The Infinite Monkey Cage - Fire

Episode Date: February 3, 2020

Fire!Brian Cox and Robin Ince are joined by comedian Ed Byrne, forensic chemist Niamh Nic Daeid and biologist Adam Rutherford, as they explore the science of fire and how it has impacted the evolution of life on earth. They also look at whether controlling fire is a uniquely human trait and how other species have evolved to use fire to their advantage.Producer: Alexandra Feachem

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Today we'll start with one of the most beautiful introductions to a science lecture and it's from Michael Faraday's Chemical History of a Candle. He said, there is not a law under which any part of the universe is governed which does not come into play and is touched upon in the chemistry of a candle. There is no better, there is no more open door by which you can enter into the study Which is beautiful, but it's not right. You have to spoil everything, don't you, with your evidence-based thinking. There's always something, isn't there? It's not his fault. He didn't know about nuclear forces. So you need nuclear forces to understand how stars shine for example just so you know by the way evidence-based thinking is very 20th century we're not doing

that in the 21st century anymore haven't you been looking around at the world in today's show we'll be talking about fire what is it how did we learn to harness it and why is it so hard to control to guide us through the science of fire we're joined by three people who have studied the chemistry of fire the physics of fire or at the very least waved a lighter around while REM played Everybody Hurts and they are... I'm Adam Rutherford and I'm a geneticist and you know me from Inside Science and the Curious Cases of Rutherford and Fry. I've written about the role of fire in evolution and I want to take this opportunity to apologise to my father because as a teenager I pretty much burnt everything. So sorry dad for the whole pyromania thing. I'm Niamh Nick-Dade,

I am a professor of forensic science at the University of Dundee and I'm a director of a research centre in forensic science. I'm also a fire investigator. why do i like fire and what do i most like about fire i like having an open fire in my living room in the right place obviously um because i just like the comfort of it it gives us great comfort and great i don't know whimsicalness when you look into its flames my name is ed barn i am a stand-up comedian except when i'm on shows like this when i'm a sit down comedian and my favourite use of fire, apart from having it as an open fire, and I find it very comforting as well,

but I find most comfort comes from its use for destroying evidence. And this is our panel. But does it though, guys? See, Niamh, you thought you'd come here actually just to do a show as an expert. In fact, you've come here to solve the crime. And it was much easier than we thought.

He's given it away already. It was him what done it. But I have to say, there's a misconception that fire destroys all evidence. I can see him destroying all of it. So, Ed, let's just work out then. So what have you tried? And then Niamh will tell you what you've done wrong

in trying to destroy your evidence. This is going down a very different way than we'd originally thought, by the way. After joyriding, torch the car. Yeah, always. I don't know. I didn't expect to have my feet held to the flames over this.

He said wiggling his hands. So what do you reckon would have been the best thing for him to have done with that car? Drive it into a lake. Or a quarry. Better. Quarry. Quarry's better. Oh, you mean a flooded quarry? Yes. Are there still going to be fingerprints after a burnt out? Or a quarry. Better quarry. Quarry's better. Oh, you mean a flooded quarry? Yes. OK, right.

Are there still going to be fingerprints after a burnt out...? You can recover fingerprints, yes. In actual fact, soot will enhance fingerprints. You can see them easier because the soot sits in the pores of the fingerprints so you can visualise them. So anyone who's trying to work out who Father Christmas really is, oh, this is great. Anyway, so... Anyway, we've covered the crime, that part of the...

Just general hints there for people hoping to commit crime. But also, we always start with a definition, and this might seem strange when we're talking about fire, but we actually want to know, what is fire? What do we mean when we say fire? So I thought I'd show you, because you can't, as a fire investigator, or people who like fire,

you can't have a fire, talk about fire without having a fire. So I've got a candle. So I'm going to light the candle with my match. There we go. So what is fire? Fire is a chemical reaction. So it's a reaction when you've got a fuel and you heat that fuel up, which is what I just did by putting the match to the wick of my candle. And you heat that fuel up in the presence of oxygen.

And as you heat the fuel, you cause it to turn into a gas. And it's the mixture of the gaseous fuel, volatile gases and oxygen in the presence of an ignition source that produces this chemical reaction which you can see in front of me and it produces light it produces heat it produces uh products like water and carbon dioxide and carbon monoxide and other stuff so fire is a chemical reaction so so what what is the i need an equation give me an outline you do know that is his catchphrase as a physicist just one more thing i need an equation i'm a chemist i'm not a physicist so but do you have just roughly what's the outline equation so you mentioned there so you've got usually fuel contains carbon and hydrogen so you've got something with carbon and hydrogen with it mixing with oxygen with o2 and you introduce heat and it turns into water h2o carbon dioxide carbon monoxide and other products what sort of things burn so we're looking at a

candle there it's the there's the wax, there's obviously the wick. What is it that's actually burning? So what's actually burning, there are a couple of really important components to causing a flaming combustion. So you see a flame, you need to have a fuel and the fuel can be anything really that contains carbon and hydrogen, but it contains other things as well. You need the presence of oxygen in the air and you need the presence of heat to start the reactions occurring. So what the heat is doing and what you can see, well you see it in a moment, what the heat is doing is it's taking a solid fuel and it's turning it into a gas. So solids don't burn, liquids don't burn, you have to turn them into a gas first. a gas. So solids don't burn, liquids don't burn, you have to turn them into a gas first. And it's a process called thermal decomposition. So you're breaking the bonds in the molecules of the

particular material that you're setting on fire, whether it's wood or plastics or whatever it is. So you put heat energy in. And as that heat energy evolves a gas, and you mix that gas with oxygen in the air, and you introduce an ignition source, my match, then you'll get that chemical reaction occurring. So it's always the gas? Yes, yeah. So if you, OK, if you touch lava in a vacuum, it'd still hurt,

but could you technically not say that you were burnt? Would there be other issues as well? Because as well as the burning, you're in a vacuum. So you may also be preoccupied with other... burnt would there be other issues as well because as well as the burning you're in a vacuum so you may also be preoccupied with other is this another of your crimes that you're working out because i'm seeing there may be flaws in a lot of them obviously i'm speaking hypothetically you know the uh were you the kind of kid who played with matches are you someone who's a little bit i'm obsessed with fire now i am'm a massive fan of it.

I spend an inordinate amount of time chopping, sawing wood logs, moving them about, building storage facilities for wood, stacking it, admiring it, moving it into the living room, admiring it again, setting it on fire, sitting and staring at it.

And I'm sure Adam will tell us about the evolutionary aspects of fire. And I wonder, when you sit and you stare at fire, because fire has been such an important mover in our evolution, is there genuinely an evolutionary... Do we enjoy looking at fire in the same way that we enjoy looking at a prospective sexual partner, say? You know what I mean?

The same urge, that primal urge you have to recreate. No, go with me on this. The crimes, the crimes. How many more crimes? Sex feels good because it's an evolutionary imperative, okay? That's why it feels, there's no logical reason

why something so filthy should feel so good. But it does. And I just wonder if this, we can enjoy watching a fire far more than you enjoy watching a soap opera, right? So is there an evolutionary aspect to that, our enjoyment of it? Yeah, well, I mean, the first thing is

I hope that you don't look at fire in exactly the same way that you look at a prospective sexual partner, because in which case you're doing both fire and sex wrong. This programme goes out at 4.30 a monday on the school run and just remind you of that adam so the question is evolutionary yeah so from an evolutionary perspective fire is an absolutely essential part of human evolution it's been with us for well since before we were homo sapiens as evidence for fire associated with homo erectus up to a million and a half years ago we look like we've got it under control by about a hundred thousand years

ago possibly a bit longer than that but from a from an evolutionary perspective it fire does so many things and we have evolved alongside fire for all of that time so for example it allows us to keep warm so we can move north from the equator. So our expansion around the Earth is dependent on our ability to control fire. But also it allows us to cook food. And this is an essential part of our evolutionary development because it means that we have to spend less time foraging,

less time eating, because fire is effectively like pre-digestion before we put it in our mouth and you know time you spend eating is time you risk being eaten because our mouths are quite near our our eyes so we can't it's hard to look out uh for predators if you're you know chowing down on something on the ground is that why a lot of mafia hits take place in restaurants there's a lot of mafia hits take place in restaurants? There's a lot of crime coming from Ed Byrne here. You said 100,000 years ago.

How do we trace that point where human beings, their ancestors, had control of fire? What is the kind of record that we see left behind? So earlier than that, we do see clear evidence of fire, although it's quite sparse and it's quite difficult to account for. What we also think is that it might be naturally occurring, as in it's been started by lightning. By 200,000 to 100,000 years ago, we have evidence of hearths,

you know, centralised cooking areas, kitchens in caves. We also have evidence that Neanderthals had control of fire as well. So there's one dig site in Tuscany where some wooden clubs have been excavated. And of course, wood doesn't preserve very well over tens or hundreds of thousands of years, so this is quite rare. And it's boxwood, which is particularly hard, but it's quite clear that the outside of it has been deliberately burnt in order to take away the small twigs. So it's not just Homo sapiens, it's humans clear that the outside of it has been deliberately burned in order to take away the small twigs.

So it's not just Homo sapiens, it's humans much more broadly, maybe as far back as Homo erectus, but definitely Homo neanderthalensis. So there are a lot of points you made there. So I can see it's an interesting idea that to move out of the Ritter Valley and certainly to move into Europe, you need fire to keep warm. But you mentioned about digestion. Fire is the use of fire. It's pre-digesting the food. Could you elaborate on that? Yeah, well, we spend time chewing food

and we chew food which helps break it down and release chemical bonds. And there's enzymes in our saliva which does the same thing. And then when it goes into our stomach, the whole process of eating is just extracting energy from food, from the stuff that we consume. What cooking food does is make that process happen before we put the food in our mouths.

So we spend a way disproportionately small amount of time eating compared to almost all other animals, especially our closest relatives like gorillas and chimpanzees, who spend an inordinate amount of time eating eating we spend a lot less time eating food and a lot more time watching television programs about preparing food that's that's what we've been able to use our evolutionary gain for yeah but you shouldn't underestimate the the the importance of the length of time we spend eating because loads of other animals do that as as well so we know that vervet monkeys in south africa spend much less time foraging in areas where the grass

has already been burnt down and um meerkats you know meerkats when they stand up on their their legs they're not just doing that to be super cute let the record show he's doing the meerkat hands because it is impossible to say the word meerkat and not do the meerkat yeah i i now realize i'm actually doing the meerkat impression meerkats stand up on their back legs not to be super cute but because they're actually looking out for for predators but when you time meerkats eating in high grassland they spend a lot more time on their feet looking out than they do in areas which have been burnt down. And they know this. And loads of animals know this because they can simply see further.

So it's just another example of many animals that have quite a sophisticated understanding and dependence on fire. And I suppose, Adam, in terms of, we talked about human evolution and the pressures or the advantages that taming fire can have. I suppose in terms of using it as a technology, that step, you know know we all think of stone age to bronze age to iron age and so on in a sense it's a step of learning how to make higher temperature fires and furnaces i suppose yeah absolutely and but but more importantly it's about just control and i think that we are this is something that darwin spent a lot of time thinking about in The Descent of Man, the things that make us uniquely human.

And tool use was one, language was another, but he put fire as separate, a sort of subset of tool use and says that it's equivalent to our ability to speak, to communicate with each other in terms of its significance. There certainly aren't any other animals that have the level of sophistication of dependence and control of fire that we do. Although, as I said, we now know that Neanderthals also had controlled use of fire.

There aren't any animals that can start fires from scratch. And that was basically true and useful for us until about two years ago when it was discovered, or when it was written up in the scientific literature, that there are three species of raptor, Australian birds of prey, who, well, they're called fire hawks by the Aboriginals who've known about this behavior for thousands of years but what they do is they hang around near the edges of savannah fires in western australia and then they fly down and they grab a stick um in their talons or or in their beak and they fly over man-made or naturally occurring fire barriers like roads or rivers find a nice dry piece of bush, drop the flaming stick into it, set a new fire, they go and sit in a tree and they just wait.

And they wait because all of the little tiny mammals and lizards and animals run out of this burning inferno because they're going to get burnt to death and then they get eaten to death. So this is the first and only other example of an animal that deliberately starts fires, even though they can't start it from scratch. There is something about that image which you can't help, there is a kind of anthropomorphisation that happens. That is a

kind of Hanna-Barbera or a successful Wiley coyote in that situation. Absolutely, and in fact, so this is a really good example of what's known as indigenous expert knowledge. So we write this up in the scientific literature in 2017. It is of the aboriginal jaralan ceremonies dream time ceremonies maybe thousands of years old there is speculation it is speculation but i think it's it's interesting speculation that maybe the aboriginal australians learnt their ability to control fire from the birds because in in Western Australia, the savannah fires, the annual savannah fires, are part of the natural fire ecosystem, and Aborigines have been controlling that for thousands of years.

There has been a suggestion that they actually learnt this ability from the birds. I know in your book you talk about a particular beetle that's evolved to use fire. Yeah, yeah, the fire chaser, which you an indication of what what its behavior is like so this is a this is a beetle that has two under its front legs it's got these these two infrared detector patches so they're a bunch of of cells and they're pretty much the only creature that when when a fire is is kicking off will make a a beeline for it beeline is the wrong incentive a beetle line for it and we know this there's examples from the 20th century of like there was a in america there was a um uh an american football stadium was burning down and everyone's running away from it there's this line of these

beetles marching towards it and the reason they do this is because they they lay their eggs in freshly burnt logs and so this is a food source for them and this is how they've evolved it's absolutely essential for their survival the most amazing thing about it is they appear to be able to detect fire from 80 miles away so they go in this this line from you know tens of miles away they'd be able to detect fire from 80 miles away so they go in this this line from you know tens of miles away they'd be able to detect using these infrared sensors uh fires and they're the only creature that is uh that really burns towards them sorry that was that was not deliberate these semi sophisticated relationships with fire that none of them have the love-hate relationship the moth has though surely can you explain what is a moth has though, surely. Can you explain, what is

a moth's deal with the fire? Oh, don't look at me for that. They're just idiots. Is there something to do with it confuses the light for the moon? So it's a distance thing where they presume that that's actually the moon and in fact it's right there and that's why they go straight

into it. Yeah, you would think that they would have learnt in the genetic sense. What happens during the daytime? Don't they just get massively confused by the sun? They would, wouldn't they? They'd fly towards the sun, wouldn't they, if that were the explanation? Because that was a big thing in Australia, with bogan moths flocking around the Sydney Harbour Bridge.

And it was because of the lights on the bridge just totally confused them. They thought they were the moon. You know, starlight, lots of insects use starlight to guide them we know that dung beetles use the milky way to guide their trajectory home and we know that because very very clever scientists decided to test it by putting hats on them i love those kind of experiments neve thinking about how fire changes the way that human beings can can change their own civilization what about our understanding of not merely controlling fire but then what heat does thinking of things like the iron age the bronze age the ways that we kind of start to use fire to adapt different materials as

well well i think that that's that understanding of what the phenomenon of fire can do in terms of changing our particularly our built environment, or, as you said, in those kind of evolutionary spurts, almost. A lot of it is trial and error. A lot of it is people finding out by accident, almost, as to how fire can modify things or how fire can be used to smelt things or to create other materials. So a lot of that has evolved simply by people trying

it out i think and by trial and error but also um within the built environment into the modern era there are two branches um of uh i suppose areas of study around fire one is fire science which is understanding how things burn and understanding that once we burn things um how much energy those things release, because the amount of energy is different depending on what it is that we burn, and harnessing that and using different mechanisms to harness that. And that's what fire scientists do, mainly in laboratories, to understand those kind of mechanisms. And then there's a whole area of discipline called fire engineering.

And fire engineering understands what does fire do within buildings. So what are the stresses and strains that buildings can cope with and if they're if a fire happens within that building or again how do you harness the the energy that's produced by a fire such that you can create buildings that are safer to be in if if those buildings are are affected by fire because you said that all fires aren't equal, so there are things that burn hotter. And I suppose if you're looking at the development of a technology, so bronze, iron, cast iron, you need hotter and hotter fires. So could you talk a bit about the different temperature ranges

that you see in fires, the different sorts of fire? What are the different temperatures? So what we've got in front of me, I'm putting my finger through the flame because I like doing that. What is in front of me, if I put a thermocouple, something that measures temperature on this flame, this is called a laminar flame, a single flame, then the heat that I'm producing within that flame and different parts of it, but on average, is about a thousand degrees centigrade. So a candle flame? A candle flame, but between 800 and a thousand degrees centigrade so a candle flame a candle flames but between 800 and 1000 degrees centigrade everybody has held their hand over a candle and as you move your hand down it gets hotter and that's the hot gases that come off as a result of the combustion material the

combustion happening um if you're looking at particular objects and you're trying to melt those objects you're trying to burn them, cellulosic material like woods, papers, some fabrics like cotton, will start to thermally decompose around 260 degrees C. So within a condition if I held a piece of wood like a match over this flame here for a reasonable amount of time, not very long, then I'll start to see the wood evolve gases and it will burn. Plastics, it takes much more heat to get them burning, so maybe about 400 degrees C, and that's simply because of the makeup of the material. But then different materials, once they burn, will produce more heat energy into a defined space. So if we burn polyurethane foam, what you're sitting on,

the material that's in the chairs, polyurethane has a high heat release rate. So once it gets burning, it produces itself a lot of heat that will then affect materials nearby and therefore increase the amount of heat, if you like, that those materials, the surface of those materials are being affected by. So it's a really complicated process and in in the kind of job i do as a fire investigator what you have to do is understand in the real world what that means so what are the circumstances that might be plausible to cause a particular thing to ignite and then for that fire to spread and that requires a knowledge of the materials and how much heat release they how much heat they will release and what configuration they're in. So as you burn things like candles or other materials, our candle is burning in the middle of the table,

well, on the table in the middle. If I put it in a corner, then I'm reducing the oxygen flow and the flame extends, it gets bigger. If I put it beside a wall, same thing, it reduces the oxygen that can flow into that combustion and keep it going, so the flames extend and get bigger. So the whole package together is quite complicated in understanding just how it works.

What's the most common cause of fires, residential fires, other than... If it's not arson, what's the most common cause? The most common cause that's recorded is electrical. So electrical appliances of one type or another, whether they're overheating sort of washing machines, a good one. Not a good one, I mean a bad one. But it's one that's very common.

Or other types of appliances like television sets and things like that. So electrical cause is the most commonly recorded single cause of fire. Other things are variable by time of year. So this time of year, candles are a potential significant cause because people like to use them for atmospheric purposes. I have seen where people have... There was a product out many years ago who was a little candle holder for these little tea lights,

and you hung it on your Christmas tree. So you light it, in it goes, your Christmas tree's in a corner, wonderful configuration for a fire. I think it was marketed as the accident waiting to happen. I think it was, you know, when you sit there and it burns away, and Christmas trees burn really well, because they've got a very high surface area,

and they're full of materials that will burn really well and they go up like nobody's business. I had a friend who worked in the fire service and they had one that they actually started calling a student fire, which was little tea lights sitting on top of an old TV, a cathode ray tube TV, and it just melts the plastic underneath it and just drops into the TV and then the whole thing goes up.

It was super common. I used to be involved in a training course where that was my party trick. I used to set televisions on fire with tea lights. Yeah. It was for training. It was for training. Do you know the greatest fire battle

I've ever been involved with, and there's a long list, obviously, but this is getting ready for a name drop. I once put out a fire with Eddie Izzard, some candles set far to a curtain, and everyone else ran out of the room, but Eddie Izzard and I beat out the fire. He used a pineapple, and I used a watermelon.

And it had a proper slapstick kind of... He was there, you know, the stalk of the pineapple, the watermelon, and it was... If Eddie Izzard had done this as a routine, you'd, like, always lost it. This is getting too silly. He never remembers anymore, you'd like, oh, he's lost it now. This is getting too silly. He never remembers anymore, but I think, don't you remember that day?

You had a pineapple, I had a watermelon. Yeah, anyway. I think you might have dreamt that. Do you know what? We did a whole show about dreams once before and I've heard they're as good as reality. I believe it happened and thus it did. Does fire occur anywhere else in the universe and i have a reason for asking that because it strikes me that you need a oxygen in an atmosphere

and the oxygen in our atmosphere came from photosynthesis so so my thesis i'm going to advance because i thought about it about half an hour ago, is that given that, though, it is interesting. Is there any other way of having fire emerge or exist without an oxygen atmosphere on a planet? Flaming combustion requires oxygen. That's for certain. You can have smouldering combustion, which is combustion almost at the surface of a material, but

not everything will smoulder. The material has to be porous and it has to have other characteristics. And that can be in a very low oxygen environment. Is that why Sheena Easton smouldered so much? Was she constantly in a low oxygen environment? You're getting back to the vacuum now, aren't you?

So you can have fires in zero gravity. Fires in zero gravity don't look like the kind of flames we're used to. The flame is completely spherical. But I'm not sure that you could have fire in absolutely zero oxygen. Or what's the minimum oxygen level? Say it's in a, in a room so in a in a room a fire's transition between through um a series of very uh well-known states so you start with a small fire that then the heat that's

derived from it then starts to heat up materials around and they start to gas off as we call it or produce thermal decomposition products and they go on fire and that then generates more smoke and more heat and in a room like the one the studio we're sitting in that smoke would rise because hot gases rise would hit the physical barrier of the roof and it would spread out across the roof and then it radiates heat back down into the room and everything starts to to evolve gases and it comes to a point so all of that happens that it becomes fuel it's-controlled fire, so it depends on what's in the room. And it comes to a point where everything becomes so heated up that it's evolving all of these thermal decomposition products. You've got a fire burning away, so you have an ignition source,

and the whole room evolves into fire. So a fire in a room becomes a room completely on fire. And then it becomes ventilation-controlled, because it uses up a huge amount of oxygen and fires like that developed fires like that will maintain at about five percent oxygen at about but it depends on the size of the room and other things but that's when you see things like materials like doors failing or windows blowing out and that's associated with this event where a fire in a room becomes a room on fire which is called flashover so unless that fire is is gets a an input of oxygen it will die down but it'll just be a superheated room until

somebody or something um lets air into it and then you get a phenomenon called backdraft, which isn't the way it happened in the movie. That never happens with aliens. No, I'm sorry. So it's a very complex relationship in terms of the amount of oxygen that's required, and it depends on what goes on fire, so what's present in the fire. Because what I think is interesting is that we don't have an oxygen atmosphere until about more than about 5%,

until about, what, a billion years ago or so? Something like that. We should give some context to the reason you're asking this question because, basically, I had written in my book that fire predates life and when I arrived here tonight, Brian's first sentence to me was, your book is wrong. Well, it was more a question...

Social decorum normally is, hello. One lovely idea, social decorum normally is, hello. Well, no, because... Oh, what a lovely idea, social decorum and a physicist. The reason, though, it is interesting, isn't it? Because I'd remembered a graph that I'd seen, I'd used somewhere, which shows the oxygen concentration of the Earth's atmosphere. And it's really very low until about a billion years ago. And, in fact, there's no oxygen, essentially,

in the atmosphere before photosynthesis, right? You're down well below a percent, way below. So it's an interesting idea that you cannot have fire without life, which is the question. Yes, and I sort of have to concede now on national radio that your opening salvo to me, your book is wrong, is in fact correct.

Well, I wasn't sure. In your department, so stars we think of as burning, but are they not? Are they just hot gas? Well, it's nuclear fusion, which goes back to our definition. So, yes, you don't need oxygen, it's hydrogen fusion, it's helium, it's a nuclear reaction which releases energy. Whereas fire, I think we've decided the definition, it's a nuclear reaction which releases energy whereas fire i think we've decided the definition is a chemical reaction which is basically oxidation

so it requires oxygen and that's why i said you know anywhere in the universe it's kind of of course i expect there'll be life out there in the universe but there may be very few planets where photosynthesis operates and therefore there may be very few places where fire exists in the by our definition. I think that is probably right, I'm sorry to say. But the implications for this conversation are really, really profound because if you're right, Brian, and I think that you are, what that means is that life created fire,

not the other way around or not in any other formulation. You only have fire because life existed. So not the mythological idea that the gods you know you steal fire from the gods or yeah it's kind of the other way around plants created the gods we we gave or life itself gave fire to the rest of the universe this is some really deep philosophical stuff anyway the main thing is adam's book you don't need to buy now it's a very very shoddy book but he's got a got a new one out in February and that's meant to be better. Brian's going to proofread that. This is the

point of a great book, that it raises interesting questions that we have. By being wrong. A lot of the great science books are deliberately wrong. I had never thought of that before I read Adam's incorrect sentence. Thank you, I think.

Because we're very near the end and i wanted to make sure we got into the hard science spontaneous combustion because you're an expert right because when i was brought in the 1970s anyone listening 70s 80s you brought up and you read things like the unexplained magazine and there was this terrifying picture of kind of a hole in the floor and and and the remnants of a leg and that that was it. And this was another case of spontaneous combustion. So now we have a proper expert on fire. Can you explain that? Is it unexplained or is it explainable?

Firstly, I'm just going to say that I'm not an expert on fire, but thank you for the sentiment. Well, you are in this panel. You're doing very well. Thank you. Spontaneous human combustion does not happen. So what is it? In those cases, what's happened?

So what we have shown to happen by experiment, not with people, not doing well now, not with people, is it's a thing called a wick effect. So it's like the scenario, and it's a bit gory, but the scenario would be somebody who might be incapacitated. It's usually someone who might have had a heart attack or something like that, or somebody who's incapacitated, but sitting in the environment of a fire.

So sitting beside maybe an electrical fire or something like that and as they are beside the fire and stay and remain in contact or close contact with the fire and what the fire begins to do is render down the areas of fat in the body so the middle of the torso and those in particular and those all the audience are now grimacing at me so those areas and they render it down a little bit like a candle is rendered down and they soak into the clothing of the person and then it's uh it's the clothing of the of the person that acts like a wick in the same way as a candle wick does and so the fat in the middle part of that person starts to slowly burn and render away so fires as you're describing so what's left are the extremities the legs the arms the head often but the whole torso can be burnt

away adam's laughing the whole torso can be burnt away so it looks like it looks like it's the source of the fire it looks like it's the source of the fire but in actual fact it's not um and the the the type of evidence that's left behind in a room where such an event can occur, or it has occurred, is very low-level burning. So it's all centred around the body, and it doesn't spread to other parts of the property or the room or whatever. I've waited 40 years for that to happen. Well, there you are. So there was a set of experiments done using pigs as a model to show that this kind of... This was the phenomenon that was occurring.

And it happens over long periods of time, so it might be many hours before... I bet that was tasty when it was done, though. I bet there were some hungry scientists at the end of that experiment. In the radio times, this was going to be listed as a show called What Is Fire? And that was a show called Why Adam Rutherford's Book Is Wrong.

Totally different. Educationally complete. It's Reithian. It's Reithian. It is Reithian. Before we get abolished by Boris. Ed, you got away with it, by the way. Your first question, which we never got to, was,

Ed, you studied horticulture at the University of Strathclyde, so our question for you is, slash and burn method of land cultivation. How do you feel? So anyway, you've got to wait. And is it the best method for creating a swidden? Do you know what a swidden is? I don't know what a swidden is. You look it up on Wikipedia.

I think it's that burn terrier of grassland that you use when you cultivate a field by burning it and then the thing that's left, I think. Yeah, that's commercial horticulture i was going to be a gardener oh oh fair enough anyway so we asked the audience a question and uh good job we didn't ask him then yeah thank you that never came out the uh so anyway we asked the audience as far as one of the many things that public information films used to warn us about

but we'd like to know what would you like to see a public information film warning us about so uh first of all cardigans which is very specific to me i presume they're nick thank you and also overpriced canadian face cream uh many of you won't know about this but this is the one time with brian where basically science goes out of the window his selection of face creams none of which have any evidence base whatsoever but when i picked him up with that he went i know but you can't take any risks with this can you and rubbed his shiny cheeks. And the answer is that he should use them as well

because he's actually younger than me. Nah, anyway, go on, what's your one? The face like a bucket. It says, D-Ream 25th anniversary heavyweight vinyl re-release if things can only get better. There's someone here from Catherine, texting while in charge of a sleigh. That sounds interesting.

That would be our Santa and the chimney collision. I'd like to see the bicycle proficiency test resurrected and publicised again. I like these. These have been taken very seriously by people, by the way. Infectious diseases, viruses and genome editing. Yep. We've moved a lot. It used to all just be rabies and water,

but now it's genome editing, the new world of public information films. Thank you very much to all of our guests, Ed, Niamh and Adam. Next week, we're going to be dealing with quantum worlds. Well, in some of the worlds, we're going to be dealing with quantum worlds, but in other worlds,

we're not going to be dealing with quantum worlds, are we, Brian? Well, it's a matter of definition, as we'll find out next week. Will we find that out next week? Will we find it out in, I mean, which next week? Because other people are going to get a different week, aren't they? It's a matter of definition, as we'll find out next week. Will we find that out next week? Will we find it out in, I mean, which next week? Because other people are going to get a different week, aren't they? It's a matter of definition.

We'll find out next week. Are you sure? We might find out. But what about the other weeks that don't find out in another quantum world? Oh, I think I've collapsed the wrong wave function. Anyway, bye-bye. Thank you. In the infinite monkey cage In the infinite monkey cage Turned out nice again.

Hello, I'm Clemmie Burton-Hill from Classical Fix, the podcast where we try out classical playlists on classical newbies. I just wanted to tell you about a very special episode we've just made with the brilliant writer and comedian Rob Delaney. That one or so minute of music that we just heard was the strangest cacophony. I think it might be a healthy part of mental and emotional hygiene to listen to sad music in a world that says, don't be sad. If Beethoven had a dial where it could be from zero to ten,

this would be some five Beethoven. So it's totally amazing. If I didn't know it was Beethoven, I'd be like, oh, yes, lovely. But with this, I'm like, come on, Beethoven, show me what you got. Rob Delaney on Classical Fix. Download it now on BBC Sounds. I can't wait to get my fix again. This is wonderful. Thank you. you. In our new podcast, Nature Answers, rural stories from a changing planet, we are traveling with you to Uganda and Ghana to meet the people on the front lines of climate change. We will share stories of how they are thriving using lessons learned from nature. And good news, it is working. Learn more by listening to Nature Answers wherever you get your podcasts. you