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Carbon Dating: The Method and Misconceptions · PlanetGeo: The Geology Podcast

• 0:03
  SPEAKER_00: Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
• 0:14
  SPEAKER_01: I really need a new partner.
• 0:16
  SPEAKER_01: I am not happy with my station in life right now.
• 0:21
  SPEAKER_00: Chris, you're just the luckiest son of a gun out there.
• 0:24
  SPEAKER_00: You get to hang out with me.
• 0:25
  SPEAKER_00: I know.
• 0:26
  SPEAKER_00: How are you doing, Jesse Ramink?
• 0:27
  SPEAKER_00: I'm doing really well.
• 0:28
  SPEAKER_00: We have not sat down and recorded together for too long.
• 0:31
  SPEAKER_00: Yeah, it's been too long.
• 0:33
  SPEAKER_00: That's not okay.
• 0:34
  SPEAKER_00: I mean, you're coaching track, you know, I'm end of the semester.
• 0:37
  SPEAKER_00: Oh, it's just we haven't done it in a while.
• 0:39
  SPEAKER_01: It is a busy, busy time of year.
• 0:42
  SPEAKER_01: And we know it's busy.
• 0:43
  SPEAKER_01: We're no busier than anyone else, but it's it's a busy time of year, right?
• 0:47
  SPEAKER_00: Totally.
• 0:47
  SPEAKER_00: Totally.
• 0:48
  SPEAKER_00: So what are we talking about today, man?
• 0:50
  SPEAKER_01: Well, let's do some introductions.
• 0:51
  SPEAKER_01: It's been a while, hasn't it?
• 0:52
  SPEAKER_00: That's true.
• 0:53
  SPEAKER_01: You are Jesse Ramink.
• 0:56
  SPEAKER_01: You're one of my former students.
• 0:57
  SPEAKER_01: Not actually, all right, here we go.
• 0:59
  SPEAKER_01: You are the former student.
• 1:03
  SPEAKER_00: The six foot four from Hudsonville, Michigan.
• 1:08
  SPEAKER_01: That's right.
• 1:08
  SPEAKER_01: I'm chest bumping you right now.
• 1:10
  SPEAKER_01: Okay.
• 1:11
  SPEAKER_01: Um, yeah, you're one of my former students, and uh you loved, you fell in love with geology as well, why wouldn't you?
• 1:19
  SPEAKER_01: And you went to Hope College, got a bachelor's degree in geology or geoscience, and then went on to the University of Alberta and Canada to get your PhD.
• 1:28
  SPEAKER_01: And you are now working as a professor of geoscience at the Penn State University.
• 1:33
  SPEAKER_00: That's right.
• 1:34
  SPEAKER_00: You're Chris Boise, my former high school teacher, high school teacher extraordinaire from the great state of Michigan, Huttsville Public Schools, Go Eagles, and uh you're a national award-winning Earth Science teacher.
• 1:44
  SPEAKER_00: You teach astronomy, summer field courses, you have your track shirt on right now.
• 1:48
  SPEAKER_00: You coach Huttsville track, or is that cross-country?
• 1:51
  SPEAKER_01: No, this is track.
• 1:53
  SPEAKER_01: It's track, there you go.
• 1:54
  SPEAKER_00: Okay, evil wings on it.
• 1:55
  SPEAKER_00: Yeah, man.
• 1:56
  SPEAKER_00: And this is Planet Geo.
• 1:57
  SPEAKER_01: Heck yeah, let's go.
• 1:58
  SPEAKER_00: We get to talk about all things geoscience.
• 2:00
  SPEAKER_01: Yeah, I'm really excited about today.
• 2:03
  SPEAKER_01: Um, today we're gonna talk about carbon dating, and which is also called radiocarbon dating.
• 2:10
  SPEAKER_01: And uh, this is this is something that like I think everybody knows this by now.
• 2:15
  SPEAKER_01: If we they've listened to our podcast for a while, they know you're into dating rocks, okay?
• 2:21
  SPEAKER_00: And very much so.
• 2:24
  SPEAKER_01: So it's your this is your lane, it's your expertise.
• 2:29
  SPEAKER_01: I have a lot to bring to it from maybe different perspectives and uh you know, misconceptions that I come across a lot.
• 2:36
  SPEAKER_01: I think this is one of the the things that is it's maligned a lot, radiocarbon dating, uh what it can do, what it can't do, what it's used for, how good is it?
• 2:47
  SPEAKER_01: I think there's a lot of stuff that's just simply wrong about it.
• 2:53
  SPEAKER_00: Misconceptions about it, not that the method itself is wrong.
• 2:56
  SPEAKER_01: Yeah, you're right.
• 2:57
  SPEAKER_01: People get a lot wrong about this topic.
• 3:00
  SPEAKER_00: Absolutely.
• 3:01
  SPEAKER_00: So carbon dating.
• 3:03
  SPEAKER_00: I always get this question in class: why can't we date diamonds?
• 3:07
  SPEAKER_00: Diamonds, most people know diamonds are made of carbon, they know carbon dating is a thing.
• 3:11
  SPEAKER_00: I mean, people generally kind of know the words carbon dating, maybe.
• 3:15
  SPEAKER_00: And the question is why can't we date diamonds?
• 3:17
  SPEAKER_00: And we'll touch on that at the end, but basically diamonds are far too old.
• 3:20
  SPEAKER_00: And you just you said I like to date rocks, which is very true.
• 3:24
  SPEAKER_00: I love dating rocks, measuring the ages of rocks.
• 3:27
  SPEAKER_00: But radiocarbon or carbon dating is not very good for rocks, actually.
• 3:31
  SPEAKER_00: It's actually really good for former organic matter, which is makes it really, really, really useful actually in the fields of archaeology.
• 3:41
  SPEAKER_00: It's very good for the last 50,000 years.
• 3:43
  SPEAKER_00: And we're gonna go through the details of why that is and why it's not good for dating rocks.
• 3:47
  SPEAKER_01: And it's only good though for dating organic matter that is younger than 50,000 years old.
• 3:54
  SPEAKER_01: Some of the misconceptions that I encounter a lot, the misconception is we use radiocarbon dating for dinosaur fossils, things like that.
• 4:03
  SPEAKER_01: And the bottom line is there's no carbon left, radioactive carbon anyway, to date in dinosaur fossils.
• 4:13
  SPEAKER_01: So we can't do radiocarbon dating on things like this.
• 4:17
  SPEAKER_01: And that is, I to me, that's the most prevalent misconception that exists out there is the dating of anything that used to be alive, regardless of how long ago that happens to be, right?
• 4:29
  SPEAKER_00: No, that's totally right.
• 4:30
  SPEAKER_00: I mean, I think I was just going through this.
• 4:32
  SPEAKER_00: We've got a couple undergrads working at our lab doing undergrad thesis projects.
• 4:36
  SPEAKER_00: And so I was in the lab working with graduate students and the undergrads, kind of teaching them the ropes of some of the techniques.
• 4:41
  SPEAKER_00: And basically, all these things, you gotta learn the tools.
• 4:45
  SPEAKER_00: You don't wanna, you know, try and drill in a screw with a hammer, right?
• 4:49
  SPEAKER_00: Like you got to use the right tool for your task at hand.
• 4:52
  SPEAKER_00: And so radiocarbon or carbon dating is very different from other types of radiometric dating.
• 4:57
  SPEAKER_00: And it just depends, are you dealing with a nail or a screw?
• 5:00
  SPEAKER_00: Like which one do you use?
• 5:01
  SPEAKER_00: Are you trying to date a young burned down tree stump from some archaeological find?
• 5:06
  SPEAKER_00: Then you might turn to carbon dating.
• 5:08
  SPEAKER_00: If you're trying to date old rocks, you're gonna turn to uranium lead or something like that.
• 5:12
  SPEAKER_00: So all these techniques have different niches uh of where they're useful, where they're really useful.
• 5:18
  SPEAKER_00: And there's overlap between them, but so let's get into Jesse.
• 5:22
  SPEAKER_01: Let's get into some of the basics about okay, carbon 12, carbon 13, and carbon-14.
• 5:30
  SPEAKER_01: What's going on?
• 5:31
  SPEAKER_01: So these are basically three isotopes of carbon.
• 5:36
  SPEAKER_01: And we need to get into a little bit of this, and we're gonna go fast with this because I don't want to lose anybody on this, but basically a carbon atom, anything that is called carbon, means that it has six protons in the nucleus.
• 5:50
  SPEAKER_01: And the vast majority of all carbon is carbon-12.
• 5:55
  SPEAKER_01: That means it has six protons and six neutrons for a mass of 12 atomic mass units.
• 6:01
  SPEAKER_01: Okay.
• 6:02
  SPEAKER_01: There are two other common isotopes, carbon-13 and carbon-14.
• 6:07
  SPEAKER_01: Carbon-13, six protons, but it has seven neutrons.
• 6:12
  SPEAKER_01: So six plus seven gives it a mass of 13, because protons and neutrons each weigh one atomic mass unit.
• 6:19
  SPEAKER_01: And then there's carbon-14, the one that is at the center of our discussion today, because that's radioactive with this half-life that we'll talk about later on.
• 6:29
  SPEAKER_01: And that has six protons and eight neutrons.
• 6:32
  SPEAKER_01: So they're all isotopes of carbon, which means they're the same atom, but they have different numbers of neutrons in the nucleus.
• 6:40
  SPEAKER_00: That is exactly right.
• 6:41
  SPEAKER_00: And that extra neutron in carbon-14, where it has eight neutrons and six protons, that extra neutrons, those make it unstable.
• 6:49
  SPEAKER_00: So this nucleus is not stable, which means it'll break apart and it'll decay into something different.
• 6:56
  SPEAKER_00: And what it decays into is nitrogen 14.
• 7:01
  SPEAKER_00: So it decays through beta decay.
• 7:03
  SPEAKER_00: So one of those neutrons is unhappy being a neutron, and it'll break down, it'll kick out an electron.
• 7:08
  SPEAKER_00: A neutron is basically a proton plus an electron.
• 7:13
  SPEAKER_00: So a proton, one mass unit and one positive charge plus an electron, one negative charge, and basically no mass, so it's a neutral thing with one mass unit.
• 7:24
  SPEAKER_01: Let me back up a second.
• 7:25
  SPEAKER_01: Okay, so beta decay, this is what happens with carbon-14 that decays into nitrogen 14.
• 7:33
  SPEAKER_01: If you define beta decay to students, you're like, okay, beta decay is a high-energy electron that is ejected or emitted from the nucleus of an atom.
• 7:45
  SPEAKER_01: Some of them will question that.
• 7:47
  SPEAKER_01: Like, wait a minute, but there are no electrons in the nucleus of an atom.
• 7:51
  SPEAKER_00: Yeah, aren't those worm around outside of it?
• 7:53
  SPEAKER_00: Aren't there isn't there some shell of electron shell?
• 7:55
  SPEAKER_01: This, Jesse, I gotta tell you, this leads to one of my most irritating things regarding chemistry.
• 8:04
  SPEAKER_00: Like I can see the vein coming out of the forehead right now.
• 8:06
  SPEAKER_01: But here's what it is.
• 8:08
  SPEAKER_01: And when I tell the students this, they actually get a little bit pissed off.
• 8:13
  SPEAKER_01: Wait a second, this is what beta decay is.
• 8:16
  SPEAKER_01: So, how does an electron, which doesn't exist in the nucleus of anatomy, how does it get emitted from it?
• 8:22
  SPEAKER_01: Well, to me, like it's such a weird thing, but I didn't learn this until I was maybe a junior in college and you know, taking a lot of chemistry classes, what a neutron really is.
• 8:32
  SPEAKER_01: And you just said it and you glossed right over it, but it's lost on a lot of people.
• 8:36
  SPEAKER_01: Let's look at, first of all, what's a proton.
• 8:40
  SPEAKER_01: A proton is a positive charge, has a mass of one, right?
• 8:46
  SPEAKER_01: An electron is a negative charge with essentially no mass.
• 8:53
  SPEAKER_01: It has such a small mass.
• 8:55
  SPEAKER_01: It is one 1,837 the mass of a proton.
• 9:00
  SPEAKER_01: You're never gonna deal with a massive electron.
• 9:02
  SPEAKER_01: So what do you get when you combine that proton with an electron?
• 9:09
  SPEAKER_01: Well, you take a plus and a minus, and you get a neutral charge, and it weighs one mass unit.
• 9:17
  SPEAKER_01: So that's what a neutron is.
• 9:20
  SPEAKER_01: A neutron is actually a particle that is made up of a proton and an electron.
• 9:27
  SPEAKER_00: So when that carbon, 14, it's too heavy, it you know has too many neutrons hanging around.
• 9:33
  SPEAKER_00: One neutron's gonna kick off an electron and turn into a proton.
• 9:36
  SPEAKER_00: Now it becomes nitrogen, which has seven protons in the nucleus, and it still has seven neutrons, so it's nitrogen with mass 14, so it's 14 nitrogen.
• 9:46
  SPEAKER_00: So 14 carbon, carbon 14, turns to nitrogen 14.
• 9:50
  SPEAKER_01: It's really messing up here.
• 10:00
  SPEAKER_01: So it feels like late fall here in Michigan right now, and it's cold.
• 10:05
  SPEAKER_01: And so I have a I have a hoodie on.
• 10:07
  SPEAKER_00: Yeah, it's like it's like 56 degrees right now.
• 10:10
  SPEAKER_00: It shouldn't be the same.
• 10:11
  SPEAKER_00: It's just a mess over there.
• 10:12
  SPEAKER_00: Just interrupting my flow, left and right, man.
• 10:14
  SPEAKER_00: Come on.
• 10:15
  SPEAKER_00: I mean sorry.
• 10:15
  SPEAKER_00: All right.
• 10:16
  SPEAKER_00: I apologize.
• 10:17
  SPEAKER_00: All right, we'll we'll summarize here.
• 10:18
  SPEAKER_00: The point is that 14 carbon, too heavy, it breaks down, kicks out an electron, turns into nitrogen.
• 10:25
  SPEAKER_00: Okay.
• 10:25
  SPEAKER_00: That's radiocarbon.
• 10:27
  SPEAKER_00: That's the radioactive version of carbon.
• 10:29
  SPEAKER_00: Radiocarbon is radioactive carbon.
• 10:31
  SPEAKER_00: Carbon 14 is the radioactive version of carbon.
• 10:34
  SPEAKER_00: And this decays over time, and it has a half-life of 5,730 years.
• 10:41
  SPEAKER_00: And half-life means that this thing's eventually going to decay away.
• 10:45
  SPEAKER_00: So carbon-14 is going to break down exponentially over time.
• 10:48
  SPEAKER_00: And Chris, you have an amazing analogy for this.
• 10:51
  SPEAKER_00: Let's go through that analogy to understand half-life.
• 10:53
  SPEAKER_01: Okay.
• 10:54
  SPEAKER_01: First, a half-life, the half-life, like the textbook definition of it, is the time it takes for one half of the atoms that are present to decay.
• 11:04
  SPEAKER_01: So we've talked about this before in previous episodes.
• 11:08
  SPEAKER_01: It's a shoebox analogy.
• 11:09
  SPEAKER_01: If you take a an empty shoebox and you put a hundred pennies in it and you close the lid and you shake it up, however many shakes you give it, right?
• 11:19
  SPEAKER_01: You shake it up a bunch and you open up the lid.
• 11:22
  SPEAKER_01: I have to remove, let's say, all of the tails.
• 11:25
  SPEAKER_01: If I put in a hundred, how much how many statistically should I remove?
• 11:29
  SPEAKER_00: Round about fifty.
• 11:31
  SPEAKER_01: Yeah, right.
• 11:31
  SPEAKER_01: I'm gonna ruin 50 of them.
• 11:33
  SPEAKER_01: So that's one half-life.
• 11:35
  SPEAKER_01: I remove 50.
• 11:36
  SPEAKER_01: So now I have 50 that are head side up in my shoebox.
• 11:39
  SPEAKER_01: I close the lid and I shake it up again.
• 11:42
  SPEAKER_01: I open it up again, and now how many statistically should I remove?
• 11:48
  SPEAKER_00: Round about 25.
• 11:50
  SPEAKER_01: 25.
• 11:51
  SPEAKER_01: That's how half-life works.
• 11:53
  SPEAKER_01: It is half of the half of the half.
• 11:57
  SPEAKER_01: So if each time I do this, where I close the lid and I shake it up and I open it up and I remove the tails, you know, whatever time span you want to pick, it does that represent one day, does it represent 10 days?
• 12:11
  SPEAKER_01: Does it represent, in the case of carbon 14, 5,730 years?
• 12:17
  SPEAKER_01: That's the half-life, the time it takes for one half of those atoms to decay.
• 12:21
  SPEAKER_01: So the first time I did it, I removed 50.
• 12:24
  SPEAKER_01: And and like rookie students want to say, well, okay, the next time you're gonna remove the other 50.
• 12:30
  SPEAKER_01: No, I don't have a hundred.
• 12:32
  SPEAKER_01: It's half of the half.
• 12:34
  SPEAKER_01: And that's the way atoms decay as well.
• 12:38
  SPEAKER_00: And this is the beauty of this analogy, Chris, is because that coin flip scenario, anytime a coin is flipped, it's 50-50 chance.
• 12:45
  SPEAKER_00: It's a probabilistic thing.
• 12:46
  SPEAKER_00: Like you might get 10 heads in all in a row, right?
• 12:50
  SPEAKER_00: You might have that one coin left for many, many half-lives because it's you know randomly getting lucky and it's staying in there.
• 12:57
  SPEAKER_00: But every flip, it's 50% chance.
• 12:59
  SPEAKER_00: That's the same thing as radioactive decay.
• 13:01
  SPEAKER_00: Every atom has a fixed probability of decaying in a year, and that probability just equates up to a half-life.
• 13:08
  SPEAKER_00: We can scale that up and it becomes a half-life when you have billions and billions of atoms sitting there.
• 13:12
  SPEAKER_00: So it's a perfect analogy for radioactive decay, Chris.
• 13:16
  SPEAKER_00: It really, really works well.
• 13:17
  SPEAKER_01: And there's a point to make here, I think, is that every radioactive element, and only certain atoms are radioactive, only certain isotopes are radioactive.
• 13:27
  SPEAKER_01: They're radioactive because they have an unstable nucleus.
• 13:31
  SPEAKER_01: There's nothing that changes that isotope's rate of decay.
• 13:37
  SPEAKER_01: No temperature changes, no pressure changes.
• 13:40
  SPEAKER_01: The half-life is what the half-life is.
• 13:43
  SPEAKER_01: The time it takes doesn't change.
• 13:46
  SPEAKER_01: And each isotope, though, has its own identity for half-life.
• 13:51
  SPEAKER_01: You know, we go to like long extremes, right?
• 13:55
  SPEAKER_00: Yeah, and so if you're sitting there listening, you should be raising red flags in your head right now about radiocarbon because your shoebox analogy, Chris, you're thinking, okay, we've got a bunch of carbon-14 atoms, let's say we got a billion of them, in a half-life, 5,730 years, we open up the shoebox and we take out half, and then we do that again, and 5,730 years later, we do it again and we do it again and again and again and again.
• 14:18
  SPEAKER_00: And pretty soon, like, there's no more carbon-14 kicking around.
• 14:22
  SPEAKER_00: Like, where's the carbon-14, right?
• 14:23
  SPEAKER_00: We're gonna run out.
• 14:24
  SPEAKER_00: So, why is this a useful system?
• 14:26
  SPEAKER_00: Why is there carbon-14 around on Earth ever?
• 14:30
  SPEAKER_00: And the answer is that it's different from other isotope systems that we have talked about on this podcast.
• 14:36
  SPEAKER_00: We talked about in our ancient nuclear reactors and in a couple different episodes, we've talked about uranium.
• 14:40
  SPEAKER_01: That's my favorite episodes, by the way.
• 14:42
  SPEAKER_00: It was a great one.
• 14:43
  SPEAKER_01: Go back and listen to Ancient Nukes.
• 14:45
  SPEAKER_01: That was a great episode.
• 14:47
  SPEAKER_01: I think I'm proud of that one.
• 14:48
  SPEAKER_00: That was fun.
• 14:49
  SPEAKER_00: I agree.
• 14:49
  SPEAKER_00: That that was a really fun one to do.
• 14:51
  SPEAKER_00: But uranium 238, there's a uranium-238 isotope, there's a uranium-235 isotope, they're both decaying away, they're decaying at different rates.
• 14:59
  SPEAKER_00: Uranium-235, we're almost six half-lifes into the decay of uranium-235 from the start of the solar system.
• 15:07
  SPEAKER_00: So there's not much 235 uranium around on Earth anymore.
• 15:10
  SPEAKER_01: We're only one half-life into uranium-238.
• 15:14
  SPEAKER_00: So there's a bunch of that around still.
• 15:17
  SPEAKER_00: Carbon-14, if it has this really short half-life, like why is it still around?
• 15:21
  SPEAKER_00: And the answer is that it's constantly being produced.
• 15:24
  SPEAKER_00: So carbon-14 breaks down to nitrogen 14.
• 15:27
  SPEAKER_00: Actually, in the upper atmosphere, nitrogen 14 is interacting with cosmic rays and being turned into carbon-14.
• 15:34
  SPEAKER_00: So carbon-14 is being actively produced in Earth's upper atmosphere.
• 15:38
  SPEAKER_00: And this means that your shoebox analogy, Chris, I think we need to modify it just slightly.
• 15:43
  SPEAKER_00: And so every time we're going to take this analogy, and every time you open up that shoebox, I'm going to dump some more coins in.
• 15:50
  SPEAKER_00: So you're going to take out all the tails and I'm just going to chuck some more coins in there.
• 15:53
  SPEAKER_00: How do you feel about that?
• 15:55
  SPEAKER_01: Well, uh, like that conjures up a funny mental image of like me doing my little shoebox analogy and you know, very regimented, very focused.
• 16:04
  SPEAKER_01: And then I got the little devil over there, Jesse, just dumping in random carbon 14s when I open it up.
• 16:09
  SPEAKER_00: Like I've got this vision of you up in front of your class trying to, you know, explain, you know, radioactive decay to your students, and you're opening up your shoebox, and I'm sneaking in behind you, chucking them in over your shoulder.
• 16:18
  SPEAKER_00: And Chris is like, what the hell?
• 16:20
  SPEAKER_00: Why are these things not decaying away?
• 16:21
  SPEAKER_00: What's going on here?
• 16:22
  SPEAKER_01: So, first of all, you're a piece of work.
• 16:24
  SPEAKER_01: Okay.
• 16:25
  SPEAKER_01: But second of all, um, I really I don't know where you're going with this because two things.
• 16:31
  SPEAKER_01: You're right, carbon 14 is regenerated in a way that most radioactive isotopes are not.
• 16:38
  SPEAKER_01: But I don't see why it matters.
• 16:40
  SPEAKER_01: I don't see why you have to be dumping in carbon 14 into my shoebox.
• 16:45
  SPEAKER_01: So explain that.
• 16:46
  SPEAKER_01: Sure.
• 16:47
  SPEAKER_01: Does that make sense?
• 16:48
  SPEAKER_00: Like, yeah, absolutely.
• 16:49
  SPEAKER_00: So it's a I mean, it's a great question.
• 16:51
  SPEAKER_00: Leads right into I think the key point is we need a way to stop me from dumping in new coins into the shoebox, right?
• 16:57
  SPEAKER_00: And isn't that just death?
• 17:00
  SPEAKER_00: Exactly.
• 17:00
  SPEAKER_00: That's what it is.
• 17:02
  SPEAKER_00: So if your shoebox is the atmosphere, then carbon is always being produced, carbon is always decaying, and you know, carbon's turning into nitrogen, nitrogen's turning back into carbon, etc.
• 17:12
  SPEAKER_00: We need a way to stop me from dumping in those extra coins.
• 17:15
  SPEAKER_00: We need to, you know, you need to lock me in your little back office of your classroom so I can't dump coins in there anymore.
• 17:21
  SPEAKER_00: And then that is death.
• 17:22
  SPEAKER_00: We are living right now.
• 17:24
  SPEAKER_00: We are respirating, we're breathing in oxygen, we're eating carbohydrates, we're taking carbon out of the atmosphere eventually through our food and putting it into our bodies.
• 17:34
  SPEAKER_00: When we die, that process stops, and that carbon is no longer exchanging with the atmosphere, and now it's just you in your shoebox.
• 17:42
  SPEAKER_01: So the ratio of carbon-14 to carbon twelve in our bodies when we die is representative of the ratio of carbon fourteen to carbon twelve in the air at the time we die.
• 18:00
  SPEAKER_00: Basically, yes, exactly.
• 18:01
  SPEAKER_00: Okay.
• 18:02
  SPEAKER_00: Yes, it's very close to the air ratio.
• 18:05
  SPEAKER_00: So you are if I if you died tomorrow, or if I died tomorrow, we would stop exchanging carbon with the atmosphere and with the food and with the water through our bodies.
• 18:16
  SPEAKER_00: All that carbon-14 would be locked in our cellular structures and it would decay away to nitrogen-14.
• 18:23
  SPEAKER_00: And so basically, we don't actually need to measure nitrogen at all in this system.
• 18:30
  SPEAKER_00: So when we talked about uranium-led dating, uranium-led geochronology, we need to measure uranium, the parent, and lead, the daughter, or the product isotope.
• 18:39
  SPEAKER_00: For this system, we only need to know how much carbon-14 is there in the thing.
• 18:44
  SPEAKER_00: Chris, if you have a lot of carbon-14 in your body and you're, you know, laying there on the street, I can think, oh yeah, actually, you died pretty recently.
• 18:51
  SPEAKER_00: If there's no carbon-14 in you, you died a long time ago because all that radiocarbon decayed away.
• 18:57
  SPEAKER_01: And I know the limit probably isn't quite 10 half-lives, is that right?
• 19:01
  SPEAKER_01: It's not 10 half-lives, is it?
• 19:03
  SPEAKER_00: It's a little bit more than that for radiocarbon.
• 19:05
  SPEAKER_00: People are pushing it up to 80 to 100,000 years.
• 19:08
  SPEAKER_00: So we're like 20,000 times incredible.
• 19:11
  SPEAKER_00: Yeah.
• 19:11
  SPEAKER_01: Because I want everybody to understand when you go through 10 half-lives, you have a tenth of a percent of the carbon 14 left.
• 19:21
  SPEAKER_01: No matter what you started with, it's one tenth of a percent left after 10 half-lives.
• 19:28
  SPEAKER_01: Virtually nothing is left at that point.
• 19:31
  SPEAKER_01: That's my point.
• 19:32
  SPEAKER_01: Okay.
• 19:33
  SPEAKER_00: Very, very, very little.
• 19:34
  SPEAKER_00: Yes.
• 19:34
  SPEAKER_01: Very little.
• 19:35
  SPEAKER_01: And it's amazing to me that they're pushing that even like further.
• 19:39
  SPEAKER_01: And that's a lot further, too, by the way.
• 19:41
  SPEAKER_00: Yeah, that's awesome.
• 19:42
  SPEAKER_00: Oh, it is.
• 19:43
  SPEAKER_00: Wow.
• 19:44
  SPEAKER_00: It's crazy.
• 19:45
  SPEAKER_01: Okay.
• 19:45
  SPEAKER_01: So basically, what I can say is if we started with a hundred thousand atoms of carbon 14 in something, after 10 half-lives, we have a hundred atoms left.
• 20:00
  SPEAKER_01: You know, so there's very little left, right?
• 20:04
  SPEAKER_00: Yeah.
• 20:04
  SPEAKER_00: So, Chris, I think at this stage we should just step back, resummarize the shoebox analogy with me adding coins in, make sure we're all on board with where we're at right now, because we're gonna add another layer of complexity to it.
• 20:14
  SPEAKER_01: So basically, something that was alive dies.
• 20:18
  SPEAKER_01: And it had a hundred thousand atoms of carbon-14.
• 20:24
  SPEAKER_01: But it died 57,300 years ago.
• 20:28
  SPEAKER_01: That means it went through ten full half-lives.
• 20:33
  SPEAKER_01: So at that point, I went from a hundred thousand parent isotopes atoms to a hundred.
• 20:42
  SPEAKER_01: That's all that's left.
• 20:44
  SPEAKER_01: Okay, that's 0.1% of a hundred thousand.
• 20:48
  SPEAKER_01: So there's virtually nothing left.
• 20:52
  SPEAKER_01: That's pushing the limit of what we're able to test.
• 21:07
  SPEAKER_01: So that's just a summary of the shoebox analogy.
• 21:10
  SPEAKER_00: Beautiful, Chris.
• 21:11
  SPEAKER_00: So the shoebox analogy then is that if you're in front of your class, you're teaching radioactive K, you're shaking the shoebox, you've got your 100,000 coins in there, you shake it for one full shake, and that is equal to 5,730 years in radiocarbon uh half-lives.
• 21:26
  SPEAKER_00: And then you open it up and you're gonna take out half of them, you're gonna take out 50,000.
• 21:30
  SPEAKER_00: Radiocarbon, though, remember, in the upper atmosphere, nitrogen is turning into carbon.
• 21:34
  SPEAKER_00: And so I'm sneaking up behind you, you know, I'm chucking some coins into your shoebox here, and I'm messing up this number.
• 21:40
  SPEAKER_00: Like I'm I'm messing this up actively, right?
• 21:42
  SPEAKER_00: As soon as you die, then I stop chucking coins in.
• 21:46
  SPEAKER_00: You get sick of me and lock me in your little office, and then your shoebox just works perfectly, works beautifully.
• 21:51
  SPEAKER_00: But the radiocarbon production rate is not constant.
• 21:55
  SPEAKER_00: So the number of coins I'm throwing in at any given time, whenever you open up that.
• 22:00
  SPEAKER_00: Shoe box, I don't throw in the same number.
• 22:02
  SPEAKER_00: I'm not throwing in 20,000 every time.
• 22:05
  SPEAKER_00: I'm throwing in 20,000 one time, 10,000 another time, maybe one one time, and maybe a hundred thousand one time.
• 22:11
  SPEAKER_00: Like I'm throwing in a different number of coins so that if you randomly die, if you just get fed up with me, lock me in your office, you might have not a hundred thousand coins in that shoebox anymore, but you might have a hundred and fifty thousand coins in that shoebox, which means that the time it takes to get down to 100 atoms is not going to be 10 half-lives, it might be 10.5 half-lives or 11 half-lives, or maybe nine half-lives.
• 22:38
  SPEAKER_00: So it kind of disturbs our clock a little bit here.
• 22:41
  SPEAKER_01: Okay.
• 22:42
  SPEAKER_01: Hold on now.
• 22:43
  SPEAKER_01: Hold on.
• 22:44
  SPEAKER_01: No, it does not, actually.
• 22:45
  SPEAKER_01: Um, it doesn't to me.
• 22:47
  SPEAKER_01: I'm just thinking this through.
• 22:49
  SPEAKER_01: It doesn't mess up the clock.
• 22:51
  SPEAKER_01: What it messes up is the limit to where you can take it.
• 22:58
  SPEAKER_01: Look, the decay rate doesn't change.
• 23:01
  SPEAKER_01: So that's where I'm a little bit confused about like, all right, you're dumping in coins, but it it really doesn't matter.
• 23:09
  SPEAKER_00: That is also true.
• 23:10
  SPEAKER_00: I think let's let's put it in a in a real sort of a real-world analogy.
• 23:14
  SPEAKER_00: Let's say, Chris, you find a dead horse buried in some mud swamp somewhere, and I want to know when did this horse die.
• 23:20
  SPEAKER_00: I give you the thing, you make the measurement, you say, oh, the ratio of carbon 14 to carbon 12 is one to 10,000.
• 23:29
  SPEAKER_00: For every one atom of carbon 14, there's 10,000 atoms of carbon 12.
• 23:35
  SPEAKER_00: What does that mean for the age?
• 23:38
  SPEAKER_00: How do we know what that means for the age?
• 23:40
  SPEAKER_00: That gives us an age, potentially, but how do we go about calculating that age?
• 23:44
  SPEAKER_00: Because that's all the information we have when we're doing radiocarbon dating.
• 23:48
  SPEAKER_00: Well, we have to know what was the carbon 14 to carbon 12 ratio back through time.
• 23:56
  SPEAKER_00: Because then we can calculate how many half-lives did this thing go.
• 24:02
  SPEAKER_00: So we have to know, oh, actually, back in time, there used to be a thousand fourteen atoms to twelve in the atmosphere.
• 24:11
  SPEAKER_00: And that's constant through time, or it's varying through time.
• 24:15
  SPEAKER_01: Okay.
• 24:15
  SPEAKER_00: I'm tracking now.
• 24:17
  SPEAKER_01: Uh like I I get you.
• 24:20
  SPEAKER_01: So that begs the question can we do this?
• 24:25
  SPEAKER_00: Yes.
• 24:26
  SPEAKER_01: That absolutely so this leads to the misconceptions that we alluded to at the beginning of the episode.
• 24:33
  SPEAKER_01: Jesse, let's go into that.
• 24:35
  SPEAKER_00: Let me ask you this.
• 24:36
  SPEAKER_00: You probably run into these a lot in your classroom.
• 24:39
  SPEAKER_00: Do you run across misconceptions about radiocarbon?
• 24:41
  SPEAKER_00: And if so, what are the greatest hits that you come across?
• 24:44
  SPEAKER_01: Radiocarbon dating is the standard for all dating.
• 24:48
  SPEAKER_01: Like that's the number one misconception that I come across.
• 24:52
  SPEAKER_01: Like Okay, we'll come back to that.
• 24:53
  SPEAKER_01: Everything comes back to well, carbon date it.
• 24:57
  SPEAKER_01: Carbon well, carbon dating is junk.
• 24:59
  SPEAKER_01: Because there's so much out there about radiocarbon dating and what it can do.
• 25:08
  SPEAKER_01: And then some people know what radiocarbon can't do.
• 25:11
  SPEAKER_01: And then people say, well, oh, if radiocarbon dating can't do this, then radiocarbon dating is junk.
• 25:18
  SPEAKER_00: Right.
• 25:18
  SPEAKER_01: And so that's the most popular thing that I come across is that you know radiocarbon dating is all over the map.
• 25:28
  SPEAKER_01: And it's not, actually.
• 25:30
  SPEAKER_01: This is very solid.
• 25:32
  SPEAKER_01: I I think if you're talking about something somebody that really has done a little poking around with it, the most common misconception centers around you don't know how much daughter isotope is present.
• 25:47
  SPEAKER_01: And maybe there was a lot of daughter isotope present at the time the decay process started, and you're assuming that none of it was there.
• 25:56
  SPEAKER_01: You're assuming then that the age is much older than what it really is.
• 26:01
  SPEAKER_01: I encounter that fairly often.
• 26:05
  SPEAKER_00: So that's a really interesting point because I I think that brings us really nicely into the later stages of radiocarbon here.
• 26:11
  SPEAKER_00: Is how do we calibrate this curve?
• 26:13
  SPEAKER_00: We've talked about, you know, I'm throwing coins into your box here, or nitrogen is being turned into carbon at different rates back in time.
• 26:21
  SPEAKER_00: How do we calibrate that thing?
• 26:22
  SPEAKER_00: Well, there's several ways to do this.
• 26:24
  SPEAKER_00: First off, tree rings are a really great one.
• 26:27
  SPEAKER_00: So tree rings, really old trees, we can count the years.
• 26:31
  SPEAKER_00: So we can start at today and go back in time.
• 26:34
  SPEAKER_00: We can link up different trees.
• 26:37
  SPEAKER_00: So dead trees plus living trees, we can link up the tree rings to make a longer tree ring segment.
• 26:42
  SPEAKER_00: You know, if we say, oh, there's three really bad years and three really good years and four really bad years, that makes a little barcode that we can match up.
• 26:49
  SPEAKER_00: So we can go back actually really far with tree rings and we can radiocarbon quote unquote date those interior tree rings, and we can calibrate our production curve, our carbon-14 production curve to a tree ring, which is a great way to calibrate this.
• 27:05
  SPEAKER_00: We can also do it with artifacts of known ages, so you know, really well-known ages that are 750 AD.
• 27:13
  SPEAKER_00: We can radiocarbon date that, and it helps us calibrate this production curve.
• 27:16
  SPEAKER_00: And that's actually how scientists first discovered that carbon-14 production rates changed back in time, was looking at artifacts with known ages, and they were slightly off.
• 27:26
  SPEAKER_00: They were a few years off, and so the production of carbon-14 had to have shifted back in time.
• 27:31
  SPEAKER_00: So we we can do this really well.
• 27:33
  SPEAKER_01: That is one of the most interesting points about this whole discussion to me is how carbon-14 has changed, like kind of organically as time goes on, right?
• 27:46
  SPEAKER_01: Let me give an example.
• 27:47
  SPEAKER_01: My dad, love you, dad.
• 27:49
  SPEAKER_01: He's an old bird.
• 27:53
  SPEAKER_00: He said old bird.
• 27:56
  SPEAKER_00: I love that.
• 27:57
  SPEAKER_00: That is such a gentle way of that.
• 28:00
  SPEAKER_00: Is great.
• 28:00
  SPEAKER_00: I'm gonna use that.
• 28:01
  SPEAKER_00: That is awesome.
• 28:02
  SPEAKER_01: I do love you, Dad, but he was alive during the 50s and 60s.
• 28:08
  SPEAKER_01: Oh, yeah, great point.
• 28:10
  SPEAKER_01: We were doing a lot of above-ground testing of nuclear bombs, and that process created a lot more carbon-14.
• 28:20
  SPEAKER_01: And then through photosynthesis and and through what we eat, right?
• 28:25
  SPEAKER_01: These people that were alive at that time have more carbon-14 in their brain stems than you and I do.
• 28:33
  SPEAKER_00: It's just so interesting, right?
• 28:35
  SPEAKER_00: I mean, humans have changed the radiocarbon production curve or the carbon-14 to carbon 12 ratio a lot.
• 28:41
  SPEAKER_00: And another way that we've done it is by burning fossil fuels.
• 28:44
  SPEAKER_00: So, Chris, how much carbon-14 is there in oil or any fossil fuel, really?
• 28:50
  SPEAKER_01: Are you quizzing me right now?
• 28:51
  SPEAKER_01: You are you're a dirty bastard.
• 28:53
  SPEAKER_01: A little quiz.
• 28:54
  SPEAKER_01: A little quiz.
• 28:56
  SPEAKER_01: Well, Jesse, this ain't my first rodeo.
• 28:59
  SPEAKER_00: Um, you've been around the block.
• 29:01
  SPEAKER_01: Yeah, I've been around the block.
• 29:03
  SPEAKER_01: There's none.
• 29:04
  SPEAKER_01: There's no carbon 14.
• 29:06
  SPEAKER_01: No, because this stuff was during the Carboniferous time period.
• 29:11
  SPEAKER_01: This is old coal.
• 29:15
  SPEAKER_00: The production of hydrocarbons, oil, that stuff was all formed from rocks.
• 29:20
  SPEAKER_00: The stuff died a long time ago, tens of millions of years ago, hundreds of millions of years ago, right?
• 29:24
  SPEAKER_01: Like longer than 57,000 years ago.
• 29:27
  SPEAKER_00: That's right.
• 29:28
  SPEAKER_00: So when we burn those hydrocarbons, we put a lot of carbon into the air and it has no carbon-14.
• 29:33
  SPEAKER_01: Which means it's enriched in carbon-12.
• 29:35
  SPEAKER_01: Yep, that's right.
• 29:36
  SPEAKER_00: So we're basically diluting the carbon-14 in the atmosphere now.
• 29:40
  SPEAKER_00: So humans have messed up the carbon-14 to carbon-12 ratio a lot more than it normally would do with this variations in the production of carbon-14 via nitrogen bombardment.
• 29:52
  SPEAKER_00: So, you know, 5,000 years from now, humans are gonna have to do a little bit more careful calibration of radiocarbon dates.
• 29:59
  SPEAKER_00: But I I think it's a really interesting thing that this production curve, at least I find this interesting.
• 30:06
  SPEAKER_00: Chris, you're probably gonna find you're gonna tell me I'm being a little bit too professor, professorial or nerdy or whatever right now.
• 30:12
  SPEAKER_00: That's what I'm saying.
• 30:13
  SPEAKER_00: Two doctory, that's the term.
• 30:14
  SPEAKER_00: To doctory.
• 30:16
  SPEAKER_00: I'm being too doctory.
• 30:17
  SPEAKER_00: But it it gives these really production rate curve, the variations in radiocarbon production rate, so carbon-14 production rate, give us weird uncertainties.
• 30:27
  SPEAKER_00: For instance, some of the Dead Sea Scrolls have been dated by radiocarbon.
• 30:31
  SPEAKER_00: And because of this calibration curve, this variation in the production of carbon-14 back in time, it gives us two different age range possibilities.
• 30:41
  SPEAKER_00: Like I'm used to thinking of uncertainties as oh, that rock is 10 million years old, plus or minus 1 million years.
• 30:47
  SPEAKER_00: So it could be nine or it could be 11.
• 30:49
  SPEAKER_00: With radiocarbon, however, we get like age groupings.
• 30:52
  SPEAKER_00: So for one of the Dead Sea Scrolls, there's a 15% chance that it dates from 355 to 295 BC, and then there's an 84% chance that it dates between 210 and 45 BC.
• 31:03
  SPEAKER_00: So there's kind of like two clusters of probability.
• 31:06
  SPEAKER_00: It could be between here and here, or it could be between here and here.
• 31:09
  SPEAKER_00: And it but it couldn't be in between those things.
• 31:12
  SPEAKER_00: So it's a really interesting sort of nuance of radiocarbon dating.
• 31:18
  SPEAKER_00: Alright.
• 31:20
  SPEAKER_00: You give me that look again, Chris.
• 31:22
  SPEAKER_00: I'm am I totally in the weeds?
• 31:24
  SPEAKER_01: You want to how does that okay.
• 31:26
  SPEAKER_01: No, no, I don't think so.
• 31:27
  SPEAKER_01: I think that's super interesting.
• 31:29
  SPEAKER_01: How does that support the idea that radiocarbon dating is solid science?
• 31:38
  SPEAKER_00: Ooh, good question.
• 31:40
  SPEAKER_00: Uh two things.
• 31:41
  SPEAKER_00: It says that, hey, we're very aware of the uncertainties in this system.
• 31:46
  SPEAKER_00: We're very aware of it.
• 31:47
  SPEAKER_00: We're aware of this back in time, this variation in the carbon-14 production curve.
• 31:53
  SPEAKER_00: We're aware of that.
• 31:54
  SPEAKER_00: We know that it's a potential problem, and we need to incorporate that in our uncertainties.
• 31:59
  SPEAKER_00: So when somebody says it's a 15% chance it's in this range, and an 85% chance it's in this range, that means they're being careful.
• 32:07
  SPEAKER_00: That means that we understand this system enough to accurately apply uncertainty to it and be honest about the uncertainties.
• 32:14
  SPEAKER_00: So I think it shows that we're doing it really well, actually, if you can say, I know how good I am at this.
• 32:23
  SPEAKER_00: It's like, you know, I don't know.
• 32:25
  SPEAKER_00: I love basketball.
• 32:26
  SPEAKER_00: A good player isn't necessarily somebody who's always good at shooting threes.
• 32:29
  SPEAKER_00: You can have a really good player who's terrible at shooting threes and just stays away from shooting threes.
• 32:34
  SPEAKER_00: And they're a really good player.
• 32:35
  SPEAKER_00: And it's this kind of toolbox thing, like radiocarbon's really good for certain things.
• 32:39
  SPEAKER_00: You also shouldn't use it to try and date a 10 million-year-old rock because you're gonna get a wrong answer.
• 32:43
  SPEAKER_00: It's just not gonna be useful.
• 32:45
  SPEAKER_01: That is such a good point.
• 32:46
  SPEAKER_01: I'm really glad you brought that up because that is uh this is an important point regarding radiometric dating that dependent on what you're dating, appropriate isotopes need to be used.
• 33:01
  SPEAKER_01: Yes.
• 33:02
  SPEAKER_01: Not any radioactive isotope will do.
• 33:06
  SPEAKER_01: And that's a very like popular misconception with this.
• 33:11
  SPEAKER_00: That's right.
• 33:11
  SPEAKER_00: You cannot use radiocarbon to date most rocks, most rock types.
• 33:16
  SPEAKER_00: It just doesn't work.
• 33:16
  SPEAKER_00: Actually, really any rock type for the most part.
• 33:19
  SPEAKER_00: Historical artifacts, ancient carbon deposits, that sort of stuff, but nothing more than 50 or maybe even 100,000 years old.
• 33:27
  SPEAKER_01: So even within artifacts, people think that you should be able to date um bricks or mortar using radiocarbon dating.
• 33:36
  SPEAKER_01: And that doesn't work.
• 33:39
  SPEAKER_01: Because there's no like there's no carbon that's inherent in those products.
• 33:45
  SPEAKER_00: Gotta have something that died.
• 33:47
  SPEAKER_00: Yeah.
• 33:47
  SPEAKER_00: And you're dating the time of death.
• 33:49
  SPEAKER_01: That's right.
• 33:49
  SPEAKER_01: That's right.
• 33:50
  SPEAKER_01: That's right.
• 33:50
  SPEAKER_00: Uh well, I don't know, Chris.
• 33:52
  SPEAKER_00: What what do you think?
• 33:53
  SPEAKER_00: Is this a sort of a wrap?
• 33:55
  SPEAKER_01: I hope it's a wrap.
• 33:56
  SPEAKER_01: It was a fun discussion.
• 33:58
  SPEAKER_01: Um, these are the kinds of things that you and I sit on my front porch and we like we talk about this.
• 34:03
  SPEAKER_00: That's right.
• 34:04
  SPEAKER_00: You know, that's right.
• 34:04
  SPEAKER_00: So they're having a couple beers, maybe whiskey, talking about carbon dating.
• 34:08
  SPEAKER_00: It's so good.
• 34:09
  SPEAKER_00: I think it's just really cool.
• 34:11
  SPEAKER_00: And radiocarbon dating, if you ever have the chance to go into a radio carbon dating lab, they're totally cool.
• 34:17
  SPEAKER_00: It's a huge room that stores these instruments to do this type of analysis is really difficult, and it's got to be really good to do it.
• 34:25
  SPEAKER_00: They're just impressive stuff.
• 34:26
  SPEAKER_00: Uh, this whole technique is really, really impressive.
• 34:29
  SPEAKER_01: I guess the summary then that I want to end this episode with is a statement by you about radiocarbon dating.
• 34:40
  SPEAKER_01: How solid are we talking?
• 34:43
  SPEAKER_00: Oh, very solid when applied appropriately.
• 34:46
  SPEAKER_00: No, radiocarbon is super solid.
• 34:48
  SPEAKER_00: We understand the system really well.
• 34:50
  SPEAKER_00: Don't try and date a rock with it because you're just using the wrong tool.
• 34:55
  SPEAKER_00: You're using a screwdriver for a nail.
• 34:57
  SPEAKER_00: Like, what are you doing?
• 34:58
  SPEAKER_00: You're being an idiot, you know?
• 34:59
  SPEAKER_00: Uh, so go use something more appropriate.
• 35:02
  SPEAKER_00: Use uranium lead, geochrinology, potassium argon, something like that.
• 35:05
  SPEAKER_00: Uh, radiocarbon's great, though.
• 35:06
  SPEAKER_00: It is so cool, and it has been such a massively important development for the geoscience community, the archaeology community, the history community.
• 35:16
  SPEAKER_00: It's one of these techniques that has its fingers in all sorts of scientific disciplines now.
• 35:24
  SPEAKER_01: And again, one of the coolest things for me about radiocarbon dating and the way it's done is it involves mass spectrometers.
• 35:32
  SPEAKER_01: And the idea that a mass spec can pick up the difference in mass between carbon 12, carbon 13, and carbon 14.
• 35:44
  SPEAKER_01: That blows my mind.
• 35:46
  SPEAKER_01: It's so cool.
• 35:48
  SPEAKER_01: Go back to our episode on geoscientific discovery.
• 35:53
  SPEAKER_01: It was an interview where I talked to Jesse specifically about mass spectrometry and how it's done.
• 35:59
  SPEAKER_01: It's amazing stuff.
• 36:01
  SPEAKER_00: Yeah, we do cover mass spectrometers.
• 36:04
  SPEAKER_00: Uh, you could don't get me gone.
• 36:05
  SPEAKER_00: We should end it before we get on the mass spectrometer train because we should we'll be here all night.
• 36:10
  unknown: Yep.
• 36:10
  SPEAKER_01: But I think that's a wrap.
• 36:12
  SPEAKER_01: I think that's good.
• 36:12
  SPEAKER_01: It was a different episode for us, but a lot of fun.
• 36:15
  SPEAKER_01: I loved it.
• 36:15
  SPEAKER_01: It's been too long.
• 36:17
  SPEAKER_00: So totally glad to get back at it, Christopher.
• 36:20
  SPEAKER_00: Hey, follow us on all the social medias.
• 36:22
  SPEAKER_00: We're at Planet GeoCast.
• 36:23
  SPEAKER_00: Send us an email, planetgeocast at gmail.com.
• 36:26
  SPEAKER_00: We have a listener question episode coming up pretty quick.
• 36:29
  SPEAKER_00: So get your questions in and we'll throw them in there.
• 36:33
  SPEAKER_00: The best thing you can do, well, not the best thing, the second best thing you can do is leave us a review and a rating on your podcast platform.
• 36:40
  SPEAKER_00: That really helps the algorithm.
• 36:42
  SPEAKER_01: And the best thing you can do is share this with somebody that you think would love Planet Geo and who cares about our amazing planet.
• 36:52
  SPEAKER_00: There you go.
• 36:53
  SPEAKER_01: Peace.
• 36:53
  SPEAKER_01: That's a wrap.
• 36:54
  SPEAKER_01: Cheers.