The Infinite Monkey Cage - Oxygen: A Matter of Life and Death

Episode Date: July 17, 2017

Oxygen: a matter of life and death.Brian Cox and Robin Ince are joined on stage by chemist Andrea Sella, science broadcaster and writer Gabrielle Walker and comedian Sara Pascoe to look at the life and death properties of oxygen. It's the molecule we simply can't live without, but as fate would have it, oxygen is also the molecule that eventually leads to our death. Hailed as an elixir of life, and foundation of the atmosphere, oxygen is the revolutionary element that quickens life and hastens death through its ferocious reactivity. It's the molecule our cells need, but is actually highly toxic to them, and is in the end what causes us to age. Brian and Robin get to grips with the chemistry of this contradictory molecule, and Andrea Sella tries not to cause too big an explosion by demonstrating oxygen's reactive nature using a digestive biscuit. Producer: Alexandra Feachem.

In our new podcast, Nature Answers, rural stories from a changing planet, we are traveling with you to Uganda and Ghana to meet the people on the front lines of climate change. We will share stories of how they are thriving using lessons learned from nature. And good news, it is working. Learn more by listening to Nature Answers wherever you get your podcasts. This is the BBC. Hello, I'm Robin Ince. And I'm Brian Cox.

And in a moment, you're going to be hearing me saying, Hello, I'm Robin Ince. And I'm Brian Cox. Because this is the longer version of the Infinite Monkey Cage. This is the podcast version, which is normally somewhere between 12 and 17 minutes longer than that that is broadcast on Radio 4. It's got all the bits that we couldn't fit in with Brian over-explaining ideas of physics.

I do object to the use of the word longer, though, because that's obviously a frame-specific statement. Yeah, we haven't got time to deal with that because even in the longer version, we can't have a longer intro. Just let them listen. I've got an idea. Can we just have a podcast version of this intro to the podcast

which can be longer than the intro to the podcast? Yeah, it will be available very soon. The podcast intro to the podcast. Hopefully it's started by now but if you're still hearing this I don't know what's going on.

And then we can have a podcast podcast podcast version of the podcast and then it would be podcast version. Hello, I'm Brian Cox. And I'm Robin Ince. Last week we did an astronaut special

from Trondheim, which means that I've spent the entirety of the last seven days going up to strangers and going, I met a man who's been on the moon! Because I did, and it was amazing. And today, as opposed to having a man who's been on the moon, we have one of our guests who said to me, put your fingers in liquid nitrogen, and I did.

Hence my nickname, Robin Three Fingers Inch. Now, we are moving one proton up the periodic table from nitrogen this week and looking at oxygen. Actually, oxygen is Brian's favourite molecule, the O2. He's so keen on that because that is what is pumped into the chamber where, in Broadcasting House, he is kept for the rest of the year to keep him as young-looking as possible. And the only reason he has a bit of grey hair

is because one of the cleaners accidentally unplugged him because they were hoovering around Nicholas Parsons' chamber. Brian, by the way, is actually even older than Nicholas Parsons. A lot of people don't know that, but the chamber is very, very effective. Do you know what? He's one year younger than me. It's true. Doesn't work out, does it?

For listeners at home who've never actually seen my face, I look very old. People thought you were my dad, didn't they? Yeah, in Australia. Isn't it lovely he brings his dad along? Well done, well done for having such a clever daughter. Anyway, so... So let's continue with the show.

Today we are exploring oxygen. What is oxygen? Why is it so reactive? Why is it so essential to complex living things like human beings? To help us return this programme to something worthy of Radio 4, we have a distinguished panel of guests, and they are... I'm Andrea Sayla, I'm Professor of Chemistry at UCL, and my favourite use of oxygen is to bring chemistry into disrepute by setting fire to stuff.

I'm Gabrielle Walker, I'm a former chemist. I'm also a writer, and I work with businesses on dealing with big issues, especially climate change. And my favourite use of oxygen is love, because if it wasn't for oxygen, you couldn't have two sexes, and it would make life a lot more simple, but I think a lot less interesting. My name's Sarah Pascoe, I'm a comedian,

and my favourite use of oxygen is that it's actually two-thirds of my body weight, so the only bit that's actually me is three and a half stone. That's how much I weigh, really. That makes it sound like you're self-loathing. Most of it's not my fault, it's the oxygen that's done it all. Damn oxygen. And this is our panel.

Right, Andrea, we'll start off with you, because for the listeners at home, you have an enormous set-up here of everything from what appears to be magnets, Hessian and digestives, which sounds like such a Radio 4 experiment. An experiment will involve digestive biscuits. I like biscuits. Or a John Peel band.

Or a John Peel band, which is Hessian and digestives. So, I bet there must have been a point where he gave a session to someone whose main instrument was just the sound of biscuits. I hope there was. So let's get back to the show. Well, we haven't even got there yet. Let's drive to the show.

What is oxygen? What is it that makes it such an interesting gas to a chemist like you? Well, oxygen is an amazingly reactive gas, but more importantly, we're talking about an element, and one of the most common elements in the universe.

And when you take this element, you can bring it around in liquid form, and I've actually brought myself a little thermos. I'm not going to have to sit my things in again, are we? I'm going to put my safety glasses on. For the listeners, Andrea has a flask of liquid oxygen.

And I'm going to pour it into this little bowl. And you can hear that it boils really quite violently. What temperature is that? So this stuff is at minus 185. Let's just top it up a tiny bit. But I think we should get a digestive biscuit

in there because I really want to illustrate what this stuff can do. So the digestive biscuit goes in. Let's just give it a little poke so that it goes in nice and deep. We'll feed it a little bit more oxygen just for good luck. And what it's going to do is it's going to soak it all up. I mean, digestives are quite an absorbent biscuit. I don't know whether this has tax implications. But let's just get the biscuit out. This is now a very cold biscuit. And what I want to do is to show you that when you actually soak a digestive biscuit in liquid oxygen and you light it with a match, something kind of interesting happens.

Oh! Oh! Okay. And you see, what's really good about it is that what I've done is I've converted it into the ultimate diet digestive, because what we've done is we've now deprived it of all nutritional benefit.

And it smokes, too, which is kind of nice. So that's essentially what would happen if you ate the biscuits, but in a rather more controlled manner. This is what happens when you eat digestive biscuits. The only thing is that biology has developed a much cleverer system than what I've got here to actually release the energy in a digestive biscuit.

Now, remember what the digestive biscuit really represents. I mean, what this is, it's actually a bunch of sunbeams. It's a very romantic object. And what you're doing is you're essentially taking all of that solar energy that's being harvested, and then what you do... And now you can't talk, of course. Because you're full of sunbeams. But what you can now do is convert all of that energy, burn it using the oxygen, and use that for physiological processes.

Also, I've never... The sunbeam thing is beautiful now, because it's like if someone says, oh, I'm not fat, I'm just sunbeam intense. That's a beautiful... I'm just more sunbeams, baby. That's fantastic. What about the exploding sheep? All backstage, all the chat was about, oh, shh.

What is your favourite? If we could have... There was, like, shields and stuff like that. If we didn't have the regulations we have, what would have been your favourite experiment to show the reactive properties of oxygen? I think the exploding sheep. And the name exploding sheep comes from something I showed to a small child.

He was about seven at the time. He's at university now, but he just loved it, and it involves taking cotton wool. Can you commentate, Sarah? Okay, so the thermos has poured some liquid oxygen into a small cauldron. There's a handful of cotton wool. I'd say enough to clean your face twice. It's gone into the cauldron. The specs are back on for safety reasons.

The eyelash curlers have gone in, and they are gripping onto the cotton wool. I can't hear what that is. Don't do secret bits. Oh, it's a match. It's a box of matches. The cotton wool is on the safety sheet. It's steaming what that is. Don't do secret bits. Oh, it's a match. It's a box of matches. The cotton wall is on the safety sheet. It's steaming

a little bit. Woo! Ah! Ladies and gentlemen, you have been listening to the Infinite Monkey Cage. Could I just say quickly that no sheep were harmed in the making of this radio program. And what a lovely reaction, because you weren't expecting that, Sarah, were you? I was very emotionally attached

to that sheep. I know, I know. Can we talk a little bit about the, you studied the atmosphere, and when did we first kind of understand that all that was around us was a lot more complex? The atmosphere, what is it made of? So the atmosphere is

a little bit more than 20% oxygen, and it's a little bit less than 80% nitrogen. And then there's a few little bits of things in there which are actually much more important than you'd think, considering how small the quantities are, especially carbon dioxide and water vapour. Carbon dioxide is, I call it like chilli powder, it's a tiny, tiny amount of it in the atmosphere,

but it's the thing that warms us up, it's the greenhouse gas that is responsible for both keeping us nicely warm and not frozen and also is getting a little bit too overenthusiastic in its quantity and causing global warming. However, back to oxygen, I just think it's really cool. I mean, imagine looking at the air around you. It's invisible.

You can't taste it. You can't smell it. You can't hold it or do anything with it. You're not really you, it's invisible. You can't taste it, you can't smell it, you can't hold it or do anything with it. You're not really aware that it's there. So what kind of person would look at the air and think, I wonder what it is? I wonder what it's made of.

I wonder what it's got inside it and how it works. So a lot of different people did that, but the people who discovered oxygen in particular, there were two, possibly three. There's one extra guy who sort of has a claim, but my two favourites are Joseph Priestley and Antoine Lavoisier, and this was both in the 18th century, and Joseph Priestley, he was this, you would have loved him, Andrea, honestly, he was a chemist, an experimenter, and in fact, one of my favourite stories about him was he had all this glassware and stuff, and he was trying to make a gas, and he sort of lit whatever was lighting

and stepped back, and the whole thing exploded in his face he ducked out of the way of the flying glass and then set it all up and did it again just to see what happened anyway so so he was very chaotic and haphazard in what he did but he did manage to generate this gas that he could tell was different from anything else because when he put a candle in it the candle flared up and and burned with this kind intense brightness. And if you put a little mouse in it and left the mouse in the oxygen, it just kept on and on and on and on going. The other thing that I love about Joseph Priestley, if you'd made a new gas like that, you could see that it made candles flare up and you could see that a mouse sitting in it,

it didn't seem to do the mouse any harm. But would you breathe it? If you'd made a brand-new gas, would you breathe it? Hands off you would. Sometimes you don't have a choice when there's a new gas in the room. No-one warns you. So he did. He was the first human being ever to breathe pure oxygen and he said it gave him a lightness of breast. He said it was very delicious. So he sort of of made it but he didn't know what it was and the guy who

figured out what it was was Antoine Lavoisier very cool calculating actually Brian you'd have liked him I think about it I can sort of see a bit of a pattern here he liked numbers he liked weights and measures and being very precise about things and doing equations. And he's the one who figured out that oxygen is actually a part of air, and that breathing oxygen is what actually makes us alive. And he did some very ingenious experiments to do it, but the story of Lavoisier is a really sad one, because after the revolution, he stayed in Paris trying to help. He was very passionate about sort of helping the poor people, but he came from an aristocratic background and the big irony is that he had a wall built around paris to help with the the taxes that were were goods that were coming in and out of paris and making sure that he could measure them very carefully and he was very into precise measurements it was his

job and they actually said about him the reason in the end he was hauled up before the Revolutionary Council, is that they said that the discoverer of oxygen, the first man to understand what it really was, that his wall had blocked off the air from the city of Paris. And so they executed him. They actually chopped his head off. And one person watching said it took them only a moment to cut off that head, and another hundred years may not see one like it. That's a really sad story.

He's famous, he's still famous. Yeah, he's still famous, but he's really dead. To be fair, he would have been dead anyway. You're right, there's a happy ending. We all die. In terms of... So we've talked about this and seen a violent reaction with oxygen, but at a deeper level, so we go down to the atomic level

and the structure of the atoms themselves, what is happening? What's the most basic description you could give, or the most fundamental description, let me say, for what's happening in these processes? OK, so these are very, very fast reactions, and reactions which, in fact, once you get them going, they really take off.

And one of the key things is that many of these reactions involve little intermediate molecules, which are referred to as radicals. In other words, ones which have unpaired electrons. And chemists, in one way, sort of simplistically, have long imagined that if you make a molecule that's going to hang together in stable fashion, you always have to pair up the electrons, that the electrons, to say it glibly, you know, they kind of pair up just like the animals in Noah's Ark or something. Oxygen is very unusual because it doesn't do that. And

perhaps we should just look at it slightly more. This is perfect for radio, of course. And I'm going to pour it into this flask. So what I've got is a thermos flask, but one which is actually clear so that you can see what this very cold liquid looks like. And for people at home, you may be able to notice here that

it's not colorless. This is not like water. This is actually a strange faint blue color. Yes. And that faint blue color is very important. What it tells us is that there's something quite odd about the way the electrons are arranged in this molecule. Now, if we take it and we pour it, and I'll do this twice. Once I'll do it so that you guys can see it, and then I'll turn it towards the audience. If I pour it between the poles of the magnet, watch what happens. Notice that the liquid actually clings between the poles. Can you actually see that? Now, just for the audience, I'll rotate it around. Can you actually see that we've got like a cylinder of oxygen which is hanging between the two? That is very strange. So we've got a sort of

a horseshoe shaped or a bit of a curved magnet with the poles very close to each other. And the liquid has formed a cylinder connecting the north and south poles of the magnets. It hangs in between. In other words, there is, when you put this liquid between the poles of the magnet, there's a force between them. In other words, this material actually becomes magnetized. And the reason is because oxygen has two unpaired electrons. It's a stable molecule, in spite of the fact that those two electrons, in simplistic theory, ought to pair up. those two electrons in simplistic theory ought to pair up. And so this was really a mystery through the sort of first good chunk of the 20th century.

No one could work out what it was, and it really comes down to, here we are. This is the moment you've been waiting for. Quantum mechanics. All roads lead to physics. So the interesting thing is that when we start describing the way the electrons sort of sit in these molecules, when you pair them up, you've got to imagine the orbitals,

as they're called, in other words, the sort of energy levels which have particular shapes, that they overlap as you bring the two atoms together. And once you do that, you get a sequence, a kind of stack of levels into which you can put your electrons. And the same rules that govern atoms apply to molecules as well. And so one rule is the Pauli principle that you can never put more than two electrons into an orbital,

so the electrons go two by two. But then there's a second rule called Hund's rule. And Hund's rule says that if you have two identical levels, the electrons go in one by one. And that's the reason. Essentially, those two electrons, right, have individual levels to stay on which are independent. And the result is that this molecule is highly reactive.

But you can see it's kind of stable. In other words, it doesn't react with itself until you bring something else in, then excitement happens. So if oxygen is so reactive, Gabrielle, why is the 20% of our atmosphere oxygen? Because it seems that it would react away very quickly, certainly on long timescales. So how did it get there and why is it there today?

It's from life. It's one of the key signals. If you find a planet with oxygen in the atmosphere, you know that there has to be life there because it's so reactive that it's going to react away from the atmosphere as fast as it's being made. And it was first made on Earth by tiny creatures. The first appearance of cyanobacteria,

the first creatures to do photosynthesis. And actually, it's quite funny, because when they appeared, it was quite a while after their first appearance, before oxygen showed up in the atmosphere. And that's because everything was sort of waiting on Earth to be oxidized. In fact, the oceans rusted out.

They had all this sort of floating iron that rusted out. If you're using anything made of steel, it probably comes from that big rusting event. But then eventually, when all that rusting had taken place, the oxygen showed up in the atmosphere. And that was disaster for most of the creatures on Earth. Because until that point, there hadn't been any oxygen in the atmosphere. And oxygen is dangerous. Oxygen is violent.

And, you know, I think of it a bit, it's like a rampaging thug, right? It wants to get those electrons, and it's going to grab them from whoever it can. So if it's got that kind of protective security guards around it when it's being delivered to a cell, all very well, but it's still going to try and rip and grab whatever it can from whoever or whatever it can get. And there were quite a lot of creatures on Earth that had never seen oxygen, never encountered it, and couldn't take it. There was mass mortality on Earth. It was a poison.

And the creatures that did survive, survived by burying themselves. That's why in the bottoms are kind of muddy lakes. So if you dig in there, it's a bit smelly and strange because all the creatures that can't cope with oxygen actually is there. And it's also, by the way, why we fart, because the creatures that actually make the methane inside our guts have buried themselves there to try and get away from oxygen. So it was a big poison. It was a big poison. But here's the really cool thing about it. As the oxygen began to build up more and more and more in the atmosphere, eventually, about 600 million years ago, you got the very first animals. You got the first multi-celled creatures. You got the first eyes and teeth and legs and cells

and brains and hair and everything that's vivid and interesting. The first creatures that could move around, the first creatures that could do stuff. And that's because they had oxygen. It has to be something really powerful to be as big and vigorous and inventive as we are. So the current thinking, though oxygen is not vital for life, would you say that current thinking is that oxygen for complex life, with our current theory of perhaps life

on other planets and the possibility of that. Basically, as far as we know, if you want to be bigger than a pinhead... I do. You want to be bigger than a pinhead and you don't want to be slime. I do. They're the two things. They are my two ambitions in life. Then keep breathing. I will. Thank you.

This is really good advice, everyone. I think you should write it down. I'm going to write it down, just in case I forget. New Year's resolutions. What has made it so successful, I suppose, if you want to say successful, the oxygen to be the third most common? At the point of the Big Bang, we have hydrogen, we have helium, and then things continue in terms of the increase in protons.

What is it about oxygen which means this universe, this system is...? It didn't have a good PR team. That's what we're looking at. We think of Edinburgh. PR gets your attention, but it doesn't mean that you get more of you, right? That's true. So what happens is... Oxygen is actually made in the heart of stars. This is Brian's thing, right? It wasn't just Brian, by the way.

I didn't know Brian had invented oxygen. Yeah, yeah. He stuck it in the middle of stars to make it more twinkly. Then it gave him something to point at as well. I'm just making the oxygen over there and all them twinkly things. But it's actually at the end of the lives, isn't it? It's when they're not quite as twinkly. You're a bit wrong there. Sorry about that. Is it when they're twinkly things. But it's actually at the end of their lives, isn't it? It's when they're not quite as twinkly. So I think you're a bit wrong there. Sorry about that.

Oh, is it when they're twinkle-less? They're not twinkle-less, but they're a little bit less on the twinkly side, as far as I understand it. I'm glad I pulled it round to solid science. It's quite a complicated process, actually. So you start with hydrogen burning to helium, and then when the hydrogen fuel is used up in the core, then you can burn helium through a complex process

into primarily carbon and oxygen. And it often stops there. So you get white dwarf stars where the nuclear fusion processes have stopped, but they are essentially carbon and oxygen, basically. And then the much more massive stars then will go all the way to iron and beyond in the supernova explosions.

But that's why it's so common. And carbon is the fourth most common element in the universe so it's hydrogen helium oxygen carbon i should have remembered that because you told me that before more than once several times how do you when when you're Sarah you've been on the show a few times when you hear that some of the the kind of ideas of complexity and you are an autodidact as well you are someone who i always see with a notebook collating information but it's because i'm stupid like as in uh I now like listening to you guys talking about this stuff which is so fascinating and and because I'm having to convert it into my brain like some of it sounds like poetry when you're talking about kind of oxygen from stars and biscuits made of sunbeams

I love it and then um kind of I feel like I'm understanding things as an adult I think that's the thing about learning isn't it learning things as an adult. I think that's the thing about learning, isn't it? Learning things as an adult. You know that someone tried to explain this to me when I was 14 and 15, but I had no framework for that information to go into. I think I'd love to go back to school now, about all of the subjects.

I'd love to learn. I have these huge gaps in my knowledge and I love being told things. Yeah, and trying to remember them. I think now, though, because also there's been a clever technique from Andrea where every time you smell a burnt biscuit, you will have magnificent recall now of equations as well.

How often are you going to smell a burnt biscuit? Never, because I'm a vegan. There must be some vegan biscuits that are flammable. I've never asked that before, by the way. When something comes out of your mouth and you think, why on earth did I say, there must be some vegan biscuits that are flammable? I'm sure there will be no ingredients.

I mean, it doesn't require eggs or dairy, does it? The biscuit to the flames? It's a secret formula. Is it a secret? Yeah, I think it's proprietary. Well, I mean, I think you don't need either the dairy or the egg. So you can just do it with pure flour or chickpeas. It would have no nutritional value at all then

because you wouldn't be able to digest it even if you were to burn it. You mean if it were made of cement for example? Well yes, it must react with oxygen. A cement biscuit would be extremely safe, non-flammable, but at the same time have, yes, as you say, very little nutritional value. Why doesn't cement react with oxygen?

Cement has already reacted with oxygen, right? Because what you're talking about is mainly aluminium and silicon oxides on the other hand you might be able to run a life form off taking oxygen with aluminium and silicon and burning that gently to make cement to make cement yes and you would get beautiful structures. Can I ask, when it comes to... I'm fascinated by this. This life form that Andrea is imagining, the end process of its digestive system is cement. I mean, you know, it would leave a permanent trail.

Wouldn't that be uncomfortable? Well... Would its bum look like a cement mixer? Let me put it to you another way. In other words, we are doing exactly the same thing because, of course, what we do is we leave a trail of CO2 and water, right? In other words, we're combining oxygen with carbon, hydrogen with oxygen,

and we leave that trail plus a few additional novel gases, right, that Sarah's into. Or maybe not. Whereas, you know, these other life forms, I mean, you're just moving down or slightly across in the periodic table. You're combining oxygen with other elements, say aluminium and silicon, and you might be able to generate life forms that way.

I'm intrigued when you just see... I know we were dealing with, you it's about that, the electrons, but those things where you go, this is highly reactive and this, therefore, when you have what appears to be a planet which is quite rich in chemical reactions, and that is not obviously what we see across the whole universe, from what we know so far and the limited knowledge we have. Well, the thing is, we know that chemistry is completely universal. I mean, that was something that was really established in about 1859. In fact, interestingly,

the same year as the origin of species, when Bunsen and Kirchhoff first suddenly realized that the lines in the spectrum of the sun matched up exactly with the lines in the spectra from flames. Bunsen had made his Bunsen burner, and there were certain particular lines, colors in the spectrum. When those two matched up, suddenly chemistry moved from being something that you did in the lab or out on Earth somehow to being universal. So we know that the chemistry happens everywhere. We haven't actually managed to really see it beyond anywhere than the solar system, in a sense. And one of see it beyond anywhere, you know, than the solar system in a sense. And one of the exciting things is, for example, the James Webb Space Telescope, which might

allow us to actually observe, you know, chemistry in atmospheres elsewhere. One of the key things, of course, for those missions is to go and look at what the chemical composition is, because the really special thing about Earth's atmosphere is the fact that it's not at equilibrium, right? And so here I'm really thinking about the kind of grand unified theory of the world that was developed in the 19th century, not about particles, but about thermodynamics. And you look at the composition of the atmosphere,

and the composition of the atmosphere is wrong. It should all burn to CO2 and to water. There shouldn't be oxygen there. We shouldn't have hydrocarbons lying around. And that might be a telltale sign of life. In fact, it was James Lovelock who first started suggesting that that would be the way to test other worlds. And so now we're actually close to the jumping-off point,

and if you were to see oxygen, the spectral characteristics of oxygen out in the atmospheres of some exoplanet, that might be an indication that there's something very strange going on there. Because you have a chemically unstable, as you said, out of equilibrium atmosphere, then something needs to be keeping it like that. There must be something which is pushing it away. Remember, equilibrium, we all learn about it

in school, in a sense, but it's the most boring situation to be in, right? It's death. It's chemical death. What you want to be is well away from that, in that exciting place where fires happen. Would it work the same way vice versa if you introduced lots and lots of oxygen into um an atmosphere could that then lead if you

put enough in could that then lead to creating life if i was writing like a sci-fi novel i i would say no because life began without oxygen it Oh, I see. It began in the big oceans. It's a complex life, so you'd have to have life already to then kind of translate. One of the real problems is that oxygen is so reactive that some of the fundamental building blocks from which you might want to construct life would actually, if you had oxygen there, might well be quite fragile, right? And you might lose them as quickly as they appear.

Oh, no, I've killed my babies. But, you know, if you could do it, I mean, from the experiment on Earth, if you could put oxygen in the atmosphere and keep on doing it for tens, hundreds of thousands, millions of years and sit and have the patience, then you might well then find... So I would be God now, which is what we're just... I've just invented God. You have invented God, well done. And he's obviously very patient. We're just running out of time.

To summarise, though, we've been talking about the atmosphere, but this thing, oxygen, for a chemist, is it one of the ultimate building blocks, the ultimate element in terms of its reactivity and the role it plays, I suppose, the profound role it plays? I mean, oxygen plays a hugely profound role in chemistry because not only does it form such incredibly sort of stable molecules, but one of the things that it does is when you put it into a molecule,

one thing that it often does is it distorts the charges. In other words, it leaves more positive on one side, and it tends to be more negative. And the moment you do that with molecules, what they do is they start to kind of stick together. You start to build in a kind of chemical stickiness, a kind of chemical bias, which, A, makes things condensed,

makes them into liquids, into solids. I mean, one of the key things about water, for example, is that you have oxygen attached to hydrogen. The hydrogens are positive, the oxygen is negative. That makes those water molecules stick together. It gives ice its weird structure and its properties. And it's all driven by the real fundamental difference between hydrogen and oxygen, right, that charge difference.

So oxygen is one of these kind of, in a way, fundamental difference between hydrogen and oxygen, right? That charge difference. So oxygen is one of these kind of, in a way, really iconic elements in the periodic table. One that is such an important contributor to our world. And yeah, if we didn't have oxygen, I mean, my God, what would we have to play with? Fluorine! Even better. Can I just say, for listeners at home, mad scientist face was suddenly seen there. That's what I wonder.

I have to ask, when I stuck my finger in the liquid nitrogen a couple of series ago, I was worried that I would just go, oh, don't take it out again. You know that bit where your brain makes you... Do you ever pour out liquid oxygen and think, I know I shouldn't drink it, why is my brain going, go on, drink it? Because that's one of the reasons I never became a chemist.

I just do, I know I shouldn't drink the mercury, but go on. Drinking oxygen is not something I've ever been tempted to do, but, you know, unlike Bill Clinton, I certainly like to inhale. It just sounds... Describing oxygen... I certainly like to inhale. Just describing oxygen. So we discussed, you could imagine a universe where life can exist without oxygen in an atmosphere, obviously, because that was the state of the Earth when life began. But as you mentioned there, water,

the properties are unique and profoundly dependent on the chemistry of oxygen. Could you imagine a universe with no oxygen but life? Well, look, I think that's a very, very difficult question on one level. I mean, we know that there are life forms on Earth that have nothing to do with molecular oxygen. In other words, down at those kind of volcanic vents, down in the depths of the sea, you have all kinds of chemistry and life which is sort of driven by chemistry involving other

elements. And remember, it's always this business of being able to transfer electrons around in order to be able to split bonds, in order to make bonds, to build structures, and so on. But if, in fact, you didn't have oxygen, I mean, that would change things very, very profoundly. Because one of the wonderful things about having oxygen is water, and the fact that it has such a high boiling point compared to any other molecule of its size, right? There's nothing comparable to that. And it's got this nice liquid range. It will dissolve, you know, water will dissolve such a wide range of things, particularly salts, but also molecules which don't sort of ionize,

which aren't as charged like that. And so I think without oxygen, you really struggle to imagine. And yet, I mean, to quote the great geneticist who was from UCL, J.B.S. Haldane, the universe is not queerer than we suppose. It's queerer than we can suppose. And almost certainly, there may be places where oxygen is much less available. And yet, perhaps this self-replicating energy capture and processing, which is what life is all about, is taking place. Can I just ask on a different practical thing near the end? I mean, obviously breathing's very practical as well

and the use of oxygen in living stuff, but... Breathing's very practical. It is, it is. I tried stopping it for a while, but I'm just addicted. But I wondered about oxygen. Everything that anyone has any rough knowledge of, we then also find there are ways of people selling you tat. Oxygen bars, for instance.

Is there any? That was a hip thing. Did you ever go to that? No, I never went, but that's what I was interested in. Also, quite often with things I've heard, like beauty products and stuff, there's always things about oxygenating your skin and all that kind of... So what... Is it all rubbish? It's not all rubbish, actually, but some of it's rubbish. OK. As usual. A bit of both. Yeah.

Antioxidants. You get people who go, yeah, I also take antioxidants, right? So antioxidants, right, my big jar of antioxidants, I don't have one, but what is that meant to be doing to my oxygen? OK, so here's the story. I mean, the oxygen bars, when Joseph Priestley first breathed oxygen, he said, oh, it makes me feel really nice. It's nice. It's a different kind of feeling. You probably don't want to breathe pure oxygen for too long,

although astronauts have done it, and also people who are sick and oxygen tense, you know, it does actually really help. So oxygenating your skin, it's already pretty oxygenated, I would have thought. Breathing oxygen feels nice. Antioxidants, we've got plenty of them in our bodies already. If you eat enough fruit and vegetables, you've got plenty of them. And there's even some theories that if you eat antioxidant pills,

then you might disrupt your own system. It's like bringing in a load of unruly mercenaries when you've already got a well-trained army. So you don't necessarily want to do that. But also there's something very profound about the fact that oxygen is the reason we're not pinheads. It's the reason we're not slime. It's how we can be big and vigorous and creative and solve problems and be interesting. But it's actually also what kills us. Oxygen is responsible for all the diseases of old age and dementia and cancer and so on, and ultimately death by the rampaging it does

with all these free radicals in your body. So the thing that you were breathing, there was one estimate that breathing for a year is the equivalent of having 10,000 chest X-rays. That's how much damage it's doing to you. And our bodies are very impressive that they can resist it, but eventually you won't. So oxygen is the thing thing it is the reason

that we will all grow old and die and yet it's the reason that we can all live so sarah you've heard both sides of the argument and you've smelt the biscuit so how do you feel oxygen good thing bad thing i feel like i feel like this is a remake with science of it's a beautiful life where you get to find out about the past and what would have been like without oxygen, if there's kind of nothing, and then the future, what happens if we don't kind of protect the things that we've got, and then I wake up, and it's all a dream.

It's all okay, and we've got some oxygen, but we have to be careful now, guys. Is that the right thing? Have I understood? I also like the fact that that breathing thing, there's going to be a Fitbit that says, hold your breath for a little bit, we'll keep you younger. I've been breathing too long.

What are you doing? You're so young! Oh, it hurts my eyes. People do go up to high altitudes for that exact reason. There's a new thing about going to a high altitude to have less oxygen. That's why you're so young! They're mountains, aren't you?

I'm a little bit nearer the stars now, up a lovely mountain. Look at me young skin. Robin lives in a cellar, that's why he's all old. So, we asked the audience a question about oxygen, which we found very hard, actually. What did we want to ask them? So, eventually, what we came up with was, Jean-Michel Jarre wrote an album all about Oxygen.

Which gas would you like there to be some kind of concept stroke prog album about? And these were all his answers. Helium, because it will be uplifting. Oh. I'm awfully sorry, Jamie. I thought you did very well, Jamie. Freon.

It's cool. It'd be a great chill-out ambient concept album. I'm awfully sorry, Jamie. I thought you did very well, Jamie. Free on. It's cool. It'd be a great, chill-out, ambient concept album. Number one, album title, All I Want Some Peace And Quiet. Number two, All The Songs Are Gone. LAUGHTER See? Huge face. Are gone. Are gone. Not hydrogen.

G-O-N-E. For the listeners. A poolside summer hit single by Dolly Parton. Chlorine, chlorine, it's all I got. Next week we'll be asking, are insects taking over the world? We're not really asking that. We're asking why are insects more resilient than human beings and why are they so successful? Why have they been around for

so long? Yeah, but if we ask, are insects taking over the world? We get pick of the day from the Daily Express. So we'll also then be asking, will the sun explode on Thursday? No. No. Are my Martian superbugs about to destroy the Earth through disease? No.

OK, that's... We don't know what we're going to be doing next week, then. Thanks. Bye-bye. APPLAUSE John, that was nice again. Brian doesn't even know that you have actually now listened to the whole of the show, and this is all he's been doing for the last 47 minutes. And it's not going to end for a while either. It's a nested infinity of podcasts. This is my life.

This is my life. This is the BBC. In our new podcast, Nature Answers, rural stories from a changing planet, we are travelling with you to Uganda and Ghana to meet the people on the front lines of climate change. We will share stories of how they are thriving using lessons learned from nature. And good news, it is working. Learn more by listening to Nature Answers wherever you get your podcasts. you