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>> All right so I think we will go ahead and get started we've got to almost 200 attendees so that's really nice I'm glad to see so many people turnout this evening. Tonight we have 2 speakers who will be discussing the Nobel Prize in physics that was awarded this year we have Professor projects to talk about each school of physics at Georgia Tech and we have Dr Aaron botting who is a senior lecturer at Emory and also the director of the Emory planetarium now without further ado I will hand it over to Professor said on a **** I don't know whether it's just me but I dread the morning I do that reading the news of what happened last night in this horrible year.

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So imagine my surprise when you look at the form and I see Nobel Prize in Physics Roger Penrose now I would have never thought that Penrose would get a Nobel Prize because he deserves it's not going up or up to startle him and c he's also a very sweet person he's just not the kind of person that Nobel Prize look at my mouse in the upper right corner about my bed there's a book it's called the wrote to reality it's really by my gut.

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And it should be by your bedside too specially if you're taking any courses it's a serious commitment that the 1099 pages to be poems this is a book this book is amazing and I will explain why it's amazing and I think the only fair thing I can do to Roger penance is to try to give you the world as seen through Roger Penrose his eyes.

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Cannot do his accent. But I want you to get a sense of what is it like to be a living passionate human being like Roger Penrose occasionally even slip in the 1st person the story starts is a typical Penrose thing immediately the moment he got his Nobel Prize he was besieged by journalists and they're always asked the same question What is your advice to young people Penner's answers advice to young people given that it is not a good idea but Ok Do what you find exciting Do what you find beautiful as a child did not give us a boy from marks by problems of mathematics teachers reporting to his parents his problem solving skills a totally Joliffe for school and Penner was there points I was moved down a class and it went like this.

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He loved math and each $21.00 he looked at his colleagues and he understood there were 2 kinds of people around all but committed to mathematics that some of them thought they surely and some of them seem to think linearly as a sequence of statements endeavor people like sounding like music some of them like our confront the difficulty understanding equations that he was manipulating so by reach 21 can invented his on that come out to call language on the left hand side you can see the usual symbols and the crazy ones mathematicians use and on the right hand side you can see his calculations he drops them down so his typical talk to wish.

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H 23 he went to math cognise and upset them and signed asset exhibit he came back talked to his father who is an impossible contrary and the Son and the father constructed the impossible try bar the father was very interested optical illusions and they published this and they went back to ashes it and draw in return the impossible waterfall at the h 24 he reinvented and the inverse of a matrix that has now unless it's matrix has too many zeros in it you cannot invert that and it turns out our undergrads take cool darts turns to a criminal organization called check you can get the answer you can get a more perilous inverse into b.l. time value taking an exam and today it turns out it's time to place it in your a science and take data it was a little invention that they spent before this longer precautions at $27.00 he decided he knew nothing.

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He knew enough is x. he says I've decided I was going to start learning some physics in a serious way I had to learn it myself because I'd never taken a proper physics course h. 20 seven's I think it's $27.00 things happen he finished this is pure mass piste and something called tensors turns out to be very useful if you want to do a general relativity 2nd he meets 29 year old David Ritz Finkelstein that changes both men's lives for ever and here is what Penrose says about it I think my older brother read me the Tompkins in Wonderland chapter no sound fascinating My friendship with Dan Sharma when I was in Cambridge here he rented me very much but it wasn't the case that I nationally wanted to do it as a career I think this came about more when I came back to Cambridge as a fellow research fellow and then a Sharma persuaded me to go to a lecture in London given by David Finkelstein and he was describing how the.

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It had been commonly known as the structure of singularity what we now call the horizon of a black how it was not actually a singularity and you could extend through it and you had a singularity in the middle but you didn't have this so I came away I we had discussions and I got certified up to do more General Ham He commented on this that I told him about some things I was doing about conflict or quantum mechanics and he went in that direction and I went in general to see which had been his record.

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I think I was struck by the fact that even though the this apparent singularity at the horizon was not there you pushed it somewhere else you still had the singularity in the middle and I wondered whether there was some theorem about the. Persistence of singularities in some sense this is a long time before I can prove my own thing from many years later to time but I did wonder you know what kind of methods could you pop possibly prove a thing that I had no idea thought because I knew very little about the subject but I have been studying spinners because I've been interested in quantum mechanics and tensor systems and more Aspen and it intrigued me a lot but this was the main thing I knew about and so I tried to write general terms instance and lots of things came out so beautifully that I got hooked by the subject I think that was the main thing I thought these things were quite.

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Fit together in interviews were way which I hadn't anticipated to and then other than that really hooked me. Was the fateful meeting what happened to parents is that he became a channel go out and he says and I agree with him general ought to have it's not difficult to comprehend compared to quantum mechanics equations make complete sense that you omit one can't explain it.

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Not entirely on a slip but rather quickly the space is like a rubber surface and if you put the plan I thought of starting the space it bends it and it falls in it as it would fall and Robert membrane and what fascinated everybody working on general I think that the up to that time was the question that if you put too much mass and part of space will it bend that rubber sits so much avail for.

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A home now what did Finkelstein talk about in his London seminar he explained that you could take what is known as the Schwarzschild metric it's one description of this bending of the spacetime in a neighborhood of a mass and he explained that you could extend this description of spacetime beyond what's today called a black hole horizon and that is to do your basic ingredient in current understanding of black holes that even though you've reached this horizon beyond you cannot escape the black hole inside of it you can describe the world and you can find that there is actually a singularity that the cold a black hole now this seminar was Revelation depending what happens after the seminar there was a couple of hours of conversation between the 2 men and it was totally amazing Penrose explained to Finkelstein his ideas about quantum nature of space time our history in that folks the 2 men exchange their research subject forever after you know I'll come back to this and I can talk about spin that works but Finkelstein picks up on the community Tauriel aspects of quantum spin as a possible route to delving more deeply into the quantum nature of reality and suspend us he took such ideas to greater lengths than.

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One Else then notes in turn to General Relativity and that was that they switched forever after what is the problem is the early glycol solutions Finkelstein's extension of the short settle metric this description for the neighborhood of black called is provided Penrose has an opening to general relativity but everybody in Penrose opinion and my opinion too had assumed too much symmetry assumed that the neighborhood of a black hole was perfectly spherical in 3 space dimensions and that the gravity pull exactly toward the center Now imagine if you had lots of people this pistols and a very high position shooting exactly the same point in space of course you know there would be a huge concentration of lead at that one point that if they made any errors whatsoever the bullets wouldn't hit to child or that would scatter round the mass would slash in the bottom of this of this rubber hole and how could not this assumption of perfect symmetry lead to a singularity the thought happens if you don't have a perfectly initial condition you have mastered the coming into this all from different directions at different speeds etc People didn't believe that then on that and said it Penrose addition to 7 What if matter sloshes around and indeed here is a simulation done by Professor John Lyons of Georgia Tech it shows what happens if you have a gas that contains 10 to the 5 solar masses collapse into a black hole in a simulation you can see that is a different instance in time of density and you can see that this is sloshing in a very complicated way there is nothing seen medical about this actual so.

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The ocean of competition early creations and until then everybody thought well symmetrical singularity collapse but and yes symmetrical one could lead to matter coming in and sloshing out again it would not be a black hole and that the thing I would like you to understand about these young people is how young that over here is Roger Penrose at age 31 leaning on this car standing in the car is David Finkelstein and then you see everybody else and what you see is you basically see change the seat to grab outs and a bunch of nerds everybody else looks like you're supposed to look like if your theoretical fist business is interesting in general not have it about not these 2 guys these are 2 cool guys who listen to nobody and follow that path will not leave Frankenstein and follow presidents age 31 here started thinking about 10 a relative that the member each trying to 70 he knew no physics he had to learn this stuff age 32 he already invent an important thing that everybody uses to base its call center stogie and basic idea of Penrose diagram is that the only thing that really matters is stuff that moves at speed of light and special and general relativity and that defines courtrooms cones of air is special because on them that is not time they somehow interpret about space and time but they divide space time into causal da grams things inside can interact things outside cannot communicate in Pender stuff I got infinity in space or time gets mapped into the point that you can look at the new can understand climate that they've features of structures the.

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General Relativity accommodates some 6 years from when he starts being a physicist he finally proves existence a black hole by bringing in something that he was very fond of but it was not a natural thing to attend a relativist he brought into parity now what is the point the polish is rubber sheet Jelnik the details just properties of objects and stretch and you know that's what strong gravity does it stretches things in you know at a parent g. for example the little Animo and the sphere are the same the cop is the same as a donor they have just one or one handle the objects like pretzels that have 3 holes or 2 holes.

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And these are the things that the parity captures it captures the basic cheer metrical shape is out focusing on the holiday actually builds a construct and what's new about topology once understand a deckchair don't need to solve equations That's the brilliant idea that goes into his proof for the existence of black holes he's able to argue that traps and for solve any shape is governed tease that once you fall into the black call it cannot slush out the technical argument is too subtle for tonight's story and not pursue it so why did he prove he proved that you can't put the surface and around a black hole at a cold trapping surface of any shape and he proved to stop the logical arguments he's out something and the equations that as you went into through the surface you could not come out again now what that meant is that General Relativity does not hold that the word segment that black call should be everywhere now at that time the event of black holes and now but in your very small or very big or anything so at the age of $33.00 he changes the subject of general relativity or black hole physics and he publishes his Nobel Prize paper Ellen the right hand side you can see a typically beautiful and Ross an illustration of how the trapping works and he's done so they can stop this presentation the man has gotten his Nobel Prize at age 33 we can go on.

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It's not to fast it took many years for his tournaments to become less skeptical now they're all on board. He had a long experience with mathematicians and physicists who told him all kinds of things that I didn't believe and turned out not to be true so Roger Penrose remains Roger Penrose at that 36 when Vance twister's one of the big questions that physicist always have to face is why do we live in 3 space dimensions and did that much of the time modern physics people hypothesize many more than 3 space Damascus productiveness convinced that there is a reason you have to live in this to make the mansions to explain it invents what he calls twisters twisters so that our 4 dimensional space time there's a say 3 dimensions of space an amount of time is a mirror of a mathematical structure in 4 dimensional complex space space which has imaginary number Senate and notice how he explains this this beautiful beautiful pictures here on a status in a beautiful way did sell all his transparencies and this is how he communicates at each $38.00 he and Hawking postulate cosmic censorship and it basically says yeah black holes out there but they're all wrapped in some kind of body bags and we can't see them that is a principle the chicle cosmic sense it contempt that black hole singularity is a confined time event horizon and surrounding this hidden spacetime region because actually if a lid on the edge we could actually harvest energy because there's lots of stuff going on just on the edge of this it had to rise and visit great amounts and you know I started on McCleon think up a great amount of energy is emanating from those regions you know what's shown here is you might have seen that this is a beautiful photograph.

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From 2019 of a black hole of course we cannot see the black hole but we can see cradle activity on the edge of the black hole and things are falling in and radiating at 38 pendency a glance negative dimensions so what's a negative dimension. Is Monday mentioned no the screen you're watching is 2 dimensional you're walking through a 3 dimensional room people who live special the ability to understand the actual live in 4 dimensions to live in space time but mathematically you could live in negative 2 dimensions and it's actually very elegant and pretty to live in 2 dimensions and look at these calculations they're all done in terms of pictures at the edge for take him what's the answer to the call foul and questioned students always ask me if space is continuous or discrete and you know many physicists are no later comes to this point you know it's quite possible that on our scale and beat or centimeters or angstroms things will continuous but if you have a very very good microscope going to very small and so there's something called Planck length which is it to pick a gravitational went maybe the space is discreet How would you know it and how would you describe it tennis proposes to build on that space the world that we live in from Blue quantum Spence spin one half's to smallest possible spins and again his calculations that dramatic you can see them right here on this show at 43 kids that's something that General Relativity should not be doing he invents Penner styling Penda styling is this amazing thing that you know a number of people have pondered but the.

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And has brought it to its simplest possible lessons and you take 2 little tiles to differentiate tiles in such a way that they can fit together and you start tiling the space like the floor of your bathroom what's amazing about this tiles is that it looks regular But if you look close to it it's actually not periodic any place you know every region is styled differently no matter how big the floor of your bathroom is you know that this transparency is you can get from my website and when they're colored links you can clean Kong and you can see the things that cannot cello you right now now what is this big deal this startling dispenses of centuries of received wisdom going back all the way to Kaplan or you know Kaplan of our searching for pentagonal snowflakes and the consensus in physics and chemistry of night in that 20th century was that you cannot build regular crystals from Pentagons that could not possibly the way the drawings again up an assistant rings and this went so far that when an expert in mentalist discovered and crystals and spent time going out symmetries 5 full symmetry I expect a man to measure that nobody believed them to give us much abused he was attacked one night another chemist who all had to know about this is one of them for peace but nevertheless And eventually the outcome of this discussion was that recently he was voted Nobel Prize in Chemistry for this thing so this seems like a strange little king but it's really in this contrarian spirit the child is saw at age 23 he his father asked design impossible tribe are here to design impossible materials and showed that they actually can be constructed at any age Roger and Lance has been a contrarian all this.

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He always derive the great pleasure in needling it irritating fellow physicist but one thing that works 100 percent if you want to irritate the physicists is to say very loudly quantum mechanics is wrong. And he profoundly believes it even though all the rest of us are now bred by using quantum mechanics and it hasn't you know done anything that's said to us for a century it's miraculous what it's given us the very fact the chimp watching this screen is a consequence of advances or to quantum mechanics forgot or quantum mechanics is wrong because what's missing in quantum mechanics is description of gravity he believes that privatisation a Quantum mechanics is made you know that he shares this Finkelstein the best thing that we have it's a wrong one thing he cannot stomach is Schrodinger's cat he claims to have done have a connection between quantum level of reality and classical I will note that your series your eyes describe the Newton mark so once that at 58 to know he has to go to Alton 7 us Christian Andersen was born so he does this cute picture of I'm learning mate of H.'s bones classical and quantum has to be joined at the waist in a way that we don't understand and then at they catch $58.00 he goes No 8 on us it comes out of his this book called The Emperor's New Mind his absurd his friend Hawking make a pile of money on a book that nobody has ever read or understood so he writes a book and he says I don't know much about neuroscience both he argues that quantum mechanics is a fundamental component of consciousness kid drives us totally crazy Truth Beauty morality trialling to develop the.

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3 it's consciousness it's so difficult in must be quantum mechanical you know furious not just evolutionary biologists here rouses the future we have a body for people wanting ideas about human consciousness he goes on I 963 year right shadows of the mind he looks for missing science of consciousness he joins forces as honest ologist Stuart Immonen off and you know there are more and more does beautiful pictures of x. in x. Suns neurons etc He uses all kind of physics worlds in neuroscience and then on the side that h. 66 he sues Kleenex quilted new paper for using his copyrighted patent and he Vince humans' the court case and they're not allowed to know how much he got out of this by the terms of the agreements the famous nondisclosure agreement in 68 rights and that a book on science and the mind and 69 is a collaborative effort that the Knesset pendants very wonderful woman they together produce a son Mike so Penrose and finally at 73 haven't being harassed by his colleagues now for decades colleagues he says like my creations but not the contention stuff about the mind and urged me to write a straightforward book on physics I thought do this impulse is a job but it didn't talk its way like a tz a work went into this bill call a complete guide to the laws of the universe the one that about my bed always and it's an amazing book in pictures as you can see a typical page inside the book they wanted to write a book about something that you know something about 80 years later he produces The Complete Guide to the laws of the universe I'll show you some illustrations and this is spent.

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Once that beautiful and takes 3 many helpful in explaining the material you know it's very mathematical material but this book makes it approachable not to the every person it was supposed to reach to my students and myself it's an invaluable resource to go back ever nor again to get some intuitive picture of the mathematics that we're doing our research at 75 become citizen outrageous solution to profit and cosmological parcel and votes to puzzle most of us have accepted that our world was created in a big bad the universe said to live and now the question is what was there before the big that he goes to Copenhagen told by the party to give a talk as a birthday present and it's a concert marriage of eternal and rebirth and again you can see the typical Pandarus transparency visually beautiful begin understand a thing you know about bare hands they did not get it then says that there is no one in the universe is born and began evolution us you notice goes in cycles of time and again illustrated beautifully you know one big bag of our universe is on the left but it's supposed to match up and then topple logically be this cylinder I don't know right off eternal felling Cain and expanding again and it's an active area of research right there and collaborators see evidence of earlier universe exist before the big band of our present universe you know it's repetition of what he did at age 33 the Big Bang is only an apparent singularity similar to the apparent singularity at the event horizon of a black hole conceptually it's a very similar thing but now we're talking about entire universe type and had h.m.t. far and to reason why he did not understand in Copenhagen what is going on is because.

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Roger would talk about was about Sri Lankan cricket team in England. To a 6 so it was only about cricket while he was in Copenhagen so that's the only thing he wanted to talk about cricket in Sri Lanka and the England in $84.00 he joins an effort that kind of science effort to teach children how to draw to be able to do math and science at age 85 he writes discrete goal fashion Faith and Fantasy in the new physics of the universe and it's a screed against his call it says who found all fashions and think in polygynous only in terms of fantasy so he's a contrarian and you love him in my bed Nobel Prize winner it's most friends Maurice ever because he's just such a lot of a whole passionate creative thinking human being here here's Vince Mitchell Fike and myself and the unsung grateful to have it and now I would like to hand off this presentation.

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Thank you very well my. Carrying So I'm afraid I don't have anywhere near that's colorful stories to tell about the 2nd half of the Nobel Prize but I will do my best Ok so I'm going to talk about raising Stuart Gulliver sharpest tool in. White support. It's going to be incredible just just wait Ok so I'm going to discuss the 2nd half of the Nobel Prize which was awarded jointly to write against will and be I guess for the in this is a quote from the Nobel citation here the discovery of a super massive compact object at the center of our galaxy the word black hole does not appear here right so it seems that even the Nobel Prize Committee is not yet on board with with the idea of black holes so as we heard.

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Earlier it is true that it took the astronomical community a while to come around to the idea that black holes were real but in another sense the idea of a black hole predates all of this work by centuries though the 1st idea of a black hole dates to the late 18th century and here is a look Plus who is calculating what would the mass and radius of a hypothetical star have to be such that the gravitation at its at its surface was strong enough that it would equal or exceed.

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The 6 is made that the escape velocity from the surface would equal or exceed the speed of light and he comes up with an answer and he is he's quite right about the mass and the radius or he's extremely close although there is no such thing as a star $250.00 times the size of the sun with density equal to the earth.

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Such a thing would collapse into into a black hole so not only were the eye was the idea of a black hole known at this time but also the way to discover them so low class was predated by a few years by an Englishman who made the same calculation and he was thinking in terms of binary stars and so whereas plus back here says at the last sentence there are the largest bodies in the universe invisible by reason of their magnitude I feel thinking about if there is some luminous bodies such as a star that revolves around a black hole we could infer their existence and he says about the consequences of such a supposition are very obvious and at some of the side like my present purpose a sign up shall not prosecute them any further so perhaps I we may have had the 1st discovery of a black hole in 784 but as we shall see there are a bit of technological difficulties with carrying out this project but this is the way that the super massive complex object I'll call it a black hole in the center of our Milky Way was found it was found by looking at luminous bodies stars orbiting around Ok so I want to give you a little bit of introduction about a black hole and just like Penrose here I'm illustrating the equations so we don't have to think too much about them so these are the equations of general relativity and I are not going to explain explain the details about we what we have is mass on the right hand side so those terms there tell us about all of the stuff the matter the energy the bowling ball on the rubber sheet and what happens when you place a bowling ball on a rubber sheet the rubber sheet is curved and deformed and that comes in on the other side of the equation we have some terms that describe the geometry of space how space is curved there.

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Another term that includes the dark energy that accounts for the extreme increasingly expanding universe which is a subject of a different Nobel Prize altogether and then there are some some calculus in there so these are the equations that Einstein developed to describe how mass affects a space and here we have the 1st solution of this for a short field a black hole so this would be.

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Black hole just a simple mass. Which has a an event horizon so the radius of a black hole we say is the event horizon and that is the point at which the escape velocity is equal to to the speed of light and it's related to to the mass of the object Now you heard Penrose talk about the singularity at the horizon that he was trying to get rid of though if you look at these various terms here what's what that equation doing up there it's telling us about how space and time interact so that 1st term you see a d.t. t. is for time and so if we imagine what happens at the event horizon at 2 g.m. oversea squared the thing in the print The sees the in front of that goes to 0 but does time stop at the event horizon its your clock must turn off as you press the event horizon that that seems odd and if you look at the space the 2nd term you are that's like the radius and we would get a one overs 0 sum infinite term there which which physicists don't don't like whatsoever so this is the singularity at the horizon which hen Rose shows is not is not a physical singularity but here is another type of black hole so short field length $116.00.

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Adding your momentum to a black hole is going to take you a few decades so in 1963 we have the expression for a rotating black hole and that's a lot we're not going to discuss that equation there and you look in the lower left we have a much more complicated structure with event horizons and singularities and this is what Penrose was but was contemplating when he came up with the idea of a collapsing star forming what is known as a trapped surface which would be the generation of the that horizon and you see there Penrose's drawing on the right which I think we have to agree is a little bit has a bit more character than the one from the Nobel Prize organization on the left Ok so to show you a couple of Penrose diagrams of the 4 we talk about discovering the real black hole because I think it's kind of interesting and it addresses some of our science fictional aspects of black holes so this is a way of representing those equations that I just showed you this is for a short field black hole.

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In in the form of a diagram and as we look at the State Graham you see on the right there there's a blue dot it's a little particle that is moving forward in time so time goes up in this diagram and you see it crosses the horizon with no problem it doesn't have to turn off it's clock and once it crosses the event horizon it lands on the singularity and we can have lights going off in different directions as well and what Penrose showed with these diagrams is that you can extend them though on the left you see a Penrose diagram for a Schwarzschild Black Hole that contains the other half of the math basically this is the idea of a parallel universe being attached to a to a black hole over on the right when we have a rotating black hole we get very.

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Interesting paths into the black hole and then out into another universe so we see in these mathematical descriptions the possibilities that extend beyond simply locating a black hole in our in our galactic neighborhood is the black hole in our galactic center a portal to another universe. But it's fun to think about Ok let me go back just a few things here so here's Penrose and his his Nobel Prize winning paper and notice how he leads off up there in the upper left and he's thinking about the discovery of Chua's a stellar radio sources which has given a kind of impetus to thinking about gravitational collapse so astronomers are coming around to the idea of a black hole because they've discovered some was a stellar radio sources some oddball objects that they think might be connected to a black hole and those are the quasars that will go back past year Ok so the 1st quasar was discovered in 1903 by Martin Schmidt you can see him honored on the cover of Time magazine back when astronomers were honored on the cover of national news magazines and what he observed was a star like object to in the over lower left there you see a Hubble image looks like a bright star but it had a very large red shift and what that means is that it was very far away so we know the universe is expanding causing things to have a redshift and if it was as far away as the redshift would indicate it must be more luminous it must be about a 1000 times as bright as the galaxy and if you look in the right hand image there in the center the center bottom you can see a little bit of buzz around around the image that's the galaxy so there is something in the center of that galaxy that is producing enough energy to outshine the all of the other stars in the galaxy so this is what astronomers were confronted with observationally and why they just so happened to have some theories regarding black holes that would explain this so in 1969.

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When the bell. Proposes the idea that quasars are run by black holes that is the falling of material onto a black hole that produces this incredible amount of energy and this is it's interesting to me to see this this all time language so instead of referring to to an event horizon he's thinking about the short field throat and so they he expects to find them in the centers of nuclei of galaxies and I think Susan then in the 2nd paragraph he expects that these collapsed bodies these black holes would have spread a broad spectrum of masses tend to the tend to tend to the 11 solar masses that's about the upper limit of super massive black holes Well Norm or got normal galaxies like ours may have only 10 to the 7 or 10 to the 8 solar masses down their throats so it's overestimates it a little bit but this is the 1st idea that if we have matter that is falling onto the black hole it in the process of falling will heat up to incredible temperatures and it will become packed into a very small region before it crosses the event horizon and we no longer see it so what a quasar is is an actively feeding black hole which suggests that when the black hole is done eating there should be a collapsed old quasar there should be a super massive black hole as a relic of this earlier period of active accretion and that indeed is what we believe the super massive black hole in the center of our galaxy to be which there is no quasar in our galaxy it would not be good if there were but there is a super massive black hole.

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Ok so there's the galaxy and if we have this idea that there might be a super massive black hole in the center of the galaxy well we'll just go look for it there's a bit of a problem with that we are quite a ways away from the center of the galaxy so about 26000 light years from the galactic center where the super massive black hole is you can see the map down there in the lower left if you like to take a visit and even more importantly the galactic center which you see there in the image of the Milky Way is highly obscured in visible light all of those dark patches that you see are regions of cold dense interstellar clouds that are absorbing light from the stars behind it so in order to see what's going on in the vicinity of the black hole we need a way to see through all of that stuff and so the way this is done is to look in longer wavelengths of light so if I show you this image here in infrared light a lot of that those dark patches go away and we see the stars a behind and this is due to the fact that longer wavelengths can more easily pass through a gas atoms and dust.

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And if we look in radio wavelengths down at the very central region of central few 100 light years in the galactic center we do instead see that there is quite a lot going on there those little bubbles that you see are supernova remnants though they are the little popped bubbles of exploding stars and you see various gas moving around and in the very central region where you see s g r a that subject areas a there is a.

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Source of radio emitting material that is interacting gravitationally in the vicinity of the black hole so the location of the galactic center is in the constellation of Sagittarius so you're ever out looking at said it areas you can imagine you're looking towards the super massive black hole Ok so how are we going to find the black hole so.

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If there are stars orbiting a black hole in the galactic center which there are are they will move similarly to planets orbiting the sun we have a smaller star orbiting a more massive black hole and in the lower left there you see the speed of planets versus their distance from the sun and the closer in they are the faster they move so we would want to measure the speeds of the stars in the vicinity of the black hole and we also expect that the orbits will be elliptical with the black hole being the center of mass at one focus and on the lower right there you see the the orbits of some of these stars that are in fact revealing the black hole but this poses a technology challenge because these stellar orbits are around a black hole that is 25000 light years away and if you look at to the scale on that figure in the lower right that's a fraction of an arc 2nd so there's 360 degrees in a circle 60 minutes in a degree in 60 seconds in a minute so these are very very tiny positional changes that you're going to have to measure very accurately in order to identify the black hole and this is what the team who are 2 teams excuse me who won the Nobel Prize did so beginning in the 1990 s. But Ronald are gentle with his Researchers in Germany and under against begin developing the technology to do this and initially a method called speckle imaging was used though if you look at that little animation there this is a star twinkling Why does a star twinkle because the light is passing through the atmosphere there's all sorts of air currents.

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Moving around that distort the image the image of the light and so if you were just to take an image of a star it would be kind of spread out and you wouldn't necessarily see those small changes in position so what they did was they developed this method of taking multiple short exposures and then you combine them together in order to reduce these these twinkling effects and you see on the right there a figure from one of the new I guess his initial papers showing the resolution of stars in the Central where arcsecond of of the Milky Way and 0 on the bottom there you see the.

[00:47:03]
The 2 observatories where these 2 teams were carrying out their work so it's good to have 2 competing teams and they really spurred each other on in order to make sure that the method is working that the data are good the observations are indeed showing what we see.

[00:47:20]
Here are some early results so this is from 1907 from Gensler's group and what's going on there in the lower left you see those arrows are measuring the loss of these of the stars how they are how they're moving in the sky and in the upper right you see something that looks very similar to that figure about the planets the closer in towards that a terrorist a star the location presumed of the black hole the faster they go so you know.

[00:47:49]
All right but there there was a limit to that so you have to take lots of short exposure images which limits how faint an object you can see you need to have plenty of time on your telescope and so in the early 2000 another method tain into into use which is called adaptive optics and the way this works is.

[00:48:15]
You have a deformable mirrors of the mirror in your telescope and shift to counteract the portion of the atmosphere and remove the twinkling of the star though there is a laser guided star that simulates a start the telescope can then adjust itself out of a simplified way of putting it but we're running out of time so in so doing it's 10 in the same way remove those atmospheric effects and make a precise location of the star and also that light from the star can be fed into other types of instruments so for example you can measure the Doppler shift of the stars and see not just how they're moving sideways on the sky but moving towards and away as well and here is an illustration from Andrea guesses group showing the improvement in resolution that you get with with adaptive optics and notice these images are taken at wavelengths of $2.00 microns so in the infrared and here is the famous movie.

[00:49:28]
Move there we got a notice in the upper right these are the dates the beginning from the mid ninety's on into 2000 and those little blobs are the stars tracing out a beautiful elliptical orbits the actually. Come around again and the location of that little cartoon star 2018 that close in Star made its made its closest approach that star called s o 2 or as till the Let us watch one Perry center passage this is amazing so what do we see we see luminous bodies revolving around a center of mass which is not a luminous body this is the deeper massive compact object in the galactic center.

[00:50:22]
Ok so from those elliptical orbits you can calculate what the mass is this is freshman physics and it's a little over 4000000 times the mass of the sun there is no 4000000 solar mass star doesn't exist anything of that mass is going to collapse into a black hole and so that gives its Schwarzschild radius or event horizon size and to be about 13000000 kilometers which is about $800.00 times the size of our sun So imagine 4000000 times the mass of the sun within a volume nearly 20 times.

[00:51:00]
Within a a distance of about 20 times from the center of our sun so incredibly compact and you know to the citation the discovery of a super massive compact object there is no other known object at this time than a black hole that can account for such a massive compact object it's a black hole that's that's my personal opinion the that's a story that you saw s o 2 or s 2 its closest approach to the black hole is 1400 Schwarzschild radius.

[00:51:39]
The way for thinking of exploring what happens when something crosses the event horizon what's the nature of space time at the Schwarzschild radius itself where the strength of the gravitational field is profoundly strong these stars are nowhere near right we're using freshman physics to check it up but that's a that's a bit over overstating it but in fact these stars do not get very very close and so there is still some open question as to perhaps there's another description of a compact object from some other physical theory which could account for it as well a hence the hedging language right there.

[00:52:17]
Ok so if there's no $4000000.00 solar mass star reared a $4000000.00 solar mass black hole come from and this is an active field in in theoretical astrophysics and we imagine as the galaxy forms there some gas in some dark matter never mind about dark matter at the moment and there's various paths you might have a few stars per galaxy that collapsed to a.

[00:52:43]
See black hole we might have an initial black hole formed from gravitational collapse and we might get a star cluster forming this is the lower sequence but in any rate we will always end up with a speed black hole which over time during the quasar phase as mass falls across that event horizon it doesn't come back out so it increases the mass of the black hole it grows the black hole to this.

[00:53:13]
Ok here are some beautiful images of the Perry center the point of closest approach of s 2 in 2008 team and when these teams analyzed the data they were able to confirm several predictions of General Relativity a with the star coming back again they could measure the precession of the orbit to the fact the orbit changes orientation in this in space and you may have heard that one of the 1st successes of Einstein's general relativity was to explain the precession of Mercury's orbit around the sun so we see this here as well likewise when the light moves away from a massive object it loses energy like we throw a ball up loses energy and that causes the star the light to be gravitationally redshifted in this was observed as well but as before the closest star is not quite.

[00:54:10]
In the general vicinity of of the event horizon Ok so what can what can be done that they will continue to monitor these stars obviously because the more precise the measurements the more precise they can correlate the measurements with these various predictions of general relativity also there's a lot of gas there so we do see sporadic flares from gas and other you know streaming.

[00:54:38]
We see superadded players from gas falling into into the black hole that come from much closer to the event horizon and then also the as we heard a couple years ago at the Event Horizon Telescope was able to image and event horizon shadow in another galaxy in the galaxy and the $87.00 they also took long observations secretary is a star of this black hole and they're continuing to to analyze that data so perhaps we will have unforseen surprises and new physics as we probe ever closer to the monster in the heart of our galaxy Ok so that's all I have to say I'll close this out and send it back to our moderator Great thank you Dr banning we have a few questions that cropped up in the q. and a so I'll read them out loud for those that are maybe just joining through mobile and can only listen.

[00:55:39]
We have Victoria Archer's asks How does this new theory apply to the Big Bang Theory can we finally say the Big Bang theory is bogus that's pro-drug. Area where I never thought I'd mention the Big Bang at all. I don't I mean by simple question 1st of all I've got good old.

[00:56:12]
Boyfriends but I don't really know Big Bear or. M. goes. I do is evidence for this creature in the race so I. Think. Cosmology to date so the response. That's your. Speculation starts off. Yes go. No. Quarterly thing goes on just to school. Rock. You know very very old place or where you just call them.

[00:57:07]
Very much. All right let's see David Lloyd George asked when calculating the orbits of the stars in the animation you showed our relativistic corrections needed at all or are the stars far enough away I'm guessing that you can he They're asking if you can just use the freshman Newtonian mechanics that you referenced or does that do some of the stars get close enough that you have to compute their orbits relativistically.

[00:57:43]
In general no though these things are thousands of short children away away from the black hole and Newtonian physics will will suffice now as I mentioned when that close in Star made its closest approach to the black hole there were relativistic corrections observed so when they would compute the Newtonian solution and subtract it out they would see some deviations from that indicating the existence of precession and I'm like well gravitational redshift so the star as it goes around it's coming towards and away from us so we're going to see the normal Doppler shift but we also see the relativistic Doppler shift for that for that one close in star at its point of closest approach it was detectable for the other stars.

[00:58:33]
You know that's there they're far enough away that you don't need to worry about it. Let's see the next question and I'm sorry if I mispronounce her name assumed chemical or ask how powerful direct telescopes need to be in order to measure the position of s o 2.

[00:58:54]
And I'll take that because image is one of my students over at Emory so I was going to get to see you and this question about how powerful due to the telescopes need to be asked what do we mean by a powerful telescope so what makes a powerful telescope is that it can see something faint and it will be able to see something faint if it collects more photons so the power of a telescope is related to the size of the mirror the buckets that collect the light and in the case of these of these observations they're using 8 meter class telescopes so the diameter of the of the cap telescopes for example that the guest group is using is about is that 8 meters and there are very few of these telescopes in the world and time on it is incredibly competitive leaf fought for but is that.

[00:59:44]
I was you know is that the largest telescope in the world right now at the moment so there are even larger there are 30 meter class telescopes in develop in development one of them if you are aware of the controversy of building more telescopes on top of. One of those is the proposed telescope and then there's another one in the southern hemisphere so not yet that's kind of the next stage in telescope development Ramon Franco asked What is the **** radius in this case where children's court records this.

[01:00:26]
Problem of the black hole there are. Some pair of are going to go through various. Or you have a much more interesting answer I'm just going to tell you how many kilometers it is so if the question means What's the short chilled radius of the black hole at said Sirius a star on the marble the article or rather the galaxy about 13000000 kilometers so there's a really nice trick for calculating the Schwarzschild radius of anything that you're interested in is you take the mass in terms of the sun so the sun would be one solar mass and you multiply it by 3 kilometers though if the sun were to become a black hole we would have to compress it within a radius of 3 kilometers so take any mass you like take your own mass and convert it to solar masses multiply by 3 kilometers and that will give you the Schwarzschild radius of of anything you're interested for said a star it is about 13000000 kilometers which is well within the orbit of Mercury if we're kind of comparing it to the Solar System little bit larger than the sun well within Mercury's orbit right thank you I'm not sure I did notice this on one of the slides but I don't remember which one of you showed it j.f. asked what is a white hole.

[01:01:42]
Now during your theory just. Notice the white hole Yeah it comes out of the I showed it it shows up in the Penrose diagrams if a black hole is something that once you cross the event horizon you can't get out a white hole is the reverse it's something that once it comes out of the white hole it can't go back in so incidentally it was originally a kind of in the more speculative corners of of astrophysics like the bars in conferences the idea that quasars maybe they're black holes are producing so much energy maybe there's energy coming out from a parallel universe away whole a 2nd went the way of sort of science fiction that's mathematically what a white hole is it's basically the inverse of a black hole but there is no there's no astronomer of any sense who thinks that such things could possibly exist there's no formation mechanism there's no there's no theory for why they would actually be there.

[01:02:40]
Ok project you have to answer this one how is the weighting of the Nobel Prize determined like why does some people get a half or a quarter. The Nobel Prize but itself it's a random process because they're told every moment this sort of market actually struck you. About the recipients.

[01:03:04]
In this particular case the bill comes after fell so you're also a very. Important serious court where you're Because all of your contributes and it's all because the bill prices wait until almost 0 to 0 it's so gross it's very serious serious fault I got it right so there is often experimental science about there to.

[01:03:31]
Their very own Well I think it's very clear we're. All recognize. Great Klink you. David Lord Lloyd George asked again do they use interferometry between multiple telescopes. I do you know I don't believe so but I am not positive Yeah I don't exactly know the answer to that I don't I think they're just simply taking.

[01:04:07]
Taking images with the single the single telescope but I don't I want to I don't know. Come all Sharman asked Are there any results obtained by using Penrose's repeating universe theory perhaps in simulations Well I suggest you wrote a book about. The Some well. Explains you know there is evidence there's always.

[01:04:46]
Feels. Sort. O.. My going. Rate that looks like. I believe all of the questions have either been answered in the Cuban exile or have been answered verbally just a moment ago so like to just take a moment to thank both of you for all of the time and hard work you put into this it was very enjoyable.

[01:05:23]
A virtual talks each get one clap instead of $230.00 or so which is I believe what we had. Professors with on a **** has promised to upload his slides from his half of the talk on to the chaos book website was that correct. Yes By course and then by some I don't call them 6 when I'm trying to.

[01:05:49]
Really Think. Reality I just want to express themselves you know that's. All I do listen. Well. They're. All right so it's right to. Expect And we have recorded this talk so if there was something that you wanted to go back and watch again or a slide that you want to deposit on you're welcome to do that though it will take us probably a few days you haven't show up on the Georgia Tech College of Science youtube channel Well thank you again it's been a great talking a fun evening and thank you to everyone tending Yeah you're right.