1 00:00:00,000 --> 00:00:02,800 Welcome to Cosmos in a Pod, Space, and Astronomy series, 2 00:00:02,800 --> 00:00:04,640 episode 13. 3 00:00:04,640 --> 00:00:07,200 Today we're going on a deep dive into a force that's 4 00:00:07,200 --> 00:00:09,400 been shaping our universe since, well, 5 00:00:09,400 --> 00:00:12,320 since the very beginning, gravity. 6 00:00:12,320 --> 00:00:16,480 Get ready to uncover the mysteries of this invisible 7 00:00:16,480 --> 00:00:19,920 force, from why things fall down to the ground 8 00:00:19,920 --> 00:00:22,400 to how it sculpts galaxies, even creates 9 00:00:22,400 --> 00:00:24,240 those crazy black holes. 10 00:00:24,240 --> 00:00:26,280 So let's start with the basics. 11 00:00:26,280 --> 00:00:28,480 What exactly is gravity? 12 00:00:28,480 --> 00:00:29,940 I mean, we experience it every day, 13 00:00:29,940 --> 00:00:31,120 but what's the science behind it? 14 00:00:31,120 --> 00:00:33,360 Gravity is one of the fundamental forces of nature, 15 00:00:33,360 --> 00:00:34,800 and it's all about attraction. 16 00:00:34,800 --> 00:00:36,640 You know, any two objects with mass, 17 00:00:36,640 --> 00:00:37,840 they pull towards each other. 18 00:00:37,840 --> 00:00:40,320 Like me and this giant burrito I'm about to devour. 19 00:00:40,320 --> 00:00:41,360 Exactly. 20 00:00:41,360 --> 00:00:43,920 But on a much larger scale, right, you and the Earth 21 00:00:43,920 --> 00:00:45,480 are constantly pulling towards each other. 22 00:00:45,480 --> 00:00:45,960 Oh, OK. 23 00:00:45,960 --> 00:00:47,720 The Earth, being much more massive, 24 00:00:47,720 --> 00:00:51,040 wins that tug of war, which is why, well, 25 00:00:51,040 --> 00:00:52,320 which is why you stay grounded. 26 00:00:52,320 --> 00:00:54,560 OK, so that explains why things fall down. 27 00:00:54,560 --> 00:00:56,980 But I remember learning about Newton's apple 28 00:00:56,980 --> 00:00:58,360 and his law of gravity. 29 00:00:58,360 --> 00:00:59,280 How does that fit in? 30 00:00:59,280 --> 00:01:00,680 Newton's law of gravity? 31 00:01:00,680 --> 00:01:02,240 That was a huge breakthrough. 32 00:01:02,240 --> 00:01:05,040 He figured out the strength of this gravitational pull, 33 00:01:05,040 --> 00:01:06,800 it depends on two things. 34 00:01:06,800 --> 00:01:10,160 The mass of the objects and the distance between them, 35 00:01:10,160 --> 00:01:13,440 the more massive the objects and the closer they are, 36 00:01:13,440 --> 00:01:14,880 the stronger the attraction. 37 00:01:14,880 --> 00:01:17,760 So a bowling ball would have a stronger gravitational pull 38 00:01:17,760 --> 00:01:18,600 than a tennis ball. 39 00:01:18,600 --> 00:01:19,800 Precisely. 40 00:01:19,800 --> 00:01:21,720 And the closer you are to an object, 41 00:01:21,720 --> 00:01:24,240 the stronger its pull. 42 00:01:24,240 --> 00:01:26,320 That's why you feel Earth's gravity more strongly 43 00:01:26,320 --> 00:01:29,440 than the sun's, even though the sun is way more massive. 44 00:01:29,440 --> 00:01:29,960 Makes sense. 45 00:01:29,960 --> 00:01:33,080 But didn't Einstein come along and change 46 00:01:33,080 --> 00:01:35,680 our understanding of gravity with his theory of relativity? 47 00:01:35,680 --> 00:01:36,640 He sure did. 48 00:01:36,640 --> 00:01:39,440 Einstein took our understanding of gravity to a whole new level, 49 00:01:39,440 --> 00:01:40,200 yeah. 50 00:01:40,200 --> 00:01:42,400 He said that gravity isn't just a force, 51 00:01:42,400 --> 00:01:44,840 but a warp in the fabric of spacetime 52 00:01:44,840 --> 00:01:46,200 caused by massive objects. 53 00:01:46,200 --> 00:01:46,800 Hold on. 54 00:01:46,800 --> 00:01:48,560 Warp in spacetime. 55 00:01:48,560 --> 00:01:51,040 That sounds a bit like science fiction. 56 00:01:51,040 --> 00:01:51,520 I know. 57 00:01:51,520 --> 00:01:52,760 It's mind-bending. 58 00:01:52,760 --> 00:01:53,760 Think of it this way. 59 00:01:53,760 --> 00:01:58,560 Imagine a stretched out sheet, like a trampoline. 60 00:01:58,560 --> 00:02:01,800 If you place a bowling ball in the center, it creates a dip. 61 00:02:01,800 --> 00:02:05,240 That's similar to how massive objects like stars and planets 62 00:02:05,240 --> 00:02:06,200 warp spacetime. 63 00:02:06,200 --> 00:02:09,440 So smaller objects are drawn towards those dips. 64 00:02:09,440 --> 00:02:10,480 Exactly. 65 00:02:10,480 --> 00:02:13,240 It's not that objects are attracted to each other 66 00:02:13,240 --> 00:02:14,280 in the traditional sense. 67 00:02:14,280 --> 00:02:17,360 Instead, they're following the curves in spacetime created 68 00:02:17,360 --> 00:02:19,480 by these massive objects. 69 00:02:19,480 --> 00:02:23,080 But gravity is more like following a cosmic roadmap 70 00:02:23,080 --> 00:02:25,320 than being pulled by an invisible force. 71 00:02:25,320 --> 00:02:26,600 That's a great way to put it. 72 00:02:26,600 --> 00:02:28,280 And this warping of spacetime is what 73 00:02:28,280 --> 00:02:31,360 causes those familiar effects of gravity, 74 00:02:31,360 --> 00:02:33,480 like objects falling to the ground 75 00:02:33,480 --> 00:02:35,200 or planets orbiting stars. 76 00:02:35,200 --> 00:02:35,840 OK. 77 00:02:35,840 --> 00:02:37,160 I think I'm starting to wrap my head around that. 78 00:02:37,160 --> 00:02:38,520 But let's zoom out a bit. 79 00:02:38,520 --> 00:02:41,880 How did gravity shape the early universe after the Big Bang? 80 00:02:41,880 --> 00:02:46,400 Well, imagine the early universe as this hot, dense soup 81 00:02:46,400 --> 00:02:48,120 of particles and energy. 82 00:02:48,120 --> 00:02:50,360 There were tiny random fluctuations 83 00:02:50,360 --> 00:02:52,520 in the density of this soup. 84 00:02:52,520 --> 00:02:54,080 Like little clumps in the cosmic soup. 85 00:02:54,080 --> 00:02:54,800 Exactly. 86 00:02:54,800 --> 00:02:57,320 And over time, gravity acted on those clumps, 87 00:02:57,320 --> 00:02:59,320 pulling more and more matter towards them. 88 00:02:59,320 --> 00:03:00,920 It's like those tiny clumps acted 89 00:03:00,920 --> 00:03:05,040 as seeds for the formation of the first stars and galaxies. 90 00:03:05,040 --> 00:03:07,800 So gravity was kind of like a cosmic sculptor, 91 00:03:07,800 --> 00:03:10,440 shaping the universe into the structures we see today. 92 00:03:10,440 --> 00:03:12,080 That's a great analogy. 93 00:03:12,080 --> 00:03:14,440 But there's another key ingredient 94 00:03:14,440 --> 00:03:17,160 in this cosmic recipe, dark matter. 95 00:03:17,160 --> 00:03:20,680 Dark matter, the universe's biggest mystery. 96 00:03:20,680 --> 00:03:23,440 What does it have to do with gravity? 97 00:03:23,440 --> 00:03:25,960 Dark matter is a mysterious substance 98 00:03:25,960 --> 00:03:28,440 that we can't see directly. 99 00:03:28,440 --> 00:03:31,680 But we know it exists because of its gravitational effects. 100 00:03:31,680 --> 00:03:33,680 It's like an invisible scaffolding 101 00:03:33,680 --> 00:03:35,680 that helped gravity pull matter together 102 00:03:35,680 --> 00:03:36,920 in the early universe. 103 00:03:36,920 --> 00:03:39,080 So even though we can't see it, dark matter 104 00:03:39,080 --> 00:03:43,360 played a crucial role in shaping the universe we see today. 105 00:03:43,360 --> 00:03:44,000 Absolutely. 106 00:03:44,000 --> 00:03:46,560 Without dark matter, galaxies wouldn't have formed as quickly 107 00:03:46,560 --> 00:03:47,400 or in the same way. 108 00:03:47,400 --> 00:03:49,920 It's a testament to the power of gravity. 109 00:03:49,920 --> 00:03:53,680 And the unseen forces at work in the cosmos. 110 00:03:53,680 --> 00:03:55,640 This is incredible. 111 00:03:55,640 --> 00:03:57,640 So gravity is responsible for bringing all this matter 112 00:03:57,640 --> 00:03:58,840 together. 113 00:03:58,840 --> 00:04:00,760 But how does it actually ignite stars? 114 00:04:00,760 --> 00:04:02,000 I mean, what makes them shine? 115 00:04:02,000 --> 00:04:04,800 Imagine those giant clouds of gas and dust 116 00:04:04,800 --> 00:04:05,760 we talked about earlier. 117 00:04:05,760 --> 00:04:08,200 As gravity pulls them inward, those clouds 118 00:04:08,200 --> 00:04:11,520 start to collapse under their own weight. 119 00:04:11,520 --> 00:04:13,840 It's like squeezing a giant cosmic balloon. 120 00:04:13,840 --> 00:04:14,680 Sort of. 121 00:04:14,680 --> 00:04:17,280 As the cloud collapses, the pressure and temperature 122 00:04:17,280 --> 00:04:20,160 at its core increase dramatically. 123 00:04:20,160 --> 00:04:22,400 Eventually, it gets so hot and dense 124 00:04:22,400 --> 00:04:25,120 that nuclear fusion ignites. 125 00:04:25,120 --> 00:04:26,520 Nuclear fusion. 126 00:04:26,520 --> 00:04:27,720 That sounds intense. 127 00:04:27,720 --> 00:04:28,240 It is. 128 00:04:28,240 --> 00:04:31,240 That's the process where hydrogen atoms fuse together 129 00:04:31,240 --> 00:04:35,040 to form helium, releasing tremendous amounts of energy 130 00:04:35,040 --> 00:04:35,720 in the process. 131 00:04:35,720 --> 00:04:37,920 That energy, that's what makes stars shine. 132 00:04:37,920 --> 00:04:38,440 Wow. 133 00:04:38,440 --> 00:04:40,920 So gravity is not only a sculptor, but also a starmaker. 134 00:04:40,920 --> 00:04:44,480 It triggers this incredible process that powers the stars. 135 00:04:44,480 --> 00:04:46,040 But what about the life cycle of a star? 136 00:04:46,040 --> 00:04:47,720 Does gravity play a role there, too? 137 00:04:47,720 --> 00:04:48,440 Absolutely. 138 00:04:48,440 --> 00:04:52,280 Gravity is a key player in the entire life story of a star, 139 00:04:52,280 --> 00:04:56,000 from its birth to its eventual demise. 140 00:04:56,000 --> 00:04:59,800 A star's mass, which determines its gravitational pull, 141 00:04:59,800 --> 00:05:01,920 dictates how it will live, how long it will shine, 142 00:05:01,920 --> 00:05:04,200 and how it will eventually die. 143 00:05:04,200 --> 00:05:07,640 So a star's fate is sealed from the moment it's born, 144 00:05:07,640 --> 00:05:08,720 all thanks to gravity. 145 00:05:08,720 --> 00:05:09,360 You got it. 146 00:05:09,360 --> 00:05:13,480 It's like gravity sets the stage for this incredible cosmic 147 00:05:13,480 --> 00:05:14,240 drama. 148 00:05:14,240 --> 00:05:18,000 Now let's shift our focus to something a bit closer to home. 149 00:05:18,000 --> 00:05:19,720 Our solar system, how does gravity 150 00:05:19,720 --> 00:05:21,520 keep everything in order here? 151 00:05:21,520 --> 00:05:25,280 Our solar system is a beautiful example of gravity's 152 00:05:25,280 --> 00:05:26,600 orchestrating power. 153 00:05:26,600 --> 00:05:30,280 It's the reason why planets, moons, and asteroids all orbit 154 00:05:30,280 --> 00:05:32,640 the sun in a delicate balance. 155 00:05:32,640 --> 00:05:35,160 Sounds like a cosmic ballet with gravity as the choreographer. 156 00:05:35,160 --> 00:05:35,660 Exactly. 157 00:05:35,660 --> 00:05:37,560 The sun's immense gravitational pull 158 00:05:37,560 --> 00:05:41,200 keeps all the planets in our solar system bound to it, 159 00:05:41,200 --> 00:05:43,360 influencing their orbits and movements. 160 00:05:43,360 --> 00:05:45,640 But it's not just the sun calling the shots, right? 161 00:05:45,640 --> 00:05:48,280 Don't the planets also influence each other? 162 00:05:48,280 --> 00:05:49,360 You're absolutely right. 163 00:05:49,360 --> 00:05:52,200 While the sun's gravity is the dominant force, 164 00:05:52,200 --> 00:05:55,720 the planets also exert their own gravitational pulls 165 00:05:55,720 --> 00:05:56,600 on each other. 166 00:05:56,600 --> 00:05:59,400 These interactions between planets 167 00:05:59,400 --> 00:06:02,920 help stabilize the entire system over billions of years. 168 00:06:02,920 --> 00:06:06,800 It's like a giant cosmic mobile with everything 169 00:06:06,800 --> 00:06:09,640 cofically balanced, thanks to gravity. 170 00:06:09,640 --> 00:06:12,520 But I have a feeling gravity's influence goes even further, 171 00:06:12,520 --> 00:06:14,720 beyond our solar system. 172 00:06:14,720 --> 00:06:15,800 You're on the right track. 173 00:06:15,800 --> 00:06:18,400 Gravity's reach extends far beyond our solar system, 174 00:06:18,400 --> 00:06:20,800 shaping the vast structures of galaxies 175 00:06:20,800 --> 00:06:23,320 and even influencing the fate of the entire universe. 176 00:06:23,320 --> 00:06:24,800 This is blowing my mind. 177 00:06:24,800 --> 00:06:28,840 I can't wait to dive deeper into those cosmic mysteries. 178 00:06:28,840 --> 00:06:30,920 But before we get lost in the vastness of space, 179 00:06:30,920 --> 00:06:32,320 let's take a quick pause. 180 00:06:32,320 --> 00:06:35,400 When we come back, we'll explore how gravity shapes galaxies, 181 00:06:35,400 --> 00:06:38,000 unravel the mysteries of black holes, 182 00:06:38,000 --> 00:06:41,920 and even ponder the ultimate fate of the universe. 183 00:06:41,920 --> 00:06:43,440 Stay tuned. 184 00:06:43,440 --> 00:06:46,240 Welcome back to Cosmos in a Pod. 185 00:06:46,240 --> 00:06:47,720 We've been on quite a ride exploring 186 00:06:47,720 --> 00:06:51,120 the power of gravity, from falling apples 187 00:06:51,120 --> 00:06:52,200 to the birth of stars. 188 00:06:52,200 --> 00:06:54,520 But now let's venture even further into the cosmos 189 00:06:54,520 --> 00:06:57,280 and see how this fundamental force shapes 190 00:06:57,280 --> 00:06:59,840 galaxies and beyond. 191 00:06:59,840 --> 00:07:03,400 Galaxies are these vast, vast collections of stars, gas, 192 00:07:03,400 --> 00:07:06,240 dust, and of course, dark matter, all held together 193 00:07:06,240 --> 00:07:07,840 by, you guessed it, gravity. 194 00:07:07,840 --> 00:07:09,680 Even on a galactic scale, gravity 195 00:07:09,680 --> 00:07:11,640 is the glue that holds everything together. 196 00:07:11,640 --> 00:07:15,080 Absolutely, but it's not just about holding things in place. 197 00:07:15,080 --> 00:07:18,160 Gravity also sculpts galaxies into those stunning 198 00:07:18,160 --> 00:07:19,240 shapes we observe. 199 00:07:19,240 --> 00:07:22,360 So how does gravity turn like a giant cloud 200 00:07:22,360 --> 00:07:26,080 of cosmic ingredients into these magnificent structures? 201 00:07:26,080 --> 00:07:29,640 Well, let's start with spiral galaxies, like our own Milky 202 00:07:29,640 --> 00:07:30,120 Way. 203 00:07:30,120 --> 00:07:33,360 Imagine a giant disk of stars and gas 204 00:07:33,360 --> 00:07:35,880 rotating gracefully in space. 205 00:07:35,880 --> 00:07:38,040 Gravity pulls everything inward, 206 00:07:38,040 --> 00:07:42,440 while the rotation flings things outward, creates a delicate 207 00:07:42,440 --> 00:07:44,400 balance that leads to the formation 208 00:07:44,400 --> 00:07:47,080 of those iconic spiral arms. 209 00:07:47,080 --> 00:07:49,600 Like a cosmic dance floor, with gravity 210 00:07:49,600 --> 00:07:53,680 setting the rhythm and the rotation, adding a twirl. 211 00:07:53,680 --> 00:07:56,680 But what about those galaxies that aren't spirals? 212 00:07:56,680 --> 00:07:57,880 Right, right. 213 00:07:57,880 --> 00:08:00,560 There are also elliptical galaxies, 214 00:08:00,560 --> 00:08:04,440 which are more rounded and less structured than spirals. 215 00:08:04,440 --> 00:08:08,120 These often form from the collision of two or more spiral 216 00:08:08,120 --> 00:08:08,640 galaxies. 217 00:08:08,640 --> 00:08:10,880 Galactic collisions, that sounds intense. 218 00:08:10,880 --> 00:08:11,440 They are. 219 00:08:11,440 --> 00:08:15,040 Imagine two galaxies, each with billions of stars, 220 00:08:15,040 --> 00:08:18,640 drawn together by their mutual gravitational attraction. 221 00:08:18,640 --> 00:08:21,840 As they get closer, their shapes distort. 222 00:08:21,840 --> 00:08:24,000 Stars get flung around. 223 00:08:24,000 --> 00:08:28,040 And eventually, they merge into a single, more massive elliptical 224 00:08:28,040 --> 00:08:28,800 galaxy. 225 00:08:28,800 --> 00:08:30,560 So gravity is not just a sculptor. 226 00:08:30,560 --> 00:08:33,120 It's also like a cosmic matchmaker, 227 00:08:33,120 --> 00:08:36,240 bringing galaxies together in these dramatic mergers. 228 00:08:36,240 --> 00:08:36,840 Exactly. 229 00:08:36,840 --> 00:08:38,520 And the story doesn't end there. 230 00:08:38,520 --> 00:08:42,120 Gravity connects galaxies into even larger structures, 231 00:08:42,120 --> 00:08:45,400 called galaxy clusters, which contain hundreds or even 232 00:08:45,400 --> 00:08:47,160 thousands of galaxies bound together 233 00:08:47,160 --> 00:08:49,840 by their mutual gravitational attraction. 234 00:08:49,840 --> 00:08:50,920 Wow. 235 00:08:50,920 --> 00:08:54,440 So we have galaxies then clusters of galaxies. 236 00:08:54,440 --> 00:08:58,600 Is there an even bigger picture to this cosmic tapestry? 237 00:08:58,600 --> 00:08:59,360 There is. 238 00:08:59,360 --> 00:09:01,160 Zoom out even further, and you see 239 00:09:01,160 --> 00:09:04,600 that gravity has woven these galaxies and clusters 240 00:09:04,600 --> 00:09:09,080 into a vast cosmic web, a network of filaments and voids 241 00:09:09,080 --> 00:09:12,320 that spans the observable universe. 242 00:09:12,320 --> 00:09:14,520 So gravity is responsible for organizing matter 243 00:09:14,520 --> 00:09:16,320 on a truly mind-boggling scale. 244 00:09:16,320 --> 00:09:16,800 OK. 245 00:09:16,800 --> 00:09:18,840 It's like the architect of the cosmos. 246 00:09:18,840 --> 00:09:22,680 But now I have to ask about the most extreme expressions 247 00:09:22,680 --> 00:09:24,520 of gravity, black holes. 248 00:09:24,520 --> 00:09:25,520 Black holes. 249 00:09:25,520 --> 00:09:27,720 These are regions of spacetime where 250 00:09:27,720 --> 00:09:30,480 gravity is so strong that nothing, not even light, 251 00:09:30,480 --> 00:09:31,160 can escape. 252 00:09:31,160 --> 00:09:35,200 They're like cosmic whirlpools warping spacetime 253 00:09:35,200 --> 00:09:36,960 to an extreme degree. 254 00:09:36,960 --> 00:09:38,720 They sound a bit terrifying. 255 00:09:38,720 --> 00:09:40,880 How do these gravity monsters form? 256 00:09:40,880 --> 00:09:44,880 Black holes form when massive stars collapse 257 00:09:44,880 --> 00:09:47,160 at the end of their lives. 258 00:09:47,160 --> 00:09:50,080 All that stellar material gets squeezed 259 00:09:50,080 --> 00:09:52,960 into an incredibly, incredibly small space, 260 00:09:52,960 --> 00:09:58,320 creating a region of immense density and gravitational pull. 261 00:09:58,320 --> 00:10:02,280 OK, so if nothing can escape a black hole, 262 00:10:02,280 --> 00:10:04,400 how do we even know they exist? 263 00:10:04,400 --> 00:10:06,520 We can't see black holes directly, 264 00:10:06,520 --> 00:10:10,520 but we can detect their presence through their effects 265 00:10:10,520 --> 00:10:11,440 on their surroundings. 266 00:10:11,440 --> 00:10:14,960 For example, we can observe stars orbiting 267 00:10:14,960 --> 00:10:17,680 around a seemingly empty space, which 268 00:10:17,680 --> 00:10:20,880 indicates the presence of a massive unseen object, 269 00:10:20,880 --> 00:10:21,440 a black hole. 270 00:10:21,440 --> 00:10:24,320 So it's like their gravitational signature gives them away. 271 00:10:24,320 --> 00:10:25,120 Precisely. 272 00:10:25,120 --> 00:10:27,280 And then there's another incredible phenomenon 273 00:10:27,280 --> 00:10:31,520 that confirms the existence of black holes, 274 00:10:31,520 --> 00:10:32,520 gravitational waves. 275 00:10:32,520 --> 00:10:33,320 Right. 276 00:10:33,320 --> 00:10:34,920 I remember we touched on those earlier. 277 00:10:34,920 --> 00:10:36,480 Remind me what those are all about. 278 00:10:36,480 --> 00:10:39,480 Imagine two black holes spiraling towards each other 279 00:10:39,480 --> 00:10:41,360 and eventually colliding. 280 00:10:41,360 --> 00:10:45,440 This cataclysmic event sends out ripples in spacetime, 281 00:10:45,440 --> 00:10:48,920 like waves spreading from a stone dropped in a pond. 282 00:10:48,920 --> 00:10:50,560 Those are gravitational waves. 283 00:10:50,560 --> 00:10:54,720 And they carry information about these violent cosmic events 284 00:10:54,720 --> 00:10:57,120 across vast distances. 285 00:10:57,120 --> 00:11:01,120 So we're essentially listening to the universe's most 286 00:11:01,120 --> 00:11:04,680 dramatic events thanks to these gravitational waves. 287 00:11:04,680 --> 00:11:05,840 That's exactly right. 288 00:11:05,840 --> 00:11:08,960 Detecting these waves was a huge breakthrough, 289 00:11:08,960 --> 00:11:12,080 providing direct evidence for the existence of black holes 290 00:11:12,080 --> 00:11:16,680 and confirming Einstein's predictions over a century ago. 291 00:11:16,680 --> 00:11:17,480 This is incredible. 292 00:11:17,480 --> 00:11:20,800 We've gone from apples falling from trees 293 00:11:20,800 --> 00:11:23,840 to the mind-bending reality of black holes 294 00:11:23,840 --> 00:11:25,600 and gravitational waves. 295 00:11:25,600 --> 00:11:29,280 But there's one more big question I have to ask. 296 00:11:29,280 --> 00:11:31,840 What do gravity tell us about the fate 297 00:11:31,840 --> 00:11:33,200 of the entire universe? 298 00:11:33,200 --> 00:11:35,640 That's the ultimate question, isn't it? 299 00:11:35,640 --> 00:11:39,320 Will the universe keep expanding forever? 300 00:11:39,320 --> 00:11:42,760 Or will gravity eventually pull everything back together 301 00:11:42,760 --> 00:11:45,160 in a big crunch? 302 00:11:45,160 --> 00:11:48,240 I guess we need to consult our cosmic crystal ball. 303 00:11:48,240 --> 00:11:50,160 Well, it's not that simple. 304 00:11:50,160 --> 00:11:53,480 The answer depends on the ongoing cosmic tug 305 00:11:53,480 --> 00:11:58,680 of war between gravity and another mysterious force, 306 00:11:58,680 --> 00:11:59,720 dark energy. 307 00:11:59,720 --> 00:12:00,240 Right. 308 00:12:00,240 --> 00:12:01,840 We talked about dark matter earlier. 309 00:12:01,840 --> 00:12:03,760 But this is dark energy. 310 00:12:03,760 --> 00:12:05,520 What's the difference? 311 00:12:05,520 --> 00:12:08,440 Think of dark matter as invisible scaffolding, 312 00:12:08,440 --> 00:12:12,040 adding to gravity's pull and helping to shape structures. 313 00:12:12,040 --> 00:12:13,880 Dark energy, on the other hand, is 314 00:12:13,880 --> 00:12:18,040 a force that seems to oppose gravity, 315 00:12:18,040 --> 00:12:21,880 causing the expansion of the universe to accelerate. 316 00:12:21,880 --> 00:12:25,800 So it's like a cosmic battle between these two forces. 317 00:12:25,800 --> 00:12:27,200 Who's going to win? 318 00:12:27,200 --> 00:12:28,840 That's the big mystery. 319 00:12:28,840 --> 00:12:32,920 The fate of the universe hangs in the balance. 320 00:12:32,920 --> 00:12:35,800 If dark energy continues to dominate, 321 00:12:35,800 --> 00:12:39,360 the universe will likely keep expanding forever, 322 00:12:39,360 --> 00:12:42,160 becoming colder and darker over time. 323 00:12:42,160 --> 00:12:44,800 But if gravity eventually wins out, 324 00:12:44,800 --> 00:12:47,280 it could slow down the expansion and eventually 325 00:12:47,280 --> 00:12:51,400 lead to a big crunch, where everything collapses back 326 00:12:51,400 --> 00:12:52,160 in on itself. 327 00:12:52,160 --> 00:12:53,440 Wow, that's heavy. 328 00:12:53,440 --> 00:12:58,240 So the future of the universe is still an open question, 329 00:12:58,240 --> 00:13:00,160 a cosmic cliffhanger. 330 00:13:00,160 --> 00:13:00,680 Absolutely. 331 00:13:00,680 --> 00:13:04,440 There's still so much we don't know about dark energy 332 00:13:04,440 --> 00:13:07,600 and the ultimate fate of the universe. 333 00:13:07,600 --> 00:13:08,600 But one thing's for sure. 334 00:13:08,600 --> 00:13:13,760 Gravity will continue to play a key role in this cosmic drama, 335 00:13:13,760 --> 00:13:16,640 shaping the universe for billions of years to come. 336 00:13:16,640 --> 00:13:20,520 This has been an amazing journey through the world of gravity 337 00:13:20,520 --> 00:13:24,120 from the everyday to the truly mind boggling. 338 00:13:24,120 --> 00:13:27,200 But before we get lost in the vastness of space, 339 00:13:27,200 --> 00:13:29,560 let's take a quick break. 340 00:13:29,560 --> 00:13:32,840 When we come back, we'll wrap up our exploration to gravity 341 00:13:32,840 --> 00:13:36,280 and leave you with some final thoughts to ponder. 342 00:13:36,280 --> 00:13:38,920 Stay tuned. 343 00:13:38,920 --> 00:13:41,080 Welcome back to Cosmos in a Pod. 344 00:13:41,080 --> 00:13:42,800 Well, we've been on quite an adventure, right, 345 00:13:42,800 --> 00:13:45,520 exploring this incredible force of gravity. 346 00:13:45,520 --> 00:13:46,800 Yeah, we certainly have. 347 00:13:46,800 --> 00:13:51,320 I mean, from its role in shaping galaxies to its influence 348 00:13:51,320 --> 00:13:55,160 on the fate of the entire universe, 349 00:13:55,160 --> 00:13:57,800 gravity is truly a force to be reckoned with. 350 00:13:57,800 --> 00:13:59,960 So as we wrap up our deep dive into gravity, 351 00:13:59,960 --> 00:14:04,160 what are some key takeaways that you think our listeners should 352 00:14:04,160 --> 00:14:05,000 hold onto? 353 00:14:05,000 --> 00:14:07,480 Well, I think the most important takeaway 354 00:14:07,480 --> 00:14:09,560 is that gravity is everywhere, right? 355 00:14:09,560 --> 00:14:10,760 And it affects everything. 356 00:14:10,760 --> 00:14:14,200 It's the invisible force that shapes our everyday experiences, 357 00:14:14,200 --> 00:14:17,720 like the way objects fall to the ground. 358 00:14:17,720 --> 00:14:22,120 And it also governs the grandest cosmic events, 359 00:14:22,120 --> 00:14:26,840 like the formation of stars in galaxies. 360 00:14:26,840 --> 00:14:31,000 It's amazing to think that this one force connects us 361 00:14:31,000 --> 00:14:33,040 to the entire universe. 362 00:14:33,040 --> 00:14:35,960 It's the smallest particles to the largest structures. 363 00:14:35,960 --> 00:14:36,680 Exactly. 364 00:14:36,680 --> 00:14:39,520 And another crucial point is that our understanding 365 00:14:39,520 --> 00:14:41,680 of gravity, it's evolved over time, right, 366 00:14:41,680 --> 00:14:45,080 from Newton's groundbreaking laws 367 00:14:45,080 --> 00:14:49,440 to Einstein's revolutionary theory of general relativity. 368 00:14:49,440 --> 00:14:53,000 Scientists have continuously refined our grasp 369 00:14:53,000 --> 00:14:54,720 of this fundamental force. 370 00:14:54,720 --> 00:14:57,280 And with new discoveries, like gravitational waves, 371 00:14:57,280 --> 00:14:59,600 we're still learning more about gravity 372 00:14:59,600 --> 00:15:01,960 and its incredible effects. 373 00:15:01,960 --> 00:15:02,480 Absolutely. 374 00:15:02,480 --> 00:15:06,560 The study of gravity is a journey of ongoing discovery. 375 00:15:06,560 --> 00:15:11,600 And each new finding, it opens up even more questions, 376 00:15:11,600 --> 00:15:12,560 and possibilities. 377 00:15:12,560 --> 00:15:14,960 So gravity is a story that's still 378 00:15:14,960 --> 00:15:18,760 being written, a cosmic mystery with many chapters 379 00:15:18,760 --> 00:15:20,240 yet to be revealed. 380 00:15:20,240 --> 00:15:21,560 That's a great way to put it. 381 00:15:21,560 --> 00:15:23,800 And what makes it so fascinating is 382 00:15:23,800 --> 00:15:27,360 that it leads us to ponder some of the biggest 383 00:15:27,360 --> 00:15:32,000 questions about existence, like how did the universe begin? 384 00:15:32,000 --> 00:15:33,120 How will it end? 385 00:15:33,120 --> 00:15:38,400 And what is our place in this grand cosmic scheme of things? 386 00:15:38,400 --> 00:15:42,440 Those are some truly profound questions that remind us 387 00:15:42,440 --> 00:15:46,360 of the vastness and the wonder of the universe. 388 00:15:46,360 --> 00:15:49,200 I think that's a perfect note to end on. 389 00:15:49,200 --> 00:15:51,400 Gravity isn't just a force. 390 00:15:51,400 --> 00:15:55,400 It's a reminder of our connection to the cosmos, 391 00:15:55,400 --> 00:15:57,680 a testament to the elegance and the mystery 392 00:15:57,680 --> 00:15:59,440 of the natural world. 393 00:15:59,440 --> 00:16:02,040 So the next time you feel your feet planted firmly 394 00:16:02,040 --> 00:16:06,600 on the ground or gaze up at a star-filled night sky, 395 00:16:06,600 --> 00:16:11,360 take a moment to appreciate the invisible hand of gravity 396 00:16:11,360 --> 00:16:12,400 at work. 397 00:16:12,400 --> 00:16:16,400 It's a force that shapes our world, our galaxy, 398 00:16:16,400 --> 00:16:19,280 and our entire universe. 399 00:16:19,280 --> 00:16:22,120 Thanks for joining us for this cosmic deep dive 400 00:16:22,120 --> 00:16:24,160 into the world of gravity. 401 00:16:24,160 --> 00:16:29,040 We hope you've enjoyed exploring this fundamental force with us. 402 00:16:29,040 --> 00:16:32,680 If you'd like to continue your exploration of the universe, 403 00:16:32,680 --> 00:16:36,080 don't forget to follow and subscribe to Cosmos in a Pod 404 00:16:36,080 --> 00:16:39,880 for more exciting adventures through space and time. 405 00:16:39,880 --> 00:16:42,680 Until next time, keep looking up and keep 406 00:16:42,680 --> 00:17:06,320 those questions coming.