1 00:00:08,160 --> 00:00:11,000 Speaker 1: Hey, Daniel, do you keep a family photo album? You know, 2 00:00:11,119 --> 00:00:13,880 Speaker 1: we used to, but these days it's all digital. I 3 00:00:13,880 --> 00:00:17,360 Speaker 1: think Mark Zuckerberg owns all of our family photos. It 4 00:00:17,440 --> 00:00:20,960 Speaker 1: owns your family period. Probably that too. But and how 5 00:00:20,960 --> 00:00:23,040 Speaker 1: do you feel when you look back and see pictures 6 00:00:23,120 --> 00:00:25,599 Speaker 1: of yourself when you were younger? Um? I try to 7 00:00:25,640 --> 00:00:28,040 Speaker 1: ignore all those signs of aging, you know, pretend that 8 00:00:28,040 --> 00:00:29,920 Speaker 1: I looked the same ten or twenty years ago as 9 00:00:29,960 --> 00:00:32,960 Speaker 1: I do today. I see myself as a fine wine 10 00:00:34,159 --> 00:00:37,960 Speaker 1: because you have turned, because I just get more expensive 11 00:00:38,000 --> 00:00:40,600 Speaker 1: the older I get. For some reason. Well, you know, 12 00:00:40,640 --> 00:00:43,720 Speaker 1: I've known you for over ten years or so, and 13 00:00:44,040 --> 00:00:46,560 Speaker 1: I can I can say with confidence for those people 14 00:00:46,560 --> 00:00:49,680 Speaker 1: listening that you are so or no Paul Rudd. Unfortunately 15 00:00:50,680 --> 00:00:53,720 Speaker 1: that's true in many ways, unfortunately. But it is kind 16 00:00:53,760 --> 00:00:57,440 Speaker 1: of interesting how little clues can show you how old 17 00:00:57,520 --> 00:01:00,560 Speaker 1: someone is or how old something is. Right, It's true, 18 00:01:00,600 --> 00:01:03,040 Speaker 1: you know, a few wrinkles here and a few gray 19 00:01:03,080 --> 00:01:05,600 Speaker 1: hairs there, and all of a sudden, you look like 20 00:01:05,640 --> 00:01:09,840 Speaker 1: you're in your midlife crisis. What's that look like a 21 00:01:09,880 --> 00:01:13,720 Speaker 1: look of panic? It's a look of gravitas. I always 22 00:01:13,760 --> 00:01:17,320 Speaker 1: remember how dan Quail died his temples gray and which 23 00:01:17,400 --> 00:01:20,080 Speaker 1: not look so much like a little boy Dan quail Man. 24 00:01:20,160 --> 00:01:23,520 Speaker 1: That's a that's a reference that totally tells everyone how 25 00:01:23,560 --> 00:01:29,320 Speaker 1: old you are. Nobody's fascinating how almost everything around us 26 00:01:29,480 --> 00:01:33,360 Speaker 1: ages right. Everything from people around you, to the rocks 27 00:01:33,400 --> 00:01:36,959 Speaker 1: around you, um to the buildings around you always show 28 00:01:37,040 --> 00:01:40,000 Speaker 1: their signs of age. Nothing in this world is permanent. 29 00:01:56,200 --> 00:02:00,280 Speaker 1: Hi am poor handmade cartoonists and the creator of PhD comics. Hi. 30 00:02:00,480 --> 00:02:05,000 Speaker 1: I'm Daniel. I'm a particle physicist, and I'm young and spry, 31 00:02:05,040 --> 00:02:07,560 Speaker 1: and I have not written any web comics, but I'm 32 00:02:07,560 --> 00:02:10,600 Speaker 1: the co author of the book We Have No Idea 33 00:02:10,800 --> 00:02:14,240 Speaker 1: All about the unknown Questions in the Universe. And welcome 34 00:02:14,280 --> 00:02:17,560 Speaker 1: to our podcast, Daniel and Jorge Explain the Universe, a 35 00:02:17,680 --> 00:02:20,720 Speaker 1: production of I Heart Radio, in which we take weird 36 00:02:20,800 --> 00:02:23,760 Speaker 1: and amazing and young and old stuff in the universe 37 00:02:23,800 --> 00:02:26,400 Speaker 1: and try to explain it to you, and not just 38 00:02:26,520 --> 00:02:29,360 Speaker 1: telling you the answers, but sometimes digging in deeply and 39 00:02:29,400 --> 00:02:32,080 Speaker 1: explaining how we know so that you can explain it 40 00:02:32,320 --> 00:02:35,639 Speaker 1: to skeptical folks around you. Yeah, we try to get 41 00:02:35,639 --> 00:02:38,840 Speaker 1: you to think about the world around you and even 42 00:02:38,880 --> 00:02:41,960 Speaker 1: the world you're standing on right now or sitting on 43 00:02:42,080 --> 00:02:45,600 Speaker 1: or lying down on and one of the depending depending 44 00:02:45,600 --> 00:02:48,320 Speaker 1: on how old you are. But one of the goals 45 00:02:48,320 --> 00:02:50,400 Speaker 1: of this podcast is for you to have sort of 46 00:02:50,400 --> 00:02:53,080 Speaker 1: a new perspective on the world around you. We want 47 00:02:53,080 --> 00:02:55,799 Speaker 1: you to see everything around you as sort of a clue, 48 00:02:56,200 --> 00:02:58,480 Speaker 1: something that can tell you how the world works, that 49 00:02:58,560 --> 00:03:02,600 Speaker 1: can reveal secrets. I can answer questions because almost every 50 00:03:02,680 --> 00:03:05,639 Speaker 1: question we have about the universe, the answers are all 51 00:03:05,639 --> 00:03:08,079 Speaker 1: around us, and it just takes sort of a trained 52 00:03:08,160 --> 00:03:11,320 Speaker 1: mind and a careful eye to see those clues everywhere. 53 00:03:11,400 --> 00:03:14,280 Speaker 1: And so there are clues all around you about where 54 00:03:14,320 --> 00:03:16,720 Speaker 1: we come from and how long we've been here, and 55 00:03:16,760 --> 00:03:19,960 Speaker 1: how long everything has been here? Right, Yeah, exactly. And 56 00:03:20,320 --> 00:03:23,480 Speaker 1: sometimes answers are easy and obvious, and sometimes the answers 57 00:03:23,520 --> 00:03:27,200 Speaker 1: are mind mogglingly surprising. And so today on the podcast, 58 00:03:27,200 --> 00:03:31,120 Speaker 1: we'll be tackling, quite possibly the oldest question on earth. 59 00:03:31,160 --> 00:03:33,200 Speaker 1: Would you say that's true, Daniel, is that who stole 60 00:03:33,240 --> 00:03:35,800 Speaker 1: my dessert? Um? I think the answer is obvious, obviously, 61 00:03:35,800 --> 00:03:39,040 Speaker 1: it's your your children. Well you know, Um, that's actually 62 00:03:39,080 --> 00:03:42,440 Speaker 1: a question my kids asked me today. Um, when was 63 00:03:42,480 --> 00:03:46,320 Speaker 1: dessert invented? It sounds like a topic for a pope, 64 00:03:46,720 --> 00:03:49,080 Speaker 1: you know, if that falls into a physics question. But 65 00:03:49,080 --> 00:03:51,800 Speaker 1: it's sort of a fascinating question, and they were actually 66 00:03:51,880 --> 00:03:55,400 Speaker 1: hypothesizing that dessert might be older than people that maybe, 67 00:03:55,520 --> 00:04:00,240 Speaker 1: like our prehuman ancestors, enjoyed a sweet, sweet treat after dinner. 68 00:04:00,440 --> 00:04:03,000 Speaker 1: What do you think the little bacteria the good that 69 00:04:03,280 --> 00:04:06,280 Speaker 1: well the ocean? They're like, you know, I could use 70 00:04:06,320 --> 00:04:10,840 Speaker 1: a little two remy suit after consuming the other other bacteria. 71 00:04:11,040 --> 00:04:12,840 Speaker 1: I don't know if we have enough in common with 72 00:04:12,920 --> 00:04:15,080 Speaker 1: bacteria to say what they might like, but I can 73 00:04:15,160 --> 00:04:18,960 Speaker 1: imagine it's some pre human homaid, you know, eating some 74 00:04:19,040 --> 00:04:22,000 Speaker 1: berries and going and that goes nicely with my antelope 75 00:04:22,080 --> 00:04:24,760 Speaker 1: or whatever they had for dinner. Well anyway, so so weely. Uh. 76 00:04:24,920 --> 00:04:28,080 Speaker 1: What I mean by it's the oldest question on Earth 77 00:04:28,279 --> 00:04:31,560 Speaker 1: is that it's it's probably really the oldest question that 78 00:04:31,600 --> 00:04:33,839 Speaker 1: could be on Earth, right, Yeah, I think that's probably true, 79 00:04:34,200 --> 00:04:36,640 Speaker 1: And it's a it's an important question, right. It's the 80 00:04:36,760 --> 00:04:39,080 Speaker 1: kind of question that we'd like to dig into because 81 00:04:39,480 --> 00:04:42,800 Speaker 1: it's the kind of question where the answer could change 82 00:04:42,839 --> 00:04:45,719 Speaker 1: the way we think about life and the universe and 83 00:04:45,800 --> 00:04:48,400 Speaker 1: the humanity's rolling it right, it has all sorts of 84 00:04:48,440 --> 00:04:51,320 Speaker 1: things to do with with creation and the context of 85 00:04:51,360 --> 00:04:53,960 Speaker 1: our lives and therefore how we should live our lives 86 00:04:53,960 --> 00:04:55,640 Speaker 1: and whether they have meanings and so to be. On 87 00:04:55,640 --> 00:05:04,040 Speaker 1: the podcast, we'll be tackling the question how old is 88 00:05:04,080 --> 00:05:08,520 Speaker 1: the Earth? And is it even polite to ask? That's right? 89 00:05:09,080 --> 00:05:11,200 Speaker 1: And what does the earth do when he gets upset? 90 00:05:11,440 --> 00:05:14,520 Speaker 1: All right, when he gets offended? Um? And not just 91 00:05:14,600 --> 00:05:16,400 Speaker 1: how old had any worked? One? Has the Earth had 92 00:05:16,440 --> 00:05:20,080 Speaker 1: any work? One? Is it trying to? I think the 93 00:05:20,120 --> 00:05:25,040 Speaker 1: Earth looks great. Doesn't look a day past four billion? Um? 94 00:05:25,040 --> 00:05:29,000 Speaker 1: It is full of buetos. They're probably right, um. And 95 00:05:29,400 --> 00:05:31,560 Speaker 1: just as important as the question how old is the 96 00:05:31,560 --> 00:05:33,800 Speaker 1: Earth and the answer, which is you know, just a number, 97 00:05:34,240 --> 00:05:36,720 Speaker 1: is how do we know? How do we have confidence 98 00:05:36,760 --> 00:05:38,800 Speaker 1: in this answer? Because you know, there are people out 99 00:05:38,800 --> 00:05:41,360 Speaker 1: there who hold beliefs about the various age of the Earth. 100 00:05:41,680 --> 00:05:44,279 Speaker 1: And one of our listeners actually wrote in and said, hey, 101 00:05:44,320 --> 00:05:46,520 Speaker 1: could you tell me how we know the age of 102 00:05:46,560 --> 00:05:48,680 Speaker 1: the Earth, so that when I discussed with my friends 103 00:05:48,720 --> 00:05:51,040 Speaker 1: who have strong opinions about the age of the Earth, 104 00:05:51,200 --> 00:05:54,039 Speaker 1: I can tell them not just what scientists think, but 105 00:05:54,200 --> 00:05:56,200 Speaker 1: how they know it. Yeah, And that's the thing I 106 00:05:56,240 --> 00:05:58,200 Speaker 1: think we always try to do in this podcast, right, 107 00:05:58,279 --> 00:06:00,679 Speaker 1: is try to get at how people know these things, 108 00:06:00,680 --> 00:06:04,200 Speaker 1: not just tell people what scientists know, but how they 109 00:06:04,240 --> 00:06:06,479 Speaker 1: know it. That's right, And that also helps you understand 110 00:06:06,839 --> 00:06:09,159 Speaker 1: with what confidence we know it, Like is this just 111 00:06:09,240 --> 00:06:11,679 Speaker 1: sort of an educated guess the back of the envelope 112 00:06:11,680 --> 00:06:14,160 Speaker 1: calculation or is this something that people have been working 113 00:06:14,200 --> 00:06:16,800 Speaker 1: on for hundreds of years and we have great confidence 114 00:06:16,839 --> 00:06:19,480 Speaker 1: and have it nailed down to like point oh one percent. 115 00:06:19,800 --> 00:06:22,640 Speaker 1: And it's important because different things in science are are 116 00:06:22,680 --> 00:06:25,520 Speaker 1: known well and some things since science are are known 117 00:06:25,560 --> 00:06:28,800 Speaker 1: not very well. So it's important to know how we know. Yeah, 118 00:06:28,880 --> 00:06:31,320 Speaker 1: And so how old is the Earth is the question 119 00:06:31,320 --> 00:06:34,600 Speaker 1: for today, and it's kind of um, I think it's 120 00:06:34,600 --> 00:06:37,960 Speaker 1: a question most people know a little bit about, right. 121 00:06:38,040 --> 00:06:40,520 Speaker 1: I mean, I think everyone knows or has a sense 122 00:06:40,520 --> 00:06:43,400 Speaker 1: that the Earth is very old. Yeah, but you know, 123 00:06:43,920 --> 00:06:47,160 Speaker 1: that sense that the Earth is like extremely old, like 124 00:06:47,760 --> 00:06:50,719 Speaker 1: many orders of magnitude older than you or me or 125 00:06:50,760 --> 00:06:55,040 Speaker 1: your parents, you know, is a fairly modern idea. I 126 00:06:55,080 --> 00:06:58,359 Speaker 1: think thousands of years ago people thought the Earth was 127 00:06:58,600 --> 00:07:01,359 Speaker 1: only hundreds or thousands of years old. They thought it 128 00:07:01,440 --> 00:07:04,239 Speaker 1: might have been created fairly recently, and it was only 129 00:07:04,279 --> 00:07:06,680 Speaker 1: sort of in the eighteen hundreds that people started to 130 00:07:06,760 --> 00:07:10,160 Speaker 1: understand that there were processes around us that we could see, 131 00:07:10,400 --> 00:07:15,080 Speaker 1: specifically rocks and evolutions or geology and biology started to 132 00:07:15,120 --> 00:07:18,640 Speaker 1: give hints that the answer was much much bigger than 133 00:07:18,680 --> 00:07:22,480 Speaker 1: anything anybody had imagined. And I think that's wonderful. I 134 00:07:22,480 --> 00:07:24,760 Speaker 1: I love to live in a scientific era like that, 135 00:07:24,800 --> 00:07:29,080 Speaker 1: where you're where something you thought you knew is upended 136 00:07:29,120 --> 00:07:31,760 Speaker 1: and replaced with a completely different answer. That's like oors 137 00:07:31,760 --> 00:07:36,160 Speaker 1: a magnitude bigger. Wow, is that really true? Like it 138 00:07:36,360 --> 00:07:39,160 Speaker 1: only in the last couple of hundred years do we 139 00:07:39,360 --> 00:07:41,760 Speaker 1: have a sense of how old the Earth really is? 140 00:07:42,160 --> 00:07:44,000 Speaker 1: Before it was totally up in the air. Yeah, it 141 00:07:44,000 --> 00:07:45,760 Speaker 1: was up in the air until about the eighteen hundreds, 142 00:07:45,760 --> 00:07:48,520 Speaker 1: and then people started trying to do calculations and they're like, well, 143 00:07:48,840 --> 00:07:51,160 Speaker 1: how long would it take to form a planet, you know, 144 00:07:51,240 --> 00:07:53,920 Speaker 1: so you gathered it together with gravity, or you know, 145 00:07:54,520 --> 00:07:57,120 Speaker 1: how how long would it take to lay down layers 146 00:07:57,160 --> 00:07:59,720 Speaker 1: of rock? You know, how long would it take glaciers 147 00:07:59,720 --> 00:08:02,600 Speaker 1: to this kind of stuff? And you know, geology is 148 00:08:02,600 --> 00:08:04,400 Speaker 1: a fairly young field and that you know, it's a 149 00:08:04,440 --> 00:08:06,800 Speaker 1: couple of hundred years old and so people started to 150 00:08:06,840 --> 00:08:09,440 Speaker 1: look around, and as soon as they started to explore 151 00:08:09,840 --> 00:08:13,680 Speaker 1: these geological processes, they realized, wow, this stuff takes a 152 00:08:13,720 --> 00:08:17,360 Speaker 1: long time. And you know, it's sort of like um 153 00:08:17,440 --> 00:08:19,920 Speaker 1: walking into a room and seeing somebody has written a 154 00:08:19,960 --> 00:08:23,800 Speaker 1: book that's like five million pages long, and you're like, wow, 155 00:08:24,040 --> 00:08:26,000 Speaker 1: you've been in this room a long time, you know, 156 00:08:26,200 --> 00:08:29,840 Speaker 1: so it shocks you into realizing the things things are 157 00:08:29,880 --> 00:08:32,880 Speaker 1: a much different scale than you imagined. And that's the 158 00:08:33,080 --> 00:08:35,240 Speaker 1: we've seen the story the earth all around us. We 159 00:08:35,320 --> 00:08:39,680 Speaker 1: realize it's staggeringly long, much longer than we imagined, and that, yeah, 160 00:08:39,679 --> 00:08:41,800 Speaker 1: that's a fairly new idea. Yeah, that's a lot of 161 00:08:41,880 --> 00:08:46,760 Speaker 1: party you've missed exactly we should. Things have been around 162 00:08:46,800 --> 00:08:49,280 Speaker 1: for a long time. Do you have a fear of 163 00:08:49,280 --> 00:08:53,840 Speaker 1: missing out? There? Is that fomo about what happened? All 164 00:08:53,840 --> 00:08:56,920 Speaker 1: the good desserts? Fear of being in parties? Actually, to 165 00:08:57,000 --> 00:08:59,120 Speaker 1: be honest, what about all the desserts? The usually have 166 00:08:59,120 --> 00:09:02,120 Speaker 1: good dessertsive party old desserts or I just like I 167 00:09:02,200 --> 00:09:05,640 Speaker 1: just like a fine dessert. Wine? So you should you 168 00:09:05,640 --> 00:09:07,200 Speaker 1: show U at the beginning of the party, how the 169 00:09:07,240 --> 00:09:09,800 Speaker 1: desserts drink the wine and then go home? That's how 170 00:09:09,840 --> 00:09:11,319 Speaker 1: you know you're old or that was like a good 171 00:09:11,320 --> 00:09:15,359 Speaker 1: party to me. That is how your age old track exactly. 172 00:09:15,760 --> 00:09:20,000 Speaker 1: That's very age appropriate. Um. The beginning of this field 173 00:09:20,040 --> 00:09:22,839 Speaker 1: like becoming scientific before that was just speculation of the 174 00:09:22,880 --> 00:09:26,440 Speaker 1: beginning of the field. Becoming scientific was in the eighteen hundreds. Um. 175 00:09:26,480 --> 00:09:29,280 Speaker 1: But still that's very inaccurate. Like looking at rocks gives 176 00:09:29,280 --> 00:09:32,240 Speaker 1: you clues about the sort of order of magnitude, But 177 00:09:32,280 --> 00:09:34,680 Speaker 1: then people wanted to know very precisely, and that took 178 00:09:35,280 --> 00:09:38,760 Speaker 1: that took some time to to like basically defined clocks 179 00:09:38,800 --> 00:09:41,400 Speaker 1: inside the earth, clocks that have been ticking since it 180 00:09:41,440 --> 00:09:44,440 Speaker 1: was born. And that's in the end signs of aging, Yeah, 181 00:09:44,520 --> 00:09:46,719 Speaker 1: signs of aging, very precise signs of aging that could 182 00:09:46,760 --> 00:09:48,679 Speaker 1: tell us how old the earth was. So you're saying, like, 183 00:09:49,200 --> 00:09:52,520 Speaker 1: you know, the people who started the United States, like 184 00:09:52,559 --> 00:09:56,600 Speaker 1: the founding father fathers, like the Founding Fathers, they had 185 00:09:57,040 --> 00:09:59,959 Speaker 1: no idea how old we've been around, Like did they 186 00:10:00,040 --> 00:10:01,920 Speaker 1: think we've been around for a few thousand years? For 187 00:10:02,000 --> 00:10:05,000 Speaker 1: a few but didn't they know about the you know, 188 00:10:05,520 --> 00:10:08,000 Speaker 1: like ancient Egypt and things like that. Yeah, but you 189 00:10:08,040 --> 00:10:10,360 Speaker 1: know that's thousands of years, and so I think they 190 00:10:10,400 --> 00:10:12,800 Speaker 1: had the idea that the Earth was, you know, thousands, 191 00:10:12,840 --> 00:10:16,360 Speaker 1: many thousands of years old, right, because that's as long 192 00:10:16,400 --> 00:10:18,839 Speaker 1: as written history is, and so they imagine it's on 193 00:10:18,920 --> 00:10:21,160 Speaker 1: that time scale because that's the oldest thing, you know. 194 00:10:21,559 --> 00:10:24,240 Speaker 1: And that's basically the game is like find the oldest 195 00:10:24,240 --> 00:10:27,000 Speaker 1: thing you know and then assume that that's basically the 196 00:10:27,080 --> 00:10:29,920 Speaker 1: age of the world, right, And that's frankly what we're 197 00:10:29,960 --> 00:10:32,360 Speaker 1: still doing, um, except that we think that we found 198 00:10:32,400 --> 00:10:34,480 Speaker 1: stuff that comes from the very beginning of the world. 199 00:10:34,520 --> 00:10:36,960 Speaker 1: But you know, they knew about stuff that was thousands 200 00:10:36,960 --> 00:10:38,800 Speaker 1: of years old, so they had no reason to believe 201 00:10:39,160 --> 00:10:42,680 Speaker 1: that the Earth might be millions or even God forbid, 202 00:10:42,960 --> 00:10:45,680 Speaker 1: billions of years old, right. Plus I think those guys 203 00:10:45,720 --> 00:10:48,000 Speaker 1: are pretty religious, all right. So it is an age 204 00:10:48,000 --> 00:10:50,400 Speaker 1: old question and one that a lot of people have 205 00:10:50,559 --> 00:10:53,400 Speaker 1: had answers to and seems seemed to have answers to. 206 00:10:53,720 --> 00:10:56,120 Speaker 1: But we were wondering what people out there right now 207 00:10:56,400 --> 00:10:59,000 Speaker 1: in the world think about this question. Yeah, and this 208 00:10:59,040 --> 00:11:01,240 Speaker 1: is one this is a set of interviews. I was 209 00:11:01,520 --> 00:11:04,240 Speaker 1: very curious to see what people thought. I was wondering 210 00:11:04,280 --> 00:11:06,240 Speaker 1: if I would run into some sort of young Earth 211 00:11:06,280 --> 00:11:10,679 Speaker 1: folks who thought the Earth was from biblical ages and uh, 212 00:11:10,720 --> 00:11:12,800 Speaker 1: and even those people who were scientific. I was wondering, like, 213 00:11:12,800 --> 00:11:15,080 Speaker 1: how precisely do people know the age of the Earth. 214 00:11:15,160 --> 00:11:17,720 Speaker 1: So this I was very fascinating to hear the answers 215 00:11:17,720 --> 00:11:22,400 Speaker 1: like is it a million years, a bazillion years, twenty 216 00:11:22,480 --> 00:11:25,560 Speaker 1: seven point two bazillion? And so, as usual, Daniel went 217 00:11:25,600 --> 00:11:29,080 Speaker 1: out and asked people on the street how old they 218 00:11:29,160 --> 00:11:31,360 Speaker 1: thought the Earth was. So think about it for a second. 219 00:11:31,440 --> 00:11:34,880 Speaker 1: If you ran into a physicist in the street, uh today, 220 00:11:35,640 --> 00:11:38,840 Speaker 1: how would you answer this question? And no googling. Well, 221 00:11:38,880 --> 00:11:41,400 Speaker 1: here's what people had to say. Um, I have no 222 00:11:41,440 --> 00:11:46,319 Speaker 1: idea probably billion years. I don't exactly, but my understanding 223 00:11:46,400 --> 00:11:49,280 Speaker 1: is it's a couple of hundred million years old. Okay, 224 00:11:49,520 --> 00:11:51,800 Speaker 1: you know how we know? So I don't actually like 225 00:11:51,840 --> 00:11:54,560 Speaker 1: my my physics knowledge is pretty limited. Um. I think 226 00:11:54,600 --> 00:11:58,280 Speaker 1: like we've used carbon dating to date things within various 227 00:11:58,280 --> 00:12:02,120 Speaker 1: geological epox but I don't actually know how we arrived 228 00:12:02,160 --> 00:12:06,880 Speaker 1: at the calculation of the Earth stage and maybe three 229 00:12:06,960 --> 00:12:14,920 Speaker 1: billion years, tens of million years, four billion years, and 230 00:12:14,960 --> 00:12:18,160 Speaker 1: how do we know rock formation? It's probably like millions 231 00:12:18,160 --> 00:12:20,760 Speaker 1: of years old. I feel like, all right, Um, a 232 00:12:20,800 --> 00:12:24,080 Speaker 1: lot of millions and billions, right, yeah, exactly, not not 233 00:12:24,200 --> 00:12:26,160 Speaker 1: a whole lot of really specific answers. I have to 234 00:12:26,160 --> 00:12:28,840 Speaker 1: say I was a little bit disappointed. I guess I 235 00:12:28,880 --> 00:12:31,080 Speaker 1: thought people were more interested in this, Like I remember 236 00:12:31,120 --> 00:12:33,440 Speaker 1: wanting to know this number as precisely as possible when 237 00:12:33,480 --> 00:12:36,120 Speaker 1: I was a kid. I was really curious about this, um, 238 00:12:36,200 --> 00:12:37,760 Speaker 1: and so I was a little surprised that people were 239 00:12:37,840 --> 00:12:40,200 Speaker 1: just sort of knew it was super old and were 240 00:12:40,240 --> 00:12:43,360 Speaker 1: satisfied and didn't really care about the details. Although I'll 241 00:12:43,360 --> 00:12:46,760 Speaker 1: say every single person here after I asked them the 242 00:12:46,880 --> 00:12:49,079 Speaker 1: question then they did turn around and ask me. They're like, well, 243 00:12:49,120 --> 00:12:51,520 Speaker 1: how old is the Earth? So they wanted to know 244 00:12:51,679 --> 00:12:54,559 Speaker 1: abous just hadn't really spend any time looking it up. 245 00:12:54,600 --> 00:12:56,920 Speaker 1: All right, Well, let's get started on this topic, Daniel 246 00:12:56,960 --> 00:12:59,040 Speaker 1: and so, um. First of all, I think I feel 247 00:12:59,080 --> 00:13:01,520 Speaker 1: like we should define what we mean by the Earth 248 00:13:02,040 --> 00:13:04,360 Speaker 1: by the age of the Earth, right, Like, um, do 249 00:13:04,400 --> 00:13:07,560 Speaker 1: you mean like the the planet, like the ball that 250 00:13:07,640 --> 00:13:10,760 Speaker 1: it's Earth, or the rocks in the Earth, or the 251 00:13:10,840 --> 00:13:12,720 Speaker 1: atoms that are that make up the Earth? What do 252 00:13:12,720 --> 00:13:14,760 Speaker 1: you mean, like what's the age of the Earth. Yeah, 253 00:13:14,800 --> 00:13:18,040 Speaker 1: it turns out that that's a bit of a fuzzy question, right, 254 00:13:18,120 --> 00:13:21,760 Speaker 1: because the Earth has a sort of continuous history. It's 255 00:13:21,800 --> 00:13:24,920 Speaker 1: not like somebody snapped their fingers and boom, there was 256 00:13:24,960 --> 00:13:28,319 Speaker 1: the Earth. And you can start from the clock from then, right, Um, 257 00:13:28,360 --> 00:13:31,240 Speaker 1: that you know of, right, that we know of, that's right, unless, 258 00:13:31,280 --> 00:13:33,600 Speaker 1: of course it was a simulation, which case things is easy. 259 00:13:34,080 --> 00:13:36,720 Speaker 1: But in the case that it wasn't the simulation, we 260 00:13:36,760 --> 00:13:39,400 Speaker 1: have an idea about how the Earth was formed, and 261 00:13:39,440 --> 00:13:41,120 Speaker 1: there's just a lot of stages there, and so you 262 00:13:41,160 --> 00:13:44,720 Speaker 1: have to sort of make an arbitrary definition and into 263 00:13:44,800 --> 00:13:47,000 Speaker 1: like a lot of things in science, you know, Um, 264 00:13:47,040 --> 00:13:49,080 Speaker 1: there's not necessarily a clear and sower. So you just 265 00:13:49,120 --> 00:13:51,000 Speaker 1: define it to be something arbitrary and at least we 266 00:13:51,040 --> 00:13:53,760 Speaker 1: can agree on it. But maybe we should recap sort 267 00:13:53,760 --> 00:13:55,880 Speaker 1: of the brief history of the of the Earth and 268 00:13:55,880 --> 00:13:58,360 Speaker 1: how it was formed, yeah, like how it how it 269 00:13:58,440 --> 00:14:00,240 Speaker 1: came to be. Yeah, And then at some point we're 270 00:14:00,240 --> 00:14:02,320 Speaker 1: gonna say, this is when the earth started, this is 271 00:14:02,320 --> 00:14:03,839 Speaker 1: when the Earth was born. That's right. This is when 272 00:14:03,840 --> 00:14:06,720 Speaker 1: the party began, right, um, Because you know, you invite 273 00:14:06,720 --> 00:14:08,880 Speaker 1: people to party at nine o'clock and then they don't 274 00:14:08,880 --> 00:14:10,400 Speaker 1: show up till ten, and by then you've eating all 275 00:14:10,400 --> 00:14:14,640 Speaker 1: the brownies, um, and parties only really get started at 276 00:14:14,640 --> 00:14:17,360 Speaker 1: one a m. That's right, unless you're in Spain, in 277 00:14:17,360 --> 00:14:20,160 Speaker 1: which cases four am um. But you know, the very 278 00:14:20,240 --> 00:14:22,920 Speaker 1: early history is that we basically started with a huge 279 00:14:23,280 --> 00:14:25,560 Speaker 1: nebula of gas and dust. And this is stuff that's 280 00:14:25,640 --> 00:14:28,480 Speaker 1: left over from the explosions of other stars and just 281 00:14:28,520 --> 00:14:31,480 Speaker 1: gas from the Big Bang. And then of course gravity 282 00:14:31,520 --> 00:14:33,840 Speaker 1: did its thing and it pulls out all that stuff 283 00:14:33,880 --> 00:14:35,960 Speaker 1: together and you get a sun, right, So most of 284 00:14:35,960 --> 00:14:37,560 Speaker 1: the stuff went to the Sun, and then you get 285 00:14:37,640 --> 00:14:40,440 Speaker 1: a disc of stuff that's rotating around the Sun. It's 286 00:14:40,480 --> 00:14:44,120 Speaker 1: like rings around the Sun. And then the gravity pulls 287 00:14:44,160 --> 00:14:46,960 Speaker 1: the stuff in that disc together to turning to turn 288 00:14:47,040 --> 00:14:50,800 Speaker 1: that disc into planets, right, And uh so we think 289 00:14:50,880 --> 00:14:53,480 Speaker 1: that the Solar system started about four and a half 290 00:14:53,560 --> 00:14:57,720 Speaker 1: billion years ago, and it took like a few million 291 00:14:57,920 --> 00:15:01,040 Speaker 1: or a hundred million years to pull all that stuff 292 00:15:01,040 --> 00:15:04,680 Speaker 1: and the disk together into sort of protoplanets. Right. So 293 00:15:04,720 --> 00:15:06,960 Speaker 1: you have this sort of loose collection of stuff that 294 00:15:07,000 --> 00:15:09,760 Speaker 1: gravity is pulled together, and then gravity really gets to 295 00:15:09,800 --> 00:15:13,200 Speaker 1: work and it starts squeezing it and it collects all 296 00:15:13,200 --> 00:15:15,720 Speaker 1: this stuff and the planet heats up and sort of 297 00:15:15,760 --> 00:15:19,080 Speaker 1: melts the metal and you get the iron dropping to 298 00:15:19,120 --> 00:15:22,640 Speaker 1: the core and the crust forming, and so you can 299 00:15:22,680 --> 00:15:26,000 Speaker 1: sort of ask, like, what moment do you count the 300 00:15:26,120 --> 00:15:28,560 Speaker 1: earth forming? Is it like when you have the first 301 00:15:28,560 --> 00:15:32,360 Speaker 1: big cluster of rocks or maybe when it got gravitationally 302 00:15:32,480 --> 00:15:35,280 Speaker 1: heated enough to sort of melt the metals and form 303 00:15:35,360 --> 00:15:38,240 Speaker 1: the core um It's not really very clear. Well, I 304 00:15:38,240 --> 00:15:41,000 Speaker 1: always find this really fascinating because we we talked about 305 00:15:41,000 --> 00:15:43,880 Speaker 1: this the other day, that something like the rings around 306 00:15:43,880 --> 00:15:47,720 Speaker 1: Saturn are only temporary, right, Like at some point those 307 00:15:47,800 --> 00:15:51,760 Speaker 1: rings might turn into little blobs. That's right. Gravity is 308 00:15:52,000 --> 00:15:55,240 Speaker 1: very weak but very very patient, and so it just 309 00:15:55,360 --> 00:15:57,840 Speaker 1: keeps working and you give it enough time, it will 310 00:15:57,880 --> 00:16:01,120 Speaker 1: gather things together. And so this stuff that's orbiting Saturn 311 00:16:01,200 --> 00:16:04,800 Speaker 1: eventually grab gravity will pull it together in two moons. 312 00:16:05,080 --> 00:16:07,920 Speaker 1: Even the asteroid belt, is that at some point gonna 313 00:16:08,040 --> 00:16:11,080 Speaker 1: turn into more planets for our Solar system? Yeah, eventually. 314 00:16:11,080 --> 00:16:13,280 Speaker 1: Gravity it means very slow and those things are mostly 315 00:16:13,280 --> 00:16:16,520 Speaker 1: stable orbits, but eventually that stuff will get pulled together. 316 00:16:16,840 --> 00:16:19,520 Speaker 1: I mean also there's disruption. Right if you just left 317 00:16:19,520 --> 00:16:22,280 Speaker 1: the Solar system all by itself, then yes, eventually you'll 318 00:16:22,320 --> 00:16:25,640 Speaker 1: just gather together into a smaller and smaller number of objects. 319 00:16:25,680 --> 00:16:28,120 Speaker 1: But this disruption from stuff that comes outside, you know 320 00:16:28,160 --> 00:16:31,800 Speaker 1: and comets things from the word cloud. Um even even 321 00:16:31,840 --> 00:16:35,320 Speaker 1: things like supernovas from other solar system can disrupt things 322 00:16:35,400 --> 00:16:39,360 Speaker 1: happening in our solar system. Um. So, But yes, eventually 323 00:16:39,360 --> 00:16:41,800 Speaker 1: gravity will pull all this stuff together. It's really incredible 324 00:16:42,160 --> 00:16:45,160 Speaker 1: what over over these time scales, what gravity can do. 325 00:16:45,200 --> 00:16:46,840 Speaker 1: And that's one of my favorite things. It's just started 326 00:16:46,840 --> 00:16:51,080 Speaker 1: realizing that these processes are really slow, so things must 327 00:16:51,120 --> 00:16:53,960 Speaker 1: have been around for a super long time to make 328 00:16:54,000 --> 00:16:57,400 Speaker 1: it happen, right right, Well, I guess I would maybe 329 00:16:57,480 --> 00:17:00,160 Speaker 1: count that the birth of the Earth is when it 330 00:17:00,240 --> 00:17:02,840 Speaker 1: was form, you know, when all those asteroids and rocks 331 00:17:02,880 --> 00:17:06,560 Speaker 1: out there clumped together into a ball about the size 332 00:17:06,560 --> 00:17:09,159 Speaker 1: of the ball that we have now, like, you know, 333 00:17:09,200 --> 00:17:11,480 Speaker 1: when when it kind of snapped into shape. I would 334 00:17:11,600 --> 00:17:15,080 Speaker 1: maybe count that as the age of when the Earth started. Yeah, yeah, 335 00:17:15,119 --> 00:17:18,680 Speaker 1: and that's totally reasonable. That's totally reasonable. Um. I think 336 00:17:18,760 --> 00:17:22,000 Speaker 1: one common definition is that you measured the age of 337 00:17:22,000 --> 00:17:24,320 Speaker 1: the Earth is sort of the age of the oldest 338 00:17:24,480 --> 00:17:27,359 Speaker 1: rock in the Earth. And then you can ask the question, 339 00:17:27,359 --> 00:17:29,160 Speaker 1: what does it mean for a rock to be old. 340 00:17:29,200 --> 00:17:31,640 Speaker 1: Like you know, a rock is just a gravitational pulled 341 00:17:31,680 --> 00:17:35,239 Speaker 1: together clump of dust. But rocks are are formed right 342 00:17:35,240 --> 00:17:37,959 Speaker 1: there through melt and then they're cooled. And so the 343 00:17:37,960 --> 00:17:40,760 Speaker 1: age of a rock is usually like the last time 344 00:17:40,800 --> 00:17:43,359 Speaker 1: it was melted, right, So it's the time since it 345 00:17:43,400 --> 00:17:45,720 Speaker 1: was last melted, and so a lot of time people 346 00:17:45,840 --> 00:17:48,320 Speaker 1: just like the time that it cooled off, the last 347 00:17:48,320 --> 00:17:51,120 Speaker 1: time it really chilled out. And so you can imagine 348 00:17:51,160 --> 00:17:53,159 Speaker 1: like all these rocks came together, as you said, and 349 00:17:53,200 --> 00:17:56,120 Speaker 1: formed the Earth and got squeezed together and probably melted 350 00:17:56,400 --> 00:17:59,200 Speaker 1: and then cooled right, and the crust at least cooled, 351 00:17:59,520 --> 00:18:01,359 Speaker 1: and so you can asked, like maybe that last moment 352 00:18:01,400 --> 00:18:04,120 Speaker 1: the last moment of cooling of the crust. So the 353 00:18:04,160 --> 00:18:07,040 Speaker 1: age of the oldest cooled rock on the Earth could 354 00:18:07,080 --> 00:18:09,280 Speaker 1: be a definition at the age of the Earth, because otherwise, 355 00:18:09,280 --> 00:18:11,800 Speaker 1: how do you know when these rocks came together? Right? 356 00:18:12,600 --> 00:18:15,720 Speaker 1: Otherwise I don't know unless you have, like you know, 357 00:18:15,920 --> 00:18:18,919 Speaker 1: CCTV of the formation of the Solar system. It's pretty 358 00:18:18,920 --> 00:18:21,560 Speaker 1: hard to pin that down. Or you could say, is 359 00:18:21,560 --> 00:18:23,359 Speaker 1: it well, but you just gave me a number you 360 00:18:23,400 --> 00:18:25,280 Speaker 1: said that it was maybe it took around a hundred 361 00:18:25,320 --> 00:18:29,240 Speaker 1: million years to to form that the ball of the Earth. Yeah, 362 00:18:29,280 --> 00:18:31,600 Speaker 1: that's you know, I said, I said between a few 363 00:18:31,680 --> 00:18:33,920 Speaker 1: and a hundred million years, right, So that's a pretty 364 00:18:33,920 --> 00:18:36,679 Speaker 1: big uncertainty. Um, we don't really know how long it 365 00:18:36,760 --> 00:18:38,840 Speaker 1: took and and what moment do you define, like do 366 00:18:38,840 --> 00:18:41,840 Speaker 1: you needed one more rock? Because you know, caustic stuff 367 00:18:41,960 --> 00:18:45,000 Speaker 1: kept getting added to the Earth, and so some people say, well, 368 00:18:45,080 --> 00:18:46,720 Speaker 1: the age of the Earth is sort of just just 369 00:18:46,880 --> 00:18:49,200 Speaker 1: just call it the age of the Solar System because 370 00:18:49,200 --> 00:18:51,560 Speaker 1: that's pretty close to the age of the Earth. Or 371 00:18:51,680 --> 00:18:54,320 Speaker 1: you could say it's the age of the the oldest 372 00:18:54,440 --> 00:18:56,760 Speaker 1: rock on the Earth. So I think both of those 373 00:18:56,800 --> 00:18:59,199 Speaker 1: are sort of acceptable. And anyway, that's really all we 374 00:18:59,240 --> 00:19:01,800 Speaker 1: can probe and end. What we do is we measured 375 00:19:01,800 --> 00:19:03,919 Speaker 1: the age of the oldest rock we can find on 376 00:19:03,960 --> 00:19:06,199 Speaker 1: the Earth, and we say that's pretty close to the 377 00:19:06,200 --> 00:19:08,480 Speaker 1: age of the Earth. So the time that it formed 378 00:19:08,480 --> 00:19:11,960 Speaker 1: into a ball is kind of in between those two numbers, right, Yeah, exactly, 379 00:19:12,000 --> 00:19:16,640 Speaker 1: it's between when the Solar System formed and when the 380 00:19:16,640 --> 00:19:21,240 Speaker 1: ball that is the Earth started getting crusty. Exactly exactly 381 00:19:21,240 --> 00:19:24,240 Speaker 1: when it started getting crusty and grumpy and eating desserted 382 00:19:24,320 --> 00:19:28,840 Speaker 1: parties and going home early like a teenager. The suwhere 383 00:19:28,880 --> 00:19:32,280 Speaker 1: between conception and teenage years that's when you're born. That's 384 00:19:32,440 --> 00:19:34,080 Speaker 1: that's right. And you know, we have the same question 385 00:19:34,080 --> 00:19:37,720 Speaker 1: about people, right, I wonder about that sometimes. You know, Um, 386 00:19:38,000 --> 00:19:40,720 Speaker 1: how do you count somebody's age if there if somebody 387 00:19:40,800 --> 00:19:44,280 Speaker 1: is born premature, they're older. You know, even then somebody 388 00:19:44,280 --> 00:19:46,359 Speaker 1: who was born it was conceived at the same moment 389 00:19:46,400 --> 00:19:49,360 Speaker 1: but then born at full term. So even the age 390 00:19:49,359 --> 00:19:52,040 Speaker 1: of people is sort of hard to define sometimes. All right, well, 391 00:19:52,080 --> 00:19:55,200 Speaker 1: we've determined, we've determined what we mean by the age 392 00:19:55,240 --> 00:19:57,360 Speaker 1: of the Earth, and so now let's get into how 393 00:19:57,400 --> 00:20:00,119 Speaker 1: we know how old the Earth is and what what 394 00:20:00,160 --> 00:20:15,200 Speaker 1: that means. But first let's take a quick break. Okay, 395 00:20:15,240 --> 00:20:17,720 Speaker 1: so we're defining the age of the Earth is how 396 00:20:17,800 --> 00:20:23,159 Speaker 1: old the oldest rock was formed that we know about 397 00:20:23,480 --> 00:20:26,440 Speaker 1: right on Earth. That's right, exactly. Let's say, so when 398 00:20:26,440 --> 00:20:29,120 Speaker 1: the Earth was like a ball of lava, that doesn't count. 399 00:20:29,280 --> 00:20:33,119 Speaker 1: But once it started solidifying, then we're saying that's when 400 00:20:33,160 --> 00:20:36,760 Speaker 1: the Earth was born. Yeah, exactly, because we're imagining that, Yeah, 401 00:20:36,800 --> 00:20:39,000 Speaker 1: we're imagining that with that the formation, the Earth probably 402 00:20:39,040 --> 00:20:40,960 Speaker 1: melted a lot of the rocks because there was this 403 00:20:41,040 --> 00:20:44,160 Speaker 1: early lava period as you as you mentioned, and so 404 00:20:44,200 --> 00:20:46,440 Speaker 1: as it's cooled down and formed the crust, then it 405 00:20:46,520 --> 00:20:49,320 Speaker 1: made rocks and and it turns out we can figure 406 00:20:49,320 --> 00:20:52,720 Speaker 1: out how old a rocky is, and so that's really 407 00:20:52,760 --> 00:20:55,080 Speaker 1: our best handle in figuring out how old the Earth is. 408 00:20:55,080 --> 00:20:57,480 Speaker 1: And in the end it's a lower bound, right we say, well, 409 00:20:57,800 --> 00:20:59,800 Speaker 1: here's an old, super old rock on the Earth, so 410 00:20:59,800 --> 00:21:02,399 Speaker 1: that Earth must be at least that old, because like 411 00:21:02,440 --> 00:21:05,440 Speaker 1: we've talked about, like you mentioned, like um, trying to 412 00:21:05,480 --> 00:21:07,960 Speaker 1: figure out how old Earth is, the only thing we 413 00:21:08,000 --> 00:21:10,160 Speaker 1: can do is sort of look around and see how 414 00:21:10,200 --> 00:21:12,359 Speaker 1: old the things in it are, right, and like, what's 415 00:21:12,400 --> 00:21:14,280 Speaker 1: the oldest thing in it? We know it has to 416 00:21:14,280 --> 00:21:17,560 Speaker 1: be at least that old. Yeah, yeah, exactly. That's about 417 00:21:17,600 --> 00:21:19,280 Speaker 1: all we can do. And you know what you can 418 00:21:19,320 --> 00:21:21,840 Speaker 1: do otherwise is sort of form of theory. You say, 419 00:21:21,880 --> 00:21:24,359 Speaker 1: I have a concept for how this might have worked, 420 00:21:24,720 --> 00:21:27,160 Speaker 1: and then you can fit data to and say, well, 421 00:21:27,480 --> 00:21:29,800 Speaker 1: I expect you know that to see these sort of 422 00:21:29,880 --> 00:21:31,560 Speaker 1: rocks in that case, and you can use that a 423 00:21:31,680 --> 00:21:33,680 Speaker 1: theory to sort of extrapolate a little bit past the 424 00:21:33,760 --> 00:21:38,600 Speaker 1: day to you you observe. But that's very but that's speculative, right, 425 00:21:38,600 --> 00:21:40,920 Speaker 1: it's based on your concept of how things happen. So 426 00:21:41,280 --> 00:21:43,919 Speaker 1: the hardest number, the one that you know best, is 427 00:21:43,960 --> 00:21:47,080 Speaker 1: the oldest thing that you can find. And the oldest 428 00:21:47,080 --> 00:21:49,679 Speaker 1: thing we find our rocks, and and so what we 429 00:21:49,720 --> 00:21:52,359 Speaker 1: do is we try to turn one question into another question. 430 00:21:52,400 --> 00:21:54,840 Speaker 1: The question we can answer is what's the age of 431 00:21:54,880 --> 00:21:57,439 Speaker 1: the oldest rock on the Earth. Wouldn't that tell us 432 00:21:57,480 --> 00:22:00,479 Speaker 1: like if we found a really old raw, what if 433 00:22:00,480 --> 00:22:03,359 Speaker 1: that rock came from before the Earth was formed? Do 434 00:22:03,440 --> 00:22:05,800 Speaker 1: you know what I mean? Yeah, yeah, there are some 435 00:22:05,840 --> 00:22:09,600 Speaker 1: of those actually, like meteorites, Right, meteorites tell us the 436 00:22:09,600 --> 00:22:12,760 Speaker 1: age of the Solar system because we think meteorites were 437 00:22:12,800 --> 00:22:15,159 Speaker 1: formed in the beginning of the Solar system. Right, the 438 00:22:15,320 --> 00:22:19,280 Speaker 1: first stage is gathered together gas and dust into rocks, right, 439 00:22:19,760 --> 00:22:22,000 Speaker 1: And so those rocks from space tell us the age 440 00:22:22,000 --> 00:22:25,159 Speaker 1: of the Solar System. But we can tell which rocks 441 00:22:25,200 --> 00:22:28,000 Speaker 1: came from space and which rocks are from Earth, And 442 00:22:28,040 --> 00:22:31,840 Speaker 1: so we can distinguish those two. How can we tell? Oh, 443 00:22:31,920 --> 00:22:35,640 Speaker 1: they're clearly labeled. You know, they have their turn address, right, 444 00:22:35,680 --> 00:22:40,240 Speaker 1: it says somewhere near Neptune Um. It's it's actually quite 445 00:22:40,240 --> 00:22:43,560 Speaker 1: interesting that the so the distribution of metals in these 446 00:22:43,680 --> 00:22:46,719 Speaker 1: rocks is very different from meteorites than it is for 447 00:22:46,920 --> 00:22:50,600 Speaker 1: rocks on the Earth. It's like a different group of rocks. Yeah, 448 00:22:50,600 --> 00:22:52,439 Speaker 1: it's like they have more nickel in them where they 449 00:22:52,440 --> 00:22:55,080 Speaker 1: have this other rare stuff. And that's a whole other 450 00:22:55,119 --> 00:22:58,760 Speaker 1: fascinating field. Um. And also, so these rocks are different 451 00:22:58,800 --> 00:23:00,439 Speaker 1: from Earth, and they tell us like what else is 452 00:23:00,440 --> 00:23:02,440 Speaker 1: out there in the Solar System and what was out 453 00:23:02,440 --> 00:23:04,359 Speaker 1: there when the Solar system was formed? There like little 454 00:23:04,400 --> 00:23:07,320 Speaker 1: time capsules from the very beginning of the Solar system. 455 00:23:07,560 --> 00:23:09,639 Speaker 1: And they actually tell us another interesting story. Right, So 456 00:23:09,720 --> 00:23:12,080 Speaker 1: those rocks, we can tell how old they are, and 457 00:23:12,119 --> 00:23:14,719 Speaker 1: they tell us how old the Solar system is. So 458 00:23:14,760 --> 00:23:16,560 Speaker 1: we can answer two questions. We can find a bunch 459 00:23:16,560 --> 00:23:18,280 Speaker 1: of rocks. We can say, oh, these came from somewhere 460 00:23:18,280 --> 00:23:20,800 Speaker 1: in the Solar System. There x y z old. These 461 00:23:20,920 --> 00:23:23,359 Speaker 1: rocks are here on Earth, they're only you know, ABC 462 00:23:23,520 --> 00:23:25,560 Speaker 1: old all right. So then so it all comes down 463 00:23:25,560 --> 00:23:27,200 Speaker 1: to the question of how do you tell how old 464 00:23:27,240 --> 00:23:30,760 Speaker 1: the rock is, yeah, right, exactly exactly, or a meteorite 465 00:23:30,840 --> 00:23:32,240 Speaker 1: which is the same, which is the same because the 466 00:23:32,280 --> 00:23:34,879 Speaker 1: meteorite is just basically a rock from space that landed 467 00:23:34,920 --> 00:23:36,760 Speaker 1: on Earth. And the way we do it is something 468 00:23:36,800 --> 00:23:41,400 Speaker 1: called radiometric dating, which is not the same as carbon dating, right, 469 00:23:41,960 --> 00:23:43,720 Speaker 1: but it works in which is not the same as 470 00:23:44,000 --> 00:23:47,040 Speaker 1: online dating either. It turns out to be actually kind 471 00:23:47,080 --> 00:23:49,120 Speaker 1: of similar. There's a lot of swiping, there's a lot 472 00:23:49,160 --> 00:23:55,760 Speaker 1: of lying about your age as well. Um. No, carbon 473 00:23:55,880 --> 00:23:58,520 Speaker 1: dating and radio metric dating have similar principles, and we 474 00:23:58,520 --> 00:24:01,000 Speaker 1: should have a whole podcast episode of how carbon dating works. 475 00:24:01,000 --> 00:24:05,480 Speaker 1: Carbondating relates to organic stuff like living beings. Radiometric dating 476 00:24:05,640 --> 00:24:08,679 Speaker 1: relates to how how old rocks are. Okay, so you 477 00:24:08,720 --> 00:24:11,000 Speaker 1: find a rock and you're you're staring at it, and 478 00:24:11,000 --> 00:24:14,040 Speaker 1: you're like, I wonder when this rock became a rock? Yeah, 479 00:24:14,080 --> 00:24:18,240 Speaker 1: exactly when this turn from lava to this heavy thing 480 00:24:18,359 --> 00:24:21,320 Speaker 1: that I'm holding, And so you can we can actually tell, right, 481 00:24:21,400 --> 00:24:23,120 Speaker 1: we can look at the stuff in it and tell 482 00:24:23,119 --> 00:24:26,119 Speaker 1: how old window was formed, how many millions of years 483 00:24:26,160 --> 00:24:30,320 Speaker 1: ago exactly? And I have so much respect for scientists 484 00:24:30,480 --> 00:24:32,480 Speaker 1: who develop these techniques. You know, they look at the 485 00:24:32,560 --> 00:24:34,360 Speaker 1: rock and they say, I want to know how old 486 00:24:34,400 --> 00:24:37,200 Speaker 1: this rock is. How could I tell? Can I find 487 00:24:37,280 --> 00:24:40,280 Speaker 1: something inside the rock that I can use as a clock, 488 00:24:40,640 --> 00:24:44,600 Speaker 1: something which changes reliably and steadily every year, so that 489 00:24:44,640 --> 00:24:47,800 Speaker 1: I can count it and and project back and figure 490 00:24:47,840 --> 00:24:50,840 Speaker 1: out when that clock started or something. And this is 491 00:24:50,880 --> 00:24:53,240 Speaker 1: hard to do, you know. You have to find something 492 00:24:53,280 --> 00:24:57,160 Speaker 1: which is steady and reliable and can be calibrated. Um, 493 00:24:57,200 --> 00:24:59,520 Speaker 1: it's not trivial, right. You can't just say, oh, I'm 494 00:24:59,560 --> 00:25:01,560 Speaker 1: just gonna your X Y Z property. You have to 495 00:25:01,640 --> 00:25:05,000 Speaker 1: invent these techniques. And it takes time and sweat and tears, 496 00:25:05,359 --> 00:25:08,199 Speaker 1: and so I have so much respect for folks who 497 00:25:08,280 --> 00:25:10,240 Speaker 1: did this. And and in the case of rocks, it 498 00:25:10,240 --> 00:25:12,200 Speaker 1: turns out to be very dependent on the special kind 499 00:25:12,240 --> 00:25:18,560 Speaker 1: of mineral called zircon. Zircon like the fake diamond like, yeah, 500 00:25:18,560 --> 00:25:22,120 Speaker 1: it's related exactly. Zirconium and zircon is a special kind 501 00:25:22,160 --> 00:25:26,320 Speaker 1: of mineral. And it's special because it has two properties. One, 502 00:25:26,840 --> 00:25:29,720 Speaker 1: it likes it's a crystal, and it likes to absorb 503 00:25:29,880 --> 00:25:32,720 Speaker 1: uranium into it right, gobbles up uranium. So when the 504 00:25:32,800 --> 00:25:35,920 Speaker 1: rock forms, if it has some zircon, then it will 505 00:25:35,960 --> 00:25:39,919 Speaker 1: grab any uranium that's around it. And the second important property, 506 00:25:40,000 --> 00:25:42,320 Speaker 1: but wait, what is zircon made out of? Is it? 507 00:25:42,680 --> 00:25:45,560 Speaker 1: What is it like a made out of iron or 508 00:25:45,720 --> 00:25:48,679 Speaker 1: what is it carbon? What is this mineral made out 509 00:25:48,680 --> 00:25:52,960 Speaker 1: of it? I think it's made out of leftover desserts. No, 510 00:25:53,119 --> 00:25:58,160 Speaker 1: it's it's a mineral um. It's made out of zirconium 511 00:25:58,440 --> 00:26:03,040 Speaker 1: and silicon and oxygen. Oh Sirgonium is like an element 512 00:26:03,280 --> 00:26:07,119 Speaker 1: like carbon or irn. Yes, Zirconium is an element, and 513 00:26:07,200 --> 00:26:10,760 Speaker 1: it's sort of like a silver metal. It's atomic number forty. 514 00:26:10,960 --> 00:26:12,720 Speaker 1: It's you know, it doesn't really play a lot of 515 00:26:12,800 --> 00:26:15,119 Speaker 1: roles and stuff other than like cubics urconium. It's not 516 00:26:15,240 --> 00:26:17,200 Speaker 1: like a famous metal like some of its friends and 517 00:26:17,280 --> 00:26:21,200 Speaker 1: neighbors um, but it plays an important role in aging rocks. 518 00:26:21,240 --> 00:26:23,840 Speaker 1: So this element is all around us and to all 519 00:26:23,880 --> 00:26:26,840 Speaker 1: the rocks, and it forms a special crystal. You're saying 520 00:26:27,760 --> 00:26:31,640 Speaker 1: that when it forms, it likes to capture or uranium. 521 00:26:31,640 --> 00:26:34,600 Speaker 1: That's right. It captures uranium and it really rejects lead. 522 00:26:34,960 --> 00:26:37,880 Speaker 1: So the moment that the rock is created, it creates 523 00:26:37,880 --> 00:26:41,159 Speaker 1: a special thing, which is zircon with just uranium in it. 524 00:26:41,359 --> 00:26:44,960 Speaker 1: And you might wonder like, well, how is that helpful? Right? Well, uranium, 525 00:26:44,960 --> 00:26:47,600 Speaker 1: as you might know, is radioactive. It doesn't just sit 526 00:26:47,640 --> 00:26:52,159 Speaker 1: around and stay uranium forever. It very reliably decays and 527 00:26:52,200 --> 00:26:55,160 Speaker 1: it decays into lead. But wait, why does the durk 528 00:26:55,280 --> 00:26:58,840 Speaker 1: circon like uranium and white, doesn't it? You mean, like 529 00:26:58,840 --> 00:27:01,200 Speaker 1: when it forms the crystal les, it forms a little 530 00:27:01,240 --> 00:27:05,119 Speaker 1: structure and it just it just likes uranium like uranium 531 00:27:05,160 --> 00:27:07,760 Speaker 1: likes being inside of zircon crystal. I mean, I don't 532 00:27:07,760 --> 00:27:09,439 Speaker 1: want to get in the mind of uranium on the 533 00:27:09,440 --> 00:27:12,520 Speaker 1: mind of zircon. I mean, they did some carbon dating 534 00:27:12,680 --> 00:27:16,320 Speaker 1: online and they decided they were a good match. Um, 535 00:27:16,359 --> 00:27:19,240 Speaker 1: but no, there's some chemical some business with the chemical bonds. 536 00:27:19,240 --> 00:27:22,199 Speaker 1: You know, the way the crystal structure of zircon forms 537 00:27:22,560 --> 00:27:25,760 Speaker 1: fits very nicely with uranium and doesn't fit very nicely 538 00:27:25,760 --> 00:27:29,320 Speaker 1: with lead. Right, Yeah, So like a rock, you have 539 00:27:29,359 --> 00:27:32,000 Speaker 1: a have a bunch of lava and it cools and 540 00:27:32,040 --> 00:27:34,960 Speaker 1: it slowly turns into rock. And in that process is 541 00:27:34,960 --> 00:27:37,639 Speaker 1: when you you're saying this crystal form, yeah, and zirkon 542 00:27:37,800 --> 00:27:39,280 Speaker 1: is it doesn't have to be all over the rock. 543 00:27:39,320 --> 00:27:40,960 Speaker 1: It's not like a whole rock full of zirkon. It 544 00:27:41,040 --> 00:27:43,919 Speaker 1: is just these little chips of zircon. And what they 545 00:27:43,960 --> 00:27:46,040 Speaker 1: do is they repel all the lead inside them and 546 00:27:46,040 --> 00:27:50,040 Speaker 1: they grab some uranium and your uranium is like a clock. 547 00:27:50,440 --> 00:27:54,000 Speaker 1: It decays very reliably. So every million years or so, 548 00:27:54,080 --> 00:27:58,800 Speaker 1: some uranium turns into lead. And so after one million years, 549 00:27:59,080 --> 00:28:02,240 Speaker 1: some fraction the uranium and then zircon has turned into lead. 550 00:28:02,600 --> 00:28:06,040 Speaker 1: After two million years, another fraction has turned into lead. 551 00:28:06,160 --> 00:28:09,760 Speaker 1: After a billion years, a very predictable fraction is turned 552 00:28:09,800 --> 00:28:12,200 Speaker 1: into lead. So what you do is you take a rock, 553 00:28:12,600 --> 00:28:15,480 Speaker 1: you look at that, you find some zircon crystals, and 554 00:28:15,520 --> 00:28:18,280 Speaker 1: you ask how much of the uranium has turned into lead, 555 00:28:18,320 --> 00:28:20,720 Speaker 1: and that tells you how much time it's had to 556 00:28:20,840 --> 00:28:23,360 Speaker 1: turn into lead. It's kind of like a like an 557 00:28:23,359 --> 00:28:26,320 Speaker 1: aging process, right like wine. If you leave wine there, 558 00:28:26,400 --> 00:28:31,520 Speaker 1: it's gonna change, it's characteristic, it's gonna change into something 559 00:28:31,520 --> 00:28:33,880 Speaker 1: else exactly, and you need something. That's why it works 560 00:28:33,880 --> 00:28:35,760 Speaker 1: so well as a clock, because uranium is something that 561 00:28:35,800 --> 00:28:38,400 Speaker 1: we know reliably. We understand it, We know how it decays, 562 00:28:38,480 --> 00:28:40,280 Speaker 1: we know how long it takes, we know, you know, 563 00:28:41,240 --> 00:28:44,400 Speaker 1: after a hundred thousand years, what fraction of uranium atoms 564 00:28:44,400 --> 00:28:46,600 Speaker 1: will turn into lead. And the other key thing, of 565 00:28:46,640 --> 00:28:49,000 Speaker 1: course is that it starts with a blank slate. That 566 00:28:49,080 --> 00:28:51,959 Speaker 1: when you form these zircon crystals, it rejects lead. Right, 567 00:28:52,040 --> 00:28:54,520 Speaker 1: So you start out like with an empty bucket, and 568 00:28:54,520 --> 00:28:58,080 Speaker 1: then slowly the uranium bucket fills the lead bucket. And 569 00:28:58,080 --> 00:29:00,600 Speaker 1: so you can just measure the uranium lead fraction and 570 00:29:00,640 --> 00:29:04,120 Speaker 1: that tells you how long the uranium has been turning 571 00:29:04,120 --> 00:29:06,959 Speaker 1: into lead. It's really amazing. It's it's really just chance 572 00:29:07,040 --> 00:29:09,480 Speaker 1: that this happens, that somebody figured this out. So like 573 00:29:09,520 --> 00:29:11,800 Speaker 1: if you find a rock and you find a little 574 00:29:12,200 --> 00:29:16,360 Speaker 1: little zircon chip inside of it, and it's like, let's 575 00:29:16,360 --> 00:29:18,400 Speaker 1: say it's full of uranium, then you know it's a 576 00:29:18,440 --> 00:29:21,040 Speaker 1: pretty new rock exactly. But if it's full of lead, 577 00:29:21,080 --> 00:29:24,160 Speaker 1: then you know it's really old rock exactly. It's exactly right. 578 00:29:24,480 --> 00:29:28,400 Speaker 1: So rock start start out pure uranium, no lead, and 579 00:29:28,440 --> 00:29:31,400 Speaker 1: then as they age, the uranium turns into lead. And 580 00:29:31,440 --> 00:29:34,040 Speaker 1: so a rock with almost no uranium is going to 581 00:29:34,120 --> 00:29:37,920 Speaker 1: be like super duper old, right, And new lead can't 582 00:29:38,040 --> 00:29:40,800 Speaker 1: just like come in from the outside because now it's crystallized, right, 583 00:29:41,280 --> 00:29:43,800 Speaker 1: It's hard for lead to get in any other way. 584 00:29:44,000 --> 00:29:45,720 Speaker 1: All the only way you can get lead inside the 585 00:29:45,760 --> 00:29:48,840 Speaker 1: zircon is for uranium to turn into lead. So the 586 00:29:49,160 --> 00:29:51,840 Speaker 1: rock sort of you might say like it's spoils or 587 00:29:52,200 --> 00:29:56,160 Speaker 1: ages by looking at that. Yeah, like you, it turns 588 00:29:56,160 --> 00:29:59,760 Speaker 1: into lead right exactly, And whether it's spoils or ages 589 00:29:59,800 --> 00:30:02,160 Speaker 1: be to fully depends on you know, your preference for 590 00:30:02,240 --> 00:30:04,720 Speaker 1: how rocks taste. I suppose whether you swipe right or 591 00:30:04,800 --> 00:30:07,080 Speaker 1: left for rocks. But you know, it took a long 592 00:30:07,120 --> 00:30:10,040 Speaker 1: time to figure this out. People tried all sorts of 593 00:30:10,080 --> 00:30:13,000 Speaker 1: other strategies first before they discovered this one. And there's 594 00:30:13,160 --> 00:30:16,200 Speaker 1: lots of scientific careers and pH d PCs that were 595 00:30:16,240 --> 00:30:18,640 Speaker 1: frustrated in people trying to figure out a way to 596 00:30:18,680 --> 00:30:22,440 Speaker 1: do radiometric dating before people stumbled onto this one. Wow, 597 00:30:22,480 --> 00:30:24,120 Speaker 1: and this is not one of these things that you 598 00:30:24,400 --> 00:30:27,920 Speaker 1: um have to calibrate, right because I imagine you have 599 00:30:28,120 --> 00:30:35,880 Speaker 1: probably very scientific information about the decay of uranium, right like, 600 00:30:35,880 --> 00:30:39,320 Speaker 1: it's very physics space like. You don't have to calibrate 601 00:30:39,360 --> 00:30:41,280 Speaker 1: it to anything else, do you. You're right, And we 602 00:30:41,320 --> 00:30:44,920 Speaker 1: can basically use simple physics arguments to argue how long 603 00:30:45,040 --> 00:30:47,880 Speaker 1: uranium takes to decay and to lead and uh, and 604 00:30:47,920 --> 00:30:51,360 Speaker 1: so it gives us pretty clear descriptions, but you know, 605 00:30:51,440 --> 00:30:54,760 Speaker 1: we also want to get confidence in it, and so 606 00:30:54,800 --> 00:30:58,280 Speaker 1: what people do to have various other sort of radiometric 607 00:30:58,360 --> 00:31:01,600 Speaker 1: methods not just uranium to lead, but other stuff, things 608 00:31:01,640 --> 00:31:04,600 Speaker 1: that decay faster, things that decay slower, and so you 609 00:31:04,640 --> 00:31:07,600 Speaker 1: can use those to sort of cross calibrate, but uranium 610 00:31:07,640 --> 00:31:10,120 Speaker 1: to let this sort of the cleanest one. But you know, 611 00:31:10,160 --> 00:31:12,160 Speaker 1: like everywhere in science, you want to check everything three 612 00:31:12,160 --> 00:31:15,240 Speaker 1: different ways, um and then make sure you get consistent answers. 613 00:31:15,400 --> 00:31:17,520 Speaker 1: All right, that's pretty cool. That's how we can tell 614 00:31:17,560 --> 00:31:21,520 Speaker 1: how old the rock is. Man, rock can't lie. I 615 00:31:21,600 --> 00:31:24,840 Speaker 1: can't lie about its age. That's right, that's right. You 616 00:31:24,880 --> 00:31:27,120 Speaker 1: can lie, but we'll know you are. All right, Let's 617 00:31:27,120 --> 00:31:29,400 Speaker 1: get into the answer now, Daniel, how old Earth is 618 00:31:29,480 --> 00:31:32,560 Speaker 1: and how old the Solar system is. But first let's 619 00:31:32,720 --> 00:31:48,840 Speaker 1: take another quick break. All right, Daniel, Let's let's break 620 00:31:48,880 --> 00:31:52,120 Speaker 1: it down for people. How old is the Earth, or 621 00:31:52,480 --> 00:31:55,480 Speaker 1: at least the oldest rocks on Earth. The oldest rocks 622 00:31:55,480 --> 00:31:57,920 Speaker 1: on Earth come from Australia. And I don't know why, 623 00:31:57,960 --> 00:32:00,440 Speaker 1: but that's not surprising to me. It seems like Australia 624 00:32:00,520 --> 00:32:04,120 Speaker 1: is the land of extremes, and so you expect the craziest, weirdest, 625 00:32:04,120 --> 00:32:07,760 Speaker 1: oldest rock to be in Australia. And they have the 626 00:32:07,760 --> 00:32:12,520 Speaker 1: biggest spiders, the biggest crocodiles and the oldest rocks, the 627 00:32:12,560 --> 00:32:16,880 Speaker 1: deadliest everything, the biggest, best stars and the best podcast 628 00:32:16,920 --> 00:32:19,360 Speaker 1: listening fans. Right. Um, you know, we've got a lot 629 00:32:19,400 --> 00:32:22,000 Speaker 1: of good email questions from Australia. But the oldest rock 630 00:32:22,040 --> 00:32:24,960 Speaker 1: on Earth come from the jack Hills of Australia and 631 00:32:25,000 --> 00:32:29,040 Speaker 1: it's four point zero four billion years old. So these 632 00:32:29,040 --> 00:32:31,719 Speaker 1: are rocks that we do we have to dig up 633 00:32:31,720 --> 00:32:34,040 Speaker 1: for them, dig for them or are they were they 634 00:32:34,440 --> 00:32:37,520 Speaker 1: pretty close to the surface or yeah, it's it's fascinating. 635 00:32:37,520 --> 00:32:40,040 Speaker 1: Actually these rocks just sort of sit on outcrops and 636 00:32:40,160 --> 00:32:43,600 Speaker 1: people recently discovered that they have that the oldest rocks 637 00:32:43,600 --> 00:32:46,880 Speaker 1: are there, and you know it's um. The Earth itself, 638 00:32:46,920 --> 00:32:49,840 Speaker 1: of course, has had lots of geologic activity and so 639 00:32:49,920 --> 00:32:52,200 Speaker 1: some of these really old rocks get buried and then 640 00:32:52,240 --> 00:32:54,560 Speaker 1: there's geological activity that brings them up to the surface, 641 00:32:54,800 --> 00:32:57,320 Speaker 1: and so it just happens to be at this spot 642 00:32:57,400 --> 00:33:00,600 Speaker 1: on the Earth, these really old rocks got pushed up 643 00:33:00,680 --> 00:33:02,960 Speaker 1: and so they're not that far underground there on these 644 00:33:02,960 --> 00:33:06,160 Speaker 1: outcropping of rocks in Western Australia, but you almost kind 645 00:33:06,160 --> 00:33:08,200 Speaker 1: of expect them to be close to the surface, right, 646 00:33:08,240 --> 00:33:11,280 Speaker 1: because that's you know, I would imagine that if we 647 00:33:11,280 --> 00:33:13,760 Speaker 1: were once a ball of lava, then the stuff sort 648 00:33:13,800 --> 00:33:16,360 Speaker 1: of cools from the outside inwards. That's true. But you know, 649 00:33:16,360 --> 00:33:20,360 Speaker 1: then there's all these sedimentary processes where old things get buried. Um. 650 00:33:20,440 --> 00:33:22,760 Speaker 1: But then there's tectonic activity and all sorts of other 651 00:33:22,800 --> 00:33:26,360 Speaker 1: crazy stuff that brings stuff up and mixes everything around. Um. 652 00:33:26,480 --> 00:33:27,840 Speaker 1: And so there's a lot of stuff going on there. 653 00:33:27,840 --> 00:33:30,120 Speaker 1: I think it's not that not that simple. Um. But 654 00:33:30,200 --> 00:33:32,280 Speaker 1: in the end, the oldest thing we found on Earth 655 00:33:32,720 --> 00:33:35,520 Speaker 1: is uh, is almost four and a half billion years old. 656 00:33:35,680 --> 00:33:39,120 Speaker 1: Is four billion, four hundred and four million years old. 657 00:33:39,520 --> 00:33:41,600 Speaker 1: And you know, that's a staggering answer. It's hard to 658 00:33:41,640 --> 00:33:46,680 Speaker 1: really comprehend what that means. For billion years old, that's 659 00:33:47,240 --> 00:33:49,840 Speaker 1: a lot. It's a it's a lot of dessert parties. Yeah, 660 00:33:49,880 --> 00:33:53,440 Speaker 1: I mean, if theysed, a lot of party missed. Yeah. 661 00:33:53,600 --> 00:33:55,239 Speaker 1: I think I think what you said earlier about how 662 00:33:55,240 --> 00:33:58,040 Speaker 1: we came to the party pretty late. It's sort of shocking. 663 00:33:58,080 --> 00:34:00,000 Speaker 1: You know, the first people to like learn these number, 664 00:34:00,000 --> 00:34:02,520 Speaker 1: first to know that the Earth was billions of years old, 665 00:34:02,880 --> 00:34:05,960 Speaker 1: it must have made humans feel sort of small and 666 00:34:06,040 --> 00:34:09,719 Speaker 1: recent and uh. And you know, maybe transient tried like 667 00:34:10,040 --> 00:34:11,960 Speaker 1: the Earth has had a long history and we are 668 00:34:12,000 --> 00:34:14,239 Speaker 1: only the very last little bit of it. Yeah. I 669 00:34:14,239 --> 00:34:17,439 Speaker 1: mean it's a difference between I mean human histories maybe 670 00:34:17,560 --> 00:34:20,440 Speaker 1: what like ten thousand two years old? Yeah, a hundred 671 00:34:20,440 --> 00:34:24,080 Speaker 1: thousand if you're really generous. Yeah, but the Earth has 672 00:34:24,080 --> 00:34:27,680 Speaker 1: been around for four point four billion years old exactly. 673 00:34:28,040 --> 00:34:30,360 Speaker 1: It's not too impressed. It's been there, It's seen a 674 00:34:30,360 --> 00:34:33,839 Speaker 1: lot of stuff. You know, it'll be here, remember done. Um. 675 00:34:33,920 --> 00:34:35,560 Speaker 1: You know, people always talk about how humans are going 676 00:34:35,600 --> 00:34:38,200 Speaker 1: to destroy the Earth, and uh, I don't think that's likely. 677 00:34:38,400 --> 00:34:41,799 Speaker 1: I think the humans might destroy ourselves or life on Earth, 678 00:34:41,880 --> 00:34:44,640 Speaker 1: but the Earth will be here when we're done. Unless 679 00:34:45,160 --> 00:34:47,120 Speaker 1: I hear some physics are trying to make black holes 680 00:34:47,360 --> 00:34:49,840 Speaker 1: down at the Large Mattern Collider. Yeah, but we just 681 00:34:49,840 --> 00:34:52,640 Speaker 1: want to understand the universe. Man, We're not threatening the world. 682 00:34:52,840 --> 00:34:55,360 Speaker 1: There's no danger there. Trust me, And can I have 683 00:34:55,400 --> 00:34:59,080 Speaker 1: ten more billion dollars to build a bigger one one 684 00:34:59,160 --> 00:35:02,399 Speaker 1: year for every one daughter, for every year that the earth? 685 00:35:03,440 --> 00:35:05,719 Speaker 1: That's right, That sounds good. Um, But you know, that's 686 00:35:05,719 --> 00:35:08,439 Speaker 1: the oldest rock on Earth that we think is part 687 00:35:08,560 --> 00:35:11,120 Speaker 1: of the Earth. It was part of the formation of 688 00:35:11,160 --> 00:35:13,360 Speaker 1: the Earth. But of course we have found rocks on 689 00:35:13,440 --> 00:35:16,480 Speaker 1: Earth that are meteorites, right, they came from space that 690 00:35:16,560 --> 00:35:19,920 Speaker 1: are older than the Earth itself. So late comers to 691 00:35:19,960 --> 00:35:22,080 Speaker 1: the party, that's right. They heard there was something cool 692 00:35:22,120 --> 00:35:24,120 Speaker 1: happening down here in the third rock from the Sun, 693 00:35:24,239 --> 00:35:26,640 Speaker 1: and they they've fell on in to figure it out. 694 00:35:27,040 --> 00:35:31,320 Speaker 1: And those rocks are four point five six billion years old, 695 00:35:31,840 --> 00:35:35,200 Speaker 1: So that's like a hundred and fifty million years older 696 00:35:35,239 --> 00:35:38,239 Speaker 1: than the oldest rocks on Earth. That's the oldest meteorite 697 00:35:38,280 --> 00:35:40,759 Speaker 1: that we found. And I think that you were saying 698 00:35:40,760 --> 00:35:43,719 Speaker 1: that that kind of tells us what the oldest media 699 00:35:44,080 --> 00:35:46,600 Speaker 1: right at all is in our solar system, right, Yeah, 700 00:35:46,680 --> 00:35:49,560 Speaker 1: using the same logic, this is the oldest thing we found. Yeah, 701 00:35:49,680 --> 00:35:51,560 Speaker 1: so it's probably the sort of the age of the 702 00:35:51,560 --> 00:35:54,160 Speaker 1: Solar system. Right, that's when we think the gas and 703 00:35:54,160 --> 00:35:57,799 Speaker 1: the dust got accumulated together to form the Sun and 704 00:35:57,840 --> 00:36:00,160 Speaker 1: the planets and all that stuff. But the first age 705 00:36:00,200 --> 00:36:02,040 Speaker 1: of that was to form smaller rocks, and so we 706 00:36:02,080 --> 00:36:05,719 Speaker 1: think these things are remnants of those times. Right, But wait, 707 00:36:05,760 --> 00:36:08,160 Speaker 1: didn't the Sun. Hasn't the Sun our son already been 708 00:36:08,160 --> 00:36:10,640 Speaker 1: through a couple of cycles, Like, hasn't it exploded a 709 00:36:10,680 --> 00:36:15,359 Speaker 1: few times already. Well, our son hasn't exploded, but it's materials, right, 710 00:36:15,520 --> 00:36:19,480 Speaker 1: have been through several solar cycles. Everything around us, all 711 00:36:19,520 --> 00:36:21,880 Speaker 1: that stuff is left over from one or two or 712 00:36:21,920 --> 00:36:25,319 Speaker 1: three solar cycles of a sun lasting for you know, 713 00:36:25,400 --> 00:36:27,799 Speaker 1: one to see three billion years and then blowing up 714 00:36:27,840 --> 00:36:30,880 Speaker 1: and spreading its materials around. So everything around us is 715 00:36:31,000 --> 00:36:33,560 Speaker 1: all all the components of the solar system are probably 716 00:36:33,719 --> 00:36:36,840 Speaker 1: been recycled. But it's not like our son formed and 717 00:36:36,880 --> 00:36:38,600 Speaker 1: then we started in formed and we started it was 718 00:36:38,600 --> 00:36:41,600 Speaker 1: a different from a different star. Oh I see, So 719 00:36:41,719 --> 00:36:45,439 Speaker 1: our current son is is maybe around four point five 720 00:36:45,520 --> 00:36:48,040 Speaker 1: billion years old. Yeah, that's what we think. That's the 721 00:36:48,080 --> 00:36:51,040 Speaker 1: history of our solar system. And remember, for context, the 722 00:36:51,080 --> 00:36:54,520 Speaker 1: Milky Way is something like thirteen billion years old, and 723 00:36:54,560 --> 00:36:57,239 Speaker 1: the universe is just a little bit older than that, 724 00:36:57,680 --> 00:37:01,319 Speaker 1: almost fourteen billion years old. So there's a lot of 725 00:37:01,400 --> 00:37:05,320 Speaker 1: history before even our son, our solar system was formed, 726 00:37:05,480 --> 00:37:08,400 Speaker 1: and then a lot of history before we came around. 727 00:37:08,880 --> 00:37:11,880 Speaker 1: And so like that's the cosmic context that we're standing in. 728 00:37:12,080 --> 00:37:13,560 Speaker 1: And so that's the all this thing we found in 729 00:37:13,600 --> 00:37:16,480 Speaker 1: the solar system, but that's older than all the things 730 00:37:16,480 --> 00:37:18,920 Speaker 1: we found. That is part of the Earth. So somewhere 731 00:37:18,960 --> 00:37:21,560 Speaker 1: between those two numbers is when maybe the ball of 732 00:37:21,560 --> 00:37:23,600 Speaker 1: the Earth form. That's right. That's what we call the 733 00:37:23,680 --> 00:37:27,040 Speaker 1: Joorge date, the Joge definition of the age of the Earth, 734 00:37:27,960 --> 00:37:32,719 Speaker 1: the Bald date or his Bald date. That's right, that's right. Um. 735 00:37:33,080 --> 00:37:35,279 Speaker 1: And so you know there's a window there about a 736 00:37:35,400 --> 00:37:38,640 Speaker 1: hundred and fifty million years, which seems like a huge number, 737 00:37:38,760 --> 00:37:41,439 Speaker 1: you know, that's like, but it's pretty small, I think 738 00:37:41,480 --> 00:37:45,520 Speaker 1: compared to exactly. Geologically speaking, it's a blink of an eye, yeah, 739 00:37:45,880 --> 00:37:50,960 Speaker 1: or universe speaking, it's it's pretty accurate, yeah, exactly. And uh, 740 00:37:51,040 --> 00:37:53,480 Speaker 1: you know, we we know these numbers two plus or 741 00:37:53,520 --> 00:37:56,160 Speaker 1: minus twenty five or fifty million years based on the 742 00:37:56,200 --> 00:38:00,759 Speaker 1: uncertainty of radiometric dating and so um, because of the 743 00:38:00,840 --> 00:38:03,439 Speaker 1: hard work of a lot of scientists to develop these 744 00:38:03,480 --> 00:38:06,240 Speaker 1: things and across check them and understand them across various 745 00:38:06,280 --> 00:38:10,040 Speaker 1: other processes. Now we've looked around us and we've gathered 746 00:38:10,040 --> 00:38:12,600 Speaker 1: these clues from everyday objects around us, you know, the 747 00:38:12,680 --> 00:38:15,719 Speaker 1: rocks at our feet, the rocks in Australia give us 748 00:38:15,719 --> 00:38:19,480 Speaker 1: clues about these fantastic numbers that would just blow the 749 00:38:19,520 --> 00:38:22,239 Speaker 1: minds of our ancestors and those clues were around for 750 00:38:22,280 --> 00:38:24,680 Speaker 1: them to discover also, and so of course that makes 751 00:38:24,680 --> 00:38:27,640 Speaker 1: you wonder, like, what clues are there laying around at 752 00:38:27,640 --> 00:38:30,080 Speaker 1: our feet now that would tell us secrets of the 753 00:38:30,200 --> 00:38:33,239 Speaker 1: universe that our descendants will know and wonder why we 754 00:38:33,239 --> 00:38:35,839 Speaker 1: couldn't figure it out. It's not just like an opinion, right, 755 00:38:35,920 --> 00:38:39,319 Speaker 1: It's pretty based on evidence, and it's pretty based on 756 00:38:39,480 --> 00:38:42,840 Speaker 1: science and physics, the numbers. Yeah, exactly, these things we 757 00:38:42,880 --> 00:38:45,080 Speaker 1: know pretty well. We have a lot of confidence in them. 758 00:38:45,080 --> 00:38:48,400 Speaker 1: People have been working on these processes for decades and decades, 759 00:38:49,000 --> 00:38:52,360 Speaker 1: a lot of you know, grumpy competition between rivals to 760 00:38:52,400 --> 00:38:54,759 Speaker 1: make more and more accurate measurements. You know, this is 761 00:38:54,760 --> 00:38:57,640 Speaker 1: not a conspiracy of scientists all working together in harmony. 762 00:38:58,000 --> 00:39:00,560 Speaker 1: You know, this is a bunch of people racing to 763 00:39:00,680 --> 00:39:03,600 Speaker 1: develop better and better techniques and trying to find older 764 00:39:03,600 --> 00:39:07,280 Speaker 1: and older rocks. Remember, sciences a competitive field, and everybody 765 00:39:07,280 --> 00:39:09,400 Speaker 1: wants to one up the other to get the more accurate, 766 00:39:09,600 --> 00:39:12,880 Speaker 1: the more reliable, the more verifiable answer. So, yeah, we 767 00:39:12,920 --> 00:39:15,239 Speaker 1: have a lot of confidence in this knowledge. Yeah, it's 768 00:39:15,280 --> 00:39:17,319 Speaker 1: like it's all around the evidence, it's all around us, 769 00:39:17,360 --> 00:39:19,640 Speaker 1: and you're you're standing on it. Yeah, exactly, and even 770 00:39:19,680 --> 00:39:22,160 Speaker 1: if you can't do radiometric dating in your head of course, 771 00:39:22,200 --> 00:39:24,600 Speaker 1: because you can't see the xericon crystals. You know, you 772 00:39:24,680 --> 00:39:26,560 Speaker 1: just look around you and you see lots of things 773 00:39:26,600 --> 00:39:29,640 Speaker 1: around you which take a long time to form. You know, 774 00:39:29,960 --> 00:39:32,560 Speaker 1: how long does it take a mountain to form? It's 775 00:39:32,600 --> 00:39:35,960 Speaker 1: a very slow process. And so all around us on 776 00:39:36,000 --> 00:39:39,000 Speaker 1: the Earth we see evidence of very very slow processes 777 00:39:39,320 --> 00:39:42,200 Speaker 1: which have accomplished a great deal, which tells you that 778 00:39:42,239 --> 00:39:44,439 Speaker 1: they've been doing it for a long long time. Yeah, 779 00:39:44,680 --> 00:39:47,479 Speaker 1: like you said, who knows what else is lying under 780 00:39:47,480 --> 00:39:52,120 Speaker 1: our feet? That's right exactly, So I think we answered 781 00:39:52,160 --> 00:39:54,799 Speaker 1: that question about the age of the earth. Yeah, yeah, 782 00:39:54,840 --> 00:39:59,600 Speaker 1: so grab a glass of wine and sit back and enjoy. 783 00:40:00,320 --> 00:40:03,319 Speaker 1: That's right. And uh, no matter how old you are, 784 00:40:03,400 --> 00:40:06,239 Speaker 1: remember you can always enjoy one more brownie. See you 785 00:40:06,320 --> 00:40:09,120 Speaker 1: next time. Thanks for tuning in, and thanks for asking 786 00:40:09,160 --> 00:40:12,120 Speaker 1: great questions. This question was inspired by an email from 787 00:40:12,120 --> 00:40:14,319 Speaker 1: a listener, So if you have a question you'd like 788 00:40:14,360 --> 00:40:16,600 Speaker 1: to know the answer to, please send it to us 789 00:40:16,760 --> 00:40:27,880 Speaker 1: at questions at Daniel and Jorge dot com. Before you 790 00:40:28,000 --> 00:40:30,840 Speaker 1: still have a question after listening to all these explanations, 791 00:40:30,920 --> 00:40:33,880 Speaker 1: please drop us a line. We'd love to hear from you. 792 00:40:33,880 --> 00:40:36,719 Speaker 1: You can find us on Facebook, Twitter, and Instagram at 793 00:40:37,040 --> 00:40:40,160 Speaker 1: Daniel and Jorge That's one Word, or email us at 794 00:40:40,440 --> 00:40:44,080 Speaker 1: Feedback at Daniel and Jorge dot com. Thanks for listening 795 00:40:44,160 --> 00:40:46,840 Speaker 1: and remember that Daniel and Jorge Explain the Universe is 796 00:40:46,920 --> 00:40:50,400 Speaker 1: a production of I Heart Radio from More podcast from 797 00:40:50,400 --> 00:40:54,160 Speaker 1: my Heart Radio. Visit the I heart Radio app, Apple Podcasts, 798 00:40:54,320 --> 00:41:02,600 Speaker 1: or wherever you listen to your favorite shows. Nine