Boom! Naked Scientists LIVE!

Genetics, geoscience, chemistry and komodo dragons - check out our latest show!
31 March 2020
Presented by Chris Smith, Adam Murphy
Production by Katie Haylor.


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This week - from genetics to geoscience, chemistry to komodo dragons, an explosive hour of science fun! Hear what went on at our live event recorded back on 11th March for the 2020 Cambridge Science Festival - one of the last events that went ahead before the rest of the festival was cancelled. Demos, anecdotes, questions, and booms with Giles Yeo, Ljiljana Fruk, Eleanor Drinkwater and David Rothery...


In this episode

a snail

Snails, planets and chocolate!
Giles Yeo, Cambridge University, Ljiljana Fruk, Cambridge University, David Rothery, Open University, Eleanor Drinkwater

Adam Murphy and Chris Smith introduce the panel...

Chris - Welcome to the stage Giles Yeo! Giles is a geneticist; he's also an author. You occasionally see him pop up on the BBC. And actually we were doing an event together a few years back and Giles said to me, "I've gone vegan Chris for an experiment for the BBC." And I said, "how's it working out?" He said, "very windy."

Giles - Pardon me! People that haven't had dinner yet. Or maybe you have had dinner. Hello.

Adam - Well speaking of dinner, we also have Cambridge University chemist, advisor to the chefs, chocolate designer, an expert on all things that are very, very small scale; please welcome to the stage Ljiljana Fruk.

Ljiljana - Thank you. Hello, hello!

Chris - We always end up talking about restaurants as well because you're not just a chemist or a chemical engineer, you're a bit good at food.

Ljiljana - I know. I like eating, so I thought maybe I'll turn my science into something good: experiments that can be eaten later on. And so I ended up mixing up the chocolate! And you can imagine... I perfected the recipes for two years, you can imagine how enjoyable that was.

Chris - Also with us: volcano expert and professor of planetary geoscience at the Open University, David Rothery! It's traditional to ask people who know about planets: what is your favourite planet? Is it Uranus?

David - No, it's not. It's Mercury because we have our own spacecraft on its way to Mercury as we speak. And you've helped pay for it, so thank you very much. It's called BepiColombo, it's a European Space Agency mission joint with the Japanese Space Agency.

Chris - And what's it going to do?

David - It's going to go to Mercury, split into two spacecraft - the European one and the Japanese one - orbit the planet, but it won't get there until round about Christmas 2025.

Chris - Wow, that's a long... it's not that far to Mercury though, is it? Why so long?

David - We set off away from the earth...

Chris - Well, that was a mistake, wasn't it?

David - Well no, because it's rocket science. We're swinging back past the earth next month. That swings us in towards the sun. We have two flybys of Venus; that swings us in past Mercury, but we're going too fast to get into orbit, so we fly past... go round the sun, flying past Mercury six or seven times, slowing down each time thanks to Mercury's gravity grabbing hold of our spacecraft a little bit. And the last time we approach Mercury, we're sneaking up on it slowly enough to get into orbit.

Chris - Why didn't you just fly a bit slower in the first place?

David - You can't, because you're falling towards the sun all the way. So our ion drive, which is what propels us, is actually acting as brakes to slow us down all the time. And we can't carry enough fuel to screech to a halt if we want to carry instruments on board the spacecraft, which we do because we want to find out what the planet's like when we get there. So you have to play these patient games in space.

Adam - Wow. And last but not least, we have beetle enthusiast and expert on woodlice personalities: please welcome to the stage, a tank. I mean Eleanor Drinkwater!

Chris - Now Giles, we mentioned and alluded to the fact you do programs on the BBC as well. There must've been some times doing that when some funny things happened.

Giles - Probably more for people watching me than for me, the one lesson: always read the waiver form. Just the fact there's a waiver is an issue. So I did an experiment for Trust Me I'm a Doctor for what happens to your glucose levels, your blood sugar levels, when you get stressed. So for a week I was wandering around with one of these glucose patches, you can actually do continuous blood glucose monitoring, and we were just figuring out what happened to my glucose after I ate. And so we then showed up on the experiment day, we had all this data, five days of what happened after I ate to my blood glucose levels. I ate; I looked at the waiver, which I didn't look at before; I signed it; it said pain in there somewhere, this is always a bad thing. And then I showed up in a room and there was a water bath at two degrees Celsius.

So I walked in and there was a po-face, white-coated gentleman in front of me, and he said, "stick your hand in in the water." Remember there's cameras on me, okay. So I stuck my hand in the water, and because the camera was on me and there's children here, I nearly swore, but I didn't. It felt like my hand got chopped off. And so 90 seconds later I then pulled my hand out and the guy goes, "subtract 37 from 1,889 sequentially!" So I'm sitting there with my hand falling off, trying to make the decision, and he yells at me for being slow, for shaking my leg...  "Hand back in! Hand out! Hand in! Hand out!" Very stressful. But what was really interesting was what happened to my glucose levels. So normally when you eat your blood glucose levels go up, and then they come back down again as long as you don't have diabetes, and I don't have diabetes. But what was interesting was as they went up after I ate and were coming back down, the moment I stuck my hand into that ice cold water, okay - the moment I got stressed - my blood glucose levels came to a screeching halt. It took nearly two hours to go down to what it was at fasting. Why? Because when you're stressed, suddenly you're thinking, "tiger, tiger, tiger," right. And so your body then keeps the glucose levels in your blood so that you have fuel to run from the tiger, to hit someone, whatever you're supposed to do, biology at work. I knew it because I study it, but it was very interesting to see.

Chris - Eleanor?

Eleanor - I can't understand how someone managed to talk you into this. You're probably one of the smartest people I've ever met.

Giles - I didn't read the waiver. Oh! But the other thing was, they couldn't tell me what the stress was, to make sure I was super stressed. I think that's probably the... I didn't actually know what I was walking into.

Adam - Now Ljiljana, as we mentioned, you are a chocolate designer. How does an engineer at the tiny scales start working in chocolate?

Ljiljana - Yeah. As I said at the beginning, I really wanted to do some chemistry where you have a result that is really desirable to other people! Because chemistry has sometimes such a bad reputation, that we are doing bad things. And I thought let me a souvenir that people can take with them, eat it, and then learn about the molecules. So we designed molecular chocolates. And it seems to be working. People are coming to me and asking me about dopamine, and glucose, and ethanol; all of these molecules that we embedded within our chocolate...

Chris - Yeah, the last one of those I can definitely identify.

Ljiljana - Yes!

Chris - Because of course that is, for people who are not in the know, that is alcohol.

Ljiljana - I know!

Adam - David?

David - So chocolate is a long chain carbon molecule basically, yeah? There's something that forms in the atmosphere of Pluto and settles to the ground and stains Pluto brown, which we think is a kind of hydrocarbon. Do you think it's possibly worth going to have a lick?

Ljiljana - I think we should name it together!

Chris - It is in the Milky Way...

All - Uuugh!

David - Other chocolate bars are available.

Chris - As someone who has been working... because you work with the BBC quite a bit as well...

David - Yeah.

Chris - Have you got any interesting things to relate?

David - You want me to tell you about fun and games with Brian Cox on the Planets series? There was an Open University coproduction called The Planets, which aired about 10 months ago, and two of us at the Open University, planetary scientists, were consultants. And we would get drafts of the scripts and tell them what was wrong with it, and how to put it right. This is a production company, and then it would go to Brian Cox, and he'd go off in a glider over the Alps or on some glacier in Iceland, somewhere atmospheric to do his pieces to camera. And he often went off-script on those, so we couldn't really control what he said. But he knows his stuff by and large... He's a particle physicist rather than a planetary scientist. But he did a lovely piece with an iPad on a glacier in Iceland saying, "look at this picture of Uranus - your favourite planet, Chris - with these rings..."

Chris - No comment.

David - "...and two little moons, one outside the ring, one inside." These were shepherd moons. And the thing about very narrow rings, which Uranus has, is that the moon orbiting inside and outside help keep that ring really narrow and keep it in shape, they're called shepherd moons. And Brian was explaining very eloquently how the outer moon going a little bit faster tugs the rings upwards, and the inner moon going a bit slower tugs the rings downwards, and between them that keeps the ring in shape. And it was very persuasive, very well done. He talks to camera beautifully. And when I saw the rush for this, the recording that comes for approval, I thought, "that's great, he's done well. It's not what we planned, but it came over really well." And it was broadcast. And the people on Twitter were saying, "that was wrong!" Because the inner ones go faster than the outer ones. Anything orbiting something, the closer you are, the faster you go. So you've got the principle right, of the tugs in opposite directions keeping the rings tight, he just got the relative speeds wrong.

Chris - And you didn't read the small print then?

David - I was seduced by Brian's brilliant delivery, but people watching television spotted it, they tweeted, and I said, "oh yes, we got it wrong!" And then Brian tweeted saying, "yes, sorry, I've got it wrong." And it's even more stupid because I did a Masters project on these very shepherd moons doing this. But when you're telling a story, it's very easy to just tell it the wrong way round. You concentrate on explaining the opposing forces doing a good job, and you can get something fundamentally wrong and not realise it.

Chris - That's why your space probe's going to take 15 million years to get to Mercury!

Giles - I did exactly the same thing once, where literally it was a graph. Now this isn't even complex. It wasn't moving, it was just a graph with a blue line going up, a red line going down. And I said, look at the red line going up. It went all the way, except for one thing: they ended up catching it the night before it went out. I had to rush down to a studio - actually came to the Naked Scientists studio actually - in order to record one line. And that's just: "just say down! Just say down!" I went, "down." And they spliced that down in, and I said it correctly.

Chris - Now Eleanor, you come on the Naked Scientists quite often because you are our insect guest, you're our creepy crawly expert.

Eleanor - Right, thank you.

Chris - And you agreed kindly - because you've come back, and we're delighted you're back in Cambridge - and you have brought us a surprise.

Eleanor - Yes, I have. So whenever I talk about science, one of the things I'm really keen about is trying to get people to realise how brilliant invertebrates are. And so I thought the best way to do this was to bring along a guest. This is Shellock Holmes.

Chris - Did you say 'Shellock' Holmes?

Eleanor - Yep, Shellock Holmes. It's too funny. So Shellock Holmes is a East African land snail. Whoops! Thank you.

Chris - 'Was' an East African land snail...

Eleanor - No that wasn't him, it's fine. Here we go, I'll just see if you can see him a bit better if I move away some of his salad.

Adam - He's got quite a banquet there.

Giles - I know...

Eleanor - Yeah, exactly.

Chris - No wonder it's so big!

Eleanor - Exactly, yeah! So when he's fully spread out he gets to about 18 centimetres long. And the really, really crazy thing about this species is they reach that size in about a year. So that means they have this incredible need to try and find as much calcium as they can. So in the wild you'll find them scavenging for bones of dead animals in order to try and get as much calcium as they possibly can. Or sometimes concrete, they'll go for a little bit of concrete as well.

Ljiljana - So they are taking this calcium from the bones, which means they probably have some kind of chemicals in their slime that can dissolve this bone structure?

Eleanor - I don't know exactly how they do it.

Giles - Because they don't have teeth...

Eleanor - But they have these lovely mouthparts though. When you watch them eat, they've kind of got this... it's almost like a kind of, you'll see it like a little pumice stone, kind of scratching off the layers. And one of the other lovely things about this is: so in the wild, they tend to be a lovely dark gray-brown colour; well this one's albino. And so as a result you can actually see, when he eats, you get little globules of food that you can see coming through its skin, because the skin is actually transparent. Which is another reason why... yeah! They are just amazing.

Chris - Good job that doesn't happen to humans. So tell me Eleanor, I'm intrigued, does a fat big snail like that travel at the same speed as a small one? Or is there a speed advantage with a big snail?

Eleanor - Ooh. That is a very good question. I would have to say that I don't know, but I do know that snails aren't known for their speeding ability.

Chris - Yeah. Well you see I've got a vested interest, because I was taking part in a snail race the other day. And we were all racing snails.

David - Did you win?

Chris - And mine was going really slowly. And so I said, "should I take the shell off?" Because I thought that would lighten the weight. And the person who was with me said, "no, that'll make it more sluggish."

All - Uuugh!

Eleanor - I see what you did there.

Chris - Give them all a round of applause, everybody! Our wonderful panel for this evening.

A tray with a burger, chips, and soft drink.

Giles Yeo: extreme genes
Giles Yeo, Cambridge University

Cambridge University geneticist, obesity expert, author and BBC presenter Giles Yeo tells Chris Smith a bit about his science...

Giles - I am a geneticist and a perfectly upstanding thing to do. You know, my mother in law still speaks to me. So this is a good thing. But people often use genetics to study a trait or a disease. And I happen to study body weight. And actually the moment I say body weight, obesity actually, which is one end of the spectrum, I suddenly become the bad person and I become the bad person because I'm perceived as giving fat people, overweight people, people with obesity an excuse - which is always an interesting take because if I was studying the genetics of cancer, would I be giving the cancer patient an excuse? I wouldn't. And the reason why I'm "bad", is because people say, "Well you eat too much. That's why you're the size you are. You eat too much. Right?" They say that to me.

Chris - They say that to you?

Giles - Thank you. I've lost weight. I want to point out when I was vegan!  Anyway, so "they eat too much" and that is true. Your body weight is going to be down to how much you eat and how much you burn. Right? But the question to ask is why? And at the end of the day it's because different people behave very, very differently around food and there is a lot of genes that are actually involved.  The physics is the first law of thermodynamics. You can't magic the calories in and magic the calories away, but it's working up to the physics. Why we actually get to the physics we get, why we eat too much. That's where the biology is. And I think by studying extreme cases of obesity, so these are not going to be normal cases of obesity. These are three, four year old children who are 40, 50 kilograms. Okay, so that's a lot. That's a lot of weight. I'm 75 kilograms. For example, one of the pathways we know that are disrupted in severe obesity is the fat sensing pathway, where because there's a lack of a signal from the fat to the brain, the brain doesn't know that you have enough fat on you and so you continue...

Chris - And that is genetic? That is a genetic reason why your fat doesn't talk properly to your brain and that makes you eat too much?

Giles - Exactly. There's a hormone there called leptin, and when there is actually a mutation in the hormone leptin then and you don't have any leptin, then your brain doesn't know how much fat you have. 

Chris - The thing is Giles, why I'm slightly skeptical, and you can probably disabuse me of my skepticism, is that 50 years ago the number of people who were overweight and obese was vanishingly small and now it's very, very large. Now we're not evolving that fast, are we?

Giles -We're not evolving that fast.

Chris - Why is there a difference?

Giles - Well, so here's the thing. Whenever people study and talk about genes, they think that geneticists only look at the genes in of themselves and we do look at the genes, but we have to look at the genes in context with the environment. It turns out that every single human trait as including our body weight has a genetic influence. Every single trait and behaviour. The trick is to ask what role the environment plays. Now your genes, as you say, they're empirical. You're born with them, you die with them. They don't change anywhere in between, but the environment does and as the environment changes, the way your genes express themselves and change actually then that changes as well. And so what has happened is as we get to the stage where we're at, we have too much food today. I think that's not, that's not anything to debate. Suddenly, it has unmasked susceptibilities of certain people you know who are going to eat more in the environment. Whereas in the past there was just not enough food around for people to eat too much. Whereas now there is ample opportunity for people there to take advantage of the environment or not advantage depending when you look at and actually get too large.

this is a lit match

Exploding custard
Dave Ansell, Sciansell; Giles Yeo, Cambridge University

Science demo superstar Dave Ansell shows Adam Murphy what happens when you set fire to cornflour...

Adam - Now, as we said, we promised you demos and it wouldn't be a proper Naked Scientists show without them. So I'd like to introduce science demo superstar and former naked scientist, who's going to put the boom in this show. Please give a round of applause for Dave Ansell. So Dave, we're talking about food and we're talking about calories. So what kind of food calorie -related demos have you got for us?

Dave - I thought we'd look at releasing those calories in a slightly different way.

Adam - Right, so not eating.

Dave - No, not quite the way you do in your body, but as a physicist in a very similar way. So your body basically, as far as I'm concerned, you're taking in energy, you react that with some oxygen and it does something useful with it.

Adam - So what does that look like?

Dave - So here I have a pot with vegetable oil in it and a string coming out the top, just like a candlewick. If I light it, we have a really exciting demo!

Adam - It's a small candle flame.

Dave - Indeed. So this is going to sit there maybe for a couple of hours and burn gently. It's the way a lot of light was produced in the ancient world.

Adam - But is there anything else we can do with food?

Dave - Well this is releasing quite a lot of energy over a very long period, so it's not that exciting. What I thought we'd try and do is increase the speed at which we release that energy. So in order to burn something quickly, you need to be able to get the oxygen to more of it at once. Yeah. So what you do that is by using very, very small particles, like a powder, like custard powder. So the particles in custard powder, they're basically starch so cornflour and they're about one micron across, about 1000th of a millimeter across. So if you imagine the surface area of all of these tiny tiny particles, it's absolutely immense. And so basically if you can get the oxygen to custom powder, it can burn almost everywhere at once.

Adam - And - he asks dramatically - what might that look like?

Dave - First you need a device for doing this. It looks a little bit like a pipe. I'll put a little bit of custard powder in this. There's a long tube attached to that and we need a source of ignition, so I'll light this blow torch.

Adam - I'm a coward so I'm stealing your goggles.

Dave - And then if I blow through this tube, the air will swirl in here. Mix the air in really nicely with the cornflower -

Adam - You're kneeling down in front of it, about to blow through the pipe -

Dave - [whoosh] We get a very cool little fireball! I mean at this scale, that's kind of pretty. If you're running a flour mill, it's a whole other kettle of fish. If, say you have a big bag of flour, it drops down from the top of your flour mill. It bursts, it fills the whole flour mill with flour, which is the same stuff as corn flour basically, all carbohydrates. There's a flame in the corner, bang! Hundreds and hundreds of windmills and other forms of mills blew up through that very reason. They were incredibly paranoid about not having flames in mills, for good reason.

Adam - And that's certainly not what I want to happen while I'm having cake anyway. Now Giles, maybe I'm in the minority here, but I feel like when I put a donut into myself, it doesn't burn up in a big fireball. So what's different about what my body's doing to turn food into energy?

Giles - It's actually, it's very interesting because when you eat food, we think about it in calories, right? We think, oh, this is a hundred calories. This is 200 calories. And what's interesting is a calorie is the amount of energy it takes to raise one liter of water, one degree Celsius. At sea level, that's a calorie. Okay? But if you think about it then how many calories do you need to boil one liter of water? The answer is a hundred calories. A chocolate bar only has 230 calories and we're not boiling. The way that our body actually does it is we then take that food and transform it into into energy, but in stepwise forms. So if we take in fat and sugar and protein, we actually absorb it. It then goes through what we call intermediary metabolism, which means that the individual glucose particles, amino acids and fatty acid particles then produce ATP, ok, which is our little units of energy. And each of these then gives a little puff of energy every time they break apart, to then be able to move certain things and we actually recycle in our body our entire body weight in ATP - these little things - every single day - in order to function.

Chris - Quick question for you. Where's Sue, Sue Taylor?

Sue - Question about Benecol, does it actually work? Benecol and things like Proactive margarine, do they actually work?

Giles - Other spreads are available, but these come with a manufacturer's sign that says "helps lower cholesterol", help being the critical word and "lower cholesterol". Now I'm not entirely sure of what the active ingredient is supposed to be in these things, but as far as I understand there is a modest effect in some people, okay. And this is the critical thing. Because not everybody's cholesterol levels are going to be sensitive to diet. To my view rather than eating a lot of spread, which is fine if you dig spread I guess, I think if you actually reduce your saturated fats and ate more unsaturated fats such as from olive oil and maybe from ground nuts, that's probably going to be more effective on lowering your cholesterol levels. If your cholesterol levels are sensitive to diet.

Chris - Hands up in the room if you prefer butter to margarine......It's about half and half. Sue, you had another question.

Sue - Is butter better?

Giles - Once again, it does depend who you are. There are going to be some people who can literally take a stick of butter and eat it and their cholesterol levels will not budge. Okay. And those are, you can call them lucky people, they may get fat. That's a very different scenario, a different problem. But from the heart perspective, but they're going to be some people, and I know I'm one of them. My cholesterol levels teeter on a little bit high. I know they're sensitive because when I went on a vegan diet, cut out my saturated fats, my cholesterol levels plummeted. So if I ate a stick of butter, I probably keel over from a coronary. So once again, I think it is very, very important when you begin to ask questions about food, that it doesn't work the same in every single person. So it depends is the answer.

Close-up of a dark chocolate bar.

25:44 - Ljiljana Fruk: exciting enzymes

How does a chemist become a chocolate designer?

Ljiljana Fruk: exciting enzymes
Ljiljana Fruk, Cambridge University

Chemist, advisor to the chefs, chocolate designer and expert on things at very small scales, Ljiljana Fruk told Chris Smith what she gets up to in her research...

Ljiljana - Yeah. So I work... in my research we explore two things: we work on extreme small scales, so we use nanotechnology, very small dimensions; and we work with materials which we can pack in such a way that they resemble the sizes of our biomolecules in our organism. And enzymes are really extremely good chemists. So they're responsible for speeding up reactions in nature. And they are also very specific. That means that they can choose one reaction, sometimes out of many reactions, and just specialise on this one. But then they specialise perfectly. And you can imagine that these enzymes are then particularly useful for chemical industry. If we could design enzymes that could help us to do these reactions that we need, to produce clothing or produce some food, we would be really happy because we will reduce the waste, they are usually biodegradable. So we try to take the inspiration from natural enzymes, those which are present in our organism or in some plants and animals, and we try to simplify them so that we can design materials which are relatively cheap, but they can still do the reactions that we would need. So for example, we designed the simplified enzyme that can make indigo dye. And indigo dye is, for example, a blue dye that you use in your clothing. So everybody who has a little bit of jeans today definitely has the indigo dye. And this is produced in chemical industry with numerous processes that produce lots of waste. If you use enzymes, you simplify these reactions. So you know, instead of having 20 reaction sequences to get this indigo, you now have three. And you work with reagents which are really sustainable. So this is what we do. And our materials look like this.

Chris - You've got a demo to show us enzymes in action.

Ljiljana - I have a demo, exactly. And you know, before, we were using oxygen to burn things; now I am going to use the enzyme to produce the oxygen. And this will do hopefully, it will do well. I have my lovely assistant here. I'll take the glasses - safety first. I have also a lab coat, which all chemists should have. And I have gloves. And what I have here, and you see - a little bit of special treatment, I have a very big flask and there are some small flasks here - I have hydrogen peroxide in this flask. And hydrogen peroxide is similar to water; so water has one oxygen and two hydrogens; hydrogen peroxide has one additional oxygen, which makes it a little bit more reactive, but it makes it also very good for different household activities. So you probably, if you look in your kitchen or in your bathroom, you might find some products, cleaning products, that have hydrogen peroxide. So what I have then here, it's a mix of yeast, normal baking yeast that you can buy in the shop, which has an enzyme called catalase. It's a very powerful enzyme, it works really within the second, and it can degrade this hydrogen peroxide into water and oxygen. So let's see if we can make this reaction go.

Adam - So we're going to pour the yeast into this philosophy of peroxide.

Ljiljana - Yes. Wooo! So what we actually get here... and if you would touch this flask now, you would realise that it's really hot and you can see it foaming.

Adam - So foam just shot out of the top. Yes.

Ljiljana - So we put a little bit of detergent in it, a little bit of soap, so that we created the foam.

Chris - Ljiljana, is that science-speak for 'we cheated'?

Ljiljana - Yes, because I wanted to make it visualised! How else would you see the oxygen? Oxygen you can't see. So we made oxygen visible. So you have lots of oxygen produced, and this reaction also releases lots of energy, so basically everything heats up.

Adam - I notice there are four more flasks.

Ljiljana - I know, yes! I need four volunteers from the audience. Yes! Oh my God, who's going to be faster? How are we going to choose? Yeah, you have to put some glasses on...

Adam - Safety first, we need lab equipment...

Ljiljana - Lab coats on!

Adam - Science is the most glamorous activity in the world. Purple gloves, matching white coats. This year from Ralph Lauren.

Ljiljana - Yes. And then you have your purple gloves. Okay, take the position. Choose your flask.

Adam - Choose wisely.

Ljiljana - And choose wisely. So you do have your flasks, which we prepared already because we put a little bit of hydrogen peroxide in the flask and we put a little bit of soap. I will move out of the way. Here you have your mix of the enzyme, yeast; you need to start your reaction and do your reaction, and you need to do it by pouring the enzyme into your mix. Are we ready?

Adam - Go, go!

Ljiljana - Go, go, go, go, go! Yay! Oh wow. That's much better than I have done. Wow, look at that foam.

Chris - What did you think of that, David Rothery? I mean, I've asked you about your favourite planet; have you got a favourite experiment?

David - Well that was fun. I mean, watching that liquid turn to foam, which expanded its volume and caused it to shoot up through the long necks of those flasks, was a very good physical analogue of what happens inside volcanoes. The chemistry is different, but when you have a liquid... when a sudden amount of gas gets formed, and it forms bubbles and it changes the volume, it can drive stuff upwards. That's why volcanoes erupt. Because the gases dissolved in the magma come out of solution, turn into foam, and push it up the conduit of the volcano. If it's more explosive than what we saw here, it can break that foam into fragments, and that's what volcanic ash would be. But you very sensibly controlled it here so it didn't break into fragments, and was just a foam and spilled out like bubbly lava. But the physics behind what you showed there is the same as happens in volcanoes. It's just gas expanding the volume and driving the molten stuff up the pipe to the surface.

Chris - Quick question for Ljiljana -  now where's Joe? Joe says he's 10, and wants to ask about famous chocolate bars. Where are you Joe?

Joe - What's the most famous chocolate bar you've worked on?

Ljiljana - Ah, that's a trick question. So I didn't work on any of the brands you will know. But I have here one chocolate, which I think is going to be very famous soon. And this is a chocolate which we developed to celebrate a birthday of Nikola Tesla, who's a famous physicist. And he has done lots of experiments with electricity. And he comes from a region in Europe which is famous for plums and berries, so we designed the chocolate - which is very delicious - which has plums and berries. So this is my next famous chocolate that I'm going to work on.

Chris - Now when you say you designed the chocolate, do you mean you fiddled with the recipe, or you use some of your magic enzymes? In what way did you design it?

Ljiljana - So we do fiddle with the types of the chocolates, cocoa beans, that we take. We play a little bit around with a mixing of the chocolate with the ingredients. And if you want to get a soft, liquidy core in your chocolate, you actually use an enzyme.

Chris - Talk nicely to Ljiljana at the end, Joe; she might give you a bit of her famous chocolate bar.


The BepiColombo Probe is Europe’s forthcoming mission to Mercury.

David Rothery: exploring Mercury
David Rothery, Open University

Volcano expert and professor of planetary geosciences at The Open University, David Rothery tells Chris Smith about his work, first off, how he first became involved in the BepiColombo mission...

Chris - Now. David, you told us some interesting insights into the BepiColombo mission and Mercury at the beginning. So chance now to dwell it more on that theme. So first of all, tell us how you got involved in that, because it's not everyone who gets to send a space probe to another planet.

David - Oh, I was invited to go to Paris to make the geological case for going to Mercury in 1997, because the guy who was meant to go, couldn't make it, and I got roped in. And I was thinking, Mercury's a boring place, but hey, we've only had one spacecraft there, so we really ought to go and take another look. Since then, we've had NASA's mission Messenger, which orbited Mercury and produced wonderful data. And we now know Mercury is a planet which just doesn't fit. It's the closest one to the Sun. It's rocky, but it's got lots of volatile substances there. We don't know what they all are. We've measured a lot of sulphur, which is a surprise. You wouldn't think that close to the sun sulphur would condense, but there's all these visible signs on the surface as well. There have been exploding volcanoes, where something in the magma was turning into gas and blasting great holes in the surface. We don't know what that substance is that's available to turn to gas in volcanic eruptions.

Chris - What is it actually like on Mercury though? If we were to go there, not that we could, but if we were to go there, what would it be like.

David - If you were standing on the surface of Mercury, it would look like standing on the surface of the Moon. It's airless, it's bare rock, but most of the rock is broken up to powder by continual bombardment, by meteorites hitting the surface. So it's very powdery. You might find a few fist sized lumps of rock, but no cliffs of solid rock. The outer part is all very powdery, but it's not so badly mixed that there are no compositional variations. We do know the composition varies from place to place, and it's been resurfaced by lava flows. And then what's happening today in some places, is either the heat or the sunlight or the solar wind is attacking the surface and turning some of it to vapour, because we've got steep sided, flat bottom depressions, 20 meters deep, that's all widening, with cliffs at their edges, getting wider with time taking the top 20 meters of the surface away, and we don't know how it's happening. We don't know what's being lost.

Chris - What's the temperature, how hot is it there? If I had a thermometer, what would it read?

David - Noontime, about 400 degrees. By night about minus 150. So there's a quite wide temperature range. But that's not enough to boil rock.

Chris - When you say night time, is it turning like Earth is or not?

David - It is turning. It rotates on its axis three times for every two orbits it makes round the Sun.

Chris - So the day is longer than the year?

David - Three spins for two orbits actually makes the day, measured from the Sun, twice as long as each year. So sunrise to sunrise is two Mercury years, which is 176 earth days. So we've got wild temperature extremes, slow spin, and weird things happening on the surface, which we do not understand. But we'll measure much better when BepiColombo gets there. We hope.

Chris - Yeah. Yeah. After 15 years in space, I'm sorry...

David - Well, it's about a nine year cruise and then at least a year working in orbit.

Chris - And then you hope it wakes up at the end of that because that's obviously a risk, isn't it? When the probe is mobile through space, of course, you hope it's going to work when it gets there, because you've got no way to control it.

David - It hasn't been turned off during cruise, the instruments are being tested. When it comes back past the Earth. In mid April, we'll run some experiments and the two Venus fly-bys, we'll collect data. But because it's two spacecraft traveling together, most of the instruments can't see the sky properly, so we won't be operating in full operational mode when we fly by Venus, or when we fly by Mercury several times. It's only when we get into orbit and separate the spacecraft and point instruments down to the ground, that we start getting our real science, but we do know it's working.

Chris - Has it got batteries or solar panels? How are you powering it?

David - Solar panels. Panels to power it when we're in orbit around Mercury, and while it's going to Mercury powered by the ion drive, it's solar electric propulsion. We've got seven metre long solar panels either side of the spacecraft. And blimey, that was tense when we got into orbit and unfurled them, I was thinking if they don't open out, we're in trouble. But they did. We collect electricity from sunlight, use that to ionise xenon gas, which has vented out through the exhaust very fast, and that's our ion drives, xenon ions. It's basically the Starfleet impulse drive.

this is a picture of a satellite orbiting Earth

39:01 - How satellites right themselves

Science demo superstar Dave Ansell explains how satellites and spacecraft orient themselves...

How satellites right themselves
Dave Ansell, Sciansell; David Rothery, Open University

Science demo superstar Dave Ansell explains to Adam Murphy how satellites and spacecraft orient themselves...

Adam - So, navigating in space seems to be a bit of a trick. So we moved to our next demo, which appears to be a stool sitting on a DJ turntable. Dave, what have we got going on here?

Dave - I thought I would pretend to be a spacecraft.

Adam - You're going to be what kind of spacecraft?

Dave - It doesn't really matter.

David - Be BepiColombo!

Adam - Okay. BepiColombo. What have we got going on here?

Dave - I have a problem. If I'm standing up, normally I want to turn around. All I do is I push on the floor. Floor gives an equal and opposite reaction to me, and I turn around. Dead easy. The problem is, if you're in space, you've got nothing to push against.

Adam - Right.

Dave - So this spinny stool is a good model of a spacecraft in one particular way, and that is I can't apply any force to the outside world. And so I can try and turn around and all I do is just kind of wiggle.

Adam - I assume spacecraft don't actually wiggle.

Dave - No, because engineers have worked out a solution to this problem.

Adam - So what is that solution?

Dave - What they have is a wheel.

Adam - A bike wheel?

Dave - Probably not a bike wheel, something more expensive and with better engineering in it. So what I can do now, is if I want to turn around, I can apply a force to the bike wheel. So if I push one way, the bike wheel applies a force to me in the opposite direction and I turn around. If I stop the wheel, I stop. If I spin the way the other way, I go the other way by doing this you can certainly turn round the spacecraft and then stop.

Adam - Is this what spacecraft are doing to turn around?

Dave - Exactly. They have, normally, at least three wheels on different axes. They can spin them up and slow them down and turn round, and there's probably some horrific gyroscopic effects, which I don't want to think about, but luckily someone else's engineering problem.

Adam - Space is complicated.

Dave - Indeed. The problem is if there's a force on you from solar wind, or even just light, light can apply a force to you, you'll start moving a bit. You can spin up, start moving, you can spin your wheel up and kind of slow yourself down. But the problem is at some point, you get to a point where you can't spin the wheel fast enough to stop moving, at which point you have a problem. They solve it for a while by throwing stuff out.

Adam - These highly scientific bags of rice?

Dave - My model of a rocket is to have a bag of rice. So if I'm turning this way and I throw a bag of rice out I can slow myself down a bit. And instead of throwing bags of rice, obviously you use hot gases in a rocket, but it's the same principle. You push something that way, it pushes you back, you stop moving so you can slow yourself down and you can slow your gyroscopes down. And it goes great until the forces build up and you've run out of fuel. At which point your spacecraft's dead. Cause if the spacecraft doesn't know where it's pointing and can't point at things, it's almost useless. You can't point your antenna back to home. You can't use your rockets to point in the right direction. Your spacecraft's dead.

Adam - I suppose if you want your telescope taking photos of stars, you don't want it pointed at your house.

Dave - Or spinning round very fast. It would be even worse.

Adam - Nice pictures though. So Dave, you mentioned BepiColombo is going to split in half as it goes around. How is it going to control doing that?

David - It's built in two parts. The Japanese one will be spun up and set loose, and the European one will be concentrating on looking at the surface. It has reaction wheels to flip it round. All spacecraft that need to point in different directions, use these reaction wheels, because you can get electricity from the Sun to drive them and you can use those to steer you without having to vent rocket fuel all the time. Yes. Excellent demonstration of how spacecraft are steered.

Adam - Amazing. Thank you.

Now where's Dan G who's aged 11 because Dan's got a question for you, David Rothery about volcanoes. Hello.

Dan G - How many volcanoes are in the solar system?

David - Okay, Dan, do you mean volcanoes that are still erupting or that are extinct?

Dan G - That are still erupting.

David - Still erupting. Okay. That's easier. Thank you. On Earth, that have erupted in the past 10,000 years and that might still erupt, there are several hundreds. On Jupiter's moon Io, there are again, hundreds which are erupting and these are both erupting molten rock. There are volcanoes, if you want to call them that, on Saturn's moon Enceladus, which is venting ice particles into space like an explosive eruption. They're called cryovolcanoes, icy volcanoes. And there are several fissures near the South pole that are venting those. Those are the active places for volcanism and cryovolcanism.

And then Mercury has got a hundred or so of these explosive volcanoes that I mentioned just now, but they're extinct. They're not operating today and unlikely to erupt ever again. Almost every rocky surface, Venus, we think might have active volcanoes today, there's a big push to get another mission back to Venus, which can nail that, but the whole surface of Venus, 90% of it is made of volcanic rocks. So they've been erupted from volcanoes. So volcanoes are everywhere on icy moons, on rocky moons and on rocky planets. It's a very important process in forming the crust of the planet to begin with.

Chris - David Rothery. Thank you very much.

Beetle on flower

44:08 - Eleanor Drinkwater: amazing insects

We chat to insect behaviour expert Eleanor Drinkwater!

Eleanor Drinkwater: amazing insects
Eleanor Drinkwater

Beetle enthusiast doing research on woodlice personalities, Eleanor Drinkwater told Chris Smith about the wonderful world of insects...

Chris - So Eleanor, we had a quiz on the Naked Scientists the other day and one of the questions was that "all the spiders on Earth could eat all the humans on Earth in a year" (true or false). Do you know what the answer was?

Eleanor - No, I don't, but I would love to know that.

Chris - Who thinks it's true? Hands up. A handful of people. Actually it's true! Because if you work out how many hundreds of millions of spiders there are and how much the spider eats, when you scale that to the population of spiders on Earth, they would actually easily devour all 7.7 billion humans in under a year.

Eleanor - But the question is would they want to, because a fly or something like that to many spiders be very tasty. But take a look at a human, we're gusting in comparison.

Chris - So you're saying, human vs blue bottle, you'd rather eat a blue bottle?

Eleanor - If I was a spider!

Chris - Where I was going with this, is that there are extraordinary numbers when we actually add up the scale of the insect world, of the microscopic world. It's enormous in terms of the numbers, isn't it?

Eleanor - Yeah, I absolutely love thinking about it. So, so for example, insects alone, this is not including anybody like snails or anything like that, just insects alone. We know about 1 million species on the planet, but actually estimates put the actual number of species at about 10 million. So just the number of un-described species is absolutely phenomenal. And that's species. If you got a giant set of weighing scales and you put all of the insects - again, just insects, no snails or anything like that. Just insects - on one side of the weighing scales and all the people on the other side of the weighing scales, the insects would probably weigh about 70 times the amount of people, which is just wonderful to think about.

Ljiljana - We are still learning so much from insects. For example, there is a new type of colours that we make, new types of kind of dye like materials that were inspired by butterflies and the way how they create their own colours. Or spiders. We are working now also in my lab a little bit with materials which are inspired by silk that spiders make. So they make an amazing number of chemicals and structures that we are really learning about them now.

Eleanor - And the thing that I find phenomenal is the fact that we just know so little about so many, even all the really big charismatic species like you know, my favorite beetle is, is the Titan beetle, biggest beetle on the planet. No one has ever seen it's larvae.

Chris - How big is it?

Eleanor - So it grows to about 17 centimeters. And the crazy crazy thing is that yeah, that's big, but baby beetles are bigger than the adult beetles.

David - How do they give birth then?

Eleanor - That would be cool to see. But no, no, no. They lay an egg. The life cycles are just remarkable. So taking something like the Titan beetle, would probably have the case that the eggs are laid, and it will grow into a larvae and then it will stay as a larvae in the soil, in the rotting rotting wood for like perhaps five to 10 years as a larvae, but for emerging into an adult, in which its adult lifespan is perhaps maybe two or three weeks. Just remarkable that they've evolved this really wonderful life cycle.

Chris - I remember going to New Zealand to Waitomo, which I think is a wonder of the world really, the modern world. I don't know if you've been there, but it's the glow worm caves there and there are so many glow worms in this cave that you can read under the light that they produce. It's really stunning and I interviewed one of the people who was taking us round on this tour and he said, it's a pretty miserable life if you're a glow worm though, because you live in the roof of this cave and you produce this light and dangle down your fishing line, thread to catch insects and things which you then eat and devour, your sole aim being to get big enough to then turn into a fly, which doesn't actually have a mouth. So you're born and you live as long as you can survive with the energy you've already packed in, in order to just find a mate, mate and die!

David - But you don't have to take her out for a meal before you get what you want.

Chris - David, I can see you're clearly a romantic. When's your next anniversary?

Chris - What about intelligence in insects though? Because we think of ourselves, we have this very, very kind of superlative view of ourselves, and we think we're the pinnacle of intelligence and things. Are insects, particularly clever?

Eleanor - There is so much more going on in invertebrate cognition than perhaps many people are aware of. I always feel like we're just beginning to scratch the surface of what many species are capable of. So taking, for example, bees, there's always so many lovely experiments done on bees. There was this absolutely lovely experiment that was done showing that you can train bees to tell the difference between paintings done by Monet and paintings done Picasso. And if that's not a like higher cognitive ability, I don't know what is!

Chris - Which do they prefer?

Eleanor - Ah, I don't think they went that far! Or wasps. They can tell the difference between individuals by their different facial markings. Again, bumblebees. There was another lovely experiment done in which they essentially trained them how to play golf, which was just a great experiment. They, they trained them to push a little ball to go down a hole and then they get treated. They got it and they're very capable of, of learning.

Chris - I remember reading that because that was done at Queen Mary University of London. We talked to them about that and they said, not only could you train a bee, but a bee will train another bee. So the bees will watch the first one do it and then they can copy, so they can play golf and waste their life away too. Questions? This one came in from Stephanie. Stephanie says, "I read that an endangered komodo dragon can give birth without a male. If so, how?"

Eleanor - Wow, that is a very good question. I don't know anything about komodo dragons, but I do know something about snails. This is relevant, I promise! So snails like Shellock Holmes here, is both simultaneously male and female. So has the ability when they can't find a mate self-fertilise themselves with their own sperm. So I know that's what snails do. Do you know how komodo dragons do it? Is it the same?

Chris - Yeah, it was 2006 and it was actually London zoo and they had a komodo dragon that was female and they were most surprised when they got another komodo dragon from one single female komodo dragon. This is a process called parthenogenesis. And unlike humans, when we have sex and you mix eggs and sperm, if you have an X chromosome and a Y chromosome, you get a man. If you have an X and an X, so an X sperm and an X egg, you get a female. Now with komodo dragons, there's actually three different combinations of genes they can have, but we'll leave that to one side for one moment. It suffices to say if you have the equivalent of two X chromosomes in a komodo dragon, you are male. If you have two different chromosomes, you are female. So if you have a female komodo dragon that say washes up on a beach and it's one female on its own, it's going to have two different chromosomes, but because it's got the ability to then make an egg, which has only got one of them in it, that egg can then turn into by, copying the chromosomes, one that's got two sets of the same type of chromosome X, X and so it has a male baby. And that means you've then introduced into a population of what would be exclusively females a male and they can then reproduce sexually again, and introduce genetic diversity. So yes, that's how they do it Stephanie.


liquid nitrogen

51:56 - Boom! The Naked Scientists

What happens when you put the lid on a bottle containing liquid nitrogen?

Boom! The Naked Scientists
Dave Ansell, Sciansell

To end our show this week, science demo superstar Dave Ansell showed Adam Murphy what happened when he put a lid on a fizzy drinks bottle containing liquid nitrogen...

Adam - We are almost at the end of our show, but we did call this show, Boom! The Naked Scientists, didn't we? I think it would be a little poor to leave you without actually giving you a proper boom. Now remember Katie at the start mentioned about covering your ears? Well we're getting into that part of the show now. So I'm going to go over to Dave who on his table has an ominous metal canister. So Dave, what is in the ominous metal canister?

Dave - So in here we have something which is a little bit chilly. Well by physics standards it's not particularly cold, it's about minus 196 degrees Celsius. This is what happens if you take normal nitrogen, which we're surrounded by in the atmosphere, and cool it down to minus 196.

Adam - And I'm guessing that this smoking plastic cup full of bubbling liquid is something I don't want to drink?

Dave - People have done this and died horribly.

Adam - so no then!

Dave - So this is nitrogen, it liquefies at minus 196 which means if it gets anything above minus 196 degrees Celsius, it boils and we can see kind of what effect that will happen on the liquid boiling by first cooling down this balloon.

Adam - Let's feel sorry for a balloon, this is a first.

Dave - This is a balloon I blew up with just my own breath earlier. You'll notice something happening to it.

Adam - You're putting the balloon in the thing. And that is far too big a balloon to go into that flask normally. So when you pull that out of the flask ... you have a tiny apple shaped little balloon.

Dave - I don't know if you can see the little bit of liquid, which is sloshing around in the bottom? Yeah. So that tiny amount of liquid is boiling to blow up the whole balloon again.

Adam - So is that, is that the air that's turned to liquid?

Dave - So we've liquified air, which takes up much less space than gaseous air. Um, so the balloon shrank and now it's boiled again and it's expanded about a thousand times, blowing up the balloon, which is why swallowing liquid nitrogen is a really bad idea.

Adam - Expanding would be bad. I don't want to be this balloon.

Dave - Yeah. Because basically you're 200 degrees Celsius above nitrogen's boiling point. Um, it's going to apply an immense pressure as it tries to turn into a gas and basically you're not going to be able to contain it.

Adam - So, pausing for effect, what can we do with putting liquid nitrogen in somewhere we're probably not supposed to unless you have scientific supervision!

Dave - And I've written many, many risk assessments over the years. Um, so this is actually one of the two major ways you can kill yourself with liquid nitrogen. The other one is by getting in a lift with it or in some kind of confined space, it excludes all the oxygen and you just suffocate. But the one we're looking at today is putting it into a sealed container. We have a half litre fizzy drinks bottle here, I am just going to put on some ear defenders as they will come in handy later.
Adam - Thank you. I was about to ask where are my ear defenders!?

Dave - And I'm now going to pour in some liquid nitrogen, at the moment this is completely safe. Apart from my fingers might get a little bit chilly.

Adam - So not completely, relatively.

Dave - So the point at which this becomes dangerous is if I put the lid on the bottle, because lemonade bottles are incredible pieces of modern engineering. They cost just a couple of pence and they're incredibly strong. They fail maybe at 10 atmospheres, so 10 times the pressure we feel now, which is about a hundred tons per square meter, it's so a lot, a lot of pressure. So putting the lid on is what makes this dangerous. To do that, I've got to come over here...
Adam - Safety first. We have a wheelie bin.

Dave - We have a wheelie bin to contain anything flying out. There's a wonderful video on The Naked Scientists website of this blowing up with no wheelie bin, and it's petrifying. So I'm about to put the lid on and shut the lid very quickly. Okay. Three, two, one...

Adam - Anyone else a little nervous? Going to slowly creep ... across the stage...

Dave - So what's happening very slowly is that -


Dave - The pressure built up until it went bang!


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