Speaker 1: Further out in the dark, we found alien life. There
Speaker 1: were mats of corn colored slime glowing in the deep
Speaker 1: as they fed on jets of sulfur bubbling up from
Speaker 1: the mud at the bottom of a flooded crater. White
Speaker 1: ticks that tunneled through the ice, growing in spindles above
Speaker 1: the salt flats, the ruins of empty cities covered in
Speaker 1: mosslike growth on quiet planets. But as we journeyed further
Speaker 1: in into the hub, into the permanent light, everything was dead.
Speaker 1: What could live here? The stars hurtled past one another,
Speaker 1: dragging their doomed clouds of matter with them to collide
Speaker 1: like weather fronts. The radiation is a hot bath, the
Speaker 1: killer surf rocking in from all around. The night swarms
Speaker 1: with starlight. But our journey goes on because the Center calls,
Speaker 1: We're going to the bottom of the galaxy. Welcome stuff
Speaker 1: to Blow your Mind. A production of I Heart Radios
Speaker 1: How Stuff Works. Hey you, welcome to Stuff to blow
Speaker 1: your Mind. My name is Robert Lamb and I'm Joe McCormick.
Speaker 1: In Today we're coming back with some space themed I
Speaker 1: was about to say the word content. I'm not going
Speaker 1: to say the word content. I'm gonna say space themed stuff.
Speaker 1: That's an old favorite how stuff works fans. How about
Speaker 1: a space material. There's a lot of discussion of material
Speaker 1: and particles this episode in the one that follows it,
Speaker 1: because of course we're going to be talking about black
Speaker 1: holes once again. Yeah. Now, we did I think a
Speaker 1: three part series on black holes. It was sometime last year,
Speaker 1: maybe a year and a half ago, but we wanted
Speaker 1: to revisit the topic to talk about a specific case
Speaker 1: of very interesting black hole that we didn't get deep
Speaker 1: into in our last four That's right, So I do
Speaker 1: want to just so so really you can go about
Speaker 1: this two ways. Uh, you could treat this is part
Speaker 1: four and part five. Uh, and you know, go listen
Speaker 1: to the three previous black Hole episodes again. But I
Speaker 1: don't think it's entirely necessary. I think you can. You
Speaker 1: can come in and listen to these is just simply
Speaker 1: part one in part two of a look at a
Speaker 1: very particular type of black hole, a super massive black hole, right,
Speaker 1: and we'll do refreshers on the basics. So it's not
Speaker 1: like you've you've got to have done your homework here, right,
Speaker 1: you have to have seen either event Horizon or Disney's
Speaker 1: The black Hole. Otherwise you have no frame of reference.
Speaker 1: That's the starting homework. That's like the summer reading before
Speaker 1: you start our podcast in the ball well, you know,
Speaker 1: I mean the weird thing is that, you know, those
Speaker 1: are two films that I think are in some cases
Speaker 1: people's first introduction to the concept of a black hole.
Speaker 1: And granted, those are two films that, each in their
Speaker 1: own way are loaded with errors and problems and misinformation.
Speaker 1: And yet Fantasy black Hole and the Fantasy black Holes.
Speaker 1: But you know, a fantasy black hole is I think
Speaker 1: a good starting place in many respects. You know, it
Speaker 1: gives you a fantastic notion, sometimes an you know, an
Speaker 1: action pack very uh you know, terrestrial model of what
Speaker 1: a black hole is. And it's not a bad place
Speaker 1: to then begin and then build scientifically on the concept.
Speaker 1: There is a kernel of truth in the suggestion of
Speaker 1: the Fantasy black hole, which is that while we know
Speaker 1: more about black holes than we ever have before, and
Speaker 1: this year, for the very first time, we think we
Speaker 1: got you know, basically a direct image of a black
Speaker 1: hole to whatever extent that's possible. And talk more about
Speaker 1: the specifics of that later on, But but yeah, while
Speaker 1: we still, while we know more than we ever have,
Speaker 1: black holes still contain a lot of mysteries. They contain
Speaker 1: some edge cases for our theories of physics where what
Speaker 1: we know ceases to make sense. And so there's still
Speaker 1: a lot of lingering questions, a lot of tantalizing mysteries.
Speaker 1: But before we get to the tantalizing mysteries and the
Speaker 1: lingering questions, I want to talk about a a nerdy
Speaker 1: engineer born in Oklahoma whose middle name is Gooth. I mean,
Speaker 1: that's a that's an excellent nerd middle name. Okay, So
Speaker 1: I'm going to talk about Carl Gooth Jansky. He was
Speaker 1: born in Norman, Oklahoma, in nineteen o five, one of
Speaker 1: six children, and his family and Jansky's dad, Cyril, was
Speaker 1: an electrical engineering professor. It's a little Carl Jansky. When
Speaker 1: he grew up, he followed in his father's trajectory to
Speaker 1: study physics and engineering as well. So as a young man,
Speaker 1: Karl Jansky earned a degree in physics from the University
Speaker 1: of Wisconsin. I think he got his undergraduate degree but
Speaker 1: then failed to complete his masters. But then anyway, he
Speaker 1: went on to get hired by a company he was
Speaker 1: hired for a position as a radio engineer with Bell
Speaker 1: Telephone Laboratories in ninety eight, and this would have been
Speaker 1: when radio engineering was something fairly new, So at this
Speaker 1: time in the late nineteen twenties, Bell Labs was interested
Speaker 1: in creating a system for a wireless radio based telephone
Speaker 1: service that would allow ins atlantic phone calls and let's
Speaker 1: just say you needed to call across the Atlantic Ocean
Speaker 1: to order a bagat or something. These radio based phone
Speaker 1: calls that Bell Labs wanted to do would have been
Speaker 1: in the short wave frequency range, meaning wavelengths of about
Speaker 1: ten to twenty meters, and Jansky was given the job
Speaker 1: of hunting down any potential sources of radio interference that
Speaker 1: would cause static on the calls. So Jansky built a
Speaker 1: giant receiver antenna to detect signals at a wavelength of
Speaker 1: fourteen point five meters. And this was a directional antenna,
Speaker 1: and that meant that it could be moved around to
Speaker 1: identify the origin vector of any particular signal. Right, so
Speaker 1: it's not receiving signals from every direction the same you
Speaker 1: aim it in the direction that you want to pick
Speaker 1: up the signal from. And it was mounted on a
Speaker 1: giant rotating platform outfitted with motorized wheels. Actually there were
Speaker 1: the wheels from a model T and it could be
Speaker 1: aimed in any direction to root out the sources of
Speaker 1: attic or other interference that they were looking for. Some
Speaker 1: people called this Jantski's Merry go Round. I've got a
Speaker 1: photo of it here for you, Robert. Yeah, at first glance,
Speaker 1: it looks not unlike a giant biplane of some kind,
Speaker 1: you know. Oh yeah, with the struts on the wings,
Speaker 1: it looks like the world's most dangerous gymnastics equipment. It's
Speaker 1: just broken shins all around. Yeah, it looks a little
Speaker 1: bit like scaffolding or uh, the system of goals and
Speaker 1: some sort of Susian sport. But in the middle, of course,
Speaker 1: it's got wheels, and it's got a little track that
Speaker 1: the wheels roll around on so that you can aim
Speaker 1: it to to calibrate where the source of the interference
Speaker 1: is coming from. So, first of all, he discovered the
Speaker 1: main source of terrestrial interference on this radio frequency range,
Speaker 1: which was electrical storms. So if there's a thunderstorm nearby
Speaker 1: that could generate static. You can even get some static
Speaker 1: from distant thunderstorms. But Jansky also discovered a source of
Speaker 1: noise in this frequency range that seemed unrelated to thunderstorms,
Speaker 1: quote a steady hiss type static of unknown origin. This
Speaker 1: signal would go through a cycle once a day, peaking
Speaker 1: in intensity and then fading roughly every twenty four hours,
Speaker 1: but not exactly every twenty four hours, just slightly, just
Speaker 1: slightly less than twenty four hours. Now, at first, you know,
Speaker 1: what would you conclude if something was emitting radiation powerful
Speaker 1: enough to cause terrestrial radio interference in a cycle that
Speaker 1: lasted about one day? What would you think it probably was?
Speaker 1: But that that brings one's attention to just like the
Speaker 1: immediate neighborhood of the Solar system, something to do with
Speaker 1: the Earth's position relative to the Sun. Yeah, exactly. You
Speaker 1: think it's probably the Sun, right, But Jansky chased the
Speaker 1: signal and it turned out it wasn't the Sun because
Speaker 1: he kept following it for several months, and while the
Speaker 1: signal at some point, I think when he was originally
Speaker 1: chasing it was kind of near the Sun, it shifted
Speaker 1: over time and moved away. And so after months of
Speaker 1: using his radio source finding techniques and teen thirty two
Speaker 1: he discovered or I think it was thirty one or
Speaker 1: thirty two. He discovered that the origin of this anomalous
Speaker 1: static hiss was coming from deep space, and he narrowed
Speaker 1: it down to an origin point roughly in the constellation Sagittarius.
Speaker 1: Now Sagittarius is named after a a centaur archer. In
Speaker 1: Greek mythology, it's associated with the centaur uh An. Ancient
Speaker 1: Mesopotamian astrology, the constellation Sagittarius was associated with the deity
Speaker 1: near gal a creature of fire and the desert and
Speaker 1: war and disease, kind of a a creepy demon type figure.
Speaker 1: In Greek and Roman astrology, the constellation was most often
Speaker 1: associated with the image of a centaur drawing a bow.
Speaker 1: So it's like this super accurate centaur archer who always
Speaker 1: hits his mark. Yeah, that centaur's that name is Chion,
Speaker 1: mentor of the Greek hero Achilles. Alright, I'd rather like
Speaker 1: the idea of of Achilles is the sort of mythical
Speaker 1: killing machine having been you know, the student of of
Speaker 1: of Well, I don't want to spoil it, but some
Speaker 1: sort of cosmic anomaly, like he was getting messages into
Speaker 1: his brain from space. Yeah, this was the static kiss
Speaker 1: talking to Achilles. Yeah, I mean, well, what is it
Speaker 1: to be, you know, to hear the voice of the gods,
Speaker 1: but to be, you know, an antenna receiving signals from beyond,
Speaker 1: or to get your brain hit by a cosmic ray.
Speaker 1: But anyway, like any constellation, Sagittarius, Sagittarius is not a
Speaker 1: thing up there. This is something that I often fall
Speaker 1: into the trap of thinking of constellations as like objects
Speaker 1: that exist in themselves. But of course a constellation is
Speaker 1: a number of stars that appear in a certain arrangement
Speaker 1: from our perspective here on Earth. It's not like those
Speaker 1: stars have a natural association with each other, right, It's
Speaker 1: just a yeah, it all has to do with our perspective.
Speaker 1: And then it just is a shorthand way of identifying
Speaker 1: different different portions of the night sky. They're not objects
Speaker 1: in the sky anymore than like the figure of a
Speaker 1: shadowy goblin hand cast on your window at night by
Speaker 1: a tree limb against the moonlight is an object. It's
Speaker 1: feature of your perspective where the lights coming from, where
Speaker 1: you're looking from. But an important thing about Sagittarius from
Speaker 1: our perspective is that this constellation just happens to be
Speaker 1: generally the direction of the center of the Milky Way galaxy,
Speaker 1: our galaxy, the one we live in. And this was
Speaker 1: what Jansky had discovered, an extraterrestrial radio source coming not
Speaker 1: just from space, but from the core of the Milky Way.
Speaker 1: Then they get you're prickling a little bit, Yeah, like
Speaker 1: something something major is happening there, something that we can detect. Right.
Speaker 1: So Jansky authored a handful of scientific papers on this finding,
Speaker 1: including a paper called Electrical Disturbances Apparently of Extraterrestrial origin,
Speaker 1: which he presented in nineteen thirty three to a conference
Speaker 1: in Washington of the International Scientific Radio Union. And this
Speaker 1: led to media coverage, including an article in The New
Speaker 1: York Times from nineteen thirty three, which you can still
Speaker 1: read online if you got a log in with your subscription.
Speaker 1: I looked it up and I read it. Can you
Speaker 1: guess what the reporters asked to Jansky? Can you just guess? Um?
Speaker 1: You probably asked, are their little green men? Of course,
Speaker 1: the concluding paragraph of the article is there is no
Speaker 1: indication of any kind. Mr Jansky replied to a question
Speaker 1: that these galactic radio waves constitute some kind of interstellar signaling,
Speaker 1: or that they are the result of some form of
Speaker 1: intelligence striving for intragalactic communication. I'm glad they cleared that
Speaker 1: up because they specify in the article that was a
Speaker 1: steady hiss of random radio static, which seems like a
Speaker 1: really bad type of radio signal to use for interstellar
Speaker 1: communication would be like trying to communicate with somebody by
Speaker 1: handing them blank pieces of paper. Plus ninety three not
Speaker 1: a great time period to be visited by some sort
Speaker 1: of extraterrestrial civilization. I mean, not that today is you
Speaker 1: know that we've necessarily got things in working order, so
Speaker 1: that so that some distant civilization can judge us and
Speaker 1: decide if we should uh, you know, be left to
Speaker 1: function on our own or not. But thirty three was
Speaker 1: not a great year, no, not not one of the
Speaker 1: best periods. So so he's not saying it's aliens. He's
Speaker 1: definitely not saying it's aliens. He's saying it's pretty much
Speaker 1: undoubtedly physical, not organic. But what was it? Well? Jansky
Speaker 1: wanted to continue research on this deep radio source at
Speaker 1: the heart of the Milky Way, but Bell Labs was
Speaker 1: of course not interested in funding this kind of thing.
Speaker 1: In the nineteen thirties, early nineteen thirties. You know, this
Speaker 1: is the depression. They're they're they're not just looking to
Speaker 1: to profligately spend money on astronomy. It was enough for
Speaker 1: them to have the radio telephone interference issues solved, But
Speaker 1: in the following decades many astronomers actually picked up where
Speaker 1: Jansky had left off, and Jansky is now remembered as
Speaker 1: one of the pioneers of radio astronomy. I've seen it
Speaker 1: speculated somewhere that if he hadn't died early he died
Speaker 1: pretty young, that he may have received the Nobel Prize
Speaker 1: at some point later. But he he hasn't forgotten. In fact,
Speaker 1: I almost forgot this. The massive radio telescope array in
Speaker 1: New Mexico known as the Very Large Array, which I
Speaker 1: visited in person last year and have talked about on
Speaker 1: the show before. It's actually named in his honor. It
Speaker 1: almost gets forgotten because it's the v l A. But
Speaker 1: it's the Carl G. Jansky v l A. Oh okay, cool, Yeah,
Speaker 1: I didn't realize that either. And there's also a metric
Speaker 1: named after him. And there's a unit in radiophysics known
Speaker 1: as the Jansky I can't remember exactly what it is.
Speaker 1: It denotes something. But now astronomers have since then has
Speaker 1: spent a lot of time and energy trying to understand
Speaker 1: what is happening at the galactic center, at the core
Speaker 1: of our galaxy. And this is really difficult because we
Speaker 1: can't leave our galaxy to look down on it from above. Right.
Speaker 1: If you've ever seen an image of the Milky Way
Speaker 1: depicted in like a circular shape, this is just a guess,
Speaker 1: a guess of an illustrator. We can't look at our
Speaker 1: galaxy from outside it. We're in it. It would be
Speaker 1: like trying to look at a storm from above while
Speaker 1: the storm you're standing on the ground. The storm is
Speaker 1: going on all around you. The center of the Milky
Speaker 1: Way is especially hard for us to see into because
Speaker 1: this region at the center of the galaxy that the
Speaker 1: rest of the galaxy orbits around, is shrouded by dust,
Speaker 1: these thick clouds of dust that obscure its millions of
Speaker 1: stars from our point of view. I've seen numbers that
Speaker 1: suggests there are like twenty five magnitudes of optical extinction
Speaker 1: from this region due to dust. And that's why, even
Speaker 1: though the core of our galaxy is by far the
Speaker 1: brightest part of the galaxy, it's lit up with tons
Speaker 1: of stars. There's all this dust there that blots out
Speaker 1: the light and mutes that brightness from our point of view.
Speaker 1: But modern telescopes and equipment have given us other ways
Speaker 1: to peer through the dust into the center of the galaxy.
Speaker 1: For example, through infrared and other radio frequency detections, we
Speaker 1: can see what's shining from within. And today astronomers believe
Speaker 1: we have extremely compelling evidence that this radio source at
Speaker 1: the center of the galaxy uh Is is a regions
Speaker 1: surrounding a gigantic supermassive black hole. This compact radio source
Speaker 1: together is known as Sagittarius a star. And if you
Speaker 1: see this printed or you know, type, it is a
Speaker 1: Sagittarius a asterix. The asterix stands for star, right, Yeah,
Speaker 1: it's pronounced star. But it always, for the longest time,
Speaker 1: whenever I saw it, it it would confuse me because I'd
Speaker 1: see it then it looked like, Okay, I'm looking for
Speaker 1: the note and there's not one. Because in astronomy that
Speaker 1: that asterix denote star. And we'll get to the you know,
Speaker 1: the details on that in a bit. Yeah, it was
Speaker 1: named that way for a cheeky reason by an astronomer
Speaker 1: in the nineteen seventies. But maybe we should take a
Speaker 1: break and then when we come back, we can sort
Speaker 1: of do a refresher on black holes and get into
Speaker 1: the details of this supermassive black hole. Thank alright, we're back,
Speaker 1: all right. So, as we said before, we did a
Speaker 1: whole series on black holes about a year and a
Speaker 1: half ago. You can go listen to those if you want.
Speaker 1: They get way into the history of the discovery of
Speaker 1: black holes and all that, but we'll do a brief
Speaker 1: refresher here. One quote I really like comes from the
Speaker 1: physicist Supermanion Chandra Shekar, who is very important in the
Speaker 1: history of black hole research. Uh. And he wrote a
Speaker 1: book called The Mathematical Theory of black Holes, and in
Speaker 1: the prologue there's a part where he writes, quote, the
Speaker 1: black holes of nature are the most perfect macroscopic objects
Speaker 1: there are in the universe. The only elements in their
Speaker 1: construction are concepts of space and time. And this gets
Speaker 1: to some of the history we discussed in those previous episodes,
Speaker 1: being that, like, the black hole was the thing that
Speaker 1: that we saw in the math before we even began
Speaker 1: to like, you know, to to see through uh. You know,
Speaker 1: other astronomical means. Yeah, it existed in theory long before
Speaker 1: it had ever been detected directly. In fact, you could
Speaker 1: only argue probably that that you could well, I don't know.
Speaker 1: I guess it depends on what evidence people count. But
Speaker 1: there is evidence now that seems to be direct indications
Speaker 1: of black holes, but it's hard for reasons that we'll
Speaker 1: talk about in a minute, I guess, yeah, for for
Speaker 1: the longest black holes. So certainly if you pull out
Speaker 1: an older textbook, they're going to refer to black holes
Speaker 1: as theoretical objects, right, Yeah, So a black hole is
Speaker 1: a region of space time that is so dense that nothing,
Speaker 1: not even light, can escape, And this of course means
Speaker 1: that you can't see a black hole. There's nothing to
Speaker 1: see because the only way we see things is if
Speaker 1: they emit or reflect light, and a black hole does neither.
Speaker 1: No light comes out of it. If light goes toward it,
Speaker 1: it doesn't bounce off and come back in your direction.
Speaker 1: It just gets absorbed and never escapes. Yeah, you know this,
Speaker 1: this reminds me a lot of how we're recently talking
Speaker 1: about casually about quantum mechanics. In a new book that
Speaker 1: you've read, about quantum mechanics and and and uh, and
Speaker 1: this is kind of that's kind of like the the
Speaker 1: micro quest and then the black holes are the macro
Speaker 1: quest and the macro into the spectrum. And you know,
Speaker 1: both of these are extremes that are just so far
Speaker 1: beyond our ability to you know, certainly our evolved ability
Speaker 1: to perceive and and to some extent even contemplate, you know,
Speaker 1: and and and and so we you know, we talk
Speaker 1: about like how we would perceive them vigitally, and even
Speaker 1: that is like when you really start turning that over
Speaker 1: in your head, um, it's it just gets ridiculous really quickly,
Speaker 1: you know. Well, it forces you to think about the
Speaker 1: nature of physical information. Yeah, the fact that you know,
Speaker 1: a black hole highlights the fact that when you see
Speaker 1: a thing, you never really see the thing. You're seeing
Speaker 1: light reflecting off of it, which is, you know, that's
Speaker 1: our most common way of sampling the world. So it
Speaker 1: makes sense to just think about that as a short cut. Yes,
Speaker 1: when I see the light bouncing off of a coffee cup,
Speaker 1: I see the coffee cup, but you're not, you know,
Speaker 1: you don't have the coffee cup within you from that,
Speaker 1: it's just light. Yeah, with our site, with with certainly
Speaker 1: healthy human side. We kind of have this illusion that
Speaker 1: that we that we are cited, that we can perceive.
Speaker 1: But the more we look at things like the microscopic world,
Speaker 1: in the macroscopic world, the inner space and and outer space,
Speaker 1: you really begin to feel that we are not cited
Speaker 1: at all. We are just so incredibly blind. And the
Speaker 1: only way that we are really really have been able
Speaker 1: to understand h nature has been through scientific inquiry that
Speaker 1: I guess you could you could relate to the like
Speaker 1: the blind pawing of of the blind men and the elephant,
Speaker 1: you know. Yeah, And astronomy is a great way to
Speaker 1: highlight that. Astronomy and well you pointed to both ends
Speaker 1: of the scale, you know, physical scale, the quantum mechanics
Speaker 1: world and astronomy what's out there in the dark beyond Earth.
Speaker 1: They both really highlight ways in which the universe is
Speaker 1: full of hugely powerful, consequential phenomena that we not only
Speaker 1: don't regularly see, but we can't even understand when we
Speaker 1: when we detect it with other means right and in
Speaker 1: both totally violates our intuitions and in both directions, both
Speaker 1: towards the small and the large. You know, we can
Speaker 1: optically enhance the telescope or the microscope, but in both
Speaker 1: directions there reaches a point where optical enhancement uh doesn't
Speaker 1: get you anywhere, and we have to rely on other
Speaker 1: means of of pawing at the uh you know, at
Speaker 1: the the the the the Titanic forces on an either
Speaker 1: end of the spectrum. And that's something that, of course,
Speaker 1: we get to with Jansky's discovery, right, this idea that
Speaker 1: there are these powerful sources of information coming into the Earth,
Speaker 1: but it's not information that anybody would be able to
Speaker 1: see with their eyes coming in radio frequencies and then uh,
Speaker 1: you know, other frequencies of light. But I guess to
Speaker 1: get back to black holes, we should ask the question,
Speaker 1: of course, how is it possible for an object to
Speaker 1: be so dense that it neither reflects nor amidst light?
Speaker 1: Like what what happens to the light when it goes in?
Speaker 1: Why that be the case? Uh? So, the basic principle
Speaker 1: is the greater the mass of an object, the more
Speaker 1: difficult it is for an object that is moving away
Speaker 1: from it to escape its gravity. Well, now, all sources
Speaker 1: of gravity have their own particular escape velocity and If
Speaker 1: I'm standing on the surface of the Earth and I
Speaker 1: throw a cantalope straight up in the air at a
Speaker 1: hundred kilometers an hour, it's of course going to fall
Speaker 1: back down to the ground. If I throw the cantle
Speaker 1: ope at two hundred kilometers per hour, it's going to
Speaker 1: go up farther, but of course it will eventually slow down,
Speaker 1: reverse course and fall back to the Earth. But if
Speaker 1: I keep throwing it up in the air greater and
Speaker 1: greater velocities each time, eventually you will reach some velocity
Speaker 1: where the cantalope doesn't fall straight back down to the ground,
Speaker 1: but it goes up and up and up, and it
Speaker 1: breaks free of Earth's gravity, and then it just keeps
Speaker 1: on flying out into space. It maintains its momentum and
Speaker 1: goes in the other direction. Now at the surface of
Speaker 1: the Earth, this velocity for objects that don't keep propelling
Speaker 1: themselves as they travel, is about eleven point twokilometers per second,
Speaker 1: so it's very fast. Humans have never made a terrestrial
Speaker 1: vehicle that goes even close to this fast with humans
Speaker 1: in it. Certainly, our our launch vehicles that put things
Speaker 1: into orbit or send them into outer space don't go
Speaker 1: that fast. At first. Heavy launch vehicles like the you know,
Speaker 1: Saturn five rocket and things of that ilk are able
Speaker 1: to put things into orbit or beyond by applying continuous
Speaker 1: thrust as they achieve higher and higher altitude. So the
Speaker 1: rocket keeps on pushing and pushing by ejecting more exhaust
Speaker 1: until it gets up through the atmosphere. And then, of course,
Speaker 1: inside the atmosphere, air resistance and frictional heating would be
Speaker 1: a huge issue if you try to have a spacecraft
Speaker 1: achieve escape velocity too early, right, your spacecraft would probably
Speaker 1: get too hot and burn up. But once outside the atmosphere,
Speaker 1: rocket can keep accelerating. In the vehicle can get up
Speaker 1: to the ultimate speed that it needs to go into
Speaker 1: orbit or leave Earth's gravity overall, and it turns out
Speaker 1: this escape velocity logic even applies to light. At a
Speaker 1: certain point, an object becomes so dense, there's so much
Speaker 1: mass inside such a small space that the escape velocity
Speaker 1: for an object exceeds the speed of light. So no
Speaker 1: light comes out of the black hole, No light is
Speaker 1: emitted from within, no light is reflected from without. It's
Speaker 1: a perfect vortex. It swallows everything that comes within a
Speaker 1: certain radius, and of course if this applies to light,
Speaker 1: it doesn't just apply to light, right, because since nothing
Speaker 1: with mass can travel faster than the speed of light,
Speaker 1: speed of light could also be thought of as a
Speaker 1: kind of speed of information or a speed of causality
Speaker 1: in the universe. If light can't escape the black hole,
Speaker 1: nothing can escape. Now. Something I think a couple of
Speaker 1: listeners were asking about after our last black Hole series
Speaker 1: was trying better to picture exactly what's going on there, Like,
Speaker 1: what is it that nothing can escape? In some ways?
Speaker 1: Could a black hole be kind of like a solid
Speaker 1: black bowl, like a black ball that you get stuck
Speaker 1: to the outside of like paper, you just get flattened
Speaker 1: against it. I think the answer to that is no.
Speaker 1: A black hole is matter that has collapsed on itself
Speaker 1: to what looks to us, at least through the math,
Speaker 1: like a point of zero volume and infinite density, and
Speaker 1: this is sometimes called the singularity. Now, is it actually
Speaker 1: physically possible to have a point of infinite density that
Speaker 1: may be not something that we're supposed to literally picture.
Speaker 1: Is what's there? But an indication that we don't have
Speaker 1: a correct theory of quantum gravity yet, and you know,
Speaker 1: we just don't understand exactly what's happening there. That's where
Speaker 1: general relativity breaks down. But I think what it does
Speaker 1: make sense to say is that there is some kind
Speaker 1: of point of extremely tiny collapse at the core of
Speaker 1: the black hole too. That doesn't really make any kind
Speaker 1: of intuitive sense to the physics, you know, engine in
Speaker 1: our brains. And then of course there is that that
Speaker 1: that point of no return as well. That plays into
Speaker 1: our very perception of the black hole, right that point
Speaker 1: of no return and is often what we think of
Speaker 1: as the black hole. But that's not necessarily stuff. That
Speaker 1: is a region of space around this point where all
Speaker 1: the all the original matter that made up the thing
Speaker 1: that became the black hole is collapsing into. So that
Speaker 1: is the event horizon. Yes, exactly, it's the sphere shaped
Speaker 1: region of space that's a kind of gravitational exclusion zone.
Speaker 1: The size of this zone, of course, depends on the
Speaker 1: mass of the black hole core. So a more massive
Speaker 1: black hole will black out a larger region of space
Speaker 1: in the sphere around it. I think we uses we
Speaker 1: might have used this very um analogy before. But if
Speaker 1: if the black hole is the killer inside the haunted house,
Speaker 1: the event horizon is the haunted house. Okay, So like, uh,
Speaker 1: you know, you can say that the black hole is
Speaker 1: leather Face, but the event horizon is the leather Face
Speaker 1: family home. Can you see people walking towards and never
Speaker 1: emerging from. Oh, but Marilyn Burns does escape, Well, I'm
Speaker 1: talking about earlier the film. You're okay, Okay, Obviously, I'm sorry.
Speaker 1: I didn't mean to nitpick your analogy. Obviously, obviously people
Speaker 1: have to escape the film. I have to escape the
Speaker 1: house for a proper horror movie to work. But in
Speaker 1: a version of the leather Face movie where nobody ever
Speaker 1: comes out, then like that is the event arison. Perhaps
Speaker 1: there's there's a there's a more fitting example from from
Speaker 1: like haunted House lore out there. I guess it would
Speaker 1: make the story is less interesting if you just know
Speaker 1: that nobody ever escaped. I think Stephen King had a
Speaker 1: short story about a women's bathroom that functioned like this,
Speaker 1: where like people went in but they didn't come out,
Speaker 1: and and like the the the point of view character
Speaker 1: was just trying to figure out what was happening. I
Speaker 1: only have a vague memory of this. I think it
Speaker 1: was like a real shorty, or maybe it was just
Speaker 1: him talking about a concept he had that he had
Speaker 1: not written, King Fans will have to straighten me out. Then, well,
Speaker 1: we're we're like that person outside the bathroom trying to
Speaker 1: figure about what's going on because we can't look inside
Speaker 1: and see. Uh So, the edge of this region of space,
Speaker 1: of course, as you said, is one name for it
Speaker 1: is the event horizon. But the distance between the core
Speaker 1: of the you know, what's known as the singularity, the
Speaker 1: core of the black hole, what everything, the point that
Speaker 1: everything collapses down into and this event horizon is known
Speaker 1: as the schwartz Shield radius, named after the twentieth century
Speaker 1: German astronomer and physicist Carl schwartz Shield, who did very
Speaker 1: important calculations in the early days of black hole theory,
Speaker 1: back when black hole theory was still ridiculed as being
Speaker 1: something that, you know, couldn't possibly be found in nature.
Speaker 1: I think it was that Arthur Eddington who originally said, uh,
Speaker 1: you know, when when Chandra Sheker and the others were
Speaker 1: proposing the idea of black holes, Eddington was like, surely
Speaker 1: nature would forbid such a preposterous event. That's one of
Speaker 1: those great times when nature faced a scientist who thought
Speaker 1: nature couldn't be that weird, and of course it is
Speaker 1: always the case. Nature is far weirder than can possibly imagine,
Speaker 1: of course. But yeah, anyways, this sphere of space from
Speaker 1: which nothing returns. Anything that passes within the short shield
Speaker 1: radius enters this strange world of warped space. And from
Speaker 1: this space it is impossible to escape. Once inside the
Speaker 1: event horizon the short shield radius, there's only one direction.
Speaker 1: That direction is down. No matter what you do, you're
Speaker 1: headed towards the center of the black hole. And I
Speaker 1: should add quickly there may be exceptions to these rules
Speaker 1: for special types of black holes with exotic properties. You
Speaker 1: find articles about these, like weird types of black holes
Speaker 1: where things can change. But this is the basic I
Speaker 1: think you're non rotating standard stellar blast. Yeah, this is
Speaker 1: your standard model. Now, we alluded to earlier the fact
Speaker 1: that even though a black hole neither emits nor reflects light,
Speaker 1: we do have pretty solid evidence now that black holes
Speaker 1: do exist. Uh, They're not just something that is sort
Speaker 1: of hypothesized by the theory of general relativity. But like
Speaker 1: we we've we're pretty certain we've detected them out there
Speaker 1: in the universe. Now, so how can you detect them
Speaker 1: if they neither reflect nor a mint light. Well, I mean,
Speaker 1: it's kind of like the hunted house scenario, Like if
Speaker 1: there was a house like this that no one ever
Speaker 1: emerged from again, because there's some sort of uh, you know,
Speaker 1: diabolical force within it that consumes everyone that passes within
Speaker 1: a you know, past its threshold. Obviously, you could note
Speaker 1: people that entered the house and didn't come back out again.
Speaker 1: You might notice the um the effect that such a
Speaker 1: house would have on the the surrounding property values, um
Speaker 1: you might have. You know, basically, it would have some
Speaker 1: effect on the surrounding environment that would be observable even
Speaker 1: if you never got to actually pass within its walls
Speaker 1: and see the dark, hideous force that is murdering people. Yeah,
Speaker 1: I think that's exactly right. You can observe a black
Speaker 1: hole by looking at its effects on surrounding objects. And
Speaker 1: one of those types of effects is gravitational effects. Imagine
Speaker 1: you see a dis stant star orbiting some invisible point,
Speaker 1: and that star's orbit is it's it's on a very
Speaker 1: irregular trajectory, maybe a super stretched out ellipse, and at
Speaker 1: one end of that ellipse, it appears to be going
Speaker 1: really close to the thing it's orbiting. Around but that
Speaker 1: we can't see, and as it goes really close to
Speaker 1: that thing, it accelerates to unbelievable speeds. There would be
Speaker 1: a good case to be made that maybe what it's
Speaker 1: orbiting is something that is incredibly tiny and incredibly massive,
Speaker 1: And in fact, this is exactly what we see. Especially
Speaker 1: with the case of Sagittary as a star the hypothetical
Speaker 1: supermassive black hole at the center of our galaxy that
Speaker 1: we were alluding to earlier, we have noted the passive
Speaker 1: the transit of stars around it that suggests that the
Speaker 1: thing these stars are orbiting could only be a black hole,
Speaker 1: because otherwise there's nothing else that could be as small
Speaker 1: as the thing they're orbiting and accelerating them as fast. Now,
Speaker 1: another way you could look at the surroundings of an
Speaker 1: object and determined that it's a black hole is if
Speaker 1: stuff is basically stuff is catching on fire, not on fire,
Speaker 1: but it's getting really hot. Um as matter like gas
Speaker 1: and dust, swirls around a black hole and eventually falls
Speaker 1: over its sword shield radius. In this process of swirling
Speaker 1: around and falling in, it gets accelerated to incredible speeds
Speaker 1: and superheated, blasting out hot radiation that that is some
Speaker 1: of the brightest stuff we can see in the entire universe,
Speaker 1: like this idea of quasars, these you know, quasi stellar
Speaker 1: radio radio emitting objects out there in the universe. We
Speaker 1: tend to think that what these things are are the
Speaker 1: cores of galaxies that have supermassive black holes at the
Speaker 1: center of the galaxy. And as stuff is falling into
Speaker 1: the supermassive black hole, it gets accelerated to such a
Speaker 1: way that to such an extent that it becomes unbelievably
Speaker 1: bright on the on the electromagnetic spectrum. So again for analogy,
Speaker 1: you can you can think of this like imagine there
Speaker 1: were an invisible blow torch floating around in a forest.
Speaker 1: Like you couldn't see the blowtorch, but you could notice
Speaker 1: that all the leaves in the wind swirling around a
Speaker 1: certain area of space or all catching on fire for
Speaker 1: some reason. And then another thing, of course, is that
Speaker 1: data collected from gravitational wave of observatories has picked up
Speaker 1: waves propagating through the universe that seem to be best
Speaker 1: described by the collision of black holes. Now we know
Speaker 1: there are a few different kinds of black holes, right,
Speaker 1: so we know that there, there's your standard model stellar
Speaker 1: black hole, and these are created by the collapse of
Speaker 1: large mature stars. Our Sun is not massive enough to
Speaker 1: become a black hole. Uh. In something like four to
Speaker 1: five billion years. Our Son's probably like halfway through its
Speaker 1: its main sequence life. In about four or five billion years,
Speaker 1: it's going to swell up into a red giant that
Speaker 1: will absorb the orbits of mercury and venus and possibly Earth,
Speaker 1: and then it will go through a series of different
Speaker 1: internal chemistry phases, is where it's fusing heavier and heavier
Speaker 1: elements as it runs out of its lighter fuel, so
Speaker 1: it'll run out of hydrogen, then fuse helium, run out
Speaker 1: of helium, and fuse heavier and heavier elements uh. And
Speaker 1: then eventually it will end up as a white dwarf,
Speaker 1: which is what it will remain for trillions of years
Speaker 1: basically until it just cools off. It's interesting, we keep
Speaker 1: coming and we'll keep coming back to the the idea
Speaker 1: of between four and five billion years old, like and
Speaker 1: again stressing that the Earth is what four point five
Speaker 1: billion about years old, So in a few via the
Speaker 1: a few different calculations, like the Earth is half done, Yeah,
Speaker 1: assuming nothing else happened to it before then. Yeah, uh though, yeah,
Speaker 1: I think the the habitability window for the Earth might
Speaker 1: be a bit shorter than that, yes, because things might
Speaker 1: get worse before before the Earth is actually even potentially
Speaker 1: swallowed up right, And then of course the's a whole
Speaker 1: there's an additional discussion about, you know, do we reach
Speaker 1: a civilization level at that point where we have the
Speaker 1: technology to do something about it, say, move the Earth, etcetera.
Speaker 1: But that's another podcast unto itself. Yeah, the scoutow thruster
Speaker 1: or whatever. Oh no, wait, no, that brings the star
Speaker 1: with us. We don't want that, need better star. But anyway, Yeah,
Speaker 1: so the Sun is not large enough to become a
Speaker 1: black hole. If our Sun were a lot larger, maybe
Speaker 1: about ten times its current mass, you could expect that
Speaker 1: when it exhausts its hydrogen fuel and begins fusing heavier
Speaker 1: and heavier elements, it could eventually end up trying to
Speaker 1: fuse a dense core made of iron, which is the
Speaker 1: chemical death ritual of a star fusing iron. Is that's like,
Speaker 1: that's like the character in the horror movie saying, is
Speaker 1: anybody there? That's just you know, there's no returning After that,
Speaker 1: fusing iron leads to not enough outward pressure to hold
Speaker 1: the mass of the star up against its own gravity,
Speaker 1: and it collapses inward catastrophically. It releases a giant blast
Speaker 1: of energy and eventually perhaps turns into a super dense
Speaker 1: neutron star or even a black hole. But again this
Speaker 1: depends on the density of the thing that's left there
Speaker 1: after this event. If our son had the same mass
Speaker 1: it does now, but it was only a few kilometers wide,
Speaker 1: supposedly it would collapse into a black hole. There's just
Speaker 1: no reason to think that it would ever be that small.
Speaker 1: But there are other kinds of black holes that we
Speaker 1: can't say are formed necessarily from the collapse of large
Speaker 1: stars after they exhaust their fuel supply of lighter elements.
Speaker 1: There is, for example, a hypothetical type of black hole
Speaker 1: called the primordial black hole, which if they did exist,
Speaker 1: would have formed due to the gravitational collapse around dense
Speaker 1: regions in the very earliest periods of the expanding universe.
Speaker 1: And then there's this other class of black hole, the
Speaker 1: one that Sagittarius a star would be if if there
Speaker 1: is in fact a black hole there, and we think
Speaker 1: there's very good evidence there is, uh, these remain more
Speaker 1: of a mystery to us. This is the These are
Speaker 1: the black holes found at the cores of massive galaxies. Yes,
Speaker 1: some of the theories that we have for the formation
Speaker 1: of sort of the standard black holes, they don't quite
Speaker 1: hold up when we try to use them to explain
Speaker 1: a supermassive black hole, like they either like one example
Speaker 1: is looking at was that they don't they don't create
Speaker 1: these simulations do not create a supermassive black hole fast enough,
Speaker 1: you know, for them to be present in the universe. Yeah,
Speaker 1: that's right. There are competing hypotheses to explain the formation
Speaker 1: of supermassive black holes. But it seems like, at least
Speaker 1: as far as I've read, there are problems with all
Speaker 1: of the proposed hypotheses. I was reading one article that
Speaker 1: can consults a scientist and Mitch Bagelman of the University
Speaker 1: of Colorado, who works on supermassive black hole formation and
Speaker 1: and basically he was saying that the theories fall into
Speaker 1: two main categories. One is that you've got an original
Speaker 1: small seed black hole that takes a long time to
Speaker 1: get bigger as it absorbs more and more material, or
Speaker 1: you've got a very large original seed black hole from
Speaker 1: the collapse of some kind of hypothetical huge star that
Speaker 1: we're you know, we don't usually see, and it rose
Speaker 1: very quickly. But there are problems with both of these
Speaker 1: classes of explanations. But then there there are other more
Speaker 1: I don't know, more exotic theories as well. I guess yeah.
Speaker 1: When I was looking at is from seen from the
Speaker 1: Cavali Institute for the Physics and Mathematics of the Universe
Speaker 1: UM principal investigator uh nail Key Yoshida at All produced
Speaker 1: a paper in Science on this with an interesting take,
Speaker 1: uh you know, a different a different proposition for how
Speaker 1: a supermassive black hole might form against something something different
Speaker 1: from just the idea that it's the first generation of
Speaker 1: stars that have turned into black holes, and something different
Speaker 1: from just the idea that, you know, a massive primordial
Speaker 1: gas cloud that collapses under gravity. So this is how
Speaker 1: they lay out an alternate formation. First of all, you
Speaker 1: have a massive clump of dark matter, which forms when
Speaker 1: the universe is just a hundred million years old. Then
Speaker 1: supersonic gas streams generated by the big dayg are caught
Speaker 1: by it and form a dense gas cloud, a protostar
Speaker 1: forms inside um of this gas u and a protostar
Speaker 1: is a young star that is formed by gas cloud collapse.
Speaker 1: And then this protostar feeds on the gas cloud around
Speaker 1: it and grows at an accelerated rate. And then the
Speaker 1: protostar grows to a mass of thirty four thousand times
Speaker 1: that of our Sun. And all this by the ways
Speaker 1: in simulations they were running, uh, and then it collapses
Speaker 1: in on its own gravity, birthing a massive black hole
Speaker 1: in the early universe that only grows more massive and
Speaker 1: more gravitationally dominant as time grinds on. And this would
Speaker 1: explain why all or most massive galaxies appear to have
Speaker 1: a supermassive black hole at the center of them. Yes,
Speaker 1: that though, that is what they're trying to explain with this.
Speaker 1: But again, this is just another hypothesis for how what
Speaker 1: could have occurred to bring these things into being. Step
Speaker 1: one assumed dark matter. It makes sense to be uh
Speaker 1: looking at all different kinds of simulations because because I
Speaker 1: mean that again comes back to the origin of our
Speaker 1: understanding of the black hole. It began as this this uh,
Speaker 1: this vacancy yeah, in the in in the mathematics of
Speaker 1: the universe. Yeah, well, yeah, it began as a simulation.
Speaker 1: It was like these people running these different hypothetical simulations,
Speaker 1: but then it turned out that they actually exist. So
Speaker 1: maybe we should take a break, and then when we
Speaker 1: come back, we can look at some specific facts about
Speaker 1: this compact radio source at the center of the Milky
Speaker 1: Way galaxy, about Sagittarius A Stark. Alright, we're back. We're
Speaker 1: talking about supermassive black holes. Uh, not the Muse song,
Speaker 1: though I ended up being reminded of the Muse song
Speaker 1: Supermassive black Hole and and listen to it at least
Speaker 1: once during a research for this. If I know that,
Speaker 1: oh yeah, it's it's pretty good. Yeah, news has some
Speaker 1: great tracks, but hasn't been I don't think they're you know,
Speaker 1: astrophys sally accurate per se, but never mind, but I
Speaker 1: guess they're more accurate than say, you know, Sam Garden's
Speaker 1: black Hole Sun, which again, uh, as we already covered,
Speaker 1: is not actually going to happen no matter how many
Speaker 1: times we watched that music video. Growing up what was
Speaker 1: a long time ago, when we were doing how stuff
Speaker 1: works articles, I remember us brainstorming a like false science
Speaker 1: facts in song lyrics. Uh, and I remember that that
Speaker 1: was the one that came up. But another one that
Speaker 1: I'm made a case for and I don't think made
Speaker 1: it into the article was Fleetwood Mac thunder only happens
Speaker 1: when it rains. Not true, Not true at all. Yeah. Yeah,
Speaker 1: it's still a great track though. Yeah, they can't beat
Speaker 1: the Mac. Alright, Well, let's talk a little bit more
Speaker 1: about Sagittarius a star. Um So, I just want to
Speaker 1: just take apart its name a little bit more of
Speaker 1: which I think helps us understand exactly what we're talking about.
Speaker 1: Uh So, first of all, we've been talking about it
Speaker 1: being not only massive but super massive, Like what does
Speaker 1: that mean? Well, we're talking about roughly four point one
Speaker 1: million solar masses, with one solar mass being equal to
Speaker 1: the mass of our own son. So a single solar
Speaker 1: mass is two times ten to the thirty power kilograms
Speaker 1: are roughly two quintillion kilograms. The mass of of Sagittarius
Speaker 1: a star is roughly four point one million times that
Speaker 1: of our son. I was trying to find a point
Speaker 1: of comparison, so I was doing a little math, and
Speaker 1: one worked out just right. I think it's roughly the
Speaker 1: difference in mass between a twenty milligram house fly and
Speaker 1: a one hundred and eighty pounds Gean Claude van dam
Speaker 1: our Son is the fly twenty milligrams. Van dam is
Speaker 1: the supermassive black hole at at a hundred and eighty pounds.
Speaker 1: That works out just about right. All right, So we're
Speaker 1: talking like um, like time cop era vandam right. I
Speaker 1: mean here, I don't know. I just googled hundred vander
Speaker 1: because he's pretty dense, right, I mean it would be
Speaker 1: a good analogy for a black hole, I guess. So, yeah,
Speaker 1: that's right. Yeah. What's the thing he does in time
Speaker 1: coop to kill somebody? Oh? He does all sorts of
Speaker 1: things to kill somebody. I mean he he does the
Speaker 1: splits on on some kitchen sinks so that somebody electrocutes himself. Uh.
Speaker 1: He somebody is frozen with liquid nitrogen, and then he
Speaker 1: kicks their arm off. Um. I mean things get super
Speaker 1: trippy when he takes ron silver of the past and
Speaker 1: Ron silver of the future and kicks one into the other,
Speaker 1: and then they merge into a cosmic Google. Oh, there's
Speaker 1: got to be a black hole analogy there, right, black
Speaker 1: hole takes past you in future you and merges you somehow. Yeah,
Speaker 1: I've never quite worked out the science of that scene,
Speaker 1: but it has always stuck with me. Perhaps a reviewing
Speaker 1: of time cop Is is worthwhile in the future. Okay,
Speaker 1: but yeah, so our Sun is much bigger than the Earth,
Speaker 1: and the Sun is a housefly compared to his John
Speaker 1: club van Dam with the supermassive black hole. As we know,
Speaker 1: because of the limit physics that rule them, black holes
Speaker 1: don't quite take up the same amount of space as
Speaker 1: normal objects of the same mass. So how big is it? Well, yeah, well,
Speaker 1: let's let's talk about it's radius. Roughly it has it's
Speaker 1: roughly thirty one point six solar radius, So that means
Speaker 1: it's radius is thirty one point six times that of
Speaker 1: the radius of our own son, which is, by the way,
Speaker 1: six hundred and ninety five thousand, seven hundred kilometers or
Speaker 1: roughly four three hundred miles. Remember that the radius is
Speaker 1: half of the diameter. So even though it's more than
Speaker 1: four million times the mass of the Sun, because it's
Speaker 1: a black hole, it's still not like so wide that
Speaker 1: it would swallow up the entire Solar system if it
Speaker 1: were in the Sun's position, right, Just talking about like
Speaker 1: the physical space, it takes up its circumference. The distance
Speaker 1: around it is roughly forty four million kilometers or twenty
Speaker 1: seven roughly twenty seven million, three hundred forty thousand, three
Speaker 1: hundred and thirty two and a half miles and a half.
Speaker 1: Now this is really big, But it got me wondering.
Speaker 1: Is Sagittarius ay started the largest black hole we know about? Nope,
Speaker 1: not even holose. Contemplating the biggest ones should make your
Speaker 1: head implode if it hasn't already. How much bigger can
Speaker 1: black holes get? Well, it's hard to be certain because
Speaker 1: the mass of the black hole at the center of
Speaker 1: another galaxy has to be inferred right based on these
Speaker 1: periphery clues, like the brightness of the emissions presumed to
Speaker 1: be from its accretion jets or accretion disk or relativistic jets.
Speaker 1: Uh So, we don't know for sure, but we have estimates.
Speaker 1: Just one example on the highest end of estimates is
Speaker 1: a black hole called Town six eighteen t O N
Speaker 1: six eighteen and unbelievably luminous quays are and a galaxy
Speaker 1: billions of light years away. One of the brightest objects
Speaker 1: in the universe, the presumed supermassive black hole at the
Speaker 1: center of this radio source has been estimated to contain
Speaker 1: sixty six billion solar masses, and so it's thought that
Speaker 1: the the brightness of the stuff swirling into that supermassive
Speaker 1: black hole, it just completely outshines everything around, outshines all
Speaker 1: the stars in the galaxy around it. So sixty six
Speaker 1: billion solar masses with with the tonight compared to Sagittarius
Speaker 1: a star, which again four point one million solar masses, right,
Speaker 1: that's incredible. I mean, we're going from like unimaginably huge
Speaker 1: to um to something even beyond that. It's like four
Speaker 1: orders of magnitude above. But going back to Sagittarius a star.
Speaker 1: How close are we to it? Yeah, I have some
Speaker 1: people may be wondering that we're roughly twenty five thousand,
Speaker 1: nine hundred light years away, give or take one thousand,
Speaker 1: four hundred light years. This is going to depend on
Speaker 1: orbital positioning. Okay, so this is the very center of
Speaker 1: the Milky Way galaxy, and we're sort of in the middle.
Speaker 1: We're sort of like halfway out right between the center
Speaker 1: of the galaxy and and the farthest reaches of its arms.
Speaker 1: Very roughly, we're basically in a stable orbit around it. Yeah, because,
Speaker 1: as we'll discuss the I would think probably more in
Speaker 1: the next episode. Things get really rough the closer than
Speaker 1: you get, which should not come as a surprise. Uh. Now,
Speaker 1: we've already talked about the name itself, Sagittarius, the ninth
Speaker 1: astrological sign associated with the constellation Sagittarius, it's connection to centaurs.
Speaker 1: But let's come back around to that A star business.
Speaker 1: Oh yeah, so this is this thing can be confusing
Speaker 1: to a lot of people. We mentioned that it often
Speaker 1: makes us look for a footnote at the bottom of
Speaker 1: the page. I was looking into where the A star
Speaker 1: part comes from the asterisk, and I found a two
Speaker 1: thousand three paper by Goss, Brown and Low that explains
Speaker 1: the origins. So astronomer Robert L. Brown and colleague Bruce
Speaker 1: Ballack are credited with discovering the compact radio source of
Speaker 1: Sagittarius a star in nineteen seventy four, and Brown apparently
Speaker 1: named this object according to a made up convention that's
Speaker 1: kind of nerd cheeky. So he writes, quote, scratching on
Speaker 1: a yellow pad one morning, I tried a lot of
Speaker 1: possible names when I began thinking of the radio sources
Speaker 1: the exciting source for the cluster of HII regions seen
Speaker 1: in the v l A maps. The name Sagittarius a
Speaker 1: star occurred to me by analogy brought to mind by
Speaker 1: my PhD dissertation, which is in atomic physics, and where
Speaker 1: the nomenclature for excited state atoms is H E star
Speaker 1: or f E star, meaning like you know, helium star
Speaker 1: or iron star. So the star there is the excited
Speaker 1: state of the atom. And apparently this discovery was exciting
Speaker 1: in more ways than one. Now, one of the other
Speaker 1: reasons it is can it can potentially be confusing is
Speaker 1: because asterix means star. I mean, it basically derives from
Speaker 1: the Greek aster riscos, which means little star um and
Speaker 1: and another thing to keep in mind, I guess is
Speaker 1: that you know it's we're basically dealing with an astronomical
Speaker 1: radio source is the likely location of a supermassive black hole.
Speaker 1: Uh So, I guess it's more like referring to an
Speaker 1: unknown serial murder as the Green River Killer before you
Speaker 1: ever find out that his name is actually Gary. And again,
Speaker 1: as as you pointed out, it's also kind of like
Speaker 1: cheeky and uh and I think I've seen it referred
Speaker 1: to as being historical in nature, but there's also a
Speaker 1: broader thing of just Sagittarius A without the star. The
Speaker 1: star is this compact radio source believed to be the
Speaker 1: location of the supermassive black hole or the let's see
Speaker 1: the radio source emitting stuff around the supermassive black hole. Yeah,
Speaker 1: and then there's there's more two because there's a there's
Speaker 1: a Sagittarius A star, but there's also Sagittarius A east.
Speaker 1: This is likely the remains of a supernova explosion that
Speaker 1: occurred between thirty five thousand and a hundred thousand b
Speaker 1: c E, and scientists think that the ejecta of the
Speaker 1: supernova was gravitationally compressed due to a close approach by
Speaker 1: the supermassive black hole. Then there's Sagittarius A. Well, this
Speaker 1: is the mini spiral. It's sometimes called because from our
Speaker 1: perspective it looks like a three armed spiral, but it's
Speaker 1: actually a cloud of dust and gas. It's orbiting Sagittarius
Speaker 1: A star. And another question people might have was how
Speaker 1: old is Sagittarius A star? How long has there been
Speaker 1: a supermassive black hole festering at the center of our galaxy. Well,
Speaker 1: the answer I guess is it's it's staggeringly old. But
Speaker 1: it's hard to put a real fine line on that.
Speaker 1: The Milky Way galaxy itself is what the thirteen point
Speaker 1: two billion years old, and there are different formation theories
Speaker 1: regarding galaxies, and the universe itself is believed to be
Speaker 1: roughly thirteen point seven thirteen point eight billion years old.
Speaker 1: So um, yeah, I'm I think we can stand by
Speaker 1: staggeringly old and is it the center of things? You know,
Speaker 1: for for a reason? Yeah, And now when we think
Speaker 1: about that compared to say, our own solar system, our
Speaker 1: Solar system is just roughly four and a half billion
Speaker 1: years old, and it's one of the reminders that our
Speaker 1: Solar system and everything that makes our planet possible, that
Speaker 1: makes our bodies possible, it's not the first generation, right.
Speaker 1: We can only exist by the fact that previous generations
Speaker 1: of stars lived and burned and died catastrophically, creating the
Speaker 1: heavy elements that make up things like the planets in
Speaker 1: our Solar system. All the technology you're using to listen
Speaker 1: to this right now, and all the stuff in your
Speaker 1: bodies that's all made of gunk from Stars that went
Speaker 1: horribly wrong. Now, I think one important thing to keep
Speaker 1: in mind, you know, whenever we discussed black holes, but
Speaker 1: especially in this episode as well, is that despite the
Speaker 1: black hole being you know, a source of peril in
Speaker 1: various science fiction treatments, despite the fact that even in
Speaker 1: this episode we've we've discussed it and often like dark
Speaker 1: and forbidding ways, you know, it's not coming to get you. Yeah,
Speaker 1: it's not coming to to get us in. But then
Speaker 1: even more to the point, it is, um it is
Speaker 1: not like this negative like counterpoint. You know, it's not
Speaker 1: this evil thing in the universe, like the black The
Speaker 1: idea that there's a supermassive black hole at the center
Speaker 1: of our galaxy should not come as uh, you know,
Speaker 1: a point of fear or disappointment. You know, it's not.
Speaker 1: It's wonder and it is. It just shows that the
Speaker 1: black hole can be a thing that holds, uh holds
Speaker 1: everything together. You know, these are that's part of the
Speaker 1: building blocks of of of the galaxy of the universe.
Speaker 1: And uh, you know, therefore we we can't think in
Speaker 1: you know, simplistic terms about it being you know, just
Speaker 1: like some sort of venomous uh you know, has us
Speaker 1: off like formation. No, it's not venomous, because what the
Speaker 1: venomous thing would would inject you with venom? Right, this
Speaker 1: sucks it out? Yeah yeah, I mean if anything is
Speaker 1: injecting us with venom, right, it's the solar radiation emerging
Speaker 1: from a start that necessary to life. To be fair,
Speaker 1: I guess the supermassive black hole what it Emits lots
Speaker 1: of radiation, so you can think of that is it? Anyway,
Speaker 1: It's not venom It's just a fantastically interesting object out
Speaker 1: there in space, so much so that we want to
Speaker 1: do a whole other episode on it. We we wanted
Speaker 1: to come back next time and deal with everything you've
Speaker 1: always wanted to know about the supermassive black hole at
Speaker 1: the center of the galaxy. But we're afraid to ask, Yeah,
Speaker 1: can you live on it? Um? Can you eat it?
Speaker 1: Questions like this? You know we will. We will get
Speaker 1: into in our next episode. In the meantime, if you
Speaker 1: want to check out other episodes of Stuff to Blow
Speaker 1: your Mind, you know where to find them. Stuff to
Speaker 1: Blow your Mind dot com. That's where you'll find them all,
Speaker 1: including those previous episodes on black holes. Likewise, we mentioned
Speaker 1: Invention If you go to invention pot dot com you'll
Speaker 1: find our other podcast, Invention. That's where you'll find that, uh,
Speaker 1: that episode on the telescope that came out, as well
Speaker 1: as episodes on the you know, the the the invention
Speaker 1: of the photograph, the motion picture, etcetera. It is a
Speaker 1: invention by invention, an exploration of human techno history and
Speaker 1: let's see what else. Yeah, If you want to support
Speaker 1: our show, really, the best thing you can do is
Speaker 1: spread the word, tell your friends about about us, tell
Speaker 1: your family members about us, and if you have the
Speaker 1: ability to do so, rate and review us wherever you
Speaker 1: get your podcasts. Huge thanks as always to our excellent
Speaker 1: audio producer Maya Cole. If you'd like to get in
Speaker 1: touch with us with feedback on this episode or any other,
Speaker 1: suggest a topic for the future, just to say hello,
Speaker 1: you can email us at contact at stuff to Blow
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