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2:00

though. Do you know what I was really excited

2:02

about when it came to being part of this

2:04

show? Tell me. Oh just the hard science. The

2:06

big shiny science. You know the science that has

2:08

to be bolted together and takes ages to do

2:10

and the numbers are amazing. Oh this science, this

2:12

science took 40

2:15

million light bulbs and 6 million

2:18

like cable ties. You know 67 countries

2:20

are involved in an initiative that will build the

2:22

world's largest meh and then you probably had to

2:25

be put under a lake

2:27

or you know burrowed into a

2:29

mountain. You know that kind of

2:31

stuff like this can only happen

2:34

by simply lifting the entire thing

2:36

into space and the big huge

2:38

hard shiny science. Or this

2:40

week bubbles. Slightly lower tech I would

2:42

say. It is isn't it? Just bubbles.

2:45

Just bubbles. We thought we

2:47

thought of these gently. So this was a question

2:49

that came in from a couple of best mates

2:51

who were chatting at the back of the class

2:54

and came up with this case for our investigation.

2:56

Hi I'm

2:58

Sophia. I'm Abby. Well I saw videos

3:00

of people online doing tricks where they

3:02

get people inside a bubble and I

3:04

was thinking about like how big of

3:06

a bubble could you make in theory

3:09

and what would it have to be made out of to

3:11

be able to make a really big bubble. Abby

3:14

and I sit together in most lessons

3:16

and she told me about this idea and I

3:19

was well my family's very into saving the

3:21

planet so I was like what if you

3:23

could get the earth into the bubble and

3:26

therefore create like whether you could use that

3:28

to combat climate change. But how could we

3:30

get it that big without it popping? Okay

3:34

so there is big stuff in here then. How do

3:36

you make the biggest bubble and I mean why not?

3:38

You could make a planet-sized bubble to save us from

3:40

climate change. Why not? Okay I see how this show

3:43

works now. That's a good question. Yeah

3:46

I mean I can see some technical challenges here. Yeah

3:48

okay fine. Are you a fluid mechanics person? Do you

3:50

know what I have a PhD in it? Wow. I'm

3:52

not in bubbles though. In droplets. Oh yeah but surely

3:54

this is a bit like you know you go to

3:57

a doctor and you go yeah but you did you

3:59

did. Dr.

6:00

Awesome. I'm a

6:02

professional bubbleologist. The records

6:04

I hold right now is the tallest free

6:06

floating soap bubble and the

6:09

tallest supported soap bubble. Then another

6:11

one that I did is the

6:13

largest outdoor free floating soap bubble.

6:16

And it was a bit windy that day. And

6:19

the poles that I use were

6:21

fishing poles, but they

6:23

were mega size like 20, 22 feet.

6:27

So I had this huge monster

6:29

lasso rope that I put on

6:32

to dip. And

6:35

for some reason, mother nature and the wind gods

6:37

were in my favor and I

6:39

blew the bubble and I've held that record since

6:41

2015. It was

6:43

calculated by one of the directors here

6:46

from NASA Glenn Space Center, that's stationed

6:48

here in Cleveland, Ohio. And

6:50

with a blast of wind that I had, that bubble

6:52

ended up being 3,399.7 cubic feet or so. 96.27

6:57

meters. The

6:59

guy actually took a day off from his

7:02

job at NASA Glenn Space Center and came

7:04

down to the field where I was doing

7:06

it at six o'clock in the

7:08

morning to come watch me blow a bubble.

7:13

That's Gary Perlman. Oh,

7:16

as he says himself, they call me Dr. Awesome.

7:18

Then they call you. I think you've very much

7:20

forced the name on people, Dr. Awesome. At least

7:22

we now know if something goes wrong in the

7:24

next NASA space mission. It's because this guy was

7:26

taking a day off measuring bubbles. It was 20

7:28

years ago with NASA that I think we all

7:30

went, Oh, hello. I

7:32

wasn't expecting NASA to here at any stage during

7:34

this endeavor, but yeah, 96.27 meters. Oh,

7:38

it's big. That is big. Do you

7:40

reckon his doctorate in bubbleology is legit?

7:42

I know it's from the, it's from

7:44

the legit university of bubbleology. Bubble

7:47

town. Yeah. Yeah. But he knows who he's talking with,

7:49

as do our guests, I have to say. Do they

7:51

do? These two who really are the real deal, because

7:53

we have got Dr. Helen Chesky, an oceanographer

7:56

and physicist at UCL, who is famous for

7:58

her love of bubbles. And I

8:00

would like to point out that bubble physicist is a

8:02

real job. Bubble physicist, yes. I know it's your scepticism

8:04

here, but this is a real job. I just, how

8:07

about bubbleologist? It's

8:09

a different form of a real job. Our

8:12

other guest is Justin Burton, a physicist at

8:14

Emory University in Atlanta. Justin, you wrote a

8:16

paper that caught her eye. In the Physical

8:19

Review of Fluids, you went with how to

8:21

make a giant bubble. Am I right? Yes,

8:23

that's right. By the way, how did you

8:25

get into this? What drew you to bubbles,

8:27

Justin? Yeah, well, I mean, I've been studying

8:30

drops and bubbles ever since I was a

8:32

PhD student back in the early 2000s in

8:34

California. And

8:36

generally interested in fluid mechanics that involved

8:39

surface tension. I used to study how

8:41

droplets break apart. And then

8:43

I also studied bubbles in the same way and

8:45

earned the nickname Dr. Bubbles. So maybe not Dr.

8:47

Awesome, but Dr. Bubbles. A lot

8:50

of times we've been throwing around in this field. So

8:53

how about that? What's the short end? You

8:55

know, just add a little soap and water together and you

8:57

can make a bubble pretty easily. But it

8:59

turns out to make the kind of bubbles that Gary was talking about,

9:02

you need something special. OK, I'm presuming

9:04

to materials question basically this. You have to

9:06

get away from just a bit of washing

9:08

up liquid and water. That's right. That's right.

9:11

For the work we published, we tested a

9:13

few different recipes and kind of teased apart

9:15

all the basic ingredients for making the world's

9:17

biggest bubble. So what's the secret? At a

9:19

basic level, what's actually happening there? Well, for

9:21

any bubble to last a reasonable amount of

9:23

time, you need something called a

9:25

surfactant molecule. In the case of a soap bubble,

9:27

we add it to there. These are molecules where

9:30

one side likes to be in the air and

9:32

then one side likes to be in the water

9:34

and they really stabilize this thin liquid film and

9:36

make it last for a really

9:38

long time. So that's the basic ingredients. But then

9:41

the real secret is this stuff called guar gum,

9:44

which is a seed that's grown

9:46

in India. But you can then grind

9:48

it up and make a powder out of it and soak it

9:50

in water. The polysaccharides

9:52

form these long chain polymers after you

9:55

soak them in water for a bit.

9:58

And you don't need much. You just need a spoonful. a

10:00

couple of grams per liter and you'll

10:03

turn your soap bubble mix into

10:05

this kind of soupy stretchy liquid

10:08

that when you try to pull a soap

10:10

film it is able to stretch

10:15

ridiculously fast without breaking that's really the secret.

10:17

Does the gloopy stuff, the long polymers, are

10:19

they helping the water to make a bubble

10:21

or is the water helping them to make

10:24

a bubble? Whose surface tension is? Is it

10:26

a combination of the two? Where the polymers

10:28

come in, I think of them as like

10:30

chains with hooks on them or like Christmas

10:32

lights or something, you know, you try to

10:35

pull them apart really quickly and they start

10:37

to stretch out and they resist that stretching

10:39

and they can also entangle with each other

10:41

and then they create this kind

10:43

of entangled network of molecules that

10:46

help keep this liquid film stable

10:48

and resist, you can even like

10:50

poke your finger through it and

10:52

not break the soap bubble. It's

10:54

really amazing how much stability these

10:56

things give it. How big

10:58

are we talking? How big can your bubbles get with this recipe?

11:01

I would say the biggest one we've ever made we could

11:03

put, you know, we put

11:05

my son and a dog inside of a bubble

11:07

that we made in front of my house. How

11:09

are they getting on? Are they okay? Yeah, it

11:11

took a while. We had to call the fire

11:13

department to get them out. The bubble was so

11:16

resistant to breaking. By the way, just for

11:18

context, so your biggest bubble fits a

11:20

boy and a dog inside it. Dr.

11:23

Autumn's, just to picture

11:25

it, roughly the size of a double deck of bus. So

11:27

we have actually had mixed up

11:30

some of Justin's recipe

11:33

of bubble juice. Okay, can we

11:35

stop calling it that? Just

11:39

mixture is the word. Just mixture, bubble

11:41

mixture. It's in the script,

11:43

I'm reading it. That's the end of it. And

11:46

are we going to have a go? Why not? Do we have

11:48

a small child and a dog? No, unfortunately. No

11:50

double deck of buses. That's the eunice by which

11:52

we're measuring this, is a small child and a

11:54

dog. But yes. So this

11:56

is recipe. This is according to Justin's

11:59

research. This is guan. gum dissolved in

12:01

rubbing alcohol, a bit of baking soda,

12:04

and you know just a little bit of washing up

12:06

liquid in there for good measure and water. And water

12:08

of course, water being the most important. So I have

12:10

to point out that I'm looking through the window at

12:13

the face of the radio engineer to see what he's

12:15

gonna do when these bubbles drift across the studio, the

12:18

expensive electronics. That

12:20

is a small wand. It's a

12:22

tiny wand. Do you know what, that is a good

12:24

bubble though. Yeah. Yeah, they're very colourful. I

12:27

would say it is a quarter of the size of

12:29

your head. Yeah, no, no, no, I wasn't going for

12:31

size. It's a small wand. It still hasn't popped. It

12:33

hasn't popped. It still hasn't popped. Which

12:36

is just a measure of how the water is

12:38

being held inside. So it's not draining very quickly.

12:40

Those are the two things that stop it if

12:42

the water evaporates or if it just drains down

12:44

to the bottom. So bubbles like this tend to

12:46

pop at the top because it

12:48

drains away and then the two sides pop

12:51

at the top. Unfortunately because this is radio you

12:53

couldn't see how perfectly on cue that bubble pops.

12:55

It popped just as you said. It was amazing.

12:57

Let me ask you some questions about the physics

12:59

of this then Helen. While Dara plays with his

13:01

bubbles on the back. You

13:03

know you were making fun before but you're looking

13:05

like a happy small child now making bubbles. It's

13:08

a great fun thing. We can

13:10

pretend like tell me about the

13:12

science. I'm just gonna be sitting here doing

13:14

this. Just playing with bubbles. Yeah, that's

13:17

literally what I'm doing. Go on. Alright,

13:19

surface tension is the secret here. Yes. Why

13:21

is it only on the surface? Well

13:24

the thing about a bubble is it's a pocket

13:26

of gas enclosed in a liquid. So

13:28

you need a gas and a liquid but

13:31

if you just have those two things they're

13:33

not very good. The reason is that the

13:35

surface tension of water, this tendency to be

13:37

elastic is so powerful that it will pull

13:39

itself inwards really quickly and basically pop anything.

13:41

So you need to stop the surface

13:43

doing that. So that's why you need

13:45

these surfactant molecules that will sit at

13:47

the surface and stop it trying

13:50

to move so violently basically. And then the polymers,

13:52

you know, they make it more viscous. They make

13:54

it harder for it to drain. He's still playing

13:56

with his bubbles. through

24:00

the gas and if you put a spoon on top of water it

24:02

would just fall through the water but if you mix the

24:04

liquid and the gas together in the right form you do

24:06

have something which will take the weight of a spoon and

24:09

so bubbles do form these very lightweight structures

24:11

even and foam like that is very useful

24:13

in all sorts of places so that's the

24:15

serious idea. A very very small amount of

24:17

material and presumably something that you could undo

24:19

quite quickly if you decided that actually you

24:21

were deflecting light in a wrong direction. With

24:24

a big pin. With a big pin. Yeah

24:27

no now we're gonna fly a pin to the

24:29

Lagrange point now we gotta be the second robot.

24:31

If I could call up NASA and get them to

24:33

help but unfortunately they're too busy measuring double decker

24:35

bath size bubbles on Earth. I just feel there's

24:38

a lot of unforeseen consequences that we

24:40

haven't thought through here and then we

24:42

have a second round of fundraising for

24:44

Earth's Savior 2 which is just

24:46

a pin that we fly up and the

24:48

pin pops all the bubbles yeah but

24:51

yeah but still look I like it I like

24:53

it as a I'd imagine the closest we're going

24:55

to get to can we because

24:57

we're not going to be able to

24:59

build one single giant bubble over. No

25:01

that's absurd. Yes that's absolutely ridiculous. Yeah

25:03

but lots of bubbles are

25:05

you know way off into space could be the thing.

25:08

You look at you you're old. I've come

25:10

around to it actually because I expected more I

25:12

expected being with you guys on this but actually

25:14

you've now you're like oh no that's actually probably

25:18

yeah that could probably work so yeah let's

25:20

go for it. Okay enough of space for

25:22

that being and science fiction coming

25:24

down to Earth though for a moment Helen you research

25:26

bubbles in the ocean which is a

25:28

different kind of bubble and it's interesting that

25:30

these bubbles already have a massive and kind

25:33

of underappreciated impact on our climate. They

25:35

do yeah so underwater bubbles they're the really

25:37

fun bubbles because they do all kinds of

25:39

interesting like they they they're a lot more

25:41

dynamic basically and so it is

25:43

the case that you know the ocean is massive

25:45

and the atmosphere is massive and the layer between

25:48

them the ocean surface that's where you get breaking

25:50

waves breaking waves make bubbles and bubbles are like

25:52

little packets of the atmosphere pushed down into the

25:54

ocean so they actually help the ocean breathe in

25:57

so if you get a really big storm at sea which is the kind of

25:59

thing I like. study, you know, you're out on

26:01

a big ship and there's these enormous waves around you,

26:04

big breaking waves, you can see the

26:06

bubble plumes underwater and what you can

26:08

also see is that all of that

26:10

is pushing gas underwater, extra gas, and

26:12

the two gases that matter are carbon

26:14

dioxide and oxygen that get moved, that

26:16

the bubbles speed up the transfer of

26:18

those gases into the ocean. Now it

26:20

depends where on the planet you are,

26:22

so near the equator the ocean tends

26:24

to be breathing out carbon dioxide and

26:27

then the North Atlantic for example it tends to

26:29

be breathing in. But are those

26:31

bubbles not constantly trying to rise upwards through

26:33

the water? Yeah but even so, I mean

26:35

they're still underwater for long enough to push

26:37

that gas into the water and you can

26:39

see this right, so just over Christmas I

26:41

was out in the Labrador Sea in the

26:43

north, sort of northwest corner of the North

26:45

Atlantic, big stormy seas and I had oxygen

26:48

sensors that were just half

26:51

a metre and less than half a metre

26:53

above, below the surface right, so right up

26:55

at the top and every time you get

26:57

a breaking wave you get a stonking great

26:59

big spike in oxygen because those bubbles are

27:01

pushing oxygen into the ocean and if that

27:03

water then moves downwards then you're moving that

27:06

gas deeper into the ocean and the only

27:08

way, all those weird deep ocean creatures with

27:10

kind of like you know lights, little fishing

27:13

rods with lights on coming out their heads,

27:15

they breathe oxygen and the place that oxygen

27:17

comes from is the surface and

27:20

it turns out that the way oxygen goes down it

27:22

seems to happen during the very stormy periods and

27:24

it seems that bubbles are making a difference. Is

27:26

that part of the reason why the oceans are

27:28

carbon sink? I mean because there's carbon dioxide in

27:30

those bubbles too right? Yes, you know the ocean

27:32

has taken up around 30% of the carbon

27:36

dioxide that we've put into the atmosphere, the

27:38

extra, and the question is will it

27:40

continue to do that and that's why

27:42

studying the bubbles is important. It's quite interesting then that

27:45

all of this fancy pants sci-fi turns out, turns

27:47

out bubbles are already helping with climate change. That's

27:49

certainly why I'm taking away from it so it

27:51

remains then to thank both of our guests Justin

27:54

Bessin and Helen Chesky, thank you very much for

27:56

joining us. So

28:00

my friend, how's that bubble trauma? If I'd known

28:02

all this at the start of lockdown, I could

28:04

have made the... It would be the best bubble

28:07

lesson ever. You'd barely have had time to blow

28:09

any bubbles. Yeah, I've been there going, oh, time's

28:11

up. They're going, no, no, Father, please. Which is

28:13

the way they address me. Father, please, tell me

28:15

more about the bubbles. Well, then, in terms of

28:17

our questioners, then, we've got the answer for you

28:20

there. Yeah, Abby wanted to know how you make

28:22

it. Gwar gum, G-U-A-R gum, or

28:24

any gloopy thing added to the soap. It

28:26

will work. And if you want to save

28:28

the planet from climate change by using bubbles

28:31

in space, you can. Just not in the

28:33

way you were thinking at all. Not one

28:35

big one, but loads

28:37

of little ones. Yeah, and also, maybe

28:39

don't do that for fear of unintended

28:42

consequences. Who knows, people of Brazil are

28:44

taught to wait. Subscribe

28:54

to Curious Cases on BBC Sounds, and make

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sure you've got push notifications turned on, and

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we'll let you know as soon as new

29:00

episodes are available. The

29:26

whole world was convinced that he

29:28

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