The 12 Scientific Days of Christmas

The Naked Scientists celebrate the holidays with the 12 scientific days of Christmas. From why 9 ladies like to dance to making those 6 geese eggs into bouncy balls...
20 December 2016
Presented by Chris Smith, Graihagh Jackson
Production by Caroline Steel.


Supported by an all-star scientific cast of luminaries and willing volunteers the Naked Scientists celebrate the holidays with the 12 scientific days of Christmas. From why 9 ladies like to dance to making those 6 geese eggs into bouncy balls...

In this episode

Christmas Reindeer

00:00 - Twelve Scientific Days of Christmas

A hoard of science-hungry academic luminaries join the Naked Scientists to celebrate Christmas

Twelve Scientific Days of Christmas
James Bowers, Eleanor Drinkwater, Alan Calverd, Hugh Hunt and Amy Thomas

Joining Chris Smith and Graihagh Jackson are biochemist and science communicator James Bowers, bird expert Eleanor Drinkwater, Cambridge engineer Hugh Hunt, psychologist Amy Thomas, and physicist Alan Calverd. And what are their tales of joys and woes of Christmas past?

Pear tree

On the first day of Christmas...
Hugh Hunt, Alan Calverd & Amy Thomas

Chris Smith and Graihagh Jackson, joined by a host of festive luminaries including Hugh Hunt, Alan Calverd and Amy Thomas are exploring the scientific side of the festive period...

Graihagh - This week we’re celebrating each of the 12 days of Christmas with a science experiment.

Chris - And how’s your singing, Graihagh?

Graihagh - Let’s find out with day 1. A partridge in a pear tree. Ready everybody? I’ll lead us in.

Everyone sing: on the first day of Christmas my true love gave to me, a partridge in a pear tree

Graihagh - So we have a beautiful pear tree (sort of) here in the studio! Well actually it is a lavender with white flowering the odd pear hanging from it, but it will suffice! I thought we would start by making our own snowflake decorations for the tree. So in front of you you should have some paper and scissors. Let’s get cutting! It’s like being back at school and making paper chains... So Hugh, you’re a physicist, could you start off by telling us how snowflakes form?

Hugh - Snow is made of water, and water molecule H2O has an oxygen with two hydrogens, and the angle between the hydrogen atoms is about 120 degrees. But it’s only approximately 120 degrees, isn’t that right Alan

Alan - Yes, it’s actually about 110 degrees, which is possibly why no two snowflakes look exactly the same.

Graihagh - I was going to say, does that matter the angle? Is that what causes them to be like fingerprints and be completely individual?

Alan - I think the old idea was that it was the hydrogen bond angle that determined the hexagonal shape but because the hydrogen bond angle doesn’t make a hexagon, we’ve got to think of some other reason why the come out that shape.

Hugh - You can kind of think that this 120 degree angle, it’s like the angle you get in a boomerang. So you can imagine three boomerangs connecting together makes this kind of hexagon shape and that’s the kind of base building block of a water crystal. And if you imagine drawing a snowflake, you might start by drawing three dissecting lines like an asterisk, and then at the end of each line you might draw another asterisk, and then at the end of those little lines you can draw another asterisk. You keep on adding…

Graihagh - You just keep going for ever and every.

Hugh - And if you ask five different people to draw using those instructions, you’re going to get five different snowflakes because they’re going to draw their asterisks at randomly different places. So every snowflake's going to look different.

Graihagh - But why do they stop growing, is there a moment when they stop growing?

Hugh - Well the water is coming out of the atmosphere, and they’ll only grow when there’s water vapour in the atmosphere around the snowflake, and once the snowflake has formed and the air is just a little bit drier around. Snowflakes need very particular conditions to grow in and amongst those conditions don’t exist anymore they stop growing.

Graihagh - Yeah. I suppose it’s hoping for a white Christmas this year, what do you reckon?

Hugh - I think the weather forecast is a bit blustery for Christmas I think.

Graihagh - I haven’t actually looked… I don’t know. I always want a white Christmas because I always want to go outside sleighing. And I remember thinking we did this every year when I was a kid but, actually, that never seems to happen any more. I thought climate change was supposed to be happening. I mean, why isn’t there any snow?

Hugh - Well, you could do what you do in Australia at Christmas time because it doesn’t snow then. So it make snow out of mashed potato.

Graihagh - How much mashed potato do you need to…

Hugh - I was only kidding!

Graihagh - I was going to say that must be a colossal amount of potatoes.

Chris - Amy, tell us about the psychology behind all this -what makes an aesthetically pleasing snowflake because I want to win this competition? So I haven’t started cutting yet actually, so I might start now.

Amy - I think as we’ve heard about how they grow and crystallise and the hydrogen bonds are able to form sort of hexagonal shape. And hexagons are quite prevalent in nature and symmetrically, obviously, is something we’re quite in tune with as humans.

Graihagh - Why are we particularly fond of…?

Amy - I think it because there’s some mathematical reasoning behind hexagons. When they fit together you’re maximising your area but minimising your perimeter. So, if you have like a beehive and you’re making honeycomb, it’s more energetically favourable for the bees to make hexagonal shapes by reducing their perimeter but maximising their area.

Graihagh - Okay. So I want something as symmetrical as possible, basically?

Amy - that’s what you should go with.

Graihagh - And that’s how I’m going to be onto a winner.

Amy - Symmetrical and hexagons, I think that’s where you should start off from.

Chris - It’s a bit late for me now. I wish I’d known that five minutes ago.

Graihagh - And Alan - very briefly, I’ve heard that all snowflakes are different, just like a fingerprint. Is this true?

Alan - Probably. I think it must have been about a hundred years ago, a couple of Canadian scientists collected snowflakes and photographed them. And they published books containing thousands of snowflake photographs, no two of which are alike.

Graihagh - Wow! And they had to trawl through every single one of them to identify the fact that they’re not alike?

Alan - I remember this was an exam question in crystallography 101, which said “the average snowflake is less symmetrical than the average photograph of a snowflake” and I think there may be a lot of selection bias in what actually goes into the photograph of a snowflake.

Graihagh - Okay - mine’s not gone very well. I’ve only just barely cut a hexagon. Oh wow that’s amazing.

Chris - Some amazing results here!


10:24 - Four calling birds...

Do bird's recognise each other's calls?

Four calling birds...
Alan Calverd, James Bowers & Hugh Hunt

How good are you at recognising birds by their songs? For our second, third and fourth scientific days of Christmas, Chris Smith asks avian expert Eleanor Drinkwater to put guests Hugh Hunt, James Bowers and Alan Calverd to the test...

Chris - Now Christmas is all about games, so to celebrate these bird-themed days of Christmas, we’re going to play guess the bird call. Have a listen to this...

Chris - Any ideas - four bird calls, so four points up for grabs. Hugh’s up for it go on...

Hugh - I didn’t hear a Kookaburra.

Chris - It’s a good start Hugh. You’re very good given it’s not an English native.

Hugh - You didn’t say they were English natives, did you?

Chris - Well we recorded them in the street. James - what do you reckon then?

James - I don’t know. I thought number four felt a little bit pidgeony and so maybe…

Chris - James gets a hint of pidgeony in there.

Alan - you like eating all these birds, I’m sure, but what do you think about listening to them?

Alan - I think the most obvious is probably the robin which was number one. It’s a good mouthful!

Chris - Okay. Not a very big mouthful though. Eleanor - you’re the bird expert. I’ll play each of them in turn again and you can tell us which one. So this was number one:

Eleanor - That’s a blackbird.

Chris - So Alan was wrong.

Eleanor - I’m sorry.

Chris - He said Robin. Okay number two:

Chris - Partridges - I didn’t get that. Did anyone else get that? Partridges normally make a different noise when they’re running across the fields near me. Really, was that a Partridge?

Eleanor - Yes.

Chris - Okay number three::

Eleanor - So that would be a chicken.

Chris - Okay. No-one got that one. This is the last one:

Now James’ money - he said pigeon-ish.

Eleanor - Pigeon-ish. Well my money would be on dove.

Hugh - Don’t tell me there’s a Christmas theme to this, is there?

Chris - Pigeon; dove, They’re quite similar though, aren’t they? You can tell them apart though because they do sing differently , don’t they. Because I heard a radio programme once and it stuck with me forever more because this person said “pigeons sing with five syllables and doves sing three syllables.”

Eleanor - Well, I haven’t heard that, but I can tell you that the RSPB says that there’s no clear distinction between pigeons and doves. They’re from the same family and what’s more you know the grey flappy things that steal you sandwiches, that we call pigeons, they’re actually the feral version of wild rock doves. So we call them pigeons but, actually, they’re really doves.

Chris - Because the argument this person put forward to me was the doves sing with three syllables and you can think of a bit like they said “a jaded soccer supporter - u... nit... ed, u... nit... ed. And they said pigeons are five and they said “my toes are bleed… ing,  my toes are bleed… ing.”  And actually it does work. I’ve identified many pigeons and doves off the back of that. And I guarantee that meme will stick with everyone! But, why do birds do this? We all take it for granted birds sing, reach out to each other. What are they trying to communicate?

Eleanor - Well, a whole range of different things. some of them are defending their territories, others are telling you how attractive they are. Sometimes they’re actually practicing their songs, and other times they use it for bonding. In fact, when they’re bonding, birds like budgies actually copy each other. Or other ones have sort of gang calls which they have in particular and other groups don’t, like Australian magpies.

Chris - They must be born with a song otherwise you wouldn't be able to say, oh that’s a blackbird or whatever because birds do have similar songs within their species. But what you’re saying is they learn that from other members of their species or they’re born with it and they adapt it?

Eleanor - It’s a bit of nature and nurture. So some parts of the song seem to be quite intrinsic and other parts of the song seem to be learnt, or at least a little bit of practice before they’re ‘top notch.’

Chris - Can birds recognise each other from their songs? So I can tell when one of you is speaking and I can can recognise just from the sound of your voice without looking at you who it is. So, can a bird do that.

Eleanor - Yes. In fact, there was a hilarious experiment done on pedal in which they got a recording on one particular pedal and played his alarm call again, and again, and again to his friends. And, eventually, they stopped reacting to his alarm call. It’s almost like the boyd calling wolf. Yet they’d still react to alarm calls from other individuals. So, yes, they can tell each other apart.

Chris - And this whole business of when penguins, taking a Christmas card analogy -  totally wrong because they’re from the wrong part of the planet of course, South Pole. But they find their young in amongst thousands of individuals when they come back. So how do they do that? Is that from calls or is there a smell, or other things?

Eleanor - Well, I’m not a penguin expert, unfortunately, as much as I’d like to be.

Chris - How dare you turn up on this Christmas edition of the Naked Scientists and not know about penguins.

Eleanor - I’m sorry. But I guess the call would be very important to that.
Chris - Eleanor Drinkwater; thank you!

Gold rings

15:49 - Five gold rings

Alan Calverd tells us about some interesting gold rings back in science history...

Five gold rings
Alan Calverd

Graihagh Jackson and Chris Smith are celebrating the 12 scientific days of Christmas, assisted by Hugh Hunt, Amy Thomas, James Bowers and Alan Calverd...

Graihagh - Moving swiftly on from bird calls to rings, it is of course time to celebrate the 5th day of Christmas...

   Everyone sings: on the fifth day of Christmas my true love gave to me five gold rings, four calling birds, three French hens, two turtle doves, and a partridge in a pear tree...

Chris - Alan Calverd, you’ve been looking into some famous gold rings in science history. What have you got for us?

Alan - I think possibly the best known gold rings in physics and medicine were the ones on the hand of Mrs Roentgen. Wilhelm Roentgen discovered X rays in 1895 and published X ray a photograph of his wife’s hand with, apparently, one very thick wedding ring on it. I’ve tried to get a reasonable copy of this photograph, and I’m rather baffled. I’ve now come across five different images, each of which claims to be Anna Bertha Roentgen’s hand with a wedding ring.

Chris - She must have a lot of hands!

Alan - Yeah. The one I think is most likely is actually of her right hand with what appears to be two quite thin rings on it. I’m still not entirely convinced. the photograph that most often appears in textbooks is of a left hand with a thick wedding ring on the ring finger. And it appears to be signed and has some sort of provenance. The problem is is that the German tradition is not to wear to rings, but to have one ring on engagement and on marriage it’s transferred from the left hand to the right hand. So now I’m prepared to believe that the likely photographs of Anna Bertha Roentgen’s hand are actually of her right hand. And I’ve now found one which is paired with a photograph of a slightly chubby woman with fairly small hands who seems to have a single thin ring on her right hand and, I believe, that’s probably the only actual photograph.

Chris - Do you not think that she was exposed to so many X rays that she just grew fifteen extra hands and that could account for the anomaly?

Alan - No, this was definitely the first X ray ever published.

Chris - I also like the way he experimented on his wife and didn’t do it on himself.

Alan - Yeah.

Chris - Interesting, obviously a brave physicist. Hugh…

Hugh - Can you actually tell that they’re right or left hands. The X ray could be flipped upside down on the photograph?

Alan - All the radiology textbooks say you always do it from the top downwards.

Hugh - Ah, so there’s some logic...

Graihagh - And James, what gives gold its special properties? Why do we like to wear it as jewellry?

James - Gold is interesting because it’s not interesting at all, really.

Graihagh - an oxymoron?

James - Yes. Because in terms of chemistry it’s actually really unreactive, which is why we can use it for so many things, and it’s actually quite easy to extract compared to other things we might use. But also that means it could last for a very long time so it’s a very good kind of measure of wealth, for example.

So, if I had a gold bar and I had it for a hundred years, it wouldn’t really change. Whereas if I had and iron bar, for example, it would probably get rust on it which is iron oxide because the the iron is reacting with the oxygens. Gold doesn’t really do that, and it’s just very malleable, it’s very easy to use, but it’s also just rare enough so that everybody can have some, but not too much.   

Chris - Amy - can you tell us about the psychology of gold though, because there’s no doubt about it, for generations people have found gold particularly valuable and attractive? So why do people a) like gold, and b) like jewellery full stop?

Amy - Oh, there’s a few  different theories about this. And I think one of the reasons why people like jewellry in general is because it can signify things which might be a little bit awkward to communicate with words. So, for example, a wedding ring perhaps; it’s there, it’s a symbol of marriage already, you don’t have to say it, it’s already there. So that’s already like a nice body que that you don't have to tell people.

Also, if you wear a necklace, you might want to draw attention to specific areas but not want to say it. so for that reason…

Chris - I’ve never thought about it like that but you’re absolutely right!

Amy - Yeah. It’s kind of like this underlying subtle signal thing, which is really cool. But then there’s more anthropological reasons to jewellery and gold is status, and monarchy, a sign of wealth. And also a sign of love and belonging if it’s something that’s bought for you by something that you love, and you wear it and you feel loved and that you belong to someone.

Chris - Wonderful! I wonder what I’m getting for Christmas...?


20:39 - Six geese are laying

What happens to a hen's egg left soaking for a day or two in vinegar?

Six geese are laying
Hugh Hunt

Graihagh Jackson and Chris Smith are celebrating 12 scientific days of Christmas with the help of Hugh Hunt, Alan Calverd and Eleanor Drinkwater.

Graihagh - Are we ready for the 6th day of Christmas? Our voices should be really warmed up by now...

Everyone sings: on the sixth day of Christmas my true love gave to me, six geese a laying, five gold rings, four calling birds, three French hens, two turtle doves, and a partridge in a pear tree.

Graihagh - So we are back to birds again. But this time not bird calls but bird eggs. Our producer this week, Caroline Steel, has put raw and uncooked chicken eggs in some vinegar for a few days and the results are interesting to say the least! We’ve got a couple here. It’s changed colour! There’s no shell on it anymore. It’s kind of squishy, a bit bouncy, I would say naked. Hugh - can you explain why it has gone all naked and bouncy?

Hugh - Well, the vinegar, it’s an acid; and the egg shell is made of calcium carbonate. And I remember learning at school that "acid plus carbonate gives salt, carbon dioxide and water". And as these eggs were sitting in the vinegar, there were bubbles of what must have been carbon dioxide on the outside. Now, all of that carbonate - all of that shell - has now gone, and it’s very "squidgy".

Graihagh - It is isn’t it? You're "squidging" it and I’m rather nervous you're going to break it.

Hugh - What’s left is that membrane. You know when you have a hard boiled egg, and you peel the hard boiled egg, there’s this membrane that’s between the shell and the egg itself. That’s the only thing that’s left.

Graihagh - That’s the only thing that’s holding it together. Rather delicate. What is that membrane for?

Hugh - Well it’s a seal, an air seal, a water seal, because the shell, the calcium carbonate is fairly porous, so without that seal the egg inside would dry out.

Graihagh - Ah, I see then. And before the programme you mentioned to me about this is relevant to climate change and the oceans. And I thought no -  because eggs aren’t found in the sea. So what were you getting at there?

Hugh - Well, this shell has dissolved in the acid of vinegar and we know that the oceans are becoming more acidic because carbon dioxide levels in the atmosphere are rising. So the acidity of the oceans is rising and that’s making it more difficult for shellfish to create the shells. So one of the real worries for ocean acidification is the threat on the marine life, particularly shellfish.

Graihagh - Um, you get things like this. I’m going to pass it round so that everyone can have a feel. Don’t break it - please be careful!  Your hand will smell very vinegary afterwards, I warn you.

Graihagh - Eleanor - do we know why birds lay eggs instead of live young like mammals?

Eleanor - Well, that is actually a fantastic question. Except for lamprey and hagfish, birds are actually the only vertebrate group that don’t have any live young and people don’t have a definitive answer as to why this is. There’s lots and lots and lots of suggestions, one of which is it might make it difficult to fly but, then again, we have lots of flightless birds. Other people have suggested it might be to do with immune function. Still others have suggested that it might be to do with lung formation or the eggshell itself.

My personal favourite, however, is the idea that birds have quite complex caring behaviours. So you will have two parents who will tend to care for the young and the females tend to be adapted to lay one egg at a time. So, from the female’s perspective, it seems like a good idea to try and get the egg out of you as quickly as possible because then the male can also invest lots of time and energy looking after the offspring rather than the entire burden being on her.

Chris - You mentioned things that do or don’t lay eggs. What about platypuses and echidnas - the duckbilled platypus because they lay eggs don’t they but they’re not birds and they’re not fish?

Eleanor - Yes, they’re just strange. we don’t talk to them.

Chris - Did they evolve to do that independently - how did they get that skill?

Eleanor - I don’t know. They’re also very odd. They’re one of the only poisonous mammally type things. Even though we call them monotremes, they don’t really fit neatly into anywhere.

Alan - I often wondered about - what about snake eggs? That’s a wholly different species and they’re very similar eggs.

Eleanor - Well, yes. But snakes also have instances where they have live young, so unlike birds where you only have egg laying. You do have some snakes who give birth to live young.

Hugh - But this is proof of which came first - the chicken or the egg. Because we know that dinosaurs laid eggs so, therefore, the egg came before the chicken.

Graihagh - Ahh. Glad we got that sorted!

So do birds serenade their eggs? You talked about birds practicing their singing and you often think of them stereotypically in a tree with their nests and their eggs. Is there any reason why they might be doing that?

Eleanor - Yes. Well, in fact, there was an amazing study that’s only recently been done that showed that zebra finches, when it’s over 26 degrees they have a particular call which they make to their eggs. Now what scientist did, they took a group of these eggs; half of them they played the song two, half of them they didn’t. And then they looked to see what happened when the birds started developing. And what they found was very strange in that those that had been played the call would develop slower and would end up smaller at higher temperatures than those that hadn’t been played the call. So the call from the mother caused changes to their physiological development after hatching, which is quite extraordinary.

Graihagh - Yes, I was going to say absolutely amazing.

Chris - Why. Why is it good to do that?

Eleanor - They put it down to the smaller size being better adapted to hotter environments so it was easier for the chicks to regulate their heat. And also, interestingly, when these chicks grew up they found that they were much more successful as smaller adults, producing more babies in higher temperatures than the ones who weren’t.

Graihagh - Aw, absolutely fascinating. I know Hugh, you’re playing with the egg here and I know you really want to pop it.

Hugh - That would be great!

Graihagh - So, do you want to do the honours and pop it?

Hugh - Alright.

Graihagh - Let's get a photo of it and we can put it up on facebook live.

Hugh - Well, I used to say the scissors that we’ve been using to make snowflakes...

Graihagh - I feel like you’re a bit close to me still!  They do smell really bad actually.

Hugh - Yeah. Okay, well are we ready?

Graihagh - Okay, are we ready? And pop…

Hugh - Awww. Urgh!

Graihagh - What’s interesting is the membrane looks like saggy skin, doesn’t it, around the thing? Hugh - I can’t believe you're touching it. Why are you touching it?

Hugh - Actually that membrane is just like the skin of a grape and it’s just this thin. Amazing, isn’t it?

Graihagh - Yeah. Keep it away from me!


27:28 - Seven swans are swimming

Why do some people also enjoy a cold dip at Christmas?

Seven swans are swimming
Alex Harper, Eleanor Drinkwater

Seven swans went swimming, according to the song. And some people also enjoy a cold dip at Christmas. Caroline Steel went for a swim in the name of science, and Chris Smith heard from Eleanor Drinkwater how birds avoid getting cold feet...

Chris - So far we’ve covered 6 of the 12 days of Christmas… Now it’s time for the 7th...

Everyone sings: on the seventh day of Christmas my true love gave to me, seven swans a swimming, six geese a laying, five gold rings, four calling birds, three French hens, two turtle doves, and a partridge in a pear tree.

Chris - Even at this time of year when it’s freezing here in Cambridge, it’s common to see swans swimming down the River Cam. But there are also people who enjoy swimming outdoors at this time of year. So we sent producer Caroline Steel to the pool in Tooting, London, to break the ice - almost literally - and take a dip with cold water enthusiast Alex Harper...

Alex - You can imagine being in a spar and you go in a plunge pool and you get a rush from it.  Well this is exactly the same kind of rush. It’s definitely getting cold, and getting warm in the sauna and getting cold again. It’s a huge endorphin release, or certainly a high buzz.

Caroline - Given that I don't think I’ve actually swum in about six months, what do you think will happen to me - how am I going to feel?

Alex - Well, we’ll walk in. but it’s up to you, you can walk or jump. I suggest walking down the steps and you will feel cold. It’s cold water and there’s no getting away from your skin will cool down, and mildly painful, but, honestly, it is mental. Physically you'll be fine, it’s the mental anguish of feeling cold, feeling uncomfortable.

Caroline - Okay. So before you hear my reaction, I just want to emphasise that the water was less than four degrees celsius. Actually, it has frozen over just three days earlier. Okay, so excuses over it’s time to jump in…

Okay, so I’m as ready as I can possibly, physically be.

Alex - Excellent.

Caroline - Is your plan to go in first and…

Alex - Do you want to go in first? Do you want to go in? And we go… no hanging around. Okay, so just get in.

Caroline::. So obviously, it was pretty cold. My skin cooled down straight away and, as my blood vessels constricted, I went really pale. But by the second length my skin went numb and it became marginally bearable.

Alex - Excellent. How was it?

Caroline - I feel like I’m not completely with it. But I enjoyed…

Alex - You did it. You finished. Well done!

Caroline - I enjoyed the second leg.

Alex - You could have done two more, couldn’t you?

Caroline - Phew, phew. Oh my Gosh!!

I’m on a beach, it’s boiling, it’s so hot that I actually want to go in the sea. I need to put on more sunscreen, I’m burning. It’s boiling… it’s boiling.  Okay, so as much as I wanted to believe that, it didn't really help me warm up. So here’s cold water enthusiast and doctor, Martin Thimbar...

Martin - Well, the dodgy thing is you get a warm glow. You often get a feeling of a warm glow after you’ve been in there, which is deceptive because, actually, it’s going to mean you lose quite a lot the heat. And so the thing to do with anyone who's a bit cold and that is put layers on. People sometimes make the mistake when they’re really quite cold of going into a hot shower and standing up. That doesn’t warm your core quickly enough but what it does do is it encourages your blood vessels on the side to dilate, and you blood pressure can drop down. So when people faint, they can faint from being cold and then having a hot shower. The best thing to do is just sit quietly and put layers on.     

Chris - Good advice. Eleanor - How do swans manage to swim in 3 degrees C water?

Eleanor - They have an amazing system called the countercurrent exchange system in that their veins and arteries are very, very close together - those going down to the foot and those going away from the foot. So you have this amazing system where the warm blood from the body gets cooled by the blood going in the opposite direction, so when the blood gets to the foot it’s already cold so the bird doesn’t lose that much heat.

Chris - Neat. So by basically pumping hot blood out of the body and passing it very close to cold blood coming back, the cold blood grabs all the heat from the hot blood so by the time it gets to the foot it’s so cold it’s not got much heat to lose. So it stays as cold as the foot was without the bird actually losing any energy?

Eleanor - Yeah, that’s exactly right.

Hens eggs

32:02 - Eight maids are milking

Will the alcohol kill off any Salmonella in my eggnog?

Eight maids are milking

Everyone sings: on the eighth day of Christmas my true love gave to me eight maids a milking, seven swans a swimming, six geese a laying, five gold rings, four calling birds, three French hens, two turtle doves, and a partridge in a pear tree.

Chris Smith and Graihagh Jackson sample some eggnog in the company of James Bowers, Hugh Hunt and Eleanor Drinkwater...

Graihagh - So for the 8th day of Christmas we’ve got some wonderful milky eggnog for us all to have a try. So. I’ll pour some out for everyone to try

James, apparently you’re a bit of an eggnog expert. I can smell the brandy. What’s in eggnog?

James - It’s made up of, obviously, eggs - lots of eggs. Milk or cream and a fair amount of sugar which is often mixed with some rum, bourbon, whisky or other alcoholic…

Graihagh - I can definitely smell it. I’m going to start passing these down. Here you go Hugh, are you an eggnog fan?

Hugh - Mmmmm

Graihagh - That sounds promising James. One for you and Alan as well. there you go Chris, do you want one as well?

Chris - Is this homemade, Graihagh? Did you make this?

Graihagh - Caroline’s made it for us. Here you go Chris one for you. How many are we short - who hasn’t got one? Alan okay, you’re in need of one.

It's a rather weird concoction. So what’s the story, why does this exist?

James - Apparently, back in the day, a long, long time ago. Even back to the 1300s things like milk and eggs were really sought after because it was only really the rich, upper classes that could afford to drink and eat those things.

Graihagh - And presumably alcohol as well?

James - And alcohol as well. So there was this drink that was call posset, which was drunk by the upper classes and then later on…

Chris - Doesn’t that mean a baby vomiting?

James - Posset.

Graihagh - I was actually thinking of possums. Something completely different.

James - And eventually, in the 1700s that got developed into where they were adding wine and beer to it.

Graihagh - Wow!

James - They think the name ‘nog’ comes from, there’s two different things. Beer from East Anglia at the time was called nog, or noggin was also the name of the cup we would drink alcohol out of at the time. I guess, somewhere along the line, that ended up in America and stuck a little bit more over there than it does here. Because in America, they tend to drink a lot more eggnog over there at Christmas than I think we do in the UK but they held onto it more than we did.

Graihagh - What does everyone think - should we reintroducing it to our Christmas holidays?

Chris - It’s lovely. I’ve never had eggnog before.

Eleanor - I quite like it.

Hugh - Well, I’ve got plenty of extra egg here if anyone would like some more.

Graihagh - Speaking of raw eggs - I remember my granny never let me eat the raw mixture. She’d never let us lick out of the cake bowl which I was always disappointed about. So is this sort of thing safe to drink?

James - The danger with raw egg is Salmonella.

Chris - Hang on… You’re asking us this question after we’ve all just necked some of it.

Graihagh - And I also haven’t had any of it yet so I’m waiting.

Chris - I did notice that.

Graihagh - Bated breath basically.

James - The danger with the Salmonella in the raw egg, even up until the 80s or 90s and early 2000s, it was said that as much as one percent of all the eggs that were tested could, potentially, contain Salmonella. Which might not sound like a lot but it’s one in a hundred eggs and it’s still quite a lot and quite a high risk of Salmonella. So it’s much safer to eat pasteurised eggs because that kills off most of the bacteria that would be in there. But these days the Food Safety Agency in the UK is saying that it’s a lot safer now to be eating raw eggs and the possibility of getting Salmonella from a raw egg is much lower than it used to be even ten years ago. Although you do need to be careful of Salmonella and things like that so probably best not to eat too many.

Graihagh - Chris, with your other hat on - you're a microbiologists at Addenbrooke's hospital - do you find you get many cases of Salmonella?

Chris - No, thankfully, the numbers are extremely low these days. Back in the 80s when people were worried about Salmonella in eggs there were thousands of cases but that's because, and the number has come right down, is because there’s a good vaccine which is administered to farmed chickens and it stops them having Salmonella. There is another bug they can carry called Campylobacter, but that’s something quite different. But the number of Salmonella cases is now vanishingly rare, so we can actually assume that raw eggs are probably absolutely fine now. The risk is extremely low.

Hugh - Where does this word Salmonella come from? It sounds like it originally came from fish.

Chris - It does, doesn’t it? And I don’t know what the origin of it is. I know who typhoid Mary was though and I wouldn’t want to make friends with her!

Graihagh - Well, as you guys tuck in after that egg-cellent bit of science, we’ll move on to our next day of Christmas...

Pole dancer

Nine ladies dancing
Amy Thomas, science communicator

Psychologist Amy Thomas explains to Chris Smith why humans like to jive, and what constitutes a "good" dance with musical accompaniment from Hugh Hunt...

Everyone sings: on the ninth day of Christmas my true love gave to me nine ladies dancing, eight maids a milking, seven swans a swimming, six geese a laying, five gold rings, four calling birds, three French hens, two turtle doves, and a partridge in a pear tree.

Amy - There’s a few theories about this. One of the main ones is that dancing is a mate selection gesture. There’s been studies done on looking at the relationship between the symmetricality of one's body and their ability to dance. And what they found out was that people with symmetrical bodies are better dancers, quite substantially.

Chris - Why?

Amy - I think it’s because of the way you balance, and you can move, and you're more flexible, and it looks more aesthetically pleasing when your body is symmetrically. If your hands are exactly the same size and your legs are exactly the same size, it’s going to look better.

Chris - Are you going to show me what I need to do better then in order to impress this Christmas?

Amy - Yes. I’ve got a little experiment to do to show you how to improve your dance skills.

Chris - What have you got in mind?

Amy - I’m going to stand up and do one dance, which is a bad unattractive dance. And then I’m going to do one dance which is an attractive dance and you’re going to tell me which one’s which.

Chris - Now I happen to know that Hugh Hunt is a very good human beat box so we’re going to get him to do the musical accompaniment for you Amy. so if you’d like to take to the dance floor, which is this patch of carpet behind my chair. So we're not going to know what order these dances are coming in. They could be the unattractive or the attractive one so could we just cue the music please Hugh. If you could kick us off with a little rhythm..  A bit more invigorating than that.

Hugh - Bum bum bum, ber dum dum  dum ber dum.

Chris: - We’ve got a bit of hip swaying action happening. The arms are outstretched like a Jesus Christ posture with fingers extended and palms out. So I’m seeing palms being presented to me and she’s looking straight out surveying the vista. Okay, is that dance one?  We need a different tune for dance two.

Hugh - do do do dodo do do do.

Chris - Okay so this is a very vigorous dance. There’s a lot of shoulder action happening here and sort of twisting of hips and arms are moving around. It’s not symmetrical at all. Okay, thank you very much. Very hard for you at home to picture what Amy was doing in dance two. It was quite hard for me to picture was Amy was doing in dance two. Alan, what was your observation?

Alan - Well, Amy was wearing a full length chiffon lab coat, brilliantly decorated with forty thousand sequins sewn on by her mum.

Chris - Is this a nod to the good old days of sexist British television?! What did everyone think then? What did we think about the attractiveness of the two dances? Graihagh - what is your instinct telling you?

Graihagh - Well, the first one was definitely more controlled I would say, and the second one was a bit more sort of loose, wasn’t it. And you’re smiling much more in it which makes it kind of more attractive to me because you're laughing, you’re smiling.

Chris - So your money’s on number two?

Graihagh - I’m going for number two.

Chris - Hugh…

Hugh - Arms higher up above the shoulders as opposed to arms lower down. So the second one had more arms up than arms down.

Chris - James - your thoughts for the judging on that side of the…?

James - It’s weird because the first one was a lot more symmetrical but it just felt a lot more robotic. We were just saying that symmetry is kind of attractive but, at the same time, it didn’t feel like I was enjoying it as much as…

Chris - So Amy, put us out of our misery. Of the two dances, which one was ostensibly the attractive dance and what are the go to points for people to bear in mind on the dance floor this Christmas at the office party?

Amy - I can safely say that you guys were correct. The second one was supposed to be the attractive dance and I’m happy that that worked. And it’s interesting because they have actually pinpointed it to specific movements in the body.

There was an experiment done a few years ago looking at particular movements of the body and they rated the attractiveness of the dance, and these were variation around the central region of your body, so if you’re doing isolations to the rib cage, that kind of thing. Quicker foot pace as well. So you notice in the second one I was speeding my feet up.

Chris - You did have to compete with the music a bit, but…

Amy - Yeah, I know. It was hard.

Chris - You did well under the circumstances.

Right so you’ve got have movement around the ribcage, move your limbs, feet..

Amy - Feet quicker.

Chris - Hands?

Amy - Hands - what you want to do is get variation in your dance moves. So as James said about the first one being a bit symmetrical, a bit boring, that has been scientifically proven in that you have to have variation in your dancing otherwise it’s not attractive and it’s boring.


42:05 - Ten lords are leaping

The science of how things spin and bounce...

Ten lords are leaping
Hugh Hunt, University of Cambridge

The science of how things spin and bounce goes under the microscope for the tenth scientific day of Christmas. Hugh Hunt demonstrates for Graihagh Jackson...

Everyone sings: on the tenth day of Christmas my true love gave to me ten lords a leaping, nine ladies dancing, eight maids a milking, seven swans a swimming, six geese a laying, five gold rings, four calling birds, three French hens, two turtle doves, and a partridge in a pear tree...

Graihagh - So we’re up to the 10th day of Christmas - and our “lords a leaping” are bouncy balls today; engineer Hugh Hunt is an expert on how things bounce and roll. It seems like an interesting profession choice Hugh?

Hugh - Well, I don’t actually do much bouncing of balls but I do lots of stuff with spinning things.

Graihagh - So what are we going to be doing today. We’re getting down on our hand and knees onto the floor. So this is the name of science, this is a lot of dedication. Okay.

Hugh - And I’ve got various balls here - bouncy balls, and snooker balls, and billiard balls, and footballs, and ping pong balls. But what I want to do is to take one of these balls and roll it towards a wall. Just roll it along the floor just as a snooker ball might roll along the table and it’s going to hit the wall. And you might think it might just bounce back ordinarily, but what it does is it leaps up into the air and then lands a little way away from the wall, it just doesn’t roll back. Now you can do the experiment - I’m rolling the ball now… and you can hear it bounces twice. There’s one bounce where it hits the wall and another bounce where it hits the floor. You hear bump, bump - here we go.

Graihagh - Yeah it’s pretty subtle. They’re very close together, aren’t they?

Hugh - Once more - we’ll do it again. You’ll hear bump, bump…

Graihagh - Okay. And that’s because it’s rolling a little bit up the wall, banging the wall, and then bouncing back?

Hugh - When the ball hits the wall, because the ball is rolling for a very, very short time it sticks to the wall, and rolls up the wall, and then becomes airborne, bounces back and then lands just a short way away from the wall. Now this kind of rolling and spinning stuff isn’t all that important except in the 2010 football World Cup, there was a famous incident in the England/Germany game - Frank Lampard’s disallowed goal. And I can hear lots of people listening to this show jumping out of their seats in indignation that the goal was not awarded.

Graihagh - What happened then? I have to admit I don’t watch football, it’s not my deal.

Hugh - Well the ball came in towards the goal, it hit the crossbar and then it went down onto the grass, across the goal line, but then it bounced back up again, hit the crossbar again and came out. Because the ball came out of it’s own accord the goal was not allowed but it was the spinning of the ball that caused the ball to hit the ground and come back out again. So understanding how things spin and what happens about spinning things turned out to be pretty important in that game of football.

Graihagh - In your scientific opinion, should it have been allowed?

Hugh - Well yes, it should have been allowed, I guess I would like to think that referees in football should know all about conservation of angular momentum and the laws of physics, and would have been able to make that deduction for themselves on the field of play.

Graihagh - Other than football though, where are you studying this and using this spinning science?

Hugh - Well, I think once you get outside of the Earth and you go into space. If you think of the Philae Lander that landed on the comet last year and the New Horizon spacecraft that went out to Pluto. If you try and think about how they turn themselves around so that the legs of the spacecraft are pointing in the right direction to land, or that the camera is pointing in the right direction, or the antenna is pointing in the right direction, and it’s all about understanding the angular motion of spacecraft. If you ever watched these movies like The Martian or Interstellar and you can see what goes wrong when spacecraft are spinning out of control. And if you think of a balloon, you blow it up and then you let go of it, it randomly flies around the room, well that’s because it’s spinning out of control. So it’s really important to get control of spin and understand spin in space.


47:18 - Eleven Pipers Piping...

Alan Calverd explains the physics of the wind section of an orchestra...

Eleven Pipers Piping...
Alan Calverd, Physicist

According to the song, by the twelfth day of Christmas, 11 pipers were piping and 12 drummers were drumming. Alan Calverd explains to Chris Smith the physics of the wind section of an orchestra...

Alan - You have to start off by making what’s called a ‘buzz.’ Basically you blow a raspberry in a funnel.

Chris - Go on!

Alan - Pthhhhhhhhh or Pfffffff depending on which level of brass instrument you’re playing. And then that contains a whole lot of tones and you select the resonant length of tubing by pressing the valves up and down.

Chris - Why do the valves actually change the notes though? Why should the length of the tube affect what comes out?

Alan - What you’re trying to do is produce a standing wave within the tube. Now the end of the tube being open means that there’s got to be an antinode at the bell and there’s going to be a node where your lips are because the air’s not moving at that point.

Chris - What’s an antinode?

Alan - Antinode is where the air is moving at it’s most rapid and the node is where the air is not moving. Essentially, if you imagine the tube is stretched out you have something like about 15 feet of tubing, you can draw lots of sine waves within that 15 feet.

Chris - Wiggly waves along it?

Alan - Wiggly waves along it. And provided they all start at zero and end at maximum, then you can have waves of various different frequencies all fit in the tube.

Chris - Would it have to be all curled up like the tuba is or could you get the same tune out of a long straight piece of pipe - it’s just that we coil it up for convenience because it would be hard to move otherwise?

Alan - It’s very difficult to march with a 15 foot drainpipe. Also, it upsets the other guys in the orchestra.

Chris - Fair enough. Why are these instruments made of brass - is there a reason why they go for brass or could you make it out of anything?

Alan - In principle you could. You can play a hosepipe if you’ve got a decent mouthpiece.

Chris - I’ve seen people do that with a funnel on the end. And by swinging the hosepipe almost like you were going to do a lasso, you get a range of different sounds out. Very interesting.

Alan - Yes, that’s quite interesting. You get quite a harsh tone out of a hosepipe - very similar to a trombone because it’s the same diameter all the way down.

Chris - What are you saying about trombonists. They won’t be very happy to hear that.

Alan - Trombonists are always happy because they always get to play the loud bits.

Chris - Fair enough!

Alan - It’s because the trombone is, essentially, the same diameter all the way down the tube. That means you can get a whole lot of harmonics and overtones and you get this good rasping sound if you really blow it hard.

Chris - But the reason for brass?

Alan - The reason for brass is it’s an easy material to work; it’s ductile, it’s malleable so you can beat the shape of the bell that you want and you can draw tubes of any size and length. You can solder it quite easily, it doesn't corrode, and most important of all from my point of view is it’s a biocide. There’s so much copper in brass that bugs don’t grow on it.

Chris - And that’s quite important because you don’t want to catch tuberculosis do you?

Alan - Urghhhhh.

Chris - Are you saying then that, actually, this is a useful aspect of the instrument because of the you’re blowing all that moisture and warm air in there and a whole bunch of bugs from your mouth, presumably instruments do end up riddled with bacteria?

Alan - The first thing they tell you when you join a brass band is... never breath in.

Chris - And what about the brass section and other parts of...say woodwind - is it pretty much the same physics or is there a difference there?

Alan - Slightly different physics. The real difference is in the way that the first edge tone is generated. Instead of blowing raspberries, woodwind either use a reed or an edge like a whistle, which is the recorder and the flute have an edge and everything else is a reed. But the question is whether the saxophone is brass or reed?

Chris - What do you think?

Alan - I think it’s interesting, it’s almost entirely in a class by itself because of all the instruments it’s the one that sounds most like the human voice.

Christmas present

51:07 - Merry Christmas 2016!

We round off Christmas 2016 with a final rendition of A Partridge in a Pear Tree...

Merry Christmas 2016!
Alan Calverd, Physics consultant

We round off Christmas 2016 with a final rendition of A Partridge in a Pear Tree... Physicist Alan Calverd provides tuba support!

Chris - Thank you Alan, and as you get your tuba into position I shall say thank you very much to our panel this week Amy Thomas, James Bowers, Hugh Hunt and Eleanor Drinkwater. The producer was Caroline Steel.

Graihagh - Now, we asked you to vote on the best snowflake, and I’m surprised and  pleased to annouce that I am the winner!

Chris: Meanwhile, from us all, have a very Merry Christmas; we’ll see you in 2017! Take it away Alan...!


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