1 00:00:04,400 --> 00:00:07,800 Speaker 1: Welcome to tech Stuff, a production from my Heart Radio. 2 00:00:12,000 --> 00:00:14,600 Speaker 1: Hey there, and welcome to tex Stuff. I'm your host, 3 00:00:14,800 --> 00:00:18,280 Speaker 1: Jonathan Strickland. I'm an executive producer with I Heart Radio, 4 00:00:18,320 --> 00:00:21,760 Speaker 1: and I love all things tech and typically I would 5 00:00:21,800 --> 00:00:26,160 Speaker 1: have a news episode for you on today, which is Thursday, 6 00:00:26,239 --> 00:00:31,400 Speaker 1: April twenty one, but this week got away from the 7 00:00:31,560 --> 00:00:35,240 Speaker 1: big time. On the bright side, we have a really 8 00:00:35,400 --> 00:00:40,320 Speaker 1: cool thing coming up early next month that um tech 9 00:00:40,320 --> 00:00:42,640 Speaker 1: Stuff is taking part in that I think you guys 10 00:00:42,680 --> 00:00:47,239 Speaker 1: are really gonna dig. But that doesn't help me today, 11 00:00:47,400 --> 00:00:50,800 Speaker 1: does it. So instead of a news episode, we're going 12 00:00:50,840 --> 00:00:53,880 Speaker 1: to have a little bit of a classic episode here. 13 00:00:54,280 --> 00:00:57,640 Speaker 1: I thought, because I'm feeling so very old as I 14 00:00:57,680 --> 00:01:01,160 Speaker 1: try to to make sure I have these episodes ready 15 00:01:01,200 --> 00:01:03,600 Speaker 1: for you guys, it would be good to kind of 16 00:01:03,640 --> 00:01:06,160 Speaker 1: take stock. And by that I mean we're going to 17 00:01:06,240 --> 00:01:10,679 Speaker 1: listen to a classic episode called is carbon Dating on 18 00:01:10,720 --> 00:01:15,880 Speaker 1: the Way Out? This episode originally published on August two 19 00:01:15,959 --> 00:01:21,039 Speaker 1: thousand and fifteen. I hope you enjoy. This comes from 20 00:01:21,200 --> 00:01:25,120 Speaker 1: nikkil Cardale, and I do apologize that I'm sure I 21 00:01:25,360 --> 00:01:28,360 Speaker 1: mispronounced your name. The request was, could you do an 22 00:01:28,360 --> 00:01:32,160 Speaker 1: episode explaining this carbon dating is pretty useful, So this 23 00:01:32,200 --> 00:01:38,840 Speaker 1: effect seems relevant and uh Cardale actually uh commented on 24 00:01:39,000 --> 00:01:43,280 Speaker 1: and and included another tweet from real scientists that included 25 00:01:43,319 --> 00:01:47,000 Speaker 1: an article titled will our fossil use ruin our ability 26 00:01:47,080 --> 00:01:50,600 Speaker 1: to use carbon dating as a scientific tool? This is 27 00:01:50,640 --> 00:01:54,480 Speaker 1: really fascinating the idea of using carbon dating, uh, and 28 00:01:54,760 --> 00:02:00,160 Speaker 1: how that that method might be in jeopardy because the 29 00:02:00,240 --> 00:02:03,040 Speaker 1: use of fossil fuels. So I thought I would go 30 00:02:03,040 --> 00:02:06,920 Speaker 1: into that explain what carbon dating is and why it 31 00:02:07,040 --> 00:02:10,280 Speaker 1: might not be an accurate means of telling how old 32 00:02:10,320 --> 00:02:14,799 Speaker 1: something is after too long. So going into the article, 33 00:02:14,919 --> 00:02:17,560 Speaker 1: it's about how the enormous amount of carbon emissions we 34 00:02:17,600 --> 00:02:20,880 Speaker 1: generate could make carbon dating and unreliable means to determine 35 00:02:20,880 --> 00:02:24,400 Speaker 1: the age of certain types of materials. But to understand 36 00:02:24,440 --> 00:02:27,760 Speaker 1: how that's possible, we need to know how carbon dating 37 00:02:27,880 --> 00:02:32,000 Speaker 1: works first, So we're gonna do a carbon dating one 38 00:02:32,040 --> 00:02:34,560 Speaker 1: oh one. Now, the first thing that we have to 39 00:02:34,560 --> 00:02:39,680 Speaker 1: talk about is carbon fourteen. So the fourteen in carbon 40 00:02:39,720 --> 00:02:43,760 Speaker 1: fourteen tells us it's an isotope of carbon. This particular 41 00:02:43,800 --> 00:02:48,079 Speaker 1: isotope must have eight neutrons because carbon has six protons. 42 00:02:48,680 --> 00:02:51,360 Speaker 1: You can change the number of neutrons in an atom. 43 00:02:51,440 --> 00:02:54,960 Speaker 1: That's the different types of isotopes atoms may have. But 44 00:02:55,040 --> 00:02:57,880 Speaker 1: you can't change the number of protons and atom has 45 00:02:57,919 --> 00:03:01,440 Speaker 1: without changing that element. So carbon had six protons, and 46 00:03:01,480 --> 00:03:03,520 Speaker 1: if you change that number of protons, you change the 47 00:03:03,560 --> 00:03:08,639 Speaker 1: element itself. It acts reacts differently in chemical operations, and 48 00:03:09,000 --> 00:03:13,560 Speaker 1: uh is no longer carbon. So carbon twelve is the 49 00:03:13,600 --> 00:03:17,360 Speaker 1: most common form of carbon that we find. It has 50 00:03:17,400 --> 00:03:20,520 Speaker 1: six protons and six neutrons. Then you have carbon thirteen, 51 00:03:20,520 --> 00:03:23,160 Speaker 1: which is six protons and seven neutrons, and both of 52 00:03:23,160 --> 00:03:27,360 Speaker 1: those are stable forms of carbon. That means they don't decay. 53 00:03:27,520 --> 00:03:30,560 Speaker 1: So if you have carbon twelve or carbon thirteen, you 54 00:03:30,680 --> 00:03:33,160 Speaker 1: put it in a box and you leave for I 55 00:03:33,200 --> 00:03:36,200 Speaker 1: don't know, two billion years, and you come back, you're 56 00:03:36,200 --> 00:03:39,280 Speaker 1: still gonna have carbon twelve or carbon thirteen because they 57 00:03:39,280 --> 00:03:43,200 Speaker 1: remain stable. They do not decay. But carbon fourteen is different. 58 00:03:43,520 --> 00:03:48,839 Speaker 1: It is a radio isotope. Radioisotopes are also known as 59 00:03:49,040 --> 00:03:53,640 Speaker 1: radio nucleides, and these are isotopes of a particular atom 60 00:03:53,760 --> 00:03:57,880 Speaker 1: that have an unstable nucleus. These isotopes undergo what we 61 00:03:57,960 --> 00:04:01,400 Speaker 1: call nuclear decay, and in that process they release some 62 00:04:01,520 --> 00:04:05,280 Speaker 1: excess energy in the form of stuff like gamma rays 63 00:04:05,320 --> 00:04:09,920 Speaker 1: and or subatomic particles. Carbon fourteen undergoes what is called 64 00:04:10,320 --> 00:04:14,440 Speaker 1: beta decay. So when it decays, one of the neutrons 65 00:04:14,440 --> 00:04:18,880 Speaker 1: in the nucleus spontaneously changes into a proton, an electron, 66 00:04:19,240 --> 00:04:23,120 Speaker 1: and an anti neutrino. The nucleus gives the boot to 67 00:04:23,160 --> 00:04:27,000 Speaker 1: the electron and the anti neutrino, but the proton stays behind, 68 00:04:27,080 --> 00:04:30,440 Speaker 1: which means the atom no longer is a carbon atom. 69 00:04:30,480 --> 00:04:33,679 Speaker 1: Since again we mentioned that atoms depend upon the number 70 00:04:33,680 --> 00:04:37,480 Speaker 1: of protons and the nucleus, so the carbon fourteen decays 71 00:04:37,560 --> 00:04:43,279 Speaker 1: into nitrogen fourteen, and nitrogen fourteen has seven protons and 72 00:04:43,400 --> 00:04:46,400 Speaker 1: seven neutrons. Also, by the way, one of the few 73 00:04:46,640 --> 00:04:50,480 Speaker 1: stable elements that has both an odd number of protons 74 00:04:50,560 --> 00:04:54,839 Speaker 1: and an odd number of neutrons uh, and nitrogen fourteen 75 00:04:55,000 --> 00:04:58,200 Speaker 1: is stable. It makes up the vast majority of the 76 00:04:58,279 --> 00:05:02,680 Speaker 1: nitrogen found naturally under Earth, More than of the nitrogen 77 00:05:02,720 --> 00:05:06,839 Speaker 1: found on Earth is nitrogen fourteen. So radioactive decay occurs 78 00:05:07,000 --> 00:05:11,080 Speaker 1: naturally within these isotopes, and it's a spontaneous occurrence. That's 79 00:05:11,120 --> 00:05:14,760 Speaker 1: really important to remember. Carbon fourteen has a radioactive half 80 00:05:14,800 --> 00:05:19,400 Speaker 1: life of about five thousand, seven hundred years. There's some 81 00:05:19,440 --> 00:05:22,159 Speaker 1: confusion about what that means. I find in day to 82 00:05:22,240 --> 00:05:25,119 Speaker 1: day conversations with people who haven't had science in a while. 83 00:05:25,360 --> 00:05:28,359 Speaker 1: You guys who have recently had this in science class, 84 00:05:28,400 --> 00:05:31,040 Speaker 1: you're rolling your eyes right now. But for adults who 85 00:05:31,080 --> 00:05:33,600 Speaker 1: have not taken a science class in a long time, 86 00:05:33,960 --> 00:05:38,400 Speaker 1: this might require some some refreshing. So, half life of 87 00:05:38,440 --> 00:05:41,760 Speaker 1: five thousand, seven hundred years, what does that mean? It 88 00:05:41,800 --> 00:05:44,720 Speaker 1: means if you have a given amount of carbon fourteen, 89 00:05:45,320 --> 00:05:49,120 Speaker 1: after five thousand, seven hundred years or so, you'll have 90 00:05:49,480 --> 00:05:52,839 Speaker 1: only half of that carbon fourteen remaining, the other half 91 00:05:53,000 --> 00:05:58,000 Speaker 1: having undergone decay, radioactive decay and turning into nitrogen. Now, 92 00:05:58,040 --> 00:06:00,440 Speaker 1: this doesn't mean that all the carbon four team will 93 00:06:00,440 --> 00:06:03,400 Speaker 1: be gone after another five thousand, seven hundred years, nor 94 00:06:03,720 --> 00:06:06,880 Speaker 1: doesn't mean that carbon fourteen has a full life of 95 00:06:06,920 --> 00:06:10,119 Speaker 1: eleven thousand, four hundred years or anything like that. In fact, 96 00:06:10,120 --> 00:06:13,279 Speaker 1: what it really means is that after another five thousand, 97 00:06:13,279 --> 00:06:16,599 Speaker 1: seven hundred years, half of the remaining sample will have decayed, 98 00:06:16,760 --> 00:06:19,039 Speaker 1: leaving you with about a quarter of what you started with. 99 00:06:19,240 --> 00:06:21,600 Speaker 1: And another five thousand, seven hundred years if that means 100 00:06:21,600 --> 00:06:23,679 Speaker 1: you be left with about an eighth of that sample, 101 00:06:23,760 --> 00:06:28,240 Speaker 1: and so on. Carbon fourteen exists naturally on Earth in 102 00:06:28,360 --> 00:06:31,960 Speaker 1: trace amounts. Before the nineteen forties, the carbon fourteen on 103 00:06:32,040 --> 00:06:36,159 Speaker 1: Earth was created through a natural process. Once in a while, 104 00:06:36,360 --> 00:06:40,120 Speaker 1: cosmic rays, these very high energy particles in outer space, 105 00:06:40,400 --> 00:06:43,880 Speaker 1: would collide with an atom in our atmosphere or upper atmosphere, 106 00:06:44,240 --> 00:06:46,800 Speaker 1: and this collision would end up emitting a high energy 107 00:06:46,839 --> 00:06:50,799 Speaker 1: neutron that then could collide with nitrogen atoms that are 108 00:06:50,839 --> 00:06:54,600 Speaker 1: also way up there in our atmosphere. Now, cosmic rays 109 00:06:54,640 --> 00:06:58,479 Speaker 1: are high energy sub atomic particles. They originate outside of 110 00:06:58,480 --> 00:07:02,839 Speaker 1: our solar system, usually are admitted by supernova of massive stars, 111 00:07:03,200 --> 00:07:06,560 Speaker 1: and these sub atomic particles are primarily atomic nuclei and 112 00:07:06,720 --> 00:07:09,840 Speaker 1: high energy protons. So this collision of the high energy 113 00:07:09,880 --> 00:07:14,120 Speaker 1: neutron with the nitrogen forces a proton to leave the 114 00:07:14,200 --> 00:07:18,400 Speaker 1: nucleus and the in fourteen changes to C fourteen. So, 115 00:07:18,440 --> 00:07:21,080 Speaker 1: in other words, nitrogen fourteen turns to carbon fourteen. So 116 00:07:21,120 --> 00:07:23,720 Speaker 1: instead of having seven protons and seven neutrons, the new 117 00:07:23,760 --> 00:07:27,840 Speaker 1: atom has six protons and eight neutrons. The proton that 118 00:07:27,960 --> 00:07:31,200 Speaker 1: was broken off from the nucleus zooms off with an electron, 119 00:07:31,680 --> 00:07:34,120 Speaker 1: so you get one proton and one electron. That means 120 00:07:34,160 --> 00:07:38,320 Speaker 1: you have an atom of hydrogen. So again what's happening 121 00:07:38,400 --> 00:07:43,560 Speaker 1: is a high energy neutron collides with nitrogen fourteen, forces 122 00:07:43,640 --> 00:07:47,680 Speaker 1: out a proton. The proton and an electron high tail 123 00:07:47,760 --> 00:07:52,480 Speaker 1: it and honeymoon off as hydrogen and the incoming neutron 124 00:07:53,120 --> 00:07:56,280 Speaker 1: joins the party, and now you've got carbon fourteen. So 125 00:07:56,440 --> 00:08:00,320 Speaker 1: pre nineteen forties, carbon fourteen is rare because of two reasons. 126 00:08:00,560 --> 00:08:04,520 Speaker 1: It undergoes radioactive decay, so over time it disappears, and 127 00:08:04,600 --> 00:08:07,120 Speaker 1: it's produced by an event that's not super frequent, though 128 00:08:07,160 --> 00:08:11,360 Speaker 1: it's also not uncommon, so it does happen regularly enough 129 00:08:11,440 --> 00:08:17,640 Speaker 1: that carbon fourteen is replenished, but it's a very small 130 00:08:17,720 --> 00:08:21,520 Speaker 1: overall percentage of the carbon here on Earth. We've got 131 00:08:21,560 --> 00:08:23,920 Speaker 1: some more to say about carbon dating in just a second, 132 00:08:24,000 --> 00:08:34,839 Speaker 1: but first let's take a quick break for our sponsor. Now, 133 00:08:34,920 --> 00:08:38,960 Speaker 1: living things here on Earth absorb carbon through various means, 134 00:08:39,400 --> 00:08:42,400 Speaker 1: and some of that carbon is carbon fourteen. So it 135 00:08:42,559 --> 00:08:45,560 Speaker 1: maybe that you know, you eat a plant in that 136 00:08:45,600 --> 00:08:47,640 Speaker 1: plant has some of the carbon fourteen in it. Now 137 00:08:47,720 --> 00:08:50,160 Speaker 1: you have some of the carbon fourteen and you and 138 00:08:50,200 --> 00:08:53,080 Speaker 1: if we know the ratio of carbon fourteen to the 139 00:08:53,120 --> 00:08:56,800 Speaker 1: stable form of carbon twelve, we can look at materials 140 00:08:56,800 --> 00:08:58,960 Speaker 1: and analyze them to see how the ratio of carbon 141 00:08:59,000 --> 00:09:01,920 Speaker 1: fourteen to carbon twelve in the material stacks up to 142 00:09:02,040 --> 00:09:05,760 Speaker 1: the standard ratio. With living things, this becomes a matter 143 00:09:05,800 --> 00:09:09,200 Speaker 1: of looking at how much carbon fourteen is not there? 144 00:09:10,120 --> 00:09:13,720 Speaker 1: All right, That's it's a little confusing. Let me explain. So, 145 00:09:13,840 --> 00:09:17,640 Speaker 1: when a living thing is still alive, it accumulates carbon 146 00:09:17,679 --> 00:09:21,880 Speaker 1: at about the same rate it loses carbon, so carbon 147 00:09:22,000 --> 00:09:25,760 Speaker 1: cosmic rays produced this carbon fourteen frequently enough that the 148 00:09:25,880 --> 00:09:30,000 Speaker 1: ratio between carbon fourteen and carbon twelve remains steady, So 149 00:09:30,040 --> 00:09:34,679 Speaker 1: the percentage of carbon fourteen to carbon twelve is fairly standardized. 150 00:09:35,080 --> 00:09:38,320 Speaker 1: But when a living thing stops being alive and turns 151 00:09:38,360 --> 00:09:44,080 Speaker 1: into a not living anymore thing, it stops accumulating carbon, 152 00:09:44,440 --> 00:09:47,240 Speaker 1: so it has the carbon that it has inside of 153 00:09:47,280 --> 00:09:51,240 Speaker 1: it stays. That's it. You're not losing anymore. You're not 154 00:09:51,320 --> 00:09:56,360 Speaker 1: gaining any more except for carbon fourteen because carbon fourteen 155 00:09:56,520 --> 00:10:01,080 Speaker 1: undergoes radioactive decay, so over time, some of that carbon 156 00:10:01,200 --> 00:10:06,880 Speaker 1: fourteen starts to convert to nitrogen. So that means if 157 00:10:07,000 --> 00:10:10,560 Speaker 1: you can look at the remains of a living thing 158 00:10:11,160 --> 00:10:15,040 Speaker 1: and detect the ratio of carbon fourteen to carbon twelve. 159 00:10:15,440 --> 00:10:17,760 Speaker 1: You can get an idea of how long ago it 160 00:10:17,960 --> 00:10:21,080 Speaker 1: was that it stopped taking in carbon, as in, how 161 00:10:21,120 --> 00:10:24,240 Speaker 1: long ago was it that this lip, once living thing died. 162 00:10:25,240 --> 00:10:27,160 Speaker 1: It gets a little more complicated than all that, but 163 00:10:27,440 --> 00:10:31,640 Speaker 1: here's the basic rule. If we want to be really precise, 164 00:10:32,040 --> 00:10:35,200 Speaker 1: here's the equation we use to determine the age of 165 00:10:35,240 --> 00:10:39,120 Speaker 1: a sample of material. You have an equation where you 166 00:10:39,160 --> 00:10:43,000 Speaker 1: take the natural logarithm of n F divided by n 167 00:10:43,040 --> 00:10:46,920 Speaker 1: o uh that in turn is divided by negative point 168 00:10:47,000 --> 00:10:49,839 Speaker 1: six nine three, and then you multiply it by t 169 00:10:50,840 --> 00:10:55,920 Speaker 1: uh one half, so one half t the natural logarithm 170 00:10:56,280 --> 00:10:59,800 Speaker 1: is a specific logarithm applied to this equation and other 171 00:10:59,840 --> 00:11:03,240 Speaker 1: things as well. N F divided and oh actually refers 172 00:11:03,280 --> 00:11:06,120 Speaker 1: to the percentage of carbon fourteen and the sample compared 173 00:11:06,120 --> 00:11:10,520 Speaker 1: to the amount found in living stuff today at times 174 00:11:10,559 --> 00:11:13,079 Speaker 1: one half is the half life of carbon, so that's 175 00:11:13,120 --> 00:11:15,760 Speaker 1: five thousand, seven hundred years. So it was a lot 176 00:11:16,080 --> 00:11:18,400 Speaker 1: easier to understand this if we take a specific example. 177 00:11:19,400 --> 00:11:22,480 Speaker 1: So let's say you've got a sample of some sort 178 00:11:22,600 --> 00:11:26,800 Speaker 1: of material and you have determined that there is five 179 00:11:26,840 --> 00:11:29,920 Speaker 1: percent of the amount of carbon fourteen in that material 180 00:11:30,559 --> 00:11:33,400 Speaker 1: compared to what you would find in something that is alive. 181 00:11:33,640 --> 00:11:37,000 Speaker 1: Right now, so you take a sample of a living thing, 182 00:11:37,800 --> 00:11:40,679 Speaker 1: and then you take the sample of the thing you're testing. 183 00:11:41,120 --> 00:11:43,080 Speaker 1: You see that the thing you're testing only has five 184 00:11:43,080 --> 00:11:45,280 Speaker 1: percent of the carbon fourteen you would find in living things. 185 00:11:45,800 --> 00:11:47,440 Speaker 1: That means you would fill out the equation with the 186 00:11:47,559 --> 00:11:53,040 Speaker 1: natural logarithm of point zero five divided by negative point 187 00:11:53,120 --> 00:11:57,160 Speaker 1: six nine three, and you multiply that that result to 188 00:11:57,520 --> 00:12:00,120 Speaker 1: with five thousand, seven hundred years. The natural lug ay 189 00:12:00,120 --> 00:12:01,680 Speaker 1: them at point zero five, by the way, in case 190 00:12:01,720 --> 00:12:04,560 Speaker 1: you don't want to whip out your calculator, is negative 191 00:12:04,600 --> 00:12:08,079 Speaker 1: two point nine nine five seven three to two seven 192 00:12:08,200 --> 00:12:11,720 Speaker 1: three five five. If you divide that by negative point 193 00:12:11,800 --> 00:12:15,400 Speaker 1: six nine three, you get four point three to two 194 00:12:15,679 --> 00:12:21,319 Speaker 1: eight four five. Don't dial that number. If you take 195 00:12:21,400 --> 00:12:24,720 Speaker 1: that number, the four point three, etcetera, and you multiply 196 00:12:24,760 --> 00:12:27,600 Speaker 1: that by five thousand, seven hundred years, you end up 197 00:12:27,640 --> 00:12:30,840 Speaker 1: with twenty four thousand, six hundred forty point two years. 198 00:12:31,120 --> 00:12:34,120 Speaker 1: I mean, the stuff you're looking at died somewhere around 199 00:12:34,160 --> 00:12:37,320 Speaker 1: that time frame, give or take thirty two hundred years, 200 00:12:37,720 --> 00:12:40,160 Speaker 1: So somewhere on twenty four thousand, six hundred forty years 201 00:12:40,160 --> 00:12:44,440 Speaker 1: ago is when that thing no longer breathed or lived, 202 00:12:44,520 --> 00:12:48,120 Speaker 1: or however you wanted to find it. By the way, 203 00:12:48,320 --> 00:12:51,960 Speaker 1: this approach does have a limitation. Anything older than sixty 204 00:12:52,040 --> 00:12:55,080 Speaker 1: thousand years is pretty much out of bounds. Carbon fourteen 205 00:12:55,120 --> 00:12:57,400 Speaker 1: just isn't a reliable means of dating that sort of material, 206 00:12:57,480 --> 00:13:00,120 Speaker 1: and we have to rely on other methods so and 207 00:13:00,200 --> 00:13:04,400 Speaker 1: fourteen because of the decay once against two very small amounts, 208 00:13:04,960 --> 00:13:08,600 Speaker 1: it's very difficult to narrow it down to a specific time, 209 00:13:08,600 --> 00:13:11,040 Speaker 1: and if it's long enough, there won't be any carbon 210 00:13:11,040 --> 00:13:14,079 Speaker 1: fourteen at all all the carbon fourteen will have decayed 211 00:13:14,120 --> 00:13:17,040 Speaker 1: by then. You can't use carbon dating if there's no 212 00:13:17,120 --> 00:13:21,960 Speaker 1: carbon fourteen left. So to actually test the carbon fourteen concentration, 213 00:13:22,679 --> 00:13:26,360 Speaker 1: you first have to take the sample, uh whatever object 214 00:13:26,360 --> 00:13:28,920 Speaker 1: it might be. You have to remove part of it, 215 00:13:29,520 --> 00:13:32,000 Speaker 1: and typically you would apply some chemicals to the material, 216 00:13:32,480 --> 00:13:35,560 Speaker 1: usually a very strong acid wash and a strong base wash. 217 00:13:36,000 --> 00:13:40,600 Speaker 1: That's to remove all the contaminating materials that could end 218 00:13:40,679 --> 00:13:44,480 Speaker 1: up giving you false readings on carbon fourteen. Then you 219 00:13:44,480 --> 00:13:48,600 Speaker 1: would burn the sample within a glass container to capture 220 00:13:48,600 --> 00:13:52,760 Speaker 1: the carbon dioxide that is emitted when you burn the material. 221 00:13:53,320 --> 00:13:56,560 Speaker 1: And then you would analyze the carbon dioxide to find 222 00:13:56,600 --> 00:14:00,000 Speaker 1: out the concentration of carbon fourteen. So you can see 223 00:14:00,000 --> 00:14:02,760 Speaker 1: that this approach has a big drawback. It ends up 224 00:14:02,880 --> 00:14:06,040 Speaker 1: damaging whatever it is you are attempting to date in 225 00:14:06,080 --> 00:14:09,400 Speaker 1: the first place. And that's why some particularly high valued 226 00:14:09,440 --> 00:14:12,760 Speaker 1: items go without being tested, because the perception is that 227 00:14:12,840 --> 00:14:16,679 Speaker 1: even a small sample of that original piece would be 228 00:14:16,679 --> 00:14:21,240 Speaker 1: too much damage to to uh make on this item. 229 00:14:21,360 --> 00:14:25,040 Speaker 1: So certain items are considered very precious and there's a 230 00:14:25,080 --> 00:14:28,920 Speaker 1: big resistance to using carbon dating because by definition, you're 231 00:14:28,920 --> 00:14:32,040 Speaker 1: going to be damaging the material. Now, there's several lines 232 00:14:32,080 --> 00:14:35,960 Speaker 1: of research they're exploring possible non destructive means of using 233 00:14:36,080 --> 00:14:40,800 Speaker 1: radiocarbon dating. There's one that uses plasma oxidation and the 234 00:14:40,920 --> 00:14:44,600 Speaker 1: use of non destructive washes to clean samples of those 235 00:14:44,840 --> 00:14:48,840 Speaker 1: contaminating humic acids, which would lead to errors if they 236 00:14:48,840 --> 00:14:52,920 Speaker 1: remain behind. But those are still largely in the testing 237 00:14:52,960 --> 00:14:56,640 Speaker 1: phase and aren't the common means of using carbon dating. Also, 238 00:14:57,040 --> 00:14:59,600 Speaker 1: keep in mind that we use this method to estimate 239 00:14:59,640 --> 00:15:02,600 Speaker 1: the date of things made from organic materials, like the 240 00:15:02,640 --> 00:15:06,680 Speaker 1: Dead Sea scrolls, but this estimation is based upon when 241 00:15:06,720 --> 00:15:10,000 Speaker 1: the materials were harvested So, in other words, whenever the 242 00:15:10,080 --> 00:15:12,880 Speaker 1: living thing that the materials came from stopped being alive, 243 00:15:14,040 --> 00:15:16,640 Speaker 1: it doesn't tell us the date of when the artifact 244 00:15:16,720 --> 00:15:19,600 Speaker 1: was actually produced. So it's possible that you could come 245 00:15:19,640 --> 00:15:23,480 Speaker 1: across an artifact like a scroll, and you use carbon 246 00:15:23,560 --> 00:15:26,600 Speaker 1: dating on it and find out that the scroll material 247 00:15:27,240 --> 00:15:29,760 Speaker 1: is two thousand years old, meaning two thousand years ago 248 00:15:30,480 --> 00:15:34,480 Speaker 1: whatever the scroll was made out of stopped living, But 249 00:15:34,520 --> 00:15:38,360 Speaker 1: it doesn't tell you about the contents written in the scroll. 250 00:15:38,480 --> 00:15:42,080 Speaker 1: It's possible that the contents were added to the scroll 251 00:15:42,360 --> 00:15:46,920 Speaker 1: much after the living thing stopped being alive. Still, it's 252 00:15:46,920 --> 00:15:49,080 Speaker 1: a pretty good bet that the two are within the 253 00:15:49,120 --> 00:15:52,520 Speaker 1: same neighborhood of time, rather than someone held onto blank 254 00:15:52,600 --> 00:15:55,800 Speaker 1: scrolls for a few centuries before finally jotting something down. 255 00:15:57,280 --> 00:15:59,680 Speaker 1: All right, it's all this is cool, But how did 256 00:15:59,680 --> 00:16:03,000 Speaker 1: we even figure out radio Carbon dating would be a 257 00:16:03,040 --> 00:16:06,920 Speaker 1: possible way of figuring out how old something is. Well, 258 00:16:06,960 --> 00:16:09,360 Speaker 1: some early discoveries were made in the nineteen thirties at 259 00:16:09,360 --> 00:16:13,280 Speaker 1: the Lawrence Radiation Laboratory in Berkeley, and you probably remember 260 00:16:13,320 --> 00:16:15,720 Speaker 1: that if you've been listening to tech stuff. It factored 261 00:16:15,760 --> 00:16:18,120 Speaker 1: heavily into the discussion I had with Ben Boland about 262 00:16:18,160 --> 00:16:24,200 Speaker 1: the Manhattan Project. So Franz Curry, an American physicist, observed 263 00:16:24,240 --> 00:16:27,520 Speaker 1: something really interesting when he irradiated a cloud of air 264 00:16:27,640 --> 00:16:31,760 Speaker 1: in a cloud chamber. He used neutrons to UH to 265 00:16:31,920 --> 00:16:36,400 Speaker 1: irradiate that cloud, and he saw proton recoil tracks that 266 00:16:36,480 --> 00:16:40,920 Speaker 1: indicated something was losing protons. So he concluded that the 267 00:16:41,000 --> 00:16:44,880 Speaker 1: neutrons that he was using were colliding with nitrogen fourteen 268 00:16:45,440 --> 00:16:48,240 Speaker 1: and producing what was believed to be a form of 269 00:16:48,280 --> 00:16:51,720 Speaker 1: carbon as a result, with hydrogen being the other product 270 00:16:51,760 --> 00:16:55,320 Speaker 1: of this collision. His work was further explored by physicists 271 00:16:55,360 --> 00:16:59,640 Speaker 1: like Tom W. Bonner, W. M. Brubaker, W. J. Burcham, 272 00:17:00,000 --> 00:17:04,080 Speaker 1: and Maurice gold Hauber. Now collectively, this laid the foundation 273 00:17:04,119 --> 00:17:07,160 Speaker 1: for the simple equation of a high energy neutron plus 274 00:17:07,280 --> 00:17:12,400 Speaker 1: nitrogen fourteen produces one hydrogen atom and one carbon fourteen atom. 275 00:17:12,520 --> 00:17:15,280 Speaker 1: Then you had Narrico Fermi. We talked about him in 276 00:17:15,320 --> 00:17:18,639 Speaker 1: the Manhattan Project, and his work showed that the cross 277 00:17:18,640 --> 00:17:21,760 Speaker 1: section of a nitrogen fourteen atom was much larger than 278 00:17:21,800 --> 00:17:26,760 Speaker 1: other materials, and that suggested that neutron and nitrogen collisions 279 00:17:26,840 --> 00:17:29,800 Speaker 1: might happen fairly regularly in nature as long as there 280 00:17:29,840 --> 00:17:33,480 Speaker 1: were a supply of high energy neutrons. All right, we 281 00:17:33,600 --> 00:17:36,160 Speaker 1: got a little bit more about carbon dating, and then 282 00:17:36,840 --> 00:17:47,440 Speaker 1: what's It's back to reality for me? I guess so 283 00:17:47,880 --> 00:17:50,320 Speaker 1: Sage Korff, who was a physicist who was born in 284 00:17:50,359 --> 00:17:53,399 Speaker 1: Finland and whose family immigrated to the United States in 285 00:17:53,400 --> 00:17:57,560 Speaker 1: the early twentieth century, he discovered the phenomenon that cosmic 286 00:17:57,680 --> 00:18:01,199 Speaker 1: rays interact with atoms and produce high energy neutrons in 287 00:18:01,240 --> 00:18:06,440 Speaker 1: the upper atmosphere. So Pharem's prediction and course observation, we're 288 00:18:06,480 --> 00:18:11,120 Speaker 1: starting to kind of coalesce here. The observations convinced scientists 289 00:18:11,160 --> 00:18:14,879 Speaker 1: that the neutrons themselves were not cosmic rays, because the 290 00:18:14,880 --> 00:18:18,400 Speaker 1: neutrons had a lifespan of just eighteen minutes, and therefore 291 00:18:19,000 --> 00:18:21,560 Speaker 1: a neutron wouldn't be able to survive the long trip 292 00:18:21,600 --> 00:18:25,120 Speaker 1: through space. They must have been something else first, so 293 00:18:25,160 --> 00:18:27,720 Speaker 1: they said the neutrons had to be a byproduct of 294 00:18:27,760 --> 00:18:31,439 Speaker 1: another interaction. A cosmic ray must be interacting with something 295 00:18:31,440 --> 00:18:35,440 Speaker 1: in the atmosphere. That interaction caused this high energy neutron 296 00:18:35,480 --> 00:18:38,600 Speaker 1: to be emitted, and Quarter hypothesized that these neutrons could 297 00:18:38,640 --> 00:18:41,919 Speaker 1: then interact with nitrogen fourteen to produce carbon fourteen in 298 00:18:41,960 --> 00:18:45,879 Speaker 1: the upper atmosphere. Now, it was Willard F. Libby who 299 00:18:45,960 --> 00:18:48,480 Speaker 1: came up with the idea that since carbon fourteen is 300 00:18:48,560 --> 00:18:51,280 Speaker 1: generated at a steady rate due to cosmic ray interactions 301 00:18:51,280 --> 00:18:54,640 Speaker 1: in our atmosphere, you should be able to use it 302 00:18:54,680 --> 00:18:58,280 Speaker 1: to measure how long something has been dead. Libby would 303 00:18:58,320 --> 00:19:01,520 Speaker 1: measure the value of carbon fourteen's half life at five thousand, 304 00:19:01,640 --> 00:19:04,480 Speaker 1: five hundred sixty eight years, give or take thirty years, 305 00:19:04,840 --> 00:19:08,000 Speaker 1: which became known as the Libby half life. And Libby 306 00:19:08,080 --> 00:19:11,359 Speaker 1: himself would be awarded the Nobel Prize in nineteen sixty 307 00:19:11,440 --> 00:19:15,160 Speaker 1: for his work in radiocarbon dating. All right, so that's 308 00:19:15,200 --> 00:19:18,560 Speaker 1: the history of radiocarbon dating and generally how radiocarbon dating works. 309 00:19:18,920 --> 00:19:22,000 Speaker 1: So why is it in trouble or what could possibly 310 00:19:22,200 --> 00:19:26,120 Speaker 1: be causing confusion with radiocarbon dating. Well, there are two 311 00:19:26,119 --> 00:19:28,840 Speaker 1: big things we need to talk about, and one was 312 00:19:28,960 --> 00:19:30,840 Speaker 1: one that I've alluded to a couple of times. I 313 00:19:30,920 --> 00:19:35,119 Speaker 1: mentioned that, you know, pre nineteen forties, you had a 314 00:19:35,160 --> 00:19:39,520 Speaker 1: certain level of carbon fourteen that was pretty standard, but 315 00:19:39,640 --> 00:19:43,119 Speaker 1: the nuclear age really messed things up for us. They 316 00:19:43,160 --> 00:19:45,879 Speaker 1: made carbon fourteen dating a bit tricky. Starting in the 317 00:19:45,960 --> 00:19:50,000 Speaker 1: nineteen forties, we began testing nuclear bombs. Now, these bombs 318 00:19:50,000 --> 00:19:52,840 Speaker 1: released a lot of energy upon exploding, partly in the 319 00:19:52,880 --> 00:19:55,600 Speaker 1: form of high energy neutrons. You could probably see where 320 00:19:55,600 --> 00:19:58,680 Speaker 1: this is going. Some of those high energy neutrons ended 321 00:19:58,760 --> 00:20:01,719 Speaker 1: up interacting with night jan fourteen atoms, which meant that 322 00:20:01,840 --> 00:20:05,600 Speaker 1: it produced carbon fourteen atoms as a result. So the 323 00:20:05,720 --> 00:20:10,960 Speaker 1: concentration of carbon fourteen increased in the wake of nuclear 324 00:20:11,000 --> 00:20:14,720 Speaker 1: bomb testing. So anything that died after the nineteen forties 325 00:20:14,760 --> 00:20:18,159 Speaker 1: actually has a higher concentration of carbon fourteen than the 326 00:20:18,200 --> 00:20:22,520 Speaker 1: stuff that died before the nineteen forties did even at 327 00:20:22,520 --> 00:20:25,960 Speaker 1: the time of death. According to Professor Nalini nod Karnie 328 00:20:26,080 --> 00:20:29,119 Speaker 1: of the Evergreen State College, the nineteen fifties saw a 329 00:20:29,240 --> 00:20:34,080 Speaker 1: one hundred percent spike in carbon fourteen coming into the atmosphere. 330 00:20:34,800 --> 00:20:38,080 Speaker 1: In nineteen sixty three, the United States and Russia agreed 331 00:20:38,119 --> 00:20:41,359 Speaker 1: to stop above ground nuclear testing, and the levels of 332 00:20:41,359 --> 00:20:44,160 Speaker 1: carbon fourteen in the atmosphere gradually dropped down to their 333 00:20:44,200 --> 00:20:47,119 Speaker 1: normal levels. But that means there's a blip in the 334 00:20:47,160 --> 00:20:51,320 Speaker 1: carbon fourteen radar between the nineteen forties and nineteen sixty three. 335 00:20:51,520 --> 00:20:53,159 Speaker 1: So if you put yourself in the shoes of a 336 00:20:53,280 --> 00:20:58,240 Speaker 1: future archaeologist. Radio carbon dating becomes unreliable because the levels 337 00:20:58,240 --> 00:21:00,920 Speaker 1: of carbon fourteen could be decept tip. If the thing 338 00:21:00,920 --> 00:21:04,520 Speaker 1: you're measuring died during the era of nuclear testing, it 339 00:21:04,600 --> 00:21:07,800 Speaker 1: might appear to be younger than you thought because there's 340 00:21:07,800 --> 00:21:11,480 Speaker 1: a higher concentration of carbon fourteen in its sample than 341 00:21:11,600 --> 00:21:14,840 Speaker 1: you otherwise would have expected. So it may seem that 342 00:21:14,960 --> 00:21:20,000 Speaker 1: something died in twenty fifteen as opposed to nineteen sixty three. 343 00:21:20,680 --> 00:21:24,040 Speaker 1: That's just an example. Now to the article that prompted 344 00:21:24,040 --> 00:21:27,040 Speaker 1: this episode in the first place, that's a different case. 345 00:21:27,400 --> 00:21:30,360 Speaker 1: Researchers published a study in the Proceedings of the National 346 00:21:30,359 --> 00:21:33,320 Speaker 1: Academy of Sciences about how the use of fossil fuels 347 00:21:33,880 --> 00:21:38,000 Speaker 1: is further making radiocarbon dating less reliable, and this time 348 00:21:38,040 --> 00:21:41,040 Speaker 1: it's not an excess of carbon fourteen. It's actually the 349 00:21:41,040 --> 00:21:45,880 Speaker 1: opposite problem. Fossil fuels have no carbon fourteen in them 350 00:21:46,119 --> 00:21:50,800 Speaker 1: because they are fossil fuels. This is billions of years old, 351 00:21:51,440 --> 00:21:54,080 Speaker 1: so they're far too old for any carbon fourteen to remain. 352 00:21:54,160 --> 00:21:57,800 Speaker 1: Remember that carbon fourteen is decaying over time and turning 353 00:21:57,800 --> 00:22:03,200 Speaker 1: into nitrogen, so eventually all of those carbon fourteen atoms decay. 354 00:22:03,320 --> 00:22:06,639 Speaker 1: So burning a fossil fuel create releases carbon dioxide, and 355 00:22:06,680 --> 00:22:09,640 Speaker 1: the carbon in that CEO two has no carbon fourteen 356 00:22:09,640 --> 00:22:13,000 Speaker 1: and it's all carbon twolve carbon thirteen. So the more 357 00:22:13,040 --> 00:22:16,840 Speaker 1: fossil fuels we burn, the more we dilute the concentration 358 00:22:16,840 --> 00:22:20,119 Speaker 1: of carbon fourteen that's in the atmosphere. So stuff from 359 00:22:20,119 --> 00:22:23,080 Speaker 1: the nuclear age tends to look younger than it really 360 00:22:23,160 --> 00:22:26,359 Speaker 1: is because of the higher concentration of carbon fourteen. Stuff 361 00:22:26,440 --> 00:22:29,920 Speaker 1: from the later ages of fossil fuel use will look 362 00:22:30,119 --> 00:22:34,280 Speaker 1: older than they really are because carbon fourteen has been diluted. So, 363 00:22:34,280 --> 00:22:38,000 Speaker 1: according to the study, fresh organic material in twenty fifty 364 00:22:38,280 --> 00:22:41,280 Speaker 1: would contain the same amount of carbon fourteen relative to 365 00:22:41,320 --> 00:22:46,359 Speaker 1: carbon twelve as something dating from ten fifty. So you 366 00:22:46,400 --> 00:22:50,840 Speaker 1: have a thousand years of doubt in any radio carbon 367 00:22:50,920 --> 00:22:54,919 Speaker 1: dated samples. You would look at the two samples if 368 00:22:54,960 --> 00:22:58,400 Speaker 1: you if all you had were miniscule samples of two 369 00:22:58,440 --> 00:23:01,000 Speaker 1: things and one of them was a T shirt that 370 00:23:01,359 --> 00:23:05,400 Speaker 1: was made in and another was a piece of cloth 371 00:23:05,600 --> 00:23:09,280 Speaker 1: that dated from ten fifty, and you did radiocarbon dating, 372 00:23:10,000 --> 00:23:13,280 Speaker 1: you'd get the same result. This is not good if 373 00:23:13,320 --> 00:23:16,280 Speaker 1: you are trying to figure out how old something is 374 00:23:17,520 --> 00:23:20,880 Speaker 1: Heather Graven, who authored the study on fossil fuel emissions 375 00:23:20,920 --> 00:23:23,399 Speaker 1: and the effect on radiocarbon dating, says that if we 376 00:23:23,400 --> 00:23:27,680 Speaker 1: were to reduce carbon dioxide emissions drastically in the very 377 00:23:27,680 --> 00:23:31,359 Speaker 1: near future, the effect on future radiocarbon dating would be 378 00:23:31,359 --> 00:23:34,800 Speaker 1: equivalent to inserting a one year error on top of 379 00:23:34,840 --> 00:23:39,720 Speaker 1: any estimation. If we don't drastically reduce emissions, that error 380 00:23:39,840 --> 00:23:43,320 Speaker 1: range will continue to grow over time. One thing that 381 00:23:43,359 --> 00:23:46,240 Speaker 1: the concentration of carbon fourteen tells us is how much 382 00:23:46,280 --> 00:23:48,760 Speaker 1: carbon dioxide in the atmosphere comes from the burning of 383 00:23:48,800 --> 00:23:52,679 Speaker 1: fossil fuels. So as we see the concentration decrease, we 384 00:23:52,760 --> 00:23:56,439 Speaker 1: know that's because proportionally more carbon twelve is being released 385 00:23:56,440 --> 00:24:00,320 Speaker 1: into the atmosphere, diluting the already tiny concentration of carbon fourteen. 386 00:24:00,600 --> 00:24:03,320 Speaker 1: So that's useful for scientists who are studying climate change 387 00:24:03,320 --> 00:24:07,359 Speaker 1: and pollution. That's not exactly a happy story, is it. 388 00:24:08,520 --> 00:24:13,920 Speaker 1: So what are our options if carbon dating becomes unreliable, Well, 389 00:24:13,960 --> 00:24:16,560 Speaker 1: that depends on what you're trying to analyze. If you're 390 00:24:16,560 --> 00:24:19,680 Speaker 1: looking at inorganic stuff like rocks, you don't need to 391 00:24:19,760 --> 00:24:22,040 Speaker 1: use carbon fourteen in the first place. That would be 392 00:24:22,160 --> 00:24:25,160 Speaker 1: pretty much useless. You would use something else like potassium 393 00:24:25,320 --> 00:24:28,159 Speaker 1: argon dating, which is useful to estimate the age of 394 00:24:28,280 --> 00:24:30,840 Speaker 1: rocks that are a hundred thousand years old or younger. 395 00:24:31,400 --> 00:24:32,959 Speaker 1: And if that's not a big enough range, you can 396 00:24:33,000 --> 00:24:36,320 Speaker 1: actually use uranium lead dating, and that will let you 397 00:24:36,440 --> 00:24:40,560 Speaker 1: estimate rocks between one point four and five million years old. 398 00:24:41,240 --> 00:24:43,240 Speaker 1: There's a lot of different options if you're trying to 399 00:24:43,320 --> 00:24:45,880 Speaker 1: date stuff. When it comes to organic materials, however, it's 400 00:24:45,880 --> 00:24:49,000 Speaker 1: a lot more tricky. Radio carbon was a great tool, 401 00:24:49,960 --> 00:24:53,280 Speaker 1: but if it becomes unreliable, we're gonna have to use 402 00:24:53,359 --> 00:24:58,520 Speaker 1: other methods like contextual clues and other items that are 403 00:24:59,000 --> 00:25:03,800 Speaker 1: helping us connect things to dates. So this is a 404 00:25:03,840 --> 00:25:07,720 Speaker 1: big problem. I guess you could argue that's a big 405 00:25:07,760 --> 00:25:11,640 Speaker 1: problem for future generations and perhaps the records we leave 406 00:25:11,720 --> 00:25:19,640 Speaker 1: behind now are so uh so complete, they're so voluminous, 407 00:25:19,680 --> 00:25:22,960 Speaker 1: I guess is the best word. That future generations will 408 00:25:23,000 --> 00:25:26,640 Speaker 1: likely have more than enough material to determine when something 409 00:25:27,119 --> 00:25:31,879 Speaker 1: originated from our time versus earlier times. But the point 410 00:25:31,920 --> 00:25:36,639 Speaker 1: being that the way we're interacting with our world is changing. 411 00:25:36,680 --> 00:25:42,720 Speaker 1: This fundamental ratio of carbon fourteen to carbon twelve, and 412 00:25:43,200 --> 00:25:46,920 Speaker 1: that means that a really brilliant means of determining how 413 00:25:46,960 --> 00:25:50,800 Speaker 1: old something is is not really going to be an 414 00:25:50,840 --> 00:25:54,560 Speaker 1: accurate measure for very much longer. So it's kind of 415 00:25:54,600 --> 00:25:59,240 Speaker 1: a bummer. Obviously for things that are much much much older. 416 00:25:59,640 --> 00:26:02,359 Speaker 1: UH will at least in the short term, not be 417 00:26:02,560 --> 00:26:04,879 Speaker 1: that big of a deal, especially if we can relate 418 00:26:04,920 --> 00:26:08,400 Speaker 1: it to other items that we we already know the 419 00:26:08,440 --> 00:26:11,960 Speaker 1: age of those items. It won't be as destructive as 420 00:26:11,960 --> 00:26:15,320 Speaker 1: saying we can never use radio carbon dating again. We 421 00:26:15,400 --> 00:26:20,479 Speaker 1: just have to keep that changing ratio of carbon fourteen 422 00:26:20,480 --> 00:26:22,960 Speaker 1: to carbon twelve in mind so that we make sure 423 00:26:23,040 --> 00:26:26,680 Speaker 1: we're making accurate measurements. I hope you enjoyed that classic 424 00:26:26,720 --> 00:26:29,919 Speaker 1: episode of tech Stuff. Again, my apologies. I've got a 425 00:26:29,920 --> 00:26:31,760 Speaker 1: lot of things I wish I could have talked about, 426 00:26:31,920 --> 00:26:35,800 Speaker 1: like the fact that there's now a patent for a 427 00:26:35,840 --> 00:26:40,800 Speaker 1: retractable lightsaber blade thing. I really want to talk more 428 00:26:40,840 --> 00:26:44,440 Speaker 1: about that, so maybe next week. But in the meantime, 429 00:26:44,560 --> 00:26:47,399 Speaker 1: if you have any suggestions for topics I should tackle 430 00:26:47,480 --> 00:26:50,159 Speaker 1: on tech Stuff, let me know. Send me a message 431 00:26:50,200 --> 00:26:53,240 Speaker 1: on Twitter. The handle is text stuff h s W. 432 00:26:54,000 --> 00:27:02,400 Speaker 1: I'll talk to you again really soon. Yeah. Text stuff 433 00:27:02,440 --> 00:27:05,640 Speaker 1: is an I heart radio production For more podcasts from 434 00:27:05,640 --> 00:27:09,400 Speaker 1: I heart Radio, visit the i heart Radio app, Apple podcasts, 435 00:27:09,520 --> 00:27:11,520 Speaker 1: or wherever you listen to your favorite shows.