[MUSIC PLAYING]
SPEAKER: Hello,
everyone, and welcome.
Today we have two speakers
coming up, the first of which
is going to be Mr. Rosing, who
used to be a SVP of engineering
here, if I remember
right, until May, 2005.
WAYNE ROSING: April 1.
SPEAKER: April 1.
The other speaker
today will be Iair,
who is an astronomer at the
Las Cumbres Laboratories.
So if you can please
join me in welcoming--
I believe that Wayne is
starting off the talk.
So if you can please join
me in welcoming Wayne.
[APPLAUSE]
WAYNE ROSING: One, two.
OK.
Hi.
We're up here, and I
thought I'd tell anyone
at Google who is
interested about what I've
been up to for what is
now 13 years, practically,
this starts in 1983 when I was
at Apple working on finishing
up the Lisa.
We were also working on
Macintosh stuff then.
And some things sort of
came together one day.
Personal computers
were getting powerful.
At least they had 32-bit
address buses then.
Disks were getting bigger.
The internet was happening.
It didn't quite take off
for another seven years.
But we were moving out of
the ARPANET and [? DekNet ?]
into the modern world
of the internet.
And I realized that you could
do astronomy around the world
by building robotic
telescopes and putting them
in good places, ideally,
in the south and the north.
So I still have "The
New York Times" atlas.
And if you look at
this thing carefully,
you'll see there's a number
of spots that are particularly
worn out, one in
Chili, Urumqi, China,
which we won't be going to,
and somewhere around Capetown.
And geography actually
says there are only
three interesting spots to
put things in the south.
You have a fairly wide source
of choices in Australia,
but of the other two places,
you're pretty constrained.
But this was an idea, and
so I started to pursue it
as a sort of a hobby.
And then late in
the 1990s, I managed
to get a small, very
small, telescope.
I think my wingspan, I could
touch both sides of the dome.
It was very small,
15 millimeter lens,
doing a survey of
the southern sky.
And the reason I did that was,
how do you design and build
something that runs on
its own for years on end
and sends you data back.
And we started, I think,
with a 25 kilobit link.
That quickly got upgraded
to a 50 kilobit link.
Really huge.
So I started figuring out
you need to compress data,
and all kinds of things.
This is a very
interesting project.
And then things went on.
And then I was retiring to
Santa Barbara with the idea
that after Sun, with
the idea of, OK, I'll
go build this network.
I'll scope out six 24-inch
telescopes and get it going
and see what happens.
Just as I was sort of starting
to get that organized,
I got this phone call that
led to my coming here.
And so I took over
from Urs, who was
the first VP of engineering.
I think, as he likes to say,
I'm the first professional one.
[AUDIENCE LAUGHING]
And the rest was history.
But an interesting thing,
when I was in my interview
cycle, which by the way,
was just as rigorous
then as it is now probably.
I was 13 weeks in
an interview cycle.
And I don't know, but it
rumored I was the 54th person
to be interviewed for this job.
I'm not sure that's true,
but I think it's probably
somewhat more true than not.
But I got the job.
But in the final
interview, I did ask Larry.
I said, I have this
project in mind.
And I want to know--
I want to be able to do it.
So I really, actually, want
to have an exit strategy.
Now, this is not your
average interview question--
[AUDIENCE LAUGHING]
--to the people
who are hiring you.
And I explained what it was, and
Larry said, oh, that's great.
If you get engineering
to 1,000, you're
free to go with my blessings.
[AUDIENCE LAUGHING]
And I'm sure he said
it with every intent
that that was going to be
indentured slavery for me
for the next 10 years
or something like that.
And so the day I
took over, there
were 80 people in my
reporting structure.
It was, I guess, what we
would still call operations,
engineering, including
search, and the people who
ran the IT system for finance.
So it was sort of, if you knew
something about computers,
or you could spell computer,
or you could do anything
with a computer, this
little gang of 80 people.
And that was what I
found when I got here.
And, needless to say, five years
later, blown through the 1,000,
and we had gone public.
And I thought it was time
for me to step aside.
And by the way, I have at
least four or five other people
who succeeded me in this room
here, so thank you for coming.
And you have obviously had
your own growth strategy.
And some of you even have
your own exit strategy.
So it's been a grand success.
So this is something
that LCO is about.
We used to have
a different logo.
It used to use
the Google colors.
But we found out, in
talking to a lot of people
in focus groups, that LCOGT.net
is confusing to people.
It's a tongue-twister.
And because we had used the
Google colors in our logo,
people actually thought we
were a subset of Google.
But we were just-- and so
when we tried to raise money,
they said oh, you
don't need money.
Google's got all the money.
So it became confused.
So about a year-and-a-half ago
we re-branded ourselves with
this new vision.
However, the rest of the
thing is not re-branded.
Now, let me see.
What do I push to go
to the next slide?
It's a Macintosh.
I don't remember how to do this.
Which?
OK.
[AUDIENCE LAUGHING]
OK.
So the goal was--
basically, I decided
that if I was
going to build this
network, it would
be interesting to establish
a small scientific institute
in the fine-honed
tradition of Lowell
Observatory in Flagstaff, which
was founded by Percival Lowell,
and they did a lot
of stuff on Mars.
And there was this other
thing called the Carnegie
Observatories of Washington,
founded by Andrew Carnegie,
who basically
funded Mount Wilson,
Palomar, and the Magellan
telescopes down in Chili.
So there's only
like three or four
privately funded
scientific institutes
in astronomy in the whole
world, and we are one of them.
So it's certainly a
unique thing to do.
And here's sort
of, at the height,
when we were pushing out
our first set of one meter
telescopes.
You can see a bunch of them.
We hit about 80
people at the peak.
And we're down to about 35 now.
And let's see.
What do we have here?
Well, I'll skip some of that.
We have a board of directors
and all that other good stuff.
And our unique global
telescope is designed
for time domain astronomy.
So you might ask, what
is time domain astronomy?
Well, basically, things change
in the sky, in the universe.
They often change on time
scales of a billion years.
Stars oscillate on
time scales of years,
to months, to sometimes days.
There are certain transient
events that reoccur,
different kinds of cataclysmic
variables and stuff like that.
So there's a lot of
stuff that's changing,
but measuring it is
difficult. And in particular,
at most observatories, what
happens is you get a night,
but you share that telescope
with 50 of your closest
friends, and you get
two or three nights.
And you take your
data, and that's it.
So if something is changing at
the scale of odd and strange,
but weeks or months, you get
a very small sample every once
in a while, unless
you have set up
some other way to watch this.
And it seems to me-- and it
always struck me as odd--
why wouldn't anyone do this?
The reason is, I talked
a lot to astronomers,
and they said, well, if anybody
has enough money to do this,
they're going to take that
money and build the biggest
telescope they
can because that's
going to result in the
most scientific output,
and papers published,
and careers made.
And that's an honest answer.
And so I didn't have to
make a scientific career,
so I guess I made a
different decision.
So time domain is what we do.
Let me see if I get around here.
I'll skip some of the
stuff and get pictures.
What we have is we have three
one-meters, 2.4's in Chili.
I'll just circle around.
We have a two-meter
telescope on Maui.
This happened in 2005.
We got extremely lucky.
Just as I started this project
that started in Britain
got in financial
trouble, and we were
able to basically acquire it.
And so we got a two-meter
telescope on Haleakala.
And if any of you are visiting
Maui, send me an email--
[AUDIENCE LAUGHING]
--and you can get a tour.
It's really neat.
[AUDIENCE LAUGHING]
Then, you sort of
trundle over here
to Coonabarabran in Australia.
We have another two-meter.
two one-meters, and
some small .04s.
We have a contract
that's waiting
on the Chinese
government to say,
here's the rest of
the money, and then
we will be installing two
one-meters in Western Tibet.
This is a place called Ali and
it is probably, in my judgment,
as close to being on
the moon as is possible.
It's at 17,500 feet.
They get about two centimeters
of precipitation a year.
And there's nothing
that's living there.
So it's the world's
most inhospitable spot.
But it's got great astronomy.
And this whole area, basically,
clouds up all summer long
off the Indian monsoon.
So you can't do
any astronomy here.
So this is the magic
spot because then you
pop down here to
South Africa, where we
have another set of telescopes.
Then we have a site in Tenerife.
We have two small telescopes.
And we're in
discussions that we hope
will lead to this
filling out with more.
And then we have a contract
with Israel, one of the--
it's at Weizmann?
AUDIENCE: Tel Aviv.
WAYNE ROSING: Tel
Aviv University.
There's a Wise Observatory
here, one-meter telescope,
and we're putting a
spectrograph on that.
So in addition to
these telescopes,
we're going to do
optical imaging.
We have a number of them,
state-of-the-art spectrographs,
fed by one or two
of these things.
That's a National
Science Foundation
grant we got to built yet
another unique network.
So basically, this is
now up and running.
We're waiting on a few things.
Yes?
AUDIENCE: How good is the
infrastructure in China
right now?
WAYNE ROSING: It's
almost nonexistent,
except the Chinese National
Optical Astronomical
Observatory wants to
build this site up
with the hope of putting an
eight-meter there someday.
Not our eight-meter,
but their eight-meter.
But we're part of
their training wheel.
So we go there.
We start to help driving
that development.
So they funded about half of it.
I think there's
just a money crunch
on dollars that are flowing
out of China that they
have to sort out.
So that's our big telescope.
It has no scale, except to say,
this gear is larger in diameter
than I am tall.
So you can see, that's what
a two-meter telescope looks
like in its clam shell.
This is our one-meter facility.
And let's see.
Looking at this, there's
something funny about this.
Oh yeah, there's some
telescopes in the foreground,
but these three are
our three one-meters.
This is our small one.
There's now two of those.
That's a telescope from Korea.
But that's our big telescope.
These are our little ones.
I won't bore you
with the details,
but there are some things about
this that are very special.
Everything is identical.
The filters are the same.
The detectors are the same.
The software is the same.
So you can actually get
results and merge them
from these telescopes easily.
Yes, sir?
AUDIENCE: What's is
your angular resolution
and your brightness resolution?
WAYNE ROSING: Let's see.
We go down to
typically an arcsecond.
We can do better,
but usually you
don't get much better than that.
It depends on the site.
Brightness, reasonably
long exposures.
I think we can get down
to 21, first magnitude.
And we've built the
whole thing around--
somebody else discovered it.
It's changing.
We measure it, potentially
six times a day,
and often for weeks at a time
if the weather cooperates.
And that's science that we get
to do that no one in the world
can do.
So we do all kinds of programs.
In fact, we have approximately
70 to 100 programs
operating now.
They're all scheduled in a batch
every few minutes, 10 minutes,
15 minutes, something like that.
And we only have a small
group of scientists.
We have five sort of staff
scientists, if you will.
And then we have, I think, about
six postdocs and grad students,
something in those
numbers, typically 10.
And we couldn't even
begin to use the time,
but our partners, our
hosts at the observatories,
have to get time.
And then they're all
organized, and we've developed
these scientific consortia.
So right now, there's about
100 programs operating,
which is quite a high
amount of productivity.
Recent important results
are the kilonova, which
you're about to hear about.
This is a world-class scientific
result, and it just happened.
It was just
announced in October.
This event happened--
it was the morning
before the eclipse, the
day before the eclipse,
the morning of the day
before the eclipse.
AUDIENCE: Two days.
WAYNE ROSING: Right.
Or maybe two days before.
So all of our astronomers were
all up with Allen, actually,
in Oregon, or wherever,
looking at the eclipse.
And this all sort of happened.
And it's an
interesting testament,
which you'll hear about.
OK.
Other things we have done.
You may have heard
of Tabby's star.
Oh no, this is a different one.
This is a different one.
This is a supernova,
that-- normally supernovas,
when they go off, they go up,
they stay up, and they fade.
And after six
months, they're gone.
They're just burnt out embers.
Well, Iair and one
of his collaborators
found a really unique one.
So this is what happens when you
have the time and the ability
to do this kind of science.
So the future is--
OK, running quick.
Rob Pike, I don't know
if any of you know him.
Rob introduced me to Tony
Tyson, who came from Bell Labs.
They both came from Bell Labs
back in, I think it was '83.
And at that time, Tony
was talking to us about,
how did you build enough
computing to digest
the data coming out of a three
gigapixel camera at a rate of--
every few minutes,
you get a new image.
And how you analyze it?
How do you get it stabilized?
How do you archive it?
How do you get it to
the United States?
How do you get it prepared
so the whole astronomical
community can use it?
And in 2003, that was still
a awesome computing problem.
Now, it's practically
a [? rack, ?] except
I'm sure their scale
is such that they still
have a big data center or two.
And NCSA in Chicago is the
destination for that data,
and they're going to
be doing a lot of work.
So this thing's coming
online in four years.
It will survey the southern sky
every point, every three days,
and some points more
frequently than that.
It will produce about a million
events a night that says,
at this point,
something happened.
And it will say, it
moved, it changed color,
it changed brightness, that
something will have changed.
So it will give a
million triggers
a night that
something has changed.
We figure there's a few
hundred to a few thousand
such triggers.
Yes, sir?
AUDIENCE: How do you
not get false positives
from the atmosphere?
WAYNE ROSING: You generally
integrate for 30 seconds or so.
So that often helps.
And you might have
lot of things.
You take three pictures.
I don't remember exactly
what [INAUDIBLE] do.
But typically, you take two
or three, and you median them,
or you look for an outlier,
and you toss it out.
You see other things.
But the idea for
us is, there will
be hundreds of
events a night that
will be moving up too bright
for this thing to measure.
And that turns out that
they move into the area
where we can do
the measurements.
So there are three or four other
surveys coming prior to this.
And then this comes on board.
And so from basically
2022 to 2032,
the LCO is going to
camp out, and we're
going to study all that stuff.
And we expect to find
out lots of new physics.
So that's basically
where we're at.
We built this thing.
It took a lot of work.
And now it's working.
And as to how it's working,
I'll introduce Dr. Iair Arcavi,
who's one of our postdocs.
He's an Einstein Fellow,
which is something
that comes out of NASA.
Basically, they pay his salary.
We give him a desk.
And guess what happened?
IAIR ARCAVI: Thank you, Wayne.
[APPLAUSE]
Let me see.
Is this working?
It sounds like it's working.
OK.
Thanks, Wayne.
So it's really
exciting to tell you
about this discovery
that has all of us
in astronomy very excited.
It is one of the biggest things
that has happened in astronomy
in the last decades.
And as Wayne said, Las
Cumbres Observatory
turned out to be the exact
thing you needed for a discovery
like this.
So this all happened
on August 17.
I think it will be remembered
as an important day in science
for many reasons.
So it was the first time we
detected gravitational waves
from the merger of
two neutron stars.
It was the strongest and best
localized and closest event
where we detected
gravitational waves from.
And it was the
first time we were
able to detect
gravitational waves
and light from the same
event at the same time.
The light from that event is
what we call the kilonova.
So that was the first time
we've seen one of those.
And it was the first
time we identified
which galaxy gravitational
waves were coming from.
OK, now that is
just a part of what
made that discovery so special.
But let me start
at the beginning
and explain what
all of this means.
So it starts, of
course, with Einstein,
who, 100 years ago, came up with
a theory of how gravity works,
a very elegant theory which--
OK, so here's the 30 seconds
of what general relativity is.
So the idea is that
space and time--
let's focus on space--
is like a fabric that can
be made to bend and curve
and shift.
And what does that is mass.
So if you put a piece
of mass on empty space,
it will curve space in the sense
that the distance between two
points is going to change.
And it is that curvature that
is what we perceive as gravity.
It's not a force.
It's not that the moon knows
that the Earth is there,
and so it orbits it.
It's that the moon
is just moving
in a straight line in curved
space caused by the Earth.
OK, so this was the idea.
Mass curves space, and that is
what we perceive as gravity.
It was a totally
revolutionary idea.
And the summary of that is
mass tells space how to curve,
and space tells
mass how to move.
But of course, it's not
just a story and idea
that he had and moved on.
This is all rooted in math.
So there are equations that
you can calculate exactly how
much mass curves
space, and how that
tells other mass how to move.
There are a lot of
different equations.
OK, just to tell you that we can
calculate this stuff precisely.
And all of the observations
match the theory very exactly.
But one of the things that
came out of the equations,
that Einstein
realized a year later,
was that if you can
get space to bend,
you can get it to
ripple in waves as well.
And the way you
would do that is you
would take two very
massive objects.
So gravity, despite
what you might think,
is actually is a weak
force in the universe.
You need a very big mass.
And you need two of them
to orbit each other.
And as they do, they will
cause space to ripple.
And as they do that,
they lose energy
and they move closer
to each other,
and go faster and faster
and stronger and stronger
until they merge.
So this is what we call
gravitational waves.
It's these waves in space
itself that move through space.
So the question is how
do you detect this?
OK?
It's a very tricky
measurement to make
because if you
just take a ruler,
and the gravitational
wave passes through,
your ruler is going to get
distorted with space itself.
So you can't make that
measurement very easily.
The way this is done is with
something called a Michelson
interferometer, in case
anyone's ever heard.
You fire laser beams
perpendicular to each other.
They hit mirrors at the end.
They come back, and
they meet each other.
And if a gravitational wave
passes through the detector,
it makes one arm shorter
and one arm longer,
and then they oscillate.
And that changes the way the
laser beams meet at the end.
The idea was designed
in the 19th century.
But it turns out to be
a super useful device.
And these are huge
versions of that.
So these are what we
call the LIGO detectors.
Each one of these is this
L-shaped interferometer.
There's one in Washington State.
There's one in Louisiana.
Each one of these arms
is four kilometers long
because the effect of
gravitational waves, even
from a very massive object,
passing through the Earth
are tiny.
The relative change
in length when
a gravitational wave like
this passes through the Earth
is 10 to the minus 21.
OK?
And so that's the
number you have
to multiply the
length of your arm
in your interferometer to get
the actual change in length
that you're going to feel.
So even with four
kilometers long,
this is about
1/1000th the diameter
of the nucleus of an atom.
This is what they are
trying to measure.
OK?
So in doing that,
these are actually
the most precise
instruments ever built.
And they have two,
so that A, they
know that they've
measured something real.
If you see it in both of
them, it's not some fluke.
And two, having two
of them tells you
where it came from on the sky,
which direction it came from.
And that allows us to
know where it's from.
There was a question.
AUDIENCE: Yes.
Is this really like
a Michelson-Morley
experiment that's trying
to detect the ether?
IAIR ARCAVI: Exactly.
It's the exact
same thing that was
used for the Michelson-Morley
experiment, which
tried to detect the ether,
and didn't detect the ether.
And that ended up being the
basis for the special theory
of relativity.
And now that same
principle is being
used to test the general
theory of relativity
and detect gravitational waves.
Yeah.
AUDIENCE: There was also
a third instrument, right?
IAIR ARCAVI: Yes.
Yeah, we'll get to Virgo.
But this is the LIGO,
the US instrument.
There's one in Washington,
one in Louisiana.
And they detected the
first gravitational waves
only less than three years ago.
It was in 2015.
You may have heard.
This made big news,
the first time
ever that gravitational
waves were detected.
This was from a merger
of two black holes.
So a lot of the
professors were happy
that Einstein was vindicated and
proven right, which is great.
But we didn't really have a
doubt that it wouldn't work.
The real importance here is
that this is a totally new way
to study the universe, right?
For 500 years, everything
we know about the universe
has come from light.
You built all the scopes.
You point it somewhere.
You get light from
a distant object.
You study that light,
and everything we know
has come from studying light.
Suddenly, for the first time,
we turn on this new mechanism.
It's not waves of light
that are coming towards us.
It's waves of gravity.
And it opens up
a totally new way
of seeing the universe that
we couldn't see before.
So just in this first detection,
the merger of two black holes,
we could not have seen
that any other way.
We only see them through
their effect on space-time.
And, in fact, it was
already a surprise
because the black holes that
merged were about 30 times
the mass of the sun each.
And we didn't know
there were black holes
that massive, let
alone in pairs,
let alone close enough to merge.
And the people who detect
gravitational waves are
physicists studying--
detected the waves--
they're happy.
They're done.
And now the astronomers
are all like, where
did two 30 solar mass
black holes come from
to merge together?
We don't know.
So it's now a new
problem we have to solve.
The problem there is
that black holes only
emit gravitational waves.
We don't see any light
coming from black holes.
They are black, right?
So the really
powerful discovery is
going to come when we can
combine the light that we see
from an event and the
gravitational waves together,
and then really understand
the physical processes that
are happening.
And we can do that if,
instead of black holes,
we look at merger of the
next densest massive object
in the universe, which
is our neutron stars.
So neutron stars are
superdense objects.
They're about the
mass of the sun packed
into the size of a city.
Here it is on top of
San Francisco for scale.
And at these
densities, matter is
totally different
than anything we know.
So we know these objects exist.
They are the leftover
cores of very massive stars
that explode.
And super heavy, they
leave behind this very
dense crushed core that
used to be their center.
About the mass of the sun,
about the size of a city.
And it is so dense, that the
atoms get squished together
in a way.
But this thing is
essentially mostly made out
of neutrons packed
together very closely.
So you can also think of this
as a city-sized atomic nucleus,
or a city-sized star.
Either way, quite
fascinating objects.
And so when they
merge together, they
will also make
gravitational waves.
But this is different
than black holes
merging together because it's
a much more messy process.
Nothing can escape a black hole,
but neutron stars, stuff still
can escape.
So this is a simulation of
two neutron stars merging.
You see it's very messy.
There's stuff flying
out everywhere.
And this stuff is very hot.
And in fact, it was
predicted that this
is the only place in
the universe, when
this happens, where the
heaviest elements can be made.
So the heaviest elements
in the Periodic Table,
including gold, and
uranium, and platinum
and all this stuff
that we know exists
in the universe has to
have been made somewhere.
And the only place where
the conditions were right,
we think--
it's a theory at least--
is in these merging
roots of neutron stars.
And as these heavy elements
are made, they emit light.
And then that is
the thing that we
will be looking for in parallel
to the gravitational waves.
If we can get both
of them together,
we'll be able to really figure
out if that's what's happening.
OK?
So here is what we expect
for the merger of two neutron
stars.
This is an
illustration, obviously.
So we have neutron
stars merging here.
They're making
gravitational waves.
That's, that ripple there in
the grid, which are moving out
through the universe.
And then there's this stuff
that is very hot that is
forging the heaviest elements.
And that is what's producing
light that we expect to see.
And we call that a kilonova.
And then there is also this
jet of very fast material
that gets launched.
And we don't know exactly why.
But the very
fast-moving material,
at substantial fractions
of the speed of light,
gets launched in
this jet, and it
makes the highest form of
energy light that we know,
called gamma rays.
It shines in gamma rays for two
seconds, and then shuts down.
And we've seen these
bursts of gamma rays
many times in the past.
But you only see it if the
jet is pointing at you.
And so, when we've seen that,
that was the only thing we saw.
It's gamma rays from the jet.
And then everything
else was too far away
so we couldn't see the
gravitational waves
or the other light.
So we've had this theory for
a while about these bursts
of gamma rays that we see
are coming from this system,
but we didn't know
that that was the case.
Now, the main problem
in trying to do this
is that when you get
gravitational waves,
they don't really know
exactly where they came from.
They give you a
location on the skies.
There's a map of the sky.
And this is the localization
that they consider
the gravitational waves
came from something that
happened somewhere over here.
Maybe.
This is the 90% sure.
It could be anywhere.
And this is the
actual localization
on the sky from this
first detection of the two
black holes.
It was somewhere in there.
So for us, with
telescopes, it's very hard
to go and find this little
arched piece of sky.
The other thing was that
the light from this kilonova
was very uncertain.
People were doing calculations--
what should this look like?
Should it be bright?
Should it be faint?
What wavelengths it would be?
Where should we look?
And the predictions
were all over the place.
Some people said, it would
be bright, it would be faint.
Most people thought, OK, it will
be faint, and it will be red.
So here's a problem
we needed to solve.
We need to find
something that's faint,
red, maybe even in the infrared.
Maybe we wouldn't even see
it in the optical end at all.
And it's somewhere in
this large piece of sky.
OK, so if you were a
reasonable astronomer, what
you'd do is you'd
say, OK, it's faint
so I need a big telescope,
because the bigger
the telescope the fainter
things you can see.
I'm going to need to put
an infrared camera on it.
And I'm going to need to design
the camera and telescope where
they can see large
chunks of sky at a time,
so they can take a few pictures
on that huge region in one
second, take a few pictures
of that huge region
and cover the whole thing
as quickly as possible,
because the other thing
about the kilonova
is that it'll be gone in a week.
This light only lasts
a week or a few days.
And if you take too long
to search, you'll miss it.
OK.
So and indeed, respectable
astronomers did exactly that.
There are huge
cooperations of hundreds
of people led by Harvard
professors that took control
over the largest telescopes
with the largest cameras.
And they're ready to
go next time there's
a gravitational
wave event to look
for it, with this strategy.
What we had at Las Cumbres was,
we gathered up about 10 of us
and said, this is going
to be pretty important.
But what we have is
pretty small telescopes
that only look at
visible light and only
see a tiny fraction of
the sky in each image.
OK.
And there's, like, 10 of us,
right. to look at the sky.
And we all looked at each other
and said, are we doing this?
We said, obviously,
we're going to do it.
And we were lucky enough
to be able to convince
to time allocation
committee, who
are the people who decide who
gets time on the telescopes
that we should do it.
So I was happy
that even though it
looked like it's not
the best way to do this,
they the still gave us
the time on the network.
Yeah.
There was a question over there.
AUDIENCE: Yeah.
What's the [INAUDIBLE]
are they [INAUDIBLE]
gravitational wave is detected
that it was from a kilonova
and not from as before,
just black hole merges.
IAIR ARCAVI: So the
gravitational wave
signal itself,
which I'll show you,
you can tell what the mass of
objects that are merging is.
And so this is an open question
in astronomy is up to mass
do you have a neutron
star and beyond that,
it becomes a black hole.
But we know more and less.
And the masses, for this event
that happened last August,
were what we think
neutron stars' masses are.
But I'll show you
something about that later.
So what we do have, though, is
something that no one else has,
which as Wayne showed you,
is complete global coverage.
So two things-- A, we have
telescopes everywhere.
So as soon as this
happens, we can get on it.
We'll a telescope in the dark.
If these other
big collaborations
have their one big
telescope in Chile,
they have to wait for the
Earth to rotate so that they
can see it from Chile.
The other thing we have is
that it's all fully robotic.
It's all software.
We can just write scripts
that will get the alert
and send it to telescopes.
You don't have to go,
fly to an observatory,
call someone up, ask for a
favor, observe this for us.
It's all done by software.
But how to get around this
problem that the localization
is typically--
this is another map
of the sky, that
was one of the localizations
from black hole mergers.
And our full view
to scale, that's
what we can get a shot of
with our cameras, right?
So it will take months to
cover the entire region.
By then, of course, the
event will be long gone.
So how do we do that?
Seems we have to get
a little bit clever
and realize that
stuff in the universe
is not just uniformly
distributed in space.
It's in galaxies.
And we kind of know where
most of the galaxies are.
Turns out, we don't know
where the small galaxies
are because they're faint.
But we know pretty much where
all the big galaxies are,
out to the distance where
gravitational waves can
be detected.
So if neutron star mergers
only happen in small galaxies,
we're screwed.
It's not going to work.
We won't know
where to find them.
But if there's a galaxy
that has more stuff in it,
it will also have
more neutron stars.
And that's where
you should look.
Then maybe we have a chance.
And so what we did,
was develop this system
where LIGO sent an alert through
this machine readable thing.
We had a listener looking
for-- once it gets the alert,
it asks, OK, where
in the sky is it.
Send me that localization.
It takes a list of galaxies
that we know where they are,
and the size based on our best
guess of where this thing could
be, which galaxies
to look at first.
And it then sends that
to the telescopes.
And we don't need any
person to be involved.
This can happen in a second.
Of course when we did
it the first time,
we did want to make sure that
this was working properly.
So we have this web page.
This is the actual
alert from August 17.
It picked 30 galaxies for us.
Turns out if you observe 30
galaxies in the region of this,
you cover about 50% of
the stuff in that region.
That's pretty good.
If you want to
cover 100%, you're
going to have to observe a
bazillion small galaxies,
and that will take forever.
But if you just observe
the 30 most massive ones,
you get 50% of the stuff.
And then there's the
list of galaxies.
It goes down.
These are the top five
that it selected for us.
Now, all we have to do is
click the big green button
to send it to the telescopes.
Again, we can do
this automatically,
which is our plan for next time.
But we just wanted to make
sure everything was working.
OK, so that was the plan.
Yeah.
AUDIENCE: Well, what
was your galaxy catalog?
IAIR ARCAVI: OK, yeah.
The galaxy catalog
is a whole issue.
There are various galaxy
catalogs out there.
We use one called GLADE,
which is a conglomeration
of different galaxy catalogs.
And some of the
galaxies, you don't
know how massive they are.
So we had to take
that into account.
It's this whole
heterogeneous data
set that you have to eventually
prioritize and decide,
I'm going to observe these and
not those for these reasons.
There's a lot of
details in that.
OK, so what actually
happened on August 17?
So two neutron stars merged and
produced gravitational waves.
And you'll notice--
and this I mention,
which is what
actually happens, they
get closer and closer together.
The waves become higher and
higher frequency and stronger
until they merge, and
then they're gone.
So that's a signal that the
gravitational wave detectors
are looking for, this
frequency going up,
and amplitude going up.
Here's what it looks like.
This is the actual
data from that day.
So this is frequency
versus time.
So this merger has been going
on for billions of years.
But we only catch
the last few seconds.
That's when it's strong enough
for the gravitational waves
to be detected.
And so what you see,
as this thing goes on,
there's the signal
at low frequency.
And as time goes on, it gets
higher and higher frequency,
and stronger and stronger.
And that's where they merged.
And that's the kind of
signals they are looking for.
So that's the actual data from
a detector in Washington state.
Now, we want to
know is this real?
Did we see it in Louisiana?
So the answer is, yes.
It was there in Louisiana.
You could see it.
But there is also that, which
is a glitch in the system.
So these kind of
glitches happen when you
have such sensitive equipment.
It's kind of a popping noise
you get on a stereo system.
It's less than a second long.
OK.
And it happened every few
hours, but they were not
worried about it.
Because, obviously,
what's the chance
that a glitch will happen
exactly at the moment
that two neutron stars merge and
the gravitational waves arrive
in the detector, right?
So the answer to that
question is 100%.
The chance is 100% that that's
exactly when it will happen.
OK, the problem with
this, of course,
is the automatic software did
not know how to deal with this.
So they set up their elevation
in a good section to one site.
They're all going on
on the other site,
so we can't give you a position.
Right, and we need the two sides
to measure the time difference
in order to get a
direction on the sky.
So we knew it was something
amazing that happened,
but we didn't know where.
So that was one thing
that didn't go as planned.
They, of course,
can remove this.
I mean, you can see the signal
here so you can extract it.
But you would need to work on
it for a few hours to do that.
It's not immediate.
So in the meantime, NASA's Fermi
satellite, which is a satellite
that's [INAUDIBLE] in space.
It looks for gamma rays,
this very high energy light
that we think comes from
the jet of these things,
but only if we're lucky
enough to be looking
from the right direction.
We never expected
to be that lucky.
We just thought the jet might go
in some other random direction,
and we would never
see the gamma rays.
But two seconds after that
gravitational wave arrived,
a burst of gamma
rays was detected.
So here's what it looks
like in real time.
So that's the gravitational
waves building up.
That's the signal for Fermi.
It's all just blue lines.
And then the merger happens.
And two second later there
is a burst of gamma rays.
Now, we see gamma rays all
the time, not that often,
a few or maybe one
a day or something.
So the chance that these
things are not related
and it just happens to be two
seconds later is very small.
Of course they calculated
what the chance is.
It's 5 millionths of a percent
is the probability that that
is not related to that because
it happened two seconds later.
OK, so again, it's just
telling us, OK, something
very important happened.
This in itself is
already the first time
that we've seen light
and gravitational waves
from the same thing.
And they sent out this alert.
It's called [INAUDIBLE].
These are like our version of
a bat signal anytime something
interesting happens.
OK, so they say, the
on-board trigger time
of Fermi happened at this time
is approximately two seconds
after the single LIGO detection
reported in this previous bat
signal that we sent you.
Now, the good thing is
Fermi, the satellite,
knows more or less where
in the sky this came from.
It can give you some
position, but it's
even worse than the
gravitational wave position.
Here is another map of the
sky with the localization.
This probability map, probably
had them here, maybe here,
maybe here.
So that's all we had to go on.
We only had the one
gravitational wave detector
so they didn't
give us a position.
But we were lucky to
get the gamma rays
and get a position from that.
And so here was
accurate depiction
of our reaction because, of
course, the way Fermi reports
its localizations is a totally
different format than the way
the gravitational
wave people do,
which is what we have
prepared all our software for.
So we had no idea how to ingest
the localization from the Fermi
satellite.
We never thought that's they
way it was going to happen.
But we did that.
And we started observing
galaxies in this region.
And then five hours later the
gravitational wave people said,
OK, we found this noise
in the glitch that
is the known part of the glitch,
and we were able to remove it.
And we updated the sky map.
And this is data from all
three gravitational wave
observatories,
Hanford, Livingston,
and V, which is the Virgo
observatory, is now available.
So Virgo is a third of these
interferometers in Italy.
And it had just turned
on for the first time
ever two weeks
before this happened.
OK?
It's a little smaller
than the LIGO observatory,
so a little less sensitive.
And it turned on just
two weeks before.
But now we had data from
all three observatories,
so the localization was
much smaller than it used
to be when you just had two.
So here it is on the sky.
When you combine those three
gravitational detectors,
then you are
somewhere over here.
So finally we have
what we were expecting,
the locations of the
gravitational waves,
where to search.
And then my reaction was bad
because we were looking over
here.
Right.
The Fermi satellite told us,
it's most likely over here.
But is it?
That'd be here.
But obviously, we started here.
So as soon as we got
this localization, which
was about five hours
later, we told ourselves
to go and stop
everything you're doing
and now observe that area.
So luckily, our telescopes
are obedient for now.
They do what we tell them.
And so here's one one
of our telescopes,
and there's the actual
galaxies it's observing.
It started going down the list
of this galaxy that we had.
Here's a map of the sky.
So that's the moon for
scale, just to get an idea.
This is considered a
small localization.
It's about-- if you
hold a banana at the sky
at arm's length,
that's about the shape
and size of this thing
that we have to look for.
And those are the galaxies.
We observe them.
Galaxy number five on our
list is one called NGC 4993.
This big fuzzy
ball is the galaxy,
and this little
point over here is
exactly what we were
looking for, the kilonova.
And we know that because
it wasn't there before.
So there's the image of the
galaxy from our [INAUDIBLE]
and the image of the
galaxy we took that night.
And that blue point of
light is exactly what
we were looking for.
And it turns out, there
were these other groups
who were doing this as well.
We were all looking at the
same galaxy within 42 minutes
of each other.
So these are all six images
taken from different groups
using different strategies.
Some of them use
different galaxy catalogs.
Some of them have
the big cameras
and they don't care
about the galaxies.
They just took pictures of
the whole thing and found it.
And so as soon as
we had them, we
started sending these
things out like crazy.
I saw this one.
What did you see?
What does yours look like?
This is [INAUDIBLE].
And the space
satellites from NASA
wanted to get in
on the action too.
So which satellite?
The Hubble space
telescope obviously
wanted to observe this as well.
So as soon as the
word was out, there
were about 70 observatories
on every continent observing
this one event.
On every continent,
someone pointed a telescope
and tried to catch this thing.
Pretty much every
professional observatory
on the planet and every
professional observatory
off the planet was
observing this.
So what did we see?
So the first image we took,
this is how bright it was,
about 150 million times
the brightness of the sun.
Remember, it's very far away.
And that's the first image
we got from our observatory
in Chile.
Now, as it happens,
this part of the sky
was only observable for
an hour and then it set.
So anyone who just had their
huge, amazing telescope that
is just in Chile have to
now wait 24 hours so they
can see what it's doing.
OK, but we don't have
to do that because we
have telescopes in Australia.
So as soon as the
Earth rotated enough,
we could see in Australia
and the site got brighter.
And then we can observe
in South Africa.
And by the time we got to Chile
again, to all those people
that are now finally able to
get their own observation,
it was much fainter.
So we had never seen
something this bright
evolve this fast before.
It went from blue to
red in just a few days,
and it faded by a factor
of ten in just a few days.
We've never seen
that happen before.
And also, it's
something we could only
see happen with this kind of
distribution of telescopes.
If you imagine that you only
have a telescope in Chile,
you're only going to have
the third point here.
So you totally missed
that it got brighter
before it got fainter.
And that turns out to be super
important for the physics we're
trying to understand,
that it got brighter
in about the timescale of a
day before getting fainter.
There's [? a smallness ?] that
went out the window as soon
as we figured that out.
But if you don't
have that thing,
you would only think
it's getting fainter.
You would miss
everything intricate
that's happening in between
because this thing was changing
so fast.
So one of the things we
learned by analyzing the light
is what kind of
elements it made.
So this is where we thought
the heavy elements were made.
Now we know.
Many of the light
elements are made
in the Big Bang, which are
mainly the elements made
by exploding stars, supernovae.
And we didn't know where--
we thought we knew,
but we didn't prove it, where
the most heavy elements are
made.
And this part shows
you now, from analyzing
the light of this event, how
much of the heavy elements
are made in the universe are
made made in emerging neutron
And we've almost solved this
problem for many of the atoms.
The press obviously likes
gold, so yeah, now we
know where the gold is made.
It's made in emerging
neutron stars.
So if you a gold ring
or a gold necklace
or something, the atoms
in that, we now know,
were made when two neutron stars
merged billions of years ago.
And someone's wedding
ring in MGC4993
is going to be made from
the gold in this kilonova
billions of years from now.
AUDIENCE: So the
percentage of yellow there,
the percentage of
that element is
made from these type of events?
IAIR ARCAVI: Yes,
that's what we think.
Now, there's a
lot of uncertainty
here because we've
only seen one.
So there's an uncertainty in
how much did that one make?
And then how common is this?
Right, so we're
still working it out,
but it looks like it
works out that most
of the heavy elements
in the universe
can be explained
by this process.
Another neat thing you can do
is find the a totally new way
to measure distances
in the universe.
So we know how strong
a gravitational wave
should have been from
calculating Einstein's
general theory of relativity.
Two neutron stars with
these masses merge.
It shouldn't have been
this strong of a signal.
We know how strong the signal
was when it got to Earth.
So we can measure a
distance to where it is.
So there we are.
This is a paper that
combines the light
with the gravitational
wave information
to get what we call a
Hubble constant, which
is this number that quantifies
how fast the universe is
expanding.
So we know the
universe is expanding.
We know it's starting
to accelerate
its expansion for
reasons we have
absolutely no understanding of.
And there are two main methods
now that quantify this.
How fast is the
universe expanding?
It's quantified in this number
called the Hubble constant,
which is about 70.
And we had our two
best methods until now
for determining this number
gets different results.
So one of them says
it's a little under 70.
And a different method says
it's a little above 70.
And now we can use this
gravitational wave event
to measure this number.
And what do you get?
It's that it's somewhere in the
middle, with this uncertainty.
So it's one event.
It's a totally different way
of constraining this quantity
in the universe.
And it gives-- it's always
consistent with what
we've been doing.
So now using other methods,
but as the more of these events
we get, this is getting
narrower and narrower.
And eventually it's
going to tell us
where exactly this number lies.
So for this one
event, we have learned
where the heavy elements
are made in the universe.
We've been able to
learn a lot of stuff
we didn't know about what
are the physics of material
at those conditions,
at those densities,
the things we call neutron
star equation of state.
We have very low
constraints, and now, we now
have some knowledge of those.
The fact that this
gamma ray bursts
that we've been seeing
for years are actually
coming from the merger of these
stars has been finally proven,
and all the way up to the
expansion of the universe.
So I don't really know of
any single event in astronomy
that has ever taught us
so much from the smallest
scales to the largest scales.
And there's still a
lot of open questions,
which is the even better part.
So somebody asked
about the masses.
So here, this is the masses
and times the mass of the sun.
So neutron stars are
about one to two times
the mass of the sun.
The ones that merged
in this event, we know,
were 1.something,
1.3, 1.6 I think.
And they merged to
make something here.
Now, the question is,
what did they make?
Did they make a neutron star
that's just more massive?
Or did they make a black hole?
So here, black
holes are this mass.
Here are the ones that
LIGO has seen, so very
massive stuff merging.
And there's this gap
that we're trying
to understand between the most
massive, you can make a neutron
star, and the least massive,
you can make a black hole.
And this thing that
was made in this event
just happens to be either
the most massive neutron
star or the least
massive black hole.
Either way, it's
pretty interesting.
There were a few other
events, a field of questions.
For example, I heard this
thing was supposed to be red.
We were never supposed
to be able to find it.
It was a totally
lost cause for us.
But it wasn't.
The universe was very kind
to Las Cumbres Observatory
and made it bright blue.
So we could see it
[INAUDIBLE] what is different,
what was wrong with the models
that predicted that it will
be red and it's actually blue.
That gamma ray burst
we saw was actually
100 times fainter than
all the previous gamma
ray bursts we've seen.
So that's also an open question,
what was going on there.
And you know, this
thing happened
150 million light years away.
It's nearby for our standards.
But it happened 150
million years ago.
That's the time the
gravitational waves
and the light were traveling
to here, which, by the way,
is another thing we have
proven with this event,
that gravitational waves
move at the speed of light,
which, of course, Einstein
predicted and is totally true.
But we've never actually
measured it before.
Now we know because
they're always together
But if this would have
happened two weeks earlier--
so this was happened 150 million
years ago, 150 million years
the light was traveling to us.
If this would have
happened two weeks earlier,
we would have not have seen
it because Virgo was off.
So the position on the
sky would have been huge,
and we probably would
not have found it.
If it would have
happened one week later,
we wouldn't have seen it either
because all the instruments
were off a week later.
But that was their last
week of their observing run.
They were scheduled to
shut down August 25.
And they did.
Because the way they work is
that they work a few months.
They shut down.
They do improvements
to be more sensitive
and come back on
again next year.
So they were scheduled to
shut down a week later.
So this would have-- you
know, 150 million years
minus two weeks, plus one
week, we would not have see it.
So again, I think
we're very lucky,
or these tings are much
more common than we thought.
And that affects--
you're starting
to get the opposite problem
that they make too much gold
and stuff than what we
seen in the universe.
And then, what did this make?
So we learned a lot, and
there's a lot of open questions.
And I just want
to mention, we do
this with a team of 10
people and seven people
in Santa Barbara.
And 10 more collaborators
around the world
have come and gave
us advice, and helped
us make this go and work.
And so one of the things I love
most about astronomy is you
don't need to be in one of these
huge collaborations and one
these hundreds of people
trying to do something.
And you come up with
an idea and just do it
with a smaller group
of people and get
it to work, of course,
assuming you have access
to a very new and unique
facility in astronomy
that no one else has.
It's the only one of
its kind that is there.
So just a quick comment
about what's next.
So the detectors are off.
As I said, they're
improving their sensitivity.
And they're going to turn on
again in the fall of this year.
So we had this event while
scrambling like crazy.
Now they're off.
We're all thankful for that.
And next year, we don't
know exactly, again,
how lucky we were, or
how common this is.
If it turns out we weren't
lucky, it's just very common,
this could happen as
often as once a week.
We could have one
of these every week.
So obviously, we need
to figure out how
we're going to deal with that.
But also, just the amount of
stuff we can learn from it
is staggering.
Other countries are
building more detectors, so
Japan and India.
This is the one in Japan, which
is going to be underground.
It's going to turn
on in a few years.
And so the localizations are
going to get even better.
So we're going to be able
to find them even quicker.
And they're going to be
doing this from space
because the things
are so sensitive,
these instruments,
at some point,
just The earth is not
quite enough to do
these measurements.
The ground is shaking at
some frequency all the time.
You need to go to space to
detect the lower frequencies
of the gravitational waves.
This mission was approved
recently by the European Space
Agency and NASA.
They're going to launch
these spacecrafts that
are going to be flying
millions of miles
away from each other in
formation to these laser beams
and sensitive to
gravitational waves
at much lower frequencies.
So totally different
kinds of things
that produce gravitational
waves in the universe
are waiting to be
discovered by them,
not to mention the same
neutron stars that, maybe five
years before, were
spinning a little slower,
it's going to find,
and it's going
to tell us five years from now,
on that day, at that second,
there's going to
be a neutron star
merger at that part of the sky.
So start training
a PhD student now
to study that event
five years from now.
Yeah.
AUDIENCE: Is the
detectionability linear?
Is that going to be six orders
of magnitude more sensitive?
IAIR ARCAVI: It is.
So it depends on what frequency.
The idea of going into
space is that you are not
going to detecting the same
things that LIGO is detecting.
You're going to be detecting
gravitational waves
at lower frequencies.
So it's like having a radio
station that's just tuned
to a different channel.
So we'll see totally
different things, but also
the same things at
different times.
And the technology to do
this doesn't exist yet.
This is still
planned, but they did
have tests that work much
better than predicted.
So this is really not
just the one discovery.
It's really just the
beginning of a totally new way
that we have to
see the universe,
and learn how it works,
and learn what's going on.
Thank you.
[APPLAUSE]
So we can just do
questions for both?
We had some during,
but happy to take more.
Yeah.
AUDIENCE: So when you say
you understand something,
you have a new
model, I understand
there's models were equations.
Are all of your
models simulations,
or do you still have equations.
IAIR ARCAVI: That's
a great question.
So the question
is are our models
equations or simulations?
Yeah, so we actually
have two types of model.
We call them analytical
model, which are equations.
We can calculate in numerical
models, where we just
put all the physics into a
computer, and let it run,
and see what happens.
And there's a benefit to both.
The universe is mathematical
to as far as we can tell.
But its mathematical in
equations that don't know
how to solve.
So at some point,
we need equations
to get some tool of
understanding what's going on.
But then, we need
the simulations
to actually solve it
and figure out what's
actually going to happen.
Even Einstein's equations, which
are relatively simple to write
down, took decades.
This is another thing
that made LIGO possible.
It took decades to
calculate what they mean
through numerical simulations.
There's a whole field
in astronomy and physics
that does this, to actually
be able to calculate
what these equations say.
And the fact that we know
what a gravitational wave
signature should look like is
thanks to those calculations.
That's how they knew what
to look for in the data.
Yeah.
AUDIENCE: So how certain
are you about, like,
that around 50 number?
Like is this something we should
you should expect next year
that [INAUDIBLE]?
IAIR ARCAVI: Yeah,
the full answer
is that it's between 1 and 50
is what they expect next year.
It's also hard to ask for the
time, location, community.
Give us between this amount
time or 50 times as much
of that on the telescope
because we don't know,
A, how common these things are.
From just watching,
seeing one of them,
we can do a calculation.
If we solve one in
this time, we know
they should be roughly this
frequent in the universe.
But there's an order of
magnitude and uncertainty
to that.
And then we don't
know how sensitive
they're going to be able
to make the instruments
in the next run.
So they're working
on them, but it
's an incredible feat of
engineering, these instruments.
So it's entirely unclear
what the sensitivity level
is going to be.
So when you factor the
two things together,
they say, yeah, we'll
find between one and 50
in the next year we
turn one, and figure out
how to deal with that.
AUDIENCE: Cool.
WAYNE ROSING: There's
an interesting thing.
I keep saying, the interesting
thing about this thing
is, if there are no events,
we don't have to put it
in any telescope time on it.
And if there's an
event, this becomes
the most important science
we could possibly be doing.
And the ultimate
goal of these surveys
is to figure out how do we
classify what comes out of them
and then make the decision, is
it important to do something
right now.
And it's interesting,
even in LCO, there's,
shall we say, a degree of
institutional resistance
to the idea of just
letting this stuff just run
and making the decision.
But the nice thing
is, you can do that.
It's all software.
It's all robotic.
And hopefully, none of the
software has to ask permission.
IAIR ARCAVI: Yeah.
I mean, in a classical
telescope, I would have to say,
here's the amount of time I
want, and here's what want.
I want it on September
14, 2018, because that's
when I think the gravitational
wave event is going to happen,
which is, of course,
impossible to know.
But LCO, we can
set some time aside
in case this happens,
but in the meantime,
do whatever other
100 observations
that people are asking for,
thousands of observations.
And when this
happens, that's when
I'll let you know, from now
to three seconds from now,
I need to observe this thing.
And I just send that to the
software, and it'll do it.
I don't have to
tell it in advance
when this is going to happen.
AUDIENCE: How long does
it take you to turn it on?
From the time you say go,
what time does the telescope
start looking?
IAIR ARCAVI: So
from the time I tell
the telescope what to observe
until the shutter opens
on my image can be between
five and 10 seconds, if there's
a telescope that's in the right
place and the sky is clear.
So we can get it on
in merely seconds.
And that is the ideal
plan for the next round
is to take the humans out
of the loop completely.
LIGO sends an alert.
It figures out the
galaxies on its own,
sends a command
to the telescopes,
telescopes start observing.
We can be sleeping
when this happens.
We wake up, and it tells us, oh,
I found this kilonova for you.
You're welcome.
Go write the paper now.
But yeah, seconds is the answer.
AUDIENCE: What--
I seem to remember
that it took a long time
for them to actually detect
gravity waves.
And if they're
happening all the time,
is that because their
instruments, for a long time,
they thought they were sensitive
enough, that they weren't?
IAIR ARCAVI: So this-- yeah,
the current way LIGO is running
is called advanced LIGO.
They ran before
that for a few years
what they called initial LIGO,
which was much less lower
sensitivity.
And they actually
knew, from what
we knew to expect of how often
gravitational waves happen
in the universe, they knew
they would probably not
detect anything.
But they still ran in case--
the best thing is, of course,
the stuff we don't expect.
So they still ran for several
years also to test the--
this is our
brand-new technology.
And they didn't find anything.
They shut down.
They did a huge upgrade.
Essentially, it's
a new instrument.
And then, in fact, that
first black hole detection
happened during an
engineering run,
before they had
officially started to run.
They said, we're doing
an engineering run.
There's this whole
story about someone
was supposed to be
working on the instrument,
and it was supposed
to be offline.
But they decided to go home
early and left it online,
and it caught that
first black hole
merger, which, to this day, was
the best signal ever obtained.
And that was a week
before they had planned
to start the observing runs.
So as soon as they
were at sensitivity,
they started timing these.
And there are now five
black hole mergers
that they detected in the last
2 and 1/2 years and this one
neutron star merger.
And when we come back
next year, the rate's
going to be even higher.
So they were right below
the sensitivity before.
And now, they're right where
things are interesting.
Yeah.
AUDIENCE: How do the
physicists and the astronomers
share the work?
IAIR ARCAVI: That's a great
question about the physicists
and the astronomers
working together.
So to many people, you can say
physicists or astrophysics,
it sounds like the same thing.
These are actually two
very different cultures.
So the people who make
LIGO are physicists.
It's a 1,000-person
collaboration.
They're all working
together for this one goal.
They are super-cautious.
There are historical
reasons why they're very,
very afraid of saying they
detected something when they
didn't.
And so as far as
they're concerned,
they want to detect the
gravitational waves, work
on it for, like, six months.
And then when they're
sure, they let people know.
OK, now, astronomers,
very different.
We still work in pretty
small collaborations.
We want to get stuff
out very quick.
And we told them if
you wait six months,
there's no way we're going
to find the signature
because it'll be long gone.
So the way we worked
this out is we
had to sign an
agreement with them.
And they signed an agreement.
It's this one huge
layer of collaboration.
We signed agreements with 100
different astronomy groups
that they would let
us know when they
find an observational
rating, we know as soon
as possible, even with
the degree of certainty
that they have at that time.
And we can do our
observations quickly.
But then we have to wait for
their OK to publish our data.
They say, only once we're
sure two months later,
then we can all
publish our data.
10 hours after this
happened, we were
sure it was real because
we had seen the kilonova.
But they still needed to work
on the data for two months.
And so everyone worked on
their data for two months.
And then in October,
80 papers came out
at the same day
about this event.
And that was all
only these groups
that were in the agreement.
Then the all the ones
that were outside, then,
started analyzing
the data after.
AUDIENCE: It was an
academic kilonova.
IAIR ARCAVI: Yeah.
[LAUGHS] It was.
Yeah, actually,
we have a webpage
that we made of
all the 80 papers,
if you want to see them,
and sort them, and look
through them because we
all get lost in that.
But it was really a
clash of cultures.
They do things very
differently than we do.
And there's one paper
that we wrote together,
which has 3,500 authors on it--
1,000 from LIGO, 1,000
from the people trying
to detect neutrinos [INAUDIBLE],,
and another about 1,500
astronomers across these
100 different groups
writing this paper together.
I was one of the people
on the committee trying
to get this to work.
And [INAUDIBLE] it was really--
they should just do
research on just that.
AUDIENCE: How long was the
paper with the 3,500 authors?
IAIR ARCAVI: Well, including
the author list, or not.
[LAUGHTER]
No, the paper is,
like, a summary
of everyone's observations.
And it points to everyone's
papers for different things.
So I don't know, it's maybe 20
pages or something like that.
But the author list
is actually longer
than the length limit for
papers in that journal, just
from the author list.
And it was funny,
When they sent it out,
they said, we think there
are about 3,500 authors
on this list.
But we actually don't
really know because somebody
might be in here
twice, and someone
needs to do just do a little
research on the author list
just to figure out if it's OK.
In particle physics, they
do this all the time.
In astronomy, this
was totally new to us.
So it was an interesting
cultural experience for sure.
AUDIENCE: Why did they need
months to double-check when
y you had evidence hours later?
IAIR ARCAVI: Yeah.
I mean, this is how they work.
Even the two-month schedule--
AUDIENCE: They
didn't believe you?
IAIR ARCAVI: No, no.
They believed.
They send out this
thing saying the false--
they give a false alarm
rate quantity on the alert
that they send out.
And this was a false
alarm rate of 1
every 10,000 years, which means
the chance that this is not--
we get a signal like
this that isn't real
will happen once
every 10,000 years.
And we saw the kilonova.
It all worked out.
But still, this
is how they work.
For them, this was a
really quick turnaround.
For us, it was excruciating.
And I should say, another
thing that came out of this
discovery, which I think
is not less important,
is definitive proof that
astronomers cannot keep
a secret.
We were sworn to secrecy by
the [INAUDIBLE] agreement.
This is a tweet that
came out August 18.
We didn't even wait 24 hours.
And Craig Wheeler,
who's a professor
at the University of
Austin, put out this tweet,
which he later retracted.
But in astronomy, we're
not built for these kinds
of things at all.
The space telescope, you
can go on this website that
tells you what the
space telescope
Hubble is looking at right now.
So when people train
the Hubble, then you
have to put in a name for the
target, and the person who
[INAUDIBLE] neutron star merger.
And then this automatically
viewed on their website.
And they were like, who
looks at the Hubble website?
We're fine.
No one looks at it.
Except we had a Twitter bot
that was tweeting everything
the space telescope
is looking at.
So as soon as you
get on Twitter,
like, two, three days after, oh,
I'm looking at the BNS merger.
And here's a picture of
what that looks like.
And everyone who is
not in on the secret
was like, wait, what
is going on here?
And so rumors started flying.
So this is a great example.
You know how everyone
says NASA's hiding aliens.
We are not capable of even
hiding a neutron star merger.
There's no way we could
keep quiet about the aliens.
But that was another
part of the culture clash
that physicists were totally
shocked that this happened.
Yeah.
AUDIENCE: I was hoping that,
given you had a use embargo,
you were able to go to
see the solar eclipse.
But it sounds like
you were busy, anyway.
IAIR ARCAVI: I totally went
to see the solar eclipse.
It was the most amazing thing
I had ever seen in my life
because the telescopes
are fully robotic.
Once I told them
what to observe,
we were actually-- once
we found the kilonova,
we had our telescopes
observing that closely.
But we also had other telescopes
looking in other galaxies
because we didn't know
yet, is this a thing,
or is this going to turn
out to be something else,
and we'll miss it happening
in some other galaxies?
So we actually have coordinated
them, so nine telescopes,
some of them looking
at the kilonova, some
of them looking
at other galaxies,
coordinating between them.
And I was watching the
eclipse because it's all
done by software.
Yeah.
AUDIENCE: Do you think the
astronomy thing was just
an organizational issue?
They had 1,000 people with
jobs, they're paid to do things,
and it took them two months
for someone say something?
IAIR ARCAVI: No, no.
I mean, they were
working on-- the thing
is, they wanted to
coordinate the publications.
If they discover something,
and then some astronomy group
weeks later is the
first one to publish,
they lose the credit for it.
And I can understand that.
They've been working for decades
to make these instruments.
We came up with this
project six months
before this happened, put it
together, wrote the software,
and discovered the kilonova.
It doesn't make sense for me
to publish it before them.
So they're [INAUDIBLE]
organization.
They move slower.
They want to make sure
that they're the first ones
to announce it.
And then they allow us to do it.
A nice thing that we
did manage, I think,
to convince them
for next year is
that the alerts are going to be
completely public immediately.
So no more of this
secrecy stuff,
which we've proven we cannot do.
And also, since these things
are brighter than we thought,
actually, amateurs
with small telescopes
can be the ones to
find the next one.
And that's great
that it's public
because an amateur that
has a small telescope
might be in at the exact right
place at the exact time right
time to find it
before any of us do.
So [INAUDIBLE] happen,
it's going to be public.
And then it's just
going to be a battle
to the death between
the astronomers who
publishes first.
In one sense, this
has allowed us
to know, no one else is going
to publish this in the next two
months, so we have time to
all work on our papers for two
months, and then get them
out synchronous the same day.
But the next one's
going to happen,
I don't know the Harvard
team or the Caltech team
are going to put out
a paper in three days,
so I'd better be quick if
I want to be in there, too.
AUDIENCE: Thank you.
SPEAKER: Thank you very much.
IAIR ARCAVI: Thank you.
[APPLAUSE]
[MUSIC PLAYING]
