The Puzzle of the Plasma Doughnut

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Welcome back, Curios.

It is the last episode in the current run, but we've just been informed that we will be back in January.

We haven't checked our schedules or diaries.

I am fairly certain that there are zero days left in Mine and Adams' diaries that align neatly enough to be able to record an episode.

But we'll find.

We'll find.

Christmas Day, Boxing Day, these are the types of things that we can.

We say this to you as we are in on a bank holiday recording this for you.

That is our level of dedication.

Yes, indeed, it is.

So, do send us your new questions because, even though there is a new series apparently starting in January, we have literally no idea what it's going to be on.

So, send us your questions to curiouscases at bbc.co.uk.

And our wonderful new producer, Ilan, will go through them and pick out the very best,

which is exactly what he did for this episode coming up.

A big high-energy physics episode to finish off this series because we are talking about nuclear fusion today.

It's a power source that has been hyped and hyped.

Right, and the stakes couldn't be higher.

If we can get nuclear fusion to work, then we enter an era of clean, endless energy.

Which does sound pretty thrilling.

But listener Les Walker wants clarification.

Earlier in the year, he writes, there were news stories about a breakthrough in nuclear fusion.

I know that nuclear fusion is the process that powers the sun, but how can we do it safely on Earth and how do we extract the energy produced?

Now, all very good questions, Les, and a subject that both of us, even this biology nerd, feel pretty strongly about.

So, as ever, we have got some real experts in with us to help get to the core of fusion.

How it works, indeed, does it work?

And could it work as a real solution to the energy and climate crises that we are in?

Dr.

Sharon Ann Holgate is a physicist, writer, and author of Nuclear Fusion, The Race to Build a Mini Sun on Earth.

And Dr.

Menley Windridge, plasma physicist who is the CEO of Fusion Energy Insights and author of Star Chambers.

Okay, so to get us going, please, Sharon, could we have the nuts and bolts of this?

We have nuclear energy already, but it's fission reactors.

And this program is about fusion energy.

So from a straight-up atomic point of view, what is the difference between fission and fusion?

Okay, so in both processes, you're creating these enormous amounts of energy, energy, which is really good news.

But in fusion, you're fusing two atoms together to make up another one.

And in fission, you're splitting an atom apart into two.

And where does the energy actually come from in that splitting apart or sticking together?

Okay, so it's this, it's to do with this thing called the strong nuclear force, which is basically what binds all of the protons and neutrons together in the nucleus.

One of the effects of the strong force is that the mass of a nucleus when these protons and neutrons are all bound together is actually slightly less than the mass of its constituent particles.

This is just an effect of the strong nuclear force.

So

if you change a nucleus in any way, you have this kind of mass difference between the nucleus bound together and the constituent particles.

And Einstein told us that energy and mass are actually equivalent.

And this is bound up in arguably the world's most famous equation, E equals M C squared.

So E is your energy, M is the mass

and C is the speed of light, which is enormous, 300,000 kilometers per second.

So even though the mass difference is tiny, because in Einstein's equation it's multiplied by this gigantic number of C squared, you get these huge amounts of energy out.

The way you've described that, though, of building building atoms together and breaking them apart, it's sort of, I guess,

two sides of the same coin, two ends of the same spectrum, as it were.

Why is it that people are so excited about fusion building atoms together if we already have fission where you break them apart?

Probably quite a few reasons for that.

I mean, one of them is that you would get four times the amount of energy yield compared with fission for the same amount of fuel, which is obviously very good news.

But also, one of the great things about fusion is if we can get this to a commercial reality, it doesn't create anywhere near the amount of radioactive waste that fission plants do.

And additionally, it's a lot safer because it's not a chain reaction.

So, basically, if anything goes wrong at a fusion power plant, if any parts shut off, like heating systems, cooling systems, actually, the whole thing just naturally closes down.

That's that's a really good, that's a really important point actually, because, well, I mean, nuclear fission, it does have something of a negative reputation with Chernobyl in the 80s and Fukushima more recently.

Fusion doesn't have that same stigma, partly because it doesn't exist yet, but also because that just would not happen.

No, that's right.

It just is completely impossible for it to happen.

The minute anything changes with the machine, the plasma will just cool down to a temperature below that at which fusion can take place.

So the whole reaction just ceases.

In terms of the differences, though, between fission and fusion, Melanie, the type of fuel that you're using is also quite different.

So, uranium for fission and then hydrogen for fusion.

Why is it that you end up with those opposite ends of the periodic table, as it were?

That's to do with something that Sharon touched on called binding energy.

So, the binding energy is just like how tightly the nucleus is bound together.

So, there's actually a curve called the binding energy curve,

this sort of goes up quite steeply and then it peaks and then it drops off again.

The more binding energy it has, the more stable the atom is.

And so the peak of that graph is at iron.

Iron is the most tightly bound nucleus, it's the most stable nucleus.

And in general, in nature, things want to get more stable.

Elements want to go up the curve, if you like.

So if they're small, they want to fuse to make themselves more stable.

And if they're big, like uranium, they want to split in two to make themselves more stable.

And anytime you're going from an atom that's got a smaller amount of binding energy and you're making something that has a larger amount of binding energy, you're actually releasing energy.

When we were preparing this in the office, Hannah got some graphs out

and she actually said, and I quote directly, there's some really nice graphs on this.

And then she proceeded to show them to me, at which point I stopped listening.

Did you love the graphs?

You didn't love the graph.

They were okay as far as graphs go.

It was a great graph.

It was a classic.

It was a good graph.

So then, would it be possible if you really wanted to, could you do nuclear fusion with uranium?

No, not as far as I'm aware.

It takes a lot of energy to push the particles together.

So if you think about it, the nucleus of an atom is positively charged.

And like charges repel each other.

They don't want to come together.

It's like trying to get two north poles of a magnet to come together.

So you've got to force them together really hard.

This is why fusion is so hard, because you've got to give them so much energy to get them to fuse, which is why it only happens naturally in the centers of stars.

Well, Sharon, we've just introduced stars here, and we often talk about how stars are giant fusion reactors.

What is different between the way stars do it, between the way the Sun is doing nuclear fusion and the way we would do it on Earth?

Pressure.

Basically, that's the big thing.

I mean, there's just no way that we can recreate on Earth these immense pressures that you get in the centre of stars.

So, to make up for that, what we have to do instead is just have it an awful lot hotter.

So the core of our Sun is about 15 million degrees Celsius and we're going to have to go 10 times hotter than that in a fusion reactor in order to overcome the electrostatic repulsion that Melanie was just talking about so that we can actually get the nuclei in the plasma to smash together and fuse.

And we've mentioned plasma as the state that hydrogen has to be in in a fusion reactor.

Relly, I understand that you once won the Rutherford Plasma Physics Communication Prize.

Anything to do with you, item?

Nothing to do with me, but I'm really, really happy to give you a prize, depending on what happens in the next 20 minutes or so.

But as such, we couldn't have anybody who was more qualified to tell us what a plasma is.

A plasma is just an electrically charged gas.

It's the fourth state of matter.

If you move through the states of matter by adding energy or heating things up, you can go from solids to liquids, liquids to gas.

And if you give a gas even more energy, then what you're able to do is strip electrons away from the nucleus of the atom.

And so then you have these charges moving around freely, and so you have an electrically charged gas.

And it's really interesting and beautiful because they're quite chaotic and dynamic because you have some of the fluid properties of a gas, but then on top of that, you have these electromagnetic properties because moving charges create magnetic fields and changing magnetic fields create electric fields which affect charged particles.

And so everything sort of feeds back on each other and it gets quite complicated and beautiful.

We should recognise that there is plasma all around us in our everyday lives in fluorescent light bulbs.

And I see you've brought in one of those, well, those little plasma balls that are sort of epitome of soft rock videos from the 1980s.

That is plasma in there, right?

It's plasma, yeah.

But that's plasma.

I mean, you're touching it with your finger, and anyone who coveted one of these as a child, as I absolutely definitely did, will know that we are looking at a sort of glass orb with a pink light in the middle.

And when you touch the outside with your finger, almost like what can only be described as like a blue shaft of light reaches out and touches your finger.

But it's, I mean, you're touching this.

This is not the temperature of the sun.

No, it's not.

Plasma doesn't have to be really, really hot.

It can be, but you can also have have cold plasmas.

All that you need is enough energy to strip electrons away from the atoms.

And different gases do this more readily than others.

So as the most ignorant person in this conversation, I had a stupid question, which is when describing a plasma and you say the electrons have been stripped away and it's a charged gas.

I get all that.

Where are the electrons?

Where have they gone?

They're just in there.

Some people call it a soup of charged particles.

They're just mixed in with the nuclei.

But they're not orbiting around their own atoms.

No, they're just moving away around freely.

Earlier on when we were in our writing room, Adam had a bit of a meltdown when he wondered where all the electrons were in the sun.

Whether the sun just didn't have any.

Perfectly reasonable question.

Where are the electrons in the sun?

They're just in the soup.

Okay.

Okay, so the key question here for me is that now that I have a vague understanding of what plasmas are and where the electrons are, which is in the plasma, I get it now.

Why do we need plasmas inside a fusion reactor?

There are three main things that we need for fusion.

We need to keep it hot enough and dense enough for long enough for fusion reactions to occur and to keep going.

And so essentially, we need to get temperatures higher or at least as high as the centre of the sun.

And the temperature in the centre of the sun is 15 million degrees.

If we try and do that on Earth, because we don't have the same amount of time as in the Sun, which is like a long, long, long time.

So we need to get a lot higher temperatures, like hundreds of millions of degrees.

And if you heat anything to 100 million degrees, it's going to be a plasma.

So it's not that you're aiming for a plasma in order to get fusion, it's that you're aiming for a temperature which results in the plasma.

You're aiming for particles moving around really fast.

And that if something's moving faster, it has a higher temperature.

But we need them to be moving really fast in order to overcome that repulsion that's between them.

We need to get them slamming into each other really hard so that they can get over the electrostatic repulsion that they feel and get into, get close enough for the strong force to kick in and pull the nucleus together.

Is fusion an automatic thing then?

If you just get a bunch of particles and you make them hot enough and pack them in densely enough and you hold them there long enough, is fusion automatic at that point?

It's still, there's a probability cross-section of it happening.

That's just what I thought, actually.

Probability cross-section in answer to your question.

They're not all going to fuse,

But that's why sometimes people ask the question of like, well, couldn't you just use a big particle accelerator like CERN and just bash the two particles together and get them to fuse?

And yeah, you could.

But that'd be very inefficient because you've got one particle fusing and we need to get a lot of particles fusing if we're going to make energy.

So that's why you tend to have a lot of fuel and a lot of particles all moving around.

And then some of them will fuse, a lot of them won't.

But hopefully you'll get enough.

I'm just sort of, you know, I actually hadn't ever clocked that before.

I think maybe I thought that there was a particular movement that was being made to manipulate the plasma in a certain way, but I didn't realise that it's essentially like a heavy metal rock concert, that you just get enough, cram them in enough together, and eventually there'll be a punch-up.

Yep, it's exactly like that.

That's where the magic happens.

That's the density.

Cram them all in closer, hi, make it really hot.

Make it really hot, and then agree.

And then, yeah,

leave them there long enough, there's sure to be a fight.

Guaranteed.

Okay, so fission is splitting things up, fusion is smashing them together.

Both result in the conversion of matter into energy, as per Einstein, and that is what we want.

Fusion uses a plasma, which is a cloud of atoms, which have been disassociated from their electrons, as I've just understood, and hence unlimited power.

So far, so good?

That's pretty good, actually, because, you know, I was beginning to think that your entire knowledge of fusion came from Back to the Future.

Yeah, great Scott.

No, no, no, I understand all of the science.

But then the question is, why don't we have fusion reactors yet?

Yes.

Sharon, I think we'll start with you on this one, if we can.

Maybe we should start with a story about a Russian doughnut.

Yes.

So a tokamak, really, you can, is one of the ways in which we might be able to have a commercial fusion reactor.

And you can imagine this a bit like, so suppose you decided to go to a shop one day and buy yourself a doughnut and for reasons best known to yourself you decide to have this doughnut gold plated

and then if you were to drill a little hole in the bottom of your gold plated doughnut and heat the whole thing up so much so that your donut actually melts and then it dribbles out through the hole the shape that you're then left with is very similar to the reactor chamber in a tokamak a hollowed out gold doughnut i mean it sounds delicious okay so so why

why

Well, why is because one of the things you need to do is obviously, if you've got this enormously hot plasma, you've got to contain this somehow.

And there just isn't a material available on Earth that you could have this incredibly hot plasma coming into contact with.

So what scientists and engineers are doing is using these incredibly large magnetic fields to basically cage the plasma and keep it away from the walls.

Because the plasma particles have got a charge, you can use the field to just repel the plasma away.

So you have the plasma sitting inside this hollowed-out doughnut and magnets on the outside that are keeping it away from the edges.

And who were the people who worked this out?

I mean, this seems like to imagine a gold doughnut in the first instance seems like quite a conceptual leap.

Who were the first people to work this out?

Well, fusion research really started in the very late 1940s, but it was mainly in the 1950s that scientists really began looking at different designs of fusion machines.

These were just kind of concepts to start with really.

So some of the first machines were so-called pinch machines, and these were more like a cylindrical tube, which was open at both ends.

And then people progressed on to circular arrangements.

And One of my favorite ever machine names is something that I came across while I was writing my book.

It was was used in America.

It was part of Project Sherwood, which started in 1951, and it was called the Perhaps Atron.

And it got the name because perhaps it would work and perhaps it wouldn't.

Goodness, that is not very reassuring at all.

So there were a whole series of these Perhaps a Tron machines, which I mean, managed to do quite a few experiments with them.

But meanwhile, the Soviets were developing the Tokamak.

And to cut a very long story short, they actually did better with their tokamak than the UK or the US or other people were doing.

And once scientists and engineers saw the sorts of results that were coming out of a tokamak, pretty much everyone at that point changed track and went for that.

Is tokamak just a Russian word, Melanie?

It's actually an acronym.

It stands for Troydenay Kamara Magnichnai Katushka.

Which is easy for you to say.

It's very impressive.

It's the only Russian I speak.

Say it again.

Teroidal nai kamera magnič na katushka.

And what does it mean?

It means toroidal chamber magnetic coils, which is essentially what a tokamak is.

It's a toroidal or ring doughnut shaped vessel with magnetic coils around the outside that make a trap for the plasma.

Is there a particular reason why the tokamak, the doughnut shape, works better than

a sphere?

Yes, it's because

you've got the charged particles are moving, and so you need to keep them constrained, essentially.

So the first machines that they started looking at were linear machines, so straight lines.

But then very quickly, you lose all your particles out the end of the machine, which you don't want to do.

So they'd move it, like they'd bend it round and make a circle instead.

So then you've got your particles travelling around in a ring, essentially.

And the early designs, like before the tokamak,

they found that the particles would actually drift outwards because of the interplay of the electric and magnetic fields in a plasma.

the particles would drift, and so they were losing their particles out the sides.

And so, what they found, and what's the key thing in a tokamak, is that if you put a current through in the same direction, so around the long way around the doughnut, then that current makes a magnetic field around it.

And that magnetic field kind of pulls everything in away from the walls, and so it stops that drift.

In terms of the tokamak, though, the traditional, as it were, design, there is a sort of gold standard as well as probably gold-plated version of this in the countryside in France, isn't there, Sharon?

So, this is a ETA, which stands for the Way in Latin.

And just incredible size, the whole site is incredibly large.

I mean, the Tokamak building itself is 73 metres high, and that's slightly taller than the Arc de Triomphe in Paris, although apparently some of that is going to be, or indeed is, it's being built now, is underground.

Each of their toroidal field magnets which are the ones that go around the uh the doughnut shape each single one weighs 310 tons and that's roughly the same as a fully loaded boeing 747 airliner wow incredible so just the whole thing is just this astonishing feat of engineering is this the point where i can brag about the fact that i've been there

If you insist, I mean, she only mentioned it 18 times when we were writing the questions earlier today, but why don't you let the audience know?

It is extraordinary.

Extraordinary.

You stand next to it, it feels like you're standing next to a spaceship.

It's like that sort of a scale, right?

You kind of stand right at the bottom and you look up and you see this gigantic structure towering over you.

And when I was there, they had just installed the first segment.

It kind of like imagine sort of an orange, is it like segment by segment as it goes in, as they slide them all in.

And the millimetre precision, I mean, probably way less than a millimetre, in fact.

It's just something else.

Okay, well, look, so ITER is kind of the gold standard, but it's under construction, Sharon.

When does it go online?

It's still on schedule to be up and running fully by 2035.

So that's the sort of time scale we're looking at.

But ETA is a kind of a proof of concept.

I mean, this is a scientific experiment rather than a plant that will generate energy for commercial purposes, right?

Absolutely.

Yes, it is very much an experiment.

The whole thing is an experiment.

It will never put electricity on the grid.

But what it is designed to do is basically a proof of concept.

And the key equation in being an energy generating machine is that the energy that it puts out is more than the energy you put into it.

And we're not there yet at all, are we?

Absolutely not.

No.

And you are absolutely correct.

In order to do anything useful, we clearly do need to get more energy out than we're putting in and that is the absolutely huge engineering challenge that's the whole hope with ether is that finally the machine is so gargantuan in scale that it can actually create the first so-called burning plasma when the plasma becomes the whole thing becomes kind of self-sustaining you say they're gargantuan in scale is gargantuan in scale the key thing here could you could you in future i'm just trying to imagine right long into the future could you get a fusion reactor that was really small, like I don't know,

the size of a desktop computer?

Yes.

Yes.

Yeah, some companies are working on very small ones, like micro scale reactors that may be as small as fitting on the back of a large truck, for instance.

Now I'm excited because my next question was, could you ever get one that was big enough to fit on the back of a DeLorean and maybe generate 1.21 gigawatts of energy that would take you back to the future?

You're saying that's a very real possibility and now I'm really engaged with this programme.

I'm not quite sure whether it could squeeze onto the back of a DeLorean but do you know what?

For you Adam I'll give it a try.

You said truck.

I mean a large, what size truck?

Melanie, can we get fusion on the back of a DeLorean?

Not yet, but when you said truck I was thinking like are we in like American or British English because like a truck's a very different scale, isn't it?

In each of those different.

I will accept that as an answer.

But it is a really key interesting point that you make though because there's nothing actually in the physics that says that fusion machines have to be big.

The size of the machine is probably going to come down to the approach adopted, the technology that's available at the time.

And I find this really hopeful because technologies always change.

And we can do a lot of things now that we couldn't do when ITA was being designed, for example.

It was probably being designed in the 80s and 90s, and we didn't even have smartphones then.

You know, we can do a huge amount more.

I used to listen to a Walkman

cassette tapes in the 80s and early 90s.

You know, so technologies are hugely different than they used to be.

And that means that we can do things differently.

And in fact, if you're thinking about commercialising a technology, and that's what we want, right?

We want to get to commercial fusion.

We want to have power stations running and creating clean energy for everybody.

And if you want to do that, you cannot make something as big as ETA.

You have to bring the size down.

So ETA, many scientists are confident, will work and will demonstrate that we can get fusion.

but if we want to commercialise it, we need to make them smaller.

Okay, so ETA down in Marseille, that's kind of the gold standard in fusion research, and it has been for decades because it's a huge international collaboration led by governments.

But we spoke to Arthur Terrell, who's a plasma physicist, and he's the author of the book Star Builders, and he told us that loads of commercial companies have now joined the race to get fusion power up and running.

His Eclipse.

For a long time, the main players in this race were mainly government laboratories.

But something really, really interesting has happened in the last decade, and even more so just in the last five years.

There are also now lots and lots of private companies who seem to think that, you know, by trying out different approaches or by raising private finance, they might be able to get there quicker and they might be able to get there cheaper.

Just to give you a sense of the scale of this, there are around 25 private sector fusion firms now and just in the last couple of years about 4.2 billion US dollars has flowed into fusion.

And today there are over 100 experimental fusion reactors built or under construction, public and private.

So it's a really exciting time where lots of new things have been tried and are being tried and it just feels like there's real momentum behind the progress.

I noticed there while you were listening to Acclip Milly that you commented on Arthur saying they like to think that they're they're going to get to fusion faster.

What did you mean by that?

Well,

it's imperative that we do get to fusion faster.

I think that's the perspective from the private companies.

They're saying if we want to contribute to climate targets like net zero, for example, in 2050, if we want to be ready by 2050 and before then, so we're contributing, then we need to be doing things faster.

So, working back from there, we need to be thinking about like rolling out in the 2040s, which means that in the 2030s, you need to be building pilot plants and showing that they work and starting construction.

And that means that in the twenty twenties, this decade, you need to be getting past energy break-even.

You need to be demonstrating the science.

And

so that's what a lot of the private companies are working on.

You need both of these things.

It's going to be a partnership.

It's going to be expertise from the public labs combined with the agility and motivation and drive of the private companies and support from government that's going to get us there.

So it's an extraordinary thing to imagine a world where actually you do have limitless clean energy.

And in fact, Arthur Terrell, he also shared with us a quite awesome possibility that fusion power could bring,

namely space travel.

The only way we are going to travel to the universe beyond our own celestial backyard is with nuclear fusion.

Because rockets based on fusion as a reaction are humanity's best hope for traveling across the vast, vast distances of space.

And you know, the reason is that fusion packs a lot of energy into a really small amount of mass.

It is the most energy-releasing, the most energy-intensive reaction that we have access to on Earth at all.

So, you don't need to take much fuel to get a lot of energy out, and that's really important for rockets.

So, you know, fusion is the power source of the stars, but it is also the only power source that can take us to the stars, too.

Melanie, you were nodding along there, and I realise you're not a neutral participant in this.

You come with some priors in this department, but do you agree with that?

Yes, and I was nodding because I thought it was very poetic how Arthur put it there at the end.

But yes, it's going to be really important for energy generation on Earth, and it also gives us the possibility of

going out into the solar system.

Well, thank you very much for that, Melanie Windridge, and thank you also to Sharon Ann Holgate and to Arthur Terrell.

So Doc Brown have we solved the problem of fusion?

Well Marty, yes and no.

We have a really solid understanding of the principles of fusion and there are amazing high-tech experiments and companies all around the world that are inching us towards making it a reality.

But it's something that's going to need serious investment if it's ever going to work.

And what the hell is a jigger what anyway?

I nerded out again, didn't I?

I managed to force 80s film references against your knowledge and will into our main output.

Look, you know what?

The day when you don't do that, I am going to worry if something bad has happened.

But did you notice we had a lot of analogies in there?

So there was a strong food theme.

So there was the doughnuts.

Melanie did it.

She had a food reference in there.

I can't remember what it was, carrots or something, probably.

Fusion carrots.

I'm pretty sure she said that.

She's actually, for the listeners, she's actually in the booth over there.

She's shaking her head.

She can't come in and we've locked the door, so she's excluded from the corner.

Oh, yeah, I remember her fusion carrot thing.

That was it.

it.

Go down.

It's classic.

The fusion carrot.

And then, of course, your great analogy, the heavy metal concert, which actually works really well.

Thanks.

I don't know whether

you should really use punch-ups as a

atomic punch-ups.

Atomic punch-ups.

Can I tell you about the first time I went into a Tokamag?

Yes, you can.

Please do.

Okay, so I was.

I didn't know very much about fusion before this point.

I hadn't really read up that much about it.

I was filming a sequence about it for a show.

This is a few years ago.

And

for a series of reasons and catastrophes, including missed flights, etc., not mine,

the director was not there with us to film this sequence in the Tokamak.

So he sent through the script, and I was there with the cameraman and the sound guy.

And we were like, right, you know, on the top it said, go to the tokamak and film this interview.

So it was like, oh, a big panic.

And we went in, and there was this room, and they had loads of like fancy computers and like loads of nerdy physicists, and it looked really great.

I say nerdy physicists, there are people.

Sorry, I, I, there are core people, okay.

No, no, no, no, no, no, no, I proudly consider myself one of those people.

Thank you very much.

This is not you.

Uh, so there's like lots of people, it was all like really, really buzzing, this amazing space.

And so, I conducted the interview in that room, and just at the tail end of the interview, just as I was finishing, I was like, wow, I got this amazing conversation from the interviewee.

The director turns up very late, very flustered, and he's like, What are you doing?

You're supposed to do this in the tokamak.

And at that point, I realized I had no idea what a tokamak was.

Where were you standing?

In an office.

That's not a tokamak.

Okay.

Can I tell you the first time I went in the tokamak?

The only time.

Weirdly, it's a story that involves Tom Cruise.

Yeah.

Yeah.

So, okay.

Good clipboard.

Thanks.

Thanks.

I done some work on a film and the the um production designer uh calls me up every so often and says, do you want to help me out on this this next film?

And one time he phoned me up and said, I need a fusion bomb

and I need it to be quite small for a film I'm working on.

A fusion bomb?

Yeah, well,

even with my limited understanding of nuclear physics and particularly fusion, I did say, yeah, you know, that's not really a thing.

And he said, it doesn't really matter.

It's a mission impossible film.

And I went, okay, that's

So what I did is I called up a friend of mine.

He's called Steve Cowley, who runs, well, he's something senior.

He's very important.

He's a very important nuclear physicist down at the

Cullum.

Very important guy at the Cullum Rutherford Research Lab that I can't remember the name of probably.

Has he got the word Rutherford in the title?

It does it, doesn't it?

I'm looking to Melanie.

Doesn't it have Rutherford in there?

Oh, she's shaking her head, but as we've already established, she's not involved in this conversation.

Could you pull down the blind so we can't see her anymore?

Anyway, so I thought,

so here's a secret,

something that me and Hannah talk about quite a lot.

The only reason we like doing TV is because you get to go to really stupid, amazing places

that people don't have access to.

And I called up Steve and said, hey, look, Mission Impossible wants to make a fusion thing.

I didn't necessarily say bomb because that doesn't exist.

Can you take me and the crew down to have a look at the Tokamak reactor outside Oxford?

And he said, yeah, sure.

So we all went down there and he showed me around and it never made it into the film.

But I had a great day out.

And just like most clickbait articles, the payoff was rubbish.

Yeah, and I never worked on Mission Impossible films ever again.

Okay, before we get to Curie of the Week, we actually got some interesting responses to our first episode.

Oh, the case of the missing gorilla.

Absolutely.

Yes.

So one thing that you may have noticed or not about that episode was that we planted a little Easter egg for you in the form of Adam's little

what?

Adam's little what?

I'm on tender hooks.

I can't remember what we did.

Adam's little...

Bumhole.

Oh, bumhole, yes.

Yes.

No, it was a very deliberate.

It was a little...

test to see if you're paying attention.

It was.

It was our version of the gorilla.

I mean, it was Adam and Ilan's version of the gorilla.

Again, I had no part in this.

We should point out that editorial guidance and policy at the BBC is very strict, and we have to go through several tiers of very serious people who considered these things very carefully so that I can say, actually, whisper the word bumhole on radio four.

Did not think that it would get past.

I'll be honest with you, I totally thought that an editor would take it out at some point, which, frankly, is the reason why I let you get away with it.

But perhaps

the most delightful thing about this story

of popping a little bum hole in

the episode episode was the conversation in the office about precisely which word we should use.

Because actually, you know, you've got to be careful about, we wanted it to be something just cheeky enough that you would notice it,

but not too rude.

So

here's a little recording of what we're talking about.

But we can say bumhole.

I feel like bum hole is

surprising.

Bum is a bit too tame.

Bumhole is like, ooh, a little bit

enough to get your attention.

It's balls.

That's balls.

That's manballs.

No, but it's just

impressive.

Bunball is cuter.

Great.

I'm asking Hannah to stop that because that's just too much.

But

we know that the producers and the senior management of the BBC don't listen to the podcast, so we can just get away with anything

in this bit.

Very serious programme.

Yes.

Now, you might remember, actually, in that episode, we also heard from Professor Polly Dalton, who told us about research on inattentional numbness.

So this is the idea where you miss tactile stimuli because you're focused on something visual.

And the flip side of that is that people tend to close their eyes when they want to focus, for example, when they're snogging.

Yes, well, a vet called David Hannum wrote to us to share his version of this story.

Oh dear.

He says, it's not about snogging, and I wish it was.

He says, closing my eyes when I was sorting out a particularly complicated and difficult calving, which I presume is giving birth to a calf.

Yes, or I believe helping a heifer give birth to a calf, more specifically.

Right, he wasn't giving birth to a calf because that would be weird.

Obviously, I couldn't see what I was doing, but closing my eyes helped me concentrate on what I was feeling to sort out the malpresentation.

Presumably he had his arm

inside the heifer.

In there, oh, I see.

So there he was with

elbow deep.

That closes his eyes to feel better.

Lol yuck.

Thank you, David.

That's a brilliant story.

I enjoyed that.

I enjoyed that.

Let's move on to a very sweet message, which is the curio of the week.

Absolutely, Absolutely, because Adam and I made it into the acknowledgement section of a published paper.

Dear Professor Fry and Dr.

Rutherford, I am a theoretical physicist working in industry in Germany.

Since I left academia, I found plenty plenty of free time, which I used to learn in depth whatever I found interesting.

I got obsessed with the terrifying beauty of nuclear explosions.

Around this time, I also happened to discover the curious cases, which I could not stop listening to.

You were loyal partners while I was solving long and complicated systems of partial differential equations, aka having fun.

Well, for you and Hannah.

Maybe.

George, you and me, we are cut from the same cloth.

Anyway, long story short, he was searching for declassified military documents for the valuable data of blast waves produced during nuclear weapons tests during the 1950s to validate his results.

And while he was filling those pages with equations, he was listening to the ASMR cocktails, to learning to respect wasps, laughing at Adam's Canadian raccoon and daydreaming about heating your space burrito with a nuclear bomb.

And so, after months of work and some novel results, he submitted his results for publication in a scientific journal.

And please find attached our copy of our scientific article that has just been published in the journal Shockwaves.

The acknowledgement section includes a brief but heartfelt thank you for your company.

JSD acknowledges the delightful company of H.

Fry and A.

Rutherford with their curious cases during most of this work.

I mean, that's wonderful.

Thank you.

That was from Dr.

Jorge Diaz.

And

I mean...

He was doing this research into nuclear explosions whilst drinking cocktails and thinking about raccoons.

I don't...

How did he concentrate?

I cannot do equations with anything other than white noise.

No, and I don't do equations at all for similar reasons.

Anyway, thank you, Jorge.

That's very kind of you.

More acknowledgements in academic papers, PhD theses.

Basically, it's just our sort of slow and subtle 20-series attempt to infiltrate the entirety of the science world.

Slowly, but surely.

And we'll be back for the next series of Curious Cases

probably after Christmas Day when Adam and I finally have a space in our diaries.

But until then, send in your questions to Ilan at curiouscases at bbc.co.uk, and we will see you in the new year.

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