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 --> 00:00:26.679 slumber under the night sky. 7 00:00:26.960 --> 00:00:30.079 Picture this, Okay, you are standing out in the absolute 8 00:00:30.120 --> 00:00:33.479 dead of night, pitch black, pitch black. You are looking 9 00:00:33.560 --> 00:00:37.200 up at the sky and you're waiting for something, anything, 10 00:00:37.240 --> 00:00:40.960 to happen, right, and then bam, a flash exactly a flash, 11 00:00:41.000 --> 00:00:42.719 a cosmic firework. 12 00:00:42.240 --> 00:00:44.280 Going off, but not just a normal one. 13 00:00:44.200 --> 00:00:46.560 Right, because you don't just see one explosion. You see 14 00:00:46.560 --> 00:00:49.719 the exact same explosion, the exact same burst of light, 15 00:00:49.840 --> 00:00:51.560 happening in five different places in the. 16 00:00:51.520 --> 00:00:53.520 Sky at the exact same moment, Yes, at. 17 00:00:53.439 --> 00:00:55.880 The exact same moment, and they are arranged in this 18 00:00:57.359 --> 00:00:59.640 perfect geometric cross. 19 00:00:59.359 --> 00:01:03.799 Pattern surrounding those two faint glowing orbs right in the center. 20 00:01:03.920 --> 00:01:06.719 It looks like a glitch, like the rendering software for 21 00:01:06.760 --> 00:01:10.079 the universe just stuttered and copied and pasted a star 22 00:01:10.359 --> 00:01:11.040 five times. 23 00:01:11.120 --> 00:01:14.439 It is a really striking visual. I mean, it completely 24 00:01:14.519 --> 00:01:17.519 challenges your intuition about how reality is supposed to work. 25 00:01:17.599 --> 00:01:20.280 It really does, because we are wired to believe that 26 00:01:20.480 --> 00:01:23.680 one object occupies one location in space. 27 00:01:23.640 --> 00:01:25.719 Right, basic physics for everyday life. 28 00:01:25.760 --> 00:01:28.439 Exactly, So when you see five of them, your brain 29 00:01:28.560 --> 00:01:30.200 instantly wants to reject it. 30 00:01:30.200 --> 00:01:31.680 It feels like science fiction. 31 00:01:31.920 --> 00:01:34.040 It does. But we aren't talking about sci fi today, No, 32 00:01:34.159 --> 00:01:34.519 we are not. 33 00:01:34.799 --> 00:01:38.879 We are talking about a very real, very hard data 34 00:01:38.920 --> 00:01:42.519 discovery that dropped in February twenty twenty six. 35 00:01:42.400 --> 00:01:43.799 A massive discovery. Right. 36 00:01:43.920 --> 00:01:48.239 This is the story of Sen Winni or Sen twenty 37 00:01:48.280 --> 00:01:51.000 twenty five Winni. If we want to use the formal catalog. 38 00:01:50.599 --> 00:01:52.640 Mam Winni is definitely easier to say. 39 00:01:52.560 --> 00:01:55.319 Much easier. It's a super nova that astronomers caught in 40 00:01:55.319 --> 00:01:55.920 the act. 41 00:01:55.920 --> 00:01:58.680 Ten billion light years away ten. 42 00:01:58.680 --> 00:02:02.040 Billion, and it's appearing has five distinct images. 43 00:02:02.319 --> 00:02:04.879 And while the image itself is beautiful, I mean, it 44 00:02:04.920 --> 00:02:07.799 really is a cosmic firework, just like the researchers called it. 45 00:02:07.959 --> 00:02:10.919 The esthetics are just the bait they draw you in, exactly. 46 00:02:11.039 --> 00:02:11.319 Yeah. 47 00:02:11.360 --> 00:02:14.719 The real hook here is what this specific glitch in 48 00:02:14.719 --> 00:02:16.080 the sky allows us to do. 49 00:02:16.319 --> 00:02:19.759 Because It's not just a stamp collecting exercise for astronomers. 50 00:02:19.360 --> 00:02:21.759 Not at all. This might actually be the solution to 51 00:02:21.800 --> 00:02:23.439 the biggest headache in modern physics. 52 00:02:23.560 --> 00:02:25.960 We are talking about the Hubble tension. 53 00:02:25.759 --> 00:02:29.319 The Hubble tension, the absolute crisis in cosmology right now. 54 00:02:29.400 --> 00:02:31.840 It's basically a one hundred year old argument that has 55 00:02:31.879 --> 00:02:34.120 split the physics community right down the middle. 56 00:02:34.360 --> 00:02:36.599 I feel like argument is almost putting it lightly at 57 00:02:36.599 --> 00:02:39.280 this point, more of a standoff. Definitely a standoff. Yeah. 58 00:02:39.319 --> 00:02:42.560 We have two very precise ways to measure how fast 59 00:02:42.560 --> 00:02:43.319 the universe is. 60 00:02:43.280 --> 00:02:46.919 Expanding, and they are giving us two completely different answers. 61 00:02:46.759 --> 00:02:49.159 Right, and they cannot both be right. 62 00:02:49.280 --> 00:02:50.879 If one side is right, the other is. 63 00:02:50.879 --> 00:02:54.639 Wrong, or even more excitingly, both are right in their 64 00:02:54.639 --> 00:02:57.800 own way, and our fundamental understanding of gravity or the 65 00:02:57.840 --> 00:02:59.000 early universe. 66 00:02:58.879 --> 00:03:01.159 Is just fly, which would be huge. 67 00:03:01.280 --> 00:03:04.280 It will re write the textbooks. We have been waiting 68 00:03:04.280 --> 00:03:06.439 for a tie breaker for years. 69 00:03:06.680 --> 00:03:08.000 A third way, Yes. 70 00:03:07.919 --> 00:03:10.719 A third way to measure the cosmos that doesn't rely 71 00:03:10.840 --> 00:03:13.000 on all the baggage of the previous. 72 00:03:12.520 --> 00:03:16.039 Methods, And that is exactly what sn winny it represents. 73 00:03:16.159 --> 00:03:17.439 It's the independent arbiter. 74 00:03:17.639 --> 00:03:20.360 It really is the Goldilock scenario. It's this one in 75 00:03:20.360 --> 00:03:24.039 a million alignment that lets us bypass the messy assumption 76 00:03:24.159 --> 00:03:26.039 heavy calculations we have been stuck with. 77 00:03:26.360 --> 00:03:28.639 So in this exploration today, we are going to look 78 00:03:28.680 --> 00:03:32.080 at how we found it, the insane technology required to 79 00:03:32.159 --> 00:03:36.319 actually see it, and the geometry, actual time delay physics. Right, 80 00:03:36.479 --> 00:03:40.240 the physics that turns a pretty picture into a literal 81 00:03:40.360 --> 00:03:41.560 ruler for the universe. 82 00:03:41.759 --> 00:03:42.680 It's fascinating. 83 00:03:42.800 --> 00:03:44.840 Let's get into the weeds. Then we need to start 84 00:03:44.879 --> 00:03:47.919 with the object itself. Sn winny. 85 00:03:48.159 --> 00:03:48.360 Right. 86 00:03:49.000 --> 00:03:52.520 We mentioned it's a supernova, but you don't get visible 87 00:03:52.599 --> 00:03:56.319 explosions ten billion light years away from just run of 88 00:03:56.319 --> 00:03:58.159 the mill dying stars, do you, No. 89 00:03:58.240 --> 00:03:59.919 You don't. This has to be something mass. 90 00:04:00.560 --> 00:04:02.280 So what are we actually looking at here? 91 00:04:02.680 --> 00:04:05.719 Well, a standard type EA supernova, which we use a 92 00:04:05.759 --> 00:04:07.800 lot in cosmology, is very. 93 00:04:07.599 --> 00:04:10.719 Bright, right, they are standard candles exactly. 94 00:04:10.800 --> 00:04:12.919 It can outshine its entire host galaxy for. 95 00:04:12.879 --> 00:04:15.520 A few weeks, which is wild to think about. 96 00:04:15.719 --> 00:04:18.439 It is, but at a red shift of two, which 97 00:04:18.480 --> 00:04:20.600 is the distance we are talking about here, roughly ten 98 00:04:20.680 --> 00:04:24.920 billion light years, a normal supernova would be incredibly. 99 00:04:24.360 --> 00:04:26.680 Faint, barely a pixel on a screen. 100 00:04:26.720 --> 00:04:29.959 Barely even that, But s and Winnie is a super 101 00:04:30.079 --> 00:04:31.959 luminous supernova super lumina. 102 00:04:31.959 --> 00:04:35.360 I always love how literal astronomers are with their naming conventions, 103 00:04:35.439 --> 00:04:38.120 very practical. It's like, well, it's a supernova, but it's super. 104 00:04:37.959 --> 00:04:39.519 It does exactly what it says on the tin. 105 00:04:39.720 --> 00:04:41.480 Right, So how much brighter are we talking? 106 00:04:41.680 --> 00:04:45.079 These are rare events. They are ten to one hundred 107 00:04:45.120 --> 00:04:48.279 times brighter than a standard supernova. Wow, we are talking 108 00:04:48.319 --> 00:04:52.680 about a release of energy that is genuinely difficult to 109 00:04:52.759 --> 00:04:53.680 even comprehend. 110 00:04:54.120 --> 00:04:56.279 So we have this absolute beacon of light going off 111 00:04:56.319 --> 00:04:59.839 in the distant universe. Right, But the light isn't traveling 112 00:04:59.879 --> 00:05:01.639 to to us in a straight line. 113 00:05:01.720 --> 00:05:04.800 No, it's not. And this is where Einstein enters. 114 00:05:04.600 --> 00:05:06.720 The chat general relativity exactly. 115 00:05:06.839 --> 00:05:10.120 General relativity tells us that mass curves space. 116 00:05:10.439 --> 00:05:13.079 Right, if you put a massive object in the fabric 117 00:05:13.079 --> 00:05:16.000 of space time, it creates a divot. Oh wow, the 118 00:05:16.040 --> 00:05:18.439 classic bowling ball on a trampoline analogy. 119 00:05:18.519 --> 00:05:21.839 It's classic for a reason. Now, imagine rolling a marble, 120 00:05:22.360 --> 00:05:26.240 which represents a photon of light across that trampoline. Okay, 121 00:05:26.319 --> 00:05:29.040 if it goes near the bowling ball, it's path curves. 122 00:05:29.160 --> 00:05:30.399 It doesn't go straight right, it. 123 00:05:30.360 --> 00:05:32.839 Follows the curve of the trampoline. Now scale that up 124 00:05:32.839 --> 00:05:35.639 to the cosmos. We have SN Whinni exploding way in 125 00:05:35.639 --> 00:05:36.800 the background. 126 00:05:36.399 --> 00:05:38.399 Ten billion light years back. 127 00:05:38.519 --> 00:05:41.920 Yes, and directly between us and that explosion, sitting right 128 00:05:41.959 --> 00:05:44.000 in the line of sight are two galaxies. 129 00:05:44.120 --> 00:05:45.360 These are the Lens galaxy. 130 00:05:45.439 --> 00:05:50.120 It's correct. The gravity of these foreground galaxies is bending 131 00:05:50.160 --> 00:05:54.839 space so severely that the light from SN Winni has 132 00:05:54.879 --> 00:05:56.800 no choice but to curve around. 133 00:05:56.519 --> 00:05:58.160 Them like a funhouse mirror. 134 00:05:58.439 --> 00:06:02.240 Exactly like a funhouse mirror. But here is the key. 135 00:06:02.319 --> 00:06:05.759 The alignment is so perfect. The light doesn't just curve 136 00:06:05.839 --> 00:06:06.279 one way. 137 00:06:06.839 --> 00:06:10.399 It splits. It splits, so it's taking multiple routes simultaneously. 138 00:06:10.560 --> 00:06:13.040 Think of it like a river flowing around a large island. 139 00:06:13.120 --> 00:06:14.160 Okay, I can picture that. 140 00:06:14.279 --> 00:06:16.839 The water splits, goes around both sides of the island, 141 00:06:16.879 --> 00:06:18.480 and then meets up again downstream. 142 00:06:18.959 --> 00:06:23.399 So the light from the supernova streams around these galaxies, taking. 143 00:06:23.199 --> 00:06:25.720 Different paths through the curved space. 144 00:06:25.480 --> 00:06:28.040 Time, and those paths converge. 145 00:06:27.439 --> 00:06:30.079 At Earth exactly so when our telescope points at that 146 00:06:30.199 --> 00:06:34.120 exact spot, it catches photons arriving from the left path. 147 00:06:33.959 --> 00:06:35.399 And photons arriving from the right. 148 00:06:35.279 --> 00:06:37.319 Path, photons coming over the top, and so on. 149 00:06:37.639 --> 00:06:40.560 And our brain or I guess the PERMERA sensor interprets 150 00:06:40.600 --> 00:06:43.480 those different arrival angles as completely different objects. 151 00:06:43.639 --> 00:06:46.879 Yes, we see five distinct images of the exact same event. 152 00:06:47.319 --> 00:06:49.639 This is what we call strong gravitational lensing. 153 00:06:49.720 --> 00:06:52.439 Now, we have seen lensing before, right, we have. The 154 00:06:52.480 --> 00:06:56.240 Einstein cross is a famous one where a quasar is 155 00:06:56.279 --> 00:06:57.759 split into four images. 156 00:06:58.120 --> 00:06:59.600 Right, that's a very well known example. 157 00:06:59.720 --> 00:07:03.680 So what makes sn WINNI so special? Why are researchers 158 00:07:03.759 --> 00:07:06.959 so incredibly excited about this one specifically? 159 00:07:07.079 --> 00:07:09.439 That is a great question. You are right. We have 160 00:07:09.560 --> 00:07:11.399 seen lensed quoasars. 161 00:07:11.000 --> 00:07:14.439 Quasars being those supermassive black holes actively feeding in the 162 00:07:14.439 --> 00:07:15.560 centers of galaxies. 163 00:07:15.639 --> 00:07:18.759 Exactly. They are incredibly bright and they stay bright. 164 00:07:18.920 --> 00:07:20.240 They are permanent fixtures. 165 00:07:20.519 --> 00:07:23.720 Basically, Yes, they flicker a bit, they have some variability, 166 00:07:23.720 --> 00:07:24.759 but they are always on. 167 00:07:24.879 --> 00:07:27.480 Meaning they don't have a distinct start and end date. 168 00:07:27.680 --> 00:07:30.279 Right. But a supernova is a transient event. 169 00:07:30.439 --> 00:07:32.959 It explodes, it brightens, it hits a peak, and. 170 00:07:32.920 --> 00:07:36.040 Then it fades away. It has a very distinct light curve. 171 00:07:35.879 --> 00:07:38.360 And that timing is crucial for what we want to 172 00:07:38.399 --> 00:07:40.680 do here, isn't it? It is everything, because if we 173 00:07:40.720 --> 00:07:43.040 want to measure the universe, we need a. 174 00:07:43.000 --> 00:07:46.120 Clock and go. We need a clock, and the supernova 175 00:07:46.240 --> 00:07:48.959 is the absolute perfect cosmic stop watch. 176 00:07:49.079 --> 00:07:49.759 That makes sense. 177 00:07:49.839 --> 00:07:52.040 But before we get into the how of the measurement, 178 00:07:52.319 --> 00:07:53.800 we really have to appreciate the. 179 00:07:53.720 --> 00:07:55.399 Odds here, right, the rarity. 180 00:07:55.879 --> 00:07:58.839 Sherry Suyu, who is a heavy hitter in this field 181 00:07:59.279 --> 00:08:02.040 over at the Technical University of Munich and the Max 182 00:08:02.040 --> 00:08:06.160 Planck Institute, she quantified the probability of this alignment. 183 00:08:06.360 --> 00:08:08.959 I read that quote she said, finding this is quote 184 00:08:09.279 --> 00:08:11.040 lower than one in a million. 185 00:08:10.759 --> 00:08:14.959 And that is not hyperbole really truly. You need a 186 00:08:15.120 --> 00:08:19.920 superluminous supernova, which is already incredibly rare on its own right. 187 00:08:20.079 --> 00:08:22.480 You need it to happen at the exact right distance 188 00:08:22.519 --> 00:08:25.600 from us. You need it to happen directly behind a 189 00:08:25.680 --> 00:08:30.240 galaxy that is massive enough and compact enough to act as. 190 00:08:30.079 --> 00:08:32.240 A lens, and you need to actually be looking at 191 00:08:32.279 --> 00:08:34.360 it at the right time exactly, so it's not just 192 00:08:34.399 --> 00:08:36.799 something you stumble upon while casually standing the. 193 00:08:36.759 --> 00:08:39.000 Sky, not at all. You have to actively hunt for it. 194 00:08:39.080 --> 00:08:40.600 And this was a long hunt, a. 195 00:08:40.559 --> 00:08:44.840 Six year hunt. The team, including researchers like Stefan Taalbenberger, 196 00:08:45.279 --> 00:08:48.480 spent years just compiling a list of potential lenses. 197 00:08:48.559 --> 00:08:50.799 So they basically mapped out the sky and said, okay, 198 00:08:50.799 --> 00:08:52.759 here are a bunch of galaxies that could act as 199 00:08:52.840 --> 00:08:55.600 lenses if something happens to explode behind them. 200 00:08:55.639 --> 00:08:57.519 That's exactly what they did, and then they waited. 201 00:08:57.799 --> 00:08:59.759 It's like setting up a bunch of camera traps in 202 00:08:59.799 --> 00:09:03.399 the jungle and just waiting for a very specific, very 203 00:09:03.519 --> 00:09:04.919 rare albino tiger to. 204 00:09:04.960 --> 00:09:08.039 Walk by and not just walk by, but explode while 205 00:09:08.080 --> 00:09:12.200 walking by. Right, They were monitoring these candidates constantly looking 206 00:09:12.200 --> 00:09:13.320 for a sudden blip. 207 00:09:13.120 --> 00:09:16.480 As light, and then in August twenty twenty five, the 208 00:09:16.519 --> 00:09:17.799 alert finally went off. 209 00:09:18.039 --> 00:09:21.200 It did this wiki transient facility picked it up. 210 00:09:21.320 --> 00:09:24.399 That's the wide field survey telescope that scans the sky 211 00:09:24.480 --> 00:09:24.919 every night. 212 00:09:25.000 --> 00:09:27.840 Right, Yes, it picked up a transient event. 213 00:09:27.960 --> 00:09:29.919 So when they pointed the big guns at it, did 214 00:09:29.919 --> 00:09:31.840 they see the five images immediately? 215 00:09:32.200 --> 00:09:34.600 Well not immediately, oh really, no, they saw that it 216 00:09:34.639 --> 00:09:36.720 was a candidate, it was a blip. But to really 217 00:09:36.799 --> 00:09:39.919 confirm the five images and see the actual structure, they 218 00:09:39.960 --> 00:09:41.120 needed the heavy artillery. 219 00:09:41.200 --> 00:09:44.960 They needed the large binocular telescope exactly, the LBT. That 220 00:09:45.039 --> 00:09:47.039 telescope is an Arizona right on Mount Graham. 221 00:09:47.159 --> 00:09:49.240 Yes it is, and it is an absolute beast of 222 00:09:49.279 --> 00:09:49.840 an instrument. 223 00:09:49.919 --> 00:09:52.399 It has two huge mirrors. 224 00:09:51.960 --> 00:09:54.840 Two eight point four meter diameter mirrors sitting side by side. 225 00:09:54.879 --> 00:09:57.279 But even with a telescope that massive, you still have 226 00:09:57.320 --> 00:09:58.240 a huge. 227 00:09:57.919 --> 00:09:59.840 Problem to deal with the atmosphere. 228 00:10:00.159 --> 00:10:03.399 Right The atmosphere is the enemy of high resolution astronomy, 229 00:10:03.440 --> 00:10:03.879 it really is. 230 00:10:04.000 --> 00:10:06.240 It's turbulent. It's what makes stars. 231 00:10:06.000 --> 00:10:09.159 Twinkle, and that twinkling smears out the fine detail. 232 00:10:09.480 --> 00:10:13.000 Exactly. If you are trying to resolve five tiny points 233 00:10:13.000 --> 00:10:16.759 of light that are huddled really close together ten billion 234 00:10:16.840 --> 00:10:17.559 light years. 235 00:10:17.360 --> 00:10:20.799 Away, the atmosphere just turns them into a fuzzy blob. 236 00:10:20.600 --> 00:10:23.600 And you cannot do precision cosmology with a blob. 237 00:10:24.080 --> 00:10:27.279 So they used adeptive optics they did. I always find 238 00:10:27.279 --> 00:10:30.159 this technology completely mind blowing. Can you break down how 239 00:10:30.200 --> 00:10:33.679 that actually works for us? Because it sounds like literal magic, 240 00:10:33.759 --> 00:10:35.480 like we just unqwinkle the stars. 241 00:10:35.759 --> 00:10:38.799 It is effectively magic, but it is deeply rooted in physics. 242 00:10:38.840 --> 00:10:39.759 Okay, walk me through it. 243 00:10:40.120 --> 00:10:44.360 They shoot a laser, usually a powerful sodium laser high 244 00:10:44.440 --> 00:10:48.120 up into the atmosphere. How high maybe ninety kilometers up 245 00:10:48.120 --> 00:10:52.039 into the mesosphere. Okay, this laser excites the sodium atoms 246 00:10:52.080 --> 00:10:55.759 up there and creates a glowing artificial star, a fake star, 247 00:10:56.080 --> 00:10:57.240 exactly a guide star. 248 00:10:57.399 --> 00:10:59.759 So they have a perfect reference point. They know exactly 249 00:10:59.799 --> 00:11:01.519 what that laser spot should look like. 250 00:11:01.600 --> 00:11:04.360 They know it should be a perfect sharp point of light. Right. 251 00:11:04.840 --> 00:11:09.399 But because of the atmospheric turbulence, the wind, the heat rising, 252 00:11:09.840 --> 00:11:13.440 the different pockets of air, the image of that laser 253 00:11:13.480 --> 00:11:15.679 dot gets distorted on its way back down. 254 00:11:15.799 --> 00:11:17.240 It dances around. 255 00:11:17.039 --> 00:11:21.720 Yes, and the telescope monitors that exact dissortion thousands of 256 00:11:21.759 --> 00:11:24.759 times per second, and then it corrects it in real time. 257 00:11:25.080 --> 00:11:26.200 That is insane. 258 00:11:26.399 --> 00:11:29.440 The telescope actually has a secondary mirror that is. 259 00:11:29.399 --> 00:11:32.600 Deformable, meaning it literally changes shape. 260 00:11:32.679 --> 00:11:36.080 Yes, it has hundreds of tiny little actuators behind it 261 00:11:36.279 --> 00:11:39.480 that physically push and pull the thin glass. 262 00:11:39.120 --> 00:11:40.879 Of the mirror, so it ripples the mirror. 263 00:11:40.919 --> 00:11:43.080 It ripples it in the exact opposite pattern of the 264 00:11:43.080 --> 00:11:44.080 atmospheric distortion. 265 00:11:44.440 --> 00:11:46.960 So if the atmosphere zigs the mirror zag. 266 00:11:46.840 --> 00:11:48.759 Precisely, it actively cancels out. 267 00:11:48.679 --> 00:11:50.440 The blur that is brilliant engineering. 268 00:11:50.519 --> 00:11:52.360 The result is that you get an image almost as 269 00:11:52.360 --> 00:11:53.879 sharp as if you were in space. 270 00:11:53.720 --> 00:11:55.799 Like Hubble or jwst right. 271 00:11:55.799 --> 00:11:58.240 But with the massive light gathering power of an eight 272 00:11:58.320 --> 00:11:59.559 meter ground telescope. 273 00:12:00.039 --> 00:12:02.480 That is how they got the first high resolution color 274 00:12:02.519 --> 00:12:03.840 image of s N WINNI. 275 00:12:04.039 --> 00:12:08.799 Yes, it revealed those five bluish points of light perfectly 276 00:12:08.919 --> 00:12:11.759 arranged around the two red or four ground galaxies. 277 00:12:12.039 --> 00:12:15.320 It's an incredible technical achievement just to get the picture 278 00:12:15.600 --> 00:12:18.039 it is, but that image is what allows us to 279 00:12:18.080 --> 00:12:19.720 actually start doing the math. 280 00:12:19.879 --> 00:12:22.799 The real work begins after the photo is taken. 281 00:12:23.039 --> 00:12:26.320 So we have the object, we have the pristine data. 282 00:12:26.360 --> 00:12:28.120 Now let's talk about the actual problem. 283 00:12:28.120 --> 00:12:29.600 This is supposed to solve, the big one. 284 00:12:29.639 --> 00:12:31.799 We mentioned the Hubble tension earlier, and I want to 285 00:12:31.879 --> 00:12:33.639 drill down into this because I think a lot of 286 00:12:33.639 --> 00:12:36.559 people hear, oh, the universe is expanding, and they just think, okay, cool, 287 00:12:36.679 --> 00:12:37.639 science knows. 288 00:12:37.440 --> 00:12:38.879 That, right. They think it's settled. 289 00:12:38.919 --> 00:12:41.240 They don't realize that we are actually in a massive 290 00:12:41.279 --> 00:12:43.519 crisis regarding how fast it's expanding. 291 00:12:43.799 --> 00:12:48.919 It is arguably the most significant disagreement in fundamental physics today. 292 00:12:48.960 --> 00:12:51.159 It's not just a rounding error, is it? 293 00:12:51.279 --> 00:12:53.159 No, it is a glaring contradiction. 294 00:12:53.440 --> 00:12:57.000 Let's define the terms for everyone, the hubble constant or 295 00:12:57.200 --> 00:12:59.440 h not. It's essentially the speed. 296 00:12:59.159 --> 00:13:02.200 Limit of the expand it's the rate of expansion. It 297 00:13:02.240 --> 00:13:04.960 tells us how fast a galaxy is receding from US, 298 00:13:05.039 --> 00:13:06.600 based entirely on its distance. 299 00:13:06.720 --> 00:13:10.440 Okay, and the units for this are notorious. 300 00:13:10.159 --> 00:13:13.440 Kilometers per second per megaparsec, which is a complete mouthful, 301 00:13:13.720 --> 00:13:16.039 it is, but it makes sense when you break it down. 302 00:13:16.159 --> 00:13:16.639 Let's do that. 303 00:13:17.039 --> 00:13:21.600 Basically, it means for every megaparsec you go out into spaces. 304 00:13:21.440 --> 00:13:24.559 And a megaparsec is about three point two six million 305 00:13:24.639 --> 00:13:26.679 light years, right exactly, So for. 306 00:13:26.639 --> 00:13:29.440 Every three point twenty six million light years you travel outward, 307 00:13:29.799 --> 00:13:32.720 how much faster is space itself expanding? 308 00:13:33.159 --> 00:13:36.320 So if the number is seventy, for example, then. 309 00:13:36.200 --> 00:13:39.519 A galaxy one megaparsec away is moving away from US 310 00:13:39.879 --> 00:13:41.440 at seventy kilometers per second. 311 00:13:41.480 --> 00:13:43.840 In a galaxy ten megaparsex. 312 00:13:43.200 --> 00:13:45.960 Away is moving away at seven hundred kilometers per second. 313 00:13:46.000 --> 00:13:50.559 Simple enough concept. Measure the speed, measure the distance, divide 314 00:13:50.559 --> 00:13:51.200 the two, and you. 315 00:13:51.159 --> 00:13:52.639 Have your number in theory. 316 00:13:52.919 --> 00:13:54.519 Why is this so hard in practice? 317 00:13:54.600 --> 00:13:59.000 Because measuring true distance in space is incredibly, incredibly difficult. 318 00:13:59.039 --> 00:14:01.159 We don't exactly have a cosmic tape measure. 319 00:14:01.279 --> 00:14:03.559 We don't. We have two main methods that we use, 320 00:14:03.799 --> 00:14:06.879 and they represent two completely different philosophies of looking at the. 321 00:14:06.919 --> 00:14:08.720 Universe, the ladder and the CMBA. 322 00:14:08.799 --> 00:14:11.399 Right, Let's start with the ladder, the cosmic distance ladder. Yes, 323 00:14:11.879 --> 00:14:13.320 this is the local universe method. 324 00:14:13.519 --> 00:14:17.080 It's empirical, meaning it relies on direct observation of things 325 00:14:17.159 --> 00:14:18.159 relatively nearby. 326 00:14:18.440 --> 00:14:21.960 Exactly. You start with objects close to Earth, where you 327 00:14:21.960 --> 00:14:26.840 can measure distance using simple geometry like parallax. Yes, exactly, 328 00:14:26.879 --> 00:14:29.639 like how your eyes jeedge distance. You mentioned the distance 329 00:14:29.679 --> 00:14:32.840 to a nearby star. Then you find a specific type 330 00:14:32.840 --> 00:14:36.039 of star called a syphiid variable in that same star cluster. 331 00:14:36.320 --> 00:14:38.360 Cipheids are what we call standard candles. 332 00:14:38.440 --> 00:14:42.759 Right. Yes, they physically pulse, they get brighter and dimmer, 333 00:14:43.200 --> 00:14:47.120 and their pulse rate is directly tied to their intrinsic brightness. 334 00:14:47.360 --> 00:14:49.480 So if you know how fast it pulses, you know 335 00:14:49.559 --> 00:14:51.360 exactly how bright it truly is. 336 00:14:51.679 --> 00:14:54.080 And if you know how bright it truly is, and 337 00:14:54.120 --> 00:14:56.200 you measure how dim it appears to us here. 338 00:14:56.080 --> 00:14:58.159 On Earth, you know exactly how far away it must 339 00:14:58.200 --> 00:14:59.000 be exactly. 340 00:14:59.039 --> 00:15:00.600 It's the inverse square law of light. 341 00:15:00.919 --> 00:15:04.759 So you use the really close sephades to calibrate the 342 00:15:04.799 --> 00:15:06.440 slightly further sephades. 343 00:15:06.519 --> 00:15:09.279 Yes, And then you look for cephiedes in galaxies that 344 00:15:09.399 --> 00:15:12.200 also happen to have Type E a supernova in them. 345 00:15:12.320 --> 00:15:16.200 Augh use the sefees to calibrate the brightness of the supernova. 346 00:15:15.799 --> 00:15:17.879 And supernova are much brighter so you can see them 347 00:15:17.960 --> 00:15:19.559 much further away exactly. 348 00:15:20.240 --> 00:15:24.519 Then you use those supernovae to measure distances to galaxies 349 00:15:24.720 --> 00:15:26.039 way way out in marble. 350 00:15:25.799 --> 00:15:28.320 Flow, where the expansion of the universe is the dominant 351 00:15:28.320 --> 00:15:29.399 force pushing them away. 352 00:15:29.519 --> 00:15:31.960 Right. So it's a ladder rung by rung by run, 353 00:15:32.039 --> 00:15:33.679 and that is its greatest. 354 00:15:33.279 --> 00:15:35.159 Weakness because it has systematics. 355 00:15:35.279 --> 00:15:38.840 Right, If your very first rung is slightly off. 356 00:15:39.519 --> 00:15:42.279 Because of dust extinction making the stars look just a 357 00:15:42.440 --> 00:15:44.399 tiny bit dimmer than they actually are. 358 00:15:44.600 --> 00:15:48.639 Or metallicity effects changing the internal physics of the sephids. 359 00:15:48.399 --> 00:15:51.919 That tiny error propagates up the entire ladder. 360 00:15:52.000 --> 00:15:54.240 It compounds at every single step. It's like a game 361 00:15:54.279 --> 00:15:54.879 of telephone. 362 00:15:55.080 --> 00:15:57.440 So what number does the latter team actually get? 363 00:15:57.759 --> 00:16:01.320 The team led by Adam Reese and others. Using this 364 00:16:01.399 --> 00:16:04.960 method consistently gets a number around seventy three or seventy four. 365 00:16:05.240 --> 00:16:08.519 Seventy three kilometers per second per megaparsec. 366 00:16:08.720 --> 00:16:11.919 Yes, they have refined this over and over for decades. 367 00:16:11.960 --> 00:16:13.679 They are incredibly confident in that number. 368 00:16:13.759 --> 00:16:16.639 Okay, so hold on to seventy three ish. Now, let's 369 00:16:16.639 --> 00:16:17.879 look at method two. 370 00:16:17.960 --> 00:16:21.120 The cosmic microwave background the CMB. This is the echo 371 00:16:21.159 --> 00:16:22.639 of the Big Bang itself, right. 372 00:16:22.559 --> 00:16:24.639 It's the oldest light we can possibly see. 373 00:16:24.799 --> 00:16:27.519 It's the ambient radiation left over from when the universe 374 00:16:27.559 --> 00:16:29.759 was only three hundred and eighty thousand years. 375 00:16:29.519 --> 00:16:32.519 Old, basically a baby picture of the cosmos exactly. 376 00:16:33.639 --> 00:16:38.440 The Plank satellite mapped this radiation with truly insane precision. 377 00:16:39.440 --> 00:16:42.919 We look at the tiny microscopic temperature fluctuations in that 378 00:16:43.000 --> 00:16:44.159 early universe. 379 00:16:43.879 --> 00:16:45.679 The little hot and cold spots in the map. 380 00:16:45.799 --> 00:16:48.279 Yes, but here's the catch with this method. 381 00:16:48.360 --> 00:16:49.320 There's always a catch. 382 00:16:49.440 --> 00:16:52.720 The CMB does not directly measure the expansion rate today. 383 00:16:52.519 --> 00:16:55.480 Because it's a picture from thirteen point eight billion years ago. 384 00:16:55.639 --> 00:16:58.200 Right. To get the expansion rate for today, we have 385 00:16:58.240 --> 00:16:59.759 to use a mathematical model. 386 00:17:00.000 --> 00:17:02.960 We have to plug that baby picture into our standard model. 387 00:17:02.679 --> 00:17:04.880 Of cosmology lamed a CDM. 388 00:17:04.559 --> 00:17:06.079 And we just run the clock forward. 389 00:17:06.160 --> 00:17:09.680 We simulate thirteen point eight billion years of cosmic evolution 390 00:17:10.079 --> 00:17:12.559 to predict what the expansion rate should be right now. 391 00:17:12.720 --> 00:17:16.000 So one team measures the universe exactly as it is locally, 392 00:17:16.079 --> 00:17:18.160 and the other team predicts what it ought to be 393 00:17:18.200 --> 00:17:19.880 based on exactly how it started. 394 00:17:19.960 --> 00:17:21.720 That is a perfect way to put it. And when 395 00:17:21.720 --> 00:17:24.720 the CMB team does that massive calculation, they get sixty 396 00:17:24.759 --> 00:17:25.920 seven point four. 397 00:17:25.880 --> 00:17:29.000 Sixty seven point four, So we have sixty seven on 398 00:17:29.000 --> 00:17:30.720 one side and seventy three on the other. 399 00:17:31.039 --> 00:17:33.440 And the airbars are tiny now. 400 00:17:33.400 --> 00:17:35.000 They don't overlap at all. 401 00:17:34.880 --> 00:17:38.119