1 00:00:09,160 --> 00:00:11,320 Speaker 1: Or Hey, do you ever wish that the speed of 2 00:00:11,440 --> 00:00:15,080 Speaker 1: light was faster? I guess I'm not dissatisfied with the 3 00:00:15,080 --> 00:00:17,640 Speaker 1: speed of light. I'm just glad it's not slower, because 4 00:00:17,680 --> 00:00:19,120 Speaker 1: you know, I don't want to wait ten minutes after 5 00:00:19,160 --> 00:00:21,640 Speaker 1: I flip on the light switch. But you know, if 6 00:00:21,680 --> 00:00:24,160 Speaker 1: it was faster, and then we could see like further 7 00:00:24,239 --> 00:00:27,640 Speaker 1: out into the universe. M m. That's true, and then 8 00:00:27,680 --> 00:00:30,840 Speaker 1: we might be able to travel further to explore the stars. 9 00:00:30,920 --> 00:00:34,360 Speaker 1: Also true. But there's another side to it, as always, well, 10 00:00:34,400 --> 00:00:36,480 Speaker 1: how could it be bad to have a faster speed 11 00:00:36,479 --> 00:00:39,120 Speaker 1: of light? Well, light speed was a million times faster 12 00:00:39,479 --> 00:00:42,720 Speaker 1: than technically any alien out there in the universe could 13 00:00:42,760 --> 00:00:45,400 Speaker 1: kill us instantly with a death ray. That's true. But 14 00:00:45,479 --> 00:00:48,840 Speaker 1: you know, witnessing an alien death ray would be pretty cool. 15 00:00:49,200 --> 00:00:51,560 Speaker 1: It would be pretty cool for about a nano second, 16 00:00:51,560 --> 00:00:53,440 Speaker 1: and then you'd be dead. Also, I'm pretty sure a 17 00:00:53,520 --> 00:00:56,480 Speaker 1: death ray would be hot and not cool. Might still 18 00:00:56,520 --> 00:00:58,520 Speaker 1: be worth it, just for that nana second, you would 19 00:00:58,520 --> 00:01:09,200 Speaker 1: know that AIDS existed. As my brain is getting FRIEDA. 20 00:01:16,959 --> 00:01:20,240 Speaker 1: I am or haemade cartoonists and the creator of PhD comics. Hi, 21 00:01:20,480 --> 00:01:23,280 Speaker 1: I'm Daniel, I'm a particle physicist, and I don't spend 22 00:01:23,319 --> 00:01:26,399 Speaker 1: a lot of time worrying about alien death rays. You don't, 23 00:01:26,680 --> 00:01:28,600 Speaker 1: do you know something I don't. I know that the 24 00:01:28,600 --> 00:01:30,920 Speaker 1: speed of light protects us from most of the universe 25 00:01:30,959 --> 00:01:33,960 Speaker 1: shooting us with alien death rays. Really like it forms 26 00:01:34,000 --> 00:01:37,120 Speaker 1: a force field around us, protecting this like a blanket 27 00:01:37,319 --> 00:01:39,280 Speaker 1: helping us sleep at night. It just makes it kind 28 00:01:39,319 --> 00:01:41,200 Speaker 1: of ineffective. If you're going to shoot an alien death 29 00:01:41,280 --> 00:01:43,360 Speaker 1: ray millions of light years, then you're gonna kill your 30 00:01:43,360 --> 00:01:47,080 Speaker 1: target in millions of years. And like, who's geopolitical strategy 31 00:01:47,160 --> 00:01:49,680 Speaker 1: really has that long and arc to it? But what 32 00:01:49,800 --> 00:01:53,720 Speaker 1: if there are patient aliens? Then we're toast? Then we 33 00:01:53,800 --> 00:01:56,440 Speaker 1: might literally be toast. Welcome to our podcast, Daniel and 34 00:01:56,520 --> 00:01:59,280 Speaker 1: Jorge Explain the Universe, a production of I Heart Radio 35 00:01:59,440 --> 00:02:02,280 Speaker 1: in which we beam our joke rays into your brain, 36 00:02:02,560 --> 00:02:06,000 Speaker 1: hoping to transmit some of the incredible wonder and knowledge 37 00:02:06,040 --> 00:02:09,040 Speaker 1: about the universe, all the things that science has learned 38 00:02:09,080 --> 00:02:12,960 Speaker 1: about this Bonker's wondrous, beautiful, glittering cosmos, and all the 39 00:02:13,000 --> 00:02:16,000 Speaker 1: things that science is still working on, all the vague 40 00:02:16,080 --> 00:02:18,960 Speaker 1: questions about how the universe got here, where it's going, 41 00:02:19,240 --> 00:02:21,880 Speaker 1: and who lives in it, and how to actually build 42 00:02:21,880 --> 00:02:25,080 Speaker 1: a joke Ray. I mean, that's probably the next Nobel Prize. 43 00:02:25,320 --> 00:02:27,080 Speaker 1: The question it doesn't make you groan or does it 44 00:02:27,120 --> 00:02:29,000 Speaker 1: make you laugh? Is that where you're gonna ask when 45 00:02:29,000 --> 00:02:30,919 Speaker 1: the aliens come, I'm gonna be like, tell us the 46 00:02:30,960 --> 00:02:33,040 Speaker 1: secrets of spacetime and you're like, have you developed the 47 00:02:33,120 --> 00:02:35,240 Speaker 1: joke Ray yet? We'll think about what it would mean 48 00:02:35,320 --> 00:02:37,959 Speaker 1: for the mental health of humanity. You know, we could 49 00:02:38,000 --> 00:02:41,120 Speaker 1: just have a laugh about everything. Laughter is the best medicine. 50 00:02:41,160 --> 00:02:43,160 Speaker 1: So anytime you go to the doctor, they're just like, yep, 51 00:02:43,240 --> 00:02:45,760 Speaker 1: we're prescribing you five shots with the joke Ray. And 52 00:02:45,800 --> 00:02:48,240 Speaker 1: then as the aliens as they you know, enslave us 53 00:02:48,320 --> 00:02:51,160 Speaker 1: and possibly eat us, we could be laughing all the way. 54 00:02:51,400 --> 00:02:54,960 Speaker 1: But it is a bizarre and jokey universe because it 55 00:02:55,000 --> 00:02:57,400 Speaker 1: seems like a lot of it is beyond our control 56 00:02:57,480 --> 00:03:01,400 Speaker 1: or even beyond our ability to whoever interact with it. 57 00:03:01,600 --> 00:03:04,840 Speaker 1: That's true, and it's also sometimes beyond our ability to 58 00:03:05,080 --> 00:03:08,120 Speaker 1: really understand. We have one way of thinking about the 59 00:03:08,160 --> 00:03:11,240 Speaker 1: world where things move and slide and the way time works. 60 00:03:11,360 --> 00:03:14,079 Speaker 1: But about a hundred years ago we discovered that that 61 00:03:14,200 --> 00:03:16,360 Speaker 1: wasn't really the way it worked, that there were different 62 00:03:16,440 --> 00:03:19,280 Speaker 1: rules the things change when you move fast or when 63 00:03:19,360 --> 00:03:22,120 Speaker 1: space is bent, and that we needed new rules and 64 00:03:22,200 --> 00:03:26,119 Speaker 1: new ideas to understand what actually goes on in this universe. Yeah, 65 00:03:26,160 --> 00:03:28,399 Speaker 1: because I guess we realized a few hundred years ago 66 00:03:28,480 --> 00:03:31,400 Speaker 1: that the universe, the world doesn't really behave the way 67 00:03:31,440 --> 00:03:33,680 Speaker 1: it behaves like on an everyday basis, like when you're 68 00:03:33,760 --> 00:03:37,320 Speaker 1: juggling baseball or or you know, balancing a basketball. It's 69 00:03:37,360 --> 00:03:39,160 Speaker 1: like that's one way that we think of the world 70 00:03:39,280 --> 00:03:41,520 Speaker 1: is working. But really, like if you get down to it, 71 00:03:41,560 --> 00:03:44,800 Speaker 1: in some situations, it's totally different. You know. In fact, 72 00:03:44,880 --> 00:03:48,160 Speaker 1: there are really fundamentally different rules that govern how things 73 00:03:48,240 --> 00:03:51,520 Speaker 1: move and how time flows. It just happens to be 74 00:03:51,560 --> 00:03:54,800 Speaker 1: that in certain situations, like when you're moving really slow 75 00:03:55,400 --> 00:03:58,520 Speaker 1: and when you're far from a black hole, things look 76 00:03:58,560 --> 00:04:01,040 Speaker 1: a lot simpler. So we're living in a sort of 77 00:04:01,040 --> 00:04:05,480 Speaker 1: a simplified corner of a very weird, very complicated universe. Right, 78 00:04:05,560 --> 00:04:07,800 Speaker 1: It's almost like we're in a special case, like our 79 00:04:08,040 --> 00:04:11,080 Speaker 1: perception of the universe. It's like a small example of 80 00:04:11,120 --> 00:04:12,720 Speaker 1: all the ways that the universe could be. It's like 81 00:04:12,720 --> 00:04:14,920 Speaker 1: you're playing the warm up levels on some video game 82 00:04:15,120 --> 00:04:17,160 Speaker 1: before all the bad guys come in, just you can 83 00:04:17,240 --> 00:04:19,400 Speaker 1: sort of like figure out how the controls work. Right, 84 00:04:19,640 --> 00:04:22,160 Speaker 1: That's what we've been doing for physics for like thousands 85 00:04:22,200 --> 00:04:25,480 Speaker 1: of years, and now we finally understand the full scope 86 00:04:25,480 --> 00:04:27,680 Speaker 1: of the game. And wouldn't be great a good respond 87 00:04:28,880 --> 00:04:31,240 Speaker 1: in this universe? We can just keep trying, well, we 88 00:04:31,279 --> 00:04:34,040 Speaker 1: sort of do. I mean, like physicists start from where 89 00:04:34,200 --> 00:04:36,600 Speaker 1: previous generations of physicists ended, right, We don't have to 90 00:04:36,600 --> 00:04:39,880 Speaker 1: start from scratch on physics every single generation. So physics 91 00:04:39,920 --> 00:04:42,000 Speaker 1: sort of responds in our minds, right, And we're going 92 00:04:42,040 --> 00:04:44,040 Speaker 1: to run out of lives at some point. Do we 93 00:04:44,080 --> 00:04:46,640 Speaker 1: need to put in more quarters into the arcade of 94 00:04:46,640 --> 00:04:50,599 Speaker 1: the universe? That depends on the alien death right or 95 00:04:50,640 --> 00:04:53,560 Speaker 1: the joke ray Neither one might help us or not 96 00:04:53,640 --> 00:04:56,320 Speaker 1: help us. But yeah, the universe is kind of tricky, 97 00:04:56,520 --> 00:04:59,640 Speaker 1: and it's tricky not just in like extreme situations like 98 00:04:59,680 --> 00:05:01,280 Speaker 1: in a that hole or moving on close to the 99 00:05:01,279 --> 00:05:03,680 Speaker 1: speed of light, because who knows, like we could be 100 00:05:03,720 --> 00:05:07,200 Speaker 1: moving right now really fast compared to other aliens and 101 00:05:07,240 --> 00:05:09,960 Speaker 1: other galaxies right we are. We are moving really fast 102 00:05:10,000 --> 00:05:12,239 Speaker 1: compared to the Sun, and the Sun is moving really 103 00:05:12,240 --> 00:05:14,840 Speaker 1: fast compared to the center of the galaxy. But all 104 00:05:14,880 --> 00:05:17,520 Speaker 1: those things are kind of abstract. What really matters is 105 00:05:17,560 --> 00:05:20,479 Speaker 1: your speed relative to the people who are watching you 106 00:05:20,640 --> 00:05:24,240 Speaker 1: and relative to your clock. And so that's something that 107 00:05:24,360 --> 00:05:27,320 Speaker 1: special relativity has taught us, is that the world looks 108 00:05:27,440 --> 00:05:30,839 Speaker 1: different from different perspectives. Based on who's doing the measuring. 109 00:05:31,160 --> 00:05:33,359 Speaker 1: You can get kind of a different account of what's 110 00:05:33,360 --> 00:05:35,680 Speaker 1: going on and what's happened in the world. Yeah, you 111 00:05:35,760 --> 00:05:39,599 Speaker 1: might not agree with your relatives about relativity, but yeah, 112 00:05:39,640 --> 00:05:42,160 Speaker 1: things are kind of tricky in this universe, and so 113 00:05:42,720 --> 00:05:45,160 Speaker 1: even physicists sort of struggle with it, right, I mean, 114 00:05:45,160 --> 00:05:48,320 Speaker 1: it's sort of hard to rab anyone's head around these 115 00:05:48,440 --> 00:05:52,080 Speaker 1: topics and how it actually works. And and so physicists 116 00:05:52,120 --> 00:05:54,880 Speaker 1: have some ways to kind of think about how these 117 00:05:54,920 --> 00:05:57,760 Speaker 1: things work that might help other people. Yeah, because in 118 00:05:57,800 --> 00:06:00,600 Speaker 1: science we have our intuition, like give a fling about 119 00:06:00,640 --> 00:06:03,320 Speaker 1: how things might work and what might happen and how 120 00:06:03,360 --> 00:06:06,440 Speaker 1: things are put together. And then there's the mathematics. And 121 00:06:06,440 --> 00:06:09,520 Speaker 1: the mathematics is what actually happens, what really is going on, 122 00:06:09,839 --> 00:06:12,919 Speaker 1: the rules that really do control the universe. But sometimes 123 00:06:12,960 --> 00:06:15,159 Speaker 1: you're looking at like a page of equations and you're like, 124 00:06:15,560 --> 00:06:17,760 Speaker 1: I don't see it. I don't really get it. And 125 00:06:17,839 --> 00:06:20,640 Speaker 1: for me personally, it's easier to think about these things 126 00:06:20,680 --> 00:06:24,640 Speaker 1: like geometrically to understand like the relationship in space and 127 00:06:24,760 --> 00:06:27,360 Speaker 1: time of these things. So sometimes you can get more 128 00:06:27,400 --> 00:06:30,560 Speaker 1: of an intuition for weird things if you think about 129 00:06:30,560 --> 00:06:33,279 Speaker 1: their structure and space and time sort of geometrically, like 130 00:06:33,360 --> 00:06:36,680 Speaker 1: the shapes that are created by all of these ideas, right, 131 00:06:36,760 --> 00:06:39,159 Speaker 1: and then you draw cartoons about it, which is where 132 00:06:40,440 --> 00:06:43,719 Speaker 1: right exactly? It helps to draw cartoons, no joke. Cartoons 133 00:06:43,720 --> 00:06:46,000 Speaker 1: are a great way to visualize this stuff. That's why 134 00:06:46,040 --> 00:06:47,919 Speaker 1: you and I work together on a lot of these books, 135 00:06:48,120 --> 00:06:50,320 Speaker 1: and folks out there should check out our book We 136 00:06:50,400 --> 00:06:53,200 Speaker 1: Have No Idea, which has all sorts of really clever 137 00:06:53,240 --> 00:06:57,440 Speaker 1: cartoons visualizing really tricky concepts. Yeah, and our upcoming book 138 00:06:57,440 --> 00:07:00,560 Speaker 1: which is coming out in a few months frequently questions 139 00:07:00,600 --> 00:07:03,640 Speaker 1: about the universe, which you can pre order right now. Man, 140 00:07:03,640 --> 00:07:07,080 Speaker 1: we totally snuck in those book plugs, Daniel, totally unplanned. 141 00:07:07,279 --> 00:07:09,600 Speaker 1: I keep getting emails from listeners saying, you guys should 142 00:07:09,600 --> 00:07:11,480 Speaker 1: write a book. I'm like, what do we not talk 143 00:07:11,520 --> 00:07:13,600 Speaker 1: about the book enough on the podcast? I guess I 144 00:07:13,720 --> 00:07:15,760 Speaker 1: guess we don't. We should talk about it every time. 145 00:07:16,040 --> 00:07:19,080 Speaker 1: I think we should, honestly. Anyway, back to the podcast. Yeah, 146 00:07:19,120 --> 00:07:20,880 Speaker 1: back to the podcast. Let's talk about one of these 147 00:07:21,120 --> 00:07:23,440 Speaker 1: tools that physicists used to kind of wrap your head 148 00:07:23,480 --> 00:07:26,080 Speaker 1: around some of these tricky concepts about relativity and the 149 00:07:26,080 --> 00:07:28,360 Speaker 1: speed of light. So today on the podcast, we'll be 150 00:07:28,400 --> 00:07:37,880 Speaker 1: asking the question, what is a light cone? Daniel, this 151 00:07:38,080 --> 00:07:40,400 Speaker 1: is a light coming, I think, I guess you mean light, 152 00:07:40,520 --> 00:07:44,280 Speaker 1: not like not heavy cone is exactly light as in 153 00:07:44,360 --> 00:07:47,280 Speaker 1: photons is and that thing that speeds along at the 154 00:07:47,440 --> 00:07:50,800 Speaker 1: maximum speed of the universe. Now, this sounds sort of 155 00:07:50,840 --> 00:07:53,640 Speaker 1: like maybe a dessert, but maybe we're not a dessert 156 00:07:53,720 --> 00:07:55,880 Speaker 1: you want to eat or that would taste very good. 157 00:07:56,160 --> 00:07:57,960 Speaker 1: Sounds like the kind of dessert your mom would order 158 00:07:57,960 --> 00:08:00,800 Speaker 1: for you when what you really want is scubavice. Where 159 00:08:00,840 --> 00:08:03,320 Speaker 1: you really want is a heavy cone, the heavy cream cone. 160 00:08:03,560 --> 00:08:06,960 Speaker 1: You don't want the like fat free light cone. But yeah, 161 00:08:07,000 --> 00:08:09,720 Speaker 1: So this is a concept that comes up in special 162 00:08:09,760 --> 00:08:14,640 Speaker 1: relativity and it has some pretty interesting consequences about causality 163 00:08:14,920 --> 00:08:18,600 Speaker 1: and like what's actually real or like what's actually happening 164 00:08:19,080 --> 00:08:21,240 Speaker 1: or happened in the universe. Yeah, and it helps you 165 00:08:21,280 --> 00:08:24,240 Speaker 1: think about what's going on inside a black hole and 166 00:08:24,400 --> 00:08:27,480 Speaker 1: even possibly maybe allows you to figure out a way 167 00:08:27,520 --> 00:08:31,360 Speaker 1: to do real life time travel. Sounds like a very 168 00:08:31,400 --> 00:08:34,720 Speaker 1: powerful dessert here. All right, Well, before we go on, 169 00:08:34,800 --> 00:08:37,080 Speaker 1: we just want to give a quick shout out to Biorn, 170 00:08:37,840 --> 00:08:40,680 Speaker 1: right he sort of helped inspire this episode. Daniel. Yeah, 171 00:08:40,720 --> 00:08:43,520 Speaker 1: thanks Born from Sweden who sent me a link to 172 00:08:43,640 --> 00:08:47,199 Speaker 1: his Solar System inspired music which I listened to while 173 00:08:47,240 --> 00:08:49,960 Speaker 1: preparing for this podcast. You can find him on Spotify 174 00:08:50,080 --> 00:08:52,560 Speaker 1: at ord cloud Services. Check them out if you like 175 00:08:52,600 --> 00:08:55,320 Speaker 1: the sort of space ambiance music. Thanks a lot, Biorn 176 00:08:55,400 --> 00:08:57,920 Speaker 1: for sharing music. Yeah, and again that's or Clouds. That's 177 00:08:57,960 --> 00:09:01,559 Speaker 1: o RT cloud service is on Spotify, which is a 178 00:09:01,640 --> 00:09:05,000 Speaker 1: pun because it's like the Orc Cloud and also cloud services. 179 00:09:05,040 --> 00:09:07,400 Speaker 1: And what is the orc cloud done for us recently? Well, 180 00:09:07,440 --> 00:09:10,760 Speaker 1: I guess it delivers spacey music and you can upload 181 00:09:10,800 --> 00:09:13,480 Speaker 1: your pictures to it. You might never get them back, 182 00:09:13,640 --> 00:09:16,360 Speaker 1: but yeah, you can upload them. It probably takes like 183 00:09:16,360 --> 00:09:18,960 Speaker 1: twenty years just to get there, and then the download 184 00:09:19,000 --> 00:09:23,360 Speaker 1: speed it's probably even worse. All right, Well, we were curious, 185 00:09:23,360 --> 00:09:25,840 Speaker 1: as usually how many people out there are familiar with 186 00:09:25,920 --> 00:09:28,960 Speaker 1: the concept we're talking about today. So Daniel went out 187 00:09:28,960 --> 00:09:31,960 Speaker 1: there into the internet to ask people what is a 188 00:09:32,160 --> 00:09:34,280 Speaker 1: light cone? And if you are out there on the 189 00:09:34,320 --> 00:09:38,040 Speaker 1: internet and always wanted to participate in a podcast, please 190 00:09:38,040 --> 00:09:40,560 Speaker 1: write to us two questions at Daniel and Jorge dot 191 00:09:40,559 --> 00:09:43,280 Speaker 1: com and you can be unprepared to answer future questions 192 00:09:43,320 --> 00:09:46,000 Speaker 1: for the podcast. Right, And if you're not on the Internet, 193 00:09:46,040 --> 00:09:48,960 Speaker 1: please tell us your secret. I mean I would to 194 00:09:49,360 --> 00:09:52,200 Speaker 1: sometimes not be on the Internet. I guess we're on 195 00:09:52,240 --> 00:09:55,280 Speaker 1: the radio too, right, Daniel. I think some stations broadcasts, 196 00:09:55,280 --> 00:09:57,959 Speaker 1: so they might be listening on the radio. Yeah, So 197 00:09:58,120 --> 00:10:00,160 Speaker 1: thanks everybody who's out there listening to us on the 198 00:10:00,280 --> 00:10:02,480 Speaker 1: radio as well. We appreciate all of your support and 199 00:10:02,520 --> 00:10:04,559 Speaker 1: all of your listening. Did you know that we recently 200 00:10:04,600 --> 00:10:10,160 Speaker 1: passed fifteen million episode downloads? Wow? Really, it's amazing. That's 201 00:10:10,160 --> 00:10:13,360 Speaker 1: like fifty million hours that people have been listening to us. 202 00:10:13,480 --> 00:10:17,439 Speaker 1: That's like fifteen million banana jokes at least at least 203 00:10:17,480 --> 00:10:20,720 Speaker 1: because you know, we're a multi banana joke death Ray 204 00:10:20,760 --> 00:10:22,760 Speaker 1: a joke Ray here. We try to in our in 205 00:10:22,760 --> 00:10:26,400 Speaker 1: our best episodes, like a shotgun rate joke. Really, we 206 00:10:26,600 --> 00:10:29,079 Speaker 1: just splatter bananappeals all over the place and now I 207 00:10:29,200 --> 00:10:32,400 Speaker 1: imagining fifteen million tiny bananas coming out of the nozzle 208 00:10:32,400 --> 00:10:35,080 Speaker 1: of a gun at very high to be coming out 209 00:10:35,080 --> 00:10:39,720 Speaker 1: of our mouth, that's a little disturbing. But anyways, think 210 00:10:39,760 --> 00:10:41,760 Speaker 1: about it for a second. If someone asked you what 211 00:10:41,880 --> 00:10:44,880 Speaker 1: do you think a light cone is? What would you say? 212 00:10:45,040 --> 00:10:47,360 Speaker 1: Here's what people had to say. I would say, that's 213 00:10:47,360 --> 00:10:50,560 Speaker 1: what comes out of the shiny end of a flash light. Um. 214 00:10:50,600 --> 00:10:54,520 Speaker 1: I believe this is a space time diagram where it 215 00:10:54,640 --> 00:10:59,719 Speaker 1: shows a three dimensional object and as you go up, 216 00:11:01,000 --> 00:11:04,679 Speaker 1: that's time passing, so it makes a calm like if 217 00:11:04,679 --> 00:11:06,760 Speaker 1: you look at the diagram of the Big Bang and 218 00:11:06,760 --> 00:11:09,360 Speaker 1: are we sure a tiny point? Then it slowly goes 219 00:11:09,440 --> 00:11:13,000 Speaker 1: up into a cone as time progresses. Um. I don't 220 00:11:13,000 --> 00:11:16,280 Speaker 1: know what a light cone is. I'm thinking about there 221 00:11:16,400 --> 00:11:21,840 Speaker 1: was some propulsion the idea that was. I think it 222 00:11:21,920 --> 00:11:24,640 Speaker 1: was largely theoretical, but it was to do with kind 223 00:11:24,679 --> 00:11:29,960 Speaker 1: of using light to push spacecraft and it would capture 224 00:11:30,000 --> 00:11:32,320 Speaker 1: the light using light sales. I don't know if that 225 00:11:32,360 --> 00:11:34,240 Speaker 1: would be to do with it. I remember seeing a 226 00:11:34,280 --> 00:11:37,839 Speaker 1: model in the Science Museum in London, but there was 227 00:11:37,880 --> 00:11:39,920 Speaker 1: a cone, but that was probably just because it was 228 00:11:39,960 --> 00:11:47,480 Speaker 1: made of plastic. Light corne is representation of how from 229 00:11:47,520 --> 00:11:52,560 Speaker 1: the light travels from a point. For instance, if you 230 00:11:52,840 --> 00:11:56,360 Speaker 1: have if I have a little flash light in my hand, 231 00:11:56,360 --> 00:12:02,120 Speaker 1: then I turned it on the lightbulb trouble in space 232 00:12:02,200 --> 00:12:08,240 Speaker 1: and time. Like cone, you can represent it as a cone. 233 00:12:09,240 --> 00:12:13,079 Speaker 1: That is something I've heard of before. Um, it's the 234 00:12:13,120 --> 00:12:16,280 Speaker 1: realm of like what you can see. So it's like 235 00:12:16,400 --> 00:12:20,959 Speaker 1: ninety three billion light years across as in our observable universe, 236 00:12:21,000 --> 00:12:24,240 Speaker 1: because that's like how far we could observes or something 237 00:12:25,000 --> 00:12:28,880 Speaker 1: into space, or like the photons that have reached us 238 00:12:29,440 --> 00:12:33,640 Speaker 1: from that distance. Although I don't understand how that's bigger 239 00:12:33,679 --> 00:12:37,040 Speaker 1: than thirteen point eight billion light years since that's the 240 00:12:37,080 --> 00:12:40,120 Speaker 1: age of the universe. But I'm still quite unclear on that. 241 00:12:40,160 --> 00:12:42,880 Speaker 1: But I know that the light cone is basically all 242 00:12:42,880 --> 00:12:46,400 Speaker 1: that we can see within our realm of light, anything 243 00:12:46,440 --> 00:12:49,280 Speaker 1: that can reach us in any form. I think a 244 00:12:49,360 --> 00:12:52,920 Speaker 1: light cone is an ice cream cone that's been left 245 00:12:52,920 --> 00:12:54,600 Speaker 1: out in the sun too long and all the ice 246 00:12:54,600 --> 00:12:58,360 Speaker 1: cream melted. A light cone is an ice cream cone 247 00:12:58,440 --> 00:13:01,400 Speaker 1: that has no chocolate ice cream minute whatsoever, which is 248 00:13:02,120 --> 00:13:04,839 Speaker 1: fundamentally flawed, and I think it violates one of the 249 00:13:04,920 --> 00:13:07,880 Speaker 1: laws of thermodynamics, because why would you want vanilla ice cream? 250 00:13:07,920 --> 00:13:10,880 Speaker 1: One chocolate is an option, so light cones make no sense. 251 00:13:11,440 --> 00:13:14,720 Speaker 1: All right. A lot of people went with my interpretation, 252 00:13:14,800 --> 00:13:18,160 Speaker 1: which is that it sounds like a dessert possibly and 253 00:13:18,240 --> 00:13:20,400 Speaker 1: that it's light. Yeah, and we also heard some people 254 00:13:20,440 --> 00:13:23,360 Speaker 1: throwing shade on vanilla ice cream. Wow, that was rough. 255 00:13:23,600 --> 00:13:26,079 Speaker 1: I know, how can you be down in vanilla ice cream? 256 00:13:26,400 --> 00:13:30,199 Speaker 1: It's like the nicest flavor gets along with everybody. That's true. 257 00:13:30,200 --> 00:13:32,880 Speaker 1: I mean I would always pick chocolate over vanilla. But 258 00:13:32,960 --> 00:13:35,000 Speaker 1: you know, if all you got is vanilla, I'm happy 259 00:13:35,000 --> 00:13:37,560 Speaker 1: to get. But if you take vanilla and sprinkle chocolate 260 00:13:37,600 --> 00:13:41,040 Speaker 1: on it, see that's the versatility of vanilla. Or take 261 00:13:41,120 --> 00:13:44,280 Speaker 1: chocolate and sprinkled chocolate on it, it's still better. But 262 00:13:44,320 --> 00:13:46,680 Speaker 1: you can't take chocolate and sprinkle vanilla on it. That's 263 00:13:46,760 --> 00:13:49,360 Speaker 1: when you do. That's vanilla doesn't add to anything. It's 264 00:13:49,400 --> 00:13:53,160 Speaker 1: just sort of like the substrate he lean. It makes 265 00:13:53,200 --> 00:13:55,920 Speaker 1: most cookies taste good. It's just sort of vanilla. That's 266 00:13:55,960 --> 00:13:58,360 Speaker 1: the reason why they call it vanilla vanilla, you know, 267 00:13:58,960 --> 00:14:02,720 Speaker 1: because it's so dependent and solid and she just always 268 00:14:02,760 --> 00:14:05,920 Speaker 1: there for you. Right. If somebody reads you're writing and 269 00:14:05,960 --> 00:14:07,720 Speaker 1: they describe it as a vanilla. Would you take that 270 00:14:07,760 --> 00:14:11,080 Speaker 1: as a compliment? Depends am I writing the bag of 271 00:14:11,120 --> 00:14:13,840 Speaker 1: an ice cream carton? Then it would meet its cool 272 00:14:14,440 --> 00:14:17,160 Speaker 1: But yeah, so a light cone, Daniel tell me, this 273 00:14:17,240 --> 00:14:19,840 Speaker 1: is something I was surprised to see in our topic 274 00:14:19,960 --> 00:14:23,480 Speaker 1: because it is it's like a graphical interpretation of physics, right, 275 00:14:23,760 --> 00:14:26,320 Speaker 1: And so it's a little tricky to describe on a podcast. 276 00:14:26,400 --> 00:14:28,360 Speaker 1: It's a little tricky to describe on a podcast. We'll 277 00:14:28,400 --> 00:14:30,920 Speaker 1: see how we do. But I thought it was useful 278 00:14:30,920 --> 00:14:33,800 Speaker 1: because I find that every time we talk about special relativity, 279 00:14:33,920 --> 00:14:36,440 Speaker 1: I have light cones in my mind. I got these 280 00:14:36,440 --> 00:14:39,440 Speaker 1: things in my brain. They really helped me think about 281 00:14:39,560 --> 00:14:42,400 Speaker 1: sort of the structure of space and time, and they 282 00:14:42,480 --> 00:14:44,520 Speaker 1: lead to a lot of interesting consequences. And so I 283 00:14:44,560 --> 00:14:47,400 Speaker 1: hope if we can somehow download the concept of a 284 00:14:47,480 --> 00:14:49,640 Speaker 1: light cone into the minds of our listeners, it will 285 00:14:49,680 --> 00:14:52,120 Speaker 1: help them think about special relativity. We need like a 286 00:14:52,200 --> 00:14:55,160 Speaker 1: light cone ray to shoot listen to people. Maybe, Yeah, 287 00:14:55,200 --> 00:14:57,200 Speaker 1: I think it's a podcast starring me and you're talking 288 00:14:57,200 --> 00:15:01,840 Speaker 1: about throwing out vananative. All right, well, m step us 289 00:15:01,840 --> 00:15:05,000 Speaker 1: through it. What is technically a light cone? So a 290 00:15:05,120 --> 00:15:08,840 Speaker 1: light cone defines the part of the universe that you 291 00:15:08,880 --> 00:15:12,240 Speaker 1: can influence, the part of the future that you can 292 00:15:12,440 --> 00:15:16,120 Speaker 1: visit geometrically. And you can think about it like if 293 00:15:16,160 --> 00:15:18,840 Speaker 1: you turn on a flashlight for a moment, so you 294 00:15:19,160 --> 00:15:21,880 Speaker 1: shine photons in every direction, they leave you in sort 295 00:15:21,920 --> 00:15:24,280 Speaker 1: of a spear. After one second, they are one light 296 00:15:24,360 --> 00:15:27,840 Speaker 1: second away from you. After one year, they are one 297 00:15:28,000 --> 00:15:30,560 Speaker 1: light year away from you. So imagine a sphere and 298 00:15:30,600 --> 00:15:34,240 Speaker 1: then that sphere sort of growing as time goes on, right, 299 00:15:34,520 --> 00:15:38,360 Speaker 1: So that set of spears versus time as those spears grow, 300 00:15:38,640 --> 00:15:41,080 Speaker 1: this is your future light cone. This is the part 301 00:15:41,160 --> 00:15:45,120 Speaker 1: of the universe that you can influence where your choices, 302 00:15:45,160 --> 00:15:47,360 Speaker 1: the things that you do as a person could have 303 00:15:47,520 --> 00:15:51,600 Speaker 1: sort of an effect downstream. It's very easy to understand why. 304 00:15:52,000 --> 00:15:55,040 Speaker 1: The reason is that everything that's outside of that growing 305 00:15:55,080 --> 00:15:58,760 Speaker 1: set of spears you can't influence because information would have 306 00:15:58,800 --> 00:16:01,840 Speaker 1: to travel faster and the speed of light to get there. 307 00:16:02,000 --> 00:16:03,680 Speaker 1: So it's a direct outcome of the fact that we 308 00:16:03,720 --> 00:16:06,760 Speaker 1: have a maximum speed limit to the universe. It divides 309 00:16:06,880 --> 00:16:09,920 Speaker 1: the universe into parts that you can influence and parts 310 00:16:10,000 --> 00:16:12,440 Speaker 1: you cannot. So the light cone is the part of 311 00:16:12,480 --> 00:16:15,640 Speaker 1: these universe, including the future. Right, we're talking space and 312 00:16:15,760 --> 00:16:18,680 Speaker 1: time here, the part of the future universe that you 313 00:16:18,680 --> 00:16:21,000 Speaker 1: can have any sort of influence over. So I turn 314 00:16:21,080 --> 00:16:24,040 Speaker 1: on a light like a light bulb, and that light 315 00:16:24,240 --> 00:16:27,080 Speaker 1: is growing comes out of the light bulb of growth 316 00:16:27,160 --> 00:16:30,000 Speaker 1: in a sphere, and you're saying, that's the light cone. 317 00:16:30,000 --> 00:16:31,840 Speaker 1: So it really should be called like a light sphere. 318 00:16:31,880 --> 00:16:34,480 Speaker 1: Maybe it'd be a better name, like the light sphere 319 00:16:34,640 --> 00:16:40,280 Speaker 1: is the sphere around you which you can reach with light. 320 00:16:40,520 --> 00:16:42,360 Speaker 1: The reason it's often called the light cone is that 321 00:16:42,400 --> 00:16:45,480 Speaker 1: it's hard to draw four dimensions on a sheet of paper. 322 00:16:45,800 --> 00:16:47,160 Speaker 1: The most we can really draw on a sheet of 323 00:16:47,200 --> 00:16:50,560 Speaker 1: papers three dimensions, you know, by having like some perspective, 324 00:16:50,920 --> 00:16:52,880 Speaker 1: and so you need to have time on there. So 325 00:16:52,960 --> 00:16:55,520 Speaker 1: you can really only have two other dimensions of space 326 00:16:55,800 --> 00:16:57,560 Speaker 1: on your sheet of paper. And so when you're drawing 327 00:16:57,600 --> 00:17:00,880 Speaker 1: these diagrams, people typically treats base as if it was 328 00:17:00,920 --> 00:17:03,600 Speaker 1: a two D surface instead of like our three D world, 329 00:17:03,880 --> 00:17:06,440 Speaker 1: just to sort of simplify it. So in two dimensions 330 00:17:06,960 --> 00:17:10,280 Speaker 1: the sphere we were just talking about, it becomes a circle. Right. Imagine, 331 00:17:10,320 --> 00:17:13,600 Speaker 1: for example, taking a smooth sheet of water and hitting 332 00:17:13,640 --> 00:17:16,560 Speaker 1: it somewhere. What happens you have a wave that leaves 333 00:17:16,560 --> 00:17:19,040 Speaker 1: where you hit it and it travels outwards. So now 334 00:17:19,080 --> 00:17:21,240 Speaker 1: you get a set of circles. Now, if you take 335 00:17:21,280 --> 00:17:23,800 Speaker 1: those set of circles and you extend them like vertically 336 00:17:23,840 --> 00:17:27,680 Speaker 1: above the surface in time and make time that vertical direction, 337 00:17:27,960 --> 00:17:30,160 Speaker 1: then what you get is a cone. Right. It starts 338 00:17:30,160 --> 00:17:32,440 Speaker 1: from a point when you hit the surface of the water, 339 00:17:32,680 --> 00:17:35,320 Speaker 1: and then as time goes on, that circle gets larger 340 00:17:35,320 --> 00:17:38,040 Speaker 1: and larger, and that defines a cone. So it's a 341 00:17:38,080 --> 00:17:41,040 Speaker 1: cone only in a sort of universe that has two 342 00:17:41,080 --> 00:17:44,320 Speaker 1: spatial dimensions and one time dimension. Right, It's kind of 343 00:17:44,320 --> 00:17:46,440 Speaker 1: like if you take a slice of those light spheres 344 00:17:46,520 --> 00:17:48,600 Speaker 1: we were talking about, Like if you take a slice 345 00:17:48,640 --> 00:17:50,920 Speaker 1: of it and you see those that circle on that 346 00:17:51,119 --> 00:17:56,720 Speaker 1: slice growing, and then you imagine that circle growing but 347 00:17:56,800 --> 00:17:59,520 Speaker 1: growing and also moving up maybe at the same time, 348 00:18:00,040 --> 00:18:02,639 Speaker 1: it kind of makes like a cone, yeah, exactly, and 349 00:18:02,680 --> 00:18:05,080 Speaker 1: it moves up because now we're imagining time to be 350 00:18:05,119 --> 00:18:07,399 Speaker 1: one of our axes. Right, we have two dimensions of 351 00:18:07,440 --> 00:18:10,760 Speaker 1: space and we have another direction, which is time. And 352 00:18:10,800 --> 00:18:13,760 Speaker 1: obviously things just flow forward in time at one second 353 00:18:13,760 --> 00:18:17,400 Speaker 1: per second, and so this circle just sort of grows 354 00:18:17,680 --> 00:18:20,680 Speaker 1: in time. If you instead had something which wasn't moving. Right, 355 00:18:20,800 --> 00:18:23,560 Speaker 1: if you just like drew a circle around you, then 356 00:18:23,640 --> 00:18:27,199 Speaker 1: that circle would slide through time and make a cylinder, right, 357 00:18:27,240 --> 00:18:29,840 Speaker 1: because it wouldn't be growing. But if it is growing, 358 00:18:29,880 --> 00:18:31,640 Speaker 1: then it makes a cone. It starts from the point 359 00:18:31,640 --> 00:18:34,040 Speaker 1: where you've made it, and it makes a cone. And 360 00:18:34,160 --> 00:18:36,000 Speaker 1: I guess if you're having trail visual license, you can 361 00:18:36,000 --> 00:18:38,520 Speaker 1: always just pop on Google images or something and look 362 00:18:38,560 --> 00:18:41,439 Speaker 1: for light cone. I imagine you'll get a picture of this, right. 363 00:18:41,880 --> 00:18:44,520 Speaker 1: How do people do podcast before Google image search anymore? 364 00:18:45,240 --> 00:18:51,640 Speaker 1: They probably avoided topics that involved geometry and and multiple dimensions. 365 00:18:51,720 --> 00:18:53,960 Speaker 1: But it's kind of an interesting concept, and I think 366 00:18:54,040 --> 00:18:57,119 Speaker 1: you as a physics you like it because it defines 367 00:18:57,400 --> 00:19:00,240 Speaker 1: kind of like a volume, right. It defines kind of 368 00:19:00,280 --> 00:19:03,440 Speaker 1: like a set of space time that is either inside 369 00:19:03,480 --> 00:19:05,600 Speaker 1: the cone or outside the cone. That's kind of the 370 00:19:05,680 --> 00:19:08,679 Speaker 1: power of this kind of visualization. Yeah, and it's not 371 00:19:08,760 --> 00:19:10,919 Speaker 1: just arbitrary, like you can make whatever shape you want 372 00:19:10,920 --> 00:19:13,600 Speaker 1: in spacetime. But this one is special. This one is 373 00:19:13,680 --> 00:19:17,480 Speaker 1: really important because everything that's inside your future light cone 374 00:19:17,880 --> 00:19:21,160 Speaker 1: are things that you can influence. Right. You can't send 375 00:19:21,160 --> 00:19:24,600 Speaker 1: the message to anything outside your future light cone, like 376 00:19:24,640 --> 00:19:27,880 Speaker 1: anything outside your future. Light cone by definition, is too 377 00:19:27,920 --> 00:19:30,880 Speaker 1: far away for any message to reach because you would 378 00:19:30,920 --> 00:19:33,400 Speaker 1: have to travel faster than the speed of light. And 379 00:19:33,680 --> 00:19:35,520 Speaker 1: if you can send a message, it means you can't 380 00:19:35,600 --> 00:19:38,840 Speaker 1: send any information. That means you can't influence it at all. 381 00:19:39,119 --> 00:19:41,639 Speaker 1: And one of the really tricky, complicated things about special 382 00:19:41,640 --> 00:19:44,560 Speaker 1: relativity is that it plays sometimes with the order of 383 00:19:44,600 --> 00:19:47,439 Speaker 1: events and it seems to have consequences for causality. So 384 00:19:47,600 --> 00:19:49,720 Speaker 1: this helps you sort of keep track of that the 385 00:19:50,000 --> 00:19:52,600 Speaker 1: part of the universe that you can influence, and also 386 00:19:53,040 --> 00:19:56,679 Speaker 1: looking backwards, the part of the universe that can influence you. Right, 387 00:19:56,720 --> 00:19:58,560 Speaker 1: all right, Well, it's get into some of these weird 388 00:19:58,640 --> 00:20:02,520 Speaker 1: consequences for because reality and simultaneity and alien death rays. 389 00:20:03,440 --> 00:20:18,640 Speaker 1: But first let's take a quick break. Alright. We're talking 390 00:20:18,640 --> 00:20:22,800 Speaker 1: about the speed of light, causality, the universe, and light cones, 391 00:20:23,200 --> 00:20:25,960 Speaker 1: which are sort of like a visualization in physics that 392 00:20:26,080 --> 00:20:29,480 Speaker 1: help you kind of figure out what you can't affect 393 00:20:29,520 --> 00:20:33,040 Speaker 1: and what you cannot affect because I guess that's something 394 00:20:33,119 --> 00:20:36,680 Speaker 1: is far enough away you can't affect it right now, 395 00:20:36,760 --> 00:20:38,359 Speaker 1: right because you have to wait for the speed of 396 00:20:38,440 --> 00:20:41,359 Speaker 1: light to get from here there or there to hear 397 00:20:41,440 --> 00:20:44,000 Speaker 1: it doesn't even have to be far away. Something that's 398 00:20:44,080 --> 00:20:47,040 Speaker 1: one foot away from you, like literally one foot away 399 00:20:47,040 --> 00:20:49,919 Speaker 1: from you right now. You can have no influence on 400 00:20:49,960 --> 00:20:53,199 Speaker 1: what's happening right there, right now, because even if you 401 00:20:53,240 --> 00:20:55,800 Speaker 1: shot your death ray, it would only affect what's happening 402 00:20:55,800 --> 00:20:57,680 Speaker 1: to foot away from you in the time it takes 403 00:20:57,720 --> 00:20:59,760 Speaker 1: for light to travel from the tip of your death 404 00:20:59,840 --> 00:21:03,160 Speaker 1: ray one foot. There's nothing you can do about what's 405 00:21:03,200 --> 00:21:06,840 Speaker 1: happening one foot away from you right now. Oh wow, 406 00:21:06,880 --> 00:21:09,760 Speaker 1: that's kind of weird, right to know that there's stuff 407 00:21:09,800 --> 00:21:12,280 Speaker 1: around me that is unaccessible to me. Yeah, I mean, 408 00:21:12,520 --> 00:21:14,800 Speaker 1: even if you're seeing something that happens a foot away 409 00:21:14,840 --> 00:21:16,640 Speaker 1: from you, that means it actually happened in the past, 410 00:21:16,680 --> 00:21:19,959 Speaker 1: so it's already done anyway. Right, So all you can 411 00:21:20,000 --> 00:21:23,000 Speaker 1: do is affect the future, right That seems obvious. But 412 00:21:23,080 --> 00:21:25,720 Speaker 1: you also can't affect the future everywhere, Like if you 413 00:21:25,760 --> 00:21:29,000 Speaker 1: want to change the future of Andromeda, you know intuitively, 414 00:21:29,040 --> 00:21:31,800 Speaker 1: you can't change the future of Andromeda tomorrow or the 415 00:21:31,840 --> 00:21:34,320 Speaker 1: next day, or even the next year. It would take 416 00:21:34,400 --> 00:21:37,280 Speaker 1: millions of years for any decision you make to affect 417 00:21:37,359 --> 00:21:41,200 Speaker 1: anything in Andromeda, because nothing you do will get there. 418 00:21:41,280 --> 00:21:44,320 Speaker 1: No choices you make can propagate that far before a 419 00:21:44,400 --> 00:21:47,800 Speaker 1: million years because it's a million light years away, right, Yeah, 420 00:21:47,800 --> 00:21:50,840 Speaker 1: I guess that's the big consequence of having a speed 421 00:21:50,840 --> 00:21:53,480 Speaker 1: limit in the universe is this idea that you know 422 00:21:53,720 --> 00:21:56,679 Speaker 1: there are things in the present, but you can't really 423 00:21:57,359 --> 00:21:59,919 Speaker 1: touch them, more affect them, or even know what they 424 00:22:00,040 --> 00:22:03,119 Speaker 1: are right now in the same president as you. That's right, 425 00:22:03,160 --> 00:22:06,560 Speaker 1: there's a limit on the information and how information travels. 426 00:22:06,600 --> 00:22:09,480 Speaker 1: It's really fascinating. You can only ever see one slice 427 00:22:09,520 --> 00:22:12,120 Speaker 1: of the universe, and your slice the universe might tell 428 00:22:12,119 --> 00:22:14,480 Speaker 1: a different story from other slices of the universe. And 429 00:22:14,840 --> 00:22:16,960 Speaker 1: this is really hard to get into your head because 430 00:22:16,960 --> 00:22:19,720 Speaker 1: you imagine that what we're doing with physics is trying 431 00:22:19,760 --> 00:22:22,400 Speaker 1: to build up like an absolute picture of the universe, 432 00:22:22,520 --> 00:22:25,720 Speaker 1: like what's really out there, what is really going on, 433 00:22:25,840 --> 00:22:28,560 Speaker 1: what happened in the universe, and what's going to happen, 434 00:22:28,640 --> 00:22:31,320 Speaker 1: And it's hard to accept that one you can never 435 00:22:31,359 --> 00:22:33,600 Speaker 1: really know everything about what's going on in the universe 436 00:22:33,840 --> 00:22:36,159 Speaker 1: because you're limited to the slice of information you're going 437 00:22:36,240 --> 00:22:38,480 Speaker 1: to get, but also that what you do learn about 438 00:22:38,480 --> 00:22:41,240 Speaker 1: the universe might not be like the absolute truth. It 439 00:22:41,359 --> 00:22:45,040 Speaker 1: might just be like what things look like from your perspective, right. 440 00:22:45,080 --> 00:22:46,960 Speaker 1: I think we talked about this once in the podcast. 441 00:22:47,040 --> 00:22:50,840 Speaker 1: It's like, imagine like how the human society was before 442 00:22:50,920 --> 00:22:54,520 Speaker 1: the Internet or before telecommunications, you know, when we had 443 00:22:54,560 --> 00:22:58,159 Speaker 1: to rely on writing letters and you know, waiting for 444 00:22:58,280 --> 00:23:01,240 Speaker 1: newspaper to be delivered to your door. It's like, there 445 00:23:01,240 --> 00:23:03,399 Speaker 1: could be things happening right now in other parts of 446 00:23:03,440 --> 00:23:06,680 Speaker 1: the Earth, but you know it'll be a long time 447 00:23:06,720 --> 00:23:08,760 Speaker 1: before you find out about them, or you know that 448 00:23:08,840 --> 00:23:10,960 Speaker 1: they actually happened at the same time that they happen. 449 00:23:11,080 --> 00:23:14,040 Speaker 1: That's right, and speeding up our communications has sort of 450 00:23:14,240 --> 00:23:18,160 Speaker 1: expanded our cone of understanding. Right, It's shrunk the time 451 00:23:18,200 --> 00:23:20,879 Speaker 1: it gets for information yet here, but not to zero. 452 00:23:21,000 --> 00:23:23,560 Speaker 1: Even with cell phones and speed of light electronics, you 453 00:23:23,560 --> 00:23:27,160 Speaker 1: still can't know exactly what's happening across the world right now. 454 00:23:27,240 --> 00:23:29,480 Speaker 1: There's still a time delay. And that's why it's cool 455 00:23:29,520 --> 00:23:31,240 Speaker 1: to see in some of these TV shows that they 456 00:23:31,240 --> 00:23:33,520 Speaker 1: really incorporate that. You know that if you're trying to 457 00:23:33,600 --> 00:23:36,680 Speaker 1: coordinate your army on Mars from your base on Earth, 458 00:23:36,960 --> 00:23:39,760 Speaker 1: it takes time for your messages to get there. If 459 00:23:39,760 --> 00:23:42,359 Speaker 1: there's a battle going on around you know, the atmosphere 460 00:23:42,359 --> 00:23:44,880 Speaker 1: of Jupiter that by the time you've heard about the beginning, 461 00:23:45,000 --> 00:23:47,679 Speaker 1: it's probably over already and there's nothing you can do 462 00:23:47,720 --> 00:23:49,919 Speaker 1: to change the outcome. I guess, like before when you 463 00:23:49,960 --> 00:23:51,359 Speaker 1: had a battle on you have to like send a 464 00:23:51,440 --> 00:23:54,840 Speaker 1: messenger or send a scout or something you had, there 465 00:23:54,880 --> 00:23:57,919 Speaker 1: was this just huge delay, and so now thinks they're faster, 466 00:23:58,160 --> 00:24:01,240 Speaker 1: but they're still limited, like there's still no simultaneity, Like 467 00:24:01,280 --> 00:24:04,320 Speaker 1: there's still no ability to know what is going on 468 00:24:04,640 --> 00:24:08,080 Speaker 1: right now somewhere else. Yeah, exactly. And the same concept 469 00:24:08,200 --> 00:24:10,840 Speaker 1: is light cone, which tells you, like what you can influence. 470 00:24:10,960 --> 00:24:12,879 Speaker 1: It also works in the other direction. You have like 471 00:24:12,920 --> 00:24:16,160 Speaker 1: a backwards light cone. If you think in the other direction, 472 00:24:16,240 --> 00:24:18,320 Speaker 1: like how close does somebody have to be to me 473 00:24:18,680 --> 00:24:21,320 Speaker 1: to shoot a death ray and hit me right now? 474 00:24:21,800 --> 00:24:24,280 Speaker 1: You know, if somebody is in Andromeda and they shoot 475 00:24:24,320 --> 00:24:26,760 Speaker 1: a death ray at you, you're safe for a few 476 00:24:26,800 --> 00:24:29,960 Speaker 1: million years, right Nobody in Andromeda can kill you right now. 477 00:24:30,280 --> 00:24:32,520 Speaker 1: Even if they shot their death ray a hundred thousand 478 00:24:32,640 --> 00:24:34,919 Speaker 1: years ago and it's been hurtling towards you for a 479 00:24:34,960 --> 00:24:37,320 Speaker 1: hundred thousand years, you're still safe. It's not going to 480 00:24:37,400 --> 00:24:39,480 Speaker 1: get here for a while. Because they are not in 481 00:24:39,560 --> 00:24:42,520 Speaker 1: your backwards light cone yet. But if they shot at 482 00:24:42,680 --> 00:24:44,879 Speaker 1: a million years ago, it would be hitting us right 483 00:24:44,880 --> 00:24:48,080 Speaker 1: now potentially. And if they shoot it right now, they 484 00:24:48,080 --> 00:24:49,720 Speaker 1: were still going to get hit, But it's going to 485 00:24:49,800 --> 00:24:51,959 Speaker 1: be a million years from now, that's right. If they 486 00:24:52,000 --> 00:24:54,119 Speaker 1: shoot it right now, it's not in our past light cone, 487 00:24:54,480 --> 00:24:57,440 Speaker 1: but our past light cone moves up this time access 488 00:24:57,440 --> 00:25:00,640 Speaker 1: and eventually they will be inside our ask light gone 489 00:25:00,720 --> 00:25:03,280 Speaker 1: and yes it will get here, right but you're safe 490 00:25:03,400 --> 00:25:06,200 Speaker 1: right now, right now, there is this past like cone 491 00:25:06,200 --> 00:25:08,639 Speaker 1: that dictates all the things that could be influencing what's 492 00:25:08,720 --> 00:25:12,440 Speaker 1: happening at your location, and somebody really far away, even 493 00:25:12,440 --> 00:25:16,160 Speaker 1: a foot away, can't influence what's happening to you right now. 494 00:25:16,320 --> 00:25:19,040 Speaker 1: They can only influence your future. Right well, they can't 495 00:25:19,119 --> 00:25:21,400 Speaker 1: influence you right now. But I mean doesn't mean you're 496 00:25:21,440 --> 00:25:23,840 Speaker 1: safe from a death ray, because they could have shot 497 00:25:23,840 --> 00:25:25,880 Speaker 1: it a while ago and you would still die from 498 00:25:25,920 --> 00:25:28,440 Speaker 1: the death ray arriving now, you're right, And the weirdest thing, 499 00:25:28,480 --> 00:25:30,800 Speaker 1: the worst thing about death rays is that they travel 500 00:25:30,840 --> 00:25:33,360 Speaker 1: at the fastest speed possible, so there's literally no way 501 00:25:33,400 --> 00:25:35,560 Speaker 1: to get any warning. Right the moment you see it 502 00:25:35,600 --> 00:25:37,720 Speaker 1: is the moment that arrives at the moment it impacts you. 503 00:25:38,000 --> 00:25:40,879 Speaker 1: But hopefully, you know, a million years ago, you know, 504 00:25:40,920 --> 00:25:43,520 Speaker 1: we were just cavemen and women, and you know we 505 00:25:43,520 --> 00:25:48,040 Speaker 1: didn't do anything to offendiate, hopefully, Or maybe it's a 506 00:25:48,119 --> 00:25:51,280 Speaker 1: natural process. Maybe the gamma rays from a supernova that 507 00:25:51,320 --> 00:25:54,480 Speaker 1: blew up, you know, a while ago, and those sterilizing 508 00:25:54,600 --> 00:25:57,520 Speaker 1: death rays are just now arriving here at Earth. Man, 509 00:25:57,560 --> 00:26:01,240 Speaker 1: this line makes me feel not at all safer. Daniel, 510 00:26:01,720 --> 00:26:04,000 Speaker 1: See how you can drop comfort from this light cone. 511 00:26:04,520 --> 00:26:08,160 Speaker 1: It's like a pretty flimsy protection against giant gamma ray bers. 512 00:26:08,280 --> 00:26:10,400 Speaker 1: It just means that somebody's got to plan ahead. If 513 00:26:10,400 --> 00:26:12,399 Speaker 1: they really want to fry us now, they're got to 514 00:26:12,480 --> 00:26:15,000 Speaker 1: either be close by or they have that planned ahead 515 00:26:16,720 --> 00:26:20,280 Speaker 1: so that athetic exploding start. Are you saying it's not 516 00:26:20,440 --> 00:26:22,560 Speaker 1: very good at planning so we're saved. Is that it's 517 00:26:22,560 --> 00:26:27,120 Speaker 1: a procrastinator saves us from procrastinators exactly? But what about 518 00:26:27,160 --> 00:26:31,880 Speaker 1: type A supernovas? Oh, the kind of plants ahead, there's 519 00:26:31,920 --> 00:26:35,239 Speaker 1: nothing we can do. Yeah, we're toast, all right. So 520 00:26:35,440 --> 00:26:38,560 Speaker 1: it sort of protects us, and I think it also 521 00:26:38,680 --> 00:26:42,800 Speaker 1: kind of affects what we might agree on. Is kind 522 00:26:42,840 --> 00:26:45,560 Speaker 1: of a consistent history of the universe. Right, Yeah, it's 523 00:26:45,640 --> 00:26:49,360 Speaker 1: really interesting. The whole universe can be divided into three regions. 524 00:26:49,400 --> 00:26:52,159 Speaker 1: You have your future like cone, your path like cone, 525 00:26:52,560 --> 00:26:55,080 Speaker 1: and then there's everything else. Right, and this is this 526 00:26:55,200 --> 00:26:58,800 Speaker 1: called this the absolute elsewhere. It sounds like an awesome 527 00:26:58,880 --> 00:27:01,200 Speaker 1: name for a Netflix show or something. So the absolute 528 00:27:01,240 --> 00:27:04,720 Speaker 1: elsewhere is the spot that you can't affect, you can't influence, right, 529 00:27:04,840 --> 00:27:07,159 Speaker 1: And that's really interesting because things that happened in the 530 00:27:07,200 --> 00:27:10,560 Speaker 1: absolute elsewhere, you might disagree with people about the order 531 00:27:10,640 --> 00:27:12,960 Speaker 1: in which they happen. Like you might look at a 532 00:27:13,000 --> 00:27:15,679 Speaker 1: series of events and say A happens before B, and 533 00:27:15,720 --> 00:27:17,359 Speaker 1: somebody else might look at it and say, no, no, no, 534 00:27:17,440 --> 00:27:20,560 Speaker 1: I think B happens before A. And you could both 535 00:27:20,560 --> 00:27:23,320 Speaker 1: be right. If these two things are not inside each 536 00:27:23,320 --> 00:27:26,919 Speaker 1: other's light cones, and these events don't have overlapping light cones, 537 00:27:27,320 --> 00:27:30,600 Speaker 1: then they can be differently ordered and not affect anything 538 00:27:30,640 --> 00:27:33,960 Speaker 1: from a causality point of view. WHOA, So I guess 539 00:27:34,040 --> 00:27:35,359 Speaker 1: I can have a light cone and you can have 540 00:27:35,400 --> 00:27:38,040 Speaker 1: a light cone. And if those two don't interact, is 541 00:27:38,040 --> 00:27:39,920 Speaker 1: that what you mean? Like if they don't touch, then 542 00:27:40,600 --> 00:27:43,520 Speaker 1: we were looking at literally like different universes. Well, they 543 00:27:43,560 --> 00:27:46,800 Speaker 1: will eventually touch, right, because their light cones will eventually impact, 544 00:27:47,000 --> 00:27:49,200 Speaker 1: and so there is some overlap in their light cone 545 00:27:49,320 --> 00:27:52,199 Speaker 1: far in the future where both of them can influence. 546 00:27:52,400 --> 00:27:55,760 Speaker 1: But it doesn't matter which one happened first. It doesn't 547 00:27:55,760 --> 00:27:58,200 Speaker 1: matter if A happened in then B, or B happened 548 00:27:58,200 --> 00:28:01,600 Speaker 1: and then A, because these two events are the events 549 00:28:01,680 --> 00:28:04,760 Speaker 1: themselves are not inside each other's light cones. Right, B 550 00:28:05,040 --> 00:28:06,840 Speaker 1: is not in a's light cone, and A is not 551 00:28:06,920 --> 00:28:09,000 Speaker 1: in b s light cone. Even though the two light 552 00:28:09,040 --> 00:28:12,000 Speaker 1: cones do overlap, if they are not inside each other's 553 00:28:12,080 --> 00:28:14,960 Speaker 1: light cones, then you can swap their order just by 554 00:28:15,040 --> 00:28:17,880 Speaker 1: changing your speed. If you decide to zip by them 555 00:28:18,080 --> 00:28:20,160 Speaker 1: in a spaceship as close to the speed of light, 556 00:28:20,440 --> 00:28:22,760 Speaker 1: you will see one happened before the other. If you 557 00:28:22,800 --> 00:28:25,000 Speaker 1: go in the other direction and nearly the speed of light, 558 00:28:25,320 --> 00:28:28,280 Speaker 1: you will see the opposite order of events. And it 559 00:28:28,320 --> 00:28:31,919 Speaker 1: all works out downstream. Because these two things aren't causally linked, 560 00:28:31,920 --> 00:28:34,840 Speaker 1: they're not inside each other's light cones, so you're free 561 00:28:34,880 --> 00:28:37,600 Speaker 1: to change their order of events. But then you know 562 00:28:37,640 --> 00:28:40,440 Speaker 1: the TV who are involved would have a different interpretation, right, 563 00:28:40,480 --> 00:28:42,880 Speaker 1: like one of them will see one thing happening before 564 00:28:42,880 --> 00:28:46,959 Speaker 1: the other. Yeah, exactly, But there is no absolute definition 565 00:28:47,000 --> 00:28:50,520 Speaker 1: of what happened. First, all the observers have their own interpretation, 566 00:28:50,640 --> 00:28:54,560 Speaker 1: and they're all correct because the answer depends on your position. 567 00:28:54,960 --> 00:28:57,760 Speaker 1: That's not true for two events where one is inside 568 00:28:57,800 --> 00:28:59,920 Speaker 1: the other one's light cone. If I shoot a joke 569 00:29:00,080 --> 00:29:02,960 Speaker 1: ray and I hit you in the head, then you laugh, right, 570 00:29:03,360 --> 00:29:06,640 Speaker 1: put it on joke mode, please, there's that. It's don 571 00:29:07,080 --> 00:29:10,320 Speaker 1: and then there's a joke open on banana mode. So 572 00:29:10,360 --> 00:29:12,720 Speaker 1: I hit the ray and the banana hits you in 573 00:29:12,760 --> 00:29:15,440 Speaker 1: the head. Right now, you are in my light cone. 574 00:29:15,440 --> 00:29:18,000 Speaker 1: Because the two events me pressing the button on the 575 00:29:18,040 --> 00:29:20,880 Speaker 1: gun and you having banana arrived in your mouth, they're 576 00:29:20,880 --> 00:29:23,520 Speaker 1: not at the same time. What happens before the other, 577 00:29:23,600 --> 00:29:26,320 Speaker 1: and there's a causal structure for them. I have to 578 00:29:26,320 --> 00:29:29,920 Speaker 1: press the button before the banana ray arrives at your head. 579 00:29:30,280 --> 00:29:33,000 Speaker 1: And that's okay, because the banana ray arriving at your 580 00:29:33,040 --> 00:29:35,640 Speaker 1: head is an event in my future. It's inside my 581 00:29:35,760 --> 00:29:38,320 Speaker 1: light cone. But for example, you and I both have 582 00:29:38,600 --> 00:29:41,320 Speaker 1: these guns and we point them in random directions or whatever, 583 00:29:41,440 --> 00:29:43,400 Speaker 1: and we try to fire them at the same time. 584 00:29:43,520 --> 00:29:45,480 Speaker 1: Some people might say we fired them at the same time. 585 00:29:45,520 --> 00:29:49,040 Speaker 1: Other people flying behind the spaceship might disagree about who 586 00:29:49,200 --> 00:29:53,120 Speaker 1: pressed their trigger first because they would be moving and 587 00:29:53,280 --> 00:29:56,840 Speaker 1: because of the way that light along the light takes 588 00:29:56,880 --> 00:29:59,480 Speaker 1: to get to them and the speed limit of the universe, 589 00:30:00,000 --> 00:30:02,640 Speaker 1: they might reconstruct the events in a different way. Yeah, 590 00:30:02,640 --> 00:30:05,200 Speaker 1: but it's not just because how long light takes to 591 00:30:05,240 --> 00:30:07,920 Speaker 1: get to them. Even if you factor that in, right, 592 00:30:07,960 --> 00:30:09,800 Speaker 1: even if you account for how long it takes the 593 00:30:09,920 --> 00:30:13,040 Speaker 1: signals and the images to appear, there's still a difference 594 00:30:13,080 --> 00:30:15,400 Speaker 1: in the order of events. And that's because time flows 595 00:30:15,440 --> 00:30:18,160 Speaker 1: differently based on where you are and how fast you 596 00:30:18,200 --> 00:30:22,120 Speaker 1: are going. So your speed affects how you see time flowing, 597 00:30:22,640 --> 00:30:24,959 Speaker 1: and so you can see one event happening before the other. 598 00:30:25,000 --> 00:30:27,520 Speaker 1: You can see Jorge presses button first, or somebody else 599 00:30:27,560 --> 00:30:29,520 Speaker 1: going in the other direction can see Daniel press the 600 00:30:29,600 --> 00:30:32,400 Speaker 1: button first, even if they account for the transmission delay 601 00:30:32,520 --> 00:30:35,600 Speaker 1: from light. But they would be wrong. I guess what 602 00:30:35,600 --> 00:30:38,160 Speaker 1: I mean is they would have their own interpretation, but 603 00:30:38,240 --> 00:30:41,200 Speaker 1: other people would have their different interpretation. Yeah, but nobody's 604 00:30:41,280 --> 00:30:44,360 Speaker 1: right or everybody's right. You know, if these two events 605 00:30:44,520 --> 00:30:46,760 Speaker 1: are not inside each other's light, cones right, their light 606 00:30:46,760 --> 00:30:48,880 Speaker 1: cones can overlap in the future, but the two events 607 00:30:48,920 --> 00:30:51,840 Speaker 1: themselves are not inside each other's light cones, then their 608 00:30:51,960 --> 00:30:55,160 Speaker 1: order is not well defined. And this is all because 609 00:30:55,240 --> 00:30:57,480 Speaker 1: the universe has a speed limit, right, Like, if it 610 00:30:57,520 --> 00:30:59,640 Speaker 1: didn't have a speed limit, then you could talk about 611 00:30:59,760 --> 00:31:03,320 Speaker 1: like absolute history of the universe. That's right exactly, And 612 00:31:03,360 --> 00:31:07,040 Speaker 1: that speed limit defines the size of this cone. Right. Imagine, 613 00:31:07,080 --> 00:31:09,840 Speaker 1: for example, if the speed of light was much much slower, 614 00:31:10,240 --> 00:31:13,200 Speaker 1: then your light cone would be narrower. The part of 615 00:31:13,240 --> 00:31:15,880 Speaker 1: the universe, the part of the future that you could influence, 616 00:31:15,920 --> 00:31:17,920 Speaker 1: would be a much smaller part of the universe. If 617 00:31:17,960 --> 00:31:20,360 Speaker 1: you shot death rays in every direction and the speed 618 00:31:20,360 --> 00:31:22,760 Speaker 1: of light was much smaller, then you would kill a 619 00:31:22,800 --> 00:31:25,360 Speaker 1: smaller fraction of the universe. Or if you shot joke raise, 620 00:31:25,560 --> 00:31:27,720 Speaker 1: you would make a smaller fraction in the universe laugh. 621 00:31:28,200 --> 00:31:30,600 Speaker 1: Then if the speed of light was ten times faster 622 00:31:30,760 --> 00:31:33,560 Speaker 1: than it is, then you could influence more of the universe, 623 00:31:33,600 --> 00:31:36,200 Speaker 1: and aliens out there with their joke raise could make 624 00:31:36,280 --> 00:31:39,640 Speaker 1: us laugh more effectively. So this number the speed of 625 00:31:39,720 --> 00:31:43,240 Speaker 1: light really changes the whole structure of causality of space. Right, 626 00:31:43,280 --> 00:31:45,239 Speaker 1: But what if you make like a light joke like 627 00:31:45,280 --> 00:31:48,240 Speaker 1: this vanilla is the best. Ha ha ha. That's a joke, 628 00:31:48,360 --> 00:31:51,400 Speaker 1: like a light vanilla joke. Yeah, that wouldn't harm anyone, 629 00:31:51,480 --> 00:31:54,080 Speaker 1: and people would just let it go by. But it 630 00:31:54,200 --> 00:31:56,040 Speaker 1: really is sort of like a cone. I'm thinking, like 631 00:31:56,080 --> 00:31:58,120 Speaker 1: a doc cone. You know those cones they put on 632 00:31:58,280 --> 00:32:01,800 Speaker 1: dogs so that data and harm themselves or just to 633 00:32:01,840 --> 00:32:04,520 Speaker 1: protect them. It really is like a cone that you 634 00:32:04,560 --> 00:32:06,480 Speaker 1: put on our we put on our heads that kind 635 00:32:06,480 --> 00:32:08,880 Speaker 1: of limits what we can see and what we can 636 00:32:08,920 --> 00:32:12,080 Speaker 1: interact with, right it sort of does. Now imagining you 637 00:32:12,160 --> 00:32:13,520 Speaker 1: with one of these on your head trying to eat 638 00:32:13,560 --> 00:32:17,640 Speaker 1: a banana, even though you can't, Daniel shoot me with 639 00:32:17,680 --> 00:32:20,200 Speaker 1: the bananas exactly, then you need me to shoot you 640 00:32:20,240 --> 00:32:22,640 Speaker 1: with the banana ray or I guess she went up 641 00:32:22,680 --> 00:32:25,080 Speaker 1: in the air and then catch it and the cone 642 00:32:25,080 --> 00:32:27,560 Speaker 1: would help me catch this. There you go, there you 643 00:32:27,600 --> 00:32:30,040 Speaker 1: go pretty soon be surrounded with bananas. I'd have a 644 00:32:30,080 --> 00:32:32,320 Speaker 1: ConA around my head filmed with bananas and I'll go 645 00:32:32,400 --> 00:32:36,120 Speaker 1: along with a scoop of vanilla on top, and then 646 00:32:36,120 --> 00:32:38,440 Speaker 1: for some childhood. But the amazing thing to me is 647 00:32:38,480 --> 00:32:40,800 Speaker 1: that we still don't know why the speed of light 648 00:32:40,960 --> 00:32:43,320 Speaker 1: is this number. You know, it has such a dramatic 649 00:32:43,320 --> 00:32:45,360 Speaker 1: effect on what part of the universe we can see 650 00:32:45,520 --> 00:32:48,040 Speaker 1: and what part of the universe we can influence, and 651 00:32:48,080 --> 00:32:50,640 Speaker 1: how the universe is sort of like tied together, you know, 652 00:32:50,680 --> 00:32:53,959 Speaker 1: what affects what It really changes everything. And it's just 653 00:32:54,080 --> 00:32:56,320 Speaker 1: like a number. We measure it. We don't know why 654 00:32:56,360 --> 00:32:57,880 Speaker 1: it is what it is. It could have been better, 655 00:32:58,200 --> 00:33:00,360 Speaker 1: it could have been smaller, for all we know. Our 656 00:33:00,440 --> 00:33:02,480 Speaker 1: laws of physics just have like an empty spot there. 657 00:33:02,480 --> 00:33:04,800 Speaker 1: If you're like right in the number you measure, there's 658 00:33:04,840 --> 00:33:07,040 Speaker 1: no reason it has to be this or that that 659 00:33:07,120 --> 00:33:09,400 Speaker 1: we know of. And that's like a real mystery, you 660 00:33:09,440 --> 00:33:11,000 Speaker 1: know, it it makes you wonder why it's this and not 661 00:33:11,120 --> 00:33:14,800 Speaker 1: something else. Alright, cool, Well, let's get into now what 662 00:33:14,960 --> 00:33:17,720 Speaker 1: consequences is this light cone has in our in the 663 00:33:17,840 --> 00:33:21,960 Speaker 1: universe and possibly in our ability to travel through time. 664 00:33:22,480 --> 00:33:37,480 Speaker 1: But first let's take another quick break. Are we're talking 665 00:33:37,480 --> 00:33:40,960 Speaker 1: about light counts and the speed of light and whether 666 00:33:41,160 --> 00:33:43,680 Speaker 1: or not we can affect things in the universe that 667 00:33:43,720 --> 00:33:47,239 Speaker 1: are happening right now, which is basically no, right, Like, 668 00:33:47,360 --> 00:33:50,800 Speaker 1: we can't affect anything else in the universe happening at 669 00:33:50,800 --> 00:33:53,920 Speaker 1: this moment, that's right, nothing except for what's happening right here, 670 00:33:54,040 --> 00:33:57,200 Speaker 1: right now, or stuff that's happening in the future. But 671 00:33:57,280 --> 00:34:00,200 Speaker 1: at this very moment, you can't affect anything except for 672 00:34:00,560 --> 00:34:03,680 Speaker 1: exactly the spot where you are. Well, technically nothing right 673 00:34:03,760 --> 00:34:06,160 Speaker 1: because even things that are one millimeter away from my 674 00:34:06,200 --> 00:34:09,520 Speaker 1: eye in the present moment, I can't even see or effect. 675 00:34:09,640 --> 00:34:11,960 Speaker 1: That's true. We have to go down to zero millimeters. 676 00:34:12,000 --> 00:34:14,000 Speaker 1: And that's only even only if you believe in free 677 00:34:14,000 --> 00:34:17,520 Speaker 1: will and if your brain operates instantaneously, So technically you're right. 678 00:34:17,600 --> 00:34:20,720 Speaker 1: Any decision you make right now can only influence the future, 679 00:34:21,000 --> 00:34:24,120 Speaker 1: except that maybe there's a possibility to use this concept 680 00:34:24,200 --> 00:34:27,359 Speaker 1: to do time travel. Daniel so explained that to me. Yes, 681 00:34:27,440 --> 00:34:29,680 Speaker 1: so what we talked about so far, this idea of 682 00:34:29,760 --> 00:34:32,360 Speaker 1: light cones these circles of light expanding out into the 683 00:34:32,440 --> 00:34:34,560 Speaker 1: universe and into your future. This is the way we 684 00:34:34,640 --> 00:34:37,600 Speaker 1: think about space. If it's not curved, so we call 685 00:34:37,719 --> 00:34:40,319 Speaker 1: space flat, if it's just sort of like has no 686 00:34:40,480 --> 00:34:43,360 Speaker 1: shape to it, if there's no bending of it that 687 00:34:43,400 --> 00:34:46,640 Speaker 1: affects like the path of photons. And we know that 688 00:34:46,760 --> 00:34:49,960 Speaker 1: space can be bent. We know that, for example, everything 689 00:34:50,000 --> 00:34:53,840 Speaker 1: with mass and energy bend space, like the Sun bend space. 690 00:34:54,160 --> 00:34:56,680 Speaker 1: That's why the Earth is moving around it instead of 691 00:34:56,719 --> 00:34:59,720 Speaker 1: just flying off into deep space. We know the Eube 692 00:34:59,840 --> 00:35:01,880 Speaker 1: and in the space because you have mass, and so 693 00:35:02,000 --> 00:35:05,879 Speaker 1: everything out there changes the shape of space, which means 694 00:35:05,920 --> 00:35:09,759 Speaker 1: it changes how light goes through it. Remember that gravity 695 00:35:09,840 --> 00:35:12,280 Speaker 1: is not just like a force that tugs on things, 696 00:35:12,760 --> 00:35:16,319 Speaker 1: because light, for example, has no mass, but gravity can 697 00:35:16,440 --> 00:35:20,120 Speaker 1: affect its path because gravity changes the very shape of 698 00:35:20,120 --> 00:35:23,279 Speaker 1: space and light travels through that space. And so we 699 00:35:23,360 --> 00:35:26,320 Speaker 1: know that things are more complicated when space gets curved. 700 00:35:26,400 --> 00:35:28,160 Speaker 1: So what we talked about so far is only in 701 00:35:28,200 --> 00:35:31,080 Speaker 1: the event that the universe is empty and there's no curvature, 702 00:35:31,280 --> 00:35:33,239 Speaker 1: there's no mass or anything to change the shape. So 703 00:35:33,239 --> 00:35:35,480 Speaker 1: in flat space, when there's a lot of mass around, 704 00:35:35,560 --> 00:35:38,640 Speaker 1: things get curved and things get pretty different and weird. 705 00:35:38,880 --> 00:35:41,680 Speaker 1: These light cones, which you can imagine sort of like 706 00:35:41,760 --> 00:35:45,399 Speaker 1: going up and going down now, start to get tilted. Right. 707 00:35:45,480 --> 00:35:47,879 Speaker 1: Is this something we can actually see? Right? You can 708 00:35:47,880 --> 00:35:51,919 Speaker 1: see light getting bent out there in space by heavy objects. Yeah, 709 00:35:52,000 --> 00:35:55,320 Speaker 1: it's called gravitational lensing. If there's like a really big 710 00:35:55,360 --> 00:35:58,319 Speaker 1: heavy object between us and some source of light, like 711 00:35:58,360 --> 00:36:02,080 Speaker 1: a background galaxy, then as those photons come towards Earth, 712 00:36:02,080 --> 00:36:05,080 Speaker 1: they could bent around that massive object. And this is 713 00:36:05,120 --> 00:36:07,360 Speaker 1: one way we can detect, for example, the existence of 714 00:36:07,440 --> 00:36:09,680 Speaker 1: dark matter and try to figure out, like roughly where 715 00:36:09,680 --> 00:36:12,279 Speaker 1: it is based on how it distorts the light that's 716 00:36:12,280 --> 00:36:15,000 Speaker 1: passing near it or through it. So it's definitely a 717 00:36:15,080 --> 00:36:18,520 Speaker 1: real thing that's happening. It's something we've observed. We're sure 718 00:36:18,520 --> 00:36:21,439 Speaker 1: it is true. So if a space can bend light, 719 00:36:21,760 --> 00:36:24,879 Speaker 1: or land space can sort of affect the trajectory of light, 720 00:36:24,960 --> 00:36:27,120 Speaker 1: that would make sense that it would bend these light 721 00:36:27,120 --> 00:36:30,040 Speaker 1: cones that we have to kind of figure out what 722 00:36:30,160 --> 00:36:32,480 Speaker 1: we can see and cannot see in the universe exactly. 723 00:36:32,520 --> 00:36:34,640 Speaker 1: Because the shape of the light cone is defined by 724 00:36:34,719 --> 00:36:38,680 Speaker 1: where light goes right where light can reach, and so 725 00:36:38,880 --> 00:36:41,600 Speaker 1: space is bent in a way that light can't get somewhere, 726 00:36:41,920 --> 00:36:44,160 Speaker 1: then the light cones are also bent. So this idea 727 00:36:44,200 --> 00:36:46,840 Speaker 1: of them being like simple cones is only in flat 728 00:36:46,840 --> 00:36:51,719 Speaker 1: space near something really massive, they bend towards the mass, right, 729 00:36:51,760 --> 00:36:55,560 Speaker 1: because light moves towards mass. Right. If you have, for example, 730 00:36:55,640 --> 00:36:57,879 Speaker 1: the Sun, and you shoot a photon near the Sun, 731 00:36:58,000 --> 00:37:00,360 Speaker 1: it will get curved sort of in the dire action 732 00:37:00,520 --> 00:37:02,960 Speaker 1: of the Sun. And if you have a black hole, 733 00:37:03,160 --> 00:37:05,920 Speaker 1: then it's going to get curved room towards the black hole. 734 00:37:06,239 --> 00:37:08,600 Speaker 1: So as you get closer and closer something massive, these 735 00:37:08,680 --> 00:37:12,040 Speaker 1: light cones tilt more and more. Well, they start to 736 00:37:12,040 --> 00:37:14,839 Speaker 1: look like maybe horns and not so much cones or yeah, 737 00:37:14,960 --> 00:37:17,400 Speaker 1: or like bow ties or something yeah, or like a bugle, 738 00:37:17,560 --> 00:37:22,879 Speaker 1: remember that snack, the little like cones, curved cones. Yeah, exactly, Yeah, 739 00:37:23,000 --> 00:37:26,919 Speaker 1: light bugles. Will call it light bugles exactly. And so 740 00:37:27,200 --> 00:37:29,719 Speaker 1: inside a black hole, of course, you can think about 741 00:37:29,760 --> 00:37:31,920 Speaker 1: what happens to a photon. While a photon inside a 742 00:37:31,920 --> 00:37:35,440 Speaker 1: black hole always goes towards the center, not because gravity 743 00:37:35,480 --> 00:37:37,920 Speaker 1: is so strong, but because the shape of space requires it, 744 00:37:37,920 --> 00:37:41,440 Speaker 1: because there's only one direction inside a black hole. So 745 00:37:41,520 --> 00:37:44,960 Speaker 1: inside a black hole, these things have tilted totally sideways. 746 00:37:45,280 --> 00:37:48,279 Speaker 1: You shoot a photon and it goes just towards the singularity. 747 00:37:48,400 --> 00:37:51,160 Speaker 1: All the light cones are now tilted towards the center. 748 00:37:51,440 --> 00:37:53,960 Speaker 1: You hear people say sometimes this thing that inside a 749 00:37:53,960 --> 00:37:57,759 Speaker 1: black hole, space and time switch roles. Right, This is 750 00:37:57,800 --> 00:38:01,400 Speaker 1: like a geometric way to understand that, because now instead 751 00:38:01,440 --> 00:38:05,040 Speaker 1: of time flowing up, it's sort of flowing sideways. Right, 752 00:38:05,040 --> 00:38:09,880 Speaker 1: Because the light cone has tilted over by forty five degrees. Well, 753 00:38:10,480 --> 00:38:15,000 Speaker 1: I guess I don't understand it at all. So the 754 00:38:15,120 --> 00:38:19,120 Speaker 1: light cone tilts, and somehow time and space which positions? 755 00:38:19,160 --> 00:38:21,600 Speaker 1: Is that what you just said? Yeah, because your future, 756 00:38:21,680 --> 00:38:25,920 Speaker 1: all possible futures are the singularity, and so the only 757 00:38:25,960 --> 00:38:28,000 Speaker 1: way to move forward in time is to move in 758 00:38:28,040 --> 00:38:30,960 Speaker 1: this one direction of space. And so sort of like 759 00:38:31,320 --> 00:38:35,000 Speaker 1: moving through space towards the singularity is the same thing 760 00:38:35,200 --> 00:38:39,120 Speaker 1: as moving forwards in time. And you can graph that 761 00:38:39,239 --> 00:38:41,839 Speaker 1: geometrically by thinking about the light zone being tilted over 762 00:38:42,360 --> 00:38:45,239 Speaker 1: from being vertical to being horizontal. It's like there's only 763 00:38:45,840 --> 00:38:49,000 Speaker 1: space and time become one way and everything goes in 764 00:38:49,040 --> 00:38:51,640 Speaker 1: the same direction. Yeah, exactly, all right, And so then 765 00:38:51,680 --> 00:38:53,600 Speaker 1: how does that relate to time travel? You said it 766 00:38:53,680 --> 00:38:56,080 Speaker 1: might be possible to do time travel. It might be 767 00:38:56,120 --> 00:38:59,440 Speaker 1: possible to do time travel if you use these cones 768 00:38:59,760 --> 00:39:03,279 Speaker 1: you and construct this really weird structure. Right, So we 769 00:39:03,360 --> 00:39:07,319 Speaker 1: talked about how near something really heavy, these cones can 770 00:39:07,320 --> 00:39:10,319 Speaker 1: tilt like up to forty five degrees right towards the 771 00:39:10,320 --> 00:39:12,719 Speaker 1: center of a black hole. Now, imagine if you could 772 00:39:12,719 --> 00:39:15,840 Speaker 1: have a cone that tilted more than forty five degrees, 773 00:39:16,120 --> 00:39:18,359 Speaker 1: And what that means is that you're tilting so that 774 00:39:18,760 --> 00:39:22,759 Speaker 1: part of the light cone is now in the past, right, 775 00:39:22,800 --> 00:39:25,319 Speaker 1: So it's possible if you could do this, it would 776 00:39:25,360 --> 00:39:28,600 Speaker 1: mean that these particles are moving not just into the future, 777 00:39:28,640 --> 00:39:31,640 Speaker 1: but like the future is now dipping into the past. 778 00:39:32,080 --> 00:39:35,080 Speaker 1: What you mean you you bend the light cone so 779 00:39:35,160 --> 00:39:38,440 Speaker 1: much it wraps around and touches kind of the past 780 00:39:38,520 --> 00:39:41,960 Speaker 1: light cone, m exactly, and you think, is this possible? 781 00:39:42,080 --> 00:39:45,799 Speaker 1: Doesn't that contradict itself? Will remember that, like the definition 782 00:39:45,840 --> 00:39:48,960 Speaker 1: of time and the definition of space depends a little 783 00:39:49,000 --> 00:39:52,160 Speaker 1: bit on how fast you're going and the environment you're in, 784 00:39:52,520 --> 00:39:55,640 Speaker 1: and that gets even more complicated when space is bent. 785 00:39:56,200 --> 00:39:58,120 Speaker 1: And so what you can have is like a particle 786 00:39:58,560 --> 00:40:02,680 Speaker 1: moving forward into it's future like it's local time still 787 00:40:02,680 --> 00:40:05,200 Speaker 1: says I'm moving forward in the future one second, then 788 00:40:05,239 --> 00:40:07,000 Speaker 1: the next second, and the next second. But it could 789 00:40:07,000 --> 00:40:09,319 Speaker 1: be moving into the past from the point of view 790 00:40:09,360 --> 00:40:12,799 Speaker 1: of another observer. So like from a distant observer who's 791 00:40:12,840 --> 00:40:16,000 Speaker 1: watching this from far away, whose space isn't curved, they 792 00:40:16,000 --> 00:40:18,839 Speaker 1: could see that particle moving into like their past, even 793 00:40:18,840 --> 00:40:22,879 Speaker 1: though if it's still moving into its own future. Whoa wait, 794 00:40:22,920 --> 00:40:25,880 Speaker 1: are you saying that space and time actually curve around itself, 795 00:40:26,120 --> 00:40:28,920 Speaker 1: or it only looks curved around to a different observer, 796 00:40:29,360 --> 00:40:32,959 Speaker 1: the structure of it is actually occurred, and people think 797 00:40:33,040 --> 00:40:36,920 Speaker 1: in some weird configurations, if there's a very special arrangement 798 00:40:36,960 --> 00:40:40,360 Speaker 1: of mass, then you might be able to construct a 799 00:40:40,520 --> 00:40:45,160 Speaker 1: structure of space that allows particles to have their local future, 800 00:40:45,200 --> 00:40:49,000 Speaker 1: their personal timeline extend into like the past from the 801 00:40:49,040 --> 00:40:51,800 Speaker 1: point of view of other observers. From the point of 802 00:40:51,840 --> 00:40:54,640 Speaker 1: view of other observers, but the particle itsels wouldn't be 803 00:40:54,680 --> 00:40:57,840 Speaker 1: traveling into the past, or like me, I wouldn't be 804 00:40:57,880 --> 00:41:01,120 Speaker 1: traveling into the past. Well, it's like into their own future. 805 00:41:01,160 --> 00:41:02,680 Speaker 1: But that's sort of like what happens on a time 806 00:41:02,719 --> 00:41:05,160 Speaker 1: travel show. Right, If you are on a time travel 807 00:41:05,200 --> 00:41:07,200 Speaker 1: show and you want to go into the past, you're 808 00:41:07,239 --> 00:41:10,359 Speaker 1: still living your life forward on your timeline. Right, you 809 00:41:10,360 --> 00:41:13,400 Speaker 1: were forty six years old and seven days and two minutes, 810 00:41:13,760 --> 00:41:15,560 Speaker 1: And then when you go into the past, you're not 811 00:41:15,640 --> 00:41:18,800 Speaker 1: like younger again, right, You're just like keep going forward. 812 00:41:18,840 --> 00:41:21,280 Speaker 1: Now you're forty seven years, two days and five minutes 813 00:41:21,320 --> 00:41:23,600 Speaker 1: and seven minutes and ten minutes. So what you want 814 00:41:23,680 --> 00:41:26,200 Speaker 1: is your own timeline to continue, but you want the 815 00:41:26,239 --> 00:41:29,400 Speaker 1: structure of space around you to change that your timeline, 816 00:41:29,760 --> 00:41:32,239 Speaker 1: your future now goes into like the rest of the 817 00:41:32,320 --> 00:41:35,719 Speaker 1: universe's past. So this is called in physics, it's called 818 00:41:35,719 --> 00:41:38,920 Speaker 1: a closed time like curve because if you can tilt 819 00:41:38,960 --> 00:41:41,480 Speaker 1: a bunch of these cones just the right way, then 820 00:41:41,520 --> 00:41:44,360 Speaker 1: you can make this path that loops on around itself 821 00:41:44,560 --> 00:41:47,480 Speaker 1: and comes back to the same point where it originated. 822 00:41:47,840 --> 00:41:50,040 Speaker 1: So it's like shooting a light beam and having it 823 00:41:50,160 --> 00:41:51,759 Speaker 1: hit you in the back of the head, almost like 824 00:41:51,760 --> 00:41:55,359 Speaker 1: a wormhole kind of in time, almost like a wormhole. Yeah, 825 00:41:55,440 --> 00:41:57,400 Speaker 1: it's not actually a wormhole, because a wormhole is like 826 00:41:57,440 --> 00:42:00,480 Speaker 1: a shortcut between two distant locations. This is like a 827 00:42:00,520 --> 00:42:03,960 Speaker 1: structure in space. It's like a loop in space time. Right. 828 00:42:04,160 --> 00:42:07,719 Speaker 1: It is a complicated reconnection and rearrangement of how space works. 829 00:42:07,760 --> 00:42:10,440 Speaker 1: But it's technically a little bit different from a wormhole. Right, 830 00:42:10,719 --> 00:42:13,000 Speaker 1: wouldn't you be stuck in this loop like you'd be 831 00:42:13,000 --> 00:42:15,880 Speaker 1: be like groundhogs day? For this particle, it's just reliving, 832 00:42:16,400 --> 00:42:18,839 Speaker 1: going around and around and around. It thinks it's going 833 00:42:18,880 --> 00:42:21,359 Speaker 1: in the future, but really it's like revisiting the same 834 00:42:21,360 --> 00:42:23,680 Speaker 1: time over and over and over. Exactly. It's a structure 835 00:42:23,719 --> 00:42:26,799 Speaker 1: that reinforces itself, and it's only stable if it does 836 00:42:26,920 --> 00:42:29,839 Speaker 1: revisit itself. And so you're right. You wouldn't like get 837 00:42:29,880 --> 00:42:31,600 Speaker 1: to go back and choose a different flavor of ice 838 00:42:31,600 --> 00:42:34,600 Speaker 1: cream or set your death ray to banana instead of 839 00:42:34,640 --> 00:42:37,040 Speaker 1: death right. You have to make the same choices over 840 00:42:37,080 --> 00:42:39,560 Speaker 1: and over again. It's like this self supporting structure in 841 00:42:39,600 --> 00:42:43,080 Speaker 1: space and time so not recommended. Well, unless you want 842 00:42:43,080 --> 00:42:45,759 Speaker 1: to keep watching the same shows maybe, or if you 843 00:42:45,840 --> 00:42:48,800 Speaker 1: really like vanilla and you want to eat only vanilla 844 00:42:49,160 --> 00:42:52,640 Speaker 1: flavor for the rest of your lives for eternity. Yeah, exactly. 845 00:42:52,680 --> 00:42:56,240 Speaker 1: And this is something which is theoretically conceivable, like people 846 00:42:56,239 --> 00:42:58,920 Speaker 1: have worked this out on paper and it seems like 847 00:42:58,960 --> 00:43:02,640 Speaker 1: it might work. But again, general relativity doesn't tell us 848 00:43:02,719 --> 00:43:06,440 Speaker 1: like how to bend space to make this happen. People like, 849 00:43:06,560 --> 00:43:09,239 Speaker 1: if you could bend space in this particular way, then 850 00:43:09,280 --> 00:43:12,400 Speaker 1: we think this could happen. That doesn't mean necessarily we 851 00:43:12,520 --> 00:43:15,360 Speaker 1: know how to make space bend in that particular way. 852 00:43:15,719 --> 00:43:19,280 Speaker 1: You know, people have ideas, they have this crazy structure 853 00:43:19,640 --> 00:43:23,440 Speaker 1: that's like an infinite spinning cylinder of dust, and they 854 00:43:23,480 --> 00:43:26,080 Speaker 1: do the calculations and they think maybe that would allow 855 00:43:26,239 --> 00:43:29,239 Speaker 1: for these closed timelike curves to happen, but other people 856 00:43:29,280 --> 00:43:31,960 Speaker 1: think it's impossible, there's no way it could work, and 857 00:43:31,960 --> 00:43:33,640 Speaker 1: that we have to sort of throw up our hands 858 00:43:33,680 --> 00:43:35,719 Speaker 1: and say, let's figure it out when we get the 859 00:43:35,800 --> 00:43:38,960 Speaker 1: unified theory of everything. Well, you're saying that it's according 860 00:43:39,000 --> 00:43:42,840 Speaker 1: to the equations, it's possible, or like you know, anything 861 00:43:42,840 --> 00:43:45,720 Speaker 1: that can bend, if you bend it enough, this will happen, 862 00:43:45,840 --> 00:43:47,920 Speaker 1: But we don't know if it's physically possible to do it. 863 00:43:48,080 --> 00:43:50,720 Speaker 1: We don't know if it's physically possible. If you believe 864 00:43:50,800 --> 00:43:54,480 Speaker 1: general relativity is absolutely true and you can construct an 865 00:43:54,480 --> 00:43:57,600 Speaker 1: infinite spinning cylinder of dust, then you should believe this 866 00:43:57,640 --> 00:44:01,520 Speaker 1: is physically possible and can actually happen. Personally, I don't 867 00:44:01,560 --> 00:44:04,319 Speaker 1: think general relativity is a true theory of nature because 868 00:44:04,320 --> 00:44:07,280 Speaker 1: it ignores quantum mechanics, and so it can't be correct, 869 00:44:07,360 --> 00:44:09,759 Speaker 1: and we need some updated version. And it might be 870 00:44:09,840 --> 00:44:12,520 Speaker 1: that in that updated version and incorporates quantum mechanics, this 871 00:44:12,600 --> 00:44:15,239 Speaker 1: doesn't work anymore. So this could be like sort of 872 00:44:15,239 --> 00:44:17,440 Speaker 1: like a singularity of a black hole, like a sign 873 00:44:17,520 --> 00:44:19,799 Speaker 1: that the theory is wrong because it predicts this sort 874 00:44:19,800 --> 00:44:22,600 Speaker 1: of nonsense result. Right, Because I guess if it's a 875 00:44:22,640 --> 00:44:25,600 Speaker 1: closed loop. How would you even get into that loop? Right? Yeah, 876 00:44:25,800 --> 00:44:27,880 Speaker 1: you have to have somebody else build that infinite spinning 877 00:44:27,920 --> 00:44:31,160 Speaker 1: cylinder for you in the infinite past, because you'll always 878 00:44:31,160 --> 00:44:33,680 Speaker 1: be in that loop. So it might exist and there 879 00:44:33,760 --> 00:44:36,560 Speaker 1: might be a particle stuck in it or from the 880 00:44:36,600 --> 00:44:38,879 Speaker 1: beginning of time, but you wouldn't be able to get 881 00:44:38,880 --> 00:44:40,840 Speaker 1: in or out of it. That's right. If it exists, 882 00:44:40,880 --> 00:44:43,600 Speaker 1: it would be stuck forever. But you know, now we're 883 00:44:43,600 --> 00:44:46,759 Speaker 1: talking about like construction of a time loop, so we're 884 00:44:46,800 --> 00:44:49,240 Speaker 1: talking about the variation of the loop as a function 885 00:44:49,280 --> 00:44:52,080 Speaker 1: of time. So it's like an extra level of meta 886 00:44:52,160 --> 00:44:54,319 Speaker 1: time there, which gets tricky. You can just use the 887 00:44:54,360 --> 00:44:58,040 Speaker 1: same vanilla equations, you get to go extra spicy or 888 00:44:58,640 --> 00:45:03,319 Speaker 1: sprinkle some bugles on for some extra crunching iss. All right, 889 00:45:03,440 --> 00:45:04,759 Speaker 1: So that's the light on one, I guess, and I 890 00:45:04,840 --> 00:45:07,240 Speaker 1: guess you're saying it's one way that that it helps 891 00:45:07,280 --> 00:45:10,600 Speaker 1: you think about all these weird situations of space and 892 00:45:10,760 --> 00:45:15,600 Speaker 1: black holes and bending time and spacetime looping around itself. 893 00:45:15,600 --> 00:45:18,799 Speaker 1: You use that in in your everyday you know, theoretical 894 00:45:18,880 --> 00:45:21,680 Speaker 1: musings I do, and also when people write to me 895 00:45:21,719 --> 00:45:23,960 Speaker 1: and they ask me some like crazy question about special 896 00:45:24,000 --> 00:45:28,120 Speaker 1: relativity involving you know, spaceships and snowballs whatever. I usually 897 00:45:28,239 --> 00:45:30,799 Speaker 1: end up drawing light cones so I can understand, like, well, 898 00:45:31,200 --> 00:45:33,880 Speaker 1: this happened there, What will this person see or is 899 00:45:33,920 --> 00:45:36,160 Speaker 1: it possible for them to know this. It's just a 900 00:45:36,239 --> 00:45:38,440 Speaker 1: nice way to sort of like separate things because in 901 00:45:38,440 --> 00:45:41,719 Speaker 1: physics problems because much simpler when you can separate and 902 00:45:41,719 --> 00:45:43,840 Speaker 1: say these things are independent from those things, so I 903 00:45:43,840 --> 00:45:45,600 Speaker 1: can just deal with it on its own. They're not 904 00:45:45,640 --> 00:45:48,000 Speaker 1: like entangled. So a light cone shows you how to 905 00:45:48,000 --> 00:45:51,760 Speaker 1: like disentangle all the causal threads of the universe into 906 00:45:51,760 --> 00:45:54,520 Speaker 1: a bunch of different packets. Right, Yeah, everything is better 907 00:45:54,520 --> 00:45:58,840 Speaker 1: with the snow cone. That's our next episode. What is 908 00:45:58,880 --> 00:46:03,480 Speaker 1: a physics snow cone? It's a commort physic You say 909 00:46:03,640 --> 00:46:07,839 Speaker 1: no all the time, it's no, can I travel back 910 00:46:07,880 --> 00:46:12,440 Speaker 1: in times? No? Cyes c Yes? All right, Well, hopefully 911 00:46:12,480 --> 00:46:14,840 Speaker 1: it helps all of you out there and think about 912 00:46:15,360 --> 00:46:18,960 Speaker 1: cantality and what we can and cannot affect about the 913 00:46:19,000 --> 00:46:22,279 Speaker 1: present and maybe makes you appreciate a little bit more 914 00:46:22,520 --> 00:46:25,319 Speaker 1: where you are and what we're able to see of 915 00:46:25,440 --> 00:46:29,560 Speaker 1: this big, crazy universe. Well, thanks for joining us, see 916 00:46:29,560 --> 00:46:39,920 Speaker 1: you next time. Thanks for listening, and remember that Daniel 917 00:46:39,960 --> 00:46:42,480 Speaker 1: and Jorge explained. The Universe is a production of I 918 00:46:42,719 --> 00:46:46,120 Speaker 1: heart Radio. Or more podcast from my heart Radio, visit 919 00:46:46,160 --> 00:46:49,680 Speaker 1: the i heart Radio app, Apple Podcasts, or wherever you 920 00:46:49,760 --> 00:46:51,280 Speaker 1: listen to your favorite shows.