WEBVTT 1 00:00:03.399 --> 00:00:07.719 Welcome to Bedtime Astronomy. Explore the wonders of the cosmos 2 00:00:07.759 --> 00:00:12.279 with our soothing Bedtime Astronomie podcast. Each episode offers a 3 00:00:12.359 --> 00:00:16.320 gentle journey through the stars, planets, and beyond, perfect for 4 00:00:16.399 --> 00:00:20.239 unwinding after a long day. Let's travel through the mysteries 5 00:00:20.239 --> 00:00:22.440 of the universe as you drift off into a peaceful 6 00:00:22.480 --> 00:00:23.800 slumber under the night sky. 7 00:00:26.879 --> 00:00:29.359 I want you to imagine the absolute bottom of the 8 00:00:29.399 --> 00:00:32.399 Mediterranean Sea. I mean we are talking over three thousand 9 00:00:32.520 --> 00:00:35.840 meters down right in this place called the Capo Pasero site, 10 00:00:35.880 --> 00:00:37.200 which is just off the coast of. 11 00:00:37.200 --> 00:00:40.960 Sicily, right, and it is a completely alien environment down there. 12 00:00:41.000 --> 00:00:45.240 Oh absolutely. The pressure is just immense, like hundreds of 13 00:00:45.240 --> 00:00:47.759 times greater than what we feel at the surface. And 14 00:00:47.880 --> 00:00:50.280 it is pitch black. I mean, the only light you 15 00:00:50.359 --> 00:00:54.159 might ever see comes from the faint biluminescence of these 16 00:00:54.200 --> 00:00:55.399 weird deep sea creatures. 17 00:00:55.479 --> 00:00:59.640 It's freezing, it's quiet, and it is almost entirely undisturbed. 18 00:00:59.799 --> 00:01:03.399 Yeah, yeah, exactly. And sitting right there on the floor 19 00:01:03.439 --> 00:01:08.560 of this abyss is a massive silent machine. It's basically 20 00:01:08.599 --> 00:01:12.719 a grid of glass spheres suspended on cables, forming this 21 00:01:12.719 --> 00:01:15.040 structure that is the size of a cubic kilometer, and. 22 00:01:15.000 --> 00:01:16.879 It doesn't move, It doesn't make a single sound. 23 00:01:16.920 --> 00:01:17.760 No, it just waits. 24 00:01:18.040 --> 00:01:21.319 It waits in that absolute darkness for a ghost, literally, 25 00:01:21.480 --> 00:01:25.280 a particle that is so elusive, so you know, unbothered 26 00:01:25.319 --> 00:01:28.200 by physical reality, that it can travel across billions of 27 00:01:28.280 --> 00:01:29.439 light years of empty. 28 00:01:29.120 --> 00:01:31.400 Space just flying through the void right it. 29 00:01:31.400 --> 00:01:34.000 Enters our solar system, passes straight through the Earth's crust, 30 00:01:34.319 --> 00:01:37.400 blasts right through the boiling liquid iron of the outer core, 31 00:01:37.840 --> 00:01:41.040 and just emerges out the other side without even slowing down. 32 00:01:41.120 --> 00:01:43.760 It doesn't bounce off anything. It leaves no wake. I mean, 33 00:01:43.799 --> 00:01:46.760 to this particle, the solid matter of our entire planet 34 00:01:47.000 --> 00:01:49.239 might as well just be an empty vacuum. 35 00:01:48.879 --> 00:01:50.879 Which is what makes it so incredibly fascinating. 36 00:01:50.959 --> 00:01:53.400 It really is. And the reason we are venturing into 37 00:01:53.480 --> 00:01:56.280 that pitch black ocean abyss today is because back in 38 00:01:56.319 --> 00:01:59.280 February of twenty twenty three, that silent machine didn't just 39 00:01:59.359 --> 00:02:01.879 catch one of them, these normal ghosts. It caught an 40 00:02:02.000 --> 00:02:03.239 absolute titan. 41 00:02:03.480 --> 00:02:08.159 It really did. It recorded a singular, microscopic particle carrying 42 00:02:08.199 --> 00:02:12.439 an amount of energy so staggering, so terrifyingly vast, that 43 00:02:12.520 --> 00:02:15.800 it actually threatens to rewrite our understanding of the universe's 44 00:02:16.039 --> 00:02:16.800 ultimate limits. 45 00:02:16.879 --> 00:02:20.560 Yeah, the event was quietly cataloged as KM three two 46 00:02:20.560 --> 00:02:23.479 three zero two one three A catch you name, right, 47 00:02:23.759 --> 00:02:27.240 But what that string of letters and numbers actually represents 48 00:02:27.360 --> 00:02:30.120 is a violent collision with the deepest mysteries of physics. 49 00:02:30.280 --> 00:02:34.159 The sheer physics of this event is honestly difficult to overstate, right. 50 00:02:34.000 --> 00:02:38.159 Because we are talking about a particle that is essentially massless, right, 51 00:02:38.439 --> 00:02:42.159 a spect of subatomic nothingness just slamming into our reality 52 00:02:42.439 --> 00:02:44.319 with two hundred and twenty ped electron volts of. 53 00:02:44.319 --> 00:02:47.080 Energy, exactly. And to find the source of that kind 54 00:02:47.120 --> 00:02:50.560 of power, you really have to look past the normal, 55 00:02:51.240 --> 00:02:53.719 quiet processes of the cosmos. 56 00:02:53.759 --> 00:02:55.840 You have to look at the high energy universe, like 57 00:02:55.960 --> 00:02:59.199 the cataclysmic, the ancient, and the catastrophic stuff. 58 00:02:58.879 --> 00:03:02.240 You do because standard stars don't do this, No, they don't. 59 00:03:02.719 --> 00:03:05.240 And for anyone listening right now, I want to stress 60 00:03:05.280 --> 00:03:07.759 that this isn't just some abstract accounting error in a 61 00:03:07.840 --> 00:03:12.919 theoretical physics paper. This is about probing the actual architecture. 62 00:03:12.360 --> 00:03:15.080 Of reality, the literal rulebook of the universe. 63 00:03:15.159 --> 00:03:17.319 Yeah, the laws of physics that govern the device you 64 00:03:17.319 --> 00:03:20.240 are listening on the biology of yourselves, the gravity holding 65 00:03:20.280 --> 00:03:22.919 you to the floor. I mean, those laws are currently incomplete. 66 00:03:23.360 --> 00:03:25.680 We know they are broken at the extremes, and. 67 00:03:25.719 --> 00:03:29.000 This single two hundred and twenty ped electron bolt ghost 68 00:03:29.479 --> 00:03:31.879 might be the exact tool we need to find out 69 00:03:31.919 --> 00:03:33.520 what the real rules actually are. 70 00:03:33.719 --> 00:03:37.280 So we need to break this down mechanically, because before 71 00:03:37.319 --> 00:03:40.240 we can even get to the underwater trap or you know, 72 00:03:40.360 --> 00:03:43.680 the crazy cosmic origins, we have to start with the 73 00:03:43.719 --> 00:03:48.800 anatomy of the phantom itself. We are talking about neutrinos. 74 00:03:48.159 --> 00:03:52.000 Right, the neutrino. It is perhaps the most solitary particle 75 00:03:52.080 --> 00:03:54.319 in the entire standard model of physics. 76 00:03:54.360 --> 00:03:55.680 It's kind of the ultimate loaner. 77 00:03:56.240 --> 00:03:58.159 That is a perfect way to put it. Because to 78 00:03:58.280 --> 00:04:00.800 understand its isolation, you have have to look at how 79 00:04:00.840 --> 00:04:03.719 particles actually communicate with one another. I mean, in the 80 00:04:03.800 --> 00:04:06.719 quantum realm, interaction is communication. 81 00:04:06.319 --> 00:04:09.599 Right, like how electrons push away from other electrons because 82 00:04:09.599 --> 00:04:14.240 they communicate via the electromagnetic force. They exchange photons. 83 00:04:13.759 --> 00:04:17.199 Exactly, and quarks bind together in the nucleus because they 84 00:04:17.199 --> 00:04:20.959 communicate via the strong nuclear force by exchanging gluons. 85 00:04:21.360 --> 00:04:24.399 So they basically have a mechanism to say I'm here, 86 00:04:24.639 --> 00:04:27.160 get away from me, or i am here stick to me. 87 00:04:27.360 --> 00:04:32.000 Yes, exactly. But the neutrino is entirely blind to electromagnetism. 88 00:04:32.120 --> 00:04:34.399 It carries zero electrical charge. 89 00:04:34.079 --> 00:04:36.879 So it literally cannot feel magnetic fields, and it cannot 90 00:04:36.879 --> 00:04:38.040 interact with light at all. 91 00:04:38.319 --> 00:04:41.839 None. And it is also completely blind to the strong 92 00:04:41.920 --> 00:04:45.639 nuclear force, so it just ignores the dense cores of atoms. 93 00:04:46.040 --> 00:04:48.639 Out of the fundamental forces of nature, the neutrino only 94 00:04:48.639 --> 00:04:49.319 feels two of. 95 00:04:49.279 --> 00:04:51.639 Them, gravity and the weak nuclear force. 96 00:04:51.800 --> 00:04:56.439 Right, and since gravity is incredibly feeble on a subatomic scale, 97 00:04:56.519 --> 00:04:59.120 that really just leaves the weak force, which you. 98 00:04:59.079 --> 00:05:01.800 Know to its name, doesn't give you a whole lot 99 00:05:01.800 --> 00:05:02.639 of stopping power. 100 00:05:02.800 --> 00:05:07.199 No, it really doesn't. The weak force is notoriously short range. 101 00:05:07.319 --> 00:05:09.759 I mean, for a neutrino to actually interact with another 102 00:05:09.839 --> 00:05:12.800 particle via the weak force, it essentially has to score 103 00:05:12.839 --> 00:05:15.360 a direct head on microscopic. 104 00:05:14.759 --> 00:05:17.000 Collision, like hitting a bulls eye on a darkboard that's 105 00:05:17.040 --> 00:05:17.680 a mile away. 106 00:05:17.759 --> 00:05:20.759 Smaller, it has to hit a quark inside a proton 107 00:05:20.839 --> 00:05:24.399 or a neutron. And because atoms are famously what ninety 108 00:05:24.480 --> 00:05:26.879 nine point nine nine nine nine nine percent empty space, 109 00:05:27.000 --> 00:05:29.680 the odds of that direct hit are astronomically low. 110 00:05:29.839 --> 00:05:32.600 I remember reading once that you could fire a neutrino 111 00:05:32.759 --> 00:05:35.399 through a block of solid lead a light year thick, 112 00:05:35.920 --> 00:05:38.040 and there's a very very good chance it just emerges 113 00:05:38.079 --> 00:05:38.959 completely untouched. 114 00:05:38.959 --> 00:05:41.279 On the other side, it's entirely possible. They are that 115 00:05:41.439 --> 00:05:42.240 non interactive. 116 00:05:42.279 --> 00:05:45.560 So this brings us to the characteristic that frankly completely 117 00:05:45.560 --> 00:05:49.279 breaks my intuition about this specific particle KM three two 118 00:05:49.319 --> 00:05:52.800 three zero two one three A. If a neutrino is 119 00:05:52.839 --> 00:05:55.959 just this ghostly non interacting point in space, how does 120 00:05:55.959 --> 00:05:58.720 it carry energy? Ah? Right, let's just look at the 121 00:05:58.800 --> 00:06:01.920 numbers for a second detection from February twenty twenty three 122 00:06:02.360 --> 00:06:05.879 was calculated at two hundred and twenty PEEDA paid electron volts. 123 00:06:06.800 --> 00:06:10.240 That is two hundred and twenty million billion electron volts. 124 00:06:10.279 --> 00:06:11.959 It's a staggering number, it is. 125 00:06:12.160 --> 00:06:14.920 And in classical physics, I mean, kinetic energy is basically 126 00:06:14.959 --> 00:06:18.319 mass in motion, right, A heavier object hits harder. But 127 00:06:18.360 --> 00:06:22.199 physicists spent decades thinking neutrino's had literally zero mass, and 128 00:06:22.279 --> 00:06:25.600 even today we know their mass is just infinitesimally. 129 00:06:24.800 --> 00:06:26.079 Small, practically zero. 130 00:06:26.240 --> 00:06:28.639 Right, So if you have almost zero mass. Where's that 131 00:06:28.680 --> 00:06:31.839 two hundred and twenty million billion electron volts actually being stored? 132 00:06:32.000 --> 00:06:34.120 It sounds like saying a literal speck of dust hit 133 00:06:34.199 --> 00:06:35.839 you with the force of a freight train. How do 134 00:06:35.879 --> 00:06:37.199 we even wrap our heads around that? 135 00:06:37.240 --> 00:06:39.680 Well, you are hitting on a fundamental disconnect between classical 136 00:06:39.680 --> 00:06:42.040 physics and relativity here. I mean, in high school physics, 137 00:06:42.079 --> 00:06:44.399 we are all taught the kinetic energy equation, right, one 138 00:06:44.480 --> 00:06:46.319 half mass times velocity squared. 139 00:06:46.519 --> 00:06:49.160 Yeah, that's the one where if his mass approaches zero, 140 00:06:49.199 --> 00:06:51.240 the energy should approve to zero exactly. 141 00:06:51.399 --> 00:06:54.439 But that equation is really just an approximation for things 142 00:06:54.480 --> 00:06:57.480 moving slowly. When you deal with the high energy universe, 143 00:06:57.519 --> 00:07:00.079 you have to throw that out and use Einstein's full 144 00:07:00.199 --> 00:07:01.360 energy momentum relation. 145 00:07:01.560 --> 00:07:05.480 Right, So everyone knows E equals mc squared. But that's 146 00:07:05.519 --> 00:07:06.759 not the whole equation. 147 00:07:06.480 --> 00:07:08.759 Is it. No, it isn't. The full equation is actually 148 00:07:09.000 --> 00:07:13.240 E squared equals pc squared plus mc squared squared. 149 00:07:13.360 --> 00:07:15.519 Okay, unpacking that a bit, So the P in. 150 00:07:15.439 --> 00:07:19.000 That equation stands for momentum. So a particle's total energy 151 00:07:19.079 --> 00:07:22.560 is actually a combination of its rest mass and its momentum. 152 00:07:22.639 --> 00:07:24.560 Oh, I see so for a heavy particle that's just 153 00:07:24.560 --> 00:07:27.199 sitting still, the momentum part is zero, and you just 154 00:07:27.199 --> 00:07:30.360 get the classic E equals mc square, Yes, exactly. 155 00:07:30.879 --> 00:07:34.759 But for a neutrino, the rest mass is so vanishingly 156 00:07:34.800 --> 00:07:37.720 small that the mc squared part of the equation is 157 00:07:37.759 --> 00:07:41.120 basically irrelevant. It drops away. Almost one hundred percent of 158 00:07:41.120 --> 00:07:43.360 its energy comes entirely from its momentum. 159 00:07:43.399 --> 00:07:46.560 Wow. So it's not hitting hard because it's heavy. It's 160 00:07:46.600 --> 00:07:49.600 hitting hard strictly because it has been accelerated to a 161 00:07:49.680 --> 00:07:52.680 velocity so incredibly close to the speed of light that 162 00:07:52.759 --> 00:07:55.319 its momentum approaches the macroscopic scale. 163 00:07:55.360 --> 00:08:00.240 It is a pure, concentrated bullet of relativistic momentum. And 164 00:08:00.279 --> 00:08:02.920 to put that two hundred and twenty Peavy into perspective, 165 00:08:03.040 --> 00:08:06.680 let's look at the most powerful machine humanity has ever built. 166 00:08:06.399 --> 00:08:08.680 The Large Hadron Collider in Switzerland. Right. 167 00:08:08.759 --> 00:08:12.839 The LHC is a twenty seven kilometer ring of superconducting 168 00:08:12.959 --> 00:08:16.879 magnets cooled to near absolute zero, designed to basically smash 169 00:08:16.920 --> 00:08:18.160 protons together, and. 170 00:08:18.120 --> 00:08:21.240 When it is running an absolute maximum capacity, it pushes 171 00:08:21.279 --> 00:08:24.319 particles to about what thirteen point six tarra electron volts, 172 00:08:24.399 --> 00:08:25.279 or a tav right. 173 00:08:25.199 --> 00:08:27.600 Now, yes, and a single tavy is often compared to 174 00:08:27.639 --> 00:08:30.720 the kinetic energy of a flying mostuito, okay, a mosquito. Now. 175 00:08:30.800 --> 00:08:33.399 Taking the macroscopic energy of a flying mosquito and cramming 176 00:08:33.440 --> 00:08:37.039 it into a single microscopic proton is an astonishing feat 177 00:08:37.080 --> 00:08:40.600 of human engineering. But the universe scales this up brutally. 178 00:08:40.279 --> 00:08:43.200 Because a ped electron volt is one thousand teo electron. 179 00:08:42.879 --> 00:08:46.000 Volts exactly, so one peavy is a thousand times more 180 00:08:46.120 --> 00:08:48.799 energetic than a mosquito. And km three two three zero 181 00:08:48.879 --> 00:08:51.240 two one three A was hearing two hundred and twenty 182 00:08:51.320 --> 00:08:52.240 of them, so it was. 183 00:08:52.200 --> 00:08:56.639 A single sytomic point carrying the physical kinetic force of 184 00:08:56.679 --> 00:08:57.440 a dropped brick. 185 00:08:57.600 --> 00:09:01.200 A dropped brick entirely contained within something smaller than an atom. 186 00:09:01.360 --> 00:09:03.759 That just stretches the limits of imagination. I mean, we 187 00:09:03.879 --> 00:09:07.279 are not generating anything close to that on Earth. We 188 00:09:07.320 --> 00:09:10.480 are maxing out around fourteen TV. This thing arrived at 189 00:09:10.480 --> 00:09:14.399 two hundred and twenty thousand TV. The machinery required to 190 00:09:14.440 --> 00:09:17.679 impart that kind of momentum to a particle just cannot 191 00:09:17.720 --> 00:09:18.679 be a quiet star. 192 00:09:18.879 --> 00:09:22.360 Now, it requires violence on a cosmic scale. When physicists 193 00:09:22.440 --> 00:09:24.759 look for the sources of pebby neutrinos. They are looking 194 00:09:24.799 --> 00:09:28.519 for engines of extreme gravity and magnetism like what well, 195 00:09:28.559 --> 00:09:31.440 they look at active galactic nuclei for one. These are 196 00:09:31.519 --> 00:09:34.600 super massive black holes at the centers of distant galaxies 197 00:09:34.600 --> 00:09:36.279 that are actively feeding on matter. 198 00:09:36.399 --> 00:09:39.159 Oh right, And as the gas and stars get shredded 199 00:09:39.200 --> 00:09:41.720 and pulled into the black hole, the magnetic fields get 200 00:09:41.759 --> 00:09:42.480 all twisted up. 201 00:09:42.480 --> 00:09:45.759 Ranks, extremely twisted. They form these massive relativistic jets that 202 00:09:45.840 --> 00:09:47.879 just shoot out from the poles at near light speed. 203 00:09:48.000 --> 00:09:50.720 So the magnetic fields around the black hole are essentially 204 00:09:50.759 --> 00:09:54.600 acting like the superconducting magnets in the LHC, but just 205 00:09:54.679 --> 00:09:55.840 on a scale of light years. 206 00:09:56.120 --> 00:09:59.720 The acceleration mechanics are very similar, but orders of magnitude 207 00:09:59.720 --> 00:10:03.440 more tents particles get trapped in the shockwaves of those jets, 208 00:10:03.759 --> 00:10:06.759 just bouncing back and forth across the magnetic boundaries. 209 00:10:06.360 --> 00:10:08.360 Gaining energy with every bound. 210 00:10:08.200 --> 00:10:11.639 Exactly until they are finally ejected out into the void. 211 00:10:12.440 --> 00:10:15.720 Or another option is we look at kilanovae. 212 00:10:16.360 --> 00:10:19.759 That's the catastrophic collision of two neutron stars. 213 00:10:19.440 --> 00:10:23.120 Right, Yes, the sheer density and the gravitational collapse of 214 00:10:23.120 --> 00:10:27.559 those events create magnetic fields trillions of times stronger than Earth's. 215 00:10:27.600 --> 00:10:31.519 I mean, these environments are the universe's natural particle accelerators. 216 00:10:31.960 --> 00:10:34.720 Okay, so that sets up the stakes perfectly. We know 217 00:10:34.799 --> 00:10:37.320 there are these apocalyptic engines out there in the deep 218 00:10:37.399 --> 00:10:41.159 universe spitting out these relativistic ghosts. And the ghost travels 219 00:10:41.159 --> 00:10:43.879 in a straight line for millions, billions of. 220 00:10:43.919 --> 00:10:45.399 Years, completely untouched. 221 00:10:45.600 --> 00:10:48.679 Right it enters our solar system, it approaches Earth. And 222 00:10:48.720 --> 00:10:51.639 this brings us back to the Kapplopasero site in the Mediterranean. 223 00:10:51.879 --> 00:10:54.679 Because if this particle passes right through planets, how did 224 00:10:54.679 --> 00:10:56.799 that grid of sensors at the bottom of the ocean 225 00:10:56.960 --> 00:10:57.879 actually catch it? 226 00:10:58.120 --> 00:10:59.840 That is the million dollar question. 227 00:11:00.080 --> 00:11:02.519 Let's dive into the mechanics of the underwater trap and 228 00:11:02.759 --> 00:11:04.559 you know the famous blue flash. 229 00:11:04.600 --> 00:11:08.919 Well, to detect a particle that refuses to interact with anything, 230 00:11:09.480 --> 00:11:12.440 you obviously cannot build a traditional telescope. You can't just 231 00:11:12.519 --> 00:11:14.279 point a glass lens at the sky. 232 00:11:14.320 --> 00:11:16.720 Right because it would just go right through the glass exactly. 233 00:11:16.840 --> 00:11:19.600 So you have to build a giant volume of target 234 00:11:19.639 --> 00:11:23.559 material and simply wait for a statistical miracle. You need 235 00:11:23.559 --> 00:11:26.679 a space where the ghost against all odds happens to 236 00:11:26.759 --> 00:11:29.080 hit the nucleus of an atom directly, and. 237 00:11:29.039 --> 00:11:32.080 The target material in this case is the entire Mediterranean Sea. 238 00:11:33.200 --> 00:11:35.279 But the immediate question that comes to my mind when 239 00:11:35.279 --> 00:11:37.879 looking at the cam through net project is the location. 240 00:11:38.320 --> 00:11:39.120 Why I put it there? 241 00:11:39.279 --> 00:11:42.879 Yeah? If I want to observe high energy cosmic phenomena, 242 00:11:43.320 --> 00:11:45.519 my instinct is to get as high up as possible, 243 00:11:45.679 --> 00:11:48.799 put a satellite in orbit, or build an observatory on 244 00:11:48.799 --> 00:11:52.399 a high altitude plateau in Chili. Why go three five 245 00:11:52.480 --> 00:11:55.840 hundred meters down under billions of gallons of salt water 246 00:11:56.039 --> 00:11:56.840 to look at the sky. 247 00:11:57.000 --> 00:11:59.639 It's a great question, and it's because the ocean isn't 248 00:11:59.639 --> 00:12:02.159 the lens of the telescope. The ocean is the shield. 249 00:12:02.240 --> 00:12:02.679 The shield. 250 00:12:02.799 --> 00:12:06.600 Yeah, the surface of the Earth is incredibly noisy from 251 00:12:06.639 --> 00:12:11.000 a particle physics perspective. I mean, we are constantly being 252 00:12:11.039 --> 00:12:16.200 bombarded by standard cosmic rays, protons, alpha particles, electrons. 253 00:12:15.679 --> 00:12:18.240 Right, and when these hit the upper atmosphere, they create 254 00:12:18.279 --> 00:12:21.600 a kind of chaotic shower of secondary particles that just 255 00:12:21.679 --> 00:12:23.320 rain down on the surface constantly. 256 00:12:23.519 --> 00:12:26.600 Exactly. So, if you put a sensitive and neutrino detector 257 00:12:26.639 --> 00:12:30.759 on a mountaintop, its sensors would be completely overwhelmed by 258 00:12:30.759 --> 00:12:31.919 this constant static. 259 00:12:32.039 --> 00:12:33.759 It would be like trying to listen for a pin 260 00:12:33.879 --> 00:12:36.919 drop while standing next to a jet engine. The signal 261 00:12:37.000 --> 00:12:39.559 of a single rare neutrino would just be totally lost 262 00:12:39.600 --> 00:12:40.639 in the background radiation. 263 00:12:40.759 --> 00:12:43.159 Precisely, so you have to bury the detector. And the 264 00:12:43.200 --> 00:12:46.399 further down you go, the more the surrounding matter filters 265 00:12:46.440 --> 00:12:50.120 out the noise. Kilometers of seawater provide an excellent dense 266 00:12:50.159 --> 00:12:52.679 barrier against all those standard cosmic rays. 267 00:12:52.799 --> 00:12:55.919 But wait, the Earth itself provides the ultimate filter, doesn't it, 268 00:12:55.960 --> 00:12:59.360 Because the CAM three net array is essentially looking down, 269 00:12:59.440 --> 00:12:59.919 not up. 270 00:13:00.120 --> 00:13:03.080 Yes, it uses the entire mass of the planet Earth 271 00:13:03.120 --> 00:13:05.919 as a shield to block everything coming from the other side. 272 00:13:06.080 --> 00:13:08.480 Because the only thing that can travel through the Earth 273 00:13:08.519 --> 00:13:12.320 from the opposite hemisphere and emerge into the Mediterranean Sea 274 00:13:12.360 --> 00:13:14.960 bed without being stopped is a neutrino. 275 00:13:14.759 --> 00:13:19.120 Exactly, So the detector just sits in the quiet, isolated dark, 276 00:13:19.559 --> 00:13:21.840 waiting for a neutrino to make that one in a 277 00:13:21.919 --> 00:13:25.399 trillion interaction via the weak nuclear force. 278 00:13:25.559 --> 00:13:29.440 Okay, let's mechanically unpack that interaction. Because the detector doesn't 279 00:13:29.440 --> 00:13:33.639 actually see the neutrino itself. Right, it sees the shrapnel. 280 00:13:33.240 --> 00:13:36.720 Yes, the shrapnel. The interaction itself is a really sudden, 281 00:13:36.840 --> 00:13:40.559 violent transformation. Remember, the neutrino is carrying two hundred and 282 00:13:40.639 --> 00:13:44.360 twenty pv of momentum. When it finally strikes a quark 283 00:13:44.519 --> 00:13:47.720 inside an oxygen or hydrogen nucleus in a water molecule, 284 00:13:48.080 --> 00:13:50.240 it initiates a weak foce exchange. 285 00:13:50.399 --> 00:13:54.720 Specifically, it exchanges a heavy unstable particle called w boson 286 00:13:54.840 --> 00:13:57.759 with the nucleus. This is the actual mechanism of the 287 00:13:57.759 --> 00:14:00.360 weak interaction. They're literally trading a particle. 288 00:14:00.159 --> 00:14:03.159 They are, and the result of that trade is fundamental transformation. 289 00:14:03.480 --> 00:14:06.120 The neutrino ceases to be a neutrino, Its energy and 290 00:14:06.159 --> 00:14:09.240 quantum numbers are transferred, and a new particle is created 291 00:14:09.279 --> 00:14:10.200 right there in its place. 292 00:14:10.519 --> 00:14:12.519 And in the case of KM three two three zero 293 00:14:12.519 --> 00:14:15.960 two one three A, the interaction produced a particle called a. 294 00:14:16.039 --> 00:14:18.600 Muon, exactly a muon. 295 00:14:18.240 --> 00:14:21.600 Which is essentially a much heavier, highly unstable cousin of 296 00:14:21.600 --> 00:14:22.159 the electron. 297 00:14:22.279 --> 00:14:26.159 Right. Yes, and crucially, unlike the neutrino, the muon actually 298 00:14:26.159 --> 00:14:30.039 carries an electrical charge. Furthermore, because of the laws of 299 00:14:30.039 --> 00:14:34.120 conservation of momentum, This newly born muon inherits a vast 300 00:14:34.159 --> 00:14:36.639 majority of that two hundred and twenty pev of energy. 301 00:14:36.720 --> 00:14:39.759 Oh wow, So you suddenly have a highly charged particle 302 00:14:40.000 --> 00:14:43.080 violently tearing through the water at a velocity so close 303 00:14:43.120 --> 00:14:45.080 to the speed of light in a vacuum that the 304 00:14:45.080 --> 00:14:46.159 difference is basically a. 305 00:14:46.080 --> 00:14:48.840 Marginal And this triggers the phenomenon that km three net 306 00:14:48.879 --> 00:14:52.080 is actually looking for care and copp radiation, the famous 307 00:14:52.120 --> 00:14:54.000 blue glow. I mean, you see this in pictures of 308 00:14:54.080 --> 00:14:57.480 underwater nuclear reactors, right, that eerie, vibrant blue light. Yes, 309 00:14:57.559 --> 00:15:01.120 But the mechanism behind that glow is why mildly counterintuitive 310 00:15:01.159 --> 00:15:03.759 to me. Yeah, it happens because the muon is moving 311 00:15:03.799 --> 00:15:06.960 through the water faster than light itself can move through 312 00:15:07.000 --> 00:15:07.320 the water. 313 00:15:07.480 --> 00:15:10.399 It is counterintuitive. The concept of moving faster than light 314 00:15:10.480 --> 00:15:12.919 often trips people up because of the hard cosmic speed 315 00:15:12.960 --> 00:15:14.360 limit that Einstein established. 316 00:15:14.519 --> 00:15:16.919 Right, nothing can go faster than the speed of light exactly. 317 00:15:17.080 --> 00:15:20.639 But Einstein's limit, which is roughly three hundred thousand kilometers 318 00:15:20.679 --> 00:15:22.879 per second, applies strictly to the speed of light in 319 00:15:22.919 --> 00:15:24.159 a perfect vacuum. 320 00:15:24.320 --> 00:15:25.120 Ah. 321 00:15:25.159 --> 00:15:28.799 When light enters a medium like glass or you know, water, 322 00:15:29.360 --> 00:15:32.399 it interacts with the electromagnetic fields of the atoms in 323 00:15:32.440 --> 00:15:36.639 that medium, and its propagation speed drops. In water, the 324 00:15:36.639 --> 00:15:38.960 phase velocity of light is only about two hundred and 325 00:15:39.039 --> 00:15:40.960 twenty five thousand kilometers per. 326 00:15:40.840 --> 00:15:44.200 Second, But our two hundred and twenty peavy muon doesn't 327 00:15:44.240 --> 00:15:46.440 care about the water's optical speed limit. It is being 328 00:15:46.440 --> 00:15:50.759 pushed by such immense relativistic momentum that it plows right 329 00:15:50.840 --> 00:15:53.080 through the water at two hundred and ninety nine thousand 330 00:15:53.120 --> 00:15:54.360 kilometers per second. 331 00:15:54.120 --> 00:15:57.039 So it is literally outpacing the local speed of light. 332 00:15:57.159 --> 00:15:59.720 It's blowing past it, and the physics of what happens 333 00:15:59.720 --> 00:16:04.120 next is beautifully violent. As this highly charged muon rips 334 00:16:04.159 --> 00:16:07.919 through the water molecules, its electromagnetic field forcefully pushes the 335 00:16:07.960 --> 00:16:10.960 electrons of the water molecules out of their stable orbits. 336 00:16:11.080 --> 00:16:15.039 It displaces them. It's physically shoving the localized electromagnetic field 337 00:16:15.200 --> 00:16:15.840 out of the way. 338 00:16:15.960 --> 00:16:18.960 It shoves them aside and then immediately passes by. But 339 00:16:19.080 --> 00:16:23.159 once the muon is gone, those displaced electrons violently snap 340 00:16:23.279 --> 00:16:26.639 back into their original stable positions. And when an electron 341 00:16:26.679 --> 00:16:29.799 snaps back to a lower energy state, it releases a 342 00:16:29.799 --> 00:16:30.519 photon a. 343 00:16:30.480 --> 00:16:33.600 Packet of light exactly. But if the muon was moving slowly, 344 00:16:34.159 --> 00:16:37.000 those photons would just randomly scatter, right, It would just 345 00:16:37.080 --> 00:16:38.840 be a faint, disorganized glow. 346 00:16:39.039 --> 00:16:41.639 It wouldn't even be a glow. If a particle moves 347 00:16:41.679 --> 00:16:44.200 slower than light. In that medium, the polarization of the 348 00:16:44.240 --> 00:16:49.080 molecules is symmetrical front and back. The electromagnetic disturbances cancel 349 00:16:49.120 --> 00:16:52.120 each other out, resulting in absolutely no net radiation. 350 00:16:52.360 --> 00:16:52.559 Oh. 351 00:16:52.600 --> 00:16:55.360 Interesting, But because the muon is moving faster than the 352 00:16:55.399 --> 00:16:59.240 emitted photons can travel away from it, the geometry changes completely. 353 00:17:00.000 --> 00:17:04.279 Polariation is asymmetrical. The photons being emitted as the electrons 354 00:17:04.319 --> 00:17:06.480 snap back, are forced to pile up on top of 355 00:17:06.519 --> 00:17:08.279 each other, constantly overlapping. 356 00:17:08.559 --> 00:17:11.400 Okay, so it is the exact same physics as a 357 00:17:11.480 --> 00:17:14.400 jet breaking the sound barrier, but just translated into the 358 00:17:14.440 --> 00:17:18.359 electromagnetic spectrum. Like a jet moves faster than the sound 359 00:17:18.440 --> 00:17:21.359 waves it creates, so the waves compress into a single 360 00:17:21.559 --> 00:17:24.000 massive acoustic shockwave a sonic boom. 361 00:17:24.119 --> 00:17:24.599 Exactly. 362 00:17:24.759 --> 00:17:27.160 The muon moves faster than the light waves it creates, 363 00:17:27.359 --> 00:17:30.200 forcing them to compress into an optical shockwave. 364 00:17:30.480 --> 00:17:32.319 That is a brilliant way to phrase it. And that 365 00:17:32.359 --> 00:17:35.279 optical shockwave takes the form of a cone of bluish 366 00:17:35.359 --> 00:17:38.960 lights spreading out behind the particle that is Scherenkov radiation, 367 00:17:39.440 --> 00:17:41.960 and that blue cone is the footprint that came. Three 368 00:17:42.000 --> 00:17:43.599 net sensors are waiting to catch. 369 00:17:43.720 --> 00:17:46.480 So let's picture the detector array again. We have these 370 00:17:46.559 --> 00:17:50.519 long vertical strings of spheres anchored to the seafloor. Inside 371 00:17:50.559 --> 00:17:53.960 each of those spheres are photomultiplier tubes. Yes, and these 372 00:17:53.960 --> 00:17:57.240 are instruments so incredibly sensitive they can literally detect a 373 00:17:57.279 --> 00:18:01.319 single individual photon of light hitting them in the pitch black. 374 00:18:01.519 --> 00:18:04.359 They are that sensitive. So as the muon streaks through 375 00:18:04.359 --> 00:18:07.440 the kilometer of water, the cone of blue light washes 376 00:18:07.480 --> 00:18:11.640 over the sensor grid. The photo multiplier tubes trigger recording 377 00:18:11.680 --> 00:18:15.119 the exact nanosecond the light hits them and the exact 378 00:18:15.160 --> 00:18:16.319 intensity of that light. 379 00:18:16.640 --> 00:18:21.319 And from those nanosecond time stamps you reconstruct reality. I mean, 380 00:18:21.640 --> 00:18:23.200 if a sensor on the left side of the grid 381 00:18:23.359 --> 00:18:25.799 registers a hit a tiny fraction of a second before 382 00:18:25.799 --> 00:18:27.960 a sensor on the right, you know the cone is 383 00:18:28.000 --> 00:18:28.720 moving left. 384 00:18:28.559 --> 00:18:31.759 To right exactly. By tracking the cascade of triggers across 385 00:18:31.799 --> 00:18:35.519 the three D volume, the computers rebuild the precise trajectory 386 00:18:35.519 --> 00:18:38.240 of the muon, and by measuring the total amount of 387 00:18:38.319 --> 00:18:40.880 light emitted, they calculate its total. 388 00:18:40.640 --> 00:18:42.680 Energy, which is how the researchers were able to trace 389 00:18:42.720 --> 00:18:45.000 the track of km three two three zero two or 390 00:18:45.079 --> 00:18:48.480 two a g and calculate that horrifying two twenty pv 391 00:18:48.799 --> 00:18:52.400 energy figure. They literally saw the optical sonic boom left 392 00:18:52.400 --> 00:18:54.759 by the shrapnel of a collision that was born millions 393 00:18:55.240 --> 00:18:56.319 or billions of years ago. 394 00:18:56.480 --> 00:18:56.960 It's incorrect. 395 00:18:57.079 --> 00:19:01.519 It is a profound sequence of events. Yessive cosmic accelerator 396 00:19:01.759 --> 00:19:05.640 fires an invisible ghost across the void. It ignores every 397 00:19:05.640 --> 00:19:10.279 physical obstacle, plummets into the Mediterranean, hits a single oxygen atom, 398 00:19:10.640 --> 00:19:13.160 and spawns a charge clone that rips through the water 399 00:19:13.279 --> 00:19:16.559 so fast it tears a literal wave of blue light into. 400 00:19:16.400 --> 00:19:19.079 Existence, and that light is caught by a deep sea 401 00:19:19.200 --> 00:19:21.920