Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomy podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: I want you to imagine, just for a moment, that
Speaker 2: you are tasked with assembling like a grand, sweeping family tree. Okay,
Speaker 2: sounds fun, right, but this isn't human ancestry. You're mapping
Speaker 2: out a cosmic family tree, tracing the lineage of the
Speaker 2: most extreme gravity warping objects in the universe.
Speaker 3: Oh, black holes.
Speaker 2: Exactly black holes. And as you lay out all this data,
Speaker 2: you hit a wall. You realize something profoundly weird, and
Speaker 2: entire generation is completely missing. Yeah, a massive blank space, right, Like,
Speaker 2: we can eat see the colossal ancient ancestors sitting at
Speaker 2: the top of the chart, and we can clearly identify
Speaker 2: the tiny, numerous descendants scattered all over the bottom. But
Speaker 2: the middle generation it's just invisible.
Speaker 3: It's completely absent, a.
Speaker 2: Glaring blank space. You've probably heard of supermassive black holes.
Speaker 2: You know those absolute monsters lurking at the center of galaxies,
Speaker 2: and you almost certainly know about the smaller ones, the
Speaker 2: stellar mass black holes formed from dying stars. But today
Speaker 2: we're venturing out into the utter void of deep space
Speaker 2: to find the missing middle.
Speaker 3: We really are, and it's one of the most frustrating
Speaker 3: yet mathematically tantalizing blind spots in modern astrophysics.
Speaker 2: Tantalizing is a good word for it, because we're going
Speaker 2: to look at how researchers are taking one of the
Speaker 2: universe's greatest.
Speaker 3: Mysteries, mass radio bursts.
Speaker 2: Yeah, these fleeting, unexplained flashes of radio waves from deep space,
Speaker 2: and they're essentially repurposing them as cosmic flashlights to expose
Speaker 2: those elusive middleweight black holes.
Speaker 3: It's wild because the fact that we have the extremes
Speaker 3: perfectly documented, but the bridge between them has eluded us
Speaker 3: for decades. It suggests that while either our theories of
Speaker 3: how the universe grows are fundamentally flawed, or these objects
Speaker 3: are hiding in a way we simply hadn't anticipated.
Speaker 2: Right before we talk about how we're finally hunting them down,
Speaker 2: let's establish why it's so strange that we can't find them.
Speaker 2: Let's talk about these cosmic weaight.
Speaker 3: Classes, good idea, because size dictates completely different physics here exactly.
Speaker 2: So at the very top of the hierarchy, the undisputed heavyweights,
Speaker 2: we have super massive black holes. These are the anchors, right.
Speaker 3: Yeah, the anchors like Sagittarius, a star at the center
Speaker 3: of our Milky.
Speaker 2: Way, right, and virtually every other major galaxy has one. Yeah,
Speaker 2: and we are talking about masses that are millions or
Speaker 2: I mean even billions of times the mass of our Sun.
Speaker 3: To give you a sense of scale, the black hole
Speaker 3: at the center of the galaxy M eighty seven, which
Speaker 3: was famously imaged a few years ago.
Speaker 2: Oh, the glowing doughnut picture.
Speaker 3: Yeah, the glowing orange ring. That one is about six
Speaker 3: and a half billion times the mass of our Sun.
Speaker 2: Billion with a bee.
Speaker 3: With a b. These supermassive objects are the gravitational pivots
Speaker 3: for entire galaxies. And you know, their origins are actually
Speaker 3: still heavily.
Speaker 2: Debated, really, like how they got so big.
Speaker 3: Yeah, whether they started out as smaller seeds that merged
Speaker 3: over billions of years, or if they collapsed directly from
Speaker 3: massive clouds of gas in the early universe. But regardless
Speaker 3: of how they got there, they are allowed.
Speaker 2: Right. They aren't exactly hiding, not at all.
Speaker 3: They're surrounded by accretion disks of superheated plasma that shine
Speaker 3: brighter than the rest of the galaxy combined, so we
Speaker 3: have no problem finding them.
Speaker 2: Through the cosmic lighthouses. And then at the other end
Speaker 2: of the observable spectrum, we have the lightweights, the stellar
Speaker 2: mass black holes, the descendants. If we're keeping with a
Speaker 2: family tree analogy. These are born when a massive star
Speaker 2: reaches the end of its life, runs out of nuclear fuel,
Speaker 2: and the core just collapses under its own staggering gravity.
Speaker 3: Yeah, and these usually weigh in and that roughly five
Speaker 3: to a few tens of times the mass of our Sun.
Speaker 2: And the physics of stellar collapse, yeah, it puts a
Speaker 2: natural cap on how big these can get, right.
Speaker 3: It does. When a star is massive enough, the pressure
Speaker 3: and temperature inside its core gets so incredibly high that
Speaker 3: it actually triggers this phenomenon called pair instability.
Speaker 2: Pair instability, what is that?
Speaker 3: It's where photons literally particles of light, spontaneously turn into
Speaker 3: electron positron pairs.
Speaker 2: Wait, light just turns into matter.
Speaker 3: Yeah, under those extreme conditions, and when that happens, it
Speaker 3: causes a sudden drop in outward pressure, the star collapses,
Speaker 3: and the resulting supernova completely obliterates the star, leaving absolutely
Speaker 3: nothing behind, no black hole at all. Because of these mechanisms,
Speaker 3: standard stellar evolution really struggles to produce black holes much
Speaker 3: heavier than say, sixty to one hundred solar masses.
Speaker 2: Okay, so I've got the supermassives and the stellar ones,
Speaker 2: but just to put all our cards on the table,
Speaker 2: there's also a theoretic featherweight class. Right, Yeah, primordial black holes.
Speaker 3: Yes, primordial black holes. And these are distinct because they
Speaker 3: weren't born from dying stars.
Speaker 2: They predate stars entirely.
Speaker 3: The theory goes that in the chaotic high energy environment
Speaker 3: just fractions of a second after the Big Bang, the
Speaker 3: universe wasn't perfectly smooth. It was a clumpy, right, There
Speaker 3: were microscopic quantum fluctuations in some incredibly tiny regions. The
Speaker 3: density of matter and radiation was so intensely concentrated that
Speaker 3: it just collapsed directly into black holes.
Speaker 2: Before atoms even existed.
Speaker 3: Exactly, and depending on exactly when they formed in that
Speaker 3: first split second, they could theoretically be the mass of
Speaker 3: like an asteroid or a mountain, but squeeze down into
Speaker 3: a space smaller than a single atom.
Speaker 2: Okay, So we have the supermassive giants anchoring galaxies, the
Speaker 2: skellar mass remnants scattered around, and potentially these tiny primordial
Speaker 2: specks left over from the dawn of time. Right. But
Speaker 2: then we look for the intermediate class, the middleweights, the
Speaker 2: intermediate mass black holes, the missing link. Theoretically, these should
Speaker 2: weigh somewhere between one hundred and one hundred that solar masses. Yeah,
Speaker 2: but we look at into the universe and.
Speaker 3: Well, nothing, nothing conclusive yet.
Speaker 2: Like exploring the African savannah, right, and you find millions
Speaker 2: of mice, and you find massive herds of elephants, but
Speaker 2: you look around and realize there is absolutely zero evidence
Speaker 2: of anything the size of a dog or a gazelle
Speaker 2: or a horse.
Speaker 3: That's a great analogy.
Speaker 2: Are we just bad at looking or are the laws
Speaker 2: of physics actively preventing them from forming?
Speaker 3: Well, that is exactly the debate that has raged for years.
Speaker 3: From a theoretical standpoint, they absolutely must exist.
Speaker 2: Why must they.
Speaker 3: Because the supermassive black holes we see in the early
Speaker 3: universe are too big to have grown from stellar mass
Speaker 3: black holes purely by eating surrounding gas.
Speaker 2: The math doesn't work out right.
Speaker 3: There simply hasn't been enough time since the Big Bang
Speaker 3: for them to get that heavy. They had to have
Speaker 3: merged from intermediate seeds.
Speaker 2: Okay, so they have to be out there. Why can't
Speaker 2: we see them?
Speaker 3: Finding them isolated today is notoriously difficult because, unlike super
Speaker 3: massive black holes that have entire galaxies of gas and
Speaker 3: stars swirling around them, an isolated middleweight black hole wandering
Speaker 3: through space doesn't have a glowing accretion disk.
Speaker 2: So if it isn't eating, it isn't shining.
Speaker 3: Exactly, if it isn't actively feeding on something, it emits
Speaker 3: no light. It is a completely dark object against a
Speaker 3: completely dark background.
Speaker 2: But it's not just about filling in a blank on
Speaker 2: a spreadsheet, is it. It's not just, oh, we need
Speaker 2: to collect the middle one to finish the set. Why
Speaker 2: do astrophysicists actually care so much about finding an object
Speaker 2: in this specific.
Speaker 3: Weight class because they represent a pristine environment to test
Speaker 3: what physicists call strong field gravity.
Speaker 2: Strong field gravity break that down for me. You mean
Speaker 2: areas where gravity isn't just pulling a planet in an orbit,
Speaker 2: but doing something fundamentally more aggressive.
Speaker 3: Yeah, exactly. Think about the gravity we experience in our
Speaker 3: Solar system. It's incredibly weak. Even the gravity of the Sun,
Speaker 3: which keeps Earth in orbit, is considered weak. Feel in
Speaker 3: the context of general relativity.
Speaker 2: Really the Sun is weak.
Speaker 3: Cosmologically speaking, yes, Newtonian physics can describe almost all of
Speaker 3: it perfectly. But near the event horizon of a black hole,
Speaker 3: space time is severely violently warped.
Speaker 2: It gets weird, very weird.
Speaker 3: It is stretched and twisted in ways that push Einstein's
Speaker 3: equations to their absolute limits. Testing our theories of physics
Speaker 3: and these extreme environments is crucial.
Speaker 2: But couldn't we just test that on those super massive
Speaker 2: black holes.
Speaker 3: We try, but they are incredibly messy environments. They're filled
Speaker 3: with magnetic fields, plasma jets, swirling matter, radiation.
Speaker 2: It's too noisy.
Speaker 3: Exactly, an isolated intermediate mass black hole would be a clean,
Speaker 3: quiet laboratory, a pure distortion in space time without all
Speaker 3: the astrophysical noise.
Speaker 2: That makes a lot of sense. But the history of
Speaker 2: trying to find these things is just a string of heartbreaks.
Speaker 2: I mean, every time we think we have one it
Speaker 2: slips away. Let's talk about the Omega Centauri controversy.
Speaker 3: Oh yeah, the classic cautionary tale in this.
Speaker 2: Field, because I think that perfectly illustrates how maddening this
Speaker 2: search has been. So for context, if you aren't familiar
Speaker 2: with Omegasentaury, it is the largest globular cluster in the
Speaker 2: Milky Way galaxy.
Speaker 3: It's huge.
Speaker 2: It's this incredibly dense spherical collection of millions of ancient stars,
Speaker 2: all packed tightly together, orbiting the center of our galaxy.
Speaker 2: And back in two thousand and eight it made massive
Speaker 2: headlines because it seemed like the missing link had finally
Speaker 2: been found right in our cosmic backyard. I remember observations
Speaker 2: from the Hubble Space telescope and the Gemini Observatory down
Speaker 2: in Chile suggested that there was a massive, invisible object
Speaker 2: sitting perfectly in the center of that star cluster.
Speaker 3: Yeah. The researchers were looking at the kinematics of the cluster,
Speaker 3: specifically how fast the stars right at the dense.
Speaker 2: Core weremoving like bees swarming a hive.
Speaker 3: Right By using the Doppler shift of the light from
Speaker 3: those stars, they measured the velocity dispersion, and they found
Speaker 3: that the stars near the center were whipping around much
Speaker 3: faster than they should be based on the visible mass
Speaker 3: of the stars alone.
Speaker 2: So there's extra gravity coming from somewhere Exactly.
Speaker 3: The gravitational math seemed inescapable. There had to be a
Speaker 3: central concentrated mass of about forty thousand times the mass
Speaker 3: of the Sun pulling on them.
Speaker 2: Forty thousand so right in that intermediate sweet spot. Yep.
Speaker 3: And since it emitted no light, it perfectly fit the
Speaker 3: profile of an intermediate mass black hole.
Speaker 2: I remember when that paper came out. It felt like
Speaker 2: a slam dug. We found the missing link. But then
Speaker 2: the scientific method showed up to ruin the party.
Speaker 3: Well ruin or refined, depending on how you look at it. Enough,
Speaker 3: the problem with looking into the center of a globular
Speaker 3: cluster is that it is a dynamically complex, chaotic environment.
Speaker 3: Follow up research heavily disputed those two thousand and eight claims.
Speaker 2: Oh, so did they get the telescope data wrong?
Speaker 3: No, the data was right. Other teams just build incredibly
Speaker 3: complex n body simulations computer models that calculate the gravitational
Speaker 3: interactions of millions of individual stars over billions of years.
Speaker 2: Wait, so they didn't just disagree with the data, they
Speaker 2: disagreed with what the data meant exactly.
Speaker 3: The counter argument reposed a mechanism called mass segregation.
Speaker 2: A mass segregation over.
Speaker 3: Billions of years, the heavier objects in a star cluster
Speaker 3: will naturally sink to the center due to gravitational friction,
Speaker 3: while lighter stars get pushed.
Speaker 2: Outward, like heavy rock sinking to the bottom of a river.
Speaker 3: Yes, so what if that dark mass at the center
Speaker 3: wasn't one single forty thousand solar mass black hole. What
Speaker 3: if it was a swarm of a few thousand stellar
Speaker 3: mass black holes, neutron stars and dead white dwarfs that
Speaker 3: had all sunk to the core. Oh wow, they would
Speaker 3: be invisible. They would collectively have enough mass to make
Speaker 3: the other stars whip around quickly, and they wouldn't require
Speaker 3: us to invent a new class of black hole to
Speaker 3: explain them.
Speaker 2: So the definitive proof basically just evaporated pretty much. Could
Speaker 2: be one giant thing, or it could be a swarm
Speaker 2: of small things. And from Earth it just looks the
Speaker 2: same right as it stands now, just by decades of
Speaker 2: staring into the heart of these dense star clusters, the
Speaker 2: existence of intermediate mass black holes remains entirely unconfirmed.
Speaker 3: We are zero for zero, which forces a paradigm shift.
Speaker 3: If you can't find the invisible object by looking at
Speaker 3: the stars swirling around it because the environment is just
Speaker 3: too crowded and noisy, you have to find a completely
Speaker 3: different method.
Speaker 2: You have to look at what the black hole does
Speaker 2: to light that just happens to be passing by it
Speaker 2: from somewhere else exactly, And to do that you need
Speaker 2: a very specific kind of light, a very specific probe,
Speaker 2: which introduces the second massive mystery of our conversation. Fast
Speaker 2: radio bursts.
Speaker 3: Oh yeah, FRBs.
Speaker 2: Now, if you are not an astrophysics nerd, you might
Speaker 2: be thinking, okay, radio burst, what's the big deal? But
Speaker 2: fast radio bursts or FRBs are the tools that astrophysicists
Speaker 2: are now trying to use to find the missing black holes,
Speaker 2: and they are wild, they really are. To understand how
Speaker 2: this works, we need to talk about what an FRB
Speaker 2: actually is, or rather what we observe them to be,
Speaker 2: since we don't actually know what they are.
Speaker 3: They are arguably the most active mystery astronomy today. I mean,
Speaker 3: the first one was discovered purely by accident in two
Speaker 3: thousand and seven.
Speaker 2: Wait, by accident.
Speaker 3: Yeah, it was retroactively found in archival data from the
Speaker 3: Park's radio telescope. In Australia. It's often called the Lorimer burst,
Speaker 3: named after the astronomer who found it.
Speaker 2: And when we say fast, we really mean it, don't we. Oh?
Speaker 3: Absolutely. These are transient pulses of radio emission and FRB
Speaker 3: can last for as little as a tiny fraction of
Speaker 3: a microsecond, maybe up to a few seconds on the
Speaker 3: extreme long.
Speaker 2: End, but most are over in the blink of an eye.
Speaker 3: But it's not just their brevity that makes them astounding,
Speaker 3: it's what that brevity implies about their power.
Speaker 2: Right because they're coming from far away.
Speaker 3: We know these bursts are coming from outside our galaxy,
Speaker 3: and we know this because of a property called dispersion.
Speaker 2: Dispersion Okay, how does that work?
Speaker 3: As radio waves travel through the incredibly sparse cold plasma
Speaker 3: in the inner galactic medium, the lower frequencies get slowed
Speaker 3: down just a tiny tiny bit more than the higher.
Speaker 2: Frequencies, like light passing through a prism.
Speaker 3: Very similar. Yeah, so when the burst hits are telescopes,
Speaker 3: the high frequencies arrive a fraction of a second before
Speaker 3: the low frequencies. It smears out. By measuring that smear
Speaker 3: that dispersion measure, we can calculate roughly how much space
Speaker 3: the bursts traveled through.
Speaker 2: And the dispersion measures for FRBs are.
Speaker 3: Huge, massive. They tell us these flashes are traveling across
Speaker 3: billions of light years of space. Now, just think about
Speaker 3: the energy required for that, oh Man, for a signal
Speaker 3: that lasts a fraction of a millisecond to be detectable
Speaker 3: by our telescopes here on Earth, after radiating outward in
Speaker 3: all directions and crossing billions of light years, I mean,
Speaker 3: the source of that birds must be unimaginably powerful.
Speaker 2: How powerful are we talking?
Speaker 3: We are talking about an event that releases as much
Speaker 3: energy in one millisecond as our sun emits in three days.
Speaker 2: In one millisex. Yeah, okay, I have to stop and
Speaker 2: push back on the logic of this entire endeavor right here.
Speaker 2: Let me get this straight. We are trying to solve
Speaker 2: the mystery of the missing intermediate black holes. Yes, to
Speaker 2: do this, we're using another completely un mystery, these fast
Speaker 2: radio bursts, as our primary tool. We are That feels
Speaker 2: like trying to find a hidden object in a pitch
Speaker 2: black room by using a flashlight, but you don't even
Speaker 2: know how the flashlight works, who manufactured it, or who
Speaker 2: is holding it. From a rigorous scientific standpoint, how is
Speaker 2: that sound? How can you use an unknown to measure
Speaker 2: an unknown?
Speaker 3: It sounds like a paradox, I know, but it's actually
Speaker 3: a deeply established tradition in physics. Really, Yeah, sometimes the
Speaker 3: behavior of the probe is actually more important than its origin.
Speaker 3: If we return to your dark room analogy, it genuinely
Speaker 3: does not matter if you don't know the brand of
Speaker 3: the flashlight, or what kind of batteries it uses, or
Speaker 3: the chemical composition of the bulb. Okay, what matters is
Speaker 3: that it is projecting a powerful, incredibly sharp, clean beam
Speaker 3: of light straight across the room.
Speaker 2: Ah, Because whatever that beam of light hits or passes
Speaker 2: through is going to alter the beam, and we can
Speaker 2: measure the alteration even if we don't know the source precisely.
Speaker 3: Even if we don't know if an FRB is created
Speaker 3: by a highly magnetized neutron star, a colliding binary system,
Speaker 3: or something completely beyond our current physics, we know its
Speaker 3: properties as it travels.
Speaker 2: We know it's a straight line of radio waves, right.
Speaker 3: We know it acts almost exactly like a point source
Speaker 3: of light. We know it emits a sharp, coherent burst
Speaker 3: of radio waves crossing vast cosmic distances. That makes it
Speaker 3: a perfect naturally occurring backlight for whatever it bumps into
Speaker 3: along its journey to Earth.
Speaker 2: It's an ideal tool for eliminating the invisible obstacles in
Speaker 2: the deep universe. Exactly, Okay, So let's put the two
Speaker 2: pieces together. What exactly happens when this mysterious microsecond flash
Speaker 2: of radio waves bumps into an invisible middleweight black hole.
Speaker 2: It isn't like shining a flashlight at a brick wall
Speaker 2: where the light just stops or reflex right. Gravity does
Speaker 2: something far stranger, much strang It creates a very specific
Speaker 2: kind of cosmic optical illusion. And this brings us to
Speaker 2: the core mechanism of the whole search. Gravitational microlensing.
Speaker 3: This is where that severe warping of space time you
Speaker 3: mentioned earlier comes into.
Speaker 2: Play, right the strong field gravity.
Speaker 3: Yes, gravitational microlensing is a direct observable consequence of Einstein's
Speaker 3: theory of general relativity. Mass bends space. John Archibald Wheeler
Speaker 3: famously summarized it. Space time tells matter how to move.
Speaker 3: Matter tells space time how to curve.
Speaker 2: I love that quote, it's perfect.
Speaker 3: But the thing is space time also tells light how
Speaker 3: to move.
Speaker 2: Let me try to visualize this. Let's say a galaxy
Speaker 2: three billion light years away fires off a fast radio burst.
Speaker 2: That little package of radioways starts traveling in a perfectly
Speaker 2: straight line toward Earth. But directly in its path, lurking
Speaker 2: completely unseen in the darkness of intergalactic space, is an
Speaker 2: intermediate mass black hole. As that FRB gets close to
Speaker 2: the black hole, it doesn't just fly straight past it, right, Yeah,
Speaker 2: Because the space around the black hole isn't flat exactly.
Speaker 3: The black hole is acting as what we call a
Speaker 3: point mass lens. Its extreme gravity has created a deep,
Speaker 3: a severe geometric curve in the very fabric of space.
Speaker 2: Time around it, like a bowling ball on a trampoline.
Speaker 3: Yes, the classic analogy. It's not that the light is
Speaker 3: being pulled by gravity the way a planet is. Rather,
Speaker 3: the light is always traveling in a straight line, but
Speaker 3: the space itself.
Speaker 2: Is curved, so the straight line becomes a curve.
Speaker 3: Right, So when the effrob enters that warped region, the
Speaker 3: path of the light is forced to follow the curve.
Speaker 3: Of space bending around the black hole.
Speaker 2: Okay, let's say I'm looking at a candle on a
Speaker 2: table and I place let's see, not a funhouse marre,
Speaker 2: that just scatters things. What if I place a thick,
Speaker 2: curved piece of glass right in front of the candle,
Speaker 2: like the base of a thick wine goblet. Okay, yeah,
Speaker 2: the curved glass physically bends the light rays from the candle.
Speaker 2: So when the light finally reaches my eye, my brain,
Speaker 2: which assumes light travels in straight lines, traces those bent
Speaker 2: rays backwards and sees two distinct candle flames instead of one.
Speaker 2: That's spot on. In our cosmic scenario, the black hole
Speaker 2: is the base of the wine glass bending the radio burst.
Speaker 3: That is a phenomenal way to picture it. The gravity
Speaker 3: of the black hole forces the light to take two
Speaker 3: separate paths around it to reach us. But here is
Speaker 3: what's crucial for the researchers. How does this bending actually
Speaker 3: look to our telescopes when we analyze the data.
Speaker 2: Because we can't actually see two flashes of light right now.
Speaker 3: No, we don't have telescopes with the spatial resolution to
Speaker 3: actually see two separate flashes of light in the sky.
Speaker 3: The angular separation is incredibly tiny on the scale of
Speaker 3: milliarc seconds or less.
Speaker 2: Right, because an FRB is so far away, it's just
Speaker 2: a single pixel of data hitting our radio dish. So
Speaker 2: how do we know it was split time?
Speaker 3: The speed of light is absolute. If an FRB travels
Speaker 3: through empty space, our telescopes record a single sharp spike
Speaker 3: of rato waves, a single peak on the graph. Okay,
Speaker 3: but if that FRB has been micro lensed by a
Speaker 3: black hole, it took two different paths to get here,
Speaker 3: and in the geometry of curved space, those two paths
Speaker 3: are almost certainly not the exact same.
Speaker 2: Length, So one path is longer than the other, exactly.
Speaker 3: Furthermore, the light traveling closer to the black hole experiences
Speaker 3: a deeper gravitational well, causing what's known as the Shapiro
Speaker 3: time delay.
Speaker 2: The Shapiro time delay, what's that.
Speaker 3: It means time itself moves slightly slower in a stronger
Speaker 3: gravitational field relative to the observer.
Speaker 2: Oh wow, So you have the physical path being longer
Speaker 2: and the local time for the light ray literally slowing down.
Speaker 3: Yes, exactly, So one path takes a tiny fraction of
Speaker 3: a millisecond longer to reach Earth than the other path.
Speaker 3: The single burst of radio waves arrives at our telescopes
Speaker 3: at two slightly.
Speaker 2: Different times, Like an echo.
Speaker 3: It appears on our readouts as a clear multipeak structure,
Speaker 3: one burst superimposed with its own echo, arriving mere milliseconds apart.
Speaker 2: Wait, if I'm tracking the physics here, this isn't just
Speaker 2: a need visual trick. This is essentially a scale. Isn't
Speaker 2: it a mathematical scale to weigh the invisible object?
Speaker 3: It is exactly a scale. The time delay between those
Speaker 3: two peaks, that split second difference in their arrival is
Speaker 3: directly mathematically to determined by the mass of the object
Speaker 3: that bent the light.
Speaker 2: Really just from the delay yep.
Speaker 3: The heavier the black hole, the deeper the space time curve,
Speaker 3: the wider the paths diverge, and the longer the delay
Speaker 3: between the original pulse and the echo that is wild.
Speaker 3: By measuring that tiny delay between the echoes, physicists can
Speaker 3: work backward through the equations of general relativity and calculate
Speaker 3: the exact mass of the invisible lens.
Speaker 2: That is breathtaking, which means if we find the right
Speaker 2: kind of echo hidden in the data of a fast
Speaker 2: radio burst, we can precisely weigh an invisible black hole
Speaker 2: that is billions of light years away and completely dark.
Speaker 3: That is the theory, yes, and it is an elegant
Speaker 3: application of physics. But until recently it was just a theory.
Speaker 3: We simply didn't have enough high resolution data on fast
Speaker 3: radio bursts to search for these microsecond echoes.
Speaker 2: And this is where the groundbreaking new research comes in.
Speaker 2: This is where theory hits reality. A team led by
Speaker 2: Juanzou at the School of Physics and opto Electronic Engineering
Speaker 2: at Yang's University recently put this exact method to the test.
Speaker 2: They did they didn't just write another theoretical paper. They
Speaker 2: went hunting. They dove into a massive database called the
Speaker 2: Canadian Hydrogen Intensity Mapping Experiment or CHIME, specifically the Chia
Speaker 2: Chime FRB catalog too. Now I want to talk about
Speaker 2: CHIME for a second, because it is not what you
Speaker 2: picture when you think of a telescope.
Speaker 3: No, not at all. If you picture a giant steerable
Speaker 3: satellite dish pointing at the sky, you have the completely wrong.
Speaker 2: Image like the one in context.
Speaker 3: Ya exactly, the RCIBO kind of dish. Chime isn't like that.
Speaker 3: It looks more like a series of four massive snowboarding
Speaker 3: half pipes sitting out in a valley in.
Speaker 2: British Columbia, the Barding half pipes.
Speaker 3: It consists of four cylindrical parabolic reflectors, each one hundred
Speaker 3: meters long, with no moving parts whatsoever.
Speaker 2: It just stares straight up right.
Speaker 3: It relies on the rotation of the Earth to sweep
Speaker 3: the sky. But what makes it so revolutionary is its
Speaker 3: digital back end. It uses an incredibly powerful supercomputer core
Speaker 3: later to process massive amounts of radio data in real times.
Speaker 2: It was more computer than telescope.
Speaker 3: In many ways. Yes, it essentially forms thousands of digital
Speaker 3: beams to monitor a huge swath of the sky simultaneously.
Speaker 3: Because FRBs can appear anywhere at any time without warning,
Speaker 3: you need a telescope with a massive field of view.
Speaker 2: You can't just point a small telescope and hope one
Speaker 2: happens exactly.
Speaker 3: C Chia is essentially the ultimate wide angle lens for
Speaker 3: transient radio signals. It has completely transformed the field, building
Speaker 3: a comprehensive catalog of hundreds of these fleeting bursts.
Speaker 2: It is a treasure trope of data for researchers looking
Speaker 2: for anomalies. So Hanzu's team analyzed this vast catalog, searching
Speaker 2: specifically for FRBs that exhibited that clear multipeak structure, the
Speaker 2: telltale echo of gravitational microlensing.
Speaker 3: And they were incredibly thorough right.
Speaker 2: They meticulously ruled out bursts where the multipeak structure could
Speaker 2: be caused by noise in the data or known scattering
Speaker 2: effects from interstellar gas. At all the data, they found
Speaker 2: two very specific microlensing signatures that stood out.
Speaker 3: And this is where the rigorous mathematical modeling pays off.
Speaker 3: When they applied those general relativity lensing equations to the
Speaker 3: precise time delays of those specific echoes, the numbers they
Speaker 3: got were extraordinary.
Speaker 2: The moment of truth, they calculated the mass of the
Speaker 2: invisible lenses that caused those two echoes. For the first signature,
Speaker 2: the mathematics inferred a mass somewhere between five hundred and
Speaker 2: thirty nine and six hundred and nine times the mass
Speaker 2: of our Sun. Incredible, And for the second signature, the
Speaker 2: inferred mass was between one thousand, five hundred and forty
Speaker 2: four and two thousand, five hundred and seventy one solar masses.
Speaker 3: Both of those specific ranges around six hundred solar masses
Speaker 3: and around two thousand solar masses. They sit perfectly squarely
Speaker 3: within that elusive intermediate mass black hole gap.
Speaker 2: They fit right in the blank space on the family tree.
Speaker 3: Yes, they're far too heavy to be stellar mass black
Speaker 3: holes and far too light to be super massive black hole.
Speaker 2: Okay, but let's play Devil's advocate here. Let's say I'm
Speaker 2: an astrophysicist reading this paper, and I want to be
Speaker 2: as skeptical as possible. Please, do we found something heavy
Speaker 2: that bends light? We know what weighs, say two thousand
Speaker 2: times the mass of the Sun, But how do we
Speaker 2: know it's a black hole? Space is full of stuff.
Speaker 2: How do we know the light wasn't bent by a
Speaker 2: really dense dark cloud of gas or maybe a really
Speaker 2: tight ancient cluster of dead stars like what they thought
Speaker 2: was happening in omegasentury.
Speaker 3: It's the essential question, and the answer lies in the
Speaker 3: specific constraints of the point mass lens geometry. To bend
Speaker 3: light in this very clean, specific way, to create that distinct, sharp,
Speaker 3: unscattered multipeak structure from a coherent radio burst, the echo
Speaker 3: the echo right the mass doing the bending must be
Speaker 3: unimaginably compact, the physical size of the lens has to
Speaker 3: be smaller than the Einstein ring radius.
Speaker 2: It creates the Einstein ring radius, meaning the physical spread
Speaker 2: of the bent light exactly.
Speaker 3: If the object doing the bending is physically wider than
Speaker 3: the paths the light ticks around it. The light just
Speaker 3: hits the object or passes through the object and get scattered, absorbed,
Speaker 3: or smeared out. It doesn't create a clean echo.
Speaker 2: So a gas cloud wouldn't work.
Speaker 3: Not even close. A cloud of gas weighing two thousand
Speaker 3: solar masses would be diffuse. It would be spread out
Speaker 3: over light years. It wouldn't ben the light sharply like
Speaker 3: the base of a wineglass.
Speaker 2: You could just be fog exactly.
Speaker 3: The radio bursts would pass through it, and the free
Speaker 3: electrons in the gas would smear the signal entirely, changing
Speaker 3: its dispersion measure in ways we could easily identify.
Speaker 2: And what about a tight cluster of dead stars?
Speaker 3: Even if you packed thousands of white dwarfs and neutron
Speaker 3: stars together as tightly as physically possible without the merging,
Speaker 3: cluster of two thousand solar masses would still be far
Speaker 3: too physically large. Plus an environment that dense would be
Speaker 3: incredibly violent.
Speaker 2: Lots of collisions.
Speaker 3: Stars would collide, accrete matter, and emit their own ambient light,
Speaker 3: X rays or thermal radiation. We would detect that surrounding.
Speaker 2: Noise, but the data shows nothing.
Speaker 3: Nothing at all. These lenses are completely dark and their
Speaker 3: gravitational focus is razor sharp at these specific mass ranges.
Speaker 3: Physics dictates that an object this massive, this physically compact,
Speaker 3: and this completely electromagnetically silent, can really.
Speaker 2: Only be one thing, a black hole.
Speaker 3: The matter has to be crushed down below its own
Speaker 3: Schwartz Child radius. It has to be a black hole.
Speaker 2: That is staggering. Finding these specific masses, actually weighing these
Speaker 2: objects and seeing they fit the missing Middleway profile is
Speaker 2: a monumental achievement on its own. It feels like we
Speaker 2: finally have our first real tangible map to the missing
Speaker 2: generation we talked about at the beginning.
Speaker 3: That's a huge milestone.
Speaker 2: But here is where the research takes a massive turn.
Speaker 2: The researchers realized that where these objects are located might
Speaker 2: actually be an even bigger discovery than their mass. The
Speaker 2: spatial context of these two detections might literally rewrite our
Speaker 2: understanding of the early universe.
Speaker 3: Yes, the location factor here ships the paper from a
Speaker 3: great astrophysics discovery into profound cosmological territory because when the
Speaker 3: scheme analyzed the line of sight, meaning they calculated the
Speaker 3: direct path from the origin galaxy of the fast radio
Speaker 3: burst through the invisible lens all the way to the
Speaker 3: Shei telescope on Earth, they realize something profoundly strange about
Speaker 3: the environment surrounding these black holes.
Speaker 2: Right, Usually black holes are anchored in galaxies or at
Speaker 2: least dense star clusters. They're born in stellar nurseries. They
Speaker 2: live in galactic disks. They are surrounded by matter.
Speaker 3: Yeah, they have neighbors.
Speaker 2: But in the case of these two specific microlensing signatures,
Speaker 2: there are no intervening structures. There are no galaxies, no
Speaker 2: galaxy clusters, no vast webs of visible matter along the
Speaker 2: line of sight in the immediate vicinity of the lens, which.
Speaker 3: Leads to a startling, almost eerie conclusion. These black holes
Speaker 3: appear to be completely isolated. They are drifting completely alone
Speaker 3: in the vast empty intergalactic voids of deep space.
Speaker 2: So if you're trying to figure out why this matters,
Speaker 2: think about the origin story. If an intermediate mass black
Speaker 2: hole isn't inside a galaxy, and there is no evidence
Speaker 2: it was ever part of a star cluster. How did
Speaker 2: it get there?
Speaker 3: It challenges the standard models fundamentally. If it's isolated and
Speaker 3: avoid it couldn't have been born from a dying star
Speaker 3: because stars don't form in intergalactic voids. They need dense
Speaker 3: clouds of gas to ignite.
Speaker 2: Right, they need a nursery.
Speaker 3: And it couldn't have formed from a runaway collision of
Speaker 3: stars in a dense cluster because there is no cluster.
Speaker 3: The environment necessary for that kind of stellar evolution simply
Speaker 3: is are there, And it's highly improbable that a two
Speaker 3: thousand solar mass black hole was somehow ejected from a
Speaker 3: galaxy without taking any stars with it or leaving a
Speaker 3: massive gravitational wake we could detect.
Speaker 2: Which brings us right back to the theoretical featherweights we mentioned
Speaker 2: at the very beginning in the show, but scaled up
Speaker 2: primordial black holes exactly.
Speaker 3: This is why the researchers explicitly suggest these candidates are
Speaker 3: strongly pointing toward a primordial origin.
Speaker 2: Because they formed before anything else.
Speaker 3: Right, Because primordial black holes formed just a fraction of
Speaker 3: a second after the Big Bang, long before the first
Speaker 3: atoms even combine, let alone, before the first stars are
Speaker 3: galaxies formed. Because they predate galaxies, they wouldn't necessarily be
Speaker 3: bound inside them. You just drift as the universe expanded.
Speaker 3: These primordial black holes would simply be carried along, scattered
Speaker 3: throughout the cosmos, drifting in the intergalactic voids.
Speaker 2: Okay, if we are seriously entertaining the idea that these
Speaker 2: are primordial black holes floating in deep space, we have
Speaker 2: to talk about the elephant in the room. We have
Speaker 2: to talk about the dark matter connection. Oh yeah, the
Speaker 2: big one.
Speaker 3: Because this is where this research scales up from Hey
Speaker 3: we found a missing black hole. Two, we might be
Speaker 3: potentially solving one of the biggest, most enduring mysteries in
Speaker 3: all of physics.
Speaker 2: It is the ultimate cosmological crossover episode. I mean, for decades,
Speaker 2: since the pioneering work of astronomers like VERA. Rubin and
Speaker 2: Fritz Wicky, scientists have known that the visible matter in
Speaker 2: the universe, the stars, the gas clouds, the planets, us
Speaker 2: it only accounts for a tiny fraction of the actual
Speaker 2: mass out there, fifteen percent, right roughly. Yeah, when we
Speaker 2: look at how galaxies rotate the stars and the outer
Speaker 2: edges are moving way too fast. Based on the amount
Speaker 2: of visible matter we can see, those galaxies should literally
Speaker 2: fling themselves apart. The gravity of the glowing stuff isn't
Speaker 2: strong in us to hold them together. But they don't
Speaker 2: fly apart. They hold together, which means there has to
Speaker 2: be an immense amount of invisible mass providing extra gravity.
Speaker 2: We call it dark matter, but let's be honest, that's
Speaker 2: just a placeholder name for the invisible stuff creating the
Speaker 2: extra gravity that we don't understand precisely.
Speaker 3: It's a label for our ignorance. And the particle physics
Speaker 3: community has spent decades looking for new exotic subatomic particles
Speaker 3: to explain it, things called whimps weakly interacting massive particles,
Speaker 3: But despite billions of dollars and incredibly sensitive underground detectors,
Speaker 3: we haven't found a single one, which has led many
Speaker 3: astrophysicists to revive an older theory. What if dark matter
Speaker 3: is an a microscopic new particle. What if it's macroscopic?
Speaker 2: What if the universe is simply teeming with an unseen
Speaker 2: population of primordial.
Speaker 3: Black holes exactly because they would exert massive gravitational influence.
Speaker 3: They emit absolutely zero light, and they don't interact with
Speaker 3: regular matter unless it falls right into them.
Speaker 2: They perfectly fit the job description of dark matter. They do.
Speaker 3: So, Juanzu's team took their two candidate black holes, looked
Speaker 3: at the volume of space sche Mi surveyed to find them,
Speaker 3: and calculated the statistical implications. They ask, if these two
Speaker 3: micro lensing events are indeed real primordial black holes, what
Speaker 3: does that imply for the dark matter population as a whole?
Speaker 2: And the math that came out with this fascinating They
Speaker 2: extrapolated from their detections and determined that if these are
Speaker 2: true primordial black holes, then black holes specifically in these
Speaker 2: intermediate mass ranges the five hundred to six hundred and
Speaker 2: fifteen hundred to twenty five hundred solar mass brackets, could
Speaker 2: account for approximately four percent of all the dark matter
Speaker 2: in the universe.
Speaker 3: Now, four percent might sound like a small sligh of
Speaker 3: the pie to someone outside the field, but in the
Speaker 3: context of dark matter, where we have spent decades with
Speaker 3: exactly zero percent of it definitively identified literally zero yes, zero,
Speaker 3: So finding an entire specific category of objects that can
Speaker 3: count for four percent is a revolutionary leap. It provides
Speaker 3: a massive tangible constraint on cosmological models.
Speaker 2: If you're wondering why finding four percent if something is
Speaker 2: a big deal, think about it this way. You have
Speaker 2: a massive jigsaw puzzle with missing pieces. For years, you
Speaker 2: didn't even know what color the missing pieces were. Now
Speaker 2: someone has just found a handful of pieces and proved
Speaker 2: they are blue. It doesn't finish the puzzle, but it
Speaker 2: completely changes how you look for the rest of them.
Speaker 3: It is a profound constraint. It begins to chip away
Speaker 3: at the absolute unknown. But what's equally impressive, and what
Speaker 3: makes this a truly rigorous piece of science, is how
Speaker 3: they handled the alternative scenario. The statistical analysis in the
Speaker 3: paper doesn't just rely on hoping their interpretation is right.
Speaker 2: Yes. What fascinating me about this paper is that this
Speaker 2: is a win win for science. The scientific method is
Speaker 2: working flawlessly here because even if these detections turn out
Speaker 2: to be false alarms, even if we later prove that
Speaker 2: these specific echoes weren't caused by black holes at all,
Speaker 2: the math still works backward to give us an answer.
Speaker 3: It really does.
Speaker 2: It's like playing a massive cosmic game of guess. Who
Speaker 2: Even when you ask does the suspect have glasses and
Speaker 2: the universe says no. That no is incredibly valuable because
Speaker 2: it helps you eliminate a huge swath of suspects on
Speaker 2: the board exactly.
Speaker 3: This is the failure scenario, and in Baesian statistics, a
Speaker 3: null result is just as mathematically valuable as a positive detection.
Speaker 3: A null result right, the authors calculated that if these
Speaker 3: candidates are not true gravitational lensing signals, if there are
Speaker 3: actually zero intermedia mass black holes acting as lenses in
Speaker 3: the entire chatching data set, we still learn something vital
Speaker 3: about the composition of the universe because.
Speaker 2: We looked so hard and found nothing.
Speaker 3: Right by not finding them in a survey this large
Speaker 3: and sensitive, scientists can establish with ninety five percent confidence
Speaker 3: that primordial black holes heavier than three hundred solar masses
Speaker 3: cannot make up more than thirteen percent of dark matter.
Speaker 2: So either we have found the missing middleweight black holes
Speaker 2: and simultaneously identified four percent of dark matter, or we
Speaker 2: have definitively proven that heavy primordial black holes are not
Speaker 2: the primary ingredient of dark matter, capping their entire contribution
Speaker 2: at a maximum of thirteen percent.
Speaker 3: Either way, the boundaries of the unknown shrink, the error
Speaker 3: bars get smaller. We are closing in on the truth.
Speaker 2: It is a structural wind for astrophysics. The constraints narrow,
Speaker 2: the theoretical models get refined, and the parameters for the
Speaker 2: next generation of radio telescopes become infinitely more precise. Absolutely, But,
Speaker 2: and there is always a butt in astrophysics. Before we
Speaker 2: officially declare the mystery of the missing little solve, before
Speaker 2: we rewrite the textbooks on dark matter and primordial cosmology,
Speaker 2: there is one massive caveat hanging over this entire study.
Speaker 2: The caveat, and this caveat is exactly the kind of complex,
Speaker 2: nagging variable that forces scientists to be incredibly cautious.
Speaker 3: Is the great scientific what if, and it brings us
Speaker 3: right back to our lack of fundamental understanding regarding the
Speaker 3: fast radio bursts themselves.
Speaker 2: We established earlier that we are using a mysterious flashlight
Speaker 2: to find a hidden object. We know the light is
Speaker 2: hitting our telescopes as a multipeak structure, an echo. We've
Speaker 2: shown how beautifully the math aligns if that echo is
Speaker 2: caused by an intermediate mass black hole bending the line.
Speaker 2: But the alternative explanation for those multiple peaks. Challenge is
Speaker 2: the very foundation of the microlensing theory.
Speaker 3: Right, we have to confront the intrinsic emission mechanisms of
Speaker 3: the fast radio bursts. Because we do not know what
Speaker 3: physical astrophysical process creates an FRB, we cannot say with
Speaker 3: absolute certainty how that process operates dynamically from millisecond to millisecond.
Speaker 2: Wait, let me make sure I'm following. You're telling me
Speaker 2: the multipeak structure, the echo that perfectly aligns with the
Speaker 2: general relativity math of a two thousand solar mass black
Speaker 2: hole might just be the flashlight flickering twice on its own,
Speaker 2: rather than a single continuous light being bent into two
Speaker 2: by gravity.
Speaker 3: That is exactly the degenerate caveat. It is entirely physically
Speaker 3: plausible that the source of the effort be itself.
Speaker 2: Stutters. It's stutter. Yeah.
Speaker 3: Let's say the burst is caused by a magnetar, a
Speaker 3: highly magnetized, rapidly rotating neutron star undergoing a massive starquake
Speaker 3: that snaps its magnetic field lines.
Speaker 2: A starquake that sounds intense.
Speaker 3: It is incredibly intense. If that cataclysmic event pulses rapidly
Speaker 3: emitting two distinct bursts separated by a fraction of a millisecond.
Speaker 3: Those two pulses would travel across the universe and arrive
Speaker 3: at our telescopes looking completely identically indistinguishable from a single
Speaker 3: burst that was split into an ego by gravitational lensing.
Speaker 2: Oh, that is brutal.
Speaker 3: It would perfectly mimic the geometric signature of a black hole.
Speaker 2: It's a cosmic counterfeit. The intrinsic stutter of the source
Speaker 2: perfectly imitates the gravitational lens. So how do we break
Speaker 2: that tie? If the time delay looks exactly the same
Speaker 2: on the graph, how do we prove we are seeing
Speaker 2: a true spatial echo caused by gravity and not just
Speaker 2: an intrinsic flicker from an unstable magnetar.
Speaker 3: That is the frontier we are on right now, and
Speaker 3: it requires us to look at properties of the light
Speaker 3: beyond just when it arrives. It requires an extraordinary level
Speaker 3: of rigorous skepticism, which the authors of the paper explicitly acknowledge.
Speaker 3: To definitively prove these signatures are intermediate mass black holes,
Speaker 3: we need to analyze the polarization of the radio waves.
Speaker 2: Polarization Okay, break down how that helps us tell a
Speaker 2: stutter from a lens.
Speaker 3: Think of polarization as the orientation of the light wave
Speaker 3: as it travels. Does it wiggle up and down or
Speaker 3: left and right?
Speaker 2: Okay? I can picture that like shaking a rope.
Speaker 3: Exactly like shaking a rope. When a magnetic field generates
Speaker 3: a radio burst, it gives that burst a very specific
Speaker 3: polarization angle. If a magnetar stutters and emits two bursts,
Speaker 3: the massive magnetic field of the star is likely shift
Speaker 3: rotating or violently reorganizing between those two.
Speaker 2: Pulses because it's having a starquake right.
Speaker 3: Therefore, the second pulse will likely have a slightly different
Speaker 3: polarization angle than the first pulse. The microscopic physics of
Speaker 3: the source change over time.
Speaker 2: I see where you're going with this, But what if
Speaker 2: it's a gravitational lens.
Speaker 3: If it's a gravitational lens, there is only one single
Speaker 3: burst of light. The source is identical. The gravity of
Speaker 3: the black hole splits that single burst into two paths.
Speaker 3: But gravity is achromatic aromatic. It affects all frequencies and
Speaker 3: polarizations exactly equally. It doesn't twist the orientation of the
Speaker 3: light differently on the left path versus the right path.
Speaker 3: So if we look at the two peaks of the
Speaker 3: echo and their polarization angles are identical down to the
Speaker 3: finest measurable degree, that strongly implies a single source was lensed. Wow,
Speaker 3: if the polarizations are different, it's almost certainly an intrinsic
Speaker 3: stutter from the source.
Speaker 2: That is an incredibly elegant solution. So why didn't they
Speaker 2: just check the polarization in this Chihaim data.
Speaker 3: Because capturing that level of granular polarization data for transient
Speaker 3: microsecond events is incredibly technically demanding.
Speaker 2: It's just too fast.
Speaker 3: Yeah, the Chino data provides the time delay beautifully, but
Speaker 3: we need more comprehensive, multi layered observational data from next
Speaker 3: generation arrays to routinely capture the exact frequency distribution and
Speaker 3: subtle polarization wave interference patterns across the peaks to distinguish
Speaker 3: a true gravitational echo from a source that just happens
Speaker 3: to be flashing twice.
Speaker 2: It's like we've been handed an ancient treasure map to
Speaker 2: the hidden monsters of the universe. We could see the
Speaker 2: X marking the spot the coordinates lineup perfectly, but we're
Speaker 2: still trying to learn the specific dialect of the legend
Speaker 2: in the corner. We aren't quite sure if we're reading
Speaker 2: the topography correctly.
Speaker 3: Yet that's a perfect summary of where the science currently stands.
Speaker 3: The time catalog has provided us with our most incredible,
Speaker 3: mathematically robust candidates to date. The math of strong field
Speaker 3: gravity holds up flawlessly. If these are in lenses, the
Speaker 3: puzzle pieces fit they do. The profound implications for primordial
Speaker 3: black holes floating in voids and their contribution to dark
Speaker 3: matter are revolutionary. But the final definitive proof, the thing
Speaker 3: that will lock this into the textbooks, requires us to
Speaker 3: crack the code of the fast radio bursts themselves.
Speaker 2: It is an incredible journey just to recap how far
Speaker 2: we've come. We started with a massive missing generation and
Speaker 2: the cosmic family tree. The intermediate mass black holes that
Speaker 2: the laws of physics demand must exist, but observation has
Speaker 2: entirely failed to confirm. To find them, we had to
Speaker 2: stop staring into the noisy, chaotic centers of dense star
Speaker 2: clusters and instead repurposed mysterious microsecond flashes of extreme radio
Speaker 2: waves from deep space as our cosmic flashlights exactly by
Speaker 2: analyzing how the extreme gravity of hidden mass bends that
Speaker 2: light to create split second echoes, scientists have essentially found
Speaker 2: a way to mathematically weigh completely invisible objects billions of
Speaker 2: light years away, so they are simultaneously closing in on
Speaker 2: the secrets of dark matter and the chaotic quite a
Speaker 2: moment's just fractions of a second after the Big Bang.
Speaker 3: It truly showcases the incredible ingenuity and resilience of modern astrophysics.
Speaker 3: When that direct, obvious approach fails, you don't give up.
Speaker 3: You use the warping fabric of space time itself as
Speaker 3: your instrument.
Speaker 2: It really does. And I want to leave you with
Speaker 2: one final lingering thought to ponder tonight. As you look
Speaker 2: up at the night sky. We are so entirely used
Speaker 2: to looking at the stars, the bright, spiraling galaxies, the visible,
Speaker 2: glowing structure of the universe. We assume that the light
Speaker 2: is where the action is.
Speaker 3: It's natural to think that.
Speaker 2: But if this research holds true, if these middleweight black
Speaker 2: holes are indeed primordial, isolated and making up significant chunks
Speaker 2: of the dark matter that silently binds the cosmos together,
Speaker 2: then the vast seemingly empty black voids of deep space
Speaker 2: between those glowing galaxies aren't empty at all, far from it,
Speaker 2: they are silently teeming with invisible ancient behemos. Middleweight Monster
Speaker 2: is born at the very dawn of time, completely undetectable
Speaker 2: to us, drifting alone in the absolute dark until they briefly,
Speaker 2: fleetingly cast their shadow in the light of a microsecond
Speaker 2: radio flash. We still don't even fully understand