OK So I think we can get started.

So I'm aware of AMANDA Yes I'm a physics
professor here George attack and

there it's a real pleasure to welcome you
all to the squishy physics out of it.

So let me start first of all by
thinking some of the people and

the sponsors that allow us to have this
event so I'm very thankful to the school

of physics here attack and in particular
to his chair professor of public.

Nothing of these would happen without
the help of a doctor or a great call and

without the help of Miss Alice or
Marine So they're very instrumental

in everything that goes on in relation
with this question of physics activities.

I'm also thankful to a large number of.

Institutions right there in City of
materials right has been a very kind

sponsor We're also thankful for the center
of Oregon for running for counties and

electronics and the A.B.B.
And then also we the you are and

Americans Test Kitchen rice or chaps
are going to be doing the demonstrations

are coming from American Test Kitchen
highroad ice cream joined.

Of in the later part of the building up
of the event on there when I have some

tasting of the end in the atrium and

then I'm also thankful to the judge
at the College of Sciences.

So last but not least I really found ways
to port of the firm and Science Center.

Robbie and Tony maiden right they have
been a partner in this wish of his

activity since the very first time which
was already five years ago OK What we do

with them in particular it's a squishy
physics photography contest that saying

that middle and high school students even
elementary students are the consummate

so I'm going to first of all announce
the winners of the contest right so so

the winners this year
are right third place

face call them hot showers
are ideal straining the for.

Since the second position goes to infusion

by her eye where you can see the ice
cream and all these mixing of callers

writing to we solved in a new way
Frank's right new colors right and

then here is a winner of
the number one rose by Kate.

And illustrates how the ice cream
can be sorted like right and

we retain a shape right so
it's a feature of a Springs but

then of the same time if you wait
long enough we did it flows right and

that's a feature of the math here you
have my water right there are liquid so

it's accept a fine sounding like
a legal leg so let's congratulate

them.

OK and then let me introduce
the event that you're here for so

that squishy physics Saturday and the
theme today is going to be ice cream and

I emphasize that he's number five
right which is already getting

significant right and
this is because of your presence so

I'm very thankful to all of you for
being here.

The speakers I saw our speakers today we
have the privilege of having We thought.

Two collaborators of American Test Kitchen
right executive task.

And executive editor of the run and
then from Penn State University

it's a pleasure to welcome
Professor John Karr plant.

OK So the plan is very simple and so

basically hopefully we'll learn something
about ice cream What is ice cream

what is the solid way can you eat it
I mean why they see taste nice and

what about that actually will take some
questions at the very end of the event

OK so if there are questions in the way
please hold them we'll take an R.V.

end OK and obviously even after that
there will be plenty of time for

you to come down here interactive
agree more with the speakers

right with you there John Morley or
Dan and then have the very end.

In the atrium as you leave the high road
asking provided to be off ice cream for

you to leave with a real taste of
the thief that squishy physics at

all and
with the said that sappy is welcome down

multi-engine.

Thank you those are great that's
a great introduction we don't

have a good accent the other two folks up
here today have really good accents so

you have to excuse us so
mine are from America's Test Kitchen and

we want to talk a little bit of you
know what America's Test Kitchen is.

Wow that's nice I was not always going
to know what it is I was like it's not

we're based in Boston I
was like it's national So

I was I felt pretty good that people
would know I was proven wrong but

anyway we're going to show a quick little
video this is a kind of a brand video we

put together is a look inside
the Test Kitchen and so we're a facility

in Brookline Massachusetts which
is right outside of Boston and

we've got a twenty five hundred square
foot Test Kitchen about fifty Tesco and

there's a little peek inside
just to give you an overview.

Twenty refrigerators thirty
five grooms thirty six of them

sixty four burners four thousand
five hundred sixty four cookbooks

this is not an ordinary kitchen and
these are not ordinary chefs.

In a world where the recipes
are everywhere one very special kitchen

is making the only ones you'll ever need.

Every day over fifty test
cooks come to work that's

our test cooks are also scientists.

Historians.

Detectives.

And artists.

And our mission is excellence.

Welcome to America's Test Kitchen.

We developed the absolute best recipes for
all your favorite foods using a one of

a kind process we've been perfecting for
twenty years.

We do everything here is eighteen.

One Tesco begins by researching
every recipe on record.

We find five versions that
represent the range of approaches.

And we study each variable the result
a starting point for our recipe.

Then we claim we test we taste and

we taste and we taste.

And America's Test Kitchen we
make our recipes forty fifty

sixty times until we get it right.

We only kitchen that develops
recipes like this and

that's why all recipes are the only
ones you'll ever need.

Our devotion to the home cook doesn't stop
with recipes from which equipment to use

to which products to buy we rigorously
test everything in the consumer cooking so

you don't have to pilot out of.

Slightly maniacal completely
unbiased undeniable accurate.

In our quest for

perfection harness the science to
unlock the secrets to give us ago.

Because cooking is chemistry.

We are curious we are perfectionists
we are devoted we are family

we are one kitchen undersides we are
America's Test Kitchen and we love what we

do.

With the.

Thirty if you watch the show you
you know at the end there that's

Lisa McManus she's the kind
of gadget guru and we put.

Through you know in pretty rigorous
testing to figure out if they're good

enough for you guys to buy a home and she
really really is that crazy she doesn't

do it like by herself out there alone but
we really do when we test skillets the we

really beat them up so we always love
the All Clad twelve inch skillet and

what's great about it so we do that we
heat it up on the stove get really really

hot and then drop it in ice
water to see what happens when

you get home put on a cold water you know
to see what heat shock happens with it and

then drop it off of high heights
mass things so here's a fun job.

Yes So this is a little bit of where
we come from in America's Test Kitchen

where we publish a bunch of magazines and
a line of books and

we have a television show which is where I
think most people know us from on P.B.S.

But what Dan and I are here to talk
about is actually what we're doing

that's a little bit new at
America's Test Kitchen go to the next.

And it's called Cook science and this is a
new brand that we're launching this summer

in July of this year and it's going to be
all digital and it's going to be all three

so that is something very new for
our company on Cook Science dot com And

what we're going to be doing is leaving
the Test Kitchen which is somewhat

unheard of for America's Test Kitchen
that's far and going out and finding

stories about the things in science
in food that we don't know about and

we want to answer questions about
the first thing was ice cream so

we're launching in July and Dan and
I went to this really fantastic conference

called the Penn State a scream short
course which is why we're here to talk

about ice cream which is why we're here
with John Copeland who we met there so

we're going to go through a little bit
of what we learned at this conference so

if you think about this is like ice cream
one to one we went to college it was.

It was eight days long it's ten
hours of class a day all focused

on ice cream there's labs there's
an exam at the end when I was work every

may look at our boss requested
to see your scores on it.

There's hope every night
it's pretty intense and

you can actually get three credits.

College credit if you take it and
but it's so

awesome we met really interesting people
so this is some of the labs that we're in

here we're talking about the difference
between still frozen and

churned frozen popsicles difference in
textures so what's amazing is you have

these absolutely brilliant professors
ph these experts in their field and

they have the hats on in the rubber gloves
and they're holding up popsicles like it's

it's like the most approachable food
everyone just like get love popsicles and

they study it so deeply and so we're going
to give a little hints of that today as we

go through the end what we really learned
here at this course was the foundations

of ice cream science which you know
we worked in America says kitchen for

many years we've developed recipes for
ice cream we know what ice cream is and

how it works but we learned so many things
that we had no idea about in this course

about the prophecies of freezing about the
ingredients that go into industrial mass

market Ice Cream about you know how
marginalization in past years each and

all of these things that are so

important in the ice cream that you eat
every single day from the supermarket that

we had no clue about and
this is a course that's been around for

I think one hundred twenty something years
it's very popular in a nice world but

it's very popular and.

A lot of the greats in the ice cream
world have been there like Ben of Ben and

Jerry's.

Yeah all of the things that's the whole
thing ice cream break you know.

There's Molly she's very good smelling
things this is a vanilla lab that we did

which was really fascinating they've done
infusions of vanilla beans from different

parts of the world and it mean it
sounds cool to safety in an Indonesian

they actually are wildly different they're
flavor profiles are really different and

so our job in the lab was to
blend all of these different

than those from around the world and
come up with our ideal version and

then they basically mass produce them and
made ice cream with them did it tasting

panel and they kind of crowned
a winner made the best vanilla and my.

So we did we that's why we have
a slide appears we can brag about

our vanilla blending
skills at the next one.

And we met a lot of amazing people at this
conference we had no idea who was going to

be there when we went into it and it
ended up being the whole gamut there were

no project managers there
were lab runners for

industrial ice cream there
were a ton of entrepreneurs

people who came in with this dream
of starting their own scoop shop and

wanting to know more about the science of
how to actually make that ice cream and

it was really fascinating during
the week that we were there some people

came in with this goal of having
a plan to start their own shop and

some left with that goal in place and
started doing and others realized that it

wasn't going to be happening for them that
it was too much money too much time so

it's really like dreams were made and
broken in this one week at Penn State.

Dramatic was very dramatic.

Going to the next one.

So we're going to do a little demo in
a bit about making ice cream in front of

people which usually you don't you know
do very much but homemade ice cream in

general is a very different product than
the commercial variety so John's going to

get into how it's made on a more
industrial level and then we'll bring it

back here when we talk about homemade
ice cream that the and if you guys have

questions about recipes that you've tried
that haven't worked we can you talk with.

I mean this one is it going to join.

Rattle claws for

John Cooper thank

you thank you Molly thank you yes I teach
at the Ice Cream Shop course which is

the strangest job to do it's a university
whenever you work at the university

everybody does something weird
the people doing some great pottery and

those people doing gender
issues in medieval Spain and

all sorts of bizarre things like
along the way I do ice cream and

then looks at me it's like Well another
thing you doing at university and

I'll try and explain a little
bit now my background is in.

Chemistry and physical chemistry
particularly and I came to Penn State and

I didn't really know what Pennsylvania
was when I when I took the job and

I ended up in this very rural community in
the middle of the state of Pennsylvania

and you started to go around and so work
out what where is this university American

higher education is so different than
European one it's built on just completely

different very egalitarian
very practical ideas and

you find old photos like this of what Penn
State looked like one hundred fifty five

before I joined.

The and it was the famous high school
they had this this was there wasn't

much here they built one building and
they went to class in the morning and

they either had military
training in the afternoon or

they worked on the farm this was
practical agricultural education for

the citizens of the state of Pennsylvania
labor they literally followed the plow.

Asked it develop on the very next building
they built on campus was a creamery

because it's a giant burying state there's
an awful lot of milk gets brought into

this place what are we going to do with
this stuff and you needed to learn to

pasteurize it you need to learn to make
cheese didn't ya get to that stage they

did make ice cream so this is one of the
very very early buildings on campus you

can see the wooden walls outsides of the
photos showing horses and carts pulling up

outs up delivering the milk from the local
farms and the churning away and they're

making ice cream it's very recognizable
ice cream the process they're going

through and this giant mechanically churn
thing is going to be very very similar

to the process that Dan's going to be
using later not exactly the same but going

to work pretty much the same idea again as
practical idea of making something which

is valuable from a product which is very
rich in the state of Pennsylvania the or

more thank you and it goes on so we've
got a nice new Creamery now very high

tech very industrial lots of robots lots
of stainless steel and some ways it's much

more disappointing from a teaching point
of view because you can't see any of

the stuff well run dairy plants shouldn't
smell of anything it should just like look

like gleaming stainless steel everywhere
because it's so sanitary and soaked.

Plain and so fast.

And we still make this stuff and

it's made by employees of the state of
Penn State University and I try and

teach about it and when you start
to teach about it it gets boom

complicated really fast because
the next line please this is an advert.

For put out maybe ten years ago when
they were trying to convince material

scientists and physicists to come and
work for Unilever to make ice cream and

the trouble is with food that
everyone thinks because you can make

it yourself because you can eat it because
it's so familiar I understand this stuff

this is easy this is just ice cream
it's not complicated like plastics or

electronics or the tonic materials
whatever they might be this is just

ice cream is going to be simple and it's
astonishingly complicated the stuff and

I'd like to transfer take you inside
about how complicated this would be so

let's start off by taking a little
slice through the ice cream this is

some work by Doug off of the University of
wealth as a wonderful microscopy just and

he's starting to see what's ice cream
made of and I'd like you to see that

at the small scale and be thinking of
concrete if you took a slice through

a piece of concrete it looks a little
bit like that doesn't it chunks

of stuff embedded in cement all kind of
glued together and look at all the stuff

which is going on within the ice cream
is these bluish pieces they're the ice

crystals typically they're going to be in
the order of a few tens of microns across

way small of the you can see
probably finer than a human hair

you can see a beautifully in
a micro under a microscope but

it's to the naked eye it just looks like
the ice cream you're scooping into your

mouth each time you take a mouthful
of ice cream you're taking millions

of individual ice crystals and just flows
over your tongue and they melts and

you're not even aware of them they're
all there the mole the seed is like gaps

are here they're labeled A In the diagram
is another one down here there's air cells

in there ice cream is very often about
half a tub of ice cream is just add

there's nothing there it's a.

Foam with they've it's been whipped and
frozen at the same time so if you've ever

tried to have an ice cream I am I once had
a some come up to me a moose complaining

that the creamery cheats people because
they're selling ice cream plus air and all

the food industry wants to do is to sell
you air because it's so cheap it would be

like trying to eat an ice cube if it
didn't have the air that you need the you

need some space in there that stops it
freezing your tongue off if you put an ice

cube on to your tongue it's painfully cold
if you put a blob of ice cream onto your

tongue it melts much more pleasantly You
need the air you need to make a lighter

make a foam that's MORRIS Well so
those tiny little flecks on the earth.

It's almost impossible to
see just down to the grain.

Those the crystals of fat ice
cream is about ten percent fat and

that fat is present as tiny
tiny little droplets and

they end up sticking around those
ourselves as well and it's all embedded in

some of the material which is the unfrozen
sugar the other ingredients then.

So this rich microstructure is
completely invisible to you

you don't see this stuff it's as
complicated as there's anything you might

make in some sort of micro fabrication lab
but it's done just in the freezers and

that big churning device my ancestors had.

Going to seasonal.

Well that's good thank you thank you so
this is the American Test Kitchen

ice cream recipe that we're going to try
and with Dan's going to try make today so

he's his pre-made some other stuff so
I took some milk cream sugar and

vanilla not very interesting vanilla so
I won't mention it again.

Now if you drink this stuff
it looks a bit like cream

it's fairly thin there's nothing much to
it this is going to turn into ice cream

in order to do it is going to have
to freeze about half the water and

with about the same volume
of air into this stuff.

This is already complicated what you
need to look at when you look at

its complexity.

Cereals like this is what does
it is it's opaque you can't see

through this stuff one of the big
distinctions in material physics

is does the stuff blend uniformly it's
a molecular level in which case we call

it a solution if I just chosen to make ice
cream from water and sugar the sugar would

have dissolved another and it had a sugar
solution there the fact that this doesn't

dissolve when it's cloudy the same stuff
which isn't dissolving in water and

that's the fact that's present
a little bit of protein as well but

the fantasy is the main thing which
is making sure that the stuff so

pake we would describe it as
scattering the light that's present and

you can see the next one place if you zoom
in on this on the microscope you'd see

the fact present as little blob of
little droplets like that if the ice

crystals we talked about before were about
the red the size of a human hair perhaps

thirty forty microns across these would
be about point five of a micron across

tiny tiny tiny little objects they were.

And it's full of this stuff and it's so
that these droplets of flats are floating

around in sugary water and there's
the droplets of fats which is scattering

the light and
making sure that the stuff so

pay Can you can't see through it even
this is complicated this was the milk

in the cream the Done used to assemble
this was was are already homogenized and

pasteurized pasteurized kills all the
bacteria in it which is a good thing to do

a modernization reduces the fun particle
size it makes the fat droplets smaller and

smaller and smaller so if you took this
is about perhaps ten percent fat so

if you took all the fat cells of
this you'd have a clear solution and

you'd have a little ball of fire Maybe so
but it.

And what's been happened to homogenise it
is we've got to start to break that ball

of fat into smaller and

smaller pieces so we started off with
something maybe a few centimeters across

we break it down into something which
is a few millimeters across the.

Few hundreds of micro meters a few tens of
micro meters a few micro meters four or

five logarithmic steps of size
reduction taking all the fat to

make it a smaller and
smaller pieces when you do that.

You end up with an emulsion which is what
we've got here and that's what we're going

to see in the structure here and
I step through the next one so

if you to Madge and we took all the flats
we had in the starting thing this little

ball I represented before and said I'm
going to take those the little ball and

crunch the particles down into smaller and
smaller sizes and

then have the same volume of fat I did
at the end as I did at the beginning of

that process is not all
the same though I think.

The number of particles gets huge so this
is just talk about going down one ten fold

step in size rather than having hunt to
run them a centimeter size droplets we're

going to get taken down to millimeter size
each the big droplet contained a lots of

fun at the smaller droplets each contain
much less so going to have many many

more of them so you saw the huge number
of droplets I had in my earlier slide

as you start to make this particle size
reduction you end up with billions and

billions of little droplets when you have
a spoonful of ice cream you're drinking

literally billions of droplets and
you don't know about them next one place

the surface area goes up so what I'd like
you to imagine is still imagining my

little bowl of fat if you will
there the what I started with and

just imagine that was an orange and
you can appeal at Orange and

lay the orange peel down and say OK that
was the surface area of the front to begin

with now take every single one of these
billions and billions of tiny droplets and

unpeel Loz carefully in your mind and
late one down of course the tiny droplets

of got much smaller surface area in the
big ones but there's billions of them so

if you took every single one of
the tiny tiny little oranges.

And compared it to the big one
it's a vastly bigger surface area

what's interesting to a material
scientist about this stuff

is the huge surface area you'd like
to think of a liquid you say OK

what's the surface of this liquid and
you'd say OK it's a few square inches

around the top of the bottle that's
the surface of the liquid but

really if you think of all the surfaces in
here there's a few square centimeters of

surface of the top inside those billions
and billions of droplets there's probably

a bigger surface area than the floor of
this room huge huge surface area it looks

simple but it's ridiculously complicated
already and that's can't that and

that's difficult because physics doesn't
like surfaces you see the next one place

this is a surface this little creatures
called a pond skater It's also known as

a Jesus bug in some parts of the world
because it can walk on water they've got.

And see how it's tiny little insect
it's got funny brush like feet and

people are fascinated by the feet of these
creatures they watch them forever it's

really complicated but look at how that
creature is walking on the surface it's

feet on point that doesn't go through the
kind of water hates things they don't get

wet and it walks on them kind of like I've
been one of those kids bouncy castles.

You know it's like a big inflated surface
new so if you're a middle aged man and

you have to go rescue a small child
in there is to walk across it really

carefully trying it not so to fall over
and the surface keeps buckling down and

pushing you back up again while you
kids a bounce in of the walls and

everything else is going on madness that's
what's the surface of the pond feels like

the pond skater the surface is
always going to push it back.

So what's it's really at the pushback is
about is that this surface wants to be as

small as it possibly can this is
a real powerful event nature doesn't

want to have this similar materials
together we don't want to have air.

And water in contact if we possibly can so

when the bug treads on it
the surface stretches down and

it's got bigger it's going to act
as an elastic it's going to try and

push back to push the boat back out
when I walk on the surface of the bouncy

castle I'm being pushed back by the
elasticities of the plus of the plastic

making up the surface that bugs being
pushed back by the elasticities

of the water surface the water surface
doesn't want to get any bigger and

as it stretches as the bug treads
on it it's getting bigger so

there's a resistance to movement about
it that that insects suffering surfaces

are trying to make themselves as small as
they possibly can and you'll notice this

already if you're paying attention when I
showed you the microscope image of the of

the emulsion every single one of
those droplets was perfectly round.

What's special about round things
is that they got the smallest

possible surface area.

For the volume if there
were no square ones or

no parent shaped ones the one though
nothing odd everything was round

surfaces trying to be as small as they
possibly can every droplet you eat in your

ice cream is perfectly
perfectly spherical around.

So the trouble we have is when we make
this emotion is that it wants to try and

get back to making the surface a smallest
possible if you had to you just

made this emulsion what's in lots of tiny
droplets the floating around in water if

they hit one another they're just going
to go bloop emerge to form a larger

droplets just like it if you had to
put a few drops of oil into a pan and

stir them around they're
going to group and

merge to form a larger droplets every time
they do that you're reducing the surface

area Nature wants to make surface areas
as small as it possibly can do so you

can work really hard you can a modernising
milk to make these tiny droplets if you.

Starts to leave it's going to merge in for
bigger ones for

bigger ones for bigger ones and
this venture is going to separate else

it's just like making salad dressing
if you had like got some vinegar and

some oil maybe a little garlic in a bottle
you shake it up you get this nice cloudy

salad dressing you've just made come back
to it a few minutes later the oils just

separated out again they haven't
dissolved you for modernized them but

you didn't make a very stable emulsion
all the oil was able to separate out this

is great this doesn't happen in ice
cream makes the must be another level

of complexity here that stopping this
this this front separating out and

here we get back to another one of the key
ingredients we needed some fat we need

some water we need some protein and
tons and tons of protein in milk and

I see the next one so that's
a computer model it's actually an X.

ray image of a protein.

Called we call it a protein
a globular protein and proteins and

we know what proteins are we what we would
choose protein in our diets we know some

foods are rich in protein we know that
we're made of proteins really but

them the Cal thought to put
inside the milk that Dan Balz and

supermarkets put a certain amount of
protein in there and the cow's plan was

to feed her baby that was the intention of
that protein it's nutritionally useful it

can do a few things to to
help the the the calf grow.

So there's tons and tons of these tiny
tiny little protein molecules and

boy talking about the droplets
they're going to be about.

One micro meter across these protein
molecules are about a thousand

times smaller than that so we started with
ice crystals which are too small to see

the size of a human hair when it's one

two orders of magnitude smaller we've got
the plants now we're going one two three

four orders of magnitude smaller amounts
and now we get the protein molecule.

Tiny tiny little protein
molecules all around the Earth and

these proteins are beautiful it's one
of them most majestic things that

nature gives us is these elegantly
designed proteins it's made

as a chain a sequence of a minor acid
switchers as a synthesised by D.N.A.

and it may be a few hundred or even
a few thousand long as perfect chain and

then within milliseconds of this thing
being generated within the cow's

memory tissue it springs in and
it takes these perfectly organized shape

first time every time proteins
are the machine tools of biology

that designed to bind
just one thing perfectly.

And in order to bind that thing they
need to be exactly the right shape so

you can't just be a big blob or
a chain you have to call up and

form exactly the right shape for
every single one of them

once you've got the perfect shape you're
able to bind the thing is supposed to bind

to do with the book The Purpose
you're supposed to do with.

We want to make ice cream with it so
what we do is we take this we take

the fat we start to homogenize it reduce
the particle size the circle at the side

is supposed to be a fine droplets of
that's that we've made inside our motion.

And.

The protein can of defuses along and
sticks to the surface of this newly

created the mulching droplets and
what it's going to do is it hiding the oil

from the water and the surfaces are always
trying to get smaller oil doesn't like to

be touching water and doesn't like to be
touching water surfaces are trying to get

smaller all they can unless you
can coax them with something.

And if you go into electronics engineering
departments of physics departments they'll

talk about applying surface coatings
to materials this is happening within

a fraction of a second of the of your
emotion being made in the homogenized in

the dairy plants these proteins are only
going to end up sticking on to that surf.

Yes and they protect it so
now the oil sees protein

the water sees protein the oil
doesn't see the water.

You've hidden the surfaces
from one another and

this means that if you get a good.

Ice cream makes it stable this stuff isn't
going to separate out into oil and water

even though there's more surface area than
there is in this room surfaces try and

reduce but the protein which was naturally
present is going to protect them.

OK So we've got some ice cream mix now
we need to turn it into an ice cream so

we're going to start to freeze it so
what we need to do is we're going to about

the same freeze about half the water
incorporate the same amount of air.

How you do this is difficult I'm going
to try and incorporate add into this ice

cream mix.

Was disastrous.

I was able to incorporate that
little bit of headspace I'm so

glad they didn't like go otherwise this
afternoon with this morning they've been

dreadful but you can't see really but
it's also operated out of mediately

just get a bottle of water shake it so
you've incorporated some air but

the air separates out almost immediately
this is going to be terrible ice cream

I can't even incorporate that little
bits of air into my emotions.

What's going wrong is.

Bubbles float so I'd like you to
drift your mind off and imagine

a coal glass of a carbonated beverage
of your choice depending on all sorts

of things a lot you imagine which over
the beverages that you'd like it to be and

I'd like you to imagine a bubble forming
in that cold cold glass detaching from

the side and rising gently to the surface.

That speed of movement is
the critical thing here

I can incorporate air into my emulsion.

Now somewhere in there there's an air
bubble which is starting to float.

If I could make sure that
the rate of floating was slow so

rather than going to the top it goes
lowly slowly slowly slowly slowly.

I'm going to be able to
incorporate air into it.

It's not working for me.

But I need to work out how fast is
this bubble going to start to rise

through my column of liquid and if I can
solve that problem then I might be able to

go some way of understanding why my
ice cream isn't working at the stage.

The way we do that is to imagine the
bubbles imagine one bubble which is going

to release it and see what's going to
happen so you think OK it's going to float

because it's buoyant buoyancy means it's
less dense than the water around it and

it's going to kind of depend on how big
the thing is if a really big bubble would

expect to float faster because it's
got more air in its small bubble and

float more slowly so you think OK it's
buoyant it's as really low density ice

cream mixes quite high density so
it's going to zoom to the surface.

I'd like to imagine it being
a bubble at this point so

I will now represent your bubble and

I've been released I'm going to float
towards that exit sign I have a buoyancy

force acting upon me so I'm starting
to move through the column of liquid.

I'm Excel orating this is what
physics tells us that bodies do

you apply a force to a body and it's
going to accelerate into that force so

I can't I'm not to be able to keep my
breath if I do exaggerate too much from

trying to walk a little bit faster and
accelerating through the room.

I'm feeling the air

blowing on the side of my face more
than feeling on the side of my face.

I'm I'm moving through this viscous ad
which is dragging on me a little bit

if I was the flash and

I was assuming it like light speed across
the room the air would be blasting at me.

And it would be almost be like
a rocket reentering the atlas.

You know we're going to burn up
with that amount of friction.

If we were able to fill this auditorium
with water which apparently would count

it would be much more drag upon me it
would be even harder if we were able to

fill this auditorium with molasses
which we really can't and

then the drag would be just completely
ridiculous I would be struggling to move

even a step I still have my
buoyancy force acting upon me but

I would be concerned about the different
types of drag I experienced and

the drag is all about the viscosity
of the fluid you move through.

If I could make this liquid really thick

perhaps I could add some starch
to it to be disgusting ice cream.

But it would be so thick that the bubbles
just couldn't float Have you seen

those like whipped chocolate
dessert things you can get.

You know what I'm talking about.

The bubbles don't float out of those
because the material is just so

thick this resistance and it was a.

Combination of efforts.

From an English guy
called George Stokes and

a chap called Albert Einstein
is statues right outside here

who worked out the physics of how
this stuff works realize that for

the kind of bubbles he was an ice cream
though I'm sure Albert Einstein Stein

wasn't think about ice cream when he
worked it out was the this viscosity

got really important you need the bubbles
to be small because you've got less pull

lift and you want the liquid
it's moving through to be thick.

And we want to try and
do that without adding nasty gradients to

be ice cream which would otherwise
make it kind of disgusting

ice is going to be terribly
terribly important here.

And I think we've reached the part of
our story where we can no longer not

talk about ice after making ice cream so

I'm going to pass back to Dan who's
going to actually make some and

then I'll try and talk about what
that might mean so we get a titanic.

Set up for us and.

You get a cop too for this.

So John talked a lot of bad
things about this really and.

You can make it sort of it's going
to go to the don my apron for

this so making ice cream in front of
people turns out to be really boring

because it takes like thirty minutes and
and ice cream TURNER So

we're not going to do it that way we're
going to use liquid nitrogen to do it.

So this is a mix that you saw earlier so
it's really simple it's equal parts

milk and cream there's three quarters
of a cup of sugar in there as well and

a little bit of the Nella and
liquid nitrogen is really really cold so

it's it boils at a negative three
hundred twenty degrees Fahrenheit so

it's very very cold.

And it's going to allow us to
do this much more rapidly.

You normally do because you know you guys
can see on the camera they're going to

move this for a second.

Who has liquid nitrogen.

We get we actually have
one in the back burner.

So you can do this or
you can do this recipe that.

Is that in there.

Cool so it's going to pour some into
the smaller doing or make a lot easier for

me and the best thing about
the conversion is how cool it looks.

Good for parties.

And what's crazy is I can just kind
of support this on the table too.

And it runs away you can see that
it's boiling inside this do or.

The reason I can port on the table there
and it doesn't freeze the table solid

because this is really cool if it's
called the leading Frost effect.

There when you have two substances
that are just completely

like really really different temperatures
so if you have a really hot skillet and

put a drop of water on it and then you'll
see it beat up kind of spin across on it

that's all like spit in a frying pan
to tell if it's if it's hot trick and

so what's happening there is right where
the water contacts the hot pan it forms

this vapor layer and
that's actually an insulator so it keeps

keeps the temperature down just enough
of that water droplet can survive for

a while so that's what we're seeing along
the side there also the it's boiling so

it considers the side of this really
really hot in comparison to what it is so

there is a vapor layer of nitrogen
protecting it and then now

the containers cooled down enough that
you're not seeing that happen anymore so

I want to put a little bit more in.

But.

These gloves protect you but

they're very slippery which doesn't
protect all of you go from me dropping.

This on.

The

screen.

All right excellent So John mentioned
a lot of times when he was making fun of

this ice cream base that we're going to
we're going to freeze about half of it and

also put in about fifty percent air so
to do that

we're always going to freeze with our
liquid nitrogen which is very cold.

But if we didn't move it along and kind
of whip it at the same time it wouldn't

get that air in there so we get a very
dense product and this would also sit on

the surface it would kind of freeze just
straight down as opposed to thanks again

so we're going to freeze it at
this moving about medium speed.

And there too right that's going to be
it will put the most complete wrong.

You're.

Going to.

Put it you know put in for the thing

in.

So the trick is to add it not too fast.

But look score it.

So as it starts to get colder
it's going to be more viscous so

the air that we're whipping
into it will be trapped.

It smells

good.

All right now let's pull a little
bit out take a look at it.

I guess we can see it's really for me at
this point start with the cannot see with

that camera there.

So John will talk a little bit more about
this but this isn't freezing in the way

that an ice cream ice cube freezes right
where it's liquid and then it's solid This

happens over a longer period of time and
it goes through different phases.

We also test stuff like mixers we
don't do this test with the kitchen.

I'm sure they would do not
want you to be doing this.

All right so you can kind of start to hear
that a little bit some of the can sort of

on the bottom and

it freezes a little bit too fast there so
going to be some torching.

Warm up the bottom.

Fire and ice all in one.

Yeah that's probably good and
then we'll take another look at it so

this is start to look a little bit more
like like a batter on this right you're

getting more air and
they're a little bit thicker.

I

would.

Startle if you.

Are a little more towards action.

But.

There you

go.

When the.

Really the one of the canisters that
you have a home it's all freezing from

the outside right and you have
the dasher blade that goes along and

cuts all those ice crystals off and
they go into the center

This happens all throughout because
we're mixing that look related.

So it's a lot

faster.

We were very close.

Well that that was
heartening I got I brought.

Some candy so we need to decide I'm going
to ask people to taste as I know you guys

take a vote on what I'm going to
put into it so I brought an end.

And Butter Finger so Eminem's.

Butter Finger by our own.

Atlanta legs Butter Fingers
it's now learn something new.

This is a very technical process and
then the butter finger up like

this.

Really like just one of the bars or
two of those or two in there to the.

To be sure he goes with one of that way.

And this tiny bit

more.

ASTA.

Right get some ice cream here so
I'm probably.

In the six.

Small tasters.

Or you know I feel like we could take
all the small tasters probably when all

the small taste has come down and
you guys can tell us what you think of us.

Thank

you.

It's a really it's a really honest
reactions if you don't like it you can

tell me my feelings will not be hurt.

And you guys had liquid
nitrogen ice cream before now.

So some people actually have
had already that's impressive.

Or well there's Don't is no fruit
in this you know about that.

You know.

It's a good try think about the texture
of the ice cream I'd really expect

this to be really smooth ice cream.

So one of the benefits of using
a connection obviously is very fast fast

freezing gives you really small ice
crystals and as John was mentioning.

We want the ice crystals to be small
enough that we don't really feel them on

our tongue when people say
that an ice cream is too ice.

It's not actually really good
representation of it we actually have more

smaller ice crystals in this we're going
to get some pretty view more smaller

ice crystals in this than in a slower
turned ice cream we're going to have fewer

bigger ice crystals.

I'm not hearing any feedback
what's going on where we think.

It's good good OK good.

Really good OK.

Any other descriptors we think
it's move but it tastes like.

Butter butter fingering.

Now.

This is really good I don't even
like peanuts are this good.

Sauce or if yet so yes this is this is
this is pretty soft at this point we can

put this enough in the freezer and harden
it fully This is probably about fifty

percent frozen at this point which is
when you would normally take it out of

an ice cream maker and then we go into the
hardening phase which is in effect which

is in the freezer where we get probably
another ten percent or so for us at that

point depending on the composition course
so you guys are you guys are fans.

Going to ask your parents for some liquid
nitrogen now good all right great let's

give a hand for these guys thank you.

So much.

And I will pass it back over to

John.

Ha.

We pass it around.

Something you never have to deal with
when you're really University professor

standing up after someone's made liquid
nitrogen ice cream with flames and

butts of thing goes through them and
they come back and

said Now let's talk about thermodynamics.

Which is just awesome.

But.

Let me tell you about so I ask you to
think about something which seems so

simple but is ridiculously complicated and

I'd like you to stop to think
about why he does want to freeze.

When you cool it down enough why do you
get these things called ice cubes so

if we did a.

Chemical analysis of that glass of water
would say there's one type of molecule

there H two O. this doing
ridiculously different things it's

a clear liquid or it's a solid
is different we call them states

of matter present here with the strength
Think about what those states of matter

might means I'm going to take use of
cartoon representation of what the water

molecules might like look like and have
I don't know this the kind of thing you

might do in middle school science you
draw molecules as little balls and

it's stack up and you say this is
what's a crystal looks like this is

my representation of what I see looks like
each of the water molecules a little black

circles is regularly spaced they're
all really close to one another and

they might vibrate backwards and
forwards a little bit but

they're basically going to stay where
they are that's crystalline ice.

And then it got liquid water so
the black balls are still the H two O.

molecules the still pretty close to one
another but they're moving all the time

the bumping into one another that
a fusing around them moving slowly and

the stuff flows this is why what
we mean about liquid being a.

Fluid it's able to move the molecules
can move past one another

just like they count in a solid.

Why can you go from such dramatically
different behavior at this is zero

degrees Celsius apologize I just don't do
far enough to bear with me on this one.

A.

This is the guy that could explain it this
is the greatest American scientist has

ever been this is just will out Gibbs
he was some of them assessed back end

of the nineteenth century and he did his
Ph D. in Germany then he moved to Yale and

it is a pity and Yale you travel
to Germany briefly after that and

he just stayed there his entire career
a very quiet man didn't really like

the limelight you know the world
scientists now are always being pushed for

their big high impact
publications Nature and

Science Some things just I will or Gibbs
published in their local in town matter.

Well science is a magazine all this stuff
and he changed the way we understand

everything and up to then
thermodynamics had been European and

it had been about steam engines
very practical Englishman and

Germans trying to make the best possible
steam engine they were interested in heat

they were interested in work they
were interested in making stuff and

making money then this American came along
and he saw the it dawned on him that

the at the operation of a steam
engine contains everything and

if I can find to if he could find a way
of translating this to the molecules that

make up the universe then all this all
sorts of things become predictable and

one of the questions he sought to
answer is well what's the preferred.

State of a chemical system a chemical
system could be a jar of ice cream mix

it could be an ice cube it could be
whatever you want to talk talk about it is

a kind of fancy way that chemists like
to talk about their world this chemical

system is going to be solid is going
to be liquid is going to be ice cream

is it going to be me and
he thought about this stuff and how big

things work out in the universe is
something we've known really since Newton.

To mean drop here but
he was English to Newton then.

You got his go to starting think about
mechanics so if I had if I could have a.

Pop sir curved surface and
I could put a marble on there you'd know

really comfortably the marbles
going to roll down the hill and

perhaps stop on the chubby part of my hand
down there if if there's a star rotating

around the planets you can predict
exactly by Newtonians light by Newton's

system of equations what's going to happen
if you kick a football Newton will tell

you it's going to fly through the air then
it's going to return to the ground and

that's where it's going to land it works
beautifully we say in terms of these

Newtonian physics that matter
is responding to energy and

in most of those cases it
would be gravitational energy

that is trying to find its optimal
position with chemical systems that.

Important not only gravity but the.

The energetic parts important but there's
also this wonderful idea of randomness

which is totally non-intuitive until
someone gives came along where

you need to get a sense of how organized
the system is so I have an ice crystal

have liquid water this is just a snapshot
be you know those are in the ice

the molecules are staying still in the
water they're diffusing past one another

and moving around from an entropy point
of view which is this disorder thing

gives would say this is much
more disordered than that and

you've got to try and
work out a balance between disorder which

tends to increase in the universe and
energy where systems going to try and

find its energy minimal both of those
things are kind of important and

gives put these together in this is
the only question I've got I promise.

This thing called the Gibbs free
energy which is a combination of and

thought he would should put it
all as it is temperature and

entropy which is this disorder thing and
I try to put a little bit more language in

there you can summarize this
stuff in the next like this.

And in saying you can get away with having
organized structures like the ice crystal

but only at low temperatures
the organized structure is preferred.

If you've got low temperatures if
you raise the temperature up that T.

Times asked him on the previous
slide that gets much much bigger so

the entropy of it becomes the thing which
drives the system chaos winds in the end

and the water's going to be preferred.

So if you could hold ice and water
together there's a going to be a clear

temperature between when it's going to be
solid when it's going to be organized but

it's cold enough to put up with that
stuff or liquid when there's so

much randomness and noise and
chaos coming in from the temperature.

That allows those crystals to melt and
as a zero degrees Celcius is when you

see one or when you see the other one and
you can use it as of the moment so

you know exactly what's going to happen
water is pretty simple once once Gibbs is

earlier had able to explain it to us and
molecular terms but

it was more complicated than that.

Is ice cream doesn't melt like that if I
cause an ice cube and started on the table

it would slow it would drop away to water
it would be either completely solid or

completely liquid was that the two states
it can be but look at these beautiful ice

cream's all these there's this students
a photograph for us you can see

which of those ice creams in
the liquid Rose was scooped first.

You know it's progressed in that direction
as it's melted it's gone from being a firm

solid to being a softer solid to being
almost completely liquid you could see

the same experiment happen in reverse and
Dan's ice cream he poured the liquid in

here there's no ice at all remember when
he first started to sample it a couple

of the words he used to talk about it was
like a batter was a milkshake OK it's

starting to look like ice cream when we
served it some people were complaining

it's still a bit soft and hammer say yeah
we put it in the freezer later the harden

up a little bit it's a progressive change
of texture we're getting an ice cream

that you don't get an ice cube
something's going on here which is just

more complicated than a simple story
I told you with Gibson is free energy

we need to go some way of trying
to explain what's going on there.

If you look at ice cream
under the microscope

you start to get a clue
of what's going on so

here's some work we did in my lab
looking at individual ice crystals

this was a sorbet rather than ice cream
because of their easier to work with and

you can see these these tiny little ice
crystals like pebbles floating around in

a liquid there are individual ice crystals
is not spew or solid it's not pure lick.

It was liquid their hand was solid there
was a blend of two different materials so

there's some water frozen as ice here and

then some unfrozen stuff and
then frozen stuff's going to be sugar.

Some liquid water pump
some flavorings bits of

Butterfinger bar the fats are all
going to be out there and

with these pure crystals of ice
that is suspended in this liquid.

That's what ice cream looks like I can
simplify that and turn it into a graphical

model so I'm going to use each of these
little black objects to represent a single

ice crystal and it might look something
like this it turns out that if the ice

cream was a little bit warmer or
it formulated it with a little bit more

sugar it might look like this
the crystals are smaller.

If you take in this ice cream which might
look at that as the stuff that down made

and put it in the freezer for a little
bit it might look like this the crystals

a bigger now so this is the pretty
much the same number of crystals but

it is getting bigger and smaller and
you can tell how this starts to affect

the texture of the thing I got all
these chunks of materials in here.

If I tried to make that
flow would go back to.

I could imagine stirring that you put
a big spoon in and you could push these

crystals around and they'd float around
like the giant icebergs in Titanic they

bump into one another and it would
be some resistance would be viscous.

But still floorball if I
want it up a little bit or

those just starting to freeze it
are going to few crystals now and

it's going to be much easier to flow
there's much less particles there

that the term would talk about if
you it talking about the reaal A-G.

the science of flow of material like
this is it would say the volume fraction

of the dispersion is changing it's a
dispersion of ice in water and now a good.

Less ice present so it can be much
thinner this is Dan's milkshake if we

go forward to if I finally make
the final product back one place.

Now will the ice crystals actually
bumping into one another the so

big now there impinging on one another
if I tried to make that flow they're all

glued together sticker ice cream scoop
in that try and move it around and

you'd have to really work because there's
ice cream they can't flow past one another

they are pushing into one another so faces
of stick in ice cream spade into an ice

cream try moving backwards and forwards
the whole ice cream blocks going to move

around on the table unless I really given
a arm and work at it it's turned into

a solid it's behaving like a solid but
do remember how much liquid is there

all the white bits on that slide is
still the unfrozen sugar solution

it's to it it's a solid to your eyes you
might say this is hard ice cream but

it's still an awful lot of liquid present
and you could see how something like that

if I could put a a bubble of air in
here the whipping action of that

ice cream mix was sitting here and we went
back to my arguments around Stokes and

Einstein about is that bubble going to
float on out what's going to give you

the most resistance more ice is going to
give you more resistance so ultimately

you only can only really get ice cream air
rated once it's not like partially frozen

you have a little bit of ice present
gives you a little bit of resistance then

the whipping gets much more effective and
you can trap more air bubbles in there and

get the air content all over
on you're really looking for.

It to explain why this is happening.

We need to drag in another piece
of physics and this is going to be

an idea called freezing point depression
and what we're thinking about here

is if you had something to water it
makes it harder to freeze that water

you need to go to a lower temperature
a great story I normally give the.

Talk in January in Pennsylvania and I can
talk about throwing salt in your driveway

and of ones like yep I know it talking
about you know the dry work I'm in Georgia

and I'm in it it's in and in spring.

If you go north it gets really
cold in the winter and this is.

That's what you try to do with
salt in the driveway and.

So what this diagram showing you is the
freezing point of different concentrations

of sugar solution so over on this end
of the graph it's zero percent sugar so

this is just water and his temperature and
we know water freezes at zero degrees

Celsius he put a mark on this line saying
OK that's the freezing point of water if

I'm above that it's a five degrees Celsius
in a refrigerator water's liquid if I

go below it to say minus ten I'm in
a deep freeze water solid I've gone below

the freezing point it solidifies if
you go to higher sugar concentrations

of twenty percent forty percent
sixty percent eighty percent sugar.

Downs ice cream would've been about
here it will have a lower freezing point

the sugar lowers the freezing
point of the solution so how OK So

there's a bit of physics for you how does
it work how is this a useful thing to do

and I'd like to try and imagine making
ice cream and suggest sugar and

water so in a forget about everything else
style with we could it would just be like

getting sugar water pouring it into the
device to bring in some liquid nitrogen

see what's going to happen and we can
start off with a twenty percent solution

of sugar in water so this would be.

Sweeter than color that kind of level.

It's it's about it's a it's a refrigerator
temperatures are going to start to

drop the temperature one clean place so
that the temperature drop

from up here dropped down there just back
and forth a couple times back and forward.

It's not that high drop
the temperature down and

I'm showing this on my
graph that it started hard.

Hey refrigerator temperatures I'm lowering
the temperature down and now my twenty

percent sugar solutions at zero degrees
Celsius what's going to happen.

What what is what's going to look like.

It's liquid nothing's going to happen
it will be a little bit colder

because the freezing point of
this stuff is minus a little bit.

OK let's keep going.

Drop the temperature again and I'm
a little circles down here by thermometer

they spent ages fiddling around in
powerpoint to make those little clicks

work I said my temperature is now
a couple of degrees below I've hit

the freezing point of my twenty
percent sugar solution who.

Let's have some options nothing happens
if freezes solid like an ice cube or

options see.

Who.

Option C..

Yeah I think I was going to happen
it gets down to the temperature and

I can just about begin to freeze Let's
go a fraction of a degree lower just to

convince ourselves it's going to freeze
and let's make one ice crystal this tiny

ice crystal forms the bar at the bottom of
my of my twenty percent sugar solution and

sits there proudly the ice
crystal is pure water bill

frozen water outside the ice crystal
was twenty percent sugar solution

I've taken some of the water
from the sugar solution and

shoved it into my ice crystal
is the sugar solution the same

concentration more concentrated or
less concentrated.

More concentrated I've taken some mortar
still inside my beaker at the same stuff

it's twenty percent sugar but I made
a tiny ice crystal which is pure water.

What's left the unfrozen bits is
a little bit more concentrated

it's got it's it's goes as it's a bit
sweeter it's got a bit more sugar and so

I made the crystal and
now it's more concentrated.

If I want to make the ice crystal grow
a bit more I'm going to make cold

because I'm not trying to freeze
a twenty percent sugar solution now

I'm trying to freeze a twenty one percent
or twenty two percent sugar solution so

let's drop the temperature a little bit
more we make it a little bit colder

my ice crystal gets a bit bigger
How does the sugar solution

it's more concentrated it's even more
concentrated I've got a pure ice crystal

it's a bit bigger sitting in a slightly
more concentrated sugar solution.

And it keeps on going like that I
keep lowering the temperature and

when ice crystal gets bigger

the sugar solution that's left behind gets
more concentrated until I choose to stop

going to happen other click
place drop the temperature more.

I'm now below the freezing point but
what I've actually got in my beaker

is a slightly bigger ice crystal sitting
in a solution which is slightly more

concentrated like again place finally I'm
going to start my experiment at minus

ten which is not a bad temperature for
ice cream leaving the freezer.

And now I've got I'm well below
the freezing point I've got ice present.

Sitting in a very concentrated
sugar solution and

it turns out that the concentration
of the sugar solution

is let's just follow this
line across horizontally.

Is that.

Ice crystal sitting in almost
sixty percent sugar solution.

One of the things we're going to ask you
to do later in this experiment is to eat

some popsicles experiment lecture you
going to ask you to eat some popsicles

when you eat those popsicles bite
down on them and suck like crazy.

What's going to happen.

These suckers sugar out that's right
it's in your tongue is going to turn

blue whatever color it is you know
you get the colors out the sugar and

what's going to be left behind
just ice is going to look white

it's going to look player and
it's going to be.

Everyone hates eating that part because
it's just you're just eating an ice cube.

What we have made is a two phase
material we started off with a sugar

solution there and we started to freeze
it we made our ice bigger and bigger and

bigger the solution more and more
concentrated but I've still got ice and

I've still got a sugar solution it's
easy to demonstrate isn't a popsicle but

the same thing that was
present in Dan's ice cream

the the ice crystals got bigger and bigger
and bigger it gets harder and harder and

harder and it's June to this freezing
point depression effect and next on place

a start of the twenty percent sugar
solution dropped to minus ten and about

half the water in the material freezes
turning it into ice the frozen to the ice

is just pure solid water leaving this
sugar solution really concentrates it you

have a lot of sugar in the unfrozen parts
of ice cream About sixty percent sugar.

You expect that.

OK.

When you teach multiple sections of
a lecture it's actually like this or

you could just start to get an answer.

Yeah so this is what's happened we
started off up here somewhere we've got

the temperature down to minus ten and
I've drawn a horizontal line here and

I'm saying one end of my line
that's that's the sugar solution

at the other end of my line that's the ice
Here's the sugar solution here's the ice

if I was doing a physical chemistry.

Lecture here we've just made
what's called a phase diagram

that freezing point line is a map showing
you what parts you can have one phase

of solution once you cross this phase line

then you get this two phase of material
you've got multiple things going on and

what are you doing when you freeze
ice cream is your is your generating.

The two phase system of partially
frozen and liquid materials.

This man can tell you why.

Freddy had to go to Austria now.

And we live with Boltzmann who
was a genius he was a person

who grappled with this idea of entropy and

champion physical and
physics is hard to see in our world but

is absolutely dominant in the way the
universe operates it's a tendency towards

greater disorder and.

Dias diffuse outwards colors
makes hot things cool down

it's how we understand time
in the universe I think

is largely about how we understand
entropy the universe moves in one way and

this terrifying looking man
worked out what that means.

And he came up with this
idea of a statistical sense

of disorder what do we remain about
about being something disordered

most of time you thinking of
a tidy room or a messy room

ones disordered ones ordered maybe when I
lined up those circles you would think and

I told you one was ordered one was
disordered it sort of made sense well

Boltzmann actually came up with numbers
for us and you can illustrate it's.

A simple thought experiment so what I'd
like you to imagine is a checkerboard or

grid like this and
a whole bunch of colored beads

that we're going to put in we were going
to start to put into spaces here so

you could use them dice and
just of say OK I'm going to

read beat where I'm going to put it
total random chance you've got four

by four one in sixteen chance of going to
anywhere you roles and dice and click.

Again my animations
pretty on points evening.

It ends up in one of the spaces
they could've ended up anywhere

I had sixteen choices now
let's put the next one in.

I have fifteen choices now and
it ends up there.

The next one I have fourteen choice is
completely random and you could and

you could keep on doing this until you've
filled the entire thing that's fine for

nothing.

Until you've used fill the whole board and

you can imagine there
would be a whole mass of.

Different ways you could fill that
checkerboard if I'd given you a little

experiment to do you'd all come up
with ones which were different because

many many different combinations you could
put those sixteen species under sixteen

squares they would just look different
you wouldn't see the different.

The chances of the next one place.

And the next one.

Chance of getting this next one.

That's ridiculously unlikely.

If it's a child of the chance of
generating that structure by chance and

you can work it out if your sisters
disagree mind it's not that hard in

terms of mathematics the chance
of getting that is tiny so

maybe if we'd all done the little
experiments and the next lecture hall and

the next lecture hall maybe by chance
one person would have got that.

One Boltzmann said is the way the universe
progresses is towards the more

random more like a police
state if I looked at a whole

mass of these things if I saw this I.

Know someone's cheated if I'd saw seen any
of the previous ones all these different

combinations I wouldn't say that I would
be surprised if any two were the same but

they would all be not in this state.

And that's what Baltimore is all about he
was saying the thing we're most likely to

see is the most probable thing this is
improbable unless a human being went in

there and intervened and cheated
the chances of using it by random is so

tiny it's.

It's not going to happen it's
the same sort of thing if you

if you start rolling dice you roll or so.

X. and you think OK got a six year old
five six years in a row you know that ISIS

fixed you can't predict what the sequence
is going to be it could be anything but

the chances of getting something regular
whole row of six as a whole row of ones

these separated like this is
statistically unlikely and

what we're going to tend to see is the
universe moving towards greater entropy

more disorder impulse means language.

So what we're seeing here
this separated state.

Is that was very very unlikely.

You can see the same thing in next
like place in this diagram in this

lovely photograph here where you
can see the dye is diffusing out.

Here you know if that you went back to
that photograph a few minutes later

a few hours later the diaries would be
more mixed they wouldn't recoil backwards

was so programmed into us this idea
that the universe flows in one direction

it's really hard to explain unless you get
into Boltzmann world which only happened

at the start of the twentieth century this
isn't old old physics at all the idea that

the more random distribution is
going to spread out like that and

the colors are going to blend in not
going to see them recoil you never see

if you had to have a warm object it
never spontaneously heats up if you have

hot water and cold water they never
separate out all the gas in this room

statistically could just choose to leave
randomly it never does it's tendency

towards randomness it's if you think more
about it it's a very bleak philosophy

the Boltzmann was able to expose but
it's powerful and this driving force

a work away from Order towards randomness
provides the next part of the puzzle

we can explain why we get this phase
separation Here's what we talked about

with gives a number we're talking
about you can have organized things

if you're cold enough this
is why water goes solid.

When we talked about making ice cream
though we talked about phase diagrams and

concentrating things and that was
more common more complicated we kept

talking about the sugar solution getting
more and more concentrated Well look what

we're doing we're knowing
Ludwig Boltzmann we're working against

we're generating order
in the world I've got.

An even mixture of sugar molecules
in water here by the time I've

gone over here I always sugar molecules
are up here they're in the unfrozen Here's

my water molecules pure all
pure water is down here

I've brought the sugar molecules together
them they're closer to separated

out than evenly mix them they were before
I think someone's been cheating here I

think someone's been separating out
the red beads from the blue beads.

And that cheating is us
putting work into the system

lowering the temperature more and more by
lowering the temperature we're able to

fight against the high entropy
disordered state of mixture and

achieve this more ordered separated
state we're working against

entropy to do this and because with
the progressive concentration thing

we continue to concentrate it then we have
to continue to work along those lines and

that's what gives us this this broad
freezing point depression and.

It also opens of all sorts of things
because when you're talking about entropy

and should be isn't about chemistry it
doesn't really matter what the sugar is as

long as it dissolves you could anything
should work and as food scientists we have

lots of types of sugars at our disposal
that you probably don't in your kitchen

but we found out that different types of
sugar behave differently and it turns

out that it's not a chemical property for
those forces glucose was a sucrose versus

concert solids What matters is
just how big those molecules are.

Because we want to know even to get the
same effect if you have the same number of

molecules that's going to be the next
line please here's what I mean so

we're going to make up a ice cream
mix with ten percent sugar so

you had like a three quarter cup of sugar
so we could decide to reformulate is

ice cream going to put three quarters of
a cup of sugar but with three quarters of

a cup of sugar could be sucrose which is
what you picked or it could be photos or

it could be glucose or millions on I've
got a big chemistry lab I've got tons

of these things they can pick from they
can pick any sugar you want to to.

If the sugar molecules can be small
molecules medium molecules or

big molecules they can be small medium or
big and

I'm going to add the same mass
of them to each of my blends.

If they're small.

The three cups and three quarters of a cup
of of the molecules I'm going to have

a ton of molecules.

If they're big.

I'm going to have relatively
few molecules going in and

putting the same mass in the same
three quarters of a cup of sugar but

because it's either three quarters of a
cup of very small things or three quarters

of cup of very very big things that you'll
know members of things are going to

going to differ dramatically so
my small molecules are going to add more

of them and it's the number that matters
so if you are the next from small for

those medium sucrose huge concert solids

out of the same amount I'm going to get
a bigger freezing point depression effect

here and yes softer ice cream with this
one because I can really lower my freezing

points the number of molecules that count
are the same amount of the sucrose.

It works not it doesn't give you as
much for example depression in fact and

concepts knowledge is lousy It doesn't
give me this freezing point depression

effect it's not the mass that's putting in
it's the number of molecules that matter

in the next one.

And this opens up another option.

Here's my freezing point lines this is
what Listen the sucrose is pretty much

the way they gave us beautiful ice cream
I could formulate with fructose and

glucose and it would give me softer ice
cream if I formulated concert so much it

would give me harder ice cream you never
formulate with ethanol if you want it so

I got it going to be there on my now
because I knew you were going to do this

lie so I actually formulated a recipe.

That it's just with ethanol.

But I'm going to go sit down over there no
no you can't sit down I need a couple of

big tasters for this one.

When John did this at ice cream course I
said I bet it makes some sense that you

would want to use ethanol but
what if you cut out all the sugar so

that you only use that at all so.

Right right here in
the in the tan shirt and

a couple back there you know when she is
going down I only have forced good so

otherwise I have more people so so what's
what's in this recipe so this is it this

is a similar recipe to the other one so
it's equal parts milk and cream.

This one I left out the vanilla You
know as a pinch of salt for flavor and

then there's some vodka.

Here you go you guys are going to have to
share the spoon but I assume that's OK.

You need bigger suppose I'll just wait and
see what I see what you think so

I'm going to take in the center might
be a little colder still there.

You can taste the bug.

So this is missing out it's a little
bit softer than it should be.

So when you made this.

It was three quarters of
a cup of sugar how much.

Went into that into that So this comes out
to about six and a half percent alcohol by

volume so this is like a slightly
strong beer OK so if you would when

you tipping vodka that would that be like
a cup of three quarter of a cup of vodka.

You know it's nothing like that it's
much smaller I think this is about

roughly two shots of vodka or two shots of
vodka and that makes sense because you see

what he was doing he's taken all the sugar
else and we don't worry about proteins or

any other facet of the way that they don't
depress freezing point is that to bake.

There's no sugar in there so
if you haven't had the vodka it would have

frozen like an ice cube would have been
totally solid and really unpleasant but

you had advanced care.

And not part of the not very much of it's
because you can see the molecule is so

small that if you added three
quarters of a cup of it it's a HUGE

amounts you get this massive freezing
point depression effect you wouldn't be

able to make enough ice so the it end
up with a couple of ice crystals and

it would look like nothing but adding just
much less vodka into its you could dance

similar sorts of texture and
it's good it's not very good but.

Creamy it looks like it's creamy and
smooth it looks like ice cream yeah.

In looks alone.

I could have a whole going to spend
the afternoon with your I think it was.

You know it's.

The owner's

good.

Yeah.

I.

Get that.

Six and a half percent.

Yet you could not bring much of it to
get there fight because it's really cool

Thank you Don That's response.

OK So what is going to tell us about how
you can make ice cream with vodka and

you use artificial flavors to get Roman
raisin ice cream but you can sew them.

Thank you.

One last story to talk to you about ice I
am a member who was talking about how this

to freezes and we have this ice
crystal getting bigger and bigger and

bigger it should be obvious at this point
that it doesn't do that I don't have

one giant ice cube in my ice cream
I have tons and tons of tiny little

crystals in the individual crystals
something else is happening here

all Boltzmann would have been happy Gibbs
would have been happy if I screamed was

a layer of ice and some concentrated sugar
solution the needs to be something else

happening to explain why we've got lots
of little crystals happening here and

here we need to talk about this idea of
the formation of an ice crystal clear so

here are these little Mickey Mouse
things in my water molecules and

the blue ones I'm showing either
on the wall of a container.

Or in the middle of the liquid a few of
them are starting to come together and

form ice crystals that
locking together and

the first few molecules are choosing not
to be in a liquid but choosing to be in

a solid Instead it's a tiny crystal it's
containing a few handfuls of individual

molecules you couldn't see it with
the best microscope in the world tiny and

it's terribly hard for these things
to form we like to think that if you

get water below zero degrees Celcius is
going to freeze solid it doesn't work like

that in order to go from a liquid to a
solid You need to form a tiny crystal and

that Crystal needs to grow out and grow
out and grow out and eventually the whole

thing will solidify but tiny crystals
are unstable they're much less stable than

the big ones are it turns out that the
shape of them they haven't got extended

microscopic shape they need there's all
kind of crushed down and twisted and

curved by being so small that this
makes them much much more unstable so

you can do this experiment
yourself if you dig around

on You Tube you can find people
filling bottles of water and

put in the freezer overnight pull
them out really gently buying them

against the wall of a container of
the table and it freezes instant.

Heinously the water was super cooled
cooled below zero degree Celsius but

hadn't gone through its phase
transition yet it hadn't solidified.

So the what you tend to see is
this Prop four with a tendency of

forming ice crystals is slow
the way to get it to go faster

is either make sure it happens cold or.

All its happens on some
sort of rough wall so

the wall of an ice cream
freezer the side of a bottle or

a surface makes it much easier and
as you start to cool ice cream down

you'll see you'd call the water down you
get it down below zero degrees Celsius and

you see these little crystal tiny tiny
crystals forming and they just fall

to pieces in the form they fall to pieces
they form in the fall to pieces so

you have this rate of formation
a couple of degrees below zero slow.

Slow You keep on cooling
it's it gets faster.

Get down to.

Minus twenty it's going pretty fast
someone pulls liquid nitrogen in.

Ridiculously cold astonishingly fast it's
happening here the way you do it in an ice

cream freezer or you'd have like ice Bryan
on the outside you have a metal wall

in a scraper going around that metal wall
is much much colder than the ice cream out

and that's the coldest place there and
it's a rough surface even get crystals

growing out there most of these these
little crystal embryos disappear but

a few of them start to grow up to
microscopic cell size if you had a fast

nucleation rate you're going to end up
with tons and tons of crystals if you had

us low nucleation rates in a few of
them are going to get the same amount of

ice in the end depending on those phase
diagram things I drew but it might be one

giant ice crystal or it might be
billions and billions of tiny ones and

an ice cream making we want billions and
billions of tiny ones the reason.

Lives are the ice cream you just made was
so good so smooth was because your your

cooling was so aggressive it was able
to get it super super super cool so

the rate of nucleation was incredibly
fast if you'd done it in a domestic

freezer you can get that cold to get it
down to about minus twenty degrees Celsius

if you're working really hard rated
mutilations much much slower.

Same advice in the end.

But spread out over fewer bigger crystals
so your ice cream I didn't get to

try any of the first one should have
been amazingly smooth domestic ice cream

you can sometimes taste the ice crystals
the defect we talk about says it's icy but

it's not the difference in the amount of
ice it's the difference in the size of

the crystals that's all of
us in a few big ones or

spread out over a whole
bunch of small ones.

The said would work on an ice cream
freezer so this would be a domestic one so

you'd have the ice Brian else here
the black line is the metal wall and

the ice cream mixes that blew liquid out
there the coldest place in the ice and

in the freezer is on that metal wall so
we're going to get it like again and

again and again the ice crystals will
start growing out from that wall and

eventually this metal blade the dasher
is going to scoop around and

scrape that surface in again and the ice
crystal floats off into the center becomes

an individual crystal already a new
crystal is going to start growing in

that wall and eventually it's going to
grow out and make the frozen ice cream

we didn't have to do that because
we had liquid nitrogen so

it was crystallizing inside the bulk of
the liquid you really get this effect

much more dramatically though if you don't
mix it a toll you could never make ice

cream really without running a mixer but
you can make popsicles

As are going back to the lovely photo
of the air you showed us earlier Molly.

If we try to make popsicles popsicles and
dead easy it's just sugar water so

sugars that depress the freezing point
water that's that's the phrase and

poured into a mold in.

Put a stick in and I'm going to lower
it into a refrigerant solution so

that mold like those is going to end
up sitting into some cold liquid and

I'm going to leave them there overnight
and eventually begin to freeze.

Could we stop passing on the popsicles.

Whose popsicle possible.

So when you start.

Can we click again please.

So as the stuff starts to freeze
where the ice crystals going to form.

The going to form in the coldest
part of the material which is right

on that metal wall and they going to
start growing in towards the center so

here's one ice crystal which is growing in
here the sugar solution is getting more

concentrated as the ice crystal
grows then eventually click again.

We're going to get these crystals
growing in from the coldest part

towards the center if I wanted to
make this into a beer a saw a or

an ice cream instead of being a popsicle
I'd have to scrape that surface and

move the crystals into the center but I
want the it to be a popsicle shape here so

what I want you to do is to bite into
your popsicle and bite the top off and

I'd like you to look at that
surface you've just exposed and

show me and see how the crystals
are arranged inside that Popsicle

you should see this lovely radial
symmetry from the outside in

because the crystals grew from
the outside heading towards the center.

The next thing I want you to do is to try
and convince yourself that this isn't

a one phase materially or
it's saying it's a two phase material so

like you just suck on that Popsicle
as hard as you can make your face

turned purple and see if you can
pull the unfrozen phase out and

leave the crystals behind except
like they do that for me.

That's cool.

So hopefully you can move out this is
the should the colors in the flavors.

And you can separate out the different
phases in popsicles and.

That's one.

So thank you and that's pretty much all
the material I think we have today so

I'm I think I'll be happy to
take some questions of them.

The owner.