1 00:00:00,000 --> 00:00:03,840 Imagine like stepping into some futuristic machine, right? 2 00:00:03,840 --> 00:00:04,920 You punch in a date. 3 00:00:04,920 --> 00:00:05,760 Oh yeah. 4 00:00:05,760 --> 00:00:08,120 And whoosh, you're just transported. 5 00:00:08,120 --> 00:00:08,960 To another time. 6 00:00:08,960 --> 00:00:09,780 To another time. 7 00:00:09,780 --> 00:00:12,700 Witnessing, I don't know, the pyramids being built maybe 8 00:00:12,700 --> 00:00:15,400 or having tea with like a future version of yourself. 9 00:00:15,400 --> 00:00:16,360 It's wild. 10 00:00:16,360 --> 00:00:17,200 Time travel. 11 00:00:17,200 --> 00:00:18,020 Yeah. 12 00:00:18,020 --> 00:00:18,860 The stuff of dreams. 13 00:00:18,860 --> 00:00:19,700 Oh sure. 14 00:00:19,700 --> 00:00:20,520 Sci-fi movies. 15 00:00:20,520 --> 00:00:21,360 Absolutely. 16 00:00:21,360 --> 00:00:22,760 And maybe, just maybe. 17 00:00:22,760 --> 00:00:23,600 Yeah. 18 00:00:23,600 --> 00:00:24,420 Real science. 19 00:00:24,420 --> 00:00:26,520 It's definitely one of those captivating ideas out there. 20 00:00:26,520 --> 00:00:27,360 Right. 21 00:00:27,360 --> 00:00:28,180 For sure. 22 00:00:28,180 --> 00:00:31,000 You know, we haven't exactly cracked the code. 23 00:00:31,000 --> 00:00:31,840 Yeah. 24 00:00:31,840 --> 00:00:34,240 To building, you know, an actual working time machine. 25 00:00:34,240 --> 00:00:35,080 Like. 26 00:00:35,080 --> 00:00:35,920 A working time machine. 27 00:00:35,920 --> 00:00:38,480 The idea itself, it's not totally crazy. 28 00:00:38,480 --> 00:00:39,420 No, not at all. 29 00:00:39,420 --> 00:00:40,960 It starts with Einstein, right? 30 00:00:40,960 --> 00:00:42,320 His theories of relativity. 31 00:00:42,320 --> 00:00:44,600 Those are like the rule book for how time works. 32 00:00:44,600 --> 00:00:45,980 That's so cool. 33 00:00:45,980 --> 00:00:48,880 Welcome to Cosmos in a Pond, our space and astronomy series. 34 00:00:48,880 --> 00:00:49,800 Glad to be here. 35 00:00:49,800 --> 00:00:53,120 Today, we're taking a deep dive into time travel. 36 00:00:53,120 --> 00:00:53,960 Okay. 37 00:00:53,960 --> 00:00:54,800 Is it pure fiction? 38 00:00:54,800 --> 00:00:55,620 Yeah. 39 00:00:55,620 --> 00:00:58,040 Or could physics actually allow this? 40 00:00:58,040 --> 00:01:02,240 So, to really kind of wrap your head around time travel, 41 00:01:02,240 --> 00:01:05,040 think of time like a river, right? 42 00:01:05,040 --> 00:01:06,200 It's constantly flowing. 43 00:01:06,200 --> 00:01:07,040 Yeah. 44 00:01:07,040 --> 00:01:09,560 We experience it as this straight path. 45 00:01:09,560 --> 00:01:10,400 Yeah. 46 00:01:10,400 --> 00:01:11,720 But Einstein showed that it can be warped, 47 00:01:11,720 --> 00:01:12,960 it can be stretched. 48 00:01:12,960 --> 00:01:13,800 Oh wow. 49 00:01:13,800 --> 00:01:16,600 Almost like, you know, a river bending around a mountain. 50 00:01:16,600 --> 00:01:18,840 So instead of a rigid, like, clock. 51 00:01:18,840 --> 00:01:19,680 Yeah. 52 00:01:19,680 --> 00:01:22,400 Time is more like this flexible dynamic kind of thing. 53 00:01:22,400 --> 00:01:23,280 Exactly. 54 00:01:23,280 --> 00:01:27,200 Now, there are two basic types of time travel. 55 00:01:27,200 --> 00:01:28,640 Forward and backward. 56 00:01:28,640 --> 00:01:29,880 Traveling to the future, 57 00:01:29,880 --> 00:01:31,960 that actually has some scientific backing. 58 00:01:31,960 --> 00:01:32,800 Really? 59 00:01:32,800 --> 00:01:35,840 Whereas going back in time, that's much more speculative. 60 00:01:35,840 --> 00:01:36,680 Okay. 61 00:01:36,680 --> 00:01:38,920 And honestly, just full of paradoxes. 62 00:01:38,920 --> 00:01:39,920 Paradoxes, yeah. 63 00:01:39,920 --> 00:01:41,360 Okay, so let's start with the future then. 64 00:01:41,360 --> 00:01:42,180 Sure. 65 00:01:42,180 --> 00:01:45,200 How can we possibly even travel, like, ahead in time? 66 00:01:45,200 --> 00:01:47,720 So the key is this thing called time dilation. 67 00:01:47,720 --> 00:01:48,560 Time dilation. 68 00:01:48,560 --> 00:01:49,760 Yeah, which comes directly 69 00:01:49,760 --> 00:01:51,520 from Einstein's special relativity. 70 00:01:51,520 --> 00:01:52,360 Okay. 71 00:01:52,360 --> 00:01:54,200 Imagine you have two identical clocks. 72 00:01:54,200 --> 00:01:55,020 Okay. 73 00:01:55,020 --> 00:01:56,400 One stays here on earth. 74 00:01:56,400 --> 00:01:57,240 Okay. 75 00:01:57,240 --> 00:01:58,880 The other one, we put it on a spaceship, 76 00:01:58,880 --> 00:02:02,120 and this spaceship travels at an incredibly high speed, 77 00:02:02,120 --> 00:02:03,800 close to the speed of light. 78 00:02:03,800 --> 00:02:04,640 Okay, wow. 79 00:02:04,640 --> 00:02:07,440 Now, when that spaceship gets back to earth, 80 00:02:07,440 --> 00:02:08,400 Yeah. 81 00:02:08,400 --> 00:02:10,280 the clock that was on the spaceship 82 00:02:10,280 --> 00:02:13,040 is going to show less time has passed. 83 00:02:13,040 --> 00:02:13,860 What? 84 00:02:13,860 --> 00:02:15,600 Compared to the clock that stayed here. 85 00:02:15,600 --> 00:02:16,920 So the clock on the spaceship 86 00:02:16,920 --> 00:02:18,720 literally traveled into the future. 87 00:02:18,720 --> 00:02:20,080 In a way, yes. 88 00:02:20,080 --> 00:02:20,920 Wow. 89 00:02:20,920 --> 00:02:22,520 The faster you move through space, 90 00:02:22,520 --> 00:02:23,340 Yeah. 91 00:02:23,340 --> 00:02:24,800 the slower time passes for you, 92 00:02:24,800 --> 00:02:26,840 relative to someone standing still. 93 00:02:26,840 --> 00:02:27,660 Okay. 94 00:02:27,660 --> 00:02:29,200 It's like taking a shortcut through time. 95 00:02:29,200 --> 00:02:30,040 That's wild. 96 00:02:30,040 --> 00:02:30,860 Right. 97 00:02:30,860 --> 00:02:33,280 But haven't we actually, like, seen this happen? 98 00:02:33,280 --> 00:02:34,120 We have. 99 00:02:34,120 --> 00:02:36,200 So astronauts on the International Space Station, 100 00:02:36,200 --> 00:02:37,040 Right. 101 00:02:37,040 --> 00:02:38,360 because they're orbiting earth at high speed. 102 00:02:38,360 --> 00:02:39,200 Okay. 103 00:02:39,200 --> 00:02:41,600 They actually age a tiny bit slower. 104 00:02:41,600 --> 00:02:42,440 Really? 105 00:02:42,440 --> 00:02:43,260 Than people on the ground. 106 00:02:43,260 --> 00:02:44,100 Wow. 107 00:02:44,100 --> 00:02:45,920 They're essentially time travelers, 108 00:02:45,920 --> 00:02:48,160 but just on a teeny tiny scale. 109 00:02:48,160 --> 00:02:50,240 So like, traveling to the future? 110 00:02:50,240 --> 00:02:51,080 Yeah. 111 00:02:51,080 --> 00:02:53,280 Even if it's just like a tiny bit, 112 00:02:53,280 --> 00:02:54,540 it's actually possible. 113 00:02:54,540 --> 00:02:56,080 It is, theoretically. 114 00:02:56,080 --> 00:02:56,900 Wow. 115 00:02:56,900 --> 00:02:59,880 But to really make these big jumps into the future, 116 00:02:59,880 --> 00:03:02,880 we'd have to hit those speeds close to the speed of light. 117 00:03:02,880 --> 00:03:03,720 Right. 118 00:03:03,720 --> 00:03:04,760 Which is a whole other challenge. 119 00:03:04,760 --> 00:03:05,720 It's a whole other thing, right. 120 00:03:05,720 --> 00:03:06,560 Right. 121 00:03:06,560 --> 00:03:07,560 Okay, that's forward time travel. 122 00:03:07,560 --> 00:03:08,400 Yeah. 123 00:03:08,400 --> 00:03:09,600 What about going back in time? 124 00:03:09,600 --> 00:03:10,440 Yeah. 125 00:03:10,440 --> 00:03:11,880 Is that even remotely possible? 126 00:03:11,880 --> 00:03:14,560 That's where things get really tricky. 127 00:03:14,560 --> 00:03:15,400 Okay. 128 00:03:15,400 --> 00:03:16,920 Both scientifically and philosophically. 129 00:03:16,920 --> 00:03:17,760 Okay. 130 00:03:17,760 --> 00:03:18,600 Traveling to the past, 131 00:03:18,600 --> 00:03:20,160 it's just riddled with paradoxes. 132 00:03:20,160 --> 00:03:21,520 They really make your head spin. 133 00:03:21,520 --> 00:03:22,360 Yeah. 134 00:03:22,360 --> 00:03:23,800 Imagine going back in time. 135 00:03:23,800 --> 00:03:24,640 Okay. 136 00:03:24,640 --> 00:03:27,040 And you accidentally stop your parents from ever meeting. 137 00:03:27,040 --> 00:03:27,880 Okay. 138 00:03:27,880 --> 00:03:29,120 If they never met, you wouldn't exist. 139 00:03:29,120 --> 00:03:29,960 Right. 140 00:03:29,960 --> 00:03:32,120 So how could you have gone back in time in the first place? 141 00:03:32,120 --> 00:03:34,320 That's like the classic grandfather paradox, right? 142 00:03:34,320 --> 00:03:35,640 Right, the grandfather paradox. 143 00:03:35,640 --> 00:03:37,200 It really makes your brain hurt a little bit. 144 00:03:37,200 --> 00:03:40,520 It does, and there are other types of paradoxes too. 145 00:03:40,520 --> 00:03:41,460 Oh, wow. 146 00:03:41,460 --> 00:03:44,900 But even if we just put those aside for a moment, 147 00:03:44,900 --> 00:03:47,960 the physics of backward time travel, 148 00:03:47,960 --> 00:03:49,760 it's much more speculative. 149 00:03:49,760 --> 00:03:53,200 Okay, so are there any actual scientific theories 150 00:03:53,200 --> 00:03:56,520 about how backward time travel might work? 151 00:03:56,520 --> 00:03:57,360 There are. 152 00:03:57,360 --> 00:03:58,200 Okay. 153 00:03:58,200 --> 00:04:00,280 But they all have major caveats. 154 00:04:00,280 --> 00:04:03,000 One idea involves wormholes. 155 00:04:03,000 --> 00:04:03,840 Wormholes? 156 00:04:03,840 --> 00:04:06,520 These theoretical tunnels through space-time. 157 00:04:06,520 --> 00:04:07,360 Okay. 158 00:04:07,360 --> 00:04:10,440 That could connect distant points in the universe. 159 00:04:10,440 --> 00:04:12,720 So like shortcuts through the fabric of reality. 160 00:04:12,720 --> 00:04:13,560 Exactly. 161 00:04:13,560 --> 00:04:14,380 Wow. 162 00:04:14,380 --> 00:04:16,400 Now, if one end of a wormhole 163 00:04:16,400 --> 00:04:19,460 were to experience really strong gravitational effects, 164 00:04:19,460 --> 00:04:21,840 like near a black hole, 165 00:04:21,840 --> 00:04:24,560 time would actually move slower at that end 166 00:04:24,560 --> 00:04:25,400 compared to the other. 167 00:04:25,400 --> 00:04:26,220 Really? 168 00:04:26,220 --> 00:04:28,280 And that difference in the flow of time 169 00:04:28,280 --> 00:04:30,680 that could, in theory, 170 00:04:30,680 --> 00:04:33,640 allow travel between different points in time. 171 00:04:33,640 --> 00:04:36,840 So you could potentially step into one end of a wormhole 172 00:04:36,840 --> 00:04:38,600 and come out the other end 173 00:04:38,600 --> 00:04:40,160 in a totally different time period. 174 00:04:40,160 --> 00:04:41,400 That's the idea. 175 00:04:41,400 --> 00:04:42,240 Wow. 176 00:04:42,240 --> 00:04:44,320 But there's some big ifs involved. 177 00:04:44,320 --> 00:04:47,480 For one, we're not even sure wormholes actually exist. 178 00:04:47,480 --> 00:04:49,440 You're purely theoretical at this point. 179 00:04:49,440 --> 00:04:51,200 And even if they do exist, 180 00:04:51,200 --> 00:04:54,040 they're thought to be unbelievably unstable. 181 00:04:54,040 --> 00:04:55,160 They would probably collapse 182 00:04:55,160 --> 00:04:56,740 before you could even get close. 183 00:04:56,740 --> 00:04:58,120 So it's not as simple as like 184 00:04:58,120 --> 00:05:00,020 hopping into a cosmic subway. 185 00:05:00,020 --> 00:05:00,860 Right. 186 00:05:00,860 --> 00:05:03,080 And just like choosing your destination year. 187 00:05:03,080 --> 00:05:03,920 Not quite. 188 00:05:03,920 --> 00:05:05,820 There are other wild theories out there too, 189 00:05:05,820 --> 00:05:07,520 like cosmic strings. 190 00:05:07,520 --> 00:05:08,440 Cosmic strings? 191 00:05:08,440 --> 00:05:10,000 Yeah, these super dense wrinkles 192 00:05:10,000 --> 00:05:11,480 in the fabric of space-time. 193 00:05:11,480 --> 00:05:12,320 Okay. 194 00:05:12,320 --> 00:05:13,640 Left over from the Big Bang. 195 00:05:13,640 --> 00:05:14,480 Oh, wow. 196 00:05:14,480 --> 00:05:16,000 They could potentially create 197 00:05:16,000 --> 00:05:18,960 what are called closed timelike curves. 198 00:05:18,960 --> 00:05:20,240 Closed timelike curves? 199 00:05:20,240 --> 00:05:22,320 Yeah, paths through space-time 200 00:05:22,320 --> 00:05:24,160 that loop back on themselves, 201 00:05:24,160 --> 00:05:26,060 allowing for backward time travel. 202 00:05:26,060 --> 00:05:28,720 So like wrinkles in the universe 203 00:05:28,720 --> 00:05:30,000 that act as time machines. 204 00:05:30,000 --> 00:05:31,000 That's one way to put it. 205 00:05:31,000 --> 00:05:31,820 Wow. 206 00:05:31,820 --> 00:05:32,660 Very simplified. 207 00:05:32,660 --> 00:05:35,240 But again, the existence of cosmic strings 208 00:05:35,240 --> 00:05:36,760 is completely hypothetical. 209 00:05:36,760 --> 00:05:37,600 Right. 210 00:05:37,600 --> 00:05:38,720 And even if we found one 211 00:05:38,720 --> 00:05:42,440 manipulating it to actually enable time travel, 212 00:05:42,440 --> 00:05:44,840 that would be something else entirely. 213 00:05:44,840 --> 00:05:46,840 Seems like every potential method, right? 214 00:05:46,840 --> 00:05:48,120 For backward time travel 215 00:05:48,120 --> 00:05:49,840 comes with a whole bunch of problems. 216 00:05:49,840 --> 00:05:50,680 It does. 217 00:05:50,680 --> 00:05:52,000 What about black holes? 218 00:05:52,000 --> 00:05:53,480 Don't they have something to do with time? 219 00:05:53,480 --> 00:05:56,440 They do, specifically rotating black holes. 220 00:05:56,440 --> 00:05:57,280 Okay. 221 00:05:57,280 --> 00:05:58,480 Known as Kerr black holes. 222 00:05:58,480 --> 00:05:59,320 Kerr black holes. 223 00:05:59,320 --> 00:06:01,200 So they spin so rapidly. 224 00:06:01,200 --> 00:06:02,040 Yeah. 225 00:06:02,040 --> 00:06:04,360 They could potentially create a time loop. 226 00:06:04,360 --> 00:06:05,200 Okay. 227 00:06:05,200 --> 00:06:06,760 Around their singularity. 228 00:06:06,760 --> 00:06:07,580 Oh, wow. 229 00:06:07,580 --> 00:06:09,160 In theory, if you entered this loop, 230 00:06:09,160 --> 00:06:11,600 it might allow for backward time travel. 231 00:06:11,600 --> 00:06:14,360 So you could like swirl around a black hole. 232 00:06:14,360 --> 00:06:15,200 Yeah. 233 00:06:15,200 --> 00:06:16,640 And end up back in the past. 234 00:06:16,640 --> 00:06:17,480 Potentially. 235 00:06:17,480 --> 00:06:19,180 Isn't that a bit risky? 236 00:06:19,180 --> 00:06:20,680 Risky is an understatement. 237 00:06:20,680 --> 00:06:21,520 Right. 238 00:06:21,520 --> 00:06:23,080 The gravity near a black hole. 239 00:06:23,080 --> 00:06:23,920 Yeah. 240 00:06:23,920 --> 00:06:26,040 It would crush anything that got too close. 241 00:06:26,040 --> 00:06:26,880 Okay. 242 00:06:26,880 --> 00:06:28,160 And even if you survived. 243 00:06:28,160 --> 00:06:29,000 Yeah. 244 00:06:29,000 --> 00:06:30,820 There's no guarantee you could escape the loop 245 00:06:30,820 --> 00:06:33,640 or even control where you ended up in the past. 246 00:06:33,640 --> 00:06:36,120 That sounds less like time travel. 247 00:06:36,120 --> 00:06:36,960 Right. 248 00:06:36,960 --> 00:06:40,120 And more like a cosmic suicide mission. 249 00:06:40,120 --> 00:06:41,720 Yeah, kinda. 250 00:06:41,720 --> 00:06:44,900 Okay, are there any other theoretical methods 251 00:06:44,900 --> 00:06:47,000 that are a little less extreme? 252 00:06:47,000 --> 00:06:48,160 One more intriguing idea 253 00:06:48,160 --> 00:06:50,240 is this thing called the Tipler cylinder. 254 00:06:50,240 --> 00:06:51,080 Tipler cylinder. 255 00:06:51,080 --> 00:06:53,520 So it's a hypothetical infinitely long. 256 00:06:53,520 --> 00:06:54,560 Infinitely long. 257 00:06:54,560 --> 00:06:55,800 Spinning cylinder. 258 00:06:55,800 --> 00:06:56,640 Okay. 259 00:06:56,640 --> 00:06:58,320 Made of incredibly dense matter. 260 00:06:58,320 --> 00:06:59,140 Okay. 261 00:06:59,140 --> 00:07:00,800 Now if you could build one of these. 262 00:07:00,800 --> 00:07:01,640 Yeah. 263 00:07:01,640 --> 00:07:03,120 And spin it fast enough. 264 00:07:03,120 --> 00:07:03,940 Okay. 265 00:07:03,940 --> 00:07:05,200 It would warp space time. 266 00:07:05,200 --> 00:07:06,040 Right. 267 00:07:06,040 --> 00:07:08,120 Enough to potentially create a pathway for time travel. 268 00:07:08,120 --> 00:07:10,280 An infinitely long cylinder. 269 00:07:10,280 --> 00:07:11,120 Yeah. 270 00:07:11,120 --> 00:07:11,960 That sounds. 271 00:07:11,960 --> 00:07:12,900 It's out there. 272 00:07:12,900 --> 00:07:14,240 A bit ambitious. 273 00:07:14,240 --> 00:07:15,760 Even for theoretical physics. 274 00:07:15,760 --> 00:07:17,040 It really pushes the limits 275 00:07:17,040 --> 00:07:18,960 of what we can even imagine. 276 00:07:18,960 --> 00:07:20,280 Let alone build. 277 00:07:20,280 --> 00:07:21,120 Right. 278 00:07:21,120 --> 00:07:22,320 And that's actually a common thread 279 00:07:22,320 --> 00:07:24,880 running through all these theoretical methods. 280 00:07:24,880 --> 00:07:27,380 They need stuff we've never even seen. 281 00:07:27,380 --> 00:07:31,360 Like exotic matter with negative energy. 282 00:07:31,360 --> 00:07:34,960 Or technologies way beyond what we can do right now. 283 00:07:34,960 --> 00:07:35,800 Right. 284 00:07:35,800 --> 00:07:36,620 Like way beyond. 285 00:07:36,620 --> 00:07:37,460 Yeah. 286 00:07:37,460 --> 00:07:39,320 Yeah, we're talking about manipulating 287 00:07:39,320 --> 00:07:41,600 the very fabric of space time. 288 00:07:41,600 --> 00:07:42,440 Right. 289 00:07:42,440 --> 00:07:45,200 A feat that would need just an unbelievable level 290 00:07:45,200 --> 00:07:48,400 of understanding and control of the whole universe. 291 00:07:48,400 --> 00:07:51,200 It does seem like the more we go into backward time travel, 292 00:07:51,200 --> 00:07:52,360 the more questions we have. 293 00:07:52,360 --> 00:07:53,200 Exactly. 294 00:07:53,200 --> 00:07:55,560 And some of those questions go way beyond just physics. 295 00:07:55,560 --> 00:07:56,400 Really? 296 00:07:56,400 --> 00:07:58,160 Yeah, they go into the realm of philosophy. 297 00:07:58,160 --> 00:07:58,980 Oh wow. 298 00:07:58,980 --> 00:08:00,960 For example, the whole concept of time travel 299 00:08:00,960 --> 00:08:03,720 makes us rethink the idea of causality. 300 00:08:03,720 --> 00:08:04,560 Causality. 301 00:08:04,560 --> 00:08:07,400 The notion that a cause always comes before an effect. 302 00:08:07,400 --> 00:08:08,240 Okay, right. 303 00:08:08,240 --> 00:08:09,760 So like the classic example. 304 00:08:09,760 --> 00:08:10,600 Yeah. 305 00:08:10,600 --> 00:08:12,480 A butterfly flaps its wings in Brazil. 306 00:08:12,480 --> 00:08:13,400 Right. 307 00:08:13,400 --> 00:08:17,080 And it can eventually cause like a hurricane in Florida. 308 00:08:17,080 --> 00:08:17,920 Precisely. 309 00:08:17,920 --> 00:08:18,740 You mean? 310 00:08:18,740 --> 00:08:20,920 But if we could travel back in time, 311 00:08:20,920 --> 00:08:23,800 wouldn't we be able to mess with that whole chain 312 00:08:23,800 --> 00:08:25,000 of cause and effect. 313 00:08:25,000 --> 00:08:25,840 Yeah. 314 00:08:25,840 --> 00:08:27,400 And create all sorts of crazy consequences. 315 00:08:27,400 --> 00:08:29,580 It's like time travel throws a wrench 316 00:08:29,580 --> 00:08:31,200 into the very order of the universe. 317 00:08:31,200 --> 00:08:32,400 In a way it does. 318 00:08:32,400 --> 00:08:35,760 It challenges our whole understanding of how time flows 319 00:08:35,760 --> 00:08:37,520 and how events actually happen. 320 00:08:37,520 --> 00:08:38,340 Okay. 321 00:08:38,340 --> 00:08:40,520 And that leads to another really interesting concept, 322 00:08:40,520 --> 00:08:42,120 the arrow of time. 323 00:08:42,120 --> 00:08:43,280 The arrow of time. 324 00:08:43,280 --> 00:08:45,960 Why does time seem to only move in one direction? 325 00:08:45,960 --> 00:08:47,340 Right, from past to future. 326 00:08:47,340 --> 00:08:48,180 Exactly. 327 00:08:48,180 --> 00:08:49,840 And this idea is really closely tied 328 00:08:49,840 --> 00:08:51,480 to this concept of entropy. 329 00:08:51,480 --> 00:08:52,320 Entropy. 330 00:08:52,320 --> 00:08:55,120 Which basically says that disorder in the universe 331 00:08:55,120 --> 00:08:56,300 always increases. 332 00:08:56,300 --> 00:09:00,080 So like, you know, if you drop a glass 333 00:09:00,080 --> 00:09:01,880 and it shatters into a million pieces, 334 00:09:01,880 --> 00:09:04,080 it's not just gonna suddenly reassemble itself. 335 00:09:04,080 --> 00:09:04,920 Exactly. 336 00:09:04,920 --> 00:09:06,360 Entropy like keeps things moving in one direction. 337 00:09:06,360 --> 00:09:07,200 Exactly. 338 00:09:07,200 --> 00:09:10,040 But time travel, especially going back in time, 339 00:09:10,040 --> 00:09:12,000 seems to go against this whole principle. 340 00:09:12,000 --> 00:09:12,840 Right. 341 00:09:12,840 --> 00:09:14,720 That it's just move around freely in time. 342 00:09:14,720 --> 00:09:15,560 Yeah. 343 00:09:15,560 --> 00:09:18,080 Wouldn't that like mess with the arrow of time 344 00:09:18,080 --> 00:09:21,080 and create just absolute causal chaos? 345 00:09:21,080 --> 00:09:23,760 And like time travel could just like unravel 346 00:09:23,760 --> 00:09:25,080 the fabric of reality. 347 00:09:25,080 --> 00:09:27,120 Yeah, and that's a concern. 348 00:09:27,120 --> 00:09:27,960 Yeah. 349 00:09:27,960 --> 00:09:29,840 Many physicists and philosophers have thought about. 350 00:09:29,840 --> 00:09:30,680 Right. 351 00:09:30,680 --> 00:09:33,080 But there are some theories that try to reconcile 352 00:09:33,080 --> 00:09:35,160 time travel with this arrow of time. 353 00:09:35,160 --> 00:09:36,000 Okay. 354 00:09:36,000 --> 00:09:37,400 And one of the most fascinating ones. 355 00:09:37,400 --> 00:09:38,240 Yeah. 356 00:09:38,240 --> 00:09:39,720 Is this idea of the multiverse. 357 00:09:39,720 --> 00:09:40,560 The multiverse. 358 00:09:40,560 --> 00:09:42,440 So not just one universe. 359 00:09:42,440 --> 00:09:43,280 Yeah. 360 00:09:43,280 --> 00:09:44,120 But many. 361 00:09:44,120 --> 00:09:44,960 Oh wow. 362 00:09:44,960 --> 00:09:47,000 Yeah, some theories suggest that time travel 363 00:09:47,000 --> 00:09:49,600 doesn't actually change the past in our own timeline. 364 00:09:49,600 --> 00:09:50,440 Okay. 365 00:09:50,440 --> 00:09:51,760 Instead, it makes a split. 366 00:09:51,760 --> 00:09:52,600 Okay. 367 00:09:52,600 --> 00:09:53,800 It creates this branching off point 368 00:09:53,800 --> 00:09:56,920 where a new parallel universe is born. 369 00:09:56,920 --> 00:09:57,760 Really? 370 00:09:57,760 --> 00:09:59,360 With a different version of those events. 371 00:09:59,360 --> 00:10:01,680 So instead of like rewriting our own history. 372 00:10:01,680 --> 00:10:02,520 Yeah. 373 00:10:02,520 --> 00:10:05,520 We'd be creating completely new universes. 374 00:10:05,520 --> 00:10:06,880 With different timelines. 375 00:10:06,880 --> 00:10:07,720 That's the idea. 376 00:10:07,720 --> 00:10:10,800 It's like having infinite parallel worlds. 377 00:10:10,800 --> 00:10:11,640 Wow. 378 00:10:11,640 --> 00:10:13,840 And then having our own unique set of events happening. 379 00:10:13,840 --> 00:10:14,680 Okay. 380 00:10:14,680 --> 00:10:17,800 What we do in the past wouldn't erase our present. 381 00:10:17,800 --> 00:10:18,640 Right. 382 00:10:18,640 --> 00:10:20,120 But it would put us on a different path 383 00:10:20,120 --> 00:10:22,320 in this massive multiverse. 384 00:10:22,320 --> 00:10:25,160 It's a pretty mind boggling concept. 385 00:10:25,160 --> 00:10:26,000 It is. 386 00:10:26,000 --> 00:10:29,000 But it does seem to like address 387 00:10:29,000 --> 00:10:30,960 some of those paradoxes we were talking about. 388 00:10:30,960 --> 00:10:31,800 It does. 389 00:10:31,800 --> 00:10:34,480 The multiverse theory gives us a possible solution 390 00:10:34,480 --> 00:10:36,240 to the grandfather paradox. 391 00:10:36,240 --> 00:10:37,080 Okay. 392 00:10:37,080 --> 00:10:38,600 For instance, imagine you went back in time 393 00:10:38,600 --> 00:10:40,000 and you changed events. 394 00:10:40,000 --> 00:10:40,840 Yeah. 395 00:10:40,840 --> 00:10:41,680 And it would be different to you existing. 396 00:10:41,680 --> 00:10:42,520 Right. 397 00:10:42,520 --> 00:10:43,680 Well, you wouldn't be erasing yourself 398 00:10:43,680 --> 00:10:44,920 from that original timeline. 399 00:10:44,920 --> 00:10:45,760 Right. 400 00:10:45,760 --> 00:10:46,600 You'd just be moving to a different branch 401 00:10:46,600 --> 00:10:48,400 of the multiverse where you still exist. 402 00:10:48,400 --> 00:10:50,440 It's like having this cosmic safety net. 403 00:10:50,440 --> 00:10:51,280 Right. 404 00:10:51,280 --> 00:10:54,040 That makes sure that even the most crazy changes 405 00:10:54,040 --> 00:10:59,040 to the past don't completely like destroy reality. 406 00:10:59,080 --> 00:10:59,960 In a way, yeah. 407 00:10:59,960 --> 00:11:02,440 The multiverse theory allows for more flexibility 408 00:11:02,440 --> 00:11:03,680 when it comes to time travel. 409 00:11:03,680 --> 00:11:04,520 Okay. 410 00:11:04,520 --> 00:11:07,920 It suggests that the results of changing the past 411 00:11:07,920 --> 00:11:10,240 might not be as bad as we think. 412 00:11:10,240 --> 00:11:11,080 Okay. 413 00:11:11,080 --> 00:11:13,240 It's a really awe-inspiring idea. 414 00:11:13,240 --> 00:11:14,080 It is. 415 00:11:14,080 --> 00:11:17,040 But it also shows us just how much we still don't know 416 00:11:17,040 --> 00:11:20,040 about the universe and what time really is. 417 00:11:20,040 --> 00:11:20,880 Right. 418 00:11:20,880 --> 00:11:21,720 Yeah. 419 00:11:21,720 --> 00:11:22,540 Absolutely. 420 00:11:22,540 --> 00:11:23,520 Time travel really pushes us to the edge 421 00:11:23,520 --> 00:11:24,760 of what we understand. 422 00:11:24,760 --> 00:11:25,600 It does. 423 00:11:25,600 --> 00:11:28,720 It makes us face the limits of like our current models. 424 00:11:28,720 --> 00:11:29,560 Yeah. 425 00:11:29,560 --> 00:11:32,120 And think about possibilities that just seem, 426 00:11:32,120 --> 00:11:34,120 you know, completely fantastical. 427 00:11:34,120 --> 00:11:34,960 Right. 428 00:11:34,960 --> 00:11:36,040 So backward time travel. 429 00:11:36,040 --> 00:11:36,880 Yeah. 430 00:11:36,880 --> 00:11:38,640 It's still very much in the realm of speculation. 431 00:11:38,640 --> 00:11:39,480 For sure. 432 00:11:39,480 --> 00:11:41,960 It does make us ask these like really deep questions. 433 00:11:41,960 --> 00:11:42,800 It does. 434 00:11:42,800 --> 00:11:45,800 About reality, causality, and the limits of what we know. 435 00:11:45,800 --> 00:11:46,640 Absolutely. 436 00:11:46,640 --> 00:11:47,460 Speaking of understanding, 437 00:11:47,460 --> 00:11:48,480 can we shift gears a little bit? 438 00:11:48,480 --> 00:11:49,320 Sure. 439 00:11:49,320 --> 00:11:51,440 Let's talk about like actual scientific research 440 00:11:51,440 --> 00:11:54,440 that's being done in relation to time travel. 441 00:11:54,440 --> 00:11:55,280 Okay. 442 00:11:55,280 --> 00:11:56,160 We've talked about the theories, 443 00:11:56,160 --> 00:11:57,580 but what about the evidence? 444 00:11:57,580 --> 00:11:59,080 You mean there are scientists out there 445 00:11:59,080 --> 00:12:01,080 actually studying time travel. 446 00:12:01,080 --> 00:12:01,920 Yeah. 447 00:12:01,920 --> 00:12:05,040 It's not just like theoretical physicists and sci-fi writers. 448 00:12:05,040 --> 00:12:05,880 Right. 449 00:12:05,880 --> 00:12:08,120 So we haven't built any working time machines, 450 00:12:08,120 --> 00:12:11,720 but there are some real scientific observations 451 00:12:11,720 --> 00:12:14,900 that support the idea that time is a lot more flexible 452 00:12:14,900 --> 00:12:16,320 than we usually think. 453 00:12:16,320 --> 00:12:17,440 Okay. I'm intrigued. 454 00:12:17,440 --> 00:12:19,680 Give me some like concrete examples. 455 00:12:19,680 --> 00:12:22,760 Okay. So remember time dilation. 456 00:12:22,760 --> 00:12:24,500 Yeah. The slowing down of time 457 00:12:24,500 --> 00:12:25,960 for things moving really fast. 458 00:12:25,960 --> 00:12:28,080 Yeah. So that's not just a theory. 459 00:12:28,080 --> 00:12:31,840 It's been proven many times using atomic clocks. 460 00:12:31,840 --> 00:12:33,200 So scientists have actually measured 461 00:12:33,200 --> 00:12:34,820 time dilation happening. 462 00:12:34,820 --> 00:12:35,920 They have. 463 00:12:35,920 --> 00:12:38,840 For example, they've flown atomic clocks 464 00:12:38,840 --> 00:12:40,840 on airplanes and satellites. 465 00:12:40,840 --> 00:12:41,680 Okay. 466 00:12:41,680 --> 00:12:43,280 And they show a little difference in time. 467 00:12:43,280 --> 00:12:44,120 Okay. 468 00:12:44,120 --> 00:12:45,840 Compared to clocks that stayed on the ground. 469 00:12:45,840 --> 00:12:46,680 Right. 470 00:12:46,680 --> 00:12:48,560 The clocks that traveled at higher speeds 471 00:12:48,560 --> 00:12:51,320 show that a tiny bit less time has passed. 472 00:12:51,320 --> 00:12:52,160 Wow. 473 00:12:52,160 --> 00:12:54,160 Exactly like Einstein's theories predicted. 474 00:12:54,160 --> 00:12:55,880 So it's not just some hypothetical thing. 475 00:12:55,880 --> 00:12:56,720 Yeah. 476 00:12:56,720 --> 00:12:58,260 Time dilation is something we can measure. 477 00:12:58,260 --> 00:12:59,280 That's incredible. 478 00:12:59,280 --> 00:13:00,800 And these measurements just prove 479 00:13:00,800 --> 00:13:03,280 that time isn't this fixed thing. 480 00:13:03,280 --> 00:13:04,120 Right. 481 00:13:04,120 --> 00:13:06,600 It's relative, it's affected by things like speed 482 00:13:06,600 --> 00:13:07,920 and gravity. 483 00:13:07,920 --> 00:13:10,360 That brings us back to Einstein 484 00:13:10,360 --> 00:13:12,920 and his revolutionary theories. 485 00:13:12,920 --> 00:13:13,760 Right. 486 00:13:13,760 --> 00:13:17,240 Are there any other observations that support this idea 487 00:13:17,240 --> 00:13:19,840 of time being malleable? 488 00:13:19,840 --> 00:13:20,960 There are. 489 00:13:20,960 --> 00:13:22,800 We've also observed what's called 490 00:13:22,800 --> 00:13:24,600 gravitational time dilation. 491 00:13:24,600 --> 00:13:25,440 Okay. 492 00:13:25,440 --> 00:13:27,480 The slowing down of time in strong gravitational fields. 493 00:13:27,480 --> 00:13:28,320 Right. 494 00:13:28,320 --> 00:13:29,880 Like the ones you'd find around massive objects 495 00:13:29,880 --> 00:13:31,520 such as black holes. 496 00:13:31,520 --> 00:13:35,720 Wait, so time literally moves slower near a black hole? 497 00:13:35,720 --> 00:13:36,560 That's right. 498 00:13:36,560 --> 00:13:37,380 Wow. 499 00:13:37,380 --> 00:13:39,680 Observations of stars orbiting close to black holes 500 00:13:39,680 --> 00:13:40,960 have actually confirmed this. 501 00:13:40,960 --> 00:13:41,800 Really? 502 00:13:41,800 --> 00:13:44,040 The intense gravity warps space time so much. 503 00:13:44,040 --> 00:13:44,880 Yeah. 504 00:13:44,880 --> 00:13:46,460 That time itself slows down near it. 505 00:13:46,460 --> 00:13:47,640 It's almost like black holes 506 00:13:47,640 --> 00:13:49,760 are like these cosmic time machines. 507 00:13:49,760 --> 00:13:50,600 Uh-huh. 508 00:13:50,600 --> 00:13:51,640 Distorting time around them. 509 00:13:51,640 --> 00:13:53,080 In a way, yes. 510 00:13:53,080 --> 00:13:53,920 Wow. 511 00:13:53,920 --> 00:13:55,200 These observations not only strengthen 512 00:13:55,200 --> 00:13:57,640 our understanding of general relativity, 513 00:13:57,640 --> 00:13:59,880 but also provide more evidence that gravity 514 00:13:59,880 --> 00:14:01,920 can change the very nature of time. 515 00:14:01,920 --> 00:14:06,000 It's like a glimpse into a world where time itself 516 00:14:06,000 --> 00:14:09,160 bends to the will of these huge objects. 517 00:14:09,160 --> 00:14:10,000 It is. 518 00:14:10,000 --> 00:14:10,820 It's mind boggling. 519 00:14:10,820 --> 00:14:14,040 It's mind boggling and as we keep exploring the cosmos, 520 00:14:14,040 --> 00:14:18,040 studying black holes and these other crazy environments, 521 00:14:18,040 --> 00:14:20,400 we're bound to find even more mind blowing stuff 522 00:14:20,400 --> 00:14:22,000 about the nature of time. 523 00:14:22,000 --> 00:14:23,440 It's amazing to think that we've gone 524 00:14:23,440 --> 00:14:25,840 from these theoretical predictions. 525 00:14:25,840 --> 00:14:26,680 Yeah. 526 00:14:26,680 --> 00:14:29,120 To actually seeing this stuff happening in the universe. 527 00:14:29,120 --> 00:14:29,960 It is. 528 00:14:29,960 --> 00:14:32,600 It really shows the power of scientific exploration. 529 00:14:32,600 --> 00:14:33,440 Yeah. 530 00:14:33,440 --> 00:14:36,080 And how our understanding of the cosmos keeps growing. 531 00:14:36,080 --> 00:14:36,920 Right. 532 00:14:36,920 --> 00:14:39,640 But it's not just about observing from afar. 533 00:14:39,640 --> 00:14:40,480 Right. 534 00:14:40,480 --> 00:14:42,360 Scientists are doing some cutting edge experiments 535 00:14:42,360 --> 00:14:43,520 here on Earth too. 536 00:14:43,520 --> 00:14:44,360 Really? 537 00:14:44,360 --> 00:14:46,360 Yeah, they're going into the quantum realm. 538 00:14:46,360 --> 00:14:47,200 Oh. 539 00:14:47,200 --> 00:14:49,800 To search for clues about time and causality. 540 00:14:49,800 --> 00:14:50,840 Quantum experiments. 541 00:14:50,840 --> 00:14:52,180 What do those have to do with time travel? 542 00:14:52,180 --> 00:14:55,560 The quantum world is this strange 543 00:14:55,560 --> 00:14:57,360 and counterintuitive place. 544 00:14:57,360 --> 00:14:58,200 Okay. 545 00:14:58,200 --> 00:15:01,040 Rules of classical physics don't really apply. 546 00:15:01,040 --> 00:15:01,880 Right. 547 00:15:01,880 --> 00:15:02,720 And within that world, 548 00:15:02,720 --> 00:15:06,280 there might be these hidden pathways, these mechanisms 549 00:15:06,280 --> 00:15:08,280 that could maybe let us manipulate time 550 00:15:08,280 --> 00:15:09,760 in ways we can't even imagine yet. 551 00:15:09,760 --> 00:15:11,680 So we're talking about using the weirdness 552 00:15:11,680 --> 00:15:13,200 of quantum mechanics. 553 00:15:13,200 --> 00:15:14,040 Yeah. 554 00:15:14,040 --> 00:15:16,840 To unlock the secrets of time travel. 555 00:15:16,840 --> 00:15:18,880 In a way, yes. 556 00:15:18,880 --> 00:15:20,800 Researchers are looking into things 557 00:15:20,800 --> 00:15:22,560 like quantum entanglement. 558 00:15:22,560 --> 00:15:23,520 Quantum entanglement. 559 00:15:23,520 --> 00:15:26,000 Where two particles are linked 560 00:15:26,000 --> 00:15:28,000 in such a way that they share the same fate. 561 00:15:28,000 --> 00:15:28,840 Okay. 562 00:15:28,840 --> 00:15:30,920 Even when they're separated by huge distances. 563 00:15:30,920 --> 00:15:32,520 It's like this spooky connection 564 00:15:32,520 --> 00:15:34,600 that goes beyond space and time. 565 00:15:34,600 --> 00:15:35,560 Exactly. 566 00:15:35,560 --> 00:15:36,400 Wow. 567 00:15:36,400 --> 00:15:37,840 And while entanglement itself 568 00:15:37,840 --> 00:15:40,680 doesn't directly lead to time travel. 569 00:15:40,680 --> 00:15:41,520 Right. 570 00:15:41,520 --> 00:15:42,960 It does give us valuable insight. 571 00:15:42,960 --> 00:15:43,800 Okay. 572 00:15:43,800 --> 00:15:45,640 Into how interconnected the universe is. 573 00:15:45,640 --> 00:15:46,480 Okay. 574 00:15:46,480 --> 00:15:49,120 And the strange ways information can be sent. 575 00:15:49,120 --> 00:15:49,960 Yeah. 576 00:15:49,960 --> 00:15:51,280 Maybe even across time. 577 00:15:51,280 --> 00:15:54,400 It's a reminder that the universe is full of mysteries 578 00:15:54,400 --> 00:15:55,560 we haven't figured out yet. 579 00:15:55,560 --> 00:15:56,400 It is. 580 00:15:56,400 --> 00:15:58,480 And that the search for time travel could lead us 581 00:15:58,480 --> 00:15:59,320 to discoveries. 582 00:15:59,320 --> 00:16:00,160 Yeah. 583 00:16:00,160 --> 00:16:02,360 That completely change how we understand reality. 584 00:16:02,360 --> 00:16:03,200 It could. 585 00:16:03,200 --> 00:16:04,040 Wow. 586 00:16:04,040 --> 00:16:04,880 It's a journey worth taking. 587 00:16:04,880 --> 00:16:05,720 Yeah. 588 00:16:05,720 --> 00:16:06,600 Even if we don't know where it leads. 589 00:16:06,600 --> 00:16:07,440 Right. 590 00:16:07,440 --> 00:16:08,280 Speaking of journeys, 591 00:16:08,280 --> 00:16:10,240 what about those massive experiments? 592 00:16:10,240 --> 00:16:11,080 Yeah. 593 00:16:11,080 --> 00:16:12,280 Like the Large Hadron Collider. 594 00:16:12,280 --> 00:16:13,120 Right. 595 00:16:13,120 --> 00:16:15,360 Does that play a role in understanding time travel? 596 00:16:15,360 --> 00:16:16,200 It does. 597 00:16:16,200 --> 00:16:18,960 The Large Hadron Collider, or LHC, 598 00:16:18,960 --> 00:16:22,640 is the most powerful particle accelerator in the world. 599 00:16:22,640 --> 00:16:23,480 Wow. 600 00:16:23,480 --> 00:16:26,480 It smashes atoms together at crazy speeds. 601 00:16:26,480 --> 00:16:27,320 Okay. 602 00:16:27,320 --> 00:16:28,840 Recreating the conditions that existed 603 00:16:28,840 --> 00:16:31,560 just fractions of a second after the Big Bang. 604 00:16:31,560 --> 00:16:32,560 It's like looking back 605 00:16:32,560 --> 00:16:34,080 to the very beginning of the universe. 606 00:16:34,080 --> 00:16:34,920 It is. 607 00:16:34,920 --> 00:16:35,760 Yeah. 608 00:16:35,760 --> 00:16:39,560 And by studying the pieces from these collisions. 609 00:16:39,560 --> 00:16:40,400 Yeah. 610 00:16:40,400 --> 00:16:41,520 Scientists are learning so much 611 00:16:41,520 --> 00:16:44,120 about the fundamental building blocks of matter. 612 00:16:44,120 --> 00:16:44,960 Okay. 613 00:16:44,960 --> 00:16:46,480 And the forces that control the universe. 614 00:16:46,480 --> 00:16:47,320 Right. 615 00:16:47,320 --> 00:16:49,440 This knowledge could help us figure out 616 00:16:49,440 --> 00:16:51,600 how to manipulate space time itself. 617 00:16:51,600 --> 00:16:54,440 So by pushing the limits of energy and matter. 618 00:16:54,440 --> 00:16:55,280 Yeah. 619 00:16:55,280 --> 00:16:57,680 These experiments could show us new particles 620 00:16:57,680 --> 00:16:58,920 or things to shed light on. 621 00:16:58,920 --> 00:17:00,800 Like the nature of space time. 622 00:17:00,800 --> 00:17:01,640 Exactly. 623 00:17:01,640 --> 00:17:02,480 Oh. 624 00:17:02,480 --> 00:17:05,440 The LHC and other advanced research facilities 625 00:17:05,440 --> 00:17:07,960 are tools for looking into the deepest mysteries 626 00:17:07,960 --> 00:17:09,000 of the universe. 627 00:17:09,000 --> 00:17:12,200 Trying to find answers to some of the most profound questions 628 00:17:12,200 --> 00:17:14,920 about time, space, and our place in it all. 629 00:17:14,920 --> 00:17:17,080 It's a truly awe-inspiring endeavor. 630 00:17:17,080 --> 00:17:17,920 It is. 631 00:17:17,920 --> 00:17:21,840 Filled by human curiosity and this desire to learn more. 632 00:17:21,840 --> 00:17:22,680 Absolutely. 633 00:17:22,680 --> 00:17:23,520 Okay. 634 00:17:23,520 --> 00:17:24,360 So after all of this. 635 00:17:24,360 --> 00:17:25,200 Yeah. 636 00:17:25,200 --> 00:17:26,020 Where do we stand? 637 00:17:26,020 --> 00:17:26,860 Right. 638 00:17:26,860 --> 00:17:29,200 Is time travel actually possible? 639 00:17:29,200 --> 00:17:30,040 Yeah. 640 00:17:30,040 --> 00:17:32,440 Or is it just this really cool idea. 641 00:17:32,440 --> 00:17:33,280 Right. 642 00:17:33,280 --> 00:17:35,400 That's always gonna stay in science fiction. 643 00:17:35,400 --> 00:17:37,080 Well, it kind of depends on what kind of time travel 644 00:17:37,080 --> 00:17:37,920 we're talking about. 645 00:17:37,920 --> 00:17:38,760 Okay. 646 00:17:38,760 --> 00:17:39,600 When it comes to forward time travel. 647 00:17:39,600 --> 00:17:40,640 Yeah, traveling to the future. 648 00:17:40,640 --> 00:17:42,920 Yeah, I'd say it's a cautious yes. 649 00:17:42,920 --> 00:17:43,920 A cautious yes. 650 00:17:43,920 --> 00:17:46,480 We know time dilation is a real thing. 651 00:17:46,480 --> 00:17:47,320 Right. 652 00:17:47,320 --> 00:17:49,800 And so technically traveling to the future 653 00:17:49,800 --> 00:17:52,040 is already happening in a way. 654 00:17:52,040 --> 00:17:55,520 We talked about astronauts aging a little slower in space. 655 00:17:55,520 --> 00:17:56,360 Right. 656 00:17:56,360 --> 00:17:59,280 But to make those like really big jumps into the future. 657 00:17:59,280 --> 00:18:00,120 Yeah. 658 00:18:00,120 --> 00:18:03,000 Wouldn't we have to go to like almost as fast as light? 659 00:18:03,000 --> 00:18:04,000 That's the thing. 660 00:18:04,000 --> 00:18:04,840 Right. 661 00:18:04,840 --> 00:18:08,000 Getting to those speeds would take technology 662 00:18:08,000 --> 00:18:10,360 way beyond anything we have now. 663 00:18:10,360 --> 00:18:14,400 We'd need completely new ways to like make energy 664 00:18:14,400 --> 00:18:15,640 and move through space. 665 00:18:15,640 --> 00:18:16,480 Yeah. 666 00:18:16,480 --> 00:18:17,760 And there's serious protection 667 00:18:17,760 --> 00:18:19,880 from all the crazy forces involved. 668 00:18:19,880 --> 00:18:20,720 Right. 669 00:18:20,720 --> 00:18:23,120 It's a huge challenge to say the least. 670 00:18:23,120 --> 00:18:26,680 So while forward time travel might be based in physics. 671 00:18:26,680 --> 00:18:27,520 Yeah. 672 00:18:27,520 --> 00:18:30,280 It seems like those big jumps into the future. 673 00:18:30,280 --> 00:18:32,320 They're still in the world of sci-fi. 674 00:18:32,320 --> 00:18:33,880 For now at least, yeah. 675 00:18:33,880 --> 00:18:34,720 Okay. 676 00:18:34,720 --> 00:18:36,640 But the possibility is there. 677 00:18:36,640 --> 00:18:37,480 Right. 678 00:18:37,480 --> 00:18:39,080 Now backward time travel. 679 00:18:39,080 --> 00:18:39,920 Yeah. 680 00:18:39,920 --> 00:18:41,000 That's a whole other story. 681 00:18:41,000 --> 00:18:42,920 Right, we've talked about all the paradoxes. 682 00:18:42,920 --> 00:18:43,760 Yeah. 683 00:18:43,760 --> 00:18:46,160 The lack of like any real evidence. 684 00:18:46,160 --> 00:18:47,000 Right. 685 00:18:47,000 --> 00:18:49,200 And just how mind blowing it all is, 686 00:18:49,200 --> 00:18:50,960 is going back in time. 687 00:18:50,960 --> 00:18:51,840 Yeah. 688 00:18:51,840 --> 00:18:55,000 Even a little bit possible scientifically speaking. 689 00:18:55,000 --> 00:18:57,200 It's highly speculative to be honest. 690 00:18:57,200 --> 00:18:58,040 Okay. 691 00:18:58,040 --> 00:18:59,320 The challenges are enormous. 692 00:18:59,320 --> 00:19:00,160 Yeah. 693 00:19:00,160 --> 00:19:01,120 Those paradoxes, they make you wonder 694 00:19:01,120 --> 00:19:03,000 if backward time travel could ever make sense. 695 00:19:03,000 --> 00:19:04,560 And then there's the energy problem. 696 00:19:04,560 --> 00:19:05,400 Yeah. 697 00:19:05,400 --> 00:19:06,760 To mess with space time that much. 698 00:19:06,760 --> 00:19:07,600 Yeah. 699 00:19:07,600 --> 00:19:09,040 You'd need a ridiculous amount of energy 700 00:19:09,040 --> 00:19:11,240 like more than we can even imagine. 701 00:19:11,240 --> 00:19:15,080 And we haven't even like talked about the actual problems 702 00:19:15,080 --> 00:19:16,400 of building a time machine. 703 00:19:16,400 --> 00:19:17,240 Right. 704 00:19:17,240 --> 00:19:18,200 Assuming we even could. 705 00:19:18,200 --> 00:19:19,880 Yeah, all those ideas we discussed, 706 00:19:19,880 --> 00:19:21,960 wormholes, cosmic strings, 707 00:19:21,960 --> 00:19:23,320 Tipler cylinders. 708 00:19:23,320 --> 00:19:24,160 Right. 709 00:19:24,160 --> 00:19:26,000 They all need things we've never actually seen. 710 00:19:26,000 --> 00:19:29,360 Or technology that's way beyond what we can do. 711 00:19:29,360 --> 00:19:31,560 Sounds like the idea of hopping in a time machine 712 00:19:31,560 --> 00:19:32,800 and going back to the past. 713 00:19:32,800 --> 00:19:33,680 Yeah. 714 00:19:33,680 --> 00:19:36,080 Is probably gonna stay just that. 715 00:19:36,080 --> 00:19:36,920 Right. 716 00:19:36,920 --> 00:19:37,760 An idea. 717 00:19:37,760 --> 00:19:39,320 It might, but even if building a time machine 718 00:19:39,320 --> 00:19:40,800 turns out to be impossible. 719 00:19:40,800 --> 00:19:41,640 Yeah. 720 00:19:41,640 --> 00:19:43,680 Just thinking about these ideas is valuable. 721 00:19:43,680 --> 00:19:44,520 Okay. 722 00:19:44,520 --> 00:19:47,200 It makes us think hard about time, cause and effect. 723 00:19:47,200 --> 00:19:48,040 Yeah. 724 00:19:48,040 --> 00:19:49,000 And the limits of what we know. 725 00:19:49,000 --> 00:19:49,840 Okay. 726 00:19:49,840 --> 00:19:50,840 It pushes science forward 727 00:19:50,840 --> 00:19:53,000 and makes us use our imaginations. 728 00:19:53,000 --> 00:19:55,720 It reminds us that there's still a lot about the universe. 729 00:19:55,720 --> 00:19:56,680 Oh yeah. 730 00:19:56,680 --> 00:19:58,000 That we just don't understand. 731 00:19:58,000 --> 00:19:58,840 For sure. 732 00:19:58,840 --> 00:20:01,000 And that we're not done discovering things. 733 00:20:01,000 --> 00:20:01,880 Absolutely. 734 00:20:01,880 --> 00:20:05,080 Who knows, maybe someday some genius 735 00:20:05,080 --> 00:20:06,480 will figure something out. 736 00:20:06,480 --> 00:20:07,320 Yeah. 737 00:20:07,320 --> 00:20:08,160 That changes everything. 738 00:20:08,160 --> 00:20:09,000 Right. 739 00:20:09,000 --> 00:20:10,640 Maybe there are these hidden laws of physics out there. 740 00:20:10,640 --> 00:20:11,480 Yeah. 741 00:20:11,480 --> 00:20:13,360 That could make time travel real. 742 00:20:13,360 --> 00:20:16,200 It's both exciting and a little scary to think about. 743 00:20:16,200 --> 00:20:17,040 It is. 744 00:20:17,040 --> 00:20:19,080 But even if we never actually travel through time. 745 00:20:19,080 --> 00:20:19,920 Yeah. 746 00:20:19,920 --> 00:20:21,240 Just trying to understand it. 747 00:20:21,240 --> 00:20:22,960 Has helped us learn more about the universe 748 00:20:22,960 --> 00:20:23,920 and where we fit in. 749 00:20:23,920 --> 00:20:27,320 It's a testament to human curiosity. 750 00:20:27,320 --> 00:20:30,320 And our need to explore the unknown. 751 00:20:30,320 --> 00:20:31,160 Definitely. 752 00:20:31,160 --> 00:20:32,240 Well that brings us to the end. 753 00:20:32,240 --> 00:20:33,080 Yeah. 754 00:20:33,080 --> 00:20:34,400 Of our deep dive into time travel. 755 00:20:34,400 --> 00:20:35,360 It has been a journey. 756 00:20:35,360 --> 00:20:36,720 It's been a really wild ride 757 00:20:36,720 --> 00:20:39,640 through physics, philosophy and imagination. 758 00:20:39,640 --> 00:20:43,040 We've looked at the possibilities, the challenges 759 00:20:43,040 --> 00:20:46,360 and what it would all mean if we could actually control time. 760 00:20:46,360 --> 00:20:47,800 And while we still don't know 761 00:20:47,800 --> 00:20:49,360 if we'll ever be able to time travel. 762 00:20:49,360 --> 00:20:50,440 Right. 763 00:20:50,440 --> 00:20:51,600 One thing's for sure. 764 00:20:51,600 --> 00:20:52,880 What's that? 765 00:20:52,880 --> 00:20:55,680 Exploring these ideas keeps inspiring us. 766 00:20:55,680 --> 00:20:56,520 Yeah. 767 00:20:56,520 --> 00:20:57,360 And making us wonder. 768 00:20:57,360 --> 00:20:58,200 It does. 769 00:20:58,200 --> 00:20:59,040 So as we wrap up. 770 00:20:59,040 --> 00:20:59,880 Yeah. 771 00:20:59,880 --> 00:21:00,720 We leave you with one last thought. 772 00:21:00,720 --> 00:21:01,560 Okay. 773 00:21:01,560 --> 00:21:02,680 If you could travel through time. 774 00:21:02,680 --> 00:21:03,520 Yeah. 775 00:21:03,520 --> 00:21:04,360 Where would you go? 776 00:21:04,360 --> 00:21:05,200 Right. 777 00:21:05,200 --> 00:21:06,760 And what would you do with that power? 778 00:21:06,760 --> 00:21:07,840 That's a great question. 779 00:21:07,840 --> 00:21:09,800 It makes us think about not just the science. 780 00:21:09,800 --> 00:21:10,640 Yeah. 781 00:21:10,640 --> 00:21:12,520 But also the ethics and what it all means. 782 00:21:12,520 --> 00:21:13,360 Absolutely. 783 00:21:13,360 --> 00:21:14,800 Until we figure all that out. 784 00:21:14,800 --> 00:21:15,640 Right. 785 00:21:15,640 --> 00:21:17,000 The answer is up to our imagination. 786 00:21:17,000 --> 00:21:18,320 Yeah. 787 00:21:18,320 --> 00:21:20,520 And maybe a little bit of cosmic wonder. 788 00:21:20,520 --> 00:21:21,880 A little bit. 789 00:21:21,880 --> 00:21:24,320 Don't forget to follow and subscribe to Cosmos in a Pod 790 00:21:24,320 --> 00:21:25,520 and our YouTube channel. 791 00:21:25,520 --> 00:21:26,880 Yes, please do. 792 00:21:26,880 --> 00:21:29,960 Thanks for joining us on this amazing trip 793 00:21:29,960 --> 00:21:48,960 through the mysteries of time and space.