We're lucky to be joined today

by Dr. Stephen Morris.

He is the J. Tuzo Wilson Professor

of Geophysics at the University of Toronto

He has a BSC and MSC from

the University of British Columbia

as Ph.D. from Toronto

Where he's been, I think for a while,

10 years? 15 years? I think

Forever

Yes. He's been there for almost forever

and has won two teaching awards

Toronto, also as an visiting fellow

at Cambridge University and is a fellow

of the American Physical Society

At Toronto he directs the

Experimental Non-Linear Physics Group

which, according to its website,

not only does he direct. He is also

the chief fundraiser and receptionist

for that group.

So, he wears many hats.

Thank you for joining us and

taking the time to watch us today.

Hello

I want maybe to start off

if you could talk a little bit about

what drew you to non-linear dynamics or

or chaos in the first place? How did you

get involved in whatever it is you're

involved in?

Well I started out a long time ago

working on liquid crystals,

which are a kind of soft matter topic

a material science soft matter topic

And what's interesting in liquid crystals

are phase transitions, so you

change the temperature and liquid crystal

goes into a different phase

Liquid crystals are very visual. You can

look at them under a microscope or with

your eye and see their phase transitions

nicely, And it's kind of a short step from

there to pattern formation, which is

the normal dynamic systems

where if you drive them with some kind of

force, you increase that force

beyond some threshold and a new pattern

emerges that's what's like a phase

transition. So in fact the

theory of phase transitions and the

theory of bifurcations and non-linear

systems are really close cousins

to each other. And the experiments are

fairly similar to each other

though one of them is an equilibrium

system--thermodynamic system

and the other one is a non-equilibrium

system. But it turns out that is not

so important. Basically when the

experiment is quite similar you can

look at transitions between systems and

patterns just by changing a parameter

and take pictures of it and write theories

It's really quite similar to condensed

matter physics.

Many people of my generation

came here from doing condensed matter

physics, especially soft matter physics

So that's how I got started on it.

I wonder...I mean, my background in grad

school, I was starting with high-energy

theory, which I enjoyed the math of

but it seem to me to be getting

farther and farther removed

from reality and one of the things

that drew to chaos and

non-linear dynamics was it was,

to some extent, the physics of

everyday.

Yes, yes

Sounds like that has been a theme in

your work, as well?

Absolutely. I really like the visual

aspect of it. I like being able to make

experiments out of simple parts

and it's very easy in this field to

just walk down the street and see

something and take in the labe

and make an experiment out of it.

The first one I ever done. It's almost

the exact opposite of LHC

LHC is bigger and bigger and more

and more expensive and takes more

and more people longer and longer

to do the experiment. And in this field

it's most exalted things are

simpler and simpler and cleverer

and cleverer and unique

And they all involve just one person.

Usually, one graduate student gets to

build the first and last experiment

and understand the phenomenon for

the first time.

Right.

And that's really attractive.

And to me, at least, I always felt

that even though they are sort of

everyday and simple phenomena,

the mathematics behind them was no more

or less beautiful than the mathematics

behind string theory--maybe more so

because it actually describes the

real world

Yes

More than string theory.

Yes, I think more so. And it's often very

difficult--one reason these things

weren't done before is--you know--

is the fact that they are difficult.

We still don't understand and lot of

what seems to be everyday phenomena

And the reason is they don't fit the

standard Hamiltonian equlibrium physics

we to teach people. We tell first year

physicists that friction is an annoying

"extra" force that we should ignore

or get rid of in our equations and so on

but it's truth is it is a powerful

organizer of phenomena and you

can't understand fluids without

viscosity and you can't understand

motion without friction

And so, year, it's crucial and

many times these things were looked at

with the tools of 19th Century physics

ages ago, but those tools have been

enormously improved and we have all

kinds of new ideas, a lot of them brought

from condensed matter physics.

And so, on the other side experimentally

you have vast tools we didn't have before,

even digital cameras. The idea now

that you can follow thousand of icicles

or whatever you are studying, and just

images which you couldn't have

afforded to to take that many images

So it opens up--it's like big data

We suddenly have big data on everyday

phenomena we didn't have before.

That means the laboratory experiments can

be very sophisticated because all I'm

using is a commercial SLR camera and

computer, but those things are very

powerful now compared to where they

were 20 years ago.

Sure, yeah. Is there an experiment in

pattern formation one of these one grad

student, one tabletop sort of thing where

maybe you could describe to us a little?

I'm thinking about icicles, because I'm

looking out my window..icicles or

something else?

I have an icicle experiment, this is

one that I'm working on right now

And it's exactly what your think it is

it's a table top thing, it's a big

fridge thing we built on a table top

It produces a small region of minus 10

or minus 20 degrees celsius

You dribble water in the top with a

periscopic pump so we know the rate

of water flow,

You stir the air inside and hopefully

control all the conditions inside for an

icicle. And there is a slot in the side

of the box, you point the camera in there

and you follow the growth of the icicle

over many hours and you can use the

digital image to trace the edge of the

icicle as a function of time, so

you know exactly the way the water runs

out and the humidity and measure the

flow of air in the box. So we can

produce icicles under completely

controlled conditions.

This is almost never done before

a few experiments where people made

icicles and they basically measure their

length and width and they did, you know,

did sort of a gross--how much ice is there

calculation, but the question of what

shape is an icicle is a quite subtle one

This is an example of a moving battery

problem : you have an interface between

ice and air and water and air

and you need to write down differential

equations or models that for the

motions of the interface . So the

outcome of the theory would become

how time distributed the shape of the

growth and length and shape of the

icicle, or any amount of growing for

example. This is incredibly difficult,

no one has ever done it before--

it's much more difficult than you would

think. And there are surprises, so

for example, icicles have ripples on them

Any icicle you might see if you look

out your window have a kind of bumpy

texture. It turns out that those

ripples are weirdly universal.

They're almost exactly one centimeter

in wavelength, everywhere in the world,

always the same. Independent of the

temperature and water flow rate

and everything--no one understands

why those ripple are there

There are also ripples on stalactites,

which are a kind of "rock" icicle

hanging from the top of the cave

and they grow in a similar but not

exactly analogous way. Water runs

over the shape, so the flow of the water

determines the shape and the shape

determines the water flow and for some

reason we still don't understand the

results of the formation of stalactites

So we're also looking for the universal

among patterns. For example, a

rippling pattern that you see is often

driven by quite different underlying

physics, but basically all ripples have

the same symmetry , all have the same

defects, ripples generically move ----

so for example, ripples on icicles

move upwards slowly. This wasn't really

well known. But the experiment is quite

simple, it sits on a desk top and is the

size of a --, and we built it.

Nice. So one of the things-when I think

a little bit about what's different

about chaos or dynamical systems

maybe than other areas of physics

is a little bit--I don't know--maybe a

little about what you are describing

and so if you were trying to come up

with a model for icicle formation

and stalactites, one approach is

to start very detailed through all

basic physics, but is another is maybe

start at a slightly higher level and say,

well, just like you were saying, there

is something common about ripples

so let's see what we can learn about

ripples independent of whether

they are ripples in water or stone

And that, to me, feels it's something

that has a different flavor about

non-linear physics as sort of work you

do and so on. Does that sound right to you?

That's right. Many times one can

qualitatively reproduce universal

behavior using what are called model

equations which are often simply guessed

from symmetry, they are kind of like

the standard model of particle physics

where (inaudible) is guessed by

the symmetry first. And you can

do those kinds of models

and patterns if you know the symmetry

you can write down the basic equation.

And often, that's enough, you don't really

need to give a detailed model of the

underlying physics the model equations

often contain all the dynamics the

patterns have in them from many different

systems, without any more work in a sense,

so that tells you that the features of

that pattern are generic so they're not

related to the underlying physics

they emerged directly from the model

level equations .

This is somewhat analogous

to what people do in phase transitions

or in condensed matter problems

where "coarse-grained" approximations, so

rather than write down the starting

equation for all the atoms and so on,

you write down a simplified Hamiltonian

which contains just a few degrees of

freedom and you hope those are the

ones that are relevant The argument is

always is all the other ones are just

averaged over or disappear or

kind of model, but anyway

it's quite common in condensed matter

physics to make models of that kind

as well. (11:54)