1 00:00:00,080 --> 00:00:01,720 Speaker 1: Okay, I want you to try something with me, just 2 00:00:01,760 --> 00:00:04,480 for a second. We're gonna do a little visualization exercise. 3 00:00:04,519 --> 00:00:08,160 I want you to imagine you are floating in the 4 00:00:08,439 --> 00:00:13,960 absolute deepest, darkest void of empty space. Okay, I'm talking 5 00:00:14,519 --> 00:00:18,120 light years away from the nearest star. There are no planets, 6 00:00:18,199 --> 00:00:23,039 no dust, no gas. It's just pure, unadulterated nothingness. 7 00:00:23,160 --> 00:00:27,600 Speaker 2: The perfect laboratory. Yeah, the physicists dream, No friction, no noise, 8 00:00:27,719 --> 00:00:28,879 just a perfect vacuum. 9 00:00:28,920 --> 00:00:32,640 Speaker 1: Exactly. It's a blank canvas. Now, in this total emptiness, 10 00:00:32,719 --> 00:00:36,280 you fire a single electron, just one tiny little particle 11 00:00:36,520 --> 00:00:39,200 zipping through the dark. Right, according to everything you and 12 00:00:39,200 --> 00:00:41,679 I were taught in high school physics, and let's be honest, 13 00:00:41,719 --> 00:00:44,719 most of what you learn in university too, what should 14 00:00:44,719 --> 00:00:45,679 happen to that electron? 15 00:00:45,880 --> 00:00:50,039 Speaker 2: Well, the classical intuition here is rock solid. It goes 16 00:00:50,079 --> 00:00:51,359 all the way back to Isaac. 17 00:00:51,079 --> 00:00:52,240 Speaker 1: Newton, the man himself. 18 00:00:52,399 --> 00:00:55,840 Speaker 2: The rule is, if there are no forces acting on 19 00:00:55,880 --> 00:00:58,159 an object, and by that I mean no electric fields 20 00:00:58,159 --> 00:01:01,320 pushing it, no magnetic fields twisting gravity pulling on it, 21 00:01:01,320 --> 00:01:03,479 it has to just continue in a straight line, in 22 00:01:03,479 --> 00:01:05,640 a straight line at a constant speed. It's the law 23 00:01:05,640 --> 00:01:06,760 of inertia. 24 00:01:06,599 --> 00:01:10,159 Speaker 1: Newton's first law. An object in motion stays in motion 25 00:01:10,400 --> 00:01:13,560 unless an external force gets involved. It's like the golden 26 00:01:13,640 --> 00:01:16,079 rule of physics, no force, no change. 27 00:01:16,120 --> 00:01:18,879 Speaker 2: Precisely, if there's nothing touching it and nothing pulling it 28 00:01:18,920 --> 00:01:22,040 from a distance, Yeah, it cannot possibly change its path. 29 00:01:22,079 --> 00:01:23,879 It's it's impossible. 30 00:01:23,920 --> 00:01:26,959 Speaker 1: Okay, So hold that word impossible in your head, because 31 00:01:27,000 --> 00:01:29,439 what if I told you that I have a device. 32 00:01:29,519 --> 00:01:33,840 It's a little metal box, and it's completely shielded, locked down, 33 00:01:34,159 --> 00:01:37,400 and it's separated from that electron by that same empty space. 34 00:01:37,959 --> 00:01:41,599 This device creates zero force field where the electron is flying. 35 00:01:41,920 --> 00:01:44,719 The magnetic field where the electron is is strictly zero. 36 00:01:44,959 --> 00:01:47,319 Speaker 2: So by definition no force, the rule. 37 00:01:47,079 --> 00:01:49,840 Speaker 1: Hold no force. But if I flip a switch on 38 00:01:49,879 --> 00:01:52,719 that box a box, remember the electron, ever touches a 39 00:01:52,760 --> 00:01:54,760 box that isn't pushing or pulling it in any way, 40 00:01:54,760 --> 00:01:57,680 we can measure. I can still change how that electron behaves. 41 00:01:57,719 --> 00:01:58,400 Speaker 2: What do you mean change? 42 00:01:58,400 --> 00:01:59,519 Speaker 1: I can make it shift its path. 43 00:01:59,599 --> 00:02:02,079 Speaker 2: That sounds telepathy or you know, magic. 44 00:02:02,439 --> 00:02:05,400 Speaker 1: It sounds like a glitch in the simulation, but it 45 00:02:05,439 --> 00:02:09,000 isn't magic. It is real. It's verifiable physics. It's called 46 00:02:09,000 --> 00:02:12,560 the Haranov Bohm effect, and when it was first proposed, 47 00:02:13,000 --> 00:02:16,400 it didn't just confuse people, it split the physics community 48 00:02:16,520 --> 00:02:17,360 right down the middle. 49 00:02:17,439 --> 00:02:21,280 Speaker 2: Oh, it really did, because it forces us to ask this, 50 00:02:21,280 --> 00:02:25,479 this really terrifying question. We spent our whole lives learning 51 00:02:25,479 --> 00:02:30,479 that force fields, electric fields, magnetic fields, gravity, those are 52 00:02:30,479 --> 00:02:31,039 the real things. 53 00:02:31,240 --> 00:02:32,639 Speaker 1: Yeah, they're what run the universe. 54 00:02:33,039 --> 00:02:37,879 Speaker 2: But this phenomenon suggests that maybe the force field is 55 00:02:37,919 --> 00:02:40,400 just a shadow. Maybe there's something deeper, something hidden in 56 00:02:40,439 --> 00:02:42,439 the mathematics that we all thought was just a trick 57 00:02:42,840 --> 00:02:44,599 that is actually running the show. 58 00:02:44,800 --> 00:02:46,520 Speaker 1: So are we looking at the puppet or are we 59 00:02:46,520 --> 00:02:47,759 looking at the strings? 60 00:02:47,879 --> 00:02:49,199 Speaker 2: That is exactly the question. 61 00:02:49,439 --> 00:02:52,199 Speaker 1: Welcome to Thrilling Threads. I'm your host, and I have 62 00:02:52,240 --> 00:02:55,000 to say, looking through the source material we've pulled for today, 63 00:02:55,319 --> 00:02:58,879 including our really fascinating transcript and some pretty heavy papers 64 00:02:58,919 --> 00:03:01,759 from the nineteen fifties, I felt a little bit betrayed 65 00:03:02,039 --> 00:03:03,639 by my physics teacher atrade. 66 00:03:03,639 --> 00:03:04,520 Speaker 2: That's a strong word. 67 00:03:04,759 --> 00:03:07,680 Speaker 1: Well, I mean think about it. We spend years drawing 68 00:03:07,759 --> 00:03:10,560 force diagrams, all those little arrows pointing this way in 69 00:03:10,599 --> 00:03:13,159 that way, and now we're finding out that that whole 70 00:03:13,199 --> 00:03:15,360 system might just be secondary. 71 00:03:15,719 --> 00:03:17,680 Speaker 2: I get it. It's like finding out the alphabet you 72 00:03:17,759 --> 00:03:20,199 learned is just a suggestion exactly. 73 00:03:20,719 --> 00:03:23,400 Speaker 1: So today we are pulling out that one little loose 74 00:03:23,439 --> 00:03:25,879 thread in the fabric of reality, and we are just 75 00:03:25,960 --> 00:03:29,039 going to keep unraveling it until we see what lies beneath. 76 00:03:29,240 --> 00:03:31,719 Speaker 2: And I'm ready. We are going on a journey today 77 00:03:31,759 --> 00:03:33,759 that you know. It starts with something as simple as 78 00:03:33,759 --> 00:03:37,599 planetary orbits and ends with the fundamental question of what 79 00:03:37,800 --> 00:03:38,919 real even means. 80 00:03:39,199 --> 00:03:41,680 Speaker 1: I love this topic because it takes something that sounds 81 00:03:41,719 --> 00:03:44,680 so dry on the surface, you know, textbook definitions of 82 00:03:44,680 --> 00:03:48,719 potentials and scalers, and it turns it into this psychological thriller. 83 00:03:48,960 --> 00:03:53,319 We've got mathematical cheaters, we've got exiled physicists literally on 84 00:03:53,360 --> 00:03:55,840 the run from the government, and an experiment that broke 85 00:03:55,879 --> 00:03:56,479 all the rules. 86 00:03:56,560 --> 00:03:58,599 Speaker 2: And what's so fascinating to me is that this story 87 00:03:58,639 --> 00:04:02,360 doesn't even start with quantum mechanics. It starts with a failure, 88 00:04:02,719 --> 00:04:06,879 a massive, centuries long failure to solve a very specific 89 00:04:07,039 --> 00:04:07,960 math problem. 90 00:04:08,080 --> 00:04:10,039 Speaker 1: Okay, let's unpack that. We're going back to the og 91 00:04:10,840 --> 00:04:11,960 Isaac Newton. 92 00:04:11,719 --> 00:04:15,680 Speaker 2: The man who wrote the rules. When Newton figured out gravity, 93 00:04:15,759 --> 00:04:18,519 he solved what we now call the two body problem 94 00:04:18,560 --> 00:04:21,319 almost trivially. If you have the Earth in the Sun, 95 00:04:21,439 --> 00:04:24,600 he could calculate their orbits perfectly. The math is beautiful, 96 00:04:24,600 --> 00:04:27,480 it's elegant. You draw a line between them, calculate the force, 97 00:04:27,600 --> 00:04:29,160 and boom you're done. 98 00:04:29,279 --> 00:04:31,040 Speaker 1: Two is company, Two is easy. 99 00:04:30,920 --> 00:04:34,240 Speaker 2: But three, three is a crowd. As soon as Newton 100 00:04:34,319 --> 00:04:36,920 added a third body, say you add the Moon to 101 00:04:36,920 --> 00:04:39,759 the Earth's sun system, where you add Jupiter tugging on 102 00:04:39,800 --> 00:04:42,439 the Earth, the math just completely fell apart. 103 00:04:42,560 --> 00:04:45,560 Speaker 1: This is the famous three body problem. And I've always 104 00:04:45,560 --> 00:04:47,040 wondered why is it so hard? I mean, if you 105 00:04:47,079 --> 00:04:49,399 can calculate the force from the Sun, and you can 106 00:04:49,439 --> 00:04:53,120 calculate the force from Jupiter, why can't you just add 107 00:04:53,160 --> 00:04:53,519 them up? 108 00:04:53,680 --> 00:04:56,279 Speaker 2: You can, but it's an absolute nightmare. And the reason, 109 00:04:56,600 --> 00:05:00,959 the entire reason, comes down to one word. Vectors varrows. 110 00:05:01,279 --> 00:05:05,480 Exactly in Newton's world forces our vectors. They have a magnitude, 111 00:05:05,680 --> 00:05:08,920 so how strong is the pole? And crucially, they have 112 00:05:09,000 --> 00:05:09,560 a direction. 113 00:05:09,920 --> 00:05:12,199 Speaker 1: Where's a pulling like an arrow, a little arrow pointing 114 00:05:12,240 --> 00:05:13,160 from the Earth to the Sun. 115 00:05:13,439 --> 00:05:17,839 Speaker 2: Right now, imagine three bodies all moving in every single 116 00:05:17,879 --> 00:05:21,519 split second, their positions change, which means the angles between 117 00:05:21,519 --> 00:05:24,399 them change, which means the direction of all the arrows changes. 118 00:05:24,560 --> 00:05:26,439 Speaker 1: So you're trying to track three different arrows that are 119 00:05:26,439 --> 00:05:29,240 all spinning and growing and shrinking at the same time, and. 120 00:05:29,240 --> 00:05:32,560 Speaker 2: They all affect each other. If body A moves, that 121 00:05:32,759 --> 00:05:35,680 changes its poll on body B. So body B moves, 122 00:05:35,720 --> 00:05:38,360 which changes its pull on body C, which then changes 123 00:05:38,399 --> 00:05:41,279 its pullback on body A. It's a feedback loop of 124 00:05:41,319 --> 00:05:44,639 pure chaos. It's a hair ball, it's a computational catastrophe. 125 00:05:44,720 --> 00:05:47,160 For one hundred years, the smartest people on the planet, 126 00:05:47,199 --> 00:05:51,240 we're talking at Eilerdllen Bear, the absolute heavy hitters of mathematics. 127 00:05:51,680 --> 00:05:53,839 They all tried to solve the three body problem using 128 00:05:53,920 --> 00:05:57,079 force vectors, and every single one of them hit a 129 00:05:57,079 --> 00:05:57,680 brick wall. 130 00:05:57,920 --> 00:06:01,279 Speaker 1: Enter the hero of our first act, Luis Lagrange. It's 131 00:06:01,319 --> 00:06:04,839 the seventeen seventies, and he looks at this, this spaghetti 132 00:06:04,879 --> 00:06:07,319 of arrows, this mess of vectors, and he just decides 133 00:06:07,360 --> 00:06:08,560 to throw the whole approach out. 134 00:06:08,759 --> 00:06:12,040 Speaker 2: Lagrange had this incredible insight. He realized that working with 135 00:06:12,120 --> 00:06:16,319 direction was the core of the problem. Direction means geometry, 136 00:06:16,360 --> 00:06:19,879 it means angles, it means trigonometry. It is messy. He 137 00:06:19,959 --> 00:06:22,000 wanted to find a way to strip direction out of 138 00:06:22,000 --> 00:06:23,160 the equation entirely. 139 00:06:23,279 --> 00:06:26,199 Speaker 1: So he invents a new character for our story, the potential. 140 00:06:26,480 --> 00:06:29,199 Speaker 2: Right, And to really get your head around the potential, 141 00:06:29,639 --> 00:06:32,399 you have to stop thinking about space as this empty 142 00:06:32,480 --> 00:06:34,959 void and start thinking of it as a landscape. 143 00:06:35,000 --> 00:06:36,839 Speaker 1: I love this analogy. Let's really break this down. 144 00:06:36,920 --> 00:06:40,519 Speaker 2: Okay, imagine a hilly terrain. You're looking at a topographical map. 145 00:06:40,879 --> 00:06:43,399 At every single point on that map, there's a specific 146 00:06:43,439 --> 00:06:46,319 height and altitude. Maybe you're a five hundred meters, maybe 147 00:06:46,360 --> 00:06:47,439 you're at two hundred meters. 148 00:06:47,560 --> 00:06:50,319 Speaker 1: Okay, So that height is just one number. It doesn't 149 00:06:50,360 --> 00:06:52,600 point north or south or upper down. It's just five. 150 00:06:52,519 --> 00:06:55,560 Speaker 2: Hundred precisely, it's a scaler. A scaler is just a 151 00:06:55,600 --> 00:06:58,680 magnitude of no direction. Temperature is a scaler, mass is 152 00:06:58,680 --> 00:07:02,600 a scaler, Altitude is scaler. Legrange's idea was to assign 153 00:07:02,879 --> 00:07:06,480 a height number a gravitational potential to every single point 154 00:07:06,519 --> 00:07:07,839 in space around a star. 155 00:07:08,160 --> 00:07:10,319 Speaker 1: So instead of drawing an arrow pointing at the star, 156 00:07:10,519 --> 00:07:12,879 you just draw a map where the star sits at 157 00:07:12,879 --> 00:07:14,600 the bottom of a really deep valley. 158 00:07:14,759 --> 00:07:18,800 Speaker 2: Yes, a gravity Well, now here's the stroke of genius. 159 00:07:19,920 --> 00:07:22,399 If you place a marble on the side of a hill, 160 00:07:22,879 --> 00:07:23,959 which way does it roll? 161 00:07:24,399 --> 00:07:27,839 Speaker 1: It rolls down the slope, the steepest way down right. 162 00:07:28,120 --> 00:07:31,120 Speaker 2: The slope tells you the direction. The slope is the force. 163 00:07:31,600 --> 00:07:32,680 The slope is the vector. 164 00:07:32,759 --> 00:07:34,519 Speaker 1: I see it now. So if you just know the 165 00:07:34,560 --> 00:07:38,120 shape of the hill the potential, you automatically know the 166 00:07:38,160 --> 00:07:40,160 force on anything you put there. You just look at 167 00:07:40,199 --> 00:07:41,000 which way is down. 168 00:07:41,079 --> 00:07:43,839 Speaker 2: You've got it. And here is why this changed everything. 169 00:07:44,639 --> 00:07:48,240 Adding scalers is incredibly easy. If you have three stars, 170 00:07:48,279 --> 00:07:50,839 you don't have to do all this complicated trigonometry with arrows. 171 00:07:51,120 --> 00:07:53,920 You just take the altitude map of Star A and 172 00:07:53,959 --> 00:07:55,720 you literally just add it to the map of Star 173 00:07:55,839 --> 00:07:57,519 B and add that to the map of Star C. 174 00:07:57,720 --> 00:08:00,879 Speaker 1: You're just adding numbers five plus ten plus two. 175 00:08:00,920 --> 00:08:03,120 Speaker 2: You're just stacking the landscapes on top of each other 176 00:08:03,160 --> 00:08:06,279 to get one final master landscape. And once you have 177 00:08:06,279 --> 00:08:08,759 that master landscape, you just look at the slope at 178 00:08:08,800 --> 00:08:10,160 any point to see how things most. 179 00:08:10,199 --> 00:08:13,120 Speaker 1: It is. Honestly, it feels like it as sheet code for physics. 180 00:08:13,399 --> 00:08:15,800 Speaker 2: It really felt like one to them too. It completely 181 00:08:15,879 --> 00:08:19,920 revolutionized physics. Now, it didn't solve the three body problem 182 00:08:19,959 --> 00:08:22,160 in the sense of finding one simple formula that was 183 00:08:22,160 --> 00:08:25,439 actually proven to be impossible later on, but it gave 184 00:08:25,480 --> 00:08:28,000 physics a whole new language. It turned a really hard 185 00:08:28,040 --> 00:08:31,319 geometry problem into a much easier accounting problem. 186 00:08:31,360 --> 00:08:35,240 Speaker 1: And this is what led to the famous Lagrangian, which 187 00:08:35,559 --> 00:08:38,200 sounds like a spaceship from Star Trek, but it's actually 188 00:08:38,200 --> 00:08:38,840 an equation. 189 00:08:39,399 --> 00:08:42,480 Speaker 2: It is the absolute foundation of all modern physics. One 190 00:08:42,519 --> 00:08:47,279 dollar isles TV Molner. It's the kinetic energy minus the 191 00:08:47,279 --> 00:08:50,960 potential energy. Lagrune showed that the universe is, in a 192 00:08:51,039 --> 00:08:54,639 sense fundamentally lazy. It always tries to minimize this quantity 193 00:08:54,679 --> 00:08:55,240 over time. 194 00:08:55,360 --> 00:08:57,360 Speaker 1: So you just plug the energies into this other thing, 195 00:08:57,399 --> 00:08:59,240 the Eiler LaGrone equation. 196 00:08:59,240 --> 00:09:01,360 Speaker 2: And you get the answer or for how things move. Yeah, 197 00:09:01,360 --> 00:09:03,559 you can do it without ever drawing a single force. 198 00:09:03,679 --> 00:09:05,639 Speaker 1: Errow the sorts of material we looked at had this 199 00:09:05,679 --> 00:09:07,679 great line it said, this method allows you to get 200 00:09:07,679 --> 00:09:10,919 the right answer without being a good physicist, meaning you 201 00:09:10,960 --> 00:09:14,039 don't need that deep intuitive sense of vectors and forces. 202 00:09:14,159 --> 00:09:16,279 You just plug in the numbers, you turn the crank, 203 00:09:16,440 --> 00:09:17,440 and outcomes of truth. 204 00:09:17,799 --> 00:09:20,759 Speaker 2: It democratized the math in a way, but it also 205 00:09:20,799 --> 00:09:25,960 shifted the entire philosophical focus of physics. Suddenly energy and 206 00:09:26,039 --> 00:09:30,200 potential became the primary tools, not force. And it works 207 00:09:30,279 --> 00:09:32,600 so well for gravity that they immediately started trying to 208 00:09:32,600 --> 00:09:33,840 apply it to other things. 209 00:09:33,720 --> 00:09:37,960 Speaker 1: Right, like electricity, because electricity is pretty similar. Mass attracts mass, 210 00:09:38,480 --> 00:09:42,840 positive charge attracts negative charge. So this guy, Simeon Dennis Poisson, 211 00:09:43,000 --> 00:09:45,360 great name, by the way, excellent name, he applies this 212 00:09:45,440 --> 00:09:48,519 whole hill and valley map idea to electric fields. 213 00:09:48,759 --> 00:09:52,639 Speaker 2: Yeah, and it worked perfectly with one little twist. Gravity 214 00:09:52,679 --> 00:09:55,399 only attracts, so its potential map is always a pit. 215 00:09:55,720 --> 00:09:58,159 Electricity can attract and repel, so you get hills for 216 00:09:58,240 --> 00:10:01,519 positive charges and pits for negative charges. But the math, 217 00:10:01,879 --> 00:10:04,840 the core idea. It held up beautifully. 218 00:10:04,399 --> 00:10:07,200 Speaker 1: Until they hit the boss fight. Ah. Yes, magnetism. 219 00:10:07,240 --> 00:10:10,799 Speaker 2: Magnetism the unruly child of classical physics, the thing that 220 00:10:10,879 --> 00:10:13,000 ruins everyone's perfectly elegant theories. 221 00:10:13,080 --> 00:10:15,480 Speaker 1: So why what makes a magnet so different from a 222 00:10:15,519 --> 00:10:17,120 star or a charged particle. 223 00:10:17,279 --> 00:10:20,720 Speaker 2: Think about the shape of the field itself. With gravity 224 00:10:20,799 --> 00:10:24,159 or electricity, the force lines radiate out from a center 225 00:10:24,399 --> 00:10:26,559 or in towards a center. They're like spikes on a 226 00:10:26,600 --> 00:10:27,840 sea ar chin, right. 227 00:10:27,720 --> 00:10:29,879 Speaker 1: They start somewhere and they end somewhere exactly. 228 00:10:30,360 --> 00:10:33,320 Speaker 2: But magnetic field lines are different. They're loops. If you 229 00:10:33,320 --> 00:10:35,960 look at a simple bar magnet, the field lines come 230 00:10:35,960 --> 00:10:38,639 out of the north pole, they loop around through space. 231 00:10:38,919 --> 00:10:41,559 They go into the south pole, and this is the 232 00:10:41,559 --> 00:10:45,159 critical part. They continue inside the magnet to come back 233 00:10:45,159 --> 00:10:47,840 to the north pole. They form a closed loop. They 234 00:10:47,840 --> 00:10:49,720 have no beginning and no end. 235 00:10:49,720 --> 00:10:51,919 Speaker 1: So you can't make an altitude map out of that. 236 00:10:52,039 --> 00:10:54,240 A hill has to have a peak, the highest point. 237 00:10:54,279 --> 00:10:56,120 You can't have a hill that just goes up forever 238 00:10:56,159 --> 00:10:58,360 in a circle. It's like an mcsher staircase. 239 00:10:58,360 --> 00:11:02,039 Speaker 2: You absolutely can't galer potential. That simple number map just 240 00:11:02,080 --> 00:11:04,960 doesn't work from agnotism because there's no highest point or 241 00:11:05,039 --> 00:11:09,440 lowest point to anchor it. So in the eighteen forties, 242 00:11:09,600 --> 00:11:13,720 this genius William Thompson, who later became Lord Kelvin, he 243 00:11:13,759 --> 00:11:16,120 had to invent a whole new kind of tool. He 244 00:11:16,159 --> 00:11:18,000 introduced something called the magnetic. 245 00:11:17,639 --> 00:11:20,919 Speaker 1: Vector potential, usually written as just the letter A the 246 00:11:20,960 --> 00:11:22,919 mystery character the mystery character. 247 00:11:23,080 --> 00:11:25,279 Speaker 2: And to make a work he had to use a 248 00:11:25,320 --> 00:11:27,240 mathematical operation called the curl. 249 00:11:27,519 --> 00:11:29,360 Speaker 1: Okay, we need to spend a minute on the curl. 250 00:11:29,360 --> 00:11:32,679 Because this is where the visualization gets really cool. The 251 00:11:32,720 --> 00:11:36,080 source we looked at uses a paddle wheel analogy, which 252 00:11:36,120 --> 00:11:37,000 I think is perfect. 253 00:11:37,159 --> 00:11:39,279 Speaker 2: It's the best way to think about it. Imagine the 254 00:11:39,320 --> 00:11:43,639 magnetic potential isn't a landscape of hills, but a river. 255 00:11:44,360 --> 00:11:46,000 It's a slowing current of. 256 00:11:45,960 --> 00:11:48,240 Speaker 1: Water, Okay, a swirling river. 257 00:11:48,480 --> 00:11:51,720 Speaker 2: Now imagine you drop a tiny microscopic tattle wheel into 258 00:11:51,759 --> 00:11:54,679 that water. If the current is moving at the exact 259 00:11:54,759 --> 00:11:58,080 same speed everywhere, the paddle wheel will just float downstream. 260 00:11:58,120 --> 00:12:00,480 Speaker 1: It won't spin at all, right, it just gets care along. 261 00:12:00,720 --> 00:12:03,000 Speaker 2: But what if the current is moving faster on the 262 00:12:03,039 --> 00:12:04,759 left side of the paddle wheel than it is on 263 00:12:04,799 --> 00:12:05,440 the right side. 264 00:12:05,480 --> 00:12:07,159 Speaker 1: Well, the fast water on the left is going to 265 00:12:07,200 --> 00:12:09,559 push that side harder, so the whole wheel will start 266 00:12:09,559 --> 00:12:09,879 to spin. 267 00:12:10,240 --> 00:12:14,600 Speaker 2: Spin. That is the curl. Thompson defined the magnetic field, 268 00:12:15,080 --> 00:12:17,240 the thing we can actually measure with the compass, the 269 00:12:17,279 --> 00:12:21,480 real force as the curl of this underlying potential. 270 00:12:21,600 --> 00:12:24,799 Speaker 1: Okay, so there's a hierarchy here at the bottom. We 271 00:12:24,919 --> 00:12:29,399 have this invisible flowing water the potential. If that water 272 00:12:29,559 --> 00:12:32,399 swirls or changes speed and just the right way, you 273 00:12:32,440 --> 00:12:35,799 get a curl and that curl is the magnetic field. 274 00:12:36,000 --> 00:12:39,240 Speaker 2: That's the mathematical relationship. So in a very real sense, 275 00:12:39,480 --> 00:12:43,279 the potential is the parent and the field is the child. 276 00:12:43,320 --> 00:12:44,720 It's derived from the potential. 277 00:12:45,120 --> 00:12:47,120 Speaker 1: And this is the huge plot twist that I think 278 00:12:47,120 --> 00:12:50,000 set physics on the wrong path for one hundred years. 279 00:12:50,440 --> 00:12:52,840 The physicists of the day didn't believe the parent was real. 280 00:12:53,000 --> 00:12:55,759 Speaker 2: No, they didn't. They decided that the water the potential 281 00:12:56,159 --> 00:12:57,279 was fake, fake. 282 00:12:57,480 --> 00:12:58,879 Speaker 1: As in like imaginary. 283 00:12:59,120 --> 00:13:02,600 Speaker 2: Just a math abstract was the polite word. They used 284 00:13:02,840 --> 00:13:06,960 a book keeping cool, a mathematical scratchbad. They came to 285 00:13:07,000 --> 00:13:09,320 believe that only the spin of the paddle wheel the 286 00:13:09,399 --> 00:13:11,039 field was physically real. 287 00:13:11,159 --> 00:13:13,440 Speaker 1: But why if the math works and it gives you 288 00:13:13,519 --> 00:13:15,879 the right answer, why would you call it fake. 289 00:13:15,960 --> 00:13:18,320 Speaker 2: It all came down to a problem called gauge invariants. 290 00:13:18,440 --> 00:13:20,279 This is kind of the villain of our story in 291 00:13:20,279 --> 00:13:20,559 a way. 292 00:13:20,639 --> 00:13:22,600 Speaker 1: Let's go back to the altitude map to explain this 293 00:13:22,639 --> 00:13:23,480 one perfect. 294 00:13:23,519 --> 00:13:27,440 Speaker 2: Okay, you're standing on a hill. Let's say your GPS 295 00:13:27,440 --> 00:13:30,159 says you're at an altitude of one thousand meters. The 296 00:13:30,200 --> 00:13:32,639 slope is steep, so gravity is pulling you down. 297 00:13:32,799 --> 00:13:33,279 Speaker 1: Got it? 298 00:13:33,360 --> 00:13:37,000 Speaker 2: Now, imagine I have some kind of cosmic being. I 299 00:13:37,080 --> 00:13:40,440 snapped my fingers, and I lift the entire continent, the oceans, 300 00:13:40,519 --> 00:13:43,480 the mountains, the valleys, everything up by ten thousand meters. 301 00:13:43,559 --> 00:13:46,120 Speaker 1: Okay, so I'm way higher up now. My GTS reads 302 00:13:46,159 --> 00:13:47,840 eleven thousand meters, right. 303 00:13:48,039 --> 00:13:49,799 Speaker 2: But has the slope of the hill you're standing on 304 00:13:50,039 --> 00:13:50,679 changed it all? 305 00:13:50,879 --> 00:13:53,200 Speaker 1: No, the steepness is exactly the same. 306 00:13:53,399 --> 00:13:55,639 Speaker 2: So the force of gravity pulling you down that hill 307 00:13:55,720 --> 00:13:58,399 is exactly the same. The physics of how you would 308 00:13:58,440 --> 00:14:00,879 tumble down that hill hasn't changed one single bit, right. 309 00:14:01,039 --> 00:14:01,399 Speaker 1: Okay. 310 00:14:01,559 --> 00:14:04,519 Speaker 2: This means I can change the absolute value of the 311 00:14:04,559 --> 00:14:08,440 potential the altitude arbitrarily. I can add ten, I could 312 00:14:08,440 --> 00:14:10,799 add a million, I can subtract five billion. As long 313 00:14:10,840 --> 00:14:13,639 as I do it everywhere equally, the physical result the 314 00:14:13,720 --> 00:14:15,360 force stays exactly the same. 315 00:14:15,480 --> 00:14:19,240 Speaker 1: I see. So the specific number one thousand meters doesn't 316 00:14:19,240 --> 00:14:21,799 actually matter. Only the difference in height from one point 317 00:14:21,799 --> 00:14:23,399 to another matters exactly. 318 00:14:23,679 --> 00:14:25,879 Speaker 2: And the physicists of the nineteenth century look at that, 319 00:14:25,919 --> 00:14:28,320 and they said, hey, wait a minute. If I can 320 00:14:28,399 --> 00:14:30,480 change this number to whatever I want and the universe 321 00:14:30,480 --> 00:14:33,360 doesn't care, then that number itself can't be real. 322 00:14:33,480 --> 00:14:36,399 Speaker 1: It's subjective. It's not a fundamental property of reality. 323 00:14:36,519 --> 00:14:40,320 Speaker 2: It's redundant. They concluded that the potential was just a 324 00:14:40,360 --> 00:14:44,279 mathematical phantom, a convenient way to calculate the slope. But 325 00:14:44,320 --> 00:14:47,320 the slip, the field, that was the only thing that 326 00:14:47,399 --> 00:14:50,559 actually existed, because the slope is unique. You can't change 327 00:14:50,600 --> 00:14:52,320 the slope without changing the physics. 328 00:14:52,399 --> 00:14:54,799 Speaker 1: So for basically one hundred years, the dogma was set 329 00:14:54,799 --> 00:14:57,759 in stone. Feels are real, Potentials are just math tricks. 330 00:14:57,879 --> 00:15:00,519 Speaker 2: Case closed, don't ask any more questions, just do the 331 00:15:00,559 --> 00:15:01,679 calculations and move on. 332 00:15:01,919 --> 00:15:06,799 Speaker 1: And that consensus held strong for decades until a couple 333 00:15:06,799 --> 00:15:10,559 of real outcasts decided to poke the bear, or maybe 334 00:15:10,559 --> 00:15:11,480 poke the solinoise. 335 00:15:11,559 --> 00:15:13,080 Speaker 2: This is where we get to the human drama of 336 00:15:13,080 --> 00:15:16,200 the episode, and we have to talk about David Boem. 337 00:15:16,840 --> 00:15:20,159 Speaker 1: This guy's origin story is just wild. You'd think a 338 00:15:20,159 --> 00:15:22,279 person who's about to rewrite the laws of physics would 339 00:15:22,320 --> 00:15:25,480 be sitting in some comfy tenured chair at Harvard or something. 340 00:15:25,759 --> 00:15:27,559 But Boem was basically on the run. 341 00:15:27,960 --> 00:15:30,559 Speaker 2: He really was. So let's set the scene. It's the 342 00:15:30,639 --> 00:15:34,799 nineteen forties, We're at Berkeley. David Boehm, is this incredibly 343 00:15:34,799 --> 00:15:40,320 brilliant PhD student, and his advisor is Jay Robert. 344 00:15:40,039 --> 00:15:42,600 Speaker 1: Oppenheimer, the father of the atomic bomb. 345 00:15:42,679 --> 00:15:45,679 Speaker 2: The very same Boehm was working on calculations that were, 346 00:15:45,759 --> 00:15:49,559 it turns out, actually critical to the Manhattan Project, specifically 347 00:15:49,679 --> 00:15:53,039 about how protons scatter. But there was a snag, a 348 00:15:53,120 --> 00:15:56,000 big one. General Leslie Groves, the military head of the 349 00:15:56,039 --> 00:15:58,960 Manhattan Project, was not a fan of Boem. He ran 350 00:15:59,000 --> 00:16:01,720 a background check and found that the Boehm had dabbled 351 00:16:01,720 --> 00:16:01,960 a bit. 352 00:16:02,039 --> 00:16:03,679 Speaker 1: He joined a communist group he. 353 00:16:03,679 --> 00:16:05,960 Speaker 2: Had, and by all accounts, it was mostly out of 354 00:16:05,960 --> 00:16:09,720 boredom and a desire for intellectual debate. He actually quit 355 00:16:09,799 --> 00:16:11,720 the group because he found the meetings dull and the 356 00:16:11,720 --> 00:16:14,759 people too dogmatic. But in the nineteen forties, just having 357 00:16:14,840 --> 00:16:16,600 had the membership card was enough. 358 00:16:16,519 --> 00:16:18,600 Speaker 1: So Groves blocks a security. 359 00:16:18,200 --> 00:16:22,279 Speaker 2: Clearance, which leads to this absolutely absurd situation. Boehm's own 360 00:16:22,360 --> 00:16:25,600 PhD thesis, the work that he wrote, was classified top 361 00:16:25,639 --> 00:16:28,639 secret because it was useful for the bomb. Boem himself 362 00:16:28,720 --> 00:16:30,200 was banned from reading his own thesis. 363 00:16:30,240 --> 00:16:32,799 Speaker 1: That is kofka esque. I mean, you can't make that up. 364 00:16:32,960 --> 00:16:36,000 Speaker 2: Oppenheimer had to go to the university administration and personally 365 00:16:36,039 --> 00:16:39,039 certified that Boehm was a brilliant physicist, so he could 366 00:16:39,080 --> 00:16:42,440 graduate without even defending his thesis because he wasn't legally 367 00:16:42,480 --> 00:16:43,600 allowed to discuss it. 368 00:16:43,720 --> 00:16:46,240 Speaker 1: And the story doesn't even end there. The war ends, 369 00:16:46,320 --> 00:16:50,559 the Cold War starts, and McCarthyism sweeps across the United States. 370 00:16:50,919 --> 00:16:54,279 Speaker 2: The Red Scare ye the House on American Activities Committee 371 00:16:54,320 --> 00:16:57,960 drags Boem in to testify against his friends and colleagues. 372 00:16:58,320 --> 00:17:01,320 He pleads the Fifth Amendment refue using to name names. 373 00:17:01,120 --> 00:17:03,639 Speaker 1: Which was an incredibly brave thing to do back then. 374 00:17:03,799 --> 00:17:06,880 Speaker 2: It was career suicide. Princeton, where he was working at 375 00:17:06,880 --> 00:17:09,400 the time, suspended him and then fired him. He was 376 00:17:09,440 --> 00:17:11,720 effectively blacklisted from American academia. 377 00:17:11,839 --> 00:17:15,599 Speaker 1: And Oppenheimer, who was powerful but was also under a 378 00:17:15,599 --> 00:17:18,799 lot of suspicion himself, basically told Boehm, you need to 379 00:17:18,880 --> 00:17:20,680 leave the country before they completely crush you. 380 00:17:21,240 --> 00:17:24,839 Speaker 2: So Bom goes into exile. He moves to Brazil, then 381 00:17:24,839 --> 00:17:28,680 to Israel, and finally he lands a position in Bristol 382 00:17:28,799 --> 00:17:29,359 in the UK. 383 00:17:29,640 --> 00:17:32,319 Speaker 1: And I think this context is just so important. Boehm 384 00:17:32,519 --> 00:17:35,319 was a true outsider. He had been schewed up and 385 00:17:35,400 --> 00:17:38,160 spit out by the establishment and when you're an outsider, 386 00:17:38,200 --> 00:17:41,480 you're just much less likely to blindly follow the establishment's 387 00:17:41,599 --> 00:17:42,680 rules about physics. 388 00:17:42,759 --> 00:17:46,720 Speaker 2: Absolutely, he had nothing left to lose by questioning the fundamentals. 389 00:17:46,880 --> 00:17:48,839 He was willing to look at the foundations of quantum 390 00:17:48,880 --> 00:17:52,200 mechanics and say, you know what, this doesn't really make sense. 391 00:17:52,319 --> 00:17:54,960 Speaker 1: So in Bristol he teams up with this brilliant grad 392 00:17:55,079 --> 00:17:59,119 student named Yaki Aharanov. And Ahranov isn't trying to solve 393 00:17:59,119 --> 00:18:03,480 some specific engineering problem. He's just he's just poking at 394 00:18:03,519 --> 00:18:05,119 the Schrodinger equation. 395 00:18:04,960 --> 00:18:08,559 Speaker 2: The holy grail of quantum mechanics, the central equation. 396 00:18:08,480 --> 00:18:10,640 Speaker 1: And he notices something that everyone else had just sort 397 00:18:10,640 --> 00:18:11,160 of ignored. 398 00:18:11,359 --> 00:18:14,920 Speaker 2: He notices that the Schrodinger equation, the fundamental formula for 399 00:18:14,960 --> 00:18:20,400 how particles behave as waves, is written using potentials, not fields. 400 00:18:20,960 --> 00:18:25,720 It explicitly usestel fee for the electric potential and other 401 00:18:25,799 --> 00:18:27,200 for the magnetic potential. 402 00:18:27,680 --> 00:18:31,440 Speaker 1: Now, the standard textbook answer for decades had been so what, 403 00:18:31,680 --> 00:18:34,000 it's just written that way for convenience. It's that math 404 00:18:34,039 --> 00:18:34,599 trick again. 405 00:18:35,000 --> 00:18:39,559 Speaker 2: But Aharnov argued, and this is the absolute key insight 406 00:18:40,000 --> 00:18:42,400 that you cannot just swamp the potential for the field 407 00:18:42,480 --> 00:18:44,920 in that equation without fundamentally breaking it. 408 00:18:45,000 --> 00:18:45,319 Speaker 1: Why not? 409 00:18:45,599 --> 00:18:47,599 Speaker 2: It has to do with integration. Let's do a quick, 410 00:18:47,720 --> 00:18:51,039 painless calculus for refresher. If I have a function, say 411 00:18:51,079 --> 00:18:52,480 the field, and I want to get back to the 412 00:18:52,480 --> 00:18:55,559 potential I have integrated and the source we've reviewed use 413 00:18:55,599 --> 00:18:58,119 a great example. If I have the expression ten biole 414 00:18:58,200 --> 00:19:00,880 of dollars and I tell you to integrate it, what 415 00:19:00,960 --> 00:19:01,559 do you get? 416 00:19:01,720 --> 00:19:04,319 Speaker 1: You get five by two two dollars plus C plus C. 417 00:19:04,599 --> 00:19:06,960 Speaker 2: Yeah, you always get plus a constant, that. 418 00:19:06,960 --> 00:19:09,799 Speaker 1: Pesky little constant of integration. 419 00:19:09,400 --> 00:19:12,319 Speaker 2: In classical physics. That C is the arbitrary number. It's 420 00:19:12,319 --> 00:19:15,480 the sea level. It doesn't matter. It watches out. But 421 00:19:15,559 --> 00:19:18,839 Harnoff looked at the quantum math and realized, wait a minute, 422 00:19:19,519 --> 00:19:22,640 in this equation, the sea isn't just disappearing, it's doing something. 423 00:19:22,839 --> 00:19:26,359 Speaker 1: He suspected that the potential contained information that the field 424 00:19:26,359 --> 00:19:29,000 had literally thrown away in the process of being calculated. 425 00:19:29,240 --> 00:19:32,759 Speaker 2: Precisely, he realized that if you try to rewrite quantum 426 00:19:32,759 --> 00:19:35,960 mechanics using only the fields E and B, the equation 427 00:19:36,079 --> 00:19:39,559 becomes a horrible, non local mess. It's hideous. But if 428 00:19:39,559 --> 00:19:43,240 you use the potentials, you'll owneio. It's simple and elegant. 429 00:19:43,480 --> 00:19:47,079 Speaker 1: So he proposes this radical idea. What if the electron 430 00:19:47,200 --> 00:19:49,519 isn't reading the field at all, What if the electron 431 00:19:49,599 --> 00:19:51,480 is directly reading the potential. 432 00:19:51,839 --> 00:19:54,680 Speaker 2: This is a massive paradigm shift. He's basically saying the 433 00:19:54,680 --> 00:19:57,839 ghost in the math, the potential is the real actor, 434 00:19:58,200 --> 00:20:00,359 and the force we measure the field is just a 435 00:20:00,400 --> 00:20:01,400 derivative side effect. 436 00:20:01,519 --> 00:20:06,240 Speaker 1: But extraordinary claims require extraordinary proof. They couldn't just argue 437 00:20:06,240 --> 00:20:08,960 about the math. They had to design an experiment, and 438 00:20:08,960 --> 00:20:09,319 this is. 439 00:20:09,240 --> 00:20:11,799 Speaker 2: Where the pure genius of the Aharanov bone paper from 440 00:20:11,880 --> 00:20:14,799 nineteen fifty nine comes in. They designed an experiment that 441 00:20:14,960 --> 00:20:18,359 was effectively a perfect trap for the old force field theory. 442 00:20:18,599 --> 00:20:20,960 Speaker 1: They needed to create a situation where the magnetic field 443 00:20:21,039 --> 00:20:24,680 is absolutely zero, but the potential is not zero, because. 444 00:20:24,440 --> 00:20:26,799 Speaker 2: If the electron reacts in that zone, if it changes 445 00:20:26,839 --> 00:20:30,440 its behavior, then the potential has to be real. Case closed. 446 00:20:30,960 --> 00:20:33,079 Speaker 1: How how in the world do you build a box 447 00:20:33,119 --> 00:20:36,160 of nothing that is simultaneously full of something. You use 448 00:20:36,160 --> 00:20:37,839 a solenoid, a simple coil of wire. 449 00:20:37,920 --> 00:20:39,759 Speaker 2: A simple coil of wire, think of a spring, a 450 00:20:39,799 --> 00:20:42,599 tightly wound spiral of copper. When you run an electric 451 00:20:42,640 --> 00:20:46,640 current through it, It creates a magnetic field basic electromagnetism 452 00:20:46,720 --> 00:20:49,200 one on one, but the geometry is very special. The 453 00:20:49,240 --> 00:20:52,119 magnetic field is trapped inside the coil. It runs straight 454 00:20:52,160 --> 00:20:52,960 down the middle of the. 455 00:20:52,920 --> 00:20:55,680 Speaker 1: Tube, like water flowing through a pipe. 456 00:20:55,319 --> 00:20:59,559 Speaker 2: Exactly, but outside the coil, if the solenoid is long enough, 457 00:20:59,559 --> 00:21:01,440 the magnetic field is effectively zero. 458 00:21:01,799 --> 00:21:05,160 Speaker 1: So outside the pipe there is no magnetic force. A 459 00:21:05,200 --> 00:21:06,799 compass held out there wouldn't spin. 460 00:21:07,000 --> 00:21:12,920 Speaker 2: Correct, the magnetic field B equals zero. However, remember the curl. 461 00:21:13,079 --> 00:21:14,039 Remember our little. 462 00:21:13,799 --> 00:21:15,319 Speaker 1: Paddle wheels swirling water. 463 00:21:15,599 --> 00:21:18,160 Speaker 2: The math says that even though the slope the field 464 00:21:18,359 --> 00:21:22,480 is zero outside the coil, the underlying potential is still 465 00:21:22,480 --> 00:21:24,240 swirling around the outside of that coil. 466 00:21:24,440 --> 00:21:26,960 Speaker 1: Wait, let me get this straight. The actual force is 467 00:21:27,000 --> 00:21:30,720 trapped inside the pipe, but the ghost water the potential 468 00:21:31,119 --> 00:21:33,599 is swirling around the exterior of the pipe. 469 00:21:33,839 --> 00:21:38,200 Speaker 2: Yes, it's like a whirlpool surrounding a perfectly calm island. 470 00:21:39,160 --> 00:21:42,519 The potential gets weaker as you move further away, but 471 00:21:42,640 --> 00:21:45,039 it is definitely non negotiably there. 472 00:21:45,160 --> 00:21:47,039 Speaker 1: So here's the plan they came up with. You take 473 00:21:47,079 --> 00:21:49,880 a beam of electrons, You use a splitter to send 474 00:21:49,880 --> 00:21:52,680 them down two separate paths. Path one goes over the 475 00:21:52,680 --> 00:21:55,359 top of the solenoid. Path two goes under the bottom. 476 00:21:55,480 --> 00:21:59,440 Speaker 2: And this is the crucial part. Neither path ever touches 477 00:21:59,559 --> 00:22:03,400 or enters the solenoid itself. They travel entirely through that 478 00:22:03,519 --> 00:22:05,279 region where the magnetic field is zero. 479 00:22:05,440 --> 00:22:08,400 Speaker 1: They are flying through the void. No force touches them. 480 00:22:08,519 --> 00:22:11,359 Speaker 2: According to Newton, and according to all of classical physics, 481 00:22:12,000 --> 00:22:15,480 absolutely nothing should happen to them. They should behave exactly 482 00:22:15,480 --> 00:22:17,160 as if the solenode wasn't even there. 483 00:22:17,240 --> 00:22:20,160 Speaker 1: But Boem and a. Harnoff predicted something very different. 484 00:22:20,240 --> 00:22:23,240 Speaker 2: They predicted that the electrons would feel the potential. 485 00:22:23,400 --> 00:22:26,000 Speaker 1: But how how can it feel something if there's no. 486 00:22:26,079 --> 00:22:29,240 Speaker 2: Force through the phase of their wave function. You have 487 00:22:29,279 --> 00:22:32,279 to remember in quantum mechanics, an electron isn't just a dot, 488 00:22:32,640 --> 00:22:35,160 it's a wave. It oscillates, It goes up. 489 00:22:35,119 --> 00:22:37,000 Speaker 1: And down like a little clock ticking. 490 00:22:37,240 --> 00:22:39,359 Speaker 2: That's a great way to put it. Think of it 491 00:22:39,400 --> 00:22:42,279 like a clock on the back of each electron, ticking 492 00:22:42,440 --> 00:22:46,279 at a very specific frequency. Now, on the top path, 493 00:22:46,720 --> 00:22:49,640 the electron is moving in the same direction as the 494 00:22:49,720 --> 00:22:50,799 swirling potential. 495 00:22:51,079 --> 00:22:53,240 Speaker 1: It's going with the flow of the ghost water. 496 00:22:53,160 --> 00:22:56,839 Speaker 2: And that interaction the potential acting on the wave actually 497 00:22:57,160 --> 00:22:59,920 changes the speed of the ticking. It advances the clo 498 00:23:00,599 --> 00:23:02,680 it shifts the phase. And on the bottom path, the 499 00:23:02,680 --> 00:23:05,119 electron is moving against the swirling potential. 500 00:23:05,960 --> 00:23:08,880 Speaker 1: It's going upstream, so it's clock ticks at a different speed. 501 00:23:08,880 --> 00:23:10,519 It gets delayed exactly. 502 00:23:10,799 --> 00:23:13,160 Speaker 2: So when these two electrons from the top path and 503 00:23:13,240 --> 00:23:15,240 the bottom path meet up on the other side of 504 00:23:15,240 --> 00:23:18,200 the solenoid and recombine, their clocks are out of sinc 505 00:23:18,359 --> 00:23:19,519 Their waves are out of phase. 506 00:23:19,640 --> 00:23:21,240 Speaker 1: And when waves are out of phase, you get an 507 00:23:21,240 --> 00:23:22,240 interference pattern. 508 00:23:22,279 --> 00:23:24,839 Speaker 2: The peaks don't line up with the peaks anymore, the 509 00:23:24,880 --> 00:23:28,039 troughs don't line up with the troughs. Everything shifts. This 510 00:23:28,079 --> 00:23:31,920 creates a visible, measurable shift in the interference pattern the 511 00:23:31,960 --> 00:23:34,119 bright and dark stripes on the detector screen. 512 00:23:34,279 --> 00:23:37,240 Speaker 1: So the final prediction is this, I flip a switch, 513 00:23:37,599 --> 00:23:41,480 turning on the solenoid. The magnetic field outside remains zero. 514 00:23:42,039 --> 00:23:45,920 No force ever touches the electrons, but the interference pattern 515 00:23:45,960 --> 00:23:48,920 on the screen jumps to the side. The electrons know 516 00:23:49,599 --> 00:23:50,440 the magnet is on. 517 00:23:50,880 --> 00:23:53,440 Speaker 2: That just wasn't says to happen. It's action without a 518 00:23:53,480 --> 00:23:54,920 force it's spooky. 519 00:23:55,039 --> 00:23:57,759 Speaker 1: So the reaction from the physics community at the time was, 520 00:23:58,599 --> 00:23:59,960 let's just say skeptical. 521 00:24:00,279 --> 00:24:05,119 Speaker 2: Skeptical as being polite. Neil's Boorr, the godfather of quantum mechanics, 522 00:24:05,440 --> 00:24:08,319 the high priests of the Copenhagen interpretation, he hated it. 523 00:24:08,640 --> 00:24:11,000 He absolutely could not accept that a particle could be 524 00:24:11,000 --> 00:24:13,960 affected without a local force. He spent weeks trying to 525 00:24:13,960 --> 00:24:15,799 find a flaw in their logic and couldn't. 526 00:24:15,880 --> 00:24:18,839 Speaker 1: But Richard Feineman Fineman is always my favorite character in 527 00:24:18,880 --> 00:24:20,519 the story of physics. What did he think? 528 00:24:20,759 --> 00:24:22,839 Speaker 2: Fineman loved it. He looked at it, and his reaction 529 00:24:23,039 --> 00:24:26,319 was basically, well, of course, it's obvious, scrange. No one 530 00:24:26,359 --> 00:24:29,440 thought of it before. He saw immediately that the mathematics 531 00:24:29,440 --> 00:24:32,000 of his own path integal formulation demanded it. 532 00:24:32,039 --> 00:24:34,680 Speaker 1: And there was another one, Victor Weiskopf, another giant of 533 00:24:34,680 --> 00:24:37,319 the field, who had that great quote, Oh yeah, he said. 534 00:24:37,400 --> 00:24:40,319 Speaker 2: My first reaction, it's wrong. My second reaction, it's obvious. 535 00:24:40,440 --> 00:24:42,839 Speaker 1: And that's the mark of a real paradigm shift, isn't it. It 536 00:24:42,880 --> 00:24:46,519 goes from that's impossible and you're crazy to well, of course, 537 00:24:46,559 --> 00:24:47,599 how did we not see that? 538 00:24:47,720 --> 00:24:51,559 Speaker 2: It completely reframes the problem. But you know, a theory 539 00:24:51,559 --> 00:24:53,960 on paper is just talk. Someone had to actually build 540 00:24:54,000 --> 00:24:54,680 the damn. 541 00:24:54,440 --> 00:24:57,440 Speaker 1: Thing, and this was incredibly difficult to do in practice. 542 00:24:57,519 --> 00:25:00,839 The first attempt was in nineteen sixty by a physicist 543 00:25:01,039 --> 00:25:02,839 named Robert Chambers. 544 00:25:02,400 --> 00:25:05,720 Speaker 2: And his biggest problem was the infinite solenoid assumption. Right, 545 00:25:05,759 --> 00:25:07,759 you can't just go to the store and buy an 546 00:25:07,759 --> 00:25:08,839 infinitely long wire. 547 00:25:08,960 --> 00:25:14,039 Speaker 1: No, and real solenoids have ends, and magnetic fields leak 548 00:25:14,160 --> 00:25:16,559 out of the ends of the solenoid. They create what's 549 00:25:16,599 --> 00:25:17,680 called a fringe field. 550 00:25:18,240 --> 00:25:21,039 Speaker 2: So Chambers runs the experiment and he sees the shift. 551 00:25:21,400 --> 00:25:23,960 The interference pattern moves just like they predicted. 552 00:25:24,240 --> 00:25:27,720 Speaker 1: But the skeptics immediately pounce. They said, Aha, see your 553 00:25:27,759 --> 00:25:31,079 solenoid isn't infinite. There are leakage fields. The electron isn't 554 00:25:31,079 --> 00:25:34,400 touching some magical ghost potential. It's touching a tiny stray 555 00:25:34,519 --> 00:25:38,200 magnetic field leaking from the top and bottom. Your experiment is. 556 00:25:38,160 --> 00:25:41,880 Speaker 2: Just sloppy, and it's a valid critique. To prove the 557 00:25:41,920 --> 00:25:45,640 effect is real, you have to be absolutely one hundred 558 00:25:45,640 --> 00:25:49,880 percent certain that there is zero magnetic field touching the electron. 559 00:25:50,119 --> 00:25:52,599 If there's even a tiny bit the whole potential is real, 560 00:25:52,720 --> 00:25:53,920 argument falls apart. 561 00:25:54,039 --> 00:25:56,599 Speaker 1: It took twenty six years to get the definitive answer 562 00:25:57,079 --> 00:26:01,200 nineteen eighty six, a kiratonoma at Hitashi in Japan. 563 00:26:01,559 --> 00:26:06,400 Speaker 2: Totamore was a true experimental artist, a perfectionist. He was 564 00:26:06,440 --> 00:26:08,119 not going to leave any room for doubt. 565 00:26:08,200 --> 00:26:11,000 Speaker 1: He realized that the long straight wire approach was always 566 00:26:11,039 --> 00:26:13,559 going to be flawed, so he changed the geometry. He 567 00:26:13,640 --> 00:26:16,519 used a toroid, the donut magnetic donut. 568 00:26:16,359 --> 00:26:18,640 Speaker 2: With a donut shape, the magnetic field can just go 569 00:26:18,759 --> 00:26:21,160 round and around in a perfect circle inside the dough. 570 00:26:21,480 --> 00:26:23,880 It never has to leave the material. It has no ends, 571 00:26:24,039 --> 00:26:25,599 so there's nothing to leak from. 572 00:26:25,759 --> 00:26:28,519 Speaker 1: That's brilliant. But he didn't even stop there. He wanted 573 00:26:28,559 --> 00:26:31,200 to be paranoid. He wanted to be absolutely sure nothing 574 00:26:31,200 --> 00:26:32,319 could possibly. 575 00:26:31,960 --> 00:26:35,000 Speaker 2: Leak out, So he wrapped the entire magnetic donut in 576 00:26:35,079 --> 00:26:36,279 a layer of niobium. 577 00:26:36,359 --> 00:26:38,119 Speaker 1: And naobium is a superconductor. 578 00:26:38,319 --> 00:26:40,960 Speaker 2: It is and superconductors have this amazing property called the 579 00:26:41,000 --> 00:26:46,799 Meisner effect. They actively expel magnetic fields. They're the ultimate 580 00:26:46,839 --> 00:26:50,519 magnetic shield. By wrapping his magnet in a superconducting layer, 581 00:26:50,839 --> 00:26:54,119 he physically guaranteed that the magnetic field outside that donut. 582 00:26:53,799 --> 00:26:56,599 Speaker 1: Was zero, not almost zero, not close to zero. 583 00:26:56,599 --> 00:27:00,400 Speaker 2: Zero point zero. And then he used a new technology 584 00:27:00,559 --> 00:27:05,119 called holographic electron microscopy to actually visualize the wavefronts of 585 00:27:05,160 --> 00:27:07,240 the electrons. This is bleeding edge stuff. 586 00:27:07,359 --> 00:27:09,839 Speaker 1: So let's just recap the setup. You have an electron beam. 587 00:27:10,039 --> 00:27:13,440 It's aimed at a tiny, perfectly shielded magnetic donut. The 588 00:27:13,440 --> 00:27:15,480 beam is set to go right through the hole of 589 00:27:15,519 --> 00:27:19,079 the donut. The field in the hole is zero. The potential, however, 590 00:27:19,240 --> 00:27:20,039 is swirling. 591 00:27:20,119 --> 00:27:23,039 Speaker 2: He turned on the current and he looked at the hologram. 592 00:27:23,079 --> 00:27:23,759 Speaker 1: What did he see? 593 00:27:23,839 --> 00:27:27,400 Speaker 2: The phase shifted perfectly. The peaks of the electron waves 594 00:27:27,440 --> 00:27:29,480 lined up with the drops, exactly as a Hornoff and 595 00:27:29,480 --> 00:27:31,880 Boom had predicted nearly thirty years earlier. 596 00:27:31,960 --> 00:27:34,039 Speaker 1: So it's real. The ghost is real, The. 597 00:27:33,920 --> 00:27:37,519 Speaker 2: Ghost is real. The potential, that thing that physicists for 598 00:27:37,559 --> 00:27:40,880 a century had called a bookkeeping trick and abstract scratch 599 00:27:40,960 --> 00:27:44,680 pad number, actually reached out across empty space and touched 600 00:27:44,680 --> 00:27:45,319 the electron. 601 00:27:45,559 --> 00:27:47,680 Speaker 1: This is the part where my brain just starts to melt, 602 00:27:47,880 --> 00:27:49,640 because now we have to interpret this. What does this 603 00:27:49,680 --> 00:27:51,799 actually mean about the nature of reality? 604 00:27:51,960 --> 00:27:54,599 Speaker 2: It means we have to choose between two maybe three, 605 00:27:55,079 --> 00:27:56,440 very uncomfortable. 606 00:27:55,880 --> 00:27:57,880 Speaker 1: Option Eh, lay the mummy, what's option one? 607 00:27:58,079 --> 00:28:02,799 Speaker 2: Option one? Potential are real? This is the view that 608 00:28:02,880 --> 00:28:06,599 Bowman feinement generally lean towards team potential team potential. This 609 00:28:06,680 --> 00:28:10,880 view says we were wrong for two hundred years. The 610 00:28:10,920 --> 00:28:14,039 field the force is not the fundamental layer of reality. 611 00:28:14,440 --> 00:28:17,680 The potential is the fundamental layer of reality. The universe 612 00:28:17,720 --> 00:28:20,680 is literally made of these scaler and vector values that 613 00:28:20,720 --> 00:28:22,880 are assigned to every single point in space. 614 00:28:23,039 --> 00:28:26,039 Speaker 1: We're all just navigating an invisible landscape of numbers that 615 00:28:26,119 --> 00:28:27,400 dictates how we move. 616 00:28:27,680 --> 00:28:30,000 Speaker 2: Yes, and the force that we feel is just what 617 00:28:30,079 --> 00:28:33,319 happens when that landscape changes shape. As Feinemann wrote in 618 00:28:33,359 --> 00:28:36,720 his lectures, A is as real as B realer, whatever 619 00:28:36,759 --> 00:28:37,240 that means. 620 00:28:37,440 --> 00:28:40,440 Speaker 1: But wait, what about the gauge invariance problem, the whole 621 00:28:40,440 --> 00:28:42,440 C level issue. If I can add a thousand to 622 00:28:42,480 --> 00:28:46,519 the potential everywhere and nothing changes, doesn't that still prove 623 00:28:46,559 --> 00:28:47,920 its arbitrary and not real? 624 00:28:48,319 --> 00:28:51,400 Speaker 2: Ah? This is the really subtle and beautiful part. The 625 00:28:51,440 --> 00:28:54,599 Aronoff Bom effect relies on the electron taking a loop, 626 00:28:54,920 --> 00:28:57,720 it splits and then comes back together. Okay, when you 627 00:28:57,759 --> 00:29:00,680 do the mathematics, of an integral around a c closed loop. 628 00:29:01,039 --> 00:29:05,319 The arbitrary constants that plus C they cancel out. If 629 00:29:05,359 --> 00:29:07,799 I raise the sea level by one thousand meters, I'm 630 00:29:07,880 --> 00:29:10,160 raising it for both the top path and the bottom path, 631 00:29:10,599 --> 00:29:13,160 so the difference in the altitude between the two paths 632 00:29:13,440 --> 00:29:14,559 stays exactly the same. 633 00:29:14,640 --> 00:29:17,279 Speaker 1: So the absolute value of the potential might be arbitrary, 634 00:29:17,359 --> 00:29:19,720 but the topology, the way it changes as you go 635 00:29:19,759 --> 00:29:22,720 around a loop that's absolute and physically real exactly. 636 00:29:22,880 --> 00:29:25,960 Speaker 2: The loop intergral is gauge invariant, the math is solid. 637 00:29:26,359 --> 00:29:27,920 The loop makes the potential real. 638 00:29:28,079 --> 00:29:30,799 Speaker 1: Okay, I think I can live with that. Invisible landscapes. 639 00:29:31,000 --> 00:29:31,759 What's option two? 640 00:29:31,839 --> 00:29:35,160 Speaker 2: Option two? Non locality. This is actually where aronoff himself. 641 00:29:35,200 --> 00:29:37,079 Eventually landity changed his mind over the years. 642 00:29:37,160 --> 00:29:40,440 Speaker 1: Non locality. That's the spooky action at a distance. Stuff. 643 00:29:40,680 --> 00:29:43,440 Speaker 2: That's the one. This view says, no, no, No. Potentials are 644 00:29:43,480 --> 00:29:46,440 still just math tools. The fields are the only real things. 645 00:29:47,200 --> 00:29:52,079 Speaker 1: But but the field was zero where the electron was exactly. 646 00:29:52,160 --> 00:29:55,480 Speaker 2: So if the field is the only real thing and 647 00:29:55,519 --> 00:29:59,200 the field is trapped inside the doughnut, then the field 648 00:29:59,319 --> 00:30:01,400 must be effected in the electron from a distance. 649 00:30:01,839 --> 00:30:05,279 Speaker 1: So it's telekinesis the magnetic field inside the donut is 650 00:30:05,359 --> 00:30:08,759 pushing the electron outside the donut without ever making contact, 651 00:30:08,839 --> 00:30:10,599 without any intermediary. 652 00:30:10,119 --> 00:30:13,680 Speaker 2: Yes, and this just shatters the golden rule of Einsteinian physics, 653 00:30:13,799 --> 00:30:17,440 which is locality, the idea that things can only affect 654 00:30:17,440 --> 00:30:20,880 their immediate surroundings. If option two is right, then the 655 00:30:21,000 --> 00:30:25,079 universe is fundamentally interconnected in a way that allows for instantaneous, 656 00:30:25,160 --> 00:30:26,079 non local. 657 00:30:25,799 --> 00:30:27,960 Speaker 1: Influence That is deeply unsettling. 658 00:30:28,400 --> 00:30:30,759 Speaker 2: It upsets the entire cause and effect structure that we 659 00:30:30,839 --> 00:30:32,440 rely on in classical physics. 660 00:30:32,599 --> 00:30:34,799 Speaker 1: So you have to pick your poison. Either the universe 661 00:30:34,839 --> 00:30:37,680 is run by invisible math numbers that we can't directly see, 662 00:30:37,720 --> 00:30:40,799 which is team potential, or things can touch you from 663 00:30:40,799 --> 00:30:43,440 across the room without anything traveling between you, which is 664 00:30:43,480 --> 00:30:44,279 team nonlocal. 665 00:30:44,559 --> 00:30:46,400 Speaker 2: There is sort of a third way, a kind of 666 00:30:46,400 --> 00:30:48,440 mill ground. We could call it option three. The path 667 00:30:48,480 --> 00:30:49,160 integral view. 668 00:30:49,519 --> 00:30:52,640 Speaker 1: The Casper the friendly ghost speculation. 669 00:30:52,359 --> 00:30:56,400 Speaker 2: Is Feinnman's view of quantum mechanics. In his path integral formulation, 670 00:30:57,039 --> 00:30:59,799 a particle doesn't take just one path from A to B. 671 00:31:00,519 --> 00:31:03,559 It takes every possible path simultaneously. 672 00:31:03,640 --> 00:31:05,359 Speaker 1: The multiverse of paths. 673 00:31:05,200 --> 00:31:08,359 Speaker 2: Right so even though the main path for the electron 674 00:31:08,440 --> 00:31:10,200 goes through the whole of the doughnut where the field 675 00:31:10,240 --> 00:31:14,839 is zero, there are other less probable ghost paths that 676 00:31:14,920 --> 00:31:18,039 might actually tunnel through the magnet itself, touch the field, 677 00:31:18,359 --> 00:31:19,680 and then rejoin the main group. 678 00:31:20,119 --> 00:31:23,359 Speaker 1: So the electron did touch the field, it's just the 679 00:31:23,480 --> 00:31:26,160 version of the electron that did that wasn't the main 680 00:31:26,200 --> 00:31:27,079 one we were tracking. 681 00:31:27,319 --> 00:31:29,799 Speaker 2: In a manner of speaking, it's like the particle sends 682 00:31:29,799 --> 00:31:34,160 out feelers along all paths, samples the entire environment brings 683 00:31:34,160 --> 00:31:37,200 that information back, and that's what shifts the phase. It 684 00:31:37,319 --> 00:31:40,599 saves locality, but it requires you to accept that particles 685 00:31:40,599 --> 00:31:43,319 are kind of doing everything everywhere all at once. 686 00:31:43,440 --> 00:31:45,039 Speaker 1: I think I need to sit down for a minute. 687 00:31:45,119 --> 00:31:46,480 Speaker 2: It's heavy stuff, it really is. 688 00:31:46,880 --> 00:31:50,000 Speaker 1: And just to twist the knife one last time. This 689 00:31:50,160 --> 00:31:52,799 isn't just some weird quirk of electricity, is it. 690 00:31:53,039 --> 00:31:56,119 Speaker 2: No, it's not. For a long time we thought maybe 691 00:31:56,119 --> 00:31:59,240 this was just a weird thing about electromagnetism, But very 692 00:31:59,279 --> 00:32:03,279 recently twenty twenty two, a team of researchers at Stanford 693 00:32:03,839 --> 00:32:06,079 finally managed to test this with gravity. 694 00:32:06,240 --> 00:32:08,680 Speaker 1: With gravity the original force. 695 00:32:08,519 --> 00:32:11,720 Speaker 2: They use something called atomic fountains. They take these ultra 696 00:32:11,799 --> 00:32:14,839 coold rubidium atoms and launch them up in a vacuum. 697 00:32:14,519 --> 00:32:16,119 Speaker 1: Tube, and they split them somehow. 698 00:32:16,240 --> 00:32:19,119 Speaker 2: They use lasers to split the wave function of the atom, 699 00:32:19,279 --> 00:32:22,000 so one part of the atom's wave goes slightly higher 700 00:32:22,079 --> 00:32:22,720 than the other part. 701 00:32:22,799 --> 00:32:25,599 Speaker 1: So they were at two different altitudes on the gravitational 702 00:32:25,640 --> 00:32:26,920 potential hill exactly. 703 00:32:26,960 --> 00:32:30,200 Speaker 2: They were exploring different values of the gravitational potential. Yeah, 704 00:32:30,519 --> 00:32:33,039 and even when they accounted for every other possible effect, 705 00:32:33,319 --> 00:32:34,519 they saw the phase shift. 706 00:32:34,640 --> 00:32:35,880 Speaker 1: So gravity does it too. 707 00:32:35,720 --> 00:32:38,799 Speaker 2: Gravity does it too. It seems this effect, this connection 708 00:32:38,880 --> 00:32:41,599 to the potential, is not a bug. It's a fundamental 709 00:32:41,599 --> 00:32:42,759 feature of our universe. 710 00:32:42,960 --> 00:32:46,279 Speaker 1: Wow, so let's just try to wrap this whole thing up. 711 00:32:46,440 --> 00:32:50,079 We started with Isaac Newton crying over his vector arrows 712 00:32:50,119 --> 00:32:52,720 because the three body problem was too hard. 713 00:32:53,000 --> 00:32:56,960 Speaker 2: Then we invented a math hack called potentials to make 714 00:32:57,000 --> 00:32:57,960 the problem easier. 715 00:32:58,079 --> 00:33:01,119 Speaker 1: We then spent the next two hundred years telling physics students, 716 00:33:01,400 --> 00:33:04,160 by the way, that hack is fake, it's not real, 717 00:33:04,440 --> 00:33:05,920 just use it to pass the test. 718 00:33:06,160 --> 00:33:10,119 Speaker 2: And then, thanks to an exile physicist and his curious student, 719 00:33:10,480 --> 00:33:12,599 we ran in an experiment that proved the hack is 720 00:33:12,640 --> 00:33:13,799 actually the reality. 721 00:33:13,960 --> 00:33:16,759 Speaker 1: There's that old saying the map is not the territory, 722 00:33:17,440 --> 00:33:19,640 But in this case, it's like we found out the 723 00:33:19,680 --> 00:33:20,720 map is the territory. 724 00:33:20,880 --> 00:33:22,799 Speaker 2: Or perhaps we were looking at the map the whole 725 00:33:22,799 --> 00:33:24,920 time and mistakenly calling it the world. 726 00:33:25,319 --> 00:33:28,359 Speaker 1: It really just highlights the danger of dogma and science, 727 00:33:28,440 --> 00:33:31,720 doesn't it. If Bohm hadn't been pushed to the outside, 728 00:33:31,759 --> 00:33:33,640 if he had stayed in the comfortable center of the 729 00:33:33,640 --> 00:33:36,920 physics establishment, maybe he never would have had the guts 730 00:33:36,960 --> 00:33:38,079 to question the rules. 731 00:33:38,400 --> 00:33:40,680 Speaker 2: Sometimes you have to be standing outside the donut to 732 00:33:40,680 --> 00:33:41,880 see what's happening in the hole. 733 00:33:42,359 --> 00:33:44,119 Speaker 1: I love that that's a perfect summary. 734 00:33:44,400 --> 00:33:46,759 Speaker 2: It's a lesson for all of us. Really, just because 735 00:33:46,759 --> 00:33:49,359 a model works, just because you can build bridges and 736 00:33:49,440 --> 00:33:51,480 land on the moon with it, doesn't mean it's the 737 00:33:51,559 --> 00:33:56,160 ultimate truth. Newton's laws got us to the moon, but 738 00:33:56,200 --> 00:33:57,200 they couldn't explain this. 739 00:33:57,279 --> 00:34:01,920 Speaker 1: Electron textbooks are always provisional. So I have to ask 740 00:34:01,960 --> 00:34:04,720 a final question, both to you and to everyone listening. 741 00:34:05,240 --> 00:34:06,359 Where do you stand on this? 742 00:34:07,119 --> 00:34:09,239 Speaker 2: It's the ultimate vote on the nature of reality. 743 00:34:09,719 --> 00:34:12,880 Speaker 1: Are you team potential? Do you like the idea that 744 00:34:12,920 --> 00:34:17,039 we're guided by this invisible landscape, these hidden scaler values 745 00:34:17,119 --> 00:34:19,119 that make up a kind of script for the universe. 746 00:34:19,840 --> 00:34:22,920 Or are you Team non Local. Do you prefer the 747 00:34:22,920 --> 00:34:26,880 spookier idea that the universe is a single, interconnected web 748 00:34:27,320 --> 00:34:29,599 where things can touch each other from a distance across 749 00:34:29,599 --> 00:34:30,039 the void? 750 00:34:30,199 --> 00:34:31,320 Speaker 2: You know, I think I'm gonna have to go with 751 00:34:31,400 --> 00:34:35,199 Team Non Local. I like the idea of that fundamental connectivity. 752 00:34:35,519 --> 00:34:37,840 It's weird, but it feels more holistic. 753 00:34:38,199 --> 00:34:40,639 Speaker 1: See I'm going Team Potential. I like the idea of 754 00:34:40,679 --> 00:34:44,599 a hidden landscape. It feels more grand and architectural. 755 00:34:44,840 --> 00:34:46,280 Speaker 2: Well, we want to hear from you. Leave a comment 756 00:34:46,280 --> 00:34:48,639 wherever you are listening. Let us know your vote, Team 757 00:34:48,679 --> 00:34:51,039 Potential or Team Non Local. Let us know which one 758 00:34:51,079 --> 00:34:52,079 is more unsettling to you. 759 00:34:52,360 --> 00:34:55,199 Speaker 1: Thanks for unspooling these mysteries with us. It has been 760 00:34:55,360 --> 00:34:58,840 a truly mind bending ride. This has been thrilling threads. 761 00:34:59,000 --> 00:35:01,079 Speaker 2: Keep pull into those loose ends. You never know what's 762 00:35:01,079 --> 00:35:01,760 going to unravel. 763 00:35:02,000 --> 00:35:02,840 Speaker 1: We'll see you next time.