Well Tom that's me.

I've got a six professor.

Yeah Georgia.

Better to have you here for
the third squishy physics.

Which as you probably know it's
one of the all with chocolate.

So I want to tell you a little bit about
the science and physics of chocolate.

But before that I want to thank some of
the people that have actually made these

possible or have contributed
to a very large extent and

I want to start by thanking
the school of physics.

Right.
And in particular Eckstein.

Also I'm thankful to Dr a brake on me.

Sally from the rain very much.

They've been helping throughout
every single detail that organizing

something like this requires.

I'm also thankful to the College of
Science and I'm one I think well for

our being professional for both Burke
he's been support these are supporting

these events from the very beginning.

Janet Zebul the graphic designer and
colleague of signs us help with

the posters on the Flyers all worth
anchor and we thank her for that.

Also on faculty the office of the Provost
actually for their GED fire program and.

Kind of our fire type of grants
right to do sort of new things and

they are sponsoring the creation of
laboratories that are going to allow to

bring squishy physics training
to the undergraduate and

graduate education at Georgia Tech.

So I'm very thankful for that support.

Mr HOAR have he's been also very
enthusiastically supporting these events

in the very beginning he said
the director of favor manufacturing of

the Coca-Cola company.

Dr Conrad who sitting right here and
she's also been very supportive

from the beginning we have a Georgia Tech
nurse the Materials Research Science and

Engineering Center that we
have here at Georgia Tech.

And then we have two new
sponsors that I like to

work on these year does really well you
are on the Institute for bio science and

by engineering at Georgia Tech.

Finally but not for that belief that.

Very thankful to the firm
on Science Center.

They are the main organizers of the
squishy physics photography contest and

in particular I'm very thankful to
the director Mr Douglas Robbie and

also to Mr Tony made it.

So thank you to all of you.

It's because of you that you
know to a great measure.

We're here today.

All right so without any further dilation
let me just announce the winner of

the photography contest or

we have two winners each year
are both fast six graders right so

the first prize goes to unleash Kumar
from Fort Hills Middle School and

the second prize of all tools the giant
from Shadow mentary so come and

see me at the end of the event will
give you the diplomas and will

range how to get you the track associated
to your prices so congratulations.

OK and then let me introduce you.

The the stars of the first
question of physics

are today physics professor Arjun year old
from the University of Pennsylvania and

William Yosef from the White House.

So I like to start with a chap
he often he's a bachelor in arts

from University of Toledo he's master
in art from Rutgers University.

He's double A Yes the green from
New York City College of Technology and

throughout the time he actually worked
with known very famous chefs the blue and

Thomas Keller then he went and
began using the pen a career and

he operated at the pastry Parminter Tavern
on the Green restaurant in New York City.

He served at this as a pastry chef a munch
are a restaurant in New York City also and

finally he planned on the sign and opened
the pastry department on the restaurant

and bakery two thousand and seven.

He's the executive pastry chef at the
White House and he's actually contributed

an interesting book that I
strongly recommend the search for

Dummies was published in one
thousand nine hundred seventy.

Recently Perhaps you've actually read up.

Already in the news.

He announced that he's leaving
the White House in the coming June.

So he's a fantastic person and

he said willing to give up such
a job to actually initiate some

sort of educational activities in trying
to bring people to hear it healthier.

So as he was saying the other day you can
actually have a highly delicious food and

that should be an objective frame but
at the same time you.

You can have healthy food.

So in addition of weaning the leashes.

You should also eat healthy.

So that's a new endeavor that he
actually had undertaken in the past and

he's going to return to the physics
professor that we're having today is hard.

You know so Arjun obtained his bachelor's
in science from Cornell University Ph D.

from Harvard University and

then he to postdocs our Bell Labs
one of them we Nobel Prize winner.

Steven Chu He then joined
the University of Pennsylvania.

That was in one thousand
nine hundred eighty two and

he's been there since then
he's actually educated or

graduated more than thirty graduate
students through all these time.

And he's contributing
contributed around three hundred

papers many of them that
have very high impact and

that has been very influential work
once all his current position.

It's associated mainly with the part of
the physics where he's a professor of

science and he's also the director
of the center funded by

the National Science Foundation and
he says research interests broadly protein

condensed matter but in what we call soft
condensed matter because you're dealing

with materials that are squishy and easy
to be form right and it turns out that

he's also very interested since the very
beginning optical sciences and he's

dedicated part of his career to use up
the X. to understand Biomedical Problems.

So what are we going to hear about today.

So we want to start with Arjan.

Is when I tell us about some of
the chopper fundamentals and

I tell us the experience more or less what
Chuck ladies some of you may know about

I'm sure some of you may not and
some of you may or some of you.

I know but there are plenty of surprises
when you actually think about truckler So

in terms of any concrete slicing
sixty from Ford for example

there's only one of them that we like
as a costumer So when you each outlet.

You will actually enjoy the most
any one of these for six weeks.

So we went up quite a bit of our
faces on face transitions and

how you go from one face to another
from one crystal to another crystal

phaser from a crystal to a liquid face.

I'm interesting liaison I illustrate
all of these with some of his research.

So he does.

Beauty for experiments you
see not the gun microscopy.

Where he images little particles
are Gielen around with the thermal motion.

We call them call it right there
to some extent like a knot on

my saw the mini classes you can think of
as classical objects that if you think of

an atom Classically there
remain a simple bam.

So they geve all on the crystallize and
they do things like the atoms do.

So he uses these to learn about
physics right in general and

condensed matter in particular and
then he also tell us about emotions.

Which as it turns out it's a way
a very interesting way to try and

mix substances that naturally
will never means OK.

And then the chaff air will take over
right and he's going to do some magic.

Well after though no not really
matter exactly level physics for

exactly when I was some experiments
is going to cook something and

hopefully you know you get
the perception that physics.

It's everywhere.

And so he actually made there two or three
research so it made actual playground

Ashworth use novel ingredients on the
whole saw plainly to be with the texture

whether they're stiffer or softer and
then he's also going to make a forms

of these is something that looks like
a solid body sets intially compost over.

So it's pretty intriguing and
so you'll see that in action.

So I hope that you will enjoy my event.

And I hope that you were inspired by
the event also I hope that you will get

the feeling that many of us have that
physics is about explaining nature and

natural phenomena.

Not necessarily only
thinking about electrons or

atoms or quantum mechanics finance
essentially about everything on food and

cooking and you know food
transformations are no exception.

So I really hope that you'll
be inspired by the event and

that you'll start thinking
about the physical properties.

And those transformations
that he was when you cook

that I'd like to welcome
the speakers of the Saturday.

Thank.

Well thank you.

Wilbur to for.

Putting this event together and
for inviting me.

And I know that you're all
here really to see Bill.

But you know my favorite subject
I'm going to tell you about

my goal today is just to tell you about
my favorite subject which is physics.

And in particular I'm going to you

know tell you about phenomena
in soft matter physics or

squishy physics and
some of the brushstrokes

I think you'll see will overlap with
some things about chocolate and so.

What my plan then is I'm going to disk
give a little background on chocolate to

kind of set up some of the things
that I'll talk about and

hopefully come back to at the end and but

my main you know the main
goal here is is this

is to you know talk about matter
phases phase transitions and.

I want to just not just tell you
about the phenomena which you might

read about in a book or
something like battery of it.

Basically I want to convince you a little
bit that this is these are questions we're

still thinking about in physics.

Right.
Would we don't really understand them all

that well and I'll show you some little
tidbits of stuff that we've been able

to understand in our lab
in the soft matter side and

then we'll go back and
I'll talk about again.

Alberto already has.

Told you the chocolate has six.

I think different solid phases
one of which we like and so

I'll sort of come back to that
a little bit and then I'll talk about

how do you mix mix stuff together
doesn't like to mix together.

OK So first to you know certainly
even though I like physics a lot.

I also like chocolate and
this is sort of a world map

showing sort of where it's grown is
really in the temperate climate here and

the trade routes from there to
places which eventually get to us.

And so
this is something that sort of worldwide

importance in interest and it starts.

If you like with this tree
of the cocoa tree and

if you look in the tree see
that there's these pods and

if you cut open the pod you'll see
that there's these kind of beans.

And basically the first thing they
do is they take out the beans and

they ferment them and actually there is
a huge amount of science of physics and

biology and chemistry and
metabolic your shoes having

to do with fermentation which
I will say nothing about.

Then they drive them and
then they grind them again

there's all sorts of interesting things
to try to understand people do that in

the good physics and chemical engineering
about sort of the mechanic Ryall A-G.

of the mechanical forces in the response
to mechanical forces in volved and

in something like this which
again I will not talk about.

And then at the end of
the day you get sort of well

there's you know there's all sorts
of different kinds of chocolates but

the main three things I'm
going to focus on today which

are the main three if you get one of these
seventy five percent chocolate bars.

You can go to Trader Joe's or
something and

get that it basically has you
know sugar which is really added.

That's not from the cocoa bean and.

And it has cocoa butter which
is essentially the background.

You know but that takes up most
of the space in the chocolate.

And then there's the cocoa nibs which you
keep brining up and that gives a lot of

the flavor of the chocolate and I want
to you know you take these things and

you mix them together and you feed
him up and you cool him down and so

on and you make it make it make
a chocolate bill so you stuff like that.

But you know you have to
mix these together and so

you know I want to tell you a little
bit about how you do that and

just again as if you just sort of
point out a couple of things the sugar

basically is something that's what's
called Polar right and so that polar just

has to do with how the electric charge
is distributed really in the molecules

that make up the sugar but the bottom
line of it is that it likes to be water.

The cocoa butter though is not polar OK so
it doesn't like the water and

then the cocoa nibs.

They're complicated but there tend to be
a little bit more polar the non-polar and

somehow you've got to mix all
these things together right.

And so.

What is probably there is some most people
here know what's sort of when you think

about mixing two things that don't like
to mix what do you think about oil and

water right so we have to fix sort of so
solve that problem.

The oil and water problem.

So I'll say something about that and

then again just to remind to reiterate
that cocoa butter is playing a key role.

It's the SOL it's sort of
filling up most of the space.

Again it depends on which kind of
chocolate you're talking about but

often it is and it's even Lee dispersing
these chocolate nibs in the sugar and

then the nice thing of course
is that you can hold it.

You know you can snap
it at room temperature.

But when you put it in your mouth it melts
which is a nice thing about chocolate.

So we'll talk about then in connection of
that crystal phases and the surfactants.

OK So
let's let's talk about matter in fees.

So first of all again.

Bases matter you're you're familiar
with an every day life was the most

probably the most common one is use of
water right so in the gas phase it's steam

in the solid phase it's ice and
then you can have the fluid liquid face.

Lots of materials have different phases.

I mean so here's gallium.

Right.

Gallium it turns out is.

You know roughly your body
temperature can melt and so.

So this you know this problem
about having faces and

making transitions from one phase to
another is sort of a ubiquitous problem

in physics that we try to understand.

And certainly you know and then that and
I want to sort of at least give you a sort

of a way that I can think about
understanding that in a simple context.

OK So one of the so
the first thing I should say that you

want to do business is often do is try to
figure out what what things are made of.

Then you've tried to
understand the properties and

try to make a connection between how
they're put together in the properties and

then and then you can answer questions
about how does it transform from one kind

of phase to another for example but so if
you look at the building blocks of matter

right in anything like ice if you take
ice and you just sort of magnify it and

magnify it and magnify it what you find
in the end is that it's sort of made up

of one sort of elemental unit which is the
water molecule right which is oxygen and

hydrogen and
I mean you can go further down right.

You know if you if you
looked at the oxygen.

Right.
It's got electrons it's got protons it's

good neutrons.

But for most of the sort of.

Every day chemistry stuff is so
the soci with food and

for many things really
this is sort of the end.

Elemental building block and
that's what I'm going to.

I'm not going to worry too much about
the stuff that's inside the atoms.

OK So you know this is what happens when
you sort of magnify down with with water.

You know you can do the same thing for
table salt.

Right.
And if you did that what you'd find at

the end of the day is that you have
sodium atoms and chlorine atoms

arranged in a well defined way and some
kind of a pattern in three dimensions.

And you know even if you
look at cocoa butter.

It's a lot more complicated bollock you'll
But you know you can break it down and

in fact sometimes there's often
more than one kind of molecule.

But roughly speaking you get sort
of a relatively it's still there

sort of a molecular building block
that looks kind of like this.

This is kind of a model of it.

It's got three tails the tails
could be all pointing backwards.

Often the you can have one pointing
one way into pointing the other way to

kind of a Y..

And but you know so this is kind of the
fundamental pilling block of cocoa butter

and it's made out of carbon and
oxygen and hydrogen.

And.

I'm going to you know in understanding
you know phase transitions.

I'm going to do something
that here the physicists

often do in this just simplify this.

OK So you know these are complicated or
relatively complicated

molecules especially the cocoa butter but
I'm going to sort

of imagine then I'm going to think of all
of these as just a sphere or a particle.

OK And what I want to try to
understand is if I if I you know what

properties of this particle.

Does it.

What properties does this particle
have to have in order to sort of have

a possibility that it could have
a solid phase and a liquid fifty's.

OK And so.

And it turns out actually that this
approach actually works very well to

understand many things and
there's sort of a few things.

They get you along a few properties about

this these these don't think of them
totally as like billiard balls right.

They could mush into each other
they could sort of overlap.

But basically these properties
that you can attribute

there are a couple of them are enough
to understand why you might have the.

These different phases and so this is sort
of my most probably my most complicated

slide but basically so
I just want to talk about what

are the properties that generally
these particles would have.

OK And this is true then of these cocoa
butter molecules at some level of the of

the water molecules.

And so on.

And so on the left hand side just
focus on that first basically

just the main thing is that when they're
far apart they don't feel each other.

OK.

So you don't really you
know one can be moving this

way one to be moving this way they
don't affect each other's motion.

And then when they're very close.

They feel each other very strongly and
they want to repel each other.

OK So this is like this arrow
is like a force vector.

Right.
So if they're pushing they're being

pushed apart when they get too close.

And then there's there's
usually a scale at which they.

It's like the bear story of
the Three Bears of in-group.

I forget the name of the story but

basically the Goldilocks total
Goldilocks in the three very you

know basically you know the this is
too far apart this is too close.

This one's just right so there's this one
distance where generally you can find for

many molecules most typically that there's
a distance where they like to sit apart.

Yeah that's

a good analogy you know right.

Now so on the right hand side.

I'm sort of just restating this but

in a kind of a diagram people often
use having to do with energy.

OK So just this dash line here would
correspond to zero energy if you like and

this is for hydrogen but it could be for
anything and my ball right.

And this this axis here is just
the distance they are apart.

So over here they're far apart.

Right.

And basically they have it doesn't
cost any energy to be far apart.

You don't even know each other.

So they're over here.

They're too close.

So it costs a lot of energy.

This is positive and
they want to go down the hill.

Into this little well here which is
where they do look which is just right.

It's a sweet spot where
they want to sit and so

different and you know generally
most molecules have this kind of.

Three features and you know what.

What can matter.

You know is one of the important things
that can matter is how big is this

this sweet spot how energetically
how low is it compared to zero

because you know it's
that's what's binding.

It's the binding it.

OK And so
just now I want you to keep that in mind.

OK So this is what I would call this is
sort of sort of associated with the energy

of this of the of the system and
it has to do with how far they are apart.

OK So
given that you know can we understand

the phases of matter let me just
remind you about the phases.

You know most of the time you think about
three phases liquids and solids and

gas is right and so
in the solid case right.

I'm telling you this and
you'll have to take my word for it but

basically right these are basically
these these these particles that we've

made some of these molecules
are sitting on some order to Ray and

you know a solid Of course it
has a well defined volume and

it doesn't change its shape unless
you push on it pretty hard.

A liquid is has roughly the same
density actually usually as the solids.

But it's disorder.

And so you know if you put it into
a container it'll sort of take it'll have

a well defined voluble take the shape of
the container it contains shape easily and

then the gas of course is just very

the atoms are very far
apart like in the scene.

And so if you put it into a container
it will expand to fill up

the fill up the container.

So those are the three phases and the sort
of can we understand why we get them in

the context of that little model of
particle interactions and the answer

is you kind of can you just need to
sort of want to add in one important.

Idea and that has to do with temperature.

OK So temper.

Basically it's like a kind of
a measure of it's random the random.

Jiggling this.

If you like of the particles.

And so you know at low temperatures.

You have a you know relatively little
amount that you're shaking at higher

temperatures you have a relatively higher
amount that you're jiggling around.

And so if you think about it when
you go to a low enough temperature.

You can get stuck in that sweet spot and

you don't have enough jiggling
energy to get out of the sweet spot.

So they sort of sit there roughly at that
sweet spot in this crystal then if you get

a little bit higher in temperature
jiggles a little bit enough enough so

that it can get out of that little sweet
spot it can get out of that little well

it doesn't really escape
that far from each other.

It sort of knows that that was there but
sort of it becomes disorder.

OK so so so that you can kind of see and

then of course you know if you go to
higher and higher it's easier to get away.

And so you know so that so you have this.

Potential energy of interaction
between the atoms that's important

to the particles that's important and
you have this other thing.

Due to temperature causing them to shake
randomly and it's a competition between

those two things that determines
whether you make a phase or not.

And you can be a little bit
more precise and I just want to

introduce one other term which don't
worry I won't use that much again but

it's kind of a cool thing
which is called entropy.

OK And that's a.

It's a it's a quantity it's something
that you can measure about these systems

it has to do with it's disorder.

And in the Second Law of Thermodynamics
sort of says things tend to become

disordered.

If you know if I saluted and
left to their own they're the evolved to

having the maximum entropy or
the maximum disorder.

So in terms of figuring
out what phases forms.

It turns out that there's something
called a free energy which is basically

a competition between this internal
energy having to do with whether in

those sweet spots in the well there or
not.

And this entropy term which
depends on temperature.

OK which is sort of a disorder.

Systems.

So again at low temperature you
have a typically and most distant.

You have the you is big because
you're all sitting in the wells.

And the entropy is low.

Because it's ordered.

OK And as you go higher in temperature
the sort of trading off order.

If you like an energy.

For disorder and entropy.

And so if you want to calculate what
phases before you can start with

a microscopic model of your system and
you can in principle try to come up with

the systems that have the lowest free
energy at any given temperature.

So that's something that is
going on in our community.

OK so yeah.

So that's sort of what I wanted
to say by way of background.

And then I just I did want to before
I show you some of our some some

a few results from our lab just
just to remind you again that

these problems even though they
might seem like they're solved

because often people tell them to you
like there's all there and they're not.

OK There's lots of questions what kinds I
took he told you about solid clicks and

gases are there other
phases they could exist.

How are they similar or dissimilar.

If you have a crystal I'll
show you something about this.

Where does it start when you melt it.

How does it start melting does it start
melting from the surface to start melting

uniformly throughout it is there a way
that I could control that if I want to

make a crystal certainly in chocolate you
want to make the right Crystal Wright.

Actually it's much harder in a way because
there are five different kinds of crystals

you could make your six
different kinds of crystals.

But what one of the things that you
can do to try to make a good person.

What happens if you cool to fans and
tails.

So I'll say a little bit about these
things these are still questions that

are not understood.

Well OK so our lab like

Alberto's Actually we do experiments
in soft matter and one of the one

of the fun systems that we work with
there are basically particles in water.

OK so these could be plastic particles.

These could be the last part.

Because these could be Paula.

Fancier particles made out of
polymers that can change size and so

but basically we put them in water and
then we pack them really tightly and

we we can make essentially thermodynamic
systems equilibrium systems

which behave in many many ways
like like water like ice.

OK I skewing to liquid water and so
on and we can see the good thing

about these systems is I can change their
shapes I can change their sizes I can

change their interactions even but I can
watch them generally in the microscope.

So I can see what's
happening to all the atoms

which is generally a hard thing to see.

OK so what we're going to
do is I'm going to take

stuff like this these kinds of particles.

You know maybe different shapes I'll
start with the spheres though and

put them into a sample cell.

You know it might be pretty thin and you
know the particle might be about a micron

or maybe even an animator you
know a few few hundred metres.

And but I'm putting it into a cell that
might be one hundred fifty microns thick.

So there are lots of layers
it's a big book system.

I'm going to show you pictures
mostly there to be pictures.

That's just one slice you'll just
have to get the idea from that but

you know also use some movies where
we're scanning through and so

you'll get the sense that it's three D.
and then basically we were a bit.

What we do is we just sort of mix these
things together to change a little

condition look at what happens.

And so again this is this is the kind
of two dimensional slice you might get

when you take these micron sized
particles and you pack them.

Fairly tightly.

That's a slice in the sample.

So you can see all the little particles.

Many of them.

OK so.

I talked about crystals they talk
about liquids Here's basically

we took those particles we
put them into these cells.

Here's some pictures of them
at different temperatures.

You can see.
The low temperature it's basically

ordered and they're moving a little bit.

This is a crystal.

Then I got a little bit higher
temperature and still Crystal and

actually if you look at it.

They're all ordered they're
sort of hexagonal e.

Symmetric and then but
they're jiggling a lot more right.

And then I raise the temperature
a little bit higher.

You have a coexistence
between the crystal phase.

That's ordered here but
you're going strongly in a liquid phase.

OK so here's sort of taking this soft
matter system of particles in water and

sort of mimicking if you like
the crystal to fluid formation.

So that sort of going from a crystal to
a liquid you can also go the other way

you can start in the liquid and this is
of course something that's important for

chocolate start in the liquid phase and
then get to the solved.

OK Also a little bit about that.

Again but
in that case by lowering the temperatures.

OK so.

So one problem that we work done and
other people have work done.

Certainly is to try to understand when you
have a melting event where does it begin.

OK.

In so we made these crystals of particles.

Let me just show you one.

This is a crystal.

This is looking at it in a microscope this
movie is just scanning the image plane so

you can see you can see that
there's all these particles that

you know they're sort of.

Like those little spiritual spots they're
ordered but I hope you also saw that

if I had as I scanned through it wasn't
just a perfect crystal there was defects

right there were stacking these
are called stacking defects.

There's a defect there.

You know it still looks like a crystal
it's still kind of crystal in for sure but

it's not it's not like everything
is perfectly arranged.

OK.

And so if you.

You know here's an example of one that
we've sort of had a lot of fun with.

This is called a defect it's
called a green boundary.

So you can see this is
again this is a slice.

But over here you have an ordered
crystal over here it's ordered but

their orientation is rotated.

OK And the rotation of
the orientation is is across this

thing here called the Green boundary.

OK so a green boundary is a kind of a
defect it makes it something that in this

crystal that makes it different from being
perfect and sort of we had this idea and

actually other people had this idea too.

We were able to do the experiment that.

The atoms basically near the green
boundary they're not really exactly where

they want to be OK And so if you like
they're not perfectly in those wells that.

And so basically if you're going to start
melting that's a good place to start

because they're not energetically
in their lowest states.

And so we didn't experiment
where we basically took

we found a green boundary
in these crystals and

we looked to see that it indeed start to
melt there and it just melt everywhere.

OK so it could have been were
sort of My guess is that it would

start to melt around here but
it could also just be melting over here.

OK.

And so here's these are these are movies.

Showing this is that lowered
low temperature where it's

still solid completely.

And this green boundary you can see
here as I'm scanning through the sample.

I'll do it again.

It's actually you have to sort of
spend a lot of time staring at this.

But you know you have to take my word and
actually I didn't really do it my grad

students did but
basically basically you can convince

yourself it's a pretty sharp interface and
it's a solid solid interface and

it's basically the same crystal and solid
but different orientations of the crystal.

Then if you go a little bit
higher in temperature and

you stare at this a long time.

You can think well maybe there is a little
bit of disorder not just disorder but

a liquid like behavior along
these the screen countering so

I'll just look at it again and again I.

Expect that you could
tell that necessarily but

you can certainly tell it here.

OK.

So here you can see well we've got
these two crystals over here and

it's really started to melt in the middle.

OK So this is basically the kind
of thing that we were trying to

see if we could understand and you know if
you keep raising the temperature then that

region keeps growing until eventually
it and follows the the system.

OK And you know I don't want to you
know so we saw this one effect.

We were able to learn about it because
he looked at it very carefully and

then there's like about one hundred
million other things to try to understand

you know if this is a bowl Crystal how
does that differ if it was a thin film.

OK this is going from a liquid to a solid.

Well what is the similar kind of physics
going from a solid to a solid OK

and so on.

Another thing is that talking here about
going from a crystal to a liquid What

if we want to go from
a liquid to a crystal.

OK how do we do that when we know right.

You know certainly if you have
a liquid and you want to make ice or

something you lower the temperature.

But it turns out right.

If you want to make a really good crystal.

Like this.

OK so if you look at this.

There's it's not perfect but
it's pretty good.

I made this by doing it very very slowly.

OK cooling it very very slowly.

So all the atoms if you like have time
to find their lowest energy state and

they can move a little bit in and so on.

Now if I did that fast.

Then you wouldn't get all these liquid
atoms that were initially in these

disordered positions don't have time to
move and so they get they get jammed.

If you like and you make a disordered
structure which is the glass.

OK.

And the glass has a lot different
properties than a crystal generally.

And even for this these different phases
of chocolate if you if you if you make

it with a glassy if you
cool it too fast then

basically you can make
something that's not very good.

OK So this is something again to disk
even mind as we go when we go back and

talk about chocolate The other thing
I just wanted to say because it's so

amazing to me every time I think about
it is that you know I've made you.

Hopefully think that those
complicated molecules are spheres.

OK.

And spheres with just this little

little property that they
like to be close together.

OK.

At a certain special place.

But what if I just change the shape.

Right.
Certainly those

molecules have different shapes.

What if I just you know the nice thing I'm
thought matter is you can sort of have

these objects and
you can literally change the shape and

look at what happens is
still a term of damage.

So suppose that I changed it from
a basically a sphere to Iran.

All right.

You know you could still imagine that
the rod could have or could have arbitrary

positions like in in a liquid you
could have arbitrary orientations.

So you could still get liquids and
gases and solids in principle but

you know let me just ask you I mean do
you think that's all you'll get no right.

Good I guess I set that up.

Well for you and I have to think of
a better way to set it up but OK so

there's a very you know.

So so the answer is.

That's right.
There's there are the faces or

some of them are the same but
lots of them are different so for

example you know liquid
crystals which are basically

the molecules used in your displays
of almost everything right there.

Basically they're not they're
not these big particles but

they're on a molecular level
they're like little rods.

OK And so.

It turns out that if
you pack them tightly.

But not so

tightly to make a solid you can make
something in between a solid in a liquid.

So this is basically what I mean this
is called in the manic phase and

the the rods are basically they're
just ordered in position but

they're all generally pointing
in roughly the same direction.

So this is this is a sort of
an orientation of the ordered.

And that's sort of the most famous
thing about the crystals and

this is sort of the phase
that's really heavily used

in these displays because you
can you can manipulate light.

That's traveling through
medias where you have

all the molecules lined
up in one direction.

You can manipulate basically
the polarization of light by switching

the direct OK with an electric field.

So.

But not only that.

OK So this is the regular kind of
a liquid This is an ordered liquid.

But if you actually you know this is very
rich and I just want to emphasize that

if we take rods we can start
with this regular liquid and

then we can make a liquid kind of
where there are there are layers.

There all generally oriented
in one direction but

there's kind of a layering OK So there's
kind of a one dimensional order this way.

You can even have the layers
with their tilted OK

it's instead of a rod like molecule
you have a plate like molecule you get

all sorts of other interesting phases like
you can get these poker chip stacks right.

And this is really a lot of fun to
figure out what are the phases and

there are many surprises and there
are many interesting things about this.

And so you know we actually
started to try to do some work

in there where to does a lot of
work with this to try to sort of

make some liquid crystal systems that
we can look at in the microscope.

And so to do that we made a rod
this right is a dead F. T. virus.

So it's about a micron
long one hundred enemy and

it's pretty narrow pretty pretty pretty
and its diameter is pretty small.

So it is very much like a rock and then we
just take these rods and we put them in

the water and we had a polymer and
we change their concentrations and

change the temperature and you know these
are the I'm not going to explain much

except to show you these are pictures of
the kinds of things that we saw right.

So these this is a cartoon
of that sort of one layered

that layered one dimensionally
ordered material.

Right.
And this is this is this is the this is

the actual image from the microscope
this is the cartoon of it.

These.

The rods right there.

You get a sort of a sheet of it then you
get some polymer another sheet polymer

Here's a defect actually when the sheets
come together and sort of to go into one.

And so on and then you can raise the
temperature and you can melt these things

you melt these these layered
structures into this so-called nomadic

structures these orientation of
the order structures and so on.

You can even make droplets of that.

Here's a movie of the droplets you can.

So this is a droplet that starts
as a layered structure and

just raising the temperature and it's
changing shape because it's changing from

a layered structure into that orientation
toward a liquid I'm melting the sort

of one dimensional solid into a liquid.

OK so
you can imagine that this is crazy fun and

that's you know again that's
something that we do.

OK so now I want to go back.

And I'm not an expert in chocolate really
but I'm just going to try to sort of

show you some of the areas where there
were some overlap in these ideas.

And I want to talk at the end
of course but the mixing.

OK So again just to remind you.

This cocoa butter which you can think of
as the kind of background phase in which

everything is put into.

So the sugar crystals
are going to be put into it.

These chocolate nibs are part trumpet
particles are going to be put into it

the cocoa butter basically looks like this
it's this big you know it's got these

three chains hydrocarbon chains and
they make kind of like a Y..

OK So you know I've asked you to think

about spheres I told you
a little bit about rods.

You know you think that you could make I
mean I wouldn't necessarily even think

I could make a crystal with this and
it's kind of a weird object.

But the answer is you really can't.

And so you know you can't just
unfortunately there's a molecular size.

So you can't really just look
at them under the microscope and

figure out what what the what they what
they are you have to do things like

a very common trick is to do
with called X. ray diffraction.

And you can.

So you take X. rays you scattered off
these samples and you look at the pattern

of spots that come off and then you
work backwards like they did for D.N.A.

to figure out what's the what's
the crystal structure inside.

I just want to emphasize
that just one thing so

you here's just two different ways that
you could have packed these wives right.

So this would be one crystal type
in which you could see the red just

look at the red right.

The red and then there's a black line and
there's a red Y..

But here they're all three in a row right.

So this is a different structure and

because of it's a different structure
it might have different properties

in it if it's a it's energetically
likes to be in that position more

might be harder to break the heart
might have a different melting point.

So all sorts of things.

Also they're not all that different.

So you can think that well you might be if
you're not careful you might get both of

these kinds of structures forming
at the same time in your.

In your material.

OK And
that's in fact what can often happen.

So here's here's the different faces

of cocoa butter and you know this is
sort of giving the temperatures that

they like to live at and you know many
certainly most of these these faces here

are kind of crumbly there they don't like
you know people don't like them very much.

This one.

Here's the good one five.

OK So people want to get five.

OK that one has this nice shiny appearance
snaps and it melts in your mouth.

OK so how can you get this.

I think I think Bill is going to
show you something about this.

But let me just show you something
to OK So it's kind of tricky and

actually this whole business of
making good crystals is tricky.

And that's so
that occupies a lot of people's time for

not just these kinds of crystals but
for protein crystals because you

want to figure out the structure
of the proteins lots of things.

So here if I start this is what I'm
planning here is temperature and i'm time.

OK so I'm putting the chalk.

Put in a pan and

heat it up and it's usually very common
you heat it into if you want to sort of.

You want to you start in the liquid phase
you heat it up into the liquid phase and

then you call it down and here's just
two different things that people do

they let it cool down right into that.

Good good sweet spot to make this phase
five usually that doesn't work all that

well and so

people what they would do is to add in
little they have from somewhere else.

They have these little crystal
lights of the right shape and

size of the right face and they just
dropped a few of them in and those

that like nucleation sites where you can
grow the right shape to kind of crystal.

And so that's a common thing that's done.

Another thing and I guess that's more
recent that people are doing that.

According to Bill.

The other thing was that you can you
can actually cool it down lower So

as you cool over here you'll get a little
bit of this phase and a little bit in

the other phases and then you slowly go
back up melting the other ones when you

have the you have the good one that you
like around and then you can get that

one to sort of dominate the other ones and
you can get mostly one kind of things.

So this is one interesting thing this
whole thing I think is called Temp

tempering.

And certainly it's more complicated with
the five solid phases than it was for

going from the liquid to the solid but.

It's a similar set of ideas
that one has to apply.

OK then the other one just
to remind you has to do

with how to mix the different
parts of the chocolate.

And you know again you know
that if you have oil and water.

They don't mix.

You can actually get them to
kind of disperse if you shake

it really hard right.

And you can get these bubbles
forming of oil say in water but

then if you wait a little while.

Bill coalesce and
they will go back it will go back to this.

OK So somehow you want to make this
shake it and make these bubbles.

If you like and but have them stay.

OK.

So to do that.

You really need this
sort of magic molecule.

OK Which really is kind
of amazing lein useful.

It's called a surfactant and

it's a molecule and
here's one of them an example of one but

the main thing conceptually is that they
have one side of it called the head.

Usually it likes water.

OK so that's hydrophilic it's Kong and

then there's this tail
that's like oil like soil.

It's a hydrocarbon tail and so

if you think about well what will
this do if I have oil and water

even just in water will do and actually
does all sorts of interesting things but

just to first off if I have
an interface between water and oil.

Then these molecules
will go to this interface

because that way they can keep their
head which likes water and water.

And they can keep their
tail which likes in oil or

it likes air better than water too.

And so on and that's energetically lower
lower rates energetically favorable so.

But there's all sorts of other things
I just want to mention that these

thing these molecules can do so
we just had water.

If you crank up the concentration
of these of these molecules you get

what's called a myself.

OK So this is a little object
where the outside of it.

It's a spiritual object the outside of
it is near the water where it likes and

the inside is this tail
soily you can get sheets.

OK this is you know your cell membranes
like this right where the outsides like

the water in the insides like you
can put proteins in there and

stuff like that you can get vessels.

Right.
These are satirical the schools

water and water.

OK you can hold things in these vessels
you can deliver drugs in the invisibles.

If you really you know this is of course
you know I talked about phases I mean

this one has a mind boggling number of
faces you know but there's more variables.

There's the amount of water versus oil.

There's amount of surfactant in
general there's also temperature and

you can get all sorts of you know
I talked about these my cells and

things like that but certainly you can
get very rich kinds of other faces.

And so but what we want to do course
is to use this just to try to dissolve

the essentially dissolve the sugar
crystals not dissolve it all the way they

usually sort of have some finite size in
the cocoa solids into the cocoa butter.

OK.

And so the key for
this is something called lecithin

which is also surfactant molecule
basically and what it does.

Again this is.

In this is showing a how you
can stabilize the oil and

water is the you put the oil in the water
but you put the surf act in there right.

And then the surfactant
goes to the surface and

it basically forms a monolayer
of stuff on the surface and

then that that drop is stable because to
get it to be break to coalesce you have to

sort of break off these molecules and
they energetically don't like to do that.

OK so that's how you stabilize the oil and
water and

that's how you're going to stabilise the
sugar if you like in this cocoa butter.

OK So for
example here's the sugar crystal and

it's sort of the reverse
process where the head.

Head of the surfactant goes near the sugar
and the tails go into the cocoa butter

right where the fat it which is basically
oily and so you might get something like

this you might get some of this also
occurring around our cocoa particles but

there's a debate about
how that stabilized and

whether it's just kinetically stabilise.

OK So really that's what I wanted

to tell you you know just
hopefully conveyed a little bit.

Now you can have the best
part of the show but

hopefully you conveyed a little bit about.

Matter and phases and
phase transitions and

you can see that you know thinking about
these problems as some relevance to.

Understanding and
controlling really chocolate.

We can certainly ask question.

So those are all solid.

Yeah.

No.
So one phase is that's a good question.

OK So the question was so
I showed six pieces of chocolate.

Yes So they certainly you have
liquid at the high temperature and

then depending on where
you are the lowest energy.

Depending on the temperature then below or

becomes a solid OK there's
a different free energy.

If you look for those different phases.

So different ones are stable
at different temperatures.

So it's like a saw it still is kind
of like a solid solid transition

the way that I've posed that you
know actually to be perfectly

honest when I've been
reading about the chocolates.

There's usually a mixture.

It's not just one kind of
it's like a fat molecule.

And so that also makes it more calm so
thank you thank you.

Thank you thank you so much.

Arjun I always learn so
much in these kind of.

SESSIONS And this is no difference.

Fascinating and.

I start out by saying that when I was
first learning how to make desserts.

You know as an apprentice
working with pastry chefs.

You would sort of naturally have curiosity
and ask well why do we whisked this thing

that way or why does this happen and in
those days the chefs wouldn't answer you.

They didn't know themselves although they
would admit that they would just say well

because just do it the way
I told you that's why.

So this is sort of my reaction to that and
going deeply deeply into how.

Matter behaves has become so
fascinating and it's something that

as we as food seems to take over
every television show that we watch.

It's it's great that there's this
much interest on a Saturday morning

beautiful day that you would come and
hear us talk and

it's it's very gratifying
to me to see that.

So just as a brief introduction
I brought this picture.

One of many to explain what I do.

So this is a a cake that I made for
reception.

It's in the Blue Room of the White House.

Beautiful drapes there
that matched the walls

the room was designed basically
by George Washington.

And James Hogan the Irish architect who

who designed the White House
the room was oval.

So that's the origin of the oval it's not
the oval office the Oval Office is a copy

of this in the sense
that Washington wanted.

That's the main gathering room of
the House wanted to be oval so

there's no corners and
people didn't feel pushed into a corner.

This is after all for
him his image of where

people of different strains of
diversity came together to talk and

he was very conscious of
this type of interaction.

So one thing and we were talking about
this last night to be in Washington D.C.

has been such a exciting and
and thrilling adventure for

me and for one reason because
you begin to see the absolute

brilliance of the people who founded this
country and wrote the Constitution and

The Jeffersons Adams Washington's and
Monroe and Madison and

these they didn't come up with these ideas
as a just kind of random discussion.

They had read the histories.

Of Rome and Gibbons Rome and they read the
critique of the critique of givens Rome

and they really came together and
they were highly highly motivated to

make this new country work and they used
all their intellectual abilities to do so.

And remember this is seven thousand nine
hundred seventy when the Constitutional

Convention was held and
it still works today in a way.

But the reason I say that it works and
I'm convinced that it does is because

one of the most interesting
days of my life was to be

in the White House on January
twenty first two thousand and nine.

So before that I was there for
two years working with the previous

administration and you have West Wing and
east wing working very hard every day

on their goals and I mean just as a chef
we work with them because there's

always some kind of entertaining that
goes on when in the White House and so

then on the twenty and
the twenty first the offices are empty.

This is the nerve center of of
the executive branch of the government and

there is no one there.

It's fascinating to me and people start
streaming in like where's where's my

office Where's my computer and so what
what I'm the reason I say that is that

these founding fathers had this kind of
confidence amenity and in the ability

of human beings to solve problems together
and know where to meet is that more

evident in that than on January twenty
first in a change of administrations.

So today from the founding of our country
to the squishy physics of chocolate it's

a short leap and so

understanding the world around us which
is is what physics does I think and

we're just taking a route to it that is
that everyone can relate to delicious

food and also sort of whimsical and
fun presentations these are.

Baseballs made out of chocolate
as white chocolate with a red

thread going around them and.

So this is the type of thing
that I make this is not mine but

it was kind of a cute.

Mickey Mouse version of what's
called a boost in a well or

chocolate log Christmas.

So the log is layers of chocolate
inside and then one of the techniques

we use to decorate this kind of thing is
we spray chocolate through a paint sprayer

which is what this is that's that
velvety surface you see on there.

We actually to do that.

Add more cocoa butter then use
in a standard bar of chocolate.

So bar of chocolate cocoa butter
can have between twenty and

thirty percent and it just depends on
the quality of the chocolate cocoa butter

is expensive because it is also used in
the pharmaceutical and cosmetic industry.

So usually the more cocoa butter.

The more expensive your chocolate is but.

That's all a ratio and no chocolate
company will tell you what that ratio is

that's their proprietary secret and
so it actually just

to get this is one of my favorite things
to talk about to complain about really.

So a few years ago you start to see
percentages on chocolates which is

as useful.

What that means eighty five percent cow or

cocoa all that's telling you
is it's fifteen percent sugar.

Which is useful.

It's useful to know but
it's become you see how big it is and

it's bigger than lint.

I mean they're like you know this is
eighty five when really means nothing

because although it's telling you
that there's fifteen percent sugar.

It doesn't tell you about those other
elements that Arjun told us about namely

the chocolate nibs they're sometimes
called it sometimes called Chocolate

liquor because no alcohol in it but
they still call it that or cocoa paste so

and the cocoa paste and the cocoa butter
with the sugar is what makes the.

The quality of the chocolate and

primarily it's the quality of that cocoa
paste because as you saw and maybe

I think I have some some other versions
of this we're going to come back to that.

That it's the quality of what's in those
beans that Arjun showed us those beans

are how they're grown and what the the
origin of their sort of plant genetics

are the best quality one bean is called
Creole You know it's a very difficult

being to grow it's highly susceptible to
pests and almost nobody grows it anymore.

There's a few of them around one of
them is a plantation in Hawaii that

grows excellent chocolate cow being and
chuff and burger used to

have a product called porcelain and that
was mostly Creole You know it's excellent.

So the cheaper kind of chocolates called
for stero forest arrow is what is grown

throughout most of the world doesn't have
the flavor profile of Creole you know but

there is a third kind of culture an Atari
zero and it's a hybrid of Creole you know

enforced arrow and that chocolate is the
type of chocolate that these premium bars

are made from They're extremely fruity
they have a very very wide flavor profile.

There's you can taste raspberry
even citrus all kinds of smoky

coffee flavors and what you saw there
with those little purple beans that

are fermented is a really is just
a microcosm of so much flavor.

So by manipulating the two parts of
the chocolate the physics of it.

That gives it the structure and
the flavor.

That's what pastry chefs do.

We're interested in both primarily really
when it comes to you know the customer

guest.

We're interested in the flavor but
you can do some wonderful things with it.

This is kind of a little
bit of a distorted image of

a the winning sculpture
chocolate sculpture.

That's what's called the plate which
takes place in Leone every two years and.

People like me get all excited about this
we call it the calling area lympics And so

the teams form and they train for
a year just like in the Olympics and.

This happens to be the French teen
which made this very sort of.

The serious sort of sculpture.

Made out of chocolate and all things out
a bill basically it's a type of thing that

we get all excited about anyway.

This was the winner it's chocolate.

Why is it so shiny well ask the people
that made it and it's not because it's so

perfectly tempered.

Which as Arjun explain why that that
happens because of those those crystals

how they how they line up as you saw in
his slide they line up all together and

they reflect light more efficiently.

This when they took salad oil and
spread it all over and they won.

OK so I'm going to go.

I'm going to go ahead here and
talk a little bit more about chocolate and

we'll go back to some
of those other things.

So another sculpture this one is mine.

Every year we make what's called
a gingerbread house at the White House for

Christmas and the kids come through and
there's a very wonderful display of

here in this case both on the left hand
side there and we even inside each room we

make we remake the furniture of the White
House other chocolate in Mars' a pan and.

So this is a way to use chocolate
that's entertaining and.

Which communicates sort of this incredible
building and as we said these incredible

people that that put it together and
the philosophy behind it.

Side view of that.

And now on to the the beans.

Arjun talk recently about it.

I'd like to bring it up again because
you see how this very like unhygenic

sort of way the beans are fermented and
then in most cases that is how it's done.

And that that results in a lot of the
quality of the chocolate comes from not

only the quality of the bean
that we talked about.

But also how it's handled so

in many cases chocolate is just
a crop that's grown by a family and

if you go to one of the chocolate
producing producing countries.

You'll drive along the road and
you will see you have to stop because

the family has the beans spread
out on the asphalt drying.

And so you have to stop the car and
they come out and they sweep them off and

then you drive through and
then they put them back out.

So actually that's the second phase so

what you're seeing here is
the fermentation that white covering

is the fruit.

It's a residual fruit the taste
delicious by the way but

it's really hard to to get off because or
to really for

a take advantage of it because it is
it's a little it just covers the bean.

So here's an example of the being a little
bit more described intensively so

they're gradation as advocation and
Browning is what happens during that from

an Taishan problem process not
a problem unless you do it wrong.

So the bean is as you saw a lump together
with it's with its fruit white fruit sort

of exterior there's a lot of sugar in that
and that helps the from in Taishan too

to take place as you see here
the sugar turns into ethanol and

as it begins to degrade the rest
these other acidic acids and

and other elements are created and not
until then doesn't taste like chocolate.

If you eat one of those beans.

It's just a bitter very bitter and
flavor of this bean.

But when you but

a time you get to the Browning where
these where it has really fermented

if you taste that bean especially if it's
dried it just tastes like chocolate.

And that's how people who judge and
buy chocolate and

process it make their decision
because they'll taste those beans and

sometimes they're not very bitter they're
they're not sweet either there's very

there's not much sugar left in it but
that's where you taste those incredible

floral notes the citrus and
raspberry and all kinds of

different aspects that a really high
quality chocolate should have and so

when you're tasting chocolate that's one
of the things besides the appearance.

You know if we look at chocolate it
should be shining as we know for

margin why because those
crystals are formed.

And it should snap as we as
we've heard also because it's.

Because there are they're very stable and
they're very tightly packed together.

So even if we heard that.

Nothing but shiny and it's perfectly
stable because it's temperature.

So just like the bar that you bought and
allowed to melt in your pocket and

put back in your in your refrigerator.

So I think I'll start out with with
this process but since we're so

deeply into it now.

So now we have this amazing.

Mixture of this combination
of of chocolate liqueur or

cocoa or cocoa paste and cocoa butter.

And we throw it together and

there's a whole process of bringing
that those particles to smaller and

smaller size the ideal size is twenty
microns or less and that's where

the chocolate manufacturer does let's see
what we have there's a picture of a really

good quality cow cut in half and
you can see it's purple.

So the really good quality
could Kahlo you'll notice even

in the chocolate that it has a kind
of a purplish Hugh to it and.

Can be a sign a good sign of
good quality the old fashioned

way the way the Mayans prepared
chocolate was on this kind of table.

So they would take a stone roller and

roll it on this roll and
on that stone still used today you go to

a cow producing country where it's still
Jews like Mexico or or Venezuela or

anywhere that the Mayan culture and
Aztec culture went and

you will still see this being done
in villages and it's fascinating.

It's really delicious.

They're taking their own cocoa.

It's also quite gritty because they don't
have the same kind of grinding system

that we do the milling.

But they'll add cinnamon and spices and
sugar to this and they will sell it in

a little markets as a kind of a little
truffle a kind of it's kind of a grainy

truffle but with wonderful chocolate
flavor very intense and very floral.

A more commercial way of doing it is
with these grinders So not only are they

grinding it down to twenty microns or
less but they're also mixing and

developing those flavors that happened
during that acidification process of from

an Taishan So those flavors are developed
in this which is a ground grinding and

also called conch in process so a really
good if you're making chocolate in a hurry

and you want to get on the marketing
get your money you might cons for

six hours to twelve hours a really good
chocolate can be const for up to seventy

two hours that fully developed those
flavors it mixes them together and

also makes the granules
a little bit smaller.

We saw this earlier this graph
of how to melt the chocolate so

that's what I'm going to show you the
moment you heat it up never higher than

one hundred fifteen degrees Fahrenheit for
dark and for white chocolate.

It should be even less and milk chocolate
even less about one hundred ten maximum.

And then we bring it down to depending on.

Chocolate itself and it will often
have a description of how to temper.

So this one doesn't but
that's OK now you know it anyway.

So you'll sometimes see this graph on
the side of the of chocolate bars which

tell you exactly how it was manufactured
and what you should be aiming for.

But in general you can go to up to one
fifteen back down to eighty two or

eighty three Fahrenheit and
then back up to up to eighty eight

eighty eight is where is that C.
sweet spot.

That's where those beta five
crystal start forming the fifth

fifth dimension in there that we talked
about that's the really the best spot so

that's where the sugar cocoa powder and
cocoa butter begin to form those that

relationship that gives a nice nap and
the best structure.

So there was a question earlier about
does it go through all those phases as

you melted Yes it does so here.

There is sort of this description they
call it the formless stage type one

the melting point and
type two up to five which is the purple

ideal one a little diagram of how it might
look as it starts to come together as

as Arjun explained the motion happens and
if you do it right.

It comes out like that.

So this is a chocolate sphere
that is one of our really fun

desserts where we would make a very thin
chocolate shell in a hemisphere globe and

then we put a chocolate cake and
ice cream and whipped cream and

cherries inside it and when it's served
the waiter comes and pours a hot chocolate

sauce on it and the whole thing like
kind of opens and reveals the inside.

Great fun.

The world's first kinetic dessert.

I call it.
This is if this is a an opera cake.

It's a it's a classic French dessert.

That is still.

Used today still very popular.

It's layers of culture cond and
then usually a very thin layer

of coffee butter cream or some pistachio
some of the butter cream a layer of.

And then this one too.

As has that sprayed
chocolate surface on it.

Along with some attend
your angel lay there.

There is a very shiny piece of
chocolate correctly tempered so

that you see those those
number five crystals.

Well lined up which reflect
light the best since

there since they're all lining the same
direction and that's why it's shining.

OK so now on to the demo.

So this has I melted this earlier.

It came from this and let me get close
to the camera there because I think

you're able to see that the cocoa butter
is already starting to since it wasn't.

Here we go since it was is already
starting to come to the top there's like

little dots like you know like the salad
oil that are don't explain with water.

So it's already starting to come to
the top it has not been tempered it's

it's really disintegrated
into that those two phases.

I mean into those two
elements of cocoa nibs and

cocoa nibs and cocoa butter and the sugar.

So let's take it back up.

If you do if you do melt chocolate in a
microwave you have to be really attentive.

It's it can burn very easily if
you go over that one fifteen.

It burns and it forms these little
granular grains of sand in there

that you never get out now that you cannot
retrieve putting in refrigerators OK or

melting it in your pocket
is probably slow melt which

by the way who decided that chocolates
had melted body temperature that strange.

Like it's a plant.

You know it has nothing to do with us.

And yet.

Maybe that's why.

It was kept around for so long.

So you had those Mayans and Aztecs usually
the chocolate and there's beautiful

drawings and Mayan art where you see
the chocolate being used in ceremonies and

you'll have it was usually prepared by
the women on those grinding tables.

But of course then in the ceremonies the
religious ceremonies the priests were men

and they just decided that it would
be good to mix it with human blood.

So you know they took that.

And spices.

Apparently it goes well with both but
they were they were drinking it.

They were they did not have this
kind of chocolate in the New World.

The first reference to chocolate in a new
world is by Columbus himself he writes

back that there was he came across
the canoe where the Indians

were had filled with these
these beans that were so

valuable that they treated
it as if it were an eye.

And this was these were
cocoa beans cocoa beans and

it was a currency at the time so
it was valuable to them.

But in any case a huge part of mine and
that's the culture was based around

chocolate and then came to Spain through
people like Christopher Columbus and

they they kept it basically secret for
about one hundred years.

So the Spanish court was drinking it.

They were drinking it in the in
the New World post Columbia world and

nobody knew about it.

It wasn't till the it was Inquisition.

When Jews were driven out of Spain
that it went into France and

went in to be a Ritz and
by you know in that area down there and

that's where chocolate began to
be known to Europe in general.

And it had a huge a huge
popularity of course the.

The English and the French adapted.

There were chocolate houses and
tea houses and

course coffee was coming around then
too so there was coffee houses.

Voltaire himself said that he never
ate anything before three P.M.

except chocolate.

So it was that and he lived to
be pretty old pretty smart guy.

OK So this is a GREAT to monitor for
chocolate it's unfortunate very

fragile but it's one I highly recommend
because each degree is very clearly marked

on here you can get these things
online but if you're interested in

bringing your chocolate back to
life that melted in your pocket.

So bring it up to that temperature
that we talked about where all

of the crystals are melted so above about

one twelve one fifteen and part of this
process now is cooling it but it's also

going to be what we do when we want
the crystals to start to form and

I am going to do what mention which is
called seeding and I highly recommend it.

So.

We want to.

To really melt as soon as it hits.

The one chocolate.

So we're going to make
it very small pieces.

Because as it cools course it
doesn't melt right away after that.

So we're as as was mentioned
the slower the better.

But we don't have that much time so we're
going to speed this up by seeding it.

And this what I'm doing is a very

you know this is something every
pastry school teaches you.

The old fashioned tempering method.

So if you're making bon bons or truffles.

This is one of the steps
that you would do.

Ok you.

Even though it's not cold it's
colder than it was in there.

The room is probably about sixty or
seventy I would guess.

So OK at that point we're going
to bring in some of these

the untampered by the way the best way to
temper is not untempered to begin with.

So in other words you would take.

You would take just your chocolate and
put it exactly eighty eight degrees and

leave it for several hours and then it
will never leave the tempering stage and

you'll come back and be melted and
you won't have to go through all of this.

That's what a lot of pastry chefs do
they just find an area above the oven.

Keep a huge bowl of chocolate so
it doesn't temperature does not change

as quickly and
then it's kind of always ready to use.

So what we're doing is moving it around.

We're allowing those crystals
to fold over one another.

We want them to take the benefit
of that seed that we put in there.

The chocolate that was already
tempered and which has the crystals

that number five crystal that we love so
get it.

In place.

The reason

we we chop it up is that you can see
there's still a few little pieces left

we're going to kind of squish
those out the word of the day.

OK As you can see because
it's becoming more and

more viscous it's not flowing
as much as it was earlier.

So those crystals are forming.

At this point.

It's going to keep going and usually
it sets up a little bit too much so.

Because we want to be sure we got
it to the to the right stage.

So we're going to put it
back in the microwave for

just a second to bring it up.

It's one or two degrees.

This is a very small amount of
chocolate so if I was doing like.

You know about four times.

This would be a pound.

I would give it about three seconds
in the microwave at this stage.

OK so.

You are out of the way.

I'll take a moment to

thank Alberto and and
the whole school here for having me.

It's so much fun to be here and
we had such a fantastic

conversation yesterday
learning about where food and

physics intersects and so as I say
I always learn a lot and thank you.

Also to the graduate students and

Perry who helped me put this
whole show bang together.

OK so getting very thick.

And I'm going to just give it a second or
two to heat it up.

OK.

So up to now it's

what it was doing when it was in
your pocket and melted and then you.

You put it back in the freezer
without doing all this so

it became like Lumpy and
coarse and granular and.

And eventually the bloom
would have come out Bloom is

called is the cocoa butter
that rises to the surface.

Since it's not I'm also fied.

But here you can see that since
we went through all this.

It's already starting to A to
set here very very quickly.

So that's.

Sign too that you are.

That's a sign that you have to get rid
of this extra here I want to show you

that you've tempered it correctly
because correctly tempered chocolate

will set up almost immediately.

So who what am I looking for here.

That.

Well you can see where it's
almost what I would call it dry.

You see how it has dried along
here as opposed to shiny.

So it's a different kind of shiny
when it's wet it's real shiny or

if you put salad oil in
a competition on your street.

But the kind of shine that we want is is
this one where it's shiny but it's and

it's set almost immediately.

And so what we'll do know is what makes
them so thicker versions of this.

And.

It's a little warm in here so
it's going to take.

I think longer than it normally would.

But we'll just let it sit here and
we'll come back to it.

This by the way is a.

Is kind of a very classic.

Decoration for
a cake you just take a spatula.

And you make like dozens of
these sort of little petals and

then when they set you pop
them off the plastic and

put them on top of your cake it's
a it's a cake that was developed by

public crews called the president's
cake and it's really kind of cool.

You always wonder like
how to finish a cake but

if you put butter cream are going to
shine and it doesn't have much flair.

But if you do something like
this then you can put it in and

have a sort of rose petal look so
while that's setting and

I'd like to find maybe a place that's
a little cooler I think I'll set it here.

I think we'll get there.

More air currents here.

So.

So I'm kind of starting backwards because
what I wanted to do was was to make

a play to dessert for you that we have
over here and do it one by one and

referring to the science that we
learned earlier about chocolate.

So the one thing I want
to start out with is

what I call the forty
five second sponge cake.

So it's a very interesting and unique
cake was developed by Fran Adria and

it's something that if you
have guests coming over.

I'm at the front door.

You could have this
dessert by the time you

by the time they get to into the house.

So it's a.

And that reminds me I think these recipes
be nice if we have them of vailable two

on the website or something.

So this recipe is is a mixture
of four egg whites three yolks.

Fifty grams of sugar cocoa powder and
a little bit of tahini paste.

So the original was with black sesame
paste but I like this to paste

just something that gives a little sesame
flavor a little more dimension to it so

and so what you do is you mix that
together and you pass it through a sieve

because you want to bring it put it
into this what we call an easy form or

or whip cream from or there's two kinds of
gas that you can put in here one is the.

Is this one the soda
Charger's which is for

a club soda don't use that because
it has that kind of salty flavor.

And then.

But what you can do is these whipped
cream Chargers which is what's in here.

So.

That makes sure that I just described you
pass through the sieves so it's nice and.

So it's nice and uniform no lumps
you charge it with I think I'll

put one more charge in because it's
been sitting here for a while so.

Let's and also so you can.

See what we do.

So in here is rock a better.

FACE.

These are paper cups a little
hole cut in the bottom because so

the steam can escape and
brushed with a little butter

off I'll try not to spray
the first row over there hopes.

No promises.

OK So there you have instant cake batter.

So what you normally would would take
you twenty minutes or so on the mixer.

Normally would take twenty minutes or
so on the mixer you know waiting for

that foam to happen which happens
very easily especially if there's

if it's egg whites and you put a little
cream of tartar in there than that acid

helps the albumin to break down and you
get a Marang if you're using whole eggs.

Then the less than of the yolks also
makes that happen more quickly.

Because you're you know it's creates
that surfactant that we talked about

earlier which enables that
phone to stay and be created.

But this is kind of fun too.

So don't fill it up very
much because there's so

much air in there now that you're
going through it's going to overflow.

If you put more than a third
of a of that cup in there.

So let it go for about this this
microwave is really strong.

I do it in mine.

I do forty seconds on high but
this one only took about.

Only took about thirty.

So yeah it's starting so it cooks it.

In a very uniform way I suppose if you
wanted to make a whole layer cake.

You'd have to find something
that wasn't metallic and

put that in there and hit the on button.

Going to another then another
second is anybody counting good.

Whoops I understand it's not good
to let those things run you're

adding to the microwave of the universe or
something.

So.

So you're you're thirty
five seconds sponge cake.

OK.

T..

It's I think it just needs a touch
more of this feels a little bit.

OK.

OK.

So as we make our plate then

yeah this is this is still very soft
what I would do if I were you know

really making this is I would
let it cool down a little bit.

But here this is interesting you
know we're talking about phones and

how they form.

So you have some very big
holes there that are.

Formed by the egg and the protein in.

And carbohydrates in the flour and
they immediately seized around that.

So OK this goes over here.

They immediately seize around.

Those bubbles and form the bubble there.

So the next thing I'd like to
do is not actually chocolate but

I always like to have some fruit
flavors with chocolate something to

to give a little bit of contrast and

so what I made here is it's
also a kind of a fall.

It's made with modified so I protein.

It's all it is is strawberry puree So
first strawberries push

through a put in the blender and then
push through and push through a sieve.

What am I missing here.

One element of.

Thank you.

Thank you.
Show.

OK So

we are with it just goes right on
there obviously not technically.

OK so modified soy protein and

strawberry puree right in here.

So it's if you have a blender at home.

You could do with the blender.

These these devices we call immersion
blunders have is great because it has all

the different tach moments like
you can do a whisk which we're

going to do in a minute or you can do this
which is kind of like a food processor.

Or you can do the actual
immersion blender with this blade

which is useful also especially with this
type of cooking if you want to call it

modern Modernist Cuisine a lot
of these hydro coal oil.

Do not blend well with liquid so
you have to shear them into the liquid.

And that blender is what we use.

Reverse.

OK so.

This I'm going to leave over here.

So it was just a strawberry puree and

now it's a very bubbly sort
of liquid the next step and

this recipe is you know you
place it on parchment or

something that we like to use in pastry
is called So Pat It's a silicone sheet.

You can get them at Williams Sonoma or.

I get five cents for each one.

First I just know it's.

So you spread that out on a sheet
with a spatula and you come up with.

What I call Strawberry bread.

So it dries out but
because it has that protein in it.

That's why protein the bubble stay.

It doesn't just collapse and then you
would wind up with like a fruit leather

which is fine to kind of interesting but

this makes these little sort of

your shape decorations and

it stays snappy so.

Still crunchy.

And gives a nice texture because so

far we have an elastic texture
over here elastic to sort of.

We're going to get to this other going
to last year which is very interesting.

So it's nice to have a crunchy
sort of touch to it.

So now they're running you see
former I'll show you another way to

make a really interesting most chocolate
most of that is a fairly classic recipe.

It is half milk half clean
a little bit of sugar and

and convert your what we call culture or
just plain chocolate.

So there were making a chocolate
mousse But why stop there.

Everybody knows what chocolate mousse
is we're going to freeze the outside of

the chocolate mousse and leave the inside.

Liquid which is gives a very interesting
kind of crack and crunch when you.

When you bite into it.

So that's one of the things
that a chefs were looking for

is a unique experience a texture
that people have not seen before.

And which is just intriguing.

Sometimes things taste better too.

Depending on their their texture.

So if it's if it's called on the outside
and then all of a sudden you bite

into it and you have this awesome
like room temperature chocolate.

The surprise sort of wakes up your
palate and you taste it more thoroughly.

OK so.

Just you know you're liquid nitrogen
the same one you have a home.

So we have we found these

cool little these hemispheres here
you have to put that in first.

So it gets real cold and otherwise
the chocolate of course is going to

stick to it but
since it's super frozen here.

Once we want to put the chocolate in
that crystallization is going to happen.

Hardening.

Crystallization is going to happen and
it will not stick.

OK So let's take this again I'll try and
do this without spraying the front row.

I don't know how you can see it.

OK.

Oops.

Well this didn't come
out quite as a sphere.

It's more like one of
those something they see.

In their telescopes
whereas Pablo you know so

this is like a sort of asteroid or Anyway

just takes a few seconds and all we've
got are I forgot my strawberry bread.

OK a little strawberry bread over here.

And now.

So the idea is when you're when
you're serving something like this in

a restaurant.

These are the type of things which
you put on at the very last minute.

It's what makes it a plated dessert in

a restaurant the most exciting
way to have dessert in my mind.

So it will go right out and

the guest will bite into it while
it's still crunchy on the outside.

So it'll stay maybe forty five
seconds like that it's so

extremely cold so liquid nitrogen

boils at something like minus one
ninety nine cent a grade seventy seven.

Kelvin very cold

which is kind of interesting because one
and one of these demos that I was doing.

Summer is mentioning how
how unique water rears and

how what an incredible substance it is
it takes so much energy to boil water to

separate those bonds that Arjun told us
about the hydrogen next to the oxygen.

So you have to heat that to
two hundred twelve Fahrenheit.

In order for it to boil.

That's so much energy.

Whereas liquid nitrogen it's
going to boil at minus three.

Twenty one.

So when you think of what I mean what is
the temperature in the universe of empty

space water is an extremely
stable substance.

So let me try another one here.

Off.

OK

And what I want to try and where so
how about on about understeer

want to help I need an assistant
can you come help me up here.

Come on and you're good to each Ochlik.

OK All right.

Volunteer Here she comes.

All right let's have a man.

What's your name three hundred on
young very nice to meet you I'm Bill.

Come on over here.

OK so
what we're going to do is we're going to

make this little chocolate mousse and
what I'd like you to do.

So this is very cold.

Don't touch this all I'm going to have you
do is you're going to shake this put your

finger on there maybe a better stick for
you are the worst the front row is

very nervous when we are doing this
they know they're going to get.

OK so what I want you to do now I'm
going to hold this with my tongs and

you just pull this lever but
very very slowly.

Otherwise I'm going to
get it all over my face.

OK you're up for that.

All right so you hold it like this and
I'm going to hold this and

then this is the liver just
pushes slowly as you can.

That's right.

Perfect.

Wow you are great chef gratis.

OK let's put it in here.

Awesome.

Thank you very much.

Yes Great only Yeah well wait
a second you get to taste it.

Since you help me.

OK nice little crunch on.

It's a little bit.

OK to me which I think you

are seeking heard yes that means.

Thank you.

OK.

Pardon my mouthful.

OK the next element.

I like to talk about.

One of the reasons that chefs want
to learn about science want to learn

how things grow where they grow how
they distributed everything you can.

And even on their molecular
level is we want great flavor.

But we'd like to be healthier if we can.

So I've been very proud to be part
of Mrs Obama's Let's Move program.

Let's Move initiative where we talk
to kids about healthy eating about

about what we eat where it comes from and

how if we don't need good things
our lifespan is shortened.

So we can look at desserts
which is something

that is probably no one
thinks of dessert and

healthy in the same sense except me but
I don't know that there's anything.

There's probably no such
thing as a healthy deserve.

But there is a healthy lifestyle that
can include dessert in moderation.

So that's my message and

one of the things that I like to
do is I like to play around with.

Recipes.

Using science to eliminate
some of the fat sugar and

cream and cholesterol that we are so
familiar with in our desserts.

And a really great recipe.

And this is this is by the way has
been around for a long time and

it was developed by
every one of the sort of

founding fathers of molecular gastronomy
and he's been working on this stuff since

with Nicholas Kirti since about one
thousand nine hundred eighty eight.

So we're like into almost fifty years
of molecular gastronomy which is crazy.

So this is a chocolate cannot.

Without milk or cream.

So Arjun explained to us that
chocolate itself is an emotion.

It's this fat cocoa butter and
then the cocoa nibs and sugar.

So we can consider that
a kind of a water and

of course the fat is hydrophobic it
doesn't want to mix with water but

the sugar and the cocoa nibs
are complex leet hydrophilic So

chocolate so this is an emulsion but we.

And that gives us a pleasant flavor
when it starts to come together so

oftentimes we're making the recipe such as

we want to maintain that emotion even
though we're adding other ingredients.

So the standard is just heavy cream and

chocolate covered your chalked up you pour
the heavy cream over the chocolate and

you whisk it right from the beginning and
knows it's the caffeine

which is in milk and cream dairy
products which becomes a surf active.

And that emulsion then takes place and
you have a very smooth very

anxious wonderful thing but
can we do it without cream.

When I was first you know asking no
chefs why why do we do it that way and

they said you know just do it they
would say Well and by the way.

Never let water get near your chocolate.

OK.

Why's that.

Just don't.

So the water because you have that
emulsion of fat and cocoa nubes is.

It's fairly fragile and if you add water
to it and the molecules don't like it and

they will start to start to that

what you want to call it that emotion
breaks down don't reward your chocolate.

Well it turns out depends on how you
put the water and how much you put.

So I have a recipe which I can
give you if you have a pen.

It's two hundred grams of water and
I think we have time to do this.

OK So

two hundred grams of water one hundred
fifty grams of chocolate covered her.

So that's you know just a bar chocolate
but use a good chocolate like this one.

You can use baking chocolate or or
and you could use milk chocolate

white chocolate probably
not work that well but and

just a little quarter teaspoon of gelatin
powder gelatin that has been bloomed so

you bloom means it's been it's sat
in some water for a few minutes.

So here's the water.

And I think I've I've been eating
the chocolate all morning.

So I probably don't have
enough left to let's see.

Maybe we can maybe we can still
perform this bear with me.

So what we're going to do

while I'm measuring it I'll
explain to you you boil the water.

Add the gelatin to the water poured
over the broken up chocolate or

in this case it's going to be
the some I melted chocolate away.

Hole in the bottom but try this.

I'd like to show you

this in real time because it's and I have
I have one that's already prepared but.

This is more fun to watch.

At least you'll see how to do it.

I really don't have any gelatin not too
but OK I'm going to make a half recipe.

So we boil our water.

Have our chocolate which can be
tempered around temper it doesn't

matter because we're going to reintroduce
the emulsion with our whisk there.

While that's happening I'm going
to show you to the end result

sort of Julia Child style known for
the more so.

So this is the good notch
that results from this

which is amazing because this is water and
chocolate.

We're told that water in chocolate
doesn't become anything nice but

look how smooth and anxious this is.

It's a it's a beautiful.

And it's water and chocolate.

So we're going to get to that in a moment
I'm going to show you how to make it.

All right.

See how our water is doing.

I love this microwave gun super
charge that you physics guys.

We don't want to know.

Don't tell us so.

Ok water the chocolate and then.

Our old friend again.

What would a pastry demo
be without liquid nitrogen.

OK We have hot water and
we have to talk about it.

Now the air bubbles.

Are going to form.

Because we're risking it with this.

We're going to need
the bubbles are going to be

captured by the Christianization
of the chocolate.

So instead of crystallizing like it did
here in just a two dimensional shape.

It's going to crystallize
around the bubble.

That's why you wind up
with this instead of that.

I need

another volunteer work with my assistance.

Can you help me again.

OK Come on come on come on.

There we go.

Thank you.

All right.

Yeah a little hot Little Rock.

Come on.

I mean here you go.

So you have to push this button down.

OK let's see what.

OK There you go.

You got it.
Keep holding it there.

I'm going to put something over it so

it doesn't keep going to
take a while though right.

You threw them in the pool.

And.

Your mom is going to be really mad
if I send you back over there.

With.

OK That's a look at it later
the now let's see that.

OK.

Just hold on hold that like
that are not too close.

Just don't put your head in there.

I don't want to because there you go.

Right here and then push.

Perfect.

Break.

Thank you keep going keep going.

OK well what are you.

So just a little technique about how the
way we think in pastry shops restaurants

is we just love canals can
also these football shape.

Sort of things.

And so.

And I wanted to do this so I can give you.

So I can show you how
smooth this water going is.

Having fun.

For me too.

OK.

So you can see how this.

With a one spoon.

And here you can just get this
really awesome very smooth can now.

OK let's see you.

OK.

Once you taste it put you put
your finger in there and taste.

If you like a good OK endorsement but
I understand you sir thank you.

You can go.

Thanks buddy.

Appreciate your help.

All right good job.

Can you have one of course you can.

It's been right there you go.

Yeah what's a little dip the finger
that's not going to talk on work.

He needs an agent.

OK where were we.

OK.
How how that works.

I mean we're taking a little longer but
it's already starting to set up and

eventually it's going to look like this.

That's our Water for Chocolate.

So what do we know we're
just missing our flowers.

You know that's.

I had nothing to do with those.

But we this is from Chef Gardens one
of the really fantastic organic growers

in the States here on Ohio growing
absolutely delicious registerable Zen etc

and then we just need a little
bit of of chocolate sauce

which we've momentarily.

I know I know we need we
need our decoration too.

So they have our canal is really cool.

It's set.

So the chocolate has set and it's one of
the telltale signs of a well tempered

chocolate is that there's no white
markings on it because the cocoa butter

would have risen to the surface by now so

we have a we've we've saved
your chocolate bar from.

From destruction.

And so they come off as one piece.

These I love this acrylic this acrylic is
perfect for chocolate by the way this is

just a little too stiff for me because I'm
not strong enough to get it off there.

Can I break it.

OK.

Yeah a little thinner would be better but
That's right.

I got to show you the shiny part.

So of course it's the the under part the
part that's against the acrylic which is

is the shiny assist.

Take my word for.

OK.

So.

There you go OK.

So squishy physics.

THANK YOU THANK YOU THANK YOU

THANK YOU.