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hi

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on thank you for coming it's such a nice
day raining

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not raining raining not raining I'm

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thank you for coming this is the third

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in the revamped lecture series the
public lecture series

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on Wednesday nights at Harvard have and
this is kinda exciting when

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gamma ray bursts on my favorite kinda
firsts a

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agenda and they're very very

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recently in in a astronomy there very
very interesting

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so I I'm kinda excited about this talk I
don't know everything and a burger is

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a a a professor in this trying to be
Department and he's actually the john l

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low but perfect associate professors
astronomy

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a he a comes to Israel but

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the went to school at UCLA in one whole
buncha prizes like

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best guy in this training department I
can

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you can read here is the actual the
actual a

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name a that's it stresses the e

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legions Prize for Outstanding graduate
and then he went on to Caltech which is

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an amazing

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at back to school in astronomy when he
did his PhD

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a he did number postdoctoral fellowships

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really interesting places and then of
course came the most interesting place

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here at Harvard where he where he

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a teaches astronomy 100 and where she

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a works on looking at gamma ray bursts
from

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many different telescopes which will
tell you about all over the world

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am and apparently he doesn't have to go
there just

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phones he's gonna tell us about that

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yeah I'm really excited to hear him talk
so let's just go ahead

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and hear about gamma ray bursts on it
thank you everybody for are coming out

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this evening

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%uh so before we start I have a
confession to make I am

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I love damn reverse I really do I find
them fascinating

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offer a variety of reasons I'll tell you
about tonight

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are first and foremost a they push

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astrophysics to its real limits

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so the objects that are involved in in
producing gamma ray bursts

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are things up the most massive stars in
the universe colliding neutron stars the

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birth of black holes

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this is really the extremes of what we
know about astronomy and physics and I

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will tell you in

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about today how we reached those
conclusions Aug demory burst also push

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astronomy itself to the limits
observational astronomy

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so most astronomical objects that were
used to you

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when we go outside and look at the night
sky maybe not on a night like this

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are there night after night right we we
always see the same stars

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same Andromeda Galaxy et cetera but damn
Reapers are very different

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they last for only a few seconds up to
maybe a few hours

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it so they push the way we do astronomy
into a very different direction we have

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to use the biggest telescopes in the
world

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on a very short notice and I'll tell you
today

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arm how how that are how that works

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we actually capture and study subjects
are

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but I think most of all I find gamma-ray
burst fascinating because day epitomize

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are the idea of scientific serendipity
on a discovery that was completely

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unexpected nobody has ever predicted
that Camry person exists

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they were discovered completely by
accident but that

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discovery really set of fight chase that
lasted for several decades and still

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going on

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on today I involving hundreds of
astronomers around the world and

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almost every single Observatory
existence and so what I want to do today

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is

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is take you all on this on this chase
that as

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I started about forty years ago and show
you what we've learned over the last few

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years

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now it's not about a dozen of

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arm then years on a motivation to think
about gamma ray bursts

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aren't so here's an article from Sky &
Telescope from few years ago

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art galleries do I why you should worry
about merging neutron stars

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and here's an artist's conception of
what would happen if a gamma-ray bursts

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exploded

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are somewhere in the Milky Way galaxy
and incinerate the earth's atmosphere

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okay so if if nothing I said so far
caught your attention

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out this year should really worry about
these things okay so let's set the stage

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before talk about what damn reverse are
let's

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talk about what gamma rays are so gamma
rays or formal flights they're part of

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the electromagnetic spectrum

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there were familiar with where are radio
waves at the longest wavelength end of

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the spectrum

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visible part of the spectrum that our
eyes are sensitive to you

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and the ultraviolet x-ray and finally
gamma rays is the most

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energetic form what with a wavelength
that's about the size of an atomic

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nucleus

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and and hence the large energy this is
really the most extreme form of

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I do we know about and one of the
important aspects of gamma rays that are

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critical to our

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story of gamma reverses that they cannot
penetrate years happens here

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now that's a good thing right the
atmosphere protects us from the harmful

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effect of gamma rays

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it also means that if you want to detect
any source of radiation that produces

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gamma rays

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we have to go about the atmosphere

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so our story of gamma-ray burst arts
like any good I'm James Bond movie

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starts at the

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at the height of the Cold War are the
early nineteen sixties

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on in the US and the Soviet Union were
carrying out larger and larger

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nuclear-armed

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test eventually realize this was not
sustainable

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and they decided to cease to sign a
limited nuclear test ban treaty in 1963

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and a critical part of the treaty it's
important to our story is that it

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prohibits prevents

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arm and to not carry out any nuclear
weapon tests in the atmosphere

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beyond its limits including outer space

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here's a picture president Kennedy
signing the treaty

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now does very little trust between the
US and Soviet Union about

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arm whether they will keep that treaty
particularly the aspect about

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a nuclear test outer space and so the
Department of Defense

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started a program called avail our
satellites

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shown here you can see these are
relatively modest size satellites

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there were designed to detect the
signature of a nuclear test in space

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and that signature is a burst of gamers
that will occur at the time

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the explosion

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now the launch the satellites in pairs
and the reason why is that using a pair

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of satellite secret triangulate the
direction from which in clear test

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i would comment could verify whether the
soviets

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I'll violated tree so they

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first of these very low satellites were
launched in 1963 and the program lasted

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for several years

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things are really exciting in 1967

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so the satellite my one of these
parasites was looking and suddenly saw

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this large burst

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gamma radiation that lasted about

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eight seconds okay so we played out
again because this is essentially

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would you be kind of an idea this is a
real time

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do but you know a gamma-ray burst in so
you can see how

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long they last so there is just nothing
and then for a few seconds

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a large burst gammons looking very much
like the signature of a nuclear

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explosion

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and so you can imagine that this created
a lot of our excitement

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all but then the satellites detected
another one and another one

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and another one and of course they have
the ability to triangulate worries

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explosions were coming from

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so eventually was realize that these
births were not due to nuclear tests

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they did not come from just outside of
the solar or the ER Earth's atmosphere

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or from the moon

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which was another are possible sites for
nuclear test

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so the information was declassified in
1973

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and three scientists from Los Alamos
National Laboratory published a paper

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in April 1973 observations of gamma
reverse the cosmic origin

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and a stated through primary factor in
particular

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one is that the durations of these burst
lasted anywhere from

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a tenth of a second only a tenth of a
second

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up to about thirty seconds so there's a
wide range of durations for the Spurs

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perhaps the more important fact the
directional information

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the ability to triangulate easy fence
showed that they

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did not come from our local part of the
solar system

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they were not coming from outside the
earth or from the song from

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okay so the reader in the other parts of
the solar system

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or beyond and this is really the paper
this is a very short paper it's only 45

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pages

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that set of this chase to study gamma
reverse for the subsequent four years

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so here's a gallery of gamma reverse
just to show you what we're talking

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about

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so each one of these diagrams is the
number of gamma-ray photon started as a

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function of time

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you can see that they come in all shapes
and forms some of them are very smooth

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they go up in just the Klein smoothly
some of them are extremely chaotic

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some of them are couple spike some of
them are many spikes

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some of them last for hundreds of
seconds and some other my shortest and

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most

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so as the saying goes in the gamma-ray
burst field if you see one gamma-ray

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burst

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you've seen one gamers a there's just no
regularity at all

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their profits now gamers are extremely
rare

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we detect about or we think there about
three gamma ray bursts per day in the

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entire universe

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out that may sound like a lot arm

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so to give you a skill supernova
explosions which are also

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relatively rare events 1 percent sure in
the Milky Way

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worker one per second in the universe
yes you can actually count I'm super no

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you can do one supernova to something
recent save mississippi

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and but just think about the throat is
killing one per second

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versus three per day these are extremely
rare evens

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okay so how is it possible that

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we never knew about gamma-ray burst and
we launch these very primitive

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satellites and the first thing we
discovered the scammers

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the reason is that they're extremely
bright and so to give you kind of a

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sense of scale how bright these events
are

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here's a map above the sky and gamers

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okay so this bright region over here is
the Milky Way galaxy

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that we live in and you can see that as
you move away from the Milky Way

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the sky demory's becomes darker and
darker only a few sources

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and the reason is a gamma rays are
extremely energetic form applied to

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takes are very

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types of objects to produce gamma
radiation

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now let's take a look what happens when
one of these gamma ray bursts takes

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place

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years the same app years a damn reversed
you can see appear

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who look at this

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okay for a few seconds five or ten
seconds outshines the entire universe

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and gamers

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you can't think about this for a second
this is a single event

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that outshines the in car universe for a
few seconds

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so that's the reason even a primitive
satellite

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as soon as it was launched are could
detect these events

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but it also gives us an idea of what
kind of offense with you

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now another interesting fact is that I
showed you this our little cartoon

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picture at the beginning of a gamma-ray
burst incinerating the earth's

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atmosphere

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I don't hasn't happened yet as you
probably don't know all

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but then reversed actually impact the
earth's atmosphere

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so here's a plot of the art Dept of the
ionosphere

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which is part above the atmosphere you
can see some date tonight I'm variation

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in here is %uh gamma ray bursts that
occurred and as you can see it just push

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the ionosphere down

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okay so this is an event that occurred
some were

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far out in the universe may be in the
outer parts of the solar system maybe

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somewhere else in the Milky Way may be
at the edge of the universe

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but it actually had an impact on the
Earth's atmosphere

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so again to give you a sense of scale
how energetic

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on these events are

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okay so the discovery was announced in
1973 and the first

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two decades after that were fantastic
okay

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on there was very little information and
so

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everybody has a theory about what
cameras on and this is an actual

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compilation

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all the theories or proposed to explain
gamma-ray burst by the early nineteen

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nineties

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135 different theories to explain these
objects and at the time to or less than

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100 m reverse known so

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in in physics or astronomy this is a
fantastic time rate the

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you know you have more than one theory
prefects I'm

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years had a fantastic know a lot of
these theories had some common themes

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and the reason is that the two

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basic facts there were no is that that
these are events with a very short

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duration

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less than a second up to maybe tens of
seconds and produce extreme energies

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they produce gamers

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so the question was what could produce
these these properties

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people came up with a variety of ideas
for example maybe some new type of

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exploding stars something different from
a supernova

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maybe these are giant flares with the
flares on the song

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which are not as large as these but
maybe these were giants layers of other

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stars

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are perhaps they weren't dead
annihilation of matter and anti-matter

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so one theory was

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that obvious they are anti-matter
comments orbiting other stars in the

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galaxy

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i won one of these anti-matter comets
collided into a star made up matter it

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00:13:46,379 --> 00:13:47,475
could produce a gamma reports

241
00:13:48,339 --> 00:13:52,347
or maybe something to do with black
holes on block was a very exotic events

242
00:13:52,419 --> 00:13:53,498
maybe they can produce gamma ray bursts

243
00:13:54,209 --> 00:13:57,237
and there was even a suggestion winter
so warfare after all these satellites

244
00:13:57,489 --> 00:13:58,535
were designed to

245
00:13:58,949 --> 00:14:03,160
detect nuclear explosions so maybe these
were really large nuclear explosions may

246
00:14:03,016 --> 00:14:06,405
be under civilization just blowing up
planets

247
00:14:06,549 --> 00:14:09,583
so so there's quite a lot of our love
interest in this and quite a lot of

248
00:14:09,889 --> 00:14:10,910
ideas

249
00:14:10,091 --> 00:14:14,050
now the reason or so many theories arm
floating around

250
00:14:14,869 --> 00:14:17,938
is that there was one basic problem
which is that there was an uncertainty

251
00:14:18,559 --> 00:14:20,620
in the distance to the gamma-ray burst
there was

252
00:14:21,169 --> 00:14:25,350
about the size of the entire universe
and that means that the energy scale was

253
00:14:25,035 --> 00:14:26,324
also not

254
00:14:26,639 --> 00:14:29,660
so it was just the only thing we knew
was that they were coming from outside

255
00:14:29,066 --> 00:14:30,185
the local party

256
00:14:30,779 --> 00:14:33,841
the solar system of course if these
events were in the other parts of the

257
00:14:34,399 --> 00:14:36,478
solar system versus the edge of the
universe they would require very

258
00:14:37,189 --> 00:14:38,262
different energy scale

259
00:14:38,919 --> 00:14:42,921
and therefore very different mechanism

260
00:14:42,939 --> 00:14:45,947
now why did we have this problem the
reason is that the satellites were

261
00:14:46,739 --> 00:14:49,741
extremely efficient at detecting these
very bright person

262
00:14:49,759 --> 00:14:53,815
gamma rays but they were not efficient
localizing in a precise way

263
00:14:54,319 --> 00:14:57,354
and so when a gamma-ray burst occurred
to satellites would detective and they

264
00:14:57,669 --> 00:14:59,703
could say well it came roughly from
target area

265
00:15:00,009 --> 00:15:03,410
stop okay so you Benny going to take a
picture of

266
00:15:03,041 --> 00:15:07,510
that area on the sky and what you see
something like this

267
00:15:07,879 --> 00:15:10,908
right there are a lot of different
sources so maybe the gamma-ray burst was

268
00:15:11,169 --> 00:15:14,980
associated with that star or that galaxy
or maybe that galaxy

269
00:15:14,098 --> 00:15:17,327
year this collection of stars it is
really unclear

270
00:15:18,209 --> 00:15:21,302
and of course this sum up the stars are
on

271
00:15:22,139 --> 00:15:26,290
I'll are close to Austin some of them
are really far away

272
00:15:26,029 --> 00:15:28,918
some with these galaxies are extremely
distant and so without actually being

273
00:15:29,179 --> 00:15:32,186
able to associate the burst with a
specific

274
00:15:32,249 --> 00:15:35,311
object there was no way of understanding
how much energy

275
00:15:35,869 --> 00:15:39,040
expertise so that was really the

276
00:15:39,004 --> 00:15:41,773
the main challenge now to scale just to
give you know there is the side of the

277
00:15:41,809 --> 00:15:42,828
Moon Scott so

278
00:15:42,999 --> 00:15:47,091
these regions on the sky was very much

279
00:15:47,919 --> 00:15:50,955
now there was one test there was clear

280
00:15:51,279 --> 00:15:54,316
and the question was whether gamma-ray
burst came from the Milky Way galaxy

281
00:15:54,649 --> 00:15:57,661
secretly say what are they came from the
Milky Way outside the Milky Way that

282
00:15:57,769 --> 00:15:58,862
would already give us some indication

283
00:15:59,699 --> 00:16:03,761
about what's happened so here's our our
Milky Way galaxy we are part of the

284
00:16:04,319 --> 00:16:06,320
discover the Milky Way

285
00:16:06,419 --> 00:16:10,467
arm so most of the stars in the objects
in the galaxy are located along this

286
00:16:10,899 --> 00:16:12,946
thin slice of the Scot

287
00:16:13,369 --> 00:16:16,462
following the plane of the Milky Way
galaxy so if gamma-ray burst came from

288
00:16:17,299 --> 00:16:18,376
the Milky Way galaxy as opposed to

289
00:16:19,069 --> 00:16:22,146
outside the Milky Way galaxy we would
expect that they would line up

290
00:16:22,839 --> 00:16:26,290
with the discovery Milky Way galaxy
right if we made a map of the locations

291
00:16:26,029 --> 00:16:27,738
of gamma-ray bursts

292
00:16:27,999 --> 00:16:31,970
it would look something like this: most
of them will be concentrated along

293
00:16:31,097 --> 00:16:34,956
the plane of the Milky Way galaxy in
there would be very few of them

294
00:16:35,829 --> 00:16:39,878
away from the Galaxy okay so here's a
very clear test even though we can't

295
00:16:40,319 --> 00:16:40,400
localize

296
00:16:41,129 --> 00:16:44,228
arm these bursts individually to our
precise position

297
00:16:45,119 --> 00:16:50,600
which at the very least see if they line
up with the discovery

298
00:16:50,006 --> 00:16:55,745
and so in 1993 r-mass a long story 1991
nasa launched the second over its great

299
00:16:56,339 --> 00:16:58,400
observatories the content gamma ray
observatory

300
00:16:58,949 --> 00:17:01,965
are the first one of course was the
Hubble Space Telescope

301
00:17:02,109 --> 00:17:06,110
and one of the main objectives of the
content gamma ray observatory

302
00:17:06,209 --> 00:17:10,214
was to discover a large number gamma ray
bursts a border a thousand are several

303
00:17:10,259 --> 00:17:11,276
thousand

304
00:17:11,429 --> 00:17:14,480
and localized them well enough that we
could see what did they come from the

305
00:17:14,048 --> 00:17:15,050
Milky Way galaxy

306
00:17:15,005 --> 00:17:19,074
or or not ended their instruments

307
00:17:19,569 --> 00:17:22,591
arm there were designed to detect these
bursts are seen here on quarters

308
00:17:22,789 --> 00:17:26,836
so they were pointed at all parts of the
sky finds

309
00:17:27,259 --> 00:17:30,720
years what they found after several
years of observations collecting one

310
00:17:30,072 --> 00:17:32,621
gamma-ray burst after another and
eventually

311
00:17:33,269 --> 00:17:37,460
be released a map of the location gamma
ray bursts after they had about 2700

312
00:17:37,046 --> 00:17:41,110
them

313
00:17:42,001 --> 00:17:48,710
right so how many people think that damn
rivers come from the Milky Way

314
00:17:48,809 --> 00:17:53,811
nobody many people think I members come
from outside the Milky Way

315
00:17:54,009 --> 00:17:58,050
everybody okay good searchers are you
smarter than most astronomers because

316
00:17:58,419 --> 00:18:00,830
when this map was released

317
00:18:00,083 --> 00:18:03,109
nasa decided two hours or the American
Islamic a society decided to have a

318
00:18:04,009 --> 00:18:05,558
great debate

319
00:18:05,639 --> 00:18:10,100
onto actually finally answered a
question for the cameras come from

320
00:18:10,001 --> 00:18:13,029
and I'll show you a second what the
answer was but the occasion

321
00:18:13,038 --> 00:18:17,167
in 1995 was the 75th anniversary of the
great debate on the scale of the

322
00:18:17,509 --> 00:18:19,576
universe that took place in nineteen
twenty

323
00:18:20,179 --> 00:18:23,880
all between our shop we incurred its

324
00:18:23,088 --> 00:18:26,967
and back then the argument was whether
the nephew either were discovered by

325
00:18:27,759 --> 00:18:28,740
Hubble

326
00:18:28,074 --> 00:18:31,973
where part of the Milky Way galaxy and
essentially the Milky Way galaxy was the

327
00:18:32,639 --> 00:18:35,090
entire universe that was the view taken
by

328
00:18:35,009 --> 00:18:39,096
sharply whether these were island
universe is their own galaxies outside

329
00:18:39,096 --> 00:18:41,183
the Milky Way meaning that the universe
was actually much bigger

330
00:18:42,083 --> 00:18:47,147
then why is our thought of it at the
time does the view taken by Chris

331
00:18:48,047 --> 00:18:51,048
now arm Curtis was correct

332
00:18:51,048 --> 00:18:54,144
these gala these island universe is
really were in independent galaxies and

333
00:18:55,044 --> 00:18:56,096
shop was wrong

334
00:18:56,096 --> 00:18:59,395
are and so are Curtis won the debate in
1920

335
00:19:00,259 --> 00:19:03,490
and shop we a year later became the
director of the Harvard College

336
00:19:03,049 --> 00:19:04,054
Observatory

337
00:19:04,099 --> 00:19:07,748
knows his consolation its

338
00:19:08,639 --> 00:19:12,360
okay so in no in 1995 dead debates

339
00:19:12,036 --> 00:19:15,335
our boys on this distance scale to
gamers

340
00:19:15,659 --> 00:19:19,610
game echoing the the question are 1920

341
00:19:19,061 --> 00:19:23,144
and the argument was whether they were
galactic war extra black dick in orgy

342
00:19:24,044 --> 00:19:28,283
cosmological sold on Lamma University
Chicago argue that their eclectic and

343
00:19:28,679 --> 00:19:30,714
but unfortunately for Prince University

344
00:19:31,029 --> 00:19:35,104
argue that they were cosmological now
you just look at that same up another

345
00:19:35,779 --> 00:19:38,080
love you thought they were the lactic so
what was the

346
00:19:38,008 --> 00:19:42,337
crux of the argument are for a galactic
origin

347
00:19:42,409 --> 00:19:45,446
well around the same time people
discovered arm

348
00:19:45,779 --> 00:19:48,852
neutron stars all-stars there were
traveling out of the Milky Way galaxy it

349
00:19:49,509 --> 00:19:52,525
speeds up hundreds of kilometers per
second

350
00:19:52,669 --> 00:19:57,090
okay so these were neutron stars there
were born in supernova explosions

351
00:19:57,009 --> 00:20:00,968
and during this explosion on the start
they somehow received a very large cake

352
00:20:01,049 --> 00:20:05,111
that rejected them outside the Milky Way
at these very large these

353
00:20:05,669 --> 00:20:08,766
creating this sort of the uniform
distribution of neutron stars in the

354
00:20:09,639 --> 00:20:11,830
halo the Milky Way galaxy

355
00:20:11,083 --> 00:20:14,672
and so the argument was that if
gamma-ray burst had something to do with

356
00:20:15,419 --> 00:20:16,493
those neutron stars

357
00:20:17,159 --> 00:20:20,840
then even though they were all related
to the Milky Way galaxy they might

358
00:20:20,084 --> 00:20:25,085
actually give a distributional discarded
looked very much uniform

359
00:20:25,094 --> 00:20:28,149
okay so that was the argument

360
00:20:29,049 --> 00:20:33,122
and arm here's a picture at the end of
the debate here sa perchance key and

361
00:20:34,022 --> 00:20:36,351
lamb and this is %ah sir Mike increases
the

362
00:20:36,549 --> 00:20:40,555
astronomer real are in when the supposed
to advise the Queen

363
00:20:41,149 --> 00:20:45,152
palm comments things like that

364
00:20:45,179 --> 00:20:48,350
that might attend disaster

365
00:20:48,035 --> 00:20:50,064
but you can see that they're all in a
good mood and the reason they're in a

366
00:20:50,379 --> 00:20:52,388
good mood is because there was a vote at
the end of the debate and it came down

367
00:20:53,279 --> 00:20:54,366
fifty 50

368
00:20:55,149 --> 00:20:59,490
okay so people really could not decide
even after having that information

369
00:20:59,049 --> 00:21:02,568
what a gamma-ray burst like a lactic or
extra

370
00:21:03,009 --> 00:21:06,250
now the reason people that were
hesitating is because if gamma-ray burst

371
00:21:06,025 --> 00:21:09,554
for cosmological in orgy became from the
far reaches of the universe

372
00:21:09,779 --> 00:21:12,990
that indicated such large energies

373
00:21:12,099 --> 00:21:14,195
that most people are not comfortable
with that idea but there are mechanisms

374
00:21:15,095 --> 00:21:17,914
in the universe that can produce these
kind of energy

375
00:21:18,769 --> 00:21:22,220
so people much more comfortable with the
idea that they were black taken yet some

376
00:21:22,022 --> 00:21:24,099
of the evidence was pointing

377
00:21:24,099 --> 00:21:28,128
so this was not enough to solve the
mystery

378
00:21:29,019 --> 00:21:32,840
now one thing was recognized by a lot of
thought theoretical Stormers

379
00:21:32,084 --> 00:21:35,089
was that just like when you light a fire
initially have these large flames

380
00:21:36,034 --> 00:21:38,125
they're very bright it's easy to see
them from Fareway

381
00:21:39,025 --> 00:21:42,804
eventually the flames die away and
you're left with this glowing embers

382
00:21:43,029 --> 00:21:45,030
that last much longer

383
00:21:45,129 --> 00:21:49,340
their favorite are harder to see but
they'll ask for a lot longer

384
00:21:49,034 --> 00:21:52,082
so there was an analogy that was made it
is the gamma-ray burst to be like that

385
00:21:52,082 --> 00:21:52,171
initial fire

386
00:21:53,071 --> 00:21:56,420
a lot of energy getting released in a
very short period of time

387
00:21:57,059 --> 00:22:01,094
second ten seconds 100 seconds but maybe
there was a hope that this would be

388
00:22:01,409 --> 00:22:03,610
followed up by these glowing embers by

389
00:22:03,061 --> 00:22:07,123
afterglow that would last for maybe a
few hours or a few days

390
00:22:08,023 --> 00:22:11,722
and if we could capture days after glow
we have longer time to actually go and

391
00:22:11,929 --> 00:22:12,953
find it

392
00:22:13,169 --> 00:22:16,460
and because it arm produce most of its
radiation at

393
00:22:16,046 --> 00:22:19,375
energies that we know how to work with
not gamma rays but

394
00:22:19,789 --> 00:22:24,070
ultraviolet and visible light on radio
waves we might be able to pinpoint the

395
00:22:24,007 --> 00:22:26,716
positions of the gamma ray bursts much
more accurately

396
00:22:26,779 --> 00:22:29,970
banned from the gamma rays a lot and so
we can use the

397
00:22:29,097 --> 00:22:32,182
afterglow to tell us where the damn
reverse came from

398
00:22:33,082 --> 00:22:36,174
and therefore deciphered the origin
experts

399
00:22:37,074 --> 00:22:40,075
now this requires are a very different
approach

400
00:22:40,084 --> 00:22:43,643
so this is actually the approach that we
take and have been taking for several

401
00:22:44,399 --> 00:22:46,438
years now to study gamma reber's

402
00:22:46,789 --> 00:22:50,600
we just show you what we do are when one
of these things occurs

403
00:22:50,006 --> 00:22:54,065
so we have satellites in space that are
gamma ray satellites designed to fines

404
00:22:54,659 --> 00:22:55,980
cameras

405
00:22:55,098 --> 00:22:59,149
in these modern satellites are fantastic
soon as a gamma-ray burst happens

406
00:23:00,049 --> 00:23:05,068
all I get an alert on my cell phone
within about 30 seconds on the Berserker

407
00:23:05,509 --> 00:23:08,587
I get an alert on my iPhone the tells me
where in the sky is

408
00:23:09,289 --> 00:23:13,351
and then op my research group group

409
00:23:13,909 --> 00:23:19,480
arm calls up all these observatories
around the world

410
00:23:19,048 --> 00:23:23,627
we told them please stop what you're
doing entry point a telescope to that

411
00:23:24,059 --> 00:23:25,330
position where the camera birds

412
00:23:25,033 --> 00:23:29,046
just occur and we have to do it with it
in its otherwise this after glow will

413
00:23:29,046 --> 00:23:31,625
fade away and disappear

414
00:23:32,039 --> 00:23:35,570
so these are not just nice gratuitous
picture is a

415
00:23:35,057 --> 00:23:39,146
telescopes on what he's a really the
facilities that we use only some of them

416
00:23:39,659 --> 00:23:42,710
on them a John telescopes in Chile the

417
00:23:42,071 --> 00:23:47,010
M&T telescope in Arizona the Gemini
telescopes which are located in Hawaii

418
00:23:47,649 --> 00:23:50,738
the Very Large Array in Mexico and then
some telescopes in space of course we

419
00:23:51,539 --> 00:23:52,624
don't get to talk about

420
00:23:53,389 --> 00:23:57,440
arm but we really just phone up the
observatory's and whoever is using it

421
00:23:57,044 --> 00:23:59,123
also be asked to stop what they're doing

422
00:23:59,519 --> 00:24:02,605
and look at the gamers and as you can
imagine as a result I we have a lot of

423
00:24:03,379 --> 00:24:04,405
friends

424
00:24:04,639 --> 00:24:08,640
I'm but you know people like people like
being part of this song

425
00:24:08,649 --> 00:24:11,737
understand everything I miss that items

426
00:24:12,529 --> 00:24:17,350
so so here is um covered the movie that
shows how the sequence of events occurs

427
00:24:17,035 --> 00:24:20,058
so somewhere in the universe to gamma
ray burst occurs

428
00:24:20,058 --> 00:24:25,777
and it's detected by satellite and
information is sent down to the ground

429
00:24:26,299 --> 00:24:30,387
and you can see that also is already
moving they responded very quickly

430
00:24:31,179 --> 00:24:36,710
and we take images of this car I and we
look for an object that fades away

431
00:24:36,071 --> 00:24:40,110
that will be the afterglow now for some
real life it doesn't come with a circle

432
00:24:40,749 --> 00:24:41,788
around

433
00:24:42,139 --> 00:24:45,166
it so we have to actually do a lot of
hard work to find what the soft glow

434
00:24:45,409 --> 00:24:46,472
isn't where it is

435
00:24:47,039 --> 00:24:50,100
but this is in a nutshell what we do to
capture these gamers and again we have

436
00:24:50,649 --> 00:24:51,690
to do to save minutes

437
00:24:51,069 --> 00:24:56,428
for hours otherwise we lose that person
we have to wait for the next one

438
00:24:57,049 --> 00:25:01,700
now with the current satellites are we
find about two gamma ray bursts per week

439
00:25:01,007 --> 00:25:05,031
that some so we run around out twice a
week to to do this and we've been doing

440
00:25:05,094 --> 00:25:06,413
this for several years

441
00:25:07,259 --> 00:25:10,620
for some reason it always seems like
they happened the week those two people

442
00:25:10,062 --> 00:25:13,741
by so it's a lot of fun

443
00:25:14,299 --> 00:25:18,344
okay so arm so this idea of capturing
the afterglow

444
00:25:18,749 --> 00:25:21,827
are came to fruition in 1996

445
00:25:22,529 --> 00:25:25,564
when the Dutch italians decided to
launch a satellite

446
00:25:25,879 --> 00:25:29,620
on that could provide positions for the
gamma rays are the gamma-ray burst there

447
00:25:29,062 --> 00:25:32,121
were 100 times more accurate than the
Compton gamma ray observatory

448
00:25:33,021 --> 00:25:36,080
and the realization was it's not enough
to just tell what did it come from

449
00:25:36,269 --> 00:25:39,280
look you're not there wasn't a good
enough that's we need a hundred times

450
00:25:39,379 --> 00:25:40,840
more active positions

451
00:25:40,084 --> 00:25:42,158
and more importantly those positions
have to be sent to the ground within a

452
00:25:43,058 --> 00:25:45,787
few hours otherwise the article fade
away

453
00:25:46,309 --> 00:25:49,366
now these days it takes 30 seconds with
its first satellite was about

454
00:25:49,879 --> 00:25:53,967
a townhouse can so the satellite was
launched in 1996

455
00:25:54,759 --> 00:25:57,764
and they had her for success in February
March 1997

456
00:25:58,259 --> 00:26:01,262
they discovered a gamma-ray burst on the
satellite

457
00:26:01,559 --> 00:26:05,220
in a satellite had x-ray telescope to
look for the afterglow

458
00:26:05,022 --> 00:26:09,095
and here's an image from X ray camera
taken on February 28th

459
00:26:09,095 --> 00:26:12,124
use an image of the same part of this
car in three days later

460
00:26:13,024 --> 00:26:17,173
you can see a bright source in x-rays
over here don't fade away

461
00:26:17,389 --> 00:26:20,466
so this was the first afterglow ever
seen from a gamers

462
00:26:21,159 --> 00:26:25,160
it really vindicated this whole idea
that by studying the after close

463
00:26:25,169 --> 00:26:29,220
we can determine the origin of dem us

464
00:26:29,679 --> 00:26:33,200
now we are interested in particular in
after closing visible light not

465
00:26:33,002 --> 00:26:36,431
X-rays and the reason is to fall we can

466
00:26:36,629 --> 00:26:40,631
pinpoint sources in visible light much
more accurately than x-rays

467
00:26:40,649 --> 00:26:43,950
and the other reason is we can use
divisible I to actually

468
00:26:43,095 --> 00:26:46,454
allow us to measure the distance again
books so here's what

469
00:26:47,309 --> 00:26:50,850
after close look like invisible light so
here is again an image

470
00:26:50,085 --> 00:26:53,774
making a few hours after a gamma-ray
burst explosion

471
00:26:54,539 --> 00:26:58,210
an image of the same part of the sky
taken a few hours later

472
00:26:58,021 --> 00:27:02,200
here again shown by arrow is object was
bright over here

473
00:27:02,389 --> 00:27:06,413
and faded away here this is the africa

474
00:27:06,629 --> 00:27:10,090
here's a nice little movie showing
another of the glow this one

475
00:27:10,009 --> 00:27:14,188
you can see occurred over here and then
just dams away

476
00:27:14,269 --> 00:27:18,293
over the course of several dates now
what's fascinating about this little

477
00:27:18,509 --> 00:27:19,120
movie

478
00:27:19,012 --> 00:27:22,391
as you can see these objects over here
this long this one is on those are

479
00:27:22,499 --> 00:27:23,940
galaxies

480
00:27:23,094 --> 00:27:27,543
was I don't like the Milky Way k
hundreds of billions of stars

481
00:27:28,389 --> 00:27:31,464
here is the visible light from this
afterglow

482
00:27:32,139 --> 00:27:35,212
and it is about a million times brighter
than an entire galaxy

483
00:27:35,869 --> 00:27:38,990
I think so even though the afterglow
Spain third in the gamma-ray burst

484
00:27:38,099 --> 00:27:39,101
itself

485
00:27:40,019 --> 00:27:43,035
it still amazingly bright

486
00:27:43,035 --> 00:27:46,614
and that allows us to actually capture
these Africans and study them in great

487
00:27:46,929 --> 00:27:47,973
detail

488
00:27:48,369 --> 00:27:51,590
now why do we care about the visible
light in particular

489
00:27:51,059 --> 00:27:55,086
well the reason is that we can use the
visible light to measure reg

490
00:27:55,086 --> 00:27:58,975
so the concert over redshift is
relatively straightforward we're all

491
00:27:59,749 --> 00:28:01,090
used to this from

492
00:28:01,009 --> 00:28:04,578
are soundly for train approaches also
moves away from us

493
00:28:04,659 --> 00:28:07,732
we hear a different pitch the same thing
happens with light if the source moves

494
00:28:08,389 --> 00:28:10,454
away from us the light is registered

495
00:28:11,039 --> 00:28:14,730
if the source is approaching us the
light is blue shifted

496
00:28:14,073 --> 00:28:17,142
and since the universe is expanding

497
00:28:17,799 --> 00:28:21,690
there is a direct correlation between
the amount of redshift

498
00:28:21,069 --> 00:28:24,133
and the distance sources that are
further away from us

499
00:28:25,033 --> 00:28:28,602
are moving away from us to the larger
velocity larger speed

500
00:28:28,899 --> 00:28:33,110
then sources that are nearby so by
measuring the redshift one object

501
00:28:33,011 --> 00:28:36,074
weekend directly relate that to the
distance of the object

502
00:28:36,074 --> 00:28:40,075
so if an object is for gamma reverses
inside-the-beltway Galaxy

503
00:28:40,084 --> 00:28:43,171
force the Milky Way galaxy is not
expending stays the same size so there

504
00:28:44,071 --> 00:28:46,074
will be no richer

505
00:28:46,074 --> 00:28:49,483
if demory burst or in the relatively
nearby part of the universe though are

506
00:28:50,149 --> 00:28:51,200
very small right shift

507
00:28:51,659 --> 00:28:54,730
and a small distance and if they're very
far away they will have an enormous red

508
00:28:55,369 --> 00:28:57,400
shift in a very large distance

509
00:28:57,679 --> 00:29:01,773
it so we can measure this from the
visible-light of in a direct way

510
00:29:02,619 --> 00:29:06,830
so here's an example I love how we do
this what we do is we find afterglow

511
00:29:06,083 --> 00:29:07,012
invisible life

512
00:29:07,759 --> 00:29:11,240
and then we take a specter of the
African we passed out light through a

513
00:29:11,024 --> 00:29:13,913
prism we break the light up into its
components

514
00:29:14,129 --> 00:29:18,970
and we look for the red shift in the way
we do it is by identifying

515
00:29:18,097 --> 00:29:21,183
these lines that are due to various
types of elements

516
00:29:22,083 --> 00:29:25,172
so all these lies that you see here are
due to elements like carbon and silicon

517
00:29:26,072 --> 00:29:30,151
magnesium and iron and aluminum and we
know the lines

518
00:29:30,799 --> 00:29:34,810
we know what the rest wavelength of the
lines are is and therefore we can

519
00:29:34,909 --> 00:29:37,360
measure it by how much their wretched

520
00:29:37,036 --> 00:29:41,083
is the richest 20 them demory bursary
multi-way if the Reg it is very large

521
00:29:41,083 --> 00:29:45,012
there in the far reaches of the universe
so from this spectrum for example the

522
00:29:45,759 --> 00:29:49,360
gamma-ray burst by identifying all these
lines we can measure to reject

523
00:29:49,036 --> 00:29:52,042
we can measure the distance in here and
what its

524
00:29:52,096 --> 00:29:55,425
twelve-point one billion light years

525
00:29:56,289 --> 00:29:59,590
so that means that the light from this
burst has been traveling to us for

526
00:29:59,059 --> 00:29:59,498
twelve

527
00:30:00,029 --> 00:30:05,190
$1.1 billion years that's over ninety
percent of the history of the universe

528
00:30:05,019 --> 00:30:08,023
that means that this burst this camera
burst occurred

529
00:30:08,023 --> 00:30:11,192
when the universe was only ten percent
of its current age

530
00:30:11,399 --> 00:30:14,436
it is extremely distant not only is it
not in the Milky Way

531
00:30:14,769 --> 00:30:18,490
it's no more in our vicinity you this is
an ancient

532
00:30:18,049 --> 00:30:22,086
engine object and so that means that
with these kind of

533
00:30:22,086 --> 00:30:26,355
enormous distances jam reber's really
are

534
00:30:27,129 --> 00:30:30,203
so energetic that they are the biggest
explosion since the Big Bang

535
00:30:30,869 --> 00:30:34,840
back to give you a sense of scale how
much energy is required

536
00:30:34,084 --> 00:30:37,148
to produce a gamma-ray burst everybody
knows Einstein's famous equation

537
00:30:38,048 --> 00:30:41,111
equals MC squared right okay so if we
take

538
00:30:42,011 --> 00:30:47,070
the song and convert all that master
energy

539
00:30:47,169 --> 00:30:50,258
pure energy using equals MC squared that
so much energy gamma

540
00:30:51,059 --> 00:30:55,065
expertise okay so think about that for a
second

541
00:30:55,119 --> 00:30:59,210
take an entire star and convert it
completely into energy

542
00:30:59,021 --> 00:31:04,440
and that's the scale talk he said he's a
really enormous explosions

543
00:31:04,629 --> 00:31:08,450
in really the only way we know we nature
are to do this

544
00:31:08,045 --> 00:31:12,024
is through the formation all a black
hole

545
00:31:12,429 --> 00:31:15,492
so by forming a block wall and into
creating the material into the black

546
00:31:16,059 --> 00:31:17,083
hole

547
00:31:17,299 --> 00:31:22,970
region release these kind of Energy's so
from 135 theories that were proposed in

548
00:31:22,097 --> 00:31:23,746
the early nineteen nineties

549
00:31:24,619 --> 00:31:27,648
by measuring the distances to gamma ray
bursts we've essentially narrowed things

550
00:31:27,909 --> 00:31:29,948
down to one theory which is

551
00:31:30,299 --> 00:31:33,850
the gamma-ray bursts essentially marked
the birth of a black hole

552
00:31:33,085 --> 00:31:39,784
that's what they are and in their
simplest

553
00:31:40,549 --> 00:31:42,940
now there's a little bit more to the
story so far I've told you that they are

554
00:31:42,094 --> 00:31:44,573
gamma ray bursts and I pretended as if
they're all

555
00:31:45,419 --> 00:31:48,480
one group of objects

556
00:31:48,048 --> 00:31:52,817
are it turns out that actually to
different categories of gamers

557
00:31:53,249 --> 00:31:57,850
arm so if we've look at the duration
that this traditional duration of gamers

558
00:31:57,085 --> 00:32:01,254
all the way from 10 milliseconds down
here to about a thousand seconds here

559
00:32:02,019 --> 00:32:05,056
you can see that they're actually two
groupings of gamma-ray bursts their ones

560
00:32:05,389 --> 00:32:08,700
that are about shorter than a second and
a lot or a large group that are longer

561
00:32:08,007 --> 00:32:12,676
about a sec it's all stars are very
inventive with names so we call these

562
00:32:13,369 --> 00:32:15,412
the short ones and call these the
Longhorns

563
00:32:15,799 --> 00:32:19,832
and you can see I'm two examples over
here on the essentially look the same

564
00:32:20,129 --> 00:32:23,172
just some of them are shorter and sold
them or longer

565
00:32:23,559 --> 00:32:26,850
now the fact that there are two group
two types of gamma-ray bursts adjusted

566
00:32:26,085 --> 00:32:27,764
maybe there are actually two ways

567
00:32:28,529 --> 00:32:32,540
of producing gamers we know that we need
to do it through the birth of a black

568
00:32:32,639 --> 00:32:34,080
hole

569
00:32:34,008 --> 00:32:36,107
you may be nature's found the way of
doing this in two different ways which

570
00:32:37,007 --> 00:32:38,034
would be quite astounding

571
00:32:38,034 --> 00:32:42,034
we can form black holes into completely
its

572
00:32:42,034 --> 00:32:45,119
what's think about so one way of forming
a black hole

573
00:32:46,019 --> 00:32:49,598
is to take an extremely massive star
something like a hundred times the mass

574
00:32:49,769 --> 00:32:50,834
of the Sun

575
00:32:51,419 --> 00:32:55,100
these massive stars have a very
different life from the Sun the Sun will

576
00:32:55,001 --> 00:32:59,310
live happily arm for about $10 billion
years

577
00:32:59,409 --> 00:33:02,472
is very massive stars are they're born
in they die within about 10 million

578
00:33:03,039 --> 00:33:04,470
years

579
00:33:04,047 --> 00:33:07,846
okay so they're kinda what the rock
stars at the of the universe

580
00:33:08,269 --> 00:33:11,710
I they can deliver faster than the flame
out

581
00:33:11,071 --> 00:33:16,120
well and explore so if we take one of
these very massive stars at the end of

582
00:33:16,759 --> 00:33:21,450
its life it collapses under its own
weight and it can produce a black hole

583
00:33:21,045 --> 00:33:24,049
and then that can give rise to the first
gamers

584
00:33:24,085 --> 00:33:27,644
so here is our a little simulation
showing the process you can see the star

585
00:33:28,409 --> 00:33:29,970
collapsing down

586
00:33:29,097 --> 00:33:32,506
to feed a black hole and then the gamma
rays emerging out

587
00:33:33,379 --> 00:33:37,388
and here's an actual computer simulation
that shows how this process occurs

588
00:33:38,279 --> 00:33:42,316
here's the black hole in the center here
is there just serve radiation emerging

589
00:33:42,649 --> 00:33:44,650
out

590
00:33:44,749 --> 00:33:48,830
and you can see that the borough their
way out of the star

591
00:33:48,083 --> 00:33:51,152
and once they get out on the starter
will produce a damn its

592
00:33:51,899 --> 00:33:54,977
because your clock running up here so
this is five seconds

593
00:33:55,679 --> 00:33:59,727
six seconds takes about 10 seconds

594
00:34:00,159 --> 00:34:03,186
artistic want to start so maybe these

595
00:34:03,429 --> 00:34:07,442
take about 10 seconds to occur are these
long gamers

596
00:34:07,559 --> 00:34:12,800
so that's one way there's another way to
make black holes

597
00:34:12,008 --> 00:34:17,307
which is are through the merger or the
collision of two neutron stars

598
00:34:18,099 --> 00:34:22,107
neutron stars are fascinating objects in
their own what neutron stars way about

599
00:34:22,179 --> 00:34:24,198
one-and-a-half times the mass of the Sun

600
00:34:24,369 --> 00:34:27,397
but there are about the size and the
City of Boston

601
00:34:27,649 --> 00:34:31,950
okay so these are extremely dense
objects still not as dense as a black

602
00:34:31,095 --> 00:34:32,194
hole which is of course

603
00:34:33,049 --> 00:34:37,040
infinitely thats are but that's not too
bad right

604
00:34:37,004 --> 00:34:41,004
1/2 times the mass of the Sun packed
into a few kilometers insights

605
00:34:41,004 --> 00:34:44,045
now sometimes these neutron stars are
born in a binary system there are two of

606
00:34:44,045 --> 00:34:45,073
them

607
00:34:45,073 --> 00:34:48,099
and as they emerge as they come closer
to each other

608
00:34:48,099 --> 00:34:53,468
they can eventually collide and merge to
form a block wall

609
00:34:54,359 --> 00:34:58,000
and I have to again lead to the
formation over gamers

610
00:34:58,000 --> 00:35:01,067
this is a very different mechanism now
you can see again a little movie over

611
00:35:01,067 --> 00:35:03,096
here to chose you how these two neutron
stars

612
00:35:03,096 --> 00:35:06,121
approach each other in orbit eventually

613
00:35:07,021 --> 00:35:11,068
r merge collided and annihilate to form
a black hole

614
00:35:11,068 --> 00:35:13,142
and that gives rise to a Jetta gamma
rays and yours again a computer

615
00:35:14,042 --> 00:35:15,090
simulation showing that

616
00:35:15,009 --> 00:35:19,048
at least on a computer this works
insecurity neutron star as they come

617
00:35:20,029 --> 00:35:21,113
into contact

618
00:35:22,013 --> 00:35:26,942
I V for a black hole in the center here
for some reason here that black was blue

619
00:35:27,059 --> 00:35:30,540
you can use our imagination and then
there's a discover material to will

620
00:35:30,054 --> 00:35:34,054
drain into the black hole and willpower
to gamers

621
00:35:34,054 --> 00:35:37,119
so those are two very different ways of
producing a gamma-ray burst from very

622
00:35:38,019 --> 00:35:42,025
different types of objects here you can
see another counter chose one

623
00:35:42,025 --> 00:35:44,100
milliseconds 20 seconds three months

624
00:35:45,000 --> 00:35:48,099
5 seconds so this is a very short time
scale compared to the

625
00:35:48,099 --> 00:35:52,114
other types so maybe these are the
object that produced a short gap

626
00:35:53,014 --> 00:35:57,443
us so we can test this and this is
something we've been doing for the past

627
00:35:57,569 --> 00:35:59,390
several years

628
00:35:59,039 --> 00:36:02,095
we got us a question if John rivers are
produced

629
00:36:02,095 --> 00:36:04,192
by the most massive stars in the
universe where would we expect to find

630
00:36:05,092 --> 00:36:06,281
them

631
00:36:07,109 --> 00:36:11,530
well remember I told it is very massive
stars have a very short lifespan

632
00:36:11,053 --> 00:36:14,079
day then they die within a few million
years ago when they were born

633
00:36:14,079 --> 00:36:16,172
that means that we're gonna find those
gamma ray bursts if these are the

634
00:36:17,072 --> 00:36:18,120
obvious that produced them

635
00:36:19,002 --> 00:36:22,023
at the same place where stars are born
right they're born in they die so

636
00:36:22,041 --> 00:36:23,054
quickly that

637
00:36:23,054 --> 00:36:26,373
they're still in the same in bar that
means that we're gonna find them in

638
00:36:26,859 --> 00:36:27,890
stellar nurseries

639
00:36:27,089 --> 00:36:30,178
in environments like these were young
massive stars are born

640
00:36:31,078 --> 00:36:34,166
that's also where they talk now where do
these

641
00:36:35,066 --> 00:36:39,097
OnStar nurseries occur so here's a view
of other whirlpool galaxy

642
00:36:39,097 --> 00:36:42,152
this is what the Milky Way would look
like if we could look at it from the top

643
00:36:43,052 --> 00:36:47,138
and you can see the spiral arms are
dotted with very bright regions

644
00:36:48,038 --> 00:36:51,053
in these are regions where star
formation occurs so in the spiral

645
00:36:51,053 --> 00:36:54,147
galaxies most the stars are born along
the arms

646
00:36:55,047 --> 00:36:58,050
whereas most of the all-stars are here
center

647
00:36:58,077 --> 00:37:02,077
so if gamma-ray burst came from is very
massive stars we expect to find a

648
00:37:02,077 --> 00:37:03,100
mocking the spiral arms

649
00:37:04,000 --> 00:37:08,079
of the galaxies in which they occur and
here's a nice example

650
00:37:08,079 --> 00:37:11,510
here's a galaxy that produced a
gamma-ray burst and then was image with

651
00:37:11,051 --> 00:37:12,146
the Hubble Space Telescope

652
00:37:13,046 --> 00:37:15,100
and so you can see the center of the
galaxy over here and you can see the

653
00:37:16,000 --> 00:37:17,839
spiral arms

654
00:37:17,839 --> 00:37:20,970
over here and this is the location of
the gamma-ray burst

655
00:37:20,097 --> 00:37:23,175
right along one of the spiral arms
exactly where we expect to find

656
00:37:24,075 --> 00:37:24,694
experience

657
00:37:25,369 --> 00:37:31,400
starts it is another place were a lot of
Matt young massive stars are born

658
00:37:31,004 --> 00:37:35,703
arm better location is when two galaxies
merge together

659
00:37:36,099 --> 00:37:39,430
and so here is actually a beautiful
example the antennae galaxies

660
00:37:39,043 --> 00:37:42,067
your two daughters they came in together
and are in the process of merging into a

661
00:37:42,067 --> 00:37:44,075
single doubt

662
00:37:44,075 --> 00:37:47,091
resume in on this region over here with
the Hubble Space Telescope you see

663
00:37:47,091 --> 00:37:52,095
all these boo not save very bright
objects these are all environments where

664
00:37:52,095 --> 00:37:54,103
young stars are formed due to the
collision

665
00:37:55,003 --> 00:37:59,016
these new these to yeltsin's so once
again if gamma-ray burst come from these

666
00:37:59,016 --> 00:38:01,098
very massive stars would expect to find
them in galaxies in

667
00:38:01,098 --> 00:38:05,169
in the process of merging again here
Hubble Space Telescope

668
00:38:06,069 --> 00:38:09,116
observations of galaxies to produce
gamma reverse

669
00:38:10,016 --> 00:38:13,425
you can see this galaxy is in the
process of merging together two galaxies

670
00:38:13,569 --> 00:38:16,624
are coming together almost looks like
these antennae galaxies

671
00:38:17,119 --> 00:38:20,430
here's another example of several
galaxies in the process of merging on

672
00:38:20,043 --> 00:38:22,102
the gamma-ray burst occurred

673
00:38:23,002 --> 00:38:26,051
so it looks like the long duration gamma
ray bursts are really occurring

674
00:38:26,051 --> 00:38:28,150
and the same environment we expect to
find the most massive stars in the

675
00:38:29,005 --> 00:38:30,009
universe

676
00:38:30,054 --> 00:38:33,077
so that gives us a very nice clue that
this this is really what

677
00:38:33,077 --> 00:38:37,886
produces these long-duration

678
00:38:38,579 --> 00:38:41,950
now what about these mergers have
neutron stars

679
00:38:41,095 --> 00:38:44,154
well it's a very different store so in
order for the

680
00:38:45,054 --> 00:38:48,873
neutron stars to merge they need you
start from a large separation

681
00:38:49,359 --> 00:38:53,384
and slowly spiraling until they come
into contact

682
00:38:53,609 --> 00:38:58,010
and that usually takes billions years
not ten million years with billions

683
00:38:58,001 --> 00:39:01,029
years so that means that by the time
those systems

684
00:39:01,029 --> 00:39:03,115
come together to merge all the other
stars the massive stars in the galaxy

685
00:39:04,015 --> 00:39:05,924
have all died away

686
00:39:06,059 --> 00:39:09,750
right they've what they've been long
gone and the only stars are left beyond

687
00:39:09,075 --> 00:39:10,152
our All Stars

688
00:39:11,052 --> 00:39:14,059
like our Sun so we would expect to find
the system's

689
00:39:15,022 --> 00:39:19,381
in these are elliptical galaxies is dead
elliptical galaxies there are no longer

690
00:39:19,579 --> 00:39:20,677
forming a young stars

691
00:39:21,559 --> 00:39:25,460
they look very boring right they all
look as pretty as the spiral galaxies

692
00:39:25,046 --> 00:39:28,144
but that's where these short are these
are gamers to come from

693
00:39:29,044 --> 00:39:32,052
mergers a neutron stars would occur

694
00:39:32,052 --> 00:39:35,121
Sophie going to take images of the
galaxies the produce short

695
00:39:36,021 --> 00:39:40,024
gamma ray bursts here's what we find is
boring

696
00:39:40,024 --> 00:39:45,024
Browns looking things elliptical
galaxies

697
00:39:45,024 --> 00:39:49,047
so here again we have direct evidence
that the short duration gamma-ray burst

698
00:39:49,047 --> 00:39:52,070
or current exactly in the environment we
expect to find only these

699
00:39:52,007 --> 00:39:55,025
old systems these Bergen you don't stop

700
00:39:55,088 --> 00:39:58,297
and so it turns out that from the sky
knows lines of evidence and there are

701
00:39:59,089 --> 00:40:00,135
other ones

702
00:40:00,549 --> 00:40:03,550
that long duration gamma ray bursts
really come from these extremely massive

703
00:40:03,559 --> 00:40:04,900
stars

704
00:40:04,009 --> 00:40:07,042
wears the short duration gamers are
produced by the collisions 0

705
00:40:08,023 --> 00:40:12,028
are to neutron stars and it's amazing
that nature found two very different

706
00:40:12,073 --> 00:40:13,139
channels to produce objects a look

707
00:40:14,039 --> 00:40:19,138
almost identical in every respect except
for their direction

708
00:40:20,038 --> 00:40:23,042
okay so this is good where we stand now
of course there are a lot of details

709
00:40:23,078 --> 00:40:26,100
that we try to understand but we've gone
a long way from not even knowing what

710
00:40:27,000 --> 00:40:30,051
are these objects were coming from there
other parts of the solar system

711
00:40:30,051 --> 00:40:34,160
you with the far reaches of the universe
with actually learned an enormous amount

712
00:40:34,619 --> 00:40:40,400
you can say okay that's all great but
what I've damage was done to me recently

713
00:40:40,004 --> 00:40:44,653
let me tell you a little bit about where
we're going next the gap

714
00:40:45,049 --> 00:40:47,770
so what are the big questions and
cosmology in the formation of the

715
00:40:47,077 --> 00:40:48,396
universe

716
00:40:49,089 --> 00:40:54,210
is when the first stars and galaxies in
the universe actually for

717
00:40:54,021 --> 00:40:57,113
so we know that there was the cosmic
microwave background

718
00:40:58,013 --> 00:41:02,018
that was formed about three hundred
thousand years after the Big Bang

719
00:41:02,018 --> 00:41:06,407
and we know the universe around us today
of all the way back to about a billion

720
00:41:06,569 --> 00:41:08,270
years after the Big Bang

721
00:41:08,027 --> 00:41:11,376
we know that there are a lot of stars
and galaxies and we have some basic

722
00:41:11,619 --> 00:41:11,666
ideas

723
00:41:12,089 --> 00:41:16,490
out the form and grow over time but this
period of time between three hundred

724
00:41:16,049 --> 00:41:17,091
thousand years after the Big Bang

725
00:41:17,091 --> 00:41:21,119
about a billion years after the Big apps
quite a big chunk

726
00:41:22,019 --> 00:41:25,102
is currently called the dark ages we
know that the first stars and galaxies

727
00:41:26,002 --> 00:41:29,081
must perform sometime

728
00:41:29,099 --> 00:41:33,470
during that period but we don't know
when and we don't know how

729
00:41:33,047 --> 00:41:37,616
those are two very big questions and
cosmology

730
00:41:38,039 --> 00:41:42,420
now we can simulate all this on the
computer okay so we can take our

731
00:41:42,042 --> 00:41:46,701
model university computer and we can run
it for them time from the Big Bang and

732
00:41:47,079 --> 00:41:49,530
we can watch how galaxies form

733
00:41:49,053 --> 00:41:53,090
arm but yet maybe that's right maybe
it's not without direct evidence we

734
00:41:53,009 --> 00:41:53,978
really don't know

735
00:41:54,869 --> 00:41:57,240
right we don't want to just rely on a
computer program to tell us how the

736
00:41:57,024 --> 00:41:57,095
universe

737
00:41:57,095 --> 00:42:02,254
for so what does this have to do with
gamers

738
00:42:03,109 --> 00:42:07,030
well as I hopefully convince your damn
rivers are extremely bright

739
00:42:07,003 --> 00:42:10,045
a outshine entire galaxies by factor
million

740
00:42:10,045 --> 00:42:13,944
in john burris they're brighter than the
entire universe for a few seconds

741
00:42:14,349 --> 00:42:16,425
so that means that if gamma-ray burst
occurred in this early phase of the

742
00:42:17,109 --> 00:42:18,440
universe in particular

743
00:42:18,044 --> 00:42:21,122
some of the first massive stars in the
universe exploded as gamma ray bursts

744
00:42:22,022 --> 00:42:27,048
we could actually see them more easily
than we could see entire yeltsin's

745
00:42:27,048 --> 00:42:31,647
so what would be great if you could find
a gamma-ray burst over here

746
00:42:32,079 --> 00:42:35,460
and winter telescope of course measured
redshift

747
00:42:35,046 --> 00:42:38,195
and get a view of what the universe look
like as a slight

748
00:42:38,609 --> 00:42:42,260
reverses all the way from the first 100
million years twice

749
00:42:42,026 --> 00:42:44,835
we can look at how the composition of
the universe changes over time we can

750
00:42:45,069 --> 00:42:46,143
learn an enormous amount

751
00:42:46,809 --> 00:42:49,817
about when the first stars and galaxies
occur using these beacons of light the

752
00:42:50,609 --> 00:42:54,611
only sign for a few hours

753
00:42:54,809 --> 00:42:58,440
now until about two or three years ago
the most distant gamma-ray burst that we

754
00:42:58,044 --> 00:42:59,069
knew about

755
00:42:59,069 --> 00:43:02,076
I'm occurred about a billion years after
the Big Bang

756
00:43:02,076 --> 00:43:06,117
so brought on the urge the dark ages

757
00:43:07,017 --> 00:43:09,916
which which is great but of course we
already know quite a lot about the

758
00:43:10,069 --> 00:43:10,123
universe

759
00:43:10,609 --> 00:43:13,760
up so what are the goals 0

760
00:43:13,076 --> 00:43:17,117
my research when I came here to harvard
was to actually

761
00:43:18,017 --> 00:43:21,456
find em reversing the dark ages actually
penetrate this veil

762
00:43:21,609 --> 00:43:24,707
are NC if we can study the early part
serbs

763
00:43:25,589 --> 00:43:29,200
the first part of that was to actually
going fine gamma ray bursts the dark

764
00:43:29,002 --> 00:43:31,049
ages and yours

765
00:43:31,067 --> 00:43:34,073
so we set out to do that and we've
actually succeeded

766
00:43:34,073 --> 00:43:37,382
also here showing images I love to gamma
reports

767
00:43:38,039 --> 00:43:41,090
one occurred only 630 million years
after the Big Bang

768
00:43:41,549 --> 00:43:45,030
the other one only 525 million years
after the Big Bang

769
00:43:45,003 --> 00:43:48,090
so this is a time when the universe was
about 4 percent of its current age

770
00:43:48,009 --> 00:43:51,015
really looking at our baby picture is a
of the universe

771
00:43:52,005 --> 00:43:56,022
and you can see these are images of the
camera person then it disappears

772
00:43:56,067 --> 00:43:59,072
in the reason is it disappears in in
these images and it's visible here is

773
00:44:00,017 --> 00:44:02,078
that the red shift is so large

774
00:44:02,078 --> 00:44:05,587
that in fact we don't see any visible
light from these purse all the light has

775
00:44:06,289 --> 00:44:08,150
been shifted into the infrared

776
00:44:08,015 --> 00:44:11,021
party this fact because the register
solar

777
00:44:11,075 --> 00:44:14,079
and that's how we measure distances

778
00:44:15,015 --> 00:44:17,714
in fact about six months ago we found
another one it's about seven hundred

779
00:44:17,849 --> 00:44:19,200
million years after the Big Bang

780
00:44:19,002 --> 00:44:22,361
and so now we have at least three of
these gamma ray bursts sitting

781
00:44:22,559 --> 00:44:25,780
right smack in the middle of the dark
ages think

782
00:44:25,078 --> 00:44:28,897
so we've achieved our first goal which
is to demonstrate that damn reverse

783
00:44:29,599 --> 00:44:32,020
actually exist in the dark ages

784
00:44:32,002 --> 00:44:36,071
and that we can actually find with
existing telescopes

785
00:44:36,089 --> 00:44:39,141
not a great thing is we can find them
but these telescopes are not big enough

786
00:44:39,609 --> 00:44:40,900
to actually

787
00:44:40,009 --> 00:44:43,228
do what we really want to do which is
dissect the light from these cameras

788
00:44:44,119 --> 00:44:46,020
take a specter

789
00:44:46,002 --> 00:44:49,004
actually use that to measure the
chemical composition of the universe at

790
00:44:49,022 --> 00:44:50,116
this very early stages

791
00:44:51,016 --> 00:44:54,425
now we expect this chemical composition
to be very different from what it is in

792
00:44:54,569 --> 00:44:56,030
the universe today

793
00:44:56,003 --> 00:44:59,332
because there were so few generations of
stars at that point

794
00:44:59,359 --> 00:45:02,454
that they have not fully enrich the
universe to the level that we see today

795
00:45:03,309 --> 00:45:07,314
in order to do that unfortunately our
existing telescopes are probably not

796
00:45:07,359 --> 00:45:08,160
going to be

797
00:45:08,016 --> 00:45:12,175
larger large enough to capture the light
but not the dissected

798
00:45:12,319 --> 00:45:15,374
so that we really need to go to the next
stage

799
00:45:15,869 --> 00:45:19,230
so luckily that next stage will happen
in the next arm

800
00:45:19,023 --> 00:45:23,392
seven to eight years so this is really
the future that's the last thing I want

801
00:45:23,599 --> 00:45:24,648
to tell you about

802
00:45:25,089 --> 00:45:28,960
this is the giant Magellan telescope
this is a computer in addition to what

803
00:45:28,096 --> 00:45:32,189
it will look like when it's completed
sometime around 2018 to 2020

804
00:45:33,089 --> 00:45:36,115
each one of these mirrors it's composed
of seven years each one of these mir's

805
00:45:37,015 --> 00:45:40,043
about 26 feet across

806
00:45:40,043 --> 00:45:43,702
okay so this whole thing across is about
25 near

807
00:45:44,089 --> 00:45:50,130
so and just to set the scale here's what
the biggest also sonora look like today

808
00:45:50,013 --> 00:45:53,472
this is what this possible

809
00:45:53,589 --> 00:45:56,910
of course the large it also appears the
more collecting area

810
00:45:56,091 --> 00:46:00,092
has the more lights Kingdom gather and
therefore it can see fainter and fainter

811
00:46:00,092 --> 00:46:01,531
objects

812
00:46:02,359 --> 00:46:05,490
all allowing us to actually dissect a
lot

813
00:46:05,049 --> 00:46:09,088
from from these gamma-ray burst in the
dark ages

814
00:46:09,088 --> 00:46:12,327
this is a an international law project
it

815
00:46:13,119 --> 00:46:17,470
it is actually a started construction on
on this facility is started

816
00:46:17,047 --> 00:46:21,406
it will be built in not chile julie has
now become the premier site for large

817
00:46:21,829 --> 00:46:23,180
telescopes

818
00:46:23,018 --> 00:46:27,147
arm and so work on this is ongoing
integrating I'm excited about is

819
00:46:27,309 --> 00:46:30,720
is the harvard is part of this project
and so we will get to use this telescope

820
00:46:30,072 --> 00:46:31,090
to study

821
00:46:31,009 --> 00:46:35,034
on the first stars in the universe well
just to show you that this is really

822
00:46:36,015 --> 00:46:37,051
happening

823
00:46:37,051 --> 00:46:40,350
here's the first of these arm seven
years

824
00:46:40,809 --> 00:46:44,420
okay so this is at the University of
Arizona me Rob where they produce a man

825
00:46:44,042 --> 00:46:47,181
manufactures mir's this mere is now

826
00:46:47,559 --> 00:46:50,770
has now been polished it took about four
years from the point of melting the

827
00:46:50,077 --> 00:46:50,145
glass

828
00:46:51,045 --> 00:46:54,069
to finishing the mirror and polishing is
on

829
00:46:54,069 --> 00:46:58,428
regular sized human beings scare

830
00:46:59,049 --> 00:47:04,210
so you don't get a sense so how enormous
just one of these mir's

831
00:47:04,021 --> 00:47:07,100
arm is and perhaps

832
00:47:07,289 --> 00:47:11,371
try to fathom what seventies look like
%uh pointed out that this cock

833
00:47:12,109 --> 00:47:15,690
so this is the next stage in this is our
I think what will really

834
00:47:15,069 --> 00:47:18,998
are allow us to move away from just
trying to understand what gamma ray

835
00:47:19,619 --> 00:47:20,637
bursts are

836
00:47:20,799 --> 00:47:23,878
to actually use email as probes of the
infinite universe

837
00:47:24,589 --> 00:47:29,665
arm to to get a basic understanding when
the first stars and galaxies for

838
00:47:30,349 --> 00:47:33,374
okay so I want to arm to end here all

839
00:47:33,599 --> 00:47:37,740
I hope you enjoy this forty your journey
from discovery to our

840
00:47:37,074 --> 00:47:40,091
first initial understanding of what
gamma ray bursts are

841
00:47:40,091 --> 00:47:44,093
and and you got a sense of where we
stand today arm

842
00:47:44,093 --> 00:47:47,189
was completely accidental discovery I
still find out fascinated

843
00:47:48,089 --> 00:47:51,498
nobody's ever predicted that the subject
to current

844
00:47:52,299 --> 00:47:56,140
now we use them to study the early
universe but this is really the next

845
00:47:56,014 --> 00:47:56,066
step

846
00:47:56,066 --> 00:47:58,152
arm finding gamma ray bursts in the
first few hundred million years after

847
00:47:59,052 --> 00:48:00,401
the Big Bang

848
00:48:00,869 --> 00:48:03,964
so thank you

849
00:48:04,819 --> 00:48:10,430
%ah

850
00:48:10,043 --> 00:48:13,422
brother that was actually S&M easing
talk thank you

851
00:48:13,809 --> 00:48:17,270
yeah I did actually didn't know any of
that

852
00:48:17,027 --> 00:48:20,296
am I have some questions though but you
can have

853
00:48:20,539 --> 00:48:24,270
other people ask questions should I so
should i scan I started to someone else

854
00:48:24,027 --> 00:48:26,029
wanna start with the question

855
00:48:26,047 --> 00:48:30,075
go ahead um so those two jets coming
into the black hole

856
00:48:30,075 --> 00:48:34,114
formation why does it look like that
like to Jess rather than

857
00:48:35,014 --> 00:48:38,068
yeah I said so the idea is that as this
something both types so

858
00:48:38,068 --> 00:48:42,121
system so we have a massive starts
rotating rapidly and then collapses

859
00:48:43,021 --> 00:48:46,038
there's a preferred access the angular
momentum access

860
00:48:46,038 --> 00:48:50,947
where the material collapses into a desk
and then this access remains evacuated

861
00:48:51,289 --> 00:48:52,220
and the jet can

862
00:48:52,022 --> 00:48:55,131
emerge from that election is there
evidence for that

863
00:48:55,329 --> 00:48:59,210
yes it is actual observational evidence
we see the signature of this

864
00:48:59,021 --> 00:49:03,093
jet in our arm visible-light
observations above the afterglow

865
00:49:03,093 --> 00:49:07,262
in fact you can actually measure the
opening on the job and so what we found

866
00:49:08,099 --> 00:49:11,144
from observations tens of gamma-ray
bursts now is that these jets are

867
00:49:11,549 --> 00:49:12,510
anywhere from

868
00:49:12,051 --> 00:49:16,140
down to one or two degrees up to maybe
ten or twenty degrees

869
00:49:16,599 --> 00:49:19,643
some of them are extremely narrow yeah

870
00:49:20,039 --> 00:49:24,045
so I have one more question a you think
there are two sources

871
00:49:24,099 --> 00:49:27,126
how do you know there's not 3 because
you did at the beginning didn't

872
00:49:27,369 --> 00:49:30,413
look like just two different things
that's right I think that's a very good

873
00:49:30,809 --> 00:49:34,750
question people have been arguing for a
while about whether these two groups

874
00:49:34,075 --> 00:49:37,924
um some somewhere on whether mergers a
third group of objects

875
00:49:38,599 --> 00:49:42,410
off for now I think we can explain
everything we see we just to

876
00:49:42,041 --> 00:49:45,910
types of objects to produce gamma ray
bursts as we collect more and more these

877
00:49:46,279 --> 00:49:48,990
gamers we are finding to have them every
week

878
00:49:48,099 --> 00:49:52,398
arm there might emerge more evidence for
third population brain hours

879
00:49:53,289 --> 00:49:56,920
i'm satisfied so there's no new physics

880
00:49:56,092 --> 00:50:00,115
well I think the physics so how to
actually form the black hole in how the

881
00:50:01,015 --> 00:50:03,394
black hole produces the jet

882
00:50:03,529 --> 00:50:06,660
at this point is completely the black
magic

883
00:50:06,066 --> 00:50:09,092
so when I tell you that a gamma-ray
burst from the black hole in the black

884
00:50:09,092 --> 00:50:11,151
hole extract energy and produces a jet

885
00:50:12,051 --> 00:50:17,070
that's all grades by there is currently
no theory that explains how that happens

886
00:50:17,529 --> 00:50:20,140
from basic physics principles

887
00:50:20,014 --> 00:50:23,021
okay to want to come to the microphone
to ask a question

888
00:50:23,021 --> 00:50:29,042
thanks

889
00:50:29,042 --> 00:50:33,671
so secondly

890
00:50:34,049 --> 00:50:37,076
so actually words water aft

891
00:50:37,319 --> 00:50:42,323
cool it does I to rate a question so the
first question was what a gamma-ray

892
00:50:42,359 --> 00:50:44,440
bursts produce Garrett Asian waves

893
00:50:44,044 --> 00:50:47,089
in the answer is yes in particular the
gamma-ray bursts are formed by the

894
00:50:47,089 --> 00:50:49,097
merger of two neutron stars

895
00:50:49,097 --> 00:50:52,196
does neutron stars are two masked to
very heavy masses

896
00:50:53,069 --> 00:50:56,750
orbiting each other and producing an
enormous amount of gravitational waves

897
00:50:56,075 --> 00:51:00,384
in fact the air defense like oh
Observatory which is being built now and

898
00:51:01,059 --> 00:51:03,210
designed to detect gravitational waves

899
00:51:03,021 --> 00:51:06,063
will primarily seed amor those objects

900
00:51:06,063 --> 00:51:09,119
those neutron stars merging to each
other is one factor hope is that once

901
00:51:10,019 --> 00:51:11,116
that Observatory gets going

902
00:51:12,016 --> 00:51:15,025
we will see the gravitational wave
signal right before the two objects

903
00:51:15,025 --> 00:51:15,834
merge

904
00:51:16,059 --> 00:51:19,133
and that will be followed up by gamers
so that will be our most

905
00:51:19,799 --> 00:51:22,930
direct test that these neutron star
bunnies actually

906
00:51:22,093 --> 00:51:25,722
I make are going to show its erotic
personals what are the extreme was part

907
00:51:26,559 --> 00:51:27,900
of the afterglow

908
00:51:27,009 --> 00:51:30,095
yes the X-rays are there some x-ray
emission that comes as part of the

909
00:51:31,076 --> 00:51:33,123
gamma-ray burst itself it's very weak

910
00:51:34,023 --> 00:51:41,023
for then the afterglow itself produces
additional x-ray radiation

911
00:51:48,559 --> 00:51:49,060
from the ground

912
00:51:49,006 --> 00:51:52,062
ocean waves yes I think there'll be a
fantastic television yes

913
00:51:52,062 --> 00:51:59,062
so in the formation of galaxies their
the

914
00:52:01,071 --> 00:52:04,147
idea massive black holes at the center

915
00:52:05,047 --> 00:52:09,071
is there any relationship with these
gamma-ray burst

916
00:52:09,071 --> 00:52:14,076
to the has two black hole for you
mission especially in the restart

917
00:52:15,021 --> 00:52:20,030
your your art yes that's a very good
question and so the question is whether

918
00:52:20,003 --> 00:52:23,015
them at this very supermassive black
holes are sitting in the centers of

919
00:52:23,042 --> 00:52:24,096
galaxies are responsible

920
00:52:24,096 --> 00:52:27,138
or related to gamers anyway I Indian
sarees

921
00:52:28,038 --> 00:52:31,044
they're not related to the camera person
I've shown you because when

922
00:52:31,098 --> 00:52:34,135
when we can pinpoint their location we
don't see them coming from the centers

923
00:52:35,035 --> 00:52:37,097
of galaxies we always see them coming
from the outside

924
00:52:37,097 --> 00:52:40,160
more where the stars are forming not
from the center arm

925
00:52:41,006 --> 00:52:44,042
there are events arm called on

926
00:52:44,096 --> 00:52:47,140
title disruption so once in a while

927
00:52:48,004 --> 00:52:51,031
are in the centers of the scouts what a
massive black hole is sitting

928
00:52:51,067 --> 00:52:55,125
are a star constrain very close the
black hole and actually get destroyed

929
00:52:56,025 --> 00:53:00,100
blackwell this is very similar to what
is happening here to destroy the star

930
00:53:01,000 --> 00:53:04,006
near the black hole and then all the
material drains into the black hole you

931
00:53:04,006 --> 00:53:06,007
can produce something that looks like a
gamma-ray bursts

932
00:53:06,016 --> 00:53:09,032
in fact we saw this for the first time
about two years ago

933
00:53:09,032 --> 00:53:13,036
was an event at arm was discovered by
one these gamers satellites

934
00:53:13,072 --> 00:53:16,089
that looked initially very much like a
regular gamma-ray burst

935
00:53:16,089 --> 00:53:19,151
but then ended up lasting for a whole
week which can reverse never do they

936
00:53:20,051 --> 00:53:21,076
only last for a few seconds

937
00:53:21,076 --> 00:53:24,145
arm and that event came from the center
of its Galaxy

938
00:53:25,045 --> 00:53:28,077
where we noted there is a supermassive
black hole think it was calls

939
00:53:28,077 --> 00:53:32,090
by this process by started just
unfortunately strayed

940
00:53:32,009 --> 00:53:39,009
to close the black on cots City

941
00:53:42,048 --> 00:53:45,083
the actual formation of supermassive
black holes is not fully understood but

942
00:53:45,083 --> 00:53:47,115
it's it's not clear that they will
necessarily produce

943
00:53:48,015 --> 00:53:51,112
gamers and it probably takes are much
larger period of time to

944
00:53:52,012 --> 00:53:55,073
to produce one of these large black
holes so will not produce something that

945
00:53:55,073 --> 00:53:56,109
only last for a few seconds

946
00:53:57,009 --> 00:54:03,016
yeah %um so will you be able to measure
the

947
00:54:03,016 --> 00:54:07,051
amount of primordial the VM 20 better
precision and answer the

948
00:54:07,051 --> 00:54:11,058
looking problem that is a very good
question I think that

949
00:54:12,021 --> 00:54:17,036
arm it's unlikely because I think that
most of that is a rising much earlier

950
00:54:17,036 --> 00:54:18,041
before we

951
00:54:18,041 --> 00:54:22,098
think that any stars actually form so
that has to do more with nucleosynthesis

952
00:54:22,098 --> 00:54:24,102
that happened during the Big Bang itself

953
00:54:25,002 --> 00:54:28,055
arm in the first few minutes after the
Big Bang

954
00:54:28,055 --> 00:54:31,060
and I nobody right now thinks that
stores conform that early

955
00:54:32,005 --> 00:54:36,032
I'm you know we are current
understandings stars form some of you

956
00:54:36,032 --> 00:54:37,063
wanted million years after the Big

957
00:54:37,063 --> 00:54:40,118
so it's not obvious that gamers will
contribute specifically did not question

958
00:54:41,018 --> 00:54:45,104
what they will allow us to see for
example is how you know how oxygen

959
00:54:46,004 --> 00:54:50,031
are increased in abundance as the
universe I became older ha carbon and

960
00:54:50,031 --> 00:54:50,083
silicon

961
00:54:50,083 --> 00:54:53,135
the other elements some point a lot for
example were in abundance

962
00:54:54,035 --> 00:55:01,035
you talk about a

963
00:55:01,075 --> 00:55:04,133
seeing how in past how everything

964
00:55:05,033 --> 00:55:08,058
was how it's going to be is it possible
to see

965
00:55:08,058 --> 00:55:11,082
further beyond where we are right now
richer

966
00:55:11,082 --> 00:55:16,109
univers is obviously work I'm certain
spark a new look into the future and see

967
00:55:17,009 --> 00:55:17,090
where we're going

968
00:55:17,009 --> 00:55:20,087
these elements as far as camera
reporters have never seen something you

969
00:55:21,068 --> 00:55:21,093
know

970
00:55:21,091 --> 00:55:24,145
have where we are specifically Milky Way
in

971
00:55:25,045 --> 00:55:28,126
where first so you know is we look

972
00:55:29,026 --> 00:55:33,071
arm further and further are in the
universe recession looking back and talk

973
00:55:33,071 --> 00:55:36,167
because we're relying on light and light
has a finite speed so

974
00:55:37,067 --> 00:55:40,094
as the light travels to Los it takes a
certain amount of time so when

975
00:55:40,094 --> 00:55:43,150
when we see these gamers essentially get
a view of the universe in the past

976
00:55:44,005 --> 00:55:47,092
is really no way to turn that around and
saying let's try to see what it will

977
00:55:48,037 --> 00:55:49,043
look like in the future

978
00:55:49,043 --> 00:55:52,096
so we can get a glimpse of what universe
looks like today by looking just around

979
00:55:52,096 --> 00:55:54,192
the house in the local vicinity of the
Milky Way galaxy

980
00:55:55,092 --> 00:55:58,109
or we can look at these very distant
objects which give us a view

981
00:55:59,009 --> 00:56:03,092
of the past history of its but Bay if we
have enough information we can

982
00:56:03,092 --> 00:56:06,163
potentially predict what we expect the
universe to look like in the future

983
00:56:07,063 --> 00:56:10,147
a any high school students have
questions

984
00:56:11,047 --> 00:56:15,141
been up and we'll have an adult

985
00:56:16,041 --> 00:56:19,077
North I'm

986
00:56:19,077 --> 00:56:23,081
to basic question what you said said you
showed us

987
00:56:24,017 --> 00:56:28,024
these a very focused

988
00:56:28,087 --> 00:56:31,130
beams from from both server them the

989
00:56:32,003 --> 00:56:35,011
the way some forming gamma-ray burst but
so when we

990
00:56:36,001 --> 00:56:39,062
observed gunnery purse is it because the
beam is

991
00:56:39,071 --> 00:56:43,136
swept across year

992
00:56:44,036 --> 00:56:47,123
earth where we just seen says says

993
00:56:48,023 --> 00:56:53,104
from other eg

994
00:56:54,004 --> 00:56:57,032
as SPECT and two to

995
00:56:57,032 --> 00:57:00,057
the ones that you found there in did to

996
00:57:00,057 --> 00:57:03,092
doe dark ages creases

997
00:57:03,092 --> 00:57:07,123
superbly their form from the your gun
stores in

998
00:57:08,023 --> 00:57:11,067
not from that the nutrient stars but
you'd

999
00:57:11,067 --> 00:57:15,111
didn't mention that yes so so does it
again two very good questions so

1000
00:57:16,011 --> 00:57:20,013
arm so because the beams are so narrow
we will only see a gamma-ray burst if

1001
00:57:20,013 --> 00:57:21,095
the beam is pointed at us

1002
00:57:21,095 --> 00:57:24,173
make because the beam doesn't move so
it's not like a pulsar word

1003
00:57:25,073 --> 00:57:29,098
being rotatable we seek once in a while
so that means that if the

1004
00:57:29,098 --> 00:57:32,193
beams are very narrow then for every
gamma-ray burst that we see there about

1005
00:57:33,093 --> 00:57:34,171
a hundred that we will never see

1006
00:57:35,071 --> 00:57:39,077
because those beams were appointed
somewhere else okay so

1007
00:57:39,077 --> 00:57:43,112
in fact we now know that there are about
200 times more gamma reports than the

1008
00:57:44,012 --> 00:57:45,100
ones we actually observed

1009
00:57:46,000 --> 00:57:49,019
due to this effect now as the other
question

1010
00:57:49,019 --> 00:57:53,080
yes the gamma-ray burst that we see at
in the dark ages are the long

1011
00:57:53,008 --> 00:57:56,014
duration for it. that we think are due
to the

1012
00:57:56,086 --> 00:58:00,143
very massive stars with very short
lifetimes we don't really expect to see

1013
00:58:01,043 --> 00:58:04,128
at this early stages of the universe
already mergers neutron stars

1014
00:58:05,028 --> 00:58:08,106
arm although that's again that's our

1015
00:58:09,006 --> 00:58:12,055
theoretical thinking right now the
universe might surprise us my choice

1016
00:58:12,055 --> 00:58:13,057
that perhaps

1017
00:58:13,075 --> 00:58:16,139
some of these me mortgage more rapidly
thoughts possible

1018
00:58:17,039 --> 00:58:21,101
if we see the short duration gamma ray
bursts that these very large distances

1019
00:58:22,001 --> 00:58:25,009
there will be an indication that some of
these neutron stars already born in

1020
00:58:25,081 --> 00:58:25,110
there

1021
00:58:26,001 --> 00:58:29,006
the smash into each other within the
first few hundred

1022
00:58:29,015 --> 00:58:35,026
big well right now they're all the long
duration

1023
00:58:35,026 --> 00:58:39,082
so up that was wonderful um let's think
the speaker again

1024
00:58:39,082 --> 00:58:39,107
and