so the news has just come through of the
2011 nobel prize for physics uh the
nobel prize has just gone to three
astronomers uh rhys perlmutter and
schmidt
who between them get the whole prize and
i think the way it splits up is
perlmutter gets half of it and reece and
schmidt get a quarter each
actually it turns out one of these three
is a mate of mine brian schmidt and i
were graduate students together many
years ago in fact he was you know a year
or so below me in graduate school so
little brian
has now won the nobel prize has shot
past me to glory and clearly i've you
know not been doing the right things in
my career
but i'm very pleased for him he's one of
the nicest guys i know so i'm delighted
that he got the prize is everyone in the
building talking about this today have
you bumped into people in the coffee
room and they're all saying what do you
think um i i want to talk about it but
it seems like a lot of people haven't
been
uh i came into the tea room and and told
all the grad students and it didn't seem
to care very much but um maybe
maybe it was just too early in the
morning they've won the prize for very
carefully measuring the brightness of a
handful of
little dots
and learning that they're not as bright
as they expected them to be
and this just has very fundamental
implications for uh measuring the the
fate of our universe brian's very
interesting guy uh he actually he lives
in australia now uh he has many talents
one of which is for example he he runs
his own vineyard so he actually makes
his own wine
which i'm told is very good i get to
actually taste it but i'm told it's
extremely good and in fact brian and i
have a bet because i bet a number of
years ago that this result was wrong and
so i have a bet of a crate of his wine
from his vineyard against a really good
bottle of malt whiskey that his results
were going to go away
and i think now he's one of the nobel
prizes i'm going to have to pay him to
be honest so the science that they've
been doing is that these guys have been
studying a particular type of supernova
a thing called a type 1a supernova
essentially it's just a particular kind
of so supernova is just exploding stars
stars at the end of their lives and this
particular designation refers to a
particular kind of supernova um which
has a rather unusual property which is
that they're all the same and it's quite
unusual in astronomy to have things
which are all the same you know most
types of supernovae for example some of
them are brighter some of them are
fainter the interesting thing about this
type of supernova is that when you've
seen one you've seen them all so
actually they all seem to blow up in
exactly the same way they're kind of
dull because you as i said you've seen
one you've seen them all but but
actually that's also what makes them
exciting because one of the things we
struggle with in astronomy is things
which are just kind of a standard right
things that we can actually compare to
one another so what's known in astronomy
is standard candles they're all the same
brightness
if you have something that is a standard
candle it means you know what its
intrinsic luminosity its intrinsic
brightness is
because when we make observations of
objects in the universe sometimes if we
don't know how far away they are we
don't know if we're looking
at
uh you know a bright search light
very far away or a little glow worm
right next door but if we know the
intrinsic luminosity if we know that
what we're looking at is 100 watt bulb
then we can fold that into how far away
that object is based on how bright it
appears to be but what's thought to
happen is it's thought these are binary
stars so you've got two stars in orbit
around another one of them is a white
dwarf now a white dwarf is the end
product of
you know a medium class star like our
sun at the end of its life puffs off its
outer layers collapses but can't
collapse all the way because of
something called electron degeneracy
pressure holding it up so this white
dwarf stays there for a while
and the other is just a normal star and
during the course of its lifetime this
normal star is losing some of its
material onto the white dwarf now the
thing about white dwarves is that they
have a maximum mass at which they're
stable called the chandrasekhar limit
and that's 1.4 times the mass of our sun
and so as long as it's less than that
it'll just sit there as a white dwarf
and this other star will dribble more
and more and more stuff on it until
eventually it'll dribble that little bit
too much on that'll tip it over this
edge and at that limit this is an
unsustainable system and it triggers an
enormous thermonuclear reaction and
causes this star to explode
and that's why we think they're all more
or less the same because actually it's
always at the same mass where these
things go unstable so it's not like
there are different masses of white
dwarf exploding it's just when they tip
over this magic mass called the
childhood sacral mass
that they all blow up the supernovae so
they're all the same
and these things can be as bright as an
entire galaxy for a couple of weeks and
because they've come out of this sort of
standard
origin process
this is why they're very good candidates
to be standard candles the supernova
physics although it's interesting is not
the thing they got the prize for the
thing they got the prize for is using
them as these standard candles using
them as a way to sort of measure the
entire universe and because they're so
bright we can see them at enormous
distances away we can see them right
across the universe which means we
really can use them to probe the
properties of the universe as a whole
they found that the ones in the distant
universe were slightly dimmer than
expected given their distance and what
this is telling them what this is
telling us
is that something the universe itself
has expanded more than we think it ha it
should have this was surprising because
actually cosmologists
before this thought that the universe
was de-accelerating going slower because
if you can imagine the universe is
expanding which you know that from
hubble in the 1930s that the
uh the mass would push stuff and make it
go slower but they found it as
accelerating which is completely
unexpected the genius of it was
that it's a very it was a very ambitious
project to do i mean uh it involved
optical telescopes by the way this is
the first nobel prize ever that use
optical telescopes in astronomy there's
been ones for radio but never for
optical the challenge of actually making
these observations and gathering enough
supernova to make the measurements that
you need to is quite a difficult one
because supernova are rare
particularly type 1a supernova which
which is what's needed for this project
the genius behind it was that they used
the telescopes in a way that was novel
that they went and they they searched
for these these
stars blowing up and if you you know 20
years ago when they started this kind of
thing if you
told the telescope allocation committee
i want to take pictures of galaxies
and then retake pictures of galaxies to
find supernova and in the distant
universe they would have thought you
were you were crazy and i think they did
have a hard time getting telescope time
to do this what these projects did was
put together an industrial supernova
factory in in a sense so they got
telescope time they had big enough
cameras that they could survey large
patches of sky around new moon when the
sky's dark and then go back and revisit
those same patches three weeks later and
then simply by blinking the two images
together you look for a little tiny
change a little dot coming up
perhaps associated with galaxy which is
going to be that supernova and because
you're surveying such a large patch of
sky
you statistics tell you that you will
find some supernova you don't know
exactly where they will be but you will
get a sample and those samples then you
take away to other telescopes and you
follow them up because what you want to
do the important thing for supernova as
a standard candle is to catch them at
their peak brightness
when these guys first started finding
the results in the 1990s this was a
complete game changer you know this is
not what anyone was expecting everyone
was expecting that actually gravity was
going to be slowing down the expansion
of the universe and therefore probably
you know that they should be measuring a
deceleration effect and they started
measuring this acceleration effect which
has kind of overturned almost our
complete understanding of cosmology and
has had to lead us to worrying about
things called cosmological constant and
dark energy and all the things that are
now going into modern cosmology that
seem to be leading to this accelerating
expansion of the universe but this was
really the observational result that set
that whole ball rolling
brian's going to be a busy man today i
suspect he's going to i haven't yet
bothered to try and put a call through
to him because i think he's going to
have plenty of people on the phone to
him today
when are you going to contact him about
this whiskey then i think it's go i'll
wait a few weeks