1 00:00:08,960 --> 00:00:11,280 Speaker 1: Are you the kind of person that wonders if black 2 00:00:11,320 --> 00:00:14,200 Speaker 1: holes have air on them? Do you ever think about 3 00:00:14,280 --> 00:00:16,880 Speaker 1: what it's like to be in a fighter jet and 4 00:00:17,120 --> 00:00:20,520 Speaker 1: roll down the windows. Do you ever wonder if light gets, 5 00:00:20,840 --> 00:00:23,960 Speaker 1: you know, tired, on its way across the universe from 6 00:00:24,120 --> 00:00:27,720 Speaker 1: distant stars all the way to Earth. If so, then 7 00:00:27,920 --> 00:00:30,400 Speaker 1: you're the right person to be listening to this podcast, 8 00:00:30,480 --> 00:00:32,560 Speaker 1: because that's exactly the kind of stuff we're gonna be 9 00:00:32,640 --> 00:00:53,560 Speaker 1: talking about today. Hi. I'm Daniel. I'm a particle physicist, 10 00:00:53,640 --> 00:00:55,640 Speaker 1: and I'm the co author of the book We Have 11 00:00:55,720 --> 00:00:59,640 Speaker 1: No Idea, A Guide to the Unknown Universe. My co author, 12 00:01:00,040 --> 00:01:02,920 Speaker 1: Jorge him is usually the co host of this podcast, 13 00:01:03,240 --> 00:01:06,720 Speaker 1: Daniel and Jorge Explain the Universe, brought to you by 14 00:01:06,720 --> 00:01:10,360 Speaker 1: I Heart Radio. Today, Jorge has to be away, so 15 00:01:10,520 --> 00:01:13,279 Speaker 1: I'm going to do the podcast by myself, and today 16 00:01:13,280 --> 00:01:16,440 Speaker 1: we're doing something which is absolutely my favorite, which is 17 00:01:16,959 --> 00:01:21,319 Speaker 1: answering listener questions. I love listener questions because they give 18 00:01:21,360 --> 00:01:24,080 Speaker 1: me feedback and help me understand what people out there 19 00:01:24,080 --> 00:01:27,480 Speaker 1: are thinking, what they're understanding, and what they're confused about. 20 00:01:28,000 --> 00:01:30,720 Speaker 1: When Jorge and I do lectures live, we talk about 21 00:01:30,720 --> 00:01:33,959 Speaker 1: all the amazing mysteries of the universe, and then people 22 00:01:34,000 --> 00:01:37,920 Speaker 1: ask questions, and those questions are so valuable because they 23 00:01:37,920 --> 00:01:41,479 Speaker 1: show me exactly what people have misunderstood. If I said 24 00:01:41,520 --> 00:01:43,640 Speaker 1: something and I thought I was super clear and then 25 00:01:43,640 --> 00:01:46,240 Speaker 1: somebody asked the question, it helps me see how to 26 00:01:46,400 --> 00:01:50,640 Speaker 1: better explain something. So I really value listener questions. Thank 27 00:01:50,680 --> 00:01:53,640 Speaker 1: you to everybody who has written in, either with a 28 00:01:53,680 --> 00:01:55,760 Speaker 1: point of confusion about something that we said on the 29 00:01:55,760 --> 00:01:59,240 Speaker 1: podcast or something totally crazy that they were thinking about 30 00:01:59,480 --> 00:02:02,240 Speaker 1: and they wanted us to explain. And for all of 31 00:02:02,280 --> 00:02:05,040 Speaker 1: you who have not written into the podcast, what are 32 00:02:05,040 --> 00:02:07,440 Speaker 1: you waiting for? We want to hear your questions. When 33 00:02:07,480 --> 00:02:10,080 Speaker 1: I say I answer every email, I mean it. And 34 00:02:10,080 --> 00:02:12,920 Speaker 1: when I say I love getting questions from listeners, I 35 00:02:13,000 --> 00:02:16,480 Speaker 1: am being totally serious. So please send us your questions 36 00:02:16,480 --> 00:02:19,799 Speaker 1: two questions at Daniel and Jorge dot com. You might 37 00:02:19,840 --> 00:02:22,760 Speaker 1: even hear yourself on the podcast. So today we'll be 38 00:02:22,800 --> 00:02:26,720 Speaker 1: answering listener questions. Questions about lights, questions about black holes, 39 00:02:26,919 --> 00:02:29,360 Speaker 1: questions about flying at the speed of sound with the 40 00:02:29,360 --> 00:02:32,400 Speaker 1: windows open, and all these questions have something in common, 41 00:02:32,440 --> 00:02:34,840 Speaker 1: which is they're sort of like what if questions, like 42 00:02:35,080 --> 00:02:36,799 Speaker 1: how could you do this? Or how could you make 43 00:02:36,840 --> 00:02:39,400 Speaker 1: this work? Or what would happen if you did this thing? 44 00:02:39,919 --> 00:02:43,080 Speaker 1: And all of these reveal people's just desire to understand 45 00:02:43,080 --> 00:02:45,519 Speaker 1: what happens in the universe, to reveal secrets of the 46 00:02:45,600 --> 00:02:49,760 Speaker 1: universe by cooking up crazy scenarios, scenarios where Nature has 47 00:02:49,800 --> 00:02:52,639 Speaker 1: to reveal the truth. And in the end, that's really 48 00:02:52,760 --> 00:02:56,120 Speaker 1: what experimental physics is. We want to know the answer 49 00:02:56,160 --> 00:02:58,680 Speaker 1: to a question, you know, does the universe work this 50 00:02:58,720 --> 00:03:00,880 Speaker 1: way or that way? And so we come up with 51 00:03:00,919 --> 00:03:04,360 Speaker 1: some scenario where nature has to reveal to us the answer. 52 00:03:04,560 --> 00:03:07,520 Speaker 1: We corner nature and say, well, show us you know, 53 00:03:07,560 --> 00:03:09,480 Speaker 1: it is light a particle or is it a wave? 54 00:03:10,080 --> 00:03:12,400 Speaker 1: Does the Higgs boson have this much mass or that 55 00:03:12,480 --> 00:03:16,680 Speaker 1: much mass? Really, all experimental physics is is constructing physical 56 00:03:16,720 --> 00:03:20,000 Speaker 1: scenarios where Nature has to show us her cards. And 57 00:03:20,080 --> 00:03:22,000 Speaker 1: so a lot of the questions you'll hear about today 58 00:03:22,240 --> 00:03:25,200 Speaker 1: are exactly that kind of question. So today we have 59 00:03:25,240 --> 00:03:29,359 Speaker 1: three questions. Let's dive in. Hey, guys, my question is 60 00:03:29,680 --> 00:03:35,120 Speaker 1: what would happen if we quantum entangled two particles and 61 00:03:35,200 --> 00:03:38,320 Speaker 1: took particle one and shot it into a black hole? 62 00:03:39,320 --> 00:03:42,200 Speaker 1: Could we learn anything? And what do you think we 63 00:03:42,320 --> 00:03:47,160 Speaker 1: could learn if we can from particle two. Shout out 64 00:03:47,200 --> 00:03:50,520 Speaker 1: to South Dakota and LEXI. All right, I got this 65 00:03:50,600 --> 00:03:52,600 Speaker 1: question and it blew my mind. And it blew my 66 00:03:52,640 --> 00:03:55,800 Speaker 1: mind because it combines so many different things that I love. 67 00:03:55,960 --> 00:03:59,200 Speaker 1: You've got black holes, you've got quantum mechanics, you got 68 00:03:59,240 --> 00:04:02,240 Speaker 1: inventing new ways to explore the universe. Right, So I 69 00:04:02,320 --> 00:04:05,400 Speaker 1: love when listeners think up new ideas for how we 70 00:04:05,440 --> 00:04:08,440 Speaker 1: could solve ancient questions. All right, so first let's talk 71 00:04:08,480 --> 00:04:11,280 Speaker 1: about why would we want to know what's going on 72 00:04:11,320 --> 00:04:13,680 Speaker 1: inside a black hole? Like, why does anybody care? Isn't 73 00:04:13,720 --> 00:04:16,560 Speaker 1: it just basically the garbage disposal of the universe, jammed 74 00:04:16,600 --> 00:04:20,080 Speaker 1: filled with rejected matter that's got swashed down the toilet 75 00:04:20,080 --> 00:04:22,400 Speaker 1: bowl and into the black hole. Well, that's what we 76 00:04:22,440 --> 00:04:26,280 Speaker 1: don't know. General relativity tells us that black holes might 77 00:04:26,320 --> 00:04:29,159 Speaker 1: have a singularity in the center of them, right, a 78 00:04:29,200 --> 00:04:33,600 Speaker 1: tiny dot of matter with infinite density something, which is, 79 00:04:33,640 --> 00:04:35,760 Speaker 1: you know, hard for us to imagine. What does infinite 80 00:04:35,839 --> 00:04:40,240 Speaker 1: density mean? And but according to Einstein's equations, that's exactly 81 00:04:40,320 --> 00:04:43,640 Speaker 1: the conditions you need to create a black hole. Fine, 82 00:04:43,680 --> 00:04:46,880 Speaker 1: And we know that Einstein's equations have been validated many, 83 00:04:46,920 --> 00:04:49,840 Speaker 1: many times, and nobody's ever found flaw on them. They 84 00:04:49,839 --> 00:04:53,520 Speaker 1: predicted gravitational waves, we've seen them. They predicted all sorts 85 00:04:53,520 --> 00:04:57,680 Speaker 1: of other crazy gravitational phenomena, and they've been verified and checked. So, 86 00:04:57,720 --> 00:05:01,320 Speaker 1: as far as we know, Einstein's equations are correc except 87 00:05:01,920 --> 00:05:05,480 Speaker 1: quantum mechanics tells us that you can't have a singularity 88 00:05:05,480 --> 00:05:08,080 Speaker 1: at the center of a black hole. Remember, quantum mechanics 89 00:05:08,080 --> 00:05:11,760 Speaker 1: tells us the universe is not smooth and continuous, instead 90 00:05:11,800 --> 00:05:15,839 Speaker 1: of the universe is discrete. Space itself is probably pixelated 91 00:05:16,000 --> 00:05:20,279 Speaker 1: into tiny little units. Right, Mass is probably pixelated, time 92 00:05:20,440 --> 00:05:23,719 Speaker 1: is probably pixelated. All these things are probably discreete and 93 00:05:23,720 --> 00:05:27,000 Speaker 1: not continuous, And that means you can't have an infinitely 94 00:05:27,040 --> 00:05:30,040 Speaker 1: small dot, certainly not one with an infinite mass inside 95 00:05:30,040 --> 00:05:32,120 Speaker 1: of it. In addition, there's all sorts of issues about 96 00:05:32,120 --> 00:05:35,240 Speaker 1: the Heisenberg uncertainty principle. Can you have so much matter 97 00:05:35,400 --> 00:05:39,240 Speaker 1: localized in one spot for such a long time. Quantum 98 00:05:39,279 --> 00:05:42,400 Speaker 1: mechanics says that that you should not find a singularity 99 00:05:42,440 --> 00:05:45,039 Speaker 1: inside a black hole. The problem, of course, is it's 100 00:05:45,120 --> 00:05:47,919 Speaker 1: awfully difficult to look inside a black hole. So I 101 00:05:47,920 --> 00:05:50,839 Speaker 1: think that's probably what motivates this question the desire to 102 00:05:50,880 --> 00:05:53,200 Speaker 1: see what's inside a black hole. And I'll be honest, 103 00:05:53,560 --> 00:05:55,479 Speaker 1: if I could see inside a black hole, I would 104 00:05:55,520 --> 00:05:57,240 Speaker 1: do it in a second. I would love to know 105 00:05:57,800 --> 00:06:00,320 Speaker 1: what is going on inside there, all right, it So 106 00:06:00,640 --> 00:06:04,400 Speaker 1: the idea from this question is to quantum entangle two 107 00:06:04,440 --> 00:06:07,680 Speaker 1: particles and shoot one into a black hole, and I 108 00:06:07,720 --> 00:06:09,960 Speaker 1: guess use the other one to sort of learn something 109 00:06:10,040 --> 00:06:13,120 Speaker 1: about what's going on inside the black hole. Right, well, 110 00:06:13,240 --> 00:06:17,200 Speaker 1: let's talk about quantum entanglement. Quantum entanglement is a very 111 00:06:17,200 --> 00:06:19,800 Speaker 1: tricky topic, and we discussed in some depth on our 112 00:06:19,880 --> 00:06:23,479 Speaker 1: quantum Computing episode. The short version is that it links 113 00:06:23,680 --> 00:06:29,000 Speaker 1: two particles potentially across gray distances or great barriers like 114 00:06:29,080 --> 00:06:31,280 Speaker 1: the edge of a black hole. The link is a 115 00:06:31,360 --> 00:06:34,600 Speaker 1: kind of constraint. If one particle spins up, the other 116 00:06:34,600 --> 00:06:37,679 Speaker 1: one has to spin down. So by knowing something about 117 00:06:37,760 --> 00:06:40,839 Speaker 1: one of the particles discovering that it's spin up, for example, 118 00:06:41,120 --> 00:06:43,839 Speaker 1: you can learn something about the other, such as knowing 119 00:06:43,839 --> 00:06:46,719 Speaker 1: that it's spin down, even if you never see it 120 00:06:46,839 --> 00:06:50,359 Speaker 1: or can't possibly see it because it's hidden. So you 121 00:06:50,400 --> 00:06:54,320 Speaker 1: see the attraction for potentially probing a black hole using 122 00:06:54,440 --> 00:06:58,720 Speaker 1: pairs of entangled particles to sort of extract some information 123 00:06:59,040 --> 00:07:02,440 Speaker 1: from one particle by looking at the other one. All right, Well, 124 00:07:02,440 --> 00:07:05,279 Speaker 1: the short answer is we would learn nothing, And the 125 00:07:05,320 --> 00:07:08,240 Speaker 1: reason is that there are pretty solid theorems about getting 126 00:07:08,279 --> 00:07:11,440 Speaker 1: information out of the black hole. All right, So the 127 00:07:11,640 --> 00:07:14,960 Speaker 1: no hair theorem, I'm not joking. It's literally called the 128 00:07:15,000 --> 00:07:17,280 Speaker 1: no hair theorem, and I don't know if it was 129 00:07:17,320 --> 00:07:20,520 Speaker 1: invented by a business without hair, but the no hair 130 00:07:20,600 --> 00:07:23,679 Speaker 1: theorem says that the only information you can get about 131 00:07:23,680 --> 00:07:27,720 Speaker 1: a black hole is its mass, it's total electric charge, 132 00:07:28,000 --> 00:07:31,640 Speaker 1: and its momentum. That's it, right. You can't get any 133 00:07:31,680 --> 00:07:35,320 Speaker 1: other information. Nothing that's going on inside the black hole 134 00:07:35,360 --> 00:07:38,560 Speaker 1: can never leave, right, certainly can't see things escaping the 135 00:07:38,600 --> 00:07:41,240 Speaker 1: black hole. Nothing can escape, so no light can come 136 00:07:41,280 --> 00:07:43,600 Speaker 1: out to reveal to you what's inside the black hole. 137 00:07:43,840 --> 00:07:46,360 Speaker 1: But more than that, you cannot get any information, no 138 00:07:46,400 --> 00:07:49,800 Speaker 1: matter how clever you are, other than those three pieces 139 00:07:49,800 --> 00:07:53,360 Speaker 1: of information. And this raises all sorts of fascinating questions, 140 00:07:53,400 --> 00:07:57,080 Speaker 1: Like um, the listener was asking about quantum entangled particles 141 00:07:57,080 --> 00:07:59,320 Speaker 1: where one is inside and one is outside the black hole. 142 00:07:59,560 --> 00:08:03,480 Speaker 1: That act really happens already. There's something called hawking radiation 143 00:08:03,920 --> 00:08:06,960 Speaker 1: or a photon inside the black hole will decay to 144 00:08:07,120 --> 00:08:10,520 Speaker 1: two quantum entangled particles, and the decay will happen so 145 00:08:10,640 --> 00:08:13,560 Speaker 1: close to the event horizon that one of the particles 146 00:08:13,600 --> 00:08:16,320 Speaker 1: slips out of the event horizon and gets to leave. 147 00:08:16,560 --> 00:08:20,800 Speaker 1: That's Hawking radiation and requires this quantum fluctuation right right 148 00:08:20,840 --> 00:08:22,840 Speaker 1: at the edge of the event horizon. And so you 149 00:08:22,920 --> 00:08:26,520 Speaker 1: might ask, can we learn something about the side of 150 00:08:26,600 --> 00:08:29,680 Speaker 1: the Hawking radiation that got slurred into the black hole 151 00:08:29,960 --> 00:08:32,800 Speaker 1: by looking at what happens outside the black hole by 152 00:08:32,840 --> 00:08:36,360 Speaker 1: measuring that Hawking radiation. Well, the answer is no, right, 153 00:08:36,480 --> 00:08:39,280 Speaker 1: no information can leave the black hole. Is just impossible 154 00:08:39,320 --> 00:08:42,360 Speaker 1: to extract any information. Even though that electron and that 155 00:08:42,400 --> 00:08:45,520 Speaker 1: positron are entangled with each other, right, they do not 156 00:08:45,640 --> 00:08:49,480 Speaker 1: contain any information about what's going on inside the black hole. 157 00:08:49,720 --> 00:08:51,640 Speaker 1: And the shorter answer is, as soon as you're trying 158 00:08:51,640 --> 00:08:55,199 Speaker 1: to interact with the electron impositron, you will anyway break 159 00:08:55,240 --> 00:08:58,680 Speaker 1: that entanglement. Right. The entanglement only exists when those particles 160 00:08:58,679 --> 00:09:01,480 Speaker 1: are isolated from the to the system. So as soon 161 00:09:01,520 --> 00:09:03,920 Speaker 1: as you trying to measure something about that electron, you're 162 00:09:03,960 --> 00:09:07,040 Speaker 1: probably going to break that entanglement anyway, which is usually 163 00:09:07,480 --> 00:09:10,400 Speaker 1: usually the problem with entanglement is that you can't really 164 00:09:10,440 --> 00:09:13,520 Speaker 1: use it to convey information because interacting with the particles 165 00:09:13,760 --> 00:09:17,680 Speaker 1: breaks that entanglement. All Right, This brings us to another 166 00:09:17,840 --> 00:09:21,080 Speaker 1: fascinating and current topic in black hole physics, which is 167 00:09:21,360 --> 00:09:25,960 Speaker 1: people are wondering where the information goes. Like, according to 168 00:09:26,080 --> 00:09:29,600 Speaker 1: black hole theories, no information can leave the black hole, right, 169 00:09:30,040 --> 00:09:34,880 Speaker 1: But according to Hawking, radiation particles do escape the black hole, 170 00:09:34,920 --> 00:09:37,040 Speaker 1: which means the black hole can shrink. In fact, for 171 00:09:37,120 --> 00:09:40,800 Speaker 1: small black holes, black holes could even evaporate and disappear. 172 00:09:41,559 --> 00:09:44,839 Speaker 1: So what happens to the information that went into the 173 00:09:44,880 --> 00:09:48,079 Speaker 1: black hole? What happened to all that quant those quantum 174 00:09:48,080 --> 00:09:50,079 Speaker 1: states and all that stuff that went into the black 175 00:09:50,080 --> 00:09:53,920 Speaker 1: hole and then the black hole disappeared? Because there's another 176 00:09:54,040 --> 00:09:56,800 Speaker 1: law of quantum mechanics that says It says that all 177 00:09:56,840 --> 00:09:59,520 Speaker 1: the information about past states in the universe is contained 178 00:09:59,559 --> 00:10:02,880 Speaker 1: in the ragement of the current universe, right, no information 179 00:10:02,920 --> 00:10:06,760 Speaker 1: should be lost. For those mathematically inclined, this means essentially 180 00:10:06,920 --> 00:10:09,840 Speaker 1: that the wave function is unitary, right. The transformations through 181 00:10:09,880 --> 00:10:13,559 Speaker 1: times do not change the overall normalization of the wave function. 182 00:10:14,280 --> 00:10:18,200 Speaker 1: So if black holes can evaporate and disappear, but no 183 00:10:18,280 --> 00:10:22,360 Speaker 1: information can leave the black hole. That suggests that information 184 00:10:22,440 --> 00:10:25,600 Speaker 1: is destroyed, and that particular puzzle goes by the name 185 00:10:25,640 --> 00:10:29,240 Speaker 1: of the black hole information paradox. And people have proposed 186 00:10:29,280 --> 00:10:32,400 Speaker 1: all sorts of crazy solutions to this, including firewalls and 187 00:10:32,440 --> 00:10:35,480 Speaker 1: all sorts of crazy stuff that we might actually see 188 00:10:35,520 --> 00:10:38,360 Speaker 1: at the edges of black holes one day. So thank 189 00:10:38,400 --> 00:10:41,560 Speaker 1: you for this wonderful question about black holes and quantum 190 00:10:41,559 --> 00:10:45,360 Speaker 1: mechanics and entanglement and information and all sorts of crazy, 191 00:10:45,360 --> 00:10:47,760 Speaker 1: amazing stuff. One of my favorite things about these kinds 192 00:10:47,760 --> 00:10:51,480 Speaker 1: of questions is that they seem theoretical, they seem crazy abstract, 193 00:10:51,720 --> 00:10:54,840 Speaker 1: but these are real, like black holes, they're real objects. 194 00:10:54,920 --> 00:10:57,559 Speaker 1: They are out there, and one day, if we build 195 00:10:57,600 --> 00:10:59,520 Speaker 1: the right kind of spaceship and the right kind of probes, 196 00:10:59,600 --> 00:11:01,080 Speaker 1: we could go when we could observe them, and we 197 00:11:01,160 --> 00:11:04,120 Speaker 1: might learn the answers to some of these questions. So 198 00:11:04,200 --> 00:11:07,120 Speaker 1: thanks for sending in that question, and keep writing. Well, 199 00:11:07,280 --> 00:11:09,280 Speaker 1: this is a perfect spot to take a break. We'll 200 00:11:09,280 --> 00:11:24,959 Speaker 1: be right back. This is a wonderful question that we 201 00:11:25,040 --> 00:11:28,959 Speaker 1: got recently from a listener and from that listener's dad. Hi, 202 00:11:29,120 --> 00:11:32,360 Speaker 1: my name is Phineas, and I'm in fourth grade and 203 00:11:32,400 --> 00:11:35,440 Speaker 1: I live in Sico, Alaska. I was wondering, if you 204 00:11:35,440 --> 00:11:37,640 Speaker 1: were in an airplane going faster on the speed of 205 00:11:37,679 --> 00:11:40,480 Speaker 1: sound and you said something to the person next to you, 206 00:11:40,800 --> 00:11:43,079 Speaker 1: would they actually be able to hear what you said. 207 00:11:44,000 --> 00:11:47,080 Speaker 1: This is Phineas's dad. Phineas asked me this question a 208 00:11:47,080 --> 00:11:50,520 Speaker 1: while ago, and it got me wondering if one was 209 00:11:50,600 --> 00:11:54,439 Speaker 1: traveling at or above the speed of light, would they 210 00:11:54,480 --> 00:11:57,480 Speaker 1: be able to see the person next to them? So 211 00:11:57,559 --> 00:12:00,440 Speaker 1: I love this question for so many reasons. I love 212 00:12:00,480 --> 00:12:03,040 Speaker 1: that that young boys imagining what it's like to be 213 00:12:03,080 --> 00:12:05,240 Speaker 1: on a spaceship or what it's like to be on 214 00:12:05,280 --> 00:12:08,319 Speaker 1: a plane traveling past the speed of sound. And it's 215 00:12:08,320 --> 00:12:12,200 Speaker 1: a great question. He's wondering about how this information is processed, 216 00:12:12,200 --> 00:12:15,360 Speaker 1: how this information is transmitted. Essentially, are you leaving that 217 00:12:15,480 --> 00:12:18,719 Speaker 1: information behind right? Well, first of all, I want to 218 00:12:18,720 --> 00:12:21,120 Speaker 1: break his bubble and say, if you're on a fighter 219 00:12:21,200 --> 00:12:24,480 Speaker 1: jet that's traveling faster than the speed of sound, probably 220 00:12:24,559 --> 00:12:27,320 Speaker 1: you don't have the windows open, right, which means that 221 00:12:27,360 --> 00:12:29,800 Speaker 1: you're in a little air bubble. That air bubble is 222 00:12:29,840 --> 00:12:32,960 Speaker 1: moving with you fast in the speed of sound. If 223 00:12:33,000 --> 00:12:35,680 Speaker 1: you had the windows open and the air was rushing 224 00:12:35,720 --> 00:12:38,760 Speaker 1: past you fasten the speed of sound, it would probably 225 00:12:38,800 --> 00:12:42,120 Speaker 1: tear you to shreds. And that's why fighter jets, for example, 226 00:12:42,240 --> 00:12:45,360 Speaker 1: have that little bubble right the window that protects them 227 00:12:45,600 --> 00:12:48,520 Speaker 1: from what's going on outside. All right, so they have 228 00:12:48,559 --> 00:12:51,240 Speaker 1: a little bubble of air. And that's the key, because 229 00:12:51,320 --> 00:12:55,640 Speaker 1: sound is a wave, right, Sound is just vibrations of 230 00:12:55,679 --> 00:12:58,360 Speaker 1: the air, and so what it does is it moves 231 00:12:58,880 --> 00:13:01,480 Speaker 1: relative to the air. Right. It's like if you have 232 00:13:01,520 --> 00:13:04,560 Speaker 1: a bathtub of water and you're slapping it to make 233 00:13:04,760 --> 00:13:07,640 Speaker 1: to make waves, the waves move relative to the water. 234 00:13:08,280 --> 00:13:11,040 Speaker 1: If that water, if that bathtub was on a train 235 00:13:11,400 --> 00:13:14,880 Speaker 1: traveling a super duper fast, it wouldn't make any difference, Right, 236 00:13:14,920 --> 00:13:16,880 Speaker 1: You could still have a bath and you can still 237 00:13:16,880 --> 00:13:19,680 Speaker 1: make splashes and they wouldn't be any different. In the 238 00:13:19,760 --> 00:13:22,320 Speaker 1: same way, if you're on a fighter jet and you're 239 00:13:22,320 --> 00:13:24,880 Speaker 1: in a little bubble of air inside the fighter jet, 240 00:13:25,240 --> 00:13:26,920 Speaker 1: you can turn to the person next to you, can 241 00:13:26,960 --> 00:13:30,079 Speaker 1: say hello, would you please pass the peanuts or whatever 242 00:13:30,120 --> 00:13:32,080 Speaker 1: you say to somebody in a fighter jet, and the 243 00:13:32,240 --> 00:13:35,560 Speaker 1: air between you is not moving relative to you, so 244 00:13:35,600 --> 00:13:38,480 Speaker 1: you can send waves through it normally, just as you 245 00:13:38,520 --> 00:13:40,719 Speaker 1: would if you were sitting on your couch in your 246 00:13:40,720 --> 00:13:43,280 Speaker 1: living room. So the sort of cheap answer to the 247 00:13:43,360 --> 00:13:46,480 Speaker 1: question is that there's no difference if you're in a 248 00:13:46,480 --> 00:13:49,120 Speaker 1: little bubble of air that's moving with you, all right, 249 00:13:49,240 --> 00:13:52,440 Speaker 1: So that's no fun. Let's imagine what happens when you 250 00:13:52,480 --> 00:13:56,200 Speaker 1: open the windows, right, You're going mocked too, You're zooming 251 00:13:56,240 --> 00:13:58,960 Speaker 1: through the atmosphere. You open the windows, all of a sudden, 252 00:13:59,000 --> 00:14:01,520 Speaker 1: the wind is screaming past you with two thousand miles 253 00:14:01,559 --> 00:14:04,920 Speaker 1: per hour. Right now, that's an interesting question. What happens 254 00:14:04,920 --> 00:14:06,839 Speaker 1: if you turn to your friend and you say, past 255 00:14:06,880 --> 00:14:10,040 Speaker 1: the bananas? Right? Can they hear you? The key thing 256 00:14:10,080 --> 00:14:13,360 Speaker 1: to remember is that sound moves at a fixed speed 257 00:14:13,720 --> 00:14:16,840 Speaker 1: relative to the air. So if you shout into a 258 00:14:16,920 --> 00:14:20,080 Speaker 1: wind blowing at your back, then your show gets carried 259 00:14:20,120 --> 00:14:22,760 Speaker 1: away from you by the wind more quickly than if 260 00:14:22,760 --> 00:14:26,480 Speaker 1: there had been no wind. Similarly, if the wind is 261 00:14:26,520 --> 00:14:29,640 Speaker 1: blowing in your face, it can slow down your shout. 262 00:14:30,120 --> 00:14:32,120 Speaker 1: If the wind blows in your face at the speed 263 00:14:32,120 --> 00:14:36,360 Speaker 1: of sound, ouch, then when you scream, your scream doesn't 264 00:14:36,440 --> 00:14:39,640 Speaker 1: actually go anywhere. It stays right there on top of you. 265 00:14:40,360 --> 00:14:43,320 Speaker 1: So in the fighter jet, if the windshield is down 266 00:14:43,400 --> 00:14:45,320 Speaker 1: or whatever they call it in a fighter jet, then 267 00:14:45,360 --> 00:14:47,480 Speaker 1: they can just talk normally right there in a bubble 268 00:14:47,520 --> 00:14:49,560 Speaker 1: of air. Just like if you're in a bathtub and 269 00:14:49,560 --> 00:14:51,640 Speaker 1: you make waves. It doesn't matter if you're on a 270 00:14:51,680 --> 00:14:54,160 Speaker 1: train at the time, because the water is moving with you. 271 00:14:54,760 --> 00:14:57,960 Speaker 1: But if they open the windshield, the wind is whipping 272 00:14:58,000 --> 00:15:00,200 Speaker 1: by them at faster than the speed of so sound, 273 00:15:00,440 --> 00:15:04,280 Speaker 1: and so they will leave their words behind. There's no 274 00:15:04,360 --> 00:15:07,120 Speaker 1: way that they can talk, even if they shout straightforwards. 275 00:15:07,360 --> 00:15:10,240 Speaker 1: This is also why planes make sonic booms. If a 276 00:15:10,240 --> 00:15:13,240 Speaker 1: plane is traveling faster than the sound it's making, then 277 00:15:13,280 --> 00:15:16,680 Speaker 1: it's catching up to his own sound, and the sound 278 00:15:16,680 --> 00:15:18,960 Speaker 1: from two seconds ago gets piled up on top of 279 00:15:18,960 --> 00:15:21,240 Speaker 1: the sound from one second ago and the sound from 280 00:15:21,360 --> 00:15:24,520 Speaker 1: right now. It's the same amount of sound total, doesn't 281 00:15:24,560 --> 00:15:28,360 Speaker 1: generate more sound, but it gets concentrated in certain places 282 00:15:28,560 --> 00:15:31,240 Speaker 1: because the plane is out racing the sound it's making. 283 00:15:31,760 --> 00:15:33,840 Speaker 1: Just like with a boat in the water, if it 284 00:15:33,920 --> 00:15:37,080 Speaker 1: travels faster than the waves in water, then those waves 285 00:15:37,120 --> 00:15:39,480 Speaker 1: pile up and you get a wake. A sonic boom 286 00:15:39,520 --> 00:15:43,920 Speaker 1: is just a plane's wake. Alright, awesome question, and my 287 00:15:44,000 --> 00:15:46,680 Speaker 1: favorite part I think of this is that his dad 288 00:15:46,760 --> 00:15:51,160 Speaker 1: couldn't help but jump in and ask even more physics equestion, right, 289 00:15:51,240 --> 00:15:54,320 Speaker 1: a question about traveling at or faster than the speed 290 00:15:54,360 --> 00:15:57,840 Speaker 1: of light. Wonderful and I love this because it allows 291 00:15:57,920 --> 00:16:00,400 Speaker 1: us to draw this contrast between the speed of sound 292 00:16:00,440 --> 00:16:02,600 Speaker 1: and the speed of light. Now, first of all, of course, 293 00:16:03,040 --> 00:16:06,040 Speaker 1: you can't travel at the speed of light, right, Nothing 294 00:16:06,080 --> 00:16:08,600 Speaker 1: that has mass can travel at the speed of light. 295 00:16:09,240 --> 00:16:12,160 Speaker 1: Only things that are massless travel at the speed of light, 296 00:16:12,520 --> 00:16:17,920 Speaker 1: and everything that's massless travels at the speed of light. Photons, gravitons, 297 00:16:18,000 --> 00:16:21,360 Speaker 1: if they exist, anything that does not have mass has 298 00:16:21,400 --> 00:16:24,080 Speaker 1: to travel at the speed of light, and always at 299 00:16:24,120 --> 00:16:28,119 Speaker 1: the speed of light. Can't go any slower. The amazing 300 00:16:28,160 --> 00:16:31,040 Speaker 1: thing about photons is not only that they travel at 301 00:16:31,040 --> 00:16:33,000 Speaker 1: the speed of light, which is super dup or fast, 302 00:16:33,480 --> 00:16:37,160 Speaker 1: but that they don't travel relative to some medium. Sound 303 00:16:37,200 --> 00:16:40,360 Speaker 1: and water waves travel it's fixed speeds relative to their 304 00:16:40,440 --> 00:16:44,200 Speaker 1: medium air or water, but the rules are totally different. 305 00:16:44,240 --> 00:16:47,240 Speaker 1: For light. It's a wave, but it always moves at 306 00:16:47,280 --> 00:16:50,040 Speaker 1: the speed of light relative to the person measuring it, 307 00:16:50,520 --> 00:16:55,120 Speaker 1: not relative to the medium, because it doesn't have a medium. Now, 308 00:16:55,160 --> 00:16:57,600 Speaker 1: for a while people thought that there has to be 309 00:16:57,680 --> 00:16:59,840 Speaker 1: some medium that light traveled through, and they called it 310 00:17:00,080 --> 00:17:02,800 Speaker 1: ether and searched for it. But now we know that 311 00:17:02,840 --> 00:17:06,160 Speaker 1: there is no ether, no medium that's doing the waving 312 00:17:06,280 --> 00:17:09,520 Speaker 1: for light like air does for sound. The Michaelson Morley 313 00:17:09,600 --> 00:17:12,359 Speaker 1: experiments showed us that because they measured the speed of 314 00:17:12,440 --> 00:17:15,920 Speaker 1: light in two different directions and found them to be identical, 315 00:17:16,240 --> 00:17:18,880 Speaker 1: even though the Earth is obviously moving in one direction 316 00:17:18,960 --> 00:17:21,240 Speaker 1: or the other as it goes around the Sun. The 317 00:17:21,280 --> 00:17:24,159 Speaker 1: reason is because light doesn't have a medium. It's the 318 00:17:24,200 --> 00:17:27,800 Speaker 1: waving of quantum fields that are the properties of space itself. 319 00:17:28,119 --> 00:17:31,120 Speaker 1: So space can be empty and still have light in it. 320 00:17:31,280 --> 00:17:33,080 Speaker 1: And the way we showed it is that we discovered 321 00:17:33,119 --> 00:17:37,000 Speaker 1: that light moves at the speed of light relative to everybody, 322 00:17:37,040 --> 00:17:40,000 Speaker 1: no matter how fast you're going. So if you are 323 00:17:40,080 --> 00:17:43,240 Speaker 1: standing on Earth and you turn on a flashlight, those 324 00:17:43,280 --> 00:17:48,120 Speaker 1: photons leave your flashlight at the speed of light. Right cool. Now, 325 00:17:48,160 --> 00:17:51,640 Speaker 1: what happens if you jump into Lamborghini and you turn 326 00:17:51,680 --> 00:17:54,760 Speaker 1: on a flashlight. Lamborghini is going to two miles per hour. 327 00:17:55,440 --> 00:17:58,760 Speaker 1: You're in the Lamborghini, you turn on the flashlight. What happens, Well, 328 00:17:58,920 --> 00:18:01,240 Speaker 1: the light leaves your fly light at the speed of 329 00:18:01,320 --> 00:18:05,240 Speaker 1: light relative to you, No big deal. What about somebody 330 00:18:05,240 --> 00:18:07,439 Speaker 1: on the ground, right, the person you left behind who 331 00:18:07,520 --> 00:18:10,920 Speaker 1: you didn't offer a ride in your Lamborghini too? When 332 00:18:11,000 --> 00:18:13,280 Speaker 1: they when you turn on the flashlight in your Lamborghini, 333 00:18:13,560 --> 00:18:16,119 Speaker 1: how fast did they see the light going? Well, you 334 00:18:16,160 --> 00:18:18,600 Speaker 1: might think, well, it's the speed of light plus the 335 00:18:18,640 --> 00:18:21,800 Speaker 1: speed of the Lamborghini, right, because the flashlight itself is 336 00:18:21,840 --> 00:18:25,800 Speaker 1: moving at two hundred miles. But that's where you'd be wrong. Right, 337 00:18:25,880 --> 00:18:28,880 Speaker 1: That's whyw light is weird. That's how our whole universe 338 00:18:28,960 --> 00:18:32,480 Speaker 1: is super bizarre. Frankly, it's bonkers. But we know that 339 00:18:32,600 --> 00:18:35,440 Speaker 1: light always travels at the speed of light, no matter 340 00:18:35,560 --> 00:18:38,040 Speaker 1: what the speed of the thing making it is, right, 341 00:18:38,080 --> 00:18:41,480 Speaker 1: And everybody who measures the speed of light always sees 342 00:18:41,560 --> 00:18:44,440 Speaker 1: it moving at the speed of light relative to them. 343 00:18:44,480 --> 00:18:47,359 Speaker 1: And that's different from sound, right. Sound travels relative to 344 00:18:47,400 --> 00:18:50,280 Speaker 1: a medium like air, and that's sort of an absolute 345 00:18:50,320 --> 00:18:53,159 Speaker 1: reference frame. And sound always moves at the same speed 346 00:18:53,200 --> 00:18:55,639 Speaker 1: relative to the air. And so if you're moving with 347 00:18:55,680 --> 00:18:57,520 Speaker 1: respect of the air, like you're in a fighter jet, 348 00:18:57,640 --> 00:18:59,520 Speaker 1: and you're moving at the speed of sound, if you 349 00:18:59,640 --> 00:19:02,760 Speaker 1: screen sam, then you're moving with that sound. Right. So 350 00:19:02,800 --> 00:19:05,480 Speaker 1: if you scream in a fighter jet and you're moving 351 00:19:05,480 --> 00:19:07,280 Speaker 1: at the speed of sound, you can basically just like 352 00:19:07,440 --> 00:19:10,760 Speaker 1: stay inside your scream. You can fly along through the 353 00:19:10,840 --> 00:19:14,160 Speaker 1: air with your scream. That's not true with light, right, 354 00:19:14,240 --> 00:19:16,640 Speaker 1: Light will always move at the speed of light relative 355 00:19:16,680 --> 00:19:19,520 Speaker 1: to you. You turn on that flashlight, even if you 356 00:19:19,560 --> 00:19:21,720 Speaker 1: were traveling very close to the speed of light, you 357 00:19:21,760 --> 00:19:24,880 Speaker 1: couldn't stay with those photons. It would leave you at 358 00:19:24,920 --> 00:19:27,800 Speaker 1: the speed of light. And so if you're traveling very 359 00:19:27,800 --> 00:19:29,560 Speaker 1: close to the speed of light, because you can't travel 360 00:19:29,720 --> 00:19:32,840 Speaker 1: at the speed of light, and you look next to you, right, 361 00:19:33,080 --> 00:19:35,720 Speaker 1: and the person next to you has a flashlight, it's 362 00:19:35,720 --> 00:19:39,080 Speaker 1: going to act totally normally for you, right, It doesn't 363 00:19:39,119 --> 00:19:42,680 Speaker 1: matter what's happening outside. Light always travels at the speed 364 00:19:42,720 --> 00:19:45,200 Speaker 1: of light relative to you. So the short I answer 365 00:19:45,200 --> 00:19:48,639 Speaker 1: to your question is, if you're traveling nearly at the 366 00:19:48,640 --> 00:19:52,320 Speaker 1: speed of light, then everything will feel normal inside your spaceship. 367 00:19:52,560 --> 00:19:55,280 Speaker 1: Clocks will run normally. Everything will seem normal. Now if 368 00:19:55,280 --> 00:19:57,440 Speaker 1: you look outside your spaceship, but things that are not 369 00:19:57,560 --> 00:20:00,520 Speaker 1: traveling at that high speed, that's when relative he kicks in. 370 00:20:01,000 --> 00:20:04,040 Speaker 1: Things seem to run slow and they seem to get shrunk. Right, 371 00:20:04,359 --> 00:20:07,840 Speaker 1: But light always travels at the same speed no matter what. 372 00:20:09,520 --> 00:20:11,520 Speaker 1: I hope that was an answer to your question. Thank 373 00:20:11,560 --> 00:20:14,040 Speaker 1: you so much for writing in, Thank you for wondering 374 00:20:14,080 --> 00:20:16,280 Speaker 1: about the universe, and thank you to all the parents 375 00:20:16,280 --> 00:20:19,680 Speaker 1: out there who are sharing their wonderings about the universe 376 00:20:19,720 --> 00:20:22,399 Speaker 1: with their kids and sharing this podcast with their kids 377 00:20:22,760 --> 00:20:26,479 Speaker 1: and letting their kids ask us crazy, awesome, amazing, super 378 00:20:26,560 --> 00:20:30,800 Speaker 1: fun questions about the universe that we totally love to answer. 379 00:20:31,000 --> 00:20:33,720 Speaker 1: Let's get to our last question, but first, let's take 380 00:20:33,720 --> 00:20:49,879 Speaker 1: a break. Okay, we're back and we're answering listener questions. 381 00:20:49,920 --> 00:20:52,359 Speaker 1: Today we talked about zooming around at the speed of 382 00:20:52,400 --> 00:20:54,840 Speaker 1: sound with the speed of light, and we talked about 383 00:20:54,960 --> 00:20:58,199 Speaker 1: quantum entanglement and black holes, and our last question is 384 00:20:58,240 --> 00:21:01,720 Speaker 1: also related to light and zoom across the universe. Here 385 00:21:01,720 --> 00:21:04,600 Speaker 1: it is Hello, Daniel and Jorge. Hey, my name is 386 00:21:04,640 --> 00:21:07,760 Speaker 1: Marcella and I'm forming a Jeanette Brazil. I'm a big 387 00:21:07,800 --> 00:21:10,840 Speaker 1: fan of your podcast and your book. So my question 388 00:21:10,880 --> 00:21:14,960 Speaker 1: is about how does light carry information or how exactly 389 00:21:15,040 --> 00:21:19,520 Speaker 1: does a photon transmit or carry within itself a pixel 390 00:21:19,600 --> 00:21:21,879 Speaker 1: so that we are able to see the images we 391 00:21:21,960 --> 00:21:25,800 Speaker 1: see on our telescopes. How does it not disintegrate after 392 00:21:25,840 --> 00:21:30,120 Speaker 1: traveling so far. Thank you so much. All right, that's 393 00:21:30,160 --> 00:21:32,920 Speaker 1: not really one question. That's like a bunch of questions 394 00:21:32,920 --> 00:21:36,240 Speaker 1: I'll stuck together but totally fair will answer all of them. 395 00:21:36,280 --> 00:21:39,320 Speaker 1: The first part of the question was essentially what information 396 00:21:39,359 --> 00:21:41,800 Speaker 1: does light carry? And I think the question is trying 397 00:21:41,840 --> 00:21:44,480 Speaker 1: to ask, like, when you see a picture of like 398 00:21:44,520 --> 00:21:47,840 Speaker 1: a distant star, what is it that the photon is carrying? 399 00:21:47,840 --> 00:21:50,159 Speaker 1: How does it how does that picture come from the 400 00:21:50,200 --> 00:21:53,840 Speaker 1: star and end up in my eyeballs or in my telescope. First, 401 00:21:53,880 --> 00:21:57,160 Speaker 1: let's be really microscopic about it, right, What happens when 402 00:21:57,200 --> 00:21:59,680 Speaker 1: you see a star is that you're seeing photons from 403 00:21:59,720 --> 00:22:03,840 Speaker 1: that star. So somewhere really far away, billions of miles away, 404 00:22:03,880 --> 00:22:06,760 Speaker 1: that big ball of fusion is shooting out photons. And 405 00:22:06,800 --> 00:22:09,119 Speaker 1: once the photons leave the star, they have nothing to 406 00:22:09,119 --> 00:22:11,679 Speaker 1: do with the star anymore. Right, they're flying through space 407 00:22:11,720 --> 00:22:13,720 Speaker 1: and the fact that they came from the star is irrelevant. 408 00:22:13,960 --> 00:22:18,359 Speaker 1: But they do carry information. They're pointing in a specific direction. Right. 409 00:22:18,400 --> 00:22:21,360 Speaker 1: That's information. If you see light coming from one direction 410 00:22:21,480 --> 00:22:24,239 Speaker 1: or another left versus right, it tells you where that 411 00:22:24,320 --> 00:22:27,640 Speaker 1: object is. Right, So where in the sky the light 412 00:22:27,720 --> 00:22:30,520 Speaker 1: is coming from is very important information to know where 413 00:22:30,560 --> 00:22:33,440 Speaker 1: that star might be. So first piece of information light 414 00:22:33,520 --> 00:22:37,879 Speaker 1: carries is its direction. Second very important piece of information 415 00:22:38,000 --> 00:22:41,639 Speaker 1: is its energy. Every photon has a certain amount of energy, 416 00:22:41,800 --> 00:22:43,879 Speaker 1: and this is the critical thing about photon. This is 417 00:22:43,920 --> 00:22:47,000 Speaker 1: the reason we know photons exist, is that light comes 418 00:22:47,000 --> 00:22:49,359 Speaker 1: in these little packets of energy. That's basically what a 419 00:22:49,400 --> 00:22:53,359 Speaker 1: photon is. And the specific energy that a photon has 420 00:22:53,400 --> 00:22:58,440 Speaker 1: also determines its frequency. Remember, photons their particles, their waves, 421 00:22:58,560 --> 00:23:00,280 Speaker 1: but when you think about them as way, you have 422 00:23:00,359 --> 00:23:03,639 Speaker 1: to think about them as sort of electromagnetic fluctuations, like 423 00:23:03,800 --> 00:23:08,520 Speaker 1: vibrations in the electromagnetic field. Those vibrations have a certain frequency, 424 00:23:08,880 --> 00:23:11,440 Speaker 1: and you probably heard of visible light having frequencies in 425 00:23:11,480 --> 00:23:14,760 Speaker 1: the range of hundreds of nanometers. So every photon has 426 00:23:14,800 --> 00:23:17,560 Speaker 1: a certain amount of energy. That energy determines a few 427 00:23:17,640 --> 00:23:20,679 Speaker 1: things about the photon. It determines the frequency of the 428 00:23:20,720 --> 00:23:24,440 Speaker 1: wiggles because remember photons are just electromagnetic waves and they're 429 00:23:24,440 --> 00:23:28,520 Speaker 1: wiggling along through space their vibrations in the electromagnetic field 430 00:23:28,640 --> 00:23:30,919 Speaker 1: or the quantum photon field, if you want to think 431 00:23:30,960 --> 00:23:33,480 Speaker 1: about it in terms of quantum field theory. So it 432 00:23:33,480 --> 00:23:38,400 Speaker 1: determines its frequency and also its wavelength, and in addition, 433 00:23:38,720 --> 00:23:41,680 Speaker 1: those things determine the photons color. But color, of course, 434 00:23:41,760 --> 00:23:43,960 Speaker 1: is something even more complicated. We're gonna have a whole 435 00:23:43,960 --> 00:23:47,000 Speaker 1: episode about that soon what it means to see different colors. 436 00:23:47,200 --> 00:23:50,720 Speaker 1: But essentially, the energy carries all this information. So so 437 00:23:50,760 --> 00:23:53,480 Speaker 1: far we have a photon zooming through space, and it's 438 00:23:53,600 --> 00:23:56,920 Speaker 1: carrying information about its direction, and it's carrying information about 439 00:23:56,920 --> 00:23:59,520 Speaker 1: the energy, and that's most of the information you need 440 00:23:59,560 --> 00:24:02,080 Speaker 1: from a poton. If you think about all the photons 441 00:24:02,119 --> 00:24:04,800 Speaker 1: coming off the Sun, for example, then there's a big 442 00:24:05,080 --> 00:24:08,320 Speaker 1: mix of frequencies. There's green, there's red, there's blue, there's 443 00:24:08,320 --> 00:24:10,840 Speaker 1: all those together and together they make white. So the 444 00:24:10,880 --> 00:24:12,720 Speaker 1: image you see of the sun if you look at 445 00:24:12,760 --> 00:24:15,000 Speaker 1: the sun, please don't if you take a picture of 446 00:24:15,000 --> 00:24:18,280 Speaker 1: the sun, is you see all those photons coming together 447 00:24:18,480 --> 00:24:21,600 Speaker 1: into your telescope or your camera or your eye, and 448 00:24:21,640 --> 00:24:25,400 Speaker 1: it's making that image. It's a summed up all those 449 00:24:25,440 --> 00:24:28,560 Speaker 1: little bits of photons together make that image. It's really 450 00:24:28,760 --> 00:24:31,399 Speaker 1: similar to the way you look at a screen. A 451 00:24:31,480 --> 00:24:34,200 Speaker 1: screen is a bunch of pixels. It's an image broken 452 00:24:34,200 --> 00:24:36,919 Speaker 1: down into little pieces, and the same thing happens in 453 00:24:37,000 --> 00:24:39,360 Speaker 1: nature even without a screen, even without a device, right, 454 00:24:39,400 --> 00:24:42,560 Speaker 1: just your eye essentially just gathers all those photons and 455 00:24:42,600 --> 00:24:45,600 Speaker 1: builds an image in your mind. So the second part 456 00:24:45,600 --> 00:24:48,480 Speaker 1: of the question was how does the photon carry within 457 00:24:48,520 --> 00:24:50,760 Speaker 1: itself a pixel so that we're able to see the 458 00:24:50,800 --> 00:24:53,800 Speaker 1: images we see on our telescopes. We'll remember the photons 459 00:24:53,800 --> 00:24:56,680 Speaker 1: that don't carry the pixels. Pixels themselves are a way 460 00:24:56,680 --> 00:25:00,159 Speaker 1: to see photons are way to detect photons. So if 461 00:25:00,160 --> 00:25:03,240 Speaker 1: you think about what happens inside a telescope these days, 462 00:25:03,240 --> 00:25:05,760 Speaker 1: telescopes are all digital, meaning you have a bunch of 463 00:25:05,840 --> 00:25:08,280 Speaker 1: lenses to gather the light and focus the light, but 464 00:25:08,320 --> 00:25:11,280 Speaker 1: the light in the end is focused onto a digital device, 465 00:25:11,400 --> 00:25:14,879 Speaker 1: a digital camera basically that gathers and measures the amount 466 00:25:14,920 --> 00:25:17,159 Speaker 1: of light. And the way those work is essentially to 467 00:25:17,200 --> 00:25:19,560 Speaker 1: have a bunch of little buckets, and if a photon 468 00:25:19,640 --> 00:25:22,119 Speaker 1: lands in that bucket, then it gets counted, and then 469 00:25:22,160 --> 00:25:24,919 Speaker 1: you just count the number of photons you see and 470 00:25:24,960 --> 00:25:27,680 Speaker 1: the picture is formed by having the places where more 471 00:25:27,720 --> 00:25:31,199 Speaker 1: photons landed be more intense and the places where fewer 472 00:25:31,240 --> 00:25:34,399 Speaker 1: photons landed be less intense. So you divide up the 473 00:25:34,440 --> 00:25:36,879 Speaker 1: whole space into these buckets, and in each one you 474 00:25:36,960 --> 00:25:40,439 Speaker 1: count how many photons you saw, and that forms your image. 475 00:25:40,640 --> 00:25:42,240 Speaker 1: So that's how you might form like a black and 476 00:25:42,240 --> 00:25:45,000 Speaker 1: white image if you're just counting the number of photons 477 00:25:45,160 --> 00:25:47,880 Speaker 1: and you don't care what the energy was for any 478 00:25:47,960 --> 00:25:51,840 Speaker 1: individual photon. That's how black and white camera works. We, 479 00:25:51,920 --> 00:25:54,359 Speaker 1: of course, are very interested in color photography or color 480 00:25:54,440 --> 00:25:56,679 Speaker 1: images of things that come from space. We want to 481 00:25:56,680 --> 00:25:59,119 Speaker 1: know not just what's there, but how bright is it 482 00:25:59,160 --> 00:26:01,800 Speaker 1: in red, or in green or in blue. So the 483 00:26:01,840 --> 00:26:04,480 Speaker 1: way that works is instead of just having a bunch 484 00:26:04,520 --> 00:26:08,080 Speaker 1: of individual buckets that capture photons regardless of their energy, 485 00:26:08,280 --> 00:26:11,440 Speaker 1: we have different kinds of buckets, just like in your eye, 486 00:26:11,760 --> 00:26:13,720 Speaker 1: how you have different kinds of things in the back 487 00:26:13,760 --> 00:26:16,240 Speaker 1: of your eye, the rods and the cones, some of 488 00:26:16,280 --> 00:26:18,160 Speaker 1: which can capture light and some of which can capture 489 00:26:18,240 --> 00:26:21,560 Speaker 1: light of only specific wavelengths. In the same way, a 490 00:26:21,680 --> 00:26:25,200 Speaker 1: digital camera has different kinds of buckets buckets with filters 491 00:26:25,200 --> 00:26:28,879 Speaker 1: over them, so they capture lighted different wavelengths, different frequencies, 492 00:26:28,920 --> 00:26:31,880 Speaker 1: different energies. All those things are equivalent, and so you'll 493 00:26:31,920 --> 00:26:35,480 Speaker 1: have like a red bucket that only captures reddish photons, 494 00:26:35,600 --> 00:26:38,359 Speaker 1: or a blue bucket that captures things around the blue 495 00:26:38,680 --> 00:26:40,800 Speaker 1: part of the spectrum, and a green one that captures 496 00:26:40,800 --> 00:26:43,480 Speaker 1: things around the green part of the spectrum. In an 497 00:26:43,520 --> 00:26:46,960 Speaker 1: ideal world, for every pixel in your image, you would 498 00:26:47,040 --> 00:26:50,080 Speaker 1: have a red, a green, and a blue bucket, so 499 00:26:50,119 --> 00:26:52,879 Speaker 1: that you could figure out afterwards exactly what the color 500 00:26:53,040 --> 00:26:55,280 Speaker 1: was by combining them back from red, green and blue 501 00:26:55,560 --> 00:26:58,440 Speaker 1: and figuring out exactly what the mixture was and telling 502 00:26:58,480 --> 00:27:00,879 Speaker 1: you what color it is. But you can't really have 503 00:27:01,000 --> 00:27:03,760 Speaker 1: these buckets on top of each other, so practically what 504 00:27:03,840 --> 00:27:06,959 Speaker 1: happens in most digital cameras is that for one pixel, 505 00:27:07,000 --> 00:27:09,679 Speaker 1: you'll only have one kind of bucket. So for a 506 00:27:09,720 --> 00:27:12,320 Speaker 1: certain pixel you might have a blue bucket, the next 507 00:27:12,320 --> 00:27:14,840 Speaker 1: pixel will be only a red bucket, and the next 508 00:27:14,840 --> 00:27:17,480 Speaker 1: one will be only a green bucket. And then later 509 00:27:17,520 --> 00:27:20,280 Speaker 1: when you want to understand how much green light is 510 00:27:20,320 --> 00:27:22,720 Speaker 1: there in a place where there was only a red pixel, 511 00:27:23,080 --> 00:27:25,320 Speaker 1: you don't know because you didn't measure it because you 512 00:27:25,320 --> 00:27:27,560 Speaker 1: didn't have a green bucket there. So what they do 513 00:27:27,680 --> 00:27:30,720 Speaker 1: is they interpolate. They say how much green was there 514 00:27:30,760 --> 00:27:32,480 Speaker 1: over there on the right, and how much green was 515 00:27:32,480 --> 00:27:34,760 Speaker 1: there over there on the left, and it figures it out, 516 00:27:34,840 --> 00:27:37,280 Speaker 1: it guesses how much green there might have been. So 517 00:27:37,400 --> 00:27:41,359 Speaker 1: color photography is much more complicated, and even color photography 518 00:27:41,440 --> 00:27:45,200 Speaker 1: using digital cameras attached to telescopes is much more complicated 519 00:27:45,640 --> 00:27:48,800 Speaker 1: than you might imagine. So that's the way that photons 520 00:27:48,920 --> 00:27:52,359 Speaker 1: carry information that creates the pixels we see in our images. Right, 521 00:27:52,400 --> 00:27:55,080 Speaker 1: they don't carry the pixel. They don't show up and say, Hi, 522 00:27:55,200 --> 00:27:57,800 Speaker 1: you should make this pixel a certain amount. The pixels 523 00:27:57,840 --> 00:28:01,119 Speaker 1: instead add up, they integrate over all the photons that 524 00:28:01,160 --> 00:28:05,119 Speaker 1: they detect. Alright, wonderful question. And my favorite part is 525 00:28:05,160 --> 00:28:08,680 Speaker 1: this last bit that how do photons not disintegrate after 526 00:28:08,720 --> 00:28:11,600 Speaker 1: traveling so far? Right? Because the photons have gone really 527 00:28:11,640 --> 00:28:14,560 Speaker 1: far away. They might have left their star a bismillion 528 00:28:14,640 --> 00:28:17,359 Speaker 1: miles away and flown through space for oodles of years 529 00:28:17,359 --> 00:28:20,960 Speaker 1: before finally landing on your telescope or on your eyeball 530 00:28:21,119 --> 00:28:24,359 Speaker 1: or on that rock. Right, think about how many amazing 531 00:28:24,400 --> 00:28:26,639 Speaker 1: things have happened in the universe and the light from 532 00:28:26,680 --> 00:28:29,480 Speaker 1: them has just been ignored. It's just like you know, 533 00:28:29,600 --> 00:28:31,760 Speaker 1: hit a dog, or hit a street light, or just 534 00:28:32,119 --> 00:28:34,240 Speaker 1: you know, hit the earth when it was daytime so 535 00:28:34,280 --> 00:28:37,720 Speaker 1: we couldn't even see it. Anyway. The question is how 536 00:28:37,760 --> 00:28:40,560 Speaker 1: does it not disintegrate? How does it last for so long? Well, 537 00:28:40,560 --> 00:28:43,760 Speaker 1: a photon can go forever. It has the energy it needs, 538 00:28:43,760 --> 00:28:46,600 Speaker 1: and it can fly through space. If it doesn't hit something, 539 00:28:47,000 --> 00:28:50,200 Speaker 1: if it doesn't bounce into an electron or hit some atmosphere, 540 00:28:50,280 --> 00:28:53,600 Speaker 1: it could literally fly forever. A photon is self sustaining. 541 00:28:53,840 --> 00:28:57,520 Speaker 1: It's it's this amazing combination of electric fields and magnetic 542 00:28:57,560 --> 00:29:01,480 Speaker 1: fields that slash back and forth to be completely self sustaining. 543 00:29:01,880 --> 00:29:04,520 Speaker 1: So in an empty universe, if you shot a photon, 544 00:29:04,720 --> 00:29:09,000 Speaker 1: it would fly forever, nothing, nothing, but there's nothing there 545 00:29:09,000 --> 00:29:10,800 Speaker 1: to stop it, in the same way that if you 546 00:29:10,880 --> 00:29:14,080 Speaker 1: pushed a ball through space through empty space, it would 547 00:29:14,080 --> 00:29:17,400 Speaker 1: fly forever. So photons don't get tired. They're happy to 548 00:29:17,400 --> 00:29:20,520 Speaker 1: fly through the whole universe to bring to you pictures 549 00:29:20,560 --> 00:29:23,719 Speaker 1: from amazing and crazy things that are happening super far away. 550 00:29:23,880 --> 00:29:26,200 Speaker 1: And we're glad that they are. We're glad that they 551 00:29:26,240 --> 00:29:29,560 Speaker 1: get here, that they deliver this information into our eyeballs 552 00:29:29,760 --> 00:29:32,840 Speaker 1: because we get to see this, this beautiful spectacle that 553 00:29:33,040 --> 00:29:35,840 Speaker 1: is the universe. All right, So that was a wonderful 554 00:29:35,880 --> 00:29:38,960 Speaker 1: listener Questions episode. Thank you very much to everybody who 555 00:29:38,960 --> 00:29:41,440 Speaker 1: wrote in and sent us their questions. And to those 556 00:29:41,480 --> 00:29:43,560 Speaker 1: of you who have sent us your recording of your 557 00:29:43,640 --> 00:29:46,200 Speaker 1: questions but not heard yourself yet on the air, be patient. 558 00:29:46,280 --> 00:29:48,880 Speaker 1: We will get to you. Thanks everybody for tuning in. 559 00:29:48,920 --> 00:29:51,480 Speaker 1: I hope you enjoyed hearing about traveling at the speed 560 00:29:51,520 --> 00:29:54,959 Speaker 1: of sound and hairy black holes and photons limping their 561 00:29:55,000 --> 00:29:57,800 Speaker 1: way through the universe after billions of miles of journeys, 562 00:29:58,160 --> 00:30:00,280 Speaker 1: and I hope that your journeys take you to place 563 00:30:00,280 --> 00:30:04,720 Speaker 1: where you can appreciate this incredible, beautiful, but perplexing universe 564 00:30:04,760 --> 00:30:08,120 Speaker 1: that we find ourselves in. Send your questions to Questions 565 00:30:08,200 --> 00:30:11,600 Speaker 1: at Daniel and Jorge dot com. Thanks for tuning in. 566 00:30:19,680 --> 00:30:22,000 Speaker 1: If you still have a question after listening to all 567 00:30:22,000 --> 00:30:25,240 Speaker 1: these explanations, please drop us a line. We'd love to 568 00:30:25,280 --> 00:30:27,680 Speaker 1: hear from you. You can find us at Facebook, Twitter, 569 00:30:27,800 --> 00:30:31,440 Speaker 1: and Instagram at Daniel and Jorge That's one word, or 570 00:30:31,560 --> 00:30:35,480 Speaker 1: email us at Feedback at Daniel and Jorge dot com. 571 00:30:35,520 --> 00:30:38,320 Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain 572 00:30:38,400 --> 00:30:41,240 Speaker 1: the Universe is a production of I Heart Radio. For 573 00:30:41,400 --> 00:30:44,320 Speaker 1: more podcast from my Heart Radio, visit the I Heart 574 00:30:44,440 --> 00:30:48,000 Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your 575 00:30:48,080 --> 00:30:48,800 Speaker 1: favorite shows,