(soft music)
(applause)
- Well, thank you.
This is, of course, episode two
of our QA Science post
lecture QA session.
We're here with local teachers,
as well as honors students
in the UA Honors College.
My name is John Pollard,
I'm gonna moderate this.
Of course, we're talking
to Professor Feryal Ozel.
I want to start off by
just making a comment,
and sort of a question.
How do you operate
in your everyday life
knowing these things?
I mean, that shot of the
moon when it was panned back
I don't know what
everyone else thought,
but I was sort of left
in a state of shock
at the magnitude of the universe
because it kind of
gave this impression.
My very first thought was
having this knowledge,
and sort of dwelling in
that realm of your research,
and then you have every day,
like you only have coffee
or something, I mean,
how do you bring these
two worlds together?
- Yeah.
- What's it, you know?
- To be honest on
a day-to-day basis
I don't think about
the scale of the things
that I'm working on.
If we did I think we
would go slightly crazy,
I mean, we being like
people who work on
different parts of the
universe and things far away,
like you said the Hubble Deep
Field, Chandra Deep Field,
black holes that are
far away from us.
I mean, I am usually
just caught up
in whatever is in front of me,
but once in a while it
does hit you that's like
I'm 10 minutes late to
something, and I'm stressed out,
and, you know, like, oh, my God,
like I'm truly a
spec of nothing,
and I'm just
continually, you know,
rushing against
time and whatever,
and it's like I'm on a tiny
planet in a vast universe
living for a blink of time,
and, of course, but that's
not how you live, I mean,
that's not how you live.
You have to take
your kids to school.
You have to make your
coffee so you're awake,
and, you know,
there's bills to pay,
and all of that, so, yeah.
- All right, well, I just had
to ask that to start this off.
I think we have some
mics in the audience.
I think we're just
gonna open it up here.
Do you want to hand the
mic over here to Jacob,
and we'll just
kind of go around.
Please hold the mic
up and go ahead Jacob.
- So what more
kinds of information
do you expect to glean from
the Event Horizon Telescope
given what you've already
gotten over the past 20 years
is there anymore to find
with the current technology?
- Yeah, so what I showed you
that time-lapse movie
from the last 20 years
is stars that are, okay,
we say close to the
galactic center,
but really they are
quite a bit farther away,
so by following their
motions we can say
there's a mass interior
to those orbits,
but it doesn't tell us what
the nature of that object is,
so with the Event Horizon we
are going much, much closer.
We would be going probably
six or seven orders
of magnitude closer,
like a million times closer
than where you see those stars,
the Event Horizon Telescope,
this image that we're
trying to obtain
is a million times closer,
and that's why we are
able to resolve, I mean,
the technology allows us to
resolve the horizon scale.
- [Jacob] Thank you.
- Another question.
Why don't you hand the mic
right there, thank you.
- Hi, so I know there's
a lot of critics who say
kind of ask the purpose
of this research,
so I kind of want to ask
what would be a rebuttal
to people who say
what's the point of giving
more funding to research
like this as opposed
to maybe like
climate change or education?
- So,
when Einstein formulated his
theory of general relativity
rewriting the laws of gravity
we certainly did not
think our GPS devices
would need it to run, right?
Our GPS devices continually
correct to Einstein time delay.
Otherwise, they would very
quickly become futile,
and, you know, like GPS
has changed our lives.
Everybody can find
their way now.
When people worked on
coherent light sources
that then became lasers
it was a purely
theoretical study.
Not one person thought I
might have eye surgery one day
using these lasers.
No, it was a purely theoretical
expedition, you know,
it was like how
does light behave,
how does it become
coherent, et cetera,
but having said that,
and I can give you many
more examples of Teflon,
of this, of that, I
mean, it's just so many
unintended consequences
of basic science.
It happens all the time.
That's not the right answer.
That's not why I do it.
I think we do it because we
are curious as human beings,
and we do it because it
brings meaning to our lives
to understand the
world that we live in,
the universe that we live in.
We create art,
we explore, we do philosophy,
so I think scientific
exploration
is just a basic human need.
Even though I could give
you that answer about
there are so many
unintended consequences,
and benefits and
spinoffs and whatever
that is not for a
single day why we do it.
- Great, now to hand the mic.
Why don't you ask
a question first,
and we'll hand the mic
back, go ahead, yeah.
- So what do you think finally
getting direct evidence
like a picture of a black hole
would contribute to
the field of science?
- I can sleep after that.
(laughter)
I think it will just
be a feat, right?
To look at something
that far away
to make a specific
prediction about
what its properties should be
that there should really
be a hole in the sky
among the light surrounding it
because gravity is so strong,
and there really is
an event horizon,
like there is an
information loss,
there is light and matter
and stuff crossing it,
and disappearing from
the observable universe
that like there's a
point of no return.
I think it's going
to be amazing,
but really at the end I
was half joking at the talk
like what if Einstein
is not right?
Actually, I mean, that would
be a very exciting possibility.
What if there is,
and I don't mean like the
experiment doesn't work,
the experiment works,
and what we see is not
exactly what we predict
that there is a
deviation from it,
and we have to now
revise Einstein's theory,
and maybe give us clues
about how we can marry it
with quantum mechanics,
I mean, the possibilities
are endless, so,
but it's just curiosity really.
- Do you want to hand
the mic back, thanks.
- Okay, after having to organize
so many star parties at schools,
and being dependent on weather
what are the logistics
behind you getting these five
days worth of data in these
places across the world?
How did you guys plan that?
Do you have dedicated scopes,
or you just had a certain
amount of time, or?
- Thank you for
asking that question.
That is one of the major
challenges of this experiment,
so one thing is getting
the telescopes everywhere,
and the other thing is
coordinating the observations.
So we have historical
data on what the weather
on different sites are like,
so we chose the time of
year that optimized that.
So we said, okay, end of March
to end of April time period
tends to be good weather
in all of our locations.
South Pole is
always good weather.
Chile the Atacama Desert is
almost always good weather
like very high, very dry,
and just usually good
part of the world.
Tucson, as you know, Mount
Graham has variable weather.
Our LMT telescope in Mexico
has variable weather.
The Alps have variable, I mean,
so there we just
relied on historical
data to find a window.
A lot of them are
dedicated telescopes.
Not dedicated to this
project, but at least work on,
hey, we need the telescope
from this day to this day,
can you make it available basis.
One telescope that is
not like that is ALMA.
It is a heavily
oversubscribed huge telescope
that researchers around
the world want to use.
So for that one we
actually write proposals.
They get peer reviewed,
we get the time,
and then we say we'll
give you a 10 day window,
and then we'll trigger
or not trigger.
Then a bunch of us
sit in a control room
like a lot of my colleagues
are at telescopes
actually doing the observations,
and a bunch of us
sit in a control room
getting real time data.
Sometimes, the telescope
will have a problem
like the tracker
won't work properly,
or one of the disks failed,
or weather it was
too windy to point,
like we couldn't stably point
because the wind on one of
our sites was so strong,
but every night, in fact,
like around three p.m.
we sat down we collected
the data from all the sites,
and we said, "Does
it look good enough?"
Like we called it a
go or no-go decision.
In 2017 we had go
decisions back to back.
In 2018 we had a lot
of no-go decisions
because the weather just
wasn't as good, so, yeah.
- [Woman] So your five
days or nights of data
they're not consecutive,
they're over a certain
period of time, or?
- In 2017, four are consecutive
the fifth one is
three days later.
In 2018, we, again, were able
to observe for nearly a week,
but it was in bits and pieces,
and not every observation
involved all the telescopes,
so we said, "Okay, we
don't have this one,
"but let's do it anyway."
- Just as a follow-up here
before we go to another question
what is the nature of this
data that you're evaluating
that comes in, I
mean, what does it...
I mean, is it
numbers, is it images,
or what are you actually
making a judgment call on?
- So the raw data,
literally is a recording
of every wavefront,
so electromagnet waves
as you know, I mean,
have the sinusoidal feature.
Whether this is millimeter
waves or X-rays,
X-rays, okay, we count
photons, but in radio.
It's just ups and downs
of a sinusoidal wave,
and we record it.
The reason we generate
so much data is because
there are 10 to the nine, a
billion cycles every second,
so when you calculate
the frequency
corresponding to that wavelength
for the speed of light
it is a billion cycles,
so every second we have
to record a billion
of those cycles,
so why do we do that?
When you record it so faithfully
so you can have individual
waveforms from one telescope,
and individual waveforms
from the other telescope
because they're at
different positions on earth
light arrived at them at
slightly different times
so there's a time delay,
you match them up.
You basically search on this
wave train and this wave train
on a supercomputer
how much do I need
to shift it by
so they completely match up.
That's what this interferometry
technique relies on,
or synthesis relies on.
- So it's an actual
visual evaluation of data
sort of like you said
the wave formation
that's forming at
some resolution, yeah.
- Of light at a millimeter
wavelength coming in,
and all the waveforms
being recorded
in each of the locations,
and that gives you I think
of it as if it were music
each pair of telescopes
would give you one note,
so you want so many
different pairs
that you hear all
the different notes,
and you put the music
together from it,
and image is very much like it.
So each pair of
telescopes will give you
one component of the image,
and then we put
all of it together,
and that synthesis of data
is the full image then.
- Interesting, Sandra, do
you have the mic, yeah?
- Yeah, so I'm going to
go back a little bit.
In this lecture and
your previous one
you talked a lot about
your excitement of failure,
and talking about how it's
a really positive thing.
So how do we as middle school
and high school teachers
instill that in
our students, too,
that science is a lot
of part of failure
without increasing that doubt
within the field of science
how do we get students to see
that failure is really
necessary in that field
without casting more shadows
that we often see in like
current media in the
field of science?
- Yeah, I think we should
honesty talk about
the uncertainty,
and our desire to
quantify that uncertainty,
and to design
experiments to reduce it.
It's one thing if you
design the experiment
it works as expected and
there is a negative result,
so I think we should just
say that is valuable, too,
that science moves forward
when you have experiments
that give you negative
and positive results.
In the field of
medicine, for example,
there is a huge problem
that scientists don't
publish negative results,
so it biases like it
actually makes you think
the result is
different than it is.
We publish negative results
as much as possible.
There isn't a stigma
attached to it,
but, ultimately, I think,
just being honest about
this is how science works.
We are not after dogmas.
This is an experimental field,
and just be smart about how
you're designing the experiment
so you can get an
answer whichever way
the dice fall, yeah.
- Okay, we got a
lot of questions.
Let's go over here first,
and we'll come back.
Hand it to to Sarah,
and then we'll kind of,
we'll just transition, go ahead.
- I had a quick question.
You mentioned information
being lost in the black hole,
and I'd read about there
was some sort of debate
between information being lost
versus information
being preserved.
What exactly is meant by
information when this is said?
- Information is anything.
So the simplest way
to understand this is
if you take a lump of coal
versus an encyclopedia,
and throw it into a black hole
there is no way to
reconstruct from any signal,
any type of info,
like any observation that
you do after the fact
of being able to tell whether
it was a lump of coal,
or an encyclopedia,
so, I mean,
encyclopedia, of course,
here is the representation
of all information,
but you lose
any knowledge of what
fell into the black hole.
It just becomes that
singularity, that
energy, that mass.
Event horizons do indicate
an information loss.
Even then there are some
versions of string theory,
which we can't test right now,
but we are certainly
trying to understand,
and trying to find where
it meets astrophysics.
Let's say information
gets stored effectively
what you would call the
skin of the black hole.
I don't, I mean,
there would have to be
certain predictions of that
that differ from
information as being lost,
and based on those predictions
then we would know what
observations to do, yeah.
- Okay, let's hand the mic over,
and we'll come back over here.
Let's go first to Kat, and
then we'll come back over.
Is the mic over here somewhere?
Yeah, okay, you got it,
you're next, go ahead, Kat.
- So the title like dark
that goes with dark
energy and dark matter
does that refer to it
being actually dark
as in the absence of light,
or more that we're in the dark
about what it actually is?
- Very nice question.
In dark matter it actually
refers to matter being dark
as in the absence of light
that it does not
interact with light.
It doesn't emit it,
it doesn't absorb it.
It doesn't have any
electromagnetic interaction.
However, I mean, even
there you could say
part of the pun is that we are
in the dark about what it is
because if it's made up of
particles that we've never seen,
and we don't know the nature,
like we don't know what is
the mass of dark matter?
I don't know.
How was it formed is
it super symmetric?
Was it formed in
the early universe?
I don't know, so, I mean, yes,
there is also a lot of that.
With dark energy
I would say it primarily refers
to we don't know the nature.
I mean, energy doesn't
emit light anyway.
It's just a completely
different form of energy
that is repulsive that
causes the universe to
expand faster and faster,
so there it's far
less about light,
and more about I don't know.
- We'll go over
here first, yeah.
- I really loved how
your talk is grounded
in the basic rules
the foundational concepts
of physics in our world.
I guess you're saying
how it helps you
interpret what we see.
So conservation of
matter and energy
maybe the name black hole
makes me think of a hole
that something goes into.
I think you maybe
answered it a little bit.
Maybe this information
goes to the skin of it,
but I was wondering
if you picture it,
if you actually find
this event horizon
do you then begin looking for
where this matter
and energy goes?
Are you looking for some
black fountain someplace
where this energy goes, or?
- So as far as conservation
of just mass and energy
forming a black hole
doesn't violate it.
You take whatever matter
there is you throw it in there
it adds to the mass
of the black hole,
so you're not losing it.
So there is conservation
in that sense,
but it is going to a place
where it's destroyed from
the rest of the universe,
so you're losing...
Like losing information
means all our laws of physics
if I just change the sign it
would go the other way, right?
So I mean I can have
interactions that
produce something.
I can have interactions
that combine the same thing
like in particle physics.
I can have interactions that
make things move one way.
If I reverse time it
will go the other way.
You get to a point where
you don't violate mass,
and energy conservation,
but you certainly violate
the reversibility of
your physical laws.
You can't say, oh,
now the black hole
is going to spew things back out
if I just change the
direction of time,
so, yeah, that breaks.
- Let's go over here and
then hand that mic up.
Yeah, go ahead.
- So you mentioned
like the reversibility
of the physical laws,
and I was wondering
if you think that
(mumbles) takes away from the
reliability of these laws,
or if it's kind of irrelevant?
- I think it's a very
basic feature of our laws.
I think back in Newton's times
we built laws one at a
time by experimenting,
and trying to fit
an amount of data whatever it
might be, planetary motions,
or how things fall to
the ground, or whatever.
Now we approach
physics from almost
a more philosophical
point of view
like we first put
down some symmetries
that we want our laws to obey,
time reversal being one of them,
and we say, okay, how can
I formulate an equation
that certainly has
desired properties as
far as nature goes,
but above and beyond that
how does it mesh with other
things I know about nature,
so I think it's an
attractive feature.
- Okay, your turn, go ahead.
- During your talk you showed
six different predictions
about what the event horizon
of a black hole might look like.
What were the differences
that we looked at
in each one of those
six predictions,
and what was looked
at specifically
for the University of
Arizona's prediction and movie?
- Very good question.
So there are things we
understand quite well
about black hole environments
if they are truly black holes,
and there are things that
we can't quite model.
So we know that a
lot of the matter
that ends up falling
into a black hole
comes from nearby stars.
They lose mass,
there's like winds of
mass leaving from stars.
They come near the black hole,
they have angular momentum.
They settle into
some sort of a disk
it's like a spiraling
inward motion.
We know the basics
of how that works,
but we don't actually
know, for example,
en route to the black hole
what temperatures
they heat up to.
We can have for those of you
who have taken thermodynamics
we can make some arguments
about what those would do,
what temperature
would they get to.
Some basic energetics arguments,
but there are lot
of subtleties to it.
There's a magnetic field there.
How does that affect things?
When the gas is very dense
how does that behave?
When it's very rarefied
how does that behave?
So there we have to resort
to our best guesses.
Those were meant to
be a gallery of both
different groups
working on this problem.
How does gas fall
into a black hole?
How does it shine
in the meantime?
What temperature does it reach?
Each group builds a
slightly different model
in order to explore the
unknown aspect of it.
If we put all our
money in one basket,
and design an
experiment around it
we can be surprised
in an unpleasant way,
but if you at least say
this is what I understand.
This is what I don't
know very well,
but I'm just going
to keep on exploring
among these possibilities if
there are any showstoppers.
So that's what we did there.
- All right, let's go
here, Chris, go ahead.
- So this might be like kind
of like a little fictional,
or Star Trekkie in a way,
but what kind of prospects
do you see like black holes
being served as in
like space travel
because there's a lot of
like theories out there
that it could be
like a wormhole,
and that like you could
do things with that.
How much merit do you
think those theories hold?
- Not very much,
sadly.
There are mathematical
solutions to general relativity
that probably don't
play out in nature.
The simplest equivalent
of that would be
like solving a
mathematical equation
you get an imaginary number,
you get a negative number,
and you say, oh, well, I'm
just counting apples here.
It can't be negative.
So general relatively equations
have solutions like that, too.
Most likely, I mean, for
example, time loops, right?
They're allowed,
they're logical.
A lot of the Star Trekkie
things that we see
about black holes
are those most likely
not applicable to
nature solutions.
- But time loops would
make for good sci-fi.
- I mean, it does,
right, it does, yeah.
- That's good stuff right there.
- Yes, you go kill your
father kind of thing.
- Yeah, whose got the
mic over on this side?
Okay, Sophia, why
don't you go there,
and then we'll
hand the mic back.
We got a lot, go ahead, Sophia.
- Okay.
Quite often
throughout elementary,
middle, high school, college
we're told that the
universe is expanding,
but as far as I'm aware
we have no concept
of the bounds of the universe,
or how far it extends
or how large it is,
so how can we measure
how a substance,
or phenomena is expanding
if we don't know how big or
small it was to begin with,
or where it's limits are?
- Okay, that's a good question.
So imagine a balloon,
and imagine when
the balloon is small
putting dots on it, okay?
So dots separate it by some
distance on that balloon.
Now start blowing up
the balloon, okay?
Every point on the
surface of that balloon
is moving away from
every other point,
so the stickers that you put
on the balloon initially,
these two are farther apart,
these two are farther apart,
these two are farther apart.
So when we say the universe is
expanding we mean the fabric.
The fabric of
space-time between them
is literally stretching out.
Now if I had a full balloon,
and I could look at
it from the outside
I would see that it's
expanding, right?
Every dot I put at the beginning
is moving away from
every other dot,
but even if I couldn't
see the whole balloon,
even if I had just
the subset of the data
I could still see the dots are
moving away from one another,
so when we look at galaxies
in the observable universe,
which is not the entire
universe, I mean,
it's just what we can observe,
how much light has traveled
during the age of the universe.
Every galaxy, like
not every galaxy,
of course, there are
close pairs of galaxies
that are not being ripped apart,
but galaxies are moving
away from each other,
so even with that kind
of data you can tell.
You don't know
where it was before,
but you know they are moving
away from one another.
- Is there potential
that even though
everything is moving
away from each other
if we could zoom out a whole
lot and see the entire universe
that the physical size of the
whole thing wouldn't change?
- I think what we
mean by physical size
is a little bit different.
So it's not that the sizes
of galaxies are changing,
but the time it
takes for the light
to go from one galaxy to
the other is changing.
It's just becoming
longer and longer.
In our future we will
remain close with Andromeda,
but probably we
will get to a point
where we won't see
any other galaxy
because it will be just too
far away for light to reach us
within a universe time,
which is a sad thought.
We'll be so lonely.
- Hand the mic back
I want to give Eric
a chance at the back,
and we'll work back up front.
Just as that mic is
being handed back
I want to just follow-up
on a question here.
Am I correct in my thinking here
that in that
balloon analogy then
no matter what point
you are in the balloon
you are the center sort of?
You have the feeling of being
at the center of the expansion
is that how that goes?
So from our perspective we
see everything expanding up,
but from every other
perspective it's?
- Sure, exactly,
sure, yeah, I mean,
the balloon analogy
is a little limited
because it is intrinsically
two dimensional, right?
Like I'm describing a
surface rather than a volume,
but it is true, I mean, from
every point in the universe
you see things
moving away from you,
so from that point of view
that analogy is successful,
and you're interpreting
it correctly.
- Okay, all right.
- So, black holes, you
know, we love them,
and we want them to like take
things somewhere or whatever,
but as they add stuff
they get more massive,
so they're collecting the
stuff they were made out of,
and now they're sucking up.
Now you learn about matter how
it's almost all nothingness,
so can you packet, I mean,
they talk about a singularity.
Is it a singularity
like an actual no space,
or is it just so much
energy that it can actually
take all of that nothingness,
and take the stuff
in the nothingness,
and pack it into
some tiny space?
I mean, is that even a question?
- I don't know, I mean,
when we say singularity
we mean the former.
It literally occupies
no volume at all.
It is infinitely condensed
just like the big bang was
at the beginning
of the universe.
All that energy and mass
is condensed in a form
that we don't know we
wouldn't be familiar with
into an infinitesimally
small space,
so it's not small it is infinite
like it just shrinks to nothing,
although that energy
and mass is there.
Is that true or does it actually
turn into something else
that stops that collapse?
I don't, I mean,
one of the reasons
for looking for horizons
is that, I mean,
a singularity behaves different
than alternatives to it.
- [John] Yeah, go
ahead, right there.
- So in your lecture you
touched briefly upon the idea
of the gravity
around a singularity
warping the space-time continuum
I was wondering if you could
go more into detail about that?
- So every object with a mass
warps the space-time
continuum around it.
It's not measurable,
but our bodies warp the
space-time around it.
The earth certainly warps
the space-time around it.
I mean, that's why we need
to do GPS corrections, right?
Like we need to generally
to see corrections
to the GPS signals
from satellites that
are orbiting the earth.
The sun warps the
space-time around it
in a pretty profound way.
You see the positions
of the stars shifting
during a solar eclipse when
the sun is in front of you,
and you can see the
star through that mass
versus when the sun is
in the other hemisphere,
and you see the stars directly,
so these are all
measurable effects
except for the warp that our
bodies cause, for example,
or like a small object causes.
In a singularity it
just becomes extreme.
It warps it so much that
there is a volume in which
all paths are pointed inward.
So around the sun the paths are,
the trajectories of
matter and light,
and starlight
behind it, whatever,
they're bent,
but they're not bent so
much that they turn inwards.
Around the singularity
they are bent so much
that they turn inward so
they're trapped there.
So that's the difference
between those cases.
I don't know if that
helps with the question.
- [Man] Can you do a little
bit more about the time aspect
of the effect of the
gravitational force as well?
- It is going to
be quite technical
for this conversation, though.
So, right at the
horizon, actually,
what we call the space cord,
and then the time
cord and it's flipped.
That's why all
trajectories point inward.
We can separately have
a space direction like I'm
walking towards John here,
and I can have a time direction
like time is running
towards tomorrow,
or like I have control
over my direction as
a function of time.
At the horizon I don't anymore.
I mean, there's a flip in
the equations that basically
points to a direction
as if that is the direction
that time is flowing in,
but without doing the math
it's a little bit abstract
so describe it that way.
- You couldn't
verbalize that by saying
that the analogy you just used,
like, okay, you're
walking towards me,
and there's a time that
just feels like it's going
regardless of whether
you're walking towards me,
so the opposite would be?
- I'm dragged with the current.
- You're controlling the
time, and the space is just...
Yeah, you're just you
can't do anything about it.
- Yeah, yeah, yeah, I mean it's
like if the current is mild
I can swim across it, maybe
I can swim against it,
but it's a waterfall.
If you're caught in a waterfall
your future direction
is pretty set, right?
I mean, this is
going to be downhill,
so that's the closest analogy
we usually come up with
like a river or running water
or something like that, yeah.
- Yeah, let's go
over here, Larry.
- So I had a educator question,
and you've handled some
of these really well,
but how do you get
to some of the wonder
that science inspires
without getting into too
much of the woo about it?
Just thinking
about the other day
when we had a lunar eclipse
you couldn't read
about it in the news
without seeing the words
wolf and blood in there.
- Right.
- Gravitational lensing,
if we had a solar
eclipse a few years ago
I didn't hear a single
peep of anybody saying,
oh, check out the
positions of these stars.
- Yeah, yeah.
I don't know why we
water it down so much.
I mean, it is fascinating.
We don't have to talk
about every detail,
but the discovery aspect of it
is really fascinating, right?
I mean, like we don't hear
how often do solar
eclipses happen.
Like what is the geometry of
the sun, earth, moon system
that causes these eclipses
to happen and how often.
Like we only hear about it
it's visible from North America
like, you know,
only once every...
Until the end of 2020 it
won't be visible, whatever.
It's like that's not
the piece of information
I'm interested in, right?
I don't know, I think our
coverage of everything
has become a bit sensational,
but as science teachers I
think you have the ability
to ground it a little bit more.
I mean, yes, it is
super fun to look at it,
and just like see that disk
moving across the moon,
and it's slowly disappearing
and reappearing.
I mean, it was very
nice, but, yeah,
it wasn't like wolf and
blood and this and that,
it's just, yeah.
Yeah, I don't know.
I mean, I think you have the
ability and the media doesn't.
- Hand the mic up here to Annie,
and then we'll go over here,
and then we've got, yeah,
Morah, go ahead, Annie.
- So the discovery of black
holes is a fairly recent event.
So how much do you think
is still completely unknown
about the universe,
and do you think we can
ever discover everything?
- The discovery of black
holes dates back to the '60s.
Before that there
are theoretical
discussions about them.
It's obvious that
one of the solutions
of the equation is a black hole.
In fact, the first
solution discovered,
the short solution
is 1915, I mean,
like months after Einstein's
formulation of the theory,
but from that, I mean,
you can always dismiss it
as this is mathematical
like it's not gonna
happen in the universe.
In the '60s when we started
seeing bright quasars
that are at large distances,
then we saw that there's just
a lot of power coming out,
not from the hole
itself, of course,
but from gas being like
falling down those potentials,
and just emitting a lot of light
that's when it became a reality.
Will we ever know everything
about the universe?
Probably not.
I think we'll keep on
looking, exploring, testing,
but I don't know how you
would ever say that's it,
I know it all.
- Could you hand
the mic over here,
then we'll go to you, Morah.
- So you mentioned you're
in search of the horizon,
which is still like a
theoretical concept to this day.
So what if you're
conducting your research
do not find the horizon,
what does that mean,
and what are the
steps from there?
- So if we don't
find the horizon
the first thing that we're
going to do is try to figure out
what we may have done
wrong with the experiment.
We say we picked up
articular wavelength
where the gas should
be transparent.
Is it that it was opaque?
It's just, I mean, the horizon
is there, but it's obscured.
We'll go through possibilities
of telescopes malfunctioning,
of our theory being incomplete.
Not theory of the
black hole itself,
but everything around it like
what we were talking about.
We think we ran a whole
suite of simulations
to quantify what we don't know.
Maybe we didn't do a good job,
so we'll go through all the
mundane possibilities first.
Things malfunctioning,
our predictions
being incomplete,
our reasons why we didn't see
what we were expecting to see.
If we convince ourselves that
it's none of those things
then you're left
to consider the possibility
that the horizon is not there,
so a black hole does not have
a black hole in its image,
so then you say
what could it be?
I know that it's a
very compact object.
For example, for our
own Milky Way black hole
four million solar masses
in an orbit that's smaller
than the solar system.
I mean, what would
happen to all that mass?
You start going through
the alternatives
of what else it could be,
but, frankly, first
we're going to search for
what could have gone wrong.
- Let's go to Morah.
Pass that back to Josh, I
think he had a question, too,
and then we'll go to you
then, go ahead, Morah.
- So it seems like a lot of
physics isn't really based
in observable evidence,
so when you're doing that
kind of theoretical research
how do you even
start that process?
- I think you start
with a framework anyway.
You either start with
the framework of the data
that you've already collected
like Copernicus did,
like Kepler did, like
Newton did, or you start from
I know this theory is proven.
It makes such and
such predictions,
so it's more like thought
experiments of, okay,
if I take this now and
apply it to this situation
what would happen?
So there are methods.
I mean, you're not literally
sitting there thinking
what equation should I write?
I mean, it's not like that.
It's really an extension
of an existing framework
whether this is data
driven or symmetry driven,
or something in between.
- Josh, go ahead.
- First of all,
thank you so much.
I think you're kind of
a master of analogies,
and I think maybe that's
partly because of your field,
but, also, I think the
teachers really try hard
to create analogies all the time
to get students to
understand things,
but I think they have a very
hard time doing it themselves.
Could you speak on like kind
of the power of creating like
mental models or even
making models on boards,
or even doing these super
computing kind of models.
I think it's a really
powerful idea in education.
I find our students they'll
quickly go to a cliff,
and then just kind of give up.
- I completely agree with you.
Mental models are
very, very important.
In fact, I recently read a book,
maybe some of you have too,
Peak, like how people learn,
and it's not just in science.
The book is arguing that
we build mental models
in anything that we learn
whether this is a
golf swing, or chess.
They experiment with
memorizing numbers.
These two authors who are
neuroscience researchers,
as far as I remember, they
talk about, yeah, I mean,
how you basically
build a mental picture
of what you're studying,
what you're trying to learn,
what you're trying to develop
like how does that feel?
How does my...
I don't play golf so, I
mean, I'm making it up,
but how does my tennis
swing feel, whatever.
Certainly working with
models allows us to develop
that one step further,
and then discussing
those models in a group.
We either come up with
analogies when we're doing that,
or we come up with questions
when we're doing that.
That then stretches
our mental picture,
and then we try to add a
little bit to it by using it.
So my PhD advisor he is a
very good astrophysicist.
One of my like very vivid
memories of talking to him
when I was a student
was he would be like
imagine I'm an electron and
I'm moving through this space,
and I'm like...
So he would embed himself in
whatever the case might be
like gas swirling
around the black hole,
and he imagined he's an
electron in that gas.
We had these like really
fruitful conversations,
and slowly, of course,
through these conversations
I started developing
that mental framework,
and then I extended it,
and then with my students,
I'm developing maybe
new things, so, yeah.
Our brains are capable of that
like solving
mathematical equations
you don't see them as numbers.
You see the patterns
in that equation
because you just develop,
I think, higher and higher
frameworks.
- Zoom over to Van, we'll
go two more questions,
and I think we'll be out
of time, yeah, go ahead.
First go to Van first.
- So when observing
the event horizon
you said that like the
telescope you needed
had to be the size of earth,
and I thought that
was kind of lucky
because if it
needed to be bigger
you'd have to use satellites,
and try transfer that
data down to the surface,
which I assume would
be a difficult task,
so I was wondering does
that have to do with
like since we're on earth,
and we're trying to
observe it from here,
or is that more of just
kind of like a happenstance
that from the distance and
the resolution you wanted
that it just so kind of lines up
that it happens to
be the size of earth?
- It's the latter.
So we said, from the distance
of these black holes,
and the mass that
we know of them,
so a size for their
event horizons
what is the resolution
that we need?
It just so happened
that for the biggest five
black holes in the sky,
and by biggest I don't
mean biggest mass.
I mean, just the
right combination
of how close they are to
us and how massive they are
which is the bigger
size in the sky.
Several are reachable by
telescopes that we put on earth.
The remainder requires
a satellite in orbit,
a dish on the moon, et cetera.
So we said since there are
three or four that we can
reach the horizon scale for
it's worth building this,
and then we'll go from there.
We'll do space based
interferometry, but
exactly, I mean,
you're very, very astute
in what you described.
The data that you have
to transfer down then
what you would have to
do is crunch it onboard,
and then transfer it
there's just no way.
I mean, I'm saying we're
fedexing literal disks,
so that's not going
to be possible,
so some level of data crunching
will need to be done onboard,
and then telemetry
down to earth,
so we're not there yet,
but if we want to look at more
distant smaller black holes
then that's the
direction we'll go,
but it's serendipitous that
at least like we can do a few.
- Maybe when we get
8G, or whatever, 9G,
it won't be a problem.
I remember my dissertation
was literally on floppy disks,
and I had to carry a...
You know, now that's,
you know, so yeah.
- Yeah, yeah, I mean,
I certainly didn't
have a supercomputer.
I would wait until
everybody went home.
I mean, they knew about this.
I wasn't doing it
behind their back.
Then I would log into every
machine in the department,
and submit like pieces
of the computer model
that I wanted to run until
they came back in the morning,
and then just stop them,
collect, like get my data back.
Now, of course, we're like,
oh, here's my $7
million supercomputer.
- Oh, you were
that grad student.
- I was that grad student.
I was when are you leaving?
Can I run on your machine?
- Yeah, yeah, Gav.
- So I was wondering
what makes Arizona
such a prime candidate
for a second telescope
because wouldn't it be more
helpful to put in a place
that doesn't already have one
to help like diversify the data?
- [Feryal] Very good question.
- [John] That's
for the Kitt Peak.
- Yeah, yeah, why do
we need Kitt Peak?
So we said effectively what
we are doing with these
pairs of telescopes
scattered across the globe
is collecting different
notes of the music,
or different wavelengths of the
image that we want to build,
and even though the
longest baselines,
the longest distances
between telescopes
provide us with
the finest details,
the short distances
are also necessary.
They provide us with
the bigger picture,
so you go from, I mean,
ideally you would have
everything from Kitt Peak
to Mount Graham distance to
here to maybe New Mexico, and
then here to Mexico, here to,
so you would have this ladder
of all pairs of possible
distances to cover the earth.
That is not possible, but
Kitt Peak to Mount Graham
turns out to be super useful.
- Well, I want to thank
you for taking time
after the lecture
it's already late.
- My pleasure, this is always
a great group, thank you.
- I want to thank
everybody here for-
- For your questions.
- Great questions and we'll
back with episode three
next week with Professor
Joellen Russell.
We're gonna be shifting from
black holes to our planet.
- Yeah, what do we
know about climates,
what do we know
about our climates.
Yeah, it's gonna be fun.
- All right, thank you, and
we'll see you next week.
(applause)
