Do you have the correct time?

Inside Science introduction

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1:14Welcome to Inside Science from the BBC World Service. I'm Tom Whipple. This week, why is the earth revolving too fast? Why does that mean that time is ticking for something called the leap second? And why is Bill Bryson using the word debauchery in the context of Britain's most respected scientific institution? Something that never revolves too fast is the return of the not at all debauched Kit Yates to Inside Science. The mathematician has been searching the journals for

1:45the best of the best of the other stories. Kit, time is already ticking for us, so get on with it. What have you found? So, Tom, this week I'm going to be finding out exactly how much of a hot-blooded predator T-Rex really was. And in keeping with that theme, I'll tell you about a new record temperature for the survival of complex life. Brilliant. Well, look, tick-tock. It all went wrong in 1955. That was when we made a clock that was too accurate. More accurate than the sun. And we have been dealing with the consequences,

2:20technological, metrological, philosophical, ever since. Now, this tale of excited caesium atoms, excited diplomats, and a fudge called the leap second may be coming to its denouement. Next month, a group of experts from around the world are going to be meeting to decide exactly what time it is. Does that make sense? I suspect not. But we went to the National Physical Laboratory in West London to go to the place where UK time is made, and had it explained to us by Setnam Shamar,

2:54Principal Scientist at NPL's Time and Frequency Department.

The atomic clock and the leap second

2:58OK, so we are in the UK's National Timescale Lab at the National Physical Laboratory. And this is the laboratory where we generate the UK's official source of time. What does that mean? Which one of these many boxes is the clock, and how does it spread around the country? This lab is like the nerve centre where we generate the National Timescale. But in fact, we have several atomic clocks around the site. One of those clocks in a different lab is the

3:31reference clock. And all the others are used as backup clocks. And we compare their signals continuously. In case the reference clock fails, then we can fall back to one of the other clocks. And why do we need it? My wristwatch isn't connected to your clock. There are a lot of users of accurate time around the country. We have, for example, telecommunications, electrical grid operators, financial institutes that timestamp financial transactions. And its timing is also used in transportation, in positioning,

4:04in emergency services, and so on and so on. Many of those industries, and some of them are national, critical national infrastructure, they get their time from satellite navigation systems, for example, GPS. But some of them, the most critical ones, get the time directly from us. So timing is important in modern technology. What is an atomic clock? A clock that's based on atomic processes, such as like in the cesium atom. And these clocks are very accurate clocks. And they are far more stable than any other type of clock that has ever been

4:41developed, including keeping time using the sun, which is solar time. Basically, the sun has always told humans the time. And we've made these clocks where we've been trying to see what the sun is doing. And we've made the mistake of making one that's better than the sun. So now you've got to adjust for the difference. That's right. Humans did keep time using the sun for many thousands of years, which depends on the rotation of the earth, which is irregular and unpredictable. So in 1972, leap seconds were introduced, typically every few years, when atomic time has diverged from

5:21solar time by almost one second, then a leap second is applied to atomic time to line it up again with solar time. And so what does that mean that there's a second that's been repeated in my life? I mean, what actually happens? Generally, what happens is that in these leap seconds, we've always added one second to atomic time. And in modern technology systems, that can be problematic, because different systems can apply

5:52leap seconds slightly differently. And that can cause timing conflicts between different networks. So that is something that we want to prevent. More recently, it's become more urgent, because the rotation has been speeding up a little bit. What that means is that another leap second would be required, but it would be required in the opposite direction from normal. It would be a negative leap second. And a negative leap second has never been applied before. Practically, what would it mean? Would it mean on December the 31st, we have a nine second countdown

6:24to midnight? Do we miss out the nine, miss out the eight? What would happen is that we miss out the 59. We jump straight from 58. So there would be a second that never existed? That's right. So I know that there's for a while been a push to get rid of all sorts of leap seconds. This, as I understand it, is precipitating a move to maybe get rid of the leap second entirely this October? At the International General Conference for Weight and Measures in 2022, it was decided that leap

6:56seconds would stop being applied at the latest in 2035. However, because of the additional urgency of this potential problem of a negative leap second, a resolution has been brought forward. What's being proposed and what will be voted on is that instead of applying leap seconds, the tolerance would increase from one second to one hour. So that's absolutely insane, isn't it? You are stipulating what your successors are going to do.

7:28So how long would it take to accumulate a leap hour? Yeah, so it would take thousands of years. So this is like Caesar having just sort of perfected the water clock telling you what you should be doing with your atomic clocks. I mean, it would be a good thing because it would not be necessary to apply these disruptions to the smooth running, the smooth operation of coordinated universal time, which could cause, there is a possibility of it causing chaos. And this is what we are trying to prevent,

8:00including in national infrastructure. Setnam Shamar, Principal Scientist at NPL's Time and Frequency Department. Does that all make sense now? Well, no, not quite, because there's one exciting and crucial mystery left and quite an important one. That mystery, why is the Earth spinning faster when it normally spins slower? Why, in fact, does it normally slow? To answer that question, we need not a metrologist or a physicist, but a geophysicist. Claire Nicholls is Associate Professor of the Geology

8:31of Planetary Processes at Oxford University.

Why the earth is spinning faster

8:34Yeah, that's a great question. So the Earth has been slowing down across the whole of its history. So Earth formed around four and a half billion years ago, and there was a lot more energy in the solar system then. So everything was rotating very, very rapidly. The moon was much closer to us. And then over geological time, the rotation rate has slowed down and the moon has gradually drifted away. So our days have got longer and longer and longer. Where's it losing energy to? Where's it disappearing off to? So the energy is being dissipated basically by the interactions between all the bodies in the solar

9:10system. So actually, the moon is slowing us down. So the tidal drag between the moon and the Earth means that the system loses energy over time. Does this mean that Tyrannosaurus Rex had a shorter day? Yeah, absolutely. Yeah, he had less time to go about and do his business. Okay, so this makes sense. The Earth's losing energy. We're slowing down, presumably eventually what we're just going to end up just facing the moon. And what's the final state of us? Yeah, it will take a lot, lot longer. So I suspect there are more sinister consequences

9:42for the whole solar system before we actually stop rotating. It's a pretty slow process. Okay, but anyway, so that's the normal thing. That is our long term fate. We will slow and slow and slow. But just at the moment, we're not. So why? Yeah, that's right. So right now, we're actually slightly speeding up. And it's a really, really small change. So this is on a much smaller scale than this kind of long term slowing. So actually, the length of the day kind of oscillates on kind of decadal and millennial

10:13timescales. And the reason for that is quite complicated. There's lots of factors that affect the length of the day. The moon, as I've already mentioned, is one factor. So the drag between the moon and the Earth, they're gravitationally speaking to each other, that causes us to slow down. The distribution of mass on the surface of the Earth causes us to slow down or to speed up, depending on where it is. And the interaction between the rocky part of the Earth that we call the mantle and the core, which is made of metal, also causes us to speed up and slow

10:45down. Okay, so at the moment, it's the speeding up bit. So let's forget about the moon. Mass on the surface. So what's that all about? How is that going to make us speed up? Yeah, so the mass of the surface of the Earth is not evenly distributed. So if you just imagine what the Earth looks like, in some places, we have ocean, in some places, we have land, that land varies in thickness, depending on where we have things like mountains and older bits of rock compared to younger bits of rock. And then we also have things like glaciers.

11:15And all of that moves around over time. And depending on whether it ends up near the poles or near the equator, that controls how fast we spin. And so the thing that I'm thinking of that's most likely to have moved around recently is we're losing a lot of glacial mass. So presumably water up high is moving to lower down. Yeah, exactly. So that's one factor that will control the mass. So you can imagine it being like an ice skater spinning. And if you stick your arms out, compared to kind of crouching inwards, that will change how quickly you spin. And whether we have that mass mostly at the

11:49equator, that's like having our mass kind of spread out compared to being at the poles. That's really the effect that's controlling it. So glaciers will play an effect in that, but it is small. Okay. But now the really interesting stuff, what's going on inside the Earth? How might this be making us spin faster? Yeah, there's a really interesting relationship between the core in the centre of the planet that's made of metal and the overlying mantle. The connection between the two basically creates torque. And so that means that it can either force the Earth to rotate slightly faster or slightly

12:25slower, depending on the relationship between the two. And what is the interaction? Is this friction? Is it magnetism? What's going on? Yeah, so there's several different ways that they can interact. So one way is the topography on the core mantle boundary. So you can think about this like the topography on the surface. Often when you see a cartoon of the Earth, we draw it as a perfect circle with little layers inside that are also perfect circles. But actually, that's not what it looks like. It's going to be a bit bumpy. And those bumps are not very big, but they're still going to generate friction.

12:58So when the liquid metal core is trying to flow past the solid rocky mantle, it's going to get stuck. And then that's going to cause these slight changes. And the other thing that happens is the core is generating a magnetic field. So we call that the geodynamo. And that can generate an electromagnetic torque with the mantle. Very much like the way in electric cars, you have the magnet rotating to make the motor. It's kind of the same thing. So that force between the two

13:29electromagnetically can also change the length of the day. So in the Earth, we've got, so there's a certain amount of sort of fixed turniness in the Earth or angular momentum. And that is slowly being diminished. But you can distribute that in different ways within the Earth and in the Earth as a whole. So if the core starts spinning more, then maybe that can manifest it as less spin on the outside. Yeah, exactly. We have a solid inner core and a liquid outer core. And there's observations that

14:03suggest that the solid inner core is actually kind of rotating slightly either ahead of the rest of the planet or behind the rest of the planet. And it seems to do that on kind of a 70-year timescale, roughly. And so if it gets slightly ahead of us, it makes the days go slightly faster. And if it gets slightly behind us, it makes the days go slightly slower. So looking at sort of the past experience of this, when are we going to start slowing again? We should start slowing down again in the next few decades. So over our lifetime, we'll probably go back to having a slightly slower day.

14:35Claire Nichols from Oxford University. Kit, so it turns out there's been several years in our lives where we've counted down to 10 at New Year's Eve and actually popped the champagne cork a second too soon. No, it's sort of disappointing, isn't it? I think we'll, I mean, most people will be familiar with leap years, right? Both leap years and leap seconds are ways of keeping our time on Earth in sync with the movement of celestial bodies, speaking grandly. Leap years, they were about adjusting our calendars for the Earth's rotation about the Sun, while these leap seconds allow us to adjust our clocks for the

15:11Earth's rotation about its own axis. That's the sort of simple distinction, I think. Yeah, and this is, the leap second is obviously a lot more ad hoc. We know when the leap years are going to be going through to the end of time, but... Yeah, exactly. And I think maybe the other important distinction is that the disparities caused by leap years accumulate more quickly and more noticeably than those caused by leap seconds. So over a hundred year lifespan, you would notice losing 24 days, but over a hundred year lifespan, you probably wouldn't notice midday shifting by a minute or so. Yeah, yeah. You're listening to Inside Science from the BBC World Service. Tell us about science you

15:45think we should be investigating. Our email address is insidescience at bbc.co.uk.

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17:21Claire mentioned that T-Rex roamed an earth where it had to get all of its business done in a shorter day. You've got some more insights into how it did that business. Yes. I mean, how did it fit all that hunting and tearing limb from limb stuff in? So I think when we're thinking about reptiles, one of the first things that comes to mind, for me at least, is like lizards sunning themselves on rocks to warm up or crocodiles basking on the riverbank. So I guess it would be natural to assume that other reptiles like dinosaurs also exhibited this what's called cold-blooded physiology. And that was the prevailing view until about 50, 60 years ago. But it's been

17:57hypothesised for quite a while now that large dinosaurs probably maintained a warmer body temperature higher than those of the surroundings, allowing them to be more active, to fit more stuff into their day. And the evidence of this has been building over the decades. But this week, scientists writing in the journal Science Advances have now effectively stuck a thermometer into the mouth of the most famous dinosaur of them all, T-Rex, and found that T-Rexes were running at about 36 degrees, give or take a couple of degrees. How? How did they? I mean, it feels astonishing you can do that from a fossil.

T-Rex body temperature and heat-tolerant amoebas

18:28Yeah. So they used a technique called clumped isotope thermometry. So this exploits the fact that tooth enamel in particular contains different isotopes of carbon and oxygen. So carbon 12 and 13, oxygen 16 and 18. And the heavier isotopes, the ones with the higher numbers, so carbon 13, oxygen 18, they tend to bunch together at lower temperatures or clump together, hence the name clumped isotope thermometry. Whereas at higher temperatures, they're more spaced out. So the degree of clumping acts as a record of what the temperature was that the enamel formed at.

19:02Extraordinary. And this isn't the only news in temperatures this week, is it? No, exactly. So scientists in the US and Europe, writing appropriately enough in a journal called Cell, they've discovered an amoeba, so a single-celled organism, which breaks a long-standing record for temperature tolerance in what's sometimes referred to as complex life. So I need to give you a little bit of background. By complex life here, I'm talking about eukaryotes. So there are three domains of life at the root of the tree of life, bacteria, archaea, and eukaryotes. And these

19:35eukaryotes probably comprise most of what we think about when we think about life. This is us, is it? Yeah, or the animals, plants, fungi, and so on. And they're much more complicated eukaryotes than archaea and bacteria. They've got nucleus, mitochondria, complex internal cytoskeletons. But this complexity that allows eukaryotes to do all sorts of cool things means that they actually have a disadvantage when it comes to living at high temperatures. So the overall record for thermophilic organisms or heat-loving organisms is, well, bacteria have been found to live up to 100

20:05degrees. Archaea have been found to live up to 120 degrees. But until recently, it was thought that eukaryotes just couldn't live above about 60 degrees the sea. It was just thought that that was just part of the master plan. So these scientists, what they've done is to find a new amoeba, a single-celled eukaryotic organism, which they've called Incendamoeba cascadensis, which roughly means fire amoeba from the Cascades, the volcanic mountain range where it's found. And this amoeba has been found to live and survive and reproduce up to 63 degrees centigrade. 63 degrees. Well, look, talking of temperatures and talking of hotting up, next week we have the

20:41hottest event of the scientific calendar. No, not some prize called the Nobels. That's the week after. I mean, of course, the Royal Society Trevady Book Prize. Each week we have an interview with one of the shortlisted candidates. One of them will go on to join a list of winners that include Stephen Hawking and Stephen Jay Gould, Andrea Wolfe and Caroline Criado-Perez. This week, before our final interview,

Bill Bryson on the Royal Society science prize

21:07we spoke to another of those past winners and a former judge. We asked Bill Bryson why he holds the prize in such affection. Yes, I won it. And then since that time, I've judged it twice. So I have a kind of longstanding association with it and a great fondness for it. I think it's a wonderful prize. What's the value of this prize? Oh, well, I think, I mean, I think it has multiple values. I mean, it's very good for the authors that are winners or on the shortlist. I think it's very good for science books generally, because it just attracts some attention to the

21:39field. And I think it's very good for the Royal Society, because it has a sort of ambition to engage in public outreach. And I think there are not many ways that you can do more valuable work than helping to promote popular science writing. You know, a good popular science book can attract a lot of younger people to go into that field. And one of the most heartening things for me is I've had over the years, a number of people say to me, oh, I, you know, I decided to become a scientist after reading your book when I was 13 or whatever. And that's really lovely. And I think that's a very,

22:11very important service that the Royal Society is providing. And what about the night itself, the sort of the greatest honour that can be bestowed on a science writer? I'd imagine it gets pretty wild with all those Nobel Prize winners. Well, I've been listening to your descriptions in recent weeks, and I really hate to disappoint you, because the Royal Society is not someplace you go to for a debauchery. But it is a really lovely evening. And it's a very nice evening. It's just a sort of a celebration. The six shortlisted people are obviously very excited and, you know, enjoying the experience that they tend not to get a lot of

22:47attention for the kind of things they do. And it's a room full of people who care very much, publishers and authors and just people generally in the world of science, who care very much about the importance of this prize. So it's, it's a very, very nice evening. Bill Bryson, who will join Bryson in the list of august winners of the Royal Society Trevady Prize?

Microchimerism and cells from other people

23:08The final shortlisted candidate is Lise Barnau, author of Hidden Guests. And as she explains in her book, if she does win, then in a very real sense, it won't just be her winning. It is in fact, for her and all of us, harder than you might think to say what an individual person is. My book describes a biological phenomenon called microchimerism. This is the fact that we all carry cells from other individuals within us. So these cells can be

23:43hidden in our blood, our heart, our lungs, or even sometimes in our reproductive organs. And inside those cells, well, you have genomes different from our own genomes because they originated in another person. And this could be from your mom, from your maternal grandmother, your older siblings. If you are a woman, it could be from all the embryos you've ever carried, whether or not they result in a living birth. This is all very new research, as in you chart the story of it going from being

24:16heretical to being considered a mere curiosity, but not of interest, to being considered something that could actually be quite important. Can you take us briefly through that history? True. Actually, it's more than a century that we have discovered that fetal cells can go inside the mother's body. So we were first thinking maybe it's only a contamination, or maybe it's only because the person is sick. But finally, we realized that it's a natural

24:48phenomenon that affects not only humans, but every animal with placenta. And only since the 20s, we are now considering this phenomenon as real and as really interesting also in terms of potential applications in medicine. Listeners might be familiar with the research that if you're a woman and you're pregnant, some of the fetal cells remain in you. Can you explain why I might have foreign or do have

25:18foreign cells within me and where have they come from? That's a very important aspect of the story. It's not a woman thing. Microchimerism is really concerning everyone only because we all span nine months in a womb. And that's where the first cells exchange happened. So when we are in the womb of our mother, we can acquire cells from our mothers, but also all the microchimeric cells our mother host. And our mother, they host their

25:52mother cells. So actually a French teen discovered only a few years ago that we can find the maternal grandmother in the blood of newborn. And because the cells exchange are going both way from the fetus to the maternal organism, but also from the maternal organism to the fetus. When we are in the womb of our mother, we can also acquire cells from older siblings that were in the same womb before us. So all the brothers and sisters.

26:25You quote a paediatrician and geneticist saying, so you think your mother is always looking over your shoulder. She may actually be in your shoulder, which you thought was a very funny quote. But is this more than a curiosity? Because your book argues that this is important. It's not just stray cells that persist. These could have a useful and important biological purpose and existence. Even beside this curiosity, there is an importance of the cells because now only since, let's say,

26:5710 years, we are discovering what these cells do. And they are not haemless drifters. They're really actively integrated in our organs. And once they are there, they multiply, they produce proteins, they communicate with the other cells for better and for worse. For instance, there's a study which documents a case of a mother's cells producing insulin for a diabetic child whose own pancreas could

27:27not do so. And several other studies are showing that cells from fetal origin are coming specifically in a damaged organ, for instance, the heart, and they can contribute to regenerate the tissue. So now scientists are trying to use these cells to repair tissue. You move into the, I guess, the philosophy, the theology, even in the emotion of this, you talk about people's reaction to realizing this is going on. There's quite a moving bit where you speak to

28:00a researcher who talks about a young woman who came up to her after one of her presentations and says that, you know, her daughter had died when she was young. She was visibly comforted, glad even to imagine her child still somehow existing through microchimerism. How do people react to this? Yeah, well, you know, I've been a science journalist for 20 years, and I think I've never received as much interest as I have with my chimera stories. This is really as if this microchimeric cells open the door to the intimate, and they reveal both your fears and your desires.

28:38That was Lise Barnou, and that's it from us. We do hope that you and your microchimeras can join us next week when we have a special edition from CERN. To discover more fascinating science content, search for the BBC Inside Science and follow the links to The Open University. But for now, it's goodbye from me and goodbye from Kit. Bye, everyone. And it's goodbye from Kit's microchimeras. Bye. Very good. I'd imagine that's what they sound like.

29:08You've been listening to BBC Inside Science with me, Tom Whipple.

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