789 it's still the fundamental taxonomy for galaxies. 00:19:01.269 --> 00:19:04.130 He didn't just find new things. He started organizing 00:19:04.130 --> 00:19:06.589 the cosmic map for everyone who came after him. 00:19:06.769 --> 00:19:09.029 Okay, so once Hubble established these vast... 00:19:09.069 --> 00:19:12.069 distances, the next crucial question was how 00:19:12.069 --> 00:19:15.069 are these massive structures moving relative 00:19:15.069 --> 00:19:17.970 to us? And this leads to his second monumental 00:19:17.970 --> 00:19:21.349 discovery. The expanding universe. This stage 00:19:21.349 --> 00:19:23.789 required synthesizing two different sets of data. 00:19:24.309 --> 00:19:27.210 First, Hubble and his team, using the suffade 00:19:27.210 --> 00:19:30.230 method and other techniques, painstakingly estimated 00:19:30.230 --> 00:19:32.869 the distances to dozens of these new galaxies. 00:19:33.170 --> 00:19:36.250 By 1929, he had distance estimates for about 00:19:36.250 --> 00:19:38.750 24 of them. So he had the distance part of the 00:19:38.750 --> 00:19:40.750 equation. Where did the velocity part come from? 00:19:40.930 --> 00:19:43.400 That came from pre -existing work. The crucial 00:19:43.400 --> 00:19:45.779 velocity data came from measurements of what's 00:19:45.779 --> 00:19:48.079 called radial velocity, the motion along our 00:19:48.079 --> 00:19:50.019 line of sight. Which you measure from redshift. 00:19:50.430 --> 00:19:52.970 Exactly. And those redshift measurements were 00:19:52.970 --> 00:19:55.710 done primarily by an astronomer named Avesto 00:19:55.710 --> 00:19:58.609 Slipher at the Lowell Observatory. Slipher had 00:19:58.609 --> 00:20:01.109 been observing these nebulae for years and found 00:20:01.109 --> 00:20:03.309 that the vast majority of them were redshifted. 00:20:03.390 --> 00:20:05.490 Meaning they were moving away from us at tremendous 00:20:05.490 --> 00:20:08.910 speeds. At incredible speeds. Hubble relied heavily 00:20:08.910 --> 00:20:11.430 on Slipher's work and later on measurements by 00:20:11.430 --> 00:20:14.109 his own assistant, Milton Humison, to get the 00:20:14.109 --> 00:20:16.809 velocity for each galaxy. So he takes his distances 00:20:16.809 --> 00:20:19.920 and he plots them against the velocity. from 00:20:19.920 --> 00:20:22.380 Slipher and Humason. And what did that graph 00:20:22.380 --> 00:20:25.779 look like in 1929? The result was an elegant, 00:20:25.859 --> 00:20:29.319 terrifyingly simple straight line, a linear relationship. 00:20:29.859 --> 00:20:33.119 This became Hubble's law. It states that a galaxy's 00:20:33.119 --> 00:20:35.519 recessional velocity, how fast it's moving away, 00:20:35.700 --> 00:20:38.319 is directly proportional to how far away it is. 00:20:38.400 --> 00:20:41.160 Right. Mathematically, it's just v equals h -naught 00:20:41.160 --> 00:20:44.180 times dh -naught is the constant of proportionality, 00:20:44.240 --> 00:20:46.119 the Hubble constant. And what does that simple 00:20:46.119 --> 00:20:48.299 relationship imply about the universe as a whole? 00:20:48.650 --> 00:20:50.450 It implies that the universe is undergoing a 00:20:50.450 --> 00:20:54.049 uniform systematic expansion. If Galaxy B is 00:20:54.049 --> 00:20:57.029 twice as far away as Galaxy A, it appears to 00:20:57.029 --> 00:21:00.049 be receding at twice the speed. This only makes 00:21:00.049 --> 00:21:02.369 sense if space itself is stretching, carrying 00:21:02.369 --> 00:21:04.970 the galaxies along with it. So there's no center 00:21:04.970 --> 00:21:07.630 to the expansion. Exactly. Every galaxy sees 00:21:07.630 --> 00:21:10.069 every other galaxy receding from it. It's a profound 00:21:10.069 --> 00:21:12.819 idea. But this brings us immediately to the calibration 00:21:12.819 --> 00:21:16.019 problem. It's a huge issue. And it's vital for 00:21:16.019 --> 00:21:18.279 understanding why Hubble himself was so skeptical. 00:21:18.500 --> 00:21:21.200 It is. His initial distance estimates, while 00:21:21.200 --> 00:21:23.779 they were flawless relative to each other, the 00:21:23.779 --> 00:21:26.779 absolute scale was dramatically wrong. Okay, 00:21:26.779 --> 00:21:29.039 wrong. He was off by a factor of about seven. 00:21:29.220 --> 00:21:31.680 His calculated distances were way too small. 00:21:31.859 --> 00:21:34.039 And what caused that error? It was later found 00:21:34.039 --> 00:21:36.579 to be a combination of things. He was confusing 00:21:36.579 --> 00:21:39.000 two different types of Cepheid variable stars, 00:21:39.140 --> 00:21:41.400 which have different properties. And in some 00:21:41.400 --> 00:21:44.220 cases, he was mistaking extremely bright gas 00:21:44.220 --> 00:21:46.740 clouds in other galaxies for the brightest individual 00:21:46.740 --> 00:21:50.140 stars. These mistakes basically meant his yardstick 00:21:50.140 --> 00:21:52.720 was calibrated incorrectly. So his distance scale 00:21:52.720 --> 00:21:54.660 was too small. What was the catastrophic consequence 00:21:54.660 --> 00:21:57.099 of that? Well, if the distances are smaller, 00:21:57.319 --> 00:21:59.700 it means the expansion rate has to be much faster 00:21:59.700 --> 00:22:02.900 to get galaxies to where they are today. calculated 00:22:02.900 --> 00:22:05.980 value for the Hubble constant, H naught, was 00:22:05.980 --> 00:22:09.420 500 kilometers per second per megaparsec. Okay, 00:22:09.480 --> 00:22:12.400 let's pause. A megaparsec is a million parsecs, 00:22:12.400 --> 00:22:16.079 and a parsec is about 3 .26 light years. So that's 00:22:16.079 --> 00:22:18.299 a unit of distance. Right. So he's saying for 00:22:18.299 --> 00:22:21.119 every million parsecs farther away a galaxy is, 00:22:21.319 --> 00:22:23.940 its apparent velocity increases by 500 kilometers 00:22:23.940 --> 00:22:27.529 per second. And that number 500 created a massive 00:22:27.529 --> 00:22:30.390 crisis, didn't it? A huge crisis, because the 00:22:30.390 --> 00:22:32.529 Hubble constant is directly linked to the age 00:22:32.529 --> 00:22:35.029 of the universe. If you run the clock backwards, 00:22:35.289 --> 00:22:38.269 a value of 500 gives you an estimated age for 00:22:38.269 --> 00:22:41.009 the cosmos of only about 2 billion years. Which 00:22:41.009 --> 00:22:43.130 was the problem. It was a catastrophic problem. 00:22:43.390 --> 00:22:46.650 By the 1930s, geologists using radiometric dating 00:22:46.650 --> 00:22:48.869 had already established that rocks on Earth were 00:22:48.869 --> 00:22:52.029 older than 3 billion years old. So Hubble's own 00:22:52.029 --> 00:22:54.869 data, taken at face value, forced this logical 00:22:54.869 --> 00:22:57.710 obsession. The universe appeared to be younger 00:22:57.710 --> 00:23:00.849 than the planets inside it. Precisely. And that 00:23:00.849 --> 00:23:03.269 massive contradiction is the empirical foundation 00:23:03.269 --> 00:23:06.450 for his famous skepticism. His dedication to 00:23:06.450 --> 00:23:08.630 observation meant he could not accept a conclusion 00:23:08.630 --> 00:23:11.250 that contradicted known facts about the age of 00:23:11.250 --> 00:23:13.390 our own planet. This is what fueled his caution 00:23:13.390 --> 00:23:16.029 for decades. And this story is further complicated 00:23:16.029 --> 00:23:19.130 by the Lemaitre priority issue. George Lemaitre 00:23:19.130 --> 00:23:21.670 had theoretically predicted this exact relationship 00:23:21.670 --> 00:23:24.930 before Hubble published it. He did. Lemaitre, 00:23:25.089 --> 00:23:27.809 a Belgian physicist and a Catholic priest, published 00:23:27.809 --> 00:23:30.029 the theoretical prediction for an expanding universe 00:23:30.029 --> 00:23:33.329 in 1927 in French, using Einstein's equations 00:23:33.329 --> 00:23:36.140 of general relativity. He even included some 00:23:36.140 --> 00:23:38.619 initial observational data to support it. That 00:23:38.619 --> 00:23:41.980 was two full years before Hubble's famous 1929 00:23:41.980 --> 00:23:45.740 paper. So historically, Lemaitre has both conceptual 00:23:45.740 --> 00:23:48.299 and chronological priority. This all ties into 00:23:48.299 --> 00:23:50.160 Hubble's own reluctance to even interpret his 00:23:50.160 --> 00:23:52.819 data as true expansion. Right. He was the ultimate 00:23:52.819 --> 00:23:55.220 empiricist, always wary of theoretical speculation. 00:23:55.460 --> 00:23:58.240 He deliberately used the term apparent velocities 00:23:58.240 --> 00:24:00.420 to describe the recession of the galaxies. So 00:24:00.420 --> 00:24:03.460 not real velocities. He was being cautious. He 00:24:03.460 --> 00:24:05.660 wrote in his correspondence that the interpretation 00:24:05.660 --> 00:24:07.980 of this correlation should be left to the very 00:24:07.980 --> 00:24:10.539 few others who are competent to discuss the matter 00:24:10.539 --> 00:24:13.980 with authority, meaning the theorists like Einstein 00:24:13.980 --> 00:24:16.059 and de Sitter. He thought of an observational 00:24:16.059 --> 00:24:18.980 correlation, not necessarily proof that the fabric 00:24:18.980 --> 00:24:21.519 of space was expanding. So what is the modern 00:24:21.519 --> 00:24:24.119 view? Is it a Doppler shift or something else? 00:24:24.480 --> 00:24:26.880 That's a crucial distinction. A traditional Douglas 00:24:26.880 --> 00:24:29.059 shift is when an object moves through space. 00:24:29.339 --> 00:24:32.480 But what we see with distant galaxies, the cosmological 00:24:32.480 --> 00:24:36.059 redshift, is now interpreted as an increase in 00:24:36.059 --> 00:24:38.259 the proper distance between them because the 00:24:38.259 --> 00:24:41.519 fabric of space -time itself is expanding. Can 00:24:41.519 --> 00:24:44.230 you give us an analogy? The classic one is raisin 00:24:44.230 --> 00:24:46.769 bread dough rising in an oven. The raisins are 00:24:46.769 --> 00:24:48.609 the galaxies and they're fixed in the dough, 00:24:48.730 --> 00:24:51.450 which is space. As the dough expands, all the 00:24:51.450 --> 00:24:53.809 raisins move farther apart from each other, but 00:24:53.809 --> 00:24:55.730 they aren't actually moving through the dough. 00:24:56.200 --> 00:24:58.380 I see. So the light traveling from one raisin 00:24:58.380 --> 00:25:00.640 to another gets stretched as the dough expands. 00:25:01.359 --> 00:25:03.980 Exactly. The light waves are stretched, making 00:25:03.980 --> 00:25:07.220 them redder. That's cosmological redshift. It's 00:25:07.220 --> 00:25:09.640 different from a Doppler shift, but for nearby 00:25:09.640 --> 00:25:12.220 galaxies, the math works out to be almost the 00:25:12.220 --> 00:25:14.440 same, which is why it's easy to confuse them. 00:25:15.079 --> 00:25:17.859 But Hubble's caution was justified because his 00:25:17.859 --> 00:25:20.140 observations alone couldn't prove one over the 00:25:20.140 --> 00:25:22.779 other. And he held on to this skepticism for 00:25:22.779 --> 00:25:25.240 his whole career. He kept questioning the Big 00:25:25.240 --> 00:25:28.000 Bang interpretation. He did. Until the end of 00:25:28.000 --> 00:25:29.960 his career, he maintained that a model where 00:25:29.960 --> 00:25:33.759 no true expansion exists was still a viable possibility. 00:25:34.039 --> 00:25:36.480 He was driven by observations that suggested 00:25:36.480 --> 00:25:39.240 a uniform distribution of galaxies, which he 00:25:39.240 --> 00:25:41.740 felt didn't quite fit the sudden explosion idea 00:25:41.740 --> 00:25:44.519 implied by that early high value of his constant. 00:25:44.980 --> 00:25:47.740 This story is just so tied up with Albert Einstein's 00:25:47.740 --> 00:25:49.960 own intellectual journey. Let's talk about what 00:25:49.960 --> 00:25:52.400 Einstein later called his biggest blunder. Yes, 00:25:52.599 --> 00:25:54.960 this just highlights the incredible power of 00:25:54.960 --> 00:25:57.839 observation to overturn even the most deeply 00:25:57.839 --> 00:26:01.940 held theoretical beliefs. Around 1917, Einstein 00:26:01.940 --> 00:26:05.240 had completed general relativity and his equations, 00:26:05.380 --> 00:26:08.039 when applied to the universe as a whole, suggested 00:26:08.039 --> 00:26:10.480 that the cosmos had to be dynamic. It should 00:26:10.480 --> 00:26:13.099 be either expanding or contracting. But Einstein. 00:26:13.690 --> 00:26:16.369 Like pretty much every scientist of his era had 00:26:16.369 --> 00:26:19.250 this philosophical preference for a static, eternal 00:26:19.250 --> 00:26:22.809 universe. He did. And to force his equations 00:26:22.809 --> 00:26:26.049 to produce a static model, he introduced a term 00:26:26.049 --> 00:26:29.880 he called the cosmological constant. It was basically 00:26:29.880 --> 00:26:33.099 a mathematical fudge factor he invented to create 00:26:33.099 --> 00:26:35.180 a repulsive force that would perfectly balance 00:26:35.180 --> 00:26:37.720 gravity and hold the universe still. So the greatest 00:26:37.720 --> 00:26:40.000 theorist of the age introduces this mathematical 00:26:40.000 --> 00:26:43.400 trick to preserve a static universe. Only to 00:26:43.400 --> 00:26:45.359 have the greatest observer of the age, Hubble, 00:26:45.559 --> 00:26:48.019 come along and prove that the universe was decidedly 00:26:48.019 --> 00:26:50.819 not static. It's the ultimate irony. And when 00:26:50.819 --> 00:26:52.700 Einstein learned of Hubble's work? He realized 00:26:52.700 --> 00:26:55.099 his theoretical bias had blinded him. He saw 00:26:55.099 --> 00:26:57.240 the data, Slipper's redshifts and Hubble's plot, 00:26:57.380 --> 00:26:59.279 and understood that the expansion was real. And 00:26:59.279 --> 00:27:01.519 they actually met, right? They did. Einstein 00:27:01.519 --> 00:27:05.119 visited Mount Wilson Observatory in 1931. He 00:27:05.119 --> 00:27:07.339 met with Hubble. He saw the telescope. He talked 00:27:07.339 --> 00:27:10.099 with the observational team. And after that visit, 00:27:10.220 --> 00:27:13.039 he famously and publicly retracted the cosmological 00:27:13.039 --> 00:27:15.839 constant, later calling it the biggest blunder 00:27:15.839 --> 00:27:18.849 of my life. He accepted the expansion based on 00:27:18.849 --> 00:27:21.329 the evidence. Which creates this second layer 00:27:21.329 --> 00:27:24.089 of irony. As Einstein is finally accepting the 00:27:24.089 --> 00:27:26.630 expansion based on Hubble's data, Hubble himself 00:27:26.630 --> 00:27:29.089 is still internally questioning what that data 00:27:29.089 --> 00:27:31.829 really means. It's incredible, isn't it? Hubble 00:27:31.829 --> 00:27:34.190 remains skeptical. He was so troubled by that 00:27:34.190 --> 00:27:36.430 age discrepancy and the uniform distribution 00:27:36.430 --> 00:27:40.309 of galaxies. In a 1941 report based on a six 00:27:40.309 --> 00:27:43.009 -year survey, he explicitly argued that his results 00:27:43.009 --> 00:27:45.609 did not support the pure expanding universe theory. 00:27:46.279 --> 00:27:48.299 He said the uniformity didn't fit the explosion 00:27:48.299 --> 00:27:50.599 idea. It shows this deep intellectual split. 00:27:50.880 --> 00:27:53.700 Hubble is saying, my telescope shows me a universe 00:27:53.700 --> 00:27:56.079 that looks uniform, and my numbers say the universe 00:27:56.079 --> 00:27:58.359 is younger than the Earth, so I have to question 00:27:58.359 --> 00:28:00.859 the expansion interpretation. it's a powerful 00:28:00.859 --> 00:28:03.960 lesson in scientific humility he refused to let 00:28:03.960 --> 00:28:07.180 theory dictate his observations he held open 00:28:07.180 --> 00:28:09.859 the possibility that redshift was caused by in 00:28:09.859 --> 00:28:13.079 his words a hitherto unrecognized principle of 00:28:13.079 --> 00:28:16.259 nature like the tired light theory exactly the 00:28:16.259 --> 00:28:18.960 idea that light simply loses energy as it travels 00:28:18.960 --> 00:28:22.059 vast distances that's been ruled out now but 00:28:22.059 --> 00:28:24.700 his willingness to challenge the prevailing view 00:28:24.700 --> 00:28:27.740 based on conflicting data is what made him such 00:28:27.740 --> 00:28:29.980 a great scientist okay let's Let's address the 00:28:29.980 --> 00:28:33.420 most serious historical controversy, the LeMetre 00:28:33.420 --> 00:28:36.460 redaction issue. For many years, this cast a 00:28:36.460 --> 00:28:39.960 real shadow on Hubble's legacy. It did. For decades, 00:28:40.140 --> 00:28:42.319 there was this deep suspicion surrounding the 00:28:42.319 --> 00:28:44.700 English translation of George LeMetre's 1927 00:28:44.700 --> 00:28:47.740 paper. The original French paper included observational 00:28:47.740 --> 00:28:49.700 evidence supporting the expansion law, including 00:28:49.700 --> 00:28:52.180 his own calculated value for the expansion rate. 00:28:52.359 --> 00:28:54.079 But when the English translation was published 00:28:54.079 --> 00:28:57.039 in 1931, Those key paragraphs were missing. They 00:28:57.039 --> 00:29:00.019 were gone. And the immediate damning conclusion 00:29:00.019 --> 00:29:02.759 that many people drew was that Hubble, or someone 00:29:02.759 --> 00:29:05.059 close to him, must have redacted those sections 00:29:05.059 --> 00:29:07.220 to make sure he kept priority for Hubble's law, 00:29:07.359 --> 00:29:10.019 which he published in 1929. It seemed plausible, 00:29:10.240 --> 00:29:13.059 an attempt to rewrite scientific history in his 00:29:13.059 --> 00:29:16.440 favor. It did, because Lemaitre clearly had theoretical 00:29:16.440 --> 00:29:20.279 and arguably observational priority from 1927. 00:29:20.539 --> 00:29:22.700 If the content was suppressed, it would have 00:29:22.700 --> 00:29:26.240 been a major ethical breach. So how is this finally 00:29:26.240 --> 00:29:29.559 resolved? The resolution came in 2011, thanks 00:29:29.559 --> 00:29:32.559 to the astronomer Mario Lubio. He did some historical 00:29:32.559 --> 00:29:35.059 detective work and found a letter in the LaMetra 00:29:35.059 --> 00:29:37.220 archive that provided the definitive answer. 00:29:37.440 --> 00:29:39.220 And the person who requested the redaction was? 00:29:39.559 --> 00:29:42.180 LaMetra himself. Why on earth would he remove 00:29:42.180 --> 00:29:44.559 his own foundational data from the English translation? 00:29:45.049 --> 00:29:48.009 It was an act of humility and practicality. Lemaître 00:29:48.009 --> 00:29:50.289 felt that his specific observational data from 00:29:50.289 --> 00:29:53.390 1927 had already been superseded by Hubble's 00:29:53.390 --> 00:29:56.970 more extensive and robust data from 1929. He 00:29:56.970 --> 00:29:59.089 saw no reason to reproduce what he considered 00:29:59.089 --> 00:30:02.210 obsolete data in the 1931 translation, which 00:30:02.210 --> 00:30:04.029 he wanted to focus on the theoretical implications. 00:30:04.450 --> 00:30:07.069 So the letter completely cleared Hubble of that 00:30:07.069 --> 00:30:09.569 charge, although the fact of Lemaître's chronological 00:30:09.569 --> 00:30:12.309 priority is still undisputed. Moving on to another 00:30:12.309 --> 00:30:14.920 professional struggle. Hubble spent much of his 00:30:14.920 --> 00:30:17.380 later career chasing an honor that ultimately 00:30:17.380 --> 00:30:20.200 slipped through his fingers. The Nobel Prize. 00:30:20.539 --> 00:30:23.140 This was a determined campaign. At the time, 00:30:23.160 --> 00:30:25.019 the Nobel Committee didn't consider astronomy 00:30:25.019 --> 00:30:27.779 to be part of physics. They saw it more as a 00:30:27.779 --> 00:30:30.559 descriptive observational science. And Hubble 00:30:30.559 --> 00:30:33.440 argued against that. Vigorously. He and his colleagues 00:30:33.440 --> 00:30:35.869 argued that foundational work like... Proving 00:30:35.869 --> 00:30:38.170 the existence of other galaxies and charting 00:30:38.170 --> 00:30:41.210 the expansion of the universe was clearly fundamental 00:30:41.210 --> 00:30:44.089 physics. It was cosmology. The physics of the 00:30:44.089 --> 00:30:47.049 universe. Exactly. He lobbied tirelessly, writing 00:30:47.049 --> 00:30:49.470 letters, trying to change the rules. And the 00:30:49.470 --> 00:30:52.630 heartbreaking twist is that he succeeded, but 00:30:52.630 --> 00:30:55.150 too late. The timing is just tragic. The Nobel 00:30:55.150 --> 00:30:57.630 Committee eventually did decide that astronomical 00:30:57.630 --> 00:30:59.769 work would be eligible for the physics prize. 00:31:00.009 --> 00:31:02.529 But that ruling was enacted shortly after Hubble 00:31:02.529 --> 00:31:06.119 died in September 1953. And since the Nobel Prize 00:31:06.119 --> 00:31:09.000 cannot be awarded posthumously, he missed out 00:31:09.000 --> 00:31:10.960 on the recognition he had campaigned for and 00:31:10.960 --> 00:31:14.019 so fundamentally deserved. He broke the universe 00:31:14.019 --> 00:31:17.279 open for us, only to be deemed ineligible for 00:31:17.279 --> 00:31:19.380 the prize that celebrates exactly those kinds 00:31:19.380 --> 00:31:21.759 of breakthroughs. A truly poignant end to that 00:31:21.759 --> 00:31:23.940 part of his story. Despite the controversies 00:31:23.940 --> 00:31:26.700 and the missed Nobel. Hubble's publications made 00:31:26.700 --> 00:31:28.740 sure his methods and discoveries were codified 00:31:28.740 --> 00:31:31.339 for future generations. Oh, yes. His foundational 00:31:31.339 --> 00:31:34.660 books are still cornerstones of cosmology. You 00:31:34.660 --> 00:31:37.559 look at The Realm of the Nebulae from 1936 and 00:31:37.559 --> 00:31:40.359 The Observational Approach to Cosmology from 00:31:40.359 --> 00:31:43.460 1937. These books didn't just report his data. 00:31:43.579 --> 00:31:45.960 They laid out his entire empirical philosophy 00:31:45.960 --> 00:31:48.119 and standardized the way we classify galaxies. 00:31:48.460 --> 00:31:50.680 They laid the groundwork for everything that 00:31:50.680 --> 00:31:52.920 followed. And on a personal level, he married 00:31:52.920 --> 00:31:56.160 Grace Lillian Burke in 1920. just a few months 00:31:56.160 --> 00:31:59.220 before his monumental Andromeda discovery. Grace 00:31:59.220 --> 00:32:01.829 was central to his life. She managed his social 00:32:01.829 --> 00:32:04.609 profile and later was the fierce guardian of 00:32:04.609 --> 00:32:07.049 his intellectual legacy. We know his health began 00:32:07.049 --> 00:32:09.569 to decline in the late 1940s. He had a heart 00:32:09.569 --> 00:32:12.170 attack in 1949. He continued to work on a restricted 00:32:12.170 --> 00:32:14.589 schedule, but his health was precarious. He died 00:32:14.589 --> 00:32:17.490 from a blood clot in the brain, a cerebral thrombosis, 00:32:17.509 --> 00:32:21.210 on September 28, 1953. And this brings us to 00:32:21.210 --> 00:32:24.069 one of the most intriguing and mysterious final 00:32:24.069 --> 00:32:27.390 details of his life. A secret his wife kept until 00:32:27.390 --> 00:32:30.410 her own death decades later. Yes, the final mystery 00:32:30.410 --> 00:32:33.490 of Edwin Hubble. There was no public funeral 00:32:33.490 --> 00:32:37.069 service held for him. An even stranger, his wife, 00:32:37.250 --> 00:32:40.549 Grace, never revealed where he was buried. So 00:32:40.549 --> 00:32:42.890 no one knows. No one knows. She donated all his 00:32:42.890 --> 00:32:45.490 papers, his logbooks, his correspondence. But 00:32:45.490 --> 00:32:47.829 the location of his final resting place remains 00:32:47.829 --> 00:32:50.390 a complete mystery to this day. It's an almost 00:32:50.390 --> 00:32:53.009 mythical ending for a man who charted the boundaries 00:32:53.009 --> 00:32:56.410 of the cosmos. His own final location is one 00:32:56.410 --> 00:32:59.430 of the universe's small secrets. It is. But despite 00:32:59.430 --> 00:33:01.730 that personal secrecy, his professional legacy 00:33:01.730 --> 00:33:04.950 is spectacularly public. It's marked by so many 00:33:04.950 --> 00:33:07.230 enduring honors. The most famous, of course, 00:33:07.309 --> 00:33:09.089 is the Hubble Space Telescope. An instrument 00:33:09.089 --> 00:33:10.970 that continues his work, pushing the limits of 00:33:10.970 --> 00:33:13.049 observation far beyond what he could have ever 00:33:13.049 --> 00:33:15.450 dreamed of with the 100 -inch Hooker Telescope. 00:33:15.589 --> 00:33:17.809 But his name is also stamped all over the place. 00:33:18.630 --> 00:33:21.569 Asteroid 2069 Hubble, the Hubble Crater on the 00:33:21.569 --> 00:33:24.539 Moon, the Edwin Hubble Highway in Missouri. And 00:33:24.539 --> 00:33:26.880 his lifetime awards, including the ones for his 00:33:26.880 --> 00:33:30.039 wartime service, really highlight what a polymath 00:33:30.039 --> 00:33:33.180 he was. The Newcomb Cleveland Prize, the Bruce 00:33:33.180 --> 00:33:36.099 Medal, the Franklin Medal, the Gold Medal of 00:33:36.099 --> 00:33:38.680 the Royal Astronomical Society, and of course 00:33:38.680 --> 00:33:40.920 the Legion of Merit for his ballistics research. 00:33:41.200 --> 00:33:44.099 A stunning list of accomplishments. His story 00:33:44.099 --> 00:33:46.940 is now permanently woven into our popular understanding 00:33:46.940 --> 00:33:48.980 of science, perhaps most famously through Carl 00:33:48.980 --> 00:33:51.299 Sagan. Sagan made sure Hubble's legacy reached 00:33:51.299 --> 00:33:54.240 a massive audience. He featured him prominently 00:33:54.240 --> 00:33:57.359 in his 1980 documentary, Cosmos, in the episode 00:33:57.359 --> 00:34:00.299 about cosmic scale and time. He's truly crossed 00:34:00.299 --> 00:34:03.359 over from being a scientific giant to a cultural 00:34:03.359 --> 00:34:06.140 icon. So as we wrap up this deep dive, let's 00:34:06.140 --> 00:34:08.400 just reflect on the monumental scale of his impact. 00:34:08.989 --> 00:34:11.090 Hubble took humanity from thinking we lived on 00:34:11.090 --> 00:34:14.130 a single contained stellar island to realizing 00:34:14.130 --> 00:34:17.409 we inhabit one galaxy among billions all rushing 00:34:17.409 --> 00:34:19.349 apart from each other in an expanding universe. 00:34:19.550 --> 00:34:21.750 His career is really a testament to the power 00:34:21.750 --> 00:34:24.349 of meticulous observation over even the strongest 00:34:24.349 --> 00:34:26.869 theoretical beliefs. He said it best himself. 00:34:27.090 --> 00:34:29.900 He wrote. We do not know why we are born into 00:34:29.900 --> 00:34:32.239 the world, but we can try to find out what sort 00:34:32.239 --> 00:34:34.800 of a world it is, at least in its physical aspects. 00:34:35.280 --> 00:34:37.960 And that dedication to observation, to exhausting 00:34:37.960 --> 00:34:41.280 the empirical resources first, led him to conclude. 00:34:41.519 --> 00:34:43.659 Not until the empirical resources are exhausted 00:34:43.659 --> 00:34:46.440 need we pass on to the dreamy realms of speculation. 00:34:47.099 --> 00:34:49.800 And that, I think, perfectly frames our final 00:34:49.800 --> 00:34:52.300 thought for you, the listener. We've established 00:34:52.300 --> 00:34:55.320 that Hubble, the man who provided the data, remains 00:34:55.320 --> 00:34:57.400 skeptical of the expansion of the universe until 00:34:57.400 --> 00:35:00.119 the end. He preferred the idea that redshift 00:35:00.119 --> 00:35:03.000 might be a sign of some hitherto unrecognized 00:35:03.000 --> 00:35:06.340 principle of nature. Like tired light. Today, 00:35:06.400 --> 00:35:08.820 physics is far more confident in the metric expansion 00:35:08.820 --> 00:35:12.079 model. So our question is this. What are the 00:35:12.079 --> 00:35:14.519 modern empirical resources that conclusively 00:35:14.519 --> 00:35:17.699 prove the universe is truly expanding, eliminating 00:35:17.699 --> 00:35:20.500 all possibility for Hubble's original skepticism? 00:35:20.909 --> 00:35:23.030 What observations, things like the light curves 00:35:23.030 --> 00:35:25.969 of Type Ia supernovae at extreme distances, or 00:35:25.969 --> 00:35:28.369 the tiny temperature fluctuations in the cosmic 00:35:28.369 --> 00:35:30.690 microwave background, what observations provide 00:35:30.690 --> 00:35:33.389 that final, zero -room -for -doubt evidence that 00:35:33.389 --> 00:35:35.769 Hubble, the ultimate observer, would have required 00:35:35.769 --> 00:35:38.030 to finally change his mind? That is something 00:35:38.030 --> 00:35:38.630 worth exploring.