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Do you ever think about 38 00:02:12,080 --> 00:02:14,640 Speaker 1: what it's like to be in a fighter jet and 39 00:02:14,919 --> 00:02:17,840 Speaker 1: roll down the windows? Do you ever wonder if light 40 00:02:18,000 --> 00:02:22,919 Speaker 1: gets tired on its way across the universe from distant stars? 41 00:02:22,960 --> 00:02:26,000 Speaker 1: All the way to Earth. If so, then you're the 42 00:02:26,120 --> 00:02:28,760 Speaker 1: right person to be listening to this podcast, because that's 43 00:02:28,800 --> 00:02:30,639 Speaker 1: exactly the kind of stuff we're going to be talking 44 00:02:30,680 --> 00:02:51,560 Speaker 1: about today. Hi. I'm Daniel. I'm a particle physicist, and 45 00:02:51,639 --> 00:02:54,200 Speaker 1: I'm the co author of the book We Have No Idea, 46 00:02:54,400 --> 00:02:58,520 Speaker 1: A Guide to the Unknown Universe. My co author, Jorge Chim, 47 00:02:58,639 --> 00:03:01,560 Speaker 1: is usually the co host of the podcast Daniel and 48 00:03:01,639 --> 00:03:06,080 Speaker 1: Horagey Explain the Universe, brought to you by iHeartRadio. Today, 49 00:03:06,320 --> 00:03:08,840 Speaker 1: Hoge has to be away, so I'm going to do 50 00:03:08,880 --> 00:03:12,080 Speaker 1: the podcast by myself, and today we're doing something which 51 00:03:12,120 --> 00:03:17,040 Speaker 1: is absolutely my favorite, which is answering listener questions. I 52 00:03:17,120 --> 00:03:20,120 Speaker 1: love listener questions because they give me feedback and help 53 00:03:20,160 --> 00:03:23,919 Speaker 1: me understand what people out there are thinking, what they're understanding, 54 00:03:24,040 --> 00:03:26,679 Speaker 1: and what they're confused about. When Hoge and I do 55 00:03:26,800 --> 00:03:29,760 Speaker 1: lectures live, we talk about all the amazing mysteries of 56 00:03:29,800 --> 00:03:33,640 Speaker 1: the universe, and then people ask questions. And those questions 57 00:03:33,639 --> 00:03:37,120 Speaker 1: are so valuable because they show me exactly what people 58 00:03:37,160 --> 00:03:40,120 Speaker 1: have misunderstood. If I said something and I thought I 59 00:03:40,240 --> 00:03:42,560 Speaker 1: was super clear, and then somebody asked the question, it 60 00:03:42,560 --> 00:03:46,440 Speaker 1: helps me see how to better explain something, so I 61 00:03:46,520 --> 00:03:49,960 Speaker 1: really value listener questions. Thank you to everybody who has 62 00:03:50,040 --> 00:03:52,880 Speaker 1: written in, either with a point of confusion about something 63 00:03:52,880 --> 00:03:55,960 Speaker 1: that we said on the podcast or something totally crazy 64 00:03:56,000 --> 00:03:58,920 Speaker 1: that they were thinking about and they wanted us to explain. 65 00:03:59,440 --> 00:04:01,640 Speaker 1: And for all of you who have not written into 66 00:04:01,640 --> 00:04:04,240 Speaker 1: the podcast, what are you waiting for? We want to 67 00:04:04,240 --> 00:04:06,760 Speaker 1: hear your questions. When I say I answer every email, 68 00:04:06,880 --> 00:04:09,280 Speaker 1: I mean it. And when I say I love getting 69 00:04:09,360 --> 00:04:12,920 Speaker 1: questions from listeners, I am being totally serious. So please 70 00:04:13,240 --> 00:04:17,120 Speaker 1: send us your questions to questions at Danielandjorge dot com. 71 00:04:17,279 --> 00:04:20,240 Speaker 1: You might even hear yourself on the podcast. So today 72 00:04:20,320 --> 00:04:23,840 Speaker 1: we'll be answering listener questions. Questions about lights, questions about 73 00:04:23,839 --> 00:04:26,880 Speaker 1: black holes, questions about flying at the speed of sound 74 00:04:26,960 --> 00:04:29,719 Speaker 1: with the windows open, and all these questions have something 75 00:04:29,720 --> 00:04:32,480 Speaker 1: in common, which is they're sort of like what if questions, 76 00:04:32,560 --> 00:04:34,400 Speaker 1: like how could you do this? Or how could you 77 00:04:34,440 --> 00:04:36,719 Speaker 1: make this work? Or what would happen if you did 78 00:04:36,760 --> 00:04:40,120 Speaker 1: this thing? And all of these reveal people just desire 79 00:04:40,160 --> 00:04:43,200 Speaker 1: to understand what happens in the universe, to reveal secrets 80 00:04:43,240 --> 00:04:46,760 Speaker 1: of the universe by cooking up crazy scenarios, scenarios where 81 00:04:46,880 --> 00:04:49,680 Speaker 1: nature has to reveal the truth. And in the end, 82 00:04:49,760 --> 00:04:53,440 Speaker 1: that's really what experimental physics is. We want to know 83 00:04:53,480 --> 00:04:56,080 Speaker 1: the answer to a question, you know, does the universe 84 00:04:56,120 --> 00:04:58,320 Speaker 1: work this way or that way? And so we come 85 00:04:58,440 --> 00:05:01,640 Speaker 1: up with some scenario Nature has to reveal to us 86 00:05:01,680 --> 00:05:04,840 Speaker 1: the answer. We corner nature and say, well, show us, 87 00:05:05,160 --> 00:05:07,240 Speaker 1: you know, is light a particle or is it a wave? 88 00:05:07,880 --> 00:05:10,159 Speaker 1: Does the Higgs boson have this much mass or that 89 00:05:10,279 --> 00:05:14,520 Speaker 1: much mass? Really, all experimental physics is is constructing physical 90 00:05:14,520 --> 00:05:17,840 Speaker 1: scenarios where Nature has to show us her cards. And 91 00:05:17,880 --> 00:05:19,800 Speaker 1: so a lot of the questions you'll hear about today 92 00:05:20,040 --> 00:05:22,960 Speaker 1: are exactly that kind of question. So today we have 93 00:05:23,000 --> 00:05:24,880 Speaker 1: three questions. Let's dive in. 94 00:05:25,279 --> 00:05:28,640 Speaker 3: Hey, guys, my question is what would happen if we 95 00:05:28,800 --> 00:05:34,839 Speaker 3: quantum entangled two particles and took particle one and shot 96 00:05:34,839 --> 00:05:38,960 Speaker 3: it into a black hole? Could we learn anything? And 97 00:05:39,000 --> 00:05:41,599 Speaker 3: what do you think we could learn if we can 98 00:05:41,960 --> 00:05:47,080 Speaker 3: from particle two? Shout out to South Dakota and LEXI. 99 00:05:47,240 --> 00:05:49,799 Speaker 1: All right, I got this question and it blew my mind. 100 00:05:49,880 --> 00:05:52,440 Speaker 1: And it blew my mind because it combines so many 101 00:05:52,480 --> 00:05:55,159 Speaker 1: different things that I love. You got black holes, you 102 00:05:55,240 --> 00:05:59,000 Speaker 1: got quantum mechanics, you got inventing new ways to explore 103 00:05:59,000 --> 00:06:01,560 Speaker 1: the universe. Right, So I love when listeners think up 104 00:06:02,000 --> 00:06:05,440 Speaker 1: new ideas for how we could solve ancient questions. All right, 105 00:06:05,480 --> 00:06:08,240 Speaker 1: so first let's talk about why would we want to 106 00:06:08,320 --> 00:06:10,360 Speaker 1: know what's going on inside a black hole? Like, why 107 00:06:10,400 --> 00:06:13,280 Speaker 1: does anybody care? Isn't it just basically the garbage disposal 108 00:06:13,279 --> 00:06:16,680 Speaker 1: of the universe, jammed filled with rejected matter that's got 109 00:06:16,800 --> 00:06:19,760 Speaker 1: swoshed down the toilet bowl and into the black hole. Well, 110 00:06:19,760 --> 00:06:23,160 Speaker 1: that's what we don't know. General relativity tells us that 111 00:06:23,200 --> 00:06:26,520 Speaker 1: black holes might have a singularity in the center of them, right, 112 00:06:26,800 --> 00:06:31,240 Speaker 1: a tiny dot of matter with infinite density, something which 113 00:06:31,279 --> 00:06:34,360 Speaker 1: is hard for us to imagine. What does infinite density mean? 114 00:06:35,440 --> 00:06:38,760 Speaker 1: But according to Einstein's equations, that's exactly the conditions you 115 00:06:38,839 --> 00:06:41,839 Speaker 1: need to create a black hole. Fine, And we know 116 00:06:41,880 --> 00:06:45,640 Speaker 1: that Einstein's equations have been validated many, many times, and 117 00:06:45,680 --> 00:06:49,160 Speaker 1: nobody's ever found a flaw on them. They predicted gravitational waves, 118 00:06:49,240 --> 00:06:52,360 Speaker 1: We've seen them. They predicted all sorts of other crazy 119 00:06:52,400 --> 00:06:55,680 Speaker 1: gravitational phenomena, and they've been verified and checked. So, as 120 00:06:55,680 --> 00:07:00,120 Speaker 1: far as we know, Einstein's equations are correct except to 121 00:07:00,200 --> 00:07:03,400 Speaker 1: mechanics tells us that you can't have a singularity at 122 00:07:03,440 --> 00:07:06,120 Speaker 1: the center of a black hole. Remember, quantum mechanics tells 123 00:07:06,160 --> 00:07:09,640 Speaker 1: us the universe is not smooth and continuous, instead that 124 00:07:09,720 --> 00:07:14,080 Speaker 1: the universe is discrete. Space itself is probably pixelated into 125 00:07:14,160 --> 00:07:18,280 Speaker 1: tiny little units, right, Mass is probably pixelated, time is 126 00:07:18,320 --> 00:07:22,360 Speaker 1: probably pixelated. All these things are probably discrete and not continuous. 127 00:07:22,640 --> 00:07:25,520 Speaker 1: And that means you can't have an infinitely small dot, 128 00:07:25,720 --> 00:07:28,040 Speaker 1: certainly not one with an infinite mass inside of it. 129 00:07:28,280 --> 00:07:30,520 Speaker 1: In addition, is all sorts of issues about the Heisenberg 130 00:07:30,640 --> 00:07:33,960 Speaker 1: uncertainty principle. Can you have so much matter localized in 131 00:07:34,000 --> 00:07:37,800 Speaker 1: one spot for such a long time? Quantum mechanics says 132 00:07:37,840 --> 00:07:41,160 Speaker 1: that you should not find a singularity inside a black hole. 133 00:07:41,360 --> 00:07:44,320 Speaker 1: The problem, of course, is it's awfully difficult to look 134 00:07:44,360 --> 00:07:46,520 Speaker 1: inside a black hole. So I think that's probably what 135 00:07:46,560 --> 00:07:49,680 Speaker 1: motivates this question, the desire to see what's inside a 136 00:07:49,680 --> 00:07:52,040 Speaker 1: black hole. And I'll be honest, if I could see 137 00:07:52,080 --> 00:07:54,120 Speaker 1: inside a black hole, I would do it in a second. 138 00:07:54,120 --> 00:07:57,120 Speaker 1: I would love to know what is going on inside there, 139 00:07:57,480 --> 00:08:00,600 Speaker 1: all right. So the idea from this question is to 140 00:08:00,720 --> 00:08:04,720 Speaker 1: quantum entangle two particles and shoot one into a black hole, 141 00:08:05,080 --> 00:08:07,160 Speaker 1: and I guess use the other one to sort of 142 00:08:07,240 --> 00:08:10,920 Speaker 1: learn something about what's going on inside the black hole. Right, well, 143 00:08:11,040 --> 00:08:14,960 Speaker 1: let's talk about quantum entanglement. Quantum entanglement is a very 144 00:08:15,040 --> 00:08:17,480 Speaker 1: tricky topic, and we discussed it in some depth on 145 00:08:17,520 --> 00:08:20,800 Speaker 1: our quantum computing episode. The short version is that it 146 00:08:20,920 --> 00:08:26,520 Speaker 1: links two particles potentially across gray distances or great barriers 147 00:08:26,760 --> 00:08:29,000 Speaker 1: like the edge of a black hole. The link is 148 00:08:29,040 --> 00:08:32,200 Speaker 1: a kind of constraint. If one particle spins up, the 149 00:08:32,240 --> 00:08:35,200 Speaker 1: other one has to spin down. So by knowing something 150 00:08:35,240 --> 00:08:38,080 Speaker 1: about one of the particles discovering that it's spin up, 151 00:08:38,120 --> 00:08:41,040 Speaker 1: for example, you can learn something about the other such 152 00:08:41,080 --> 00:08:44,000 Speaker 1: as knowing that it's spinned down, even if you never 153 00:08:44,160 --> 00:08:47,120 Speaker 1: see it or can't possibly see it because it's hidden. 154 00:08:47,920 --> 00:08:51,280 Speaker 1: So you see the attraction for potentially probing a black 155 00:08:51,320 --> 00:08:55,400 Speaker 1: hole using pairs of entangled particles to sort of extract 156 00:08:55,480 --> 00:08:59,520 Speaker 1: some information from one particle by looking at the other one. 157 00:08:59,679 --> 00:09:02,319 Speaker 1: All right, Well, the short answer is we would learn nothing, 158 00:09:02,640 --> 00:09:05,400 Speaker 1: and the reason is that there are pretty solid theorems 159 00:09:05,440 --> 00:09:08,520 Speaker 1: about getting information out of the black hole. All right, 160 00:09:08,600 --> 00:09:12,440 Speaker 1: So the no hair theorem, I'm not joking. It's literally 161 00:09:12,480 --> 00:09:14,880 Speaker 1: called the no hair theorem, And I don't know if 162 00:09:14,920 --> 00:09:17,800 Speaker 1: it was invented by a visitist without hair, but the 163 00:09:17,880 --> 00:09:21,040 Speaker 1: no hair theorem says that the only information you could 164 00:09:21,040 --> 00:09:24,560 Speaker 1: get about a black hole is its mass, it's total 165 00:09:24,600 --> 00:09:28,560 Speaker 1: electric charge, and its momentum. That's it, right. You can't 166 00:09:28,600 --> 00:09:32,640 Speaker 1: get any other information. Nothing that's going on inside the 167 00:09:32,640 --> 00:09:35,400 Speaker 1: black hole can never leave, right. You certainly can't see 168 00:09:35,400 --> 00:09:37,920 Speaker 1: things escaping the black hole. Nothing can escape, so no 169 00:09:38,040 --> 00:09:40,840 Speaker 1: light can come out to reveal to you what's inside 170 00:09:40,840 --> 00:09:43,240 Speaker 1: the black hole. But more than that, you cannot get 171 00:09:43,280 --> 00:09:46,200 Speaker 1: any information, no matter how clever you are, other than 172 00:09:46,240 --> 00:09:50,000 Speaker 1: those three pieces of information. And this raises all sorts 173 00:09:50,040 --> 00:09:54,080 Speaker 1: of fascinating questions. Like the listener was asking about quantum 174 00:09:54,200 --> 00:09:56,600 Speaker 1: entangled particles where one is inside and one is outside 175 00:09:56,600 --> 00:10:00,000 Speaker 1: the black hole. That actually happens already. There's something called 176 00:10:00,000 --> 00:10:03,480 Speaker 1: called Hawking radiation, where a photon inside the black hole 177 00:10:03,679 --> 00:10:07,439 Speaker 1: will decay to two quantum entangled particles, and the decay 178 00:10:07,480 --> 00:10:10,480 Speaker 1: will happen so close to the event horizon that one 179 00:10:10,520 --> 00:10:13,360 Speaker 1: of the particles slips out of the event horizon and 180 00:10:13,440 --> 00:10:18,600 Speaker 1: gets to leave. That's Hawking radiation. It requires this quantum fluctuation, right, right, 181 00:10:18,640 --> 00:10:20,640 Speaker 1: at the edge of the event horizon. And so you 182 00:10:20,720 --> 00:10:24,920 Speaker 1: might ask, can we learn something about the side of 183 00:10:24,400 --> 00:10:27,520 Speaker 1: the hawking radiation that got slurped into the black hole 184 00:10:27,760 --> 00:10:30,640 Speaker 1: by looking at what happens outside the black hole by 185 00:10:30,640 --> 00:10:34,400 Speaker 1: measuring that hawking radiation. Well, the answer is no, no 186 00:10:34,520 --> 00:10:37,160 Speaker 1: information can leave the black hole. It's just impossible to 187 00:10:37,240 --> 00:10:40,760 Speaker 1: extract any information. Even though that electron and that positron 188 00:10:40,800 --> 00:10:43,840 Speaker 1: are entangled with each other, right, they do not contain 189 00:10:43,920 --> 00:10:47,280 Speaker 1: any information about what's going on inside the black hole. 190 00:10:47,559 --> 00:10:49,440 Speaker 1: And the shorter answer is, as soon as you're trying 191 00:10:49,440 --> 00:10:52,640 Speaker 1: to interact with the electron and positron, you will anyway 192 00:10:52,720 --> 00:10:53,760 Speaker 1: break that entanglement. 193 00:10:53,840 --> 00:10:53,960 Speaker 4: Right. 194 00:10:53,960 --> 00:10:57,520 Speaker 1: The entanglement only exists when those particles are isolated from 195 00:10:57,520 --> 00:10:59,480 Speaker 1: the rest of the system. So as soon as you 196 00:10:59,559 --> 00:11:02,160 Speaker 1: try to measure something about that electron, you're probably going 197 00:11:02,240 --> 00:11:05,920 Speaker 1: to break that entanglement anyway, which is usually usually the 198 00:11:05,960 --> 00:11:08,520 Speaker 1: problem with entanglement is that you can't really use it 199 00:11:08,559 --> 00:11:12,080 Speaker 1: to convey information because interacting with the particles breaks that 200 00:11:12,240 --> 00:11:16,440 Speaker 1: entanglement all right. This brings us to another fascinating and 201 00:11:16,520 --> 00:11:19,680 Speaker 1: current topic in black hole physics, which is people are 202 00:11:19,720 --> 00:11:25,000 Speaker 1: wondering where the information goes like, according to black hole theories, 203 00:11:25,320 --> 00:11:29,280 Speaker 1: no information can leave the black hole. Right, But according 204 00:11:29,280 --> 00:11:32,920 Speaker 1: to Hawking, radiation particles do escape the black hole, which 205 00:11:32,960 --> 00:11:35,240 Speaker 1: means the black hole can shrink. In fact, for small 206 00:11:35,280 --> 00:11:39,520 Speaker 1: black holes, black holes could even evaporate and disappear. So 207 00:11:39,559 --> 00:11:43,320 Speaker 1: what happens to the information that went into the black hole? 208 00:11:43,640 --> 00:11:46,560 Speaker 1: What happened to all those quantum states and all that 209 00:11:46,600 --> 00:11:49,080 Speaker 1: stuff that went into the black hole and then the 210 00:11:49,120 --> 00:11:53,040 Speaker 1: black hole disappeared, Because there's another law of quantum mechanics 211 00:11:53,080 --> 00:11:55,839 Speaker 1: that says It says that all the information about past 212 00:11:55,840 --> 00:11:58,240 Speaker 1: states in the universe is contained in the arrangement of 213 00:11:58,280 --> 00:12:01,520 Speaker 1: the current universe, right, no information should be lost. For 214 00:12:01,559 --> 00:12:05,480 Speaker 1: those mathematically inclined, this means essentially that the wave function 215 00:12:05,600 --> 00:12:08,680 Speaker 1: is unitary, right, The transformations through time do not change 216 00:12:08,760 --> 00:12:12,840 Speaker 1: the overall normalization of the wave function. So if black 217 00:12:12,880 --> 00:12:17,120 Speaker 1: holes can evaporate and disappear, but no information can leave 218 00:12:17,160 --> 00:12:21,280 Speaker 1: the black hole, that suggests that information is destroyed, and 219 00:12:21,360 --> 00:12:23,960 Speaker 1: that particular puzzle goes by the name of the black 220 00:12:24,000 --> 00:12:27,720 Speaker 1: hole information paradox, and people have proposed all sorts of 221 00:12:27,720 --> 00:12:30,800 Speaker 1: crazy solutions to this, including firewalls and all sorts of 222 00:12:30,880 --> 00:12:33,880 Speaker 1: crazy stuff that we might actually see at the edges 223 00:12:33,920 --> 00:12:36,640 Speaker 1: of black holes one day. So thank you for this 224 00:12:36,760 --> 00:12:40,760 Speaker 1: wonderful question about black holes and quantum mechanics and entanglement 225 00:12:40,880 --> 00:12:44,240 Speaker 1: and information and all sorts of crazy amazing stuff. One 226 00:12:44,240 --> 00:12:46,240 Speaker 1: of my favorite things about these kinds of questions is 227 00:12:46,240 --> 00:12:49,839 Speaker 1: that they seem theoretical, they seem crazy abstract, but these 228 00:12:49,880 --> 00:12:53,000 Speaker 1: are real, like black holes, they're real objects. They are 229 00:12:53,040 --> 00:12:55,679 Speaker 1: out there, and one day, if we build the right 230 00:12:55,760 --> 00:12:57,480 Speaker 1: kind of spaceship and the right kind of probes, we 231 00:12:57,480 --> 00:12:59,200 Speaker 1: could go when we could observe them, and we might 232 00:12:59,280 --> 00:13:02,240 Speaker 1: learn the answer to some of these questions. So thanks 233 00:13:02,280 --> 00:13:05,160 Speaker 1: for sending in that question, and keep writing. Well, this 234 00:13:05,320 --> 00:13:07,160 Speaker 1: is a perfect spot to take a break. We'll be 235 00:13:07,360 --> 00:13:14,640 Speaker 1: right back. 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If you want 271 00:14:59,440 --> 00:15:01,800 Speaker 4: to do more and spend less, like Uber eight by 272 00:15:01,920 --> 00:15:04,640 Speaker 4: eight and Data Bricks Mosaic, take a free test drive 273 00:15:04,640 --> 00:15:09,080 Speaker 4: of OCI at Oracle dot com slash Strategic. That's Oracle 274 00:15:09,120 --> 00:15:13,640 Speaker 4: dot com slash Strategic Oracle dot com slash Strategic. 275 00:15:13,920 --> 00:15:17,240 Speaker 1: If you love iPhone, you'll love Applecard. It's the credit 276 00:15:17,240 --> 00:15:21,200 Speaker 1: card designed for iPhone. It gives you unlimited daily cash 277 00:15:21,280 --> 00:15:24,320 Speaker 1: back that can earn four point four zero percent annual 278 00:15:24,400 --> 00:15:27,240 Speaker 1: percentage yield. When you open a high Yield Savings account 279 00:15:27,280 --> 00:15:30,960 Speaker 1: through Applecard, apply for Applecard in the wallet app, subject 280 00:15:30,960 --> 00:15:34,360 Speaker 1: to credit approval. Savings is available to Applecard owners subject 281 00:15:34,440 --> 00:15:37,960 Speaker 1: to eligibility. Apple Card and Savings by Goldman Sachs Bank USA, 282 00:15:38,000 --> 00:15:41,280 Speaker 1: Salt Lake City branch member, FDIC, terms and more at 283 00:15:41,320 --> 00:15:53,040 Speaker 1: applecard dot com. This is a wonderful question that we 284 00:15:53,120 --> 00:15:56,560 Speaker 1: got recently from a listener and from that listener's dad. 285 00:15:56,920 --> 00:16:00,480 Speaker 5: Hi, my name is Phineas and I'm in four and 286 00:16:00,480 --> 00:16:03,520 Speaker 5: I live in Psicho, Alaska. I was wondering if you 287 00:16:03,560 --> 00:16:05,720 Speaker 5: were in an airplane going faster than the speed of 288 00:16:05,800 --> 00:16:08,600 Speaker 5: sound and you said something to the person next to you, 289 00:16:08,920 --> 00:16:11,160 Speaker 5: would they actually be able to hear what you said. 290 00:16:12,080 --> 00:16:15,160 Speaker 6: This is Phineas's dad. Phineas asked me this question a 291 00:16:15,160 --> 00:16:18,600 Speaker 6: while ago, and it got me wondering if one was 292 00:16:18,720 --> 00:16:22,560 Speaker 6: traveling at or above the speed of light, would they 293 00:16:22,560 --> 00:16:25,040 Speaker 6: be able to see the person next to them? 294 00:16:25,400 --> 00:16:28,200 Speaker 1: So I love this question for so many reasons. I 295 00:16:28,280 --> 00:16:30,800 Speaker 1: love that that young boy is imagining what it's like 296 00:16:30,920 --> 00:16:33,080 Speaker 1: to be on a spaceship or what it's like to 297 00:16:33,080 --> 00:16:36,040 Speaker 1: be on a plane traveling past the speed of sound. 298 00:16:36,080 --> 00:16:38,960 Speaker 1: And it's a great question. He's wondering about how this 299 00:16:39,080 --> 00:16:42,720 Speaker 1: information is processed, how this information is transmitted. Essentially, are 300 00:16:42,760 --> 00:16:46,360 Speaker 1: you leaving that information behind right? Well, first of all, 301 00:16:46,480 --> 00:16:48,680 Speaker 1: I want to break his bubble and say, if you're 302 00:16:48,720 --> 00:16:51,280 Speaker 1: on a fighter jet that's traveling faster than the speed 303 00:16:51,280 --> 00:16:54,560 Speaker 1: of sound. Probably you don't have the windows open, right, 304 00:16:54,680 --> 00:16:57,040 Speaker 1: which means that you're in a little air bubble. That 305 00:16:57,160 --> 00:16:59,960 Speaker 1: air bubble is moving with you fast and the speed 306 00:17:00,200 --> 00:17:02,880 Speaker 1: of sound. If you had the windows open and the 307 00:17:02,920 --> 00:17:05,520 Speaker 1: air was rushing past you fasten the speed of sound, 308 00:17:06,000 --> 00:17:08,920 Speaker 1: it would probably tear you to shreds. And that's why 309 00:17:09,080 --> 00:17:12,040 Speaker 1: fighter jets, for example, have that little bubble right the 310 00:17:12,160 --> 00:17:16,000 Speaker 1: window that protects them from what's going on outside. All right, 311 00:17:16,040 --> 00:17:18,040 Speaker 1: so they have a little bubble of air. And that's 312 00:17:18,080 --> 00:17:22,280 Speaker 1: the key. Because sound is a wave, right, Sound is 313 00:17:22,359 --> 00:17:25,480 Speaker 1: just vibrations of the air, and so what it does 314 00:17:25,560 --> 00:17:29,240 Speaker 1: is it moves relative to the air. Right. It's like 315 00:17:29,280 --> 00:17:31,800 Speaker 1: if you have a bathtub of water and you're slapping 316 00:17:31,840 --> 00:17:35,160 Speaker 1: it to make to make waves, the waves move relative 317 00:17:35,200 --> 00:17:38,320 Speaker 1: to the water. If that water, if that bathtub was 318 00:17:38,320 --> 00:17:42,000 Speaker 1: on a train traveling a super duper fast, it wouldn't 319 00:17:42,040 --> 00:17:44,000 Speaker 1: make any difference. Right, You could still have a bath 320 00:17:44,280 --> 00:17:46,560 Speaker 1: and you could still make splashes and they wouldn't be 321 00:17:46,560 --> 00:17:49,359 Speaker 1: any different. In the same way, if you're on a 322 00:17:49,400 --> 00:17:51,600 Speaker 1: fighter jet and you're in a little bubble of air 323 00:17:51,720 --> 00:17:54,359 Speaker 1: inside the fighter jet, you can turn to the person 324 00:17:54,400 --> 00:17:57,080 Speaker 1: next to you can say hello, would you please pass 325 00:17:57,119 --> 00:17:57,680 Speaker 1: the peanuts? 326 00:17:57,800 --> 00:17:58,160 Speaker 4: Or whatever? 327 00:17:58,200 --> 00:18:00,280 Speaker 1: You say to somebody in a fighter jet and the 328 00:18:00,320 --> 00:18:03,639 Speaker 1: air between you is not moving relative to you, so 329 00:18:03,720 --> 00:18:06,560 Speaker 1: you can send waves through it normally, just as you 330 00:18:06,600 --> 00:18:08,800 Speaker 1: would if you were sitting on your couch in your 331 00:18:08,800 --> 00:18:11,399 Speaker 1: living room. So the sort of cheap answer to the 332 00:18:11,440 --> 00:18:14,560 Speaker 1: question is that there's no difference if you're in a 333 00:18:14,560 --> 00:18:17,240 Speaker 1: little bubble of air that's moving with you, all right, 334 00:18:17,320 --> 00:18:20,520 Speaker 1: So that's no fun. Let's imagine what happens when you 335 00:18:20,600 --> 00:18:24,280 Speaker 1: open the windows, right, you're going mock to you're zooming 336 00:18:24,320 --> 00:18:27,000 Speaker 1: through the atmosphere. You open the windows, all of a sudden, 337 00:18:27,040 --> 00:18:29,560 Speaker 1: the wind is screaming past you at two thousand miles 338 00:18:29,640 --> 00:18:33,000 Speaker 1: per hour. Right now, that's an interesting question. What happens 339 00:18:33,040 --> 00:18:34,880 Speaker 1: if you turn to your friend and you say, pass 340 00:18:34,960 --> 00:18:38,120 Speaker 1: the bananas? Right? Can they hear you? The key thing 341 00:18:38,160 --> 00:18:41,440 Speaker 1: to remember is that sound moves at a fixed speed 342 00:18:41,840 --> 00:18:44,960 Speaker 1: relative to the air. So if you shout into a 343 00:18:45,040 --> 00:18:48,200 Speaker 1: wind blowing at your back, then your shout gets carried 344 00:18:48,240 --> 00:18:50,840 Speaker 1: away from you by the wind more quickly than if 345 00:18:50,840 --> 00:18:54,520 Speaker 1: there had been no wind. Similarly, if the wind is 346 00:18:54,640 --> 00:18:58,040 Speaker 1: blowing in your face, it can slow down your shout. 347 00:18:58,200 --> 00:19:01,480 Speaker 1: If the wind blows in your face at this of sound. Ouch. 348 00:19:01,920 --> 00:19:05,760 Speaker 1: Then when you scream, your scream doesn't actually go anywhere, 349 00:19:05,800 --> 00:19:09,080 Speaker 1: it stays right there on top of you. So in 350 00:19:09,119 --> 00:19:11,800 Speaker 1: the fighter jet, if the windshield is down or whatever 351 00:19:11,840 --> 00:19:13,720 Speaker 1: they call it in a fighter jet, then they can 352 00:19:13,800 --> 00:19:15,960 Speaker 1: just talk normally. Right they're in a bubble of air, 353 00:19:16,359 --> 00:19:18,400 Speaker 1: just like if you're in a bathtub and you make waves. 354 00:19:18,560 --> 00:19:20,560 Speaker 1: It doesn't matter if you're on a train at the time, 355 00:19:20,600 --> 00:19:23,480 Speaker 1: because the water is moving with you. But if they 356 00:19:23,560 --> 00:19:26,720 Speaker 1: open the windshield, the wind is whipping by them at 357 00:19:26,760 --> 00:19:29,640 Speaker 1: faster than the speed of sound, and so they will 358 00:19:29,760 --> 00:19:33,400 Speaker 1: leave their words behind. There's no way that they can talk, 359 00:19:33,520 --> 00:19:36,720 Speaker 1: even if they shout straightforwards. This is also why planes 360 00:19:36,760 --> 00:19:40,000 Speaker 1: make sonic booms. If a plane is traveling faster than 361 00:19:40,000 --> 00:19:43,080 Speaker 1: the sound it's making, then it's catching up to its 362 00:19:43,119 --> 00:19:46,040 Speaker 1: own sound, and the sound from two seconds ago gets 363 00:19:46,119 --> 00:19:48,160 Speaker 1: piled up on top of the sound from one second 364 00:19:48,240 --> 00:19:50,560 Speaker 1: ago and the sound from right now. It's the same 365 00:19:50,680 --> 00:19:54,240 Speaker 1: amount of sound total, doesn't generate more sound, but it 366 00:19:54,240 --> 00:19:58,360 Speaker 1: gets concentrated in certain places because the plane is outracing 367 00:19:58,400 --> 00:20:00,919 Speaker 1: the sound it's making. It's like with a boat in 368 00:20:00,960 --> 00:20:04,040 Speaker 1: the water if it travels faster than the waves and water, 369 00:20:04,400 --> 00:20:06,480 Speaker 1: then those waves pile up and you get a wake. 370 00:20:06,800 --> 00:20:10,280 Speaker 1: A sonic boom is just a plane's wake. All right, 371 00:20:10,359 --> 00:20:13,320 Speaker 1: awesome question. And my favorite part I think of this 372 00:20:13,840 --> 00:20:16,400 Speaker 1: is that his dad couldn't help but jump in and 373 00:20:16,520 --> 00:20:19,720 Speaker 1: ask an even more physics e question, right, A question 374 00:20:19,800 --> 00:20:22,800 Speaker 1: about traveling at or faster than the speed of light. 375 00:20:23,640 --> 00:20:26,200 Speaker 1: Wonderful And I love this because it allows us to 376 00:20:26,280 --> 00:20:28,720 Speaker 1: draw this contrast between the speed of sound and the 377 00:20:28,720 --> 00:20:31,280 Speaker 1: speed of light. Now, first of all, of course, you 378 00:20:31,320 --> 00:20:34,320 Speaker 1: can't travel at the speed of light, right, Nothing that 379 00:20:34,400 --> 00:20:37,639 Speaker 1: has mass can travel at the speed of light. Only 380 00:20:37,680 --> 00:20:40,240 Speaker 1: things that are massless travel at the speed of light, 381 00:20:40,640 --> 00:20:46,080 Speaker 1: and everything that's massless travels at the speed of light. Photons, gravitons, 382 00:20:46,080 --> 00:20:49,440 Speaker 1: if they exist, anything that does not have mass has 383 00:20:49,520 --> 00:20:52,200 Speaker 1: to travel at the speed of light, and always at 384 00:20:52,240 --> 00:20:55,600 Speaker 1: the speed of light. It can't go any slower. The 385 00:20:55,680 --> 00:20:59,000 Speaker 1: amazing thing about photons is not only that they travel 386 00:20:59,000 --> 00:21:01,119 Speaker 1: at the speed of light, which is super duper fast, 387 00:21:01,560 --> 00:21:05,280 Speaker 1: but that they don't travel relative to some medium sound 388 00:21:05,320 --> 00:21:08,480 Speaker 1: and water. Waves travel at fixed speeds relative to their 389 00:21:08,520 --> 00:21:12,240 Speaker 1: medium air or water, but the rules are totally different 390 00:21:12,280 --> 00:21:15,359 Speaker 1: for light. It's a wave, but it always moves at 391 00:21:15,359 --> 00:21:18,199 Speaker 1: the speed of light relative to the person measuring it, 392 00:21:18,680 --> 00:21:23,240 Speaker 1: not relative to the medium, because it doesn't have a medium. Now, 393 00:21:23,280 --> 00:21:25,719 Speaker 1: for a while people thought that there has to be 394 00:21:25,760 --> 00:21:27,919 Speaker 1: some medium that light traveled through, and they called it 395 00:21:28,160 --> 00:21:30,879 Speaker 1: ether and searched for it. But now we know that 396 00:21:30,920 --> 00:21:34,280 Speaker 1: there is no ether, no medium that's doing the waving 397 00:21:34,359 --> 00:21:37,679 Speaker 1: for light like air does for sound. The Michaelson Morally 398 00:21:37,720 --> 00:21:40,440 Speaker 1: experiments showed us that because they measured the speed of 399 00:21:40,520 --> 00:21:44,040 Speaker 1: light in two different directions and found them to be identical, 400 00:21:44,359 --> 00:21:46,879 Speaker 1: even though the Earth is obviously moving in one direction 401 00:21:47,040 --> 00:21:49,320 Speaker 1: or the other as it goes around the Sun. The 402 00:21:49,359 --> 00:21:52,240 Speaker 1: reason is because light doesn't have a medium. It's the 403 00:21:52,320 --> 00:21:55,879 Speaker 1: waving of quantum fields that are the properties of space itself. 404 00:21:56,200 --> 00:21:59,200 Speaker 1: So space can be empty and still have light in it. 405 00:21:59,359 --> 00:22:01,160 Speaker 1: And the way we sh Yoda is that we discovered 406 00:22:01,160 --> 00:22:05,080 Speaker 1: that light moves at the speed of light relative to everybody, 407 00:22:05,160 --> 00:22:08,080 Speaker 1: no matter how fast you're going. So if you are 408 00:22:08,160 --> 00:22:11,320 Speaker 1: standing on Earth and you turn on a flashlight, those 409 00:22:11,359 --> 00:22:16,200 Speaker 1: photons leave your flashlight at the speed of light. Right. Cool. Now, 410 00:22:16,240 --> 00:22:19,720 Speaker 1: what happens if you jump into Lamborghini and you turn 411 00:22:19,760 --> 00:22:22,200 Speaker 1: on a flashlight, the Lamborghini is going to two hundred 412 00:22:22,240 --> 00:22:25,200 Speaker 1: miles per hour. You're in the Lamborghini, you turn on 413 00:22:25,240 --> 00:22:28,440 Speaker 1: the flashlight. What happens, Well, the light leaves your flashlight 414 00:22:28,720 --> 00:22:31,560 Speaker 1: at the speed of light relative to you. No big deal. 415 00:22:32,440 --> 00:22:34,720 Speaker 1: What about somebody on the ground, right, the person you 416 00:22:34,880 --> 00:22:37,080 Speaker 1: left behind who you didn't offer a ride in your 417 00:22:37,160 --> 00:22:41,399 Speaker 1: Lamborghini to. When you turn on the flashlight in your Lamborghini, 418 00:22:41,680 --> 00:22:44,200 Speaker 1: how fast do they see the light going? Well, you 419 00:22:44,280 --> 00:22:46,679 Speaker 1: might think, well, it's the speed of light plus the 420 00:22:46,720 --> 00:22:49,879 Speaker 1: speed of the Lamborghini, right, because the flashlight itself is 421 00:22:49,960 --> 00:22:52,520 Speaker 1: moving at two hundred miles per hour. But that's where 422 00:22:52,560 --> 00:22:55,520 Speaker 1: you'd be wrong. Right, That's why light is weird. That's 423 00:22:55,520 --> 00:22:59,400 Speaker 1: how our whole universe is super bizarre. Frankly, it's bunkers. 424 00:23:00,160 --> 00:23:03,000 Speaker 1: We know that light always travels at the speed of light, 425 00:23:03,160 --> 00:23:06,120 Speaker 1: no matter what the speed of the thing making it is, right, 426 00:23:06,160 --> 00:23:09,600 Speaker 1: And everybody who measures the speed of light always sees 427 00:23:09,640 --> 00:23:11,920 Speaker 1: it moving at the speed of light relative to them. 428 00:23:12,560 --> 00:23:13,800 Speaker 1: And that's different from sound. 429 00:23:13,880 --> 00:23:13,960 Speaker 6: Right. 430 00:23:14,080 --> 00:23:17,320 Speaker 1: Sound travels relative to a medium like air, and that's 431 00:23:17,359 --> 00:23:20,480 Speaker 1: sort of an absolute reference frame, and sound always moves 432 00:23:20,520 --> 00:23:22,919 Speaker 1: at the same speed relative to the air. And so 433 00:23:22,960 --> 00:23:24,800 Speaker 1: if you're moving with respect to the air, like you're 434 00:23:24,800 --> 00:23:26,720 Speaker 1: in a fighter jet and you're moving at the speed 435 00:23:26,720 --> 00:23:30,760 Speaker 1: of sound, if you scream, then you're moving with that sound. Right, 436 00:23:30,760 --> 00:23:33,320 Speaker 1: So if you scream in a fighter jet and you're 437 00:23:33,320 --> 00:23:35,040 Speaker 1: moving at the speed of sound, and you can basically 438 00:23:35,119 --> 00:23:38,080 Speaker 1: just like stay inside your scream, you can fly along 439 00:23:38,440 --> 00:23:42,240 Speaker 1: through the air with your scream. That's not true with light, right. 440 00:23:42,320 --> 00:23:44,720 Speaker 1: Light will always move at the speed of light relative 441 00:23:44,760 --> 00:23:47,639 Speaker 1: to you. You turn on that flashlight, even if you 442 00:23:47,640 --> 00:23:49,800 Speaker 1: were traveling very close to the speed of light, you 443 00:23:49,840 --> 00:23:52,960 Speaker 1: couldn't stay with those photons. They would leave you at 444 00:23:53,000 --> 00:23:55,880 Speaker 1: the speed of light. And so if you're traveling very 445 00:23:55,880 --> 00:23:57,679 Speaker 1: close to the speed of light, because you can't travel 446 00:23:57,760 --> 00:24:00,960 Speaker 1: at the speed of light, and you look next to you, right, 447 00:24:01,160 --> 00:24:03,840 Speaker 1: and the person next to you has a flashlight, it's 448 00:24:03,840 --> 00:24:07,200 Speaker 1: going to act totally normally for you, right, It doesn't 449 00:24:07,240 --> 00:24:10,760 Speaker 1: matter what's happening outside. Light always travels at the speed 450 00:24:10,800 --> 00:24:13,320 Speaker 1: of light relative to you. So the short answer to 451 00:24:13,400 --> 00:24:17,040 Speaker 1: your question is, if you're traveling nearly at the speed 452 00:24:17,040 --> 00:24:20,440 Speaker 1: of light, then everything will feel normal inside your spaceship, 453 00:24:20,640 --> 00:24:23,359 Speaker 1: clocks will run normally. Everything will seem normal. Now if 454 00:24:23,400 --> 00:24:25,480 Speaker 1: you look outside your spaceship, but things that are not 455 00:24:25,680 --> 00:24:28,639 Speaker 1: traveling at that high speed, that's when relativity kicks in. 456 00:24:29,080 --> 00:24:32,160 Speaker 1: Things seem to run slow and they seem to get shrunk, right, 457 00:24:32,440 --> 00:24:35,760 Speaker 1: But light always travels at the same speed no matter what. 458 00:24:37,600 --> 00:24:39,640 Speaker 1: I hope that was an answer to your question. Thank 459 00:24:39,680 --> 00:24:42,160 Speaker 1: you so much for writing in, thank you for wondering 460 00:24:42,160 --> 00:24:44,320 Speaker 1: about the universe, and thank you to all the parents 461 00:24:44,400 --> 00:24:47,760 Speaker 1: out there who are sharing their wonderings about the universe 462 00:24:47,800 --> 00:24:50,520 Speaker 1: with their kids, and sharing this podcast with their kids 463 00:24:50,840 --> 00:24:54,600 Speaker 1: and letting their kids ask us crazy, awesome, amazing, super 464 00:24:54,680 --> 00:24:58,919 Speaker 1: fun questions about the universe that we totally love to answer. 465 00:24:59,080 --> 00:25:01,600 Speaker 1: Let's get to our last this question, but first let's 466 00:25:01,640 --> 00:25:07,960 Speaker 1: take a break. When you pop a piece of cheese 467 00:25:08,000 --> 00:25:11,040 Speaker 1: into your mouth or enjoy a rich spoonful of Greek yogurt, 468 00:25:11,119 --> 00:25:14,760 Speaker 1: you're probably not thinking about the environmental impact of each 469 00:25:15,000 --> 00:25:17,440 Speaker 1: and every bite, But the people in the dairy industry 470 00:25:17,520 --> 00:25:21,439 Speaker 1: are US. Dairy has set themselves some ambitious sustainability goals, 471 00:25:21,520 --> 00:25:24,840 Speaker 1: including being greenhouse gas neutral by twenty to fifty. That's 472 00:25:24,880 --> 00:25:27,080 Speaker 1: why they're working hard every day to find new ways 473 00:25:27,119 --> 00:25:30,760 Speaker 1: to reduce waste, conserve natural resources, and drive down greenhouse 474 00:25:30,760 --> 00:25:34,199 Speaker 1: gas emissions. Take water. For example, most dairy farms reuse 475 00:25:34,320 --> 00:25:37,320 Speaker 1: water up to four times. The same water cools the milk, 476 00:25:37,480 --> 00:25:40,840 Speaker 1: cleans equipment, washes the barn, and irrigates the crops. How 477 00:25:40,920 --> 00:25:44,480 Speaker 1: is US dairy tackling greenhouse gases. Many farms use anaerobic 478 00:25:44,520 --> 00:25:47,800 Speaker 1: digestors that turn the methane from maneuver into renewable energy 479 00:25:47,920 --> 00:25:50,600 Speaker 1: that can power farms, towns, and electric cars. So the 480 00:25:50,640 --> 00:25:52,480 Speaker 1: next time you grab a slice of pizza or lick 481 00:25:52,520 --> 00:25:55,159 Speaker 1: an ice cream cone, know that dairy farmers and processors 482 00:25:55,200 --> 00:25:58,360 Speaker 1: around the country are using the latest practices and innovations 483 00:25:58,520 --> 00:26:01,359 Speaker 1: to provide the nutrient dense every products we love with 484 00:26:01,520 --> 00:26:04,000 Speaker 1: less of an impact. Visit us dairy dot com slash 485 00:26:04,040 --> 00:26:05,520 Speaker 1: sustainability to learn more. 486 00:26:06,560 --> 00:26:10,040 Speaker 7: There are children, friends, and families walking, riding on paths 487 00:26:10,040 --> 00:26:12,520 Speaker 7: and roads every day. Remember they're real people with loved 488 00:26:12,520 --> 00:26:14,720 Speaker 7: ones who need them to get home safely. Protect our 489 00:26:14,760 --> 00:26:18,280 Speaker 7: cyclists and pedestrians because they're people too. Go safely California 490 00:26:18,320 --> 00:26:20,960 Speaker 7: from the California Office of Traffic Safety and Caltrans. 491 00:26:22,119 --> 00:26:24,879 Speaker 8: In the rhythm of our daily lives, it's the little 492 00:26:24,920 --> 00:26:28,840 Speaker 8: things that make the greatest impact. At the Monterey Bay Aquarium. 493 00:26:28,960 --> 00:26:33,240 Speaker 8: Those moments blossom into memories where every side and sound 494 00:26:33,400 --> 00:26:36,840 Speaker 8: connects us with the natural world. Embark on a journey 495 00:26:36,840 --> 00:26:40,880 Speaker 8: of discovery today, from the captivating canopy of the Kelpforest 496 00:26:40,960 --> 00:26:44,200 Speaker 8: to the enigmatic depths of the deep sea. Monterey Bay 497 00:26:44,240 --> 00:26:48,840 Speaker 8: Aquarium inspiring conservation of the ocean. Visit Monterey Bay Aquarium 498 00:26:48,920 --> 00:26:50,360 Speaker 8: dot org, slash together. 499 00:26:59,320 --> 00:27:03,000 Speaker 1: Okay, and we're answering listener questions. Today. We talked about 500 00:27:03,200 --> 00:27:05,280 Speaker 1: zooming around at the speed of sound or the speed 501 00:27:05,280 --> 00:27:08,959 Speaker 1: of light, and we talked about quantum entanglement and black holes. 502 00:27:09,119 --> 00:27:11,679 Speaker 1: And our last question is also related to light and 503 00:27:11,800 --> 00:27:14,200 Speaker 1: zooming across the universe. Here it is. 504 00:27:14,840 --> 00:27:17,600 Speaker 9: Hello, Daniel and Jorge. My name is Marcella and I'm 505 00:27:17,600 --> 00:27:21,040 Speaker 9: Fromrio Janeto, Brazil. I'm a big fan of your podcasts 506 00:27:21,119 --> 00:27:24,040 Speaker 9: and your book. So my question is about how does 507 00:27:24,200 --> 00:27:28,879 Speaker 9: light carry information or how exactly does a photon transmit 508 00:27:29,080 --> 00:27:32,360 Speaker 9: or carry within itself a pixel so that we are 509 00:27:32,400 --> 00:27:35,520 Speaker 9: able to see the images we see on our telescopes. 510 00:27:36,000 --> 00:27:39,960 Speaker 9: How does it not disintegrate after traveling so far? Thank 511 00:27:40,000 --> 00:27:40,600 Speaker 9: you so much. 512 00:27:41,600 --> 00:27:43,959 Speaker 1: All right, that's not really one question, that's like a 513 00:27:44,000 --> 00:27:47,160 Speaker 1: bunch of questions all stuck together, but totally fair. We'll 514 00:27:47,200 --> 00:27:49,440 Speaker 1: answer all of them. The first part of the question 515 00:27:49,600 --> 00:27:53,080 Speaker 1: was essentially what information does light carry? And I think 516 00:27:53,080 --> 00:27:55,720 Speaker 1: the question is trying to ask, like, when you see 517 00:27:55,760 --> 00:27:58,639 Speaker 1: a picture of like a distant star, what is it 518 00:27:58,680 --> 00:28:01,920 Speaker 1: that the photon is carrying? How does that picture come 519 00:28:01,920 --> 00:28:04,479 Speaker 1: from the star and end up in my eyeballs or 520 00:28:04,680 --> 00:28:07,800 Speaker 1: in my telescope. First, let's be really microscopic about it, right, 521 00:28:07,840 --> 00:28:10,479 Speaker 1: what happens when you see a star is that you're 522 00:28:10,520 --> 00:28:14,280 Speaker 1: seeing photons from that star. So somewhere really far away, 523 00:28:14,600 --> 00:28:17,240 Speaker 1: at billions of miles away, that big ball of fusion 524 00:28:17,280 --> 00:28:20,240 Speaker 1: is shooting out photons. And once the photons leave the star, 525 00:28:20,440 --> 00:28:22,480 Speaker 1: they have nothing to do with the star anymore. Right, 526 00:28:22,520 --> 00:28:24,399 Speaker 1: they are flying through space and the fact that they 527 00:28:24,400 --> 00:28:27,560 Speaker 1: came from the star is irrelevant. But they do carry information. 528 00:28:28,080 --> 00:28:29,879 Speaker 1: They're pointing in a specific direction. 529 00:28:30,160 --> 00:28:30,400 Speaker 4: Right. 530 00:28:30,440 --> 00:28:33,399 Speaker 1: That's information. If you see light coming from one direction 531 00:28:33,520 --> 00:28:36,280 Speaker 1: or another left versus right, it tells you where that 532 00:28:36,400 --> 00:28:39,680 Speaker 1: object is. Right, So where in the sky the light 533 00:28:39,760 --> 00:28:42,560 Speaker 1: is coming from is very important information to know where 534 00:28:42,600 --> 00:28:45,480 Speaker 1: that star might be. So first piece of information light 535 00:28:45,560 --> 00:28:49,880 Speaker 1: carries is its direction. Second very important piece of information 536 00:28:50,080 --> 00:28:53,760 Speaker 1: is its energy. Every photon has a certain amount of energy, 537 00:28:53,840 --> 00:28:55,920 Speaker 1: and this is the critical thing about photons. This is 538 00:28:55,960 --> 00:28:59,040 Speaker 1: the reason we know photons exist is that light comes 539 00:28:59,040 --> 00:29:01,440 Speaker 1: in these little packets of energy. That's basically what a 540 00:29:01,440 --> 00:29:05,200 Speaker 1: photon is. And the specific energy that a photon has 541 00:29:05,480 --> 00:29:10,520 Speaker 1: also determines its frequency. Remember, photons their particles, their waves, 542 00:29:10,640 --> 00:29:12,320 Speaker 1: but when you think about them as waves, you have 543 00:29:12,400 --> 00:29:15,720 Speaker 1: to think about them as sort of electromagnetic fluctuations, like 544 00:29:15,840 --> 00:29:20,600 Speaker 1: vibrations in the electromagnetic field. Those vibrations have a certain frequency, 545 00:29:20,920 --> 00:29:23,520 Speaker 1: and you've probably heard of visible light having frequencies in 546 00:29:23,560 --> 00:29:26,840 Speaker 1: the range of hundreds of nanometers. So every photon has 547 00:29:26,880 --> 00:29:29,600 Speaker 1: a certain amount of energy. That energy determines a few 548 00:29:29,680 --> 00:29:33,240 Speaker 1: things about the photon. It determines the frequency of the wiggles, 549 00:29:33,240 --> 00:29:36,960 Speaker 1: because remember photons are just electromagnetic waves and they're wiggling 550 00:29:37,000 --> 00:29:40,840 Speaker 1: along through space their vibrations in the electromagnetic field or 551 00:29:40,960 --> 00:29:43,200 Speaker 1: the quantum photon field, if you want to think about 552 00:29:43,200 --> 00:29:46,000 Speaker 1: it in terms of quantum field theory. So it determines 553 00:29:46,040 --> 00:29:51,000 Speaker 1: its frequency and also its wavelength, and in addition, those 554 00:29:51,000 --> 00:29:53,880 Speaker 1: things determine the photon's color. But color, of course, is 555 00:29:53,920 --> 00:29:56,440 Speaker 1: something even more complicated. We're gonna have a whole episode 556 00:29:56,440 --> 00:29:59,040 Speaker 1: about that soon, what it means to see different colors. 557 00:29:59,280 --> 00:30:02,680 Speaker 1: But essentially the energy carries all this information. So so 558 00:30:02,840 --> 00:30:05,560 Speaker 1: far we have a photon zooming through space, and it's 559 00:30:05,680 --> 00:30:08,960 Speaker 1: carrying information about its direction, and it's carrying information about 560 00:30:09,000 --> 00:30:11,600 Speaker 1: the energy, and that's most of the information you need 561 00:30:11,640 --> 00:30:14,120 Speaker 1: from a photon. If you think about all the photons 562 00:30:14,160 --> 00:30:16,840 Speaker 1: coming off the sun, for example, then there's a big 563 00:30:17,160 --> 00:30:20,360 Speaker 1: mix of frequencies. There's green, there's red, there's blue, there's 564 00:30:20,400 --> 00:30:22,840 Speaker 1: all those together and together they make white. So the 565 00:30:22,920 --> 00:30:24,760 Speaker 1: image you see of the sun, if you look at 566 00:30:24,800 --> 00:30:26,959 Speaker 1: the sun please don't or if you take a picture 567 00:30:26,960 --> 00:30:29,960 Speaker 1: of the sun, is you see all those photons coming 568 00:30:30,000 --> 00:30:33,280 Speaker 1: together into your telescope or your camera or your eye, 569 00:30:33,560 --> 00:30:37,440 Speaker 1: and it's making that image. It's summed up all those 570 00:30:37,480 --> 00:30:40,680 Speaker 1: little bits of photons together make that image. It's really 571 00:30:40,840 --> 00:30:43,480 Speaker 1: similar to the way you look at a screen. A 572 00:30:43,520 --> 00:30:46,240 Speaker 1: screen is a bunch of pixels. It's an image broken 573 00:30:46,280 --> 00:30:48,960 Speaker 1: down into little pieces, and the same thing happens in 574 00:30:49,040 --> 00:30:51,400 Speaker 1: nature even without a screen, even without a device, right 575 00:30:51,480 --> 00:30:54,640 Speaker 1: just your eye essentially just gathers all those photons and 576 00:30:54,640 --> 00:30:57,640 Speaker 1: builds an image in your mind. So the second part 577 00:30:57,680 --> 00:31:00,320 Speaker 1: of the question was how does a photon care carry 578 00:31:00,320 --> 00:31:02,720 Speaker 1: within itself a pixel so that we're able to see 579 00:31:02,720 --> 00:31:05,440 Speaker 1: the images we see on our telescopes. We'll remember the 580 00:31:05,440 --> 00:31:08,720 Speaker 1: photons don't carry the pixels. Pixels themselves are a way 581 00:31:08,760 --> 00:31:12,160 Speaker 1: to see photons or way to detect photons. So if 582 00:31:12,200 --> 00:31:15,240 Speaker 1: you think about what happens inside a telescope, these days, 583 00:31:15,320 --> 00:31:17,800 Speaker 1: telescopes are all digital, meaning you have a bunch of 584 00:31:17,880 --> 00:31:20,320 Speaker 1: lenses to gather the light and focus the light, but 585 00:31:20,360 --> 00:31:23,360 Speaker 1: the light in the end is focused onto a digital device, 586 00:31:23,480 --> 00:31:26,920 Speaker 1: a digital camera basically that gathers and measures the amount 587 00:31:26,960 --> 00:31:29,239 Speaker 1: of light. And the way those work is essentially they 588 00:31:29,280 --> 00:31:31,600 Speaker 1: have a bunch of little buckets, and if a photon 589 00:31:31,680 --> 00:31:34,200 Speaker 1: lands in that bucket, then it gets counted, and then 590 00:31:34,240 --> 00:31:37,000 Speaker 1: you just count the number of photons you see, and 591 00:31:37,040 --> 00:31:39,760 Speaker 1: the picture is formed by having the places where more 592 00:31:39,800 --> 00:31:43,240 Speaker 1: photons landed be more intense and the places where fewer 593 00:31:43,280 --> 00:31:46,480 Speaker 1: photons landed be less intense. So you divide up the 594 00:31:46,480 --> 00:31:48,960 Speaker 1: whole space into these buckets, and in each one you 595 00:31:49,000 --> 00:31:52,600 Speaker 1: count how many photons you saw, and that forms your image. 596 00:31:52,720 --> 00:31:54,280 Speaker 1: So that's how you might form like a black and 597 00:31:54,320 --> 00:31:57,040 Speaker 1: white image. If you're just counting the number of photons. 598 00:31:57,320 --> 00:32:01,120 Speaker 1: You don't care what the energy was for any individual photon. 599 00:32:01,400 --> 00:32:04,280 Speaker 1: That's how black and white camera works. We of course, 600 00:32:04,320 --> 00:32:07,000 Speaker 1: are very interested in color photography or color images of 601 00:32:07,040 --> 00:32:09,320 Speaker 1: things that come from space. We want to know not 602 00:32:09,440 --> 00:32:11,720 Speaker 1: just what's there, but how bright is it in red, 603 00:32:11,840 --> 00:32:14,360 Speaker 1: or in green or in blue. So the way that 604 00:32:14,440 --> 00:32:17,320 Speaker 1: works is instead of just having a bunch of individual 605 00:32:17,360 --> 00:32:20,560 Speaker 1: buckets that capture photons regardless of their energy, we have 606 00:32:20,640 --> 00:32:24,000 Speaker 1: different kinds of buckets, just like in your eye, how 607 00:32:24,000 --> 00:32:25,880 Speaker 1: you have different kinds of things in the back of 608 00:32:25,920 --> 00:32:28,560 Speaker 1: your eye, the rods and the cones, some of which 609 00:32:28,560 --> 00:32:30,400 Speaker 1: can capture light and some of which can capture light 610 00:32:30,440 --> 00:32:34,120 Speaker 1: of only specific wavelengths. In the same way, a digital 611 00:32:34,160 --> 00:32:37,640 Speaker 1: camera has different kinds of buckets, buckets with filters over them, 612 00:32:37,840 --> 00:32:41,760 Speaker 1: so they capture light in different wavelengths, different frequencies, different energies. 613 00:32:41,800 --> 00:32:44,240 Speaker 1: All those things are equivalent, and so you'll have like 614 00:32:44,280 --> 00:32:47,840 Speaker 1: a red bucket that only captures reddish photons, or a 615 00:32:47,840 --> 00:32:51,000 Speaker 1: blue bucket that captures things around the blue part of 616 00:32:51,040 --> 00:32:53,520 Speaker 1: the spectrum, and a green one that captures things around 617 00:32:53,600 --> 00:32:56,360 Speaker 1: the green part of the spectrum. In an ideal world, 618 00:32:56,680 --> 00:33:00,440 Speaker 1: For every pixel in your image, you would have a red, green, 619 00:33:00,640 --> 00:33:03,120 Speaker 1: and a blue bucket, so that you could figure out 620 00:33:03,120 --> 00:33:06,240 Speaker 1: afterwards exactly what the color was by combining them back 621 00:33:06,280 --> 00:33:09,200 Speaker 1: from red, green and blue and figuring out exactly what 622 00:33:09,240 --> 00:33:11,520 Speaker 1: the mixture was and telling you what color it is. 623 00:33:12,040 --> 00:33:14,240 Speaker 1: But you can't really have these buckets on top of 624 00:33:14,280 --> 00:33:17,600 Speaker 1: each other. So practically what happens in most digital cameras 625 00:33:18,080 --> 00:33:20,560 Speaker 1: is that for one pixel, you'll only have one kind 626 00:33:20,560 --> 00:33:22,959 Speaker 1: of bucket. So for a certain pixel you might have 627 00:33:23,040 --> 00:33:25,560 Speaker 1: a blue bucket, the next pixel will be only a 628 00:33:25,600 --> 00:33:27,719 Speaker 1: red bucket, and the next one will be only a 629 00:33:27,760 --> 00:33:30,719 Speaker 1: green bucket. And then later when you want to understand 630 00:33:31,000 --> 00:33:33,400 Speaker 1: how much green light is there in a place where 631 00:33:33,400 --> 00:33:36,280 Speaker 1: there was only a red pixel, you don't know because 632 00:33:36,320 --> 00:33:38,160 Speaker 1: you didn't measure it because you didn't have a green 633 00:33:38,200 --> 00:33:41,480 Speaker 1: bucket there. So what they do is they interpolate. They 634 00:33:41,480 --> 00:33:43,520 Speaker 1: say how much green was there over there on the right, 635 00:33:43,560 --> 00:33:45,640 Speaker 1: and how much green was there over there on the left, 636 00:33:45,760 --> 00:33:48,120 Speaker 1: and it figures it out. It guesses how much green 637 00:33:48,160 --> 00:33:51,920 Speaker 1: there might have been. So color photography is much more complicated, 638 00:33:52,040 --> 00:33:55,640 Speaker 1: and even color photography using digital cameras attached to telescopes 639 00:33:56,000 --> 00:33:59,520 Speaker 1: is much more complicated than you might imagine. So that's 640 00:33:59,560 --> 00:34:03,240 Speaker 1: the way that photons carry information that creates the pixels 641 00:34:03,280 --> 00:34:05,600 Speaker 1: we see in our images. Right, they don't carry the pixel. 642 00:34:05,720 --> 00:34:07,719 Speaker 1: They don't show up and say, Hi, you should make 643 00:34:07,760 --> 00:34:10,799 Speaker 1: this pixel a certain amount. The pixels instead add up, 644 00:34:10,840 --> 00:34:15,000 Speaker 1: they integrate over all the photons that they detect. All right, 645 00:34:15,080 --> 00:34:17,960 Speaker 1: wonderful question. And my favorite part is this last bit 646 00:34:18,280 --> 00:34:21,640 Speaker 1: that how do photons not disintegrade after traveling so far? 647 00:34:21,880 --> 00:34:22,040 Speaker 9: Right? 648 00:34:22,080 --> 00:34:24,920 Speaker 1: Because the photons have gone really far away. They might 649 00:34:24,960 --> 00:34:27,360 Speaker 1: have left their star a bis million miles away and 650 00:34:27,440 --> 00:34:31,160 Speaker 1: flown through space for oodles of years before finally landing 651 00:34:31,200 --> 00:34:34,840 Speaker 1: on your telescope or on your eyeball or on that rock. Right, 652 00:34:35,000 --> 00:34:37,360 Speaker 1: think about how many amazing things have happened in the 653 00:34:37,440 --> 00:34:40,080 Speaker 1: universe and the light from them has just been ignored. 654 00:34:40,400 --> 00:34:42,719 Speaker 1: It's just like you know, hit a dog, or hit 655 00:34:42,760 --> 00:34:45,279 Speaker 1: a street light, or just you know, hit the Earth 656 00:34:45,320 --> 00:34:48,640 Speaker 1: when it was daytime so we couldn't even see it anyway. 657 00:34:48,640 --> 00:34:51,120 Speaker 1: The question is how does it not disintegrate? How does 658 00:34:51,120 --> 00:34:53,440 Speaker 1: it last for so long? Well, a photon can go 659 00:34:53,560 --> 00:34:56,200 Speaker 1: forever it has the energy it needs, and it can 660 00:34:56,239 --> 00:34:59,319 Speaker 1: fly through space. If it doesn't hit something. If it 661 00:34:59,360 --> 00:35:02,400 Speaker 1: doesn't bunce into an electron or hit some atmosphere, it 662 00:35:02,440 --> 00:35:06,759 Speaker 1: could literally fly forever. A photon is self sustaining. It's 663 00:35:06,800 --> 00:35:10,160 Speaker 1: this amazing combination of electric fields and magnetic fields that 664 00:35:10,320 --> 00:35:14,000 Speaker 1: slosh back and forth to be completely self sustaining. So 665 00:35:14,120 --> 00:35:16,840 Speaker 1: in an empty universe, if you shot a photon, it 666 00:35:16,840 --> 00:35:21,120 Speaker 1: would fly forever, nothing nothing, but there's nothing there to 667 00:35:21,120 --> 00:35:23,240 Speaker 1: stop it, in the same way that if you pushed 668 00:35:23,280 --> 00:35:26,840 Speaker 1: a ball through space, through empty space, it would fly forever. 669 00:35:27,239 --> 00:35:29,920 Speaker 1: So photons don't get tired. They're happy to fly through 670 00:35:29,920 --> 00:35:33,400 Speaker 1: the whole universe to bring to you pictures from amazing 671 00:35:33,440 --> 00:35:36,080 Speaker 1: and crazy things that are happening super far away. And 672 00:35:36,120 --> 00:35:38,759 Speaker 1: we're glad that they are. We're glad that they get here, 673 00:35:39,000 --> 00:35:42,359 Speaker 1: that they deliver this information into our eyeballs because we 674 00:35:42,400 --> 00:35:45,800 Speaker 1: get to see this beautiful spectacle that is the universe. 675 00:35:46,440 --> 00:35:49,360 Speaker 1: All right. So that was a wonderful listener Questions episode. 676 00:35:49,480 --> 00:35:51,640 Speaker 1: Thank you very much to everybody who wrote in and 677 00:35:51,760 --> 00:35:53,920 Speaker 1: sent us their questions, and to those of you who 678 00:35:53,920 --> 00:35:56,319 Speaker 1: have sent us your recording of your questions but not 679 00:35:56,440 --> 00:35:58,680 Speaker 1: heard yourself yet on the air. Be patient. We will 680 00:35:58,719 --> 00:36:01,239 Speaker 1: get to you. Thanks everybody, for tuning in. I hope 681 00:36:01,239 --> 00:36:04,040 Speaker 1: you enjoyed hearing about traveling at the speed of sound 682 00:36:04,120 --> 00:36:07,440 Speaker 1: and hairy black holes and photons limping their way through 683 00:36:07,440 --> 00:36:10,440 Speaker 1: the universe after billions of miles of journeys, and I 684 00:36:10,480 --> 00:36:12,520 Speaker 1: hope that your journeys take you to a place where 685 00:36:12,520 --> 00:36:16,880 Speaker 1: you can appreciate this incredible, beautiful, but perplexing universe that 686 00:36:16,920 --> 00:36:20,399 Speaker 1: we find ourselves in. Send your questions to Questions at 687 00:36:20,480 --> 00:36:32,480 Speaker 1: Danielandjorge dot com. Thanks for tuning in. If you still 688 00:36:32,480 --> 00:36:35,520 Speaker 1: have a question after listening to all these explanations, please 689 00:36:35,800 --> 00:36:38,080 Speaker 1: drop us a line. We'd love to hear from you. 690 00:36:38,080 --> 00:36:40,959 Speaker 1: You can find us at Facebook, Twitter, and Instagram at 691 00:36:41,239 --> 00:36:44,399 Speaker 1: Daniel and Jorge That's one word, or email us at 692 00:36:44,600 --> 00:36:48,880 Speaker 1: Feedback at Danielandhorge dot com. Thanks for listening, and remember 693 00:36:48,920 --> 00:36:51,720 Speaker 1: that Daniel and Jorge Explain the Universe is a production 694 00:36:51,840 --> 00:36:57,160 Speaker 1: of iHeartRadio. For more podcasts from iHeartRadio, visit the iHeartRadio app, 695 00:36:57,400 --> 00:37:09,080 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows. 696 00:37:10,640 --> 00:37:12,399 Speaker 1: When you pop a piece of cheese into your mouth, 697 00:37:12,400 --> 00:37:15,680 Speaker 1: you're probably not thinking about the environmental impact, but the 698 00:37:15,719 --> 00:37:18,600 Speaker 1: people in the dairy industry are. That's why they're working 699 00:37:18,640 --> 00:37:21,239 Speaker 1: hard every day to find new ways to reduce waste, 700 00:37:21,360 --> 00:37:25,640 Speaker 1: conserve natural resources, and drive down greenhouse gas emissions. House 701 00:37:25,760 --> 00:37:30,120 Speaker 1: US dairy tackling greenhouse gases. Many farms use anaerobic digestors 702 00:37:30,120 --> 00:37:33,440 Speaker 1: to turn the methane from manure into renewable energy that 703 00:37:33,440 --> 00:37:37,080 Speaker 1: can power farms, towns, and electric cars. Visit you as 704 00:37:37,160 --> 00:37:39,920 Speaker 1: dairy dot COM's Last sustainability to learn more. 705 00:37:41,480 --> 00:37:45,000 Speaker 7: There are children, friends, and families walking, riding on passing 706 00:37:45,000 --> 00:37:47,439 Speaker 7: the roads every day. Remember they're real people with loved 707 00:37:47,440 --> 00:37:49,640 Speaker 7: ones who need them to get home safely. Protect our 708 00:37:49,680 --> 00:37:51,759 Speaker 7: cyclists and pedestrians because they're people too. 709 00:37:52,040 --> 00:37:52,560 Speaker 1: Go safely. 710 00:37:52,640 --> 00:37:55,560 Speaker 7: California from the California Office of Traffic Safety and Caltrans. 711 00:37:56,080 --> 00:37:59,320 Speaker 1: We're paint Care and we're all about keeping it simple. 712 00:37:59,800 --> 00:38:03,799 Speaker 1: We make recycling leftover paint easy with convenient locations like 713 00:38:03,800 --> 00:38:06,759 Speaker 1: your local paint store. We have three simple rules for 714 00:38:06,800 --> 00:38:11,760 Speaker 1: painting smarter and reducing waste. One buy only what you need, 715 00:38:12,280 --> 00:38:16,759 Speaker 1: Two use up what you already have, and three recycle 716 00:38:16,840 --> 00:38:21,040 Speaker 1: the rest. Visit paintcare dot org slash three simple rules 717 00:38:21,200 --> 00:38:24,080 Speaker 1: to learn more or find a paint drop off site 718 00:38:24,120 --> 00:38:24,520 Speaker 1: near you.