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 --> 00:00:29.640 I want you to take a second and just look 8 00:00:29.679 --> 00:00:32.479 at the seemingly empty space between you and whatever device 9 00:00:32.479 --> 00:00:34.679 you're listening on right now. Just look at the air 10 00:00:35.240 --> 00:00:40.399 the gap. Does it look perfectly smooth, perfectly still? Because 11 00:00:40.600 --> 00:00:42.799 I mean, what if I told you that the very 12 00:00:42.840 --> 00:00:46.640 emptiness you are looking at, that sheer nothingness is secretly 13 00:00:46.679 --> 00:00:52.280 boiling and bubbling and violently churning on an incredibly microscopic level. 14 00:00:52.439 --> 00:00:52.799 It is. 15 00:00:53.359 --> 00:00:57.719 It's a profoundly unsettling thought. Honestly, we are entirely conditioned 16 00:00:57.719 --> 00:00:59.200 to rely on space being. 17 00:00:59.079 --> 00:01:00.359 Just that right space. 18 00:01:00.399 --> 00:01:03.159 This is an empty room, exactly, a completely empty quiet 19 00:01:03.200 --> 00:01:06.280 stage where the actual events of the universe simply play out. 20 00:01:06.480 --> 00:01:09.840 We treat nothingness as this passive backdrop. But the physics 21 00:01:09.840 --> 00:01:12.040 we're going to get into today suggests that quietness is 22 00:01:12.120 --> 00:01:13.840 almost certainly a massive. 23 00:01:13.519 --> 00:01:16.840 Illusion, and breaking that illusion is exactly our mission today. 24 00:01:17.159 --> 00:01:20.200 We are exploring a monumental breakthrough. From early April twenty 25 00:01:20.239 --> 00:01:22.560 twenty six, led by a team of physicists at the 26 00:01:22.640 --> 00:01:26.719 University of Warwick, they've produced this groundbreaking mathematical blueprint that 27 00:01:26.799 --> 00:01:30.519 might finally allow us to detect this churning emptiness right 28 00:01:30.519 --> 00:01:31.239 in the laboratory. 29 00:01:31.359 --> 00:01:34.519 Yeah, physicists called the quantum foam of the universe. 30 00:01:34.359 --> 00:01:37.480 The quantum foam, and if this team is right, their 31 00:01:37.519 --> 00:01:40.879 blueprint could be the key to bridging the absolute ultimate 32 00:01:40.959 --> 00:01:44.159 gap between quantum mechanics and general relativity. 33 00:01:44.439 --> 00:01:47.120 Okay, let's unpack this because we are talking about the 34 00:01:47.239 --> 00:01:48.599 single greatest clash. 35 00:01:48.280 --> 00:01:49.159 In modern physics. 36 00:01:49.959 --> 00:01:53.640 On one hand, you have Albert Einstein's general relativity, which 37 00:01:53.840 --> 00:01:55.280 works flawlessly for. 38 00:01:55.280 --> 00:01:57.560 The massive cosmos, flawlessly. 39 00:01:57.200 --> 00:02:00.599 Like it describes gravity as the actual warping of space 40 00:02:00.680 --> 00:02:04.120 and time. It dictates the spiral of galaxies, the crush 41 00:02:04.159 --> 00:02:07.239 of black holes, the orbit of the planet you are 42 00:02:07.280 --> 00:02:10.439 standing on. But on the other hand, you have quantum mechanics, 43 00:02:10.439 --> 00:02:14.879 which completely rules the subatomic world with probabilities and discrete jumps. 44 00:02:15.080 --> 00:02:15.240 Right. 45 00:02:15.479 --> 00:02:19.240 The problem is these two frameworks fundamentally refuse to play 46 00:02:19.319 --> 00:02:20.080 nicely together. 47 00:02:20.280 --> 00:02:22.919 What's fascinating here is that the root of this conflict 48 00:02:22.960 --> 00:02:27.240 comes down to the actual fabric of reality itself, the underlying. 49 00:02:26.800 --> 00:02:29.080 Geometry literal grid of the universe. 50 00:02:29.120 --> 00:02:32.400 Precisely when we use Einstein's models of gravity, the non 51 00:02:32.400 --> 00:02:35.919 negotiable assumption is that space time is a smooth, continuous sheet. 52 00:02:36.240 --> 00:02:39.039 You can zoom in forever and it remains perfectly smooth, 53 00:02:39.080 --> 00:02:42.319 like a perfectly stretched, infinitely thin sheet of rubber. Okay, 54 00:02:42.520 --> 00:02:46.319 but quantum mechanics operates on entirely different rules. It dictates 55 00:02:46.360 --> 00:02:49.919 that nothing can be perfectly smooth or perfectly certain. There 56 00:02:50.000 --> 00:02:53.919 is this inherent, inescapable fuzziness to the universe at the 57 00:02:53.960 --> 00:02:57.120 smallest levels. So quantum mechanics suggests that if you zoom 58 00:02:57.159 --> 00:03:00.000 in far enough on that rubber sheet, it stops being small, 59 00:03:00.879 --> 00:03:04.840 the geometry itself starts to jitter. There are constant, random, 60 00:03:05.039 --> 00:03:08.680 fluctuating distortions in the very makeup of space and time. 61 00:03:09.039 --> 00:03:12.080 Wow. And to really grasp how we are hunting for 62 00:03:12.120 --> 00:03:15.039 these space time fluctuations today, we have to look back 63 00:03:15.080 --> 00:03:18.520 at where this mind bending concept actually came from, and 64 00:03:18.560 --> 00:03:21.039 we have to go back to the nineteen fifties, specifically 65 00:03:21.120 --> 00:03:23.280 to the visionary physicist John Archibald Wheeler. 66 00:03:23.319 --> 00:03:26.800 Oh absolutely, Wheeler was the one who first proposed this concept. 67 00:03:26.960 --> 00:03:28.800 He's the guy who coined the term quantum fone. 68 00:03:28.919 --> 00:03:32.599 Wheeler essentially asked a very simple but like dangerous question, 69 00:03:32.879 --> 00:03:37.280 what happens if we apply quantum uncertainty to Einstein's smooth space? 70 00:03:37.800 --> 00:03:40.879 And he realized that at a certain microscopic threshold, the 71 00:03:40.960 --> 00:03:43.479 smooth picture of gravity simply has to break down, it 72 00:03:43.479 --> 00:03:46.599 has to surrender to quantum chaos. And that threshold is 73 00:03:46.599 --> 00:03:48.960 what we call the plank scale. Let's give some context 74 00:03:48.960 --> 00:03:51.479 for the plank scale, because the numbers are almost comical. 75 00:03:52.159 --> 00:03:55.039 We're talking about distances on the order of ten to 76 00:03:55.080 --> 00:03:58.639 the power of negative thirty five meters. Just to visualize that, 77 00:03:59.120 --> 00:04:01.280 if a single add was somehow blown up to be 78 00:04:01.319 --> 00:04:04.599 the size the entire visible universe, the plank length would 79 00:04:04.639 --> 00:04:06.520 be roughly the height of an average tree. 80 00:04:06.599 --> 00:04:09.879 That really puts it into perspective. It's unfathomably small, right, 81 00:04:10.159 --> 00:04:14.479 And the time scales are equally incomprehensible. We're talking around 82 00:04:14.680 --> 00:04:17.319 ten to the power of negative forty three seconds, which 83 00:04:17.360 --> 00:04:19.839 is essentially the time it takes light to travel that 84 00:04:19.839 --> 00:04:24.519 single plank length. At those scales, Wheeler theorized that quantum 85 00:04:24.560 --> 00:04:29.240 uncertainties cause space and time to literally warp, tear, bubble, and. 86 00:04:29.199 --> 00:04:32.079 Fluctuate, like time might not flow in a straat air exactly. 87 00:04:32.279 --> 00:04:36.279 Time gets messy. The physical distance between two microscopic points 88 00:04:36.360 --> 00:04:37.879 might constantly shift and shutter. 89 00:04:38.120 --> 00:04:40.560 So we have this nineteen fifties concept. But this isn't 90 00:04:40.600 --> 00:04:44.040 just an old thought experiment, right. The quantum foam naturally 91 00:04:44.079 --> 00:04:48.199 emerges in almost every modern attempt we have to quantize gravity. 92 00:04:48.720 --> 00:04:51.399 I mean, whether physicists are working on string theory or 93 00:04:51.439 --> 00:04:54.759 loop quantum gravity or causal set theory, they all eventually 94 00:04:54.879 --> 00:04:56.680 hit this boiling turbulence. 95 00:04:56.959 --> 00:04:59.920 They do, though you know, they approach the bubbling differently. 96 00:05:00.160 --> 00:05:04.759 String theory, for instance, replaces point particles with tiny vibrating strings, 97 00:05:05.040 --> 00:05:08.000 and the geometry of space gets incredibly complex at those 98 00:05:08.000 --> 00:05:12.560 microscopic scales. Loop quantum gravity suggests that space itself isn't 99 00:05:12.560 --> 00:05:16.680 a continuous sheet at all, but rather made of tiny, discrete, 100 00:05:16.879 --> 00:05:19.920 finite loops woven together like a chain mail shirt. 101 00:05:20.000 --> 00:05:21.839 A chain mail shirt. That's a great image. 102 00:05:21.959 --> 00:05:24.600 Yeah. And then causal set theory proposes that space time 103 00:05:24.639 --> 00:05:27.800 is fundamentally discrete, almost like pixels on a television screen. 104 00:05:28.160 --> 00:05:31.120 But the common denominator across all of these incredibly dense 105 00:05:31.279 --> 00:05:34.560 mathematical models is that space time is not a quiet void. 106 00:05:34.920 --> 00:05:37.560 It's dynamic. It is incredibly pergulent. 107 00:05:38.000 --> 00:05:39.879 And think of it like looking at the ocean from 108 00:05:39.920 --> 00:05:43.240 an airplane cruising at thirty thousand feet from way up 109 00:05:43.240 --> 00:05:46.480 there in the sky, the water looks like a perfectly serene, 110 00:05:47.040 --> 00:05:51.600 completely smooth sheet of glass. That is relativity. That is 111 00:05:51.680 --> 00:05:54.879 us looking at the universe from our massive human. 112 00:05:54.639 --> 00:05:55.360 Scale, right. 113 00:05:55.879 --> 00:05:57.639 But if you were dropped out of that plane and 114 00:05:57.680 --> 00:06:00.000 you're floating right on the surface of that exact same 115 00:06:00.120 --> 00:06:04.279 motion in a tiny raft, you aren't experiencing smooth glass. 116 00:06:04.360 --> 00:06:08.120 You're getting violently tossed around by chaotic waves, crashing water 117 00:06:08.199 --> 00:06:11.319 and bubbling foam. That is the quantum level. 118 00:06:11.519 --> 00:06:13.480 I really like that analogy, but we kind of have 119 00:06:13.519 --> 00:06:15.720 to push it one step further to really. 120 00:06:15.439 --> 00:06:16.279 Capture the physics. 121 00:06:16.279 --> 00:06:17.000 Okay, push it. 122 00:06:17.800 --> 00:06:20.120 So in the ocean, the waves are made of water 123 00:06:20.160 --> 00:06:23.680 molecules splashing around inside space. But in our universe, the 124 00:06:23.800 --> 00:06:28.120 quantum foam means that the underlying space itself is what's splashing. Whoa, Yeah, 125 00:06:28.439 --> 00:06:31.319 the grid lines of reality are bending. And what is 126 00:06:31.360 --> 00:06:34.240 crucial to understand is that in these modern models, gravity 127 00:06:34.279 --> 00:06:37.399 isn't just some classical predictable force holding planets in orbit. 128 00:06:37.920 --> 00:06:41.920 It is fundamentally influenced by these minute stochastic distortions. 129 00:06:42.160 --> 00:06:45.439 I want to pause on that word stochastic. That just 130 00:06:45.519 --> 00:06:49.000 means fundamentally random, unpredictable variations. 131 00:06:49.079 --> 00:06:49.279 Right. 132 00:06:49.399 --> 00:06:53.839 Yes, the quantum foam essentially creates a permanent background noise 133 00:06:54.040 --> 00:06:58.079 of stochastic distortions that alters the geometry of the universe 134 00:06:58.120 --> 00:06:59.079 from moment to moment. 135 00:06:59.800 --> 00:07:04.040 Okay, if Wheeler proposed this quantum foam over seventy years ago, 136 00:07:04.399 --> 00:07:06.800 and it's a mandatory feature of our best theories of 137 00:07:06.839 --> 00:07:10.040 the universe, why haven't we found it? I mean, think 138 00:07:10.040 --> 00:07:13.759 about our technological timeline. We've split the atom, we've photographed 139 00:07:13.800 --> 00:07:16.800 the event horizon of black holes, we've mapped the human genome. 140 00:07:17.120 --> 00:07:19.480 Why is the foam still hiding from us in twenty 141 00:07:19.519 --> 00:07:20.079 twenty six. 142 00:07:20.319 --> 00:07:23.480 Well, because experimental physicists have essentially been trapped in a 143 00:07:23.560 --> 00:07:27.720 nightmare scenario for decades. They had absolutely no unified target 144 00:07:27.720 --> 00:07:30.800 to aim for. The theoretical physics community just could not 145 00:07:30.920 --> 00:07:33.319 agree on what the quantum foam should actually look like 146 00:07:33.360 --> 00:07:34.319 when it hits a detector. 147 00:07:34.399 --> 00:07:37.439 Wait, so theoretical physicists have just been handing the experimentalists 148 00:07:37.480 --> 00:07:39.000 a bunch of conflicting treasure maps. 149 00:07:39.040 --> 00:07:39.519 Way much. 150 00:07:39.560 --> 00:07:41.920 How is an engineer supposed to build a billion dollar 151 00:07:42.000 --> 00:07:45.439 machine to find a signal when the theorists can't even 152 00:07:45.439 --> 00:07:47.639 agree on what the signal looks like or if it's 153 00:07:47.680 --> 00:07:49.560 a beat bahammer a flash. 154 00:07:49.360 --> 00:07:52.319 That is precisely the blockade that stalled the field. And 155 00:07:52.360 --> 00:07:56.040 this is exactly the issue highlighted by doctor Shermila Bellamurgan, 156 00:07:56.120 --> 00:07:59.560 an assistant professor at the University of Warwick. The theories 157 00:07:59.600 --> 00:08:02.879 were just incredibly fragmented. How so, Well, if you look 158 00:08:02.879 --> 00:08:06.360 at certain string theory models, they might predict fluctuations that 159 00:08:06.399 --> 00:08:09.759 are highly correlated, meaning a ripple in the foam here 160 00:08:09.920 --> 00:08:12.040 is strongly connected to a ripple in the comb a 161 00:08:12.040 --> 00:08:14.720 few meters away. Okay, but if you look at certain 162 00:08:14.800 --> 00:08:19.040 semi classical gravity models, which try to mix quantum fields 163 00:08:19.040 --> 00:08:22.079 with classical gravity in a very specific way, they might 164 00:08:22.120 --> 00:08:26.759 predict completely uncorrelated, rapidly decaying bursts of noise. 165 00:08:27.000 --> 00:08:30.560 So if the fluctuations act like a subtle background noise 166 00:08:30.600 --> 00:08:33.240 in our precision measurements. But you don't know what kind 167 00:08:33.240 --> 00:08:35.480 of noise to isolate. You just end up staring at 168 00:08:35.519 --> 00:08:38.039 a wall of static. You wouldn't know discovery if it 169 00:08:38.080 --> 00:08:39.799 was screaming at you exactly. 170 00:08:39.840 --> 00:08:43.080 You just assume your laser was miscalibrated, or you know, 171 00:08:43.159 --> 00:08:46.080 a truck drove by outside the laboratory and shook the mirror. 172 00:08:46.679 --> 00:08:51.440 Doctor Ballamergan pointed out that these abstract, siloed theoretical predictions 173 00:08:51.879 --> 00:08:55.279 left the people actually building the instruments completely in the dark. 174 00:08:55.480 --> 00:08:59.519 Here's where it gets really interesting. That exact frustration, the 175 00:08:59.600 --> 00:09:03.639 lack of a clear, unified mathematical target, is what the 176 00:09:03.759 --> 00:09:07.679 University of WARCLID team finally solved this year. They took 177 00:09:07.840 --> 00:09:11.559 all of these messy, conflicting, highly abstract theories of quantum 178 00:09:11.639 --> 00:09:16.559 gravity and they distilled them into a rigorous, testable mathematical framework. 179 00:09:16.679 --> 00:09:17.200 Yes, they did. 180 00:09:17.399 --> 00:09:21.759 They systematically sorted these microscopic space time fluctuations into three 181 00:09:21.879 --> 00:09:25.759 broad categories based on their space and time correlations. 182 00:09:25.120 --> 00:09:28.159 And understanding the mechanism behind these three categories is the 183 00:09:28.200 --> 00:09:31.440 absolute key to this entire breakthrough. The first category they 184 00:09:31.519 --> 00:09:34.039 identified is uncorrelated fluctuations. 185 00:09:34.080 --> 00:09:36.480 You can think of these as white noise, likelus pure noise. 186 00:09:36.799 --> 00:09:40.519 Yeah, they are the most chaotic, with minimal spatial or 187 00:09:40.519 --> 00:09:44.679 temporal correlations. What that means physically is that space time 188 00:09:44.759 --> 00:09:49.519 is boiling independently at every single point and every single microsecond. 189 00:09:49.799 --> 00:09:52.919 What happens at point A has zero memory or connection 190 00:09:53.039 --> 00:09:55.279 to what happens at point B, even if it's just 191 00:09:55.320 --> 00:09:56.759 a fraction of a millimeter away. 192 00:09:57.000 --> 00:09:59.679 To picture that, think of category one like the sheer 193 00:10:00.039 --> 00:10:05.120 DM static on an untuned radio, just harsh, unpredictable broadband hissing. 194 00:10:05.279 --> 00:10:09.960 Let's move to the second category, partially correlated or colored fluctuations. 195 00:10:10.480 --> 00:10:14.360 In this scenario, the space time fluctuations show moderate organization. 196 00:10:14.759 --> 00:10:17.679 They might be correlated over certain specific length scales or 197 00:10:17.720 --> 00:10:18.399 time scales. 198 00:10:18.440 --> 00:10:19.919 This is not totally random, right. 199 00:10:20.240 --> 00:10:23.840 This often arises from specific quantum gravity mechanisms where the 200 00:10:23.840 --> 00:10:26.600 effects of the foam propagate through space in a damped 201 00:10:26.679 --> 00:10:29.600 or filtered manner, Meaning a bubble pops here and its 202 00:10:29.679 --> 00:10:32.919 energy ripples outward but gets absorbed or altered as it travels. 203 00:10:33.080 --> 00:10:36.000 Following the audio analogy, category two is like hearing a 204 00:10:36.080 --> 00:10:40.080 muffled rhythmic bass line thumping through a thick apartment wall. 205 00:10:40.639 --> 00:10:43.200 You can't hear the full complexity of music, but you 206 00:10:43.200 --> 00:10:47.320 can detect a clear, repeating, organized pattern punching. 207 00:10:46.960 --> 00:10:47.600 Through the noise. 208 00:10:47.799 --> 00:10:51.840 That bass line comparison is highly accurate for the physics involved, actually, 209 00:10:51.879 --> 00:10:55.639 because it produces characteristic power spectra in the data. Just 210 00:10:55.679 --> 00:10:58.360 like a bass line produces a specific frequency peak on 211 00:10:58.399 --> 00:11:03.720 an audio equalizer, colored fluctuations produce a distinct mathematical. 212 00:11:03.000 --> 00:11:04.519 Signature that makes a lot of sense. 213 00:11:04.720 --> 00:11:09.600 And finally, the third category is highly correlated or coherent fluctuations. 214 00:11:10.039 --> 00:11:14.000 These exhibit profound organization. We are talking about long range 215 00:11:14.080 --> 00:11:18.799 spatial correlations or persistent temporal patterns. In fact, these fluctuations 216 00:11:18.799 --> 00:11:21.399 are so deeply organized that they might even mimic low 217 00:11:21.480 --> 00:11:25.759 frequency gravitational waves or massive collective quantum effects. 218 00:11:25.799 --> 00:11:28.759 And that third category is like hearing a clear, persistent melody. 219 00:11:28.960 --> 00:11:31.279 It cuts right through the ambient noise of the universe, 220 00:11:31.559 --> 00:11:34.559 unmistakable and highly structures. So we have our static, our 221 00:11:34.639 --> 00:11:36.639 bass line, and our melody. 222 00:11:36.679 --> 00:11:39.360 If we connect this to the bigger picture, the sheer 223 00:11:39.519 --> 00:11:42.799 brilliance of the Warwick team's work isn't just describing these 224 00:11:42.840 --> 00:11:49.000 three categories conceptually, they derived precise, exhaustive mathematical mappings. 225 00:11:48.519 --> 00:11:51.200 For each one the actual blueprints exactly. 226 00:11:51.559 --> 00:11:55.559 They calculated exactly how these three specific types of quantum 227 00:11:55.559 --> 00:11:59.559 fluctuations would alter the physical properties of laser light, specifically, 228 00:12:00.039 --> 00:12:03.120 how the phone would shift the phase, the amplitude, or 229 00:12:03.159 --> 00:12:06.080 the arrival timing of a photon. Because when you're trying 230 00:12:06.080 --> 00:12:08.360 to measure something at the Plank scale, you can't use 231 00:12:08.399 --> 00:12:11.799 a ruler. You are ultimately looking at how light travels 232 00:12:11.799 --> 00:12:13.039 through that bubbling space. 233 00:12:13.279 --> 00:12:15.639 That is the crucial pivot of this whole discussion. We 234 00:12:15.759 --> 00:12:19.320 finally have the blueprints. The experimentalists know what the static, 235 00:12:19.360 --> 00:12:21.960 the baseline, and the melody actually look like in the math. 236 00:12:22.600 --> 00:12:25.360 But that brings up the obvious next question, what physical 237 00:12:25.360 --> 00:12:27.759 instruments are we actually using to listen to the bubbling 238 00:12:27.759 --> 00:12:28.360 of the universe. 239 00:12:28.519 --> 00:12:30.200 We use laser interferometers. 240 00:12:30.480 --> 00:12:33.399 Let's really break down how an interferometer works, because it 241 00:12:33.440 --> 00:12:36.679 sounds incredibly intimidating, but the concept is actually quite elegant. 242 00:12:37.159 --> 00:12:41.360 Imagine a perfectly synchronized marching band walking down a street. Okay, 243 00:12:41.639 --> 00:12:45.519 at an intersection, the band splits perfectly in half. One 244 00:12:45.559 --> 00:12:48.759 half marches straight ahead, the other half turns ninety degrees 245 00:12:49.039 --> 00:12:51.679 and marches down the cross street. They march at the 246 00:12:51.759 --> 00:12:55.200 exact same distance. They turn around, and they march back 247 00:12:55.240 --> 00:12:56.799 to the intersection to recombine. 248 00:12:57.200 --> 00:12:57.639 And if the. 249 00:12:57.559 --> 00:13:00.399 Streets are perfectly smooth and they marched at the exact 250 00:13:00.440 --> 00:13:04.000 same pace, they will merge back together at the intersection 251 00:13:04.159 --> 00:13:08.600 in flawless formation. Their footsteps will be perfectly synchronized. 252 00:13:09.200 --> 00:13:11.600 But if the street one half of the band walked 253 00:13:11.639 --> 00:13:16.480 on was secretly bubbling, shifting and stretching even slightly, those 254 00:13:16.519 --> 00:13:20.120 marchers would get jostled, their strides would be uneven. When 255 00:13:20.159 --> 00:13:22.600 they finally returned to the intersection, they would be out 256 00:13:22.600 --> 00:13:24.039 of step with the other half of the band. 257 00:13:24.320 --> 00:13:27.440 That is exactly what an interferometer does with light. It 258 00:13:27.480 --> 00:13:30.360 takes a single laser beam, splits it in two, and 259 00:13:30.440 --> 00:13:34.360 sends those beams down perpendicular vacuum tubes, which we call arms. 260 00:13:34.960 --> 00:13:36.759 The light bounces off mirrors at the end of the 261 00:13:36.840 --> 00:13:38.519 arms and recombines at the center. 262 00:13:39.000 --> 00:13:40.879 And if space is bubbling, well, if. 263 00:13:40.799 --> 00:13:44.360 The fundamental fabric of spacetime itself stretches or compresses even 264 00:13:44.360 --> 00:13:47.159 a fraction of a proton's width while the light is traveling, 265 00:13:47.440 --> 00:13:50.480 the recombined laser beams will be out of step. Their 266 00:13:50.559 --> 00:13:53.399 light waves will interfere with each other differently, shifting the 267 00:13:53.399 --> 00:13:54.840 pattern we see on the detector. 268 00:13:55.399 --> 00:13:57.759 And when we talk about these laser interferometers, there are 269 00:13:57.799 --> 00:14:01.000 basically two weight classes in this hunt, the Goliaths and 270 00:14:01.039 --> 00:14:05.840 the David's. The goliath, famously is LIGO, the laser interferometer 271 00:14:05.919 --> 00:14:09.639 gravitational wave observatory in the United States. We're talking about 272 00:14:09.879 --> 00:14:16.200 four kilometer long concrete vacuum tubes stretching across the desert landscape. 273 00:14:16.360 --> 00:14:19.519 LIGO is an absolute marvel of modern engineering. Because its 274 00:14:19.600 --> 00:14:23.039 arms are four kilometers long, the light travels a massive distance, 275 00:14:23.120 --> 00:14:26.720 making the instrument unimaginably sensitive to very low strains in 276 00:14:26.759 --> 00:14:30.440 space time. The Warwick framework notes that LIGO excels as 277 00:14:30.480 --> 00:14:33.000 a binary yes or no detector for the existence of 278 00:14:33.039 --> 00:14:37.080 certain space time fluctuations. Its extreme sensitivity makes it ideal 279 00:14:37.120 --> 00:14:41.639 for confirming whether Category three, those highly correlated melody like 280 00:14:41.720 --> 00:14:43.720 coherent fluctuations are present. 281 00:14:44.080 --> 00:14:48.360 But wait, if LEGO is a four kilometer long hypersensitive giant, 282 00:14:48.879 --> 00:14:51.840 why hasn't it found the foam yet? It detects black 283 00:14:51.879 --> 00:14:55.120 holes colliding billions of light years away, surely it could 284 00:14:55.159 --> 00:14:57.679 detect the space inside its own tubes boiling. 285 00:14:58.080 --> 00:15:00.919 You would think so, But Ligo's mass of size is 286 00:15:00.960 --> 00:15:03.960 actually is fatal flaw when it comes to hunting quantum foam. 287 00:15:04.159 --> 00:15:05.399 Let me see if I can deduce this. 288 00:15:05.840 --> 00:15:08.639 If the arms are four kilometers long, the light has 289 00:15:08.679 --> 00:15:11.159 to bounce back and forth inside those tubes for a 290 00:15:11.240 --> 00:15:15.559 relatively long time. But the quantum foam is boiling millions 291 00:15:15.639 --> 00:15:18.600 or billions of times a second. Right, So while the 292 00:15:18.679 --> 00:15:21.360 light is traveling that huge distance, isn't it just passing 293 00:15:21.399 --> 00:15:24.519 through millions of different bubbles? Doesn't the sheer scale of 294 00:15:24.559 --> 00:15:28.440 the four kilometer trip just average out all that microscopic chaos. 295 00:15:28.480 --> 00:15:31.480 That is an excellent deduction. Yes, The long arm cavities 296 00:15:31.519 --> 00:15:35.360 introduce specific filtering effects. In engineering terms, Ligo acts as 297 00:15:35.399 --> 00:15:38.480 a low pass filter. The long travel time literally washes 298 00:15:38.519 --> 00:15:39.879 out the high frequency jitters. 299 00:15:40.000 --> 00:15:40.320 Wow. 300 00:15:40.559 --> 00:15:44.440 So while Lego is perfectly tuned for the slow, massive, 301 00:15:44.519 --> 00:15:48.799 low frequency ripples of colliding black holes, the rapid high 302 00:15:48.799 --> 00:15:52.679 frequency bubbling of the quantum foam simply slips right past it, 303 00:15:52.799 --> 00:15:54.399 completely smoothed out. 304 00:15:54.240 --> 00:15:56.279 In the data, which brings us to the Davids in 305 00:15:56.320 --> 00:16:01.879 this story. The tabletop interferometers specifically instruments currently coming online 306 00:16:01.919 --> 00:16:04.960 like Quest at Cardiff University in the UK and GQUEST 307 00:16:05.039 --> 00:16:08.200 at Celtic in the US. These devices don't have four 308 00:16:08.279 --> 00:16:10.720 kilometer arms. Their arms are only a few meters long. 309 00:16:11.120 --> 00:16:15.159 They literally fit inside a single standard laboratory room they do. 310 00:16:15.720 --> 00:16:17.840 Let me pause you right here, though, are you telling 311 00:16:17.879 --> 00:16:20.759 me that a tiny tabletop device in a university basement 312 00:16:21.120 --> 00:16:25.240 might actually outperform a multi billion dollar four kilometer giant 313 00:16:25.480 --> 00:16:27.519 in unlocking the deepest mystery in physics? 314 00:16:27.600 --> 00:16:30.720 It sounds completely counterintuitive, I know, but the mathematics and 315 00:16:30.759 --> 00:16:34.279 the Warwick study conclude exactly that because these tabletop devices 316 00:16:34.320 --> 00:16:37.120 are physically smaller, the light spends far less time in 317 00:16:37.159 --> 00:16:37.960 the arms. 318 00:16:37.759 --> 00:16:39.200 So no low pass filter effect. 319 00:16:39.559 --> 00:16:40.159 Exactly. 320 00:16:40.519 --> 00:16:42.679 That means they do not suffer from the low pass 321 00:16:42.679 --> 00:16:47.720 filtering effect LEGO does. They possess a much broader frequency bandwidth. 322 00:16:47.960 --> 00:16:51.799 They can actively monitor fluctuations happening millions of times a second, 323 00:16:52.159 --> 00:16:55.799 pushing up into the megahertz ranges. This allows them to 324 00:16:55.840 --> 00:17:00.480 capture all three of the Warwick framework's characteristic signatures, including 325 00:17:00.679 --> 00:17:04.640 the rapid violent white noise static of category one, much 326 00:17:04.680 --> 00:17:07.720 more comprehensively than LEGO ever could. 327 00:17:07.440 --> 00:17:07.960 But hold on. 328 00:17:08.079 --> 00:17:10.839 The whole reason Lego is four kilometers long is to 329 00:17:10.880 --> 00:17:14.799 achieve its mind bending sensitivity. If you shrink an interferometer 330 00:17:14.880 --> 00:17:17.559 down to three or four meters, the laser being barely 331 00:17:17.599 --> 00:17:21.319 travels anywhere, don't you completely lose the precision required to 332 00:17:21.359 --> 00:17:23.759 measure a shift the size of a proton. 333 00:17:24.079 --> 00:17:27.079 If you are using traditional classical optics, yes, you absolutely 334 00:17:27.079 --> 00:17:30.759 would lose that precision. But the tabletop interferometers are packed 335 00:17:30.759 --> 00:17:33.599 with advanced quantum technologies. To make up for their size. 336 00:17:33.799 --> 00:17:37.640 They utilize sophisticated photon counting and a highly counterintuitive technique 337 00:17:37.640 --> 00:17:38.720 called quantum squeezing. 338 00:17:38.880 --> 00:17:42.000 Okay, quantum squeezing. I hear this term thrown around constantly 339 00:17:42.000 --> 00:17:44.519 in physics news. Can we break down the actual mechanism 340 00:17:44.559 --> 00:17:45.440 of how you squeeze light? 341 00:17:45.680 --> 00:17:48.759 To understand squeezing, we have to talk about the Heisenberg 342 00:17:48.880 --> 00:17:53.359 uncertainty principle. Heisenberg proved that there is a fundamental, hard 343 00:17:53.400 --> 00:17:55.640 coded limit to how much we can know about a 344 00:17:55.720 --> 00:17:56.519 quantum system. 345 00:17:56.720 --> 00:17:57.960 Right, the uncertainty principle. 346 00:17:58.119 --> 00:18:02.720 Yes, you cannot simletaneously know a photon's exact phase, where 347 00:18:02.720 --> 00:18:05.799 it is in its wave cycle, and its exact amplitude, 348 00:18:05.920 --> 00:18:09.279 which is its intensity, there will always be a baseline 349 00:18:09.400 --> 00:18:13.880 level of quantum fuzziness. This absolute limit of precision is 350 00:18:13.920 --> 00:18:15.759 called the standard quantum limit. 351 00:18:15.960 --> 00:18:16.720 So even if your. 352 00:18:16.640 --> 00:18:19.680 Mirrors are perfectly still and your laser is perfectly tuned, 353 00:18:20.119 --> 00:18:22.400 the light itself is inherently a little bit blurry just 354 00:18:22.400 --> 00:18:23.640 by existing exactly. 355 00:18:24.200 --> 00:18:27.880 But researchers realize they could exploit a loophole in Heisenberg's rule. 356 00:18:28.400 --> 00:18:30.519 Imagine the total uncertainty of the light. 357 00:18:30.400 --> 00:18:31.000 As a balloon. 358 00:18:32.000 --> 00:18:34.279 Heisenberg says the balloon must always have a certain volume 359 00:18:34.319 --> 00:18:36.599 of air in it, a certain amount of total uncertainty. 360 00:18:36.720 --> 00:18:39.519 You can't deflate the balloon, but he didn't say you 361 00:18:39.519 --> 00:18:40.599 couldn't change its shape. 362 00:18:40.799 --> 00:18:43.359 Uh So, if you take your hands and physically squeeze 363 00:18:43.359 --> 00:18:45.680 the middle of the balloon, making it incredibly narrow in 364 00:18:45.720 --> 00:18:48.160 one direction, the air has to go somewhere else it 365 00:18:48.240 --> 00:18:49.799 bulges out at the top and bottom. 366 00:18:49.880 --> 00:18:54.319 That is quantum squeezing. Researchers use specialized crystals to alter 367 00:18:54.440 --> 00:18:58.039 the quantum state of the laser beam. They basically squeeze 368 00:18:58.039 --> 00:19:00.359 the balloon to make the uncertainty in the la lights 369 00:19:00.359 --> 00:19:06.000 phase unbelievably tiny hyper precise. But the trade off is 370 00:19:06.000 --> 00:19:08.920 that the uncertainty in the light's amplitude bulges out and 371 00:19:08.960 --> 00:19:10.759 becomes incredibly blurry. 372 00:19:11.000 --> 00:19:14.039 But because an interferometer only cares about measuring the phase 373 00:19:14.079 --> 00:19:16.440 of the light, when those marching bands come back together, 374 00:19:16.839 --> 00:19:20.000 it doesn't matter if the amplitude is blurry. You've effectively 375 00:19:20.160 --> 00:19:23.599 cheated the universe's precision limit for the one specific trait 376 00:19:23.640 --> 00:19:24.799 you actually need to measure. 377 00:19:25.000 --> 00:19:27.920 You've nailed it by using these squeezed states of light. 378 00:19:28.319 --> 00:19:32.559 These three meter tabletop interferometers become hyper sensitive, and because 379 00:19:32.559 --> 00:19:34.839 of their broad bandwidth, they don't just act as a 380 00:19:34.839 --> 00:19:37.839 binary yes or no detector for the quantum foam. They 381 00:19:37.880 --> 00:19:41.839 provide incredibly rich detailed information about the physical nature of 382 00:19:41.880 --> 00:19:42.960 the fluctuations, so. 383 00:19:42.880 --> 00:19:45.400 They can actually categorize what they are hearing. They can 384 00:19:45.440 --> 00:19:48.079 tell us if the universe is playing static, a bass line, 385 00:19:48.160 --> 00:19:48.720 or a melody. 386 00:19:48.880 --> 00:19:52.279 Doctor Sander Vermullin from Caltech made a brilliant point regarding 387 00:19:52.319 --> 00:19:56.599 this exact dynamic. He noted that while interferometers have historically 388 00:19:56.640 --> 00:19:59.880 been able to measure space time with extraordinary precision, that 389 00:20:00.119 --> 00:20:03.440 precision is useless if you are hunting blindly right to 390 00:20:03.480 --> 00:20:07.920 measure microscopic spacetime fluctuations. You need to know exactly where 391 00:20:07.960 --> 00:20:12.200 to look at, what specific megahertz frequency, and precisely what 392 00:20:12.240 --> 00:20:15.359 the mathematical signal will look like when it hits the detector. 393 00:20:15.039 --> 00:20:19.000 And the Warwick framework finally handed them that map. It 394 00:20:19.079 --> 00:20:23.400 tells the experimentalists exactly how to tune their hypersensitive radios 395 00:20:23.440 --> 00:20:24.440 to hear the phone. 396 00:20:24.319 --> 00:20:28.359 And Professor Animesh data from Warwick emphasized an even broader implication. 397 00:20:29.079 --> 00:20:32.759 With this unified methodology, the global scientific community can now 398 00:20:32.799 --> 00:20:36.640 treat any proposed model of space time fluctuations in a consistent, 399 00:20:36.720 --> 00:20:39.839 standardized way. If a theorist comes up with a brand 400 00:20:39.880 --> 00:20:42.200 new theory of quantum gravity tomorrow, we can run it 401 00:20:42.200 --> 00:20:46.119