Q&A: Deadly Lasers and Delicious Brains

How many calories are in a human brain? And what would happen if our planet stopped rotating?
20 September 2022
Presented by Chris Smith
Production by Will Tingle.

BRAIN

A brain sparking with electricity.

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This week, it is time to put your questions to a panel of excellent experts in one of our Q&A shows! We are going to be investigating if truth serum really exists, what would happen if the Earth stopped rotating, and just how much nutrition is there in the human brain? Plus, we have a science quiz based on today in history and going back to school. See how you fare against our experts...

In this episode

A microphone and mixing desk

01:04 - Meet the panel!

We introduce the band of scientists here to answer all your questions...

Meet the panel!
Jonathan Reisman & Kathryn Harkup & Risa Bagwandin & Peter Haynes

Before we start crunching through conundrums, let’s meet this week’s panel, Kathryn Harkup, Jonathan Reisman, Risa Bagwandin and Peter Haynes...

Chris - First up, we have chemist and author Kathryn Harkup. Her latest book is called 'Super Spy Science: Science, Death, and Tech in the World of James Bond' and it focuses on the science and technology involved in that world famous super spy series. She's also written on the subject of poisons that have been used in fiction, such as those featured in Agatha Christie and Shakespeare and I have to ask you this, obviously. Kathryn, what is your number one James Bond gadget?

Kathryn - I always lean towards the villainous side and I think my favourite gadget has to be Rosa Klebb's poison tipped shoes. Genius.

Chris - How does it work?

Kathryn - It's very simple. It's just like a button release: you get this very sharp stabby thing turn up at the end of your shoe. And then of course you lace it with something that will kill you allegedly in 12 seconds. I doubt there's a poison that will do that, but I'm afraid that the henchman who gets kicked with it is as good as dead because they're not helping him.

Chris - Something similar happened with risin in an umbrella though, didn't it?

Kathryn - Yes. There was a famous murder in London on Waterloo bridge that was allegedly a poison filled pellet that was fired into a man's thigh, Georgi Markov's thigh, an adapted umbrella. I'm not sure the umbrella bit is true, but he certainly was poisoned with ricin and it took him three horrible days to die. Not quite the 12 seconds that Spectre manages.

Chris - What came first, Ian Fleming doing this with the shoe or the umbrella?

Kathryn - No, Ian Fleming got there first. I don't know if anyone was picking up tips, literally. Though, there has always been the idea of poison tipped weapons. There is nothing new to that. There's arrows have been laced with all sorts of nasty since time immemorial just to kill off various animals for food. So I don't think Fleming can be held responsible in any way for informing on Georgi Markov's death.

Chris - One of the things you wrote in the book that I must admit I was amazed by was you were describing - I can't remember exactly which film it was - it's where James Bond is swimming underwater, using that amazing thing he plugs into his mouth. And you say in the book that one of the spy services rang up the producers to find out how they did it.

Kathryn - That's true. That is how the story goes. Apparently some secret service agency had been interested in developing something similar because it has obvious uses in the secret services. And so they were fascinated, like they'd cracked the problem that they'd been tackling. And so they got in touch with the producers and the producers had to confess that this device that you see on screen was actually two soda syphon capsules glued together, and the actors were holding their breath.

Chris - So it doesn't work after all.

Kathryn - Well, it does. Now, this is one of those weird things I do wonder if someone has watched a James Bond film and thought, you know what, that's what the world needs. You can now buy rebreathers. They don't quite work the way they're described in the films. They kind of filter oxygen from the surrounding water a bit like fish gills. And it will give you some oxygen whilst you are underwater. So I do wonder if Bond has inspired a rather cool gadget.

Chris - Are they not huge?

Kathryn - They are bigger than the soda syphon capsules, admittedly, but they're still quite small. It's not like swimming around with a huge tank on your back.

Chris - Thanks, Kathryn. I'm amazed.

Chris - Well, next up, we've got physician and author Jonathan Reisman with us. Jonathan's got a great deal of information to impart about internal organs, everything ranging from inspecting them through to eating them. You can learn about that from his book, which is The Unseen Body, that delves inside our insides and navigates its way through the wonders of our internal systems. Jonathan, you say in your book that the throat is foolishly designed. Why?

Jonathan - As we all know, when things go into the back of the throat they can either be swallowed down the oesophagus into the stomach, which is certainly the route that all food and drink and saliva and whatever else we're swallowing should take. There's another route for air to go through the windpipe or trachea into the lungs. And if anything that should be swallowed, such as food or drink or saliva, gets into that airway, one small slip up and you can die or become gravely ill. And yet those two entrances for air and for everything else are right next to each other with just a few millimetres separating them. And every time we swallow the material that we're swallowing comes within a hair's breadth of going down the wrong pipe and killing us. So it seems less than ideal design though it does work and we swallow daily for decades without dying. So that's good.

Chris - Well sitting alongside Jonathan, we've got Risa Bagwandin. Now, Risa's a PhD student. She's studying Chemical Biology at the University of Cape Town. She's focusing on the diagnosis of tuberculosis. It's pretty special, actually, that you're here. So why don't you tell us how you came to be here?

Risa - So I met Dr Chris Smith in Durban, South Africa at a conference called BIO African Convention in 2019. It so happened that the conference organisers along with Chris presented a science communication fellowship award, which was awarded to the best science communicator. You had to attend a science communication workshop and present in front of a large audience that was attended by ministers.

Chris - Well, we thought we needed a good test. So we gave the three fine finalists at the workshop the challenge: they had to stand up at the conference dinner in front of a thousand people and tell them in three minutes what they were working on. And as Risa says, there was the minister for health there and a few other high level dignitaries. Congratulations.

Kathryn - Seriously, that takes some doing.

Chris - And so they thought she did a jolly good job and, even better, the South African government agreed to pay to send her here. So we are very privileged to have you with us for about eight weeks. And so we thought given we've got a big chemical brain in the room, we would use it this week. Sitting next to Risa is Peter Haynes. Now Peter's a mathematician and you work on the climate. What are the challenges that people like you are trying to solve? Having got weather forecasts that work rather well, what are the unknowns or the less good at bits that we are trying to improve on?

Peter - Well, of course, weather forecasting is only part of the story, right? And one of the challenges we face is thinking about climate change, how things will change on a longer time scale. We're not talking about individual weather events. We're talking about whether the weather will be systematic, warmer, or wetter, or colder for a year or a decade. The fact is that the weather and climate are determined by a whole set of complicated processes and whilst our models and the way we do those sums, those calculations, have improved a lot, they can still be improved further, and also they can take into account more observations. So we've got many new observations of the atmosphere from satellites and radar, and also all of these things can be exploited. So it's a continuous 'can do better'. A must do better kind of topic.

Chris  - Was it Neils Bohr who said "Prediction is always difficult, especially when it concerns the future."

Peter - Exactly. That's right.

Chris - So anything mathematical and possibly weather related, that's all coming your way!

Green comedy chattering teeth

08:31 - Can a trip to the dentist impact on hearing?

The surprising connections between very different parts of the body...

Can a trip to the dentist impact on hearing?
Jonathan Reisman

Chris - The human body is a mass of interconnected systems and feedback loops. And some people may be surprised by which areas of the body have influence over others. Jonathan Reisman, Liz asks: is it true that getting your teeth removed, via dental surgery or otherwise, can lead to hearing loss?

Jonathan - That is a fairly well known phenomenon. According to my understanding, it is a very rare occurrence. You can find reports in the literature about people who lost hearing on one side partially or completely after a dental procedure, but it's rare enough that if it happens, a dentist is likely to write about it in the medical literature as a rare event.

Chris - Do we know what the mechanism might be? Why would a person having some kind of dental intervention go deaf?

Jonathan - So it's actually hotly debated or not that hotly because it's so rare. There's some theories that perhaps the adrenaline or epinephrine, which is often in the local anaesthetic that's injected into the area of the teeth, might seep through to nearby arteries that feed the hearing mechanism and the nerves feeding the hearing mechanism. And perhaps this causes those blood vessels to shrink down or spasm and stop blood flow to the organs, perhaps damaging them through lack of blood flow. There's another theory, actually, that just the sound of the dental equipment, the drills and other things, which can be quite loud and can be quite close to one of your ears, perhaps that sound alone is causing some damage to the hearing organs. Another theory I came across, perhaps the odd positions you're asked to put your neck into, and how widely you open your jaw and for a prolonged period of time during the procedure, perhaps also smooshes some blood vessels shut that should be feeding the hearing organ and it's neural component.

Chris - So one thing Liz probably can't do, if she's worried about hearing damage from the drill, is to wear ear plugs because presumably the vibrations are going to go straight through the bone and into her brain anyway.

Jonathan - True. You'll save damage to the eardrum and the outer parts of the ear, but you can still sustain neural damage to your hearing mechanism. Also, the dentist will probably want to talk to you saying "open wider, stop moving" et cetera. So you should hear those things.

Chris - So probably not a sound and valid reason not to go to the dentist, Liz, on the grounds that you might lose your hearing. Probably unlikely to happen.

A picture of someone talking, drawn on a blackboard

10:59 - Could truth serum really exist?

The chemical that could alter your ability to tell lies...

Could truth serum really exist?
Kathryn Harkup

Kathryn Harkup, aside from your latest venture into the world of James Bond, you have also written books on some of the prominent serums and chemicals found in popular culture. One of the more commonly touted examples found in the spy genre is the ‘truth serum’, a mystery substance capable of loosening anyone’s tongue. But Kathryn, is there actually such a thing as a truth serum, such as sodium pentothal? If so, then how does it work?

Chris - Kathryn, let's come back to you, author of Super Spy Science and the world of James Bond. You've also written books on some prominent serums and chemicals that are found in popular culture. One of the common ones in the spy genre is truth serum, a mystery substance capable of loosening tongues, but is there such a thing? And if so, what is it, how does it work?

Kathryn - I think a lot of people have tried to develop truth serums. It would be extremely useful in questioning if you just know whatever was coming out of someone's mouth was the absolute unadulterated truth. And I think the idea behind a lot of these serums or compounds was that it would relax your inhibitions. So you would talk more freely perhaps a bit like if you're under the influence of alcohol. So in which case you might as well get your interrogatee drunk as opposed to giving them sodium pentothal or whatever drug. For a long time, sodium pentothal was used, allegedly, as a truth serum, basically because it would lower inhibitions, but you could just be talking like a drunk person: the first piece of nonsense that comes into your head. So if it's reliably truth or not, I don't know. As far as I know, there's no real truth serum out there, but of course they wouldn't tell me if there was.

Chris - You should give them some truth serum then!

flooded road

What's the impact of rising sea levels?
Peter Haynes, University of Cambridge

As the floods in Pakistan are highlighting, climate change is set to alter the distribution of water across our planet in a dramatic way. One of the most widely covered aspects of this is rising sea levels. Peter Haynes, the news that sea levels are projected to rise, in the US, by 30cm in the next 30 years doesn’t seem that much. Why is it such a problem?

Chris - Peter, let's cross over to you. We've all seen the footage of what's happened to Pakistan. Climate change has had the finger pointed at it for what's happened there with flooding. Other countries as well are seeing very dramatic shifts in weather and our own country, the UK, we've seen a very radical departure from what we regard as normal summer temperatures this year and in recent years. So let's just consider climate change for a minute. One of the things that people often talk about in the context of climate change is what will happen to sea levels. And some of the predictions are only about 30 centimetres of sea level rise in the next 30 years. This question says, why is only 30 centimetres in 30 years such a problem?

Peter - I think the key thing here is that whilst sea level rise of a foot doesn't seem to mean very much if you're on the beach or something, right, we have to think of this in the context of severe extreme events and any systematic rise in sea level is going to increase the likelihood and the frequency of extreme flooding events. So it's not so much the fact that the average by itself has gone up. It's the fact that those high water events, the times for example when tides and the weather reinforce each other, those leading to dangerous levels of water rise are going to become more frequent.

Chris - A lot of people also point to Antarctica. And the fact that if that melts that's going to have a really significant impact, and Greenland of course, because that's ice that's not already in the water and so it's not floating and it will therefore directly contribute to a sea level rise, unlike the Arctic where the ice is already displacing water. So if that melts, the water just redistributes, but it doesn't actually mean there's a change in sea level rise.

Peter - That's right. It's the melting of ice on land that will have the most severe implications. Just in the last week or so, I think I read a newspaper headline the other day that it was going to be inevitable that the Greenland ice cap was going to be lost to a large extent. But I think another point to think about here is that melting of ice caps isn't the only effect that's going to give sea level rise. Also, just the fact that water expands when you heat it up is going to make an effect, right? So these things have to be considered together. There will inevitably be sea level rise, whatever happens to the Antarctic ice shelf or Greenland in the next 50 years, simply because of thermal expansion.

Kathryn Harkup - Something I was going to ask also about once all of this ice disappears from the land surface, do we know what is underneath that that's been trapped in? I've heard stories of methane gases that would be released after thaws and so on. So is there any concern about once the ice is gone what is left behind?

Peter - Certainly there is methane trapped in the sea bed. Increases in temperature and melting will potentially release it. Methane is a greenhouse gas, it traps radiation near the earth's surface, it'll increase the overall temperature. There are subtle differences with the way it works from carbon dioxide. Another effect that I could mention is this idea of what scientists called albedo, which is reflecting radiation. This is relevant actually to mountain glaciers as well as to the Arctic sea ice. Currently, where you have ice, you're reflecting radiation back so you don't get so much heating as soon as you remove the ice. And actually another effect here is having soot on the ice, for example, which might come from wildfires and things, particularly in mountain areas, that reduces the reflectivity which means you get more radiation absorbed and more warming. So there are quite a few different feedback effects that might have to be considered as important.

Chris - And albedo is quite different from libido...

sun shining through a window with flowers in a vase

16:57 - Is glass a solid?

The strange chemistry of this everyday material

Is glass a solid?

Risa Bagwandin answered this question...

Risa - Well, when we hold an object made out of glass, we naturally would think that it's a solid material. However, it's not a true solid for something to be a solid, it needs to have atoms which are audited and that remain fixed in place. Glass is unique in the sense that it has properties of both liquid and solid. It has atoms that are in an ordered structure, but these atoms move rather than remaining fixed in position. So the movements of atoms relative to each other is one of the properties that we know that characterises liquid states.

Chris - There's a claim that if you look at old windows, the glass at the bottom of the frame is thicker than at the top. And people will say, "oh, that's because the glass is a liquid and it's flowed downhill over time. Is that true or false?

Risa - Well, that is false. So the reason why the glass is thicker at the bottom is just because of the placement of the glass on the window pane. So normally when you have a thicker surface at the bottom, it'll be more rigid and be able to be fixed in place securely. In fact, quoting The New Scientist, it would take a billion years for just a few atoms in a pane of glass to shift at all.

Chris - So there you go, Katie.

Cow in a farm

18:26 - Can Brucellosis cross between species?

Bruce asks whether there might be any connection between the miscarriages in his family and their farm animals

Can Brucellosis cross between species?

Jonathan Reisman answered this question...

Jonathan - I think that acute brucellosis infection - that is, infection with bacteria in the genus brucell - is known to cause miscarriage, especially in animals. It's one of the most common causes, infectious causes, of miscarriage. And it does seem to also, with acute infection, cause a miscarriage in a high number of women. I saw some studies that have just under 50% of women with acute brucellosis for a miscarriage. I think that outside the context of an acute infection with fever, that's harder to say there are some chronic brucellosis infections that can be smouldering over years. I don't think it's as clear that they cause miscarriage at all, so I doubt if there's any symptoms of any kind or there's any acute infection with fever, probably not related to those miscarriages that seem to run in the family. There are many other things that can cause miscarriage for it to run in families, such as clotting disorders, but I doubt it's chronic brucellosis as the cause.

Chris - Thank you for clearing up Bruce's problem anyway.

Quiz

19:58 - Quiz!

Our teams of scientists are pitted against one another...

Quiz!

It is that time in the show where we put our experts' knowledge to the test with a quiz.

Team 1 are going to be Kathryn Harkup and Jonathan Reisman

And team 2 are Risa Bagwandin and Peter Haynes. 

You are actively encouraged to confer between you.

Chris - Round one is called 'On this day in history'. So Kathryn and Jonathan, question one. September the 15th, a date that echoes through history, on this day, the 15th of September, 187 years ago, Charles Darwin first landed in the Galapagos Islands, would you believe. He was best known for having his big beard and bad handwriting, as well as having some pretty important theories to impart. He was though also an avid collector of which group of invertebrates? I've got three options for you: A) Ants B) Beetles or C) Butterflies. So Jonathan and Kathryn, Darwin had a penchant for collecting what group of invertebrates?

Kathryn - Are there interesting beetles in and about his home, or was he collecting them in the Galapagos? I don't know what the beetle population of the UK is, and how exciting it is and whether it's worthy of collecting

Chris - Jonathan?

Jonathan - I do know that beetle diversity across the world is quite staggering and surprising, so I might go for that answer.

Chris - It's a good choice. It is answer B - beetles. Darwin was a huge collector of beetles and his collection of thousands of them from the Beagle voyage is in the Natural History Museum in London. Well done, plus one to team one so far, I shall mark you up as one point. Question two, this is going to Risa and Peter. September the 15th, 1928 is also an important date because it's the date on which Alexander Fleming discovered the effect of a pretty important mold that turned out to be world changing. But how many lives do we estimate penicillin, that came from that mold, has since saved since it was rolled out in 1942. So Risa and Peter, penicillin - how many lives saved since A) 20 million B) 200 million C) 2 billion lives saved? What do you think?

Risa - Well, if we take the approximation that there's 6 billion people on the planet. But In a lifetime...

Peter - Well, your comment about how many people on the planet has made me think actually 2 billion is too many. So perhaps we go over 200 million.

Risa - Mm I'm thinking 200 million.

Peter - Okay. Let's go for that.

Risa - Okay.

Chris - It's a good one to go for. It is 200 million because that's about two and a half million lives a year that gets saved from diseases like meningitis and pneumonia. So it is one point a piece level, pegging after round one. Back to our team number one, Katherine and Jonathan. Your question in round two, which is 'close family and neighbours'. The first animal to orbit the earth was A) a mouse B) a dog or C) a pig. What do you think?

Kathryn - Oh, I'm pretty sure both a mouse and a dog have been sent into space. I'm not sure a pig has, I missed that particular news item if it was sent into space, but I don't know whether a mouse or a dog went first.

Jonathan - I do know that the Russians sent up a dog named Laika

Kathryn - Yeah. I don't know if they did any experiments before with smaller animals. I imagine the weight would've been an advantage when launching something into space, but I'm happy to go with a dog because I've definitely heard of Laika and going into space.

Chris - Yeah. With that, Jonathan?

Jonathan - Sure. Let's go with Laika.

Chris - It's a good one to go with. You're quite right. Laika was the first animal in orbit. It was on 'Sputnik 2', November, 1957. She was part of the Soviet space dog program. And the half-ton Sputnik 2 satellite unfortunately didn't have a very good life support system on it though. So she didn't live very long, but she did live long enough to be the first animal to orbit the Earth. And then she burned up in 1958 when the satellite was returned to Earth. Well done, it's a point for you. Over to team two. This is Peter and Risa and we're gonna stay in space with this one. Our galaxy is the Milky way. It's one of billions of galaxies that spread out across the universe, but who is our nearest neighboring galaxy? Who's our nearest neighboring galaxy? Is it the Andromeda galaxy, Canis Major or the Tadpole galaxy?

Risa - I have no idea. This is something that I've not paid much attention to.

Peter - There was a nice exhibit in Cambridge a few weeks ago of planets along the river, but unfortunately it didn't get to galaxies. Cause if they put galaxy in it, I might have known the answer. I mean, Tadpole seems very unlikely to me.

Risa - I agree

Peter - What was the first one?

Chris - Andromeda, Canis Major, or the Tadpole galaxy?

Peter - Go for the middle one?

Risa - Is that what we're going for? We'll just go with the one in the middle, like in multiple question quiz sheets.

Peter - Perhaps just go for tadpole because it's unlikely.

Chris - Going to have to hurry you, what do you think? What are you gonna go for?

Risa - We'll go with B since that's our default now.

Chris - Okay. You're going for your default answer. And it's the right thing to do. It is Canis Major. Now the Tadpole galaxy does it really exist because it looks like a tadpole. It's 420 million light years away, that's a long way off. Andromeda, two and a half million light years away. That was thought to be our nearest neighbour until very recently actually. But Canis Major now has the crown. It's actually a thousand times closer than Andromeda, 25,000 light years away. It's our nearest galactic neighbour but is still a long way off though, because even our fastest spacecraft, which is the Parker Solar probe would take a mere 39 million years to get there. So that's a point for you too. So level pegging at the end of round two, we might be in tiebreaker territory. Let's find out. Round three is called back to school and it's GCSE time. So schools have all gone back recently, the GCSE results, which we sit here in the UK, are not far in the past. So time to see how you would fare at GCSE. We want to know team one. This is Catherine and Jonathan. What is hotter? A) the boiling point of iron B) a lightning bolt or C) the surface of the sun. What's hotter?

Kathryn - So for me, I think it's between the surface of the sun and a lightning bolt. I'm gonna discount iron because I think that's... Although boiling point though that's...

Chris - I was crafty there. Wasn't I?

Kathryn That was crafty. See if you said melting point, I'd have dismissed it out of hand, but boiling point. Mm.

Chris - Yeah. See, I knew you were coming on the program and I thought 'chemist, she's gonna know that, I'm gonna be crafty.'

Kathryn - It's almost like you planned it.

Chris - I did. <laugh> Jonathan. Any thoughts?

Jonathan - I agree, Kathryn, that I'm a little perplexed because they're all certainly very hot. Could anything on earth be hotter than the surface of the sun? I wonder...

Kathryn - I think it's one of those deceptive questions where the surface of the sun, everyone imagines, it's going to be super, super hot, but actually it's not as hot as some lots of other things. For example, a lightning bolt. That would be my gut reaction is a lightning bolt

Chris - Going for that one?

Jonathan - I'll back you up on that one, Kathryn

Kathryn - Oh, bless you.

Chris - It's a good choice. It is a lightning bolt. Let me tell you about iron. You were quite right with iron. 1500 degrees Celcius is the melting point, give or take. The boiling point, craftily, is 2,800 C. I did that on purpose. The sun's surface is 5,000 degrees Celcius. Lightning super heats the air around it to a sizzling 30,000 degrees Celcius. So it's about six times hotter than the surface of the sun. Well done. So you get a point for that one as well. You gotta get this one right team two, Risa and Peter, because at the moment they've got a full house. We're over to biology for you two and we want to know how many bones are there in a great white shark. Is it 0, 536, or 2,804? 0, 536 or 2,804 in your average great white?

Risa - Any thoughts?

Peter - Well, the non marine biologist in me has this vague idea that sharks don't have bones. They have some other kind of solid material in them. But I could be distracted because Kathryn has just made a gesture at me, which is interesting.

Chris - She was trying to put the opposition off.

Kathryn - I'm trying to make it fair competition. I want the best out of everyone.

Risa - I'm gonna go with with Peter here

Chris - Which is?

Peter - Which is zero.

Chris - Peter's going zero. Answer A), you're breaking with your tradition. You went B every time.

Peter - Yeah. I mean, that was a tough decision

Chris - I can't tempt you with 536?

Risa - No, no.

Chris - It's a good choice because it's not right. A is the correct answer. Sharks are cartilaginous fish so they are not bony. There are no bones in a great white shark, well done. So that means it's tiebreaker time because you have all got a hundred percent so far. So the tiebreaker is: how are your Nobel prizes? How are you on Nobels? Are you good at Nobels? We'll find out. We want to know what year the Nobel prizes were first awarded. Jonathan's down the line so I'm gonna ask him to start. So Jonathan, what year do you think the Nobels first started? You're not allowed to click quickly flick out your phone and go looking at this either.

Jonathan - Of course not. I may be close or very, very wrong. I'll go with 1938.

Chris - Okay. 1938. Kathryn. Any thoughts?

Kathryn:
I'm gonna go much earlier than that because I think it's 190-something. I'm going to guess 1904.

Chris - Karthryn goes 1904. Peter?

Peter - I'd go a bit earlier. I'd go for 1895.

Chris - 1895. Risa?

Risa - I have to admit, I know this one. So I've been following the Nobel prize winners for quite some time. So the first noble prize was awarded in 1901

Chris - And you are right. So our Naked Scientists 'big brain of the week' award goes to Risa and Peter. Very well done. I think we should give them a round of applause for that one!

A bottle marked with a skull and crossbones, and the word poison, containing a dark purple liquid

31:02 - Could a poison tipped ring work?

The feasibility of weapons that you can wear...

Could a poison tipped ring work?

Kathryn Harkup answered this question...

Kathryn - It's very simple. It's just like a button release: you get this very sharp stabby thing turn up at the end of your shoe. And then of course you lace it with something that will kill you allegedly in 12 seconds. I doubt there's a poison that will do that, but I'm afraid that the henchman who gets kicked with it is as good as dead because they're not helping him.

Chris - Something similar happened with risin in an umbrella though, didn't it?

Kathryn - Yes. There was a famous murder in London on Waterloo bridge that was allegedly a poison filled pellet that was fired into a man's thigh, Georgi Markov's thigh, an adapted umbrella. I'm not sure the umbrella bit is true, but he certainly was poisoned with ricin and it took him three horrible days to die. Not quite the 12 seconds that Spectre manages.

Chris - What came first, Ian Fleming doing this with the shoe or the umbrella?

Kathryn - No, Ian Fleming got there first. I don't know if anyone was picking up tips, literally. Though, there has always been the idea of poison tipped weapons. There is nothing new to that. There's arrows have been laced with all sorts of nasty since time immemorial just to kill off various animals for food. So I don't think Fleming can be held responsible in any way for informing on Georgi Markov's death.

Chris - One of the things you wrote in the book that I must admit I was amazed by was you were describing - I can't remember exactly which film it was - it's where James Bond is swimming underwater, using that amazing thing he plugs into his mouth. And you say in the book that one of the spy services rang up the producers to find out how they did it.

Kathryn - That's true. That is how the story goes. Apparently some secret service agency had been interested in developing something similar because it has obvious uses in the secret services. And so they were fascinated, like they'd cracked the problem that they'd been tackling. And so they got in touch with the producers and the producers had to confess that this device that you see on screen was actually two soda syphon capsules glued together, and the actors were holding their breath.

Chris - So it doesn't work after all.

Kathryn - Well, it does. Now, this is one of those weird things I do wonder if someone has watched a James Bond film and thought, you know what, that's what the world needs. You can now buy rebreathers. They don't quite work the way they're described in the films. They kind of filter oxygen from the surrounding water a bit like fish gills. And it will give you some oxygen whilst you are underwater. So I do wonder if Bond has inspired a rather cool gadget.

Chris - Are they not huge?

Kathryn - They are bigger than the soda syphon capsules, admittedly, but they're still quite small. It's not like swimming around with a huge tank on your back.

Chris - Thanks, Kathryn. I'm amazed.

The Arctic Ocean

33:06 - Will melting ice affect ocean salinity?

The effects of climate change on the makeup of our oceans

Will melting ice affect ocean salinity?

Chris - Peter Haynes, when ice melts, it's adding fresh water to the ocean. So does this mean that progressively,as we go through climate change and so on, that the salinity of the world's oceans will change...do we think?

Peter - As always, there's a kind of complicated answer. Because actually, what we expect is that some parts of the ocean will get more saline and some parts will get fresher. I mean, the fact is that climate change is associated not only with more melting of ice, but also more evaporation. So where you've got water flowing out from melting ice sheets, the ocean will come fresher. Where you've got some more evaporation, like in the Mediterranean for example, then the water will get saltier. And of course, if you go to some point in the ocean, what you see is some subtle combination or of all of those processes that are taking place over the globe. And then, the effects are brought by the circulation to the place where you are looking.

Chris - When you add fresh water to saltwater, because they're different densities, that can have effects, can't it? Because I've seen quite a lot of speculation about the impact of the Gulf Stream and the melting of the Arctic pushing that backwards, and potentially making Britain colder through global warming because we lose that heat source that comes up the west coast.

Peter - Exactly that's right. At the moment, you get something called convection where heavy water, dense water sinks in the North Atlantic and Arctic ocean, and that happens in part because of salinity, which adds to the density. And if you were to kind of flood the top of the ocean with fresher water, then that combination of temperature and salinity, that determines density, may no longer give to sinking. Some part of the circulation system of the Atlantic is driven by this process. So there would be potentially a change, but I think the jury is still out on how likely it is to happen. Another question would be when would it happen? There's a lot of discussion written about tipping points. I mean, that's another favorite idea in climate science at the moment. If you look at the list of tipping points, this is one which is sort of somewhat lower down the list. It's an effect which could happen, obviously would be potentially serious, but it's not one of the ones that is seen most imminent.

Chris - Thank you, Peter.

Brain schematic

35:27 - What is the brain-gut connection?

Is there a second brain located in our stomach?

What is the brain-gut connection?

Jonathan Reisman answered this...

Jonathan - Great question. There is an entire nervous system of the gut of the elementary canal — it's called the enteric nervous system. And in some ways it, it does operate semi-autonomously from our primary nervous system (the brain spinal cords coming from there). The nervous system of the gut, the entire nervous system helps control the gut: motility helps push food forward through peristalsis, helps impact blood flow to various parts of the tract, helps regulate also the endocrine function of the elementary canal. There's quite a lot of hormones that are secreted to impact its function and timing and things like that.There's also immune function in the gut itself since the external world, through the food that we eat presents a lot of microbes that can hurt us.

Jonathan - So there's a good, strong immune system also regulated by this entire nervous system. Our central nervous system does impact and regulate the entire nervous system mainly through the vagus nerve, which comes down from the brain stem and impacts the elementary canal function. But even if you sever that nerve, even if you completely separate the entire nervous system from the body's primary nervous system, it continues to function largely on its own. Not completely, but mostly on its own. It seems like a good, backup system to have that can function mostly on its own and keep you alive despite severing that connection.

Chris - So when people talk about gut instinct, they're not wrong,

Jonathan - They're not wrong, though that's one of the anatomical metaphors that we use throughout our language. But, it does make some sense.

Smoke emissions and air pollution from an industrial landscape.

37:16 - What is the most problematic greenhouse gas?

Is releasing methane into the atmosphere more harmful than CO2?

What is the most problematic greenhouse gas?

Kathryn Harkup and Peter Haynes answered this question...

Chris - Kathryn, let's come back to you. We've heard from Phoebe who has written to us to say, " I've read that methane is a worse greenhouse gas than carbon dioxide, but why is this? Is that something to do with its molecular structure?"

Kathryn - To be honest, that would be a question for a climate scientist. There are chemical differences between methane and carbon dioxide. Methane is rather more inert than carbon dioxide, but depending on the circumstances, however, the atmosphere is a very different environment and there are all sorts of things going on in that environment that are very different to down on the ground. So what is going on with methane and carbon dioxide? I think Peter would actually be in a better position to answer.

Peter - The common feature of these two gases is that the molecules there is sort of several atoms. There's three atoms in carbon dioxide, there are five in methane. And, that means that they can vibrate at frequencies, which are relevant to absorbing infrared radiation, absorbing heat radiation. So they can both absorb radiation and also re-emmit it. It's those sorts of differences that determine how effective the greenhouse gas is. There are also other effects, like for example, what are called "window effects". That if something absorbs in a wavelength, which other molecules don't absorb in, it's overall effect can be more powerful than you can ever thought. So these things can be weighed against each other.

Chris - So if I've got a whole heap of methane, is my best option then to set fire to it? Because it will be better for the environment to do that than to leave it as methane in the atmosphere.

Peter - I would say almost certainly not. Right, <laugh> , there's something which we talk about as a "lifetime" . If I put a molecule of carbon dioxide in the atmosphere, then it stays in the atmosphere for hundreds or thousands of years until they're probably absorbed by sort of geological processes. Actually, if I've got met into the atmosphere, there are chemical processes that break it down. So all of those things have to be taken into account when you are sort of comparing the merits or demerits of different molecules.

Chris - So short term yes. Long term, probably not then. Yeah. That's right. Yep. Thank you for that.

A woman thinking.

38:54 - Where are memories stored?

Why you might be able to recall certain things only at certain times...

Where are memories stored?

Jonathan Reisman answered this question...

Jonathan - Well, good to always start out by pointing out that our knowledge is very incomplete on the science of memory, as with most things in the brain. I think it's safe to say that the brain has no equivalent of a gallbladder that stores bile or a bladder that stores urine. There's no sack of memories up there that can be located upon dissecting the brain. But I think some things we do know about memory and how it's stored, is that the brain, like many other aspects of its function, including consciousness and subjective experience is not all in one location, but rather spread out in a number of parts of the brain. It's quite a geographic and distributed process. But, we certainly know that different aspects of memory are operated upon in certain parts of the brain.

For instance, on the inside of both of your ears and the temporal lobe, is an important part of how short-term memories are made into long-term memories (in structures such as the hippocampus that are in there). But we also know that if you have a particular memory, the emotion associated with that memory is stored in another part, called the amygdala (another part of deep in the brain). So that's different than the actual facts of the memory: the place, the person, even let's say someone's face you remember. The long-term memory of that image is that it seems stored in the visual cortex (in the back part of the brain and the occipital lobe). Where other facts about that memory or emotion tied to that face, will be stored in other parts of the brain. So it's all very broken down and certainly complex. And how a neuron actually stores memory? I don't believe is really well-known at this point.

A solitaire diamond ring

41:07 - What makes diamonds so hard?

The chemistry behind one of the world's strongest substances...

What makes diamonds so hard?

Kathryn Harkup answered this question...

Kathryn - Diamonds are very special. It is a unique combination of carbon atoms, in that every carbon atom within a diamond is connected to four others. And those four, are connected to four others. So a single diamond on a ring is in theory, one molecule of carbon, which is quite an extraordinary thought. You don't normally expect to see a molecule of something, but that's the kind of scale it's operating on. And all of this interconnectedness means that it is very difficult to chip off a bit of carbon, which gives it its strength. This arrangement also gives it its beautiful clarity and its lustre and reflects light. A lot of what we attribute and what we love about diamonds, is their visual impact and their cultural associations rather than their physical properties.

Chris - Where do they come from?

Kathryn - They come from very, very deep within the Earth. So they were formed many millions of years ago. And the only reason they ever make it to the surface was if many, many hundreds of thousands of years ago, a volcano happened to push through this particular bed of rocks. So, if the temperature wasn't too high the pressure wasn't too crazy and in flux, as it shifted right up to the surface of the earth that it destroyed the diamonds, then you might find diamond deposits on the surface of the earth. So they come from deep, deep, within the earth surface. They're very, very old, but of course you could just make some in the lab these days.

Chris - One thing I've always wondered. And, this sounds like a bit of a daft question, but it's a genuine, straight-up question. If diamonds are the hardest thing, what do you cut them with?

Kathryn - Other diamonds. So it's a real skill, cutting diamonds. The people that do it, they are artists, they train for a long time. And so you find that, because the crystals that you dig out the ground are not perfect. These are natural substances. They all have flaws. They will have cracks in them that you can take advantage of, but also you want to avoid in the finished product. So spotting where all of those flaws are that you can use and manipulate and shape and cut into another diamond, using a diamond, it's all very difficult and lots of planning goes into it. Because huge amounts of money can be lost if you make the wrong cut.

Chris - I can imagine. That's fascinating. Thank you for that. Peter Haynes?

Peter Haynes - Well, I'm interested in this idea of diamonds, right? So do you get anything like diamonds but made of other elements? You've said that a diamond is like a single large molecule of carbon. Do you find other single large molecules of other elements?

Kathryn - You can get single crystals of metals that are highly, highly, organised and grown in specific ways. They use it a lot for engineering purposes, because in theory there are no flaws within this metal. So there's no source of cracks and they're very hard wearing.

Chris - Are they called metallic glasses? I did meet a material scientist who told me that they're great for golf clubs.

Kathryn Haynes - Wow. They must be expensive. I've heard them being used in like jet engines for the blades of a jet, because obviously they're under an awful lot of pressure and they have a lot thrown at them. So yes, they won't look as beautiful and clear as diamonds simply because they're metals and the electronic structure within is very different. But yes, in theory, you can have not specific diamond structures, but highly organised, massive single molecules of other elements.

Peter - ​Okay, thank you.

A xombie

What's the nutritional value of brains?

Jonathan Reisman answered this question...

Jonathan - Well, besides the legal and ethical questions about eating another human's brain, it's a very nutritious and very high calorie meal. The average human brain is about three pounds or about 1.3 or so kilograms, and 60% of it is fat. So myelin, which is the substance that sort of insulates all the nerves. If the nerves were wires, myelin would be the sort of rubber coating on the outside. So a lot of that fat, would provide a lot of calories, probably enough calories to last you several days — you know, if you had only one human brain to subsist on. There's also protein, various kinds of, minerals, some B vitamins as well. I don't know if the person asked for a recipe when they submitted this question, but I would go with the traditional brain sandwich preparation method. Common in the city of St. Louis, which is to slice the brain, dip it in egg, spice it, and then deep fry it before putting it on rye bread with a hot mustard for the sandwich.

Chris - Delicious. I might ask the rest of the panel for their brain related recipes. Kathryn?

Kathryn Harkup - I have a question. I remember seeing a sign once many years ago that said smart cannibals don't eat brains because of the diseases that can be transmitted and accumulates within the species because of it. Is that true?

Jonathan - Yes. The most famous example is diseases of the prion form. There's a disease called kuru , historically common in Papa New Guinea, where cannibalism was more common —perhaps in ancient times than it is now. But there was a ritual eating of people's brains after death and this prion disease, kuru, was transmitted from person to person. There's also mad cow disease or bovine spongiform encephalopathy, which can be transmitted through, I am not totally clear how common it is for it to be transmitted to humans, but eating the nervous tissue or the brain of infected animals does put you at risk. I think the risk of contracting any of those prion diseases, including mad cow or chronic wasting disease, which is very common in white-tailed deer, here in the US, the transmissibility to humans is not well documented. But certainly in the case of kuru, which every medical student in the world knows about —because it's such a unique instance. There's definitely a risk there.

Raindrops hitting the ground

Is there space dust in rain?

Peter Haynes answered this question...

Peter - So I think the simple answer is there is not a piece of space dust in every raindrop, but there is dust in every raindrop — because the formation of drops is basically helped significantly by solid particles. And it's much, much easier if you like for water, to condense some form of drop or ice also on a particle, than it is simply without that. So there's an element of truth. There's no space, but there's certainly dust.

Chris - We interviewed the guys on this show. It was about 20 years ago, but they flew collectors through clouds to see what was living in clouds. And they were very surprised to find lots of bacteria in the clouds, including bacteria that seemed to make holes in trees. So that the bacteria get blown up off the tree, into the cloud and they make rainfall in the cloud by doing exactly what you say, with making water droplets form around themselves. Then they rained down on a new plant that they can infest and infect. They also said there was dandruff. They found evidence for dandruff in clouds doing again the job well .

Peter - Your answer is consistent with what I said , that any, any dust is good.

Chris - Dust. Right? And it wasn't just human dandruff. I mean, there's a lot of animal dandruff as well, but it was just intriguing to me to think that, you know, you shake a cloud and you get some — it's not just snow that comes out and there's some other white flaky stuff in there and it might be some old dandruff. Can you help this person out though, Peter? Because this person's wondering how we detect what's in the atmosphere, not of our own planet, but other planets around other stars. So, if we look out into space and we are now at the stage where we've got telescopes, powerful enough to see not just distance stars, but planets around them. Scientists are reporting what's in the atmospheres of those planets. How do they know?

Peter - Well, the first thing to say is it's actually, to me as a bit of an old guy, it's actually, this is kind of amazing, right? Because it's only sort of 30 years ago, probably less, that we saw the first planet outside the solar system. So the idea that now we can actually start to say, what's in the atmosphere is actually pretty amazing. But we're seeing this basically through radiation, that if you look at the spectrum of radiation, the distribution of radiation over different wavelengths that you see coming reflected from a planet or perhaps the radiation has come from a star near the planet, then through the planet's atmosphere. And then to us then, by looking at the spectrum, you can deduce something about the chemical species that are in the atmosphere.

A laser beam.

51:04 - Can lasers be weapons other than in films?

They're a staple of spy and space thrillers, but is this application for real...

Can lasers be weapons other than in films?

Kathryn Harkup answered this question...

Kathryn - I think lasers, they are almost synonymous with spy movies. Everything's better with a laser attached, surely. But in 1964 or 63, whenever they were filming Goldfinger —the original book had a buzz-saw that was threatening the life of James Bond. And that was a bit hackneyed, I think even when Ian Fleming wrote about it. So they wanted to update it. And in the 1960s lasers were a new thing. They are now common every-day objects — lasers are everywhere. But in 1964, they needed an explanation, because the majority of the audience had never seen one before. They understood the concept of a death ray, that's kind of a common trope in science fiction, but not a laser specifically. So they gave dialogue to Auric Goldfinger to say it is a concentrated beam of light that can melt through metal and it can project a spot on the moon, which is absolutely true.

And of course, to show it on-screen, you have this brilliant red line heading towards Sean Connery's nether regions, which of course you wouldn't see because metal cutting lasers are invisible,. But having an invisible beam travelling up a metal sheet makes no sense in a cinematic situation. So of-course you put a red light on it. So the whole concept of red lights and laser beams, I think it is a wonderful combination of ultramodern cutting-edge science, literally. But also a trope that an audience understands. And so it symbolises the old and the new very, very nicely throughout the James Bond franchise.

The Earth see from space, with the Sun just beginning to emerge from behind it

If Earth stopped rotating, what would happen?

Peter Haynes answered this question...

Peter - Well, yeah, there are mass equations for almost anything interesting. I mean, actually, this is interesting. So there are many ways to answer this question. If the earth suddenly stopped rotating, a whole bunch of things would probably sort of fly off. In some ways, it's almost more interesting to think about if it slowly stopped rotating, but I may be misinterpreting the question because there are planets that don't rotate. If I go to this topic of exo-planets, which I don't know very much about, but is very interesting. That many of the exo-planets that have been detected are what's called "locked". They're tidally locked. So the same side of the planet is facing the star. There's obviously very extreme difference between the sunny side, so to speak, and the not so sunny side —and one effect of the earth stopping rotating would be that the days would become much longer.

Chris - Well that is sort of happening, isn't it? Because Earth's rotation is slowing down indeed, because we are losing some energy to the moon. Cause there was that story earlier this year saying it's been slowing down and we have to keep adding the odd second here and there to keep track of time. But then suddenly it's speeded up again. And we actually covered the fact that the earth was about a millisecond per day, less long than it should have been in July.

Peter - There's a whole bunch of interesting things there. Which, actually another thing that effects on short time scales - another thing that affects the rotation rate of the Earth is actually the weather patterns because there's this thing called angular momentum: the amount of spin. And you can exchange angular momentum between the atmosphere and the Earth. So fluctuations on short time scales can be a result of that. If in an atmosphere that wasn't rotating, another answer would be that actually somehow, is the tropics would sort of expand, right? Which isn't to say that everything would become warmer, but we'd sort of have tropical weather over a much broader proportion of the Earth's surface. Because the rotation of the Earth is very important in determining how weather systems work. And if you go to the tropics, then actually it turns out the rotation isn't so important. So, the tropics would expand if the Earth stopped rotating.

Kathryn Harkup - So can I ask in true Bond villain fashion... Will global warming, if I could speed it up, will that also speed up the rotation of the earth as we get more violent weather systems going on?

Peter - I think these are more fluctuations than systematic effects.

Kathryn Harkup - Damn, I almost had plot the of the next film.

Peter - Yeah. You could imagine dangerous variability in the rotation of the Earth. Is it slowing down? Is it speeding up? But I mean, that's stretching things a bit far, but hey, if the people writing this Bond movie wants some new science.

Kathryn Harkup - If the Broccolis are listening, I thought of it first!

Chris - Your name will go on the credits, Kathryn.

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