QnA: Fridges and impossible food

We're tackling the science questions you've been sending in!
13 August 2019
Presented by Chris Smith
Production by Katie Haylor.




In this month's QnA show we're asking: why are fridges harder to open again after you just closed them? What’s the best way to wipe the memory of a smart phone? And what might climate change mean for chocolate? We're answering your questions with the help of an expert panel - neuroscientist Duncan Astle, techxpert Peter Cowley, food security expert Nadia Radzman and engineer Livia Souza...

In this episode


Meet the panel: brains and concrete
with Duncan Astle, Cambridge University; Peter Cowley; Nadia Radzman, Cambridge University; Livia Souza, Cambridge University

It's time for a science show and tell! Chris Smith met Cambridge University cognitive neuroscientist Duncan Astle, Cambridge University food security expert Nadia Radzman,  Cambridge University engineer Livia Souza and tech expert Peter Cowley...

Chris -  Now with me to tackle the questions this week are; Duncan Astle who's a cognitive neuroscientist at Cambridge University. And sitting in front of him is something very interesting. What have you go there Duncan?

Duncan - It is. Let me describe it to you. So it looks like a tiny sculpture of a brain.

Chris - It looks like a truffle.

Duncan - It might look like a truffle, or maybe a walnut.

Chris - Yeah.

Duncan - It's around an inch and a half long, about an inch wide. It weighs, I’m going to hand it to the person next to me who's going to hold it. So it looks like a tiny sculpture but actually it's not. It's a real 3D printed brain.

Chris - Of what?

Duncan - That's the brain of one of the research fellows in my lab.

Chris - Is it really that small?

Duncan - It's life size! No, it’s not life size. I've made that joke to him many times.

Chris - What's his or her name?

Duncan - So it’s Edwin's brain

Chris - It’s as well endowed then, Edwin isn't he, cognitively speaking at least?

Duncan - He's a smart guy. Now this is actually, it would need to be about three and a half times larger.

Chris - Yeah

Duncan - For it to be his real brain. Now it's quite heavy because it's made from a steel and bronze alloy. We took a magnetic resonance imaging scan, in our department, of his brain. We have those from everyone in the lab, and then there's a company that you can send them off to and they will render it for you, and then they will print it for you in different types of substance.

Chris - Are you saying you've got this for everyone in the lab? Is this an inclusion criteria to work in your group then you have to have your brain scanned and then and then a 3D model made just to make sure you've got one.

Duncan - It's more of an inclusion criteria that they are willing to be involved in all the research experiments that we do and as a result we end up having lots of brain scans for all the lab members.

Chris - It's interesting that you're saying this though because there is a serious side to all this, isn't there? The fact that previously to study neuroanatomy you'd have to get the brain out of something, and now we're in a position where the scans are so good, like the one that presumably led to the creation of that model, that you can get the brain out of something without actually having to take its brain out. And then you can study these things in front of you, without having to harm anything.

Duncan - Yeah, it's basically been revolutionary in how we think about the brain and how we study it. So this is taken from an image from a three tesla scanner. So that's the strength of the magnet that's been used, but in Cambridge here we actually have a seven tesla scanner, so that's got an exceptionally powerful magnet. And that means that the detail with which you can look at the brain neuroanatomy, is getting increasingly sophisticated. So for instance, with the seven tesla, people are even starting to think that you might be able to look at different layers of cells within the brain. It's that sophisticated.

Chris - That's amazing thank you Duncan for introducing us to that. Now, I'm always worried when I see a falcon tube. These are the kinds of things you pee into when the doctor says give me a specimen, pee into this. But I'm sure Nadia Radzman who is a food security and plant scientist specialist from Cambridge University, that's not why you brought in that red top tube, what’s in there? to you.

Nadia - No, these are the seeds of a plant called medicago truncatula.

Chris - Medicago?

Nadia - Yes. So it's a model legume that we use in the lab to study nodule formation, and these nodules are formed in the roots, well on the roots, and they are globalist structure. They are formed with the association with soil bacteria. So the soil bacteria will be housed inside these nodules, while the bacteria would fix nitrogen from the air and form ammonium, which is available to the plant and the plants will give carbon as nutrients to the bacteria. So it's a win win situation.

Chris - So it's an exchange?

Nadia - Yes.

Chris - So the plants grow these nodules, make a home with food on tap for microorganisms and the microbes are recruited into these nodules where they bring the biochemistry that says I can grab nitrogen out of the air and make it available to you as a plant, and only for fertiliser.
Nadia - So they're pretty much, like mini-factories, mini nitrogen fertiliser factories for the plants.

Chris - Why are you studying this? I mean, is your vision that if we can work out how one group of plants that we don't want to eat, or don't want are we all the time do this, could we make plants that we do want to eat a lot more do it too, and then we wouldn't need fertiliser.

Nadia - Yes so the lab that I belong to, we want to know how legumes actually form these nodules, and if we know the exact process, this is how this is being done, then we could potentially transfer it to something like wheat.

Chris - And that would be important because at the moment we're dumping enormous amounts of fertilisers onto fields to feed a burgeoning world population, and that if we didn't have fertiliser there's no way the world could feed itself. It's fair to say that isn't it?

Nadia - Yeah. And so this is something that is interesting too. So legumes can form these nodules, and fix nitrogen at ambient temperature but if we were to produce nitrogen fertilisers, we need to have high temperature and high pressure. So that would cause a lot of fossil fuels to do that.

Chris - So it's got a big carbon footprint hasn't it? Thanks Nadia. So you can appreciate now where the food security angle comes in. Now next to Nadia is program regular, tech expert - texpert, I suppose you could say, and angel investor Peter Cowley. Now he always brings in fancy gadgets and he refused to tell us what the fancy gadget he was going to reveal is, when he said I'm going to bring in something that's going to wow you out. So what have you got?

Peter - Yeah well I've got it in front of me, I better describe it first. I've often taken it along to dinner parties and ask people what it is. You can see it in the studio. It's about a cubic centimeter, it's about one and a half centimetres long by about 7.5 millimetres by five millimeters. And it's made, it’s a little piece of ceramic, it's got about 100 ceramic pyramids inside it. This isn't helping at all is it?

Chris - Not really.

Peter - it looks like it's got burnt which is a good reason. Now you've got to cast your mind back to, and there won't be many listeners could remember this, but the V1 bombs in the Second World War, which used to fly over us stop, that sound went off and they would crash and there were many many casualties because of that. That was a pulse jet engine. So it was basically like an organ tube where it was igniting, and the gases they expelled pull the next fuel in, which ignited and so on, and that was running through about 40 or 50 hertz. This is ultrasonic apparently. So this is running at 30 kilohertz.

Chris - and what's in that? Are you saying that's a mini rocket engine?

Peter - Exactly. Yes. So its inventor is a guy called Bill Den in Great Shelford, just south of Cambridge, about five miles from Cambridge. And he does it in his shed, and I nearly invested in it in 2012. His main problem, I've got actually the final report in front of me, was igniting it, but I've been in that shed more than once, where he has ignited it. A complicated method.

Chris - So you squirt in there, fuel and air?

Peter - Yes, and what happened, is his calculations are, that it's the equivalent of a two litre car engine but double the efficiency. It’s just mind boggling.

Chris - It's just how do you extract the energy? It's just the gas stream emerging at extremely high speed, and that’s thrust?

Peter - It’s thrust. It’s a jet engine, exactly.

Chris - Goodness. And has it gone anywhere?

Peter - I don't think so. I don't think it’s gone through. I checked the company’s house and the company’s dormant at the moment. So the idea behind it, which the application’s the interesting thing, is things like putting a jet engine on the trailing edge of an aircraft wing so you haven't got that thing. So it's just basically a line of these. Got a longer one here which is probably equivalent with six litre petrol engine, which is about three centimetres long. The fluid dynamics possibly doesn't work, because the molecules size, if you think you've got fuel and air molecules are a certain size. How can you get those down to that size, but then you have seen it producing thrust, he ignited it rather clumsily but it was it was taking I think, propane gas in, and generating thrust which you could see. So that's what I brought in because it's just amazing. But we hope certain people like Hermann Hauser, who a name you might know from Cambridge who invested in but I didn’t, how it went.

Chris - We’ll have to get Hermann on, and ask how it went. I mean Duncan's impressed.

Duncan - It's basically like a tiny Lego box.

Chris - Yeah. It's a good way of putting it. It's very very smart to think that could do a two litre engine. It’s amazing.

Peter - We ought to tweet a photograph of it.

Chris - Thank you for bringing it in Peter, now sitting next to me, is Lívia Souza and now she's a civil engineer. She's also a chemist by original training. She's part of a group at the University of Cambridge who are developing self healing concrete, sounds extraordinary, why do we need self healing concrete and how does this work?

Lívia - Yeah, we need it because well there is a lot of CO2 emissions associated with the repair and maintenance of the concrete structures that we have nowadays. So the idea is, when there is a crack in concrete, what if the crack can repair itself without any external intervention, and to do so what we do is-

Chris - Oh this is where your show and tell comes and you've got what looks like a blood sample in front of you, a big pot of something! What on Earth is in that pot? It looks like jelly

Lívia - Because it's red! Here are micro-capsules. They are in liquid because they have this very interesting property that when they are wet they are very ductile. They are very soft and rubbery and when they are dry they are very brittle. So we use this as a property, for we can mix these micro capsules with concrete very easily and they are very rubbery.

Chris -This is when you're making the concrete, when it’s liquid, so you’d mix some of that in at the time when you’re making the concrete?

Lívia - Yeah, and it's worth mentioning that they are very tiny. While these ones are a bit larger so you can see them, basically, but the ones that we are actually producing in the lab are very very tiny, 100 microns, 200 microns, of size

Chris - So that's a tenth of a millimetre to a fifth of a millimetre, so very very tiny these capsules. What's in the capsules? What's the chemistry here?

Lívia - So the idea is we mix them with concrete and then when the concrete settles and dry and when there is a crack in the concrete, the crack opens the capsule and releases the healing agent.

Chris - And what’s the healing agent? What’s in there?

Lívia -  This healing agent can be a polymeric material like epoxy for instance, or it could be a mineral such as sodium silicate, or colloidal silica that can form a healing product or interestingly it can be bacteria.

Chris - The thing is, this is gonna be great for concrete we’re laying now. But obviously for the buildings that are already up there. Not so good. Or can you inject this into already injured concrete and get it to heal there?

Lívia - The technology is so recent and so interesting that we are thinking about ways of using it, and one way is to repair the structures that are already existent. A good example, it's a case in the Netherlands, where it was a massive parking lot and they had infiltration and that it was damaging the whole structure because of cracks. So what they decide to do is to spray this self healing technology using bacteria over the whole structure, and it would repair itself and hopefully it could repair in the future autonomously as well.

Chris - Yeah could be bad if you've got a really ugly housing estate though that you'd quite like to fall down and you're coming along with your self healing concrete could mean it's a monstrosity for a lot longer than we’d like couldn’t it?

Lívia - That would be bad!

Brain schematic

Why do people get deja vu?

Neuroscientist Duncan Astle delved into Paul's question...

Duncan - Who knows what déjà vu means? Who’s good at French? ‘Already seen’. It’s that sense of familiarity but in the absence of an explicit memory of something. So as you can imagine there are lots of different theories as to why we experience déjà vu. I'm going to give you my favourite one, because I think it's probably the most plausible one: and that is that déjà vu is the moment when you become consciously aware of a discrepancy between two different memory signals that come from two different memory systems. And it's the signal about what you think you've experienced before, and the signal about what you've actually experienced before.

So there are actually multiple different memory systems that we use all the time. They have slightly different underlying neurobiological implementations; some of them are really to do with learning about and remembering episodes, so facts that have happened. Others are more to do with learning about the general principles of the world around us. For instance I knew the way here but I couldn't remember the first time that I had been here.

Now you can imagine the situation where these two systems give contrary indications, so that you get a very strong feeling of familiarity but in the absence of an explicit memory. And one theory of déjà vu is it’s the moment when you consciously realise that you're getting these two conflicting signals about one particular experience.

Chris - What tends to make it happen?

Duncan - No one knows for sure. For instance when people are more sleepy they tend to be more...

Chris - I was going to say, ‘cause I know I've had this and it's happened when I've been jet lagged. It tends to happen to me when I'm really tired or when I've done a night shift at the hospital or something, I get it then. Is that common?

Duncan - It is. When studies try and look at it experimentally, one of the ways that they try and induce it is by sleep depriving people. 

Chris - And is that just because one of the memory circuits you allude to is failing to imprint a memory properly and another one thinks it has, or one of them thinks it's put something into long term memory and it actually hasn't, and so there is this disparity arising. Is it a memory failure or is it just spurious signals being generated by a tired brain?

Duncan - I suspect it's that when you're really tired you're less able to disentangle these two sources of information and that's why you get this moment of conflict.

Using a mobile phone

What's the best way to wipe a smartphone?

Tech guru Peter Cowley tackled Golfvswag's question...

Peter - First of all you’ve got to understand there's quite a big difference between Android and IOS - so IOS is the Apple operating system; Android has about 75 percent of the market in the world, and IOS most of the rest apart from a few Windows phones, except in the UK actually where they’re about 50/50 - because they have different levels of security built in anyway. So first of all there is a function in all of them to delete or wipe the whole of the contents. But some research was done in Cambridge actually, I think last year, which took a phone - Android phones - and found that you could get data off it again. This is because of something called levelling, wear levelling of the flash memory, where a block of memory is actually not used any longer because it might get worn out. And so to avoid that, I  think there are two possibilities, both of which should be used - well, in different cases. One: if you encrypt it first, the phone, and an IOS phone is encrypted anyway using hardware, but if it’s an Android phone you encrypt it first, then you wipe it, you will almost certainly have removed... there'll be no way of getting at any data at all. First point. With IOS as I say there's a piece of hardware in there and has been for the last nine years or so. Of course the final, which doesn't allow any recycling, is just to get a sledgehammer.

Chris - That works quite well, doesn't it.

Peter - Well I suspect it probably works well but you've still got to break the chip involved. And so if a crime was involved which might involve murder, and it's not completely broken, then it could be cracked.

Chris - You could still read that. Lívia?

Lívia - How do you encrypt the phone?

Peter - The encryption is a software encryption on an Android. There's a switch inside it, so you go into the settings, you'll find ‘encrypt’. The problem about encrypting is that the decrypt process can take time. Which is why on IOS it's done in hardware, it's done as the data is coming out of the memory chip in hardware, and therefore it's done the whole time. So information on an IOS device, an Apple device, is always encrypted. So you'd actually have to force the encryption. Whether there’s a knock-on effect on an Android device we’ve encrypted because of the speed of response, I don't know, because I use Apple.

Water lily on a black background

What plants can we grow in space?

Food security expert Nadia Radzman from Cambridge University dug into the answer to Agasthya's question...

Nadia - Right. So what kind of plants? I'm guessing small enough plants to fit in the growth chamber that we currently have in the ISS, the International Space Station. So there is this small cabinet-size chamber that astronauts can grow plants in. So a couple of plants that had been grown before in space are lettuce, cabbage, Chinese cabbage, and also the model plant that we usually use in the lab called Arabidopsis thaliana - so it's a very small plant. A couple of these plants were grown for the astronaut consumption. So for example I think it was Chinese cabbage that they grew in the ISS and then they actually had to try... I'm not sure about that. But a lot of experiments, plant science experiments using Arabidopsis, are also being done in the ISS. So it's interesting that they were comparing how plants grow in space and on earth.

Chris - Because of course there’s microgravity in space, so these plants are growing in freefall, aren’t they. Is it true to say that plants actually depend on gravity in order to know what's up and what's down? And so therefore in the absence of a strong gravity signal, because they're in freefall, they're not gonna have that. So do they grow all wrong?

Nadia - So they don't exactly grow wrong. They do grow slower than the ones on Earth. And on Earth... so how plants detect where is the direction of gravity is that at the very end of the root tip, there are a group of cells, and these cells would actually detect where gravity is. So in microgravity in space these cells couldn't detect where's the direction of gravity anymore. So they would use light.

Chris - That’s the dominant signal is it? So they just obey where it's brightest and grow towards that?

Nadia - Yes. So the roots will grow away from the light and the shoots will grow towards the light. And it’s interesting, when they had a lot of light, when plants couldn't detect which direction that the lights are coming from, pretty much the roots and the shoots don't have any preference anymore.

Chris - So the answer is we're growing plants in space to see how they grow, but presumably because we're going to need them for food. Because plants are nature's solar panel. They get the energy from the sun, they turn it into chemical energy we can eat. So we're going to need plants in space if we're going to make space journeys. Maybe that’s the bottom line, isn’t it.

A skyscraper

21:16 - Is climate change affecting the way we build?

We're seeing unprecedented temperatures this summer...

Is climate change affecting the way we build?

Lívia Souza, Cambridge University engineer, weighed in on this question from Steph...

Lívia - It is affecting how we we’re planning our cities and how we are building our buildings basically. The main thing to keep in mind is CO2 emission -when we are talking about this conversation, as we are talking about how do we minimise CO2 emissions on our buildings basically. For that, concrete can be very damaging.

Chris - It’s something like 20 percent of the world’s CO2 emissions is just making concrete - I think - isn’t it? It’s a very large number.

Lívia - I think it’s around 7 - 10 percent? But it’s still quite big.

Chris - It’s still a big number... I mean, obviously, you get a bit of payback because the concrete takes down some carbon dioxide from the atmosphere when it goes off doesn't it and turns back into a solid. But even so, you have still got to bake this mineral at very high temperature to make the concrete in the first place.

Lívia - I think we have the massive payback in terms of infrastructure for people that is provided with concrete. That's amazing. But we are paying a price for it because - another conversation on that - when we're talking about reducing the use of concrete for buildings, so we could be using timber, for instance or bio based materials in general. When we are talking about changing the technology we are talking about developed countries. What if we're talking about developing countries? How is this moving forward?

Chris - Duncan?

Duncan - In 20 years time, do you still think that we'll be using concrete as we currently use it or is your vision that we'll have come up with some - not timber - but some alternative substance?

Chris - Why not timber? I mean, timber is pretty good as a material isn't it? I mean it's carbon neutral, potentially, and it's very long lived and it's very strong, what's not to like?

Duncan - I'm sure it's great for certain kinds of structures but I'm guessing there are lots of structures that we might want to build - like airports for example - in the future which it might be difficult to make it out of timber. You know you can pour concrete, you can set it, you can do all sorts of things to it

Chris - Well, you wouldn't build a nuclear bunker out of - probably - paper. I grant you that. You probably would need concrete for that. Wood’s a pretty good material - I mean - surely that's going to be one of the things that's factoring into the equation more and more?

Lívia - More and more we are thinking about straws, we're thinking about hempcrete - concrete with hemp bits in it...

Chris - The bits you can’t smoke?

Lívia - Can set fire in the house

Chris - Nadia?

Nadia - Referring back to the self-healing concrete - can we use it as a building material?

Lívia - That's the idea. The buildings that we are making right now. The idea is to make it as resilient as possible. So for the future they need very little repair and maintenance.

Chris - What you’re saying is rather than having to make more cement and more CO2 carbon footprint in the future, make the building once and make it last longer - and also make it repair itself into the bargain.

Lívia - Yes. To reply to your question Duncan - a challenge. Because to think about new materials replacing concrete we are also talking about changes in policies, isn't it? And the UK may think about it but other countries may be not thinking about it and concrete is still quite cheap to produce. Environmentally it's not so much but cost is very good.


24:55 - What temperature is the moon?

What temperature is the moon, with and without sunlight?

What temperature is the moon?

Chris Smith answered this question from John...

Chris - The answer to this - we know this very well - because of course it's been measured directly by NASA. We heard a couple of weeks ago all about the moon landings - and things - when we celebrated the fiftieth anniversary of the first moon landing. The answer is that it matters whether you're in the sunlight or not in the sunlight because the energy reaching the Earth comes in the form of radiation from the sun. And that includes light we can see and light we can't see such as ultraviolet radiation. That energy hitting a surface like the moon's surface or an astronaut spacesuit is enough to warm it up to more than 120 degrees.

So the lit surface of the moon is at about 120 to 130 degrees C. That's why the astronauts needed such fancy spacesuits to keep their body temperature correct and reflect off a lot of that radiation. But at the same time if you go out of the illuminated part of the moon you're not having that heat hitting you anymore and the temperature plummets.

And at night-time on the moon - because the moon isn't always permanently illuminated - the night-time temperature the moon is about minus 170 degrees or even colder in some places. And so that's why people are interested in the water that's on the moon, for example, in some of these deep dark recesses because that's actually part and parcel of the material that was laid down when the moon was formed probably through a huge collision about five and a half billion years ago - about five billion years ago - four point five seven billion years ago, we think, when something clobbered the Earth and formed a fusion of two planets and our moon.

And so that material can tell us a lot about what what the Earth was made of, what that other planet was made of and therefore what the moon's also made off. But yes, very very cold - minus hundred and seventy degrees C - so certainly a chilly one.


27:23 - Quiz: how many hearts does an octopus have?

Peter and Nadia face off against Livia and Duncan...

Quiz: how many hearts does an octopus have?

Who will win Naked Scientists' big brain of the week? Our teams are tech guru Peter Cowley and food security expert Nadia Radzman, facing off against neuroscientist Duncan Astle and engineer Lívia Ribeiro de Souza...

Peter and Nadia, you’re team 1. Duncan and Livia, you’re team 2. You’re competing for the honour of the naked scientists’ big brain of the week. Ready?


There are three rounds - the first one is sci-fi or sci fact? And for this, we’re going under the sea...

So Peter and Nadia...

Q: Octopuses have 8 hearts, 1 that powers each tentacle. Science fact, or sci-fiction?

Nadia - I am not sure…

Peter - I’m sort of towards no.

Nadia - … I would say yes.

Peter - Okay, so we disagree. Is there a coin we can toss?

[Laughter in studio]

Chris - What are you going to go for, science fact with 8-hearts?

Peter - Nadia is going to answer it.

Nadia - It’s too many hearts on one organism, I would think.

Chris - So you think science fiction?

[Correct buzzer sounds]

It is indeed science fiction! They do actually have three hearts.

Peter - Per leg?

Chris - Ha ha, no that would be 18… Wait, 24! You’re testing my maths. Two of the hearts move blood through the animal’s gills, while the third keeps the organs perfused. The interesting thing is that the third organ perfusing heart actually stops beating when the animal swims, which is why they tend to slink around and crawl about. It's more efficient in terms of their circulatory demands.

So plus one to you two. Right, Duncan and Livia. You're up next.

Q: American explorer Victor Vescovo, during his descent to the bottom of the Mariana Trench, the deepest ever dive, found what?

A species of 12-eyed fish, since named decem-oculus pisces.
A cannonball fired from a military naval vessel thought to have participated in the Battle of the Java Sea.
A Tin of spam.

Or, all of the above?

Duncan - Naval History is not really my thing. The cannon ball seems plausible but…

Lívia - I feel like saying “all of the above” just to cover all of the options.
Duncan - I can imagine all of the above is true.

Chris - You’re going all of the above. Is that true or is it false? Well I'm afraid to say....

[Incorrect buzzer sounds]

No it's not true. The fish we made up. The cannonball? No idea but there might be one of those down there but he certainly didn't find it. He found a tin of spam.

You can look at the picture, it's really quite staggering. At five kilometres down, on the slope, on the way down into the Mariana Trench. Even deeper down he did find plastic bags, some sweet wrappers and some other angular metal objects, which we'll assume were human made. But no twelve-eyed fish or cannonballs I'm afraid, Duncan and Lívia.

So no points for you so far. Right round two, you're in the lead Peter and Nadia.

Q: Which is taller?  The Empire State Building in New York or the Shard in London.

Peter - The Empire State Building is about a thousand feet and I think the Shard slightly higher. My guess is it's probably about 10 to 30 metres higher.

Nadia - I’ll go with your answer.

Peter - I would say the Shard.

Chris - And the answer is....

[Incorrect buzzer sounds]

...No. New York has clinched it. The Empire State Building 381 meters the Shard is 310.

Peter - That's including the mast on the top though, isn't it?

Chris - Well I didn't say that! You're just getting desperate now, Peter. Okay, so zero for that round, Peter and Nadia are still on one.

Duncan and Lívia your chance to claw back the victory..

Q - Which has the fastest acceleration -  that’s nought to sixty… Or one hundred kilometres an hour for people on new money - a cheetah or a Ford Fiesta ST, that's a sports turbo Ford Fiesta? So what can accelerate nought to sixty the fastest, a cheetah or a Ford Fiesta ST?

Duncan - I used to have a Ford Fiesta…

Chris - Was it an ST though?

Duncan - No it wasn’t!

Chris - Hmmm, that's the difference. See I had a Ford Fiesta and it definitely was an ST.

Duncan - I know cheetahs are really quick.

Lívia - Yeah, I would guess cheetahs

Duncan - Nought to sixty… Sixty is quite fast for a cheetah to go.

Lívia - Cheetah.

Duncan - Yeah, we’re gonna go cheetah.

Chris - And the answer is…

[Correct buzzer sounds]

Yes, you’re plus now so it’s level pegging now so well done.

The cheetah is faster by far. The Ford Fiesta ST, the 2012 to 2017 model, is quoted to do 0 to 60 in 6.7 seconds, the cheetah achieves that in three.

Everyone - Wow.

Chris - It's elastic energy in tendons and muscles, it’s an explosive burst of speed. The acceleration, the rate of speed, changes very fast, much faster in the car. What the cheetah can't do is to keep it up for any duration. It can do that for a matter of seconds. The Ford Fiesta hopefully manages a little bit better than that.

Level pegging on round three… It’s all on this one. Otherwise, we go to tiebreaker. Back to you Peter and Nadia.

Now this round is called “The shoe’s on the other foot” because we ask you a question that the other team are experts on. They get to laugh when you get it wrong but don't worry the shoe will be on the other foot once we get to the second part and it’s their turn.

Peter and Nadia, a brainy neuroscience question for you. So Duncan, Lívia, no chipping in here.

Q: The human brain accounts for about 2% of your body weight. To the nearest 10%, how much energy does it use, as a percentage of the total energy used by the body?

Peter - So how much energy does the body use? The rest is probably 300 watts, 400 watts?

Nadia - I know that the brain requires a lot of glucose and oxygen. So when you are oxygen deprived, you can get brain damage.

Peter - So it’s to the nearest 10 percent?

Chris - I just need a number in percentage terms. I'll give you plus or minus 10 percent of how much of your total energy burn in a day your brain, which makes up two percent of your body weight, uses.

Peter - 30? 20? Not 50.

Nadia - 30 or slightly more?

Peter - Fourty?

[Incorrect buzzer sounds]

Chris - Unfortunately no, it's about 20 percent. About 20 percent of your cardiac output goes to your brain and your cardiac output, the amount of blood your heart pumps, is delivering oxygen and therefore that's a good index for how much of your metabolism a certain tissue accounts for. The brain is your most metabolically hungry organ so about 20 percent of the calories you burn in a day will go up there. If your brains the size of the one that Duncan has in front of him, the model, then maybe not.

But yes a good 400 to 500 calories a day in an adult. So no points for that. Okay.

If you get this one wrong, it's the tiebreaker. If you get this one right, you can clinch it. Duncan and Lívia.

This is tech-yes or tech-no. In other words does it exist or not. Peter, you have to keep quiet.

Q: Does this exist. A talking and listening toilet?

Duncan - I think that probably exists. If not then we should make one. It sounds like a great idea.

Lívia - I just came back from Japan, it sounds like a great idea. Yes.

Duncan - We’re going to say that that exists.

[Correct buzzer sounds]

[Duncan & Lívia Cheering]

Chris - This has been showcased at the Consumer Electronics Conference. Apparently you can converse with the toilet via a smart assistant while you're doing whatever comes naturally to you on the toilet.

Peter - My question is, what is listening to apart from your voice? Do I get a medical diagnosis?

Chris -  I tell you what, though… I've just come back from Western Australia where a lab there are working on a smart toilet. And the idea is that where we used to talk about Farm to Fork, where you look at the food cycle of what's it comes off the farm, it goes down your throat. Now we're talking about paddock to porcelain. They're going to build a smart toilet which will analyse what you dump into it.

And that puts a whole new spin, as I put it to them, of logging onto the Internet. This thing's going to be online and it's going to track exactly what you put down the loo and therefore it can inform your smart fridge in terms of how to manipulate your diet to improve your overall health.

So we have a winner. Give yourselves a round of applause. Duncan and Lívia, you are this week's naked scientist big brain of the Week award winners. Well done. Your score of two out of the three. And you are our losers this week, Peter and Nadia, but don't let that bother you!

The white cliffs of Dover viewed from the sea.

35:26 - Crossing the channel by hoverboard

Inventor Franky Zapata has just achieved this sci-fi feat...

Crossing the channel by hoverboard

In the news recently we’ve heard that the inventor Franky Zapata successfully crossed the Channel between Britain and France using his jet-powered hoverboard. Chris Smith finds out whether techhead Peter Cowley is impressed...

Peter - Were you on the program back at the end of 2017 where we talked about the Richard Browning device from Gravity Industries? I don’t know if you interviewed me or not…

Chris - He had rockets on his hands, didn’t he?

Peter - Hands and feet. So he was doing the same sort of thing. In fact I think using the same gas turbines actually, which are about a foot or so long and about 22 kilograms of thrust with about the same fuel consumption. So he must be pretty disappointed that he's not on the news now because that device was quite difficult to control, if you saw the video a couple of years ago. This one is effectively the same gas turbines I believe, looking at the photographs, just sitting on something that his feet are on. Now the big disadvantage on your hands is the exhaust gas is about 500 degrees centigrade so you don't really want to get it too close to…

Christ - You’d cook your legs!

Peter - I've got shorts on at the moment. Can you imagine that. So the concept is basically the same as it was some time ago but he has managed to get it working properly. Now the actual flight time is about the same. I don’t know if you noticed but Frank, he had to stop halfway, land on a ship, refuel, and take off again. And the reason he failed the week before or whenever it was, was because he missed the ship and landed in the water. So this time he actually managed to refuel, go on, and land then on the cliffs of Dover.

Chris - So how does it work then? He's got a hoverboard which has got the engines, the jet engines, gas turbines strapped onto it. Where's the fuel then? Is he carrying it?

Peter - The fuel’s in the backpack. So he's carrying about 20-odd kilos of fuel, which is only paraffin, so it's effectively gas jet engine fuel.

Chris - Oh my goodness, that’s quite heavy. So if he lands in the sea… how does he stay afloat?

Peter - No he will have landed... well I'm not sure about that, but he will have landed with it empty because he was trying to refuel at that point. Yeah you're right.

Chris - But if you crash into the sea, it’s quite a big weight! You need some buoyancy.

Peter - I don't know. But anyway, still alive. His wife was in tears if you noticed on the news clips.

Chris - I'm not surprised.

Peter - But the important thing is it must have some sort of self-stabilising thing. So if you see him flying through the air, he was going up to 110 miles an hour, 180 kilometres per hour, and he was about this sort of angle, so about 45 degrees, leaning well forward.

Chris - Leaning forward into the wind. So it must take quite a lot of controlling, that. Has he got a trigger or something?

Peter - He has a trigger for control of power I think, on the hand. But he said his own core strength was the most important thing to control himself, because any wind gust, he's having to protect that; unlike the Richard Browning one where he could just move his hands and legs around the place. I mean he would have more control over it than the hoverboard.

Chris - But think you're doing over 100 kilometres…

Peter - Well over 100 miles an hour. Exactly.

Chris - ...and if you hit the water doing that… that’s devastating, isn’t it?

Peter - Yeah. He would have to rotate if he was going to go headfirst into it. But you know these, what's it called... wingsuiting. Have you seen the videos of wingsuiting, going through little holes in rocks?

Chris - Yeah.

Peter - There are people who are actually quite close to not minding if they die. But this guy, he’s achieved something quite special.

Chris - It is amazing. One wonders whether this will become de rigueur in future. This is going to become very much not science fiction anymore, become science fact.

Peter - Yeah. Apparently the reason the military are not that interested in it is because it's too noisy and it takes a lot of training.

Chris - I’m not surprised.

Peter - A lot of dead soldiers potentially getting it wrong.

Pouring cocoa beans into a sack by hand.

What might climate change mean for chocolate?

Nadia Radzman, Cambridge University food security expert, tucked in to this question from James...

Nadia - So climate change affects rainfall and temperature. And then occurrences of drought and flooding. So these environmental changes would affect plant productivity and in terms of cocoa trees this would affect the fruit production. And since the seeds said the ones that we use for chocolate this would affect chocolate production too. So if we look at the major producers of cocoa, they have tropical climates. So changes in rainfall and temperature would affect food production. Sadly, that would reduce chocolate production too.

Chris - Will not some bits of the world's surface become more amenable to growing chocolate? So although some areas won't be so good - Brazil could be in trouble as a big producer, some parts of  Africa - but could other areas become much more propitious for a cacao plant? And then before we know it they become the chocolate Mecca?

Nadia - I'm not so sure about that, because with climate change you also would get a boom of pests and pathogens at different parts of the world too. So that would have also affect the yield of cocoa trees and the other thing that we need to consider is if we look at the farmers that are growing these trees, most of them are small scale farmers. They really need to have high productivity of these trees in order to sustain their livelihood.

Chris - So the bottom line, are we worried about chocolate and climate change?

Nadia - We should be I think.

Chris - So good time to buy Chocolate Cocoa Futures then, the price is going to rocket is that what you’re saying?

Nadia - Or we can do something about it! Do a lot more studies on how to prevent this from happening, and we could also reduce our greenhouse gas emissions.

A white fridge

Why are fridges hard to open once closed?

Cambridge University engineer Lívia Souza lifted the lid on this question from NeilEP from The Naked Scientists forum... 

Lívia - So the idea is the fridge is closed as a container containing cold air inside of it. So you open the door and let's say it's summer outside and all the hot air is going in and the cold air is coming out. And then when you close the door, what happens is this hot air that went in, starts to cool down and then when it happens it decreases the pressure. And then you have a tiny vacuum and takes a while for you to be able to pull it.

Chris - So it's the air that goes in that's warmer and therefore at a higher volume because it's warmer.  Hitting the cold surface inside the fridge and shrinking so the pressure inside the fridge drops. And presumably then if you kept on opening and closing the door as the temperature went up inside the fridge, that effect would go away. And also if you had a fridge that wasn't on it should be much easier to open it.

Lívia- For sure.

Chris -  Is that true? I haven't tested that. That would be the scientific way to approach this. We need to actually do the experiment.

Duncan -  I can confirm that warm fridges can be opened fine. When I moved house there was this bizarre situation, we had multiple fridges and we just used them like cupboards and they were totally easy to open.

Person looking ahead

What visual information does the brain cull?

Neuroscientist Duncan Astle tackled forum user Sazr's question...

Duncan - I think what he's getting at there is that the visual world outside of us, in front of us is incredibly rich and there's an information processing capacity problem. And there’s a couple of ways in which the information is simplified it as it moves through the system. So I’m just going to tell you about two of them. The first one is very early on - so in our retinas the layer at the back of the eyes has lots of photo sensitive receptors but they're very densely packed around a region of the centre called the fovea, and the fovea is only big enough to pick up your thumbnail at arm's length - if everyone sticks their arms out then you'll get a sense that it's actually very small. And so what your eye is doing is, it's moving around the environment very quickly in special type of eye movements called saccades, and it's updating information as it goes. Actually, much of what you perceive is actually slightly out of date from the last time that you made a saccade to that location. So there's lots of information the brain's just filling in the gaps really, from the last time around, but then when it arrives at the brain it's then culled again. And the reason we do that is because it's actually much more strategic to focus all of the resources on the information that's most relevant to the task at hand.

So there's a really nice experiment that someone did where they had participants watch a video of people playing football. And the task for the participants was to count how many times the ball touches someone's foot. Whilst they're watching this - and they're watching very closely and attending very closely to the ball and the foot - on the video someone comes on in a gorilla costume and runs around the pitch and runs up the camera and it turns out that actually very few participants are aware of ever having seen the gorilla. And that's because what their brain essentially is doing is biasing the allocation of resources so heavily to the task at hand - which is the balls and the feet - that it's screening out what it considers to be irrelevant information, in this case the gorilla. So there's lots of culling that goes on.

Chris - Peter?

Peter - Can I ask you how quickly it's rebuilding this image? If it's wandering around, are we talking milliseconds or tens of milliseconds... what happens if a child jumps into the road? Could you have missed it because at some point your brain was actually looking over there, your eyes were looking over there?

Duncan - Yeah. So for instance, one of the reasons why you shouldn't use your mobile phone while driving is because you're devoting your resources elsewhere. So there's what we call top down and bottom up attention. So if there's something that's relevant, like the task the participants were given, then you use top down systems in the brain to drive attention towards location. But you can also get bottom up attention - so if something very salient or surprising happens, then attention can immediately be captured to that location and there's a dynamic interplay between those two drivers.

A few burgers on a table

What's an impossible burger?

What's an impossible burger, and would you eat one?

Nadia - I would definitely eat one. It's a more sustainable and environmentally friendly way to consume burgers because this burger is pretty much a meat mimic. It tastes like meat and it looks like meat, but it's fully made from plant material. And the difference between other meat mimics, what I've been told, is that it has this added hemoglobin.

Chris - So this burger bleeds?

Nadia  - Yes! It has haemoglobin, but not from animals, from plants.

Chris - Because haemoglobin is the stuff in our red blood cells that carries oxygen around the body, it’s got iron it it. And this is why we like eating red meat because it’s good for your iron levels.

Nadia - Yes. So the haemoglobin that is added in this meat to mimic, this impossible burger, is to give that iron taste that we associate with meat. But this particular haemoglobin comes from plants, the gene itself comes from plants.

Chris - Doesn't it come from the nodules that you work on?

Nadia - Exactly, from soya beans.

Chris - Yeah because when you cut those across they do look a red colour don't they? I met a plant scientist who  said “yes that's this leghemoglobin molecule because the bacteria are actually very metabolically active, and they're using a lot of this stuff in order to maintain a high metabolism.

Nadia - So it functions the same way as the haemoglobin in our blood which is to carry oxygen, but in nodules, so when the bacterium is fixing nitrogen, it doesn't like to have a lot of oxygen. So what it does is this "leghaemoglobin", which makes the nodules very pink, is that to get the oxygen away from those bacteria that are fixing nitrogen.

Chris - So it keeps the oxygen away from the bacteria that need to fix the nitrogen?

Nadia - Yep!

Chris -  And so the the impossible burger makers are using this, so you can get genuinely vegan but...

Nadia - yeah -

Chris - ...good way of having iron in this plant-based burger?

Nadia - Yeah.

Chris - Are they any good?

Nadia - I haven't tried one but I have friends who actually already tried one. And she said that if no one told her that it was meat from plants she wouldn't even know.


Energy efficient houses

Engineer Livia Souza built on this question from Jim...

Livia - So typically mineral wool which is a type of material that can trap a little bit of air inside and it's very good for insulation of the house. I just came back from a bio based conference and they were talking about straws as well to be used as insulating material and they seem to be very very good.

Chris - Is this like bales of straw?

Livia - It's a good material. There is a lot of research being done right now to do it. It's a bio based material so the carbon footprint is great. And on top of that, there is a very cool material as well that is just air bubbles around the house that can work for installation as well.

Chris - So you're saying live in a bubble?

Livia - You put the bubble in the wall.  It’s not very good for the wallet though!

Chris - Like bubble wrapping your house? You put an air bubble like a bubble wrap in the cavity between the inside the outside. But we already do that don't we? Don't we don't we fill those cavities with an expanding foam or something which is doing sort of that?

Livia - That's what we called polyurethane that could expand and fill. So basically we're talking about having more air around the house and decreasing the thermal conductivity so to decrease the heat loss. That's the general idea around it.

Chris - And have people like yourselves interested in the materials we're going to use of tomorrow,  and having an eye on the carbon footprint,  has anyone done this sort of calculation to work out what the best way to build a house is now in terms of what sorts of materials to use and what sorts of proportions? Do we know?

Livia - That's the key question. Yes there is a lot of people working on it. What I would say for now is it depends from place your place. Because it depends which are the demands in each place that you build and what are the products around to build the house as well.

Chris - So there is not going to be a generic answer. A house that's good at staying warm in winter is not going to be the same as a house that stays cold in summer, there are going to be differences and we're gonna have to find out how to do that, place to place?

Livia - Yes.


Are smart assistants always listening?

Tech expert Peter Cowley answered Katie's question...

Peter - So in principle we're told smart devices are just listening for so-called “wake words” which could be Siri or Okay Google or Alexa or Amazon etc, and you can prove that. If you switch off the Wi-Fi, you'll find that it wakes up the device and it goes “urgh, what do I do now?”.

So this is because there isn't enough processing power, space capability, to actually do the analysis inside the device. So once woken it will then connect itself to servers somewhere your Amazon servers Apple servers or whatever, which will take the data, work out what you're trying to say and then work out what the answer is. So in principle certainly I'm pretty confident that in general, only when it's woken, will it talk to the servers.

However there is evidence that came out a few months ago that some of the data that is recorded and listened to after it's woken up. I tend to believe that they're not transferring or listening to the data the whole time. So in principle, yes, I would trust them that they're not listening the whole time.


Can you train pain?

Cambridge University neuroscientist Duncan Astle got stuck into Ali's question...

Duncan - It's an interesting question from a kind of basic science perspective, but also from a clinical perspective. One of the big challenges in medicine is trying to manage people's pain. It's very difficult because ultimately there's no way of knowing how much pain the participant or a subject or a patient in the hospital is in.

And so it's very hard to know how much medication they should be given. So there's lots of variability in how sensitive different people are to pain. And one of the big sources of variability is genetic. So the way that this is studied in the lab is they will use something like a heat sensor or a cold presser to create a kind of painful sensation. And we know that variability in heat pain sensitivity, about 26 to 32 percent of that can be attributed to underlying genetic differences, but it's as much as 60 percent for variability in cold presser pain.

Chris - And what are those genes actually doing, to make say you feel a lot more pain for the same stimulus than the me?

Duncan - Those genes could be doing various different things. So there there's a kind of a long pipeline going from the affector - when you receive the sensation of the pain - that travels up to the chord then all the way to the brain and then back out again. And there are multiple steps at which for instance those genes could be coding for different types of receptor, that could be coding for different types of transmitter, or they could be involved in higher level neurobiological systems.

So one source of variability that we know about is that there are areas of the cortex, the outer layer of the brain that's usually we think of as being responsible for the higher order cognitive skills. So areas of the frontal lobe like the insula which is kind of just behind your eyes and also somatosensory cortex, we know that variability in the extent to which people can up-regulate those areas seems to be involved in their ability to regulate pain.

Chris - So it's a bit like high then, in the sense that there are loads and loads of genes that probably determine how tall you get. But it's not gonna be down to one gene alone.

Duncan - Exactly. So the way that we work out these percentages one way that they do is with twin studies. So if you get identical twins and not identical twins, then you know roughly speaking how much shared genetic material those participants have. And from that you can calculate what proportion of the variability is genetic.

But of course it doesn't which genes it is or how many genes it is. There are different types of pain sensation and they seem to have different types of genetic susceptibility. And that implies that there are underlying the system physiologically distinct different pain systems. Some of them might be more genetic than others. And so for instance gender is an important predictor of pain. So people who are male have slightly higher pain tolerances than female. It's about 8 percent for heat pain but much larger for cold presser pain.

The fact that variability in the extent to which you can up-regulate these higher order almost cognitive areas of the brain, the fact that that will modulate your pain sensation, implies that it is to some degree trainable. And we know that there are all sorts of different interventions like practicing meditation for example. And people who are experts in meditating do claim that it helps them to moderate their experience of pain. And so for instance there are people who practice different types of meditation prior to childbirth.




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