Thanks very very good to speak here.

It's a pleasure to convey
to you some of the sense

you know if you know this research.

You know that I was mulling this it
was very a student was involved and

when it all prospered I was with
people on our team and the leader.

It was all for you.

I mean that's you know it's it's you know
I always say very nice to get that kind

of external recognition and I'll show you
some pictures from the nice part of being

stopped home but you know it really
was when we were sort of started out.

So make this measurement.

We really didn't know what we were going
to find we thought we were doing this

interesting test is scarier cosmology and
we thought we would confirm that

the universe the expansion of the universe
the slowing down just like everyone

expected and it was really the universe
turned out to be surprising that was our

good fortune and I was doubly fortunate
to just be involved in the scene so

I'll tell you a little bit about how
your opinion about inclusion and

how we've all learned more
accelerated universe since then.

So this image is I think Michelle and

you're right Alex even with
the Hubble Space Telescope and

in this part of this galaxy in two
thousand and eight at the beginning of two

thousand native you look at this galaxy
you have seen a bright supernova right at

that location and this image is actually
from two thousand and eleven I believe

when we were looking at that sort of every
bit hard to see how it became a way.

And so very very that supernova
a few years after it exploded and

I'll tell you how we use it really like
these two surveys you saw or a verse and

they actually were surveying the final
really in the sense of surveyor on earth

were surveying the universe by
measuring astronomical distances and

sure enough to measure the distances of
things that are far away in the universe

actually one of the hardest things you
can measure the positions of stars or

galaxies you can measure are.

Right.
They are measured how far away they are it

is a challenge but it is key for
this kind of measurement.

I'm so we've built in astronomy
this idea of this cosmological

distance ladder where we can measure
distances of days near by and

you can just back to the furthest
census figures farther away.

So for

example in the solar system we can just
shoot already a ways that objects in time.

How long it takes for the radio waves
are down soft save us in this example and

come back to earth and

knowing the speed of light we can see how
far away this is how that's a big constant

practical once you talk about nearby
stars which are light years away.

You have to wait years for that signals
come back and so we have other techniques

once we know the sizes of things in the
solar system we can use simple geometry to

figure out how far away the right
stars are so there's a chance.

Parallax that you can simulate that I use
to hold your finger in closing one eye or

the other the position of
some nearby objects has to

shift relative to the background.

Depending on where you're viewing it from
and so simple geometry will tell you

the distance from you to that
often as you go farther and

farther in the universe that we can't
measure angles precisely enough to measure

distances the objects more distant and
so we have used indirect techniques.

So we have to use for
example properties of stars or

a special kind of started this
case a set your variable star

measure the distances to nearby galaxies
by your environment sort of ten and

one hundred million light years away and
I want a special part of the sky because

this year is a hundred anniversary of
the discovery of the stuff you heard it

will not see your relationship that allows
us to use the stars to measure distances.

I'm never scared by one hundred eleven and

I can plot and beyond that is really what
this talk is going to be about if we use

other distance and here's a particular
sort of kind of stimulus or kind of

exploding star to measure distances
the objects are way up in the universe.

So the history of this field
is actually quite long.

And I simply I would hope will
be shown here poignantly for

a second variable in
the gravity galaxy very well

made a couple of measurements to
measure just is this a nearby galaxies.

So that's here and used up the speeds of
galaxies measured from their outward shift

and part of those you know those
are actually measured by others including

life or what Hubble it just was iron
This is actually this figure from

seeing the National Academy of Sciences
this axis says a lot city but for

the other guys out there you
might see the video denser and so

meters are not you know the velocity and
yet.

So does this craft was actually
published with the wrong units

one of my students said that I
would definitely points off and

apparently I WILL GET AWAY WITH
IT GETS I'll still stand up for

you know the view that here on the science
but what I actually all really discovered

was that there is this relationship
between the velocity of galaxies.

First of all or something unusual all the
galaxies seem to be moving away from us.

I recall for sure they were already
shifted and their distance and

this really linear relationship to the
velocity of Justice is full of holes and

it's really a reflection
of the universe expanding.

I don't know how well that
shows up to this bright room.

But this animation shows you what you
really should think about Herman's of

the expanding universe the distance
between galaxies in our universe is

growing with time and if you interpret
that if you look at galaxies that are far

away just because as the sort of fabric of
the universe trekkers the galaxies that

are farther away are going to be moving
away from us faster than the ones nearby

and so you get this linear relationship
between velocity and distance and

a constant of course Navi now we call
it a shot in our republic is the whole

hierarchy of the whole concept means
a faster rate of action than a lower

team in sight is the whole law as
a consequence of the expansion

of the universe and so we've known for.

For you know almost ninety years
now of the universe that spanned

I wish we mean the distance
between our galaxy and

other galaxies and
it's just increasing with time.

So we can look at what was going to
happen in the future and what happened in

the past on a pretty simple plot and
I'm going to show a version of this

plot repertoire and so I Y. axis here are
already in the separation between us and

some typical galaxy and
we normalized into a while today.

So today that galaxy is one unit whatever
that you know have to be away from us and

that's the time as well since we know the
obvious expanding problems observations.

We know that in the future point of the
right that galaxy is going to be far away.

So we know that we live on some
kind of purpose going up into

the right in the Star.

Well.

Conversely in the past.

Everything must have been closer
together in our spare universe so

we know that this curve must also move
down the block and so already just from

whole observations we can you know draw
start this field on this earth and

show you know those going
off to the right to view.

So we really like to know is what is
her going to do farther on future.

What did you do previously and
what is the history and

future of this extent there's
an interesting thing that already

figure out if we were just assume that
this expansion was very very at a constant

rate graph time we can't just play
the movie of the universe backwards

put this on the wires and see that galaxy
which is a certain distance away from

us now would have been right on top
of us at some point in the past and

that's the kind that we call
the Big Bang and if the universe.

They expect with a sort of constant rate
we could actually just from figure out

what the whole concept is figure out how
long ago it was from the beginning and

the formulas are actually quite simple
the age of the universe the kind

since the Big Bang is actually
just one overall per year.

So that's anything we
want to know is going.

Expression uniform.

Actually we don't think it is and

the way we figure out what
the expression is doing.

We need some physics to do and because
we're you know that I have certified with

places in my prime not
fully with a point so much.

We've been through a few assumptions
Firstly assume that you're worse

on one of the skills described Einstein's
theory of gravity general theory and then

we make an assumption of the cosmological
principle of the universe homogeneous and

isotropic any it looks the same in
all directions and you can test it

off racial we have good tests from looking
at the way galaxies are distributed in

the universe and looking at the way the
cosmic microwave background which you're

good at your result look the same in all
directions and we've also just a general

assembly on various scales and that seems
to be our best theory for gravity today.

So combining those two that's
sort of our best estimate of

understanding how the universe is going
to evolve and if you from others.

So you lead to a specific metric for the
universe it's called freemen living for

sometimes Roberts and water matter and
it has a lot of what it turns out or

whether the time and
space of the space time interval.

I want to go is that so

much of the details of this are there
to sound facts about this matter.

First of all there's assumption of pay
as you see with multiply the whole

spatial part of the metric and
that's called the scale factor so

that multiplies all spatial coordinates in
the universe and so that's what we really

kind of talk about in terms of the size or
scale of the universe is the scale factor.

There's also another constant here K.
which describes spatial curvature.

And of course my friend I was raising
show that is very close to zero.

So we actually don't have a word for it.

So photons in general to be they
have a spacetime interval of zero

and that leads to a relationship for
the current so that as they

travel through the universe their weight
line stretches with the scale factor.

So.

The scale factor is growing which it
isn't exactly a universe of photons

until a wonderful calm will increase
as before all through this universe and

when that which serenaded is related
to the way it would give Mr observer.

By the ratio of the scale
factors of those two times and

this also relates to the squire easy.

Which is the right color and
this is something we can observe if we

know a certain photon has a wavelength
we can observe it when it gets for

a telescope and
we have already so the whole

idea of the small used to figure out what
is this scale factor doing with time.

WHAT IS THIS A with C. and so
one simple way to do that is that what's

called a you know magic description of a
scale we can normalize it to be one today.

Any loss of generality the slope
of the first derivative

is related to the whole parameter
of the second derivative

which the here we call
this all racial parameter.

I was there.

The second derivative there and
you're going to calculate third fourth and

fifth derivative of the scale factor if
maybe there are serious expansion around

today zero then you get value of the whole
parameters of a that's actually what

we call the whole concept of the value of
that you saw aeration president today.

You know and you have the jerk parameter
and further derivatives of celebration so

there's your nurse now and supposedly
at the next root it's crackle and pop.

That's actually true.

Anyway so we can expand the scale factor
into these derivatives and learn about its

evolution and its history and one other
piece of the public goes into these kinds

of measurements is we need to measure
these distances in the universe and

actually an expanding universe what you
mean by existence is somewhat confusing so

we use a specific kind of distance.

We just call balloon oxygen in the sense
we observe an object far away.

We measure its flux and
if we know it was in transit.

When I asked any of them they're related.

To each other just by the inverse
square law like so this piece of L.

is a living off the investments that
we can get from the measured slugs

in the know in physical nonskid and
it turns out if you

crank through this metric in front of your
all that distance it is it's actually some

fairly straight forward relationship
between this will not see distance and

the scale factor or
at least the first through the scale.

So this is a somewhat you know
you have you leave you there.

All you have to do numerical here is five.

It's pretty straightforward.

I want to get it.

OK So the idea is now this plotted
talking about in terms of the galaxy

separation and time you can really
you know do I was part of the new way

to galaxies aberrational that just tells
you what's that separation between us and

this galaxy Well that is exactly the scale
factor relative to the scale factor and

that is directly related to that
pressure parameter you saw before.

So if we measure the ratio of the some
object we can put a point on the Y.

axis in this spot just
by measuring the right.

Something we can do I was great on this

axis we need to know the time
at which that light was emitted.

So presumably now looking back at
the past when might this be a minute.

Well actually it is about
women oxygen distance.

Sure before divided by the speed
of light from a distance in time.

So the goal is to make alterations
to put points on this tire and

the trees out of this her for the universe
is going to do by measuring the red

shifts and distances of octaves and so

what do we expect for that illusion.

Well depends on what the universe.

What's in the universe.

So before I was sort of part of
a kinematics of the universe the scale

factor the derivative the acceleration
the next routed the jerk so

we can connect that to matters
of the dynamics in terms of

what are the forces in the Emperor's own
lives and on what you are so full of.

And usually to some Vikings and
puzzling way you might.

A universe full of different
kinds of perfect fluids.

You know people are kind
of put in a state and

I was going to that you felt
too much about you different

constituency of course but one of them
was just sort of the whole matter.

The only think of or

even dark matter which has the value of
this equation of state parameter of zero.

You have actually exposed as energy
density is just in the mass density.

There's no pressure on that normal high or
having normal gravity attracts everything.

And so it was at the celebration
of the scale and so

it's an acceleration which is needed
proportional to the density of that

you can have radiation through
the universe of photons and

also other more exotic things like
an awful constant talk about later.

But why saying it different
about the cosmos the concept

first of all it has a value for this place
in this day parameter exactly minus one

compared to zero from matter and
the second thing is that because of

the positive value of this it's
already rather than a negative value.

So if there was a problem for

the concept that we call the scale
factor to accelerate you so so if

you imagine how different amounts of these
different components of the universe.

You can calculate your right to be
what different curves would look

like in this case.

And so here this record is one with a lot
of matter and no awful consequence at all.

So there's a lot of these all aeration So

today the scale factor we know is
normalized the one we know from the whole

concept of the slowed mass to be so
those are all fixed but

the deceleration caused by a lot of matter
will cause this curve to turn over and

result in what it will call the big
price where we have expansion now but

the universe will stop expanding in the
future and then come back to a state of

very high density and you know first go
backwards in time and see what happens

if there's Last matter in the universe and
the density is not very high and

you still have these celebrations of these
blue green curves are still be celebrated.

But they never actually
close in on itself.

So it's a the analogy to fight for
a lot of dollars a day care.

Most of all the people who are on all
this trajectory they come back down.

But if you're really strong on steroids
scandals and Baseball recently and

you get really strong you might throw
the ball up with escape velocity and so

you know it's all you slowing down for
the skid and

never come back out and there are only
matter in the universe these are the only

possible trajectories and so what we were
hoping to do was try to figure out which

one of these trajectories are you
the worst actually was on and

of course one with you that is will one
time and see what happens to the scale but

we don't really have billions
of years to wait around or

don't you know we might
put it another way.

So look back in the past if we look
far back in the past we can tell

the difference between the skirts.

We get the red shift gears the Y.
axis and distance all the time and

so will be able to point on this diagram
and figure out which one of these

universes we have problems we know
where we can measure the red shift

actually fairly easily into objects but
we need to measure the distance and so

we need something that will tell us how
far away it is good just standing here

that works to billions of light years and
that's where the supernovae come.

So this is a picture of a nearby
galaxy again about thirty million

light years away.

This is how it looked in March
of ninety three ninety seven and

here it is in May of ninety
ninety eight where one star

in this galaxy exploded the Superdome and
I see ninety eight be you in this.

You're right.

Galaxy and for a short period of
time he leads to a few months.

One star in this galaxy that's
brightness ten billion stuff.

So this is one star you couldn't even
identify it by itself to forge this last

in the walk of life from the hundred
billion stars in this galaxy but for

a further of time it explodes and
you can see.

If you take a spectrum
of this supernova and so

you look at the like
a different way of life.

You see a bunch of
the signature of one from

kind of all those that were fused
in this supernova explosion.

So there's calcium iron sulfur
insulting and this pattern of

elements is indicated that it's what
we call intermediate mass elements

that aren't big on me and so I can tell
is that the way this he's on a form or

from the nuclear fusion of
carbon oxygen very explosive and

we think that there's a certain kind of
star carbon oxygen white floor where when

it explodes it will produce this pattern
elements that will release enough energy

that would make these elements you know
trouble out of space had quite high speed

speeds of time Palin or so kilometers and

so we have no idea why this one case
with most of the different kinds of

supernovae different kinds of exploding
stars but this pattern of how that's how

it was it was just one of these why for
our own option what course of explosions

to produce you see so

we have a kind of a story about how this
works to produce a white horse to know

you kind of actually need a complicated
scenario you know there's no you know

there's a different kind of growth for
five years to grow which just happens when

I'm very massive star or that about
eight solar masses it reaches the end of

the five and these are a little bit more
uncertain and a little more complicated

period a binary star and stars are undergo
this evolution one of the stars becomes

all the way for so our sun will for
instance end up as a foreign object and

wife works at the end of a five
you know five billion years but

in a certain situation where you have two
stars her side is not environment and

so are some never undergo
the supernova explosion.

I think you have to start close
enough you can get a second start to

dump material on.

On to that first white four and
it turns out that trying to separate

predicted a long time ago in the thirty's
that there's a maximum now for

this kind of way for about one point four
solar max if that companion star dumps

enough material so much of this light for
approaches that live it under head for

a limit it can explode and idea that

they all explode as they reach this little
bit which may or not may not be true but

it's that's the theoretical understanding
we're still being so I understand this

better if that is true in fires that
maybe these explosions are very similar

to each other because they are happening
roughly the same way they all happened one

a certain kind of way for exploded want
to reach a certain mass and so we might

expect that they're very uniform no
matter where we see them in the universe.

So there's a lot of detail and you can get
a whole pot just on this little slide.

There's a lot of these
health it's complicated and

it's uncertain we don't
know all the details but

observationally observed this kind of
supernova the one that shows the elements

that it should be for to be very
homogeneous to be very similar interests.

So here couple examples of the light
curves of these are grosser just a part of

the brightness is a function of time
using ninety to the sort of structures.

You don't see here in different way.

Whites.
So starting with the ultraviolet weeks of

offical light of it being
too much of a mirror.

So this is actually going to I
will show you the formation A.P.

you in a nearby galaxy.

Here's another one more recent ones
you've done one feet in another galaxy.

You can see they rise for
a period of about twenty days and

get away over that period so much.

And so we study we measure
the life purpose for the tsunami.

We can't predict in advance where it's
a good one agent was going to go off so

we have to monitor galaxies and hope one
goes off and then once we see one and

we get all that off this one
was discovered very early.

You can see you can see the whole life for
a fish rising and

following this one
wasn't discovered until.

Well there was last year marks and
so after the white person missing.

Are you so are a number of years
ago starting to deny these

people have been observing these I want to
throw me I noticed something interesting.

They were all quite the same but
there's usually a relationship there was

a pretty small range of how bright
they were about a factor of three.

So the rate of the twenty second all over
looked something like this some more paper

and some were brighter by about a factor
of three what they noticed in this and

were mostly done by Mark Phillips and

Mario probably what they noticed is that
the writer once told longers to fade away.

And so if they made a lot of
how bright the Superdome was

compared to how long it took to fade away.

That's what's sort of shown here a certain
characterization of that would be big

time I did have this relationship
with a writer once a longer range or

once fitted with more quickly and
so what that meant was if you just

measure how long it takes that
should be able to fade away.

You can figure out how to write it really
was was it one of these guys in profaned

or was it one of these guys are so
you know were the shades of Boyd heard.

Let's you read the label
on your current Bible.

They're not all read why explosions
four hundred forty four why explosions.

They have some variation but

just by seeing how they rise in the face
you can actually see your own brain.

Another fact that affects
the like her right there.

Here is imagine you see a white ball but
there's something in the way this thing

you know I hold which
could be in the light and

something that does that then after
physics is what we call interstellar dust.

I'm just a theory or material for
brains usually higher

Carbon Silicon brains in the interest or
medium of galaxies.

You know the source of the light and
make your object look you know where it

really is poorly we know that
kind of dust absorbs moral.

Lou I mean you don't read life and so
if we imagine the scenario in different

wavelengths we can see how much of that
there is and correct for that as well.

So there's two corrections really made for

you to be Superman to make them
especially useful for this work.

Why is to measure the shape whatever and
the other scenarios are going different

colors to correct for
any of this extinction either.

So here's your own more modern version
of those our original diagrams again

showing the supernova brightness first as
this decline rate in different various

different weird lights and this is sort
of a formalism that I hope that all of us

part of my pieces to fit these like herds
and measure the writers of the surprise I

won't go into the details of the formalism
but we basically take those like Earth

to a model that's described here and
figure out how far away.

Was that it was how does
it work in practice

periods who are examples of these like
a perfect sphere if you supernovae

you can see in four different always
like bands and in white on top.

You can see the model fits
the markets are pretty good.

They don't always do a perfect job.

This isn't the brightest way but you can
see that there are some problems here from

all of those that fit the data very well
it turns out that's a feature not a bug.

I reason is that we actually know
the supernovae are themselves

are quite variable in this fact they don't
all follow the same behavior and we're not

sure why but them all of those are there
and they can be way off here where they

can't be very far off and these parents
near the end sort of model accounts for

that to make sure you're trying to use
points and doesn't worry so much that he's

so when you apply this all kind of
complicated operands to these objects.

Here's the existence of
modules that comes out.

So again these are just it's isn't
a strong pull system of units.

But anyway.

You just want to where you can see this
one is a very very five or six plus

minus minus over here thirty three point
four nine miles from our point one zero.

So they're very consistent
distances with these.

Now these are two separate supernovae but

it turns out that they happen
to occur in the same galaxy.

So we know they should be
the same distance away from us

usually decided when a supernova
over the supernovae goes off.

No typical galaxy.

Maybe every three hundred years we
were very fortunate that this galaxy

from our point of view anyway.

Had taken a supernova the two of them
that went office three years apart but

it was really nice to check out the method
for when we are five this analysis to

these two objects we get the same
distance but if you're going to be there.

We have to get there and see.

And it's totally independent data and
not give them this makes them into so

that's a nice external check Very few
more that you can see here is far showing

the parent magnitudes of the brightness
right on this and feed on this and

a supernovae compared to their
philosophy the redshift so

very similar to the guy around
the hole made earlier and

you can see if we just assume that all
those are going to be were exactly

the same that's the assumption of
what's called the Standard Model.

There's quite a bit scattered here
about twenty percent in brightness

if we have five days corrections for
the shape of the light hurt and

the amount of dust the different colors.

We can get that scattered down tonight.

And by the way I was in this line is not
exactly a fit the slope of the wire is

just fix by the fact that the light
should fall off as one over the square.

So the slope is not something you can
play around with your you can play around

with the spine is the intercept.

So there's just one degree of freedom
here you see it fits the data and

using these corrections takes a pretty
reasonable standard handle of

the you know twenty percent
uncertainty in distances.

So I guess it's a much better post.

So this is Imperial validation that
the method works I said the theoretical

underpinnings of what exactly
is exploding how these like but

that's not a solved problem.

But inherently We know that a person's
work because of the proof is here did this

line says that you know these objects all
have the same corrective brightness and

they view all objects are assigned
to pursue know about ten percent.

OK So when you have that you can make
the whole Hiram dislikable dead and

this is something we did a few years ago.

So here it is now watch the distance.

Just like all that matters
are the very few hints for the last.

And so your parents are going to be
each point there's a difference or

another right on the spot.

I'm way down here and this gray box.

Is Hubble's original to me.

So we've extended it way much farther

out that we don't use galaxies that close
because they get tugged on by their

neighbors too much that
the velocity is from unreliable.

We go farther out into what's
called the whole flow and

we confer all the original you know
sort of writing measurements down here.

They really send you to flee our part.

And we actually measure of value for
the whole concept of service there.

We've actually improved that
value recently with more analysis

of the absolute brightness of used to
produce the whole space telescope.

We have a three percent measurement
of the Hubble constant interest.

So that's nicely put find signs of
desire of walk speed and distance.

What does it say going
back to this plot in

terms of the history of
the future of the expansion.

Well the problem is with
only using these need or

by putting those are going to be which
were only about a maximum of about two

billion light years away all the points
that I've been showing you would have fit

into this little part of the diary and
that unfortunate that's not where all

these curves start to divert you want to
know which one of these curves we live on

we need to go farther out and pull points
on the diagram direction it's more

distant supernovae to see
which one of these curves.

So you will realize that even
back in the ninety's and

people started this project
to look at higher a fifth.

Very existence of a.

We put points on this diagram and
figure out the fun of these prayers.

So how do you find these very very distant
supernovae Well they're very faint.

So we did use big hospitals and
here I mean a far different place.

But this is an image of the C C I L
four meter and star exploded in

Chile and so there's a bigger picture and
I think the southern

sky pierced the Milky Way If any of you
have been to the summit comes fear and

which is so in the sky it really is
it really is beautiful life here.

You know.

So this is the center of the Milky Way
when there's a there's the Southern Cross

appears I'll do this and already here.

These are two neighbors galaxies ours
which are the larger one in the smaller

like the overhead post over
here in Chile is really

always really the improvement that led
us to make he'll make these measurements

is on the end of this house of the house
to be built in the seventy's so that's

been sort of the same for a long time but
that innovation in digital cameras.

Now if you were to have big digital
detectors which could take pictures of

larger types of the sky
here that's the real C.B.

technological very critical of in
the in the ninety's a lot of news here.

We need to search the archives of
the sky to find these supernovae

because the supernovae are very rare.

I said maybe once every few hundred years.

And yeah we see.

So if you study of a few hundred
galaxies you might find once you've

been over a year.

Well you said You thousand galaxies you
might find one supernova a week and

we want to find lost three times or
even hundreds of people so

we need to look at last galaxies and
how the sky like this.

There might be safe and thousand galaxies.

You can survey in just one year.

And so that's really was the breakthrough
in allowing this this sort of offering

this is how you do it if we
take a picture of this guy.

Here's a little zoom in a you know
one of these regions with lots.

The galaxy is yours and
I believe he's right one.

When we come back and take another
picture a few weeks later and we look at

them here to subtract the suit images and
ask you know has anything changed.

And if you look very carefully.

You might I feel to see that
something has changed but

if you're doing your job as well.

You take this one minus
one you see what's left.

And you can see that there's an author
right here you can see it right there

in this image.

I was walking there before and this is an
illusion where all that exploded in that

galaxy in this week time to be so
and you know we didn't

know which one of these galaxies are going
to be more than this one and I wonder any

of these we don't know we're sitting on my
car but if you look at enough galaxies.

OK so

here is another example of a supernova.

That was observed above the Space
Telescope at an even higher redshift this

the value of Z. is one point three
the scale factor of the universe goes.

Basically as one zero and one of the as I
want to see in this case is still quite

very I mean the universe when this really
explore the universe was two point three

times smaller than its current size and
scale back the most of my free time smart.

It is today.

So more than halfway for back into
the history of the universe where we

started the circle and
so just to show you.

Here's the spectrum it's very noisy
because the stakes are very faint you

can only do these measurements
with the whole space also for

the most distant objects and but
if you look at it very carefully this

red line is flowing through all this noise
which is the spectrum of the nearby.

I want to match as well.

The box of wiggles that you see in the
night you start from that's how we know

there's just an object.

There's also one of these supernova
you have the same kind of power but

you can measure a smile for about
what we need to measure its distance.

So here is the first time we looked at
this field where we did see a supernova.

That's over here and

then suddenly there's a supernova
right there are these are now as you.

Washable get brighter.

But now it's in yours and
then it's going to fade away.

And so it gets brighter only to step
back through the glass before and

you can see the figures
develop to brighter picture.

So imagine it.

There were these two teams that were
working on a project like that now

that that nice data was
from two thousand and

two that's after we got one more total
time but you know before that we only have

a good deal of you know what a tough
job but I'll give you these give us so

we have quite as nice bit of science and
interesting results.

So there is you see this time I was on the
same problem I see supernova search team

led by our great Schmidt helped
us really an after university and

the competing teams should know
about all of the projects but

my small home under five a large Fergal
and basically simultaneously a nice ninety

eight we can produce results that showed
that the supernovae were not behaving

in terms of their existence it is as you
would expect in the universe that was only

the celery so there was only a matter
in the universe you'd expect or

if you do sourish in for the scale
factor and you would expect the tsunamis

a little love to look down here
in the dark and they don't.

There we are here and
this is the accelerating regime.

Here's how I wish about this if
those points are the contours

we're down here that would
have been well we'd expected.

He's already in first step and they
are the ones we have here in accelerating.

So I did this discovery of this already
versus caught up to the scientific

breakthrough here and I want to give you
a little bit off lever of course and

then this year alone or
last year this same result

was our own love of Christ physics and
that's why we're having this talk now.

So there are three people who are going.

Price I recently ran from
it from our theme and

saw from our leader the other team.

This is the paper that we submitted and

I came here reporting our first
results I was ready for it.

It's from supernovae for it's already
the universe and a coffee concept because

I get so I don't raise the price
members who authors do about price.

I'm not sure why they got it and
I'd say some other authors.

I mean all know actually you know but

I just wanted to give you
a little you know so I was a grad

student times a third year I was doing
this paper was coming out and I wanted to

be into little view of what it was like
in those days when we were doing this and

of course we didn't really know what you
know what you have your results you have

you just knew that you know we were
trying to make an important measurement.

We also knew that we were in competition
with another team was also doing this work

and so there was a third
seed to get the there and so

I risk was leading our analysis of
this first supernovae here sort of

a pretty you know harsh task master and
that by the way we operated

as we had farmed out as you
can only different people.

So these people were kind of
the worker bees on the female time

there's me you know we're
the ones responsible for

measuring the light purse of these
supernovae and we'd have one or

two supernova that were ours that we
had made and I decided that line.

So this was in October and you know
something I don't know exactly deadline I

think I guess of October ninth for us to
get our analysis done and back to him.

So you could look at the distances and
figure out what the fiber I was on and

so this is you know I
just I'm from overseas.

It's like wow I can't wait.

It's almost here.

But the life emphasis on dad
that's sort of a subtle threat.

You know and so I just like it's like
you know you don't get your stuff done

by time.

What might happen after having
dinner because there's only

two days left to turn in your completed
relative supernova of concrete

the measurements of how
bright the supernova.

So at the time I was a private student I
was working as a service hardly put on

that there was an issue
that the software was

were all news I asked you very
favorably So it was difficult and

I was still still very good and
so I worked on it.

Two days went by and I didn't get it and
I was not one to you know

he doesn't like and so I was actually
quite nervous I don't like him once and

I have and I mean and I and
I you know I didn't hear from him and

I was sort of worried it will happen but
instead I got to see so

many things like That's nice and
surprising Hermano here are birds.

Thanks to all who sent in their wife heard
yesterday I received everyone's except for

one verse you know you are OK So
if you're ever having that error.

You know gratitude reading this thing like
I thought you know maybe Aaron was having

problems but no it's only you know you're
the one holding up this if we're projects.

You know.

Yeah I was sort of really shaky at
this point I am I'm shaking right now

I see everyone's exactly one person you
know your for this threatening tone here.

And when they signed theirs and I have
them all so you know you are getting me so

that was a clear message
sent directly from me and

so you know I was really I
dismissed I was private.

They were running my tires
are you in around so

I and others because I wasn't
I born are in the group.

I don't it's hard times I look for
them and find out who your brothers.

He talks to the hard time I couldn't find
him so I was like OK well it's Friday.

I Can we get on this in a work in
a straight through thirty six hours that

fully get the data done and get them sent
i'm so I did that I think by Sunday night.

I thought I.

So that's you know sort of relieved
to you know not be holding it up and

only held it up for a couple days.

Remember we were in this for a bit and
competition with the Soviets and you know

those two days might have been there so
I wanted more you wanted office and

I saw your version the charts were
the most I was there and I was like

I'm really sorry I was the one holding
everything out like I did Sunday night.

So it's fine.

So don't worry and they will do that
meeting like in your eyes was a joke.

No one got there period and
you said this to everybody and

I was the only one who has
done enough to offer him and

he not like you know forty
eight straight hours of work.

I mean just by having this or
are you saw the moral

of this story is so
when I will write your students.

It's a work in heart.

So it's a good lesson for YEAH THIS IS SO

this is I really you know this was for
me it was terrifying.

Everyone else knew that Adam was
just you know had this was hers.

Anyway I want to do some more so

after this was done and after a day.

Don't worry I'm wise you'll be darned if
you're the one doing the analysis he did

Washington out of this and it became this
you know very surprising conclusion that

the did favor this accelerated
model with the price of how awful.

And this was a concern.

First of all we were expecting that
all we were expecting the story in

terms of the mothers who are in love with
the paper the year before from their first

handful of supernovae which indicated the
celebration not the next operating hours

later it was we didn't know that yet they
were also find your story for the time.

This is now in January
of next year you know so

I went out and sent some hair around for
the whole group and Housefull and for

all I remember that was my postdoc riser.

I'm seventy eight.

I'll say I'm sorry fantastic
off before he left his wedding.

So I actually had.

Getting Married out
recently pretty exciting.

We are doing fine.

On zero House on the constant
Are you celebrating you know who

knows this like you the right answer.

We have members of the team from all over
the world and so you know this you know

how the world and people you know
responded if they vote for or doesn't

rely on the from very same and very
hard problem because of I'd like to ask.

I don't for anyone else in the group if
they feel prepared to defend the answer

there is no one writing articles
were not very forgiving very rash

met my show is a Tea Party leader.

I agree are terrified of the possible.

How hard they are in this
result I find very well for

sure it was my either heart of mine but
it was about and so

far I'm worried in your heart you know
that I was constantly wrong in your head.

Hell you don't care.

You're supporting observations.

You'll be silly to say we must have
a non-zero problem often only to

retract it here and the reason that we
have essentially you know biased against

the idea of this concept
is that you would.

Einstein because the consequence
is his biggest blunder.

He'd originally had introduced and
there are ways general thirty to explain

the static universe one where the skill
factor wasn't changing at all and

that was before all those observations
showing the universe dynamics expanded and

so I signed supposedly realized that you
know how all the possible actually needed

in this model you didn't need something to
counteract the effects of gravity and so

we said well you know it was my
biggest blunder and so helpful for

since that I know of course that you know
what the cat is out of the bags hard to

put it back again in a lab the park was
has been around for a long time but

you know any claims in the past
that we also have cancer and we and

most of those who are you know shot down
and so we sort of knew that history and so

to say that we were you know
resurrecting this long dead cat.

It was it was certainly a concern for
many of the people so.

Actually serious responsible scientists.

We all know that it's hot
it's the air we all know that

particularly reaching firm conclusions.

The value of time I read why we
need to have all these different

places to have access to telescopes
to get us to do them for

this kind of big project who are the
detection of magnetic monopole and other

gaffes on the other hand you shouldn't
be shy about giving our results out.

Alex is sort of you know
told him you know what stood

out there said all around me and said so
be at least be running the race.

I don't really have done a lot of work
in trying to check the result and

they are what I said the results
are very surprising shocking even

I don't know what is how anyone about
them because I want to use the prospects.

I have and I want to go further into
writing results that they were firing on

zero problem on set of procedures all out
of your heart you know in your heart or

in your head or
with your eyes your servers are all

meeting to the data as well but
there I figure.

It's from ALL hundred you
know he was also in Chile.

He said I signed me to the state
because my view on said I couldn't wait

that's a very odd hundred hundreds
David being my you know when we sit

on the Sunset one of the other
a leaders of our group.

I really heard you have to work your butt
off on this we need to be careful if

you're really for the common
concept of not the I get it out.

I mean this seriously.

You will never have another site
because all of the words I mean come

your way in your life and so
I made it a kind of the sense

of the group in the in the surf you
days after we first come first.

You know that she was often
you know people's feelings.

So here's what it looked
like on the kind of graph I

show you the supernova data favored
of her that wasn't any of the birds I

was from before in one in which the skill
factor is actually expanding faster and

faster with higher acceleration.

So here's you know one showing
the data here's a more schematic for

it instead of any of these curves
which are all slowing down with.

Time we actually live and accelerated
a universe where the scale factor or

the distance between galaxies is going
to go after about three faster with time

and so didn't publish our paper
the only republished there ever.

I mean for the same reasons and

now I'm the only you know years of
passing that's been confirmed as often.

So this was on December eighth of his life
a summary of what I mean are I see Team

twenty members and with I don't
think Brian receive you will rise.

I don't for being the first offer on the
discovery of Ryan for being market leader

there I and my second heard there as I
was saying to someone I want to share.

I really urge you to want to know Christ
because the party is really great.

So you can hear the results of these
kinds of things get fancy gold medals and

stuff like that you're
some more pictures you.

There's a riot and solve problems are for
the leader of the US Here he and

we in Sweden receive your prize
winning big power over people and

people are standing up.

It turns out that and I offer no
bells will physics is the first prize

in action and so the physics prize
winners get to get their work first.

And they're the ones who get to sit next
to the royal family the banquet and so

there is Brian two thirds of
the picture is cut off and

it's all on the other side
with the crown princess.

Sorry there was a the current
business when this was very

a timeshare people have a very and
there's a really embarrassing.

How what picture out of staring at
her pregnant belly which made it

was how boys because this was
like Oscar night and stuff.

So anyway.

And here is actually
kind of a public figure.

Not everybody but as many people
did attend from the two groups.

So there were again twenty barks here on
the high seas even about thirty people

on the streets of Hollywood probably
which were big teams by astronomical

numbers of time.

So if you're in physics part of physics.

Or for that matter really review our
game but of the time the late ninety's.

You have to get a big group of people to
do these I mean this is the prize was

awarded this the wording for the citation
it was for the discovery of these already

expansion of the universe through our
existence of distance or the big question

now is so that makes already a universe
that this distance between galaxies is

going increasing faster and
faster so yours will movie of it.

Where exactly did you celebrate it.

And now it's accelerating as something
is calling the universe puts him faster

to the pride of how a warrior for what
causes politics over it was awarded for

the discovery of probably sorry I don't
quite know what possibly it's already been

that what people are working on today we
have an answer but it's just a living

answer called dark energy because some
substance that fills the universe.

It causes it to expand faster and faster.

It could be the quantum of
constant of a big mentioning but

there are other many other possibilities.

All right for our time so I just wanted to
quickly talk about a little bit about what

you've been doing to try and figure out
which one of these possibilities could be

either come out of Kansas in fact
every sensible answer is observers.

But if you ask a theoretical
physicist How far is that

it's not a very sensible answer.

I think trying to predict what you might
expect to be you got the answer wrong by

a huge factor and also some puzzles
density of matter is just like everything

else you might think of you expand
the volume with which you have some matter

all the density goes down and that's
what's shown here in this blooper but

if you expand the volume you cut off
a constant density just stays the same.

So the US twice as much volume
you're twice as much on the rocks.

How does that happen so

much here it's also you know why is it
now relatively recent New History of

the universe of the cosmos concept
density in this vacuum that city.

Anymore that mattered at City.

Whereas in the past that mattered
a city where they were a dollar about

let's call it was trying to figure out.

So the answer a lot of the concept
seems unreasonable assumption and

so we're trying to figure out is it
all of them is it something else and

the way to do that is to make more precise
measurements in this part of the curve.

If it is a composite we could
again just wait a long time and

will see that the salaries will
keep increasing after Nasser after

it will be out of these first galaxies
will be moving away faster and faster.

We'll tell you all.

That's why we need to make these
measurements now because in twenty billion

years ago the galaxies were far away and
one hundred billion years ago.

We'll be able to see any other galaxy and
so if you want to you actually live in

China now it may not be the compounds and

it might be something else of the dark
energy might not because it could be

dynamic and then it occurred
doesn't have to just go away.

Does it put an over I mean the start of
a Big Crunch depending on the areas you

could also have a big wreck in which case
everything gets broken but it's torn apart

in a finite time is we're trying to
figure out what those possibilities are.

Here's what I will die around looks
like today instead of just how I ten or

her forty's are probably we
have hundreds of supernovae on

a library at all these different
branches from a number of servers and

we have sort of this continuous
measurement of this expansion history from

supernovae you know intense
observational campaigns.

We've seen that in the past you know
it was actually good you celebrated and

we don't seem to see any evidence
I've heard this phrase through these

often we don't see any evidence
that the dark energy is changing so

no worries that column article
concept model one with W. It was

minus one is part of the consistent with
all supernova vigor that we have today.

I mean you take that statement
to about a ten percent level.

So a ten percent decision on this
question of state parameter.

Everything seems to be consistent
with the current model but we like.

Do better.

And so in the future.

I understand you're not
just the future and

you the future of our
understanding of our therapy.

Well the supernal in right now and by so
many super only observe that now we

are limited by systematic answer and there
are a lot of what are the generators.

I touched upon and we don't know
exactly what is exploding how they

did change if you look at them in hiring
shifts are they in the same as the ones

here by how well these methods
to standardize them really work.

How good are the tech there is and
how very much for measuring and so

technical and
issues with these types of radio work.

So right now reserve a ten percent
compensated in this equation the state

parameter still consistent with a lot
more in the near future than the say

the next decade constraints on the way
to a few percent are probably peaceful

with increasing sample
smartness adultery and

examples with issues like the largest NOT
picture of it also and perhaps a wide

field infrared survey the scope this
is going to be on the ground in Chile.

This was our plan space telescope to
look at is another very important thing

is it's just not true that the evidence
for it is already universe and dark energy

today there are many other pros because
it might redact from the W.X. I played.

I'm sure those that indications are after
have been this accelerated universe

other problems of dark energy curricular
measurements of the whole concentrate part

of the beginning political scenario
are for matter that are very complementary

to the Irish assuming there are other
problems that will are coming online.

Maybe into various supernovae It's nice to
have all left techniques because many of

them have generously used in different
parameterizations of their dark area.

Here's one of them.

I want to get into the details
of these parameters but

it is the dark energy the causal
concept you expect this grander W.

not to be might just want you to focus
ground or which measures any change in

the dark energy both Come on folks in this
concept so you expect that to be zero.

And so you expect.

It really is because one concept all these
different purposes because you are for

the universe this point and ours.

But you can see they all have
the heresies in different directions and

it's really the combination of
all of these different techniques

that will give us the best
handle on what this dark energy.

OK so I want to close with this.

It's a very interesting time
not just because this research.

You know you happen to love into this
you know as a graduate student there

doing all supernovae might be interesting
to work on and not having any clue what

it's going to turn into but it's also an
interesting time in terms of where we seem

to now have a pretty complete inventory
of the composition of the car.

You know whether I cast out to
be kind of have their uses.

You know have the elements like you
know already been ironed in the things

that were made out of one point over some
of those little composition under a tree

those and in stars point five percent.

I return Elian like normal islands that we
think about only about four percent all

together of the universe that
is normal stuff that you

know about I think there's been talk about
using variants in a way that we progress

on this summer's chemical little
possibility that the big question is

we don't know about these two
big unknown parts of this high.

You know we know how much there
is dark matter dark energy.

We don't know where these missing baryons
are we don't know what dark matter really

is that we don't know how much there is
and we know even last about this star and

so it's kind of you know whether
you see the glass out all I see

is this a prosperous model where we just
you know we're just putting in the age for

ignorance or that something was really
good about the components of the universe.

Now it's time to figure out what they are
but I mean we live in a really interesting

universe and beyond to live very
interesting time we're going to make life.

That's all.

And there is life.

Thank.

Yes that's right.

Yes For this technique for

this economy you can measure it in
different ways but with different.

I think you can offer Richard
to be a free printer for that.

And so we do the fits in with or
without fixing her at all.

So the public library background transfer
very limited her to be very close to zero.

So you can put out as a hard story.

So it doesn't affect the results

you know there are more holes
than you can you know so

that I think there is a sense this
is covering this for the paper.

I'm all over dark here every day.

So that's how many papers are and it's
quite a wide range in some of the halls

you can rule out hers as the measurements
of tell you that we have today.

Some of them were predicted you know minus
point six or something like that which you

could rule out you know the simplest model
of course is the lab the whole thing

it really is the cost concept we have
some kind of the road finder standard for

at least how that works and you are how
that arises from our use of the vacuum

that people are much more uncertain about
at least if you are the expertise or so

and as far as the worst kind of you
know like one all that we can attack and

then there's a range of other things where
people comparative alterations some will

doubt but some are so close to how
often are all that it's very hard to

pull them out if you made some
other technique to look and

it doesn't have to just be
some kind of fluid with it.

Where there's a primary it could be
a modification generally it would be.

It could be something about the universe
not being perfectly homogeneous So

there you know broader class of model
than him even after just a single

figure back home result very serious

in this one or so

the original for me.

Just so I had he would be visiting me.

I see some of this election with her.

Yeah I think all of

that who you say do the past yet right.

Yes you have to sell this mall
is a silly Marvel concept where

basically in the long term future that
scale factor just grows exponentially.

So in the long term this will
just become one of the T.V.

Kind of her but that assumes
that the dark energy density is

constant the actual density grounds for
doing so.

Meter of dark energies stop this
constant which is what are the possible.

I've got on one of these more complicated
models which in fact the dark

energy field or whatever it is made to
pave the future for change in some other

way that you have heard that certainly
a matter of fact here but then first.

So we used to think that the density of
what we're trying to measure was destiny.

But we could predict for

future was just by measuring the density
of stuff today but actually do although

more complicated models of their time
it's not true can't really say for

what it is it's a lot of possible yes
we know it's just an accelerator.

But it's something else and

the art dearest friends tell us that
it's likely to be something else and

we can't say for sure until we
have a good theory that's awful.

You know it's one person so
there's you know that one simple law that

we like to test is this land of all I
want because it says a W. B. minus five.

If you change the time and the cycle
you say it should be different and

there are so in fact right now we have
a few hundred objects and people love

to not see any difference in different
direction but it's something with this

future surveillances to you that we really
do will have thousands in different

directions and will look very carefully
to see if its origin is the same in that

direction as it is over their eyes or
prediction of the particle concept model

some of these very models of the very time
they offer various theories as well and

you might be able to tell that
something else I do exactly.

Yeah but I know it's hard enough
to do that now says so and

so yeah you're right I mean there
are going to be as right now.

You know one homogeneous universe.

You know are you large average or you
are you know how does that actually work.

So we can give you all of the last.

This is an already shifts and you can see
that it works with an homogeneous model

but right now people debate in the
literature quite a bit saying It matters

quite a bit you can't do this averaging
this whole procedure is not right or

you know it you know you can think
you are it should only be a scale.

So I'm shy as atoms are I can't
decide between these two but

people are seriously
considering this possibility.

You know you know if that
metric is not the right one.

How do you know if you for these.

You know.

Yeah yeah

yeah yeah.

So I think very the right one is for
military.

Yes.

History that said Yeah.

So they have more data they have forty
two hundred fifty four nobody in that

interview you had time but there are Irish
twice as big as ours and the reason

is that you have a higher signal from his
observations and more filters than there.

And so statistically the power of the data
sets are about same everywhere and is life

generally by some bigger cars and so
in fact both of them give them a salary.

So for example you can see that there
are many more red points about the wind in

the local water system and by I can see
that it really does various origin.

Even with fires are low points
are more tightly concentrated but

there are some so yeah it has happened
to do with their quality and for

the history of the teams and
however there are a lot of

thank you.