Transcript:
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and it gets so quiet yeah I think this oh my God we're live
now I don't want to say anything we're in space they can't hear you oh
yeah they can't hear you scream they can't yeah how do they know you can I
don't know you know I've seen Orion go by quite a
few times now I think I like this Loop do you like the loop it's winter time
it's coming yes it is I can't believe Christmas is what just a
little over a month away yeah and Christmas is already in the stores two months ago yeah it was in August yeah
yeah but it seems like we were just at Alcon you know it doesn't seem like it's been
that long ago that's because it was not that long ago I know
yeah the whole pandemic pandemic kind of completely distorted our sense of passage of time right yeah yeah it just
still doesn't feel normal it's all moving at weird speeds yeah yeah
it seems like everything's kind of changed a little bit you know our perceptions at least right yeah yeah
definitely
yeah they keep talking about the new normal but I don't know if it feels normal yet
exactly normal then it all changes up to something else so yeah that's right
constantly changing which is apparently good for our neurons
as we get older so that's right and that's the reason why you need to be taking lion's mane talking about her
the American lion's mane association yes
he'll have his lion mane on that's right my whole suit
oh yeah I look like The Wizard of Oz so what did you guys think of David
eicher dressed up and for the Halloween thing that was the last in the last show it was
it's kind of scary you know it was amazing and like blood dribbling out of the side
of his mouth yeah I don't know what kind of blood it was but
last year I did a public lecture on Halloween for Whipple Observatory so I
wore my Star Trek uniform so it was perfect that's cool that's cool have you Shane have you ever
been to a a Star Trek convention I have and so many what is that like what is
what is it like you know I haven't been for maybe a decade or more but you know it's kind of awesome because everyone's
kind of into it right so right meet the whole whole spectrum of people and you
kind of all love the same thing it's it's kind of like being at a star party right everyone just loves the same stuff when we talk about the same stuff and
it's right now with people who are like you are right that's cool that's cool
good to see you I want you and I walked in the restroom
and there were two Klingon women and I kid you not I went whoa and they
looked at me and said haven't you ever seen a Klingon
great must have been the best sisters that's right
we're going to share to the Austin Astronomical Society that's a great group Austin yep
they're a league club aren't they yes
and I think they're a fairly large Crow Club too well they're uh I think you're right I think
and the done for mean done done for firm line done firm line Astronomical Society
so here we go hopefully I'm not messing that up
if uh if we're lucky our power won't go out we're on the receiving end of the
storm that's coming through
at the end of 2017 a Galaxy 236 million light years away began a rare and
dramatic transformation it's an event astronomers are still puzzling over one set off by changes
near its Central black hole they first explained this as a title disruption event that's when a star
wanders so close to a supermassive black hole that it's torn apart
a new study of observations spanning the entire event suggests a different cause
the trigger may have been a flip in the magnetic field in the disk of material around the black hole
the sun's magnetic field reverses polarity every 11 years on longer time scales even Earth's magnetic field flips
starting in December 2017 the Galaxy began to brighten invisible and ultraviolet light the source of this
brightening appeared to be the disc of material around the supermassive black hole at the Galaxy Center
it peaked three months later at nearly 100 times its previous brightness
that's when regular monitoring with NASA's Swift satellite began as the visible and UV brightened x-rays from
the Galaxy dimmed by August 2018 the higher energy x-rays had disappeared
completely a few months later the high gx-rays came back even brighter than before
they returned to normal within a year these x-rays come from a cloud of super
hot particles near the black hole it's a feature called the corona which is formed by the strong magnetic field the
lack of higher energy x-rays means that this structure was essentially gone based on observations from Swift
Europe's xmn satellite and ground-based Optical and radio telescopes here's what
may have happened the visible and UV flare results when
the flow of matter into the black hole increases this may have started when the magnetic field in the disk's outer
regions began to flip the weakened magnetic field can no longer support the corona which vanishes
the flipped magnetic field gains strength restoring the X-ray Corona but the inward flow of matter is still high
so this emission is stronger than it was before the flare finally the Corona and disc return to
their States before the flare now with a flipped magnetic field
rapid changes in UV and visible light have only been observed in a few dozen
active galaxies like this one this is the first time x-rays have been
seen to drop out as other wavelengths
near an active active supermassive black hole
[Music]
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well hello everyone this is Scott Roberts from explore scientific and the explore Alliance and we are coming up on
our 22nd astronomical League live program uh with me tonight uh is of course Terry
Nann Terry is the host of astronomical League live she brings on the uh you
know the top officers from the astronomical league and we've got Carol orange and John glass with us also here
tonight and we've got David Levy and myself that have also been invited here
and the keynote speaker tonight is Shane Dr Shane Larson who did the very first
astronomical League live program so I'm going to turn this over to Terry and let
her introduce everyone and get this thing going thank you very much Scott I appreciate
it so good to see everybody again and be online it's been it seems like it's been a long time and yet
everything seems to be going by a lot faster than normal too so thank you all for attending and thank you all for
viewing we appreciate you being there for our Friday night astronomy so how
about if we start off with David Levy David it's always a pleasure to see you
here and you have been on just about every show we've ever done so thank you very much for that and how about if you
get us started well thank you so much Terry it's really
good to be here tonight and uh such and wasn't that a wonderful eclipse I think
a lot of us had clear or partially clear sky that we were able to see this beautiful beautiful event
it was pretty dark I got it as an L2 Eclipse um it wasn't the darkest Eclipse I've
seen that one would have been December the 30th 1963
when the Luminosity was absolutely zero the moon simply vanished to totality on
that darker than ever eclipse and so for my poetry tonight I'm going
to quote from uh Thomas Hardy's beautiful poem at a lunar eclipse he
wrote it in 1903 after seeing an eclipse in London in 1902 and the interesting
thing about it is that he's comparing the beauty the magnificence of a Celestial event
to the troubles that we have on the planet Earth and that I can find no
better time that it would be more appropriate than now with the war going still on in the Ukraine
and a lot of uncertainty in the world right now with covid still going on
and by the way having lost two close friends to covet in the last couple of
months I'd like to suggest that you also remain very very cautious about that
anyway here is Thomas Hardy at a lunar eclipse thy Shadow Earth from Pole to
Central sea now Steels along the moon's meet shine and even monochrome and
curving line of imperturbable serenity how shall I link such Suncast symmetry
with the torn troubled form I know as line that profile placed as a brow Divine
with continence of Mile and misery and can immense mortality but throw so a
smaller shade and Heaven's High human scheme the hemmed within the cause
implies is such the Stellar gauge of Earthly show nation of war with nation
Reigns the team Heroes and women fairer than the skies thank you very much and
back to you Terry
Tara you are muted there we go we really appreciate
um you being here and thank you again that was so nice um it's a great start to a Friday night
if you ask me so how about Cheryl if you kind of update us on what's going on in
the league here lately and uh govade thanks so much for sharing your poetry with us and I would like to say I saw
the eclipse I did not we were clouded out but uh your verse made it come alive
but and I can imagine what it was like if I had never seen one before so thank you
um to start out with on behalf of the 22 000 members of The League I would like to wish the veterans among our ranks a a
big thank you for your service to our country and we really appreciate all you've been to keep our freedom alive in
the United States beyond that we've done quite a bit going on right now we have about as Terry was
saying earlier we've put uh 2022 to rest as far as outcome now we're getting
ready for our con 2023 and we're very honored to have two
uh keynote speakers for Alcon 2023 and Baton Rouge
first one is David icker editor of astronomy magazine and the
other one is Fred espanek well-known Eclipse Chaser and the authority on all
things Eclipse so we'll have more information about that just a little bit later
the other thing that is very uh good to hear is that throughout all these uh
various weather conditions in the midwest here for example where I live we have very few
decent Skies this time of the year I was in Minneapolis a couple of weeks ago
actually it's been a little longer now been about four weeks ago time goes fast anyway we had an astronomy day up there
I helped them celebrate an astronomy day and that's one of the Rarities in the league and I'd like to remind everyone
of this we have two astronomy days one in the spring and one in the fall but we
get a lot more entries from the war in the spring however uh they did an
excellent job of putting on that uh Autumn astronomy day in Minneapolis and
you'll see more about that and the next reflection also
We are continuing to have good reports about people still out observing even with less than ideal weather conditions
so we're always thankful to hear that I know our friends in Arizona uh and David's part of the world uh you can be
more selective about when you want to observe if you choose to here in the Midwest we have to take what we can get
and it is Noah's super good but I well glad to see that we're continuing to
observe as a our group uh really is out there under the skies
that's about it for right now we will have some major announcements coming up around the first year but I'm not going
to tip my hand right now because I've I've known when one sets deadlines sometimes you have to take them back so
I'm not going to say any more about that right now but more will be revealed
okay thank you Carol we appreciate that it seems like there's always something going on somewhere and uh you know we
all seem to be busy doing different things for different offices so um I look for I know some of the stuff
that's going on but I won't tip my hat either I don't know everything so thank you very much I appreciate you being
here too and what I would like to do next is to ask the questions for tonight
and naturally I'm right at the end of my slideshow here so we're gonna go up to the top
and you can kind of see what's coming up next so um tonight the I'm gonna ask the three
questions and as you know we will I select three winners from these questions that are asked but what we
need to do it's not like the G the global star party uh tonight we will
announce the winners right after the main speakers so please when I ask the questions if you could get them win
within 20 minutes to a half hour because I will give the winners names after
Shane gets done speaking and please send your answers to secretary at
astrowleague.org and as you can see tonight three winners will win the astronomical League travel mug
and we still are not doing international shipping we still are trying to work all of that out
so as I just told you and the winner somebody from the astronomical League office will be contacting the winners
within the next few days so questions for tonight while driving
on the moon the fender on the Rover was damaged what did Apollo 7 what did the
Apollo 17 crew do to fix this Fender how did they
fix offender on Apollo 17's Rover and again send those answers to
secretary at astraleague.org and you'll notice I'm going to go slow
we had two more people contact us and say we're going through the questions too quickly so please slow down so
that's what we're going to do a little bit tonight on December 7th what part of the U.S on
December 7th part of the U.S we'll see this occultation what planet will
be agitated what kind of what planet will be part of the occultation
so December 7th part of the U.S will see this occultation of what planet
and again send your answers to secretary at asterleague.org
and the last question on November 16 2022 Mars will be in what constellation
so on November 16th 2022 Mars will be in
what constellation and again please send your answers as quickly as you can to
secretary at astrowleague.org and next up John get warmed up because I
am headed your way so uh for those of you that don't know John Goss John Goss is the one that does
these fantastic announcements for Al live he does a
great job and I really do appreciate it uh I I know it has to take quite a bit
of time but he's always there and always willing to do it so thank you very much and he is also our media officer for the
astronomical league so John I will be quiet and let you talk
alrighty um I'm not muted am I for months
okay there we go
good it's it's uh it's good good to be on and thank you for for having me thank you for inviting me
um I like to come on every now and then and say a few words and this time I will uh I have a presentation to give but I'm
going to start out with something else first and as you can see it's no this has nothing to do with the presentation
it's just an icebreaker let's see what we can do
see how much ice I can break okay
now here's your test this is not part of this of the three questions so don't get confused on this
this is me being a wise guy okay so what do we have here image of a sunspot
a negative image of a globular cluster or a section of a decaying banana peel
now I bring this up because I had this posted on the league website and we had
the most responses ever of anything on there it's such a silly thing
yeah so what is it well I recently completed the globular
cluster observing program so that the next morning you know I'm I'm All About globular clusters next
morning I'm eating my Cheerios slicing the old banana on onto the Cheerios toss the peel down and I looked down and I
said I don't believe it this is a globular cluster right in front of me a whole bunch of them so
just think about that the signs of the cosmos are all around you all the time
you just gotta look carefully enough okay enough of that now let's really get into this um
I wanted to talk about something which I just um laughingly called Astro Devo
which you might remember the band Devo from the 1980s
and they talked about uh Devolution instead of evolution so I thought okay
I'm gonna talk about my Devolution and astronomy
you know we our our hobby is such that we never know where it's going to lead
you know if you have other other Hobbies at least you know what you're going to be doing so with hours from night to
night year to year as we progress in it we never really know where we're going or where we're going to end up and I
always like to tell people you know the journey is just as important just as important as as the destination and
oftentimes or every time it's just as rewarding because you never really know what's going to come up around the bend
so we're going to look into our crystal ball here uh I happen to have one at home which I
consult all too often I'm afraid but um we're going to be looking at a few things on this idea
you know like like like most amateurs I started out small small telescope and as
time went on I got bigger and bigger telescopes I started out with a six inch dynoscope way back in 19
69 something like that and then kind of moved up is is time went on now my
largest telescope now is a 17 and a half inch dobsonian which I I like works great but you're going to kind of hear
me put things down about some of these things but I'm not really
you do some observing you get out under the stars as I was saying you never really know where your journey is going
to take you you know let this just take an example here the uh open cluster m46 I assume a lot
of you have seen it it's a nice looking cluster in the winter Sky uh in in Canis Major uh obviously it's a Messier
cluster but um you know the first time you see it you might not be expecting everything that you're actually going to
end up with in the eyepiece so you zoom in there and you're going to see you haven't have your nice cluster
of I think it's about uh three 400 stars in there actually we've got m46 but you
end up with a bonus the NGC 2438 now first time you see this and if you're
not aware what you're going to be finding you're going to look at that and go what is that I discovered something
you know but a lot of people have seen it and it is it is pretty cool so that's one illustration there of of seeing
something that you're going to be surprised with and and enjoying the journey along the way okay so you're into the hobby now you're
seeing clusters like this dimmer ones and dimmer ones and ones further away you're always looking for the dimmer and
dimmer dimmer objects which can become an obsession now use Obsession because
of the telescope people that will play on words for you so one night
with my 17 and a half inch I was going through the rehearsal II catalog trying
to earn my Herschel 2 pin from the astronomical League having already seen 400 objects in the Herschel list now I'm
tapping the 400 in the Herschel too so I'm getting kind of you know up up to here as far as as far as Jim Jim stuff
go dim galaxies but anyway I came across this
I did a quick drawing of it um I entered inadvertently stumbled across m106
I didn't realize what I looked at I was looking at it first and I thought you know that that looks so it looks just just like a M31 oh what's it obviously
it can't be M31 it's a wrong time of year one part of this guy and all that so I thought well you know here's my 17
and a half inch telescope looking at this looks pretty good
so I also had a four and a half inch reflector living in M31 now I'm flipping
back and forth and thinking gosh you know these two shirts sure look very very similar in a way and it kind of
dawned on me that here I am with big 17 and a half inch trying to get dimmer and
dimmer and dimmer to make objects look like they would through a much much smaller scope
so I realized I started thinking about this this would be my uh Devolution realization
that perhaps I was becoming just too fed up with all these other dim galaxies in
the herself too and they are and their Herschel one and on and on and on so you know I
thought well if m106 uh looks pretty good in a big scope it looks like M31 in a small scope then why
do you really need to proceed to larger and larger telescopes to see dimmer and dimmer things because they're just going
to look a little bit brighter a little bit bigger otherwise so if I if I want to see dim objects I
can stay with the easy to use small scope now I like putting that sentence in there because right now uh these
telescopes are I don't know how they're doing it but they're getting heavier and heavier every year and uh be nice to have a smaller scope
sometimes now I'm going to back off this for a little bit and and circle back on this
in about 2003 members of my astronomy club we live in Roanoke Virginia
I decided to pick out a Galaxy cluster that we could designate the big lit
cluster because that's the name of Roanoke Virginia it's a long story I'll go into it
um but okay so we picked out a cluster called Hixson Galaxy group number 68
which happens to pass right overhead in the spring skies at about 38 degrees
latitude or 38 degrees declination and because we're at 38 degrees latitude so
we decided to start calling it The Big lit cluster so that then about nine years later you
know this is not not a big deal it's not something you think about all the time so nine years later I happen to receive a copy of the
Journal of the artists and okay well on the back cover though
was a picture uh taken by one of their members of The Big Lick cluster that
nearly fell over when I saw this because you know we just kind of did it as a humorous little thing to do and we got
the the Bigler cluster so let's look at this a little bit more uh carefully that is beautiful well it's
not my picture it was my picture it would look horrible
and yes Scott the images are very appealing but what do you really see
through a large or small telescope when you look at clusters like this galaxies like this
well here's my my view through the 17 and a half when I jotted everything down real really quickly there are I don't
know half a dozen uh galaxies in there uh for some on the bright side some are
on us on on the dim side and I started thinking in relationship to this uh
uh Devolution bit uh how big of a telescope do you really need to see this
stuff so what did I do I made a mask for the front of the 17 and a half inch
stopping it down uh various uh various amounts and we're going to go through that I made a uh 11 and a quarter inch
mask now the reason why I ended up with this simply because that reduces the
magnitude uh the the limiting magnitude by one so everything's a little bit
dimmer you can still see a number of the galaxies but they're starting to disappear on us
did it again same idea now to a seven inch mask which is again
dropped the magnitude by another excuse me the eliminating magnitude by the by full amount and fewer galaxies things
are getting dimmer and I thought well you know a four inch telescope isn't
very big because you see something could you see any one of these dim galaxies so I put on the four actually four and a
half inch four and a quarter excuse me inch mask and yeah you can still see two dim galaxies there
um with us so theoretically if you had a small telescope four and a four and a quarter inch telescope you should be
able to see two of the two of these galaxies so instead of turning around and getting that 17 and a half and then
buying a 20 and then a 24 and well however big they are nowadays I thought I was thinking well you know I can still
see galaxies with a really small telescope don't know
start doing other things I won't go through everything I did the NGC 188
which I believe is the most northern open cluster in the sky it's uh it's not
extremely easy to see uh as you can see the the image on the on the left is with
a three inch mask on my 10s telescope so we look it's like using a three inch telescope all I guess is some fuzzy
blobs but when I go through the full aperture of that 10 inch it's pretty easy to see
so yeah it is it's kind of interesting to see what you can actually spot what
you can discern with the smaller you go instead of the bigger you go try to try to go smaller you can see what's going
on I'm not going out okay another thing that came up in mind was locational location
that's where you are observing makes a big difference um
uh NGC 7789 is in Cassiopeia it's a really really pretty cluster if you have
too small of a scope you aren't going to get anything out of it but this was uh I drew this with with my 10 inch telescope
and you can kind of see well you can see many many many many dim stars in this cluster
um so that's one time when you've got to have a larger telescope to see it but if I use this with my 17 and a half it may
just be just too much and you won't have that that that Stardust effect the hazy goal in the
background Stardust effect so aperture does play a big role on us
another one which I did this month in gc55 it's a
in a way I think it would be a showpiece Galaxy except for
my our area in Virginia it never Rises very high so it's never far above the Horizon so it's tough to see and it's a
big Galaxy it's like 30 minutes 30 arc Arc minutes across but you can just barely see it with a 10 inch telescope
okay with a four inch you're not going to be able to see this
one more okay eight inch telescope I think my second or third slide actually showed all my fancy telescopes I got I
have an eight inch F5 which I was lucky enough to take to Chile and do observing
there and M83 it's a great spiral galaxy it uh
I think it's like 80 uh 80 degrees altitude from from Chile from where I live no so I could actually see the
spiral nature and I was I was really thrilled really really thrilled with that
now you may have noticed I have a lot of drawings in here because I I really want to
um promote the astronomic league sketching program um astrophotographs are great but
astrophotographs are something that you're not really going to see what you're going to see is something going to be
I I don't want to say disappointing but if that's what you're expecting to see yeah you're going to be disappointed but you're going to see how things truly
appear uh through an eyepiece with your own eyes and you use sketching to to try
to capture this I always found that to be very very very very good thank you
and I'm going to leave you with one more um instance here you know that we've all
looked at the Double cluster in Perseus it's really pretty we have a big telescoping look no it's going to be
spread out way too much you aren't going to see you aren't going to appreciate that the cluster effect of it the
diamonds on the Black Velvet so with a four and a half inch or maybe slightly
lower larger you're going to see a really really nice really nice looking um
uh subject there in the sky so here we are looking at the stars you
go out on the stars in your career in your astronomy career you're always going to want something
bigger you're going to want something bigger and you're going to want something bigger and then you just might realize you know that the dimmer objects
in large telescopes uh look like the brighter objects in small telescope so why would you want to spend all your
time on that large telescope where you can haul out that little one and see this really great stuff and sketching not imagery records what you really see
so the next time you go out try try to keep keep these perspectives in mind that some objects you certainly got to
have a big telescope but not all of them you can really appreciate the heavens with with the small stuff I'd say
um 80 of my time outside I really just have a pair of binoculars or my smallest
telescope with me um it's I find it enjoyable you know it's not so stressful it's it's just a
lot of fun so I'm not happy note I'll turn things back over to Terry and we can get the show on the road thank you
Terry well thank you John that is really I
like seeing all the drawings I cannot draw so you know as far as if I was doing a program I think I'm like a lot
of people I get kind of you know I can't really draw if I drew a circle you might
be able to tell a circle but I'm really not an artist in that sense so uh but it
is interesting to see it because I've seen some excellent drawings from a lot of people that do sketching on all the
different programs so thank you it's nice to see that and it's nice to know you don't have to be an artist actually
to do this you know even if you can't draw do the best you can well just just
remember to tell everybody that it's supposed to look like that there you ago because most people probably would look
like mine would look so okay well thank you very much John I appreciate you
being here thank you all right Shane we're actually going to go to you pretty
quickly here so let me do an introduction to who Shane is as Scott
mentioned Shane did our very first astronomical League live he was our very
first speaker and he is an excellent speaker so I wanted to have him back we haven't seen him in a long time that was
on December 5th of 2020 that you were our first one I have not remembered that
so yeah thanks for having me that long so I wanted to have you back again and
we do appreciate you being back so much so Shane Larson is a research associate
professor of physics at Northwestern University where he is the associate
director of Sierra Center of interdisciplinary exploration and
research in astrophysics he works in the field of gravitational wave astrophysics
specializing in the studies of compact stars binaries and galaxies he works in
gravitational wave astronomy with both ground-based ligo Pro with both the lag
ground-based ligo project and the future space based Observatory Lisa he was
formerly a tenure associate professor of physics at the Utah State University he
is an award-winning teacher and a fellow of the American astrophysical I'm sorry
American physical Society he's an avid amateur astronomer I can vouch for that
Greenback yeah you do some amazing stuff uh he is an avid amateur astronomer
observing with two homemade dobsonians a 12 and a half inch named Equinox and a
22-inch named Cosmos Mariner he contributes regularly to public
Science Blog at science write sciencewordpress.com and tweets with a
handle at space Jedi Star Wars I was gonna say we're talking about Star Trek
there's Star Wars I love the title of his talk it is monsters in the cosmic
sea black hole Tales from the edge of space that is so cool so Shane thank you
again and I will let you take it from here okay thank you Terry uh yeah I do
want to thank Terry and the folks at the astronomical league and Scott and the folks at explore scientific for inviting
me back um I am a professional as well as an amateur astronomer and so there's
something that's very near and dear to my heart about coming and talking to people who are enthused about the
science I do professionally about the things they're very near and dear to my heart so I do appreciate the invitation
it's great to be back um and so tonight is Terry said I'm going to tell you about black holes so
let me go ahead and share a few slides I will say that uh you know I got into
this business into the professional business because I wanted to study black holes so when I went to get my doctorate
it was because I wanted to study black holes and I'm very fortunate that during my career black holes have gone from
being less well understood to being kind of Mainstay pieces of modern astrophysics
and uh particularly with the Advent of gravitational wave astronomy which I talked about last time but I'll also
mention again here at the end they are increasingly becoming objects that we can actually collect data on and observe
and kind of learn about what their fundamental properties and what their nature is all about
now as you might imagine I could talk about this every night for an hour for a
year and we would never get to all the things that we could talk about about black holes so what I want to do tonight
um lots of you probably know some stuff about black holes I'm going to go through some stuff that almost certainly
um you know or you've heard maybe I'll tell you some things that you don't know about we'll talk a little bit about the
history but really what I want to do is lay some foundations for you to be able
to go and do some more learning about this on your own okay now invariably
you'll get to the end and you know two weeks from now long after this talk is done you'll have some questions I put my
email address there I do that at every public lecture I give it's there for a reason if you email me I will do my best
to help you find something to help you learn about whatever it is your question might have been there's a link to my
blog I write a lot about black holes there as you might imagine I write a lot about astronomy it is meant to be a
public Science Blog as I tell folks it's written so my mom knows what I do okay so hopefully you can find some stuff
there that you may also enjoy okay and there's my social media links um as well
so we're going to talk about black holes we really have to start with this question
um especially among amateur astronomers we've all kind of been exposed to the idea of black holes and we probably have
an idea in our head about what black holes are but it's really important very often I think to very definitively say
in clear language what we mean when we say this phrase so we know what we're talking about and one of the things that
I often find is that people are bashful about the things that they know about
black holes because they've learned them from science fiction or movies and not
from professors and astronomy books okay but the truth is even though uh our
colleague Neil deGrasse Tyson uh roundly uh dislikes this movie right lots of us
learned about black holes from the very first time watching this movie I certainly did right and one of the
things that I love about science fiction in particular is for all the things that we as scientists complain about out when
we watch science fiction or scientists like to complain about very often there are kernels of Truth and those kernels
of truth I find to be excellent places to have conversations and uh people can
say I saw this in the movie is it real is it not real and that provides an opportunity to talk about what we know
or what we don't know or what scientists think or don't think about all these exotic phenomena that build the universe
and black holes are certainly one of them and for everything that people dislike about this movie I will say
there are elements of the description of black holes in this movie that I think
are spot on and we should take it face value because even today decades after this movie was made they are close to
true or at least close enough to true for folks like me and you to have an intelligent conversation about them okay
so as we go along kind of keep all the stuff you know in your mind and think about the touchstones the places where
it overlays with the things I'm going to tell you and and and ways that uh it made sense or it got things right in
ways that it didn't make sense or maybe movies got things wrong okay so
what is a black hole I'm in the very simply Define a black hole to be and if
we were all in the same room together I'd let the audience do this for you but I'm gonna do it here
um is I'm gonna make a very short and concise definition okay and the short and concise definition is not meant to
capture all the properties and all the things that black holes can do and whatnot right but it's supposed to
capture the essential thing that makes a black hole different from everything else in the universe okay and that
essential thing is a black hole is an object whose gravity is so strong not
even light can escape okay and if we start from that definition everything that we as
astrophysicists think about black holes can follow okay now if you ask people
who thought of this idea you will often get the Albert Einstein's name coming up
but in fact the idea of a black hole is far far older than that the very first person to propose the idea of a black
hole was an angling getting priest named John Mitchell in 1783. so this is kind
of a hundred-ish so years or so after Newton's publication of the principia
and after uh in the principia Newton wrote down the very first mathematical
description of gravity and what Mitchell did was he asked
how strong would gravity have to be what kind of object could create gravity so
strong that this definition I've written up here at the top of the slide is true that light could not escape from it
now at that time they had no preconceived notions about the speed of light other than it was fast okay so he
was just using the speed of light as some fast speed to try and compute what an object with enormous gravity had to
look like and what's remarkable about Mitchell's derivation is that it corresponds exactly today to what we
call the schwarzshield radius of a black hole okay and there's there's deep reasons for that because general
relativity the modern way we think about gravity is not that different in fact it
contains Newtonian Gravity the way Newton wrote down gravity in the principia
so if Mitchell first thought of this then what did Einstein add well what Einstein added was actually special
relativity the idea that there's actually an ultimate speed limit in the
universe if you can't travel faster than the speed of light and a black hole is
an object whose gravity is so strong not even light can escape then the thing Einstein added to this
whole picture is that if you go into a black hole you're never gonna get out
okay so that's the addition and that's the thing that really to our common
sense right our everyday experience that we have with baseballs and Volkswagens and telescopes right that idea that you
can't get out is the part that kind of is a stumbling block mentally very often because we don't really experience such
absolute statements in our everyday life but the laws of physics as we understand them suggest that this is the case okay
and indeed everything that we've observed and discovered and know about black holes today points to the fact
that this is still the defining character okay so my goal here at the beginning for the
kind of first you know third of this talk is to convince you of this fact black holes are actually simple now on
the surface that sounds like a Bonkers thing to say right I went and got a doctorate studying black holes how can
this statement be true but when I say this I mean something very specific okay
and you you can understand this if you just go down to your local supermarket
or your local bookstore you will find lots of magazines that look like this okay car magazines that tell you all
kinds of things about cars okay everything you need to know tars you
know tires engines paint jobs upholstery horse powers all those things about cars
okay and the reason there are so many magazines about cars is because cars are
complicated if I took a simple car like this Hugo right here and I wanted to
describe bit I would have to describe about 20
000 different parts what their shape is what they're made of
what kind of strain and force they can endure how hot can they get where do they go on the car how do they interact
and touch and attach to other parts a car is a really complicated object and
that's why you see tons of magazines about cars what you don't see at the
bookstore are magazines like this because contrary to the idea that cars
are complicated black holes are not they're actually really simple and using
the same analogy that I use with the car the reason we think black holes are
simple is because it only takes three numbers to describe them
okay if I tell you these three numbers together with the laws of physics that's the complicated part but with these
three numbers you can discover no write down everything you need to know about a
black hole and those three numbers are the mass the spin and the electric
charge masses how much stuff is there what's the stuff creating the gravity that the
black hole exerts spin is how fast it goes around like merry-go-rounds or
tires or whatever and electric charges you know the stuff you get out of the light socket when you stick a fork in it
okay so these three things are all properties that the black hole could
have and if I tell you these three numbers I can use relativity general relativity to
write down how a black hole interacts with the universe okay
so let's talk about the most important of those okay which is the mass okay
because the mass is the thing that defines the gravity of the black hole really okay and gravity is what the game
is all about from our definition of black holes at the beginning okay so black holes aren't solid objects right
they're not like a star or a planet or Lego bricks or anything that you might be able to pick up in the normal World
they don't have surfaces okay there is an outer layer to the black hole that we
call the Event Horizon but it's a it's an invisible barrier that you can walk
through and not even though you walk through it black holes aren't solid and so if that's the case the question
becomes what do I mean by mass if it doesn't have a solid surface that I can
lay my hands on and then grab and somehow measure what do I mean by the
amount of stuff in the black hole well I often remind people that we talk
about the mass of the Sun all the time but no person has ever gone up to the
sun grabbed it and thrown it on a bathroom scale to measure its mass okay
it's far outside our ability to do that but it's not practical in any sense of the word any astronomical object you
can't measure the mass of at least not in the conventional sense that you and I think of putting things on bathroom
scales okay so how do we measure the mass of objects in outer space well the
typically way we we do that is we use the laws of physics I watch for things
that I know of in the case of the sun maybe planets or maybe spaceships that we've sent to investigate the sun we
watch them orbit around the Sun and if I know the laws of physics in particular
Kepler's laws of orbital motion I can just use a stopwatch to time how long it
takes the object to complete its orbit and compute the required Mass which is equivalent to
saying the required gravity to make that object move in the orbit that I see
and so we can do the exact same thing with black holes if I were to just replace the black hole for the sun in
this image then I can measure the mass of the black hole by looking at at the orbits of
things going around the black hole okay and this lesson is Central to the way we
have to study black holes the way we study black holes until very recently is
we watch black holes doing things to other things in the universe and we'll come back to that in a moment okay but
when we talk about Mass this is what we're talking about how much mass would it take to create the orbits that we see
around the black hole okay now I can imagine these things all I want
John Mitchell originally wrote them down as an exercise in theoretical physics
Einstein you know in general relativity as well they wrote down the idea of
black holes long before we had ever detected one in the universe but if we want to be astronomers right if we don't
want to just be mathematicians of physics if we want to be observers of
physics then we have to look for these things out in the universe and so the question becomes what do we do well
there's a lot of different starting points you could take but as astronomers one of the things I often think the
right place to start is is to imagine well how is the universe going to make black holes if these things do exist and
I can figure out some way by which the universe makes black holes then that might tell me where to go look
okay now there's a whole bunch of this story I'm not going to tell you but really the thing that you need to do is
you have to unleash tremendous amounts of energy in order to make an object's
gravity so strong that it can become a black hole and the only way that we
really know how to do this or traditionally know how to do this is we can blow up Stars
now as amateur astronomers we are used to this we've often go out and in our long lists of observing things that we
get to see there are things called Supernova remnants and so there's a long list of them I could show you but a
particular favorite one of mine is found off the wing of cygnus so if you go off
the wing of cygnus there there's a naked eye star that the telrad circle is on right there called 52 Sydney and if you
Center on that star you will see one side of what is known as the cygnus loop
okay so the star in that uh image is this one right here that's 52 Sydney up
here that's part of this is sometimes called the veil nebula the eastern and western Veil this part is sometimes
called the uh the witches broom and The Far Side is sometimes called the veil but the whole complex is called the veil
nebula now this is the remains of a star that exploded
estimates suggest it was about 10 to 20 000 years ago and now all of these
shattered remnants of what the star used to be are found in the night sky but
when the star explodes it throws all of its stuff out into the universe but it's
heart its core gets left behind and that Stellar skeleton is the thing that we're
looking for at the beginning of our search for black holes now we've we've
looked for years and years and years for the the Stellar skeleton at the heart of the cygnus loop we we've never found it
there are other Supernova remnants where we have the Crab Nebula is is probably the prime example there but I like the
veil nebula that's why I showed you this one so okay so what does that Stellar core look like so um you know if I ever
give this talk locally to your Club I'll put your map of your local town here okay but I live in Chicago okay and the
Stellar remnant of a a supernova explosion takes one of two states
the less intense state is called a neutron star when the star explodes it throws off
that Remnant that Supernova Remnant and the core gets compressed down to something about the size of a city
typically about 20 kilometers across or so so if I were to hang this object this
neutron star as we call it over the city of Chicago you would see that it stretches from me up here out the
Northwestern campuses Evanston all the way down to the center of Chicago okay
this object is the size of a city but it has one and a half times the mass of the
sun take everything in our solar system the sun all the planets sweep it together
take another half a star pile it in and squeeze it down into the size of the
city and that thing you get is called a neutron star it's so dense and exotic
that normal atoms don't exist normal atoms break apart all the protons and
electrons combine to become neutrons and so more or less this whole thing is a
gigantic pile of neutrons we have a visualization of what it might
look like hanging over the city of Chicago so you can get a sense for you know typical City skyline and this
enormous uh but very small cosmological object hanging over the city of course
this couldn't really happen right because if it did you would see people in buses flying up from the streets up
towards the star because its gravity is so intense and that's really the reason I'm telling you about this before we
talk about black holes because the gravity of a neutron star is not the
gravity of a black hole but it is enormously intense so intense as to be
far outside any experience that we have here on Earth if I could stand up on top
of the Willis Tower or the Sears Tower for those of you who are old enough there okay and reach up to that neutron
star with a spoon and grab off a teaspoon sized chunk of it a sugar cube
size chunk okay the mass of that little peace would be more than three times the
mass of every man woman and child on the planet Earth
okay it's enormously dense and as a consequence the gravity is enormously
strong the gravity on the surface of the neutron star is
200 billion times more than the gravity you're feeling right
now sitting in your chair if you could if you could take a stroll
across the surface of a neutron star and you had the sad Misfortune of
encountering a cliff just one millimeter high and you fell off that cliff by the time
you reached the bottom you would be traveling at 136
000 miles per hour the gravity on the neutron star is
intense but it's still not the gravity of a black hole
if I want to make a black hole my explosion the Supernova needs to be a
little bit stronger the star has to be a little bit bigger before it blows up but it will take a proto-neutron star
something that thinks maybe I want to be a neutron star and squeeze it even harder and it will shrink down until it
was just about three and a half miles across and at that moment everything that the
star was collapses beyond that invisible barrier we mentioned that event horizon
and disappears forever hidden from View but the gravity it leaves behind is this
object that you and I call a black hole an object whose gravity is so intense
not even light can get away which means if you walk across that
event horizon barrier you're never coming back out to tell us the story
because nothing can travel faster than the speed of light
okay so that's how we make them okay and once we once we realize Wow nature could make
these things then we go looking for them okay so my wife is also an
astrophysicist and so I asked her um you know I'm going to give this talk to the astronomical League I need to
show them a picture of what a black hole looks like do you got one and she's like yeah I absolutely got one but I won't
let you show it to him unless I get an image credit I'm like no problem babe you can have an image credit so here is
my wife's image of a black hole okay wow so I can see Terry laughing and
I'm sure that is dark okay but this is actually a serious picture right a black hole by definition
that we agreed on at the beginning is an object whose gravity is so strong not
even light can escape but we're astronomers we study the universe with telescopes We Gather light
so if we want to observe black holes and we normally observe the universe with
light this causes a real problem for us because light can't get away from a
black hole so since we can't get light from black holes we do the thing we can we look for
black holes doing stuff to objects that we can see other stars hot gas right things
orbiting it all kinds of stuff fills the universe that we can see with our telescopes and so if we can see them
doing something exotic then based on that exotic Behavior we can assure ourselves that black holes
exist okay and this is basically the process that has been going on my entire
professional career is in astronomer where I've lived through the transition from okay well we could look for these
things and maybe we'll see some exotic behaviors to Absolute confidence on the part of astronomers that these exist
because there's nothing else we can explain all the Exotic phenomena in the universe
okay so let me give you an example of this so uh many of you uh working through
your missier list which we heard John talk about a little earlier okay and so right in between Leo and Virgo and coma
is the uh Virgo cluster of galaxies it's the nearest large cluster of galaxies to
us those of you who are working through your missing list is probably one of the first Places You'll see multiple objects
in the telescope field when you looked there are lots of faint smudges you will get lost the whole time you're
navigating through but right in the center of the Virgo cluster is a monster okay the monster is usually called Virgo
a or m87 it is a large elliptical galaxy so elliptical galaxies are the
um piles that result from galaxies colliding and forming one larger Galaxy
the kind of cool Trivial Pursuit fact I like about m87 is the Milky Way has like
150 globular clusters around it m87 has twelve thousand globular clusters around
it okay so it gives you a sense for the scale of the Galaxy it is okay but for a
long long time people have stared at the core of m87 and it is known that there
is a feature there okay and that feature NASA has always pointed to uh this is a
picture from Hubble of this very long linear jet coming from the exact center
of the Galaxy and if you saw the video that was playing at the beginning of the live stream they were talking about
these jets these jets are a feature of active galaxies as we call them they are
always associated with with black holes because black holes are the engines that drive the formation of the Jet and so
you know in the kind of first decade after Hubble launched this image here on the on the left which you can get from
the Hubble archive is one that NASA would put up and say Smoking Gun evidence for the existence of black
holes okay now famously uh I uh when I was first in amateur astronomy a friend
of mine Mike Murray who's the uh planetarium director at uh Delta College in Michigan and Adam block who used to
run the uh observing program at kid Peak we took an image of the Jet and m87 and
you can see it right there with the 16-inch telescope okay so this is this
is you know in as much as John was encouraging us to not rely on technology all the time this is something you can't
see with your naked eye but amateurs today have the same technology the pros
have to such an extent that we can actually see evidence for black holes from your own backyard okay and I think
that's kind of cool so this jet uh is a consequence of
material streaming down onto the Black Hole uh the black hole in the center of the
Galaxy accumulates stuff around this uh this is often called an accretion disk or an accretion Taurus that provides a
supply of gas and dust and material that will slowly spiral onto the black hole
that material becomes very hot emits X-rays and other wavelengths of light that we can see with our satellites and
then some of it gets stirred up into these Jets and that's a combination of
conserving the quantities in physics that must be conserved energy angular momentum things like that if you
remember your physics classes but also the magnetic fields and the the the energy dynamics of what's going on down
there in the core but but it's the black hole that ultimately provides the energy to push that jet uh just light years and
light years out into space and we see these in many different galaxies they're very common and they all point to black
holes okay now those of you who pay attention to
the news and listen about black holes all the time you will know that the big news of late is we've finally taken a
picture of a black hole as the story goes okay so this is the picture of m87
again this case uh taken by the Event Horizon telescope collaboration and so
what you see here is this very bright donut and you should kind of keep watching the news because our colleagues
who work on this are constantly getting better data and doing better image processing so these images get better
and better with time uh but this donut here is not actually the black hole it's as we say the shadow of the black hole
the shadow of the actual black hole is about uh you know where I'm circling my mouse there two-thirds the size of this
or something like that but what you're seeing is the black hole bending light around it
from the accretion and the gas and the hot material that's around it and creating this donut shape and precisely
mapping out this donut shape the size is and the places where it's bright and where it's dim are a way of mapping out
the gravity of the object creating this image and it precisely matches the
gravity we expect for these objects that we call black holes so this is this is this is almost
certainly the best picture we're ever going to be able to get of a black hole without actually flying out to one and
you know taking a picture from up close Okay uh but but from from our Vantage Point here on Earth this is the kind of
image that we're always going to be able to get okay and it's it's a a tremendous and a remarkable uh technical
achievement and uh you you should be you should be blown away by what our colleagues on this project have done
they've released a second picture I probably should have put it in the talk I'm sorry I didn't uh of M80 of uh
Sagittarius A star which is the black hole at the center of our own Milky Way so in terms of size on the sky m87 and
Sagittarius A star the two largest black holes which is why they're the ones they're taking these pictures of so
okay so so observing is getting easier we know what to do we know how to look
for them we've got many many examples of black holes and all kinds of different sizes uh now and so the other part of
that though when you're looking for black holes doing exotic things to objects we can see is understanding what
black holes actually do to the world around them okay so I want to kind of
ask the question and kind of walk through very briefly what happens if you
get too close to a black hole because that's what's going on in these pictures some astrophysical object maybe it's gas
it could be Stars it could be all kinds of things get too close to black holes and the black holes do bad things to
them okay and so what happens if you get too close so let's not talk about exotic
stars that we don't have experience with right some of you may some of us do but let's talk about some explorers that we
can all appreciate okay so I want to send these two explorers into a black hole okay now when we did this we
realized I should have been starfly during that year but we'll we'll leave that for some other time so okay so these are our two explorers we're going
to drop into the black hole now the thing I want to do is I want to look at the force the gravitational force that
an Explorer experiences as they jump into the black hole and I've asked Bert
here to jump in feet first what happens is this the the gravity of
the black hole the strength of the gravity depends on how far away you are
so if you're close the gravity is strong represented by this big Arrow pulling
you towards the black hole and farther away the gravity is weak
represented by an arrow that's smaller but still pointing towards the black hole
now we're used to this right you and I experience plenty of gravity here on the surface of the Earth but if we go out in
you know into orbit then we don't feel the same gravitational pull that we feel right here on the surface okay so
gravity does get weaker with distance the difference between something like
the Earth and a black hole is this change in gravity happens over very
short distances fact it can happen over the scale of Bert right here if Bert jumps into the
black hole feet first it pulls very very strongly on Bird's feet and less
strongly on bird's head and so the effect of the black hole is to try and
stretch Bert apart to pull them apart there's a technical name for this we owe
it to Stephen Hawking if you go look up this on Wikipedia it will attribute it to Stephen he's the one who made it we
call this spaghettification okay if you want to be all Technical and impress
your parents with cool physics words you learned on YouTube tonight what a physicist would call this is a tidal
Force okay a difference in force between two points on an object okay it's the
same Force the moon exerts on the earth to produce the tides that's why we call them tidal forces okay but with black
holes we often use this term spaghettification precisely because it is so extreme okay and you can't tell it
because Bert's long-headed to start with right Birds kind of stretched out but if we threw our captain in there as well
they would definitely be getting spaghettified the black hole would be pulling on the captain's foot trying to
stretch the captain out into a long thin piece of human spaghetti okay
now the thing about this when you first hear it is it sounds exotic right but in
fact we see this happen in astronomy all the time one of the kind of current hot
fields in observational astronomy is looking for tidal disruption events okay
so this is a simulation of a gas blob that we had seen approaching Sage star
you can see the the years ticking by down there uh that we did a simulation of and what you when it restarts if you
watch you'll see the blob was initially very compact and then as it went around the black
hole the parts of the black hole that were uh closest to the blob pulled
really strongly towards the black hole and then everything else kind of kept going and everything stretched out into
these long streamers that we called tidal ales okay the material keeps
streaming onto the black hole that's what produces all that bright x-ray light and radiation that we look for in
our telescopes but the object itself is eventually disrupted and destroyed okay
this is what we call a tidal disruption okay it actually happens around black
holes we've seen events that we think are titled disruption events but it also happens right here in our solar system
okay so I got into amateur astronomy because I wanted to build a telescope to
watch Comet Shoemaker Levy 9 and David was here with us a little while ago right crash into Jupiter in 1992 this
comment Shoemaker Levy 9 came too close to Jupiter and the size of the Comet that was close to Jupiter got pulled on
more strongly than the side of the Comet that was far away and it broke it apart into this long string of mini comments
that we call the String of Pearls famously if you go read about this okay and so they were trapped by Jupiter's
gravity and just like the black hole absorbs gas the comet eventually fell
onto Jupiter and when they did they produced these spectacular uh explosion
sites with these black scars on the surface of Jupiter that we could see with our telescopes with our amateur
telescopes from here on Earth okay so I I particularly like this because this is what got me a damage or astronomy but
it's kind of closely related to something that I study study every day okay so tidal disruption events are not
exotic they happen here on Earth they happen all the time it's just black holes take it to the max
okay now there are other ways let's go back to that idea about orbits there are
other ways to see black holes and that is to watch individual stars and this is
the way that we actually mask black holes so the closest sorry this is not true anymore traditionally the closest
black hole candidate to Earth is cygnus X1 it's just under 6 000 light years
away this is a finder chart you can actually see the star that's the companion of the black hole in your
telescope you can kind of Star Hop through there if you want to but what is going on is there is a blue supergiant
star that is in about a five and a half day orbit around an object that we can't
see okay we could see the star wobble but when we flew uh the first started doing
x-ray astronomy in space uh this is the brightest x-ray Source in sigmus and
it's because the wind from the blue supergiant is captured by the black
holes gravity all of that gas in the wind spirals down onto the black hole it
gets very hot in the mid to X-rays and so we can see it as an x-ray Source in the sky
okay based on the size of the blue supergiant Star based on the X-ray emission based on the period of the
orbit this black hole is about 20 times the mass of the sun okay
now I said this used to be the closest candidate to Earth uh some of you may be aware of the Gaia experiment which is
measuring the distances to something like a billion stars in the Milky Way and so they're like constantly papers
popping up oh new system discovered by Gaia and one of those systems I recollect right now is a black hole the
black hole binary system that's closer than this and I just don't have the information off the top of my head but
traditionally this has been the closest black hole to Earth okay so this is all kind of classic astronomy
this is the stuff that's been bubbling around now for the entire time that I've been a professional astronomer but as I
told you at the beginning right I went to graduate school to study black holes and I fell into this game called
gravitational wave astronomy which is about looking at the universe not with
light but with gravity itself and that makes it an ideal
tool for studying black holes because black holes aren't made of anything black holes are made of Pure Gravity
so when I started in this game we could only do these things theoretically this is a theoretical simulation done by my
colleagues at Goddard about how two black holes orbiting each other Bend
space-time it creates distortions in the gravity which then Ripple out into the
universe uh in waves that we call gravitational waves and you can see them going out in every direction from this
simulated black hole merger this simulation I like to show you often see lots of different simulations that kind
of look like ripples on a pond but I like this one because it shows that the gravitational waves go in every
direction in much the same way that light from a star goes in every direction and that's useful if you're an
astronomer because it means it doesn't matter where you live in the universe you'll be able to see the waves the
gravitational waves in this case from this object okay now Einstein famously predicted that
these gravitational waves words exist in in 1916. okay and he spent the rest of his life
wondering whether or not they existed or not and he would constantly oscillate back and forth between they do exist
they don't exist they do exist they don't exist and it wasn't just Einstein right Einstein the entire physics
Community was confused and the reason for that is that this is a prediction about from general relativity and it
says something about the universe it's the phenomenon of the universe that our senses our bodies are not designed to
detect none of us have a gravitational wave detector in our elbow right it's not like our eyes right telescopes are
basically bionic eyeballs but none of us have gravitational wave detectors and so it took physicists 50 years to figure
out to convince ourselves oh these things are real and this is how
we could build an experiment to do it okay now Einstein himself had imagined
trying to build experiments to measure this but he famously thought it would
never be able to be done because he thought the effects he he's correct the effects were enormously tiny
right he was imagining could I build something in the laboratory that would generate gravitational waves and let me
measure them and he's like nope it's too small there's no way this will ever work okay but you and I live in the future
okay and we have technology and understandings of the laws of physics and capabilities that Einstein didn't
have he passed away in 1955 in about 1957 we
finally figured out what we ought to be doing and it took us all the way until the early 2000s to build an observatory
which today we called ligo okay our colleagues in Europe have one called Virgo our colleagues in Japan have one
called kagra but ligo discovered the first gravitational waves finally in
2015. that event is called GW gravitational
wave 15 2015 09 September 14th
okay so on September the 14th I had just moved into my house I got an email from
Vicki my director of the center here that said uh oh I think we saw one and
what we had observed were gravitational waves nothing else No Light No Other
signal gravitational waves in ligo from two black holes spiraling around each
other and merging to form a single bigger black hole
this is 400 megaparsecs away 1.3 billion light years away and that gravitational
signal has propagated Across the Universe until it washed across the Earth on September 14 2015.
okay the final black hole that you see there is about 227 miles in diameter so if we
were to lay it down on the state of Illinois it would stretch all the way from Indiana to the Iowa border
okay at the time we discovered this if you had asked me on September 13th we would
have told you we didn't know black holes this size existed we would have told you the largest black
holes would be about 10 or 15 solar masses but what we saw were two black
holes each roughly 30 solar masses crashing together and leaving behind
something that was 62 times the mass of the sun
this single event completely transformed our understanding of black holes in the
universe sorry it transformed our confusion of black holes in the universe because we
still don't understand where these things come from but we know they're there and today now almost a decade not
quite a decade later there are nearly a hundred such mergers that we have seen
so you can get this plot on our website at Sierra there's a little tool that lets you an interactive tool that will
let you play around with it if you want to but all of these blue black holes are
mergers of black holes that ligo has seen the red ones are everything that we knew
about before ligo's first detection okay so in less than a decade we have
increased the number of known black holes by something like a factor of five okay so you and I are living in an era
where we are slowly becoming inundated by so much information about black holes
that we will be able to answer almost any question we have about them because finally it's more than just a game on a
piece of paper writing out some math science is always this interplay between
observations and Theory Theory describes what we think is going on the
observations are the proof that the universe is doing that and for a hundred years or more we've been thinking about
black holes from that theory side but today in my careers in astronomer and especially in the last decade we finally
have data observations that are shaping what we think and what we know about
these really exotic objects it's going to get even better because I
work on this mission that Terry mentioned called Lisa we will launch in the early 2030s and we will see black
holes in the centers of galaxies okay so questions exist still of where do black
holes like that one we see in m87 come from and one of the only ways we can
imagine they grow is crashing together with other black holes okay and so Lisa this is one of the Prime things that
they should be able to observe so in 10 years when I come back to do an Al lecture live I'll have data from Lisa to
tell you all about this okay so that's something all I'm going to say I always like to leave you with things
to read and learn on your own uh so uh this book here by Marcia bartujiak some
of you may have read Marsha's book she's an excellent excellent excellent science writer this one won a science writing
award it's called Einstein's unfinished Symphony it's about the construction of
ligo and the Quest for gravitational waves the book does come into editions if you get the second edition uh there's
an additional uh bit in there about the first detection that I just told you about so it's an excellent excellent
book if you kind of want to you know melt your brain and understand a little bit about general relativity and black
holes and all the weird stuff that happens uh this book by Kip is probably the best one uh it's very complete it uh
also won a science writing award and it it kind of has a whole bunch of this kind of cool bending space time stuff in
it that you may enjoy if you have a little bit of technical expertise that is you're not afraid of algebra this is
a book that some people use as a textbook but it's called exploring black holes uh by Ed Taylor and John Wheeler
and it kind of goes through all the technical details of tidal forces and stretching space and stretching time and
how GPS works and all kinds of cool stuff which is related to black holes and so this is good for those of you who
just want to you know practice your algebra skills okay uh here's a link to my blog again and then here's a link to
a set of kind of 12 posts that I wrote for the 100 year anniversary of gr which
kind of tries to teach you about gr from the ground up without using a whole bunch of math so you may find that
enjoyable it gets to black holes somewhere in the middle there and gravitational waves near the end okay so
I am going to end right there and say thank you for your time and I will turn it back over to Terry
thank you Shane that was amazing that you have taken a subject that honestly I
didn't know a lot about and you made it understandable uh that was our goal you
did you did an amazing job thank you so much no problem that was incredible
um does any is or are there any questions or is there anything that anyone else would like to ask yeah I
just um your brain's melting right now it's Pride right now
um but thinking of a black hole is Just Pure Gravity yeah right
nothing else just Pure Gravity you know you know you've got stuff that's being
captured by it what's happening to you know what would happen to a planet or a
star or something gets gets sucked into the to the black hole does it just
convert to Pure Gravity or that's what happens to everything else right that's
a great question so so the thing that happens as you get closer and closer to a black hole is that that
tidal stretching gets stronger and stronger okay now perhaps
counter-intuitively if the black holes bigger if it's like the size of the black hole in m87 you can go all the way
up to the edge of the black hole and not become spaghettified the forces will not be so strong that you feel bad about it
and you can cross over the Event Horizon into the inside okay but at the point
you do that the gravity is going to constantly pull you towards the source
of the black hole gravity which at the center of the black hole is an object that we call the singularity okay the
singularity many of you have heard this term it's an object whose
um whose gravity uh it's an object who's which is not precisely described by the
laws of physics if I look at the predictions for the gravitational field at that point it becomes infinite which
is we believe is an impossibility right it's Infinity is a mathematical idea we
don't think it's a a physics idea and so what we usually say is the laws of
physics break down near the singularity but all the way up to the point where
that the laws of physics break down those tidal forces are getting stronger and stronger and stronger and stronger
and so once you're inside the black hole even if you survive through the Event Horizon as you get closer to the
singularity you will get spaghettified okay and then that Singularity it's a
source of infinitely strong gravity it's going to pull all the material into it and at that point we don't know what
happens right it gets compressed into something that's infinitely dense and infinitely
small and those Concepts don't mean anything okay right and there's a there's a great book by uh Lenny suskind
I think called the black hole Wars okay and this is all about what goes on inside the black hole what happens to
right if I throw information into the black hole a person a book right the
quantum states of all the atoms that fall into it what does the black hole do with that information this is a huge
issue in physics is it lost or is it preserved somehow but it's all related to the fact that we don't know what's
going on with that Singularity I see yeah okay or I don't see so the inside
right here anyone who says they see NC is completely bullying you right so right but the inside of the black hole
is empty space as well that's what we mean when we say the black hole is Pure Gravity it's just pulling everything towards that Singularity The Singularity
is the only thing and we don't even know what it is hmm Shane that is fairly well accepted
Now isn't the theories that you were just describing tonight so so especially
especially with the Event Horizon telescope pictures with you know all the
kind of probing of what's going on close to black holes with title disruption events we take all of those observations
this is the data side of astronomy right we say these are our observations this
is what nature is doing we can't argue with it right maybe the observations are great maybe they're not but the point is
they tell us this is what the universe is doing and if we compare that to the
predictions of general relativity which is what we understand Gravity the correct description of gravity to be we
have not seen any anomalies between the two okay so as as physicists as astronomers
what we say is the data the observations and the the the the the mathematics are
in agreement but we keep looking we keep trying to probe closer to the black hole we keep
looking for new black holes we keep looking for new events because we know and the history of physics is replete
with this kind of of of case we know that as we get better with our
observations we get more precise we get to smaller scales eventually the way we
currently describe physics isn't going to be good enough anymore and there will be some new additional bit that we have
to add on and the Frontiers in gravity are something called quantum gravity how does gravity behave on the most
microscopic of scales and whether or not we can get there with astrophysics or we
need something like particle physics or something String Theory something different that remains to be be decided
but but this is this is the frontier right now right thank you well done yeah
you mentioned that there was a second picture of sag Jay is that something that is on line somewhere that yeah here
let me see if I can pull it up in a web browser while we're here okay so uh Event Horizon
telescopes sgra star
yeah rock and roll okay so in fact here let me pull up this image because this is the two of them together okay and let
me put it in a window all by itself so I can share the window
yeah waiting for it to load here
okay so so this is the two Event Horizon
telescopes uh pictures side by side so this is the one I showed you of m87 on
the right and this is the sage star one so the Sagittarius A star uh Sagittarius
A is this complex right in the Milky Way so if you look at the teapots of Sagittarius the you kind of go up uh
where the steam coming out of the spout would be that's the direction of the center of the Galaxy so Sage a is the
complex there and sajay star is a compact radio Source at the location of the black hole so we typically call the
black hole Sagittarius A star because we think it's the source of the radio emission but this is the ring around
Sagittarius A star and it's different than the ring around m87 but that's because the gas is distributed
differently we're looking at the black hole the slightly different angle okay but you can see they're roughly the same
size they have the same kinds of features and to to Carol's comment a
moment ago right this is this is our data so we use this and we compare this against
simulations of what does light around the black hole do and how does that arrive at our telescopes and what kind
of image would it look like and and this this this is in agreement
so these are the two largest black holes that we know of correct yeah well so they're not the largest black holes
they're the black holes that have the largest size on the sky right so we're talking about angular diameter okay
right because it's just like anything right the moon's a certain size because it's at a certain distance from us but
right pushed it farther from Earth it gets smaller if we brought it closer it'd get bigger right the black holes
are the same way so these two black holes based on their size but their distance from Earth they have the
biggest apparent size in the sky okay so that's why they were the targets
there are other black holes we could try and image but they won't make as big a shadow image as these make because
they're they're smaller in apparent size go ahead Terry go ahead you mentioned uh
the the black part of the donut there uh the actual black hole is not as big as the dark Center correct yeah right
exactly yeah and that has to do with the path that light takes as it goes around
the black hole because if it's trying to go around the black hole by just skimming over the surface of the black
hole it usually can't doesn't have enough oomph to get away from the gravity of the black hole and falls in
right but as you get farther from the black hole the gravity gets a little weaker and and the photons can
eventually wind their way out so this the size of this donut is actually an indicator of the fact that there's a
black hole in there right okay the uh in in these images uh Shane it
seems that you know uh a lot more than I do or could even find out not as much as
my EHT friends but but I'm looking at the images and you
know of course we see these bright brighter areas here you know the Sage's
got uh three bright uh areas and in its uh in that ring but I also notice a
fainer you know background um you know uh stuff detail yeah these
things yeah you know are these like jets are they um uh is it material of some sort yeah
so so it is absolutely material right because what you're looking at here this
is all done with radio telescopes right so so radio emission comes from gas at a
certain temperature and the intensity of the emission is how much gas at that
temperature yeah where it is and so you know as you go out this way this gets finer so there's less and less gas but
the fact that you're seeing radio emission here means there's something there producing that that that that
signature that you're seeing in your telescope it's emitting the light and if if you look on bigger scales you can so
if you if you um if you go Google images about uh the sage complex there is
enormous molecular clouds of gas and dust down in this region right there's lots and lots of stuff uh both close to
and far from the black hole and so this is part of that extended emission but this is the stuff that's closest to the
black hole right because the black hole is this big so you're only what you know five or six black hole radii away when
I'm talking about this right the scales that we're used to looking at stuff on this areas of galaxies is is kind of
much much like light days across right sure but here this is stuff that's really close and it's emission so it's
gas of some sort huh okay those it's very very interesting
and you're cool yourself wonderful and the audience uh that responded uh they
don't have questions but I think that they really enjoyed you know they said uh we're all or uh I asked Ronald green
watching on Facebook uh you know if he had any questions at all uh he says not
now but it's a great talk so well I'm glad everyone enjoyed it and I appreciate the invitation yeah hey you
are welcome anytime we appreciate the talk we have a date in 10 years after Lisa
flies right no we're gonna have one before that oh okay all right thank you so much that really
was incredible so all right I am going to go back to the questions
and give the answers to the questions that we've um uh oh
hmm okay I am not able to let's see if I can
share this way here we go there we go
you're sharing all right there we go and which screen I need to look at okay all
right so here we go the answers foreign
to the questions first question was while driving on the moon the fender on the Rover was damaged what did the
Apollo 17 crew use to fix the fender they used four maps and duct tape uh
Harrison Schmidt was on was at Alcon this year talking about that it was amazing to listen to the stories so yeah
that was really cool the winner is Barbara Brown next question
on December 7th part of the U.S will see this occultation of what planet and
that's going to be Mars being occultated by the moon and the winner is Jess Myers
and the last question on November 16 2022 Mars will be in what
constellation it will be in Taurus but it's really cool because it's going to be centered between the horns of Taurus
so I think that that's pretty cool too so our winner is Marilyn Wright and we'd
like to thank all the people that answered the questions and thank everybody for tuning in
and I would like to thank everybody that has been on the show tonight we had David
Levy uh Carol orge we he is the astronomical league president we call
him the leader of the pack uh John goth uh League media officer Scott Scott we
couldn't do this without you thank you so much for everything you do we are greatly appreciated my honor and
pleasure thank you hey we are so honored to have you so and Shane Larson oh my
gosh Shane that was a fantastic talk I really enjoyed that as I know many more
did uh thank you so much for being on and everything that you have taught us I
will definitely be in touch with you next year we'll see if we can't get another day put together we're on it
that sounds great and thank you to everyone that is watching and we wish
you all a Happy Thanksgiving and we're going to let you know we will be back Friday December 16th what we are going
to do is bring on all of the astronomical League officers so we can tell you what the year has been like and
kind of wrap up 2022 and welcome 2023 and our speaker for keynote for our next
for December 16th will be Bob King and he's going to talk about the sun
equipment a lot of things about the Sun and he will will all start talking about
the solar eclipses coming up there's one in 2023 for an annular and 2024 we've
got the big one coming across the U.S that's going to be a big one for all of us so thank you all
for that and for being with us and please join us next month we really
appreciate it and uh I think that will probably wrap us up for tonight unless
somebody else has anything they would like to say okay people are uh Harold
lock says thanks for a great show um and uh Mike Mike modricum I think
that's how it's pronounced for Madison uh said will this be available on YouTube if you're watching on YouTube
right now I can see you're on Facebook but yes it will be available on YouTube uh you could go to the explore
scientific official YouTube page and find it there of course you can watch it again on uh
the astronomical League Facebook page I've put a link in the uh the uh the
post of this uh of this program and um uh so it's it's going to be out
there in perpetuity uh unless a black hole comes and swallows it up
anyways so and then it might be preserved forever and ever I don't know
what happens after it goes in that's right Mark is from the Omaha Astronomical
Society so that's great that's great okay so uh
yeah Stephanie Bain is watching Ronald green uh these are just people that uh
chimed in uh a lot of people watch Without Really uh chatting with us but
uh uh it's great to have you watching uh Michael P Mike peoples who is uh was
talking to us recently about the uh Northeast astronomy forum and the
Imaging conference that's coming up okay um Conor Bradley was watching uh he had
questions about the moon and the trails from the Taiko crater on the moon you know so I was able to answer that for
him um but uh um
I think that's going to do it for tonight so thank you very much and Terry thank you hey thank you Scott all right
okay this is number 22 correct number 22. that's right that's a big pile of
them yeah that's right that's right I'll have to add up all the hours and all the
um uh you know all the views and everything else so we'll we'll get to that Terry thank you again okay uh to
everybody that's watching and we'll watch this program uh if you want to learn more about black holes you
probably need to watch this program about 10 times Yeah okay or come come study them with me go back to college
that's right and then ask the questions from Dr Larson okay so that's great
um and uh you know keep looking up and we'll be back again with another
astronomical League live see you December 16th thank you everybody good night good
night okay good night
there is no audio with this but I thought it was a great uh visualization of uh gamma ray burster
221009a where they think a new black hole formed in that heart of a collapsing star
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