ALVARO: Let us all
welcome our distinguished
guest, Alex Filippenko.
[APPLAUSE]
ALEX FILIPPENKO: Well,
thank you very much, Alvaro,
for that very kind introduction.
It's really a pleasure for
me to be here again today.
I last spoke at Google
in November of 2013.
And I remember many of
the faces from that talk.
So it's especially a
pleasure, actually,
to be speaking here about Lick
Observatory and the research
we're doing there, because,
as I'll mention more
near the end of my talk, Google,
through Google Making Science,
is now a partner with us, a
supporter of Lick Observatory
through a generous gift.
And we're actually
doing a number of things
together in order to
increase public understanding
of science, and
astronomy in particular.
So thank you so much, Google.
It's been a great beginning.
And we look forward to a
really wonderful partnership.
And this is really
the boost we needed.
And I'll talk about that
more near the very end.
So the Lick Observatory
is owned and operated
by the University of California.
You can see it from here,
actually, from Silicon Valley.
It's those little
white mushrooms
at the top of Mount
Hamilton, California.
If you go up there,
you notice that it's
a very, very long, windy road--
19 miles following the contours
of the mountain, very windy.
Not very steep because
things were brought up
by horse and carriage
more than 120 years ago.
And so it's a favorite
among bicyclists.
And I know many Googlers
love to ride their bicycles.
And I've met Googlers
up in the parking
lot at Lick Observatory.
So there they are.
Just if you do this,
be very careful
of all the crazy car drivers
on Mount Hamilton Road, OK?
But anyway, it's just
not a very steep road
because everything was brought
up by horse and carriage
So here's a photo from 1900.
In 1888, when the
observatory was completed,
it was the world's first remote
mountain top observatory.
Prior to that
time, observatories
were on university campuses that
tended to be in large cities
at or near sea level.
But this was a
very remote place.
And it was arguably the birth
of big science in the whole US,
but certainly in the Western US.
And it was made possible
by a generous donation
from James Lick.
James Lick has a very
interesting history.
I don't have time to
go into most of it.
But suffice it to say that he
came to San Francisco, which
was then Yerba Buena, at the
beginning of January, 1848,
when it was a little shanty
town of perhaps 1,000 people.
He already had
considerable wealth.
And he had the good
fortune of arriving
17 days before gold was
discovered at Sutter's Mill.
He tried himself looking for
gold for three or four days
and then realized that this
is just not the way to go.
He wants to deal
with real estate,
but not with the
dirt in his fingers.
So what he did is
he bought up land
that people were selling in
order to go and hunt for gold.
And then he sold it back to them
after they started coming back.
And of course, the Gold Rush
brought lots and lots of people
into California.
So within three
years, San Francisco
was a booming city
of 20,000 or 30,000.
And Lick basically owned
a good fraction of it,
as well as good fractions of the
rest of California-- Catalina
Island, parts of Napa
Valley, and places like that.
So he made a very large amount
of money, very, very large.
Near the end of
his life, he wanted
to use that money to
commemorate his parents,
the memory of his parents.
And so he was thinking maybe
of having statues erected
of his parents on Ocean
Beach facing the Pacific
Ocean until it was pointed
out to him that if we are ever
attacked from the west, these
would be the first structures
to come down, so that's
not such a good idea.
So then Lick thought,
well, how about a pyramid
at the corner of Fourth and
Market Streets in San Francisco
to commemorate himself
and his parents?
But you know, he was told that,
look, pyramids are no big deal.
There are pyramids in
Egypt, Mexico, Central
America, all over the place.
So why not do something
really useful and new?
And a friend of his
was George Davidson,
who was President of the
California Academy of Sciences.
And he suggested that James
Lick build a telescope.
So in 1875, James
Lick donated $700,000
to the building of
the world's greatest,
most powerful telescope.
And as a fraction
of the GDP, that's
equivalent to about $1.2 billion
today, the largest gift ever,
certainly, in the
physical sciences.
So it was amazing.
And a 36-inch
refractor was built.
And James Lick is
buried at its base
down underneath the floor there.
And there you can
see the plaque,
"Here lies the body
of James Lick."
Well, that was 1888.
At age 127, you might think,
what good is Lick these days?
But what I want
to show you today
is that it is doing cutting
edge research, technology
development, student
training, and public outreach.
And for all these reasons, it's
really an incredible place.
And we don't just have the
1888 great refractor anymore.
We have other telescopes that
have been built since then,
the most recent of which
is now only two years old,
the Automated Planet Finder.
All of these telescopes are
small by today's standards.
I'm privileged to be a
user of the mighty Keck
telescopes in Hawaii.
I love them.
They're 10 meters in diameter.
I use them to study very, very
faint, distant, exploding stars
and galaxies.
But the time is
so precious and it
is needed by so many
astronomers that you just
can't do certain
types of projects
that I'll be describing here.
We're planning to build
a 30-meter telescope
if all goes well.
And there have been some
issues, as you may have
heard in the news recently.
But hopefully, the 30-meter
telescope will be built.
And that will be fantastic, too.
We'll use it to study the
faintest, most distant objects
in the universe.
But time will be
very, very precious--
for UC astronomers, maybe
40 nights a year in total.
So there are certain
types of research
that you simply can't do with
the Hubble and the 30-meter
and the Kecks.
But you can do them
with smaller telescopes,
like at Lick, to which
you have repeated access.
So that's what I want to
describe to you today.
I'll start with supernovae.
I have always liked
things that blow up,
as long as they're
used safely and stuff.
You know, I'm not some
terrorist or something.
But our sun will not blow
up at the end of its life.
It will die a
relatively slow death.
It'll become brighter than
it is now, But in a slow way.
But some stars become
much, much brighter very,
very quickly because
they literally explode.
This is a titanic,
colossal explosion
that can make the star
up to several billion
times the brightness of
our sun, or the luminosity,
the true power.
So here is one star in this
galaxy of 100 billion stars.
And at its peak, it's about as
bright as the central billion
stars in this galaxy.
So if our sun were to do
this-- and don't worry,
it won't-- then sun block of
50 just wouldn't cut it, folks.
You'd need sun block,
or supernova block,
of a few billion to
protect yourself.
But don't worry, be happy-- our
sun is not going to do this.
When stars do do this, they're
not only exciting to watch,
but they are of fundamental
importance to us,
because they generate
and spew out into space
the heavy elements that are so
necessary for life on Earth.
So during the normal nuclear
reactions in a star, carbon
and oxygen are built up
eventually-- right now
our sun is forming
helium-- but those elements
have no way to get out.
The supernova releases them
and, during the explosion,
creates additional
heavy elements.
And we can look at supernova
remnants, like this one,
and see that the gases are
enriched in heavy elements that
simply weren't there in
any significant abundance
at the time the star was born.
The supernova remnants
spread out like this
and then meet up with
other clouds of gas,
eventually forming giant,
gravitationally-bound clouds,
like the Orion Nebula, in
the center of which you
can see lots of newly-formed,
or in some cases
still-forming, stars.
And because this gas has gone
through many, many generations
of stellar birth and death
and chemical enrichment,
these gases are
now significantly
enriched in heavy elements.
And so you can get
gas and dust disks
around newly-formed stars,
which then coagulate
into planets, some of which will
be rocky, Earth-like planets.
And this is how our
own solar system
was born 4 and 1/2 billion
years ago from gases
that had gone through many,
many generations of enrichment
of this sort.
And somehow, somewhere-- I'll
leave this to the biologists--
lifeforms-- and it evolves.
I'm skipping a few steps here.
And it ends up-- oops.
One of the pictures
somehow got hidden.
But there's part of my DNA.
It ends up with people who are
sentient beings that can sit
and look out into the cosmos.
And my kids just attended the
Maker's Faire a short time ago
and were particularly
thrilled by the Google booth,
where they made
rockets and stuff.
So they're going to sign up
for a Maker's Camp this summer.
So anyway, we are
made of star stuff.
So we would like to
understand the process
by which this occurs.
So we'd like to find
nearby supernovae,
but they're pretty rare.
So if you look at
some galaxies, you're
unlikely to find supernovae,
because they only go off
once every 30 or 40 years.
And that would be pretty boring
looking through a telescope
in search of supernovae by eye.
Fortunately, with
modern technology,
we have a better technique.
You attach CCD cameras to the
eyepiece end of a telescope,
take photographs of
thousands of galaxies,
and simply look for arrows.
And where you see arrows,
you see exploding stars.
You see it happened once,
twice, three times, four times,
five times.
By rigorous
mathematical induction,
I conclude that this
process works every time.
Well, it doesn't.
You have to program
telescopes and computers
to do this and software that
will look for the new objects.
And so what we have
at Lick Observatory
is a telescope
that's by no means
large by today's standards.
It's only 3/4 of a
meter in diameter.
But it's been
programmed expertly
by my associate Weidong
Li to look at, literally,
thousands of galaxies each week
and to compare the new pictures
with the old pictures.
And usually, there is nothing
new in the new picture.
But occasionally, you'll notice
something new, this star here.
I mean, the arrow is new, too.
But that was put in with
Photoshop or something.
So there is a
thing that might be
a supernova candidate-- or,
it is a supernova candidate.
It might be a supernova.
But it could be something else.
It could be an asteroid flying
through the field of view,
perhaps with Earth's
name written on it.
Someday, astronomers
will save humanity
because they'll
find the asteroids
and then applied physicists
and engineers will figure out
how to deflect them.
But anyway, one person's garbage
is another person's gold.
I don't want the asteroids.
I don't want the cosmic rays,
which are charged particles
that interact with the CCD.
I want the supernovae.
So out of a couple of dozen
candidates each night,
maybe one of them will be
a supernova, maybe none.
And there, I used students who,
with their superb eye-brain
combination, look
at the candidates
and determine which ones are
likely to be genuine supernovae
worthy of further study.
And these students,
often starting
in their freshman year,
even, get so excited when
they find a supernova.
And they write home
to Mom about it.
And then they analyze the data.
And they get trained in lots
of science data analysis, error
propagation,
statistical techniques.
Most don't go on to become
professors of astrophysics
at universities.
Most go on and become more
immediately useful to society
as engineers, applied
physicists, medical physicists,
computer scientists,
people like that.
But they get that early
exposure to research
through groups such as mine
at Berkeley and the UC system
throughout.
But my point here--
and this is the mantra
throughout the whole talk-- is
that for this kind of research,
just having a few nights per
year on the biggest telescopes
does you no good whatsoever.
You need huge amounts of
time, months or years,
on small or
modest-sized telescopes.
Once we or others--
I'm not saying we're
the only ones who
find supernovae--
but once we or others
find a supernova,
we'd like to study
that supernova.
We collect more light
with a bigger telescope,
like the 3-meter
telescope at Lick.
And then we're able to spread
the light out into a spectrum,
plot the intensity
versus the wavelength.
And when you do this
for enough supernovae,
you find that they come in
several well-defined groups--
the Type I's that don't have
hydrogen and the Type II's that
do.
But here, you can see calcium,
oxygen, silicon, sulfur, iron,
magnesium, the elements
that were generated
during the star's life and
during its explosion, elements
that are necessary for
Earth and for life on Earth.
So there are other
types, as well.
But we study them
in some detail.
And getting one
spectrum isn't enough,
because you're
then just sampling
the chemical elements that
are on the outside parts
of the star.
But as the exploding
star expands,
the gases thin out and
become transparent.
And you see down into
deeper and deeper layers.
So by getting a series
of spectra over time--
from 12 days before peak
brightness, in this case,
to several months
after peak brightness--
you can get, essentially, a CAT
scan of this exploding star,
because you see the
different layers up
to where it's transparent down
to where it becomes opaque.
And that boundary moves
farther and farther in.
So at early times, you see
things like calcium and silicon
and stuff.
And at late times, you see iron.
And so, in fact, that
shows that the iron
is produced in the
explosion close
to the center of
the exploding star.
And students are involved
in the spectroscopy
as well as in the discovery
of the supernovae.
They also get the light
curves of the supernovae,
the brightness versus time.
And again, this
tells us something
about the physics of what's
going on in these two
main types, the Ia's Type IIs.
And we do this, again,
with just a small telescope
because these are bright,
nearby exploding stars.
What we need is lots
and lots of time
on a small telescope,
not a little bit of time
on the biggest telescopes.
And students are
involved throughout,
more so now than ever
before, because we now
have these remote
observing stations set up
at each of the UC campuses,
where students can essentially
talk to the telescope
operator-- or run
the telescope themselves,
in this case-- get the data,
analyze the data.
It's as though they're
up on the summit.
But they're not
up at the summit.
That's great, because students
are busy with courses.
And generally, they
don't have cars.
And it's a four-hour round trip
from Berkeley or Santa Cruz,
not even to mention UCLA,
San Diego, Riverside, Irvine.
Those are all much more distant.
So students are now involved
more than ever in real research
because of the remote
facilities set up
at the different campuses.
I then have a group lunch once
a week-- my group lunch will
be tomorrow--
where I bring pizza
and they justify their
existence for the previous week.
They'll do anything,
undergraduates and grad
students and postdocs,
for free food.
And we just discuss
all of our projects.
And everyone helps each other.
It's a really
groupthink-type experience.
It's wonderful.
But again, to get
spectra and light curves,
you need lots and lots of time.
That's the mantra.
And someone who was very
inspired by the work we
did in setting up the Katzman
telescope and the success
we achieved with it was,
in fact, Wayne Rosing,
who left Google some years
ago and has started up
this gigantic thing called the
Las Cumbres Observatory Global
Telescope Network.
He and his team in Santa
Barbara have set up
telescopes of this sort
modeled after our telescope
at Lick throughout the world.
And their motto is, "The
sun never rises on LCOGT."
In other words,
at some longitude,
there's always a telescope
where the sun is down.
So that's fantastic.
I want to tell you one
application of the Type Ia
supernovae.
And this was the subject of
my talk back in November.
So if you want to
hear more details,
you can go online
and watch that talk.
But the point is that the
universe is expanding.
We've known that ever
since Hubble's work, which
showed that the
light from galaxies
is shifted toward longer
wavelengths, redder
wavelengths.
And the greater the distance,
the greater is this redshift.
And we now know
that this is because
of an expansion of space itself.
Hubble himself resisted
that interpretation back
in the late 1920s
and early 1930s.
But we now know
that it's the case.
And so you look at all these
galaxies, and you wonder, well,
will they keep on expanding
away from each other forever?
Or will they someday return
back into a denser structure?
And if the density
is big enough--
the density of the
universe, visible matter
and dark matter--
then everything
will pull in everything else
so much that, eventually,
the expansion will stop.
And then it will reverse itself.
And the universe will implode.
So Big Bang, Big Crunch.
Or you could say, Big
Bang, "gnab, gib,"
which is Big Bang backwards.
And so if you were
in this universe
and lying on your back
looking at the galaxies,
they would look progressively
fainter and smaller.
And you would say, yes, I
live in a good universe.
And then you'd notice
something a bit peculiar.
And right around now, you'd
start getting a little nervous.
And then, you know,
goodbye, cruel world,
because the universe
would collapse in on you.
All right.
On the other hand,
you might live
in a sufficiently
low-density universe
that the expansion,
though slowing down
with time because of
gravity, never quite
comes to a complete stop.
And that's, of course,
like launching something
at a speed greater than
Earth's escape speed.
In that case, the
galaxies would continue
to get fainter and smaller
in the sky forever,
albeit at a progressively
decreasing rate, because there
is some gravity
acting upon them.
Well, we would like to know
which kind of a universe
we live in, all right?
And so here's the scale
factor, the distance
between two clusters of
galaxies versus time.
Here's the universe
that expands for a while
and then undergoes a Big Crunch.
Here's an empty universe.
It expands forever
at the same rate
because there is no gravity.
Clearly, we're somewhere
in between because it's not
an empty universe.
Here's sort of a
medium-density universe.
This is one that expands
forever, but just barely.
And most measurements of
the density of the universe
suggested back in
the early 1990s
that we live in a universe
that has about 30%
of the critical density.
That is, it's a universe that
will expand forever easily,
not just barely.
But it would be interesting to
see whether this is actually
supported by a measurement
of the past history
of the universe.
In other words,
which of these curves
has the universe been following?
Then we could predict what
it will do in the past.
So we want to measure the
expansion history to determine
the fate of the universe.
It's a little bit like
measuring the speed of the apple
at many, many times.
Seeing how much it's
slowing down from that,
you can calculate whether
it'll speed up or not.
So let's look at the left part
of this diagram more closely.
The definition of the redshift
is that 1 plus the redshift
is simply the scale
factor of the universe--
the distance
between two clusters
of galaxies now-- divided
by what it was back
when the light was emitted.
So redshift 0--
well, 1 plus 0 is 1.
Even a non-Googler
understands that.
And so this ratio is 1.
Redshift 1-- well, that
means that the light
was emitted when the universe
was essentially half its size.
So let's draw a line
now, redshift 0.
And let's go to redshift 1.
At that time, the universe
was half its size.
You can see that, depending
on the past history
of the universe,
redshift 1 corresponds
to different lookback times,
and hence different distances,
because light travels
through the universe
at the speed of light.
The lookback time, and
hence the distance,
of a redshift 1 object is
smallest for a dense universe,
bigger for a less
dense, medium universe,
bigger still for a
low-density universe,
bigger still for
an empty universe.
So the functional form between
the redshift and the distance
is what ends up being a measure
of what kind of a universe
we live in.
You want to measure
that functional
form between the lookback time
or distance and the redshift.
The theoretical models give
you a different functional form
depending on what
universe you live in.
And of course, all these
curves meet right here.
Now two clusters have
whatever separation
they have, and they're
expanding at whatever
the current expansion rate is.
That's the slope.
So all these curves
have to meet now.
But they diverge as
you go back in time.
And that's what this
graph is showing.
That's the theoretical view.
Here's the observational view.
If you measure redshift and
distance and plot the points--
this part is what Hubble found.
You go out to big
enough redshifts,
you should see which
of these curves
the universe has been following.
And that will tell you
the cosmological model
that applies to our universe.
So redshifts are
easy to measure.
Just get a spectrum
and see how much
the lines have been shifted.
Here's 0.
Here, by 10%.
So that galaxy is
moving away from us
at 30,000 kilometers per second.
So that's easy.
Redshifts are easy.
Distances are a bit harder.
The way we do it
is the same way you
judge the distance of an
oncoming car at night.
You look at the relative
brightnesses of the headlights
and you use the inverse
square law in your mind.
Well, for galaxies that are
sufficiently distant to apply
this test, you're not going
to see individual stars,
because these galaxies are
billions of light years away.
So you're not going to see
a sun-like star or even
a fairly bright star, like
a Cepheid variable, which
is what Edwin Hubble used
to get the low redshift
end of the Hubble diagram.
But supernovae, in
fact, are bright enough
to be seen at distances of
billions of light years.
That's the key.
So you can measure nearby ones
in galaxies whose distance you
already know through
some other technique,
like measuring
Cepheid variables.
And then you find one in
some pathetic little galaxy,
like this.
There it is.
You subtract one epoch from
another, and you find it.
And you can take
measurements of it
and do the inverse square law
and figure out the distance,
and hence the lookback time.
So that's the idea.
And this is best done with
the subclass called Type Ia's.
These are quite standard
in how powerful they are.
And that's because they
come from a weird type
of a star called a white dwarf.
Our own sun will turn
into a white dwarf
in about 7 billion
years, at which time
it will be about the
size of the Earth.
And it won't explode.
It'll just sort of
sit there, because it
doesn't have a companion.
But those that have a
sufficiently nearby companion
can steal material from that
companion, grow in mass,
and eventually reach an
unstable limit, at which point
they explode.
And that unstable limit
should be the same each time.
And so they should explode in
exactly the same way each time
and reach the same
peak luminosity.
That's true to first order.
But when you look
more carefully,
such as the work that my
team did in the early 1990s,
you find that there are,
in fact, differences
among the Type Ia supernovae.
Even though they are all
approximately the same,
when you look carefully,
there are differences.
And here's spectra
of three supernovae
that I studied in
the early 1990s.
You can see that there are
spectroscopic differences
among them.
There are differences
in various places.
This big absorption
trough here is not that--
And in fact, measurements
of their peak brightness
shows that they are
different, as well.
So we were sort of stuck for
a while in the early 1990s
until Mark Phillips and Mario
Hamuy developed a relationship.
They found, by
looking at supernovae
that are bright and nearby in
galaxies of known distance,
that the intrinsically
more luminous ones
decline more rapidly than
the less luminous ones.
And we now know that they
rise more-- I'm sorry,
decline more slowly is
what I meant to say.
The luminous ones
decline more slowly
than the less luminous ones.
And we now know that they
rise more slowly, as well.
So once you've determined
this relationship
by using Type Ia supernovae
in galaxies of known distance,
you can then apply it
to the distant ones,
measure their light
curves, and figure out
whether this is a
normal luminosity
one, an over luminous one,
or a sub-luminous one.
So instead of saying, these
are all 100-watt light bulbs,
plus or minus 50 watts-- by
the way, they are much more
luminous, of course--
you could say,
this one is 116,
plus or minus 20,
and, this one is 94,
plus or minus 12,
or something like that.
You can know where
in the distribution
that particular
supernova comes from.
And that is what
makes these things
such great
standardizable candles.
Sometimes astronomers call
them standard candles.
But I don't like that term.
Standardizable is better.
So we find these things.
My job on both teams
that did this work was
to get spectra of them,
to get the redshifts
and to make sure they
were Type Ia supernovae.
I used the Keck
telescopes for that work.
And here's then the diagram
of the possibilities.
And here is what we
found, this green curve.
OK.
Oops, none of the above,
folks, the answer that's
so attempting on
multiple choice exams.
That's where the data fell.
And if this is sort of a dense
universe-- 1, greater than 1,
1.3, 0-- it doesn't
take a genius
to realize that
this curve formally
corresponds to a density
less than 0 for the universe.
But that just doesn't
make any sense whatsoever,
unless the other
parts of the universe
are made out of some wacky
stuff with negative mass.
But we have no
indication whatsoever
that that's the case.
Fortunately, there
is an alternative.
There is what's
called Einstein's
cosmological constant, which
now is just one subset of a more
general class of theories
called dark energy theories,
stuff that has a
positive energy density
and actually has some
gravitational attraction
associated with it,
but it has what's
called a negative pressure.
And the negative
pressure is what
can accelerate the
expansion of the universe.
So by the end of
'98, no one had found
any flaws in what we had done.
And so this was deemed by the
editors of "Science Magazine"
as the single greatest
breakthrough in all areas
of science that year.
And so we were, obviously,
very pleased by that.
And Einstein is
surprised here not
because there are
multiple universes--
though, there might be.
Though, they don't
come from pipes
of theoretical physicists.
He's surprised because
this one universe
is expanding at an
accelerating rate, rather
than a decelerating rate.
That's the bottom
line, is the data
imply acceleration,
rather than deceleration.
And that's just really weird.
And when you combine the
supernova measurements
with measurements of the
cosmic microwave background
radiation and other data,
then you figure out,
basically, that the
dark energy that
is causing this repulsion,
whatever it is--
and we don't know what
the dark energy is.
It might be a property
of space itself,
the cosmological
constant, or it could be
some new kind of energy field.
But whatever it is, it
actually constitutes
70% of the total
contents of the universe.
And we don't know what it is.
And most of the
rest is dark matter
that holds galaxies and
clusters of galaxies together.
But we can't see it.
And we don't know, really,
what that is, either.
Although, it's probably
little, tiny particles
left over from the Big Bang.
But we're not sure.
And the ordinary stuff, out
of which you and I and Google
are made, is only 5%.
And the easily visible stuff
is only half a percent.
So if you're talking about
science to youngsters
and someone says to you, well,
they heard from their uncle
or something that
there's nothing left
to be done in physics,
you tell that youngster,
what about the origin and
nature of 95% of the universe?
Pretty exciting stuff.
And when I was a
student, we didn't even
know that these parts
of the pie existed.
The whole pie was
ordinary matter.
And that consists of 92
naturally-occurring elements.
OK.
So anyway, this was all
confirmed in the subsequent 13
years after 1998, at which
point the discovery was honored
with a Nobel Prize in Physics.
And given the rules, it went
to the team leaders, Sal
Perlmutter at
Berkeley, Brian Schmidt
at the Australian
National University--
and I'm pleased to say that
the Nobel Committee did
the right thing-- they gave
my post doctoral scholar, who
was working with
me and with Brian,
but directly under my mentorship
at Berkeley at the time
that he made the
measurements-- He's
the first on Schmidt's
team to realize
what the data were telling us.
These three gentlemen knew that
without the rest of us working
in the trenches, they wouldn't
have been honored in this way.
So they spent a good
fraction of their prize
money flying the rest of us
out to celebrate Nobel Week.
Here's right after the
awarding of the Nobel Prize
to Schmidt and Riess.
And here's the Supernova
Cosmology Project team.
I happen not to be
in this picture,
because their group picture
was taken right at the time
that the high redshift
team, Schmidt's
team, my primary
affiliation, was
having its celebratory lunch.
And at that lunch, Noelle,
my wife, who is here,
revealed a t-shirt
that she made--
"Dark energy is the new black."
And that was our
consolation prize
for not winning the
Nobel Prize itself,
but for having done the work.
And that was really the thrill,
is just having done the work.
And never in my
wildest dreams as a kid
did I think that I
would be associated
with such a discovery.
And so that's been
the real reward.
It's just been the fun and
working with people and stuff.
Nevertheless, it is
nice to get some credit.
And as Alvaro said,
more recently,
the 2015 Breakthrough Prize
in Fundamental Physics
specifically by name recognized
all of the participants, all 51
of them.
And so that's really good.
So there we go.
Yeah.
[LAUGHTER]
So anyway, specifically,
the Lick contributions
were in the early 1990s showing
the spectroscopic diversity
of Type Ia supernovae.
And then in the years
following the building
of the Katzman
telescope in 1998,
getting lots and lots of
light curves and stuff
and verifying this,
admittedly, not yet
well-verified discovery
that we announced in 1998.
At some point, you've
just got to be brave.
And if you think
you've done your work,
you have to announce
a discovery,
even though you're not
sure that you're right yet.
But the confirmation
of this light curve
shape versus luminosity
relationship with the Katzman
telescope, so that
was something we did.
Next big topic-- and one that I
personally don't work on, just
to show you that I'm really
being fair and egalitarian here
and stuff-- exoplanets, really
a hot field in astrophysics
these days.
Basically, are there
other planetary systems?
Are any of them like
our own solar system?
Well, the way to
detect exoplanets
is not so much to see
their reflected light--
because they're so dim
they're lost in the glare--
but rather to see the
effect they have on the star
that they orbit,
or, more correctly,
the two orbit their
common center of mass.
So when the planet is
going away from us,
the star will be
going toward us.
And the light will
be blueshifted--
by the way, not
instantaneously, of course.
But the blueshifted part will
travel at the speed of light
toward us.
That's a bit of a subtlety here.
But anyway, no big deal.
And when the planet
is going toward us,
the star will be
going away from us.
And so you'll see these
periodic Doppler shifts.
And you have to spread out
the spectrum a heck of a lot.
So it's a high
dispersion spectrograph.
And let's zoom in
on it and see what's
happening to these
absorption lines.
So here's a little
magnifying glass.
And we're going to look at
the absorption lines produced
by the chemical elements in
the atmosphere of the star.
They shift back and forth.
And you can measure
the changing flux
levels in these little pixels.
And the shifts are typically
1/1,000 of a pixel.
So we've exaggerated
the effect a lot here.
But there are thousands
of absorption lines.
If you use cross-correlation
techniques and stuff,
you can measure speeds
that are basically walking
speed, meters per second.
It's unbelievable.
They're now down to
a meter per second.
But you need huge
amounts of time,
or on modest-size telescopes
to get enough data, right?
Measuring the star once or twice
is just not going to do it.
So here in the early 1990s,
Geoff Marcy and Paul Butler
using the Lick 3-meter telescope
made some measurements.
They noticed that the star
wasn't standing still.
And here's a periodic
function fit through it.
But they said, well, let's start
taking data more frequently,
and then really frequently.
And you can see that there is
sort of a 0.7-year variability
here in the velocity and
also a 4-year variability.
And a 4.6-day variability
has been removed from this
presentation of the data.
So Epsilon Andromedae has this
three-planet system where there
is this 4-Jupiter-mass planet
way out here with a 4-year
period-- the 4s
are coincidental--
the 2-Jupiter-mass planet
with a period of 0.7 years,
and then this little guy
here, which is actually not
so little, half a Jupiter mass
or so, with a 4.6-day orbital
period.
This is the beginning of
a very exciting new class
of planets called hot Jupiters.
This thing basically
has the mass of Jupiter,
yet it's orbiting the star
with an orbital period
of just a few days.
It shouldn't have formed there.
Jupiter is a big,
gaseous, liquid thing.
Probably, it formed farther
out and then migrated in
through friction
with the accretion
with the protoplanetary
disk or something.
But here's an artist's
impression of it.
It may even be evaporating away.
We have evidence of ones
that are evaporating away.
Obviously, we don't
have any pictures
that are quite like this.
But if anyone wants to
help build a telescope,
if that's-- Anyway--
[LAUGHTER]
So anyway, you might
wonder, how do you
get actual parameters like the
orbital distance and the mass?
So here's 51 Pegasi,
the one that was first
found by a team of
Swiss astronomers
and then quickly verified
by Marcy and Butler.
Again, a 4.23-day
period in this case.
Well, the period is
4.23 days for 51 Pegasi
b, this little exoplanet.
Kepler's law is that
the square of the period
is proportional to the
cube of the distance,
and you have to divide
by the mass of the star.
Oh, and by the way, the
constant of proportionality
is 1 when you use
these particular units.
You know the mass of the
star from its classification.
We know stars
pretty well by now.
So you can solve for
R. And in this case,
it's 1/20 of Earth's orbital
distance from the sun.
So this guy is just
screaming around this star
with a mass of 0.45
Jupiter's divided by sine i.
And the factor of the sign
of the inclination angle
is that you don't know what
the orbital inclination is
to your line of sight.
The really nice ones are the
ones that are 90 degrees.
They're transiting
the Kepler satellite.
Found some of those.
There, you know that
the angle is 90 degrees.
So sine of i is 1.
But where you don't
know, you're only
seeing in the Doppler
effect, that component
of the total velocity,
which is radial.
You don't see the
transverse part.
And that's why you get only
a lower limit for the mass.
OK.
So let's get the mass
now knowing the distance.
So there we go.
Conservation of
momentum-- M star V star
is M planet V planet.
The overall system is
just sitting there.
Solve for the mass
of the planet.
There we go.
You know the mass of the
star from its classification.
You get the speed of the star
from the maximum Doppler shift,
55 meters per
second in this case.
What is the speed of the planet?
Well, I'll just do it
for circular orbits here.
Circumference--
that total distance
is the speed times the period.
OK.
And so you can solve for
the speed of the planet.
And you know R. I just did
that on the previous slide.
So the mass of the planet
in this case is about half
a Jupiter mass.
So that's how you do it.
For elliptical orbits, it's a
little bit more complicated.
So the other big surprise
early on in the game
was that instead of just having
nearly circular, only slightly
eccentric orbits, as
in our solar system,
a whole bunch of exoplanets
were found with these highly
eccentric orbits.
And the signature
of such an orbit
is where you have a
periodic velocity curve,
but it is not sinusoidal.
OK.
So this is clearly periodic.
But what's happening
is the star's speed
reverses very, very quickly.
And that's, of course,
when the planet
goes zipping around the star.
The star's speed reverses very
quickly at that moment, too,
because it goes
[VOCALIZING    ENGINE].
And that's Kepler's
second law, of course.
So anyway, who among
you were students
in my Astro 10 class at Cal?
I know several of you were.
OK, so I'm going to quiz
you on this afterwards.
You'd better remember.
Otherwise, you'll
fail the class.
And your job at Google
will have been revoked.
OK.
So the big thing in the
early days-- and it's still
interesting that more of
these things are being found--
are lots of hot Jupiters and
lots of these eccentric ones.
Of course, more normal
ones have been found.
And the Kepler satellite
has been wonderful recently
at finding transiting ones.
But in the early days,
especially Paul Butler
and Geoff Marcy-- Marcy's
a professor at Berkeley--
were the undisputed
leaders in this field.
They found 70 of the first
100 known exoplanets.
And they did it with the
Lick 3-meter telescope.
And that's still a
relevant telescope.
And they still are
among the leaders.
But back then, they found
most of these things.
And in the early
'90s-- well, mid
'90s, in this case-- when
two planets were found,
it made the cover
of "Time Magazine."
You know, "Dole
Drops, Clinton Rises."
Well, half of this might be
relevant for the next year
and a half or so.
But anyway, "Is
Anybody Out There?--
How the Discovery of
Two Planets Brings Us
Closer to Solving the
Most Profound Mystery
in the Cosmos."
You know, is there
life out there?
Is there intelligent life?
You might say we already
have published evidence
that there really is, of course,
because look-- "Weekly World
News," "Alien Backs
Arnold for Governor."
I don't have to tell
this crowd not to believe
everything you read, of course.
So anyway, so a lot of
those were hot Jupiters.
Here's Lynette Cook's
artist's impression
of what one of these
things looks like.
But the name of the game now
is we want to find Earths.
And we want to find Earths in
the habitable or potentially
habitable zone, where
liquid water might exist
on the surface of the planet.
So for that, you need
really huge amounts
of time on modest-size
telescopes,
because though
Jupiter would produce
a signal of about 10
meters per second--
if an alien were looking at
the sun, they would see the sun
moving around at a speed
of 10 meters per second
because of Jupiter.
The reflex motion
caused by Earth
is 10 centimeters per second.
So that's the motion of
the sun induced by Earth.
So you really need a
lot of telescope time
to dig the signal
out of the noise.
And so Marcy said,
you, Filippenko, you're
using up too much of the 3-meter
for your studies of supernovae.
So he built himself, along
with Steve Vogt at Santa Cruz,
a 2.4-meter telescope, the
size of the Hubble, basically,
that's dedicated to
looking for planets.
And so they're looking at the
brightest stars in the sky.
Sure everyone would like
the Lick's sky to be darker,
but it's not necessary
for all types of projects.
And we live here.
And that's just the way it goes.
But for naked-eye
stars, you hardly
care about the sky brightness,
as long as the sun isn't up.
And so, you know, I'm
being a bit facetious.
But the point is you
can do this kind of work
over and over again, look
at the same stars searching
for Earth-like planets.
And here's Lauren Weiss,
one of our grad students,
running this whole
system from Berkeley.
And in fact, it's robotic.
So really, what she's doing
is looking at the data
as the data are coming in,
monitoring for quality control,
that kind of thing, because
these systems are now
largely robotic.
And the project
they're doing now
is to search for
Earth-like planets
among the nearest stars, the
roughly 100 stars that are
within about 20 light years.
Because if we can find
Earth-like exoplanets
around those stars, well, that
might be a post, a signpost,
of where to look
if we seek Yoda.
All right.
Supermassive black holes,
my next science topic.
A black hole is a
region where gravity
is so strong that nothing,
not even light, can escape.
So apples can't escape.
Rockets can't escape.
Not even light can escape.
So here is my prize-winning
photograph of a black hole.
Yeah, you can just
choose a black background
in PowerPoint, or whatever,
put your lens cap on.
"Abandon all hope,
ye who enter here!!,"
quoting from "Dante's
Inferno," of course.
They're pretty wild places.
They suck you in, and
they don't let you out.
So they're pretty ferocious.
We have a saying, what
happens in a black hole
stays in a black hole.
All right.
Well, how do you detect
them if you don't see them?
Again, by their
gravitational influence.
This is essentially
like exoplanets.
You can measure the
mass of an object.
If you measure the
distance of something
orbiting it and
the orbital speed.
In the case of exoplanets, what
we used was a period and speed.
And from that, we
got R. But as long
as you have two of
those variables,
you get the third one,
and you can get M.
Anyway, we suspected
for a long time
that big black holes might
exist within an active galaxy.
And an active galaxy
is like a normal galaxy
that has a concentration of
brightness near the center.
But in an active
galaxy, the center
is unusually bright, as though
something very energetic
is going on inside.
And you might think, why
would that be a black hole?
I just told you
that a black hole
is a region from which
light does not escape.
That's true.
But if you have a black hole,
especially if it's spinning,
and you've got an
accretion disk orbiting it,
then in the process
of falling in,
that material rubs against
neighboring material
and converts its
gravitational potential energy
and its bulk kinetic
energy into light.
And that can be a very
efficient process,
10 times more efficient than
nuclear energy, by the way.
So that might be a place
where there is a black hole,
because you need a very
efficient release of energy
from a small region in the
middle of an active galaxy.
So how do you prove that
there is a black hole there?
Well, here is the spectrum of
light from an active galaxy.
And you have several components.
Here's the continuum that
comes from this accretion
disk of material.
And then you have
these emission lines.
And the emission lines come in
two forms-- narrow and broad.
Here's some narrow ones.
They come from gas
that's relatively far
from the putative black hole.
And that gas isn't
moving very quickly.
But there's also these
broad Balmer lines
of hydrogen, which
come from gas that's
moving with speeds of
thousands of kilometers
per second very near
the putative black hole.
Well, so here's
sort of an anatomy
of an active galactic nucleus.
There is the black hole.
There is the accretion disk that
emits the continuum radiation.
Here is this broad line
region where clouds of gas
are moving around very quickly,
producing those broad lines,
because some gas
is Doppler-shifted
because it's moving toward you.
Some of it is
Doppler-redshifted because it's
moving away from you.
That's what gives the breadth.
So if you can measure the
motions of these clouds
and if there is some
way to determine
their distance from the
center, well, that's
a speed and a distance.
That's what you need
to get the mass.
Remember from that thing
that I just showed.
All right.
So well, the width
of the broad line--
here is hydrogen
data-- tells you
something about the aggregate
orbital speeds of the clouds
in this broad line region.
And if you measure how far these
clouds are from the black hole,
then you've got what you
need to solve for the mass.
Well, how do we do that?
We use a technique
called echo mapping.
Here's a nebula.
This is called a
planetary nebula.
It has nothing to
do with planets.
But our own sun will do this
in about 5 or 6 billion years,
when it becomes a red
giant and the outer parts
of its atmosphere will
be only loosely held.
So the point is there
is a hot star here.
And if you've got
ultraviolet radiation coming
from that hot star
or some other source,
then it will ionize
the clouds of gas.
And if you have an increase
in the UV brightness
of this source, that will lead
to an increase in the emission
line brightness of the
surrounding ionized gas.
But if you're over
here somewhere,
it will have taken
time for light
to travel to the back side
and produce emission lines
and then to reach you.
Whereas from the front side,
the continuum variation
and the emission
line variation will
be essentially simultaneous.
So the observer will
see a time delay
between changes
in the brightness
of the central source
and the brightness
of the overall nebula.
Different parts will
brighten at different times.
But if they're
spatially unresolved,
it just means there
will be an overall delay
in the brightening
of this nebula.
So if we look at, say, a
step function continuum
variation of the
active nucleus, it
might look
intrinsically like this.
But the emission
line light curve
will start brightening
at the time
that the continuum brightened
because the emission line
clouds that are along
the line of sight
to the continuum source suffer
essentially no time delay.
But there will be a
progressively bigger and bigger
time delay for all
these clouds here.
And so the overall thing will
have this kind of a shape.
And that's how you get a measure
of the size of the system.
So we measure the
continuum light curves
with a telescope
like KAIT, where
you can get many,
many measurements
over the course of time.
We measure the
emission line light
curves using a bigger
telescope, because you
have to spread the light
out into a spectrum
and measure the
individual emission lines.
But the point is you need
huge amounts of time, right?
You're not going
to do this with one
or two measurements on the
world's biggest telescopes.
This should be firmly affixed
to your brain at this point
through your retina.
And again, students and
postdocs are doing all this work
remotely from the UC campuses.
It's really great.
So what we've found for a
bunch of studies of galaxies--
and this overall study is led
by Aaron Barth of UC Irvine,
who is a former PhD student
of mine-- is we indeed
find evidence, as have
other astronomers-- again,
none of what I'm saying
is unique to our group.
But what we found
is there really
are big black holes in the
centers of these galaxies,
as shown by these data
that we've gathered.
And so this theoretical picture
that was proposed 50 years ago
appears to be correct.
And Einstein never thought
that black holes actually
occur in nature.
He was aware that they are a
possible theoretical prediction
consistent with his general
theory of relativity.
But he didn't think
that nature has
any way of making black holes.
Well, imagine what his reaction
would be if he were alive now
and could see the evidence
that we and others have
found for black holes.
I mean, his reaction might
be something like this.
Finally, technology development.
There, we do lots of things.
We make and test new equipment
on smaller telescopes,
where the time
isn't so precious.
And then we move it over
to other telescopes.
And the one application
I want to focus on,
given limited time, is laser
guide star adaptive optics.
When you look at stars
through a telescope,
they look smeared out.
And this is related
to twinkling,
because the different
light rays are
passing through different
pockets in Earth's atmosphere,
having different
indices of refraction
because of different humidity,
temperature, density,
and so on.
And so all these little
pockets are moving around.
And that causes the star
to twinkle and to blur out.
You'd like it to look like a
point, like my laser point.
But if you look at it
hundreds of times a second,
it looks like this thing
that, averaged over time,
becomes all smeared out, smeared
into something big like this.
So we'd like it
to look like that.
Well, if you measure
the incoming wavefronts
hundreds of times per second
with a wavefront sensor
and then you send
appropriate corrections
to a small,
deformable mirror, you
can deform the
shape of the mirror
such that when the
wave front hits it,
it'll hit with exactly
the same shape.
And that will then
turn a distorted wave
into a plane-parallel
wave once again.
You can see this.
If this shape is exactly the
same as whatever wavefront
is hitting it,
then what comes out
will be a plane-parallel
wave again.
It's fantastic.
And if you do this hundreds
of times per second,
then, in fact, you can
get a nice, sharp image.
So your image will
be sharp not only
for the star that
you've corrected,
but for a small patch
of the sky next to it.
So suppose you want
to study this galaxy
and you've got, conveniently,
a bright star next to it.
You make the measurements
of this bright star,
correct it to make it look
like a point of light,
like my laser pointer,
and then the correction
will apply essentially
equally well to the galaxy.
And that fuzzy thing
will turn into that.
That's the kind of
improvement you get.
Now, full disclosure--
this is actually
a Hubble picture of that.
And it's not that galaxy.
But I couldn't find
the matching pair.
I don't know that this
particular galaxy has
been imaged in this way,
because, in principle, what I'm
telling you is absolutely
true, even though you
might be thinking, Alex just
showed us a Hubble picture
and he implied
that this was taken
with a ground-based telescope.
So full disclosure.
Well, most galaxies and
other objects in the sky
don't happen to have a bright
star conveniently located next
to them.
Maybe this one is close enough.
But all these others are not.
So what we do is we create
a fake or correction
star with a laser beam that
excites a layer of sodium atoms
about 100 kilometers up.
They're deposited there by
micrometeorites and stuff.
And that whole system was
developed and perfected
by Professor Claire Max, who
had an appointment at Livermore.
And much of this
technology was classified
until the Cold War ended.
And then she started
applying it to astronomy.
So this whole thing was
developed and perfected
at the Lick 3-meter telescope,
moved to the Keck telescopes.
And the Kecks are now the
undeniable world champions
at laser guide star
adaptive optics.
And why debug and
fix screws and stuff
on new instruments
on telescopes where
the time is really precious?
Keck time is worth
$100,000 a night, OK?
So you don't want
to do it there.
You want to do it at a place
where it doesn't cost so much.
So let me show you some results.
Io, one of the moons of
Jupiter, before adaptive optics
and after adaptive optics, the
most volcanically active body
known in the solar system.
Uranus, the seventh planet.
That is the correct
pronunciation for all those
above the age of seven or eight.
And after adaptive optics.
You can see not only the
ring, but the development
of storm systems,
which could end up
someday helping us to
understand Earth's atmosphere.
And then one of my
favorites, the center
of our galaxy in
the constellation
Sagittarius before and
after adaptive optics.
And this is work done by
Professor Andrea Gessa's group
at UCLA.
And her group and that of
Reinhard Genzel at Berkeley
and Max Planck have shown that
the central stars are zipping
around in Keplerian
orbits-- that
means they're dominated by a
single, point-like mass-- whose
location is marked
by this red cross.
And the mass within there,
using Newton's laws,
is 4 million solar masses
within a volume no larger
than that of our solar system.
And so the conservative
explanation
is that this is a black hole,
a supermassive black hole.
This is the single
best piece of evidence.
By the way, I should
get an update.
They now have a complete orbit
for this one here spanning
two decades.
And I love this one coming in.
Look at this.
Watch.
It goes, zoom!
That's a great one.
That's the one that gives the
tightest constraints, actually.
So that's really fantastic
technology development.
And then, finally-- I
lied-- public outreach,
an important aspect
of what we do
and something that Google
is very interested in.
This is the primary base
for UC astronomy education
and outreach efforts.
We have more than 20,000
visitors per year.
I mean, yeah, some
people go to Hawaii.
But usually, they're sipping
Mai Tais on the beach,
as they probably
should in Hawaii.
A few make it up to the summit
of Mauna Kea, but not many.
So we have lots of visitors.
We have a hallway with exhibits,
where various jokers describe
what they're doing,
and a summer visitor
program with lots and
lots of volunteers.
In fact, there are
volunteers even in this room.
It's a fantastic thing.
You can sign up.
During the summers,
we have nights
where you can view through
the great James Lick refractor
with this dead guy underneath
your feet-- not right
underneath your feet, but
underneath the base of the pier
here.
So just go to ucolick.org.
And these programs are
free, or for a nominal cost.
This type of work inspires
youth, sparks interest.
It's really fantastic.
We have amateurs who set up
their telescopes in the parking
lot, thus we're able to
serve even more people.
By the way, my good friend,
Mike Hanna, from grade school
is one of the volunteers at
Lick, as was-- your name?
Who introduced me?
Ar--
AUDIENCE: Here.
ALEX FILIPPENKO:
Yes, but-- Alberto?
ALVARO: Alvaro.
ALEX FILIPPENKO: Alvar--
ALVARO: Alvaro.
ALEX FILIPPENKO: Alvaro.
OK, Alvaro.
Alvaro is a volunteer,
as well, right?
ALVARO: Yes.
ALEX FILIPPENKO:
Yes, for 12 years.
Anyway, thank you, Alvaro.
Thank you, Michael.
Any other volunteers
here in the crowd?
OK Well, anyway,
it's just fantastic.
And then my good friends,
Dan Zevin and Laura Peticolas
and their associates at
the Space Sciences Lab
running what was called the
Center for Science Education.
But they've now
renamed themselves
in a much more interesting
way-- the Multiverse.
They've set up a thing with
a partnership with the UC
observatories and
Lick where they
train teachers on how data are
taken and how to analyze data.
And then those teachers
bring that knowledge
to their classroom.
It turns out teachers are
not generally taught how
data are taken and utilized.
And so now they can do this.
And they can teach
their students
and bring real data
to their classrooms
and talk to astronomers.
And so the multiplicative
factor is fantastic.
So Laura and Dan, thank
you so much for doing this.
So what I hope I've
shown you is that we
have been vital for
research for over 100 years.
We continue doing research,
especially that kind that
requires large amounts of
time on small or modest-size
telescopes.
We design new instruments
and techniques
for use at Lick and elsewhere.
And even grad
students and postdocs,
like Sloan [? Victorovich ?]
here, can design instruments.
And boy, people like
this are in hot demand.
You know, observers like
me are a dime a dozen.
And pencil-pushing theorists
are a dime a dozen.
But someone who knows
how to design and build
instruments and use them
for scientific work, that's
a dying breed, in part
because too few universities
have access to their
own private facilities
where this kind of
work can be done.
And the big telescopes--
Hubble and James Webb
and 30-meter and
places like that-- it's
just very hard for
a student to be
involved in a meaningful way.
But here, they design and
build new instruments.
And fantastic.
Hands-on training
for grad students,
undergrads, and postdocs.
And through early
exposure to research,
these people become future
leaders in many, many fields.
Again, I emphasize that
especially our undergrads,
and to some degree,
our grad students,
but especially our undergrads
mostly do not go on
to become PhD astrophysicists.
They go on in computer science,
bio physics, medical physics,
computer science, engineering,
applied physics-- future
leaders.
But they get their training as
undergrads in labs like this.
Very important point--
grad students and postdocs
can be principal investigators
on projects at Lick.
That means they are in charge.
They conceive, design, conduct,
and write up the whole project
with only occasional kibitzing
from me if they need it.
That's different from the
initial apprenticeship they do,
where they help me with a
project I've largely designed
and maybe even have
taken data for.
That's an important
part of their training.
But equally, if not more
important, is to set them loose
and let them become real
leaders in their fields
by making mistakes, by
designing and conducting
their own projects.
They can't do that at Keck
with the 30-meter, if and when
it gets built.
Public education
and outreach-- this
is a unique, historic
Bay Area treasure.
We love doing this kind of
stuff for the general public.
But a couple of years ago, the
UC Office of the President,
financially strapped,
as UC is, decided
to ramp down funding to
Lick by the summer of 2018.
That's a bad idea.
And so a bunch of us spent
some time educating them
about what it is we do
at UC Lick Observatory,
especially for students.
And if it's not in
students, then why
does the university exist?
We're not the
Princeton Institute
for Advanced Study, where
they just sit and do research.
Our mission is also to educate.
And this is where the
students get educated.
So we taught them.
And there was a
big public outcry.
And we were successful.
In October of 2014,
they recanted.
They said they were going to
provide partial funding-- only
partial because the UC
system is heavily stressed.
The economy of California
is heavily stressed.
And everyone has to do
some belt tightening.
But this was so important to
get their partial support,
OK, really very, very important.
We really turned a
big corner there.
And in December of 2014, Google,
through Google Making Science,
gave this fantastic gift of half
a million a year for two years,
I'm hoping just the beginning
of a long, long relationship.
Let's call this
the courtship time.
And we now, at
Berkeley and elsewhere,
are trying to raise funds
to match that to leverage
their big donation.
And really, there's
nothing like a stamp
of approval behind a
place like Google, right?
Others who are on
the fence or maybe
haven't heard much
about the project,
they say, oh, Google
is supporting it.
Well, it's got to be pretty
good, then, you know.
And so it's made a world of
difference, that and the UC
funding.
So we've really turned a corner.
We're not out of the
woods yet completely.
But I'm very optimistic now.
So thank you, Google, and
especially my colleagues
here at Google Making Science.
I know Chris DiBona isn't here.
But maybe he'll
watch this lecture.
Those of you who
see him, tell him
that I really am
so, so grateful.
And you might ask, well, what's
in it for Google, after all?
Well, first of all, I would
say it's two main things--
help kids get interested
in science and technology.
Astronomy is the
gateway science.
Kids love the Hubble
images and all these kind
of cosmic discoveries.
And they then learn
more about science.
And they're more likely
then to pursue careers
in science and technology
in almost all cases,
not as astrophysicists.
That's OK.
But the hook was, as
kids, what they saw.
And the long-term
future of Google
and other high tech
companies like this
depends on getting today's
kids interested in science
and technology.
And the second, of course,
at a more advanced level,
10 years later, helping students
get real research experience,
like in my research
group and stuff.
We now have Google
research scholars.
I need to discuss with you
exactly what the name should
be so as not to step
on anyone else's toes.
But these are students
who are getting
real exposure to
research and data
and data analysis and computers.
And they just get so jazzed.
And these are
valuable skills, then,
for the future in
the high-tech world.
So I would say those are
probably the two main aspects
of Google Making Science.
At least, that's what
I would think they are.
And there are probably
others, as well.
It's a great new subdivision,
or whatever you call it here.
And we're continuing to discuss
ways in which we can mutually
benefit each other and do
things that will bring science
to the general public and more
to the universities, as well.
So we spend about $2
million a year, maybe $1.5
just to keep going and another
half to $1 million to improve.
So let's just call
it $2 million a year.
Your support would
help Lick thrive.
And Google's support already is.
So as the UC Office
of the President,
you can do so in two ways.
You can become a friend of Lick
Observatory, an organization
of which I'm the
chairman of the board.
And you can make-- perhaps
more significant-- tax
deductible donations to the
UC Berkeley Lick Observatory
Operations Fund.
And online, all you need to
do is use your favorite search
engine to search
for "Give to Cal."
And then put "Lick"
in the little box
there, and it'll show
you how to do it.
And in case you need the
foundation tax ID number,
there it is.
Anyway, so that's that.
And then I have
three video courses
that happen to be available
online at 70% off.
I checked last night
from The Great Courses.
So thank you very much.
And I'll be happy
to answer questions.
[APPLAUSE]
OK, yes.
Right there.
AUDIENCE: You
showed on the slide
about the Type Ia supernovae--
ALEX FILIPPENKO: Yes.
AUDIENCE: --and how luminosity
decreases more slowly
with time for a
larger explosion.
ALEX FILIPPENKO: Yes.
AUDIENCE: And I don't
know why that is.
And I'd love to hear why.
ALEX FILIPPENKO: Yeah.
What is the physics behind the
peak luminosity decline rate
correlation in Type Ia's?
Here is the point.
It turns out that, for reasons
we don't yet fully understand,
the thermonuclear
runaway in a Type Ia
can produce different amounts of
radioactive nickel, nickel-56.
Nickel-56 is four helium
nuclei squished together.
You tend to get multiples
of helium nuclei.
Carbon is three of them.
Oxygen is four of them.
Nickel is 14 of them.
And this nickel-56
is radioactive.
It decays to cobalt-56 and then
to iron-56, which is stable.
That's what causes
the supernova to glow.
It's the decay of the nickel.
That's what causes it to glow.
But if you make more nickel,
then you heat the ejecta more.
And that changes their opacity.
It makes the ejected
gases more opaque.
So the photons that are
generated by radioactive decay
rattle around inside for a
longer time before escaping.
Now, of course, what produces
the different amounts
of nickel?
That, we're still working on.
But that's part of
what makes science fun.
Possibly slight differences
in chemical composition,
possibly slight
differences in temperature,
which would occur
as a result of white
dwarfs forming with a
different initial mass,
depending on the mass of the
star from which they formed.
AUDIENCE: My question
is, do you have
any explanation for the
formation of elliptical orbits
in exoplanets?
ALEX FILIPPENKO: Yeah.
Elliptical orbits in
exoplanets-- great question.
The prevailing theory
is that early on, there
are more big bodies
than there are now
in most planetary systems.
And early gravitational
interactions
can, in some cases,
fling one planet out.
And the other then will be left
in a highly eccentric orbit.
And this occurs after the
disk has cleared away.
And so there is no
real frictional drag
against the gas that would
circularize the orbit.
But because of this
mechanism, in part because
of so many eccentric
exoplanets we see,
we now think that there
is just a giant number
of rogue exoplanets wandering
around in the Milky Way galaxy
and in other galaxies without
orbiting a star any longer.
And some may have formed
just alone as it is.
But at the very least,
we know that some
must have been flung
out, because we
see the remaining planet with
this highly eccentric orbit.
Yeah.
AUDIENCE: Since you uncorked
the mystery of dark energy,
can you talk about, where is
the research on that going?
ALEX FILIPPENKO: Yeah.
So where is the research
on dark energy going now?
So we're approaching it
from a number of fronts.
Basically, we need to
constrain its observed effects
more in order to rule
out certain hypotheses.
And so my own group is trying
to more accurately trace
the expansion history
of the universe
and to see which of the models
is ruled out by the data.
We can never prove
that a particular model
is the only one that
uniquely represents the data.
But we can rule out ones.
And so yes, we now
know that the universe
is expanding faster than
it was 5 billion years ago.
And we have even
measured 15 years ago
the early deceleration.
So the universe for its first 9
billion years was slowing down.
And about 5 billion
years ago, dark energy
started to become more
dominant than the dark matter,
and so it started accelerating.
So decelerating,
then accelerating.
But that's two or
three broad lumps.
What was it doing 1
billion years ago?
2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12?
What was the behavior?
That kind of expansion
history, in other words--
I could go back--
but it's that curve.
We're trying to define
what that curve is.
That helps rule out
certain hypotheses.
On other fronts,
people are looking at,
for example, the
formation of what's
called large-scale structure.
Galaxies and clusters of
galaxies and superclusters
and the voids
between them all grew
as a result of tiny, little
density fluctuations that
were imprinted upon the
universe by quantum fluctuations
when the universe was a tiny
fraction of a second old.
And then they were blown into
spatially big fluctuations
by this process
called inflation.
Then the slightly
over dense regions
collected material from
their surroundings,
stealing from the
less dense regions.
Well, you can run
computer simulations
of how that occurs
with different amounts
of dark matter, dark
energy, and different forms
of this repulsion
for the dark energy
and see which of the
computer simulations
end up looking most
like the observations.
And then the other big field is
microwave background radiation.
By measuring the fluctuations
in the temperature, which
correspond to fluctuations
in the density
of the early universe, you
can set incredible constraints
on all kinds of things.
And if you want to look this
up, the Planck satellite
is the most recent
incarnation of the greatest
microwave background data.
And prior to that, WMAP-- the
Wilkinson Microwave Anisotropy
Probe-- years 1, 3,
5, 7, and 9 gave us
progressively better and
better maps and power density
spectra-- that is, the
amplitude of the fluctuations
versus their spatial scale.
That spectrum tells you
a giant amount of stuff
about how much dark matter
there is, how much dark energy,
and even what kinds of
dark energy there might be.
So those are three of the main
ways in which we're probing
what the dark energy might be.
Yes.
AUDIENCE: If we're in the sort
of expand-contract universe
that you were talking
about earlier--
ALEX FILIPPENKO: Yeah.
AUDIENCE: It would
be implicit, I guess,
that this might not be the
first time this has happened.
ALEX FILIPPENKO: Yeah.
AUDIENCE: Who knows how
many times it's happened?
This universe could have
been many times before.
But if, as it seems
more likely, we
are in one that's
ever-expanding,
does that have any
implication for, this is
the first time it's happened?
Or, who knows, it
could mean anything?
ALEX FILIPPENKO: Yeah.
Basically, I would
say still anything
goes, because we don't know
what the dark energy is.
The historical
precedent is that there
was a dark energy-like
substance, called the inflaton,
that inflated the
universe in the first 10
trillionths of a trillionth of
a trillionth of a second-- 10
to the minus 35 seconds.
That was an accelerated,
indeed an exponential phase,
of expansion of
our early universe.
It's what made the universe big.
But that dark energy,
that inflaton turned off.
We think it decayed
from a substance
with a negative
pressure-- which has
this weird relativistic
effect of causing
an accelerated expansion--
it decayed into normal stuff.
And indeed I'm glad you asked
this question, because it gives
me an excuse to tell
you that each of us--
you, me, all of you--
contributed to the Big
Bang itself inflation because
you consist of material
that used to be the inflaton.
Can you believe that?
So you contributed
to the Big Bang,
if the "Bang" of the
Big Bang was inflation,
which I and many
people feel is probably
the correct view of the early
history of the universe.
So with that historical
precedent of the dark energy
back then turning into stuff
that was gravitationally
attractive, it's conceivable
that today's dark energy
will someday become
gravitationally attractive,
as well.
And in that case, if there
is enough of it-- and there,
we don't know which side of
the dividing line of omega
equals 1 are we on--
if there's enough of it
and it becomes
gravitationally attractive,
then someday, the universe
will start slowing down,
come to a stop,
and reverse itself.
But if the total
amount of dark energy
is slightly below omega
of 1, 0.9999, then
even if it becomes
gravitationally attractive,
the universe will continue
to expand forever.
So we just don't know.
And I, unfortunately, don't know
of any way we will ever know.
And this is for a subtle reason.
Here it is.
Our observable universe
is just a small part
of what we think there is.
Inflation makes a
gigantic universe.
And there will be fluctuations
in different observable
volumes.
So just like this room has an
average number of molecules
per cubic centimeter,
if you take
any particular cubic centimeter,
it need not be-- in fact,
it usually won't be--
right at that average.
It'll be a little bit above
and a little bit below.
And when you're two standard
deviations away, it'll be more.
But those are rare.
And blah, blah, blah.
If we find that the density
is very, very close to 1,
then this so-called
cosmic variance
tells us that what we measure
in our own observable volume
need not be representative
of the whole thing,
because we're so close
to the dividing line.
And most observable volumes will
be close to, but not right on,
the dividing line.
And so they're not
representative.
And so I don't
know any way around
that fundamental
limitation of not
being able to see outside
our observable universe.
So I don't think we'll
ever know, actually.
And this actually
has implications
for what the geometry
of the universe is.
If the omega is greater
than 1, then it's
some sort of a hypersphere.
It's a closed geometry.
Whereas if omega
total is less than 1,
then it's either flat space--
well, if it's less than 1,
then it's hyperbolic geometry.
If it's exactly 1, then
it's Euclidean flat space.
And I don't know
that we'll ever know
what the true global
geometry of the universe is.
That doesn't mean we
shouldn't keep doing research
at Lick Observatory
and elsewhere,
and the public outreach.
It just means we won't know.
Yes, Dion.
AUDIENCE: Alex,
how do you estimate
that the dark energy is
70%, dark matter is 25%,
and observable is 5%?
ALEX FILIPPENKO: Yeah.
So how do we get that?
So how do we know that
the dark energy is 70%?
There are many different
constraints, now.
But let me give you the
simplest one, and the one
that we originally used
in a paper back in 1998.
The current acceleration
of the universe
tells you who's
winning the tug of war
between pushing outward--
the dark energy--
and pulling inward-- normal
matter and dark matter.
It's like a tug of war contest.
You don't need to know the
absolute amounts of the two
sides.
You just need to know
their difference.
Could be that one team
completely gave up
and the other is pulling
with 1 unit of force.
Or it could be that this
team is pulling with 1,000
and the other one is
pulling with 1,001.
The difference is 1.
And that will have
the same effect.
So the redshift
distance relationship
tells us who's winning the
tug of war and by what amount.
It tells us the difference
between the push and the pull,
so to speak.
So in a sense, omega matter
minus omega dark energy
is what we get from
the supernovae.
And that number is negative 0.4.
Remember that number.
On the other hand, the
microwave background maps,
they show you these
little freckles.
And from theory, it's
quite easy to calculate
the spatial scale, the physical
size of a typical freckle.
It turns out there's
a certain size
having to do with
how far sound could
have gone in the early
universe by the time
these things formed.
So you know the physical size.
And that's relatively
independent of what
the universe is doing now.
It's quite model-independent.
So you know the physical size.
You know the angular size
because you measure it.
And that then tells you
whether the light rays
have been going through
a Euclidean space
or not, because
you're essentially
measuring whether the sum of the
interior angles of a triangle
is 180 degrees, greater
than 180 degrees, or less
than 180 degrees.
We find that it's
equal to 180 degrees.
That's what the angular
measurements show us.
So it's a Euclidean space
to within the uncertainties.
It could be either
way I just told you.
But it's Euclidean
within the uncertainties.
Well, that, according
to general relativity,
tells you that the total
omega, the total density
of the universe, is 1.
If the difference is negative
0.4 and the sum is 1,
then matter is point 0.3 and
the dark energy is point 0.7.
AUDIENCE: Is that
0.4 remaining stable?
ALEX FILIPPENKO: No, no.
As the universe
expands, the dark energy
is becoming more and more
of the dominant thing,
even if its density
is not changing--
if it's a property of
space, then its density
doesn't change-- but
the matter gets diluted.
If you have 1,000 particles
in a box and the box expands,
the density of the
particles is decreasing.
So as a fraction of the pie,
the matter is decreasing.
And thus as a fraction of
the pie, the dark energy
is increasing, even
though per unit volume,
its energy density
appears to be constant.
But it's always as a
fraction of the total pie.
So indeed the universe
is now accelerating,
but not yet exponentiating.
But as the dark energy
becomes 90%, 95%, 99%,
99.9% of the total,
then the acceleration
will transition to
an exponentiation.
The other thing, without getting
into the microwave background
omega equals 1 total thing,
the other argument-- and this
is one that we also use--
is that, as I told you,
in the early '90s,
a lot of people
were convinced that the matter
content of the universe is 0.3.
So if omega M is 0.3
and omega M minus omega
dark energy is negative 0.4,
then omega dark energy is 0.7.
And by the way,
0.3 plus 0.7 is 1
which agrees with the
microwave maps of the flatness
of the universe.
And now there are
several other ways
of constraining that, as well.
So the so-called
concordance cosmology
is now something that
is accepted by most
astrophysicists that I know.
We're still completely
befuddled by this.
It's not your
grandmother's universe.
It's not what we asked for.
But it appears to be that
that's what our universe is.
Or-- and Noelle will confirm
that sometimes I wake up
screaming at night at 3:00
in the morning-- I sometimes
think that dark
matter and dark energy
are our 20th and 21st
century counterparts
to Ptolemaic epicycles.
Right?
Epicycles could
be used to explain
the observed positions of
planets to arbitrary accuracy.
You could add epicycles
on top of epicycles.
By the way, this is a
Fourier series, right?
Any periodic function
can be represented
by a sum of sines of
different amplitudes, phases,
and periods.
Well, that's what a bunch of
circles on top of each other
are.
So Ptolemy invented
Fourier analysis
with the first two terms
long before Fourier did,
and he didn't know it.
But that's what it is.
It is arbitrarily accurate,
if that's all you want,
is accuracy in terms of
predicted positions of planets
versus observed
positions of planets.
But ultimately, now-- no fault
of Ptolemy's-- we know that
it's wrong.
He was brilliant for having
conceived of the idea.
And it lasted 1,500 years.
And he made his living
being an astrologer.
And so he needed to know the
positions of Mars and stuff.
And it worked well.
But it ended up being wrong.
So dark matter and
dark energy are simply
our best current descriptions
to try to explain what we see.
But they may well be wrong.
And what I'm hoping is that
one of the youngsters excited
by Google Making Science
and Lick Observatory
will figure out what it
is if it is indeed wrong.
AUDIENCE: Thank you, Alex.
We really appreciate it.
ALEX FILIPPENKO: Thank you.
Thank you.
[APPLAUSE]
