Our first speaker is Professor good
to see maker from the Center for

relativistic astrophysics and

she'll be followed by Professor Laura
card not a Also from the Center for

relativistic astrophysics and they will
be talking to us tonight about general

relativity This is the one hundred
anniversary of general relativity and

we just have a brand new awesome statue
out in the quad you may have walked by and

so we hope you will learn
something tonight to help connect

you to that statue and to physics if you
have questions at the end we will pass

around the microphones and you can ask
questions if you don't get a chance once

the talk is over you can come down to
the front and meet with the speakers.

All right sort of OK.

All right am I on Probably I'm pretty loud
without a microphone so go like this if

it's horrible So hey obviously we're
really into Einstein here are a little

insane Stachel we're going to talk about
one of the three equations on the book but

before we do to get a sense for
where we are in the audience

what the Fed will do that more often that
be fun just dance around you know ready

Welcome to the fleet.

What does relativity mean to
you harder Quezon store or

they've rumors and they want to answer.

It's just like class but
there's hundreds of you.

Someone's waving he doesn't want
to hand up right there I don't

read what is about to the media.

Right now I like him it's like my
practical application Yes sir it does

we will see that in a second maybe as.

Now.

No cipher fans Yeah back then the gray.

Yeah different speeds for different
observers will talk about that too

about equations I'm not that mean
there's a quiz there's no quiz.

At the end of this and you also.

Volunteer yes or.

You're not sure where you are at the
Heisenberg Uncertainty Principle relative

and I'm.

Sure we can use it though.

So here's what I thought it might
be to some people sorry girl

Paris is in the front row she's going to
kill me like never send Dierdre images

that you make She painted this image and
obviously I like it.

The point here is we all
recognize that face Joey it's so

funny how a physicist could be that iconic
his image that a group of people who

would probably not tell you that their
favor sub favorite subject is physics

especially introductory physics or
though Dr Greco is the best teacher that

we saw all recognize this face we also
might recognize this is what I grew

up watching the reruns of the original
Star Trek I wasn't actually watching

the original Star Trek anyone
know it was powered by.

Dilithium crystals and the next
generation would have a right warp drive.

So I let them crystals drive so on they
would curve space time to get themselves

to move fast free so this is one way
that we think about relativity so

another anyone see this movie.

And are stellar.

So relativists from Cal Tech they have all
the fun was it was one of the executive

producers of this movie and this image is
of a warm hole that of course they use

to travel to a distant part of the galaxy
where there is a gigantic black hole which

we'll talk about a little bit later and
this image is actually pretty accurate for

what curved space time looks like if you
were to go through a wormhole Now full

disclosure we don't have any wormholes
we can't keep them open with the physics

of matter that we know of but
they sure are cool looking.

So what is it I can't really
control this what is.

Done to an astrophysicist its job
long word it's hard to say a lot but

what do we think of.

For us we see it as something that's
driving modern astrophysics so

we're I'm not going to spend too much time
unfortunately on cosmology an expanding

universe is although we do have another
faculty at the center who works

on cosmology but it was one of the big
solutions to Einstein's equations of

general to Vittie is cosmology and how is
the whole universe forming and expanding

my personal favorite black holes is one of
the solutions of mine finds relativity so

all talk about them this is a black
hole image the image of the way a black

hole distort the light we view
from the Milky Way galaxy so

if you put a black hole between us in the
Milky Way This is what you would see so

you see you can't see in the middle
obviously black hole but you see the light

from the full light spectrum of
the entire Milky Way you still can see it

is just distorted and coming around
the black hole because it curves like and

my colleagues will talk about her
favorite thing gravitational waves and

a few minutes so here it is my
one slide of Einstein's best year

of his life he wrote five papers I
wrote down four of them up here and

I'm going to Einstein statute talks a
couple of PA You'll know I got these from

because I stole the slide from public
Laguna and you recognize far too many so

you might want to escape soon.

So it's just a was an amazing period
of time if as a physicist I think any

scientists even a small part of one
of these papers have been enough

to make a career let alone all of them but
what all focus on is this last one

special relativity so the phone
logic of fact got in the Nobel Prize

from emotion superimportant
in many areas of science and

engineering equals MC squared one of the
equations in the book of our new statue

special relativity is where we'll focus in
fact I'm going to focus on general instead

of special because it is not two
thousand and five writes When

fifteen and from special relativity
you get those cool effects we're.

Talk about I don't know your
names of the people answer but

you know the cool effects of time
dilation and length contraction

that you learn in class but also you
realize that all the natural phenomena he

could be discussed in terms of special
relativity except for gravitation and

that's why we need a new theory so
here it is kind of wordy I apologize

I love this because how do you get your
happiest thought is this I like it

I think that we should embrace that
here so a translation of what Einstein's

happiest thought was that he realized that
a gravitational field only has a relative

existence if you thought time was bad
enough well take away gravity because for

an observer freely falling
from the roof of a house or

whatever you want to jump around on when
you feel if you jump from the roof of

a house with not a dog that seems
mean with a stuffed animal and

you throw it I don't know what you do OK
you win your dog jump there's no easy way

to do it and as you're falling you
look at each other it seems like

there is no gravity until you had the
ground the normal force is what kills you

so it's as if there is no
gravitational field and

what Einstein did so this is that scenario
I'm in space far from any stars I don't

have a window I'll feel the same as if
I'm freely falling towards the earth

Interestingly if I put that elevator with
the Scooby Einstein on the earth with no

windows he could conduct an experiment
like dropping something and conclude I'm

on the surface of the earth I understand
physics enough but if I stuck that

same elevator in a rocket and accelerated
at nine point eight meters per second

squared if you conducted that
same experiment he'd come up with

the same results and he would think
even though he's Einstein because on

the surface of the earth despite
being out in outer space.

So this connection seems so simple and

it's amazing how much easier it is to
understand relativity if you understand

this principle of equivalence because
it's a lot easier to calculate things and

accelerating field than on
the surface of the earth.

So Riis.

Why it's called general relativity
is because Einstein saw this

as a generalization of the Galilean
principle of relativity.

So let's get a little more
modern Here's our book.

This is the equation on the book
physicists today tend to write it like

this.

You see relativity is easy looks a bit
like a fraternity or sorority party.

It's not a problem I don't know
what you guys are worried.

It's got a lot in there it's true for
the hardest equations to solve I think.

On a computer but what it tells us is
it tells us that spacetime curvature

this grid that we as we like to represent
it tells matter how to move this for

the Sun It tells the earth to go around
the sun instead of out in a straight line

and matter tell space time
you should curve like that so

there coupled and ever present for
dimensions of space and time and

they're not linear and messy but
you don't have to solve them idea.

So OK so let's go on a little further
one of your favorite consequences of

relativity was this time thing
that seems really cool so

I also saw part of the slide
from probably going to and

then he's the Jose Maria person so
here we have a rocket.

With Maria shiningly she's going to
receive the green pulses from Jose and

Jose is going receive.

Sorry because they receive the green
pulses from Maria and Maria receives

the blue pulses from Jose and you ask
yourself if your friend was at the top of

a rocket shining light down at you would
you expect you to read different clocks if

you clock the pulse reaching you is there
any expectation it would be different.

When we tell you so the answer here is
that someone at the top of a building

age is more than someone in the basement
is the easy way to think this so

where you want a gravitational
field affects the way time.

Ticks off and if you think of your heart
as a clock similar so we can get that

same effect it's easier to think about if
you think about the rocket as accelerating

you could probably believe that this is
true because of course says that light

front is going down the rockets Babar
Maria is is accelerating towards it so

she reaches the signal faster and
faster as Jose signs the light so

that's how we use the principle of
equivalence to make it easier to

understand a concept that's so hard to
understand the surface of the Earth

why would a strong memories of
the top of the building be older than

the experimentalists in the basement and
this is how we do it but

there is another consequence which front
comes from Special Relativity which is

speed so if we take this rocket and
have it moving at a uniform speed

I have to take josé out of the rocket
I put him in a suit so no.

Because if they're both in the rocket
they're not going to see an effect

because they're moving at the same uniform
speed is different than when they were

accelerating with respect to
each other in the same so

now josé maría will also
disagree about time and this

time the person moving will appear younger
than the person holding the clock and

standing still so if you move fast
you might say you age less so

you have to be low gravitational field
moving quickly if you want to be younger

than somebody doing the opposite
that's the plan OK So

gravity we have these to cool
a fax somebody is nameless so

sorry about G.P.S. we have these
Mundine the facts because of this

really fantastic concept of curved
spacetime the fact that matter and

energy tell space of a curve and spacetime
tells matter energy how to move we have

apples falling that's pretty mundane but
it also causes this beautiful travel

destruction that will see in a second
of a star being eaten by a black hole

same same stuff just gravity and
it also works with.

Your G.P.S. on your i Phone So if you did
not correct for the way that time changes

depending on the gravitational potential
and the speed of the satellite suspect to

your receiver on your phone you would lose
forty five microseconds per day from G.R.

and seven from special relativity and you
see how the signs are different because we

notice that the Pens and
what you're doing but the signs are so

you lose about eleven kilometers a day so
you would certainly not make it to your

plane on time if this is if you
didn't correct for General David.

So it's got a little deeper and

black holes because that's
the cool part I think.

Anyone see this kind of image before
describe a black hole Yeah right like this

I call it a trampoline a fact one of my
kids is bigger than the other side you so

I was pretend he was the block
on the curve the champion

the other little kid
wasn't as big a fault or

it's and it wasn't nice and
because you know those kids.

So once a seventy year senior is
not here I can make fun of them so

what we have here is a solution of those
equations G.M.U. equals a party knew

the simplest one you could think of even
if you're in a trench in war was obviously

you do util that let's take the spirit
with symmetric solution that's make time

Independent get a solution this
illusion was something nobody liked

Einstein Oppenheimer big powerful guys
very uncomfortable because it said that if

you could collapse matter all the way down
to a point or really to a region where

nothing else could support it you would
reveal an actual physical singularity

this is before we knew about the Big Bang
we have to physical singularities and

they just thought that that was
not possible physical reality.

But this is what we have so
here is just for fun.

We're so popular in the media these days
that physicists like to show Big Bang

theory so don't jump into
a black hole true story right so

they are ubiquitous in the universe is for
going to find out but I am.

In popular culture so it is true that
black holes have this sense that nothing

can escape them and that is true you have
to go faster than the speed of light

to escape the gravitational pull if you're
within the event horizon of a black hole

OK We call this spaghettification it's a
very fancy word I think I spelled it right

it means the just tidal forces that if
you're approaching a black hole if you get

too close even before you had the event
horizon the tidal forces you feet would

feel compared to your head if your feet
first would cause you to stretch out and

also there's a lot of information
available black holes if you fall into one

don't struggle you'll die faster so
I'll get advice and

I want you to be unprepared So
black holes they sound really cool but

are they just figments of board
astrophysicists imagination or

are they actually part of our universe
that we deal with so the truth is is that

we consider big stars or
how we form stars the universe and

if you play with how much the initial
mass of that star is depending

on its life cycle its details it
actually has a path they do form

a black hole when they run out of fuel and
basically die so they can become a few

different types of stars there are others
appear if there are low mass less massive

than our sun our sun will not become a
black hole in a trance starts to small but

something you know two to three
times the size of our sun or

even bigger could become a black hole so
this is easy path to form a black hole.

And here is a different kind of buckle
this one will be little bigger than

the size of our sun This one could be like
Gargantua on a million or a billion times

the mass of our sun And we believe these
lurk in the middle of our galaxies most

galaxies seem to have them so let's
look a little deeper at these things.

So I've used this joke too often probably
even some of you have seen it if you hang

out on me too long but so do I like
the fact that we're all wearing lab.

I don't know why an astronomer would
be in a lab coat get dirty I'm not sure

it's no chemicals astronomy and
they're looking at this picture

they've taken with the telescope of a
black region of a black hole so it's black

It looks like a hole I say it's a black
hole not the way it actually right so

how do we say if we tell you what we think
black holes are everywhere in the universe

why do we think that well it's because we
can see the partner dancing with the black

hole we see matter falling into it it
gives off a lot of energetic phenomena and

that's what we're detecting not the black
hole itself despite the beautiful images

we make up in popular culture so
we can be small like this

image of ten saw a mass pothole
eating its companion star or

it can be million times like the one
in the center of our galaxy.

This is not a real image but
it's beautiful so

this is what it looks like that picture of
Cygnus X. one this is what it would look

like if we had a star disrupt if a star
and a black hole were orbiting each

other like we expect that they do because
we see evidence for them the star loses

its matter into the black hole and we see
all this shiny extreme material come out

it's just a beautiful movie of what
one of our expectations of black holes

acting in the universe I found that
like Google Google's powerful.

So here's another image this is real data
you can tell because it's not as pretty.

So good looking as pretty so it's real on
these are actual orbits of stars around

are all cute little black hole look
at that star this is about the size

of our solar system this is in the middle
of our own galaxy Milky Way And we

have our own black hole about four times
four million times the mass of our sun and

you can see these orbits are so tight and
there's nothing there nothing shiny that's

our own black hole so this is some of
the best evidence around for a black hole.

OK So we want to get to you.

Portion of this tag team event so
I'm going to tell you

in the end of the last couple slides
about what I do for a living.

Which is I take two black holes and
collide them because one just isn't enough

so I take that star that was setting
its material on the beautiful image and

now I put it as a black hole as well so
I have two black holes orbiting each other

and their fate is to merge
into a single black hole and

when they do that they're giving off a lot
of radiation but nothing that we can see

it's not electromagnetic radiation and
it's something called gravitational waves

which will tell us about next so what this
is is a fake star field because that's

just too pretty to be real data fairly but
the gravitation wave these beautiful

white lines coming out of those two
objects are the gravitational waves that

we actually find when we solve Einstein's
equations the problem I sense equation

see an image different star background I'm
different colors you'll see the gravity

is waves come out in a second
the Einstein's equation I told you.

You seem so simple but
they're super hard and

even the two body problem can't be solved
pen and paper because it's non-linear so

you can't just take one solution short to
a black hole at a second black hole and

it being two locals now non-linear doesn't
work and instead you take twenty years and

all the super computers you can get
your hands on to create the solution and

this is what it looks like at the end of
the day this is the gravitational wave

signal in time that is going to talk about
with what we're trying to attack today.

So instead of this is my favorite
magazine cover ever because

we're always like doomsday devices when
black holes collide their slingshot

in a frantic deep space journey why
are the bottles frantic I don't know.

I love this kind of stuff it's great but

now we're going to switch gears and
you'll hear about gravitational waves so

all we'll take questions at
the end if you guys don't mind.

Thank.

You.

For the.

Form.

This is it it's great where
you're funny take literally

I should put it on that
slides have at that OK good.

All right so it's going to be
hard to follow the results so

I'll be much calmer this.

Obvious thing here.

So so what I want to do now is to talk
you more about gravitational waves which

I call here and sense messengers and
why we're trying to the track them and

and how and possibly when.

So.

So this is an image from
the Hubble telescope

this is a very high resolution
image of the universe and and

that's probably what you think about when
you think about the universe out there.

Or a point or so

there are there are galaxy is there are
stars it's out there and you can see it's.

The image of the universe that instead I'm
saying gives us is something that will

be different it looks more like this so

generally City explains gravitation
in terms of distortions of space and

times and we can picture
the universe like going to greed and

big masses what they do is to
distort the spacetime and so for

instance if you have
a if you have a black.

Star or a heavy object it bends
a core of spacetime like this

this could be the Sun This down here is
a funnel that what the black hole would be

it's a Muslim article solution that.

That looks at how what's
the shape of space time of this

space time where you would find or
coordinates.

Whenever something catastrophic
happens in the universe so

when two black holes collides like
you saw in the simulations there

what happens is that all of this is just
like when you throw rocks in the water and

the surface of the water makes waves
the same thing happens with space and when

when you have a big explosion supernova
you have a collision of black called Stars

are the result is that we have ripples in
space time and this ripples according to

Einstein travel all the way to
us at the speed of light so what

we're trying to do is to find on Earth
the echo or whatever happened out there

when the catastrophic events happened
going all the way to the Big Bang.

So.

This is a.

This is another simulation.

Similar to the ones that showed you
earlier what I'm going to show you now

it's a one of these calculations of
the gravitational waves that are produced

by the collision of two black holes but
what you're going to see with it is

what what kind of sounds does
this gravitational waves make so

we can just wave like everything else we
can plug into a speaker we can listen to

it and if we can find them we can hear
the sounds of colliding black holes or

explode in supernova so in particular
when we go after when we're looking at

collisions of black holes if
the idea works this is what we would

hear.

So.

So we can now think about having
a new way of observing the universe

that uses a different type of
messengers waves everything we know so

far is coming from electromagnetic waves
gravitational waves are going to tell us

something else are going to tell us things
that we cannot see so what happens when

two black holes collides what happens
inside the core collapse supernova so

in a way really once we do we can
measure dissuades we're going to have

a new sense to perceive the universe
around us and so we're going to be able to

combine electromagnetic waves and
habitation waves and

get a new perception of
the reality of the universe.

So so
what can we learn about the universal so

there is a lot of things
that we can we can go after.

Because they are an entirely new
way to probe the natural universe

they're coming from the motion
of big masses as opposed to

electromagnetic radiation which is
coming from the motion of charges.

And so we can do once we discover them
we can do some physics we can now we

can answer questions such as is generally
the correct theory of gravity may

be honest and was not right after all we
just have not been able to disprove him.

How does the matter behave in extreme
gravity conditions so we're really happens

inside a black hole are black holes really
the black also general attributes in

what we have so far a mathematical
solution of the equations but what's

really happening inside what's the matter
doing we can do is throw physics and

astronomy we can go after questions
such as what's power in the gamma ray

burst those flashes of gamma rays that are
being observed and there are the bright.

Servants in the universe
how do stars explodes

how many black holes
are there in the universe.

Do intermediate mass black holes
even exist how many are there and

we can do cosmology can we go after the
rest of your gravitational wave there's

still rippling out there from the from
the Big Bang so this is a real pleasure of

physics and also physics and cosmology
all questions that are still unsolved and

that once with a tag with
additional way we can go after so

that's why we're excited
about measuring them.

Now how do we do try gravitational
waves so general activity is.

A geometry theory and

physically the way we can go after
them is by looking at strains so

changes in land relative
to the land itself.

So I way that we can go after measuring
them here on earth is by taking.

The arms of think about this
as a clocks as a clock and

the two arms of it as a gravitational
wave is coming towards

the screen after a quarter of the period
of the wave this circle is going to have

stretched into an oval after another
quarter of a circle is going to go back to

a circle itself and
stretch in the opposite direction as on so

because gravitational gen to Beauty
is about the geometry of space and

time Gravitational Wave stretches
of squeezes spacetime so

if we can measure the changes
in length in one direction and

in the other as a gravitational wave
comes through then we can go after

the gravitational wave
itself is the right.

OK.

Now the challenge here is that
the gravitational wave is a wave

is propagating into a medium
the media is a space time and

space time is really really stiff so

a tiny tiny wave can carry a lot of
energy so there is a lot of fun to just.

Reviews in this big traffic events that
are astrophysics are putting out there but

the changes are really small
ones they are regions.

So we had to be creative into how to
go after measuring these changes and

so that's where the project that I'm
working on the laser interferometer

gravitational wave of sort of a Tory and
there's a game so

I'm going to show you a little animation
of it's a very simplified cartoon of

of the principle under which like a works.

On a star.

You can choose this OK so the idea is
that we have a laser beam they get splits

at the center of like the mirror travels
along two arms there are perpendicular to

each other they get
reflected they come back and

they recombine but things are aligned
in such a way that the interference

of the to recombine beings is destructive
So the two cancel each other OK So

this is all the experiment is set up now
as the gravitational wave comes through

what happens is that the two arms are
stretching and squeezes and squeezing like

in the car still not sure before and so
as the gravitational wave comes through

one are becomes longer the other shorter
and so on with the period of the wave and

so the interference pattern changes and
so we get some lights coming out and

we put a photo detector here to
see how much light is coming out.

So if we can.

If we can build that attacked or that's so
accurate that nothing else disturbs

the measurements then we can measure
the passage of the gravitational wave.

So that's the principle still
is it OK now I told you

these things are very small so
this is the challenge.

For the title for us or a physical
source is that we're going after so

the collision of two neutron stars or
two black holes.

The kind of signal that we can hope to
see just because these things are so

weak is of a delta of a strain of ten
to the minus twenty two now that's

a really small number this is equivalence
of measuring the distance between or

and the close a star by the resubmission
of the weight of a of an air so

that's that's how small does a fact it is.

The resubmission of power the tractor so

I was the tractor cannot be as long as the
distance between us and Proxima Centauri

if want to build something on earth
it can be kilometers scale long and

so we need to be able to measure
distances there are of the order of one

in ten thousand times
the size of the proton So

that's the accuracy at which we're
going this train so this this kind of.

Points gases are organisers are in
here I can't even count them so

this is a very accurate measurements that.

If you want to be able to do it go this is
very challenging because we need to fight

against everything else that wants to
change and move those mirrors more than

a relational wave does guys so that's why
I like is such a difficult experiment.

So this project has been going on for
a few years now

there are now through the TAC
to us that are operating.

A part of the Lego project so
one is in Washington states and

the other one is closer to
here is in Louisiana and

the two are separated by
three thousand kilometers and

that means that wave travels
from here to here at most it

takes time milliseconds so that's the song
it takes to go along the Great Circle.

It's a National Science Foundation
projects

the construction started now fifteen or
twenty years ago.

And the operation started in two
thousand and two so I've been taking.

Data for eighty years and
then we stopped for upgrades.

We are now part of a large collaboration
that has about a thousand members so

it's a large It's a large community eighty
situation Georgia Tech being one of them

it crosses sixteen countries so
this is really worldwide efforts and

we are actually not the only
project like this the results so

we are collaborating with a project in
Italy that's called Borgo there are plans

to build a detector in India and there is
an ongoing project going on in Calgary so

this is a worldwide quests different
project different experiments and

together we are aiming at the tact in the
gravitational waves to solve those physics

and us are physical questions
that I mentioned earlier.

This is what the data looks
like this is the data from.

The first run so
this was acquired five years ago.

This is the kind of this is that we
have as a function of frequencies so

this is the audio band between
one hundred Earths and

the Q Norths this is the opposite
spectral density and

what we need to do is to do data
analysis to find the signatures

the signals that are due to collapse
supernova so this is what a signal for

McCorkle up supernova looks
like from mergers of.

Neutron stars or black holes.

Echoes from the Big Bang or
the rotation of pole source so

lots of what we do is to really dig
through the data to find the type of

signal does life by sources
there are in the galaxy or

all the way out to
cosmology called distances.

Just some pictures what I showed you was
a really simple Course shown in reality

in reality the experiment is
much more complex there is.

This is where the laser is we have
a complicated system of optics to

clean the the most of the laser This
is a semi reflective mirror and

then the arms are actually
four kilometers long.

You have some pictures this is the mirrors
mirrors this are suspended this

are seismic as a nation to protect from
the motion of the ground the real trick of

the game here is to isolate our
signal isolates the nearest because

motion of the or vibrations and the type
of noise also want to move the meter so

we have to be really careful at
counseling and correcting the noise.

So so that that's what looks like now

when can we expect to find a way.

Well this is just.

Some simple scaling.

So if we consider the signal from the
collision of two neutron stars so that's

that's the one that we understand better
what starts according to the theory this

type of coalescence happened once every
ten thousand years per galaxy OK So in our

galaxy we have to wait quite a bit to have
one of these events happen in nearby.

So this is or this is where we see the
inside the galaxy this is where the galaxy

sits inside the range that was visible
to initialise ago so up to five years

ago we were sensitive to gravitational
waves from one hundred galaxies and

we didn't really see anything but that
was not so surprising because the initial

initial like around was more to
prove that we could do this.

Now in the current configuration which we
called advance like we can actually reach

out to one hundred thousand galaxies so
this is the reach of advance like

this is what we are probing as I speak so

this state Iran has just started
this bus the Tambour and we are now.

We're being at acquiring data from
most of the visible universe.

So we are expecting the actual
rates which is on the order of

one of em's per month once about
flood with a full sensitivity so

we aren't really now on the brink of
a choir in this or that according to

the prediction will yield the first
gravitational wave signals.

This is just to show you that you know
this is right now we're in this force it's

taking we are acquiring three months of
data we're going to be do another run next

year one day or later and so on and in two
thousand and nineteen we're going to have

a full network of gravitational wave
detractors where just like with a G.P.S.

we can actually triangulates and
identify what is the origin of our signal.

So.

They want to my goal here is to
combine the signal from every dish and

waits neutrinos and photons which
are the messengers from a electromagnetic

waves to really get a complete picture
of what's happening out there so

what's this this image
is the image of a burst.

And it's thought that this kind of
event is due to the collision of a star

with a black hole so little star
that's it an hour by a black hole and

it's producing this big
flashes of gamma rays.

It produces neutrinos to produce photons
and it produces gravitational waves so

in this new configuration we're now going
to be sitting here on Earth with one two

three The tactile so this is the to live
on this is the Virgo and then we can add

this attack to really sit there like Big
years they're just waiting for something

to come and then if we can triangulate
between the arrival time it's one two and

three detectors we can reconstruct
where the events was produce send

information out to Southern Lights and to.

Telescopes we're going to do
a follow up in the electromagnetic.

And so we're going to be.

Able to come by electromagnetic waves
the gravitational waves to get the full

picture and so we have established
all this in this connection with

the observatory is to
do this with our first.

So.

Brief so
likewise now resume the search for

gravitational wave just this past
September we have now fresh data we

are allies in August and
they get a fine get and

and who knows maybe I
would be able to announce

that we have the Dr with us always stay
tuned hopefully we can come back and

talk about the results so in the spring.

Thank you

thank.

You.

We have time for questions if you have
questions raise your hand I'll bring

the microphone to you should
everyone can hear your question.

How quickly do gravitational waves travel.

Trouble the speed of light so yes C.

In fact that's one of the things that
if that were not true that would be

generative it is it's one of
the things that we want to make sure.

Why do they travel at the speed of light.

That's so hard.

As that somehow becomes my question and
I can't and basically because there.

If you assume that it's mass is like
a photon it travels at the same speed as

the photon but it's basically a spin
weighted field of something crazy

let's ask.

Where is the the next person to
mention yabber hand over here so much.

As neutrinos are minute by
supernova are they subject to the.

Gravitational.

Are they subjects or are they sucked
in by a black hole like photons or.

So the neutrinos are emitted in
the first stages of the collapse so

they they can escape I mean it's
just emitted in the first stage

before the problem of the stars so
we get to see the signal even though there

is a black hole left behind OK but there
radically speaking if they crossed a black

hole's event horizon with a beef
I guess if yes they would be but

in the core collapse they escape
before the black hole is produced.

If a gravitational wave was discovered
tomorrow what would be the biggest

implication on on us.

Right.

Now I mean it's so so I think.

The most likely source is
the gravitational waves

are going to be the collision off
a neutron star sort of those are in

the black hole of the black holes so
what that would do is

to open a better understanding into
this US vs to physics of the sources or

better understanding of the population so
many black holes there are lots

of this projections are based on
the observation of one or two systems so

lots of the Astronomy is based on just
a few examples so I would just give this

additional information to start of
the coding of the physics of it

now if we can actually the codes
the signal what have not been talking so

much about in this way forms
that are produced that showed

little we goals or little changes in
the way form shape itself are associated

to the physics of the event itself so
we could be able to

understand better the question of states
of the stars for instance and then.

Would give us some clue into
neutral nuclear physics also

on the ground based on the scale so.

So yes there could be consequences also
for nuclear physics but that's you know

that without more than one so the first
thing is just a physics it would rock or

have to happen and
would be crap for everyone.

Do these waves lose amplitude or strength
with distance travel from source to light

go for instance Hubble photos show at
least a hundred billion galaxies out there

extents and you're measuring a hundred
thousand beds being able to see

these waves as we see the photons from
Hubble you know when you give you more

examples more chance to see these waves.

This this events are pretty rare right so
what I was showing is that

liveliest kind of now spanning order
of one out of a thousand galaxies and

in each of them there could be one of and
then thousand years so

we're talking about one or
two events per month that's why I saw for

the hundred billion measurements
could you where they have strength

when they get here from the further
reaches of the universe as our strength so

they do they do it when you measure
them they still have them to do

they fade like photons they
they propagate they OK so

what we measure is the amplitude of the
string itself so it's kind of a scale star

like one of our right so that's
the that's the extent of the scale so

if we can get ten times more sensitive we
can get a thousand times more volume so

it's a one off for
our spreading it's really like with

photons.

So I'm faster maybe and either work out.

Their thing or.

Does this help us
understand dark matter and.

Just totally unrelated.

This is fun.

And that's pretty unrelated I
mean let's let's imagine that we

don't detect a gravitational wave or you
do and it doesn't come out with the speed

of light or there is an extra polarization
then it might make a difference right

because then you'd say General to he's
not the right there you gravity and

now you've opened up the Vista to start
spending dark energy if it comes in and

nothing's unexpected then then
we're really doing astrophysics.

But I think I think the first
measurements are going to be you know.

Kind of in the from the close by Universe
we're going to start from one of two

events so I think once we get bigger
the doctors more sensitivity at that point

we can kind of this kind of studies
with higher rates of events and

published understanding.

OK.

It was a pair of arms were
two like ways meet and

then they cancel each other out is there
any benefit to reflect him around back and

forth before you join him again Yes yes
I actually do we actually do i gave you

the simpler cards to wear that travel
back and forth but we actually do.

The bouncing back and forth is about
one hundred times so yes we do that and

that's one of the power in the cavity and
the more power you have

the more photons you have in the system so
it reduces the shot so

it's all related.

OK you talked about the formation of
like who should stop the collapse

what about super massive black hole.

Not because I don't have them good idea so
super massive black holes are harder to

explain their formation is one of the big
challenges in astrophysics right now and

I actually have a lot of
people working on that.

Some of the center but you can imagine
super massive black holes would grow

from very early on in the universe they
would grow through mergers they grow

from accretion they would form in like
the early dark matter pockets that happen

after the universe is expanding and
they just keep growing and

they form at the center of galaxies that
way they collide as well potentially if

two galaxies collide there are so massive
that lie go on to attack them there

are different frequency we would barely
hear them like we did those gravitational

waves if a space space mission gets
launched like Lisa Lisa that's the black

holes we would be looking for super
massive black holes clouding those we can

see all the way out like really early on
in the universe to be able to check them.

Does the moving of earth or space and and
the solar system affect your ability to

detect the stuff because of the changing
gravitational forces on the earth itself.

So that's a smaller foxed
scamper to other noise sources.

Gradients it's actually no
it's one of the major or.

The biggest source of trouble for
us is actually seismic motion

the fact that the detector is sitting on.

Our north and Dorothy is moving on so
those seismic motions are the biggest

problem and that's why lots of engineering
has gone into seismic as relations for

instance and understanding you know
the result of feedback loop and.

Really lots of engineering
designing something that stable

against vibration and seismic motions.

If we have a last question
over there danger

I'm just running between the aisles for.

You.

If there's so much trouble with seismic
motion would it be easier to send it into

space right so that would be Lisa Actually
there are there is there is this is

another project that's.

In the works for many years I think the
current plan is to send it to space in.

Two thousand and twenty five or
thirty five twenty five right.

As they head around so so
once you're out in space you don't have

the problem of seismic motion and the idea
is also if you can put you know all

the mirrors are actually
standing in spaceships so

you can put them very far apart from each
other and so that's why it's going to be

sensitive to smaller frequences and
go off their super massive black hole so

it's going to be doing a different type of
physics that's actually part of what was

challenging the Lego that we know what
about super massive black holes but

the black holes that we are off there are
smaller and we don't know as much about

them so it's really really being in
the spirit it's all for exploration

of a little bit of the unknown because we
don't know so much about the sources that

we're going after is going to be doing
a different type of physics and it's going

to benefit from not having seismic motion
there noise is somebody else a source

which is literally gravitational waves
from school I think it's pretty amazing.

All right.

Thank our speakers.

Thank you.

THANK YOU THANK YOU have you come down
to the front afterwards thank you.