WEBVTT 1 00:00:01.480 --> 00:00:05.599 Welcome to the core side. Quantum Physics podcast, an exploration 2 00:00:05.679 --> 00:00:10.880 of the fundamental structure of reality, where quantum laws govern matter, energy, 3 00:00:11.199 --> 00:00:16.239 and information. Here, uncertainty is a feature, not a flaw, 4 00:00:16.719 --> 00:00:19.239 and understanding begins at the smallest scales. 5 00:00:27.600 --> 00:00:31.519 Imagine for a second the absolute ultimate divide in our 6 00:00:31.600 --> 00:00:32.759 understanding of reality. 7 00:00:32.840 --> 00:00:34.520 Oh yeah, the classic split. 8 00:00:34.840 --> 00:00:37.799 Right on one side, you have the classical universe. This 9 00:00:37.880 --> 00:00:41.840 is the world of the intuitive, the visible, predictable stuff. 10 00:00:41.560 --> 00:00:43.079 The everyday world exactly. 11 00:00:43.159 --> 00:00:45.560 It's where gravity pulls an apple from a tree, or 12 00:00:45.600 --> 00:00:50.600 where a baseball follows this perfect predictable mathematical arc. And 13 00:00:51.000 --> 00:00:55.039 massive planets they just orbit stars with absolute clockwork precision. 14 00:00:56.280 --> 00:00:58.479 The rules here, they just make sense to us. 15 00:00:58.640 --> 00:01:02.359 Well, yeah, because the the physics of everyday reality are 16 00:01:02.399 --> 00:01:04.799 built on this foundation of certainty. I mean, we can 17 00:01:04.840 --> 00:01:07.719 measure a macroscopic object, figure out its speed, and predict 18 00:01:07.719 --> 00:01:09.799 exactly where it will be an hour or a day 19 00:01:09.879 --> 00:01:11.519 or a century from now. 20 00:01:11.640 --> 00:01:14.599 Right, It's totally deterministic. But then, and this is where 21 00:01:14.599 --> 00:01:18.040 it always gets wild. You cross this threshold. You zoom 22 00:01:18.040 --> 00:01:20.959 in close enough down to the level of individual electrons 23 00:01:20.959 --> 00:01:23.439 and photons, and you enter the quantum realm, and all. 24 00:01:23.359 --> 00:01:25.799 Those comforting rules just completely evaporate. 25 00:01:26.159 --> 00:01:30.280 They really do. Suddenly, particles seem to just like teleport 26 00:01:30.920 --> 00:01:34.719 or they exist in this fuzzy cloud of probability, potentially 27 00:01:34.760 --> 00:01:37.760 being in multiple places at once until someone actually looks. 28 00:01:37.519 --> 00:01:40.040 At them, which is deeply unintuitive. 29 00:01:39.599 --> 00:01:43.359 Highly unintuitive, And for nearly a century, the consensus has 30 00:01:43.400 --> 00:01:47.599 been that these two realms are just fundamentally incompatible. Yeah, 31 00:01:47.640 --> 00:01:51.200 we've been told essentially that the universe speaks two completely 32 00:01:51.239 --> 00:01:52.560 different languages. 33 00:01:52.200 --> 00:01:55.159 Right, classical mechanics for the big stuff and quantum mechanics 34 00:01:55.159 --> 00:01:55.920 for the tiny stuff. 35 00:01:55.959 --> 00:02:00.239 Yeah, and having two totally disparate rule books for the 36 00:02:00.280 --> 00:02:05.239 exact same universe, depending entirely on how closely you're squinting 37 00:02:05.280 --> 00:02:07.799 at it. That's always been an uncomfortable compromise. 38 00:02:07.840 --> 00:02:10.719 Hast uncomfortable as an understatement, I mean that philosophical and 39 00:02:10.759 --> 00:02:13.400 mathematical factor has pretty much defined modern science. 40 00:02:13.479 --> 00:02:17.599 Well, that compromise might actually be over because in April 41 00:02:17.599 --> 00:02:21.360 of twenty twenty six, researchers at MIT published this paper, 42 00:02:21.439 --> 00:02:23.719 which is in the Proceedings of the Royal Society A, 43 00:02:24.199 --> 00:02:26.240 and it fundamentally shatters this separation. 44 00:02:26.439 --> 00:02:28.280 It really does. It's a massive paradigm shift. 45 00:02:28.520 --> 00:02:32.439 It is they mathematically proved that the most iconic, the 46 00:02:32.479 --> 00:02:37.159 most bizarre quantum behaviors can actually be perfectly reproduced using 47 00:02:37.240 --> 00:02:39.080 purely classical physics concepts. 48 00:02:39.120 --> 00:02:42.240 And we should clarify there are no approximations here, no 49 00:02:43.680 --> 00:02:46.840 semi classical half measures were only kind of work right, No. 50 00:02:46.879 --> 00:02:50.439 Close enough. It is an exact mathematical bridge between the 51 00:02:50.479 --> 00:02:54.039 macro and the micro, which is just its mind blowing. 52 00:02:54.159 --> 00:02:57.599 The implications really cannot be overstated by showing that a 53 00:02:57.639 --> 00:03:01.919 separate quantum rule book isn't strictly necessary to get quantum results. 54 00:03:02.120 --> 00:03:04.919 I mean, Jean Jacques Lautine and Winfrey low Miller from 55 00:03:05.039 --> 00:03:08.439 MIT's Nonlinear Systems Lab. They've really changed the game here. 56 00:03:08.479 --> 00:03:10.719 So today we are going to unpack the mechanics of 57 00:03:10.719 --> 00:03:13.360 how these scientists actually prove this. We're going to look 58 00:03:13.360 --> 00:03:17.039 at the math, the physical models, and this wild reality 59 00:03:17.080 --> 00:03:19.840 that the classical universe and the quantum universe might just 60 00:03:19.879 --> 00:03:22.039 be the exact same thing, view through different lenses. 61 00:03:22.080 --> 00:03:23.960 It's a lot to wrap your head around, it is. 62 00:03:24.360 --> 00:03:26.879 So to really understand this breakthrough, we need to ground 63 00:03:26.919 --> 00:03:29.639 ourselves in the original rule book. First, Let's look at 64 00:03:29.639 --> 00:03:34.520 the classical world, specifically something called the principle of least action. 65 00:03:34.960 --> 00:03:37.800 Right, So, the principle of least action is essentially the 66 00:03:37.840 --> 00:03:41.599 beating heart of classical mechanics, and it's intimately tied to 67 00:03:41.639 --> 00:03:45.039 this mathematical framework known as the Hamilton Jacoby equation. 68 00:03:45.240 --> 00:03:49.680 Okay, Hamilton Jacoby, what does that mean in plain English? 69 00:03:50.280 --> 00:03:53.360 In simple terms, this principle basically states that when a 70 00:03:53.360 --> 00:03:57.520 physical system evolves, like say, a rock tumbling down a mountain, 71 00:03:58.039 --> 00:04:01.000 it will always always take the path that minimizes a 72 00:04:01.000 --> 00:04:04.159 specific quantity, and that quantity is called action. 73 00:04:04.560 --> 00:04:07.360 An action just to clarify for everyone, is the mathematical 74 00:04:07.400 --> 00:04:11.000 difference between kinetic energy, so the energy of the rock's 75 00:04:11.159 --> 00:04:14.840 actual motion, and potential energy, which is its stored energy 76 00:04:14.879 --> 00:04:17.120 based on where it is tracked over time. 77 00:04:17.279 --> 00:04:22.000 Exactly nature is. Well, it's incredibly a canonmical Macroscopic objects 78 00:04:22.000 --> 00:04:25.680 inherently seek out the absolute most mathematically efficient route to 79 00:04:25.720 --> 00:04:27.839 get from point A to point B, just based on 80 00:04:27.879 --> 00:04:29.199 the forces acting on them. 81 00:04:29.360 --> 00:04:31.240 A good way I like to visualize this and tell 82 00:04:31.279 --> 00:04:33.879 me if this tracks is to think of the classical 83 00:04:33.959 --> 00:04:39.519 universe as this perfectly efficient delivery driver using the ultimate 84 00:04:39.560 --> 00:04:40.439 GPS system. 85 00:04:40.519 --> 00:04:41.079 Oh, I like that. 86 00:04:41.199 --> 00:04:43.439 Yeah, right, So if you throw a ball across a field, 87 00:04:43.879 --> 00:04:48.639 the universe instantly calculates the absolute laziest, most efficient trajectory 88 00:04:48.639 --> 00:04:49.480 for that ball to take. 89 00:04:49.600 --> 00:04:53.279 It factors in gravity, wind, resistance, starting velocity, all of 90 00:04:53.319 --> 00:04:54.399 it exactly. 91 00:04:54.000 --> 00:04:56.959 And it plots one single hyper efficient path. The ball 92 00:04:57.000 --> 00:04:59.600 doesn't wander around the field exploring. It just follows that 93 00:04:59.639 --> 00:05:02.279 one eye optimal route. It's totally deterministic. 94 00:05:02.519 --> 00:05:06.120 One starting point, one optimal path, one destination. That is 95 00:05:06.199 --> 00:05:10.639 classical physics in a nutshell, right. But the contrast comes 96 00:05:10.639 --> 00:05:13.319 in when we try to apply that exact same logic 97 00:05:13.399 --> 00:05:16.959 to the quantum realm, because there we run headfirst into 98 00:05:16.959 --> 00:05:18.480 the Schrodinger equation. 99 00:05:18.240 --> 00:05:19.920 The famous Shrodinger equation, Right. 100 00:05:20.000 --> 00:05:23.720 It's the central pillar of non relativistic quantum mechanics. It 101 00:05:23.759 --> 00:05:27.720 governs everything from electron orbitals to the behavior of light. 102 00:05:28.319 --> 00:05:31.720 And the Schrodinger equation explicitly rejects the concept of a 103 00:05:31.759 --> 00:05:32.959 single defined path. 104 00:05:33.040 --> 00:05:35.519 So the single delivery driver's just gone. 105 00:05:35.240 --> 00:05:39.480 Replaced by an infinite swarm. According to the foundational models 106 00:05:39.480 --> 00:05:44.079 of quantum mechanics, like Richard Feynman's path integral formulation, a 107 00:05:44.160 --> 00:05:46.800 particle doesn't pick one efficient route. 108 00:05:46.959 --> 00:05:50.120 It explores like an infinite number of paths simultaneously. 109 00:05:50.240 --> 00:05:53.000 Right, Yes, it takes a direct route, sure, but it 110 00:05:53.079 --> 00:05:56.079 also mathematically takes a route that loops around the moon 111 00:05:56.600 --> 00:06:01.160 and a route that zigzags through the floorboards. Every conceivable 112 00:06:01.240 --> 00:06:05.399 path through the universe is calculated and some together, which. 113 00:06:05.199 --> 00:06:07.399 Sounds completely absurd when you say it out loud. 114 00:06:07.519 --> 00:06:11.439 It does. But mathematically, all those infinite paths interfere with 115 00:06:11.480 --> 00:06:15.759 each other. They create constructive and destructive interference, and that 116 00:06:15.839 --> 00:06:17.079 results in a wave function. 117 00:06:17.680 --> 00:06:20.480 So instead of knowing exactly where a particle is, the 118 00:06:20.519 --> 00:06:23.439 Schrodinger equation just gives us a mathematical description of the 119 00:06:23.439 --> 00:06:25.600 probability of finding it somewhere exactly. 120 00:06:25.720 --> 00:06:28.399 We're just left with these clouds of possibility. 121 00:06:28.639 --> 00:06:30.879 Okay, so this is where I'm struggling. We have a 122 00:06:30.920 --> 00:06:34.600 single hyper efficient delivery driver taking the most logical route 123 00:06:34.600 --> 00:06:37.879 on one hand, and on the other, an infinite swarm 124 00:06:37.920 --> 00:06:41.680 of drivers taking literally every conceivable path in the entire 125 00:06:41.759 --> 00:06:43.000 universe at the same time. 126 00:06:43.199 --> 00:06:44.399 The ultimate contradiction. 127 00:06:44.639 --> 00:06:47.879 Right, So, how could anyone possibly claim that these two 128 00:06:47.879 --> 00:06:51.600 mathematical models are identical? It sounds impossible on its face. 129 00:06:51.839 --> 00:06:54.160 Well, that was the genius of Slotein and low Miller. 130 00:06:54.959 --> 00:06:58.319 They looked at the classical Hamilton Jacobe equation the math 131 00:06:58.439 --> 00:07:02.279 for our single efficient driver and realized it actually had 132 00:07:02.319 --> 00:07:07.000 the inherent capability to handle messy quantum scenarios all along. 133 00:07:07.199 --> 00:07:09.680 Wait, really, the classical math already had it. 134 00:07:09.680 --> 00:07:13.040 It did it simply lapped two very specific ingredients to 135 00:07:13.079 --> 00:07:15.720 bridge that gap, and the first ingredient they introduced is 136 00:07:15.759 --> 00:07:17.360 something called multipaths. 137 00:07:17.519 --> 00:07:20.680 Multipaths Okay, let me guess instead of one single lease 138 00:07:20.720 --> 00:07:23.839 action path, we just upgrade the system to an infinite 139 00:07:23.920 --> 00:07:25.120 number of classical paths. 140 00:07:25.399 --> 00:07:28.639 H No, actually, because that would just be reinventing Feinman's 141 00:07:28.680 --> 00:07:32.120 complex path integrals all over again. We want to avoid infinity. 142 00:07:32.240 --> 00:07:34.000 Oh right, fair point. So what do they do? 143 00:07:34.319 --> 00:07:37.480 The MIT team expanded the classical framework to consider a 144 00:07:37.519 --> 00:07:42.120 select few highly efficient leased action paths simultaneously, so the 145 00:07:42.160 --> 00:07:45.160 math is allowed to evaluate multiple optimal routes at once, 146 00:07:45.519 --> 00:07:48.079 rather than forcing just one deterministic outcome. 147 00:07:48.360 --> 00:07:50.879 Okay, so, going back to our analogy, we have a 148 00:07:50.920 --> 00:07:55.240 handful of really good delivery drivers taking the top three 149 00:07:55.360 --> 00:07:58.759 or four best routes rather than an infinite swarm covering 150 00:07:58.800 --> 00:07:59.399 the whole earth. 151 00:07:59.439 --> 00:08:02.279 Exactly. It's a multi valued, classical action. 152 00:08:02.439 --> 00:08:07.040 That makes mathematical sense. It's cleaner. But and here's where 153 00:08:07.040 --> 00:08:11.240 I get stuck. A few efficient routes still don't explain 154 00:08:11.639 --> 00:08:15.319 the fuzzy cloudlike nature of a quantum particle, right. 155 00:08:15.199 --> 00:08:17.279 Because a particle isn't just a fleet of trucks. 156 00:08:17.360 --> 00:08:18.720 Yeah, So how do we get the cloud? 157 00:08:19.000 --> 00:08:22.639 This is where the second absolutely crucial ingreding comes into play. 158 00:08:23.000 --> 00:08:27.439 Density density like mass, not quite. The researchers use the 159 00:08:27.439 --> 00:08:31.519 Greek letter row to represent a classical concept borrowed directly 160 00:08:31.519 --> 00:08:34.159 from hydrodynamics. You know, the study of fluid motion. 161 00:08:34.240 --> 00:08:35.559 Okay, fluid dynamics, right, And. 162 00:08:35.600 --> 00:08:39.240 Fluid dynamics density describes how a substance flows, how it clusters, 163 00:08:39.279 --> 00:08:42.519 and how it interacts with its environment. They essentially grafted 164 00:08:42.559 --> 00:08:46.320 this classical notion of fluid density onto those multipaths we 165 00:08:46.399 --> 00:08:46.960 just talked about. 166 00:08:47.000 --> 00:08:49.639 Wait, hold on, I need to push back here. Particles 167 00:08:49.919 --> 00:08:54.080 like electrons, they are discrete, indivisible points of matter. They 168 00:08:54.080 --> 00:08:57.320 aren't liquids. So if we are tracking a single electron, 169 00:08:58.039 --> 00:09:01.480 treating it like a continuous flowing fluid seems like a 170 00:09:01.559 --> 00:09:06.240 huge fundamental contradiction. How does a single microscopic billiard ball 171 00:09:06.639 --> 00:09:08.120 suddenly behave like a river. 172 00:09:08.279 --> 00:09:11.399 It's a great question. The density here doesn't mean the 173 00:09:11.440 --> 00:09:14.919 physical mass of the electron is smearing out like spilled 174 00:09:15.000 --> 00:09:16.000 milk across the room. 175 00:09:16.080 --> 00:09:17.519 Okay, good, that would be messy. 176 00:09:17.799 --> 00:09:20.960 Very no. It represents a fluid of probability, and it's 177 00:09:20.960 --> 00:09:24.120 tied strictly to those multiple classical paths. Think about like 178 00:09:24.120 --> 00:09:24.919 traffic density. 179 00:09:25.000 --> 00:09:25.799 Traffic density. 180 00:09:25.919 --> 00:09:28.639 Yeah, even if you are only tracking one specific car, 181 00:09:28.960 --> 00:09:31.480 the mathematical probability of where that car might end up 182 00:09:31.480 --> 00:09:33.919 on its journey behaves a lot like a fluid. It 183 00:09:34.000 --> 00:09:37.200 clusters around bottlenecks, it spreads out over open highways. 184 00:09:37.279 --> 00:09:37.840 Oh I see. 185 00:09:38.000 --> 00:09:41.720 So by combining a multi valued classical action those multiple 186 00:09:41.759 --> 00:09:45.840 efficient paths with an analytically computed density flowing along those 187 00:09:45.879 --> 00:09:49.120 exact paths, the system starts to behave completely differently than 188 00:09:49.159 --> 00:09:50.840 just a single deterministic particle. 189 00:09:51.000 --> 00:09:54.399 The friction and the crowding of the paths dictate the behavior. 190 00:09:54.720 --> 00:09:59.840 So by calculating how this probability fluid flows and bunch 191 00:09:59.879 --> 00:10:03.519 of up along a few highly efficient routes, they built 192 00:10:03.519 --> 00:10:06.200 a mathematical replica of a quantum system. 193 00:10:06.360 --> 00:10:08.799 Actually, they went much further than just a replica. What 194 00:10:08.799 --> 00:10:11.799 do you mean when they integrated multiple classical paths with 195 00:10:11.879 --> 00:10:15.840 that fluid density, The resulting math produced the exact quantum 196 00:10:15.840 --> 00:10:19.919 wave function predicted by the Scherdinger equation. Wait, exactly exactly. 197 00:10:20.200 --> 00:10:24.159 The equations become literally identical once that classical density is 198 00:10:24.200 --> 00:10:27.399 properly accounted for in the math. Slow Teine even pointed 199 00:10:27.399 --> 00:10:29.799 out that they didn't have to invent any new quantum 200 00:10:29.840 --> 00:10:34.159 physics at all. They literally just applied classical fluidynamics to 201 00:10:34.200 --> 00:10:35.639 classical action principles. 202 00:10:35.720 --> 00:10:39.159 That is a massive claim because normally, you know, attempts 203 00:10:39.200 --> 00:10:41.519 to bridge the macro and the micro rely on those 204 00:10:41.559 --> 00:10:43.840 semi classical theories we mentioned, right. 205 00:10:43.679 --> 00:10:45.960 The ones that kind of work for large molecules but 206 00:10:46.039 --> 00:10:48.519 completely fall apart the second you try to model a 207 00:10:48.559 --> 00:10:50.759 single solitary electron exactly. 208 00:10:51.399 --> 00:10:54.960 But claiming an exact rigorous bridge means this theory has 209 00:10:55.000 --> 00:10:58.799 to survive like the ultimate boss battles of quantum mechanics. 210 00:10:59.120 --> 00:11:02.000 It has to explain the stuff that is historically defied 211 00:11:02.080 --> 00:11:05.960 classical logic entirely, and it does well. Let's test that. 212 00:11:06.320 --> 00:11:09.440 Let's start with the most famous one, the double slit experiment. 213 00:11:09.559 --> 00:11:12.679 Oh, the quintessential demonstration of quantum weirdness. 214 00:11:12.759 --> 00:11:14.919 Right, so we all know the basic setup. You have 215 00:11:14.919 --> 00:11:17.240 a barrier with two vertical slits in it and a 216 00:11:17.240 --> 00:11:18.399 blank screen behind it. 217 00:11:18.519 --> 00:11:19.200 Simple enough. 218 00:11:19.279 --> 00:11:23.279 But if you fire quantum particles like individual electrons through 219 00:11:23.320 --> 00:11:26.000 the slits one at a time, they don't just form 220 00:11:26.039 --> 00:11:28.519 two simple bands on the back wall like you'd expect. 221 00:11:29.320 --> 00:11:33.039 Over time, these single electrons build up an interference pattern, 222 00:11:33.440 --> 00:11:37.320 a really complex series of alternating light in dark stripes. 223 00:11:36.919 --> 00:11:40.080 Which looks exactly like the ripples created when two distinct 224 00:11:40.120 --> 00:11:42.000 waves crash into each other in a pond. 225 00:11:42.159 --> 00:11:45.559 Yes, but because you are firing the electrons strictly one 226 00:11:45.600 --> 00:11:48.519 at a time, the implication is that a single electron 227 00:11:48.600 --> 00:11:52.440 is somehow traveling through both slits, simultaneously interfering with the 228 00:11:52.480 --> 00:11:56.320 self and deciding where to land based purely on probability. 229 00:11:55.960 --> 00:11:59.720 Which is why the traditional quantum explanation requires calculating the 230 00:11:59.720 --> 00:12:03.919 complex phases for infinite and so many possible meandering routes 231 00:12:04.279 --> 00:12:07.960 the electron could take through space just to figure out 232 00:12:08.000 --> 00:12:11.799 where that constructive and destructive interference will happen on the screen. 233 00:12:12.039 --> 00:12:16.480 It is incredibly heavy, incredibly unintuitive math extremely so if 234 00:12:16.519 --> 00:12:19.519 the mit team is throwing out the infinite paths, how 235 00:12:19.519 --> 00:12:22.519 on earth do they get the alternating stripes? Because if 236 00:12:22.559 --> 00:12:27.240 you only have two classical multipaths, like one highly efficient 237 00:12:27.320 --> 00:12:29.759 route going through the left slit and one going through 238 00:12:29.759 --> 00:12:32.679 the right slit, that shouldn't create a complex ripple. 239 00:12:32.759 --> 00:12:35.480 No, two simple paths should just give you two solid 240 00:12:35.480 --> 00:12:37.200 stripes on the back wall exactly. 241 00:12:37.519 --> 00:12:39.159 So where does the wave pattern come from? 242 00:12:39.200 --> 00:12:42.559 Classically, it emerges entirely from the physical constraints of the 243 00:12:42.559 --> 00:12:45.919 slits themselves, acting upon that second ingredient we discussed the 244 00:12:45.919 --> 00:12:46.679 fluid density. 245 00:12:46.759 --> 00:12:47.799 The physical constraints. 246 00:12:48.000 --> 00:12:51.879 Yeah, the researchers mathematically modeled the physical barrier with the 247 00:12:51.919 --> 00:12:55.840 slits as a space with highly constrained choke points. So 248 00:12:55.879 --> 00:12:59.480 as the probability fluid travels along those two optimal paths, 249 00:13:00.039 --> 00:13:03.480 it is quite literally forced to squeeze through the narrow openings. 250 00:13:03.639 --> 00:13:06.120 Okay, So the physical boundaries of the slits are acting 251 00:13:06.159 --> 00:13:09.320 as literal constraints on the probability fluid exactly. 252 00:13:09.799 --> 00:13:12.679 The boundaries force the paths to bend, and they force 253 00:13:12.720 --> 00:13:16.559 the fluid density to ripple outward. The mathematical term involves 254 00:13:16.559 --> 00:13:21.440 constraint forces, specifically non Lipschitz forces altering the momentum of 255 00:13:21.480 --> 00:13:22.440 the classical density. 256 00:13:22.519 --> 00:13:22.919 Oh wow. 257 00:13:23.080 --> 00:13:25.559 Yeah, So when the fluid density from the left path 258 00:13:25.639 --> 00:13:28.080 interacts with the fluid density from the right path after 259 00:13:28.080 --> 00:13:31.320 squeezing through those constraints, they naturally create interference. 260 00:13:31.519 --> 00:13:32.279 That is wild. 261 00:13:32.480 --> 00:13:36.000 The alternating stripes of the famous wave function emerge entirely 262 00:13:36.080 --> 00:13:39.639 naturally from the friction and pressure of classical fluid dynamics 263 00:13:39.720 --> 00:13:41.320 interacting with a physical boundary. 264 00:13:41.519 --> 00:13:44.720 So no particle being in two places at once, no 265 00:13:44.919 --> 00:13:48.720 infinite paths taking detours through the Andromeda galaxy. Just a 266 00:13:48.720 --> 00:13:52.399 probability fluid naturally rippling as it squeezes through two tight 267 00:13:52.440 --> 00:13:53.399 classical paths. 268 00:13:53.639 --> 00:13:56.039 That's it. No quantum magic required. 269 00:13:56.600 --> 00:13:59.679 That actually makes a terrifying amount of sense. It really does. 270 00:14:00.240 --> 00:14:04.679 But let's push this even further. What about quantum tunneling? 271 00:14:05.039 --> 00:14:07.480 Ah another great boss battle right. 272 00:14:07.879 --> 00:14:11.000 This is the phenomenon where a particle simply passes straight 273 00:14:11.080 --> 00:14:15.039 through a solid energy barrier, like walking through a wall. 274 00:14:14.840 --> 00:14:18.559 Which in a purely classical framework is totally forbidden. I mean, 275 00:14:18.600 --> 00:14:20.279 if you roll a ball up a hill, but it 276 00:14:20.360 --> 00:14:22.919 lacks the kinetic energy to reach the crest, the ball 277 00:14:22.960 --> 00:14:23.960 just rolls back down. 278 00:14:24.039 --> 00:14:26.759 It can't magically cross over to the other side exactly. 279 00:14:27.000 --> 00:14:30.039 Yet in the quantum world, electrons routinely appear on the 280 00:14:30.039 --> 00:14:33.600 other side of barriers they mathematically shouldn't have the energy 281 00:14:33.639 --> 00:14:34.480 to cross, and. 282 00:14:34.480 --> 00:14:37.799 The traditional quantum explanation is always that the particle is 283 00:14:37.840 --> 00:14:40.799 a wave of probability, and a tiny piece of that 284 00:14:40.840 --> 00:14:43.919 wave is basically leaks through the barrier. It's always described 285 00:14:43.960 --> 00:14:47.000 like a ghost walking through a brick wall. So how 286 00:14:47.039 --> 00:14:52.840 does a classical lazy delivery driver model explain walking through walls. 287 00:14:52.720 --> 00:14:56.519 By analyzing how fluid pressure and density naturally behave when 288 00:14:56.559 --> 00:15:00.440 confronted with an obstacle. The MIT team just applied their framework, 289 00:15:00.519 --> 00:15:03.759 relying again on those same multipaths and density evolution. 290 00:15:04.519 --> 00:15:07.240 Okay, so how does a fluid act differently than a bowl? 291 00:15:07.639 --> 00:15:11.759 Well, while a single solid particle obviously lacks the energy 292 00:15:11.799 --> 00:15:15.279 to surmount the barrier, a fluid distributed over a multiple 293 00:15:15.279 --> 00:15:20.320 paths behaves very differently. The formulation inherently allows for what 294 00:15:20.360 --> 00:15:23.679 they term transmission through forbidden. 295 00:15:23.240 --> 00:15:25.840 Regions, transmission meaning it seeps through. 296 00:15:25.799 --> 00:15:30.039 Precisely because the density represents a distribution of probability, the 297 00:15:30.039 --> 00:15:33.919 mathematical pressure of that fluid along the classical multipaths just 298 00:15:34.000 --> 00:15:37.399 finds efficient routes that seep through the barrier's constraints. 299 00:15:37.519 --> 00:15:37.879 Wow. 300 00:15:38.000 --> 00:15:41.320 And the most amazing part the classical calculation, they did 301 00:15:41.399 --> 00:15:45.600 perfectly match the exact Shreddinger predictions for the tunneling probability. 302 00:15:45.679 --> 00:15:49.879 So the fluid density is just finding mathematically valid, highly 303 00:15:49.919 --> 00:15:54.200 efficient microscopic routes through the barrier that a single classical 304 00:15:54.240 --> 00:15:58.159 trajectory would just completely ignore. That completely reframes how we 305 00:15:58.279 --> 00:16:02.240 visualize the micro world. And it's my understanding they didn't 306 00:16:02.320 --> 00:16:04.840 just stop at the double slater tunnel link, right. They 307 00:16:04.840 --> 00:16:10.039 applied this classical framework to a massive roster of textbook 308 00:16:10.120 --> 00:16:10.879 quantum mysteries. 309 00:16:10.960 --> 00:16:15.799 Oh, they systematically proved the framework against numerous foundational problems. 310 00:16:15.799 --> 00:16:19.720 I mean, they modeled the harmonic oscillator, which is essentially 311 00:16:19.759 --> 00:16:23.720 a particle trapped in a quadratic potential, and they tackled 312 00:16:23.720 --> 00:16:25.200 a particle in a box. 313 00:16:25.399 --> 00:16:26.679 What did they find with the box? 314 00:16:27.200 --> 00:16:30.679 In that scenario? They demonstrated how a single particle bouncing 315 00:16:30.720 --> 00:16:33.399 back and forth off the walls naturally generates the very 316 00:16:33.440 --> 00:16:37.039 multipaths we've been discussing, which builds up a complex internal 317 00:16:37.080 --> 00:16:38.679 density all on its own. 318 00:16:38.960 --> 00:16:41.639 I want to dive deep into one of their specific successes, 319 00:16:41.960 --> 00:16:45.039 because just listing phenomena kind of doesn't do the underlying 320 00:16:45.080 --> 00:16:48.399 mechanics justice. Let's talk about the hydrogen atom. 321 00:16:48.240 --> 00:16:50.399 The kulum potential problem. 322 00:16:50.080 --> 00:16:53.159 Right, because applying classical physics to the orbit of an 323 00:16:53.159 --> 00:16:57.000 electron around a nucleus usually ends in total disaster, which 324 00:16:57.039 --> 00:16:59.000 is basically why quantum mechanics had to be invented in 325 00:16:59.039 --> 00:16:59.600 the first place. 326 00:16:59.679 --> 00:17:04.039 Right. Yes, classical physics says an orbiting electron should instantly 327 00:17:04.160 --> 00:17:06.759 radiate away all of its energy and just crash into 328 00:17:06.759 --> 00:17:08.400 the nucleus. It shouldn't be stable. 329 00:17:08.960 --> 00:17:13.640 So how did multipaths and fluid densities solve the hydrogen atom. 330 00:17:13.880 --> 00:17:18.759 By mathematically linking classical kepler orbits directly to quantum wave functions. 331 00:17:18.920 --> 00:17:21.359 Kepler orbits like planetary orbits. 332 00:17:21.079 --> 00:17:24.480 Exactly the same. Kepler orbits are the mathematical principles that 333 00:17:24.519 --> 00:17:29.160 describe how massive planets orbit the Sun. They are elliptical, predictable, 334 00:17:29.480 --> 00:17:33.960 deterministic paths dictated by gravity. Okay, the MIT team took 335 00:17:34.000 --> 00:17:36.759 the electrical attraction between the electron and the nucleus the 336 00:17:36.839 --> 00:17:40.599 coulum potential, and applied their classical fluid framework. 337 00:17:41.160 --> 00:17:43.519 But They didn't just treat the electron like a tiny planet, 338 00:17:43.519 --> 00:17:43.839 did they. 339 00:17:44.079 --> 00:17:44.279 No? 340 00:17:44.279 --> 00:17:46.880 No, they treated it as a fluid density distributed over 341 00:17:47.000 --> 00:17:51.799 multiple classical Kepler like orbits simultaneously. Oh yeah, and by 342 00:17:51.839 --> 00:17:55.200 mapping how the probability density flows along these elliptical paths, 343 00:17:55.440 --> 00:17:59.319 the classical math natally produced the exact complex, three dimensional 344 00:17:59.359 --> 00:18:00.720 shapes of elect orbitals. 345 00:18:00.759 --> 00:18:03.039 Wait, you mean the SP and D shells, the things 346 00:18:03.079 --> 00:18:05.440 that basically define all of chemistry, The. 347 00:18:05.480 --> 00:18:08.599 Very same the stationary states of an atom emerge simply 348 00:18:08.640 --> 00:18:12.440 because the fluid density falls into a stable repeating pattern 349 00:18:12.759 --> 00:18:14.799 along those classical orbital paths. 350 00:18:15.200 --> 00:18:18.880 So the shapes of chemistry are literally just stable fluid 351 00:18:18.880 --> 00:18:22.319 patterns built on top of planetary orbits. That is beautiful. 352 00:18:23.400 --> 00:18:26.720 But if that's true, how does this framework handle what 353 00:18:26.839 --> 00:18:29.279 I think is the most mystical part of quantum physics 354 00:18:29.400 --> 00:18:31.640 rock wave function collapse? 355 00:18:32.000 --> 00:18:34.279 Ah? Yes, the measurement problem. 356 00:18:34.000 --> 00:18:38.000 Right, the idea that a fuzzy cloud of probability instantly 357 00:18:38.039 --> 00:18:40.759 snaps into a single, definite point of reality the very 358 00:18:40.799 --> 00:18:43.400 moment a scientists looks at it or measures it. Does 359 00:18:43.440 --> 00:18:47.319 classical fluid density explain why observation actually changes reality. 360 00:18:47.680 --> 00:18:51.079 It demystifies it completely because in the traditional quantum view, 361 00:18:51.319 --> 00:18:55.000 measurement triggers this magical, instantaneous collapse of the wave function 362 00:18:55.079 --> 00:18:57.119 that completely defies classical explanation. 363 00:18:57.319 --> 00:18:58.799 Right, it's always felt a bit like magic. 364 00:18:58.960 --> 00:19:01.720 But in the MIT work, measurement is simply treated as 365 00:19:01.759 --> 00:19:03.799 a classical update of information. 366 00:19:03.720 --> 00:19:06.319 Like updating a statistical model when new data comes in. 367 00:19:06.680 --> 00:19:11.000 Precisely in that vein, if you have a fluid density 368 00:19:11.000 --> 00:19:14.319 of probability spread across several paths, and you place a 369 00:19:14.359 --> 00:19:17.559 detector along one of those paths, you are imposing a 370 00:19:17.640 --> 00:19:20.759 new physical constraint on the entire system because. 371 00:19:20.519 --> 00:19:23.480 The detector is a physical object interacting with the fluid. 372 00:19:23.640 --> 00:19:27.359 Exactly the moment the detector interacts with the fluid, the 373 00:19:27.400 --> 00:19:32.839 density distribution mathematically must update to reflect the new boundary conditions. Oh, 374 00:19:32.920 --> 00:19:36.759 the fluid doesn't mysteriously collapse due to human consciousness or 375 00:19:36.799 --> 00:19:41.599 anything spooky. The density simply redistributes itself instantly according to 376 00:19:41.640 --> 00:19:45.440 classical statistical mechanics, purely because the physical parameters of the 377 00:19:45.519 --> 00:19:46.480 environment changed. 378 00:19:46.599 --> 00:19:50.400 Wow. That removes the mysticism entirely, it really does. It 379 00:19:50.480 --> 00:19:55.559 just translates the spookiest quantum behaviors into rigorous classical statistics 380 00:19:55.559 --> 00:19:58.000 and fluid dynamics. I mean, didn't they even manage to 381 00:19:58.039 --> 00:19:59.480 map quantum entanglement with this? 382 00:19:59.640 --> 00:20:03.279 They did. They mapped entanglement, which Einstein called spooky action 383 00:20:03.359 --> 00:20:07.400 at a distance to complex classical mathematical structures called tensor 384 00:20:07.480 --> 00:20:08.559 products of spiners. 385 00:20:08.799 --> 00:20:11.200 It is a total rewrite of how we model the universe. 386 00:20:11.200 --> 00:20:11.799 It really is. 387 00:20:11.920 --> 00:20:13.640 But you know, if I'm listening to this, I'm probably wondering, 388 00:20:14.079 --> 00:20:17.079 does bridging this math actually change anything in the real 389 00:20:17.079 --> 00:20:20.519 world or is it just like the ultimate flex for 390 00:20:20.640 --> 00:20:24.720 theoretical physicists. Does this have practical applications in a laboratory today? 391 00:20:24.759 --> 00:20:28.079 Oh, the practical applications are immense, particularly when you look 392 00:20:28.119 --> 00:20:31.200 at the limits of modern computation. How so well, think 393 00:20:31.319 --> 00:20:34.960 back to Feinneman's pass integrals we discussed earlier the infinite 394 00:20:35.000 --> 00:20:38.799 swarm of paths. If you are a material scientist trying 395 00:20:38.839 --> 00:20:42.440 to simulate a complex molecule to invent, say a more 396 00:20:42.480 --> 00:20:47.319 efficient solar panel or a room temperature superconductor, the quantum 397 00:20:47.400 --> 00:20:51.599 math using Feinnemann's method becomes impossibly complex. 398 00:20:51.240 --> 00:20:54.240 Because asking a computer to calculate infinity or even just 399 00:20:54.279 --> 00:20:57.799 a close approximation of infinity across hundreds of interacting particles 400 00:20:58.119 --> 00:21:01.240 is going to choke even the most advanced supercomputers on Earth. 401 00:21:01.599 --> 00:21:05.240