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When you pop 10 00:00:29,320 --> 00:00:31,240 Speaker 1: a piece of cheese into your mouth, you're probably not 11 00:00:31,360 --> 00:00:34,280 Speaker 1: thinking about the environmental impact. But the people in the 12 00:00:34,360 --> 00:00:37,680 Speaker 1: dairy industry are. That's why they're working hard every day 13 00:00:37,720 --> 00:00:40,760 Speaker 1: to find new ways to reduce waste, conserve natural resources, 14 00:00:40,800 --> 00:00:44,360 Speaker 1: and drive down greenhouse gas emissions. How is US Dairy 15 00:00:44,400 --> 00:00:48,520 Speaker 1: tackling greenhouse gases? Many farms use anaerobic digesters to turn 16 00:00:48,560 --> 00:00:53,080 Speaker 1: the methane from manure into renewable energy that can power farms, towns, 17 00:00:53,120 --> 00:00:57,240 Speaker 1: and electric cars. Visit us dairy dot COM's Last Sustainability 18 00:00:57,280 --> 00:00:58,000 Speaker 1: to learn more. 19 00:00:58,720 --> 00:01:02,160 Speaker 2: What's Good It's Calling and Eating Walbroke is back for 20 00:01:02,280 --> 00:01:05,120 Speaker 2: season three, brought to you by the Black Effect Podcast 21 00:01:05,200 --> 00:01:08,560 Speaker 2: Network and iHeartRadio. We're serving up some real stories and 22 00:01:08,640 --> 00:01:12,120 Speaker 2: life lessons from people like van leythan DC, Young, Flight, 23 00:01:12,400 --> 00:01:14,880 Speaker 2: Phone Thugs and Harmony and many more. They're sharing the 24 00:01:14,920 --> 00:01:17,440 Speaker 2: dishes that got them through their struggles and the wisdom 25 00:01:17,480 --> 00:01:20,080 Speaker 2: they gained along the way. We're cooking up something special, 26 00:01:20,280 --> 00:01:24,319 Speaker 2: So tune in every Thursday. Listen to Eating Wallbroke on 27 00:01:24,360 --> 00:01:28,600 Speaker 2: the Black Effect Podcast Network, iHeartRadio, app Apple Podcasts or 28 00:01:28,600 --> 00:01:29,679 Speaker 2: wherever you get your. 29 00:01:29,640 --> 00:01:33,840 Speaker 1: Podcasts presented by State Farm like a good neighbor. State 30 00:01:33,920 --> 00:01:34,600 Speaker 1: Farm is there? 31 00:01:42,880 --> 00:01:45,399 Speaker 3: Hey, Daniel, do you keep a family photo album? 32 00:01:45,520 --> 00:01:48,440 Speaker 1: You know we used to, but these days it's all digital. 33 00:01:48,560 --> 00:01:51,240 Speaker 1: I think Mark Zuckerberg owns all of our family photos. 34 00:01:51,840 --> 00:01:53,280 Speaker 3: Hey it on is your family period? 35 00:01:53,320 --> 00:01:54,960 Speaker 1: Probably that too. 36 00:01:55,440 --> 00:01:57,080 Speaker 3: And how do you feel when you look back and 37 00:01:57,120 --> 00:01:59,120 Speaker 3: see pictures of yourself when you were younger? 38 00:02:00,120 --> 00:02:02,320 Speaker 1: Trying to ignore all those signs of aging? You know, 39 00:02:02,360 --> 00:02:04,320 Speaker 1: pretend that I look the same ten or twenty years 40 00:02:04,320 --> 00:02:05,279 Speaker 1: ago as I do today. 41 00:02:05,480 --> 00:02:09,880 Speaker 3: I see myself as a fine wine, because you have turned. 42 00:02:11,639 --> 00:02:13,480 Speaker 3: I just to get more expensive the older I get. 43 00:02:13,919 --> 00:02:16,160 Speaker 3: For some reason. Well, you know, I've known you for 44 00:02:16,560 --> 00:02:20,000 Speaker 3: over ten years or so, and I can say with 45 00:02:20,080 --> 00:02:22,760 Speaker 3: confidence for those people listening, that you are, sir No 46 00:02:23,080 --> 00:02:23,640 Speaker 3: Paul Rudd. 47 00:02:23,680 --> 00:02:26,919 Speaker 1: Unfortunately that's true in many ways. 48 00:02:27,040 --> 00:02:30,280 Speaker 3: Unfortunately, but it is kind of interesting how little clues 49 00:02:30,360 --> 00:02:33,399 Speaker 3: can show you how old someone is, or how old 50 00:02:33,480 --> 00:02:34,239 Speaker 3: something is. Right. 51 00:02:34,800 --> 00:02:37,240 Speaker 1: It's true, you know, a few wrinkles here and a 52 00:02:37,240 --> 00:02:39,960 Speaker 1: few gray hairs there, and all of a sudden, you 53 00:02:40,000 --> 00:02:41,960 Speaker 1: look like you're in your midlife crisis. 54 00:02:43,320 --> 00:02:45,280 Speaker 3: What's that look like a look of panic? 55 00:02:46,639 --> 00:02:49,560 Speaker 1: It's a look of gravitas. I always remember how dan 56 00:02:49,639 --> 00:02:52,480 Speaker 1: Quayle died his temples gray in order to not look 57 00:02:52,520 --> 00:02:53,560 Speaker 1: so much like a little. 58 00:02:53,360 --> 00:02:57,640 Speaker 3: Boy dan quail Man. That's a reference that totally tells 59 00:02:57,840 --> 00:02:58,880 Speaker 3: everyone how old you are. 60 00:03:01,240 --> 00:03:05,840 Speaker 1: Nobody's fascinating how almost everything around us ages right. Everything 61 00:03:05,919 --> 00:03:09,760 Speaker 1: from people around you, to the rocks around you, to 62 00:03:09,919 --> 00:03:12,840 Speaker 1: the buildings around you always show their signs of age. 63 00:03:13,000 --> 00:03:14,720 Speaker 1: Nothing in this world is permanent. 64 00:03:30,919 --> 00:03:33,440 Speaker 3: Hi, I am Poorhan. I'm a cartoonist and the creator 65 00:03:33,480 --> 00:03:34,760 Speaker 3: of PhD comics. 66 00:03:34,840 --> 00:03:38,080 Speaker 1: Hi I'm Daniel. I'm a particle physicist, and I'm young 67 00:03:38,280 --> 00:03:41,960 Speaker 1: and spry, and I have not written any web comics, 68 00:03:41,960 --> 00:03:44,320 Speaker 1: but I'm the co author of the book We have 69 00:03:44,440 --> 00:03:48,440 Speaker 1: no idea all about the unknown questions in the universe. 70 00:03:48,360 --> 00:03:52,040 Speaker 3: And welcome to our podcast, Daniel and Jorge Explain the Universe, 71 00:03:52,200 --> 00:03:54,840 Speaker 3: a production of iHeartRadio. 72 00:03:54,160 --> 00:03:57,000 Speaker 1: In which we take weird and amazing and young and 73 00:03:57,120 --> 00:03:59,680 Speaker 1: old stuff in the universe and try to explain it 74 00:03:59,720 --> 00:04:02,400 Speaker 1: to you, and not just telling you the answers, but 75 00:04:02,480 --> 00:04:05,760 Speaker 1: sometimes digging in deeply and explaining how we know so 76 00:04:05,800 --> 00:04:08,720 Speaker 1: that you can explain it to skeptical folks around you. 77 00:04:09,080 --> 00:04:12,200 Speaker 3: Yeah, we try to get you to think about the 78 00:04:12,240 --> 00:04:14,880 Speaker 3: world around you and even the world you're standing on 79 00:04:15,000 --> 00:04:17,760 Speaker 3: right now or sitting on or lying down on. 80 00:04:18,200 --> 00:04:21,280 Speaker 1: And one of the depending on how old you are, 81 00:04:21,760 --> 00:04:24,359 Speaker 1: but one of the goals of this podcast is for 82 00:04:24,440 --> 00:04:26,400 Speaker 1: you to have sort of a new perspective on the 83 00:04:26,440 --> 00:04:29,279 Speaker 1: world around you. We want you to see everything around 84 00:04:29,279 --> 00:04:31,920 Speaker 1: you as sort of a clue, something that can tell 85 00:04:31,960 --> 00:04:34,719 Speaker 1: you how the world works, that can reveal secrets, that 86 00:04:34,800 --> 00:04:38,320 Speaker 1: can answer questions. Because almost every question we have about 87 00:04:38,360 --> 00:04:41,320 Speaker 1: the universe, the answers are all around us, and it 88 00:04:41,440 --> 00:04:44,039 Speaker 1: just takes sort of a trained mind and a careful 89 00:04:44,040 --> 00:04:46,080 Speaker 1: eye to see those clues everywhere. 90 00:04:46,160 --> 00:04:49,039 Speaker 3: And so there are clues all around you about where 91 00:04:49,040 --> 00:04:51,480 Speaker 3: we come from and how long we've been here. And 92 00:04:51,520 --> 00:04:53,200 Speaker 3: how long everything has been here? Right? 93 00:04:53,720 --> 00:04:57,039 Speaker 1: Yeah, exactly. And sometimes the answers are easy and obvious, 94 00:04:57,040 --> 00:05:00,600 Speaker 1: and sometimes the answers are mind bogglingly surprising. 95 00:05:00,720 --> 00:05:03,320 Speaker 3: And so today on the podcast we'll be tackling, quite 96 00:05:03,360 --> 00:05:07,080 Speaker 3: possibly the oldest question on earth. Would you say that's true? Daniel? 97 00:05:07,200 --> 00:05:08,440 Speaker 1: Is that who stole my dessert? 98 00:05:09,080 --> 00:05:11,560 Speaker 3: I think the answer is obvious, obviously it's your your children. 99 00:05:12,120 --> 00:05:15,039 Speaker 1: Well, you know, that's actually a question my kids asked 100 00:05:15,120 --> 00:05:18,200 Speaker 1: me today. When was dessert invented? 101 00:05:18,480 --> 00:05:20,840 Speaker 3: Oh, sounds like a topic for a. 102 00:05:20,760 --> 00:05:23,599 Speaker 1: Podcast, you know, if that falls into a physics question, 103 00:05:23,720 --> 00:05:26,280 Speaker 1: But it's sort of a fascinating question, and they were 104 00:05:26,279 --> 00:05:30,240 Speaker 1: actually hypothesizing that dessert might be older than people, that maybe, 105 00:05:30,279 --> 00:05:34,400 Speaker 1: like our pre human ancestors, enjoyed a sweet, sweet treat 106 00:05:34,440 --> 00:05:35,040 Speaker 1: after dinner. 107 00:05:35,200 --> 00:05:38,320 Speaker 3: What do you think the little bacteria that that walled 108 00:05:38,320 --> 00:05:41,040 Speaker 3: in the ocean or like, you know, I could use 109 00:05:41,040 --> 00:05:45,560 Speaker 3: a little timi suit after consuming other other bacteria. 110 00:05:45,800 --> 00:05:47,599 Speaker 1: I don't know if we have enough in common with 111 00:05:47,680 --> 00:05:49,840 Speaker 1: bacteria to say what they might like, but I can 112 00:05:49,920 --> 00:05:54,240 Speaker 1: imagine some pre human homadid, you know, eating some berries 113 00:05:54,279 --> 00:05:57,160 Speaker 1: and going, hm, that goes nicely with my antelope or whatever. 114 00:05:57,200 --> 00:05:57,920 Speaker 1: They had for dinner. 115 00:05:58,000 --> 00:06:01,080 Speaker 3: Well anyway, So so really, uh, what I mean by 116 00:06:01,120 --> 00:06:04,560 Speaker 3: it the oldest question on Earth is that it's probably 117 00:06:04,600 --> 00:06:07,280 Speaker 3: really the oldest question that could be on Earth, Right. 118 00:06:07,240 --> 00:06:11,080 Speaker 1: Yeah, I think that's probably true. And it's an important question, right. 119 00:06:11,120 --> 00:06:13,039 Speaker 1: It's the kind of question that we'd like to dig 120 00:06:13,080 --> 00:06:16,680 Speaker 1: into because it's the kind of question where the answer 121 00:06:16,920 --> 00:06:19,560 Speaker 1: could change the way we think about life and the 122 00:06:19,640 --> 00:06:22,600 Speaker 1: universe and the humanity's rolled in it. Right. It has 123 00:06:22,640 --> 00:06:25,480 Speaker 1: all sorts of things to do with creation and the 124 00:06:25,480 --> 00:06:28,200 Speaker 1: context of our lives and therefore how we should live 125 00:06:28,279 --> 00:06:29,680 Speaker 1: our lives and whether they have meaning. 126 00:06:29,760 --> 00:06:31,760 Speaker 3: And so today on the podcast, we'll be tackling the 127 00:06:31,839 --> 00:06:41,320 Speaker 3: question how old is the earth? And is it even 128 00:06:41,360 --> 00:06:42,080 Speaker 3: polite to ask? 129 00:06:42,760 --> 00:06:45,320 Speaker 1: That's? Right? And what does the earth do when it 130 00:06:45,360 --> 00:06:46,000 Speaker 1: gets upset? 131 00:06:46,360 --> 00:06:46,480 Speaker 4: Right? 132 00:06:46,520 --> 00:06:49,800 Speaker 1: When he gets offended? And not just how old? 133 00:06:49,800 --> 00:06:51,840 Speaker 3: I had any work done? Has Earth had any work done? 134 00:06:52,040 --> 00:06:52,560 Speaker 3: Is it trying to? 135 00:06:54,360 --> 00:06:56,599 Speaker 1: I think the Earth looks great? Doesn't look a day 136 00:06:56,640 --> 00:06:57,560 Speaker 1: past four billion? 137 00:07:00,160 --> 00:07:02,880 Speaker 3: Full of bulltok? They'll probably rank me sure. 138 00:07:03,920 --> 00:07:06,160 Speaker 1: And just as important as the question how old is 139 00:07:06,200 --> 00:07:08,000 Speaker 1: the Earth and the answer, which is you know, just 140 00:07:08,040 --> 00:07:10,680 Speaker 1: a number, is how do we know? How do we 141 00:07:10,720 --> 00:07:13,040 Speaker 1: have confidence in this answer, because you know, there are 142 00:07:13,080 --> 00:07:15,640 Speaker 1: people out there who hold beliefs about the various age 143 00:07:15,680 --> 00:07:18,120 Speaker 1: of the Earth. And one of our listeners actually wrote 144 00:07:18,160 --> 00:07:20,560 Speaker 1: in and said, hey, could you tell me how we 145 00:07:20,680 --> 00:07:22,280 Speaker 1: know the age of the Earth, so that when I 146 00:07:22,280 --> 00:07:25,080 Speaker 1: discuss it with my friends who have strong opinions about 147 00:07:25,080 --> 00:07:26,840 Speaker 1: the age of the Earth, I can tell them not 148 00:07:27,000 --> 00:07:29,840 Speaker 1: just what scientists think, but how they know it. 149 00:07:30,160 --> 00:07:31,760 Speaker 3: Yeah, And that's the thing I think we always try 150 00:07:31,800 --> 00:07:33,920 Speaker 3: to do in this podcast, right, is try to get 151 00:07:33,960 --> 00:07:36,680 Speaker 3: at how people know these things, not just tell people 152 00:07:36,720 --> 00:07:39,400 Speaker 3: what scientists know, but how they know it. 153 00:07:39,360 --> 00:07:41,960 Speaker 1: That's right, And that also helps you understand with what 154 00:07:42,080 --> 00:07:44,240 Speaker 1: confidence we know it, Like is this just sort of 155 00:07:44,320 --> 00:07:47,560 Speaker 1: an educated guess back of the envelope calculation or is 156 00:07:47,600 --> 00:07:49,560 Speaker 1: this something that people have been working on for hundreds 157 00:07:49,560 --> 00:07:51,920 Speaker 1: of years and we have great confidence and have it 158 00:07:52,080 --> 00:07:54,800 Speaker 1: nailed down to zero point oh one percent. And it's 159 00:07:54,840 --> 00:07:58,000 Speaker 1: important because different things in science are known well, and 160 00:07:58,040 --> 00:08:01,080 Speaker 1: some things in science are are known no, not very well, 161 00:08:01,120 --> 00:08:03,000 Speaker 1: So it's important to know how we know. 162 00:08:03,400 --> 00:08:05,680 Speaker 3: Yeah, And so how old is the Earth is the 163 00:08:05,760 --> 00:08:09,320 Speaker 3: question for today, and it's kind of I think it's 164 00:08:09,360 --> 00:08:12,680 Speaker 3: a question most people know a little bit about right. 165 00:08:12,800 --> 00:08:15,240 Speaker 3: I mean, I think everyone knows or has a sense 166 00:08:15,280 --> 00:08:16,800 Speaker 3: that the Earth is very old. 167 00:08:17,400 --> 00:08:20,240 Speaker 1: Yeah, but you know, that sense that the Earth is 168 00:08:20,280 --> 00:08:24,400 Speaker 1: like extremely old, like many orders of magnitude older than 169 00:08:24,560 --> 00:08:27,480 Speaker 1: you or me or your parents, you know, is a 170 00:08:27,480 --> 00:08:31,920 Speaker 1: fairly modern idea. I think thousands of years ago, people 171 00:08:32,000 --> 00:08:35,280 Speaker 1: thought the Earth was only hundreds or thousands of years old. 172 00:08:35,360 --> 00:08:38,320 Speaker 1: They thought it might have been created fairly recently. And 173 00:08:38,360 --> 00:08:40,680 Speaker 1: it was only sort of in the eighteen hundreds that 174 00:08:40,720 --> 00:08:44,120 Speaker 1: people started to understand that there were processes around us 175 00:08:44,120 --> 00:08:48,160 Speaker 1: that we could see, specifically rocks and evolutions or geology 176 00:08:48,240 --> 00:08:51,760 Speaker 1: and biology started to give hints that the answer was 177 00:08:52,000 --> 00:08:55,800 Speaker 1: much much bigger than anything anybody had imagined. And I 178 00:08:55,800 --> 00:08:58,920 Speaker 1: think that's wonderful. I'd love to live in a scientific 179 00:08:58,920 --> 00:09:02,440 Speaker 1: era like that, where you're where something you thought you 180 00:09:02,559 --> 00:09:05,800 Speaker 1: knew is upended and replaced with a completely different answer. 181 00:09:05,800 --> 00:09:07,440 Speaker 1: That's like, or is a magnitude bigger? 182 00:09:08,960 --> 00:09:11,680 Speaker 3: Wow? Is that really true? Like it only in the 183 00:09:11,760 --> 00:09:14,720 Speaker 3: last couple of hundred years do we have a sense 184 00:09:14,760 --> 00:09:17,440 Speaker 3: of how old the Earth really is. Before it was 185 00:09:17,480 --> 00:09:18,400 Speaker 3: totally up in the air. 186 00:09:18,480 --> 00:09:19,800 Speaker 1: Yeah, it was up in the air until about the 187 00:09:19,800 --> 00:09:22,559 Speaker 1: eighteen hundreds, and then people started trying to do calculations 188 00:09:22,600 --> 00:09:24,800 Speaker 1: and they're like, well, how long would it take to 189 00:09:24,880 --> 00:09:27,160 Speaker 1: form a planet? You know, say you gathered it together 190 00:09:27,200 --> 00:09:30,640 Speaker 1: with gravity, or you know, how long would it take 191 00:09:30,720 --> 00:09:33,320 Speaker 1: to lay down layers of rock? You know, how long 192 00:09:33,400 --> 00:09:35,760 Speaker 1: would it take glaciers to move this kind of stuff? 193 00:09:36,040 --> 00:09:38,520 Speaker 1: And you know, geology is a fairly young field and 194 00:09:38,559 --> 00:09:40,360 Speaker 1: that you know, it's a couple hundred years old. And 195 00:09:40,400 --> 00:09:43,000 Speaker 1: so people started to look around and as soon as 196 00:09:43,000 --> 00:09:47,480 Speaker 1: they started to explore these geological processes, they realized, wow, 197 00:09:47,559 --> 00:09:50,840 Speaker 1: this stuff takes a long time. And you know, it's 198 00:09:50,880 --> 00:09:54,040 Speaker 1: sort of like walking into a room and seeing somebody 199 00:09:54,120 --> 00:09:57,679 Speaker 1: has written a book that's like five million pages long, 200 00:09:57,800 --> 00:09:59,599 Speaker 1: and you're like, wow, you've been in this room a 201 00:09:59,720 --> 00:10:03,840 Speaker 1: long time. You know, it shocks you into realizing that things, 202 00:10:04,200 --> 00:10:07,199 Speaker 1: things are a much different scale than you imagined. And 203 00:10:07,240 --> 00:10:09,880 Speaker 1: that's this. We've seen the story the earth all around us. 204 00:10:09,920 --> 00:10:13,720 Speaker 1: We realize it's staggeringly long, much longer than we imagined, 205 00:10:13,880 --> 00:10:15,520 Speaker 1: and that, yeah, that's a fairly new idea. 206 00:10:15,760 --> 00:10:19,079 Speaker 3: Yeah, that's a lot of party you've missed exactly we 207 00:10:19,160 --> 00:10:22,360 Speaker 3: should things have been around for a long time. 208 00:10:23,200 --> 00:10:24,719 Speaker 1: Do you have a fear of missing out. There is 209 00:10:24,720 --> 00:10:26,319 Speaker 1: that fomo about what happened. 210 00:10:26,000 --> 00:10:31,280 Speaker 3: To all the good desserts, fear of being in parties? Actually, 211 00:10:31,600 --> 00:10:32,520 Speaker 3: to be honest. 212 00:10:32,440 --> 00:10:34,320 Speaker 1: What about all the desserts? They usually have good desserts 213 00:10:34,360 --> 00:10:35,200 Speaker 1: of parties. 214 00:10:35,000 --> 00:10:37,240 Speaker 3: Old desserts or I just like I just like a 215 00:10:37,320 --> 00:10:38,439 Speaker 3: fine dessert. 216 00:10:38,480 --> 00:10:38,760 Speaker 2: Wine. 217 00:10:39,720 --> 00:10:41,160 Speaker 1: So you show you show up at the beginning of 218 00:10:41,160 --> 00:10:43,120 Speaker 1: a party, how the desserts, drink the wine, and then 219 00:10:43,160 --> 00:10:45,360 Speaker 1: go home. That's how you know you're old or. 220 00:10:45,360 --> 00:10:46,480 Speaker 3: It sounds like a good party to me. 221 00:10:47,760 --> 00:10:50,840 Speaker 1: That is how you age old. Trick exactly. That's very 222 00:10:50,920 --> 00:10:56,000 Speaker 1: age appropriate. The beginning of this field, like becoming scientific, 223 00:10:56,000 --> 00:10:58,079 Speaker 1: before that was just speculation. But the beginning of the 224 00:10:58,080 --> 00:11:01,680 Speaker 1: field becoming scientific was in the eighteen hundreds. But still 225 00:11:01,679 --> 00:11:04,720 Speaker 1: that's very inaccurate. Like looking at rocks gives you clues 226 00:11:04,800 --> 00:11:07,440 Speaker 1: about the sort of order of magnitude. But then people 227 00:11:07,480 --> 00:11:11,079 Speaker 1: wanted to know very precisely, and that took some time 228 00:11:11,160 --> 00:11:15,000 Speaker 1: to like basically to find clocks inside the earth, clocks 229 00:11:15,040 --> 00:11:17,280 Speaker 1: that have been ticking since it was born. And that's 230 00:11:17,360 --> 00:11:19,920 Speaker 1: in the end signs of aging, Yeah, signs of aging, 231 00:11:20,080 --> 00:11:21,880 Speaker 1: very precise signs of aging that could tell us how 232 00:11:21,920 --> 00:11:22,640 Speaker 1: old the Earth was. 233 00:11:22,720 --> 00:11:25,240 Speaker 3: So you're saying, like, you know, the people who started 234 00:11:25,640 --> 00:11:30,040 Speaker 3: the United States, like the Founding father fathers, like the 235 00:11:30,080 --> 00:11:34,200 Speaker 3: Founding Fathers, they had no idea how old we've been around, 236 00:11:34,320 --> 00:11:35,880 Speaker 3: Like did they think we've been around for a few 237 00:11:35,880 --> 00:11:39,120 Speaker 3: thousand years or few? But didn't they know about the 238 00:11:39,520 --> 00:11:41,920 Speaker 3: you know, like ancient Egypt and things like that. 239 00:11:42,240 --> 00:11:44,280 Speaker 1: Yeah, but you know, that's thousands of years And so 240 00:11:44,360 --> 00:11:46,520 Speaker 1: I think they had the idea that the Earth was, 241 00:11:46,559 --> 00:11:50,560 Speaker 1: you know, thousands, many thousands of years old, right, because 242 00:11:50,559 --> 00:11:52,440 Speaker 1: that's as long as written history is, and so they 243 00:11:52,520 --> 00:11:55,560 Speaker 1: imagine it's on that time scale because that's the oldest thing, 244 00:11:55,600 --> 00:11:58,400 Speaker 1: you know, And that's basically the game is like find 245 00:11:58,440 --> 00:12:01,080 Speaker 1: the oldest thing you know and then assume that that's 246 00:12:01,160 --> 00:12:04,320 Speaker 1: basically the age of the world, right, And that's frankly 247 00:12:04,360 --> 00:12:06,800 Speaker 1: what we're still doing, except that we think that we 248 00:12:06,880 --> 00:12:09,200 Speaker 1: found stuff that comes from the very beginning of the world. 249 00:12:09,240 --> 00:12:11,679 Speaker 1: But you know, they knew about stuff that was thousands 250 00:12:11,679 --> 00:12:13,600 Speaker 1: of years old, so they had no reason to believe 251 00:12:13,880 --> 00:12:17,520 Speaker 1: that the Earth might be millions or even god forbid, 252 00:12:17,679 --> 00:12:20,440 Speaker 1: billions of years old, right. Plus I think those guys 253 00:12:20,480 --> 00:12:21,800 Speaker 1: were pretty religious. 254 00:12:21,440 --> 00:12:23,560 Speaker 3: All right, So it is an age old question and 255 00:12:23,640 --> 00:12:26,280 Speaker 3: one that a lot of people have had answers to 256 00:12:26,400 --> 00:12:29,240 Speaker 3: and seem to have answers to. But we were wondering 257 00:12:29,440 --> 00:12:32,120 Speaker 3: what people out there right now in the world think 258 00:12:32,120 --> 00:12:32,880 Speaker 3: about this question. 259 00:12:33,120 --> 00:12:35,680 Speaker 1: Yeah, and this is one. This is a set of interviews. 260 00:12:35,720 --> 00:12:38,480 Speaker 1: I was very curious to see what people thought. I 261 00:12:38,520 --> 00:12:40,440 Speaker 1: was wondering if I would run into some sort of 262 00:12:40,520 --> 00:12:44,520 Speaker 1: young Earth folks who thought the earth was from biblical ages, 263 00:12:45,000 --> 00:12:47,560 Speaker 1: and even those people who were scientific. I was wondering, like, 264 00:12:47,600 --> 00:12:49,840 Speaker 1: how precisely do people know the age of the Earth. 265 00:12:49,920 --> 00:12:52,800 Speaker 1: So this I was very fascinated to hear the answers. 266 00:12:52,480 --> 00:12:55,160 Speaker 3: Like is it a million years, a bazillion years. 267 00:12:56,840 --> 00:12:58,760 Speaker 1: Twenty seven point two bajillion? 268 00:12:59,040 --> 00:13:01,240 Speaker 3: And so, as usual, Dane went out and asked people 269 00:13:01,320 --> 00:13:04,920 Speaker 3: on this street how old they thought the Earth was. 270 00:13:05,040 --> 00:13:06,679 Speaker 3: So think about it for a second. If you ran 271 00:13:06,720 --> 00:13:10,800 Speaker 3: into a physicist in the street on today, how would 272 00:13:10,800 --> 00:13:13,920 Speaker 3: you answer this question and no googling. Well, here's what 273 00:13:13,960 --> 00:13:14,720 Speaker 3: people had to say. 274 00:13:15,720 --> 00:13:17,800 Speaker 1: I have no idea. Probably a billion years. 275 00:13:18,120 --> 00:13:22,120 Speaker 5: I don't exactly, but my understanding is it's a couple 276 00:13:22,240 --> 00:13:23,520 Speaker 5: hundred million years old. 277 00:13:23,679 --> 00:13:24,880 Speaker 1: Okay, you know how we know? 278 00:13:25,320 --> 00:13:28,280 Speaker 5: So I don't actually like my physics knowledge is pretty limited. 279 00:13:29,000 --> 00:13:31,360 Speaker 5: I think, like we've used carbon dating to date things 280 00:13:31,400 --> 00:13:36,400 Speaker 5: within various geological epochs, but I don't actually know how 281 00:13:36,400 --> 00:13:38,760 Speaker 5: we arrived at the calculation of the Earth's age A. 282 00:13:38,760 --> 00:13:42,479 Speaker 1: Million year millionaires, okay, maybe three billion. 283 00:13:42,160 --> 00:13:47,600 Speaker 3: Years old, five billion, tens of million of years billions, yeah, cool, 284 00:13:47,840 --> 00:13:49,040 Speaker 3: four billion airs? 285 00:13:49,160 --> 00:13:51,240 Speaker 1: All right? And how do we know rock formation? 286 00:13:51,600 --> 00:13:54,040 Speaker 3: It's probably like millions of years old. I feel like, 287 00:13:54,280 --> 00:13:57,400 Speaker 3: all right, a lot of millions and billions, right. 288 00:13:57,320 --> 00:14:00,560 Speaker 1: Yeah, exactly, not not a whole lot of really specific answers. 289 00:14:00,600 --> 00:14:02,839 Speaker 1: I have to say I was a little bit disappointed. 290 00:14:03,120 --> 00:14:05,280 Speaker 1: I guess I thought people were more interested in this, 291 00:14:05,360 --> 00:14:07,480 Speaker 1: Like I remember wanting to know this number as precisely 292 00:14:07,520 --> 00:14:09,200 Speaker 1: as possible when I was a kid. I was really 293 00:14:09,240 --> 00:14:12,040 Speaker 1: curious about this, and so I was a little surprised 294 00:14:12,040 --> 00:14:14,160 Speaker 1: that people were just sort of knew it was super 295 00:14:14,200 --> 00:14:17,520 Speaker 1: old and were satisfied and didn't really care about the details. 296 00:14:17,640 --> 00:14:21,240 Speaker 1: Although I'll say every single person here after I asked 297 00:14:21,280 --> 00:14:23,320 Speaker 1: them the question, then they did turn around and ask me. 298 00:14:23,360 --> 00:14:25,720 Speaker 1: They're like, well, how old is the Earth? So they 299 00:14:25,760 --> 00:14:28,280 Speaker 1: wanted to know. I guess they just hadn't really spend 300 00:14:28,280 --> 00:14:29,280 Speaker 1: any time looking it up. 301 00:14:29,320 --> 00:14:31,640 Speaker 3: All right, Well, let's get started on this topic, Daniel. 302 00:14:31,680 --> 00:14:33,880 Speaker 3: And so, first of all, I think I feel like 303 00:14:33,880 --> 00:14:36,960 Speaker 3: we should define what we mean by the Earth by 304 00:14:36,960 --> 00:14:39,520 Speaker 3: the age of the Earth, right, Like do you mean 305 00:14:39,600 --> 00:14:43,800 Speaker 3: like the planet, like the ball that it's Earth, or 306 00:14:43,240 --> 00:14:46,400 Speaker 3: the rocks in the Earth, or the atoms that are 307 00:14:46,480 --> 00:14:47,920 Speaker 3: that make up the Earth. What do you mean, like, 308 00:14:47,960 --> 00:14:49,000 Speaker 3: what's the age of the Earth? 309 00:14:49,280 --> 00:14:51,440 Speaker 1: Yeah, it turns out that that's a bit of a 310 00:14:51,480 --> 00:14:54,920 Speaker 1: fuzzy question, right, because the Earth has a sort of 311 00:14:55,000 --> 00:14:59,280 Speaker 1: continuous history. It's not like somebody snapped their fingers and boomed, 312 00:14:59,320 --> 00:15:01,040 Speaker 1: there was the Earth and you can start. 313 00:15:00,840 --> 00:15:04,320 Speaker 3: From the clock from then, right that you know of, right. 314 00:15:04,240 --> 00:15:06,360 Speaker 1: That we know of, that's right, Yeah, unless, of course 315 00:15:06,360 --> 00:15:08,880 Speaker 1: it was a simulation, which case the answer is easy. But 316 00:15:09,640 --> 00:15:11,440 Speaker 1: in the case that it was in the simulation, we 317 00:15:11,520 --> 00:15:14,120 Speaker 1: have an idea about how the Earth was formed, and 318 00:15:14,160 --> 00:15:15,880 Speaker 1: there's just a lot of stages there, and so you 319 00:15:15,920 --> 00:15:19,440 Speaker 1: have to sort of make an arbitrary definition. And it's 320 00:15:19,560 --> 00:15:22,000 Speaker 1: like a lot of things in science, you know, there's 321 00:15:22,080 --> 00:15:24,280 Speaker 1: not necessarily a clear answer, So you just define it 322 00:15:24,280 --> 00:15:25,920 Speaker 1: to be something arbitrary and then at least we can 323 00:15:25,960 --> 00:15:28,760 Speaker 1: agree on it. But maybe we should recap sort of 324 00:15:28,840 --> 00:15:31,000 Speaker 1: the brief history of the of the Earth and how it. 325 00:15:30,920 --> 00:15:33,960 Speaker 3: Was formed, yeah, like how it came to be. Yeah, 326 00:15:34,000 --> 00:15:35,520 Speaker 3: and then at some point we're going to say this 327 00:15:35,600 --> 00:15:37,480 Speaker 3: is when the Earth started, This is when the Earth 328 00:15:37,520 --> 00:15:37,800 Speaker 3: was born. 329 00:15:37,840 --> 00:15:40,880 Speaker 1: That's right. This is when the party began, right, because 330 00:15:40,920 --> 00:15:42,640 Speaker 1: you know, you invite people to a party nine o'clock 331 00:15:42,680 --> 00:15:44,520 Speaker 1: and then they don't show up till ten, and by 332 00:15:44,520 --> 00:15:46,200 Speaker 1: then you've eaten all the brownies. 333 00:15:47,400 --> 00:15:50,000 Speaker 3: And parties only really get started at one am. 334 00:15:50,360 --> 00:15:52,640 Speaker 1: That's right, unless you're in Spain, in which case it's 335 00:15:52,680 --> 00:15:56,000 Speaker 1: four am. But you know, the very early history is 336 00:15:56,000 --> 00:15:59,040 Speaker 1: that we basically started with a huge nebula of gas 337 00:15:59,040 --> 00:16:01,040 Speaker 1: and dust. And this is stuff that's left over from 338 00:16:01,040 --> 00:16:03,800 Speaker 1: the explosions of other stars and just gas from the 339 00:16:03,840 --> 00:16:06,800 Speaker 1: Big Bang. And then of course gravity did its thing 340 00:16:07,120 --> 00:16:09,360 Speaker 1: and it pulls all that stuff together and you get 341 00:16:09,360 --> 00:16:11,280 Speaker 1: a sun, right, So most of the stuff went to 342 00:16:11,320 --> 00:16:13,280 Speaker 1: the Sun, and then you get a disc of stuff 343 00:16:13,280 --> 00:16:16,600 Speaker 1: that's rotating around the Sun. It's like rings around the Sun. 344 00:16:17,040 --> 00:16:19,760 Speaker 1: And then the gravity pulls the stuff in that disk 345 00:16:19,880 --> 00:16:23,440 Speaker 1: together to turning to turn that disk into planets. Right, 346 00:16:23,880 --> 00:16:27,360 Speaker 1: And so we think that the Solar system started about 347 00:16:27,400 --> 00:16:30,280 Speaker 1: four and a half billion years ago, and it took 348 00:16:30,360 --> 00:16:34,120 Speaker 1: like a few million or one hundred million years to 349 00:16:34,520 --> 00:16:37,600 Speaker 1: pull all that stuff and the disk together into sort 350 00:16:37,600 --> 00:16:40,080 Speaker 1: of proto planets. Right, So you have this sort of 351 00:16:40,360 --> 00:16:43,360 Speaker 1: loose collection of stuff that gravity's pulled together, and then 352 00:16:43,400 --> 00:16:46,760 Speaker 1: gravity really gets to work and it starts squeezing it 353 00:16:47,000 --> 00:16:49,800 Speaker 1: and it collects all this stuff, and the planet heats 354 00:16:49,840 --> 00:16:52,520 Speaker 1: up and sort of melts the metal and you get 355 00:16:52,560 --> 00:16:55,800 Speaker 1: the iron dropping to the core and the crust forming, 356 00:16:56,640 --> 00:16:59,200 Speaker 1: And so you can sort of ask like, at what 357 00:16:59,360 --> 00:17:02,000 Speaker 1: moment do you count the Earth forming? Is it like 358 00:17:02,480 --> 00:17:05,000 Speaker 1: when you had the first big cluster of rocks, or 359 00:17:05,040 --> 00:17:08,639 Speaker 1: maybe when it got gravitationally heated enough to sort of 360 00:17:08,880 --> 00:17:12,120 Speaker 1: melt the metals and form the core. It's not really 361 00:17:12,240 --> 00:17:12,760 Speaker 1: very clear. 362 00:17:12,800 --> 00:17:15,480 Speaker 3: Well, I always found this really fascinating, because we talked 363 00:17:15,480 --> 00:17:18,280 Speaker 3: about this the other day, that something like the rings 364 00:17:18,320 --> 00:17:22,160 Speaker 3: around Saturn are only temporary, right, Like at some point 365 00:17:22,240 --> 00:17:24,840 Speaker 3: those rings might turn into little blobs. 366 00:17:25,000 --> 00:17:29,000 Speaker 1: That's right. Gravity is very weak, but very very patient, 367 00:17:29,400 --> 00:17:31,600 Speaker 1: and so it just keeps working and you give it 368 00:17:31,720 --> 00:17:34,439 Speaker 1: enough time, it will gather things together. And so the 369 00:17:34,480 --> 00:17:38,679 Speaker 1: stuff that's orbiting Saturn eventually gravity will pull it together 370 00:17:38,800 --> 00:17:39,600 Speaker 1: in two moons. 371 00:17:39,840 --> 00:17:42,359 Speaker 3: Even the asteroid belt, is that at some point going 372 00:17:42,440 --> 00:17:44,960 Speaker 3: to turn into more planets for our Solar system? 373 00:17:45,040 --> 00:17:47,360 Speaker 1: Yeah, eventually gravity. I mean it's very slow and those 374 00:17:47,359 --> 00:17:50,480 Speaker 1: things are mostly stable orbits, but eventually that stuff will 375 00:17:50,480 --> 00:17:53,639 Speaker 1: get pulled together. I mean also there's disruption, right if 376 00:17:53,680 --> 00:17:56,000 Speaker 1: you just left the Solar system all by itself, then yes, 377 00:17:56,040 --> 00:17:59,119 Speaker 1: eventually it'll just gather together into a smaller and smaller 378 00:17:59,200 --> 00:18:02,600 Speaker 1: number of objects. But this disruption from stuff that comes outside, 379 00:18:02,680 --> 00:18:06,560 Speaker 1: you know, and comets, things from the ort cloud, even 380 00:18:06,560 --> 00:18:10,120 Speaker 1: things like supernovas from other Solar systems can disrupt things 381 00:18:10,119 --> 00:18:14,479 Speaker 1: happening in our Solar system. So but yes, eventually gravity 382 00:18:14,520 --> 00:18:17,880 Speaker 1: will pull all this stuff together. It's really incredible over 383 00:18:17,920 --> 00:18:20,320 Speaker 1: these time scales what gravity can do, and that's one 384 00:18:20,320 --> 00:18:23,440 Speaker 1: of my favorite things. It's just realizing that these processes 385 00:18:23,480 --> 00:18:26,720 Speaker 1: are really slow, so things must have been around for 386 00:18:26,760 --> 00:18:29,920 Speaker 1: a super long time to make it happen, right. 387 00:18:30,040 --> 00:18:33,439 Speaker 3: Right, Well, I guess I would maybe count the birth 388 00:18:33,480 --> 00:18:35,879 Speaker 3: of the Earth is when it was form, you know, 389 00:18:35,960 --> 00:18:39,080 Speaker 3: when all those asteroids and rocks out there clump together 390 00:18:39,400 --> 00:18:41,959 Speaker 3: into a ball about the size of the ball that 391 00:18:42,000 --> 00:18:44,840 Speaker 3: we have now, Like you know, when it kind of 392 00:18:44,840 --> 00:18:47,399 Speaker 3: snapped into shape. I would maybe count that as the 393 00:18:47,400 --> 00:18:49,119 Speaker 3: age of when the Earth started. 394 00:18:49,240 --> 00:18:53,199 Speaker 1: Yeah, yeah, and that's totally reasonable. That's totally reasonable. I 395 00:18:53,200 --> 00:18:56,640 Speaker 1: think one common definition is that you measure the age 396 00:18:56,680 --> 00:18:58,560 Speaker 1: of the Earth is sort of the age of the 397 00:18:58,600 --> 00:19:01,720 Speaker 1: oldest rock in the Earth. And then you can ask 398 00:19:01,720 --> 00:19:03,080 Speaker 1: the question, well, what does it mean for a rock 399 00:19:03,119 --> 00:19:05,199 Speaker 1: to be old? Like, you know, a rock is just 400 00:19:05,240 --> 00:19:08,560 Speaker 1: a gravitational and pulled together clump of dust. But rocks 401 00:19:08,600 --> 00:19:11,960 Speaker 1: are are formed right there, they melt and then they're cooled, 402 00:19:12,280 --> 00:19:14,040 Speaker 1: and so the age of a rock is usually like 403 00:19:14,640 --> 00:19:17,280 Speaker 1: the last time it was melted, right, So it's the 404 00:19:17,359 --> 00:19:19,720 Speaker 1: time since it was last melted, and so. 405 00:19:19,680 --> 00:19:21,800 Speaker 3: A lot of people just like the time that it 406 00:19:21,880 --> 00:19:23,320 Speaker 3: cooled off, the last. 407 00:19:23,080 --> 00:19:25,880 Speaker 1: Time it really chilled out. And so you can imagine 408 00:19:25,920 --> 00:19:27,879 Speaker 1: like all these rocks came together, as you said, and 409 00:19:27,960 --> 00:19:30,840 Speaker 1: formed the Earth and got squeezed together and probably melted 410 00:19:31,119 --> 00:19:34,320 Speaker 1: and then cooled, right the crust at least cooled, and 411 00:19:34,359 --> 00:19:36,199 Speaker 1: so you can ask, like, maybe that last moment the 412 00:19:36,280 --> 00:19:39,160 Speaker 1: last moment of cooling of the crust. So the age 413 00:19:39,160 --> 00:19:41,919 Speaker 1: of the oldest cooled rock on the Earth could be 414 00:19:41,920 --> 00:19:44,000 Speaker 1: a definition of the age of the Earth, because otherwise, 415 00:19:44,000 --> 00:19:46,080 Speaker 1: how do you know when these rocks came together? 416 00:19:46,320 --> 00:19:46,520 Speaker 4: Right? 417 00:19:47,359 --> 00:19:50,439 Speaker 1: Otherwise I don't know unless you have, like you know, 418 00:19:50,640 --> 00:19:53,639 Speaker 1: CCTV of the formation of the Solar System. It's pretty 419 00:19:53,640 --> 00:19:54,680 Speaker 1: hard to pin that down. 420 00:19:55,200 --> 00:19:57,399 Speaker 3: Or you could say, is it well, but you just 421 00:19:57,400 --> 00:19:59,000 Speaker 3: gave me a number. You said that it was maybe 422 00:19:59,080 --> 00:20:01,960 Speaker 3: it took around one hundred million years to form that 423 00:20:02,800 --> 00:20:03,600 Speaker 3: the ball of the Earth. 424 00:20:03,720 --> 00:20:06,560 Speaker 1: Yeah, that's I said. I said between a few and 425 00:20:06,640 --> 00:20:09,480 Speaker 1: one hundred million years, right, So that's a pretty big uncertainty. 426 00:20:10,200 --> 00:20:12,159 Speaker 1: We don't really know how long it took and what 427 00:20:12,280 --> 00:20:14,680 Speaker 1: moment do you define, like do you need one more rock? 428 00:20:14,840 --> 00:20:18,040 Speaker 1: Because you know, custic stuff kept getting added to the Earth. 429 00:20:18,480 --> 00:20:20,320 Speaker 1: And so some people say, well, the age of the 430 00:20:20,320 --> 00:20:22,159 Speaker 1: Earth is sort of just let's just call it the 431 00:20:22,160 --> 00:20:24,919 Speaker 1: age of the Solar System because that's pretty close to 432 00:20:24,920 --> 00:20:27,040 Speaker 1: the age of the Earth. Or you could say it's 433 00:20:27,040 --> 00:20:30,720 Speaker 1: the age of the oldest rock on the Earth. So 434 00:20:30,800 --> 00:20:33,000 Speaker 1: I think both of those are sort of acceptable, and anyway, 435 00:20:33,200 --> 00:20:35,320 Speaker 1: that's really all we can probe. In the end. What 436 00:20:35,359 --> 00:20:37,600 Speaker 1: we do is we measure the age of the oldest 437 00:20:37,680 --> 00:20:39,960 Speaker 1: rock we can find on the Earth, and we say 438 00:20:40,040 --> 00:20:41,600 Speaker 1: that's pretty close to the age of the Earth. 439 00:20:41,840 --> 00:20:43,840 Speaker 3: So the time that it formed into a ball is 440 00:20:44,320 --> 00:20:46,600 Speaker 3: kind of in between those two numbers, right, yeah, exactly, 441 00:20:46,760 --> 00:20:51,359 Speaker 3: it's between when the solar system formed and when the 442 00:20:51,400 --> 00:20:53,520 Speaker 3: ball that it's the Earth started getting. 443 00:20:53,240 --> 00:20:57,840 Speaker 1: Crusty, exactly exactly when it started getting crusty and grumpy 444 00:20:58,080 --> 00:20:59,919 Speaker 1: and eating desserted parties and going home. 445 00:21:00,640 --> 00:21:05,679 Speaker 3: Like a teenager. So somewhere between conception and teenage years, 446 00:21:05,720 --> 00:21:06,680 Speaker 3: that's when you're born. 447 00:21:06,760 --> 00:21:08,800 Speaker 1: That's right. And you know, we have the same question 448 00:21:08,840 --> 00:21:11,399 Speaker 1: about people, right, I wonder about that sometimes, you know, 449 00:21:12,760 --> 00:21:15,440 Speaker 1: how do you count somebody's age if they're If somebody 450 00:21:15,520 --> 00:21:19,040 Speaker 1: is born premature, they're older. You know, even then somebody 451 00:21:19,040 --> 00:21:21,080 Speaker 1: who was born it was conceived at the same moment 452 00:21:21,119 --> 00:21:24,120 Speaker 1: but then born at full term. So even the age 453 00:21:24,119 --> 00:21:26,080 Speaker 1: of people is sort of hard to define sometimes. 454 00:21:26,200 --> 00:21:29,520 Speaker 3: All right, well, we've determined, we've determined what we mean 455 00:21:29,560 --> 00:21:31,080 Speaker 3: by the age of the Earth, and so now let's 456 00:21:31,080 --> 00:21:34,600 Speaker 3: get into how we know how old Earth is and 457 00:21:34,400 --> 00:21:36,879 Speaker 3: what that means. But first let's take a quick break. 458 00:21:41,480 --> 00:21:44,439 Speaker 1: With big wireless providers, what you see is never what 459 00:21:44,520 --> 00:21:47,200 Speaker 1: you get. Somewhere between the store and your first month's bill, 460 00:21:47,240 --> 00:21:50,280 Speaker 1: the price you thought you were paying magically skyrockets. 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See 506 00:24:09,520 --> 00:24:19,760 Speaker 1: terms and more at applecar dot com. 507 00:24:19,920 --> 00:24:22,240 Speaker 3: Okay, so we're defining the age of the Earth is 508 00:24:22,520 --> 00:24:27,760 Speaker 3: how old the oldest rock was formed that we know 509 00:24:27,880 --> 00:24:29,160 Speaker 3: about right on Earth. 510 00:24:29,160 --> 00:24:30,080 Speaker 1: That's right exactly. 511 00:24:30,480 --> 00:24:32,440 Speaker 3: Let's say, so when the Earth was like a ball 512 00:24:32,480 --> 00:24:35,920 Speaker 3: of lava, that doesn't count, but once it started solidifying, 513 00:24:36,400 --> 00:24:38,960 Speaker 3: then we're saying that's when the Earth was born. 514 00:24:39,080 --> 00:24:42,760 Speaker 1: Yeah, exactly, because we're imagining that. Yeah, we're imagining that 515 00:24:42,800 --> 00:24:45,080 Speaker 1: the formation of the Earth probably melted a lot of 516 00:24:45,080 --> 00:24:47,600 Speaker 1: the rocks because it was this early lava period as 517 00:24:47,600 --> 00:24:50,160 Speaker 1: you as you mentioned, and so as it's cooled down 518 00:24:50,200 --> 00:24:52,760 Speaker 1: and formed the crust, then it made rocks. And it 519 00:24:52,800 --> 00:24:56,080 Speaker 1: turns out we can figure out how old a rock is, 520 00:24:56,600 --> 00:24:59,200 Speaker 1: and so that's really our best handle in figuring out 521 00:24:59,200 --> 00:25:00,960 Speaker 1: how old the Earth is. And in the end, it's 522 00:25:01,000 --> 00:25:03,360 Speaker 1: a lower bound, right we say, well, here's an old, 523 00:25:03,400 --> 00:25:05,440 Speaker 1: super old rock on the Earth, so the earth must 524 00:25:05,440 --> 00:25:07,000 Speaker 1: be at least that old. 525 00:25:07,000 --> 00:25:09,199 Speaker 3: Because like we've talked about it, like you mentioned like 526 00:25:10,200 --> 00:25:12,520 Speaker 3: trying to figure out how old the earth is. The 527 00:25:12,560 --> 00:25:14,359 Speaker 3: only thing we can do is sort of look around 528 00:25:14,400 --> 00:25:16,720 Speaker 3: and see how old the things in it are, right, 529 00:25:16,760 --> 00:25:18,960 Speaker 3: and like, what's the oldest thing in it? We know 530 00:25:19,000 --> 00:25:20,160 Speaker 3: it has to be at least that old. 531 00:25:20,280 --> 00:25:23,600 Speaker 1: Yeah, yeah, exactly. That's about all we can do. And 532 00:25:23,640 --> 00:25:25,439 Speaker 1: you know what you can do otherwise to sort of 533 00:25:25,720 --> 00:25:28,159 Speaker 1: form a theory. You say, I have a concept for 534 00:25:28,240 --> 00:25:31,080 Speaker 1: how this might have worked, and then you can fit 535 00:25:31,160 --> 00:25:33,439 Speaker 1: data to it and say, well, I expect, you know, 536 00:25:33,960 --> 00:25:35,840 Speaker 1: to see these sort of rocks in that case, and 537 00:25:35,880 --> 00:25:37,879 Speaker 1: you can use that a theory to sort of extrapolate 538 00:25:37,880 --> 00:25:41,160 Speaker 1: a little bit past the data you observe. But that's 539 00:25:41,320 --> 00:25:44,800 Speaker 1: very but that's speculative, right, It's based on your concept 540 00:25:44,840 --> 00:25:47,520 Speaker 1: for how things happen. So the hardest number, the one 541 00:25:47,520 --> 00:25:50,040 Speaker 1: that you know best, is the oldest thing that you 542 00:25:50,080 --> 00:25:53,200 Speaker 1: can find. And the oldest thing we find our rocks. 543 00:25:53,520 --> 00:25:55,920 Speaker 1: And so what we do is we try to turn 544 00:25:56,000 --> 00:25:58,399 Speaker 1: one question into another question. The question we can answer 545 00:25:58,480 --> 00:26:01,440 Speaker 1: is what's the age of the oldest rock on the Earth. 546 00:26:01,640 --> 00:26:04,440 Speaker 3: Wouldn't that tell us like if we found a really 547 00:26:04,480 --> 00:26:07,359 Speaker 3: old rock, what if that rock came from before the 548 00:26:07,400 --> 00:26:09,040 Speaker 3: Earth was formed? Do you know what I mean? 549 00:26:09,200 --> 00:26:12,800 Speaker 1: Yeah, Yeah, there are some of those actually, like meteorites, Right, 550 00:26:13,119 --> 00:26:16,480 Speaker 1: meteorites tell us the age of the Solar system, because 551 00:26:16,520 --> 00:26:18,960 Speaker 1: we think meteorites were formed in the beginning of the 552 00:26:18,960 --> 00:26:22,480 Speaker 1: Solar system. Right, the first stage is gathered together gas 553 00:26:22,480 --> 00:26:26,120 Speaker 1: and dust into rocks, right, And so those rocks from 554 00:26:26,119 --> 00:26:28,000 Speaker 1: space tell us the age of the Solar System. But 555 00:26:28,480 --> 00:26:31,320 Speaker 1: we can tell which rocks came from space and which 556 00:26:31,400 --> 00:26:34,360 Speaker 1: rocks are from Earth, and so we can distinguish those two. 557 00:26:35,760 --> 00:26:36,440 Speaker 3: How can we tell? 558 00:26:36,720 --> 00:26:39,320 Speaker 1: Oh, they're clearly labeled, you know, they have they have 559 00:26:39,359 --> 00:26:42,440 Speaker 1: they ever turn address? Right that says somewhere near Neptune. 560 00:26:44,200 --> 00:26:47,439 Speaker 1: It's it's actually quite interesting. The sort of the distribution 561 00:26:47,560 --> 00:26:50,920 Speaker 1: of metals in these rocks is very different for meteorites 562 00:26:51,160 --> 00:26:52,720 Speaker 1: than it is for rocks on the Earth. 563 00:26:52,800 --> 00:26:55,320 Speaker 3: Oh I see, Yeah, it's like a different group of rocks. 564 00:26:55,359 --> 00:26:57,320 Speaker 1: Yeah, It's like they have more nickel in them where 565 00:26:57,320 --> 00:26:59,920 Speaker 1: they have this other rare stuff. And that's a whole 566 00:27:00,040 --> 00:27:03,760 Speaker 1: they're fascinating field. And also so these rocks are different 567 00:27:03,800 --> 00:27:05,439 Speaker 1: from Earth, and they tell us like what else is 568 00:27:05,440 --> 00:27:07,440 Speaker 1: out there in the Solar System and what was out 569 00:27:07,440 --> 00:27:09,399 Speaker 1: there when the Solar System was formed. They're like little 570 00:27:09,400 --> 00:27:12,359 Speaker 1: time capsules from the very beginning of the Solar System, 571 00:27:12,560 --> 00:27:14,679 Speaker 1: and they actually tell us another interesting story. Right, So 572 00:27:14,760 --> 00:27:17,080 Speaker 1: those rocks, we can tell how old they are, and 573 00:27:17,160 --> 00:27:19,719 Speaker 1: they tell us how old the Solar System is. So 574 00:27:19,760 --> 00:27:21,560 Speaker 1: we can answer two questions. We can find a bunch 575 00:27:21,600 --> 00:27:23,320 Speaker 1: of rocks. We can say, oh, these came from somewhere 576 00:27:23,320 --> 00:27:25,840 Speaker 1: in the Solar System. They're x y z old. These 577 00:27:25,920 --> 00:27:28,960 Speaker 1: rocks are here on Earth. They're only you know, ABC old. 578 00:27:29,000 --> 00:27:30,639 Speaker 3: All right. So then so it all comes down to 579 00:27:30,680 --> 00:27:32,320 Speaker 3: the question of how do you tell how old the 580 00:27:32,400 --> 00:27:32,840 Speaker 3: rock is? 581 00:27:33,000 --> 00:27:36,440 Speaker 1: Yeah, right, exactly exactly, or a meteorite, which is the same, 582 00:27:36,480 --> 00:27:38,280 Speaker 1: which is the same because a meteorite is just basically 583 00:27:38,320 --> 00:27:40,800 Speaker 1: a rock from space that landed on Earth. And the 584 00:27:40,800 --> 00:27:43,880 Speaker 1: way we do it is something called radiometric dating, which 585 00:27:43,920 --> 00:27:47,600 Speaker 1: is not the same as carbon dating, right, but it works. 586 00:27:47,720 --> 00:27:50,520 Speaker 3: Which is not the same as online dating either. 587 00:27:50,920 --> 00:27:52,479 Speaker 1: It turns out to be actually kind of similar. 588 00:27:52,480 --> 00:27:54,560 Speaker 3: There's a lot of swiping, there's a lot of lying 589 00:27:54,560 --> 00:27:56,160 Speaker 3: about your age, as well. 590 00:28:00,040 --> 00:28:03,480 Speaker 1: So carbon dating and radiometric dating have similar principles, and 591 00:28:03,520 --> 00:28:05,520 Speaker 1: we should have a whole podcast episode about how carbon 592 00:28:05,560 --> 00:28:09,240 Speaker 1: dating works. Carbon dating relates to organic stuff like living beings. 593 00:28:09,560 --> 00:28:12,800 Speaker 1: Radiometric dating relates to how old rocks are. 594 00:28:13,080 --> 00:28:15,560 Speaker 3: Okay, so you find a rock and you're you're staring 595 00:28:15,600 --> 00:28:17,760 Speaker 3: at it, and you're like, I wonder when this rock 596 00:28:17,920 --> 00:28:21,080 Speaker 3: became a rock? Yeah, exactly when this turned from lava 597 00:28:21,600 --> 00:28:25,000 Speaker 3: to this heavy thing that I'm holding, And so we 598 00:28:25,040 --> 00:28:27,200 Speaker 3: can actually tell yeah, right, we can look at the 599 00:28:27,200 --> 00:28:29,399 Speaker 3: stuff in it and tell how old when it was formed? 600 00:28:29,480 --> 00:28:31,560 Speaker 3: How many millions of years ago? 601 00:28:32,040 --> 00:28:34,639 Speaker 1: Its cool exactly. And I have so much respect for 602 00:28:34,720 --> 00:28:37,439 Speaker 1: scientists who developed these techniques. You know, they look at 603 00:28:37,480 --> 00:28:39,200 Speaker 1: a rock and they say, I want to know how 604 00:28:39,200 --> 00:28:41,880 Speaker 1: old this rock is? How could I tell? Can I 605 00:28:41,960 --> 00:28:44,840 Speaker 1: find something inside the rock that I can use as 606 00:28:44,880 --> 00:28:48,960 Speaker 1: a clock, something which changes reliably and steadily every year, 607 00:28:49,360 --> 00:28:52,440 Speaker 1: so that I can like count it and project back 608 00:28:52,440 --> 00:28:55,400 Speaker 1: and figure out when that clock started or something. And 609 00:28:55,480 --> 00:28:56,560 Speaker 1: this is hard to do. 610 00:28:56,720 --> 00:28:56,920 Speaker 3: You know. 611 00:28:57,000 --> 00:28:59,840 Speaker 1: You have to find something which is steady and rely 612 00:29:00,320 --> 00:29:03,440 Speaker 1: and can be calibrated. It's not trivial, right, You can't 613 00:29:03,480 --> 00:29:05,400 Speaker 1: just say oh, I'm just going a measure X Y 614 00:29:05,520 --> 00:29:08,240 Speaker 1: z property. You have to invent these techniques and it 615 00:29:08,280 --> 00:29:11,120 Speaker 1: takes time and sweat and tears, and so I have 616 00:29:11,160 --> 00:29:14,160 Speaker 1: so much respect for folks who did this. And and 617 00:29:14,240 --> 00:29:15,800 Speaker 1: in the case of rocks, it turns out to be 618 00:29:15,880 --> 00:29:19,160 Speaker 1: very dependent on the special kind of mineral called zircon. 619 00:29:19,080 --> 00:29:26,120 Speaker 3: Zircon like the fake diamond. 620 00:29:21,400 --> 00:29:26,600 Speaker 1: Like, Yeah, it's related exactly. Zirconium and zircon is a 621 00:29:26,600 --> 00:29:30,120 Speaker 1: special kind of mineral. And it's special because it has 622 00:29:30,160 --> 00:29:33,840 Speaker 1: two properties. One, it likes it's a crystal, and it 623 00:29:34,000 --> 00:29:37,440 Speaker 1: likes to absorb uranium into it. Right, it gobbles up uranium. 624 00:29:37,440 --> 00:29:40,080 Speaker 1: So when the rock forms, if it has some zircon 625 00:29:40,120 --> 00:29:42,840 Speaker 1: in it, then it will grab any uranium that's around it. 626 00:29:43,160 --> 00:29:44,720 Speaker 1: And the second important. 627 00:29:44,360 --> 00:29:47,560 Speaker 3: Property, But wait, what is zircon made out of? Is it? 628 00:29:47,680 --> 00:29:47,720 Speaker 4: What? 629 00:29:48,120 --> 00:29:50,880 Speaker 3: Is it like a made out of iron? Or what 630 00:29:50,960 --> 00:29:54,400 Speaker 3: is carbon? What is this mineral made out I think it's. 631 00:29:54,280 --> 00:30:01,280 Speaker 1: Made out of leftover desserts. No, it's it's a mineral. 632 00:30:01,880 --> 00:30:05,800 Speaker 1: It's made out of zirconium and silicon and oxygen. 633 00:30:06,040 --> 00:30:09,840 Speaker 3: Oh, so zirconium is like an element like carbon or iron. 634 00:30:09,960 --> 00:30:12,800 Speaker 1: Yes, zirconium is an element and it's sort of like 635 00:30:12,800 --> 00:30:16,880 Speaker 1: a silver metal. It's atomic number forty. You know, doesn't 636 00:30:16,920 --> 00:30:18,920 Speaker 1: really play a lot of roles and stuff other than 637 00:30:18,920 --> 00:30:21,280 Speaker 1: like cubic zirconium. It's not like a famous metal like 638 00:30:21,320 --> 00:30:24,280 Speaker 1: some of its friends and neighbors. But it plays an 639 00:30:24,280 --> 00:30:26,080 Speaker 1: important role in aging rocks. 640 00:30:26,280 --> 00:30:29,400 Speaker 3: So this element is all around us in all the rocks, 641 00:30:29,440 --> 00:30:33,160 Speaker 3: and it forms a special crystal. You're saying that when 642 00:30:33,160 --> 00:30:36,640 Speaker 3: it forms it likes to capture uranium. 643 00:30:36,680 --> 00:30:40,120 Speaker 1: That's right. It captures uranium and it rejects lead. So 644 00:30:40,200 --> 00:30:43,000 Speaker 1: the moment that the rock is created, it creates a 645 00:30:43,080 --> 00:30:46,280 Speaker 1: special thing, which is zircon with just uranium in it. 646 00:30:46,400 --> 00:30:49,960 Speaker 1: And you might wonder, like, well, how is that helpful? Right? Well, uranium, 647 00:30:50,000 --> 00:30:52,600 Speaker 1: as you might know, is radioactive. It doesn't just sit 648 00:30:52,680 --> 00:30:57,200 Speaker 1: around and stay uranium forever. It very reliably decays and 649 00:30:57,240 --> 00:30:58,760 Speaker 1: it decays into lead. 650 00:30:59,120 --> 00:31:02,600 Speaker 3: But wait, why does or cercon like uranium in white, 651 00:31:02,640 --> 00:31:05,320 Speaker 3: doesn't it? You mean, like when it forms the crystals, 652 00:31:05,520 --> 00:31:08,440 Speaker 3: it forms a little structure and it just it just 653 00:31:08,720 --> 00:31:12,080 Speaker 3: likes uranium, like uranium likes being inside of zircon crystal. 654 00:31:12,120 --> 00:31:13,600 Speaker 1: I mean, I don't want to get in the mind 655 00:31:13,640 --> 00:31:16,000 Speaker 1: of uranium or the mind of zircon. I mean they 656 00:31:16,040 --> 00:31:19,200 Speaker 1: did some carbon dating online and they decided they were 657 00:31:19,200 --> 00:31:23,320 Speaker 1: a good match. But no, no, some chemical, some business 658 00:31:23,360 --> 00:31:25,800 Speaker 1: with the chemical bonds. You know, the way the crystal 659 00:31:25,840 --> 00:31:29,560 Speaker 1: structure of zircon forms fits very nicely with uranium and 660 00:31:29,680 --> 00:31:32,240 Speaker 1: doesn't fit very nicely with lead, right, I see. 661 00:31:32,480 --> 00:31:35,320 Speaker 3: Yeah, So like a rock, I have a bunch of 662 00:31:35,400 --> 00:31:38,640 Speaker 3: lava and it cools and it slowly turns into rock. 663 00:31:38,760 --> 00:31:42,040 Speaker 3: And in that process is when you're saying this crystal form. 664 00:31:41,880 --> 00:31:43,680 Speaker 1: Yeah, and zircon is not. It doesn't have to be 665 00:31:43,720 --> 00:31:45,280 Speaker 1: all over the rock. It's not like a whole rock 666 00:31:45,320 --> 00:31:47,800 Speaker 1: full of zircon. It's just these little chips of zircon. 667 00:31:48,400 --> 00:31:50,440 Speaker 1: And what they do is they repel all the lead 668 00:31:50,480 --> 00:31:54,160 Speaker 1: inside them and they grab some uranium. And your uranium 669 00:31:54,360 --> 00:31:57,880 Speaker 1: is like a clock. It decays very reliably. So every 670 00:31:57,920 --> 00:32:02,320 Speaker 1: million years or so, some uranium turns into lead. And 671 00:32:02,360 --> 00:32:05,640 Speaker 1: so after one million years, some fraction of the uranium 672 00:32:05,640 --> 00:32:09,160 Speaker 1: and then zircon has turned into lead. After two million years, 673 00:32:09,400 --> 00:32:12,640 Speaker 1: another fraction is turned into lead. After a billion years, 674 00:32:12,960 --> 00:32:16,040 Speaker 1: a very predictable fraction is turned into lead. So what 675 00:32:16,120 --> 00:32:18,320 Speaker 1: you do is you take a rock, you look at 676 00:32:18,320 --> 00:32:21,400 Speaker 1: that you find some zircon crystals and you ask how 677 00:32:21,480 --> 00:32:23,560 Speaker 1: much of the uranium has turned into lead, and that 678 00:32:23,600 --> 00:32:26,760 Speaker 1: tells you how much time it's had to turn into lead. 679 00:32:26,960 --> 00:32:29,520 Speaker 3: It's kind of like a like an aging process, right, 680 00:32:29,560 --> 00:32:31,760 Speaker 3: like wine. Yes, if you leave wine there, it's going 681 00:32:31,840 --> 00:32:36,280 Speaker 3: to change. It's characteristic exactly, It's going to change into 682 00:32:36,280 --> 00:32:37,000 Speaker 3: something else. 683 00:32:36,880 --> 00:32:39,120 Speaker 1: Exactly, and you need That's why it works so well 684 00:32:39,120 --> 00:32:41,640 Speaker 1: as a clock, because uranium is something that we know reliably. 685 00:32:41,680 --> 00:32:43,680 Speaker 1: We understand it, we know how it decays, we know 686 00:32:43,720 --> 00:32:46,680 Speaker 1: how long it takes. We know you know, after one 687 00:32:46,760 --> 00:32:49,840 Speaker 1: hundred thousand years what fraction of uranium atoms will turn 688 00:32:49,880 --> 00:32:52,440 Speaker 1: into lead. And the other key thing, of course is 689 00:32:52,480 --> 00:32:54,320 Speaker 1: that it starts with a blank slate. That when you 690 00:32:54,360 --> 00:32:57,240 Speaker 1: form these zircon crystals, it rejects lead. Right, So you 691 00:32:57,280 --> 00:33:00,480 Speaker 1: start out like with an empty bucket, and then slowly 692 00:33:00,560 --> 00:33:03,280 Speaker 1: the uranium bucket fills the lead bucket, and so you 693 00:33:03,320 --> 00:33:06,080 Speaker 1: can just measure the uranium lead fraction and that tells 694 00:33:06,120 --> 00:33:09,640 Speaker 1: you how long the uranium has been turning into lead. 695 00:33:09,680 --> 00:33:12,800 Speaker 1: It's really amazing. It's really just chance that this happens 696 00:33:12,840 --> 00:33:14,120 Speaker 1: and that somebody figured this out. 697 00:33:14,240 --> 00:33:16,440 Speaker 3: So like if you find a rock and you find 698 00:33:16,440 --> 00:33:20,840 Speaker 3: the little little zircon chip inside of it, and it's like, 699 00:33:21,200 --> 00:33:23,360 Speaker 3: let's say it's full of uranium, then you know it's 700 00:33:23,360 --> 00:33:26,040 Speaker 3: a pretty new rock exactly. But if it's full of lead, 701 00:33:26,120 --> 00:33:28,200 Speaker 3: then you know it's really old rock exactly. 702 00:33:28,280 --> 00:33:32,960 Speaker 1: It's exactly right. So rockstart start out pure uranium, no lead, 703 00:33:33,360 --> 00:33:36,280 Speaker 1: and then as they age, the uranium turns into lead. 704 00:33:36,360 --> 00:33:39,040 Speaker 1: And so a rock with almost no uranium is going 705 00:33:39,080 --> 00:33:42,600 Speaker 1: to be like super duper old, right, and new lead 706 00:33:42,680 --> 00:33:45,840 Speaker 1: can't just come in from the outside because now it's crystallized, right, 707 00:33:46,280 --> 00:33:48,840 Speaker 1: it's hard for lead to get in any other way. 708 00:33:49,000 --> 00:33:50,720 Speaker 1: All The only way you can get lead inside the 709 00:33:50,760 --> 00:33:53,000 Speaker 1: zircon is for uranium to turn into lead. 710 00:33:53,280 --> 00:33:55,920 Speaker 3: So the rock sort of you might say, like it 711 00:33:56,040 --> 00:34:00,840 Speaker 3: spoils or it ages by looking at that. Yeah, it 712 00:34:00,920 --> 00:34:02,120 Speaker 3: turns into leads. 713 00:34:02,040 --> 00:34:05,719 Speaker 1: Right exactly. And whether it spoils or ages beautifully depends 714 00:34:05,760 --> 00:34:08,160 Speaker 1: on you know, your preference for how rock's taste. 715 00:34:08,200 --> 00:34:10,680 Speaker 3: I suppose whether U swype bright or left for rocks. 716 00:34:10,760 --> 00:34:12,400 Speaker 1: Right. But you know, it took a long time to 717 00:34:12,400 --> 00:34:15,920 Speaker 1: figure this out. People tried all sorts of other strategies 718 00:34:15,920 --> 00:34:18,600 Speaker 1: first before they discovered this one. And there's lots of 719 00:34:18,600 --> 00:34:22,640 Speaker 1: scientific careers and phdpcs that were frustrated in people trying 720 00:34:22,640 --> 00:34:25,280 Speaker 1: to figure out a way to do radiometric dating before 721 00:34:25,280 --> 00:34:27,080 Speaker 1: people stumbled onto this one. 722 00:34:27,200 --> 00:34:28,920 Speaker 3: Wow, and this is not one of these things that 723 00:34:29,000 --> 00:34:32,960 Speaker 3: you have to calibrate, right because I imagine you have 724 00:34:33,200 --> 00:34:40,799 Speaker 3: probably very scientific information about the decay of uranium, right, 725 00:34:40,840 --> 00:34:43,880 Speaker 3: like it's very physics space like, you don't have to 726 00:34:43,920 --> 00:34:45,680 Speaker 3: calibrate it to anything else, do you. 727 00:34:45,400 --> 00:34:48,440 Speaker 1: You're right, And we can basically use simple physics arguments 728 00:34:48,480 --> 00:34:51,879 Speaker 1: to argue how long uranium takes to decay into lead, 729 00:34:52,320 --> 00:34:56,400 Speaker 1: and so it gives us pretty clear descriptions, but you know, 730 00:34:56,440 --> 00:34:59,719 Speaker 1: we also want to get confidence in it, and so 731 00:35:00,000 --> 00:35:03,800 Speaker 1: people do that have various other sort of radiometric methods, 732 00:35:03,840 --> 00:35:06,759 Speaker 1: not just uranium to lead, but other stuff, things that 733 00:35:06,960 --> 00:35:09,759 Speaker 1: decay faster, things that decay slower, and so you can 734 00:35:09,840 --> 00:35:12,719 Speaker 1: use those to sort of cross calibrate. But uranium to 735 00:35:12,800 --> 00:35:15,120 Speaker 1: lead is sort of the cleanest one. But you know, 736 00:35:15,200 --> 00:35:17,160 Speaker 1: like everywhere in science, you want to check everything three 737 00:35:17,160 --> 00:35:20,240 Speaker 1: different ways and then make sure you get consistent answers. 738 00:35:20,400 --> 00:35:22,560 Speaker 3: All right, that's pretty cool. That's how we can tell 739 00:35:22,600 --> 00:35:26,560 Speaker 3: how old the rock is. Then rock can't lie. It 740 00:35:26,600 --> 00:35:27,840 Speaker 3: can't lie about its age. 741 00:35:28,440 --> 00:35:31,040 Speaker 1: That's right, that's right. You can lie, but we'll know 742 00:35:31,160 --> 00:35:31,480 Speaker 1: you are. 743 00:35:31,560 --> 00:35:33,560 Speaker 3: All right, Let's get into the as right now, Daniel, 744 00:35:33,560 --> 00:35:36,880 Speaker 3: how old Earth is and how old the solar system is. 745 00:35:36,920 --> 00:35:39,080 Speaker 3: But first, let's take another quick break. 746 00:35:43,400 --> 00:35:45,200 Speaker 1: When you pop a piece of cheese into your mouth 747 00:35:45,320 --> 00:35:48,440 Speaker 1: or enjoy a rich spoonful of Greek yogurt, you're probably 748 00:35:48,480 --> 00:35:52,520 Speaker 1: not thinking about the environmental impact of each and every bite. 749 00:35:52,560 --> 00:35:55,200 Speaker 1: But the people in the dairy industry are. US Dairy 750 00:35:55,239 --> 00:35:59,520 Speaker 1: has set themselves some ambitious sustainability goals, including being greenhouse 751 00:35:59,520 --> 00:36:02,120 Speaker 1: gas news by twenty to fifty. That's why they're working 752 00:36:02,160 --> 00:36:04,479 Speaker 1: hard every day to find new ways to reduce waste, 753 00:36:04,560 --> 00:36:08,799 Speaker 1: conserve natural resources, and drive down greenhouse gas emissions. Take water, 754 00:36:08,840 --> 00:36:11,920 Speaker 1: for example, most dairy farms reuse water up to four 755 00:36:11,960 --> 00:36:15,440 Speaker 1: times the same water cools the milk, cleans equipment, washes 756 00:36:15,480 --> 00:36:18,280 Speaker 1: the barn, and irrigates the crops. How is US dairy 757 00:36:18,320 --> 00:36:22,040 Speaker 1: tackling greenhouse gases? Many farms use anaerobic digestors that turn 758 00:36:22,080 --> 00:36:26,000 Speaker 1: the methane from maneuver into renewable energy that can power farms, towns, 759 00:36:26,040 --> 00:36:28,120 Speaker 1: and electric cars. So the next time you grab a 760 00:36:28,120 --> 00:36:30,160 Speaker 1: slice of pizza or lick an ice cream cone. Know 761 00:36:30,239 --> 00:36:32,919 Speaker 1: that dairy farmers and processors around the country are using 762 00:36:32,960 --> 00:36:36,439 Speaker 1: the latest practices and innovations to provide the nutrient dense 763 00:36:36,560 --> 00:36:39,279 Speaker 1: dairy products we love with less of an impact. Visit 764 00:36:39,360 --> 00:36:42,160 Speaker 1: us dairy dot com slash sustainability to learn more. 765 00:36:42,360 --> 00:36:46,000 Speaker 4: With the United Explorer Card, earn fifty thousand bonus miles, 766 00:36:46,160 --> 00:36:49,560 Speaker 4: then head for places unseen and destinations unknown. 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Strengthen your 786 00:37:48,120 --> 00:37:51,719 Speaker 7: home and help protect your family. Get prepared today and 787 00:37:51,800 --> 00:38:05,160 Speaker 7: worry less tomorrow. Visit strengthen your House dot Com. 788 00:38:05,200 --> 00:38:07,600 Speaker 3: All right, Daniel, let's let's break it down for people. 789 00:38:07,600 --> 00:38:11,280 Speaker 3: How old is the Earth, or at least the oldest 790 00:38:11,360 --> 00:38:11,920 Speaker 3: rocks on Earth? 791 00:38:12,000 --> 00:38:15,319 Speaker 1: Yeah, the oldest rocks on Earth come from Australia. And 792 00:38:15,360 --> 00:38:17,040 Speaker 1: I don't know why, but that's not surprising to me. 793 00:38:17,080 --> 00:38:20,040 Speaker 1: It seems like Australia is the land of extremes, and 794 00:38:20,120 --> 00:38:23,360 Speaker 1: so you'd expect the craziest, weirdest, oldest rock to be 795 00:38:23,400 --> 00:38:24,200 Speaker 1: in Australia. 796 00:38:24,480 --> 00:38:28,600 Speaker 3: And they have the biggest spiders, the biggest crocodiles, and 797 00:38:29,360 --> 00:38:30,400 Speaker 3: the oldest. 798 00:38:30,040 --> 00:38:31,640 Speaker 1: Rocks, the deadliest everything. 799 00:38:31,400 --> 00:38:34,840 Speaker 3: The biggest best stars, it seems, and the best podcast 800 00:38:34,920 --> 00:38:35,600 Speaker 3: listening fans. 801 00:38:35,680 --> 00:38:35,799 Speaker 6: Right. 802 00:38:36,800 --> 00:38:39,000 Speaker 1: No, we got a lot of good email questions from Australia. 803 00:38:39,080 --> 00:38:41,719 Speaker 1: But the oldest rock on Earth come from the jack 804 00:38:41,840 --> 00:38:45,680 Speaker 1: Hills of Australia and it's four point zero four billion 805 00:38:45,840 --> 00:38:46,520 Speaker 1: years old. 806 00:38:46,719 --> 00:38:49,279 Speaker 3: So these are rocks that we do we have to 807 00:38:49,320 --> 00:38:51,680 Speaker 3: dig up for them, dig for them or are they 808 00:38:51,680 --> 00:38:54,120 Speaker 3: were they pretty close to the surface or. 809 00:38:54,239 --> 00:38:56,680 Speaker 1: Yeah, it's it's fascinating. Actually these rocks just sort of 810 00:38:56,719 --> 00:39:00,319 Speaker 1: sit on outcrops and people recently discovered that they have 811 00:39:00,520 --> 00:39:03,160 Speaker 1: that the oldest rocks are there, and you know it's 812 00:39:03,880 --> 00:39:06,640 Speaker 1: the Earth itself of course, has had lots of geologic 813 00:39:06,680 --> 00:39:09,279 Speaker 1: activity and so some of these really old rocks get 814 00:39:09,320 --> 00:39:11,960 Speaker 1: buried and then there's geological activity that brings them up 815 00:39:11,960 --> 00:39:13,960 Speaker 1: to the surface, and so it just happens to be 816 00:39:14,480 --> 00:39:17,480 Speaker 1: at this spot on the Earth, these really old rocks 817 00:39:17,520 --> 00:39:20,440 Speaker 1: got pushed up and so they're not that far underground. 818 00:39:20,440 --> 00:39:23,400 Speaker 1: They're on this outcropping of rocks in Western Australia. 819 00:39:23,440 --> 00:39:25,319 Speaker 3: But you almost kind of expect them to be close 820 00:39:25,360 --> 00:39:28,040 Speaker 3: to the surface, right because that's you know, I would 821 00:39:28,080 --> 00:39:30,600 Speaker 3: imagine that if we were once a ball of lava, 822 00:39:30,719 --> 00:39:33,560 Speaker 3: then the stuff sort of cools from the outside inwards. 823 00:39:33,640 --> 00:39:35,520 Speaker 1: That's true, but you know, then there's all these sedimentary 824 00:39:35,520 --> 00:39:39,000 Speaker 1: processes right where old things get buried. But then there's 825 00:39:39,000 --> 00:39:41,440 Speaker 1: tectonic activity and all sorts of other crazy stuff that 826 00:39:41,520 --> 00:39:44,880 Speaker 1: brings stuff up and mixes everything around. So there's a 827 00:39:44,920 --> 00:39:46,239 Speaker 1: lot of stuff going on there. I think it's not 828 00:39:46,360 --> 00:39:49,360 Speaker 1: that simple. But in the end, the oldest thing we 829 00:39:49,440 --> 00:39:53,040 Speaker 1: found on Earth is almost four and a half billion 830 00:39:53,120 --> 00:39:56,400 Speaker 1: years old. It's four billion, four hundred and four million 831 00:39:56,520 --> 00:39:59,200 Speaker 1: years old. And you know, that's a staggering answer. It's 832 00:39:59,239 --> 00:40:01,040 Speaker 1: hard to really comprehend what that means. 833 00:40:01,320 --> 00:40:05,600 Speaker 3: For billion years old, that's a lot. 834 00:40:05,719 --> 00:40:09,560 Speaker 1: It's a lot of dessert parties. Yeah, I mean, if. 835 00:40:09,400 --> 00:40:10,960 Speaker 3: Their history was a lot of party missed. 836 00:40:11,239 --> 00:40:13,080 Speaker 1: Yeah, I think. I think what you said earlier about 837 00:40:13,080 --> 00:40:15,560 Speaker 1: how we came to the party pretty late. It's sort 838 00:40:15,560 --> 00:40:17,479 Speaker 1: of shocking. You know, the first people to like learn 839 00:40:17,560 --> 00:40:19,880 Speaker 1: these numbers, to know that the Earth was billions of 840 00:40:20,000 --> 00:40:22,839 Speaker 1: years old. It must have made humans feel sort of 841 00:40:23,200 --> 00:40:27,480 Speaker 1: small and recent and and you know, maybe transient, right, 842 00:40:27,560 --> 00:40:29,680 Speaker 1: Like the Earth has had a long history and we 843 00:40:29,760 --> 00:40:31,640 Speaker 1: are only the very last little bit of it. 844 00:40:31,920 --> 00:40:34,680 Speaker 3: Yeah, I mean it's a difference between I mean human 845 00:40:34,760 --> 00:40:37,680 Speaker 3: history is maybe what like ten twenty thousand years. 846 00:40:37,480 --> 00:40:40,240 Speaker 1: Old, yeah, one hundred thousand. If you're really generous. 847 00:40:40,880 --> 00:40:44,040 Speaker 3: Yeah, but the Earth has been around for four point four. 848 00:40:43,960 --> 00:40:47,759 Speaker 1: Billion years old exactly. It's not too impressed. It's been there, 849 00:40:47,800 --> 00:40:50,120 Speaker 1: It's seen a lot of stuff. You know, it'll be 850 00:40:50,160 --> 00:40:52,960 Speaker 1: here when we're done. You know, people always talk about 851 00:40:52,960 --> 00:40:55,399 Speaker 1: how humans going to destroy the Earth, and I don't 852 00:40:55,440 --> 00:40:58,759 Speaker 1: think that's likely. I think the humans might destroy ourselves 853 00:40:58,880 --> 00:41:01,160 Speaker 1: or life on Earth, but the Earth will be here 854 00:41:01,320 --> 00:41:02,080 Speaker 1: when we're done. 855 00:41:02,200 --> 00:41:04,719 Speaker 3: Unless I hear some physicists are trying to make black 856 00:41:04,760 --> 00:41:06,840 Speaker 3: holes down at the Large Patron Collider. 857 00:41:07,280 --> 00:41:09,200 Speaker 1: Yeah, but we just want to understand the universe. Man, 858 00:41:09,280 --> 00:41:12,400 Speaker 1: We're not threatening the world. There's no danger there. Trust me. 859 00:41:12,680 --> 00:41:14,680 Speaker 1: And can I have ten more billion dollars to build 860 00:41:14,680 --> 00:41:15,279 Speaker 1: a bigger. 861 00:41:15,000 --> 00:41:19,960 Speaker 3: One one year for every one dollar for every year 862 00:41:20,000 --> 00:41:20,879 Speaker 3: that the Earth has been away? 863 00:41:21,080 --> 00:41:23,680 Speaker 1: Yeah, that's right, that sounds good. But you know, that's 864 00:41:23,719 --> 00:41:26,480 Speaker 1: the oldest rock on Earth that we think is part 865 00:41:26,560 --> 00:41:29,080 Speaker 1: of the Earth. It was part of the formation of 866 00:41:29,120 --> 00:41:31,359 Speaker 1: the Earth. But of course we have found rocks on 867 00:41:31,400 --> 00:41:34,480 Speaker 1: Earth that are meteorites, right, that came from space, that 868 00:41:34,560 --> 00:41:36,400 Speaker 1: are older than the Earth itself. 869 00:41:36,600 --> 00:41:38,680 Speaker 3: So late comers to the party. 870 00:41:38,520 --> 00:41:40,920 Speaker 1: That's right, they heard there was something cool happening down here. 871 00:41:40,960 --> 00:41:43,600 Speaker 1: In the third rock from the Sun and they've fell 872 00:41:43,640 --> 00:41:46,480 Speaker 1: on in to figure it out. And those rocks are 873 00:41:46,680 --> 00:41:50,480 Speaker 1: four point five six billion years old, So that's like 874 00:41:50,680 --> 00:41:53,840 Speaker 1: one hundred and fifty million years older than the oldest 875 00:41:53,960 --> 00:41:54,680 Speaker 1: rocks on Earth. 876 00:41:54,880 --> 00:41:58,080 Speaker 3: That's the oldest meteorite that we found. And I think 877 00:41:58,080 --> 00:42:00,799 Speaker 3: that you were saying that that kind of tells what 878 00:42:00,880 --> 00:42:04,400 Speaker 3: the oldest meteorite right at all is in our solar system, right. 879 00:42:04,320 --> 00:42:06,680 Speaker 1: Yeah, using the same logic, this is the oldest thing 880 00:42:06,719 --> 00:42:09,080 Speaker 1: we found. Yeah, so it's probably the sort of the 881 00:42:09,120 --> 00:42:11,320 Speaker 1: age of the solar system. Right, that's when we think 882 00:42:11,600 --> 00:42:14,919 Speaker 1: the gas and the dust got accumulated together to form 883 00:42:14,960 --> 00:42:17,440 Speaker 1: the Sun and the planets and all that stuff. But 884 00:42:17,480 --> 00:42:19,640 Speaker 1: the first stage of that was to form smaller rocks, 885 00:42:19,640 --> 00:42:22,920 Speaker 1: and so we think these things are remnants of those times. 886 00:42:23,160 --> 00:42:25,359 Speaker 3: Right, But wait, didn't the sun? Hasn't the Sun? Our 887 00:42:25,400 --> 00:42:27,440 Speaker 3: Sun already been through a couple of cycles, like as 888 00:42:27,480 --> 00:42:29,640 Speaker 3: in it exploded a few times already. 889 00:42:29,840 --> 00:42:33,640 Speaker 1: Well, our Sun hasn't exploded, but its materials, right have 890 00:42:33,800 --> 00:42:37,600 Speaker 1: been through several solar cycles. Everything around us, all that 891 00:42:37,640 --> 00:42:40,120 Speaker 1: stuff is left over from one or two or three 892 00:42:40,200 --> 00:42:43,799 Speaker 1: solar cycles of a sun lasting for you know, one, two, 893 00:42:43,920 --> 00:42:46,320 Speaker 1: see three billion years and then blowing up and spreading 894 00:42:46,320 --> 00:42:49,680 Speaker 1: its materials around. So everything around us is all the 895 00:42:49,719 --> 00:42:52,960 Speaker 1: components of the Solar system are probably been recycled. But 896 00:42:53,000 --> 00:42:55,480 Speaker 1: it's not like our sun formed and then we started 897 00:42:55,560 --> 00:42:57,279 Speaker 1: and formed and restarted. It was a different it was 898 00:42:57,360 --> 00:42:58,200 Speaker 1: from a different star. 899 00:42:58,600 --> 00:43:02,400 Speaker 3: Oh I see, So our current sun is maybe around 900 00:43:02,480 --> 00:43:04,239 Speaker 3: four point five billion years old. 901 00:43:04,280 --> 00:43:06,520 Speaker 1: Yeah, that's what we think. That's the history of our 902 00:43:06,560 --> 00:43:09,960 Speaker 1: solar system. And remember, for context, the Milky Way is 903 00:43:09,960 --> 00:43:13,960 Speaker 1: something like thirteen billion years old, and the universe is 904 00:43:14,000 --> 00:43:16,520 Speaker 1: just a little bit older than that, like almost fourteen 905 00:43:16,600 --> 00:43:20,680 Speaker 1: billion years old. So there's a lot of history before 906 00:43:20,800 --> 00:43:23,719 Speaker 1: even our sun, our solar system was formed, and then 907 00:43:23,760 --> 00:43:27,200 Speaker 1: a lot of history before we came around. And so 908 00:43:27,440 --> 00:43:29,880 Speaker 1: like that's the cosmic context that we're standing in. 909 00:43:30,040 --> 00:43:31,680 Speaker 3: And so that's the oldest thing we found in the 910 00:43:31,680 --> 00:43:34,520 Speaker 3: Solar system, but that's older than the oldest thing we 911 00:43:34,640 --> 00:43:37,280 Speaker 3: found that is part of the Earth. So somewhere between 912 00:43:37,280 --> 00:43:39,640 Speaker 3: those two numbers is when maybe the ball of the 913 00:43:39,680 --> 00:43:40,440 Speaker 3: Earth formed. 914 00:43:40,480 --> 00:43:42,319 Speaker 1: That's right, that's what we call the whore Heey date, 915 00:43:43,080 --> 00:43:45,280 Speaker 1: the whore hate definition of the age of the Earth. 916 00:43:45,920 --> 00:43:47,839 Speaker 3: The ball date or his bal date. 917 00:43:48,560 --> 00:43:52,520 Speaker 1: That's right, that's right. And so you know there's a 918 00:43:52,560 --> 00:43:55,080 Speaker 1: window there about one hundred and fifty million years, which 919 00:43:55,120 --> 00:43:57,879 Speaker 1: seems like a huge number. You know, that's like a. 920 00:43:57,920 --> 00:43:59,920 Speaker 3: Hundred company it's pretty small, I think compared to. 921 00:44:00,239 --> 00:44:02,719 Speaker 1: Exactly Geologically speaking, it's a blink of an. 922 00:44:02,640 --> 00:44:06,560 Speaker 3: Eye, yeah, or universe speaking, is it's pretty accurate? 923 00:44:06,840 --> 00:44:10,920 Speaker 1: Yeah, exactly. And you know, we know these numbers two 924 00:44:10,960 --> 00:44:14,000 Speaker 1: plus or minus twenty five or fifty million years based 925 00:44:14,000 --> 00:44:18,640 Speaker 1: on the uncertainty of radiometric dating, and so because of 926 00:44:18,680 --> 00:44:21,200 Speaker 1: the hard work of a lot of scientists to develop 927 00:44:21,239 --> 00:44:23,440 Speaker 1: these things and to cross check them and understand them 928 00:44:23,440 --> 00:44:27,319 Speaker 1: across various other processes. Now we've looked around us and 929 00:44:27,360 --> 00:44:30,480 Speaker 1: we've gathered these clues from everyday objects around us, you know, 930 00:44:30,520 --> 00:44:33,520 Speaker 1: the rocks at our feet, the rocks in Australia give 931 00:44:33,600 --> 00:44:37,320 Speaker 1: us clues about these fantastic numbers that would just blow 932 00:44:37,400 --> 00:44:39,840 Speaker 1: the minds of our ancestors, and those clues we are 933 00:44:39,840 --> 00:44:42,279 Speaker 1: around for them to discover also, And so of course 934 00:44:42,320 --> 00:44:45,120 Speaker 1: that makes you wonder, like what clues are there laying 935 00:44:45,160 --> 00:44:47,920 Speaker 1: around at our feet now that would tell us secrets 936 00:44:47,960 --> 00:44:50,840 Speaker 1: of the universe that our descendants will know and wonder 937 00:44:50,880 --> 00:44:52,200 Speaker 1: why we couldn't figure it out. 938 00:44:52,360 --> 00:44:55,120 Speaker 3: It's not just like an opinion, right, It's pretty based 939 00:44:55,120 --> 00:44:58,400 Speaker 3: on evidence, and it's pretty based on science and physics. 940 00:44:58,760 --> 00:45:01,560 Speaker 1: These numbers, Yeah, exactly, these things we know pretty well. 941 00:45:01,840 --> 00:45:03,400 Speaker 1: We have a lot of confidence in them. People have 942 00:45:03,440 --> 00:45:07,080 Speaker 1: been working on these processes for decades and decades, a 943 00:45:07,120 --> 00:45:10,600 Speaker 1: lot of you know, grumpy competition between rivals to make 944 00:45:10,680 --> 00:45:12,840 Speaker 1: more and more accurate measurements. You know, this is not 945 00:45:12,880 --> 00:45:16,200 Speaker 1: a conspiracy of scientists all working together in harmony. You know, 946 00:45:16,320 --> 00:45:19,359 Speaker 1: this is a bunch of people racing to develop better 947 00:45:19,400 --> 00:45:23,200 Speaker 1: and better techniques and trying to find older and older rocks. Remember, 948 00:45:23,200 --> 00:45:25,680 Speaker 1: science is a competitive field and everybody wants to one 949 00:45:25,760 --> 00:45:28,480 Speaker 1: up the other to get the more accurate, the more reliable, 950 00:45:28,719 --> 00:45:31,279 Speaker 1: the more verifiable answer. So, yeah, we have a lot 951 00:45:31,320 --> 00:45:32,600 Speaker 1: of confidence in this knowledge. 952 00:45:32,719 --> 00:45:34,839 Speaker 3: Yeah, it's like it's all around the evidence is all 953 00:45:34,880 --> 00:45:36,480 Speaker 3: around us, and you're you're standing on it. 954 00:45:36,600 --> 00:45:39,120 Speaker 1: Yeah, exactly. And even if you can't do radiometric dating 955 00:45:39,200 --> 00:45:40,960 Speaker 1: in your head, of course, because you can't see the 956 00:45:41,040 --> 00:45:43,560 Speaker 1: zircon crystals, you know, you just look around you and 957 00:45:43,600 --> 00:45:45,960 Speaker 1: you see lots of things around you which take a 958 00:45:46,040 --> 00:45:48,640 Speaker 1: long time to form. You know, how long does it 959 00:45:48,640 --> 00:45:52,239 Speaker 1: take a mountain to form? It's a very slow process, 960 00:45:52,640 --> 00:45:54,600 Speaker 1: and so all around us on the Earth we see 961 00:45:54,640 --> 00:45:58,440 Speaker 1: evidence of very very slow processes which have accomplished a 962 00:45:58,480 --> 00:46:00,840 Speaker 1: great deal, which tells you that they've been doing it 963 00:46:00,880 --> 00:46:01,920 Speaker 1: for a long long time. 964 00:46:02,160 --> 00:46:05,080 Speaker 3: Yeah, like you said, who knows what else is lying 965 00:46:05,239 --> 00:46:05,960 Speaker 3: under our feet? 966 00:46:06,560 --> 00:46:10,480 Speaker 1: That's right, exactly. So I think we answered that question 967 00:46:10,560 --> 00:46:11,560 Speaker 1: about the age of the earth. 968 00:46:11,920 --> 00:46:16,480 Speaker 3: Yeah. Yeah, So grab a glass of wine and sit 969 00:46:16,560 --> 00:46:17,799 Speaker 3: back and enjoy it. 970 00:46:18,280 --> 00:46:21,840 Speaker 1: That's right. And no matter how old you are, remember 971 00:46:22,080 --> 00:46:23,880 Speaker 1: you can always enjoy one more brownie. 972 00:46:23,920 --> 00:46:24,800 Speaker 3: See you next time. 973 00:46:25,280 --> 00:46:27,880 Speaker 1: Thanks for tuning in and thanks for asking great questions. 974 00:46:28,040 --> 00:46:30,600 Speaker 1: This question was inspired by an email from a listener, 975 00:46:30,719 --> 00:46:32,520 Speaker 1: so if you have a question you'd like to know 976 00:46:32,600 --> 00:46:35,520 Speaker 1: the answer to, please send it to us at questions 977 00:46:35,560 --> 00:46:46,840 Speaker 1: at Danielandjorge dot com. Before you still have a question 978 00:46:46,920 --> 00:46:50,319 Speaker 1: after listening to all these explanations, please drop us a line. 979 00:46:50,360 --> 00:46:52,520 Speaker 1: We'd love to hear from you. You can find us 980 00:46:52,520 --> 00:46:56,319 Speaker 1: on Facebook, Twitter, and Instagram at Daniel and Jorge That's 981 00:46:56,320 --> 00:46:59,680 Speaker 1: one word, or email us at Feedback at Daniel and 982 00:46:59,719 --> 00:47:03,280 Speaker 1: Horny dot com. Thanks for listening, and remember that Daniel 983 00:47:03,320 --> 00:47:06,760 Speaker 1: and Jorge Explain the Universe is a production of iHeartRadio. 984 00:47:07,040 --> 00:47:12,160 Speaker 1: For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts, 985 00:47:12,320 --> 00:47:24,239 Speaker 1: or wherever you listen to your favorite shows. When you 986 00:47:24,239 --> 00:47:26,320 Speaker 1: pop a piece of cheese into your mouth, you're probably 987 00:47:26,360 --> 00:47:29,400 Speaker 1: not thinking about the environmental impact. But the people in 988 00:47:29,440 --> 00:47:32,560 Speaker 1: the dairy industry are. That's why they're working hard every 989 00:47:32,640 --> 00:47:35,960 Speaker 1: day to find new ways to reduce waste, conserve natural resources, 990 00:47:36,000 --> 00:47:39,560 Speaker 1: and drive down greenhouse gas emissions. How is US dairy 991 00:47:39,600 --> 00:47:43,719 Speaker 1: tackling greenhouse gases? Many farms use anaerobic digestors to turn 992 00:47:43,760 --> 00:47:48,279 Speaker 1: the methane from manure into renewable energy that can power farms, towns, 993 00:47:48,280 --> 00:47:51,560 Speaker 1: and electric cars. 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