1 00:00:00,000 --> 00:00:03,880 Welcome to Cosmos in a Pod Space and Astronomy series. 2 00:00:03,880 --> 00:00:08,640 Have you ever imagined that the universe has like built in magnifying glasses? 3 00:00:08,640 --> 00:00:11,600 Like things that reveal hidden galaxies, distant wonders? 4 00:00:11,600 --> 00:00:13,440 They do, they do, they really do. 5 00:00:13,440 --> 00:00:17,600 It's called gravitational lensing and it's, it really is as mind-bending as it sounds. 6 00:00:17,600 --> 00:00:20,880 That sounds pretty wild. So what is gravitational lensing? 7 00:00:20,880 --> 00:00:26,040 It's kind of like the universe is playing a cosmic game of tricks with light. 8 00:00:26,040 --> 00:00:30,160 Just imagine a massive object, something like a galaxy cluster, 9 00:00:30,160 --> 00:00:33,360 and it's warping the fabric of space-time around it. 10 00:00:33,360 --> 00:00:37,240 Now picture the light from a really distant galaxy trying to reach us. 11 00:00:37,240 --> 00:00:37,840 Okay. 12 00:00:37,840 --> 00:00:40,760 That light doesn't just travel in a straight line, 13 00:00:40,760 --> 00:00:45,680 it follows the curves of space-time that are created by that massive object. 14 00:00:45,680 --> 00:00:48,480 So you're saying that massive objects can actually bend light? 15 00:00:48,480 --> 00:00:49,080 Yeah. 16 00:00:49,080 --> 00:00:51,320 I always thought light traveled in straight lines. 17 00:00:51,320 --> 00:00:54,000 It does, but remember space itself is being warped 18 00:00:54,000 --> 00:00:56,080 so the light is still traveling in a straight line. 19 00:00:56,080 --> 00:00:58,120 It's just going through a curved space. 20 00:00:58,120 --> 00:00:58,520 Wow. 21 00:00:58,520 --> 00:01:01,280 It's like if you were to draw a straight line on a piece of paper 22 00:01:01,280 --> 00:01:02,800 and then you bend the paper, 23 00:01:02,800 --> 00:01:05,600 the line is still straight but its path has changed, right? 24 00:01:05,600 --> 00:01:08,040 Right, right. That makes sense. 25 00:01:08,040 --> 00:01:12,600 Okay, so how does this bending of light create these magnifying glasses you were talking about? 26 00:01:12,600 --> 00:01:17,320 So when the light from that distant object passes by a massive object, 27 00:01:17,320 --> 00:01:19,560 it gets bent and then it's focused, 28 00:01:19,560 --> 00:01:21,840 kind of like how a lens would focus light. 29 00:01:21,840 --> 00:01:24,880 And this can create a lot of different effects depending on 30 00:01:24,880 --> 00:01:28,840 the alignment of the distant object, the massive object, and us, the observers. 31 00:01:28,840 --> 00:01:29,440 Okay. 32 00:01:29,440 --> 00:01:33,040 Sometimes it creates multiple images of that distant object 33 00:01:33,040 --> 00:01:36,200 as if the universe is showing us the same thing from different angles. 34 00:01:36,200 --> 00:01:37,120 Hold on. 35 00:01:37,120 --> 00:01:40,560 You're telling me we can see multiple versions of the same galaxy? 36 00:01:40,560 --> 00:01:41,960 Yeah, it's really wild. 37 00:01:41,960 --> 00:01:42,560 That's wild. 38 00:01:42,560 --> 00:01:44,800 Are there any like famous example of this happening? 39 00:01:44,800 --> 00:01:46,080 Absolutely. 40 00:01:46,080 --> 00:01:49,160 One of the most iconic examples is the Einstein Cross. 41 00:01:49,160 --> 00:01:50,520 It's a quasar. 42 00:01:50,520 --> 00:01:53,680 And for those who don't know, a quasar is a super bright object. 43 00:01:53,680 --> 00:01:55,880 It's powered by a supermassive black hole. 44 00:01:55,880 --> 00:01:56,520 Okay. 45 00:01:56,520 --> 00:01:59,520 And it appears as four distinct images 46 00:01:59,520 --> 00:02:02,960 because its light is being lensed by a galaxy that's in front of it. 47 00:02:02,960 --> 00:02:03,800 That's incredible. 48 00:02:03,800 --> 00:02:04,160 Yeah. 49 00:02:04,160 --> 00:02:06,480 So it's almost like a cosmic kaleidoscope 50 00:02:06,480 --> 00:02:09,080 showing us multiple reflections of the same object. 51 00:02:09,080 --> 00:02:10,800 Exactly. It's a really good way to put it. 52 00:02:10,800 --> 00:02:12,160 Wow. 53 00:02:12,160 --> 00:02:16,640 So are there other ways that this lensing effect can like manifest itself? 54 00:02:16,640 --> 00:02:17,160 Definitely. 55 00:02:17,160 --> 00:02:20,800 So sometimes instead of seeing multiple images, 56 00:02:20,800 --> 00:02:23,000 we see these beautiful arcs of light. 57 00:02:23,000 --> 00:02:26,640 They're stretched and distorted, almost like taffy being pulled apart. 58 00:02:26,640 --> 00:02:27,080 Okay. 59 00:02:27,080 --> 00:02:31,000 As if the universe is creating its own like abstract art. 60 00:02:31,000 --> 00:02:33,480 And sometimes if the alignment is just right, 61 00:02:33,480 --> 00:02:35,840 we can see these perfect rings of light. 62 00:02:35,840 --> 00:02:37,640 We call those Einstein rings. 63 00:02:37,640 --> 00:02:38,560 Einstein rings. 64 00:02:38,560 --> 00:02:39,400 I've heard of those. 65 00:02:39,400 --> 00:02:40,880 Those sound pretty spectacular. 66 00:02:40,880 --> 00:02:42,080 They are really spectacular. 67 00:02:42,080 --> 00:02:45,760 It's like the universe has put a giant cosmic halo 68 00:02:45,760 --> 00:02:49,600 around this distant galaxy, all thanks to the bending of light. 69 00:02:49,600 --> 00:02:52,800 So we have multiple images, arcs of light, and Einstein rings. 70 00:02:52,800 --> 00:02:54,160 Those all sound pretty dramatic. 71 00:02:54,160 --> 00:02:54,600 Yeah. 72 00:02:54,600 --> 00:02:58,200 Are there any like subtly forms of lensing too? 73 00:02:58,200 --> 00:02:58,640 You're right. 74 00:02:58,640 --> 00:03:00,040 Those are more dramatic effects. 75 00:03:00,040 --> 00:03:01,480 That's what we call strong lensing. 76 00:03:01,480 --> 00:03:01,800 Okay. 77 00:03:01,800 --> 00:03:04,960 But there's also weak lensing, which is much more subtle. 78 00:03:04,960 --> 00:03:08,520 It doesn't create multiple images or those dramatic arcs. 79 00:03:08,520 --> 00:03:12,440 It just distorts the shapes of background galaxies ever so slightly. 80 00:03:12,440 --> 00:03:14,680 So instead of seeing like double galaxies, 81 00:03:14,680 --> 00:03:17,680 we're seeing slightly stretched or squashed galaxies. 82 00:03:17,680 --> 00:03:18,680 Yeah. 83 00:03:18,680 --> 00:03:20,320 Doesn't sound quite as exciting. 84 00:03:20,320 --> 00:03:21,960 Maybe not as visually stunning. 85 00:03:21,960 --> 00:03:22,400 Yeah. 86 00:03:22,400 --> 00:03:25,920 But weak lensing is incredibly valuable to astronomers. 87 00:03:25,920 --> 00:03:30,480 It's like having this cosmic magnifying glass that's revealing 88 00:03:30,480 --> 00:03:32,960 something we can't see directly, dark matter. 89 00:03:32,960 --> 00:03:33,560 Dark matter. 90 00:03:33,560 --> 00:03:35,240 You mean that mysterious stuff that makes up 91 00:03:35,240 --> 00:03:39,160 like a huge chunk of the universe but doesn't emit or absorb light? 92 00:03:39,160 --> 00:03:39,760 Exactly. 93 00:03:39,760 --> 00:03:40,160 Okay. 94 00:03:40,160 --> 00:03:42,320 We can't see dark matter directly, 95 00:03:42,320 --> 00:03:44,840 but we can see its gravitational effects. 96 00:03:44,840 --> 00:03:47,280 And that includes its ability to bend light. 97 00:03:47,280 --> 00:03:49,880 So by studying how the shapes of background galaxies 98 00:03:49,880 --> 00:03:52,360 are distorted by weak lensing, astronomers 99 00:03:52,360 --> 00:03:55,480 can map out where the dark matter is concentrated. 100 00:03:55,480 --> 00:04:00,160 So we're using the bending of light to map something that we can't even see. 101 00:04:00,160 --> 00:04:03,120 It's like using shadows to figure out the shape of an invisible object. 102 00:04:03,120 --> 00:04:04,400 That's a great analogy. 103 00:04:04,400 --> 00:04:05,320 That's pretty cool. 104 00:04:05,320 --> 00:04:08,280 And that's just one of the ways that gravitational lensing is helping 105 00:04:08,280 --> 00:04:10,840 us unlock the secrets of the universe. 106 00:04:10,840 --> 00:04:11,960 It's a powerful tool. 107 00:04:11,960 --> 00:04:15,360 It allows us to see things that would otherwise remain hidden 108 00:04:15,360 --> 00:04:20,400 to probe the distant past and to test our understanding of gravity itself. 109 00:04:20,400 --> 00:04:21,000 That's incredible. 110 00:04:21,000 --> 00:04:24,760 So we've got strong lensing creating these really amazing visual effects. 111 00:04:24,760 --> 00:04:28,320 We've got weak lensing acting like a cosmic x-ray 112 00:04:28,320 --> 00:04:30,920 revealing this invisible world of dark matter. 113 00:04:30,920 --> 00:04:31,680 Yeah. 114 00:04:31,680 --> 00:04:34,040 But you mentioned another type of lensing earlier, right? 115 00:04:34,040 --> 00:04:34,600 Yes. 116 00:04:34,600 --> 00:04:35,880 Something called micro lens. 117 00:04:35,880 --> 00:04:38,000 Yes, micro lensing. 118 00:04:38,000 --> 00:04:39,720 Now think small scale. 119 00:04:39,720 --> 00:04:42,440 So instead of galaxies bending the light from other galaxies, 120 00:04:42,440 --> 00:04:46,440 we're talking about stars or even planets acting as lenses. 121 00:04:46,440 --> 00:04:46,920 Hold on. 122 00:04:46,920 --> 00:04:49,480 Are you saying that a single star can bend light enough 123 00:04:49,480 --> 00:04:51,680 to create a noticeable effect? 124 00:04:51,680 --> 00:04:55,320 Well, not quite like the dramatic effects that we see with galaxies. 125 00:04:55,320 --> 00:04:59,360 With micro lensing, it's more about subtle changes in brightness. 126 00:04:59,360 --> 00:05:01,840 So imagine a distant star's light being magnified 127 00:05:01,840 --> 00:05:03,760 by a star passing in front of it. 128 00:05:03,760 --> 00:05:07,040 We would see that distant star temporarily brighten as the closer star 129 00:05:07,040 --> 00:05:08,320 acts like a lens. 130 00:05:08,320 --> 00:05:10,760 So we're looking for stars that suddenly get brighter. 131 00:05:10,760 --> 00:05:12,240 Yeah, exactly. 132 00:05:12,240 --> 00:05:14,120 And here's where it gets really interesting. 133 00:05:14,120 --> 00:05:17,240 If that lensing star has a planet orbiting it, 134 00:05:17,240 --> 00:05:20,280 the planet's gravity can cause a little extra blip 135 00:05:20,280 --> 00:05:21,640 in the brightening pattern. 136 00:05:21,640 --> 00:05:25,080 It's like the planet is adding its own tiny magnifying effect 137 00:05:25,080 --> 00:05:26,880 on top of the star's lensing. 138 00:05:26,880 --> 00:05:30,680 So we can actually detect planets using this micro lensing technique. 139 00:05:30,680 --> 00:05:31,480 It is. 140 00:05:31,480 --> 00:05:34,920 And micro lensing has proven to be particularly good at finding planets 141 00:05:34,920 --> 00:05:36,960 that are farther away from their stars, planets that 142 00:05:36,960 --> 00:05:39,400 would be really difficult to detect using other methods. 143 00:05:39,400 --> 00:05:42,800 It's like having this special magnifying glass just for planets. 144 00:05:42,800 --> 00:05:43,880 That is incredible. 145 00:05:43,880 --> 00:05:44,920 Wow. 146 00:05:44,920 --> 00:05:48,960 So we have strong lensing creating these spectacular visual displays. 147 00:05:48,960 --> 00:05:53,480 We have weak lensing helping us map this invisible world of dark matter. 148 00:05:53,480 --> 00:05:56,440 And now we have micro lensing revealing hidden planets. 149 00:05:56,440 --> 00:05:57,440 This is mind blowing. 150 00:05:57,440 --> 00:06:00,960 But I'm curious, how does this lensing process actually work step by step? 151 00:06:00,960 --> 00:06:02,200 Can you break it down for me? 152 00:06:02,200 --> 00:06:02,840 Sure. 153 00:06:02,840 --> 00:06:06,280 So first, picture a distant galaxy emitting light. 154 00:06:06,280 --> 00:06:09,520 And it's traveling across these vast cosmic distances, 155 00:06:09,520 --> 00:06:11,040 trying to reach our telescopes. 156 00:06:11,040 --> 00:06:12,080 That's our starting point. 157 00:06:12,080 --> 00:06:13,080 The source is a light. 158 00:06:13,080 --> 00:06:14,200 Got it. 159 00:06:14,200 --> 00:06:17,920 So we've got light traveling toward us from this distant galaxy. 160 00:06:17,920 --> 00:06:18,800 What happens next? 161 00:06:18,800 --> 00:06:21,520 OK, so as that light travels towards us, 162 00:06:21,520 --> 00:06:25,240 it encounters, let's say, a massive object along its path, 163 00:06:25,240 --> 00:06:26,960 maybe a cluster of galaxies. 164 00:06:26,960 --> 00:06:29,480 And that cluster is our lens. 165 00:06:29,480 --> 00:06:31,440 OK, so the light from that distant galaxy 166 00:06:31,440 --> 00:06:34,480 is going to run right into that massive galaxy cluster. 167 00:06:34,480 --> 00:06:35,920 Not exactly run into. 168 00:06:35,920 --> 00:06:38,800 It's more like a cosmic bypass, I guess. 169 00:06:38,800 --> 00:06:43,400 So the galaxy cluster's gravity warps the fabric of spacetime around it. 170 00:06:43,400 --> 00:06:44,600 Right, like we were talking about earlier, 171 00:06:44,600 --> 00:06:46,880 spacetime is kind of like this flexible sheet. 172 00:06:46,880 --> 00:06:49,200 And massive objects create dips in it. 173 00:06:49,200 --> 00:06:50,600 So what happens to the light? 174 00:06:50,600 --> 00:06:53,880 The light, following its natural path, it bends. 175 00:06:53,880 --> 00:06:56,480 It travels through that warped spacetime. 176 00:06:56,480 --> 00:06:58,960 And it curves around the galaxy cluster. 177 00:06:58,960 --> 00:07:01,960 This bending and this curging, that's what we call gravitational lensing. 178 00:07:01,960 --> 00:07:02,920 Ah, OK. 179 00:07:02,920 --> 00:07:05,440 So the light doesn't smash into the galaxy cluster. 180 00:07:05,440 --> 00:07:10,080 It takes kind of a detour around it, like a car swerving to avoid a pothole, 181 00:07:10,080 --> 00:07:11,720 but on a cosmic scale. 182 00:07:11,720 --> 00:07:12,960 Exactly. 183 00:07:12,960 --> 00:07:15,480 And the final step in this little cosmic play 184 00:07:15,480 --> 00:07:18,200 is us, the observers here on Earth. 185 00:07:18,200 --> 00:07:21,200 We point our telescopes toward that distant galaxy, 186 00:07:21,200 --> 00:07:23,640 hoping to catch a glimpse of its light. 187 00:07:23,640 --> 00:07:28,280 And because of gravitational lensing, that light takes this curved path. 188 00:07:28,280 --> 00:07:31,920 And that can sometimes make the distant galaxy appear brighter 189 00:07:31,920 --> 00:07:33,240 or in a different position. 190 00:07:33,240 --> 00:07:33,840 Right. 191 00:07:33,840 --> 00:07:35,680 Or even multiply it into several images. 192 00:07:35,680 --> 00:07:36,600 Exactly. 193 00:07:36,600 --> 00:07:40,520 It depends on how the light is bent and focused by the lensing object. 194 00:07:40,520 --> 00:07:41,280 That's incredible. 195 00:07:41,280 --> 00:07:45,920 It's like the universe has its own built-in optical illusions. 196 00:07:45,920 --> 00:07:48,600 It's playing tricks with light and revealing things 197 00:07:48,600 --> 00:07:49,960 that we wouldn't otherwise see. 198 00:07:49,960 --> 00:07:50,920 Yeah, it's true. 199 00:07:50,920 --> 00:07:54,080 And the beauty of gravitational lensing is that it's not just about pretty 200 00:07:54,080 --> 00:07:54,960 pictures. 201 00:07:54,960 --> 00:07:59,080 It's this powerful tool that allows us to delve into the deepest 202 00:07:59,080 --> 00:08:00,400 mysteries of the universe. 203 00:08:00,400 --> 00:08:03,080 OK, what kind of mysteries are we talking about? 204 00:08:03,080 --> 00:08:04,880 Well, for one, it's helping us understand 205 00:08:04,880 --> 00:08:06,800 the elusive nature of dark matter. 206 00:08:06,800 --> 00:08:09,360 Remember how we talked about weak lensing distorting 207 00:08:09,360 --> 00:08:11,480 the shapes of background galaxies? 208 00:08:11,480 --> 00:08:14,120 Yeah, it was like using the lensing effect to see the invisible. 209 00:08:14,120 --> 00:08:15,280 Precisely. 210 00:08:15,280 --> 00:08:17,800 So by studying these subtle distortions, 211 00:08:17,800 --> 00:08:21,280 astronomers can create these detailed maps of dark matter, 212 00:08:21,280 --> 00:08:24,720 showing how it's distributed throughout the universe. 213 00:08:24,720 --> 00:08:28,360 These maps are giving us crucial insights into how galaxies form 214 00:08:28,360 --> 00:08:32,200 and evolve and how the universe's large-scale structure came to be. 215 00:08:32,200 --> 00:08:34,880 So it's not just confirming that dark matter exists. 216 00:08:34,880 --> 00:08:38,440 It's actually showing us where it is and how it shapes the universe. 217 00:08:38,440 --> 00:08:39,560 That's incredible. 218 00:08:39,560 --> 00:08:41,600 But aside from dark matter, what other mysteries 219 00:08:41,600 --> 00:08:43,280 is lensing helping us to solve? 220 00:08:43,280 --> 00:08:46,360 Well, it's allowing us to peer back in time to witness 221 00:08:46,360 --> 00:08:48,400 the universe in its infancy. 222 00:08:48,400 --> 00:08:52,400 Remember, the farther away an object is, the longer it takes for its light 223 00:08:52,400 --> 00:08:53,680 to reach us, right? 224 00:08:53,680 --> 00:08:55,760 So when we look at these distant galaxies, 225 00:08:55,760 --> 00:08:58,680 we're seeing them as they were billions of years ago. 226 00:08:58,680 --> 00:09:00,640 It's like looking at a cosmic photo album, 227 00:09:00,640 --> 00:09:03,800 with each galaxy representing a snapshot from a different era 228 00:09:03,800 --> 00:09:05,000 in the universe's history. 229 00:09:05,000 --> 00:09:06,080 Exactly. 230 00:09:06,080 --> 00:09:08,560 And the remarkable thing is that gravitational lensing 231 00:09:08,560 --> 00:09:12,800 can magnify the light from these incredibly faint, distant galaxies, 232 00:09:12,800 --> 00:09:15,240 making them visible to our telescopes. 233 00:09:15,240 --> 00:09:17,200 So it's like having a time machine that allows 234 00:09:17,200 --> 00:09:20,200 us to witness the universe's earliest chapters, 235 00:09:20,200 --> 00:09:23,360 to see the first stars and galaxies bursting into existence. 236 00:09:23,360 --> 00:09:23,840 Wow. 237 00:09:23,840 --> 00:09:26,280 So we're not just studying what the universe is made of. 238 00:09:26,280 --> 00:09:29,880 We're actually seeing how it evolved, how it transformed 239 00:09:29,880 --> 00:09:35,640 from this hot, dense soup of particles into the magnificent tapestry 240 00:09:35,640 --> 00:09:36,880 of galaxies that we see today. 241 00:09:36,880 --> 00:09:37,520 Absolutely. 242 00:09:37,520 --> 00:09:39,520 Gravitational lensing is like a key. 243 00:09:39,520 --> 00:09:42,080 It's unlocking the universe's hidden archives, 244 00:09:42,080 --> 00:09:45,360 giving us this access to information that would otherwise 245 00:09:45,360 --> 00:09:49,480 be lost to the vastness of space and time. 246 00:09:49,480 --> 00:09:50,360 It's remarkable. 247 00:09:50,360 --> 00:09:54,560 But with all this talk about dark matter in these distant galaxies, 248 00:09:54,560 --> 00:09:59,120 is there any chance that lensing could reveal something completely unexpected, 249 00:09:59,120 --> 00:10:02,760 something that challenges our current understanding of the universe? 250 00:10:02,760 --> 00:10:03,760 That's a great question. 251 00:10:03,760 --> 00:10:05,000 And the answer is absolutely. 252 00:10:05,000 --> 00:10:05,480 OK. 253 00:10:05,480 --> 00:10:08,840 While lensing has consistently validated Einstein's theory of relativity, 254 00:10:08,840 --> 00:10:12,680 there's always the possibility of finding these subtle deviations 255 00:10:12,680 --> 00:10:13,880 from predicted patterns. 256 00:10:13,880 --> 00:10:14,480 Deviations. 257 00:10:14,480 --> 00:10:15,520 What kind of deviation? 258 00:10:15,520 --> 00:10:18,560 Imagine observing a lensing effect that's 259 00:10:18,560 --> 00:10:21,640 stronger or weaker than what our current understanding of gravity 260 00:10:21,640 --> 00:10:22,720 would predict. 261 00:10:22,720 --> 00:10:26,480 Or let's say we find these anomalies in the shapes and positions 262 00:10:26,480 --> 00:10:29,680 of lensed images, things that just don't quite add up 263 00:10:29,680 --> 00:10:31,200 based on our current models. 264 00:10:31,200 --> 00:10:33,360 So like little glitches in the cosmic matrix? 265 00:10:33,360 --> 00:10:34,520 You could say that. 266 00:10:34,520 --> 00:10:38,200 And these glitches could be hints of new physics, 267 00:10:38,200 --> 00:10:42,560 pointing towards the existence of unknown forces or exotic particles, 268 00:10:42,560 --> 00:10:46,400 maybe even extra dimensions beyond our current perception of reality. 269 00:10:46,400 --> 00:10:48,960 So not only does lensing confirm what we know, 270 00:10:48,960 --> 00:10:52,560 but it also has the potential to reveal what we don't know, 271 00:10:52,560 --> 00:10:55,360 to push the boundaries of our understanding of the cosmos. 272 00:10:55,360 --> 00:10:56,280 Exactly. 273 00:10:56,280 --> 00:10:58,560 And that's what makes this field so exciting. 274 00:10:58,560 --> 00:11:00,440 We're not just confirming existing theories. 275 00:11:00,440 --> 00:11:03,160 We're constantly exploring the unknown, searching 276 00:11:03,160 --> 00:11:05,760 for those subtle anomalies that could revolutionize 277 00:11:05,760 --> 00:11:07,120 our view of the universe. 278 00:11:07,120 --> 00:11:09,480 I can't wait to see what new discoveries lensing will 279 00:11:09,480 --> 00:11:10,640 bring in the years to come. 280 00:11:10,640 --> 00:11:11,400 Me too. 281 00:11:11,400 --> 00:11:13,360 It's like a cosmic treasure hunt. 282 00:11:13,360 --> 00:11:18,120 Each new observation potentially revealing a hidden gem of knowledge. 283 00:11:18,120 --> 00:11:19,360 It really is. 284 00:11:19,360 --> 00:11:21,720 And the best part is we're only just beginning 285 00:11:21,720 --> 00:11:24,880 to tap into the potential of gravitational lensing. 286 00:11:24,880 --> 00:11:28,880 So with these new telescopes coming online and more sophisticated analysis 287 00:11:28,880 --> 00:11:33,120 techniques being developed, the future of this field is incredibly bright. 288 00:11:33,120 --> 00:11:35,200 Well, on that note, we'll have to take a short break. 289 00:11:35,200 --> 00:11:36,680 But don't worry, dear listeners. 290 00:11:36,680 --> 00:11:39,320 We'll be back soon for the final part of our deep dive 291 00:11:39,320 --> 00:11:41,240 into gravitational lensing. 292 00:11:41,240 --> 00:11:44,040 We're going to explore some of the most groundbreaking discoveries 293 00:11:44,040 --> 00:11:47,980 and look ahead at the future of this fascinating field. 294 00:11:47,980 --> 00:11:50,240 Welcome back to Cosmos in a Pod. 295 00:11:50,240 --> 00:11:53,760 We've been exploring the crazy world of gravitational lensing. 296 00:11:53,760 --> 00:11:56,360 And it's amazing to think that something like gravity 297 00:11:56,360 --> 00:12:00,360 can create these magnifying glasses that reveal hidden galaxies 298 00:12:00,360 --> 00:12:02,480 and map out dark matter. 299 00:12:02,480 --> 00:12:05,920 And we even found out that it helps us discover distant planets. 300 00:12:05,920 --> 00:12:08,680 It really shows how everything's connected in the universe. 301 00:12:08,680 --> 00:12:11,520 Like something as huge as a galaxy cluster 302 00:12:11,520 --> 00:12:14,640 can change the path of light from a distant galaxy, 303 00:12:14,640 --> 00:12:16,840 light that's been traveling for billions of years. 304 00:12:16,840 --> 00:12:18,560 And then we get to see it here on Earth. 305 00:12:18,560 --> 00:12:21,000 It's like some kind of cosmic game of billiards. 306 00:12:21,000 --> 00:12:21,800 Yeah. 307 00:12:21,800 --> 00:12:24,680 You know, where gravity is setting the balls in motion 308 00:12:24,680 --> 00:12:27,160 and light's showing us the paths they're taking, 309 00:12:27,160 --> 00:12:30,400 except the table's all warped and the balls can curve and bend 310 00:12:30,400 --> 00:12:31,680 in ways we wouldn't expect. 311 00:12:31,680 --> 00:12:33,480 And it's not just a game. 312 00:12:33,480 --> 00:12:37,680 It's a tool that's changed how we understand the universe. 313 00:12:37,680 --> 00:12:39,600 In this last part of our deep dive, 314 00:12:39,600 --> 00:12:42,040 I think we should talk about some of the most amazing 315 00:12:42,040 --> 00:12:44,000 discoveries that have been made because 316 00:12:44,000 --> 00:12:45,320 of gravitational lensing. 317 00:12:45,320 --> 00:12:46,760 OK, I'm ready. 318 00:12:46,760 --> 00:12:47,960 What are some of the big ones? 319 00:12:47,960 --> 00:12:49,280 Well, one of the biggest has been 320 00:12:49,280 --> 00:12:51,920 confirming that dark matter actually exists. 321 00:12:51,920 --> 00:12:53,680 Like we've been talking about, dark matter 322 00:12:53,680 --> 00:12:56,240 doesn't interact with light, so our telescopes can't see it. 323 00:12:56,240 --> 00:12:57,760 Right, it's like trying to see a ghost. 324 00:12:57,760 --> 00:13:00,120 You might know it's there, but you can't really see it. 325 00:13:00,120 --> 00:13:01,880 Yeah, exactly. 326 00:13:01,880 --> 00:13:03,480 But with gravitational lensing, we 327 00:13:03,480 --> 00:13:06,520 can see how it affects things, like how it warps the light 328 00:13:06,520 --> 00:13:08,920 coming from those distant galaxies. 329 00:13:08,920 --> 00:13:12,760 These distortions, that's the proof that dark matter is real. 330 00:13:12,760 --> 00:13:16,000 And it makes up a big part of the universe's mass. 331 00:13:16,000 --> 00:13:19,600 So lensing gives us the evidence for this mysterious stuff. 332 00:13:19,600 --> 00:13:22,040 But does it tell us what dark matter is made of? 333 00:13:22,040 --> 00:13:23,760 Now, that's the big question. 334 00:13:23,760 --> 00:13:27,240 Lensing shows us where dark matter is and how it's spread 335 00:13:27,240 --> 00:13:29,960 out, but it doesn't tell us what it's made of. 336 00:13:29,960 --> 00:13:31,920 There are a lot of theories about that, 337 00:13:31,920 --> 00:13:36,000 from exotic particles to forces we don't know about yet. 338 00:13:36,000 --> 00:13:39,240 So the mystery continues, but at least we know for sure 339 00:13:39,240 --> 00:13:40,600 that it's out there. 340 00:13:40,600 --> 00:13:42,240 And that's because of lensing. 341 00:13:42,240 --> 00:13:45,560 What other big discoveries have we made using this technique? 342 00:13:45,560 --> 00:13:47,480 Well, lensing's also been super important 343 00:13:47,480 --> 00:13:50,280 in finding some of the most distant galaxies 344 00:13:50,280 --> 00:13:51,440 we've ever seen. 345 00:13:51,440 --> 00:13:53,640 These galaxies are so far away that their light 346 00:13:53,640 --> 00:13:56,600 has been traveling for billions of years to reach us. 347 00:13:56,600 --> 00:13:59,600 So we're seeing a glimpse of the very early universe. 348 00:13:59,600 --> 00:14:02,080 So it's like using lensing as a time machine 349 00:14:02,080 --> 00:14:04,040 to see the universe when it was just a baby. 350 00:14:04,040 --> 00:14:05,880 What kind of galaxies are we talking about here? 351 00:14:05,880 --> 00:14:07,300 Well, we're talking about galaxies 352 00:14:07,300 --> 00:14:09,280 that formed just a few hundred million years 353 00:14:09,280 --> 00:14:10,560 after the Big Bang. 354 00:14:10,560 --> 00:14:12,560 Back then, the universe was still forming. 355 00:14:12,560 --> 00:14:14,760 It was like the first stars and galaxies were just 356 00:14:14,760 --> 00:14:15,920 starting to light up. 357 00:14:15,920 --> 00:14:17,080 That's amazing. 358 00:14:17,080 --> 00:14:19,920 It's like we're looking at a baby picture of the universe 359 00:14:19,920 --> 00:14:22,080 when galaxies were first forming. 360 00:14:22,080 --> 00:14:25,280 But how does lensing help us actually see these super 361 00:14:25,280 --> 00:14:27,880 faint and distant objects? 362 00:14:27,880 --> 00:14:31,300 Remember how we said lensing acts like a magnifying glass? 363 00:14:31,300 --> 00:14:33,720 Well, for these really distant galaxies, 364 00:14:33,720 --> 00:14:35,480 lensing can make their light stronger. 365 00:14:35,480 --> 00:14:37,400 So they look brighter and bigger to us 366 00:14:37,400 --> 00:14:38,680 than they would otherwise. 367 00:14:38,680 --> 00:14:40,320 And that means we can see galaxies that 368 00:14:40,320 --> 00:14:43,640 would be way too faint to see without lensing giving them 369 00:14:43,640 --> 00:14:44,440 a boost. 370 00:14:44,440 --> 00:14:48,240 So it's like lensing is giving our telescopes superpowers, 371 00:14:48,240 --> 00:14:50,600 letting them see further back in time. 372 00:14:50,600 --> 00:14:53,360 What did we learn from studying these early galaxies? 373 00:14:53,360 --> 00:14:56,320 By looking at the light from these lensed galaxies, 374 00:14:56,320 --> 00:14:58,680 we're learning a ton about the early universe. 375 00:14:58,680 --> 00:15:01,360 We're figuring out what it was like when the first stars 376 00:15:01,360 --> 00:15:02,920 and galaxies were born. 377 00:15:02,920 --> 00:15:05,220 We can look at their light and tell what they're made of, 378 00:15:05,220 --> 00:15:07,960 how fast they're making stars, and how they've changed 379 00:15:07,960 --> 00:15:09,360 over billions of years. 380 00:15:09,360 --> 00:15:11,040 It's like putting together a giant family 381 00:15:11,040 --> 00:15:14,160 album for the universe, tracing galaxies all the way back 382 00:15:14,160 --> 00:15:15,280 to the beginning. 383 00:15:15,280 --> 00:15:17,280 But besides those distant galaxies, 384 00:15:17,280 --> 00:15:19,640 has lensing led to any other surprising discoveries? 385 00:15:19,640 --> 00:15:20,960 Oh, yeah, for sure. 386 00:15:20,960 --> 00:15:23,260 One of the most unexpected ways we're using lensing 387 00:15:23,260 --> 00:15:24,960 is to find exoplanets. 388 00:15:24,960 --> 00:15:26,920 That's planets orbiting other stars. 389 00:15:26,920 --> 00:15:28,400 It's called microlensing. 390 00:15:28,400 --> 00:15:30,600 Wait, we can find planets with lensing. 391 00:15:30,600 --> 00:15:32,920 I thought it was all about galaxies and dark matter. 392 00:15:32,920 --> 00:15:33,440 That's true. 393 00:15:33,440 --> 00:15:35,640 Those are the most common ways we use it. 394 00:15:35,640 --> 00:15:37,920 But remember how we talked about microlensing, 395 00:15:37,920 --> 00:15:42,360 where a star or even a planet can act as a lens? 396 00:15:42,360 --> 00:15:44,960 And that makes the light from a farther star 397 00:15:44,960 --> 00:15:46,360 get brighter for a little bit? 398 00:15:46,360 --> 00:15:47,720 Yes, I remember. 399 00:15:47,720 --> 00:15:49,760 It was like a mini-lensing event happening 400 00:15:49,760 --> 00:15:50,760 inside a bigger one. 401 00:15:50,760 --> 00:15:51,840 Right. 402 00:15:51,840 --> 00:15:53,920 And if that star that's doing the lensing 403 00:15:53,920 --> 00:15:57,540 has a planet going around it, well, that planet's gravity 404 00:15:57,540 --> 00:16:00,280 can make a small change in the brightening pattern. 405 00:16:00,280 --> 00:16:02,760 It's almost like the planet's adding its own little effect 406 00:16:02,760 --> 00:16:03,720 to the lensing. 407 00:16:03,720 --> 00:16:05,980 So it's like the planet is jumping into the picture 408 00:16:05,980 --> 00:16:08,160 while the star is doing its lensing thing. 409 00:16:08,160 --> 00:16:11,400 And we can actually see these tiny planet photobombs. 410 00:16:11,400 --> 00:16:12,560 We can. 411 00:16:12,560 --> 00:16:15,840 And by looking at those changes in how bright the star gets, 412 00:16:15,840 --> 00:16:18,360 astronomers can figure out if there's a planet there, 413 00:16:18,360 --> 00:16:21,920 how big it is, and even how far away it is from its star. 414 00:16:21,920 --> 00:16:22,840 That's incredible. 415 00:16:22,840 --> 00:16:24,680 So we're using the gravity of a planet 416 00:16:24,680 --> 00:16:27,400 to find it, even though we can't see the planet itself. 417 00:16:27,400 --> 00:16:29,160 It's like a cosmic mystery. 418 00:16:29,160 --> 00:16:31,040 And gravity is giving us the clues. 419 00:16:31,040 --> 00:16:31,600 Exactly. 420 00:16:31,600 --> 00:16:34,680 Microlensing is really good at finding planets, especially 421 00:16:34,680 --> 00:16:37,200 small ones or ones that are far from their stars. 422 00:16:37,200 --> 00:16:39,680 It's like a special lens just for finding planets. 423 00:16:39,680 --> 00:16:40,720 This is amazing. 424 00:16:40,720 --> 00:16:43,520 We've seen how lensing helps us learn about dark matter, 425 00:16:43,520 --> 00:16:46,800 see distant galaxies, and even find hidden planets. 426 00:16:46,800 --> 00:16:48,320 What an amazing tool. 427 00:16:48,320 --> 00:16:49,080 What's next? 428 00:16:49,080 --> 00:16:51,080 What's the future of lensing research? 429 00:16:51,080 --> 00:16:53,520 The future of lensing is super exciting. 430 00:16:53,520 --> 00:16:55,920 We've got new powerful telescopes being built, 431 00:16:55,920 --> 00:16:58,520 both in space and on the ground. 432 00:16:58,520 --> 00:17:01,060 And that means even more incredible discoveries. 433 00:17:01,060 --> 00:17:02,960 Like the James Webb Space Telescope, 434 00:17:02,960 --> 00:17:06,160 it's already changing how we see lensed objects, 435 00:17:06,160 --> 00:17:08,040 because it can see infrared light, which 436 00:17:08,040 --> 00:17:10,520 lets it see through dust clouds that block our view 437 00:17:10,520 --> 00:17:11,320 with normal light. 438 00:17:11,320 --> 00:17:13,480 So Webb's like an X-ray machine for the universe. 439 00:17:13,480 --> 00:17:14,640 That's a great way to put it. 440 00:17:14,640 --> 00:17:16,880 And here on Earth, they're building huge telescopes, 441 00:17:16,880 --> 00:17:18,760 like the Extremely Large Telescope, which 442 00:17:18,760 --> 00:17:21,880 will have a mirror that's over 39 meters across. 443 00:17:21,880 --> 00:17:23,600 These next generation telescopes will 444 00:17:23,600 --> 00:17:26,920 be able to see individual stars in those distant galaxies, 445 00:17:26,920 --> 00:17:29,840 map dark matter even better, and maybe even 446 00:17:29,840 --> 00:17:33,160 find tiny differences from what Einstein's theory of gravity 447 00:17:33,160 --> 00:17:33,960 predicts. 448 00:17:33,960 --> 00:17:36,720 It sounds like we're about to enter a whole new era of lensing 449 00:17:36,720 --> 00:17:37,760 research. 450 00:17:37,760 --> 00:17:40,280 We've got better tools and ways to analyze things 451 00:17:40,280 --> 00:17:41,200 than ever before. 452 00:17:41,200 --> 00:17:42,200 Yeah, we are. 453 00:17:42,200 --> 00:17:44,000 And as we keep pushing the limits of what 454 00:17:44,000 --> 00:17:45,400 we can do with lensing, we're going 455 00:17:45,400 --> 00:17:47,760 to find even more amazing things. 456 00:17:47,760 --> 00:17:50,120 We'll learn more about how the universe evolved, 457 00:17:50,120 --> 00:17:52,920 what dark matter and dark energy are really like, 458 00:17:52,920 --> 00:17:55,000 and maybe even discover new laws of physics 459 00:17:55,000 --> 00:17:57,160 that control the whole cosmos. 460 00:17:57,160 --> 00:18:00,080 It's a fantastic time to be studying the universe using 461 00:18:00,080 --> 00:18:01,960 gravity as our guide. 462 00:18:01,960 --> 00:18:05,560 And that wraps up our deep dive into gravitational lensing. 463 00:18:05,560 --> 00:18:08,760 We started with the basics of this mind-blowing phenomena 464 00:18:08,760 --> 00:18:11,960 and explored how it affects what we know about the universe. 465 00:18:11,960 --> 00:18:15,000 We saw how it helps us uncover the secrets of dark matter, 466 00:18:15,000 --> 00:18:18,640 discover faraway galaxies, and even find hidden planets. 467 00:18:18,640 --> 00:18:20,080 We even peeked into the future, where 468 00:18:20,080 --> 00:18:21,760 new telescopes and techniques are going 469 00:18:21,760 --> 00:18:23,440 to unlock even more secrets. 470 00:18:23,440 --> 00:18:26,440 The universe is full of amazing things waiting to be discovered, 471 00:18:26,440 --> 00:18:29,460 and gravitational lensing gives us a unique and powerful way 472 00:18:29,460 --> 00:18:30,560 to see them. 473 00:18:30,560 --> 00:18:33,600 It helps us understand the mysteries of space and time 474 00:18:33,600 --> 00:18:36,520 and figure out where we fit in this vast cosmos. 475 00:18:36,520 --> 00:18:38,200 This has been an amazing journey. 476 00:18:38,200 --> 00:18:40,920 I hope you've all enjoyed it as much as we have. 477 00:18:40,920 --> 00:18:43,360 If you want to keep exploring the universe with us, 478 00:18:43,360 --> 00:18:45,360 be sure to subscribe to Cosmos in a Pod 479 00:18:45,360 --> 00:18:46,720 and check out our YouTube channel 480 00:18:46,720 --> 00:18:48,480 for more cosmic adventures. 481 00:18:48,480 --> 00:18:51,480 Until next time, keep looking up, keep asking questions, 482 00:18:51,480 --> 00:18:53,560 and never stop being amazed by the beauty 483 00:18:53,560 --> 00:19:09,200 and mystery of the universe.