Hunting for Black Holes, with Janna Levin - StarTalk All-Stars

this is Startalk welcome to Startalk Allstars I'm Jan 11 and I'm your all-star host today I'm an astrophysicist and author but nowhere near as interesting as my co-host the incredibly talented Matt kirshen Matt welcome to New York hey thank you for welcoming both here onto the show and for pointing out that I'm more interesting than enough surfaces and that's right and we're gonna hold you to that for the rest of you who are interested also in the studio we have special guest Shepard Dolman who has a long list of accomplishments including getting through graduate school at MIT same year as me getting me through general relativity Shep is an astrophysicist at the harvard-smithsonian Center for Astrophysics and the director of the event horizon telescope project event horizon telescope is a fantastic project not yet complete still under development it is a telescope essentially the size of the entire Earth that is going to try to take the first real picture of a black hole very exciting stuff so this is what we're going to talk about today good day's work if we can pull it off it's a good day's work so we're we're gonna be talking about black holes how we observe them so far why we think they're real and what it would mean to take a real picture of them for the first time so Shep thanks so much for coming making the trip from MIT from Harvard thanks for having me it's a pleasure today we're going to delve into one of the weirdest and sort of most exciting topics in astrophysics everyone loves to talk about black holes and in particularly how we observe them but first let's just start with you know what is a black hole Shep I get it I see how things are someone's already playing favorites I didn't go to school with you you just go to Shep to immediately ask about black holes yeah you didn't graduate from MIT have a beaver on them yeah the beaver ring is the MIT class ring industrious and why you're calling I know all right face says it all oh because a building thing is all right that makes it almost sense build telescopes P image black holes that's what yeah so black holes so black holes what are they and I think well everyone has some idea of what a black hole is but essentially it's when gravity's run amok it's when mass collapses in on itself to the point where gravitational runaway is inevitable and nothing can keep matter from infalling to a singularity to a point and the interesting and defining thing about a black hole this is what we all probably know about is that there's this membrane called the event horizon around the black hole and that's the point outside the singularity where gravity is so strong that even light can't escape and then hangs off to the movie the other way around actually you know but it's it's what most people think about when they think about the event horizon the movie and the spaceship that went into hell and then came back out haunted so the event horizon means no events that happen on the other side of that line will ever be known to you so it separates Causley right two parts of space okay so it's been actual membrane it's not an actual membrane it's just a region of space-time that demarks where gravity is so strong that the escape velocity from that mass is the speed of light once you pass through it you really can't get back out again if you could actually stick a light pulse right at the event horizon and racing outwards at the speed of light it wouldn't go anywhere it would just sit there it's refrozen it would be yet just hovering there it's as though almost as no space times falling in like a waterfall so what would you see if you were actually right at that event horizon you would pass the light pulse and think it's traveling at the speed of light so but this is a good question Matt because you say matter is a dense you know crushes under its own weight a big enough star will crush under its own weight eventually so is there stuff there like people think of a black holes this incredibly dense object so when I cross the event horizon like Matt asked is there anything there usually there's nothing there yeah cool like the ones that are in the center of our galaxy or in other galaxies you just pass right through the event horizon like it's not there or you can't get back out again it's one of these strange things that's why philosophers get very dreamy when you talk to them about black holes in a way that they don't when you talk to them about stars because world lines can go through the event horizon and you don't know what Bin's it's a world what a world line is where you are following space and time on your own trajectory and I go from this point to that point from point A to point B but if point B is inside the event horizon you can't get back out again so you can't tell your friends where you are or how you got there yeah you know how Google Maps plots your spatial path they should do a spacetime diagram all right so the world lines your path through space and through time but sometimes it gets it wrong and it picks like the wrong Massachusetts or whatever and then it says you need to take a boat and then you need to take a left turn right and then a boat and then you'll never escape but the thing about the GPS units is they do actually have to correct for relativity to get your location right on the map so our clocks run a little bit slower here on earth than they do say at the satellites and so they have to correct for that time difference the fact that our clocks are running slower they were aging slightly more slowly in order to locate you properly on the earth so and that's hugely interesting right because Einstein developed this theory of general relativity in 1915 over 101 years ago and sometimes I imagine going back and talking to Einstein and saying here professor Einstein you know you know 100 years from now I don't have to put on the voice I have to put on the voice and I don't put on the voice isn't sound good right so you go back in time you say to Einstein you talk to everyone in the accents that they have are you gonna start speaking British to MIT but you you you talk to Einstein you would say a hundred years from now Corrections that you discovered will enable me with my phone to take down links from a constellation of satellites around the earth and pinpoint my location to anywhere on the earth and of course he'd be very excited and he would say what's the phone we've our technology has gone so far beyond what Einstein had that the first thing he'd be interested in is or what's a phone and that he wouldn't he refused to memorize his phone number because he said why would i memorize anything I could look up like hi clutter your mind here's Brian Stein you can get whoever the lowest yeah well he also said when I was a student I was no Einstein so how do we know that these Weinstein does that make us kind of on a par that's right it works in both directions also I don't know why it's nice phone number so exactly so actually clearly very similar wouldn't have had a phone number maybe so maybe this is one of those apocryphal stories that I'm propagating without having properly so black holes Einstein understood the mathematical solution but he wasn't sure that they were real in fact he sort of thought nature would protect us from their formation I mean after all I can't crush this desk very easily it's very very hard to do I mean it's hard to fold a piece of paper more than what's the number 11 times or something it starts to really fight so he believed quite sensibly that nature would not allow something to collapse all the way to a black hole and there were decades between that time 1916 this this guy in the trench is an infantry soldier on the Russian front you know is calculating ballistic trajectories and writing to Einstein naturally and he wrote down the first solution for a black hole do you know when it got its name the black hole people schemas wheeler wheeler also a Princeton guy yeah it was 67 and I I'm not gonna tell you I know your chef was warned and he was tired of saying in state of complete gravitational collapse apparently so someone from the audience shouted how about black hole and the name stuck that's 50 years right 50 years it took for people to really start to believe that black holes were real so why do we believe they're real now well it was well the way I think about it is that for a long time people didn't think that anything could be much denser than water right so if you take our Sun that the average density of the Sun is not too much more than water given its volume but you could fill the whole volume of the Sun with water it would weigh about what the Sun ways and it wasn't until people found white dwarves which are very dense in states of stars like cinders of stars it'll be the end state of our Sun for example and neutron stars that people began to really you know think that matter could be compressed to extreme density just to be clear this is scientist so you didn't think things could be denser than water not just like people in the pub theories like I remember my friend Jordan telling me when we were 8 that the way we could travel faster than light is I mean if you if you saw the end of Jaws but like the way that the canister of like exploded in the shark's mouth was so powerful and he's like that's a big an explosion as you can get and that'll get us like faster than the speed of light and it turns out G was wrong Jordan's one of those people apparently who write me those you know their theories of everything look I'm gonna search for the name Jordan yeah my crazy phone always get these letters that say I ain't got it wrong by a minus sign and here's why although he did have a minus sign error in some of his first papers he yeah but not in relativity I mean he made mistakes he wasn't really afraid of that I mean it this stuff is you know it's not written on a tablet somewhere it takes some trial and error but sorry was there more to Jordan's theory no that was mostly in we should just call it Jordan's theory basically anything that can explode a shock is gonna be pretty powerful well actually it's quite amazing they really needed to understand the nuclear physics that goes into the bomb technology before they were sophisticated enough in their understanding of small scale matter forces to realize that the black hole would form so mmm so all these guys really did work on the bomb but on that happy note and we're switching to cosmic queries Matt what do you got okay so on that note here's a question from a victor firt and back on Facebook who says well from Stockholm Sweden as well is it possible to kill or destroy a black hole a black hole hunt like words putting a compressed air canister in the black hole's mouth and then shooting it from the boat I think it's shark could easily write like how to beat a black hole yes it depends on what you mean by destroy well black holes will evaporate by themselves if just left to their own devices all right and that's because there's something called Hawking radiation so the boundary of the black hole this event horizon is a turbulent place and you can get particle and pair production right and one particle will go into the black hole and one will go out of the black hole from a distance it looks like the black hole is giving off particles slowly evaporating over billions of years a stellar-mass black hole can just vanish alright that's one way to get rid of a black hole just leave it alone wait for a very long time ignore it right now the light left over from the Big Bang is hotter than all the Astrophysical black holes we we think we know of so that the black hole's right now are absorbing the light right from the Big Bang they're not emitting it yet in a long time though everything will fall into black holes and then all those black holes will live a bit longer if this black hole is currently terrorizing a seaside town like this is not the approach that you want yeah that would not be a good yeah protective mother measure yeah that wouldn't work but also a shark sized black hole would be a shark masked black hole be really tiny can you make that can you have a black hole that's not sighs oh sure so if you had a black hole that was the mass of an asteroid for example let's say a hundred trillion kilograms it's a good sized asteroid it would be smaller than an atom so wouldn't terrorize the town it would just drop right to the center of the earth because there'd be no support for it well you know we don't actually know how to force an asteroid to become a black hole but there was a direct pressure but in the Large Hadron Collider people were afraid that by smashing particles together one of the byproducts was going to be subatomic sized black holes and so people did try to take an injunction against turning on the Large Hadron Collider now I remember that being a thing did any mini like micro black holes actually get created and if so what happens awesome no one were to happen it would actually do bad things like you even if it is it wouldn't actually so physicists just are never willing to say never they're only willing to say it's very very improbable so the argument was black holes could be made depending on whether there were extra spatial dimensions and what gravity is really like at higher energies but if they were made they actually evaporate through the process Shep's describing much faster than big black holes the smaller the black hole the faster they evaporate so the idea was they would just be gone in a flash they would be like an explosion they're tiny they burn brightly yeah at least that's the theory so the other thing that that people should feel safe about is that nature has already done this experiment for us so people worry about CERN and the Large Hadron Collider slamming particles together to make a little black hole but cosmic rays hit the earth all the time and they're hugely high energy they're higher energy you can make in the LHC so they're slamming into the earth all the time and they haven't made a black hole yet the devoured the earth maybe they made a black hole but every black holes have these tiny little mouths right they're like huge animals but with tiny little mouths right and so it's very difficult for them to eat Humminbird exotic object world so do we have some more cosmic queries yeah so again and I think this question might turn out to be slightly off in terms of the way it's phrased but hunts 105 on Instagram I don't know how you asked a question on Instagram I don't know whether this is just done by posing for a picture conveys this question better holding up a cardboard hunter from the United States says how close with a black hole have to be in order to see it with the unaided eye hmm you'd have to see the shadow cast cuz that's all there is to see so one of the mysteries of black holes that maybe we'll get to this later but this is the perfect time is that by definition you can't see them by definition all the action happens within the event horizon once things fall through even light you can't see it so why are black holes actually some of the brightest things we see in the sky that's because all the gas and dust that's being attracted to the black hole is trying to fit into this impossibly small volume and just as when you rub your hands together they get hot the friction of all that gas and dust madly trying to get into this teeny little volume heats everything up to hundreds of billions of degrees see what you're seeing is everything clamoring to get into the black hole rather than the actual black hole itself yes it's like you know like the line outside a nightclub something's happening inside there and it's pretty special but all you can see is like this big exciting line outside and the bouncer is kind of like the heat keeping people everybody oh right right but then you think you know right maybe it's all hype so what Shep wants to do is take an actual picture of the shadow so that's something amazing but to see the shadow means there has to be something bright behind it so if the black hole is just against a dark sky there's no hope of seeing it even unaided but if it was had the Milky Way galaxy shining behind it you would see a sort of lens image of the Milky Way and that's how and you would see the shadow so it's an interesting question how close wouldn't have to be so a black hole the size of the Sun is about six kilometers across so how close would six kilometers have to be Shep do you think to be able to see it in the case of my eyes like right here it would be like within the solar system like so if you're out if you're if you're out in the orbit of Pluto for example and you look back to the Sun it you can't even see that right right oh you have to be well within the orbit of mercury I would imagine to even see this kind of thing well so Sebastian dubis on Facebook says where is the closest black hole and could we send something to orbit around it well that's a great question we often joke that the best way to study a black hole is to send an undergraduate with a laser pointer to nearest black hole and throw them in right and then as they go in the laser of course would be Doppler shifted and right they totally passed the course okay yeah that's good well the nearest one is just like a few tens of light-years away I think exceeding the six one is that's that's one six thousand light-years away Oh fact-checkers is there a black hole at the center of the Milky Way he's absolutely a black hole that's farther away than the nearest black hole that's about 25,000 light-years away okay so the nearest black hole is that also part of the Milky Way or how does this okay yeah so there's a hundred billion stars in the Milky Way and about a million of them what'd I say a hundred billion about a billion of them actually will one day become black holes it doesn't mean that they all are now so there's a lot of black holes just speckled around the galaxy a lot we may talk about this later but the black hole the center of our galaxy is one of the only ones that we can hope to resolve with any kind of astronomical instrument so the kind of telescope that Janna was referring to before the event horizon telescope can just make out the four million solar mass black hole in the center of our galaxy this is a perfect place to break because we're gonna come back to talk about the event horizon telescope and how it's going to resolve that shadow and the excitement of that project so we're going to take a short break but stick around so we can talk more with Shep and about event horizon telescope on Startalk all-stars welcome back to Startalk all-stars as we continue to talk about black holes and event horizon telescope I'm your host Janna Levin and I'm very excited to have my wonderful comedic co-host Matt kirshen Jenna hey Matt a long time no oil in a few seconds and our science guest Shep Dolman Shep is the leader of the event horizon telescope project so tell me a little bit more about event horizon telescope so the event horizon telescope is a project dedicated to the notion that we can see something that we've always been taught is unseeable right so everybody knows that a black hole is something that absorbs light matter nothing come out from the event horizon once it's gone into the event horizon but because all the gas and dust is heated up and you get this effective three-dimensional flashlight all around the black hole illuminating it from all angles you can see its shadow or the silhouette that it casts against all that hot gas so what about interstellar do you know how an interstellar they show the disk around the black hole but you can kind of see it above and below do you think that was a pretty accurate portrayal I think that's very accurate right so because it turns out that just like water going down the bathtub drain everything kind of falls into this pancake shape that's swirling around the black hole it makes like a disc like holes spin the other way around in Australia that is not true actually all the toilets do also checked yeah it's one of the great experiments of our time we can get toilet bowls astronomers spent a lot of time looking at toilet bowls but the point that Jana is talking about is quite true there is no behind of a black hole right so that's it that came out wrong didn't the anything that's behind the black hole by definition gets bent up and around so the light rays from on the other side of the black hole get bent up and around so you have this pancake object and you're seeing the rear side of it flipped up yeah I always stole this line from you Shep you you you once said you can't hide behind a black hole and it's actually a great description you're crouching down behind the black hole and they can see you one step too close you're in the black hole I should've done that I should have paid attention in asteroids class Rosie reads on Instagram what is the telescope made of oh what a great question so so first of all black holes are extremely small they're the smallest objects theorized by Einstein's gravitational theory and so to see them you need a large telescope cuz the larger the telescope the smaller the object you can see on the sky so to do this we take radio dishes all around the globe and we synchronize them with atomic clocks we point them all at the same time it's kind of incredible when you think about it but they swivel at the same moment look at the black hole take radio wave data from the outside of the event horizon of this black hole and they record it on hard disk drives we essentially freeze the light everywhere around the globe and we bring them all back to a specialized supercomputer that compares them all it operates exactly the same way that an optical mirror does for an optical telescope so for an optical telescope the light rays hit this perfect paraboloidal shape and they focus it all to a point where your camera sets all the light is focused to a point in the event horizon telescope we replay all of these recordings that we've made all around the earth and we adjust the timing of them to make it seem as though there is this huge dish the size of the earth and then we synthesize this focal point and that's where we make the image so the whole earth is a telescope well well telescopes around the earth for night so it makes right it makes this like giant machine so how big I mean I remember this comparison if you resolve the shadow of the black hole from the supermassive black hole at the center of our galaxy which is how how big is it again it weighs about four million times where our Sun does and about how big across is it well on the sky it measures about 10 micro arc seconds and the shadow would be about 50 micro arc seconds this is the same as trying to observe your favorite citrus fruit on the moon jello you know a pomelo I don't know if you have a favorite citrus for it it does sound weird and I'm disappointed have you looked for it in the past because it comes up a lot like you know what is just like them all the same and then we have to choose matte you have to choose like one of those parents who like you can't love all of your culture in the same way I just don't have a favorite amongst when you next go to the moon I want you to put one that you chose on the surface of the Moon and we will try to resolve it with event horizon telescope for gags someone that doesn't have it's like resolving a quarter on the moon is that the same almost is so it would be a citrus fruit on the moon it's bigger than a quarter or huh if you were in New York now your friend was in Los Angeles holding a quarter it would be equivalent to reading the date on that quarter and that's what you guys are trying not to we are trying to do so much of being a professional scientist is coming up with different sized analogies it'd be like if Pluto were a baseball like your hand was Alpha Centauri and your dad was throwing Pluto from you just seems like there's a lot of that like we are poles and whales and fruit as hamsters have a trail okay this black hole which is four million times the mass of the Sun probably fits in about three Sun widths is that does that sound like about right no no it's about play about the event rise will be about a third the orbit of mercury Oh so that's actually cuz it's four million times oh yes kilometer or figure that you gave before so it's quite large yeah so it's quite large but it's twenty-five twenty-six thousand light years away exactly so as I said black holes they toss your stars around like planets you know the supermassive ones they're hugely dynamically important but the the largest one that we know of that's close to us is twenty-five thousand light years away so it's not gonna hurt us we're not in any danger we are falling into it just really slow very very sick much worse things are gonna happen to us in the next ten years but not to get off-topic so this is a the biggest black hole in our galaxy it's at the center of our galaxy and we think that there are black holes this big in all the galaxies more or less do we have any aspiration for observing the shadow of taking a picture of the shadow of another black hole supermassive black hole in another galaxy yeah so it turns out there's one other wonderful candidate for doing this so that the number one target for us is the supermassive black hole in the center of the Milky Way galaxy a star which is called Sagittarius a star in the constellation Sagittarius and the other one is in the Virgo a galaxy and that weighs six billion times what our Sun does you'll monster it's a huge monster it's a thousand times more than a thousand times bigger yeah it's about one and a half 1,500 times it was part of the Milky Way different galaxies holding galaxies and so that so it the only reason why we have any hope of resolving that is cause it's so much bigger even though it's much further away how much portion also it's about 1,500 times more massive it's also about 1,500 times farther away looks about the same on the sky so a telescope with the same magnifying power would see them both about the same size so you're basically building a telescope the size of the earth to take the picture of two things I'd like to see it this way if I were to be trapped on a desert island with two targets these would be the two targets right so we have one that is kind of a rosetta stone if you will or it's an exemplar of most of the supermassive black holes in the universe they're nondescript in smaller galaxies we wouldn't see them if they were our black hole it's just not bright it's not bright because it's just not taking anything down right now it's on a starvation diet it's it's kind of eating with a you know a teaspoon and so it's not it's not that the gas around it is hot but it's not enough to really be seen from very very far away whereas the Virgo a the supermassive black hole is is much much brighter and that's driving a jet of relativistic particles from its North and South Pole that's literally piercing the entire galaxy now is that because we're seeing it in the past when it was more active well well is it not that far away it's about let's see it's about 18 17 mega parsecs away some million years away really old enough it's not too old we're probably seeing it as it's eating as it's driving these jets from its north and south pole through the galaxy so in the past was our black hole at the center of our galaxy bright Oh almost definitely so there's probably some alien civilization on the other side of the universe where the light's taking billions of years to get there that thinks that our black holes like a quasar [Laughter] this is the best universe in which this show is going the best oh I feel like Trump it's the best it's huge and it's the best the well what I'll say very briefly on this is that about 300 light years from the center of the galaxy they see these wisps of x-ray light and they think that what causes that is that 300 years ago there was a burst of activity in the center of our galaxy and the shock wave has reached the clouds that bound that area and it's fluorescing so speaking of which we're seeing the black hole 25,000 years ago as it was then so wasn't there this excitement for a while that a cloud was about to be torn apart by the black hole g2 thats cloud 2 and we watched people watched it for how long were they watching this gas cloud yes so there was a gas a cloud of gas that they thought was about 3 times the mass of earth and it was falling into the black hole and knew they knew was falling in because it began to be tidally stretched so the front part of the cloud was feeling more gravity than the rear part of the cloud is being sure it's like streaming out right right it was like the exciting bit when you're watching the water drain out of the bath like when it just suddenly it's the only fun part of that that watch but in any event people thought there was going to be fireworks that were gonna be fireworks and we haven't seen anything it's been the biggest dud alright so what do you think happened well just not fall in a lot of it depends on how you engage the black hole so if the black hole is spinning this way and you're coming in counter to that rotation you could get a lot of fireworks but if it's spinning in the same direction as you you just be sucked along with it yeah and it might take a long time for the gas that you're contributing to the black hole to find its way all the way to the event horizon where would light up yeah let's be clear if I were to fall across the supermassive black hole in the center of the galaxy I would not be torn to shreds I would just drift across right happily because I am we compared to the size of you man horizon Matt what do we got so call us on Instagram is saying will this telescope be studying the effects of Hawking radiation probably not so lucky Kyle it's a great question protect Kyle from a Matt here it's a great question we know that Hawking radiation exists but the event horizon telescope is going to see this outline and Hawking radiation is not likely to affect that outline there are some cases in which it might there are some quantum effects that might affect the shadow size and that's an active area of debate right now but Hawking radiation itself is something that happens over very long periods of time and so we probably wouldn't see that dynamically affect the shadow you know I should point out that we are getting cosmic queries from our audience through social media so next time tune in and send your questions ahead of time and we may or may not actually get to them yes so um leigh jackson on facebook asks could the Big Bang be the birth of a black hole and are we all living within a black hole hmm I almost think it would be the other way around people have speculated that the black hole could Harbor a big bang inside so the black hole is much bigger on the inside than it is on the outside it could be as big as a universe on the inside it's like doctor who's TARDIS you know you come in a small little red box but inside is an enormous lab so you fall into the black hole and you think you've got a microsecond before you hit the singularity but your quantum bits get blown out into a Big Bang so the second part of that question web blasts says all we all living within a black hole we could be like well this could be them when we look back at the Big Bang we might be looking back at the singularity inside a black hole in that sense it's not really inside but in that sense yeah although most people don't really take that speculation very seriously it's it's it's intriguing to contemplate I always find myself kind of going back to that suggestion no matter how many times people tell me why it's faulty or what the problems are there's something appealing about that well there's something interesting about the singularity being in every direction right so the the big bang is everywhere you look alright so in that sense it is not unlike a black hole yeah the singularity of the Big Bang and the singularity of a black hole are so similar that people have just kind of tried to artificially sew them together like a quilt and see if it matches on that same note Dale chess lit rose on Facebook says if sounds needs air to pass through did the Big Bang actually make a noise yeah well we're gonna talk about this in a gravitational wave home episode in a sense the Big Bang probably did make a bang in the sense that it rang the drum of space-time we're you know you imagine three-dimensional drum of space-time is ringing in response to this kind of chaotic event so in that sense it might have yeah made in a sense a noise that if we could record the shape of the ringing drum we would interpret a sound okay even in the absence of air it changes its shape slightly and that changes the gravitational waves that it's emitting and also around the black hole via the accretion disk can support sound waves can't it so this disk that you were describing of all this material falling in around the black hole and flattening it out it can have a sound wave through that material as long as you as long as you think of sound waves not as being something we can hear with our eardrum but as being waves mediated by some kind of medium like gas and dust it's based on like a Brooklyn DJ it's just not something you can appreciate through your ears but it's also just about just the feel of the space time you know anyway here's my disk important question also coming from Nick's spinel on Facebook and I don't know which of you two is gonna be the best to answer this can we send Hillary and Trump to a black hole but they might in Aisle eight each other a boom they got there then well use the interesting thing about black holes no matter how you feed them they all look the same so you can take a black hole and you can fill it full of Hello Kitty dolls you can put old rusty refrigerators in it you could throw Donald Trump into it you can throw Hillary Clinton into it and after it's done settling down you would have no idea what went into it this is kind of deep there is no way to tell the difference between a black hole made by crushing Donald Trump to a point and that made by crushing Hillary Kent Clinton to a point all politicians are they say just a Massachusetts would vote for one or not the other that's the only way you can tell so do we have a last cosmic query in our final few seconds last minute at least on earth let me see-oh you from the International Space Station to last longer this is a is there a correlation between the law of conservation of energy and the fact that time stops at the speed of light does this have to do with light having no mass because it is pure energy says Jacob Seymour Facebook um do I read that again yeah okay so I'm gonna try this anything that has no mass will travel at the speed of light anything so we think that there might be subatomic particles that like neutrinos some neutrinos which might also have no mass and they would have to travel also at the speed of light and and their energy can be converted to MC squared equals MC squared energy but it is a pure energy of kinetic energy one way to think of a equals MC squared which I've struck upon lately which I really like is to think of it as your kinetic energy through time the amount of energy you transport by your motion through time so if we were to draw those space-time diagrams when you're running in your Google Maps you know you have some energy as you move through New York City but you haven't plotted your energy as you move through time and that's equals mc-squared energy and on that note unfortunately we have to take a quick break but we'll be right back with star talk all-stars so we can answer some more of your cosmic queries with Shep dolmen and Matt kirshen stick around welcome back to Startalk Allstars where the topic of the day is black holes how they work and how we hope to take a picture of our first black hole I can't think of two better people to talk to on this topic than Shep Dolman and astrophysicist and leader of the event horizon telescope project and the very funny Matt kirshen who also hosts probably science probably not science just probably science that's what it is I'm Janna Levin your all-star host for today and I want to pick up with Shep on the event horizon telescope because this is still a project under development you're talking about we will observe we hope to observe and there are these two objects so first of all when do you expect to start making these first pictures of the black hole at the center of our galaxy and why are you going to do this good good questions so we started off on the event horizon telescope project by linking three radio telescopes around the world together in Hawaii in Arizona and California and the first thing we realized was that the supermassive black hole in the center of our galaxy Sagittarius a star had a size that was predicted by this shadow feature so a hundred years ago Einstein came up with this idea that black hole would cast a shadow and we saw exactly that size and that really got us excited right because with only three telescopes all we can do is tell the size of the black hole now we want to build instrumentation and put it at all the other telescopes that we can around the world to fill in this earth sized telescope and then we can make an image because the whole reason for doing this is to look at the size and shape of that shadow predicted again by Einstein to test whether Einstein's theories break down at the edge of a black hole and also to study the dynamics of matter around the black hole now will you really be looking all the way at the event horizon I mean after all light can orbit a black hole but you know to actually get all the way to the shadow are you really seeing the event horizon are you seeing a little bit further out you see you wind up seeing a little bit further out there's something called the last photo orbit and light as fast as it goes also is constrained to orbit around the black hole that's how deform the space-time is it's a crazy crazy place you could stand there with a flashlight and look at the back of your head or you could illuminate the back of your head if you're having a bad hair day you would know it immediately because that's what you're worried about when you're you know right outside a black hole yeah wouldn't your hair automatically become bad just because it's kind of being sucked it you would see how bad you think your hair feels gravity more strongly that's the spaghettification behind would it kind of be more frizzy or to be more like high volume like what kind of shampoo would you need to there might be special black hole products I think we've just started somebody right now is scratching out a memo company there's something else we'll learn to be upset and worried about more ways to oppress women what happens would you like which cellulite be changed near black hole how we the hair care products but I'm not going to touch that one so you are making your first observations when right so from these three telescopes in these humble beginnings a global international consortium has formed and we are now instrumenting telescopes around the world so in Chile even the South Pole in France and Spain and so forth in addition to the ones we already have and the new observations are occurring in the spring of 2017 under a year from now that's we light up most of the array that'll be our first shot at taking the first image of a black do you think that's gonna be a successful shot of course I do a lot of times these experiments take decades and the first shots not expected to be successful and you thinking 10 years down the line will refine enough to really nail it but you think as early as spring you're gonna have an actual picture well we are eternal optimist and even even experiments that are long shots are always assumed to perhaps give a good result if not light the way to future innovations that make inevitable success reality so we are really focused on success in spring of 2017 on the same time nature is nature we have no idea what we're going to see it doesn't always comply it does not always comply and we may fall flat on our face but the idea is that we get up and we sew is this a done deal the consortium the international collaboration is on board and this is definitely going to happen absolutely so we have time on some of the biggest apertures some of the biggest telescopes around the world and we have these systems that are going to freeze the light at all of these telescopes at unprecedented rates I'm rooting for you chef I'm rooting for you is there a risk when you're setting up these huge telescopes you'll see something you didn't plan to see like like like Matt waving I guess I'm gonna have to report this now a quarter on the moon is like a freckle on the neighbors yeah yeah yeah so so the yeah we could this could be like a Milky Way CSI episode or something like that like murder at the galactic center well so let me just say that we think we know we're gonna see but nobody would be happier than most of the people in the consortium if we saw something unexpected that would be hugely interesting and the way I like to put it is that we will will perhaps be able to test Einstein's theory but it's never wise dab it against Einstein but if we see something crazy if the size of the shadow is not what Einstein would have predicted given the mass of that black hole we will be really scratching our heads thinking about alternative forms of gravity we're thinking about objects even more exotic than a black hole so would that mean that the whole theory of general relativity is wrong and needs to be supplanted well we know Janna that gr cannot be complete right because at the center of the black hole where everything is crushed to a point the singularity gr has to come into a chord with quantum mechanics and nobody not even Einstein ever found a way to do that so we know gr is complete there just question is how close do we have to get to the singularity before it becomes evident right could be at the event horizon there could be manifestations of this deep mystery at the event horizon that the event horizon telescope could you know image there you know you mentioned quantum phenomenon the Hawking radiation which happens at the event horizon so quantum fluctuation of in empty space gets stolen by the black hole and the other particle radiates and to an observer far away it looks like the black hole is actually emitting radiation is that something you think you could probe with this telescope we can't see the Hawking radiation itself because that's going to be higher energy particles we know that something strange is happening at the event horizon right there's this thing called the information paradox right so if you throw an encyclopedia into the black hole what happens to the information in that encyclopedia it's uh I know this one it's planted by Wikipedia that everyone now uses and you free up a bookshelf the canoes for photos and that kind of thing it's a real time-saver yeah these black holes but so it turns out that that information has to go somewhere either the Hawking radiation has to encode it as it evaporates or it gets frozen onto the surface a lot of different theories and in some of those the quantum states inside the black hole may be in communication with the exterior of the black hole in that case you could wind up with different orbits of photons around the black hole and the shadow would look different know exactly how different it might look but there are ways to think about it from that framework no it's also possible that we just couldn't see any effect but there's still something going on it's just too difficult to imprint it in such a macroscopic object yeah I make it sound easy it's it's called what we're doing you make it look easy Shep I'm proud of you okay so people like a home one to build their own one of your telescopes well hash they go back they should not because we don't want any competition don't do this at home folks it's quite difficult and I would say that the only way that we're able to think about doing it is because we have a global team of exceptionally talented collaborators that all make it happen so sometimes you have to kind of sublimate your own ego right to be part of this bigger team it's not the lone pioneer oh it's really a global effort Emilia's and it's it's a real privilege to work with all these people yeah we're we're excited too for spring spring 2017 spring 20 hey stay tuned people we hope this show airs before then of t-shirts bye then ah I think it's time for the cosmic queries lightning round I think I'm supposed to deem this bow no way Jack I'm not very good at taking instructions I think that's what I'm supposed to do here what do we got in that alright from Sean Rasmussen who's a patreon patron and I think you've sort of touched on this already hi dr. Levin why is it the general relativity the theory of the large and quantum mechanics the theory of the small cannot be reconciled as one theory of everything if I'm not mistaken dr. Tyson described general relativity as being a mathematical shortcut on a larger scale because these to be unified with the new discovery of gravitational waves or say a graviton thanks for the show that's unlike caps unlikely couple nights a nation might like really wants to know let's hope you got the accent right well this is a this is a really important question I mean this is what all theoretical physicists pine for is a resolution of the theory of gravity with the fear of quantum mechanics so the large theory of the universe on a large scale on the theory of the universe on the small scale they're very hard to put together even if I went through kind of a standard program oh this is what I always do when I try to quantize a model of the universe it doesn't really work with gravity because gravity is so nonlinear right this is not you know the the effects feed back onto themselves in these very complex mathematical ways that we don't know how to control so literally we just don't know how to write it down it doesn't mean it doesn't exist in reality but we just don't know how to mathematically write it down or our tools fail us and so many people have tried just to find better tools but it might be the case that they're actually not reconcilable in nature that gravity in some sense isn't a fundamental force so you know when I say the temperature in this room is you know it's warm in this room temperature isn't an actual quantity that belongs to anything it's the collective behavior of group motions of small things gravity might be like that it might be the collective behavior of quantum entanglement and and phenomena like that and that when we look small enough we realize gravity is not really a thing at all it's something an illusion that only emerges on large scales I mean this stuff's really interesting we love not knowing the answers right that's why we have John's that's how we have something to do we build telescope yeah all right Travis Eva on Facebook Travis Eva on Facebook says how the black holes affect time presumably there are shot gravitational gradients in and around the black hole if so how do these affect the resulting temporal distribution of matter thank you well that's very interesting so well well you mentioned interstellar before so interstellar in interstellar they had this moment when people went close to the black hole and you know every hour they spent down there was twenty years outside that's a real thing right so time really does slow down close to the black hole and they spend time down there and they came back and everybody was twenty years older so the there is a dark time gradients near a black hole and they do affect the dynamics and when we think about matter and light orbiting the black hole we have to take those into account learning we're learning Ellie on Facebook says perhaps these questions were a little elementary but how much of our understanding of black holes relies on our understanding of quantum physics are their mind you values that influence the structure black holes that we have identified I mean in some sense astrophysically not at all yeah black holes are typically classical kind of objects when you look at them from the outside so unless we saw Hawking radiation we wouldn't really be able to see those quantum fluctuations but there's a whole community of mathematicians that are at their desks with pen and paper who are studying only the quantum aspects only would find them in different buildings on a university campus all right if I enter zero Ellis great name on facebook says how useful with space-based radio telescopes be for taking blackhole pictures oh they'd be fantastic so it turns out that one of the big problems we have is the Earth's atmosphere it's the water vapor in the atmosphere that's similar to what makes stars twinkle for optical telescopes that limits the event horizon telescope so if we could take a telescope put it in orbit their main telescope as big as the the orbital size of that how big is a radio telescope having across well the largest one that was a single one we use is about 50 meters across 150 feet across and then we have one in Chile that would be hard to get up in space all right Mike Schneider's on Facebook says if two black holes one being a bit stronger than the other words a meet would they in theory cancel each other out they would just get bigger it just happened like Oh made that first detection and it's a that's painful an amazing result first time in history we've seen two black holes collide and what happens is they make a bigger black hole and some of the mass though is released as gravitational wave energy thank you for the great questions in the lightning round but sadly we're at the end of our time today it's been a great day here at Startalk all stars once again thanks to Shep if you want to hear more about event horizon telescope go to event horizon telescope org and follow Matt on Twitter at Matt kirshen who is co-host of probably science podcast which is especially funny when I'm on it and I'm Janna Levin thanks for listening see you around the multiverse this is Startalk [Music]

Channel: StarTalk All-Stars

Views: 5,270

Rating: 4.8611112 out of 5

Keywords: Janna Levin, Matt Kirshen, Shep Doeleman, black holes, Albert Einstein, physics, quantum mechanics, general relativity, Event Horizon Telescope, Sgr A*, radio telescopes, accretion disk, Hawking Radiation, event horizon, light, spacetime, gravity

Id: xJiHPZxSlqA

Length: 49min 37sec (2977 seconds)

Published: Tue Oct 15 2019