1 00:00:00,080 --> 00:00:02,080 Speaker 1: Okay, stop what you're doing for a moment and just 2 00:00:02,439 --> 00:00:05,639 consider this. Right now, this very second, the universe might be. 3 00:00:05,519 --> 00:00:08,039 Speaker 2: Splitting, and not just splitting once. 4 00:00:07,879 --> 00:00:11,599 Speaker 1: No, splitting into just countless parallel universes. And I don't 5 00:00:11,640 --> 00:00:14,199 mean that in some metaphorical way like a story. 6 00:00:14,240 --> 00:00:18,440 Speaker 2: I mean literally, right physically, real separate universes are branching 7 00:00:18,480 --> 00:00:20,839 off from our own moment by moment. 8 00:00:20,800 --> 00:00:23,440 Speaker 1: And in every single one of those new realities, there's 9 00:00:23,480 --> 00:00:26,559 a new version of you, a distinct you, living a 10 00:00:26,600 --> 00:00:29,280 completely different, non overlapping life. 11 00:00:29,320 --> 00:00:31,600 Speaker 2: It's a concept that sounds so much like science fiction. 12 00:00:31,760 --> 00:00:36,520 It's so big, so profoundly counterintuitive, that you'd be forgiven 13 00:00:36,679 --> 00:00:38,280 for just dismissing it. 14 00:00:38,399 --> 00:00:41,920 Speaker 1: You would. But here's the thing you can't, because this 15 00:00:42,000 --> 00:00:45,479 isn't fantasy. It's a direct consequence of the mathematics of 16 00:00:45,560 --> 00:00:46,600 quantum mechanics, the. 17 00:00:46,640 --> 00:00:49,840 Speaker 2: Very same physics that you know powers your phone, your computer, 18 00:00:50,000 --> 00:00:52,039 the Wi Fi are probably using to listen to this. 19 00:00:52,679 --> 00:00:56,359 The math works, we know it works, and this is where. 20 00:00:56,159 --> 00:00:58,920 Speaker 1: It leads, and this is where it gets really really interesting. 21 00:00:59,119 --> 00:01:02,079 We are doing ad dive today into something called the 22 00:01:02,119 --> 00:01:06,159 many world's interpretation of quantum mechanics, or MWI for sure. 23 00:01:06,560 --> 00:01:09,120 Speaker 2: It's an attempt to solve one of the deepest, most 24 00:01:09,159 --> 00:01:12,640 stubborn problems in all of physics, and it leads directly 25 00:01:12,719 --> 00:01:15,879 to I think the most radical idea. 26 00:01:15,519 --> 00:01:17,239 Speaker 1: Imaginable quantum immortality. 27 00:01:17,359 --> 00:01:20,560 Speaker 2: Quantum immortality the idea that from your own subjective point 28 00:01:20,560 --> 00:01:22,159 of view, you might just live forever. 29 00:01:22,519 --> 00:01:25,799 Speaker 1: So our mission for this deep dive is it was 30 00:01:25,799 --> 00:01:28,359 pretty demanding. We've gone through a mountain of research on 31 00:01:28,400 --> 00:01:32,079 the history, the actual mechanics, and the wild implications of 32 00:01:32,120 --> 00:01:32,959 this theory. 33 00:01:32,680 --> 00:01:35,079 Speaker 2: And we're going to distill it all down. Our goal 34 00:01:35,159 --> 00:01:37,359 is that by the end of this you will understand 35 00:01:37,400 --> 00:01:41,040 the fundamental conflicts in quantum physics better than almost anyone. 36 00:01:41,079 --> 00:01:41,400 You know. 37 00:01:42,000 --> 00:01:45,560 Speaker 1: It's a journey that will, I promise, probably redefine how 38 00:01:45,599 --> 00:01:49,359 you think about reality itself and maybe just maybe your 39 00:01:49,400 --> 00:01:50,079 own existence. 40 00:01:50,159 --> 00:01:52,280 Speaker 2: And to really get the solution, you have to start 41 00:01:52,319 --> 00:01:53,400 with the problem exactly. 42 00:01:53,400 --> 00:01:56,519 Speaker 1: So let's go back. Our story begins over a century ago, 43 00:01:56,599 --> 00:02:00,799 early nineteen hundreds. You've got this incredible ferment of intellectual 44 00:02:00,840 --> 00:02:01,959 activity in physics. 45 00:02:02,000 --> 00:02:07,519 Speaker 2: Oh, the Titans, Einstein, mex Plank, Bore, Shrewdinger, all of them. 46 00:02:07,560 --> 00:02:10,039 Speaker 1: And they were all wrestling with these new phenomena, things 47 00:02:10,080 --> 00:02:13,680 like black body radiation, the photoelectric effect, that the old 48 00:02:13,719 --> 00:02:17,319 physics that classical Newtonian physics just couldn't explain at all. 49 00:02:17,479 --> 00:02:21,599 Speaker 2: Classical physics was beautiful. It was deterministic. It described a 50 00:02:21,639 --> 00:02:25,319 world like a giant clockwork mechanism. If you knew the 51 00:02:25,319 --> 00:02:28,800 position and momentum of every particle at the start, you could, 52 00:02:28,879 --> 00:02:32,759 in theory, calculate the entire future of the universe, perfect prediction. 53 00:02:33,159 --> 00:02:35,680 Speaker 1: But when they started looking at the sub atomic world, 54 00:02:35,879 --> 00:02:40,680 at electrons and photons, they realized those classical rules just 55 00:02:40,840 --> 00:02:41,840 completely fell apart. 56 00:02:41,960 --> 00:02:44,879 Speaker 2: They failed spectacularly. So they had to develop a new theory, 57 00:02:45,000 --> 00:02:49,360 quantum mechanics, which was I mean, unbelievably successful at making predictions. 58 00:02:49,800 --> 00:02:52,960 It explained that energy comes in these little discrete packets or. 59 00:02:53,199 --> 00:02:56,000 Speaker 1: Quanta, but that success came with a really high price. 60 00:02:56,599 --> 00:02:58,639 The map was telling them that things like light and 61 00:02:58,719 --> 00:03:01,960 matter had this bizizar are dual nature. So as it 62 00:03:02,000 --> 00:03:04,280 acts like a particle, you know, tiny little. 63 00:03:04,039 --> 00:03:06,759 Speaker 2: Ball, and sometimes it acts like a diffuse wave spread 64 00:03:06,800 --> 00:03:11,159 out over space. And worse, it introduced probability and pure 65 00:03:11,280 --> 00:03:14,319 chance right into the very fabric of reality. 66 00:03:14,120 --> 00:03:17,800 Speaker 1: And that underlying weirdness was a bitter pill to swallow, 67 00:03:18,319 --> 00:03:20,280 even for the people who invented the theory. 68 00:03:20,840 --> 00:03:23,759 Speaker 2: So to really get why something as wild as a 69 00:03:23,800 --> 00:03:27,800 many World's interpretation was even necessary, we have to hammer 70 00:03:27,840 --> 00:03:30,960 home this fundamental split between the old world and the 71 00:03:31,000 --> 00:03:32,080 new quantum world. 72 00:03:32,479 --> 00:03:35,639 Speaker 1: Right think about the world we live in. The macroscopic 73 00:03:35,719 --> 00:03:39,800 world classical physics. Everything is exact, it's definite. 74 00:03:40,000 --> 00:03:42,680 Speaker 2: We can measure the trajectory of a baseball. We can 75 00:03:42,719 --> 00:03:45,439 calculate the orbit of a planet down to the millimeter. 76 00:03:45,919 --> 00:03:47,840 If you ask me where's the Earth right now, I 77 00:03:47,879 --> 00:03:50,520 can give you a single precise set of coordinates. 78 00:03:50,639 --> 00:03:54,280 Speaker 1: Determinism is king. Everything has a definite value, whether we're 79 00:03:54,280 --> 00:03:55,080 looking at it or not. 80 00:03:55,400 --> 00:03:57,639 Speaker 2: But the second you shrink down to the world of 81 00:03:57,680 --> 00:04:01,639 atoms and electrons, all of that comforting certainty just evaporates. 82 00:04:01,680 --> 00:04:03,080 It completely disintegrates. 83 00:04:03,120 --> 00:04:06,879 Speaker 1: You go from exact numbers to probability probabilities. 84 00:04:06,879 --> 00:04:09,240 Speaker 2: That's it. You can't say anymore the electron is right 85 00:04:09,280 --> 00:04:12,000 here at position X with this exact speed. You can 86 00:04:12,039 --> 00:04:13,840 only talk about the likelihood of finding it in a 87 00:04:13,840 --> 00:04:16,199 certain place or a certain state, and. 88 00:04:16,240 --> 00:04:20,040 Speaker 1: The tool they use to figure out those likelihoods. That's 89 00:04:20,079 --> 00:04:22,240 the core of this whole thing, isn't it the wave function? 90 00:04:22,360 --> 00:04:25,519 Speaker 2: The wave function yes, usually written with the Greek letter sigh, 91 00:04:26,079 --> 00:04:28,839 and it's crucial to understand what it is and what 92 00:04:28,879 --> 00:04:31,720 it isn't. It's a purely mathematical. 93 00:04:31,040 --> 00:04:34,720 Speaker 1: Object, so it's not describing something we can like see 94 00:04:34,800 --> 00:04:36,120 or touch, not directly. 95 00:04:36,360 --> 00:04:40,240 Speaker 2: It's a recipe. It's a tool physicists used to calculate 96 00:04:40,319 --> 00:04:44,480 the probability of all the possible outcomes for a quantum system. 97 00:04:44,759 --> 00:04:47,759 The key is it doesn't describe where a particle is. 98 00:04:47,959 --> 00:04:50,839 It describes all the places it could be, all at once. 99 00:04:51,000 --> 00:04:53,879 Speaker 1: And that's such a critical distinction because it's not just 100 00:04:53,920 --> 00:04:56,439 that we're ignorant, right. It's not like me saying I 101 00:04:56,480 --> 00:04:58,639 don't know where my keys are, but there's a fifty 102 00:04:58,639 --> 00:05:00,759 percent chance through on the kitchen ca exactly. 103 00:05:00,800 --> 00:05:03,360 Speaker 2: That's a perfect analogy with your keys. They are in 104 00:05:03,439 --> 00:05:06,240 one definite place, you just don't know where. The wave 105 00:05:06,279 --> 00:05:08,959 function says that before you look, the particle doesn't have 106 00:05:09,000 --> 00:05:12,720 a single definite location. It physically exists in a kind 107 00:05:12,759 --> 00:05:15,519 of blurry haze of all possibilities at the same time. 108 00:05:15,680 --> 00:05:19,240 That's superposition, a superposition of all possibilities defined by that 109 00:05:19,319 --> 00:05:19,920 wave function. 110 00:05:20,160 --> 00:05:24,360 Speaker 1: Simultaneously, Let's drill down on that idea of superposition, because 111 00:05:24,360 --> 00:05:26,639 that's where all the weirdness really comes from. 112 00:05:26,720 --> 00:05:30,279 Speaker 2: Okay, good idea. Let's take an electron spin You can 113 00:05:30,279 --> 00:05:33,240 think of it like a tiny spinning top. In our world, 114 00:05:33,319 --> 00:05:37,240 a top is either spinning clockwise or counterclockwise, spin up 115 00:05:37,360 --> 00:05:38,000 or spin. 116 00:05:37,920 --> 00:05:39,319 Speaker 1: Down right one or the other. 117 00:05:39,519 --> 00:05:42,600 Speaker 2: But in quantum mechanics, before you measure it, the electron 118 00:05:42,759 --> 00:05:46,600 is in a superposition of both. It is literally spin 119 00:05:46,720 --> 00:05:49,279 up an a spin down at the same time. 120 00:05:49,199 --> 00:05:51,000 Speaker 1: Not flipping back and forth really fast. 121 00:05:51,120 --> 00:05:54,160 Speaker 2: No, it's existing as a combination of both states. The 122 00:05:54,199 --> 00:05:56,600 wave function might tell us there's a fifty percent probability 123 00:05:56,639 --> 00:05:58,759 of finding it spin up and a fifty percent probability 124 00:05:58,759 --> 00:06:01,480 of finding it spin down, But until we look it's 125 00:06:01,519 --> 00:06:03,480 a literal physical blend of the two. 126 00:06:03,839 --> 00:06:06,120 Speaker 1: And this is what just drove the founders of the 127 00:06:06,120 --> 00:06:09,879 theory crazy. How does this system, which is this lurry 128 00:06:09,920 --> 00:06:14,079 haze of probabilities, suddenly decide to be just one thing 129 00:06:14,319 --> 00:06:16,399 in one place the instant we look at it. 130 00:06:16,600 --> 00:06:19,560 Speaker 2: That is the question, That is the measurement problem. If 131 00:06:19,600 --> 00:06:22,800 the wave function is a complete description of reality, and 132 00:06:22,839 --> 00:06:25,319 we know the math works, because again, all our modern 133 00:06:25,360 --> 00:06:28,600 tech is based on it. What is the physical mechanism 134 00:06:28,680 --> 00:06:33,480 that forces that superposition to resolve into the single definite 135 00:06:33,560 --> 00:06:35,680 reality we actually experience. 136 00:06:35,439 --> 00:06:39,079 Speaker 1: And trying to answer that question basically started a civil 137 00:06:39,120 --> 00:06:43,160 war among physicists that lasted for decades. So the first 138 00:06:43,800 --> 00:06:46,360 major attempt to answer the measurement problem and the one 139 00:06:46,360 --> 00:06:48,439 that was dominant for what fifty sixty years? 140 00:06:48,439 --> 00:06:50,199 Speaker 2: Oh, easily, it was the only game in town for 141 00:06:50,240 --> 00:06:53,120 a long time. It was the Copenhagen interpretation. 142 00:06:52,759 --> 00:06:55,879 Speaker 1: Name for where it's main champion Neil's Boorr worked. He 143 00:06:55,920 --> 00:06:58,480 and vererneror Heisenberg developed it in the nineteen twenties. 144 00:06:58,279 --> 00:07:02,240 Speaker 2: Right, and they introduced a new extra rule into quantum mechanics, 145 00:07:02,519 --> 00:07:06,759 a concept they called the collapse. Postulate the collapse the collapse. 146 00:07:06,959 --> 00:07:10,399 It's a simple but very strange assertion. It says that 147 00:07:10,439 --> 00:07:14,480 the wave function, with all its possibilities, evolved perfectly fine 148 00:07:14,480 --> 00:07:17,800 on its own, but it instantly and randomly collapses down 149 00:07:17,839 --> 00:07:20,639 to just one of those possibilities the moment it's measured 150 00:07:20,639 --> 00:07:21,319 by an observer. 151 00:07:21,639 --> 00:07:23,680 Speaker 1: So if we go back to our electron, that's fifty 152 00:07:23,680 --> 00:07:25,879 percent spin up and fifty percent spin down. 153 00:07:25,959 --> 00:07:28,399 Speaker 2: As soon as you bring a detector, a magnet, anything 154 00:07:28,439 --> 00:07:32,480 to measure it, that wave function just snaps instantly. It 155 00:07:32,519 --> 00:07:34,759 becomes either one hundred percent spin up or one hundred 156 00:07:34,759 --> 00:07:36,079 percent spin down. 157 00:07:35,839 --> 00:07:39,600 Speaker 1: And the other possibility, the one that didn't happen gone. 158 00:07:39,800 --> 00:07:43,759 Speaker 2: According to Copenhagen, it just vanishes from reality. It never existed. 159 00:07:44,120 --> 00:07:47,480 Speaker 1: That is so deeply weird. I mean, why, why does 160 00:07:47,519 --> 00:07:50,639 the act of looking the active measurement have this almost 161 00:07:50,680 --> 00:07:53,879 magical power to force reality to make a choice. 162 00:07:53,920 --> 00:07:57,759 Speaker 2: That was the problem. It introduced this strange dualism. You 163 00:07:57,839 --> 00:08:00,680 had the quantum world, which was governed by this smooth 164 00:08:00,720 --> 00:08:03,399 wave function, and then you had the classical world of 165 00:08:03,480 --> 00:08:07,000 observers and measuring devices, which followed different rules and could 166 00:08:07,000 --> 00:08:09,240 somehow reach in and break the quantum rules. 167 00:08:09,279 --> 00:08:11,240 Speaker 1: It seems so arbitrary, and a lot of the big 168 00:08:11,240 --> 00:08:13,120 thinkers at the time were really not happy. 169 00:08:12,879 --> 00:08:15,319 Speaker 2: With it, not at all. It felt like a philosophical cheat. 170 00:08:15,600 --> 00:08:19,560 It suggested that reality was fundamentally fuzzy and undecided until 171 00:08:19,600 --> 00:08:22,040 a conscious being or at least a big, clunky machine 172 00:08:22,120 --> 00:08:25,560 got involved. It took objectivity out of physics, and. 173 00:08:25,519 --> 00:08:27,560 Speaker 1: The person who hated the most was Albert Einstein. 174 00:08:27,839 --> 00:08:32,360 Speaker 2: Oh, he despised it. He was a realist through and through. 175 00:08:32,879 --> 00:08:36,799 He believed in an objective reality that exists independent of us. 176 00:08:37,200 --> 00:08:40,080 He just couldn't accept that the universe's fundamental nature was 177 00:08:40,120 --> 00:08:41,159 based on chance. 178 00:08:41,440 --> 00:08:43,679 Speaker 1: That's where his famous line comes from, Right, God does 179 00:08:43,720 --> 00:08:46,080 not play dice with the universe exactly. 180 00:08:46,440 --> 00:08:50,000 Speaker 2: He was convinced the theory was incomplete. He believed there 181 00:08:50,039 --> 00:08:53,960 must be some hidden variables, some deeper layer of reality 182 00:08:54,000 --> 00:08:57,120 we just hadn't discovered yet that would restore determinism and 183 00:08:57,200 --> 00:09:00,840 explain away all the randomness and to home just. 184 00:09:00,879 --> 00:09:05,759 Speaker 1: How absurd this whole observer causes collapse. Idea was another 185 00:09:05,840 --> 00:09:09,240 founder of the theory, or when Schrodinger came up with 186 00:09:09,279 --> 00:09:12,000 what has to be the most famous and maybe darkest 187 00:09:12,120 --> 00:09:14,360 thought experiment in all of science. 188 00:09:14,120 --> 00:09:17,120 Speaker 2: Schrodinger's cat. And it's so important to remember, as you said, 189 00:09:17,159 --> 00:09:19,919 he wasn't proposing this was real. He was making a 190 00:09:19,960 --> 00:09:23,120 reductio ad absurdum argument. He was trying to show the 191 00:09:23,240 --> 00:09:26,120 ridiculous logical conclusion of the Copenhagen interpretation. 192 00:09:26,279 --> 00:09:28,639 Speaker 1: So let's walk through the setup, because the details really matter. 193 00:09:28,679 --> 00:09:31,240 You take a cat, poor cat, You put it in 194 00:09:31,240 --> 00:09:35,120 a sealed steel box, and in that box with the cat, 195 00:09:35,159 --> 00:09:37,919 you have this diabolical device. 196 00:09:38,200 --> 00:09:41,399 Speaker 2: It's a tiny amount of radioactive material, so small that 197 00:09:41,480 --> 00:09:43,960 in the course of one hour there's a perfect fifty 198 00:09:43,960 --> 00:09:46,600 to fifty chance that just one atom will decay. 199 00:09:46,840 --> 00:09:49,919 Speaker 1: And if it does decay, it triggers a guy your counter. 200 00:09:49,799 --> 00:09:52,799 Speaker 2: Which is connected to a relay that releases a hammer. 201 00:09:52,480 --> 00:09:55,960 Speaker 1: Which then smashes a little flask of hydrocyanic acid, a 202 00:09:56,039 --> 00:09:58,559 deadly poison which would kill a cat insecse. 203 00:09:58,519 --> 00:10:00,879 Speaker 2: Very grim rube gold machine. 204 00:10:00,960 --> 00:10:03,000 Speaker 1: It is. So the key is that the fate of 205 00:10:03,039 --> 00:10:06,600 the cat is now inextricably linked, entangled with the state 206 00:10:06,639 --> 00:10:08,200 of that single quantum particle. 207 00:10:08,320 --> 00:10:11,159 Speaker 2: Precisely, the atom is the quantum system. It's in a 208 00:10:11,200 --> 00:10:14,919 superposition fifty percent decayd and fifty percent not decayed. And 209 00:10:14,960 --> 00:10:16,919 since the cat's life is now tied to it, the 210 00:10:16,960 --> 00:10:20,840 whole system atom hammer poison cat has to be described 211 00:10:20,840 --> 00:10:22,360 by one single wave function. 212 00:10:22,559 --> 00:10:25,759 Speaker 1: So, according to the Copenhagen interpretation, until an observer opens 213 00:10:25,799 --> 00:10:28,559 the box to make a measurement, what state is the cat. 214 00:10:28,360 --> 00:10:31,720 Speaker 2: In the cat is literally and mathematically in a superposition 215 00:10:31,799 --> 00:10:34,639 of being fifty percent alive andy fifty percent dead. 216 00:10:34,759 --> 00:10:37,879 Speaker 1: At the same time, maybe alive, maybe dead, both both. 217 00:10:38,159 --> 00:10:40,320 Speaker 2: It's only when you open the box that the system 218 00:10:40,320 --> 00:10:43,320 wide wave function collapses and the cat resolves into being 219 00:10:43,399 --> 00:10:46,399 either definitely alive or sadly definitely dead. 220 00:10:46,480 --> 00:10:51,360 Speaker 1: And Schrodinger's point was just that's insane. No one actually 221 00:10:51,440 --> 00:10:54,639 believes a cat is a sort of zombie ghost hybrid 222 00:10:54,960 --> 00:10:56,919 until we look at it. There has to be something 223 00:10:56,960 --> 00:11:01,279 wrong with an interpretation that leads to such a Bonker's conclusion. 224 00:11:01,600 --> 00:11:04,639 Speaker 2: The problem was the boundary, where does the quantum world 225 00:11:04,720 --> 00:11:08,399 stop and the classical world begin. Copenhagen was just totally 226 00:11:08,480 --> 00:11:09,320 vague on that point. 227 00:11:09,360 --> 00:11:14,200 Speaker 1: And yet, despite Einstein's objections, despite Schrodinger's brilliance at hire, 228 00:11:14,600 --> 00:11:18,360 the Copenhagen math just it worked. 229 00:11:18,600 --> 00:11:21,600 Speaker 2: It worked flawlessly, it was predictive, it was accurate. It's 230 00:11:21,600 --> 00:11:25,120 the foundation of the entire technological revolution of the twentieth century. 231 00:11:25,120 --> 00:11:27,679 So for decades the attitude of most physicists was just 232 00:11:27,960 --> 00:11:30,440 shut up and calculate except the weirdness. Don't ask what 233 00:11:30,440 --> 00:11:33,759 it means, just use the equations. But that discomfort, it 234 00:11:33,840 --> 00:11:36,399 never really went away, that special role for the observer. 235 00:11:36,440 --> 00:11:39,279 It just felt wrong, It felt I don't know, almost supernatural. 236 00:11:39,320 --> 00:11:41,679 Why should the laws of physics suddenly change just because 237 00:11:41,720 --> 00:11:43,639 a person decides to look at something right. 238 00:11:43,679 --> 00:11:47,919 Speaker 1: It's a huge philosophical leap, and that tension, that dissatisfaction, 239 00:11:48,039 --> 00:11:51,000 is really what set the stage for a completely different. 240 00:11:50,720 --> 00:11:52,799 Speaker 2: Approach, a truly radical one. 241 00:11:52,840 --> 00:11:55,600 Speaker 1: It comes in nineteen fifty seven a twenty seven year 242 00:11:55,639 --> 00:11:59,679 old PhD student at Princeton named Hugh Everett the Third's 243 00:11:59,759 --> 00:12:03,120 Right Now thesis, and he looks at this whole measurement problem, 244 00:12:03,200 --> 00:12:06,879 this collapse postulate, and he asks this incredibly simple but 245 00:12:07,039 --> 00:12:08,480 profound question, what if the. 246 00:12:08,399 --> 00:12:10,200 Speaker 2: Wave function never collapses at all? 247 00:12:10,320 --> 00:12:12,120 Speaker 1: What if the weird part is in the wave function? 248 00:12:12,200 --> 00:12:14,120 What if the weird part is this extra rule we 249 00:12:14,200 --> 00:12:16,080 added on the collapse exactly? 250 00:12:16,200 --> 00:12:18,200 Speaker 2: What if the math is telling us the truth all along? 251 00:12:18,279 --> 00:12:21,080 What if the probabilities in the wave function aren't just 252 00:12:21,200 --> 00:12:25,919 describing potential outcomes, but are actually describing all outcomes, all 253 00:12:25,919 --> 00:12:26,639 of which are real. 254 00:12:26,840 --> 00:12:30,639 Speaker 1: And that is the birth of the many World's interpretation MWI. 255 00:12:31,080 --> 00:12:33,559 Speaker 2: Everett's insight was just so elegant. He said, look, you 256 00:12:33,559 --> 00:12:35,440 don't need to add any new rules. You just have 257 00:12:35,519 --> 00:12:39,279 to take the existing rule, the Schrodinger equation that governs 258 00:12:39,320 --> 00:12:42,919 the wave function and take it seriously. Assume it applies 259 00:12:42,960 --> 00:12:45,639 to everything all the time, with no exceptions. 260 00:12:45,840 --> 00:12:47,960 Speaker 1: So let's get into the mechanics of it, the branching, 261 00:12:48,440 --> 00:12:51,919 because this is where it really diverges from Copenhagen. Let's 262 00:12:51,919 --> 00:12:54,759 go back to our electron with two choices. It can 263 00:12:54,759 --> 00:12:56,200 go left or go right. 264 00:12:56,519 --> 00:13:02,080 Speaker 2: Okay, So in the Copenhagen view, electron is in a superposition. 265 00:13:02,360 --> 00:13:05,360 It's a wave of left plus right, and observation happens, 266 00:13:05,399 --> 00:13:08,440 and bang, the wave collapses. Let's say it collapses to left. 267 00:13:08,240 --> 00:13:11,200 Speaker 1: And the possibility of it going right is just gone, 268 00:13:11,720 --> 00:13:12,360 wiped from. 269 00:13:12,159 --> 00:13:15,279 Speaker 2: Existence, annihilated. It never became real in our universe. But 270 00:13:15,360 --> 00:13:19,399 in everetts mwiview the process is totally different. The electron 271 00:13:19,480 --> 00:13:22,000 is in the superposition of left plus right, a measurement 272 00:13:22,120 --> 00:13:26,480 or really any irreversible interaction happens, and instead of collapsing in. 273 00:13:26,559 --> 00:13:28,559 Speaker 1: The universe itself splits, the entire. 274 00:13:28,399 --> 00:13:33,000 Speaker 2: Universe splits into two separate, equally real physical universes. 275 00:13:33,080 --> 00:13:35,679 Speaker 1: So in one universe the electron went left, and in 276 00:13:35,720 --> 00:13:38,200 another completely separate universe it went right. 277 00:13:38,440 --> 00:13:42,120 Speaker 2: Yes, And this process is what physicists call branching and 278 00:13:42,200 --> 00:13:44,960 it's not just the electron that splits. The measuring device splits, 279 00:13:45,000 --> 00:13:47,200 the air in the room splits you, the observer, You 280 00:13:47,240 --> 00:13:47,799 split too. 281 00:13:48,000 --> 00:13:50,440 Speaker 1: So there's a version of me in universe A that 282 00:13:50,519 --> 00:13:55,279 sees the electron go lest and another completely real version 283 00:13:55,320 --> 00:13:58,399 of me in universe B that sees it go left right. 284 00:13:59,120 --> 00:14:02,360 Speaker 2: And once that's split happens those two universes, those two 285 00:14:02,399 --> 00:14:05,480 branches of reality can never interact or communicate with each 286 00:14:05,480 --> 00:14:08,360 other ever. Again, they are causally disconnected. 287 00:14:08,480 --> 00:14:11,039 Speaker 1: Okay, now we have to scale this up because it's 288 00:14:11,039 --> 00:14:12,440 not just one electron every now and. 289 00:14:12,399 --> 00:14:14,879 Speaker 2: Then, O, my god, think about the sheer number of 290 00:14:15,000 --> 00:14:18,840 quantum events happen constantly every fraction of a nanosecond all 291 00:14:18,879 --> 00:14:21,720 over the universe. Every photon of light hitting your retina, 292 00:14:22,279 --> 00:14:26,279 every radioactive atom decaying in the Earth's crust, every molecule 293 00:14:26,320 --> 00:14:27,720 bouncing off another in the air. 294 00:14:27,919 --> 00:14:29,200 Speaker 1: Each one is a decision point. 295 00:14:29,399 --> 00:14:31,919 Speaker 2: Each one forces a split, which means the universe is 296 00:14:31,919 --> 00:14:35,200 branching at an almost infinitely fast rate. It's creating this 297 00:14:35,440 --> 00:14:39,919 unimaginably vast, ever growing tree of parallel realities. 298 00:14:40,080 --> 00:14:43,120 Speaker 1: My consciousness. Yeah, it's not just one thing. It's like 299 00:14:43,159 --> 00:14:45,840 a passenger on a train that's constantly arriving at a 300 00:14:45,840 --> 00:14:48,440 station where the tracks split in a million different directions. 301 00:14:48,639 --> 00:14:50,559 Speaker 2: That's a great way to put it. You are riding 302 00:14:50,600 --> 00:14:55,240 along one single path through this infinite multiverse, but at 303 00:14:55,320 --> 00:14:59,320 every single quantum juncture, an alternate version of you, just 304 00:14:59,360 --> 00:15:02,720 as real as you you are, continues on a different path. 305 00:15:02,879 --> 00:15:07,159 Speaker 1: So, yeah, this morning, I hesitated between having coffee or tea, 306 00:15:07,960 --> 00:15:10,600 and the quantum processes in my brain that led to 307 00:15:10,639 --> 00:15:14,039 that decision they branched. So there's a version of me 308 00:15:14,799 --> 00:15:17,559 out there right now who is having a very different 309 00:15:17,600 --> 00:15:18,519 day because he. 310 00:15:18,440 --> 00:15:20,960 Speaker 2: Chose tea, absolutely, and he's just as real as you are. 311 00:15:21,039 --> 00:15:24,519 He just exists on a different, inaccessible branch of the 312 00:15:24,600 --> 00:15:25,720 universal wave function. 313 00:15:25,879 --> 00:15:28,360 Speaker 1: The universal wave function that was Everett's big idea, right, 314 00:15:28,600 --> 00:15:29,879 one equation for everything. 315 00:15:30,039 --> 00:15:33,039 Speaker 2: That was the philosophical cleanup. Instead of having one set 316 00:15:33,039 --> 00:15:35,679 of rules for quantum stuff and another for big stuff, 317 00:15:35,720 --> 00:15:39,440 Everett said, there's just one thing, the universal wave function. 318 00:15:40,000 --> 00:15:42,799 It describes the state of the entire multiverse, and it 319 00:15:42,799 --> 00:15:46,279 always evolves smoothly according to one equation. The collapse is 320 00:15:46,320 --> 00:15:49,080 just our subjective experience of getting locked into one of 321 00:15:49,120 --> 00:15:51,879 these branches after a split it's so much cleaner. 322 00:15:51,759 --> 00:15:53,759 Speaker 1: So much more elegant. You'd think people would have jumped 323 00:15:53,799 --> 00:15:54,399 on it, you. 324 00:15:54,320 --> 00:15:59,000 Speaker 2: Would think, But the reception was huh, cold, glacial. Everett 325 00:15:59,039 --> 00:16:02,399 was only twenty seven. He takes his theory to Copenhagen 326 00:16:02,480 --> 00:16:05,279 to present it to the great Nils bore the father 327 00:16:05,399 --> 00:16:09,480 of the established interpretation, and Borr just completely dismissed it. 328 00:16:09,519 --> 00:16:11,960 Found it way too extravagant, too ridiculous. 329 00:16:12,000 --> 00:16:16,600 Speaker 1: Ookham's razor, right. Why invent an infinite number of unseeable 330 00:16:16,679 --> 00:16:20,039 universes just to get rid of one little rule about collapse? 331 00:16:20,360 --> 00:16:23,919 Speaker 2: That was the argument. The scientific community just wasn't ready 332 00:16:23,919 --> 00:16:26,519 for it. They stuck with what worked, what was practical, 333 00:16:26,879 --> 00:16:28,919 and Everett w well, he was pretty as heartened by 334 00:16:28,960 --> 00:16:29,320 the whole thing. 335 00:16:29,399 --> 00:16:32,000 Speaker 1: Yeah. Our sources say he left academia right after getting 336 00:16:32,039 --> 00:16:35,240 his PhD, never published another physics paper. 337 00:16:35,159 --> 00:16:37,080 Speaker 2: Which is such a tragedy. He went on to have 338 00:16:37,120 --> 00:16:40,600 a brilliant career in military research and computing, but his idea, 339 00:16:40,919 --> 00:16:44,120 the many World's interpretation just kind of sat dormant for 340 00:16:44,159 --> 00:16:47,559 almost two decades. It needed another piece of the puzzle 341 00:16:47,600 --> 00:16:48,919 to become truly viable. 342 00:16:49,399 --> 00:16:51,840 Speaker 1: Okay, so let's get into the big problem that MWI 343 00:16:51,919 --> 00:16:54,440 had for all those years, the one that made people 344 00:16:54,480 --> 00:16:56,559 like Borr dismiss it out of hand, right. 345 00:16:56,480 --> 00:16:59,000 Speaker 2: The elephant in the room. If the universe is constantly 346 00:16:59,039 --> 00:17:01,799 splitting into all these different branches, why do we only 347 00:17:01,840 --> 00:17:02,679 ever see. 348 00:17:02,440 --> 00:17:07,000 Speaker 1: One outcome exactly? If Schrodinger's cat is genuinely in a 349 00:17:07,039 --> 00:17:10,480 superposition of alive and dead, why when we open the 350 00:17:10,519 --> 00:17:14,319 box do we never see some sort of blurry half dead, 351 00:17:14,400 --> 00:17:15,880 half alive monstrosity. 352 00:17:16,000 --> 00:17:18,640 Speaker 2: Why don't we feel ourselves splitting? Why does every single 353 00:17:18,680 --> 00:17:21,839 experiment we've ever run look exactly like the wave function 354 00:17:21,920 --> 00:17:23,720 is collapsing to a single result. 355 00:17:23,960 --> 00:17:26,400 Speaker 1: This was the major hurdle. It's a great theory, but 356 00:17:26,480 --> 00:17:30,240 it seems to contradict observation. If the other worlds are real, 357 00:17:30,640 --> 00:17:32,319 where are they? Why can't we see them? 358 00:17:32,400 --> 00:17:35,960 Speaker 2: And the answer? The mechanism that rescued MWI from being 359 00:17:36,079 --> 00:17:39,720 just a philosophical curiosity didn't really come into focus until 360 00:17:39,759 --> 00:17:43,640 the nineteen seventies and eighties, and the key word is decoherence. 361 00:17:43,759 --> 00:17:46,079 Speaker 1: Decoherence, let's break that down. We probably have to start 362 00:17:46,079 --> 00:17:47,000 with coherence, then. 363 00:17:46,960 --> 00:17:50,279 Speaker 2: Good idea. A quantum system is coherent when all its 364 00:17:50,319 --> 00:17:53,359 different possible states like our electrons spin up and spin 365 00:17:53,400 --> 00:17:56,799 down states are all in a neat orderly relationship with 366 00:17:56,839 --> 00:18:00,200 each other. They maintain what's called a stable phase relationship. 367 00:18:00,240 --> 00:18:01,480 Speaker 1: It's like they're all marching instead. 368 00:18:01,640 --> 00:18:05,599 Speaker 2: Perfect analogy. But that coherence can only be maintained if 369 00:18:05,599 --> 00:18:08,440 the system is in perfect total isolation from the rest 370 00:18:08,480 --> 00:18:09,119 of the universe. 371 00:18:09,119 --> 00:18:10,440 Speaker 1: And in the real world, perfect. 372 00:18:10,200 --> 00:18:14,079 Speaker 2: Isolation is impossible. It's absolutely impossible. And that's where decoherence 373 00:18:14,079 --> 00:18:17,920 comes in. The instant that quantum system interacts with its environment, 374 00:18:18,039 --> 00:18:21,640 and I mean anything, a single photon of light bouncing 375 00:18:21,640 --> 00:18:26,599 off it, a stray air molecule, a tiny vibration, it 376 00:18:26,640 --> 00:18:29,599 becomes entangled with that environment. 377 00:18:29,480 --> 00:18:32,000 Speaker 1: Entanglement, so its fate is now tied to the fate 378 00:18:32,039 --> 00:18:33,279 of all these other particles. 379 00:18:33,400 --> 00:18:36,920 Speaker 2: Inextricably, the states of that one little electron are now 380 00:18:36,960 --> 00:18:40,119 linked to the states of the trillions upon trillions of 381 00:18:40,160 --> 00:18:43,880 particles in the surrounding environment. So if the electron goes left, 382 00:18:44,160 --> 00:18:46,559 all the air molecules around it are jostled in a 383 00:18:46,559 --> 00:18:47,599 way that reflects the. 384 00:18:47,640 --> 00:18:50,640 Speaker 1: Left path, and if it goes right, they're all jostled 385 00:18:50,680 --> 00:18:52,880 in a slightly different way that reflects the right path. 386 00:18:53,079 --> 00:18:57,640 Speaker 2: Precisely and because the environment is so unimaginably huge and complex, 387 00:18:57,799 --> 00:19:00,920 the simple neat wave function of the electron gets smeared 388 00:19:00,960 --> 00:19:04,359 out and lost in the staggeringly complex wave function of 389 00:19:04,400 --> 00:19:09,079 the environment. That nice orderly marching in step relationship between 390 00:19:09,119 --> 00:19:11,880 the spin up and spin down states is destroyed almost instantly. 391 00:19:12,079 --> 00:19:14,279 Speaker 1: That loss of order, that's decoherence. 392 00:19:14,359 --> 00:19:17,400 Speaker 2: That's decoherence. And what's so brilliant about it is that 393 00:19:17,480 --> 00:19:21,880 it provides a purely physical mechanical explanation for why the 394 00:19:21,920 --> 00:19:23,839 branches of the multiverse become separate. 395 00:19:24,000 --> 00:19:26,720 Speaker 1: So the left world where the electron and all the 396 00:19:26,759 --> 00:19:29,880 air molecules went one way, and the right world, where 397 00:19:29,880 --> 00:19:30,920 they all went another. 398 00:19:30,680 --> 00:19:33,720 Speaker 2: Way, they are now so vastly different. Their wave functions 399 00:19:33,720 --> 00:19:37,440 are so completely orthogonal to each other that they can't interfere. 400 00:19:37,640 --> 00:19:40,920 They can no longer interact or communicate. The information that 401 00:19:41,000 --> 00:19:43,519 will let them see each other has been diluted into 402 00:19:43,559 --> 00:19:45,119 the vastness of the environment. 403 00:19:45,519 --> 00:19:48,279 Speaker 1: So decoherence is the mechanism that prunes the branches of 404 00:19:48,319 --> 00:19:50,400 the tree and make sure they can't grow back into 405 00:19:50,480 --> 00:19:50,880 each other. 406 00:19:51,200 --> 00:19:54,240 Speaker 2: That's it exactly. So an MWI proponent looks at the 407 00:19:54,240 --> 00:19:57,960 results of an experiment and says, see, decoherence has rapidly 408 00:19:58,039 --> 00:20:03,720 and permanently separated the alternative outcomes into distinct, isolated realities. 409 00:20:03,240 --> 00:20:06,400 Speaker 1: While the Copenhagen believer looks at the exact same result 410 00:20:06,440 --> 00:20:08,799 and just says the wave function collapsed. 411 00:20:09,119 --> 00:20:13,200 Speaker 2: But the MWY explanation doesn't require a magic collapse rule. 412 00:20:13,640 --> 00:20:17,160 It just uses the standard known physics of entanglement and 413 00:20:17,279 --> 00:20:21,200 environmental interaction. It explains how the fuzzy quantum world can 414 00:20:21,240 --> 00:20:24,799 appear to become the definite classical world without needing any 415 00:20:24,839 --> 00:20:26,759 special role for a conscious observer. 416 00:20:27,000 --> 00:20:29,160 Speaker 1: And that's what made it a serious theory against It 417 00:20:29,200 --> 00:20:29,720 was everything. 418 00:20:29,799 --> 00:20:32,200 Speaker 2: It took away the biggest objection. It was no longer 419 00:20:32,240 --> 00:20:37,319 just a philosophical preference. Decoherence provided a concrete physical mechanism. 420 00:20:37,640 --> 00:20:41,039 It showed how MWI could be consistent with all our observations, 421 00:20:41,119 --> 00:20:44,319 retain all the predictive power of Copenhagen, and get rid 422 00:20:44,319 --> 00:20:47,240 of the part that Einstein and Schrodinger hated the most, 423 00:20:47,400 --> 00:20:52,079 the observer. The observer, it's removed from its special privileged position. 424 00:20:52,720 --> 00:20:55,480 The universe just does its thing, splitting and evolving according 425 00:20:55,480 --> 00:21:00,720 to one consistent law. So once decoherence was understood, MWI 426 00:21:00,799 --> 00:21:04,680 wasn't this fringe idea anymore. It became a respectable, viable 427 00:21:04,759 --> 00:21:09,039 contender for what's actually happening at the fundamental level of reality, and. 428 00:21:09,000 --> 00:21:11,039 Speaker 1: In the twenty first century it's really gained a lot 429 00:21:11,039 --> 00:21:11,440 of ground. 430 00:21:11,680 --> 00:21:15,599 Speaker 2: It has when you pull physicists today on which interpretation 431 00:21:15,680 --> 00:21:18,839 they favor. Copenhagen and its modern variations are still in 432 00:21:18,880 --> 00:21:22,279 the lead, but MWI is a strong second. Somewhere around 433 00:21:22,279 --> 00:21:23,960 twenty percent of the community. 434 00:21:23,640 --> 00:21:26,519 Speaker 1: Endorses it, and its popularity seems to be rising, especially 435 00:21:26,559 --> 00:21:30,079 with people in certain fields right like cosmologists and quantum 436 00:21:30,160 --> 00:21:31,319 information scientists. 437 00:21:31,480 --> 00:21:33,640 Speaker 2: Yes, people who have to deal with the universe as 438 00:21:33,680 --> 00:21:36,519 a whole quantum system, or who work directly with things 439 00:21:36,559 --> 00:21:40,759 like entanglement and superposition all day. For them, MWI is 440 00:21:40,759 --> 00:21:42,720 often the most straightforward way to think about it. 441 00:21:42,720 --> 00:21:45,440 Speaker 1: And as our sources point out, things have really heated 442 00:21:45,519 --> 00:21:48,480 up recently because of a very practical, real. 443 00:21:48,279 --> 00:21:49,759 Speaker 2: World development quantum computer. 444 00:21:49,880 --> 00:21:53,160 Speaker 1: It's quantum computers. This is where the theory might actually 445 00:21:53,160 --> 00:21:55,759 be moving from the abstract to something we can see 446 00:21:55,759 --> 00:21:57,119 the effects of potentially. 447 00:21:57,279 --> 00:21:59,599 Speaker 2: Yes, to get it, we need a quick refresher on 448 00:21:59,640 --> 00:22:03,640 how computer's work. Your laptop or phone uses classical bits. 449 00:22:03,799 --> 00:22:06,000 They're like little switches. They can be either a zero 450 00:22:06,079 --> 00:22:06,839 or a one. 451 00:22:06,720 --> 00:22:09,839 Speaker 1: On or off. Simple all calculations are done one after 452 00:22:09,880 --> 00:22:11,200 another sequentially. 453 00:22:11,480 --> 00:22:15,200 Speaker 2: But a quantum computer uses quibits, and because of superposition, 454 00:22:15,519 --> 00:22:17,680 a quibit can be both a zero and a one 455 00:22:17,799 --> 00:22:20,720 at the same time, that blurry state against exactly. And 456 00:22:20,799 --> 00:22:22,799 if you have two quibits, they can be in a 457 00:22:22,839 --> 00:22:27,640 superposition of all four possible states zero, zero, zero, one, ten, 458 00:22:27,799 --> 00:22:32,119 and eleven simultaneously. This is where the exponential power comes from. 459 00:22:32,240 --> 00:22:34,920 Instead of doing one calculation at a time, a quantum 460 00:22:34,920 --> 00:22:38,799 computer can explore a huge number of possible calculation paths, 461 00:22:38,839 --> 00:22:39,680 all in parallel. 462 00:22:39,720 --> 00:22:43,200 Speaker 1: And David Deutsch, who's a huge modern proponent of MWI, 463 00:22:43,279 --> 00:22:45,319 I mean, it's a fascinating argument about this. He basically 464 00:22:45,359 --> 00:22:49,240 says quantum computers are indirect physical evidence of the multiverse. 465 00:22:49,279 --> 00:22:52,519 Speaker 2: It's a really provocative claim. Let's use his example. Suppose 466 00:22:52,519 --> 00:22:55,000 you build a quantum computer with three hundred qubits that 467 00:22:55,039 --> 00:22:58,079 are all entangled. That system is now in a superposition 468 00:22:58,200 --> 00:23:01,079 of two to the power of three hundred classical. 469 00:23:00,640 --> 00:23:02,839 Speaker 1: States and two to the three hundred. I mean, that 470 00:23:02,920 --> 00:23:06,680 number is just it's beyond astronomical it's. 471 00:23:06,519 --> 00:23:08,920 Speaker 2: A number that is vastly larger than the total number 472 00:23:08,920 --> 00:23:13,200 of atoms in the entire observable universe. It's incomprehensibly huge. 473 00:23:13,400 --> 00:23:16,680 Speaker 1: Okay, so you have this machine in a state of 474 00:23:16,799 --> 00:23:20,119 two the three hundred possibilities and you run a quantum 475 00:23:20,160 --> 00:23:23,279 algorithm on it. Where is that computation actually happening? 476 00:23:23,359 --> 00:23:26,960 Speaker 2: That's Deutsche's killer question. If that computation is exploring all 477 00:23:26,960 --> 00:23:29,960 those possibilities in parallel to find the answer, and say 478 00:23:30,000 --> 00:23:32,960 a few minutes, where did the physical resources to do 479 00:23:33,000 --> 00:23:35,960 that come from? Our one single universe doesn't have enough 480 00:23:35,960 --> 00:23:38,119 matter to write down the problem, let alone solve it 481 00:23:38,160 --> 00:23:38,640 that fast. 482 00:23:38,759 --> 00:23:39,559 Speaker 1: So his answer is. 483 00:23:39,599 --> 00:23:41,799 Speaker 2: His answer is that those two to the three hundred 484 00:23:41,799 --> 00:23:44,680 parallel computations are literally being performed in two to the 485 00:23:44,720 --> 00:23:48,039 three hundred parallel universes. The quantum computer is, in a 486 00:23:48,160 --> 00:23:51,599 very real sense, harnessing the processing power of the multiverse. 487 00:23:51,880 --> 00:23:55,839 Speaker 1: That is just a staggering thought. Yeah, that the reason 488 00:23:55,839 --> 00:23:58,559 these machines are so powerful is that they are borrowing 489 00:23:58,599 --> 00:24:00,079 resources from other realities. 490 00:24:00,279 --> 00:24:05,119 Speaker 2: It provides a simple, if mind boggling, physical explanation for 491 00:24:05,319 --> 00:24:09,039 where the power comes from. If you don't accept MWI, 492 00:24:09,160 --> 00:24:11,759 you have to come up with some other, often much 493 00:24:11,799 --> 00:24:16,119 more convoluted, explanation for how all that parallel processing is 494 00:24:16,160 --> 00:24:18,480 happening within our single universe. 495 00:24:18,559 --> 00:24:20,319 Speaker 1: Well, hold on, I have to play Devil's advocate here 496 00:24:20,359 --> 00:24:23,279 for a second. Isn't this still just a matter of interpretation? 497 00:24:23,480 --> 00:24:26,200 It sounds great, but doesn't this sheer extravagance of it 498 00:24:26,240 --> 00:24:31,599 the infinite universes just violate Okham's razor. M isn't it 499 00:24:31,640 --> 00:24:34,400 simpler to just believe in the collapse even if it's weird? 500 00:24:34,680 --> 00:24:38,079 Speaker 2: That is the number one philosophical argument against MWI, and 501 00:24:38,119 --> 00:24:40,480 it's a very fair one. Critics say it's not a 502 00:24:40,519 --> 00:24:43,359 real scientific theory because it's non falsifiable. We can never 503 00:24:43,440 --> 00:24:46,079 visit these other branches to prove they exist. Right, But 504 00:24:46,160 --> 00:24:49,559 proponents like George flip Oham's razor right back at them. 505 00:24:49,880 --> 00:24:52,640 They argue that MWI is actually the simpler theory from 506 00:24:52,640 --> 00:24:55,839 a physics perspective, because it doesn't add any new laws. 507 00:24:56,319 --> 00:24:59,920 Copenhagen adds a whole new arbitrary rule, the collapse posti, 508 00:25:00,440 --> 00:25:03,559 that says the known laws of physics stop working when 509 00:25:03,559 --> 00:25:07,559 a measurement happens. MWI just takes the one known law, 510 00:25:07,720 --> 00:25:10,319 the Schroderer equation, and says the sit this is the 511 00:25:10,319 --> 00:25:13,640 only rule, and it applies to everything, everywhere, all the time. 512 00:25:13,799 --> 00:25:16,839 Speaker 1: So MWI has fewer rules, even if it leads to 513 00:25:16,839 --> 00:25:17,960 a much bigger reality. 514 00:25:18,079 --> 00:25:21,079 Speaker 2: Exactly, it's the simplest law, even if it produces the 515 00:25:21,079 --> 00:25:24,599 most complex cosmos. And that's the reframing. It's not a 516 00:25:24,599 --> 00:25:27,720 complex theory. It's the simplest interpretation of the mac we 517 00:25:27,759 --> 00:25:28,759 already know is correct. 518 00:25:28,880 --> 00:25:31,319 Speaker 1: And if we're going to accept that, if we accept 519 00:25:31,319 --> 00:25:36,000 this new definition of reality with infinite, constantly generated parallel worlds, 520 00:25:37,200 --> 00:25:39,720 well we have to talk about the ultimate consequence for us, 521 00:25:39,759 --> 00:25:40,400 for the observer. 522 00:25:40,640 --> 00:25:43,319 Speaker 2: So if we take the many world's interpretation as a given, 523 00:25:43,559 --> 00:25:46,359 just for the sake of argument, if reality really is 524 00:25:46,400 --> 00:25:49,039 this constantly branching tree of possibilities, and. 525 00:25:49,119 --> 00:25:52,640 Speaker 1: What does that mean for us, for human consciousness? And 526 00:25:52,680 --> 00:25:54,720 this is where we get to the most speculative but 527 00:25:54,799 --> 00:25:56,960 also the most profound implication. 528 00:25:56,480 --> 00:25:58,200 Speaker 2: Of all quantum immortality. 529 00:25:58,480 --> 00:26:02,160 Speaker 1: It's a direct, if contra virtial, logical consequence of the theory. 530 00:26:02,680 --> 00:26:05,640 The core idea is all about the subjective continuity of 531 00:26:05,680 --> 00:26:09,119 your experience from your own point of view. Do you 532 00:26:09,160 --> 00:26:10,960 ever actually witness your own death. 533 00:26:11,519 --> 00:26:14,240 Speaker 2: Let's run a thought experiment, a pretty grim one, as 534 00:26:14,319 --> 00:26:17,319 laid out in the research. Imagine you're in a situation 535 00:26:17,400 --> 00:26:20,279 that is almost certain to be fatal, a game of 536 00:26:20,359 --> 00:26:23,759 Russian Roulette, but with a quantum trigger instead of a 537 00:26:23,799 --> 00:26:24,640 spinning chamber. 538 00:26:24,799 --> 00:26:27,480 Speaker 1: Okay, so there's a gun pointed at your head and 539 00:26:27,519 --> 00:26:29,319 it's set up to fire based on the spin of 540 00:26:29,319 --> 00:26:32,680 an electron. The electron is measured to spin down, it fires. 541 00:26:32,720 --> 00:26:35,319 If it's pin up, it just clicks, and the odds 542 00:26:35,359 --> 00:26:36,559 are fifty to fifty. 543 00:26:36,680 --> 00:26:38,960 Speaker 2: You pull the trigger, the quantum measurement is made, the 544 00:26:39,079 --> 00:26:42,160 universe splits. In one massive branch, fifty percent of the 545 00:26:42,200 --> 00:26:45,319 wave function, the electron will spin down, the gun fires, 546 00:26:45,599 --> 00:26:46,920 and you die instantly. 547 00:26:47,279 --> 00:26:49,279 Speaker 1: End of story for that version of may end of story. 548 00:26:49,279 --> 00:26:51,039 Speaker 2: But in the other branch, the other fifty percent, the 549 00:26:51,079 --> 00:26:53,519 electron will spin up, the gun clicks, and you're still alive, 550 00:26:53,599 --> 00:26:55,960 heart pounding thinking, who I got lucky. 551 00:26:56,240 --> 00:26:59,960 Speaker 1: The theory of quantum immortality says that your subjective consciousness, 552 00:27:00,240 --> 00:27:03,680 the thing you experience as you, can only continue in 553 00:27:03,720 --> 00:27:04,920 the branch where you survive. 554 00:27:05,279 --> 00:27:10,559 Speaker 2: Because consciousness, by definition requires a functioning brain. The stream 555 00:27:10,680 --> 00:27:13,759 of your awareness is terminated in the death branch. So 556 00:27:13,839 --> 00:27:16,960 from your perspective, you will always find yourself in the 557 00:27:17,000 --> 00:27:18,400 branch where the gun clicked. 558 00:27:18,559 --> 00:27:21,680 Speaker 1: So I pulled the trigger again. The universe splits again. Again, 559 00:27:21,839 --> 00:27:24,559 My consciousness follows the survival path. 560 00:27:24,599 --> 00:27:28,480 Speaker 2: And again and again. From your subjective point of view, 561 00:27:28,640 --> 00:27:31,559 you play ten rounds, one hundred rounds, one thousand rounds, 562 00:27:31,559 --> 00:27:34,200 and the gun just clicks every single time. You would 563 00:27:34,240 --> 00:27:36,160 feel like the luckiest person who ever lived. 564 00:27:36,200 --> 00:27:39,160 Speaker 1: You would seem immortal, while in the vast majority of universes, 565 00:27:39,319 --> 00:27:41,079 countless versions of me are dead. 566 00:27:41,319 --> 00:27:44,960 Speaker 2: Exactly, death becomes something that only ever happens to the 567 00:27:45,000 --> 00:27:47,680 other guys who just happen to also be you. For 568 00:27:47,799 --> 00:27:50,880 the continuous stream of consciousness that you identify as yourself, 569 00:27:51,039 --> 00:27:52,839 you only ever experience survival. 570 00:27:52,960 --> 00:27:55,559 Speaker 1: And this isn't just some fringe idea attacked on Hugh 571 00:27:55,599 --> 00:27:58,160 Everett himself, the guy who came up with MWI. 572 00:27:58,960 --> 00:28:03,039 Speaker 2: He believed this, he did now. He was very careful. 573 00:28:03,160 --> 00:28:07,119 He never wrote about quantum immortality in his formal physics papers. 574 00:28:07,160 --> 00:28:11,079 It was too speculative, But his colleagues, his friends, even 575 00:28:11,079 --> 00:28:14,240 his family have all said in secondhand accounts that he 576 00:28:14,440 --> 00:28:18,039 privately believed his theory guaranteed his own immortality. 577 00:28:18,279 --> 00:28:22,559 Speaker 1: He genuinely believed that his consciousness would just follow whichever 578 00:28:22,640 --> 00:28:24,279 branch didn't lead to his death. 579 00:28:24,359 --> 00:28:27,400 Speaker 2: It's a pretty powerful belief to hold. Imagine living your 580 00:28:27,440 --> 00:28:30,160 life with that conviction. You might see a series of 581 00:28:30,200 --> 00:28:33,400 what looked like miracles. You survive a car crash that 582 00:28:33,440 --> 00:28:36,559 should have been fatal, You recover from a disease that 583 00:28:36,640 --> 00:28:38,920 was supposed to be terminal to you. It feels like 584 00:28:38,920 --> 00:28:40,599 a one in a billion streak of luck. 585 00:28:40,799 --> 00:28:43,640 Speaker 1: But in the MWI view, it's just you following the 586 00:28:43,680 --> 00:28:46,119 one in a billion survival branch that was always there 587 00:28:46,119 --> 00:28:46,920 in the wave function. 588 00:28:47,160 --> 00:28:49,559 Speaker 2: And this connects in a really fascinating way to near 589 00:28:49,599 --> 00:28:50,599 death experiences. 590 00:28:50,720 --> 00:28:52,079 Speaker 1: Oh wow, think about it. 591 00:28:52,200 --> 00:28:55,240 Speaker 2: Someone has a terrible accident, their heart stops, and they 592 00:28:55,279 --> 00:28:58,279 report this experience of seeing a light a tunnel a 593 00:28:58,400 --> 00:29:02,480 life review. If that subjective flash isn't just brain chemistry, 594 00:29:02,759 --> 00:29:05,680 what if that's the moment the multiverse branch violently. 595 00:29:05,599 --> 00:29:08,640 Speaker 1: And the person reporting the experience is the one whose 596 00:29:08,680 --> 00:29:13,079 consciousness made it through to an incredibly improbable survival branch. 597 00:29:13,480 --> 00:29:16,519 Speaker 2: While trillions of other versions of them simply died and 598 00:29:16,519 --> 00:29:19,759 couldn't report anything. We only ever hear from the survivors. 599 00:29:20,160 --> 00:29:23,000 So what we call a near death experience might just 600 00:29:23,039 --> 00:29:25,039 be what it feels like to land on a low 601 00:29:25,119 --> 00:29:27,920 probability branch of the wave function where you didn't die. 602 00:29:28,160 --> 00:29:32,799 Speaker 1: The implication is just staggering. It means every single fatal event, 603 00:29:32,880 --> 00:29:37,480 no matter how certain, has some astronomically tiny, non zero 604 00:29:37,559 --> 00:29:40,079 probability of survival hidden in the math. 605 00:29:40,240 --> 00:29:43,079 Speaker 2: A quantum tunnel effect in your cells that stops a bullet, 606 00:29:43,119 --> 00:29:45,240 a freak gust of wind that saves you from a fall, 607 00:29:45,519 --> 00:29:48,680 and your consciousness will always experience that improbable outcome. 608 00:29:48,880 --> 00:29:51,200 Speaker 1: So from my own frame of reference, death is an illusion. 609 00:29:51,319 --> 00:29:54,079 It's something that is constantly happening to my duplicates, but 610 00:29:54,200 --> 00:29:54,759 never to me. 611 00:29:55,240 --> 00:29:57,720 Speaker 2: But that raises a huge question about identity, doesn't it. 612 00:29:58,079 --> 00:30:00,279 If I am the version of me that survives ten 613 00:30:00,400 --> 00:30:03,039 rounds of quantum roulette, am I still the same person 614 00:30:03,079 --> 00:30:05,640 as the one who started after experiencing a series of 615 00:30:05,680 --> 00:30:09,039 impossible escapes? My life would be so radically different from 616 00:30:09,079 --> 00:30:10,400 the statistical average. 617 00:30:10,599 --> 00:30:13,160 Speaker 1: At what point do I become a completely different person 618 00:30:13,559 --> 00:30:16,880 defined only by my improbable survival? 619 00:30:17,039 --> 00:30:20,680 Speaker 2: That's the ultimate existential fallout of the theory. The physics 620 00:30:20,799 --> 00:30:24,920 might guarantee your subjective continuity, but it shatters our concept 621 00:30:24,960 --> 00:30:26,880 of a single, unified self. 622 00:30:27,319 --> 00:30:31,160 Speaker 1: Wow. Okay, that has been a deep, deep dive. We 623 00:30:31,200 --> 00:30:33,720 started in the safe, deterministic. 624 00:30:33,039 --> 00:30:38,000 Speaker 2: Classical world, and we plunged right into the strange, probabilistic 625 00:30:38,079 --> 00:30:41,720 quantum realm, all governed by the enigmatic wave function. 626 00:30:41,920 --> 00:30:43,920 Speaker 1: We saw the first big attempt to make sense of 627 00:30:43,960 --> 00:30:48,039 it all, the Copenhagen interpretation, the idea that an observer's 628 00:30:48,079 --> 00:30:50,279 measurement forces the wave function. 629 00:30:50,039 --> 00:30:53,079 Speaker 2: To collapse, a position that led to the wonderful absurdity 630 00:30:53,119 --> 00:30:56,079 of Schrodinger's cat being both alive and dead and prompted 631 00:30:56,079 --> 00:30:59,119 Einstein's famous protest that God doesn't play dice. 632 00:30:59,079 --> 00:31:02,400 Speaker 1: And then the radical alternative from Hugh Everett, the Many 633 00:31:02,440 --> 00:31:06,079 World's interpretation. The wave function never collapses, it just branches. 634 00:31:06,720 --> 00:31:10,359 Every possible outcome becomes real in its own parallel universe. 635 00:31:10,720 --> 00:31:14,039 Speaker 2: We saw how that wild idea was made physically plausible 636 00:31:14,079 --> 00:31:17,640 by the discovery of decoherence, the way a quantum system's 637 00:31:17,640 --> 00:31:21,599 interaction with the environment naturally isolates these branches, giving us 638 00:31:21,640 --> 00:31:23,000 the illusion of a collapse. 639 00:31:23,279 --> 00:31:26,000 Speaker 1: And finally we saw how This framework isn't just philosophy. 640 00:31:26,039 --> 00:31:29,440 It has connections to the real world, offering a potential 641 00:31:29,519 --> 00:31:33,759 explanation for the incredible power of quantum computers. 642 00:31:33,559 --> 00:31:35,519 Speaker 2: And leading us down the rabbit hole to the ultimate 643 00:31:35,519 --> 00:31:39,960 thought experiment, quantum immortality, where your consciousness might just be 644 00:31:40,039 --> 00:31:43,640 a passenger that always, against all odds, finds itself on 645 00:31:43,680 --> 00:31:44,640 the path of survival. 646 00:31:44,839 --> 00:31:47,279 Speaker 1: So we always end with a final provocative thought for 647 00:31:47,319 --> 00:31:48,279 you to take away. 648 00:31:48,519 --> 00:31:52,519 Speaker 2: Right and here it is. If your subjective reality is 649 00:31:52,519 --> 00:31:55,559 in fact guaranteed to follow the survival path through every 650 00:31:55,640 --> 00:31:58,559 single fatal quantum decision, what does that really mean for 651 00:31:58,599 --> 00:32:01,440 your sense of self? Think about it this way. If 652 00:32:01,480 --> 00:32:04,119 eighty percent of all possible future branches of your life 653 00:32:04,160 --> 00:32:07,039 and in a tragic car accident tomorrow, but your consciousness 654 00:32:07,079 --> 00:32:10,160 is guaranteed to follow the remaining twenty percent, the improbable 655 00:32:10,200 --> 00:32:12,680 branch where you swerve at the last second, what price 656 00:32:12,759 --> 00:32:14,480 do all those other versions of you pay for your 657 00:32:14,480 --> 00:32:15,680 subjective immortality. 658 00:32:15,839 --> 00:32:18,759 Speaker 1: They are just as real, Their experience was just as 659 00:32:18,839 --> 00:32:21,200 valid up until the moment it was extinguished. 660 00:32:21,359 --> 00:32:24,559 Speaker 2: Does your singular, continuous experience come at the cost of 661 00:32:24,599 --> 00:32:28,880 the termination of millions of your other selves? If reality 662 00:32:28,920 --> 00:32:31,759 is an infinite tree, but your awareness only ever follows 663 00:32:31,799 --> 00:32:36,359 one increasingly unlikely golden path. It forces us to ask 664 00:32:36,440 --> 00:32:39,039 what self and time and luck even mean. And a 665 00:32:39,079 --> 00:32:41,200 cosmos that is perpetually splitting. 666 00:32:41,720 --> 00:32:43,559 Speaker 1: Was that near miss you had on the highway last 667 00:32:43,559 --> 00:32:46,279 week just a lucky break? Or did a very real 668 00:32:46,400 --> 00:32:49,039 alternate version of you in a universe that just split 669 00:32:49,119 --> 00:32:52,240 off from ours make the ultimate sacrifice so that your 670 00:32:52,240 --> 00:32:53,799 conscious journey could continue. 671 00:32:53,880 --> 00:32:55,200 Speaker 2: The deep dive is complete. 672 00:32:55,240 --> 00:32:55,960 Speaker 1: We'll see next time.