Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomie 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 slumber.
Speaker 1: Under the night sky.
Speaker 2: I want you to step outside with me for a second,
Speaker 2: just in your mind. Okay, there, picture the night sky.
Speaker 2: It's you know, it's clear, the air is cold, it's
Speaker 2: incredibly dark, right, and you are looking up at the
Speaker 2: constellation of Ursa Major, which most of us know as
Speaker 2: the Great Bear.
Speaker 3: Yeah, classic, exactly.
Speaker 2: Now, if you know exactly where to look. Sitting deep
Speaker 2: within that patch of sky is Messia one oh one,
Speaker 2: the pinwheel galaxy.
Speaker 3: Oh that is a beautiful one.
Speaker 2: It really is. And when we observe it using our
Speaker 2: most powerful orbital tools like Hubbles advanced camera for surveys,
Speaker 2: we're doing something pretty remarkable.
Speaker 3: We're literally looking back in time.
Speaker 2: Yeah, we are pulling in photons that have been traveling
Speaker 2: across the vacuum of space for like twenty one million years.
Speaker 3: We're just staggering to think about it is.
Speaker 2: And we route that light through these highly specialized green
Speaker 2: and infra red filters right hitting these incredibly sensitive charge
Speaker 2: coupled device sensors, and what we capture is this breath taking,
Speaker 2: hyper detailed image across a three point three by three
Speaker 2: point three arc minute field of view.
Speaker 3: Right you see the whole disc.
Speaker 2: Yeah, It's a vast, swirling disc of hundreds of billions
Speaker 2: of stars, glowing neon gas, dense dust lanes, And it
Speaker 2: feels so complete.
Speaker 3: It feels like you're seeing the whole universe right.
Speaker 2: There, exactly. It feels like we are seeing everything there
Speaker 2: is to see in that majestic spiral. But then you
Speaker 2: have to pivot sharply and ask yourself a really unsettling question,
Speaker 2: which is, what if the most important part of that
Speaker 2: entire image just the stuff we absolutely cannot see?
Speaker 3: Oh Man point?
Speaker 2: What if the real story, like the fundamental architecture holding
Speaker 2: that entire spinning pinwheel together, is hidden in the dark,
Speaker 2: completely invisible, completely invisible. No matter what filters we use,
Speaker 2: and no matter how long we leave the camera shutter.
Speaker 3: Open, it forces a profound shift in perspective, doesn't it.
Speaker 3: It really does because we are so conditioned biologically by
Speaker 3: our evolutionary history and technologically by the instruments we build
Speaker 3: to just focus on the light.
Speaker 2: Right, we're visual creatures, exactly.
Speaker 3: We design these billion dollar orbital observatories specifically to capture
Speaker 3: the electromagnetic spectrum photons. But the visible universe, those swirling galaxies,
Speaker 3: the brilliant stars, the eliminated nebulas, that's just the frosting.
Speaker 2: The frosting on a very big invisible cake.
Speaker 3: Exactly. The vast majority of the universe's mass doesn't interact
Speaker 3: with electromagnetism at all. It just ignores it, totally ignores it.
Speaker 3: It doesn't emit light, it doesn't reflect it, and it
Speaker 3: doesn't absorb it. Wow, it is completely invisible to our
Speaker 3: primary way of experiencing reality.
Speaker 2: Okay, let's unpack this, because understanding that invisible architecture is
Speaker 2: the core mission of our conversation today.
Speaker 3: Let's do it.
Speaker 2: We know this invisible stuff, dark matter, we know it exists,
Speaker 2: we do, and we know it's incredibly abundant, outnumbering regular
Speaker 2: matter by roughly five to one. Right, and we know
Speaker 2: it's there because of its gravitational pull on the visible matter.
Speaker 2: We just talked about.
Speaker 3: Yeah, Vera. Ruben showed us this beautifully back in the
Speaker 3: nineteen seventies.
Speaker 2: Oh yeah, the galactic rotation curves exactly.
Speaker 3: You look at a galaxy spinning and the stars on
Speaker 3: the outer edges are moving way too fast.
Speaker 2: Like they should just fly off into space, right.
Speaker 3: They absolutely should, based on the visible mass, those stars
Speaker 3: should be flung out into deep space.
Speaker 2: That they don't, right.
Speaker 3: The fact that they stay locked in orbit means there's
Speaker 3: an enormous amount of invisible mass holding the galaxy together.
Speaker 2: It's kind of like seeing the branches of trees whipping
Speaker 2: back and forth. You can't see the wind, but the
Speaker 2: cane energy of the branches tells you the wind is there.
Speaker 3: That's a great analogy.
Speaker 2: But yet, despite decades of searching, despite building the most
Speaker 2: sensitive detectors humanity has ever conceived, we have never observed
Speaker 2: a dark matter particle directly.
Speaker 3: Never, not once.
Speaker 2: It has never given us a clear, undeniable, reproducible signal.
Speaker 3: No, it's been incredibly frustrating.
Speaker 2: So today we are exploring a radical new idea in
Speaker 2: particle astrophysics. What if the universe's failure to give us
Speaker 2: a clear, uniform signal isn't a dead end?
Speaker 3: Oh, I like where this is going?
Speaker 2: What if the fact that the signal keeps disappearing is
Speaker 2: actually the crucial clue we've been waiting for all along.
Speaker 3: That is the crux of the current crisis in the
Speaker 3: field right there. Yeah. Yeah. We have spent decades operating
Speaker 3: under a very specific, mathematically elegant set of assumptions about
Speaker 3: what dark matter should.
Speaker 2: Look like, how it should behave fundamentally.
Speaker 3: Exactly, and when the observational data repeatedly fails to match
Speaker 3: those mathematical assumptions, the initial reaction within the community is
Speaker 3: understandably intense frustration.
Speaker 2: I mean, I'd be pulling my hair out.
Speaker 3: Plenty of physicists are. But in physics, a null result
Speaker 3: an absence of a signal in a place where your
Speaker 3: best theories strongly predict there absolutely should be one that
Speaker 3: is incredibly valuable data.
Speaker 2: It's not a failure, it's a clue exactly.
Speaker 3: It forces you to rethink the fundamental rules of the
Speaker 3: standard models you've built your whole career.
Speaker 2: On, right, and to understand this new set of rules.
Speaker 2: We are going to explore a really fascinating mystery.
Speaker 3: That's playing out right now where do we start.
Speaker 2: It starts with a strange, highly energetic, totally unexplained glow
Speaker 2: right at the center of our very own Milky Way galaxy,
Speaker 2: the galactic center. Yes, then to figure out what that
Speaker 2: glow is, will travel out to the quietest, most pristine
Speaker 2: laboratories in the universe, these tiny, faint systems known as
Speaker 2: dwarf spheroidal galaxies.
Speaker 3: The clean rooms of the cosmos exactly.
Speaker 2: And finally we'll look at a groundbreaking theory from Fermilab
Speaker 2: which suggests that we've been thinking about the fundamental nature
Speaker 2: of dark matter all wrong. Okay, that maybe it's not
Speaker 2: just one single monolithic particle, but a complex system of two.
Speaker 3: That distinction, by the way between dark matter being a
Speaker 3: single uniform substance versus a dynamic system of multiple interacting
Speaker 3: parts that is not just a minor tweak to the equations.
Speaker 2: It's a big deal.
Speaker 3: It changes absolutely everything about how we map the kinematic
Speaker 3: history of the universe.
Speaker 2: So let's start right at the center of the action.
Speaker 2: The galactic center is glowing mystery. For decades, cosmologists have
Speaker 2: proposed that dark matter isn't just some abstract mathematical modifier
Speaker 2: to gravity it's made of actual physical.
Speaker 3: Particles, right, tangible stuff, even if we can't see.
Speaker 2: It exactly, and within the standard paradigm, there is this
Speaker 2: leading hypothesis that when these dark matter particles meet under
Speaker 2: the right conditions, they can annihilate each other ellilation, yes,
Speaker 2: And when they do that, they produce high energy radiation,
Speaker 2: specific gamma ray photons. And right now, as we speak,
Speaker 2: the Fermi Gamma ray space telescope is locked onto the
Speaker 2: center of our Milky Way.
Speaker 3: And what is it seeing.
Speaker 2: It is seeing a massive, unexplained excess of these gamma
Speaker 2: ray photons. It's coming from this roughly spherical region enveloping
Speaker 2: the dense inner bulge of our galaxy, right.
Speaker 3: The GV excess. To really grasp what the Fermi telescope
Speaker 3: is capturing, we need to dive into what annihilation actually
Speaker 3: means when we talk about particle astrophysics.
Speaker 2: Because it's not just things bumping together.
Speaker 3: No, no, this isn't just things bumping into each other and
Speaker 3: breaking apart into smaller pieces. It's a fundamental conversion of reality. WHOA, yeah, yeah,
Speaker 3: imagine two dark matter particles. Let's assume they're what we
Speaker 3: call weakly interacting massive particles. Or whimps okay, wandering through
Speaker 3: the incredibly dense gravitational environment of the galactic center. If
Speaker 3: the cross sections align and they collide, they destroy each
Speaker 3: other entirely, like completely gone completely. All of their mass
Speaker 3: is instantaneously converted into pure kinetic energy and standard model particles.
Speaker 2: Well it sounds violent.
Speaker 3: It is incredibly energetic. Depending on the mass of the
Speaker 3: dark matter particles. This process eventually cascades into the production
Speaker 3: of gamma rays. Okay, we are talking about photons with
Speaker 3: energies in the gig little electron volt or JEV range.
Speaker 2: And just for scale, how energetic is that?
Speaker 3: That is billions of times more energetic than the visible
Speaker 3: light hitting.
Speaker 2: Your eye right now, billions wow. And the Fermi telescope
Speaker 2: is specifically designed to catch these incredibly energetic photons, right
Speaker 2: it is. It's an amazing piece of engineering. I mean,
Speaker 2: it doesn't use mirrors or lenses like a regular telescope
Speaker 2: because gamma rays would just blast right through a mirror.
Speaker 3: They'd shatter it or just pass right through without interacting exactly.
Speaker 2: So instead it uses alternating layers of tungsten foils and
Speaker 2: silicon strip detectors. When a gamma ray hits the dense tungsten,
Speaker 2: the photon actually undergoes pair production. It spontaneously transforms into
Speaker 2: an a lee ttron and a positron from energy. Yeah. Those
Speaker 2: newly created particles then streak through the silicon detectors, leaving
Speaker 2: a tiny electrical wake that the computers can track backward
Speaker 2: to figure out exactly where the original gamma ray came
Speaker 2: from in the sky.
Speaker 3: It is an absolute triumph of particle physics applied to astronomy,
Speaker 3: it really is. And when we use Fermi to look
Speaker 3: at the center of the Milky Way, it maps this
Speaker 3: spherical excess of JEV gamma rays with astonishing precision.
Speaker 2: Right.
Speaker 3: The data reveals a morphology, a shape, and a spatial
Speaker 3: distribution that is a nearly flawless match for what we
Speaker 3: call a Navaro Frank White or NFW profile.
Speaker 2: And what's an NFW profile that.
Speaker 3: Is the exact mathematical density profile we expect a dark
Speaker 3: matter halo to have. Oh wow, Yeah, it's intensely concentrated
Speaker 3: at the galactic core where gravity pulls everything together. Yeah,
Speaker 3: and the density smoothly falls off inversely with the radius
Speaker 3: as you move further out.
Speaker 2: So we have this massive halo of dark matter sitting
Speaker 2: around the Milky Way in the very center. It's packed
Speaker 2: so densely that the particles are constantly interacting, annihilating and
Speaker 2: creating this glowing sphere of givy gamma rays.
Speaker 3: That's a theory.
Speaker 2: It paints this incredibly vivid picture in your mind. You
Speaker 2: have the flat, swirling, relatively thin disc of the Milky
Speaker 2: Way filled with visible stars and gas, and then enveloping
Speaker 2: the center, ballooning out above and below the galactic plane.
Speaker 2: Is this glowing orb of pure high energy radiation.
Speaker 3: It sounds like a smoking gun for dark matter, doesn't it?
Speaker 2: It really does.
Speaker 3: It certainly felt like one. When the gvxcess was first
Speaker 3: isolated from the background noise, right the energy spectrum peaked
Speaker 3: exactly where theories predicted it should if dark matter particles
Speaker 3: weighing around thirty to fifty gv were annihilating into bottom.
Speaker 2: Quarks, which then decayed into gammers exactly.
Speaker 3: It was almost too perfect. But but astrophysics is rarely
Speaker 3: that accommodating.
Speaker 2: Yeah, I have to push back on the smoking gun
Speaker 2: idea because the center of the Milky Way is decidedly
Speaker 2: not quiet controlled environment, not even a little bit. It
Speaker 2: is arguably the most chaotic, noisy, crowded neighborhood in our
Speaker 2: entire cosmic zip code.
Speaker 3: It's a mess in there.
Speaker 2: We've got Sagittarius, a star, a four million solar mass
Speaker 2: supermassive black hole sitting right there.
Speaker 3: Yep.
Speaker 2: We've got massive stars living fast and dying young in
Speaker 2: spectacular supernobe. We've got shock waves heating up unbelievable amounts
Speaker 2: of interstellar gas.
Speaker 3: So much background radiation exactly.
Speaker 2: So, could this gamma ray glow just be regular violent
Speaker 2: space phenomena? Like, specifically, what about ordinary astrophysical sources acting
Speaker 2: as impostors?
Speaker 3: Ah, the impostors, Yeah.
Speaker 2: Like a dense, unresolved cluster of millisecond pulsars.
Speaker 3: See. This raises an important question, and it is the
Speaker 3: exact center of gravity for the debate that has dominated
Speaker 3: this field for the last decade because of the mess. Yes,
Speaker 3: you are highlighting the fundamental problem with the galactic center.
Speaker 3: It is incredibly messy. Let's look closely at your pulsar hypothesis. Okay,
Speaker 3: A pulsars are rapidly spinning incredibly dense neutron star. It's
Speaker 3: the crushed remnant of a massive star that went supernova. Now,
Speaker 3: a millisecond pulsar is an older neutron star that has
Speaker 3: been spun up to insane speeds, rotating hundreds of times
Speaker 3: a second because it cannibalized matter from a companion star.
Speaker 2: Right, and they have these terrifyingly strong magnetic fields they
Speaker 2: whip around, acting like naturally occurring particle accelerator.
Speaker 3: Precisely, they accelerate electrons and positrons to near the speed
Speaker 3: of light along their magnetic poles.
Speaker 2: So they're just shooting beams of particles out into space.
Speaker 3: Yes, and these relativistic electrons then smash into ambient low
Speaker 3: energy photons like starlight or cosmic microwave background radiation. Okay,
Speaker 3: through a process called inverse Compton scattering, the electrons transfer
Speaker 3: a massive amount of their kinetic energy to the photons,
Speaker 3: kicking them all the way up into the GV gamma
Speaker 3: ray spectrum.
Speaker 2: Oh wow, so they just power up the regular light exactly.
Speaker 3: And here's the brutal part for dark matter. Huh.
Speaker 2: What's that?
Speaker 3: The combined spectrum of thousands of these unresolved millisecond pulsars
Speaker 3: peaking in the Gevy range looks almost mathematically identical to
Speaker 3: the expected signal of a forty gvy dark matter particle annihilating.
Speaker 2: No way.
Speaker 3: Yes, they're the ultimate astrophysical imposters.
Speaker 2: So we have a massive degeneracy problem, a huge one.
Speaker 2: We have a glowing sphere of gamma rays, and we
Speaker 2: have two completely different mechanisms that could be creating it exactly.
Speaker 2: It could be the groundbreaking discovery of dark matter annihilating,
Speaker 2: or it could just be a swarm of thousands of
Speaker 2: spinning dead stars clustered around the galactic core.
Speaker 3: And because the galactic center is so thick with dust
Speaker 3: and other radiation, we can't just zoom in with an
Speaker 3: optical telescope and count the pulsars to rule them out.
Speaker 2: We just can't see them clearly enough.
Speaker 3: We simply cannot separate the signals based on that data alone.
Speaker 3: The background modeling of the galactic center is fraught with
Speaker 3: systematic uncertainties. If you tweak your model of how interstellar
Speaker 3: gas is distributed by just a few percent, the dark
Speaker 3: matter signal can either vanish entirely or double in statistical significance.
Speaker 2: That's a huge margin of error.
Speaker 3: That is not a robust foundation for claiming a Nobel
Speaker 3: prizeworthy discovery. No, definitely not to prove that this glow
Speaker 3: is actually dark matter and not just a population of
Speaker 3: exotic neutron stars, you have to find the exact same
Speaker 3: dark matter signature somewhere.
Speaker 2: Else, some more quieter.
Speaker 3: Exactly. If the fundamental laws of physics are universal, which
Speaker 3: is the bedrock of our scientific understanding, then dark matter
Speaker 3: should behave identically everywhere in the cosmos.
Speaker 2: Okay, I see where this is going. We can't definitively
Speaker 2: prove what's happening in the noisy, chaotic center of the
Speaker 2: Milky Way because there's simply too much background noise, far
Speaker 2: too much. I like to think of it this way.
Speaker 2: It's like trying to isolate and record the sound of
Speaker 2: a single acoustic guitar while you are standing in the
Speaker 2: front row of a heavy metal concert. Oh I love that, right,
Speaker 2: there's pyrote technic's going off. There's a wall of amplifiers blasting,
Speaker 2: the crowd is screaming.
Speaker 3: They're chaos.
Speaker 2: Yeah. You might look at your audio waveform and think
Speaker 2: you see the acoustic guitar's frequency, but it's completely washed
Speaker 2: out by the distortion of the bass guitars and the symbols.
Speaker 3: You'd never be able to trust the recording exactly.
Speaker 2: You can't be sure, so you have to take the
Speaker 2: acoustic guitar out of the stadium. You have to find
Speaker 2: a quieter laboratory to see if you can hear it clearly.
Speaker 2: And for astrophysicists, that leads us directly to the clean
Speaker 2: rooms of the cosmos.
Speaker 3: That analogy hits the nail on the head. If the
Speaker 3: galactic center is our heavy metal concert, we desperately need
Speaker 3: to find the cosmic equivalent of an antichoic chamber.
Speaker 2: A completely sound proof room.
Speaker 3: Yes, and for high energy astrophysics, those sound proof chambers
Speaker 3: are a specific class of satellites orbiting our galaxy called
Speaker 3: dwarf spheroidal galaxies or dfs for short.
Speaker 2: Let's really dive into these dwarf speroidal galaxies because they
Speaker 2: are fascinating, deeply weird little objects there really are. We
Speaker 2: are talking about systems like Reticulum two or Takana to
Speaker 2: second or Segue one. They are very small and they
Speaker 2: are incredibly faint. You cannot see them with the naked.
Speaker 3: Eye, not a chance.
Speaker 2: In fact, many of them were only discovered recently through
Speaker 2: massive automated sky surveys because they are so dim. But
Speaker 2: what makes them special is that they are overwhelmingly dominated
Speaker 2: by dark matter.
Speaker 3: Their mass to light ratios are absolutely staggering. How so, well,
Speaker 3: in the Milky Way, the ratio of dark matter to
Speaker 3: regular matter is roughly five to one. Okay, In some
Speaker 3: of these ultra faint dwarf cerroidal galaxies the ratio can
Speaker 3: be a thousand.
Speaker 2: To one, one thousand to one.
Speaker 3: Yes, they're essentially massive, dense lumps of dark matter holding
Speaker 3: on to just a tiny microscopic sprinkling of ancient stars. Wow.
Speaker 3: And the critical factor for our search is what they lack.
Speaker 3: They have absolutely no interstellar gas and no dust.
Speaker 2: And without gas and dust, you can't have stellar nurseries.
Speaker 2: You can't form new star.
Speaker 3: Exactly the point point because they aren't forming new stars.
Speaker 3: They haven't had any recent supernovae.
Speaker 1: Ah.
Speaker 3: Therefore, they do not possess massive populations of pulsars.
Speaker 2: That's huge.
Speaker 3: It is the stars that are there are billions of
Speaker 3: years old, small and stable. Furthermore, we understand structurally why
Speaker 3: they are so empty. Why is that as these dwarf
Speaker 3: galaxies orbit the Milky Way, they pass through our galaxies
Speaker 3: diffuse outer halo. The friction of that passage creates a
Speaker 3: phenomenon called ram pressure stripping.
Speaker 2: Ram pressure stripping.
Speaker 3: Yeah, which effectively blows all the loose gas right out
Speaker 3: of the dwarf.
Speaker 2: Galaxy, just strips it clean.
Speaker 3: Right, So you are left with a pristine, ancient environment.
Speaker 3: No supermansive black holes, no active star formation, no pulsars.
Speaker 2: They are practically empty of ordinary high energy astrophysical background noise.
Speaker 3: The perfect clean room.
Speaker 2: So, returning to our analogy, trying to find dark matter
Speaker 2: in the Milky Way was the heavy metal concert. Pointing
Speaker 2: the Fermi telescope at a dwarf galaxy like reticulum texts
Speaker 2: is like trying to hear that acoustic guitar in a
Speaker 2: perfectly soundproof empty library.
Speaker 3: Yes, there is zero background noise.
Speaker 2: And because we know, based on their gravitational dynamics, that
Speaker 2: these dwarf galaxies are absolutely packed with dark matter, the
Speaker 2: math is incredibly.
Speaker 3: Straightforward, very straightforward.
Speaker 2: If dark matter is annihilating in the Milky Way and
Speaker 2: producing that massive JEV gamma ray glow, then it must
Speaker 2: be annihilating in the dwarf galaxies too, right.
Speaker 3: The community formalized this expectation by calculating something called the
Speaker 3: j factor for each of these dwarf galaxies.
Speaker 2: The J factor.
Speaker 3: Yes, it's essentially a mathematical integral of the dark matter
Speaker 3: density squared integrated along our line of sight.
Speaker 2: Okay, so a measure of how dense the dark matter is.
Speaker 3: Basically, it tells us exactly how bright the gamma ray
Speaker 3: signal should be if annihilation is occurring. Right for dwarf
Speaker 3: galaxies like Segue one are Reticulum two, the J factors
Speaker 3: are incredibly high. The target is painted clearly. We know
Speaker 3: where to look, We know exactly where to look, we
Speaker 3: know exactly what energy spectrum to look for, and we
Speaker 3: know there is no background radiation to confuse us.
Speaker 2: So what did we find?
Speaker 3: We point fermi at these quiet little galaxies, open the
Speaker 3: digital shutter, and wait to capture the undeniable glow of
Speaker 3: dark matter annihilation.
Speaker 2: But here is the massive, unsettling reveal. When we point
Speaker 2: our telescopes at those incredibly dense, dark matter rich dwarf
Speaker 2: galaxies year after year, we don't hear the acoustic guitar. No,
Speaker 2: we don't hear a whisper. We hear absolute, terrifying.
Speaker 3: Silence, total silence.
Speaker 2: There is a complete and total absence of a gamma
Speaker 2: ray signal.
Speaker 3: In an astrophysics that silence is deafening.
Speaker 2: I can imagine.
Speaker 3: We call it a null result, but it is a
Speaker 3: null result that carries the weight of a sledgehammer. It
Speaker 3: creates a massive kinematic paradox that threatens to break our
Speaker 3: foundational understanding of how the universe is.
Speaker 2: Constructed, because you simply cannot have it both ways.
Speaker 3: You really can't.
Speaker 2: If the fundamental dark matter particle is exactly the same
Speaker 2: everywhere in the universe, which is the bedrock assumption of
Speaker 2: the cold dark matter paradigm, right, and it is annihilating
Speaker 2: to create that massive glowing sphere in the Milky Way.
Speaker 2: Why is it completely utterly invisible in the dwarf galaxies?
Speaker 3: Exactly? It's a glaring contradiction.
Speaker 2: It's like it's like finding a species of bird that
Speaker 2: sings beautifully and loudly when it's in a noisy, chaotic city,
Speaker 2: but the moment you put that exact same bird in
Speaker 2: a quiet, peaceful forest, it loses its voice entirely.
Speaker 3: Oh, that's a perfect way to put it.
Speaker 2: It doesn't make any biological sense if it's the same
Speaker 2: bird operating under the same rules.
Speaker 3: No, it doesn't.
Speaker 2: And in physics, This profound silence from the Dwarf galaxies
Speaker 2: forces us to confront the terrifying possibility that our standard
Speaker 2: theories are fundamentally broken.
Speaker 3: To understand why this paradox froze the scientific community in
Speaker 3: its tracks, we really need to break down the mechanics
Speaker 3: of the two standard models of particle dark matter annihilation.
Speaker 2: Okay, let's do that.
Speaker 3: For decades, physicists have relied on these two primary kinematic
Speaker 3: frameworks to explain how whimps should behave the silence of
Speaker 3: the Dwarf's spheroidal galaxies essentially dismantles both of them simultaneously.
Speaker 2: All right, let's unpack these frameworks. Let's look at theory
Speaker 2: one constant probability. Okay, in particle physics, I believe this
Speaker 2: is referred to as an swave annihilation cross section.
Speaker 3: That's right.
Speaker 2: That's why this is the simplest, most elegant case. It
Speaker 2: assumes that the probability of two dark matter particles annihilating
Speaker 2: is a universal constant.
Speaker 3: It doesn't matter how fast the particles are moving relative
Speaker 3: to each other.
Speaker 2: Right, and it doesn't matter what the ambient temperature or
Speaker 2: gravitational environment is. If they get close enough their cross
Speaker 2: sections overlap, and they annihilate.
Speaker 3: The swave model is highly favored because it naturally explains
Speaker 3: the abundance of dark matter we see in the universe today.
Speaker 3: It's a concept known as the whimpe miracle.
Speaker 2: The wimp miracle. What is that? Exactly?
Speaker 3: Well, in the incredibly hot, dense environment of the early universe,
Speaker 3: dark matter particles were constantly annihilating and being created. It
Speaker 3: was a balance, okay. As the universe expanded in the
Speaker 3: particles spread out and the creation process stopped. The annihilation
Speaker 3: continued until the particles were too far apart to find
Speaker 3: each other, leaving behind the exact amount of dark matter
Speaker 3: we currently observe.
Speaker 2: So the math just worked out perfectly.
Speaker 3: For this mathematical miracle to work, the annihilation cross section
Speaker 3: needs to be a constant, specifically about three times ten
Speaker 3: to the negative twenty six cubic centimeters per second.
Speaker 2: Very specific. But if theory one is true, if the
Speaker 2: annihilation rate is truly a constant, we have a fatal
Speaker 2: flaw staring us in the face, a huge one. If
Speaker 2: the probability doesn't change, then we should absolutely see a
Speaker 2: bright gamma ray signal coming from the dwarf galaxies.
Speaker 3: We should the density of dark matter in the center
Speaker 3: of articulum two is more than high enough that these
Speaker 3: particles would be bumping into each other and annihilating regularly.
Speaker 3: But they're not right. The fact that Fermi has stared
Speaker 3: at these systems for over a decade and seen absolutely
Speaker 3: nothing means theory one, the elegant, mathematically favored swave model,
Speaker 3: cannot possibly be the explanation for the glow at the
Speaker 3: center of the Milky Way.
Speaker 2: It contradicts the observational data entirely.
Speaker 3: Exactly the problem. The Dwarf galaxy data places stripped upper
Speaker 3: limits on the cross section, and those limits completely rule
Speaker 3: out the constant probability model for a thirty to fifty
Speaker 3: GV particle.
Speaker 2: So theory one is dead pretty much.
Speaker 3: Oh so the community pivot is predictable if the constant
Speaker 3: model is broken. We look at the alternative theory two,
Speaker 3: the velocity dependent probability model.
Speaker 2: Okay, theory two.
Speaker 3: In the nomenclature of particle physics, this is a p
Speaker 3: wave annihilation cross section key wave. This theory posits that
Speaker 3: the chance of two particles annihilating is not constant. It
Speaker 3: depends heavily mathematically on how fast the particles are moving
Speaker 3: relative to one another.
Speaker 2: Let's translate that velocity dependence. In some theoretical models, particles
Speaker 2: need to be moving very fast to overcome a kinetic barrier,
Speaker 2: or conversely very slowly to interact effectively. In the standard
Speaker 2: cold dark matter paradigm, as galaxies form and evolve, the
Speaker 2: dark matter particles settle into these massive halos, and their
Speaker 2: velocities are dictated by the gravitational potential of the galaxy.
Speaker 3: This concept is known as velocity dispersion. Okay, in a
Speaker 3: massive system like the Milky Way, the gravitational well is
Speaker 3: very deep. The dark matter particles are zipping around at
Speaker 3: roughly two hundred kilometers per second. That's fast it is.
Speaker 3: But in a tiny dwarf galaxy, the gravitational well is
Speaker 3: incredibly shallow. The particles there are moving much much slower,
Speaker 3: perhaps only ten kilometers.
Speaker 2: Per second, so a big difference in speed.
Speaker 3: Huge. Now, if the annihilation probability is p wave, it
Speaker 3: is proportional to the square of the velocity. Because the
Speaker 3: velocity and dwarf galaxies is a factor of twenty smaller
Speaker 3: than in the Milky Way, the annihilation rate drops by
Speaker 3: a factor of four hundred Wow.
Speaker 2: Okay, so if theory two is correct an annihilation probability
Speaker 2: drops off a cliff when the particles are moving slowly,
Speaker 2: then that perfectly explains why the dwarf galaxies are silent exactly,
Speaker 2: just moving too slowly to trigger the annihilation.
Speaker 3: That's the idea.
Speaker 2: But wait, if the annihilation rate is tied to velocity
Speaker 2: and it drops drastically, shouldn't that also affect the Milky Way?
Speaker 3: That is the logical trap right there. If you calculate
Speaker 3: the P wave annihilation rate using the two hundred kilometers
Speaker 3: per second velocity of the Milky Way's dark matter halo,
Speaker 3: the resulting gamma ray signal is still far too weak
Speaker 3: to account for the massive glowing GV excess we actually
Speaker 3: observe with FERMI.
Speaker 2: It's just not fast enough.
Speaker 3: The velocity simply isn't high enough to overcome the drop
Speaker 3: in probability.
Speaker 2: Which means, if theory two is true, the massive glowing
Speaker 2: sphere of gamma rays we see at the center of
Speaker 2: our galaxy cannot possibly be dark matter annihilation.
Speaker 3: Nope, the physics simply won't allow it to be bright enough.
Speaker 2: It has to be. The astra physical impostures it has
Speaker 2: to be pulsar.
Speaker 3: You're completely backed into a corner here.
Speaker 2: It feels like a total conceptual dead end. I mean,
Speaker 2: if the annihilation rate is constant theory one, we should
Speaker 2: see it clearly in the dwarfs, but we don't. If
Speaker 2: the annihilation rate depends on velocity theory too, we shouldn't
Speaker 2: see a bright signal in the Milky Way, but we do.
Speaker 2: The paradox is absolute.
Speaker 3: It's a wall.
Speaker 2: So does this mean the scientific community just gives up?
Speaker 2: Do we conclude that the gamma ray excess at the
Speaker 2: center of our galaxy is definitely just a swarm of
Speaker 2: millisecond pulsars and we've literally been chasing ghosts this entire time.
Speaker 3: It is a profoundly frustrating, almost existential moment for the field.
Speaker 3: I mean, you spend twenty years building supercomputers, launching orbital observatories,
Speaker 3: analyzing petabytes of data, refining your theoretical models, only to
Speaker 3: find that the universe stubbornly refuses to fit neatly into
Speaker 3: your equations.
Speaker 2: It's got to hurt.
Speaker 3: It forces a moment of reckoning. Many physicists were ready
Speaker 3: to concede the galactic center to the pulsar hypothesis. I
Speaker 3: don't blame them, but as is so often the case
Speaker 3: in the history of science, just when a standard theory
Speaker 3: seems dead and buried under the weight of paradoxical data,
Speaker 3: someone looks at the fundamental assumptions of the problem from
Speaker 3: a completely different, slightly subversive angle.
Speaker 2: And that is exactly what happened. Just when the dark
Speaker 2: matter hypothesis for the Milky Way Center felt like it
Speaker 2: was on life support, a theoretical physicist named Gordon Krunjak
Speaker 2: from Fermilab in his collaborators introduced a brilliant rule breaking alternative.
Speaker 3: Yes they did.
Speaker 2: They published a new study in the Journal of Cosmology
Speaker 2: and Astraparticle Physics, and they proposed a kinematic model they
Speaker 2: playfully called d s fobic dark matter.
Speaker 3: Which dands for dwarf spheroidal phobic.
Speaker 2: Dark matter that is somehow fundamentally averse to or inactive
Speaker 2: in dwarf galaxies.
Speaker 3: The terminology is definitely Italian cheek, but the physics behind
Speaker 3: the ds fobic model is revolutionary. How So, Krenjac's team
Speaker 3: looked at the paradox the screaming signal in the Milky
Speaker 3: Way versus the deafening silence of the dwarfs and asked
Speaker 3: a very simple, yet radically destructive question, which was, what
Speaker 3: if the foundational assumption we've been using since the nineteen
Speaker 3: seventies is completely wrong?
Speaker 2: Oh wow?
Speaker 3: What if we been blinded by our desire for mathematical simplicity.
Speaker 3: What if dark matter is in a uniform type of particle.
Speaker 2: Here's where it gets really interesting. They propose a framework
Speaker 2: called inelastic dark matter. Yes, they suggest that the dark
Speaker 2: sector consists of two distinct, slightly different particles. Let's call
Speaker 2: them State A and State B. Okay, and the critical
Speaker 2: rule changes this. For an annihilation event to happen and
Speaker 2: produce those gamma rays, these two distinct particles must find
Speaker 2: each other and interact.
Speaker 3: It's no longer just particle A bouncing into another identical
Speaker 3: particle A.
Speaker 2: The entire process requires particle A to physically encounter particle B.
Speaker 3: This introduces a profound concept into the dark matter paradigm,
Speaker 3: environmental dependence.
Speaker 2: Environmental dependence.
Speaker 3: Suddenly, the probability of seeing a gamma ray glow isn't
Speaker 3: just a universal constant, and it isn't just dependent on
Speaker 3: the raw speed of the particle.
Speaker 2: It's conditional.
Speaker 3: It becomes entirely inextricably dependent on the local density and
Speaker 3: the specific race of these two distinct particle states within
Speaker 3: any given cosmic environment.
Speaker 2: Let's try an analogy here to make this kinematic mechanism tangible.
Speaker 2: I want to avoid anything too simplistic, because we are
Speaker 2: talking about high level physics. Let's imagine this two state
Speaker 2: dark matter like a highly specific binary star system.
Speaker 3: I like the sound of that.
Speaker 2: In order to create a massive stellar flare, which is
Speaker 2: our equivalent of the gamma ray burst, you need a
Speaker 2: massive red giant star and a tiny dense white dwarf
Speaker 2: star to fall into a very specific tight orbital resonance
Speaker 2: where the white dwarf siphons gas off the red giant.
Speaker 3: Right, a cataclysmic variable exactly.
Speaker 2: Now, if you have a galaxy filled with billions of
Speaker 2: these pairs mixed together, both the red giants and the
Speaker 2: white dwarfs and relatively equal numbers, you get these flares
Speaker 2: popping off constantly. The whole galaxy glows.
Speaker 3: That's in the milky way, right.
Speaker 2: You have a well mixed, incredibly dense population of both
Speaker 2: State A and State B particles. They easily find each other,
Speaker 2: they interact, and they produce the massive Jevy excess at
Speaker 2: the center of our galaxy.
Speaker 3: That is an excellent way to conceptualize the kinematic requirement.
Speaker 3: Both components are present and the density is high enough
Speaker 3: that interactions are frequent.
Speaker 2: But what about the dwarfs.
Speaker 3: That's where the brilliance of the inelastic model becomes apparent.
Speaker 3: How does a two state system naturally explain absolute silence? Right?
Speaker 2: So, what if, due to the chaotic history of how
Speaker 2: galaxies actually form, a dwarf galaxy ends up with a
Speaker 2: completely skewed population on what if, going back to our
Speaker 2: binary star analogy, a dwarf galaxy is composed almost entirely
Speaker 2: of isolated red giant stars and practically zero white dwarfs.
Speaker 2: It might have a massive amount of total stellar mass
Speaker 2: a huge gravitational footprint, but without the specific partner needed
Speaker 2: to trigger the interaction, nothing happens.
Speaker 3: It just sits there.
Speaker 2: It's dark, it's inert, and it's completely silent. If articulum
Speaker 2: two is filled with ninety nine point nine percent State
Speaker 2: A dark matter particles and essentially zero O state B particles,
Speaker 2: then annihilation is physically impossible, regardless of how dense the
Speaker 2: State A particles are packed.
Speaker 3: What's fascinating here is how elegantly and brudally this solves
Speaker 3: the entire paradox.
Speaker 2: It really does.
Speaker 3: It is a conceptual masterstroke. By introducing this second component,
Speaker 3: the state B particle, you successfully decouple the behavior of
Speaker 3: dark matter in the deep potential well of the Milky
Speaker 3: Way from its behavior in the shallow wells of the
Speaker 3: dwarf galaxies.
Speaker 2: You get to have your cake and eat it too exactly.
Speaker 3: You get to keep your dark matter explanation for the
Speaker 3: glowing center of our galaxy because the two particles are
Speaker 3: well mixed there and simultaneously, without violating any rules of physics,
Speaker 3: you perfectly explain the dark silence of the dwarf galaxies
Speaker 3: because the ratio there is overwhelmingly unbalanced.
Speaker 2: But it begs the question, how does a galaxy get
Speaker 2: unbalanced like that?
Speaker 3: That's the big question.
Speaker 2: Why would the Milky Way have a nice, even fifty
Speaker 2: to fifty mix of state A and State B while
Speaker 2: a dwarf galaxy ends up with a ninety nine to
Speaker 2: one ratio. Is it just endem cosmic luck?
Speaker 3: It's not luck. It's a consequence of the complex kinematics
Speaker 3: of the early universe and galactic formation. Quenji's model explores
Speaker 3: a few mechanisms for this, like what. One of the
Speaker 3: most compelling involves a slight mass difference between the two states.
Speaker 3: Imagine State B is just a tiny fraction of a
Speaker 3: percent heavier than State A.
Speaker 2: Okay, slightly heavier.
Speaker 3: In the incredibly dense hot early universe, they were in
Speaker 3: thermal equilibrium. But as the universe expanded, the slightly heavier
Speaker 3: State B particles could theoretically decay into the lighter State
Speaker 3: A particles, or they could interact with standard model particles differently.
Speaker 2: Making them rarer.
Speaker 3: Right. Alternatively, in the shallow gravitational potential of a tiny
Speaker 3: dwarf galaxy, if a scattering event gives a State B
Speaker 3: particle a tiny kick of kinetic energy, it might achieve
Speaker 3: escape velocity and just leave the dwarf galaxy entirely over
Speaker 3: billions of years.
Speaker 2: Oh, it just flies away.
Speaker 3: Exactly In the Milky Way, the gravity is so immense
Speaker 3: that even if a particle gets kicked, it can't escape.
Speaker 3: It stays trapped in the halo.
Speaker 2: So over cosmic time, the Milky Way retains both states,
Speaker 2: while the shallow dwarf galaxies slowly leak or decay their
Speaker 2: heavier state, leaving them completely depleted.
Speaker 3: You've got it perfectly.
Speaker 2: It's almost like giving the universe permission to have local
Speaker 2: historical variation.
Speaker 3: Which is very hard for some physicists to.
Speaker 2: Accept, right because we're so used to thinking of fundamental
Speaker 2: physics as being rigidly identical everywhere. An electron on Earth
Speaker 2: is exactly the same as an electron in the Andromeda
Speaker 2: galaxy a million light years away, exactly.
Speaker 3: The same charge, exact same mass.
Speaker 2: But this theory says, sure, the fundamental particles are the
Speaker 2: same everywhere, but the macrostopic recipe of the dark sector
Speaker 2: can change drastically depending on the specific gravitational and evolutionary
Speaker 2: history of where you are looking.
Speaker 3: The universe is suddenly allowed to be messy, varied, and
Speaker 3: historically contingent.
Speaker 2: And if we step back and look at reality objectively,
Speaker 2: we shouldn't be surprised by that messiness at all. Think
Speaker 2: about the ordinary matter we interact with every day, the
Speaker 2: baryonic matter, it's incredibly messy. The visible universe isn't just
Speaker 2: made of one type of monolithic particle. It's almost absurdly complex.
Speaker 2: We have protons, neutrons, electrons, we have neutrinos oscillating between
Speaker 2: three different flavors.
Speaker 3: We have a whole zoo of quarks and gluons.
Speaker 2: Yep. Yeah, these particles interact in highly specific, incredibly conditional
Speaker 2: ways based entirely on their local environment. The ratio of
Speaker 2: hydrogen to helium varies drastically in different generations of stars. Absolutely,
Speaker 2: the distribution of heavy metals, carbon, and oxygen is entirely
Speaker 2: different in a terrestrial planet like Earth compared to a
Speaker 2: gas giant like Jupiter.
Speaker 3: So why on Earth do we expect the dark sector,
Speaker 3: which makes up roughly eighty five percent of all the
Speaker 3: mass in the universe, to be just one boring, monolithic,
Speaker 3: uniform particle doing the exact same simple thing everywhere from
Speaker 3: the beginning of time until the heat depth the universe.
Speaker 2: Right, It makes no sense when you put it like that.
Speaker 3: It is an inherent cognitive bias in physics, a bias. Yeah.
Speaker 3: We have a strong bias toward mathematical simplicity. When building
Speaker 3: a new model, you always start with the simplest possible assumption,
Speaker 3: a single particle a constant cross section, because it's the
Speaker 3: easiest to calculate and test.
Speaker 2: You don't want to complicate the math unless.
Speaker 3: You have to. Exactly, you don't add complexity until the
Speaker 3: data forces you to. But the universe is under absolutely
Speaker 3: no obligation to be mathematically simple or conceptually convenient for
Speaker 3: our benefit.
Speaker 2: No, it's not.
Speaker 3: This two state inelastic dark matter theory forces us to
Speaker 3: treat the dark universe with the same respect for structural
Speaker 3: complexity that we give to the visible universe.
Speaker 2: Okay, so we have this brilliant new kinematic theory. It
Speaker 2: solves the paradox, It respects the complexity of the universe.
Speaker 2: It makes logical and physical sense.
Speaker 3: It does.
Speaker 2: But how do we actually prove this complex new scenario
Speaker 2: because right now, sitting here talking about it, it sounds
Speaker 2: suspiciously like a really elegant, highly tuned mathematical band aid
Speaker 2: invented just to save the dark matter hypothesis from the
Speaker 2: pulsar imposters.
Speaker 3: That is the crucial next step, and it separates theoretical
Speaker 3: philosophy from hard physics.
Speaker 2: How do we move this from a neat idea on
Speaker 2: a whiteboard at Fermi Lab to verifiable empirical science.
Speaker 3: Well, a theory, no matter how elegant, is only as
Speaker 3: good as its testable, falsifiable predictions. And proving this will
Speaker 3: require the next generation of observatories to gather much more precise,
Speaker 3: incredibly long term data on these dwarf galaxies better than Fermi.
Speaker 3: The Fermi data we have currently is exceptional, but it
Speaker 3: is still fundamentally limited by the sheer faintness of these
Speaker 3: dwarf systems and the agonizing difficulty of separating true ultra
Speaker 3: faint signals from cosmic ray background noise over ten year timeframes.
Speaker 2: Right, because we're talking about staring at essentially empty, completely
Speaker 2: dark patches of sky for years on end, hoping to
Speaker 2: catch literally a handful of extrajevy photons that stand out
Speaker 2: above the statistical.
Speaker 3: Noise, like finding an in a haystack of needles.
Speaker 2: So let's talk about the future of this observational hunt.
Speaker 2: What happens when we get that better data from say,
Speaker 2: the upcoming Cherenkov telescope array, which would be vastly more
Speaker 2: sensitive than Fermi. What is the bifurcated path of discovery here?
Speaker 3: The future of this hunt really splits down two very
Speaker 3: distinct paths based on what those next generation telescopes see.
Speaker 3: Path number one after years of deeper, much more sensitive
Speaker 3: observation with the Charinkov telescope array, we eventually detect a
Speaker 3: very faint, incredibly subtle, but statistically significant gamma ray signal
Speaker 3: emerging from a dwarf galaxy like reticulum. Too.
Speaker 2: If that happens, if we finally hear a tiny whisper
Speaker 2: in the silent library, what does it mean? Does it
Speaker 2: kill kranjayx to state theory?
Speaker 3: Not necessarily. In fact, it could refine it beautifully. Ow
Speaker 3: if we find a highly suppressed faint signal, it implies
Speaker 3: that both of the dark matter components dd A and
Speaker 3: state B are still present in the dwarf galaxies, but
Speaker 3: just in a wildly different distribute or a highly skewed
Speaker 3: ratio compared to the dense core of the Milky Way.
Speaker 2: So, going back to our binary star analogy, it would
Speaker 2: mean our dwarf galaxy isn't one hundred percent red giants,
Speaker 2: it has a tiny microscopic scattering of white dwarf still
Speaker 2: hanging around exactly.
Speaker 3: It would firmly support the environmental dependence model, and it
Speaker 3: would give theorists the exact data they need to calculate
Speaker 3: the precise mass splitting and decay rates of the two states.
Speaker 2: Okay, that makes sense. But what about path number two?
Speaker 3: Right?
Speaker 2: What if we get the most precise data imaginable, we
Speaker 2: deploy the Charinkoff telescope array, we stare at these pristine
Speaker 2: dwarf galaxies for another entire decade, and we confirm the absolute, undeniable,
Speaker 2: mathematically perfect absence of any signal whatsoever, just.
Speaker 3: A profound, unbroken cosmic void. Exactly what then, if we
Speaker 3: confirm absolute undeniable silence at higher sensitivities, it strongly suggests
Speaker 3: a heavily unbalanced, almost totally exclusive ratio.
Speaker 2: So one particle is just gone, right.
Speaker 3: It would be incredibly compelling evidence supporting the idea that
Speaker 3: one component of the dark matter is almost entirely missing,
Speaker 3: either decayed away completely or kinematically ejected from those specific
Speaker 3: shallow gravitational environments.
Speaker 2: So it still fits the theory.
Speaker 3: It would strongly validate the core mechanism of Karen Jake's
Speaker 3: d it's ahobic model.
Speaker 2: But I have to play devil's advocate here, representing the
Speaker 2: skeptics in the astrophysics community.
Speaker 3: Bring it on.
Speaker 2: Are we just inventing increasingly complicated math to save our
Speaker 2: favorite theories?
Speaker 3: I mean, it's a fair question.
Speaker 2: Let's look at the history of this. The original idea
Speaker 2: was beautifully simple. One dark matter particle annihilates with itself,
Speaker 2: we see a glow. The dwarf galaxies didn't show a glow.
Speaker 3: True.
Speaker 2: So instead of practicing good science and saying, okay, our
Speaker 2: simple theory is wrong, the glow in the Milky Way
Speaker 2: is just the pulsars, we invented a brand new invisible particle,
Speaker 2: gave it a highly specific mass splitting, and created a
Speaker 2: complex decay history just to make the math work out.
Speaker 3: It sounds like a stretch when you phrase it that way.
Speaker 2: Are we over complicating the universe just because we really
Speaker 2: don't want to admit we might be wrong about what's
Speaker 2: glowing at the galactic center?
Speaker 3: If we connect this to the bigger picture of the
Speaker 3: philosophy of science, it's a very valid, necessary criticism. Yeah,
Speaker 3: it's the classic Okham's razor argument, the principle that the
Speaker 3: simplest explanation is usually the correct one, and adding a second,
Speaker 3: entirely invisible particle state to your model is a huge
Speaker 3: violation of simplicity. Massive However, as I mentioned earlier, when
Speaker 3: we discuss the standard model of particle physics, the visible
Speaker 3: universe is overwhelmingly complex. It's messy, very the standard model
Speaker 3: has seventeen fundamental particles. It would be almost historically arrogant
Speaker 3: of us and scientifically naive to assume that the dark sector,
Speaker 3: which holds five times more mass and dictates the entire
Speaker 3: large scale structure of the cosmos, is fundamentally simpler than
Speaker 3: the tiny fraction of baryonic matter we have to be
Speaker 3: made of.
Speaker 2: That is a really powerful point. We are sitting here,
Speaker 2: complex biological organisms made of interacting carbon molecules, breathing a
Speaker 2: complex atmospheric mixture of nitrogen and oxygen, on a geologically
Speaker 2: complex planet, demanding that the remaining eighty five percent of
Speaker 2: the universe just be one simple, easy to calculate thing.
Speaker 3: Exactly. It's anthropocentric hubris.
Speaker 2: Yeah, we think we're the complex ones that everything else
Speaker 2: must be simple.
Speaker 3: And I must add a crucial note of scientific caution here,
Speaker 3: because physics relies on rigor, not just elegant ideas. Of course,
Speaker 3: the two state inelastic dark matter model is a brilliant interpretation,
Speaker 3: but it is not the only one currently on the
Speaker 3: theoretical table. Oh really, Yeah, the absence of a signal
Speaker 3: in dwarf galaxies could still be related to other astrophysical
Speaker 3: factors we haven't fully mapped out yet. Perhaps the dark
Speaker 3: matter halos around dwarf galaxies are shaped differently than the
Speaker 3: NFW profiles we assume like.
Speaker 2: Maybe they're flatter.
Speaker 3: Perhaps they are flatter, which would alter the core density
Speaker 3: and therefore lower the collision rates beneath our detection thresholds.
Speaker 3: We have to ruthlessly compare this two state model with
Speaker 3: a much wider range of observations, looking at galactic rotation curves,
Speaker 3: cosmic microwave background data, and direct detection experiments deep underground
Speaker 3: before we declare victory.
Speaker 2: So we aren't popping champagne yet.
Speaker 3: We certainly aren't popping champagne yet. The mystery is very
Speaker 3: much alive.
Speaker 2: No champagn yet, But it is an incredible, profound shift
Speaker 2: in how we think about the architecture of the cosmos.
Speaker 3: It absolutely is.
Speaker 2: When you really step back and look at the intellectual
Speaker 2: journey we've just taken over the course of this conversation,
Speaker 2: starting from the glowing, incredibly chaotic core of our home
Speaker 2: galaxy with its supermassive black hole, its pulsars, and its
Speaker 2: swirling high energy radiation, and then traveling out to the quiet, dark,
Speaker 2: pristine frontiers of the dwarf's ferroidal galaxies sitting out there
Speaker 2: in the intergalactic void. It fundamentally shifts your perspective on reality.
Speaker 3: It does it serves as a constant, humbling reminder that
Speaker 3: we are sitting inside a vast, invisible ecosystem.
Speaker 2: Invisible ecosystem, I like.
Speaker 3: That the universe isn't just unamaan dgably vast in terms
Speaker 3: of physical distance, It is profoundly layered in terms of
Speaker 3: physical substance. We only have the sensory tools to see
Speaker 3: the very top, thinnest layer of reality, and.
Speaker 2: That brings us back perfectly to that image we started
Speaker 2: with Messia one oh one, the pinwheel galaxy glowing against
Speaker 2: the dark void.
Speaker 3: Such a great image.
Speaker 2: We look at that beautiful Hubble image and we inherently
Speaker 2: think we see the whole picture. But this conversation leaves
Speaker 2: me with a truly mind expanding idea to mull over,
Speaker 2: what's that If dark matter isn't just a single inert,
Speaker 2: boring particle, but multiple different particles interacting with each other
Speaker 2: based on complex environmental ratios and kinetic energies, could there
Speaker 2: be an entire dark chemistry.
Speaker 3: Oh wow, that is the ultimate frontier pushing question in
Speaker 3: astroparticle physics.
Speaker 2: I mean, if you have multiple particles with distinct masses
Speaker 2: and interaction states, you immediately have the theoretical potential for
Speaker 2: complex structural interactions. You do think about the implications of that.
Speaker 2: Could there be unseen dark structures floating right through our
Speaker 2: galaxy as we speak? Dark matter isn't just a static,
Speaker 2: featureless fog holding the stars together? What if it has
Speaker 2: its own intricate internal.
Speaker 3: Dynamics Dark chemistry?
Speaker 2: Yeah? Could there be dark atoms, dark molecules? Could there
Speaker 2: be dark radiation that we simply have no physics to detect,
Speaker 2: operating under their own exotic rules, completely invisible to our
Speaker 2: eyes and our most advanced telescopes while we go about
Speaker 2: our daily lives oblivious to them.
Speaker 3: Entirely possible.
Speaker 2: The idea that we are swimming in an unseen ocean
Speaker 2: of complex interactive matter is both deeply humbling and intensely thrilling.
Speaker 2: It means the universe is infinitely more mysterious and infinitely
Speaker 2: more structure than we ever imagine.
Speaker 3: A very exciting time to be looking at the data,
Speaker 3: that's for sure.
Speaker 2: Thank you for exploring this invisible reality, for questioning the
Speaker 2: standard models, and for taking this journey into the unseen
Speaker 2: universe with us today. Keep looking up and remember the
Speaker 2: most important structures in the cosmos are often the ones
Speaker 2: you cannot see.