1 00:00:00,000 --> 00:00:02,960 Welcome back to Cosmos in a Pod, Space, and Astronomy series. 2 00:00:02,960 --> 00:00:04,120 Episode 10. 3 00:00:04,120 --> 00:00:07,520 Get ready, because today we're taking a deep dive. 4 00:00:07,520 --> 00:00:10,200 Into the fascinating world of galaxies. 5 00:00:10,200 --> 00:00:11,200 I'm excited for this one. 6 00:00:11,200 --> 00:00:12,480 Oh, me too, me too. 7 00:00:12,480 --> 00:00:15,240 All right, so to start us off, can you set the scene, 8 00:00:15,240 --> 00:00:18,000 like, way back, just moments after the Big Bang? 9 00:00:18,000 --> 00:00:19,800 What was the universe like back then? 10 00:00:19,800 --> 00:00:21,200 OK, so picture this. 11 00:00:21,200 --> 00:00:22,200 It's hot. 12 00:00:22,200 --> 00:00:22,680 OK. 13 00:00:22,680 --> 00:00:26,320 A dense sea of mostly hydrogen and helium gas. 14 00:00:26,320 --> 00:00:26,960 I'm picturing it. 15 00:00:26,960 --> 00:00:28,280 It's the very beginning. 16 00:00:28,280 --> 00:00:30,560 And this is where it gets really interesting. 17 00:00:30,560 --> 00:00:32,320 It wasn't perfectly uniform. 18 00:00:32,320 --> 00:00:34,600 There were these tiny fluctuations in density, 19 00:00:34,600 --> 00:00:36,640 like ripples from the Big Bang itself. 20 00:00:36,640 --> 00:00:37,200 Ripples. 21 00:00:37,200 --> 00:00:37,880 Ripples. 22 00:00:37,880 --> 00:00:41,840 And those ripples unbelievably became the seeds of galaxies. 23 00:00:41,840 --> 00:00:43,320 The seeds of galaxies. 24 00:00:43,320 --> 00:00:46,920 How did something so small create something so vast? 25 00:00:46,920 --> 00:00:48,840 It's all thanks to gravity. 26 00:00:48,840 --> 00:00:51,480 Over millions of years, these denser regions, 27 00:00:51,480 --> 00:00:53,280 with the help of dark matter's pull, 28 00:00:53,280 --> 00:00:56,840 started drawing in more and more gas. 29 00:00:56,840 --> 00:00:59,840 Think of it as cosmic dust bunnies gathering under the bed, 30 00:00:59,840 --> 00:01:01,280 except on a much grander scale. 31 00:01:01,280 --> 00:01:03,720 And eventually, they grew into massive structures 32 00:01:03,720 --> 00:01:05,400 called dark matter halos. 33 00:01:05,400 --> 00:01:09,120 So dark matter halos acted as a kind of scaffolding. 34 00:01:09,120 --> 00:01:09,640 Exactly. 35 00:01:09,640 --> 00:01:11,080 Upon which galaxies were built. 36 00:01:11,080 --> 00:01:12,320 Precisely. 37 00:01:12,320 --> 00:01:15,800 They provided the framework for gas to clump together 38 00:01:15,800 --> 00:01:18,040 and become so dense that it eventually 39 00:01:18,040 --> 00:01:20,360 collapsed under its own gravity. 40 00:01:20,360 --> 00:01:24,120 And from that collapse, the first stars were born. 41 00:01:24,120 --> 00:01:24,920 The first stars. 42 00:01:24,920 --> 00:01:25,720 What were they like? 43 00:01:25,720 --> 00:01:28,840 These first stars, called population III stars, 44 00:01:28,840 --> 00:01:30,520 were true titans. 45 00:01:30,520 --> 00:01:33,160 Hundreds of times more massive than our sun. 46 00:01:33,160 --> 00:01:34,880 But their reign was short lived. 47 00:01:34,880 --> 00:01:35,560 What happened to them? 48 00:01:35,560 --> 00:01:36,560 Did they just fade away? 49 00:01:36,560 --> 00:01:37,160 No, no. 50 00:01:37,160 --> 00:01:39,200 They went out with a bang, literally. 51 00:01:39,200 --> 00:01:42,440 They exploded as supernovae, seeding the surrounding space 52 00:01:42,440 --> 00:01:45,160 with heavier elements like carbon and oxygen. 53 00:01:45,160 --> 00:01:47,960 These elements, forged in the hearts of dying stars, 54 00:01:47,960 --> 00:01:50,880 became the building blocks for future generations of stars. 55 00:01:50,880 --> 00:01:51,360 Oh, wow. 56 00:01:51,360 --> 00:01:53,040 And eventually, life itself. 57 00:01:53,040 --> 00:01:53,540 Wow. 58 00:01:53,540 --> 00:01:55,000 So the death of those first stars 59 00:01:55,000 --> 00:01:56,520 was a way for us. 60 00:01:56,520 --> 00:01:57,640 Absolutely. 61 00:01:57,640 --> 00:02:00,320 Those supernovae enriched the cosmic soup, 62 00:02:00,320 --> 00:02:03,440 allowing for the formation of more complex structures, 63 00:02:03,440 --> 00:02:07,000 including the first galaxies, called proto galaxies. 64 00:02:07,000 --> 00:02:08,200 Proto galaxies. 65 00:02:08,200 --> 00:02:10,320 So how did we go from those early proto galaxies 66 00:02:10,320 --> 00:02:12,680 to the majestic spiral, analytical galaxies 67 00:02:12,680 --> 00:02:13,640 we see today? 68 00:02:13,640 --> 00:02:17,520 So the early universe was a bit like a cosmic mosh pit. 69 00:02:17,520 --> 00:02:19,400 These proto galaxies were constantly 70 00:02:19,400 --> 00:02:21,320 colliding and merging. 71 00:02:21,320 --> 00:02:24,000 This process is called hierarchical merging. 72 00:02:24,000 --> 00:02:26,320 Smaller galaxies were drawn together by gravity, 73 00:02:26,320 --> 00:02:30,520 creating larger, more complex galaxies over billions of years. 74 00:02:30,520 --> 00:02:31,280 And you know what? 75 00:02:31,280 --> 00:02:32,680 This process is still happening. 76 00:02:32,680 --> 00:02:35,600 It's one of the key forces shaping the galactic landscape 77 00:02:35,600 --> 00:02:36,280 we observe. 78 00:02:36,280 --> 00:02:39,400 So even galaxies have a dramatic and chaotic past. 79 00:02:39,400 --> 00:02:40,960 They certainly do. 80 00:02:40,960 --> 00:02:42,720 And speaking of drama, let's dive 81 00:02:42,720 --> 00:02:44,560 into the different types of galaxies 82 00:02:44,560 --> 00:02:46,080 we see scattered across the universe. 83 00:02:46,080 --> 00:02:47,240 OK, I'm all ears. 84 00:02:47,240 --> 00:02:50,000 We can broadly classify them into three main types, 85 00:02:50,000 --> 00:02:52,080 elliptical, spiral, and irregular. 86 00:02:52,080 --> 00:02:52,680 OK. 87 00:02:52,680 --> 00:02:54,800 Each type has its own unique characteristics 88 00:02:54,800 --> 00:02:57,120 and tells us a story about its formation history. 89 00:02:57,120 --> 00:02:58,880 All right, let's start with elliptical galaxies. 90 00:02:58,880 --> 00:02:59,720 What are they like? 91 00:02:59,720 --> 00:03:03,440 Imagine a smooth, almost featureless oval of stars. 92 00:03:03,440 --> 00:03:05,280 That's an elliptical galaxy in a nutshell. 93 00:03:05,280 --> 00:03:08,440 They come in a range of shapes, from nearly spherical 94 00:03:08,440 --> 00:03:10,520 to quite elongated. 95 00:03:10,520 --> 00:03:12,840 Elliptical galaxies are thought to form mainly 96 00:03:12,840 --> 00:03:15,560 through the mergers of smaller galaxies. 97 00:03:15,560 --> 00:03:17,040 And because they've already used up 98 00:03:17,040 --> 00:03:20,320 most of their gas in previous bursts of star formation, 99 00:03:20,320 --> 00:03:22,660 they're mostly composed of older stars. 100 00:03:22,660 --> 00:03:25,720 So they're like the seasoned veterans of the universe. 101 00:03:25,720 --> 00:03:26,880 That's a great way to put it. 102 00:03:26,880 --> 00:03:28,600 They've lived through the wild times 103 00:03:28,600 --> 00:03:32,160 and now reside in a more settled phase of their existence, 104 00:03:32,160 --> 00:03:34,840 giving off a reddish hue due to the abundance 105 00:03:34,840 --> 00:03:35,960 of those older stars. 106 00:03:35,960 --> 00:03:37,840 OK, now spiral galaxies. 107 00:03:37,840 --> 00:03:40,200 I know our own Milky Way is a spiral, right? 108 00:03:40,200 --> 00:03:40,920 That's right. 109 00:03:40,920 --> 00:03:44,240 The Milky Way is a perfect example of a spiral galaxy. 110 00:03:44,240 --> 00:03:46,320 With its flat, disk-like structure 111 00:03:46,320 --> 00:03:48,840 and those beautiful spiral arms winding outward 112 00:03:48,840 --> 00:03:51,820 from the central bulge, it's like a cosmic pinwheel, 113 00:03:51,820 --> 00:03:53,680 constantly spinning and evolving. 114 00:03:53,680 --> 00:03:55,640 Those spiral arms are where the action is, right? 115 00:03:55,640 --> 00:03:56,760 Exactly. 116 00:03:56,760 --> 00:03:59,560 The spiral arms are hotbeds of star formation, 117 00:03:59,560 --> 00:04:03,040 where vast clouds of gas and dust collapse under gravity, 118 00:04:03,040 --> 00:04:05,080 igniting the birth of new stars. 119 00:04:05,080 --> 00:04:07,480 They're the vibrant nurseries of galaxies. 120 00:04:07,480 --> 00:04:09,800 It must be an incredible sight to witness those star 121 00:04:09,800 --> 00:04:11,080 nurseries in action. 122 00:04:11,080 --> 00:04:12,680 It is breathtaking. 123 00:04:12,680 --> 00:04:16,000 We can see star-forming regions in nearby galaxies 124 00:04:16,000 --> 00:04:19,840 with our telescopes, and they are truly awe-inspiring. 125 00:04:19,840 --> 00:04:21,960 So we've covered the stately elliptical galaxies 126 00:04:21,960 --> 00:04:24,360 and the dynamic spiral galaxies. 127 00:04:24,360 --> 00:04:25,880 What about the irregular ones? 128 00:04:25,880 --> 00:04:27,480 What sets them apart? 129 00:04:27,480 --> 00:04:30,920 Irregular galaxies are the rebels of the galaxy world. 130 00:04:30,920 --> 00:04:32,840 They defy the neat classifications 131 00:04:32,840 --> 00:04:35,800 of spirals and ellipticals with their chaotic, jumbled 132 00:04:35,800 --> 00:04:36,440 appearance. 133 00:04:36,440 --> 00:04:37,640 They just do their own thing. 134 00:04:37,640 --> 00:04:38,880 They do their own thing. 135 00:04:38,880 --> 00:04:42,200 They tend to be smaller and more active in star formation, 136 00:04:42,200 --> 00:04:44,600 often exhibiting bursts of star birth, 137 00:04:44,600 --> 00:04:47,000 triggered by interactions with other galaxies. 138 00:04:47,000 --> 00:04:49,920 So galactic encounters can really mess with a galaxy 139 00:04:49,920 --> 00:04:50,400 structure. 140 00:04:50,400 --> 00:04:51,320 They can. 141 00:04:51,320 --> 00:04:54,360 Think of a cosmic fender bender, a near miss, 142 00:04:54,360 --> 00:04:55,680 or a side swipe. 143 00:04:55,680 --> 00:04:57,640 These encounters can warp and distort 144 00:04:57,640 --> 00:04:59,400 the shape of a galaxy, leaving it 145 00:04:59,400 --> 00:05:01,520 with a unique and irregular form. 146 00:05:01,520 --> 00:05:04,400 This makes me realize that even though we classify galaxies 147 00:05:04,400 --> 00:05:06,720 into these three main types, there's still 148 00:05:06,720 --> 00:05:08,120 so much diversity out there. 149 00:05:08,120 --> 00:05:09,120 You're absolutely right. 150 00:05:09,120 --> 00:05:12,360 The universe is an incredible tapestry of galaxies, 151 00:05:12,360 --> 00:05:15,000 each with its own unique history, characteristics, 152 00:05:15,000 --> 00:05:16,320 and evolutionary path. 153 00:05:16,320 --> 00:05:19,240 It's like a cosmic zoo of galaxies out there. 154 00:05:19,240 --> 00:05:21,320 Now, we've talked a lot about the visible components 155 00:05:21,320 --> 00:05:22,440 of galaxies. 156 00:05:22,440 --> 00:05:24,920 But what about the unseen force shaping them? 157 00:05:24,920 --> 00:05:26,560 You're talking about dark matter, right? 158 00:05:26,560 --> 00:05:27,360 Exactly. 159 00:05:27,360 --> 00:05:30,520 We can't see it, but it seems to be a major player 160 00:05:30,520 --> 00:05:32,560 in the universe's structure, especially 161 00:05:32,560 --> 00:05:33,720 when it comes to galaxies. 162 00:05:33,720 --> 00:05:34,840 You're spot on. 163 00:05:34,840 --> 00:05:37,200 Dark matter, despite being invisible, 164 00:05:37,200 --> 00:05:40,400 exerts a powerful gravitational influence. 165 00:05:40,400 --> 00:05:43,680 It acts like an invisible hand, shaping galaxies 166 00:05:43,680 --> 00:05:45,320 and holding them together. 167 00:05:45,320 --> 00:05:48,240 But how do we even know it exists if we can't see it? 168 00:05:48,240 --> 00:05:51,720 We know it's there because of its gravitational effects. 169 00:05:51,720 --> 00:05:54,080 One compelling piece of evidence comes from observing 170 00:05:54,080 --> 00:05:56,080 the rotation of galaxies. 171 00:05:56,080 --> 00:05:58,840 Stars and galaxies orbit much faster than they should, 172 00:05:58,840 --> 00:06:00,880 based on the visible matter alone. 173 00:06:00,880 --> 00:06:04,080 This tells us that there must be some unseen mass providing 174 00:06:04,080 --> 00:06:06,440 the extra gravitational pull. 175 00:06:06,440 --> 00:06:07,440 That's dark matter. 176 00:06:07,440 --> 00:06:09,120 So it's like an invisible glue holding 177 00:06:09,120 --> 00:06:10,560 these massive structures together. 178 00:06:10,560 --> 00:06:11,880 That's a great analogy. 179 00:06:11,880 --> 00:06:14,760 Dark matter creates a halo around each galaxy, 180 00:06:14,760 --> 00:06:18,080 extending far beyond the visible stars and gas. 181 00:06:18,080 --> 00:06:20,440 This halo provides the gravitational scaffolding 182 00:06:20,440 --> 00:06:23,160 that allows galaxies to maintain their structure 183 00:06:23,160 --> 00:06:24,720 and prevents them from flying apart. 184 00:06:24,720 --> 00:06:26,480 That's mind blowing. 185 00:06:26,480 --> 00:06:28,480 We've talked about galaxy formation, 186 00:06:28,480 --> 00:06:32,320 the different types of galaxies, and the role of dark matter. 187 00:06:32,320 --> 00:06:34,600 But what happens when galaxies get a little too 188 00:06:34,600 --> 00:06:35,760 close for comfort? 189 00:06:35,760 --> 00:06:39,440 Ah, now that's where things get truly spectacular. 190 00:06:39,440 --> 00:06:41,320 Galaxies aren't static objects. 191 00:06:41,320 --> 00:06:43,360 They interact and collide with each other, 192 00:06:43,360 --> 00:06:46,360 performing a cosmic dance across vast stretches 193 00:06:46,360 --> 00:06:47,680 of time and space. 194 00:06:47,680 --> 00:06:49,800 Galactic collisions. 195 00:06:49,800 --> 00:06:51,120 That sounds intense. 196 00:06:51,120 --> 00:06:53,240 What happens when two galaxies collide? 197 00:06:53,240 --> 00:06:55,000 It's less of a head-on collision and more 198 00:06:55,000 --> 00:06:57,440 of a graceful slow motion interaction. 199 00:06:57,440 --> 00:07:00,520 Stars rarely collide directly because the distances 200 00:07:00,520 --> 00:07:03,560 between them are vast, even within a galaxy. 201 00:07:03,560 --> 00:07:06,120 Instead, the gravitational forces between the galaxies 202 00:07:06,120 --> 00:07:09,160 distort their shapes, pulling out long streamers of stars 203 00:07:09,160 --> 00:07:09,760 and gas. 204 00:07:09,760 --> 00:07:10,360 Oh, wow. 205 00:07:10,360 --> 00:07:12,840 Triggering intense bursts of star formation. 206 00:07:12,840 --> 00:07:14,280 So galactic collisions can actually 207 00:07:14,280 --> 00:07:15,680 lead to the birth of new stars. 208 00:07:15,680 --> 00:07:16,360 Absolutely. 209 00:07:16,360 --> 00:07:18,640 The compression of gas clouds during these encounters 210 00:07:18,640 --> 00:07:21,400 can spark star formation on a grand scale, 211 00:07:21,400 --> 00:07:24,640 leading to a spectacular cosmic fireworks show. 212 00:07:24,640 --> 00:07:27,160 Are there any famous examples of galactic collisions 213 00:07:27,160 --> 00:07:28,120 we can look at? 214 00:07:28,120 --> 00:07:29,840 One of the most stunning examples 215 00:07:29,840 --> 00:07:32,040 is the antenna galaxies. 216 00:07:32,040 --> 00:07:33,840 This pair of interacting galaxies 217 00:07:33,840 --> 00:07:36,520 is caught in a spectacular collision, 218 00:07:36,520 --> 00:07:39,200 showcasing the dynamic and ever-changing nature 219 00:07:39,200 --> 00:07:40,200 of the universe. 220 00:07:40,200 --> 00:07:42,000 I've seen pictures of the antenna galaxies, 221 00:07:42,000 --> 00:07:43,400 and they are breathtaking. 222 00:07:43,400 --> 00:07:44,320 They are. 223 00:07:44,320 --> 00:07:48,360 The images show long, arcing tales of stars and gas 224 00:07:48,360 --> 00:07:51,360 being pulled out as these galaxies waltz around each 225 00:07:51,360 --> 00:07:52,120 other. 226 00:07:52,120 --> 00:07:55,160 It's a glimpse into the sheer power and beauty of gravity 227 00:07:55,160 --> 00:07:55,920 at work. 228 00:07:55,920 --> 00:07:58,160 This makes me wonder about the fate of our own galaxy, 229 00:07:58,160 --> 00:07:59,200 the Milky Way. 230 00:07:59,200 --> 00:08:01,600 Are we on a collision course with any other galaxy? 231 00:08:01,600 --> 00:08:03,720 Well, here's a thought-provoking fact. 232 00:08:03,720 --> 00:08:05,680 The Milky Way is on a collision course 233 00:08:05,680 --> 00:08:08,160 with our nearest galactic neighbor, the Andromeda 234 00:08:08,160 --> 00:08:09,120 Galaxy. 235 00:08:09,120 --> 00:08:10,120 Wait, seriously. 236 00:08:10,120 --> 00:08:12,800 Are galaxies going to collide with another galaxy? 237 00:08:12,800 --> 00:08:14,200 It's true, but don't worry. 238 00:08:14,200 --> 00:08:16,360 It's not happening for another few billion years. 239 00:08:16,360 --> 00:08:17,960 Phew, that's a relief. 240 00:08:17,960 --> 00:08:20,160 But what will happen when the collision does occur? 241 00:08:20,160 --> 00:08:22,000 It will be a monumental event. 242 00:08:22,000 --> 00:08:23,640 The two galaxies will merge. 243 00:08:23,640 --> 00:08:27,280 There are stars and gas swirling together in a cosmic ballet, 244 00:08:27,280 --> 00:08:30,880 eventually forming a new, larger elliptical galaxy. 245 00:08:30,880 --> 00:08:33,240 So in a sense, galactic collisions 246 00:08:33,240 --> 00:08:38,320 are part of a grand cosmic cycle of creation and destruction. 247 00:08:38,320 --> 00:08:41,640 It's fascinating to think about the vastness of the universe 248 00:08:41,640 --> 00:08:44,000 and the incredible processes that shape it 249 00:08:44,000 --> 00:08:45,480 over billions of years. 250 00:08:45,480 --> 00:08:46,720 It truly is humbling. 251 00:08:46,720 --> 00:08:48,680 And we've only scratched the surface of what there 252 00:08:48,680 --> 00:08:50,560 is to learn about galaxies. 253 00:08:50,560 --> 00:08:53,400 Well, before we get too lost in the cosmic vastness, 254 00:08:53,400 --> 00:08:54,800 let's take a moment to appreciate 255 00:08:54,800 --> 00:08:56,760 the incredible diversity of galaxies 256 00:08:56,760 --> 00:08:58,440 that exist in the universe. 257 00:08:58,440 --> 00:08:59,960 We've talked about the main types, 258 00:08:59,960 --> 00:09:02,600 but I imagine there's a whole spectrum of shape, sizes, 259 00:09:02,600 --> 00:09:04,000 and characteristics out there. 260 00:09:04,000 --> 00:09:04,960 We're absolutely right. 261 00:09:04,960 --> 00:09:07,480 It's like a cosmic art gallery showcasing 262 00:09:07,480 --> 00:09:09,520 an astonishing array of galaxies. 263 00:09:09,520 --> 00:09:12,440 We have dwarf galaxies, which are small and faint, 264 00:09:12,440 --> 00:09:14,600 containing just a few million stars. 265 00:09:14,600 --> 00:09:17,320 And then we have giant elliptical galaxies, 266 00:09:17,320 --> 00:09:20,040 behemoths that harbor trillions of stars. 267 00:09:20,040 --> 00:09:23,400 So galaxies come in all shapes and sizes, just like, well, 268 00:09:23,400 --> 00:09:23,720 you know. 269 00:09:23,720 --> 00:09:24,720 Exactly. 270 00:09:24,720 --> 00:09:26,640 And their diversity doesn't stop there. 271 00:09:26,640 --> 00:09:29,320 Some galaxies are actively forming stars, 272 00:09:29,320 --> 00:09:32,520 ablaze with the brilliant glow of newborn stars. 273 00:09:32,520 --> 00:09:35,200 Others are more quiescent, their star formation having 274 00:09:35,200 --> 00:09:36,760 slowed or ceased altogether. 275 00:09:36,760 --> 00:09:39,920 It's as though each galaxy has its own personality and story 276 00:09:39,920 --> 00:09:40,520 to tell. 277 00:09:40,520 --> 00:09:41,760 I love that analogy. 278 00:09:41,760 --> 00:09:43,040 It's so true. 279 00:09:43,040 --> 00:09:45,520 Each galaxy is a unique entity shaped 280 00:09:45,520 --> 00:09:47,520 by its history and environment. 281 00:09:47,520 --> 00:09:49,120 And by studying this diversity, we 282 00:09:49,120 --> 00:09:52,120 can gain a deeper understanding of the processes that govern 283 00:09:52,120 --> 00:09:55,240 galaxy formation and evolution. 284 00:09:55,240 --> 00:09:56,800 This makes me think about the role 285 00:09:56,800 --> 00:09:59,400 of supermassive black holes. 286 00:09:59,400 --> 00:10:02,200 I know they lurk at the centers of most galaxies, 287 00:10:02,200 --> 00:10:03,520 including our own Milky Way. 288 00:10:03,520 --> 00:10:04,080 Yes. 289 00:10:04,080 --> 00:10:06,760 Supermassive black holes are fascinating objects. 290 00:10:06,760 --> 00:10:09,720 They have masses millions or even billions of times 291 00:10:09,720 --> 00:10:10,920 greater than our sun. 292 00:10:10,920 --> 00:10:12,840 And they exert a powerful influence 293 00:10:12,840 --> 00:10:14,520 on their host galaxies. 294 00:10:14,520 --> 00:10:17,440 How do these supermassive black holes affect the galaxies 295 00:10:17,440 --> 00:10:18,520 they reside in? 296 00:10:18,520 --> 00:10:20,520 Their immense gravity can influence 297 00:10:20,520 --> 00:10:24,000 the orbits of stars and gas clouds in the galactic core. 298 00:10:24,000 --> 00:10:26,560 They can also drive powerful outflows of energy, 299 00:10:26,560 --> 00:10:29,200 which can heat up and expel gas from the galaxy, 300 00:10:29,200 --> 00:10:31,400 shaping its evolution in dramatic ways. 301 00:10:31,400 --> 00:10:33,440 So they can both create and destroy. 302 00:10:33,440 --> 00:10:34,600 In a way, yes. 303 00:10:34,600 --> 00:10:37,600 They play a complex role in the evolution of galaxies. 304 00:10:37,600 --> 00:10:40,080 Sometimes their activity can trigger star formation, 305 00:10:40,080 --> 00:10:41,680 while other times it can quench it. 306 00:10:41,680 --> 00:10:43,080 It's a delicate balance. 307 00:10:43,080 --> 00:10:46,520 It's amazing to think that these invisible objects can 308 00:10:46,520 --> 00:10:49,520 have such a profound impact on the galaxies they inhabit. 309 00:10:49,520 --> 00:10:50,480 It is. 310 00:10:50,480 --> 00:10:53,360 And we're still learning so much about the intricate interplay 311 00:10:53,360 --> 00:10:57,600 between supermassive black holes and their host galaxies. 312 00:10:57,600 --> 00:11:00,080 All of this makes me wonder about the long term 313 00:11:00,080 --> 00:11:01,400 fate of galaxies. 314 00:11:01,400 --> 00:11:03,800 What will happen to them as the universe continues 315 00:11:03,800 --> 00:11:05,440 to age and expand? 316 00:11:05,440 --> 00:11:06,800 That's a great question to ponder 317 00:11:06,800 --> 00:11:08,800 as we move to the next part of our discussion. 318 00:11:08,800 --> 00:11:10,960 OK, well on that note, I think it's time to wrap up 319 00:11:10,960 --> 00:11:12,880 part one of our galactic exploration. 320 00:11:12,880 --> 00:11:15,360 Join us next time as we continue our journey, 321 00:11:15,360 --> 00:11:17,680 delving deeper into the mysteries and wonders 322 00:11:17,680 --> 00:11:19,600 of these cosmic masterpieces. 323 00:11:19,600 --> 00:11:20,360 Welcome back. 324 00:11:20,360 --> 00:11:23,280 OK, so we left off talking about the future of galaxies. 325 00:11:23,280 --> 00:11:24,320 The part two. 326 00:11:24,320 --> 00:11:26,800 As the universe continues to age and expand. 327 00:11:26,800 --> 00:11:28,280 Of our galactic adventure. 328 00:11:28,280 --> 00:11:29,360 It's a bit mind boggling. 329 00:11:29,360 --> 00:11:31,880 Ready to delve deeper into the mysteries of the universe. 330 00:11:31,880 --> 00:11:32,920 Absolutely. 331 00:11:32,920 --> 00:11:35,440 To think about such vast time scales. 332 00:11:35,440 --> 00:11:36,320 It really is. 333 00:11:36,320 --> 00:11:39,360 But by thinking about these enormous stretches of time, 334 00:11:39,360 --> 00:11:43,080 we can start to grasp the grand cycles of the universe. 335 00:11:43,080 --> 00:11:45,200 Just like stars have life cycles. 336 00:11:45,200 --> 00:11:46,400 So galaxies. 337 00:11:46,400 --> 00:11:48,320 They are born, they flourish, they evolve, 338 00:11:48,320 --> 00:11:51,320 and eventually their star forming days wind down. 339 00:11:51,320 --> 00:11:55,440 So if a galaxy is no longer actively forming new stars, 340 00:11:55,440 --> 00:11:58,080 does it essentially become a cosmic graveyard? 341 00:11:58,080 --> 00:12:00,720 Not quite a graveyard, but certainly a quieter place. 342 00:12:00,720 --> 00:12:01,680 Think of it this way. 343 00:12:01,680 --> 00:12:03,880 Even though new star formation might cease, 344 00:12:03,880 --> 00:12:06,360 the existing stars continue to shine. 345 00:12:06,360 --> 00:12:09,280 However, the galaxy's stellar population 346 00:12:09,280 --> 00:12:11,400 begins to shift over time. 347 00:12:11,400 --> 00:12:12,480 What do you mean by shift? 348 00:12:12,480 --> 00:12:15,520 Well, as massive stars reach the end of their lives, 349 00:12:15,520 --> 00:12:18,040 they explode as supernovae. 350 00:12:18,040 --> 00:12:21,560 Leaving behind remnants like neutron stars and black holes. 351 00:12:21,560 --> 00:12:24,600 Meanwhile, the smaller, less massive stars, 352 00:12:24,600 --> 00:12:27,160 which are much more numerous, keep burning steadily 353 00:12:27,160 --> 00:12:29,520 for billions, even trillions of years. 354 00:12:29,520 --> 00:12:31,560 So a galaxy gradually becomes populated 355 00:12:31,560 --> 00:12:33,640 with more of these long-lived lower mass stars. 356 00:12:33,640 --> 00:12:34,640 Precisely. 357 00:12:34,640 --> 00:12:36,520 And this change in the stellar population 358 00:12:36,520 --> 00:12:39,520 affects the galaxy's appearance in a very noticeable way. 359 00:12:39,520 --> 00:12:40,600 How so? 360 00:12:40,600 --> 00:12:43,440 I'm picturing a galaxy full of tiny, faint stars. 361 00:12:43,440 --> 00:12:44,960 It's not just about size. 362 00:12:44,960 --> 00:12:46,400 It's about color. 363 00:12:46,400 --> 00:12:49,800 Hot, massive stars emit bluer light, 364 00:12:49,800 --> 00:12:53,200 while cooler, less massive stars emit redder light. 365 00:12:53,200 --> 00:12:56,280 So as a galaxy ages and its population of massive stars 366 00:12:56,280 --> 00:13:00,600 dwindles, its overall color shifts from bluer to redder. 367 00:13:00,600 --> 00:13:02,520 So that's why older galaxies often have 368 00:13:02,520 --> 00:13:04,200 that reddish hue in images. 369 00:13:04,200 --> 00:13:04,680 Right. 370 00:13:04,680 --> 00:13:06,440 It's like they've mellowed with age. 371 00:13:06,440 --> 00:13:07,920 That's a great way to think about it. 372 00:13:07,920 --> 00:13:09,600 It's a telltale sign of their age 373 00:13:09,600 --> 00:13:12,240 and the evolution of their stellar populations. 374 00:13:12,240 --> 00:13:15,320 It's fascinating how we can infer so much about a galaxy's 375 00:13:15,320 --> 00:13:17,560 history just by observing its color. 376 00:13:17,560 --> 00:13:19,120 It's like the galactic archaeology. 377 00:13:19,120 --> 00:13:19,620 It is. 378 00:13:19,620 --> 00:13:21,440 And as our telescopes become more powerful, 379 00:13:21,440 --> 00:13:23,960 we're able to peer even deeper into the universe 380 00:13:23,960 --> 00:13:26,800 and study galaxies at different stages of their evolution, 381 00:13:26,800 --> 00:13:29,560 piecing together the story of how they formed and changed 382 00:13:29,560 --> 00:13:30,360 over time. 383 00:13:30,360 --> 00:13:31,560 Speaking of looking back in time, 384 00:13:31,560 --> 00:13:33,800 it makes me wonder about the very first galaxies that 385 00:13:33,800 --> 00:13:35,480 formed in the early universe. 386 00:13:35,480 --> 00:13:37,080 What were they like? 387 00:13:37,080 --> 00:13:39,500 The first galaxies were true pioneers, 388 00:13:39,500 --> 00:13:43,080 blazing a trail through the darkness of the early universe. 389 00:13:43,080 --> 00:13:45,640 They were likely much smaller and less massive 390 00:13:45,640 --> 00:13:47,920 than the galaxies we see today, perhaps even 391 00:13:47,920 --> 00:13:51,560 100 or 1,000 times smaller than our Milky Way. 392 00:13:51,560 --> 00:13:54,040 So they were like the building blocks of the larger galaxies 393 00:13:54,040 --> 00:13:54,640 that came later. 394 00:13:54,640 --> 00:13:55,520 Exactly. 395 00:13:55,520 --> 00:13:57,560 And they were probably quite chaotic, 396 00:13:57,560 --> 00:14:00,360 with lots of mergers and interactions happening 397 00:14:00,360 --> 00:14:03,320 as they jostled for position in the young universe. 398 00:14:03,320 --> 00:14:05,080 Yeah, I can imagine the early universe must 399 00:14:05,080 --> 00:14:06,840 been a pretty wild place. 400 00:14:06,840 --> 00:14:09,880 It's amazing that we can observe these early galaxies now, 401 00:14:09,880 --> 00:14:13,400 thanks to powerful telescopes like the James Webb Space 402 00:14:13,400 --> 00:14:14,040 Telescope. 403 00:14:14,040 --> 00:14:14,800 It is remarkable. 404 00:14:14,800 --> 00:14:17,320 The James Webb Telescope is like a time machine, 405 00:14:17,320 --> 00:14:20,040 allowing us to peer back billions of years 406 00:14:20,040 --> 00:14:22,840 and witness the formation of the first galaxies, 407 00:14:22,840 --> 00:14:25,520 capturing light that has been traveling across the universe 408 00:14:25,520 --> 00:14:27,520 for almost its entire history. 409 00:14:27,520 --> 00:14:28,320 Wow. 410 00:14:28,320 --> 00:14:30,760 It's like having a front row seat to the universe's greatest 411 00:14:30,760 --> 00:14:31,880 show. 412 00:14:31,880 --> 00:14:33,520 And with each new observation, we 413 00:14:33,520 --> 00:14:36,720 gain a clearer picture of how galaxies formed and evolved. 414 00:14:36,720 --> 00:14:37,760 Precisely. 415 00:14:37,760 --> 00:14:39,560 As we gather more data, we continue 416 00:14:39,560 --> 00:14:43,240 to unravel the mysteries of galaxy formation and evolution. 417 00:14:43,240 --> 00:14:46,800 This makes me appreciate the vastness of the universe 418 00:14:46,800 --> 00:14:48,600 and the incredible processes that 419 00:14:48,600 --> 00:14:50,440 have shaped it over billions of years. 420 00:14:50,440 --> 00:14:51,600 Me too. 421 00:14:51,600 --> 00:14:54,280 It's a humbling and awe-inspiring experience 422 00:14:54,280 --> 00:14:56,520 to study these cosmic wonders. 423 00:14:56,520 --> 00:14:58,400 Before we wrap up this part of our discussion, 424 00:14:58,400 --> 00:15:01,800 I wanted to circle back to something we mentioned earlier. 425 00:15:01,800 --> 00:15:03,960 Supermassive black holes. 426 00:15:03,960 --> 00:15:07,440 They seem to play a significant role in the lives of galaxies. 427 00:15:07,440 --> 00:15:08,600 They do. 428 00:15:08,600 --> 00:15:11,440 We now believe that nearly every large galaxy 429 00:15:11,440 --> 00:15:14,320 harbors a supermassive black hole at its center. 430 00:15:14,320 --> 00:15:18,000 What exactly makes these black holes so supermassive? 431 00:15:18,000 --> 00:15:19,880 Well, their name says it all. 432 00:15:19,880 --> 00:15:22,840 They are incredibly massive, containing millions or even 433 00:15:22,840 --> 00:15:25,120 billions of times the mass of our sun. 434 00:15:25,120 --> 00:15:27,040 Billions of times the mass of our sun. 435 00:15:27,040 --> 00:15:28,400 How did they get so big? 436 00:15:28,400 --> 00:15:32,000 We think they grow over time by pulling in gas and stars 437 00:15:32,000 --> 00:15:33,320 from their surroundings. 438 00:15:33,320 --> 00:15:35,320 It's a process called accretion, and it 439 00:15:35,320 --> 00:15:37,120 can be a very dramatic affair. 440 00:15:37,120 --> 00:15:39,280 And sometimes, during galactic collisions, 441 00:15:39,280 --> 00:15:40,920 supermassive black holes can even 442 00:15:40,920 --> 00:15:44,280 merge with each other, creating even more massive black holes. 443 00:15:44,280 --> 00:15:46,920 It's like a never-ending feast for these black holes, 444 00:15:46,920 --> 00:15:49,640 constantly consuming matter to grow larger and larger. 445 00:15:49,640 --> 00:15:51,320 That's a good way to think about it. 446 00:15:51,320 --> 00:15:53,320 They have a voracious appetite for matter. 447 00:15:53,320 --> 00:15:53,920 But hold on. 448 00:15:53,920 --> 00:15:56,760 Aren't black holes supposed to be invisible? 449 00:15:56,760 --> 00:15:59,640 How do we even know they're there if they don't emit light? 450 00:15:59,640 --> 00:16:01,080 That's a great question. 451 00:16:01,080 --> 00:16:03,720 We can't see the black hole itself directly 452 00:16:03,720 --> 00:16:08,440 because its gravity is so strong that not even light can escape. 453 00:16:08,440 --> 00:16:10,840 However, we can detect their presence 454 00:16:10,840 --> 00:16:12,520 through their gravitational effects 455 00:16:12,520 --> 00:16:13,760 on their surroundings. 456 00:16:13,760 --> 00:16:17,120 So it's like their gravity leaves a telltale signature 457 00:16:17,120 --> 00:16:18,080 that we can observe. 458 00:16:18,080 --> 00:16:19,200 Exactly. 459 00:16:19,200 --> 00:16:21,920 Even though we can't see the black hole itself, 460 00:16:21,920 --> 00:16:24,440 we can observe how its gravity influences 461 00:16:24,440 --> 00:16:27,760 the motion of stars and gas in its vicinity. 462 00:16:27,760 --> 00:16:29,360 And the more massive the black hole, 463 00:16:29,360 --> 00:16:31,520 the stronger its gravitational pull 464 00:16:31,520 --> 00:16:33,680 and the more noticeable its effects. 465 00:16:33,680 --> 00:16:35,800 It's amazing how we can infer the presence 466 00:16:35,800 --> 00:16:38,120 of these invisible objects just by observing 467 00:16:38,120 --> 00:16:39,440 their gravitational influence. 468 00:16:39,440 --> 00:16:41,520 It's like a cosmic detective story. 469 00:16:41,520 --> 00:16:42,160 It is. 470 00:16:42,160 --> 00:16:44,840 And as our observational techniques improve, 471 00:16:44,840 --> 00:16:47,240 we are learning more about the fascinating relationship 472 00:16:47,240 --> 00:16:50,720 between supermassive black holes and their host galaxies. 473 00:16:50,720 --> 00:16:53,200 So what role do these supermassive black holes 474 00:16:53,200 --> 00:16:56,120 play in the evolution of galaxies? 475 00:16:56,120 --> 00:16:57,720 Are they helpful or harmful? 476 00:16:57,720 --> 00:16:59,240 It's a complex relationship. 477 00:16:59,240 --> 00:17:01,720 And we're still piecing together the details. 478 00:17:01,720 --> 00:17:04,640 But we know that these black holes can have a profound impact 479 00:17:04,640 --> 00:17:07,640 on their surroundings, both positive and negative. 480 00:17:07,640 --> 00:17:08,520 For example? 481 00:17:08,520 --> 00:17:10,720 Well, as matter falls into a black hole, 482 00:17:10,720 --> 00:17:14,320 it heats up and emits intense radiation. 483 00:17:14,320 --> 00:17:17,800 This radiation can create powerful outflows of energy, 484 00:17:17,800 --> 00:17:20,360 which can push gas out of the galaxy, 485 00:17:20,360 --> 00:17:23,360 influencing its ability to form new stars. 486 00:17:23,360 --> 00:17:24,960 Wait, so black holes can actually 487 00:17:24,960 --> 00:17:28,080 blow away the very material the galaxies need 488 00:17:28,080 --> 00:17:29,320 to form new stars? 489 00:17:29,320 --> 00:17:30,480 Yes. 490 00:17:30,480 --> 00:17:32,080 It's a bit counterintuitive, but that's 491 00:17:32,080 --> 00:17:33,680 exactly what can happen. 492 00:17:33,680 --> 00:17:37,200 These outflows can regulate star formation in galaxies, 493 00:17:37,200 --> 00:17:40,120 preventing them from growing too large or forming stars 494 00:17:40,120 --> 00:17:40,920 too quickly. 495 00:17:40,920 --> 00:17:43,200 So in a way, supermassive black holes 496 00:17:43,200 --> 00:17:45,200 act as a kind of galactic thermostat, 497 00:17:45,200 --> 00:17:47,320 regulating the temperature and controlling the growth 498 00:17:47,320 --> 00:17:48,400 of their host galaxy. 499 00:17:48,400 --> 00:17:49,480 That's a great analogy. 500 00:17:49,480 --> 00:17:51,760 They can help to maintain a balance in the galaxy's 501 00:17:51,760 --> 00:17:52,640 ecosystem. 502 00:17:52,640 --> 00:17:55,160 It's incredible to think that these seemingly destructive 503 00:17:55,160 --> 00:17:58,900 objects can also play a vital role in shaping and regulating 504 00:17:58,900 --> 00:17:59,920 galaxies. 505 00:17:59,920 --> 00:18:01,720 It really highlights how interconnected 506 00:18:01,720 --> 00:18:03,720 the different components of a galaxy are. 507 00:18:03,720 --> 00:18:04,600 It does. 508 00:18:04,600 --> 00:18:07,040 From the stars and gas to the central black hole, 509 00:18:07,040 --> 00:18:11,040 everything is connected in a complex and dynamic system. 510 00:18:11,040 --> 00:18:12,920 And we are only beginning to understand 511 00:18:12,920 --> 00:18:14,520 all the intricate connections. 512 00:18:14,520 --> 00:18:16,140 Well, we've covered a lot of ground 513 00:18:16,140 --> 00:18:18,840 in this part of our discussion, from the aging of galaxies 514 00:18:18,840 --> 00:18:21,880 to the power of supermassive black holes. 515 00:18:21,880 --> 00:18:25,160 But there's still so much more to explore. 516 00:18:25,160 --> 00:18:26,720 What do you say we take a short break 517 00:18:26,720 --> 00:18:29,120 and then come back for the final part of our deep dive? 518 00:18:29,120 --> 00:18:30,720 Sounds like a plan. 519 00:18:30,720 --> 00:18:32,680 I'm eager to continue our exploration 520 00:18:32,680 --> 00:18:34,160 of these cosmic wonders. 521 00:18:34,160 --> 00:18:36,920 Welcome back to the final part of our deep dive 522 00:18:36,920 --> 00:18:37,840 into galaxies. 523 00:18:37,840 --> 00:18:38,840 The final part. 524 00:18:38,840 --> 00:18:41,420 It feels like we've journeyed through billions 525 00:18:41,420 --> 00:18:44,960 of years of cosmic history, exploring everything 526 00:18:44,960 --> 00:18:47,880 from their birth in the early universe 527 00:18:47,880 --> 00:18:50,800 to the powerful influence of supermassive black holes. 528 00:18:50,800 --> 00:18:52,080 We've covered a lot of ground. 529 00:18:52,080 --> 00:18:54,040 But just when you think you've grasped 530 00:18:54,040 --> 00:18:56,360 the scale of the universe, there's 531 00:18:56,360 --> 00:18:57,920 always another layer to uncover. 532 00:18:57,920 --> 00:18:59,120 You're right about that. 533 00:18:59,120 --> 00:19:01,580 And it brings to mind something I've been wondering about. 534 00:19:01,580 --> 00:19:05,280 We've talked extensively about how galaxies evolve over time. 535 00:19:05,280 --> 00:19:08,000 But what about the vast spaces between them? 536 00:19:08,000 --> 00:19:10,400 What's out there in those cosmic voids? 537 00:19:10,400 --> 00:19:12,040 It's a great question. 538 00:19:12,040 --> 00:19:15,080 It's easy to get caught up in the dazzling beauty of galaxies 539 00:19:15,080 --> 00:19:17,560 and forget about the seemingly empty spaces that 540 00:19:17,560 --> 00:19:18,960 surround them. 541 00:19:18,960 --> 00:19:22,280 But the truth is, those spaces, known 542 00:19:22,280 --> 00:19:25,640 as the intergalactic medium, aren't truly empty. 543 00:19:25,640 --> 00:19:28,160 So what fills these cosmic voids? 544 00:19:28,160 --> 00:19:32,080 They're primarily filled with gas, extremely thin and diffuse 545 00:19:32,080 --> 00:19:32,720 gas. 546 00:19:32,720 --> 00:19:33,920 But gas nonetheless. 547 00:19:33,920 --> 00:19:36,800 It's mainly hydrogen, the simplest and most abundant 548 00:19:36,800 --> 00:19:37,800 element in the universe. 549 00:19:37,800 --> 00:19:40,200 Is this gas just left over from the Big Bang? 550 00:19:40,200 --> 00:19:42,080 Some of it is, but other processes 551 00:19:42,080 --> 00:19:44,480 contribute to the intergalactic medium as well. 552 00:19:44,480 --> 00:19:46,320 For instance, as galaxies evolve, 553 00:19:46,320 --> 00:19:48,680 they can lose gas through galactic winds and supernova 554 00:19:48,680 --> 00:19:49,520 explosions. 555 00:19:49,520 --> 00:19:52,160 This gas can then escape into the intergalactic medium, 556 00:19:52,160 --> 00:19:54,280 enriching it with heavier elements. 557 00:19:54,280 --> 00:19:57,200 So it's like galaxies are constantly breathing, exhaling, 558 00:19:57,200 --> 00:19:59,240 and inhaling gas as they evolve. 559 00:19:59,240 --> 00:20:01,160 That's a great way to visualize it. 560 00:20:01,160 --> 00:20:04,080 The intergalactic medium is a dynamic environment 561 00:20:04,080 --> 00:20:06,480 with gas flowing between galaxies, 562 00:20:06,480 --> 00:20:09,240 enriching the cosmic soup and influencing the formation 563 00:20:09,240 --> 00:20:10,520 of new structures. 564 00:20:10,520 --> 00:20:14,560 This makes me wonder, could this intergalactic gas ever clump 565 00:20:14,560 --> 00:20:16,920 together and form new galaxies? 566 00:20:16,920 --> 00:20:18,560 It's certainly possible. 567 00:20:18,560 --> 00:20:21,520 We believe that some dwarf galaxies, smaller galaxies 568 00:20:21,520 --> 00:20:23,760 that often orbit larger ones, might 569 00:20:23,760 --> 00:20:27,120 have formed from gas clouds in the intergalactic medium. 570 00:20:27,120 --> 00:20:29,000 So even though the universe is expanding 571 00:20:29,000 --> 00:20:31,240 and galaxies are moving farther apart, 572 00:20:31,240 --> 00:20:33,280 there's still potential for new galaxies 573 00:20:33,280 --> 00:20:36,520 to emerge from the seemingly empty spaces between them. 574 00:20:36,520 --> 00:20:37,840 Exactly. 575 00:20:37,840 --> 00:20:39,600 The universe is full of surprises, 576 00:20:39,600 --> 00:20:43,600 and galaxy formation is a complex and ongoing process. 577 00:20:43,600 --> 00:20:45,400 Who knows what wonders are still waiting 578 00:20:45,400 --> 00:20:48,280 to be discovered in the vast expanse of the cosmos? 579 00:20:48,280 --> 00:20:50,720 That's what makes studying the universe so exciting. 580 00:20:50,720 --> 00:20:52,800 There's always something new to learn, always 581 00:20:52,800 --> 00:20:54,520 another mystery to unravel. 582 00:20:54,520 --> 00:20:58,280 This deep dive into the world of galaxies has been incredible. 583 00:20:58,280 --> 00:21:00,600 We've explored their formation, their evolution, 584 00:21:00,600 --> 00:21:03,400 their diversity, and the powerful forces that shape them. 585 00:21:03,400 --> 00:21:05,480 It's been a fascinating journey, hasn't it? 586 00:21:05,480 --> 00:21:07,800 From the first moments after the Big Bang 587 00:21:07,800 --> 00:21:09,680 to the intricate dance of galaxies 588 00:21:09,680 --> 00:21:12,840 across billions of years, it's a story that fills you 589 00:21:12,840 --> 00:21:14,240 with awe and wonder. 590 00:21:14,240 --> 00:21:15,720 It certainly does. 591 00:21:15,720 --> 00:21:17,160 And I hope our listeners have enjoyed 592 00:21:17,160 --> 00:21:19,920 exploring these cosmic wonders with us today. 593 00:21:19,920 --> 00:21:22,400 And remember, the exploration doesn't end here. 594 00:21:22,400 --> 00:21:25,080 Keep looking up, keep asking questions, 595 00:21:25,080 --> 00:21:27,680 and keep marveling at the beauty and complexity 596 00:21:27,680 --> 00:21:28,400 of the universe. 597 00:21:28,400 --> 00:21:29,400 Well said. 598 00:21:29,400 --> 00:21:31,560 There's always something new to discover, always 599 00:21:31,560 --> 00:21:32,960 another question to ask. 600 00:21:32,960 --> 00:21:35,600 The universe is an endless source of fascination 601 00:21:35,600 --> 00:21:36,840 and inspiration. 602 00:21:36,840 --> 00:21:37,680 Absolutely. 603 00:21:37,680 --> 00:21:39,040 And for our listeners, don't forget 604 00:21:39,040 --> 00:21:41,800 to follow and subscribe to the podcast for more deep dives 605 00:21:41,800 --> 00:21:43,400 into fascinating topics. 606 00:21:43,400 --> 00:21:59,040 Until next time, keep exploring.