WEBVTT

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- I'd like to introduce our
guest speaker for tonight

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here at Space Place.

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Tonight I'm very pleased
to introduce an astronomer

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from the UW
Astronomy Department,

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but also a friend of
mine, Eric Hooper.

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Eric came to us,

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he got his PhD at the University
of Arizona in astronomy,

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and then came here
after working at

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UT Austin, came here to
Madison where he's been here

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for a few years now doing
a lot of different things,

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but including a two-year
stint as director of the
WIYN Observatories.

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You might remember the W
in WIYN is for Wisconsin.

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It's a set of telescopes
that we manage from here,

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and Eric was the director
of those for a term there.

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But tonight, he's gonna tell
us about some of his research

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with the intriguing
phrase cosmic archeology,

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but I'm gonna turn it
over to him right now.

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So please welcome Eric Hooper.

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[clapping]

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- Thank you, Jim.

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And thank you everybody for
coming out this evening.

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I really appreciate it.
We have a big crowd here.

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I'm gonna start out by
just giving a shout out

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to the organization
that's funding this work,

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and that's the National
Science Foundation.

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They provide funding
across the country

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for a lot of different
interesting science,

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not just in astronomy, but
across the whole spectrum

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of science, technology,
engineering, and mathematics.

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And I'm not the only
one on this project.

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So let me introduce some of
the other cosmic archeologists.

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I've included the pictures
of our local team here.

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These are all University of
Wisconsin Madison astronomers.

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The two on the left and right
are graduate students who,

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of course, do most of the work.

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The person in the middle
is the PI or the
principal investigator.

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She's the leader of the grant.

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The other two are faculty
collaborators of ours.

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But we're not just a
UW of Madison team.

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There are other people
I've showcased down
here at the bottom.

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These are collaborators
from across the country,

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and as you also see, from
other parts of the world.

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These are part a large
international team

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called the Sloan
Digital Sky Survey.

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We'll talk more about
that later in the talk,

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so I'm just giving you a little
foreshadowing of that here.

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And one of the themes about
this that you're gonna see

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throughout this talk is that
a lot of modern scientific

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research, including in
astronomy, is done by teams

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of people, this is actually
a relatively small team,

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and also utilizing
a wide variety

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of different technologies
and techniques.

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That's gonna be part of
the story of this evening,

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is what those techniques
and technologies

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we're using to address
the project I'm
gonna tell you about.

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Well first, we have to
deal with that title,

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that weird title
that Jim alluded to.

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He's really hoping I'm
gonna explain what it is.

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I know that some of
you may be thinking,

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"Oh, that guy, this
is a marketing ploy.

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"He just made up the weirdest
title he could think of

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"to get a crowd out tonight."

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Well, maybe a little bit.

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But the fun part of
tonight's talk is

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that it is not completely crazy.

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There's actually
a grain of truth

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in everything in that title,

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and I'm gonna explain a
little bit of that here.

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And the entire talk
is encapsulated,
really, in the title.

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So it's more than
just crazy marketing.

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There really is meaning to
everything that's in that title,

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and I just wanna unpack
that a little bit here.

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But first, a quick
story, little anecdote,

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how I actually
came up with this.

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It wasn't for this talk,

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although the details
of it for this talk,

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but it occurred to me while
I was traveling sometime.

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I was flying and I
was on an airplane.

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And, as often happens,
you sit next to somebody

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and they ask, "Well, where're
you going after Chicago?"

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And after you say, "Well,
I'm going to Kalamazoo

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"and they're going
to Walla Walla,"

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then the conversation goes to,

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"Oh, well, what do
you do for a career?"

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And we sometimes get some
interesting responses

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when we say we're astronomers,

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because there's just not
that many of us in the world.

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And some people find
that really intriguing.

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Some people find
that really strange

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and they don't know what to do.

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and I've often thought,
"What could I say

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"that would have a
grain of truth to it

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"that would really make people
think it's kinda weird?"

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So I've thought, I guess I
could say, given the project
I'm working on now,

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I could turn to them.

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I could say, "Yeah, so, I'm

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"a time-traveling
cosmic archeologist.

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"And by the way, let's talk
about this on the 15-hour
flight to Shanghai."

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[laughing]
All right.

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So let's unpack what
I actually mean here.

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Clearly the most
ridiculous sounding part

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of that whole title
is the archeology.

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I mean, what does astronomy
have to do with archeology,

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other than they
both start with A?

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I have heard, oftentimes,
that astronomers,

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and maybe others, use
archeology as sort

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of a metaphor for astronomy.

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Here's why.

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Because there is an element
of looking into the past

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that's inherent in astronomy.

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The reason for
that is that light,

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and any information
that comes with it,

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has a finite travel time.

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Now, that may not be readily
apparent to us in this room

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because the speed of
light is so rapid,

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but when you're talking
about the vast distances

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that we are often dealing
with in astronomy,

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then it starts
becoming relevant.

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For example, the Sun's
light that we see,

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is already a few minutes old.

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That's not that far in the past.

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Center of the galaxy,
when we look at it,

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is over 20,000 years old.

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The nearest large galaxy,

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now we're going over
a million years old.

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So by having things very far
away when we look at them,

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we are inherently
looking into the past.

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Maybe a more
down-to-earth analogy.

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I don't know if maybe
today in middle school

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and in elementary school
they don't do this,

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but in my time kids would
pass notes to each other.

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So here's the analogy.

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Somebody starts passing
around the note around school

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that so-and-so likes
whosie-what-sit.

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And by the time that note
makes it all the way

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around school, so-and-so
and whosie-what-sit have
already broken up.

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So by the time you get
that, if you're at the end

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of the chain, you have just
discovered information,

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it's real information,
but it is lagging in time.

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It's out of date.

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And that is unavoidable
in astronomy.

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And so that's why
people often will say,

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"Astronomy's a little bit like
archeology in that sense."

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But not really.

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There is a difference.

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And in astronomy, when
you're looking back in time

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at something that is old
because it's far away,

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it's not that we are digging
up pieces of the past

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and looking at them
as they are now.

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It's as though we are
actually able to look at

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what really happened.

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Take Pompeii, for example,
on that fateful day

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when Vesuvius blew up.

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It would be as though rather
than going to Pompeii now

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and unearthing artifacts
from that time,

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we were able to look
from a distance and watch

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the life of the
city in the morning,

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watch the residents go about
their day on that final day.

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Now, it would not
be a very clear view

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because it would be
a long ways away.

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We would not have really good
images or pictures of it,

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but that's what
we would be doing.

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We'd actually see
it going through

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and happening as it occurred.

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So in that sense, it's
not like archeology.

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That's the time travel
bit in my title.

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But wait, there is also
an element of archeology,

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in that what we
are trying to do,

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and I'm going to
describe to you,

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is look back in time

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at distant objects and
look for artifacts.

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So we are doing both.

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It is time traveling
and it is archeology.

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We're trying to understand
what has been happening

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with galaxies and the
black holes they contain,

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at times previous
to when we see them.

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Why? We'll talk about that.

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So, we're gonna talk

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about a fair number of
things this evening.

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Big ones are black
holes and galaxies.

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That's what this whole
project is about.

08:02.300 --> 08:05.133 align:left position:12.5%,start line:83% size:77.5%
By the way, this project, this
time traveling archeology,

08:05.233 --> 08:07.000 align:left position:22.5%,start line:89% size:67.5%
this is a field report.

08:07.100 --> 08:09.633 align:left position:12.5%,start line:83% size:77.5%
We're not completely done yet.
We're in the middle of it.

08:09.733 --> 08:11.600 align:left position:15%,start line:83% size:75%
We've got a lot of work done.
This is an update.

08:11.700 --> 08:13.933 align:left position:20%,start line:83% size:70%
This is like when you're
watching a show about archeology

08:14.033 --> 08:16.333 align:left position:27.5%,start line:83% size:62.5%
on TV and they are
just starting the dig

08:16.433 --> 08:18.266 align:left position:15%,start line:83% size:75%
and they're out in the jungle
and they're getting hot

08:18.366 --> 08:20.166 align:left position:22.5%,start line:83% size:67.5%
and sweaty and they're
getting bitten by scorpions,

08:20.266 --> 08:23.133 align:left position:17.5%,start line:77% size:72.5%
that's where we are, we're
at the scorpion-biting
phase of this.

08:23.233 --> 08:25.566 align:left position:27.5%,start line:83% size:62.5%
So we're gonna talk
about black holes,

08:25.666 --> 08:29.266 align:left position:20%,start line:83% size:70%
supermassive or monstrous
black holes, and galaxies.

08:29.366 --> 08:31.266 align:left position:15%,start line:89% size:75%
The black holes living inside

08:31.366 --> 08:33.300 align:left position:12.5%,start line:83% size:77.5%
at the centers of the galaxies,
how are they connected?

08:33.400 --> 08:36.066 align:left position:22.5%,start line:83% size:67.5%
That's the fundamental
question that we're after.

08:36.166 --> 08:38.933 align:left position:27.5%,start line:83% size:62.5%
And what have these
been doing in the past,

08:39.033 --> 08:40.700 align:left position:22.5%,start line:83% size:67.5%
specifically the stars
that are in the galaxies?

08:40.800 --> 08:42.866 align:left position:20%,start line:83% size:70%
Galaxies are made up of a
bunch of different things

08:42.966 --> 08:46.066 align:left position:17.5%,start line:77% size:72.5%
that we'll talk about here
in a minute, but the stars,
what have they been doing?

08:46.166 --> 08:49.733 align:left position:22.5%,start line:83% size:67.5%
And what have the black
holes been up to in the past?

08:50.833 --> 08:53.066 align:left position:22.5%,start line:83% size:67.5%
We're gonna talk about
some new observations

08:53.166 --> 08:54.833 align:left position:17.5%,start line:89% size:72.5%
with a big radio telescope.

08:54.933 --> 08:56.766 align:left position:22.5%,start line:83% size:67.5%
You may be thinking of
the one in New Mexico.

08:56.866 --> 08:58.400 align:left position:32.5%,start line:83% size:57.5%
Some people may
be aware of that.

08:58.500 --> 09:01.433 align:left position:22.5%,start line:83% size:67.5%
A little farther away,
a little bit bigger.

09:01.533 --> 09:05.133 align:left position:20%,start line:5% size:70%
As I mentioned, a lot of
modern science needs multiple

09:05.233 --> 09:08.166 align:left position:25%,start line:5% size:65%
different approaches
all integrated together.

09:08.266 --> 09:11.266 align:left position:15%,start line:5% size:75%
One of the things we're doing
are massive simulations,

09:11.366 --> 09:14.966 align:left position:10%,start line:5% size:80%
theoretical work using computers
to try to understand better

09:15.066 --> 09:17.633 align:left position:17.5%,start line:5% size:72.5%
what we're actually seeing
with some of these telescopes.

09:17.733 --> 09:21.800 align:left position:20%,start line:5% size:70%
And also, we're utilizing
visible light surveys

09:21.900 --> 09:23.400 align:left position:27.5%,start line:5% size:62.5%
of the sky as well.

09:23.500 --> 09:26.166 align:left position:25%,start line:5% size:65%
So that's where we're
going this evening.

09:28.166 --> 09:30.166 align:left position:20%,start line:5% size:70%
Black holes and galaxies.

09:30.266 --> 09:32.166 align:left position:20%,start line:5% size:70%
I talked about that this
was gonna be a connection

09:32.266 --> 09:34.700 align:left position:20%,start line:5% size:70%
between them, a story of
the connection between them.

09:34.800 --> 09:36.933 align:left position:25%,start line:5% size:65%
Time traveling in the
sense of looking backward

09:37.033 --> 09:39.933 align:left position:15%,start line:5% size:75%
or into the past and see how
they actually were at time.

09:40.033 --> 09:42.366 align:left position:15%,start line:5% size:75%
Archeology in the sense that
we are going to be looking

09:42.466 --> 09:48.566 align:left position:20%,start line:5% size:70%
at relics in the past of
yet even in earlier history

09:48.666 --> 09:50.866 align:left position:25%,start line:5% size:65%
of both the galaxies
and the black holes.

09:50.966 --> 09:53.100 align:left position:22.5%,start line:5% size:67.5%
But before we dig into
these connections,

09:53.200 --> 09:56.300 align:left position:27.5%,start line:5% size:62.5%
let's actually talk
about, remind ourselves

09:56.400 --> 09:59.633 align:left position:20%,start line:5% size:70%
what are the black holes
and what are galaxies?

09:59.733 --> 10:01.633 align:left position:30%,start line:89% size:60%
On the left here,

10:01.733 --> 10:05.766 align:left position:20%,start line:83% size:70%
is a series of depictions
of a black hole.

10:06.933 --> 10:09.200 align:left position:27.5%,start line:83% size:62.5%
Little bit hard to
get a real picture.

10:09.300 --> 10:11.100 align:left position:25%,start line:83% size:65%
This is more than an
artist's conception.

10:11.200 --> 10:13.133 align:left position:27.5%,start line:83% size:62.5%
This is actually a
computer simulation

10:14.433 --> 10:17.300 align:left position:25%,start line:83% size:65%
of a disk of material
around a black hole.

10:17.400 --> 10:19.700 align:left position:25%,start line:89% size:65%
Anybody recognize it?

10:19.800 --> 10:22.066 align:left position:15%,start line:89% size:75%
It may look vaguely familiar.

10:22.166 --> 10:24.133 align:left position:17.5%,start line:89% size:72.5%
It's a simulation that went

10:24.233 --> 10:26.466 align:left position:27.5%,start line:83% size:62.5%
into the Hollywood
movie Interstellar.

10:27.533 --> 10:30.433 align:left position:20%,start line:83% size:70%
So that the filmmakers
there wanted to have as much

10:30.533 --> 10:32.400 align:left position:27.5%,start line:83% size:62.5%
scientific accuracy
as they could

10:32.500 --> 10:34.366 align:left position:22.5%,start line:83% size:67.5%
within the constraints
of the production.

10:34.466 --> 10:36.366 align:left position:25%,start line:83% size:65%
So one of their major
scientific advisor,

10:36.466 --> 10:38.166 align:left position:22.5%,start line:83% size:67.5%
who I understand worked
very closely with them,

10:38.266 --> 10:40.166 align:left position:15%,start line:89% size:75%
is a fellow named Kip Thorne.

10:40.266 --> 10:43.700 align:left position:22.5%,start line:83% size:67.5%
Kip Thorne recently won
the Nobel Prize in physics

10:43.800 --> 10:45.800 align:left position:32.5%,start line:83% size:57.5%
for working on
gravity-related things.

10:45.900 --> 10:49.033 align:left position:17.5%,start line:83% size:72.5%
So he knows a thing or two
about black holes and gravity.

10:49.133 --> 10:51.100 align:left position:20%,start line:83% size:70%
He has literally written
some of the books on them.

10:51.200 --> 10:53.800 align:left position:25%,start line:83% size:65%
He worked with their
special effects team

10:53.900 --> 10:57.533 align:left position:22.5%,start line:83% size:67.5%
to make as realistic as
possible simulations.

10:57.633 --> 10:59.800 align:left position:10%,start line:89% size:80%
So going down from the top here,

10:59.900 --> 11:02.700 align:left position:20%,start line:83% size:70%
if anybody saw the movie,
this is closest

11:02.800 --> 11:05.233 align:left position:25%,start line:83% size:65%
to what was actually
depicted in the movie.

11:05.333 --> 11:06.833 align:left position:30%,start line:83% size:60%
The black hole is
here in the middle.

11:06.933 --> 11:09.100 align:left position:27.5%,start line:83% size:62.5%
More specifically,
that's its event horizon.

11:09.200 --> 11:12.600 align:left position:17.5%,start line:83% size:72.5%
And this material around it
is called the accretion disk.

11:12.700 --> 11:15.766 align:left position:25%,start line:83% size:65%
It's material flowing
into the black hole.

11:17.200 --> 11:21.766 align:left position:20%,start line:83% size:70%
This was depicted in the
movie, but more realistic

11:21.866 --> 11:24.200 align:left position:12.5%,start line:89% size:77.5%
are these down here, these two.

11:24.300 --> 11:25.900 align:left position:22.5%,start line:83% size:67.5%
These are progressively
more realistic.

11:26.000 --> 11:29.200 align:left position:17.5%,start line:83% size:72.5%
What they put in the movie
did not have an effect

11:29.300 --> 11:31.900 align:left position:17.5%,start line:83% size:72.5%
known as Doppler shifting,
which changes colors

11:32.000 --> 11:34.366 align:left position:20%,start line:83% size:70%
depending on whether the
material's moving towards you

11:34.466 --> 11:35.766 align:left position:30%,start line:89% size:60%
or away from you.

11:35.866 --> 11:37.933 align:left position:25%,start line:83% size:65%
And there is also an
effect of relativity

11:38.033 --> 11:40.133 align:left position:20%,start line:83% size:70%
that makes things moving
very fast towards you

11:40.233 --> 11:43.933 align:left position:17.5%,start line:83% size:72.5%
appear brighter, over here,
and things that are moving

11:44.033 --> 11:45.666 align:left position:30%,start line:83% size:60%
quickly away from
you appear dimmer.

11:45.766 --> 11:49.966 align:left position:25%,start line:83% size:65%
So this is how, right
here, a bit closer

11:50.066 --> 11:53.066 align:left position:25%,start line:83% size:65%
to how the black hole
would be more realistically

11:53.166 --> 11:55.933 align:left position:17.5%,start line:83% size:72.5%
in appearance, but that was
thought to be a little bit,

11:56.033 --> 11:57.633 align:left position:20%,start line:83% size:70%
potentially too confusing
to the audience.

11:57.733 --> 12:00.233 align:left position:20%,start line:83% size:70%
I was reading about this,
interestingly enough,

12:00.333 --> 12:04.166 align:left position:22.5%,start line:83% size:67.5%
in a scientific paper,
in a journal called,

12:04.266 --> 12:06.133 align:left position:10%,start line:83% size:80%
<i>Classical and Quantum Gravity</i>,
Kip Thorne

12:06.233 --> 12:09.600 align:left position:22.5%,start line:83% size:67.5%
and the special effects
people wrote a paper,

12:09.700 --> 12:12.500 align:left position:15%,start line:5% size:75%
more than one, I think, about
doing movie special effects

12:12.600 --> 12:14.066 align:left position:30%,start line:5% size:60%
in Classical and
Quantum Gravity.

12:14.166 --> 12:15.933 align:left position:32.5%,start line:5% size:57.5%
It's actually a
really fun paper.

12:16.033 --> 12:19.133 align:left position:20%,start line:5% size:70%
And down here, finally...

12:19.233 --> 12:24.700 align:left position:15%,start line:83% size:75%
This is an attempt to explain
why it looks so weird.

12:24.800 --> 12:26.666 align:left position:22.5%,start line:83% size:67.5%
Anybody, when they saw
the movie, wondered

12:26.766 --> 12:29.800 align:left position:10%,start line:83% size:80%
why is there material, if you've
heard of an accretion disk,

12:29.900 --> 12:33.800 align:left position:15%,start line:83% size:75%
why is it above and below as
well as from side to side?

12:33.900 --> 12:38.266 align:left position:20%,start line:83% size:70%
It's an effect of gravity
called gravitational lensing.

12:38.366 --> 12:41.266 align:left position:12.5%,start line:89% size:77.5%
This up here is a colored disk.

12:41.366 --> 12:45.100 align:left position:20%,start line:83% size:70%
It's a color swatch that
changes color radiating outward

12:45.200 --> 12:47.433 align:left position:32.5%,start line:83% size:57.5%
and is the same
all the way around.

12:47.533 --> 12:51.466 align:left position:17.5%,start line:83% size:72.5%
If you take this and put it
in front of the black hole,

12:51.566 --> 12:54.466 align:left position:22.5%,start line:83% size:67.5%
because of the warping
of space time by gravity,

12:54.566 --> 12:56.300 align:left position:25%,start line:89% size:65%
this is what you see.

12:56.400 --> 12:58.966 align:left position:20%,start line:83% size:70%
So this is really just a
nice, uniform color swatch,

12:59.066 --> 13:01.533 align:left position:27.5%,start line:83% size:62.5%
but see how it gets
distorted around there?

13:01.633 --> 13:04.700 align:left position:15%,start line:83% size:75%
Gravitational effects through
the warping of space time.

13:04.800 --> 13:07.533 align:left position:20%,start line:83% size:70%
Anyway, that's my little
introduction into black holes.

13:07.633 --> 13:10.066 align:left position:17.5%,start line:5% size:72.5%
By the way, I, and it turns
out, other astronomers,

13:10.166 --> 13:11.933 align:left position:30%,start line:5% size:60%
had assumed that
when we saw the movie

13:12.033 --> 13:15.333 align:left position:17.5%,start line:5% size:72.5%
that this is what's called
a stellar mass black hole,

13:15.433 --> 13:18.100 align:left position:27.5%,start line:5% size:62.5%
something that has
relatively, as you will see,

13:18.200 --> 13:20.800 align:left position:25%,start line:5% size:65%
low mass, though it's
not low by our standards,

13:20.900 --> 13:23.966 align:left position:10%,start line:5% size:80%
a few times the mass of our Sun.

13:25.066 --> 13:29.133 align:left position:20%,start line:5% size:70%
And it's the product of a
large massive star dying

13:29.233 --> 13:31.033 align:left position:10%,start line:5% size:80%
leads to a black hole like that.

13:31.133 --> 13:32.733 align:left position:32.5%,start line:5% size:57.5%
We all assumed
that's what this is.

13:32.833 --> 13:35.633 align:left position:12.5%,start line:5% size:77.5%
Well, in reading about it, Kip
Thorne actually modeled this

13:35.733 --> 13:37.600 align:left position:27.5%,start line:5% size:62.5%
as what's called a
supermassive black hole.

13:37.700 --> 13:40.466 align:left position:27.5%,start line:5% size:62.5%
The black hole that
was in the simulations

13:40.566 --> 13:43.600 align:left position:25%,start line:5% size:65%
is 100,000,000 times
the mass of our Sun.

13:43.700 --> 13:46.633 align:left position:22.5%,start line:5% size:67.5%
And I was delighted to
see that, because what I
am talking about here

13:46.733 --> 13:48.466 align:left position:15%,start line:5% size:75%
are supermassive black holes,

13:48.566 --> 13:50.100 align:left position:30%,start line:5% size:60%
black holes with
masses of millions

13:50.200 --> 13:52.600 align:left position:25%,start line:5% size:65%
and even billions of
times the mass of the Sun.

13:52.700 --> 13:55.266 align:left position:17.5%,start line:5% size:72.5%
So this is actually a very
relevant depiction of this.

13:55.366 --> 13:58.633 align:left position:17.5%,start line:5% size:72.5%
So that's a bit about black
holes, supermassive ones.

13:58.733 --> 14:01.633 align:left position:25%,start line:5% size:65%
They live in here, in
the middle of the galaxy.

14:03.433 --> 14:05.333 align:left position:25%,start line:89% size:65%
We live in a galaxy.

14:05.433 --> 14:07.833 align:left position:20%,start line:83% size:70%
If you go outside, maybe
later at night if it's clear,

14:07.933 --> 14:11.000 align:left position:12.5%,start line:83% size:77.5%
get out where some lights are,
away from some of the lights,

14:11.100 --> 14:13.733 align:left position:12.5%,start line:83% size:77.5%
you can see it's the Milky Way,
that's our galaxy.

14:13.833 --> 14:15.333 align:left position:25%,start line:83% size:65%
This is not a picture
of the Milky Way.

14:15.433 --> 14:17.000 align:left position:20%,start line:83% size:70%
Some people may recognize
this as a picture

14:17.100 --> 14:20.800 align:left position:15%,start line:83% size:75%
of the Sombrero Galaxy taken
with the Hubble Space Telescope.

14:20.900 --> 14:23.600 align:left position:27.5%,start line:83% size:62.5%
It's meant there as
kind of a generic

14:23.700 --> 14:26.400 align:left position:20%,start line:77% size:70%
but very pretty depiction
of the galaxy, you see
some of the parts of it.

14:26.500 --> 14:30.200 align:left position:17.5%,start line:83% size:72.5%
You see the fuzz there, the
lighted fuzz, those are stars.

14:30.300 --> 14:32.133 align:left position:27.5%,start line:83% size:62.5%
This is an enormous
number of stars

14:32.233 --> 14:34.000 align:left position:30%,start line:83% size:60%
whose light's all
blended together.

14:35.000 --> 14:37.400 align:left position:10%,start line:89% size:80%
The dark plane is a disk of gas.

14:37.500 --> 14:39.400 align:left position:32.5%,start line:83% size:57.5%
We have a plane
in our Milky Way.

14:39.500 --> 14:41.966 align:left position:25%,start line:83% size:65%
Our Milky Way doesn't
look like this quite.

14:42.066 --> 14:43.566 align:left position:30%,start line:83% size:60%
It is a different
type of galaxy,

14:43.666 --> 14:45.466 align:left position:30%,start line:83% size:60%
but it does have
that disk in it,

14:45.566 --> 14:47.000 align:left position:17.5%,start line:89% size:72.5%
does have that dust in it.

14:47.100 --> 14:49.700 align:left position:15%,start line:83% size:75%
And then right at the center
of almost every galaxy

14:49.800 --> 14:52.833 align:left position:22.5%,start line:83% size:67.5%
we know about, there is
one of these monsters.

14:52.933 --> 14:55.533 align:left position:25%,start line:83% size:65%
There is one of these
supermassive black holes.

14:55.633 --> 14:58.466 align:left position:22.5%,start line:89% size:67.5%
So we live in a galaxy.

14:58.566 --> 15:01.333 align:left position:15%,start line:83% size:75%
There's a supermassive black
hole living in the galaxy,

15:01.433 --> 15:03.233 align:left position:30%,start line:89% size:60%
almost every one.

15:03.333 --> 15:05.733 align:left position:15%,start line:89% size:75%
What does that mean about us?

15:05.833 --> 15:07.100 align:left position:32.5%,start line:89% size:57.5%
I can tell you.

15:07.200 --> 15:09.433 align:left position:30%,start line:83% size:60%
There's somebody
in here tonight,

15:10.900 --> 15:14.933 align:left position:15%,start line:5% size:75%
sitting right now, and there
is a supermassive black hole

15:15.033 --> 15:17.700 align:left position:32.5%,start line:5% size:57.5%
behind you and
underneath your chair.

15:19.433 --> 15:21.333 align:left position:22.5%,start line:5% size:67.5%
One of you, one of us.

15:22.333 --> 15:24.833 align:left position:20%,start line:5% size:70%
Anybody getting nervous?
[laughing]

15:24.933 --> 15:28.733 align:left position:20%,start line:5% size:70%
You don't have to worry.
That one person is me.

15:28.833 --> 15:31.166 align:left position:22.5%,start line:5% size:67.5%
The supermassive black
hole in our galaxy

15:31.266 --> 15:34.433 align:left position:30%,start line:5% size:60%
is roughly there.

15:34.533 --> 15:36.800 align:left position:22.5%,start line:5% size:67.5%
It's in that direction,
still below the horizon.

15:36.900 --> 15:38.933 align:left position:22.5%,start line:5% size:67.5%
It's not that long ago.

15:39.033 --> 15:41.133 align:left position:22.5%,start line:5% size:67.5%
It's okay. I don't have
to worry about it.

15:41.233 --> 15:42.833 align:left position:22.5%,start line:5% size:67.5%
It's a long ways away.

15:42.933 --> 15:46.566 align:left position:20%,start line:5% size:70%
It takes 25,000 years for
anything to happen to get to us.

15:46.666 --> 15:50.300 align:left position:17.5%,start line:5% size:72.5%
And black holes don't have
some mysterious sucking power.

15:50.400 --> 15:52.100 align:left position:22.5%,start line:5% size:67.5%
They're not gonna suck
an entire galaxy in,

15:52.200 --> 15:53.933 align:left position:22.5%,start line:5% size:67.5%
and things have to get
relatively close to them.

15:54.033 --> 15:55.400 align:left position:30%,start line:5% size:60%
So we're gonna be
okay with that.

15:55.500 --> 15:58.733 align:left position:30%,start line:5% size:60%
But if you do get
material close to them,

15:58.833 --> 16:02.500 align:left position:22.5%,start line:5% size:67.5%
and that material falls
into this accretion disk,

16:02.600 --> 16:05.833 align:left position:17.5%,start line:5% size:72.5%
hapless stars, unfortunate
planets that may be around them,

16:05.933 --> 16:08.366 align:left position:27.5%,start line:5% size:62.5%
gas, dust, whatever
happens to get in there,

16:08.466 --> 16:12.866 align:left position:17.5%,start line:5% size:72.5%
loses an enormous amount of
energy. It's falling energy.

16:12.966 --> 16:14.966 align:left position:17.5%,start line:5% size:72.5%
It's just like if something
fell down, it breaks.

16:15.066 --> 16:18.133 align:left position:20%,start line:5% size:70%
Imagine something falling
with so much more energy

16:18.233 --> 16:19.766 align:left position:25%,start line:5% size:65%
than we can conceive
of on Earth,

16:19.866 --> 16:22.166 align:left position:25%,start line:5% size:65%
and it releases some
of that before it falls

16:22.266 --> 16:25.533 align:left position:32.5%,start line:5% size:57.5%
into the black
hole, that can power

16:25.633 --> 16:27.866 align:left position:17.5%,start line:5% size:72.5%
a rather remarkable thing.

16:27.966 --> 16:29.933 align:left position:25%,start line:5% size:65%
It's called an active
galactic nucleus.

16:30.033 --> 16:32.500 align:left position:12.5%,start line:5% size:77.5%
It's the visible manifestation,
and when I say visible

16:32.600 --> 16:34.133 align:left position:10%,start line:5% size:80%
I don't just mean visible light,

16:34.233 --> 16:36.866 align:left position:17.5%,start line:5% size:72.5%
I mean all different kinds
of electromagnetic radiation

16:36.966 --> 16:39.533 align:left position:25%,start line:5% size:65%
as we'll talk about,
it's the manifestation

16:39.633 --> 16:42.300 align:left position:15%,start line:5% size:75%
of one of these supermassive
black holes consuming

16:42.400 --> 16:46.433 align:left position:20%,start line:5% size:70%
material and then jetting
out some of that material

16:46.533 --> 16:47.933 align:left position:27.5%,start line:5% size:62.5%
and a lot of light.

16:48.033 --> 16:50.233 align:left position:22.5%,start line:5% size:67.5%
And those jets come out
at very close to the speed

16:50.333 --> 16:53.266 align:left position:12.5%,start line:5% size:77.5%
of light and they can be huge.

16:53.366 --> 16:56.000 align:left position:22.5%,start line:5% size:67.5%
So getting over to the
panel on the right.

16:56.100 --> 16:58.466 align:left position:25%,start line:83% size:65%
Now we're putting the
two of them together.

16:58.566 --> 17:01.133 align:left position:25%,start line:83% size:65%
This is an image of a
cluster of galaxies.

17:01.233 --> 17:04.033 align:left position:20%,start line:83% size:70%
Each little fuzz ball in
there is its own galaxy.

17:04.133 --> 17:05.733 align:left position:27.5%,start line:83% size:62.5%
It's like the Milky
Way in which we live.

17:05.833 --> 17:08.100 align:left position:30%,start line:83% size:60%
Some are bigger,
some are smaller.

17:08.200 --> 17:11.166 align:left position:30%,start line:83% size:60%
Those red plumes,
that's a false color.

17:11.266 --> 17:12.533 align:left position:20%,start line:89% size:70%
They're not actually red.

17:12.633 --> 17:16.300 align:left position:25%,start line:83% size:65%
They're representing
radio jets and lobes.

17:16.400 --> 17:19.333 align:left position:17.5%,start line:83% size:72.5%
A lot of times the largest
physical manifestations

17:19.433 --> 17:21.766 align:left position:10%,start line:89% size:80%
of these active galactic nuclei,

17:21.866 --> 17:24.633 align:left position:20%,start line:83% size:70%
these supermassive black
holes gobbling up material,

17:24.733 --> 17:27.533 align:left position:20%,start line:83% size:70%
sending up these enormous
jets at close to the speed

17:27.633 --> 17:29.500 align:left position:17.5%,start line:89% size:72.5%
of light are in the radio.

17:29.600 --> 17:31.700 align:left position:25%,start line:83% size:65%
I mentioned the radio
telescope earlier,

17:31.800 --> 17:33.433 align:left position:25%,start line:83% size:65%
so that's where we're
going with this.

17:33.533 --> 17:36.700 align:left position:20%,start line:83% size:70%
And you can see how much
bigger sometimes these are.

17:36.800 --> 17:40.300 align:left position:30%,start line:83% size:60%
They can be much
larger than the galaxy.

17:40.400 --> 17:42.733 align:left position:20%,start line:83% size:70%
They can be a substantial
fraction of the size

17:42.833 --> 17:45.900 align:left position:20%,start line:83% size:70%
of a cluster of galaxies,
like is in this case.

17:56.966 --> 17:59.333 align:left position:27.5%,start line:83% size:62.5%
So now, what might
be the connection?

17:59.433 --> 18:01.400 align:left position:30%,start line:83% size:60%
That's where our
story's leading.

18:01.500 --> 18:06.166 align:left position:17.5%,start line:83% size:72.5%
It's the connection between
black holes and galaxies.

18:06.266 --> 18:09.333 align:left position:20%,start line:83% size:70%
Again, it's a time travel
story because we're looking

18:09.433 --> 18:11.700 align:left position:17.5%,start line:83% size:72.5%
at things that are distant,
and hence back in time.

18:11.800 --> 18:14.166 align:left position:25%,start line:83% size:65%
It's an archeological
story because we're looking

18:14.266 --> 18:17.500 align:left position:22.5%,start line:83% size:67.5%
at relics back in time
to try to understand

18:17.600 --> 18:20.100 align:left position:20%,start line:83% size:70%
what has happened earlier
and earlier in time.

18:20.200 --> 18:23.633 align:left position:25%,start line:77% size:65%
And what we're trying
to understand is
how the black holes

18:23.733 --> 18:26.433 align:left position:25%,start line:83% size:65%
and the stars in the
galaxies might be connected

18:26.533 --> 18:28.433 align:left position:30%,start line:89% size:60%
with each other.

18:28.533 --> 18:31.366 align:left position:30%,start line:83% size:60%
This is why we're
thinking about this,

18:31.466 --> 18:34.233 align:left position:20%,start line:83% size:70%
because there is growing
evidence that there is

18:34.333 --> 18:36.366 align:left position:12.5%,start line:89% size:77.5%
a very fundamental connection.

18:37.466 --> 18:40.000 align:left position:32.5%,start line:83% size:57.5%
The work on the
left is not ours.

18:40.100 --> 18:42.566 align:left position:22.5%,start line:83% size:67.5%
It's a published paper.
The citation right there.

18:42.666 --> 18:44.500 align:left position:27.5%,start line:83% size:62.5%
But it's showing a
cluster of galaxies.

18:44.600 --> 18:48.566 align:left position:17.5%,start line:83% size:72.5%
Again, the light fuzz balls
are individual galaxies.

18:48.666 --> 18:51.466 align:left position:17.5%,start line:89% size:72.5%
The blue is an X-ray image.

18:51.566 --> 18:54.233 align:left position:17.5%,start line:83% size:72.5%
We don't see X-rays, but we
have to represent it somehow,

18:54.333 --> 18:57.000 align:left position:15%,start line:83% size:75%
so it's a false color image.
The X-rays are blue.

18:57.100 --> 18:58.366 align:left position:17.5%,start line:89% size:72.5%
Again, the radio's in red.

18:58.466 --> 19:00.133 align:left position:35%,start line:83% size:55%
You see those
large radio plumes.

19:00.233 --> 19:04.633 align:left position:25%,start line:83% size:65%
If you look closely,
the radio plumes

19:04.733 --> 19:07.700 align:left position:17.5%,start line:83% size:72.5%
appear to be in areas where
there's not many X-rays.

19:07.800 --> 19:11.033 align:left position:17.5%,start line:83% size:72.5%
The X-rays are tracing the
hot gas around these galaxies

19:11.133 --> 19:12.400 align:left position:25%,start line:89% size:65%
around this cluster.

19:12.500 --> 19:15.466 align:left position:30%,start line:83% size:60%
The radio plumes
driven by this AGN

19:15.566 --> 19:19.866 align:left position:17.5%,start line:83% size:72.5%
or active galactic nucleus
have driven out this material.

19:19.966 --> 19:21.933 align:left position:12.5%,start line:89% size:77.5%
There's a term called feedback.

19:22.033 --> 19:24.500 align:left position:22.5%,start line:83% size:67.5%
This is something that
people have been getting more

19:24.600 --> 19:27.300 align:left position:17.5%,start line:83% size:72.5%
and more interested in, not
only because of observational

19:27.400 --> 19:29.600 align:left position:27.5%,start line:83% size:62.5%
evidence like this,
but theoretical evidence.

19:29.700 --> 19:31.466 align:left position:27.5%,start line:5% size:62.5%
Folks who have been
getting better and better

19:31.566 --> 19:33.433 align:left position:12.5%,start line:5% size:77.5%
at modeling how galaxies form,

19:33.533 --> 19:36.933 align:left position:12.5%,start line:5% size:77.5%
they basically create an entire
universe inside a computer.

19:37.033 --> 19:40.933 align:left position:10%,start line:5% size:80%
They create gas, primordial gas,

19:41.033 --> 19:43.333 align:left position:30%,start line:5% size:60%
add dark matter,
this mysterious stuff.

19:43.433 --> 19:45.300 align:left position:10%,start line:5% size:80%
We really don't know what it is.

19:45.400 --> 19:46.933 align:left position:22.5%,start line:5% size:67.5%
And watch what happens.

19:47.033 --> 19:50.366 align:left position:12.5%,start line:5% size:77.5%
And gravity will cause the gas
and dark matter to collapse,

19:50.466 --> 19:53.100 align:left position:20%,start line:5% size:70%
which will form galaxies,
stars, et cetera.

19:53.200 --> 19:56.233 align:left position:25%,start line:5% size:65%
They've gotten better
and better and better at
this across my career.

19:56.333 --> 19:59.400 align:left position:10%,start line:5% size:80%
It's actually been remarkable at
how much progress they've made.

19:59.500 --> 20:02.100 align:left position:20%,start line:5% size:70%
But there was a problem.

20:02.200 --> 20:05.600 align:left position:20%,start line:5% size:70%
Stars formed too quickly,
more than people see.

20:05.700 --> 20:09.600 align:left position:15%,start line:5% size:75%
Too many stars faster than we
actually see in real galaxies.

20:09.700 --> 20:11.366 align:left position:22.5%,start line:5% size:67.5%
What to do about this?

20:11.466 --> 20:13.933 align:left position:17.5%,start line:5% size:72.5%
There had to be some way of
suppressing that star formation,

20:14.033 --> 20:16.633 align:left position:25%,start line:5% size:65%
some kind of feedback
mechanism that as gas flowed

20:16.733 --> 20:19.866 align:left position:22.5%,start line:5% size:67.5%
into the galaxies would
then puff it back up again.

20:19.966 --> 20:22.366 align:left position:22.5%,start line:5% size:67.5%
Two main candidates for
that, the stars themselves.

20:22.466 --> 20:25.566 align:left position:20%,start line:5% size:70%
Some stars explode, huge
explosion, super nova,

20:25.666 --> 20:27.833 align:left position:30%,start line:5% size:60%
they blow the gas
back out or heat it.

20:27.933 --> 20:30.533 align:left position:22.5%,start line:5% size:67.5%
The other one's these,
the active nucleus.

20:30.633 --> 20:34.300 align:left position:22.5%,start line:5% size:67.5%
The material flows in,
it can light up the black hole,

20:34.400 --> 20:37.866 align:left position:17.5%,start line:5% size:72.5%
turn on the active galactic
nucleus, puff out the material,

20:37.966 --> 20:41.733 align:left position:17.5%,start line:5% size:72.5%
shut itself off, and maybe
shut off the star formation

20:41.833 --> 20:43.266 align:left position:32.5%,start line:5% size:57.5%
in the galaxy.

20:43.366 --> 20:46.066 align:left position:17.5%,start line:5% size:72.5%
This is where we're going.
It's that connection.

20:46.166 --> 20:48.133 align:left position:17.5%,start line:5% size:72.5%
People have been working on
this to try to understand

20:48.233 --> 20:49.633 align:left position:22.5%,start line:5% size:67.5%
this better and better.

20:49.733 --> 20:51.533 align:left position:10%,start line:5% size:80%
It's probably a fundamental link

20:51.633 --> 20:54.066 align:left position:20%,start line:5% size:70%
between the supermassive
black holes at the center

20:54.166 --> 20:57.866 align:left position:20%,start line:5% size:70%
of galaxies and the stars
in the galaxies around them.

20:57.966 --> 21:00.700 align:left position:25%,start line:5% size:65%
The specific question
we're trying to address

21:00.800 --> 21:03.200 align:left position:32.5%,start line:5% size:57.5%
is time scale.

21:04.300 --> 21:08.866 align:left position:15%,start line:5% size:75%
Is there any connection with
when a supermassive black hole

21:08.966 --> 21:10.933 align:left position:32.5%,start line:5% size:57.5%
became active,
like is shown here,

21:12.800 --> 21:14.833 align:left position:12.5%,start line:5% size:77.5%
and any star formation events,

21:14.933 --> 21:17.500 align:left position:15%,start line:5% size:75%
the history of the formation
of stars in the galaxy.

21:17.600 --> 21:18.866 align:left position:10%,start line:5% size:80%
Is there any connection between.

21:18.966 --> 21:20.900 align:left position:27.5%,start line:5% size:62.5%
This would indicate
there would be.

21:21.000 --> 21:23.266 align:left position:25%,start line:5% size:65%
The theoretical work
indicate there would be.

21:23.366 --> 21:25.400 align:left position:22.5%,start line:5% size:67.5%
But what's the timing?

21:25.500 --> 21:28.466 align:left position:15%,start line:5% size:75%
Does the AGN turn the active
galactic nucleus on first,

21:28.566 --> 21:29.866 align:left position:22.5%,start line:5% size:67.5%
same time, afterwards?

21:29.966 --> 21:31.500 align:left position:25%,start line:5% size:65%
How are they relative
to each other?

21:31.600 --> 21:33.200 align:left position:15%,start line:5% size:75%
Is there always a connection,

21:33.300 --> 21:35.266 align:left position:25%,start line:5% size:65%
or is there really no
connection in timing?

21:35.366 --> 21:37.133 align:left position:27.5%,start line:5% size:62.5%
Is it maybe just a
little bit that happens

21:37.233 --> 21:38.466 align:left position:20%,start line:5% size:70%
below what we can detect?

21:38.566 --> 21:39.900 align:left position:30%,start line:5% size:60%
So these are the
type of questions

21:40.000 --> 21:41.433 align:left position:15%,start line:5% size:75%
that we're trying to answer.

21:41.533 --> 21:45.466 align:left position:25%,start line:5% size:65%
So if we're trying to
see a connection in time

21:45.566 --> 21:47.866 align:left position:30%,start line:5% size:60%
between what the
black hole is doing

21:47.966 --> 21:50.766 align:left position:25%,start line:5% size:65%
and what the stars in
the galaxy are doing,

21:50.866 --> 21:53.666 align:left position:25%,start line:5% size:65%
we can't just look at

21:53.766 --> 21:56.366 align:left position:25%,start line:5% size:65%
a galaxy and a black
hole at the same time.

21:56.466 --> 21:58.000 align:left position:32.5%,start line:5% size:57.5%
Well, you can.
People have done that.

21:58.100 --> 22:00.100 align:left position:27.5%,start line:5% size:62.5%
That's done a lot.
But you're limited.

22:00.200 --> 22:02.033 align:left position:20%,start line:5% size:70%
You're looking at a snap
shot in time, one time.

22:02.133 --> 22:05.833 align:left position:20%,start line:5% size:70%
Remember, you're looking
at Pompeii that morning.

22:05.933 --> 22:08.166 align:left position:30%,start line:5% size:60%
You're not seeing
what had happened

22:08.266 --> 22:11.400 align:left position:15%,start line:5% size:75%
500 years earlier in Pompeii.

22:11.500 --> 22:15.133 align:left position:25%,start line:5% size:65%
For that, you need to
go back to that morning

22:15.233 --> 22:18.433 align:left position:25%,start line:5% size:65%
in the early 80's and
go dig up something.

22:19.533 --> 22:21.066 align:left position:32.5%,start line:5% size:57.5%
That's the time
traveling archeology,

22:21.166 --> 22:22.633 align:left position:25%,start line:5% size:65%
and that's what we're
trying to do here,

22:22.733 --> 22:25.900 align:left position:17.5%,start line:5% size:72.5%
is go dig up things and see
if we can make a connection

22:26.000 --> 22:27.400 align:left position:27.5%,start line:5% size:62.5%
in that time scale.

22:27.500 --> 22:29.733 align:left position:20%,start line:5% size:70%
And the plot on the left
here is just a schematic.

22:29.833 --> 22:31.433 align:left position:22.5%,start line:5% size:67.5%
The thing in the middle
that looks like a sun

22:31.533 --> 22:33.566 align:left position:12.5%,start line:5% size:77.5%
is actually meant to represent
an active galactic nucleus.

22:33.666 --> 22:35.533 align:left position:25%,start line:83% size:65%
That's a supermassive
black hole.

22:35.633 --> 22:38.333 align:left position:37.5%,start line:89% size:52.5%
Over here,

22:38.433 --> 22:41.733 align:left position:25%,start line:83% size:65%
on the right part of
that, is the outflow.

22:41.833 --> 22:43.666 align:left position:32.5%,start line:83% size:57.5%
And it may even
trigger star formation.

22:43.766 --> 22:46.200 align:left position:17.5%,start line:83% size:72.5%
So the idea, the main idea
people are thinking about now

22:46.300 --> 22:49.033 align:left position:25%,start line:83% size:65%
is that these active
galactic nuclei may shut off

22:49.133 --> 22:50.866 align:left position:20%,start line:83% size:70%
star formation, but they
may also trigger it.

22:50.966 --> 22:52.466 align:left position:25%,start line:83% size:65%
That's an idea that's
been around a long time.

22:52.566 --> 22:54.666 align:left position:20%,start line:83% size:70%
I remember hearing about
that in graduate school.

22:54.766 --> 22:56.600 align:left position:30%,start line:83% size:60%
So there may be a
lot going on here.

22:59.266 --> 23:02.166 align:left position:20%,start line:83% size:70%
And this is the question
I was addressing just here.

23:02.266 --> 23:03.933 align:left position:15%,start line:89% size:75%
What is the time scale here?

23:04.033 --> 23:07.233 align:left position:32.5%,start line:83% size:57.5%
So to do this,
we need a couple things.

23:07.333 --> 23:09.266 align:left position:15%,start line:89% size:75%
This is the archeology again.

23:09.366 --> 23:13.133 align:left position:15%,start line:83% size:75%
We need to be able to trace a
black hole's activity history.

23:13.233 --> 23:15.800 align:left position:30%,start line:83% size:60%
What has it been
up to in the past?

23:15.900 --> 23:18.366 align:left position:17.5%,start line:83% size:72.5%
Was it active in the past,
or was it just sitting there?

23:18.466 --> 23:21.400 align:left position:27.5%,start line:77% size:62.5%
Remember, it's only
active if you have
material flowing into it.

23:21.500 --> 23:23.966 align:left position:22.5%,start line:83% size:67.5%
That accretion disk, if
it runs out of material,

23:24.066 --> 23:25.600 align:left position:27.5%,start line:89% size:62.5%
it just sits there.

23:25.700 --> 23:27.366 align:left position:20%,start line:89% size:70%
Also, we need to be able

23:27.466 --> 23:29.333 align:left position:25%,start line:83% size:65%
to trace the galaxy's
star formation history.

23:29.433 --> 23:32.166 align:left position:17.5%,start line:83% size:72.5%
What were the stars doing?
Do we see a connection?

23:32.266 --> 23:34.733 align:left position:22.5%,start line:83% size:67.5%
Was there an episode of
activity in the black hole

23:34.833 --> 23:38.366 align:left position:17.5%,start line:83% size:72.5%
in the past that then shut
off the star formation,

23:38.466 --> 23:41.133 align:left position:27.5%,start line:83% size:62.5%
that then triggered
the star formation?

23:41.233 --> 23:42.766 align:left position:35%,start line:83% size:55%
Did the star
formation happen first

23:42.866 --> 23:45.000 align:left position:25%,start line:83% size:65%
and then trigger the
black hole or shut it off?

23:45.100 --> 23:47.000 align:left position:27.5%,start line:83% size:62.5%
How do these things
connect with each other?

23:47.100 --> 23:49.000 align:left position:30%,start line:83% size:60%
That's what we're
trying to get at here.

23:49.100 --> 23:52.266 align:left position:22.5%,start line:83% size:67.5%
And we can do that with
a black hole, at least,

23:52.366 --> 23:53.900 align:left position:27.5%,start line:83% size:62.5%
the active galactic
nucleus, we can do that

23:54.000 --> 23:56.800 align:left position:27.5%,start line:83% size:62.5%
if we look at them
with radio light.

23:56.900 --> 24:00.766 align:left position:17.5%,start line:83% size:72.5%
Remember, I said those huge
plumes were radio emission,

24:00.866 --> 24:03.600 align:left position:12.5%,start line:89% size:77.5%
particularly at low frequency.

24:03.700 --> 24:07.333 align:left position:22.5%,start line:5% size:67.5%
And we need to be able
to trace the galaxy's

24:07.433 --> 24:10.000 align:left position:22.5%,start line:5% size:67.5%
star formation history,
and we can do that

24:10.100 --> 24:12.800 align:left position:10%,start line:5% size:80%
with visible light observations.

24:12.900 --> 24:15.033 align:left position:30%,start line:5% size:60%
That's the story
of this evening,

24:15.133 --> 24:16.533 align:left position:15%,start line:5% size:75%
the rest of the evening here.

24:16.633 --> 24:21.100 align:left position:25%,start line:5% size:65%
So getting to how we
figure out what the stars

24:21.200 --> 24:25.633 align:left position:25%,start line:5% size:65%
have been up to, this
is a very brief rundown

24:25.733 --> 24:27.633 align:left position:12.5%,start line:5% size:77.5%
of a rather complicated topic.

24:27.733 --> 24:29.733 align:left position:15%,start line:5% size:75%
But the principles are okay.

24:29.833 --> 24:32.033 align:left position:25%,start line:89% size:65%
Over here on the left

24:32.133 --> 24:35.100 align:left position:25%,start line:83% size:65%
is something called a
Hertzsprung-Russell diagram

24:35.200 --> 24:37.066 align:left position:15%,start line:89% size:75%
or a color magnitude diagram.

24:37.166 --> 24:39.366 align:left position:15%,start line:83% size:75%
We don't need to worry about
the terminology too much.

24:39.466 --> 24:41.766 align:left position:35%,start line:83% size:55%
It's a plot.
This is color.

24:41.866 --> 24:43.866 align:left position:12.5%,start line:89% size:77.5%
They've nicely color-coded it.

24:43.966 --> 24:47.566 align:left position:30%,start line:83% size:60%
This end is red.
That end is blue.

24:47.666 --> 24:51.433 align:left position:17.5%,start line:83% size:72.5%
So it's color, blue to red,
and up here is brightness.

24:51.533 --> 24:53.433 align:left position:30%,start line:83% size:60%
This is fainter,
that's brighter,

24:53.533 --> 24:55.233 align:left position:17.5%,start line:89% size:72.5%
and these represent stars.

24:55.333 --> 24:59.566 align:left position:22.5%,start line:83% size:67.5%
This is the culmination
of decades of work,

24:59.666 --> 25:02.300 align:left position:20%,start line:83% size:70%
particularly in the first
half of the 20th century,

25:02.400 --> 25:04.900 align:left position:25%,start line:83% size:65%
to understand, to not
only measure these things

25:05.000 --> 25:09.033 align:left position:27.5%,start line:83% size:62.5%
but understand how
this changes with time.

25:09.133 --> 25:12.733 align:left position:20%,start line:83% size:70%
And what happens is that
when a bunch of new stars

25:12.833 --> 25:16.966 align:left position:25%,start line:83% size:65%
are first born, they
lie all along here.

25:17.066 --> 25:19.100 align:left position:32.5%,start line:83% size:57.5%
This is called
the main sequence.

25:19.200 --> 25:21.833 align:left position:17.5%,start line:83% size:72.5%
And the more massive ones,
the ones that turn out

25:21.933 --> 25:24.900 align:left position:17.5%,start line:83% size:72.5%
the more massive ones, are
brighter and they're bluer.

25:25.000 --> 25:27.433 align:left position:12.5%,start line:83% size:77.5%
They gobble up their fuel, even
though they have more of it,

25:27.533 --> 25:28.866 align:left position:27.5%,start line:89% size:62.5%
they are real hogs.

25:28.966 --> 25:33.000 align:left position:27.5%,start line:83% size:62.5%
They gobble up very
quickly, and they expire.

25:33.100 --> 25:34.733 align:left position:32.5%,start line:89% size:57.5%
The star dies.

25:34.833 --> 25:36.400 align:left position:30%,start line:89% size:60%
And so from here,

25:36.500 --> 25:38.300 align:left position:22.5%,start line:83% size:67.5%
they would move off to
this other part here.

25:38.400 --> 25:40.600 align:left position:27.5%,start line:83% size:62.5%
This is not a talk
about stellar evolution,

25:40.700 --> 25:42.600 align:left position:22.5%,start line:83% size:67.5%
just suffice it to say
that they go over here

25:42.700 --> 25:44.500 align:left position:27.5%,start line:83% size:62.5%
and then they loop
around over here

25:44.600 --> 25:46.100 align:left position:12.5%,start line:89% size:77.5%
and they eventually peter out.

25:46.200 --> 25:48.966 align:left position:17.5%,start line:83% size:72.5%
The point is that the older
the group of stars are,

25:49.066 --> 25:51.800 align:left position:30%,start line:89% size:60%
the more, whoops.

25:51.900 --> 25:54.066 align:left position:27.5%,start line:83% size:62.5%
Back that up a bit,
hit the wrong button.

25:54.166 --> 25:57.733 align:left position:17.5%,start line:83% size:72.5%
The more they moved off of
here to get down to this,

25:57.833 --> 26:02.233 align:left position:17.5%,start line:83% size:72.5%
so you can tell the age of
a group of stars this way.

26:02.333 --> 26:07.933 align:left position:17.5%,start line:83% size:72.5%
And this allows you to then
connect age of lots of stars

26:08.033 --> 26:11.133 align:left position:25%,start line:83% size:65%
and how the galaxy in
which they live appears.

26:11.233 --> 26:12.866 align:left position:20%,start line:89% size:70%
And this is it over here.

26:12.966 --> 26:17.100 align:left position:12.5%,start line:83% size:77.5%
So if we have very young stars,
a very young group of stars,

26:17.200 --> 26:19.466 align:left position:30%,start line:83% size:60%
that's these blue
ones over here.

26:19.566 --> 26:21.933 align:left position:27.5%,start line:83% size:62.5%
Remember, the young
ones live up in here.

26:22.033 --> 26:25.600 align:left position:17.5%,start line:83% size:72.5%
Very bright, very blue, so
they dominate the light,

26:25.700 --> 26:28.966 align:left position:17.5%,start line:83% size:72.5%
they can dominate the light
of the whole group of stars

26:29.066 --> 26:30.466 align:left position:25%,start line:89% size:65%
and even the galaxy.

26:30.566 --> 26:33.200 align:left position:20%,start line:83% size:70%
So this is what's called
a stellar population.

26:33.300 --> 26:35.766 align:left position:22.5%,start line:83% size:67.5%
Each of these graphs is
a stellar population.

26:35.866 --> 26:40.566 align:left position:15%,start line:83% size:75%
What it means here is this is
brightness, again, vertical.

26:40.666 --> 26:43.400 align:left position:27.5%,start line:83% size:62.5%
And this is color,
specifically wavelength.

26:43.500 --> 26:46.466 align:left position:20%,start line:83% size:70%
So this is blue, what our
eyes would see as blue,

26:46.566 --> 26:48.400 align:left position:27.5%,start line:89% size:62.5%
red, near infrared.

26:48.500 --> 26:50.466 align:left position:32.5%,start line:83% size:57.5%
And even though
these are each coded

26:50.566 --> 26:52.266 align:left position:30%,start line:83% size:60%
by the same color
all the way through,

26:52.366 --> 26:53.700 align:left position:22.5%,start line:83% size:67.5%
it doesn't mean they're
all the same color.

26:53.800 --> 26:55.500 align:left position:27.5%,start line:83% size:62.5%
It's just that this
one is colored blue

26:55.600 --> 26:57.466 align:left position:30%,start line:83% size:60%
because it's more
dominantly blue.

26:57.566 --> 26:59.066 align:left position:27.5%,start line:83% size:62.5%
It's got more light
up in the blue

26:59.166 --> 27:00.900 align:left position:30%,start line:83% size:60%
than it does over
here in the red.

27:01.000 --> 27:02.366 align:left position:15%,start line:89% size:75%
And this is an age sequence.

27:02.466 --> 27:04.066 align:left position:42.5%,start line:89% size:47.5%
Young,

27:04.166 --> 27:06.400 align:left position:45%,start line:83% size:45%
old,
really old.

27:06.500 --> 27:08.600 align:left position:20%,start line:89% size:70%
You can see what happens.

27:08.700 --> 27:12.266 align:left position:27.5%,start line:83% size:62.5%
This plot of light,
this is like a rainbow.

27:12.366 --> 27:14.666 align:left position:30%,start line:89% size:60%
It's a spectrum.

27:14.766 --> 27:18.800 align:left position:20%,start line:83% size:70%
By the way, these tags up
here, this is showing us

27:18.900 --> 27:21.633 align:left position:25%,start line:83% size:65%
what kind of the key
ideas here in each figure

27:21.733 --> 27:23.400 align:left position:20%,start line:83% size:70%
and this is where we are
in the plot, roughly,

27:23.500 --> 27:24.933 align:left position:25%,start line:83% size:65%
just kind of a guide,
because this can be

27:25.033 --> 27:26.366 align:left position:20%,start line:89% size:70%
a little bit complicated.

27:26.466 --> 27:28.233 align:left position:25%,start line:83% size:65%
So if you're ever not
sure, or you wake up

27:28.333 --> 27:29.866 align:left position:27.5%,start line:83% size:62.5%
and you say, "Where
is that guy?"

27:29.966 --> 27:32.333 align:left position:25%,start line:83% size:65%
That's where we are.
Just look at the top there.

27:32.433 --> 27:37.200 align:left position:20%,start line:83% size:70%
So this is the appearance
of a collection of stars

27:37.300 --> 27:38.966 align:left position:30%,start line:89% size:60%
of a single age.

27:39.066 --> 27:42.233 align:left position:22.5%,start line:83% size:67.5%
And a galaxy is made up
of collections of stars

27:42.333 --> 27:43.633 align:left position:27.5%,start line:89% size:62.5%
of different ages.

27:43.733 --> 27:46.166 align:left position:25%,start line:83% size:65%
And so we can combine
these together.

27:47.366 --> 27:50.666 align:left position:17.5%,start line:83% size:72.5%
Principle is we can combine
these together and form

27:50.766 --> 27:53.566 align:left position:17.5%,start line:83% size:72.5%
the rainbow or the spectrum
of an entire galaxy

27:53.666 --> 27:55.566 align:left position:12.5%,start line:89% size:77.5%
made up of components of these.

27:55.666 --> 27:57.566 align:left position:27.5%,start line:83% size:62.5%
If you can combine
them together to see

27:57.666 --> 28:00.366 align:left position:20%,start line:83% size:70%
what a galaxy looks like,
you can also take them apart.

28:00.466 --> 28:03.600 align:left position:17.5%,start line:5% size:72.5%
That's the key, we can take
a spectrum of a galaxy,

28:03.700 --> 28:06.633 align:left position:22.5%,start line:5% size:67.5%
or pieces of a galaxy,
and pull it apart

28:06.733 --> 28:10.466 align:left position:22.5%,start line:5% size:67.5%
into these constituent
pieces and understand,

28:10.566 --> 28:13.066 align:left position:25%,start line:5% size:65%
in principle, how old
each of the pieces were.

28:13.166 --> 28:16.733 align:left position:32.5%,start line:5% size:57.5%
So that is the
stellar archeology.

28:16.833 --> 28:20.166 align:left position:15%,start line:5% size:75%
That's figuring out the past
history of the star formation

28:20.266 --> 28:24.533 align:left position:17.5%,start line:5% size:72.5%
in any galaxy for which we
have sufficiently good data

28:24.633 --> 28:27.433 align:left position:12.5%,start line:5% size:77.5%
and a good enough understanding
of what we're doing,

28:27.533 --> 28:30.066 align:left position:25%,start line:5% size:65%
which is a key that's
still being worked on.

28:30.166 --> 28:33.100 align:left position:17.5%,start line:5% size:72.5%
Most of our project today,

28:33.200 --> 28:34.700 align:left position:30%,start line:5% size:60%
like I said, this
is a field report.

28:34.800 --> 28:37.866 align:left position:17.5%,start line:5% size:72.5%
We're still in the scorpion
biting, bug stinging,

28:37.966 --> 28:40.233 align:left position:15%,start line:5% size:75%
digging around in the jungle
phase of the archeology.

28:40.333 --> 28:42.433 align:left position:27.5%,start line:5% size:62.5%
Most of what we've
done so far has been

28:42.533 --> 28:43.966 align:left position:15%,start line:5% size:75%
on the other part, the radio.

28:44.066 --> 28:46.166 align:left position:30%,start line:5% size:60%
I'll come back to
the stars in a bit.

28:46.266 --> 28:48.666 align:left position:30%,start line:5% size:60%
This is the AGN.

28:48.766 --> 28:51.533 align:left position:27.5%,start line:5% size:62.5%
This thing here is
also a spectrum.

28:51.633 --> 28:53.966 align:left position:27.5%,start line:83% size:62.5%
This is a rainbow,
just like a rainbow,

28:54.066 --> 28:56.000 align:left position:10%,start line:83% size:80%
rainbow when you see it outside,
it's a spectrum.

28:56.100 --> 28:57.766 align:left position:17.5%,start line:83% size:72.5%
It's breaking the light up
into its constituent colors,

28:57.866 --> 28:59.633 align:left position:20%,start line:89% size:70%
but this is a radio one.

28:59.733 --> 29:03.633 align:left position:15%,start line:83% size:75%
What's up here at the top are
frequencies and megahertz.

29:05.000 --> 29:09.333 align:left position:25%,start line:83% size:65%
150 megahertz on the
left, 1,400 on the right.

29:09.433 --> 29:11.666 align:left position:30%,start line:83% size:60%
Now, that may be
coming out of the blue.

29:11.766 --> 29:13.800 align:left position:25%,start line:83% size:65%
Red and blue colors,
we're used to.

29:13.900 --> 29:15.866 align:left position:32.5%,start line:83% size:57.5%
150 megahertz,
well, what's that?

29:15.966 --> 29:17.766 align:left position:32.5%,start line:83% size:57.5%
So I gave a few
guidelines up here.

29:17.866 --> 29:21.033 align:left position:17.5%,start line:83% size:72.5%
I've listed a few things we
might be somewhat familiar with,

29:21.133 --> 29:23.933 align:left position:22.5%,start line:83% size:67.5%
very high frequency TV,
the high band of it,

29:24.033 --> 29:25.700 align:left position:25%,start line:83% size:65%
is roughly where it's
indicated up there.

29:25.800 --> 29:29.466 align:left position:27.5%,start line:83% size:62.5%
The UHF channels of
TV are over there.

29:29.566 --> 29:32.266 align:left position:22.5%,start line:83% size:67.5%
And underneath of it, I
got merged in a little bit

29:32.366 --> 29:35.200 align:left position:30%,start line:83% size:60%
with the labeling
there, cell phones.

29:36.566 --> 29:40.333 align:left position:17.5%,start line:83% size:72.5%
And AM is lower frequency,
so off to the left,

29:40.433 --> 29:43.833 align:left position:15%,start line:83% size:75%
and Sirius XM radio is higher
frequency, so off to the right.

29:43.933 --> 29:46.733 align:left position:17.5%,start line:83% size:72.5%
So that kind of gives us an
idea of where we are here.

29:46.833 --> 29:50.833 align:left position:20%,start line:89% size:70%
And I've plotted spectra

29:50.933 --> 29:53.066 align:left position:25%,start line:89% size:65%
of the radio source.

29:53.166 --> 29:54.666 align:left position:22.5%,start line:89% size:67.5%
It looks a lot simpler.

29:54.766 --> 29:57.133 align:left position:17.5%,start line:83% size:72.5%
So this is similar to, it's
the same type of thing,

29:57.233 --> 29:59.766 align:left position:25%,start line:83% size:65%
a plot of brightness
of light with color

29:59.866 --> 30:03.233 align:left position:17.5%,start line:83% size:72.5%
as we had before, but this
one looks a lot simpler,

30:03.333 --> 30:05.966 align:left position:20%,start line:83% size:70%
thankfully, because that
one's really complicated.

30:06.066 --> 30:08.433 align:left position:27.5%,start line:83% size:62.5%
And again, there's
a sequence of age.

30:08.533 --> 30:11.366 align:left position:25%,start line:83% size:65%
The blue one here is
for a radio source

30:11.466 --> 30:13.033 align:left position:15%,start line:89% size:75%
that's 10,000,000 years old.

30:13.133 --> 30:15.933 align:left position:17.5%,start line:83% size:72.5%
What you see happening here
is that as you go older,

30:16.033 --> 30:17.866 align:left position:25%,start line:83% size:65%
the key is down there
in the lower right,

30:17.966 --> 30:21.566 align:left position:12.5%,start line:83% size:77.5%
as you go older from 10,000,000
years to 50,000,000 years

30:21.666 --> 30:24.933 align:left position:20%,start line:83% size:70%
to 100,000,000 years, by
the way, MYR is mega year,

30:25.033 --> 30:27.800 align:left position:25%,start line:83% size:65%
million years old, to
300,000,000 years old.

30:27.900 --> 30:31.066 align:left position:20%,start line:83% size:70%
Look at the corresponding
colored lines.

30:31.166 --> 30:34.333 align:left position:17.5%,start line:83% size:72.5%
The young ones are shallow
and go straight across.

30:34.433 --> 30:37.366 align:left position:20%,start line:83% size:70%
As they progressively get
older, they get steeper

30:37.466 --> 30:39.033 align:left position:15%,start line:89% size:75%
and there's a turnover there.

30:39.133 --> 30:41.466 align:left position:22.5%,start line:83% size:67.5%
So those are two things
we're gonna see here more of

30:41.566 --> 30:44.300 align:left position:25%,start line:83% size:65%
as we go forward, how
steep that line is.

30:44.400 --> 30:46.766 align:left position:32.5%,start line:83% size:57.5%
Is it shallow?
That indicates pretty young.

30:47.966 --> 30:50.000 align:left position:32.5%,start line:83% size:57.5%
Or is it steep?
That indicates older.

30:50.100 --> 30:54.800 align:left position:12.5%,start line:89% size:77.5%
And also, the location of where

30:54.900 --> 30:57.233 align:left position:25%,start line:83% size:65%
these turnovers have
happened, like this one.

30:57.333 --> 30:59.733 align:left position:37.5%,start line:83% size:52.5%
This one is
300,000,000 years old.

30:59.833 --> 31:02.033 align:left position:22.5%,start line:83% size:67.5%
Notice how quickly it's
turning over like that.

31:02.133 --> 31:04.133 align:left position:27.5%,start line:83% size:62.5%
So we're gonna talk
about that more.

31:04.233 --> 31:06.800 align:left position:25%,start line:83% size:65%
The steepness of the
spectrum, the radio spectrum,

31:06.900 --> 31:10.166 align:left position:22.5%,start line:77% size:67.5%
and the turnover point,
the frequency at which
it turns over.

31:10.266 --> 31:12.333 align:left position:15%,start line:89% size:75%
This, then, is also a clock.

31:12.433 --> 31:14.533 align:left position:12.5%,start line:89% size:77.5%
Like what we had for the stars,

31:14.633 --> 31:16.433 align:left position:27.5%,start line:83% size:62.5%
this is a clock for
the active galaxies.

31:16.533 --> 31:19.500 align:left position:22.5%,start line:83% size:67.5%
So we can get some idea
of how old they are,

31:19.600 --> 31:22.133 align:left position:20%,start line:89% size:70%
and even look for relics,

31:22.233 --> 31:24.433 align:left position:37.5%,start line:83% size:52.5%
again, the
archeological reference.

31:24.533 --> 31:29.433 align:left position:17.5%,start line:83% size:72.5%
We are looking for not only
currently active galaxies,

31:29.533 --> 31:31.600 align:left position:22.5%,start line:83% size:67.5%
but ones that may have
been active in the past.

31:31.700 --> 31:35.333 align:left position:15%,start line:89% size:75%
And this is a way to do that

31:35.433 --> 31:37.833 align:left position:27.5%,start line:83% size:62.5%
because you can see
something that was active

31:37.933 --> 31:41.366 align:left position:30%,start line:83% size:60%
a long time ago,
300,000,000 years ago,

31:41.466 --> 31:45.066 align:left position:15%,start line:83% size:75%
we can still see it, even if
it's no longer active today,

31:45.166 --> 31:48.400 align:left position:27.5%,start line:83% size:62.5%
with the right kind
of observations.

31:48.500 --> 31:52.066 align:left position:17.5%,start line:83% size:72.5%
And that means lower radio
frequencies, 300 megahertz,

31:52.166 --> 31:56.400 align:left position:15%,start line:83% size:75%
150 megahertz, are considered
low frequency in the radio.

31:59.333 --> 32:00.766 align:left position:30%,start line:89% size:60%
So getting there.

32:00.866 --> 32:02.666 align:left position:30%,start line:5% size:60%
At the beginning,
remember, I mentioned there

32:02.766 --> 32:04.566 align:left position:30%,start line:5% size:60%
would be a radio
telescope in here,

32:04.666 --> 32:06.033 align:left position:30%,start line:5% size:60%
but it's not the
one in New Mexico.

32:06.133 --> 32:08.700 align:left position:20%,start line:5% size:70%
The one in New Mexico is
called the Very Large Array.

32:08.800 --> 32:10.800 align:left position:25%,start line:5% size:65%
It's been in a lot of
commercials, movies,

32:10.900 --> 32:12.333 align:left position:12.5%,start line:5% size:77.5%
the movie Contact, for example.

32:12.433 --> 32:14.133 align:left position:27.5%,start line:5% size:62.5%
You can tell I'm a
bit of a movie buff,

32:14.233 --> 32:17.166 align:left position:17.5%,start line:5% size:72.5%
especially when it comes to
astronomical-themed things.

32:17.266 --> 32:19.100 align:left position:17.5%,start line:5% size:72.5%
This is a telescope that's
actually even bigger

32:19.200 --> 32:21.133 align:left position:17.5%,start line:5% size:72.5%
than the one in New Mexico.

32:21.233 --> 32:23.966 align:left position:22.5%,start line:5% size:67.5%
More dishes, the dishes
are larger themselves.

32:24.066 --> 32:26.900 align:left position:25%,start line:83% size:65%
And this picture here
is just a subset of it.

32:27.000 --> 32:29.233 align:left position:27.5%,start line:83% size:62.5%
This is only a tiny
part of the array.

32:29.333 --> 32:32.700 align:left position:22.5%,start line:83% size:67.5%
If you look carefully,
the one in the foreground,

32:32.800 --> 32:36.733 align:left position:20%,start line:83% size:70%
the biggest dish, is next
to a little white blob.

32:36.833 --> 32:39.166 align:left position:30%,start line:83% size:60%
That little white
blob is a Jeep.

32:39.266 --> 32:41.666 align:left position:30%,start line:83% size:60%
These dishes are
45 meters across.

32:41.766 --> 32:44.200 align:left position:20%,start line:89% size:70%
This is near Pune, India.

32:44.300 --> 32:46.466 align:left position:25%,start line:83% size:65%
It's called the Giant
Metrewave Radio Telescope,

32:46.566 --> 32:50.800 align:left position:17.5%,start line:83% size:72.5%
GMRT there stands for Giant
Metrewave Radio Telescope.

32:50.900 --> 32:54.300 align:left position:25%,start line:83% size:65%
Metrewaves, it's the
wavelength of the radio waves.

32:55.766 --> 32:59.833 align:left position:17.5%,start line:5% size:72.5%
These things will go, this
will observe wavelengths,

32:59.933 --> 33:03.233 align:left position:30%,start line:5% size:60%
the shortest one
is about that big.

33:03.333 --> 33:07.300 align:left position:27.5%,start line:5% size:62.5%
The longest one is
taller than Darth Vader.

33:07.400 --> 33:10.766 align:left position:27.5%,start line:5% size:62.5%
That's why they say
metrewave, it's in the meters.

33:10.866 --> 33:13.133 align:left position:27.5%,start line:5% size:62.5%
Longer wavelengths
corresponds to low frequency.

33:13.233 --> 33:14.966 align:left position:15%,start line:5% size:75%
So those are the same thing.

33:15.066 --> 33:16.733 align:left position:15%,start line:5% size:75%
It's a radio interferometer.

33:16.833 --> 33:19.633 align:left position:17.5%,start line:5% size:72.5%
We could have a whole talk
about radio interferometers.

33:19.733 --> 33:21.866 align:left position:30%,start line:5% size:60%
They're wonderful
things that allows you

33:21.966 --> 33:25.700 align:left position:20%,start line:5% size:70%
to use many dishes, many
radio dishes, to work as one.

33:25.800 --> 33:27.933 align:left position:12.5%,start line:5% size:77.5%
Gives you the clarity of image

33:28.033 --> 33:30.800 align:left position:12.5%,start line:5% size:77.5%
that you would have close to it

33:30.900 --> 33:33.133 align:left position:27.5%,start line:5% size:62.5%
if you had a single

33:33.233 --> 33:35.800 align:left position:27.5%,start line:5% size:62.5%
gigantic radio dish

33:35.900 --> 33:40.066 align:left position:27.5%,start line:5% size:62.5%
that was as big as
the entire array.

33:40.166 --> 33:43.133 align:left position:17.5%,start line:5% size:72.5%
So these things are spread
out over 10's of kilometers

33:43.233 --> 33:45.600 align:left position:12.5%,start line:5% size:77.5%
all across this plane in India.

33:45.700 --> 33:48.633 align:left position:17.5%,start line:5% size:72.5%
And they work together and
they can give you an image

33:48.733 --> 33:51.933 align:left position:15%,start line:5% size:75%
that is approaching as crisp

33:52.033 --> 33:55.400 align:left position:25%,start line:5% size:65%
as if you had a giant
bowl that was 10's

33:55.500 --> 33:57.666 align:left position:20%,start line:5% size:70%
of kilometers across all
collecting radio length.

33:57.766 --> 33:59.733 align:left position:12.5%,start line:5% size:77.5%
That's why they're really neat.
That's why people use them.

33:59.833 --> 34:02.500 align:left position:25%,start line:83% size:65%
And over here on the
right is an example

34:02.600 --> 34:05.166 align:left position:27.5%,start line:83% size:62.5%
of observations of
one of our objects.

34:05.266 --> 34:08.266 align:left position:32.5%,start line:83% size:57.5%
This is a radio
galaxy, similar to ones

34:08.366 --> 34:10.333 align:left position:22.5%,start line:83% size:67.5%
that I showed earlier,
not quite as big.

34:10.433 --> 34:12.566 align:left position:25%,start line:77% size:65%
And all the alphabet,
don't worry about the
alphabet soup up there.

34:12.666 --> 34:15.300 align:left position:27.5%,start line:77% size:62.5%
Those are different
surveys, we've drawn
these from our surveys.

34:15.400 --> 34:18.166 align:left position:17.5%,start line:83% size:72.5%
The SS in all these things
stands for sky survey.

34:18.266 --> 34:22.233 align:left position:20%,start line:83% size:70%
So SDSS is a sky survey.
TGSS is a sky survey.

34:22.333 --> 34:23.766 align:left position:22.5%,start line:89% size:67.5%
WINSS is a sky survey.

34:23.866 --> 34:25.900 align:left position:20%,start line:83% size:70%
And then I've indicated a
couple points of new data.

34:26.000 --> 34:27.766 align:left position:30%,start line:83% size:60%
These are some of
the data we've taken

34:27.866 --> 34:29.566 align:left position:15%,start line:89% size:75%
and are currently working on.

34:29.666 --> 34:32.133 align:left position:17.5%,start line:83% size:72.5%
We just finished the second
of three observing runs.

34:32.233 --> 34:33.933 align:left position:25%,start line:83% size:65%
The next one will be
coming up next month,

34:34.033 --> 34:36.366 align:left position:25%,start line:83% size:65%
and then we will have
all the data we need,

34:36.466 --> 34:39.033 align:left position:20%,start line:83% size:70%
hopefully for one of the
graduate student's PhD theses.

34:39.133 --> 34:42.100 align:left position:22.5%,start line:83% size:67.5%
And so we'll have a lot
more of this coming in.

34:43.533 --> 34:45.333 align:left position:37.5%,start line:89% size:52.5%
All right.

34:45.433 --> 34:46.900 align:left position:15%,start line:89% size:75%
Here's just a quick example.

34:47.000 --> 34:48.733 align:left position:17.5%,start line:89% size:72.5%
This is some early results.

34:50.566 --> 34:52.400 align:left position:27.5%,start line:83% size:62.5%
I've plotted three
things up here.

34:52.500 --> 34:54.700 align:left position:25%,start line:83% size:65%
Remember I said that
one of the key things

34:54.800 --> 34:57.566 align:left position:17.5%,start line:83% size:72.5%
is a spectrums shape, this
is an indication of shape.

34:57.666 --> 34:59.466 align:left position:22.5%,start line:83% size:67.5%
Don't worry about what
the color bar means here.

34:59.566 --> 35:02.466 align:left position:22.5%,start line:83% size:67.5%
The key thing is this.
This is the age.

35:02.566 --> 35:06.433 align:left position:27.5%,start line:83% size:62.5%
This is the derived
product from the spectrum.

35:08.333 --> 35:10.433 align:left position:42.5%,start line:89% size:47.5%
That is

35:10.533 --> 35:13.233 align:left position:12.5%,start line:89% size:77.5%
100,000,000 years right there.

35:13.333 --> 35:15.966 align:left position:10%,start line:89% size:80%
Green blue is 200,000,000 years.

35:16.066 --> 35:19.233 align:left position:15%,start line:83% size:75%
And so this thing looks like
it's actually relatively young.

35:19.333 --> 35:22.200 align:left position:15%,start line:83% size:75%
It's around 50,000,000 years
old, look at the color there.

35:22.300 --> 35:24.533 align:left position:17.5%,start line:5% size:72.5%
Now, a key component of any
type of scientific research

35:24.633 --> 35:26.433 align:left position:12.5%,start line:5% size:77.5%
is not only can I put a number,

35:26.533 --> 35:28.400 align:left position:25%,start line:5% size:65%
but understanding how
precise that number is.

35:28.500 --> 35:30.900 align:left position:25%,start line:5% size:65%
Is it a good number?
Is it a usable number?

35:31.000 --> 35:33.133 align:left position:25%,start line:5% size:65%
To what degree is it
good, is it usable?

35:33.233 --> 35:37.300 align:left position:15%,start line:5% size:75%
That comes with precision or
understanding the uncertainty.

35:37.400 --> 35:39.966 align:left position:25%,start line:83% size:65%
And so this one over
here on the right

35:40.066 --> 35:43.800 align:left position:30%,start line:83% size:60%
is a ratio of the
age we determined

35:43.900 --> 35:46.000 align:left position:32.5%,start line:83% size:57.5%
divided by how
uncertain we think it is.

35:46.100 --> 35:48.233 align:left position:22.5%,start line:83% size:67.5%
And those numbers are a
little bit hard to see,

35:48.333 --> 35:50.333 align:left position:30%,start line:83% size:60%
but they range to
about 10 to 20 there.

35:50.433 --> 35:53.166 align:left position:25%,start line:83% size:65%
So it's 10 to 20, the
age is 10 to 20 times

35:53.266 --> 35:55.333 align:left position:20%,start line:83% size:70%
what the precision of it
is, which is not too bad.

35:55.433 --> 35:57.133 align:left position:10%,start line:89% size:80%
We could do a little bit better.

35:57.233 --> 36:00.966 align:left position:25%,start line:83% size:65%
But that is just the
so-called random uncertainty.

36:02.333 --> 36:05.633 align:left position:25%,start line:5% size:65%
That's if everything
else was just fine,

36:05.733 --> 36:08.533 align:left position:20%,start line:5% size:70%
just due to the nature of
the random fluctuations

36:08.633 --> 36:10.666 align:left position:25%,start line:5% size:65%
in the data you get,
how good the data are,

36:10.766 --> 36:13.866 align:left position:22.5%,start line:5% size:67.5%
but there are more than
random fluctuations.

36:14.900 --> 36:17.866 align:left position:32.5%,start line:5% size:57.5%
There are also
systematic uncertainties.

36:17.966 --> 36:21.500 align:left position:17.5%,start line:5% size:72.5%
And I'm gonna make a brief
but kinda big deal about this.

36:21.600 --> 36:23.366 align:left position:27.5%,start line:5% size:62.5%
I'm gonna put it up
here, systematic errors,

36:23.466 --> 36:25.400 align:left position:20%,start line:5% size:70%
'cause this is important,
not just in astronomy,

36:25.500 --> 36:28.300 align:left position:15%,start line:5% size:75%
but in any time we're dealing
with any type of data,

36:28.400 --> 36:29.866 align:left position:20%,start line:5% size:70%
any type of information.

36:29.966 --> 36:32.466 align:left position:30%,start line:5% size:60%
It's not only the
basic precision of it,

36:32.566 --> 36:35.166 align:left position:27.5%,start line:5% size:62.5%
but also how well--
what are your assumptions

36:35.266 --> 36:36.833 align:left position:27.5%,start line:5% size:62.5%
and how well do you
know your assumptions?

36:36.933 --> 36:40.233 align:left position:20%,start line:5% size:70%
For example, polling data
is a commonly-used analogy.

36:40.333 --> 36:43.200 align:left position:22.5%,start line:5% size:67.5%
You'll see an error bar
quoted on most polls.

36:43.300 --> 36:47.200 align:left position:12.5%,start line:5% size:77.5%
That's 35% of people like this

36:47.300 --> 36:49.100 align:left position:15%,start line:5% size:75%
and 70% of people like that,

36:49.200 --> 36:51.933 align:left position:25%,start line:5% size:65%
put an error bar plus
or minus 2% or 3%

36:52.033 --> 36:53.800 align:left position:22.5%,start line:5% size:67.5%
is often what you hear.

36:53.900 --> 36:56.133 align:left position:12.5%,start line:5% size:77.5%
But that's only the full story

36:56.233 --> 37:01.033 align:left position:32.5%,start line:5% size:57.5%
if it's been a
careful representative
sample of the people.

37:01.133 --> 37:03.600 align:left position:30%,start line:5% size:60%
If they only call
up a group of people

37:03.700 --> 37:06.433 align:left position:25%,start line:5% size:65%
who have a particular
connection with each other,

37:06.533 --> 37:09.933 align:left position:15%,start line:5% size:75%
they may get very different,
very skewed and biased results.

37:10.033 --> 37:11.800 align:left position:25%,start line:5% size:65%
And that's what we're
trying to understand here.

37:11.900 --> 37:13.433 align:left position:10%,start line:5% size:80%
The basic techniques I outlined,

37:13.533 --> 37:17.900 align:left position:20%,start line:5% size:70%
the plot of those simple
radio spectra, are great,

37:18.000 --> 37:19.833 align:left position:22.5%,start line:5% size:67.5%
but they sweep a lotta
things under the carpet.

37:19.933 --> 37:21.566 align:left position:22.5%,start line:5% size:67.5%
It's not that anybody's
been hiding anything.

37:21.666 --> 37:25.333 align:left position:17.5%,start line:5% size:72.5%
It's just this is something
that was developed 50 years ago.

37:25.433 --> 37:26.866 align:left position:12.5%,start line:5% size:77.5%
It's a beautiful piece of work,

37:26.966 --> 37:29.466 align:left position:27.5%,start line:5% size:62.5%
but the real things
are so complicated

37:29.566 --> 37:31.266 align:left position:25%,start line:5% size:65%
that you have to make
certain assumptions

37:31.366 --> 37:32.933 align:left position:30%,start line:5% size:60%
that we know are
not valid in nature.

37:33.033 --> 37:35.966 align:left position:25%,start line:5% size:65%
The question is, how
invalid are they?

37:36.066 --> 37:37.400 align:left position:27.5%,start line:5% size:62.5%
What will they do?

37:37.500 --> 37:40.200 align:left position:20%,start line:5% size:70%
What do these assumptions
do that we've made?

37:40.300 --> 37:43.066 align:left position:20%,start line:5% size:70%
And so this is where the
numerical simulations

37:43.166 --> 37:45.266 align:left position:27.5%,start line:5% size:62.5%
I was talking about
come into play.

37:45.366 --> 37:47.700 align:left position:42.5%,start line:5% size:47.5%
We are

37:47.800 --> 37:49.833 align:left position:22.5%,start line:5% size:67.5%
using computer models,

37:49.933 --> 37:53.966 align:left position:20%,start line:5% size:70%
basically creating these
AGN inside of a computer,

37:54.066 --> 37:56.933 align:left position:25%,start line:5% size:65%
letting them age, and
seeing what happens to them.

37:57.033 --> 37:59.366 align:left position:20%,start line:5% size:70%
And remember, I told you
earlier that we would be talking

37:59.466 --> 38:02.466 align:left position:17.5%,start line:5% size:72.5%
about a couple things here:
one is the turnover frequency.

38:02.566 --> 38:05.333 align:left position:25%,start line:83% size:65%
That's what this is.
This is 100 megahertz.

38:05.433 --> 38:08.266 align:left position:17.5%,start line:83% size:72.5%
1,000 megahertz, so this is
the range we're observing.

38:08.366 --> 38:09.900 align:left position:25%,start line:89% size:65%
This is 10 gigahertz.

38:10.000 --> 38:12.666 align:left position:22.5%,start line:83% size:67.5%
You'd have to go to the
VLA in New Mexico to see that.

38:12.766 --> 38:15.633 align:left position:17.5%,start line:83% size:72.5%
This is a snapshot in time.
This one's 10,000,000 years old.

38:15.733 --> 38:18.166 align:left position:10%,start line:83% size:80%
This one's 40,000,000 years old.
Again, this is the simulation.

38:18.266 --> 38:21.300 align:left position:22.5%,start line:83% size:67.5%
So we're looking at it
at a particular time.

38:21.400 --> 38:24.400 align:left position:17.5%,start line:89% size:72.5%
If everything were simple,

38:24.500 --> 38:26.500 align:left position:35%,start line:83% size:55%
as that basic
model was assuming,

38:26.600 --> 38:29.533 align:left position:32.5%,start line:83% size:57.5%
this should all
have the same color,

38:29.633 --> 38:32.933 align:left position:20%,start line:83% size:70%
should all have the same
color frequency. It doesn't.

38:33.033 --> 38:34.833 align:left position:32.5%,start line:83% size:57.5%
Some of this is
very high frequency.

38:34.933 --> 38:36.500 align:left position:32.5%,start line:83% size:57.5%
Some of this is
very low frequency.

38:36.600 --> 38:38.200 align:left position:27.5%,start line:83% size:62.5%
That tells us that
there's a lot going on.

38:38.300 --> 38:39.666 align:left position:30%,start line:83% size:60%
It's not that we
didn't know this,

38:39.766 --> 38:41.566 align:left position:27.5%,start line:83% size:62.5%
but we're trying to
better understand this.

38:41.666 --> 38:45.000 align:left position:17.5%,start line:83% size:72.5%
And over here is a measure
of the shape of the spectrum.

38:45.100 --> 38:46.866 align:left position:25%,start line:83% size:65%
Again, the key thing
is to look at the range

38:46.966 --> 38:48.700 align:left position:22.5%,start line:89% size:67.5%
of colors across this.

38:48.800 --> 38:50.666 align:left position:32.5%,start line:83% size:57.5%
These are just
snapshots in time.

38:50.766 --> 38:52.466 align:left position:32.5%,start line:89% size:57.5%
I have a movie.

38:52.566 --> 38:54.233 align:left position:25%,start line:89% size:65%
This is kind of fun.

38:54.333 --> 38:56.000 align:left position:22.5%,start line:83% size:67.5%
It's a different color
scale because we're still,

38:56.100 --> 38:57.766 align:left position:22.5%,start line:83% size:67.5%
this is still very much
work under development,

38:57.866 --> 38:59.466 align:left position:20%,start line:83% size:70%
and Yi-Hao, the graduate
student who's working

38:59.566 --> 39:01.833 align:left position:10%,start line:83% size:80%
on this changed the color scale.
He likes this one better.

39:01.933 --> 39:04.400 align:left position:22.5%,start line:83% size:67.5%
I think it's kinda fun.
We're watching time move here.

39:04.500 --> 39:07.366 align:left position:30%,start line:83% size:60%
This is the jet.
This is inside a simulation.

39:07.466 --> 39:09.033 align:left position:22.5%,start line:89% size:67.5%
You're seeing the jet.

39:09.133 --> 39:11.633 align:left position:15%,start line:83% size:75%
The black hole is where that
yellow stuff is spouting out.

39:11.733 --> 39:15.700 align:left position:32.5%,start line:83% size:57.5%
And again, the
color coding here is

39:15.800 --> 39:18.566 align:left position:25%,start line:83% size:65%
that frequency where
the spectrum turns over.

39:18.666 --> 39:21.066 align:left position:27.5%,start line:83% size:62.5%
The deep purple is
below 100 megahertz,

39:21.166 --> 39:23.200 align:left position:27.5%,start line:83% size:62.5%
very low frequency,
lower than we can see.

39:23.300 --> 39:25.633 align:left position:27.5%,start line:83% size:62.5%
And the blue is up
at 10 gigahertz.

39:25.733 --> 39:27.766 align:left position:25%,start line:83% size:65%
I mean, the yellow's
up at 10 gigahertz.

39:27.866 --> 39:31.233 align:left position:17.5%,start line:83% size:72.5%
So what you're seeing is an
evolution of the spectrum

39:31.333 --> 39:33.333 align:left position:15%,start line:89% size:75%
of the radio source in time.

39:33.433 --> 39:35.600 align:left position:17.5%,start line:83% size:72.5%
Can't show it all at once,
it'd just be too confusing.

39:35.700 --> 39:37.800 align:left position:22.5%,start line:83% size:67.5%
I mean, as it is, we're
looking at a three-dimensional

39:37.900 --> 39:39.566 align:left position:35%,start line:83% size:55%
model here in
two-dimensional space.

39:39.666 --> 39:43.500 align:left position:15%,start line:83% size:75%
The point is, you're watching
it age before your very eyes.

39:43.600 --> 39:47.133 align:left position:17.5%,start line:83% size:72.5%
What the color coding here
represents how it would look

39:47.233 --> 39:49.066 align:left position:22.5%,start line:83% size:67.5%
to us if we observed it
in a radio telescope.

39:49.166 --> 39:51.633 align:left position:25%,start line:83% size:65%
So what we're trying
to do is understand,

39:51.733 --> 39:53.666 align:left position:22.5%,start line:83% size:67.5%
better understand what
the data we're getting out

39:53.766 --> 39:56.900 align:left position:22.5%,start line:83% size:67.5%
of this radio telescope
in India actually mean.

39:58.533 --> 40:00.900 align:left position:25%,start line:89% size:65%
And it's going out to

40:01.000 --> 40:04.533 align:left position:17.5%,start line:83% size:72.5%
350,000,000 years, it goes
out to 500,000,000 years.

40:04.633 --> 40:07.000 align:left position:22.5%,start line:83% size:67.5%
So this is a simulation
over half a billion years

40:07.100 --> 40:08.800 align:left position:32.5%,start line:89% size:57.5%
of cosmic time.

40:09.933 --> 40:12.566 align:left position:27.5%,start line:83% size:62.5%
And we're trying to
use this to inform,

40:12.666 --> 40:14.533 align:left position:30%,start line:83% size:60%
let's play it one
more time real quick.

40:14.633 --> 40:17.066 align:left position:27.5%,start line:83% size:62.5%
There it is again.
There's the jet.

40:17.166 --> 40:20.033 align:left position:15%,start line:83% size:75%
That's the galaxy, the active
nucleus is very active.

40:20.133 --> 40:23.100 align:left position:20%,start line:83% size:70%
The black hole's running.
We're at 3,000,000 years.

40:24.266 --> 40:26.800 align:left position:22.5%,start line:83% size:67.5%
It goes slowly at first
and then shuts off.

40:26.900 --> 40:28.300 align:left position:30%,start line:83% size:60%
I think they shut
off the black hole

40:28.400 --> 40:31.600 align:left position:20%,start line:83% size:70%
at about 10,000,000 years
and then they speed up

40:31.700 --> 40:33.400 align:left position:30%,start line:83% size:60%
because we would
be here all night

40:33.500 --> 40:36.266 align:left position:12.5%,start line:89% size:77.5%
if we watched it at this pace.

40:36.366 --> 40:37.766 align:left position:25%,start line:89% size:65%
It's 8,000,000 years.

40:37.866 --> 40:39.966 align:left position:27.5%,start line:83% size:62.5%
So you see that the
yellow, there it goes,

40:40.066 --> 40:42.866 align:left position:15%,start line:83% size:75%
the black hole just shut off.
The active nucleus shut off.

40:42.966 --> 40:44.733 align:left position:15%,start line:89% size:75%
Now it's passively evolving.

40:44.833 --> 40:49.033 align:left position:12.5%,start line:83% size:77.5%
So if we were to observe a real
galaxy that was like this,

40:49.133 --> 40:52.900 align:left position:20%,start line:83% size:70%
this would be the relic,
this would be the artifact.

40:53.000 --> 40:56.966 align:left position:15%,start line:83% size:75%
This would be what we dug up
as the cosmic archeologists,

40:57.066 --> 40:58.400 align:left position:22.5%,start line:89% size:67.5%
that thing right there.

40:58.500 --> 41:00.100 align:left position:27.5%,start line:83% size:62.5%
A snapshot in time,
that we, unfortunately,

41:00.200 --> 41:02.466 align:left position:12.5%,start line:89% size:77.5%
we can't see that in real life.

41:02.566 --> 41:04.500 align:left position:30%,start line:83% size:60%
It's only in the
simulation that we're able

41:04.600 --> 41:06.133 align:left position:27.5%,start line:89% size:62.5%
to see that movie.

41:06.233 --> 41:09.800 align:left position:22.5%,start line:83% size:67.5%
But we're trying to use
these simulations to inform

41:09.900 --> 41:12.900 align:left position:17.5%,start line:83% size:72.5%
what it is we are actually
seeing in real life.

41:13.000 --> 41:15.766 align:left position:27.5%,start line:5% size:62.5%
So the trick is to
take the observations

41:15.866 --> 41:17.933 align:left position:15%,start line:5% size:75%
that we're making with these
radio telescopes and say,

41:18.033 --> 41:21.833 align:left position:30%,start line:5% size:60%
"All right, well,
what is the best match?

41:21.933 --> 41:24.633 align:left position:30%,start line:5% size:60%
"What timing here
does it best match

41:24.733 --> 41:26.500 align:left position:30%,start line:5% size:60%
"and how well can
we determine that?"

41:26.600 --> 41:30.333 align:left position:17.5%,start line:5% size:72.5%
So that's where a lotta the
work is going on right now.

41:35.266 --> 41:38.466 align:left position:22.5%,start line:5% size:67.5%
And this is what I was
just talking about.

41:38.566 --> 41:40.500 align:left position:22.5%,start line:5% size:67.5%
What if we pretend the
simulations are real?

41:40.600 --> 41:42.400 align:left position:27.5%,start line:5% size:62.5%
And what I mean by
that is we can take--

41:42.500 --> 41:44.666 align:left position:20%,start line:5% size:70%
Those simulations have an
enormous amount of information.

41:44.766 --> 41:46.866 align:left position:17.5%,start line:5% size:72.5%
You saw there's information
about the shape of the spectrum,

41:46.966 --> 41:48.633 align:left position:25%,start line:5% size:65%
information about the
slope of the spectrum,

41:48.733 --> 41:51.400 align:left position:22.5%,start line:5% size:67.5%
information about time,
we have brightness of it.

41:51.500 --> 41:52.800 align:left position:30%,start line:5% size:60%
We have all these
different qualities.

41:52.900 --> 41:55.066 align:left position:30%,start line:5% size:60%
We know what the
pressure of the gas is.

41:55.166 --> 41:56.866 align:left position:30%,start line:5% size:60%
We know what the
magnetic fields are,

41:56.966 --> 41:59.566 align:left position:20%,start line:5% size:70%
far more than we know in
an actual, real observation.

41:59.666 --> 42:02.933 align:left position:20%,start line:5% size:70%
So to really try to make
progress in understanding

42:03.033 --> 42:06.300 align:left position:15%,start line:5% size:75%
what it can tell us, we have
to look at these simulations

42:06.400 --> 42:10.833 align:left position:30%,start line:5% size:60%
as though we were
actually making a

42:10.933 --> 42:12.400 align:left position:30%,start line:5% size:60%
real observation.

42:12.500 --> 42:14.733 align:left position:25%,start line:5% size:65%
And that's what these
are representing.

42:14.833 --> 42:17.000 align:left position:27.5%,start line:5% size:62.5%
So there are three
simulations here.

42:17.100 --> 42:20.966 align:left position:12.5%,start line:89% size:77.5%
The 10,000,000 years, this one.

42:21.066 --> 42:23.200 align:left position:22.5%,start line:83% size:67.5%
50,000,000 years, these
are snapshots in time

42:23.300 --> 42:24.933 align:left position:17.5%,start line:89% size:72.5%
of the simulation you saw.

42:25.033 --> 42:26.433 align:left position:27.5%,start line:89% size:62.5%
100,000,000 years.

42:26.533 --> 42:28.133 align:left position:25%,start line:83% size:65%
By the way, note the
different size scale.

42:28.233 --> 42:29.766 align:left position:30%,start line:89% size:60%
It looks smaller,

42:29.866 --> 42:31.966 align:left position:27.5%,start line:83% size:62.5%
yet you saw it was
getting bigger with time.

42:32.066 --> 42:33.933 align:left position:22.5%,start line:83% size:67.5%
That's just because it
got too big to fit on here

42:34.033 --> 42:36.966 align:left position:25%,start line:83% size:65%
so I changed the size
scale to fit it on there.

42:37.066 --> 42:38.766 align:left position:25%,start line:83% size:65%
So I'm just alerting
people of that.

42:38.866 --> 42:41.466 align:left position:12.5%,start line:83% size:77.5%
Up here, this is an indication
of that spectral shape,

42:41.566 --> 42:43.400 align:left position:22.5%,start line:83% size:67.5%
but let's go down here
and look at the age.

42:43.500 --> 42:46.533 align:left position:17.5%,start line:83% size:72.5%
And it's a little difficult
to see it scale on here

42:46.633 --> 42:49.133 align:left position:25%,start line:89% size:65%
with this large view.

42:49.233 --> 42:53.566 align:left position:27.5%,start line:83% size:62.5%
But this is, if we
looked at a region

42:53.666 --> 42:57.466 align:left position:25%,start line:83% size:65%
of this radio source
using the basic techniques

42:57.566 --> 42:59.200 align:left position:22.5%,start line:83% size:67.5%
I talked about when we
first introduced them,

42:59.300 --> 43:02.166 align:left position:22.5%,start line:83% size:67.5%
when I introduced those
simple radio spectra,

43:02.266 --> 43:04.200 align:left position:27.5%,start line:83% size:62.5%
this is how old it
would tell us it is.

43:04.300 --> 43:09.000 align:left position:17.5%,start line:83% size:72.5%
So it would say that colors
down here in this region

43:09.100 --> 43:11.000 align:left position:20%,start line:89% size:70%
are 8,000,000 years old.

43:11.100 --> 43:12.966 align:left position:27.5%,start line:83% size:62.5%
Colors out here are
22,000,000 years.

43:13.066 --> 43:16.000 align:left position:25%,start line:77% size:65%
The actual simulation
age, that's the nice
thing about this.

43:16.100 --> 43:19.000 align:left position:22.5%,start line:83% size:67.5%
We know exactly how old
this is because it's made up

43:19.100 --> 43:21.533 align:left position:27.5%,start line:83% size:62.5%
and we can test it,
is 10,000,000 years.

43:21.633 --> 43:24.966 align:left position:30%,start line:83% size:60%
So it doesn't do
too bad of a job,

43:25.066 --> 43:26.600 align:left position:12.5%,start line:89% size:77.5%
but here is one of the reasons

43:26.700 --> 43:28.700 align:left position:22.5%,start line:83% size:67.5%
why we are doing these
simulations. Look at this.

43:28.800 --> 43:31.500 align:left position:20%,start line:83% size:70%
You saw this in the movie
and some of the stills I did.

43:31.600 --> 43:33.000 align:left position:12.5%,start line:89% size:77.5%
This is a very different color.

43:33.100 --> 43:34.966 align:left position:27.5%,start line:83% size:62.5%
So 10,000,000 years
is around here,

43:35.066 --> 43:36.633 align:left position:27.5%,start line:83% size:62.5%
so this should all
be that blue color,

43:36.733 --> 43:38.033 align:left position:22.5%,start line:89% size:67.5%
but a lot of it is not.

43:38.133 --> 43:39.566 align:left position:15%,start line:89% size:75%
A lot of it looks much older.

43:39.666 --> 43:41.166 align:left position:32.5%,start line:83% size:57.5%
And we think we
understand why that is.

43:41.266 --> 43:42.566 align:left position:27.5%,start line:83% size:62.5%
There are very good
reasons for it.

43:42.666 --> 43:44.566 align:left position:25%,start line:5% size:65%
It's losing energy to
blowing material around,

43:44.666 --> 43:46.200 align:left position:32.5%,start line:5% size:57.5%
a lot of other
things are going on,

43:46.300 --> 43:47.900 align:left position:25%,start line:5% size:65%
but that's what we're
trying to understand.

43:48.000 --> 43:51.433 align:left position:12.5%,start line:5% size:77.5%
And then out here, this should
be 50,000,000 years old.

43:51.533 --> 43:55.266 align:left position:15%,start line:5% size:75%
That's way off the scale, so
this time snapshot looks older.

43:56.733 --> 43:59.800 align:left position:25%,start line:5% size:65%
All of it looks older
than it really is

43:59.900 --> 44:01.600 align:left position:27.5%,start line:5% size:62.5%
in the simulation.

44:01.700 --> 44:04.166 align:left position:22.5%,start line:5% size:67.5%
This one's not so bad.

44:04.266 --> 44:05.566 align:left position:32.5%,start line:83% size:57.5%
This should be
100,000,000 years old.

44:05.666 --> 44:07.500 align:left position:15%,start line:89% size:75%
Most of it's that blue color.

44:07.600 --> 44:09.300 align:left position:25%,start line:83% size:65%
The point of this is
that by doing this,

44:09.400 --> 44:14.033 align:left position:20%,start line:83% size:70%
we can better understand
how good our deductions are

44:14.133 --> 44:16.733 align:left position:17.5%,start line:5% size:72.5%
about what we're learning,
and ultimately be able

44:16.833 --> 44:18.600 align:left position:15%,start line:89% size:75%
to make corrections for that.

44:18.700 --> 44:21.000 align:left position:25%,start line:5% size:65%
So that's where we're
going with this.

44:21.100 --> 44:24.066 align:left position:27.5%,start line:5% size:62.5%
All right. So where
do we go from here?

44:24.166 --> 44:26.033 align:left position:25%,start line:5% size:65%
So we've made quite a
bit of progress already.

44:26.133 --> 44:28.866 align:left position:32.5%,start line:5% size:57.5%
You can see the
simulations are underway.

44:28.966 --> 44:31.233 align:left position:30%,start line:5% size:60%
Surveying of the
radio is almost done.

44:31.333 --> 44:34.133 align:left position:15%,start line:5% size:75%
We're still working on doing
the radio data reduction,

44:34.233 --> 44:36.733 align:left position:30%,start line:5% size:60%
whoops, back up.

44:36.833 --> 44:38.400 align:left position:12.5%,start line:5% size:77.5%
That's what this is over here.

44:38.500 --> 44:40.733 align:left position:17.5%,start line:83% size:72.5%
It's gonna be a little hard
probably to see from the back,

44:40.833 --> 44:43.033 align:left position:20%,start line:83% size:70%
but these are two images
of the same thing,

44:43.133 --> 44:45.166 align:left position:20%,start line:83% size:70%
just showing the progress
we're slowly making.

44:45.266 --> 44:47.166 align:left position:12.5%,start line:89% size:77.5%
This is a brand new telescope.

44:47.266 --> 44:50.633 align:left position:12.5%,start line:83% size:77.5%
Nobody really knows exactly how
to reduce the data from it yet.

44:50.733 --> 44:53.433 align:left position:20%,start line:77% size:70%
Even the people who built
it are still learning it,
and so are we.

44:53.533 --> 44:55.700 align:left position:25%,start line:77% size:65%
And there's a bit of
an improvement, if you
squint your eyes.

44:55.800 --> 44:59.500 align:left position:22.5%,start line:77% size:67.5%
We measured it. There's
some banding in the left
panel here of this.

44:59.600 --> 45:02.033 align:left position:10%,start line:83% size:80%
That is, there's some banding in
here that's disappeared there.

45:02.133 --> 45:05.633 align:left position:22.5%,start line:77% size:67.5%
So we're busy trying to
figure that out, finish
the observations,

45:05.733 --> 45:07.600 align:left position:25%,start line:83% size:65%
and then later on go
observe more of these.

45:07.700 --> 45:10.166 align:left position:17.5%,start line:83% size:72.5%
After all this time, three
observing runs a year

45:10.266 --> 45:13.633 align:left position:22.5%,start line:83% size:67.5%
working on this, we've
observed 40, which is a lot.

45:13.733 --> 45:15.533 align:left position:12.5%,start line:89% size:77.5%
But there are a lot more to go.

45:15.633 --> 45:17.833 align:left position:22.5%,start line:83% size:67.5%
And then I talked about
these simulations.

45:17.933 --> 45:19.566 align:left position:30%,start line:83% size:60%
I just showed you
one simulation.

45:19.666 --> 45:22.333 align:left position:12.5%,start line:89% size:77.5%
We learned a lot by doing that.

45:22.433 --> 45:23.866 align:left position:25%,start line:89% size:65%
We're gonna do more.

45:23.966 --> 45:25.433 align:left position:27.5%,start line:83% size:62.5%
For one thing, and
it's gonna be done

45:25.533 --> 45:27.000 align:left position:25%,start line:83% size:65%
on this thing called
XSEDE, which is the

45:27.100 --> 45:30.000 align:left position:12.5%,start line:83% size:77.5%
Extreme Science and Engineering
Discovery Environment.

45:30.100 --> 45:31.700 align:left position:35%,start line:83% size:55%
I'm glad they
shortened it to XSEDE.

45:31.800 --> 45:33.066 align:left position:12.5%,start line:89% size:77.5%
It's an NSF funded thing again.

45:33.166 --> 45:35.833 align:left position:30%,start line:83% size:60%
Again, the NSF is
supporting science of a lot

45:35.933 --> 45:38.200 align:left position:20%,start line:83% size:70%
of different fields with
this, and we've been awarded

45:38.300 --> 45:41.166 align:left position:15%,start line:89% size:75%
3,000,000 core hours so far.

45:41.266 --> 45:45.066 align:left position:15%,start line:83% size:75%
That sounds like a lot to me.
I don't work in this normally.

45:45.166 --> 45:46.300 align:left position:15%,start line:89% size:75%
Sebastian, he had to do this.

45:46.400 --> 45:48.166 align:left position:32.5%,start line:83% size:57.5%
So that sounded
impressive to me.

45:48.266 --> 45:49.833 align:left position:37.5%,start line:89% size:52.5%
And it is.

45:49.933 --> 45:53.766 align:left position:22.5%,start line:83% size:67.5%
It would take centuries
on this laptop to do this.

45:53.866 --> 45:56.666 align:left position:17.5%,start line:83% size:72.5%
And on this supercomputer,
we're gonna run it in a month.

45:56.766 --> 45:58.333 align:left position:30%,start line:83% size:60%
So 3,000,000 core
hours for that.

45:58.433 --> 46:02.000 align:left position:15%,start line:83% size:75%
And we're going to change the
parameters of the material

46:02.100 --> 46:04.700 align:left position:15%,start line:89% size:75%
into which these AGN jets go,

46:04.800 --> 46:06.600 align:left position:27.5%,start line:83% size:62.5%
how they make those
jets and lobes,

46:06.700 --> 46:10.766 align:left position:17.5%,start line:83% size:72.5%
to better match the actual
galaxies that we're observing.

46:10.866 --> 46:13.400 align:left position:27.5%,start line:5% size:62.5%
We're gonna change
the range of power

46:13.500 --> 46:14.900 align:left position:12.5%,start line:5% size:77.5%
of the jet coming out of there.

46:15.000 --> 46:16.433 align:left position:22.5%,start line:5% size:67.5%
Everything I showed you

46:16.533 --> 46:18.700 align:left position:17.5%,start line:5% size:72.5%
was a great starting point,
but it's one simulation.

46:18.800 --> 46:22.033 align:left position:15%,start line:5% size:75%
So we're now gonna do a grid
of nine in this next one

46:22.133 --> 46:25.666 align:left position:25%,start line:5% size:65%
and better learn how
these parameters affect

46:25.766 --> 46:29.933 align:left position:20%,start line:5% size:70%
the results and what they
mean for our interpretation

46:30.033 --> 46:33.000 align:left position:32.5%,start line:5% size:57.5%
of how old our
own real data are,

46:33.100 --> 46:34.666 align:left position:27.5%,start line:5% size:62.5%
'cause that's what
we're gonna do.

46:34.766 --> 46:37.166 align:left position:17.5%,start line:5% size:72.5%
We're gonna try to measure
how old these simulations are

46:37.266 --> 46:40.000 align:left position:12.5%,start line:5% size:77.5%
when we know how old they are,

46:40.100 --> 46:42.466 align:left position:25%,start line:5% size:65%
and then learn how we
can better determine

46:42.566 --> 46:46.733 align:left position:17.5%,start line:5% size:72.5%
the ages of our real AGN so
we can connect those together.

46:46.833 --> 46:48.666 align:left position:25%,start line:5% size:65%
And I haven't talked
too much about the stars

46:48.766 --> 46:50.433 align:left position:15%,start line:5% size:75%
since I first did the intro,

46:50.533 --> 46:52.100 align:left position:27.5%,start line:5% size:62.5%
because we've been
mostly focusing

46:52.200 --> 46:55.400 align:left position:15%,start line:5% size:75%
on the active galactic nuclei
and the radio observation.

46:55.500 --> 46:57.333 align:left position:12.5%,start line:89% size:77.5%
But we have a lot of neat stuff

46:57.433 --> 46:59.233 align:left position:30%,start line:83% size:60%
to look at those
stellar populations,

46:59.333 --> 47:02.966 align:left position:27.5%,start line:83% size:62.5%
to disentangle the
different ages of the stars

47:03.066 --> 47:04.733 align:left position:20%,start line:83% size:70%
and build up the history
of star formation

47:04.833 --> 47:07.300 align:left position:20%,start line:89% size:70%
across the entire galaxy.

47:07.400 --> 47:11.900 align:left position:30%,start line:83% size:60%
And UW-Madison is
a major partner in

47:12.000 --> 47:13.833 align:left position:15%,start line:89% size:75%
something that's really cool.

47:13.933 --> 47:18.233 align:left position:27.5%,start line:83% size:62.5%
The specific survey
is called MaNGA,

47:18.333 --> 47:21.300 align:left position:27.5%,start line:83% size:62.5%
stands for Mapping
of Nearby Galaxies.

47:21.400 --> 47:23.933 align:left position:27.5%,start line:83% size:62.5%
I bet they made the
acronym up first

47:24.033 --> 47:27.133 align:left position:22.5%,start line:83% size:67.5%
because the guy leading
this at the time

47:27.233 --> 47:29.000 align:left position:10%,start line:89% size:80%
was living and working in Japan.

47:29.100 --> 47:32.066 align:left position:22.5%,start line:89% size:67.5%
So he thought, "Ah-ha,

47:32.166 --> 47:34.100 align:left position:15%,start line:89% size:75%
"that's a good name for it."

47:34.200 --> 47:37.400 align:left position:15%,start line:83% size:75%
It's part of something called
the Sloan Digital Sky Survey.

47:37.500 --> 47:39.700 align:left position:22.5%,start line:83% size:67.5%
If you haven't heard of
that, keep an eye out for it.

47:39.800 --> 47:42.966 align:left position:17.5%,start line:83% size:72.5%
It's been, I would say, one
of the most important surveys

47:43.066 --> 47:44.800 align:left position:32.5%,start line:83% size:57.5%
of the sky that
humans have done.

47:44.900 --> 47:47.066 align:left position:22.5%,start line:83% size:67.5%
It's been going on for
close to 20 years now.

47:47.166 --> 47:51.400 align:left position:22.5%,start line:83% size:67.5%
It's done with a rather
modest-looking telescope.

47:51.500 --> 47:54.000 align:left position:15%,start line:83% size:75%
That's it in the lower left.
It's a weird thing.

47:54.100 --> 47:56.300 align:left position:12.5%,start line:83% size:77.5%
I've never been out there, I've
seen plenty of pictures of it,

47:56.400 --> 47:58.000 align:left position:30%,start line:83% size:60%
but there's this
enclosure around it.

47:58.100 --> 48:03.200 align:left position:17.5%,start line:83% size:72.5%
It looks like it's a cannon
with those pedals up there.

48:03.300 --> 48:06.133 align:left position:27.5%,start line:83% size:62.5%
That's actually the
opening of the light paths.

48:06.233 --> 48:09.100 align:left position:20%,start line:77% size:70%
So the light goes in down
that tube and all the
detectors are down there.

48:09.200 --> 48:11.266 align:left position:22.5%,start line:83% size:67.5%
It's not that big of a
telescope by modern standards.

48:11.366 --> 48:14.066 align:left position:20%,start line:83% size:70%
It's about 2 1/2 meters,
but it is dedicated.

48:14.166 --> 48:15.833 align:left position:22.5%,start line:83% size:67.5%
First it was dedicated
to taking the images

48:15.933 --> 48:17.633 align:left position:15%,start line:89% size:75%
of a major swath of the sky.

48:17.733 --> 48:20.633 align:left position:22.5%,start line:77% size:67.5%
Those are all publicly
available, anybody can
go get that.

48:20.733 --> 48:24.733 align:left position:12.5%,start line:83% size:77.5%
Since then, it's been dedicated
to more specific activities,

48:24.833 --> 48:26.966 align:left position:15%,start line:89% size:75%
a series of survey projects.

48:27.066 --> 48:29.600 align:left position:22.5%,start line:83% size:67.5%
We're now in the fourth
generation of this,

48:29.700 --> 48:31.100 align:left position:25%,start line:89% size:65%
working on the fifth.

48:31.200 --> 48:33.200 align:left position:20%,start line:83% size:70%
And UW's heavily involved
in both of those.

48:33.300 --> 48:36.933 align:left position:20%,start line:83% size:70%
The project scientist for
all of this fourth generation

48:37.033 --> 48:39.466 align:left position:12.5%,start line:89% size:77.5%
of Sloan is one of our faculty.

48:39.566 --> 48:41.633 align:left position:32.5%,start line:83% size:57.5%
He's back right
next door to Marsha,

48:41.733 --> 48:44.100 align:left position:15%,start line:83% size:75%
who's the PI of our project,
so he's in our building.

48:44.200 --> 48:47.066 align:left position:22.5%,start line:83% size:67.5%
And we are also heavily
involved in designing

48:47.166 --> 48:49.400 align:left position:15%,start line:83% size:75%
one of the major projects for
the next generation of this.

48:49.500 --> 48:53.833 align:left position:32.5%,start line:83% size:57.5%
But on to this,
this MaNGA survey

48:53.933 --> 48:56.800 align:left position:17.5%,start line:83% size:72.5%
has been solving a problem
that has bedeviled astronomers

48:56.900 --> 48:58.566 align:left position:25%,start line:83% size:65%
who are doing things
like I'm trying to do,

48:58.666 --> 49:01.000 align:left position:20%,start line:83% size:70%
like our group is trying
to do, for a long time,

49:01.100 --> 49:04.633 align:left position:25%,start line:83% size:65%
in that a lot of what
we observe in galaxies

49:04.733 --> 49:09.233 align:left position:15%,start line:83% size:75%
with visible light is either
from one part of the galaxy,

49:09.333 --> 49:12.333 align:left position:30%,start line:83% size:60%
like the middle,
or it's a swath,

49:12.433 --> 49:14.666 align:left position:42.5%,start line:83% size:47.5%
a cut,
through the galaxy,

49:14.766 --> 49:17.633 align:left position:15%,start line:83% size:75%
because of the nature of the
instruments that are used.

49:17.733 --> 49:20.400 align:left position:25%,start line:5% size:65%
There are instruments
that use optical fibers,

49:20.500 --> 49:22.733 align:left position:25%,start line:5% size:65%
similar to what's in
telecommunication.

49:22.833 --> 49:24.866 align:left position:12.5%,start line:5% size:77.5%
Optical fibers are light pipes.

49:24.966 --> 49:27.933 align:left position:20%,start line:5% size:70%
Hold up an optical fiber,
whatever light comes in.

49:28.033 --> 49:31.000 align:left position:20%,start line:5% size:70%
Goes down a pipe. You can
bend them. Really cool.

49:31.100 --> 49:32.666 align:left position:27.5%,start line:5% size:62.5%
Move the light, and
it is a light pipe.

49:32.766 --> 49:35.033 align:left position:22.5%,start line:5% size:67.5%
You can take the light
from where it comes in

49:35.133 --> 49:37.233 align:left position:27.5%,start line:5% size:62.5%
from the telescope,
bend it around corners,

49:37.333 --> 49:39.733 align:left position:17.5%,start line:5% size:72.5%
go down somewhere else, and
run it into an instrument

49:39.833 --> 49:41.900 align:left position:27.5%,start line:5% size:62.5%
like a spectrograph
that makes the rainbow.

49:43.233 --> 49:44.833 align:left position:32.5%,start line:5% size:57.5%
So what MaNGA's
doing, and again,

49:44.933 --> 49:46.633 align:left position:20%,start line:5% size:70%
this isn't the first time
people have done this,

49:46.733 --> 49:48.600 align:left position:30%,start line:5% size:60%
but this is done
on a massive scale.

49:48.700 --> 49:51.100 align:left position:10%,start line:5% size:80%
They're putting a whole bunch of
these optical fibers together,

49:51.200 --> 49:55.100 align:left position:15%,start line:5% size:75%
and the graphic on the right
is meant to represent that.

49:55.200 --> 49:58.866 align:left position:12.5%,start line:83% size:77.5%
You can see the hands in there
are holding one of these things.

49:58.966 --> 50:01.433 align:left position:10%,start line:89% size:80%
These are small, little devices.

50:01.533 --> 50:04.466 align:left position:27.5%,start line:83% size:62.5%
That cylinder that
that person is holding

50:04.566 --> 50:07.166 align:left position:27.5%,start line:83% size:62.5%
contains dozens, it
depends on which one,

50:07.266 --> 50:11.700 align:left position:17.5%,start line:83% size:72.5%
we have different kinds of
up to close to 130 fibers,

50:11.800 --> 50:14.300 align:left position:30%,start line:83% size:60%
so dozens to over
100 of these fibers.

50:14.400 --> 50:17.100 align:left position:20%,start line:83% size:70%
If you look in the lower
right corner there,

50:17.200 --> 50:20.000 align:left position:25%,start line:83% size:65%
right here, this is a
close-up of the top of that

50:20.100 --> 50:21.333 align:left position:17.5%,start line:89% size:72.5%
with a little graphic done.

50:21.433 --> 50:23.100 align:left position:27.5%,start line:83% size:62.5%
This is showing an
overlay of a galaxy.

50:23.200 --> 50:24.833 align:left position:27.5%,start line:83% size:62.5%
The idea is, here,
you get the telescope,

50:24.933 --> 50:26.466 align:left position:30%,start line:83% size:60%
make a picture of
the galaxy here.

50:26.566 --> 50:28.400 align:left position:30%,start line:83% size:60%
And every one of
these little spots

50:28.500 --> 50:30.266 align:left position:12.5%,start line:89% size:77.5%
is one of these optical fibers.

50:30.366 --> 50:32.400 align:left position:17.5%,start line:83% size:72.5%
And it will take the light
from each spot of the galaxy

50:32.500 --> 50:35.366 align:left position:12.5%,start line:83% size:77.5%
and run it into the instrument,
to the spectrograph,

50:35.466 --> 50:36.933 align:left position:17.5%,start line:89% size:72.5%
and make a spectrum for us.

50:37.033 --> 50:40.500 align:left position:20%,start line:83% size:70%
That allows us to look at
these stellar populations

50:40.600 --> 50:44.533 align:left position:20%,start line:83% size:70%
and other things about it
across the entire galaxy,

50:44.633 --> 50:46.266 align:left position:22.5%,start line:89% size:67.5%
not just at the center.

50:46.366 --> 50:49.100 align:left position:27.5%,start line:83% size:62.5%
So this is a really
important new development

50:49.200 --> 50:50.833 align:left position:25%,start line:83% size:65%
and this is basically
the second half

50:50.933 --> 50:53.666 align:left position:20%,start line:83% size:70%
of the archeological dig,
which we started on,

50:53.766 --> 50:55.400 align:left position:12.5%,start line:89% size:77.5%
but haven't gotten very far yet

50:55.500 --> 50:57.466 align:left position:15%,start line:83% size:75%
'cause we've been focusing on
the simulations and the radio.

50:57.566 --> 50:59.033 align:left position:30%,start line:83% size:60%
And this is just
a quick example,

50:59.133 --> 51:00.833 align:left position:25%,start line:83% size:65%
I'm gonna run through
this very quickly,

51:00.933 --> 51:02.333 align:left position:17.5%,start line:89% size:72.5%
of what this MaNGA can do.

51:02.433 --> 51:03.933 align:left position:32.5%,start line:83% size:57.5%
This is putting
everything together.

51:04.033 --> 51:06.900 align:left position:20%,start line:83% size:70%
So here is, in the image
down here in the lower left,

51:07.000 --> 51:09.733 align:left position:37.5%,start line:83% size:52.5%
of a rather
nondescript-looking galaxy.

51:09.833 --> 51:12.066 align:left position:20%,start line:83% size:70%
This is from the original
Sloan sky survey,

51:12.166 --> 51:13.433 align:left position:17.5%,start line:89% size:72.5%
the one that took pictures.

51:13.533 --> 51:16.066 align:left position:25%,start line:83% size:65%
This is a compendium
of radio maps.

51:16.166 --> 51:18.900 align:left position:27.5%,start line:83% size:62.5%
This is an overlay.
There's the galaxy right there.

51:19.000 --> 51:21.100 align:left position:20%,start line:83% size:70%
You can see it looks much
more interesting in the radio.

51:21.200 --> 51:23.100 align:left position:25%,start line:83% size:65%
These are those jets
and plumes going out.

51:23.200 --> 51:24.766 align:left position:32.5%,start line:83% size:57.5%
These are three
different surveys

51:24.866 --> 51:27.766 align:left position:15%,start line:83% size:75%
at two different frequencies,
three different surveys.

51:27.866 --> 51:29.833 align:left position:25%,start line:83% size:65%
This is not our data.
These are existing ones,

51:29.933 --> 51:31.800 align:left position:22.5%,start line:83% size:67.5%
but showing some of the
complexity in there.

51:31.900 --> 51:34.600 align:left position:20%,start line:77% size:70%
This is what we're trying
to measure to determine
the age of the AGN.

51:34.700 --> 51:38.066 align:left position:22.5%,start line:83% size:67.5%
And this is a result of
the MaNGA data product.

51:38.166 --> 51:40.700 align:left position:27.5%,start line:83% size:62.5%
This is looking at
actually ionized gas,

51:40.800 --> 51:43.066 align:left position:12.5%,start line:83% size:77.5%
which is a little bit different
from what I was telling you

51:43.166 --> 51:46.100 align:left position:25%,start line:83% size:65%
about in figuring out
the histories of stars,

51:46.200 --> 51:48.733 align:left position:22.5%,start line:77% size:67.5%
but it's important for
understanding what's
going on right now.

51:48.833 --> 51:50.533 align:left position:17.5%,start line:83% size:72.5%
So this will tell you about
current star formation

51:50.633 --> 51:52.633 align:left position:20%,start line:83% size:70%
and also what the active
nucleus is doing as well

51:52.733 --> 51:54.800 align:left position:20%,start line:89% size:70%
as looking at the radio.

51:54.900 --> 51:57.933 align:left position:20%,start line:83% size:70%
And you can see here, I'm
not gonna go into the details

51:58.033 --> 51:59.966 align:left position:30%,start line:83% size:60%
of this, but you
get in the past,

52:00.066 --> 52:03.700 align:left position:17.5%,start line:83% size:72.5%
we might get something from
just one part of the galaxy,

52:03.800 --> 52:05.166 align:left position:32.5%,start line:89% size:57.5%
or a slit here.

52:05.266 --> 52:08.000 align:left position:25%,start line:83% size:65%
Now we're able to see
across the entire galaxy.

52:08.100 --> 52:09.833 align:left position:30%,start line:83% size:60%
This is plotting
where the ionized,

52:09.933 --> 52:12.033 align:left position:30%,start line:83% size:60%
where we think is
causing the ionized gas,

52:12.133 --> 52:14.033 align:left position:10%,start line:89% size:80%
whether it's new star formation,

52:14.133 --> 52:15.633 align:left position:25%,start line:83% size:65%
so it tells us about
star formation,

52:15.733 --> 52:17.033 align:left position:32.5%,start line:83% size:57.5%
or whether it's
the active nucleus.

52:17.133 --> 52:18.933 align:left position:27.5%,start line:83% size:62.5%
So that's just the
tip of the iceberg

52:19.033 --> 52:21.333 align:left position:20%,start line:83% size:70%
of what we're getting out
of this MaNGA project.

52:21.433 --> 52:23.333 align:left position:37.5%,start line:89% size:52.5%
All right.

52:23.433 --> 52:26.433 align:left position:22.5%,start line:83% size:67.5%
To wrap up here, we've
talked about a lot.

52:26.533 --> 52:28.766 align:left position:17.5%,start line:89% size:72.5%
It's a complicated project.

52:28.866 --> 52:31.300 align:left position:15%,start line:5% size:75%
It's a fun project, but there
are a lotta pieces to it.

52:31.400 --> 52:34.233 align:left position:10%,start line:5% size:80%
So let's just review it briefly.

52:34.333 --> 52:37.266 align:left position:12.5%,start line:5% size:77.5%
And I'm going back to my little
shtick from the beginning,

52:37.366 --> 52:41.033 align:left position:20%,start line:5% size:70%
my silly little title for
here, the time travel.

52:41.966 --> 52:43.500 align:left position:30%,start line:5% size:60%
Again, that is--

52:44.500 --> 52:46.200 align:left position:25%,start line:5% size:65%
It's not technically
time travel,

52:46.300 --> 52:48.333 align:left position:20%,start line:5% size:70%
what we're talking about,
but it is an element of that.

52:48.433 --> 52:49.833 align:left position:27.5%,start line:5% size:62.5%
That's what I said
at the beginning.

52:49.933 --> 52:52.066 align:left position:30%,start line:5% size:60%
This title has a
grain of truth to it.

52:52.166 --> 52:55.266 align:left position:25%,start line:5% size:65%
It's a time travel in
the sense that by looking

52:55.366 --> 52:58.133 align:left position:15%,start line:5% size:75%
at objects that are far away,

52:58.233 --> 53:01.366 align:left position:30%,start line:5% size:60%
we are not seeing
relics of them.

53:01.466 --> 53:03.400 align:left position:27.5%,start line:5% size:62.5%
We are seeing them

53:03.500 --> 53:06.700 align:left position:25%,start line:5% size:65%
as they were early in
time, earlier in time.

53:06.800 --> 53:08.433 align:left position:22.5%,start line:5% size:67.5%
That's the analogy with
actually being able

53:08.533 --> 53:12.133 align:left position:20%,start line:5% size:70%
to watch the residents of
Pompeii on that fateful morning.

53:13.166 --> 53:15.233 align:left position:32.5%,start line:5% size:57.5%
That's the time
travel aspect of it.

53:15.333 --> 53:17.500 align:left position:15%,start line:5% size:75%
We are also doing archeology.

53:17.600 --> 53:20.333 align:left position:22.5%,start line:5% size:67.5%
That's looking into the
relics of past events

53:20.433 --> 53:23.500 align:left position:22.5%,start line:5% size:67.5%
in the histories of the
galaxies, their stars,

53:23.600 --> 53:25.233 align:left position:15%,start line:5% size:75%
their star formation history,

53:25.333 --> 53:27.633 align:left position:20%,start line:5% size:70%
and what the supermassive
black holes have been up to.

53:27.733 --> 53:29.533 align:left position:25%,start line:5% size:65%
That's pretty tricky.

53:29.633 --> 53:32.233 align:left position:27.5%,start line:5% size:62.5%
We can do it if the
supermassive black holes

53:32.333 --> 53:35.733 align:left position:17.5%,start line:5% size:72.5%
have been active and pumped
out all of this hot gas,

53:35.833 --> 53:38.933 align:left position:25%,start line:5% size:65%
this plasma, that is
emitting radio light.

53:39.033 --> 53:42.600 align:left position:30%,start line:5% size:60%
The spectrum, the
rainbow of radio light,

53:42.700 --> 53:45.833 align:left position:27.5%,start line:5% size:62.5%
encodes the history

53:45.933 --> 53:48.700 align:left position:20%,start line:5% size:70%
of what that supermassive
black hole's been doing.

53:48.800 --> 53:51.966 align:left position:22.5%,start line:5% size:67.5%
It's up to us to figure
out how to do it.

53:52.066 --> 53:54.200 align:left position:25%,start line:83% size:65%
So the time traveling
archeology aspect

53:54.300 --> 53:57.833 align:left position:27.5%,start line:83% size:62.5%
is we're looking at
galaxies as they were,

53:57.933 --> 54:01.433 align:left position:12.5%,start line:89% size:77.5%
but also at artifacts back then

54:01.533 --> 54:04.700 align:left position:25%,start line:83% size:65%
of even earlier epics
to try to figure out,

54:04.800 --> 54:07.433 align:left position:17.5%,start line:83% size:72.5%
the ultimate goal is to try
to figure out this timing

54:07.533 --> 54:10.700 align:left position:22.5%,start line:83% size:67.5%
between star formation
and the activity

54:10.800 --> 54:12.400 align:left position:27.5%,start line:83% size:62.5%
of the supermassive
black hole to see

54:12.500 --> 54:15.700 align:left position:25%,start line:83% size:65%
if we can really get
some deep insight

54:15.800 --> 54:17.566 align:left position:30%,start line:83% size:60%
into what people
think is going on,

54:17.666 --> 54:19.500 align:left position:25%,start line:83% size:65%
this deep connection
of how the activity

54:19.600 --> 54:21.800 align:left position:27.5%,start line:83% size:62.5%
of the supermassive
black hole and the stars

54:21.900 --> 54:24.000 align:left position:12.5%,start line:83% size:77.5%
in the galaxies are intimately
connected to each other.

54:24.100 --> 54:27.866 align:left position:25%,start line:83% size:65%
So it's part of that
larger ongoing story.

54:27.966 --> 54:31.766 align:left position:15%,start line:83% size:75%
And the final theme here, is
lots of tools coming together.

54:31.866 --> 54:34.600 align:left position:17.5%,start line:83% size:72.5%
That's what made this kind
of a complex talk in a way,

54:34.700 --> 54:37.033 align:left position:15%,start line:89% size:75%
but also a fun, fun project,

54:37.133 --> 54:39.166 align:left position:22.5%,start line:83% size:67.5%
because we're using the
state-of-the-art surveys.

54:39.266 --> 54:40.733 align:left position:22.5%,start line:83% size:67.5%
I only briefly alluded
to the radio ones,

54:40.833 --> 54:42.833 align:left position:15%,start line:83% size:75%
but there's several of those,
making good use of those.

54:42.933 --> 54:45.500 align:left position:10%,start line:89% size:80%
I talked about the MaNGA survey.

54:45.600 --> 54:47.566 align:left position:17.5%,start line:89% size:72.5%
We're using visible light.

54:47.666 --> 54:49.266 align:left position:30%,start line:83% size:60%
That's how we're
getting at the stars.

54:49.366 --> 54:50.766 align:left position:20%,start line:89% size:70%
We're using radio light.

54:50.866 --> 54:53.366 align:left position:20%,start line:83% size:70%
That's how we're getting
primarily at the active nucleus.

54:53.466 --> 54:55.800 align:left position:22.5%,start line:83% size:67.5%
And we're tying it all
together with simulations

54:55.900 --> 54:58.500 align:left position:17.5%,start line:83% size:72.5%
of the stars, and we talked
a little bit about that.

54:58.600 --> 55:00.600 align:left position:27.5%,start line:83% size:62.5%
But I alluded to it
back in the beginning

55:00.700 --> 55:03.333 align:left position:25%,start line:83% size:65%
when we're trying to
disentangle what the spectrum,

55:03.433 --> 55:05.066 align:left position:27.5%,start line:83% size:62.5%
what the rainbow of
light of the galaxy was

55:05.166 --> 55:07.900 align:left position:22.5%,start line:83% size:67.5%
in terms of how it was
put together in the past.

55:08.000 --> 55:09.633 align:left position:27.5%,start line:83% size:62.5%
When did the stars
form to do that?

55:09.733 --> 55:11.500 align:left position:17.5%,start line:89% size:72.5%
That's a modeling exercise.

55:11.600 --> 55:14.100 align:left position:15%,start line:83% size:75%
And also, simulations of the
jets and these big balloons,

55:14.200 --> 55:16.133 align:left position:27.5%,start line:83% size:62.5%
these lobes, of the
radio galaxies to try

55:16.233 --> 55:18.500 align:left position:25%,start line:83% size:65%
to better understand
what we're learning,

55:18.600 --> 55:21.266 align:left position:15%,start line:83% size:75%
what we think we're learning,
about the ages of them.

55:22.566 --> 55:24.666 align:left position:12.5%,start line:89% size:77.5%
Thanks so much, appreciate it.

55:24.766 --> 55:27.766 align:left position:37.5%,start line:5% size:52.5%
[applause]