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
Speaker 1: slumber under the night sky.
Speaker 2: I want you to imagine the absolute bottom of the
Speaker 2: Mediterranean Sea. I mean we are talking over three thousand
Speaker 2: meters down right in this place called the Capo Pasero site,
Speaker 2: which is just off the coast of.
Speaker 3: Sicily, right, and it is a completely alien environment down there.
Speaker 2: Oh absolutely. The pressure is just immense, like hundreds of
Speaker 2: times greater than what we feel at the surface. And
Speaker 2: it is pitch black. I mean, the only light you
Speaker 2: might ever see comes from the faint biluminescence of these
Speaker 2: weird deep sea creatures.
Speaker 3: It's freezing, it's quiet, and it is almost entirely undisturbed.
Speaker 2: Yeah, yeah, exactly. And sitting right there on the floor
Speaker 2: of this abyss is a massive silent machine. It's basically
Speaker 2: a grid of glass spheres suspended on cables, forming this
Speaker 2: structure that is the size of a cubic kilometer, and.
Speaker 3: It doesn't move, It doesn't make a single sound.
Speaker 2: No, it just waits.
Speaker 3: It waits in that absolute darkness for a ghost, literally,
Speaker 3: a particle that is so elusive, so you know, unbothered
Speaker 3: by physical reality, that it can travel across billions of
Speaker 3: light years of empty.
Speaker 2: Space just flying through the void right it.
Speaker 3: Enters our solar system, passes straight through the Earth's crust,
Speaker 3: blasts right through the boiling liquid iron of the outer core,
Speaker 3: and just emerges out the other side without even slowing down.
Speaker 2: It doesn't bounce off anything. It leaves no wake. I mean,
Speaker 2: to this particle, the solid matter of our entire planet
Speaker 2: might as well just be an empty vacuum.
Speaker 3: Which is what makes it so incredibly fascinating.
Speaker 2: It really is. And the reason we are venturing into
Speaker 2: that pitch black ocean abyss today is because back in
Speaker 2: February of twenty twenty three, that silent machine didn't just
Speaker 2: catch one of them, these normal ghosts. It caught an
Speaker 2: absolute titan.
Speaker 3: It really did. It recorded a singular, microscopic particle carrying
Speaker 3: an amount of energy so staggering, so terrifyingly vast, that
Speaker 3: it actually threatens to rewrite our understanding of the universe's
Speaker 3: ultimate limits.
Speaker 2: Yeah, the event was quietly cataloged as KM three two
Speaker 2: three zero two one three A catch you name, right,
Speaker 2: But what that string of letters and numbers actually represents
Speaker 2: is a violent collision with the deepest mysteries of physics.
Speaker 3: The sheer physics of this event is honestly difficult to overstate, right.
Speaker 2: Because we are talking about a particle that is essentially massless, right,
Speaker 2: a spect of subatomic nothingness just slamming into our reality
Speaker 2: with two hundred and twenty ped electron volts of.
Speaker 3: Energy, exactly. And to find the source of that kind
Speaker 3: of power, you really have to look past the normal,
Speaker 3: quiet processes of the cosmos.
Speaker 2: You have to look at the high energy universe, like
Speaker 2: the cataclysmic, the ancient, and the catastrophic stuff.
Speaker 3: You do because standard stars don't do this, No, they don't.
Speaker 2: And for anyone listening right now, I want to stress
Speaker 2: that this isn't just some abstract accounting error in a
Speaker 2: theoretical physics paper. This is about probing the actual architecture.
Speaker 3: Of reality, the literal rulebook of the universe.
Speaker 2: Yeah, the laws of physics that govern the device you
Speaker 2: are listening on the biology of yourselves, the gravity holding
Speaker 2: you to the floor. I mean, those laws are currently incomplete.
Speaker 2: We know they are broken at the extremes, and.
Speaker 3: This single two hundred and twenty ped electron bolt ghost
Speaker 3: might be the exact tool we need to find out
Speaker 3: what the real rules actually are.
Speaker 2: So we need to break this down mechanically, because before
Speaker 2: we can even get to the underwater trap or you know,
Speaker 2: the crazy cosmic origins, we have to start with the
Speaker 2: anatomy of the phantom itself. We are talking about neutrinos.
Speaker 3: Right, the neutrino. It is perhaps the most solitary particle
Speaker 3: in the entire standard model of physics.
Speaker 2: It's kind of the ultimate loaner.
Speaker 3: That is a perfect way to put it. Because to
Speaker 3: understand its isolation, you have have to look at how
Speaker 3: particles actually communicate with one another. I mean, in the
Speaker 3: quantum realm, interaction is communication.
Speaker 2: Right, like how electrons push away from other electrons because
Speaker 2: they communicate via the electromagnetic force. They exchange photons.
Speaker 3: Exactly, and quarks bind together in the nucleus because they
Speaker 3: communicate via the strong nuclear force by exchanging gluons.
Speaker 2: So they basically have a mechanism to say I'm here,
Speaker 2: get away from me, or i am here stick to me.
Speaker 3: Yes, exactly. But the neutrino is entirely blind to electromagnetism.
Speaker 3: It carries zero electrical charge.
Speaker 2: So it literally cannot feel magnetic fields, and it cannot
Speaker 2: interact with light at all.
Speaker 3: None. And it is also completely blind to the strong
Speaker 3: nuclear force, so it just ignores the dense cores of atoms.
Speaker 3: Out of the fundamental forces of nature, the neutrino only
Speaker 3: feels two of.
Speaker 2: Them, gravity and the weak nuclear force.
Speaker 3: Right, and since gravity is incredibly feeble on a subatomic scale,
Speaker 3: that really just leaves the weak force, which you.
Speaker 2: Know to its name, doesn't give you a whole lot
Speaker 2: of stopping power.
Speaker 3: No, it really doesn't. The weak force is notoriously short range.
Speaker 3: I mean, for a neutrino to actually interact with another
Speaker 3: particle via the weak force, it essentially has to score
Speaker 3: a direct head on microscopic.
Speaker 2: Collision, like hitting a bulls eye on a darkboard that's
Speaker 2: a mile away.
Speaker 3: Smaller, it has to hit a quark inside a proton
Speaker 3: or a neutron. And because atoms are famously what ninety
Speaker 3: nine point nine nine nine nine nine percent empty space,
Speaker 3: the odds of that direct hit are astronomically low.
Speaker 2: I remember reading once that you could fire a neutrino
Speaker 2: through a block of solid lead a light year thick,
Speaker 2: and there's a very very good chance it just emerges
Speaker 2: completely untouched.
Speaker 3: On the other side, it's entirely possible. They are that
Speaker 3: non interactive.
Speaker 2: So this brings us to the characteristic that frankly completely
Speaker 2: breaks my intuition about this specific particle KM three two
Speaker 2: three zero two one three A. If a neutrino is
Speaker 2: just this ghostly non interacting point in space, how does
Speaker 2: it carry energy? Ah? Right, let's just look at the
Speaker 2: numbers for a second detection from February twenty twenty three
Speaker 2: was calculated at two hundred and twenty PEEDA paid electron volts.
Speaker 2: That is two hundred and twenty million billion electron volts.
Speaker 3: It's a staggering number, it is.
Speaker 2: And in classical physics, I mean, kinetic energy is basically
Speaker 2: mass in motion, right, A heavier object hits harder. But
Speaker 2: physicists spent decades thinking neutrino's had literally zero mass, and
Speaker 2: even today we know their mass is just infinitesimally.
Speaker 3: Small, practically zero.
Speaker 2: Right, So if you have almost zero mass. Where's that
Speaker 2: two hundred and twenty million billion electron volts actually being stored?
Speaker 2: It sounds like saying a literal speck of dust hit
Speaker 2: you with the force of a freight train. How do
Speaker 2: we even wrap our heads around that?
Speaker 3: Well, you are hitting on a fundamental disconnect between classical
Speaker 3: physics and relativity here. I mean, in high school physics,
Speaker 3: we are all taught the kinetic energy equation, right, one
Speaker 3: half mass times velocity squared.
Speaker 2: Yeah, that's the one where if his mass approaches zero,
Speaker 2: the energy should approve to zero exactly.
Speaker 3: But that equation is really just an approximation for things
Speaker 3: moving slowly. When you deal with the high energy universe,
Speaker 3: you have to throw that out and use Einstein's full
Speaker 3: energy momentum relation.
Speaker 2: Right, So everyone knows E equals mc squared. But that's
Speaker 2: not the whole equation.
Speaker 3: Is it. No, it isn't. The full equation is actually
Speaker 3: E squared equals pc squared plus mc squared squared.
Speaker 2: Okay, unpacking that a bit, So the P in.
Speaker 3: That equation stands for momentum. So a particle's total energy
Speaker 3: is actually a combination of its rest mass and its momentum.
Speaker 2: Oh, I see so for a heavy particle that's just
Speaker 2: sitting still, the momentum part is zero, and you just
Speaker 2: get the classic E equals mc square, Yes, exactly.
Speaker 3: But for a neutrino, the rest mass is so vanishingly
Speaker 3: small that the mc squared part of the equation is
Speaker 3: basically irrelevant. It drops away. Almost one hundred percent of
Speaker 3: its energy comes entirely from its momentum.
Speaker 2: Wow. So it's not hitting hard because it's heavy. It's
Speaker 2: hitting hard strictly because it has been accelerated to a
Speaker 2: velocity so incredibly close to the speed of light that
Speaker 2: its momentum approaches the macroscopic scale.
Speaker 3: It is a pure, concentrated bullet of relativistic momentum. And
Speaker 3: to put that two hundred and twenty Peavy into perspective,
Speaker 3: let's look at the most powerful machine humanity has ever built.
Speaker 2: The Large Hadron Collider in Switzerland. Right.
Speaker 3: The LHC is a twenty seven kilometer ring of superconducting
Speaker 3: magnets cooled to near absolute zero, designed to basically smash
Speaker 3: protons together, and.
Speaker 2: When it is running an absolute maximum capacity, it pushes
Speaker 2: particles to about what thirteen point six tarra electron volts,
Speaker 2: or a tav right.
Speaker 3: Now, yes, and a single tavy is often compared to
Speaker 3: the kinetic energy of a flying mostuito, okay, a mosquito. Now.
Speaker 3: Taking the macroscopic energy of a flying mosquito and cramming
Speaker 3: it into a single microscopic proton is an astonishing feat
Speaker 3: of human engineering. But the universe scales this up brutally.
Speaker 2: Because a ped electron volt is one thousand teo electron.
Speaker 3: Volts exactly, so one peavy is a thousand times more
Speaker 3: energetic than a mosquito. And km three two three zero
Speaker 3: two one three A was hearing two hundred and twenty
Speaker 3: of them, so it was.
Speaker 2: A single sytomic point carrying the physical kinetic force of
Speaker 2: a dropped brick.
Speaker 3: A dropped brick entirely contained within something smaller than an atom.
Speaker 2: That just stretches the limits of imagination. I mean, we
Speaker 2: are not generating anything close to that on Earth. We
Speaker 2: are maxing out around fourteen TV. This thing arrived at
Speaker 2: two hundred and twenty thousand TV. The machinery required to
Speaker 2: impart that kind of momentum to a particle just cannot
Speaker 2: be a quiet star.
Speaker 3: Now, it requires violence on a cosmic scale. When physicists
Speaker 3: look for the sources of pebby neutrinos. They are looking
Speaker 3: for engines of extreme gravity and magnetism like what well,
Speaker 3: they look at active galactic nuclei for one. These are
Speaker 3: super massive black holes at the centers of distant galaxies
Speaker 3: that are actively feeding on matter.
Speaker 2: Oh right, And as the gas and stars get shredded
Speaker 2: and pulled into the black hole, the magnetic fields get
Speaker 2: all twisted up.
Speaker 3: Ranks, extremely twisted. They form these massive relativistic jets that
Speaker 3: just shoot out from the poles at near light speed.
Speaker 2: So the magnetic fields around the black hole are essentially
Speaker 2: acting like the superconducting magnets in the LHC, but just
Speaker 2: on a scale of light years.
Speaker 3: The acceleration mechanics are very similar, but orders of magnitude
Speaker 3: more tents particles get trapped in the shockwaves of those jets,
Speaker 3: just bouncing back and forth across the magnetic boundaries.
Speaker 2: Gaining energy with every bound.
Speaker 3: Exactly until they are finally ejected out into the void.
Speaker 3: Or another option is we look at kilanovae.
Speaker 2: That's the catastrophic collision of two neutron stars.
Speaker 3: Right, Yes, the sheer density and the gravitational collapse of
Speaker 3: those events create magnetic fields trillions of times stronger than Earth's.
Speaker 3: I mean, these environments are the universe's natural particle accelerators.
Speaker 2: Okay, so that sets up the stakes perfectly. We know
Speaker 2: there are these apocalyptic engines out there in the deep
Speaker 2: universe spitting out these relativistic ghosts. And the ghost travels
Speaker 2: in a straight line for millions, billions of.
Speaker 3: Years, completely untouched.
Speaker 2: Right it enters our solar system, it approaches Earth. And
Speaker 2: this brings us back to the Kapplopasero site in the Mediterranean.
Speaker 2: Because if this particle passes right through planets, how did
Speaker 2: that grid of sensors at the bottom of the ocean
Speaker 2: actually catch it?
Speaker 3: That is the million dollar question.
Speaker 2: Let's dive into the mechanics of the underwater trap and
Speaker 2: you know the famous blue flash.
Speaker 3: Well, to detect a particle that refuses to interact with anything,
Speaker 3: you obviously cannot build a traditional telescope. You can't just
Speaker 3: point a glass lens at the sky.
Speaker 2: Right because it would just go right through the glass exactly.
Speaker 3: So you have to build a giant volume of target
Speaker 3: material and simply wait for a statistical miracle. You need
Speaker 3: a space where the ghost against all odds happens to
Speaker 3: hit the nucleus of an atom directly, and.
Speaker 2: The target material in this case is the entire Mediterranean Sea.
Speaker 2: But the immediate question that comes to my mind when
Speaker 2: looking at the cam through net project is the location.
Speaker 3: Why I put it there?
Speaker 2: Yeah? If I want to observe high energy cosmic phenomena,
Speaker 2: my instinct is to get as high up as possible,
Speaker 2: put a satellite in orbit, or build an observatory on
Speaker 2: a high altitude plateau in Chili. Why go three five
Speaker 2: hundred meters down under billions of gallons of salt water
Speaker 2: to look at the sky.
Speaker 3: It's a great question, and it's because the ocean isn't
Speaker 3: the lens of the telescope. The ocean is the shield.
Speaker 2: The shield.
Speaker 3: Yeah, the surface of the Earth is incredibly noisy from
Speaker 3: a particle physics perspective. I mean, we are constantly being
Speaker 3: bombarded by standard cosmic rays, protons, alpha particles, electrons.
Speaker 2: Right, and when these hit the upper atmosphere, they create
Speaker 2: a kind of chaotic shower of secondary particles that just
Speaker 2: rain down on the surface constantly.
Speaker 3: Exactly. So, if you put a sensitive and neutrino detector
Speaker 3: on a mountaintop, its sensors would be completely overwhelmed by
Speaker 3: this constant static.
Speaker 2: It would be like trying to listen for a pin
Speaker 2: drop while standing next to a jet engine. The signal
Speaker 2: of a single rare neutrino would just be totally lost
Speaker 2: in the background radiation.
Speaker 3: Precisely, so you have to bury the detector. And the
Speaker 3: further down you go, the more the surrounding matter filters
Speaker 3: out the noise. Kilometers of seawater provide an excellent dense
Speaker 3: barrier against all those standard cosmic rays.
Speaker 2: But wait, the Earth itself provides the ultimate filter, doesn't it,
Speaker 2: Because the CAM three net array is essentially looking down,
Speaker 2: not up.
Speaker 3: Yes, it uses the entire mass of the planet Earth
Speaker 3: as a shield to block everything coming from the other side.
Speaker 2: Because the only thing that can travel through the Earth
Speaker 2: from the opposite hemisphere and emerge into the Mediterranean Sea
Speaker 2: bed without being stopped is a neutrino.
Speaker 3: Exactly, So the detector just sits in the quiet, isolated dark,
Speaker 3: waiting for a neutrino to make that one in a
Speaker 3: trillion interaction via the weak nuclear force.
Speaker 2: Okay, let's mechanically unpack that interaction. Because the detector doesn't
Speaker 2: actually see the neutrino itself. Right, it sees the shrapnel.
Speaker 3: Yes, the shrapnel. The interaction itself is a really sudden,
Speaker 3: violent transformation. Remember, the neutrino is carrying two hundred and
Speaker 3: twenty pv of momentum. When it finally strikes a quark
Speaker 3: inside an oxygen or hydrogen nucleus in a water molecule,
Speaker 3: it initiates a weak foce exchange.
Speaker 2: Specifically, it exchanges a heavy unstable particle called w boson
Speaker 2: with the nucleus. This is the actual mechanism of the
Speaker 2: weak interaction. They're literally trading a particle.
Speaker 3: They are, and the result of that trade is fundamental transformation.
Speaker 3: The neutrino ceases to be a neutrino, Its energy and
Speaker 3: quantum numbers are transferred, and a new particle is created
Speaker 3: right there in its place.
Speaker 2: And in the case of KM three two three zero
Speaker 2: two one three A, the interaction produced a particle called a.
Speaker 3: Muon, exactly a muon.
Speaker 2: Which is essentially a much heavier, highly unstable cousin of
Speaker 2: the electron.
Speaker 3: Right. Yes, and crucially, unlike the neutrino, the muon actually
Speaker 3: carries an electrical charge. Furthermore, because of the laws of
Speaker 3: conservation of momentum, This newly born muon inherits a vast
Speaker 3: majority of that two hundred and twenty pev of energy.
Speaker 3: Oh wow, So you suddenly have a highly charged particle
Speaker 3: violently tearing through the water at a velocity so close
Speaker 3: to the speed of light in a vacuum that the
Speaker 3: difference is basically a.
Speaker 2: Marginal And this triggers the phenomenon that km three net
Speaker 2: is actually looking for care and copp radiation, the famous
Speaker 2: blue glow. I mean, you see this in pictures of
Speaker 2: underwater nuclear reactors, right, that eerie, vibrant blue light. Yes,
Speaker 2: But the mechanism behind that glow is why mildly counterintuitive
Speaker 2: to me. Yeah, it happens because the muon is moving
Speaker 2: through the water faster than light itself can move through
Speaker 2: the water.
Speaker 3: It is counterintuitive. The concept of moving faster than light
Speaker 3: often trips people up because of the hard cosmic speed
Speaker 3: limit that Einstein established.
Speaker 2: Right, nothing can go faster than the speed of light exactly.
Speaker 3: But Einstein's limit, which is roughly three hundred thousand kilometers
Speaker 3: per second, applies strictly to the speed of light in
Speaker 3: a perfect vacuum.
Speaker 2: Ah.
Speaker 3: When light enters a medium like glass or you know, water,
Speaker 3: it interacts with the electromagnetic fields of the atoms in
Speaker 3: that medium, and its propagation speed drops. In water, the
Speaker 3: phase velocity of light is only about two hundred and
Speaker 3: twenty five thousand kilometers per.
Speaker 2: Second, But our two hundred and twenty peavy muon doesn't
Speaker 2: care about the water's optical speed limit. It is being
Speaker 2: pushed by such immense relativistic momentum that it plows right
Speaker 2: through the water at two hundred and ninety nine thousand
Speaker 2: kilometers per second.
Speaker 3: So it is literally outpacing the local speed of light.
Speaker 3: It's blowing past it, and the physics of what happens
Speaker 3: next is beautifully violent. As this highly charged muon rips
Speaker 3: through the water molecules, its electromagnetic field forcefully pushes the
Speaker 3: electrons of the water molecules out of their stable orbits.
Speaker 2: It displaces them. It's physically shoving the localized electromagnetic field
Speaker 2: out of the way.
Speaker 3: It shoves them aside and then immediately passes by. But
Speaker 3: once the muon is gone, those displaced electrons violently snap
Speaker 3: back into their original stable positions. And when an electron
Speaker 3: snaps back to a lower energy state, it releases a
Speaker 3: photon a.
Speaker 2: Packet of light exactly. But if the muon was moving slowly,
Speaker 2: those photons would just randomly scatter, right, It would just
Speaker 2: be a faint, disorganized glow.
Speaker 3: It wouldn't even be a glow. If a particle moves
Speaker 3: slower than light. In that medium, the polarization of the
Speaker 3: molecules is symmetrical front and back. The electromagnetic disturbances cancel
Speaker 3: each other out, resulting in absolutely no net radiation.
Speaker 2: Oh.
Speaker 3: Interesting, But because the muon is moving faster than the
Speaker 3: emitted photons can travel away from it, the geometry changes completely.
Speaker 3: Polariation is asymmetrical. The photons being emitted as the electrons
Speaker 3: snap back, are forced to pile up on top of
Speaker 3: each other, constantly overlapping.
Speaker 2: Okay, so it is the exact same physics as a
Speaker 2: jet breaking the sound barrier, but just translated into the
Speaker 2: electromagnetic spectrum. Like a jet moves faster than the sound
Speaker 2: waves it creates, so the waves compress into a single
Speaker 2: massive acoustic shockwave a sonic boom.
Speaker 3: Exactly.
Speaker 2: The muon moves faster than the light waves it creates,
Speaker 2: forcing them to compress into an optical shockwave.
Speaker 3: That is a brilliant way to phrase it. And that
Speaker 3: optical shockwave takes the form of a cone of bluish
Speaker 3: lights spreading out behind the particle that is Scherenkov radiation,
Speaker 3: and that blue cone is the footprint that came. Three
Speaker 3: net sensors are waiting to catch.
Speaker 2: So let's picture the detector array again. We have these
Speaker 2: long vertical strings of spheres anchored to the seafloor. Inside
Speaker 2: each of those spheres are photomultiplier tubes. Yes, and these
Speaker 2: are instruments so incredibly sensitive they can literally detect a
Speaker 2: single individual photon of light hitting them in the pitch black.
Speaker 3: They are that sensitive. So as the muon streaks through
Speaker 3: the kilometer of water, the cone of blue light washes
Speaker 3: over the sensor grid. The photo multiplier tubes trigger recording
Speaker 3: the exact nanosecond the light hits them and the exact
Speaker 3: intensity of that light.
Speaker 2: And from those nanosecond time stamps you reconstruct reality. I mean,
Speaker 2: if a sensor on the left side of the grid
Speaker 2: registers a hit a tiny fraction of a second before
Speaker 2: a sensor on the right, you know the cone is
Speaker 2: moving left.
Speaker 3: To right exactly. By tracking the cascade of triggers across
Speaker 3: the three D volume, the computers rebuild the precise trajectory
Speaker 3: of the muon, and by measuring the total amount of
Speaker 3: light emitted, they calculate its total.
Speaker 2: Energy, which is how the researchers were able to trace
Speaker 2: the track of km three two three zero two or
Speaker 2: two a g and calculate that horrifying two twenty pv
Speaker 2: energy figure. They literally saw the optical sonic boom left
Speaker 2: by the shrapnel of a collision that was born millions
Speaker 2: or billions of years ago.
Speaker 3: It's incorrect.
Speaker 2: It is a profound sequence of events. Yessive cosmic accelerator
Speaker 2: fires an invisible ghost across the void. It ignores every
Speaker 2: physical obstacle, plummets into the Mediterranean, hits a single oxygen atom,
Speaker 2: and spawns a charge clone that rips through the water
Speaker 2: so fast it tears a literal wave of blue light into.
Speaker 3: Existence, and that light is caught by a deep sea
Speaker 3: grid of perfectly timed glass eyes.
Speaker 2: Yeah, but recording the event is really only half the battle.
Speaker 2: Now we kind of step into the role of the detective.
Speaker 2: We have the path of the muon, we know the
Speaker 2: angle it was traveling, So how do we use that
Speaker 2: to find the monstra that fired the gun.
Speaker 3: Well, this brings us to why neutrinos are so highly
Speaker 3: prized in multi messenger astronomy. They are considered the ultimate
Speaker 3: incorruptible cosmic messengers.
Speaker 2: Incorruptible I like that.
Speaker 3: Yeah, As Rosa Cunniglioni, who was the deputy spokesperson at
Speaker 3: the time, pointed out, the very property is making neutrinos
Speaker 3: so impossibly difficult to catch for the exact same properties
Speaker 3: that make them invaluable, like their lack.
Speaker 2: Of charge, their tiny mass, their weak interaction.
Speaker 3: Exactly, they carry un tampered information from the most extreme
Speaker 3: distant phenomena in the universe.
Speaker 2: Let's contrast the neutrino with the other things we usually
Speaker 2: look at to study the sky, like photons and standard
Speaker 2: cosmic rays, because both of those have major flaws when
Speaker 2: you try to look across billions of.
Speaker 3: Light years, right, we definitely do. Let's start with standard
Speaker 3: high energy cosmic rays, which are mostly bare protons. Now,
Speaker 3: protons have a positive electrical charge, and the space between
Speaker 3: galaxies is not entirely empty, No.
Speaker 2: It's woven with these massive, twisting intergalactic magnetic fields.
Speaker 3: Exactly, so, when a charged proton travels through magnetic field,
Speaker 3: it experiences a perpendicular push known as the Lorentz.
Speaker 2: Force, its trajectory basically gets bent.
Speaker 3: It curves and over millions of light years, passing through
Speaker 3: the magnetic fields of various galaxy clusters and nebulae, that
Speaker 3: proton's path becomes a tangled, chaotic mess.
Speaker 2: So by the time it finally hits the Earth's atmosphere,
Speaker 2: its a rival direction has absolutely no correlation to its
Speaker 2: original solace. You cannot look back down the trajectory of
Speaker 2: a cosmic ray proton and see what fired it.
Speaker 3: You really can't.
Speaker 2: It's like trying to figure out who threw a bouncy
Speaker 2: ball by looking at the angle it hits you after
Speaker 2: it has already ricocheted off ten different walls. You know
Speaker 2: it was thrown hard, but the origin is completely lost.
Speaker 3: That's a great analogy.
Speaker 2: So what about photons, I mean, light travels in a
Speaker 2: straight line. Why don't we just use high energy gamma
Speaker 2: rays to map the extreme universe?
Speaker 3: Well, photons do travel straight, but they interact with matter.
Speaker 3: Space is full of interstellar dust, gas clouds, and background radiation.
Speaker 3: High energy photons have a very high probability of hitting something,
Speaker 3: being absorbed or scattering.
Speaker 2: So the universe is practically opaque to the highest energy
Speaker 2: light if you look far enough out.
Speaker 3: Yes, but the neutrino bypasses both of these physical limitations.
Speaker 2: Because it is electrically neutral, so the Lorentz force doesn't apply.
Speaker 2: The intergalactic magnetic fields cannot bend its path.
Speaker 3: At all exactly, and it is immune to the weak
Speaker 3: force's short range, so it punches straight through interstellar dust
Speaker 3: clouds without being absorbed. A neutrino created in the heart
Speaker 3: of an active galactic nucleus travels in a geodetically perfect,
Speaker 3: mathematically rigid straight line to the Capo Picero site.
Speaker 2: Okay, but here is my hangup. If that is true,
Speaker 2: if the flight path is a perfect, unbroken line, why
Speaker 2: is its origin still a mystery? I mean, why couldn't
Speaker 2: the researchers just take the three D trajectory reconstructed by
Speaker 2: the underwater sensors, draw a straight line backward into the sky,
Speaker 2: and point to a specific collapsing star or black hole.
Speaker 3: It's a fair question.
Speaker 2: They narrat it down to four broad origin zones right, galactic, local, universe, transient,
Speaker 2: and extragalactic. Why such a wide net if the particle
Speaker 2: flew perfectly scored.
Speaker 3: The ambiguity doesn't come from the neutrino's journey through space.
Speaker 3: The ambiguity comes from the physical mechanics of the collision
Speaker 3: inside the water and the inherent limits of human engineering.
Speaker 3: Oh I see, because when you draw a line backward
Speaker 3: across billions of light years, the tiniest fraction of a
Speaker 3: degree of error at the starting point expands into a massive,
Speaker 3: sweeping cone of uncertainty at the destination.
Speaker 2: Right, because geometry is just unforgiving it. Cosmic scales, if
Speaker 2: you are off by a millimeter here, you are off
Speaker 2: by a galaxy cluster.
Speaker 3: Over there, precisely. And there are two sources of that error. First,
Speaker 3: there's the kinematic scattering angle. When the neutrino hits the
Speaker 3: quark and produces the muon via the weak force, the
Speaker 3: muon doesn't always continue on the exact, mathematically perfect trajectory
Speaker 3: of the incoming neutrino because.
Speaker 2: The exchange of the massive w boson imparts a tiny
Speaker 2: amount of transverse momentum.
Speaker 3: Yes, the muon's path is ever so slightly skewed from
Speaker 3: the original neutrino vector.
Speaker 2: So the shrapnel doesn't fly perfectly straight from the point
Speaker 2: of impact.
Speaker 3: It is incredibly close, especially at two twenty pay v
Speaker 3: where four momentum heavily dominates, but there is still a
Speaker 3: fractional divergence. And then the second source of error is
Speaker 3: the detector resolution itself.
Speaker 2: Right because caantri net is a triumph of engineering. Sure,
Speaker 2: but the photo multiplier tubes are still reconstructing a light
Speaker 2: cone through moving ocean water exactly.
Speaker 3: There is scattering of light deep sea currents, and tiny
Speaker 3: limits to the nanosecond timing resolution. When the algorithms process
Speaker 3: all that data, they calculate a trajectory with a margin
Speaker 3: of error an angular resolution usually around point one to
Speaker 3: point two degrees, and aero point.
Speaker 2: Two degree circle in the night sky might look tiny
Speaker 2: to the naked eye, but when you project it deep
Speaker 2: into the extra galactic void, that circle contains thousands, maybe millions,
Speaker 2: of stars, galaxies, and potential high energy sources, which is.
Speaker 3: Why the researchers categorize the potential sources into those four
Speaker 3: distinct topological zones.
Speaker 2: Let's run through though, so was it galactic, meaning a
Speaker 2: source located within the disk of our own milky Way,
Speaker 2: like maybe a highly magnetized pulsar, or.
Speaker 3: Was it the local universe originating from nearby galaxy groups
Speaker 3: within a few hundred million light years, or was.
Speaker 2: It transient a sudden temporary explosion like a gamma ray
Speaker 2: burst that went off and has since fate to dark.
Speaker 3: Or finally, was it extragalactic, a deep space phenomenon from
Speaker 3: the distant cosmic past.
Speaker 2: And usually by analyzing the energy levels and cross referencing
Speaker 2: with other optical telescopes observing that patch of sky at
Speaker 2: that exact time, they look for coincidences. If an active
Speaker 2: galactic nucleus in that zero point two degree circle flared
Speaker 2: up right when the neutrino arrived, you have a prime suspect.
Speaker 3: You do. But because Cam three two three zero two
Speaker 3: one three A arrived with that unprecedented two twenty pv punch,
Speaker 3: it just doesn't comfortably match the standard models for a
Speaker 3: lot of those local suspects.
Speaker 2: The sheer magnitude of the energy just demands something more.
Speaker 3: It does. The event sits right on the edge of
Speaker 3: what standard astrophysical sources can reasonably produce. It is so
Speaker 3: energetic that they were compelled to introduce a viable alternative hypothesis.
Speaker 2: And this brings us to the absolute climax of this event,
Speaker 2: the possibility that honestly makes physicists stay up at night
Speaker 2: because if this wasn't fired by a standard cosmic accelerator,
Speaker 2: we step into the realm of the cosmogenic hypothesis.
Speaker 3: The cosmogonic neutrino.
Speaker 2: Yeah, this is the idea that the neutrino we caught
Speaker 2: in the Mediterranean wasn't the exhaust of a dying star
Speaker 2: at all, but the shrapnel from a collision with the
Speaker 2: echo of the Big Bang itself.
Speaker 3: It is one of the most sought after theoretical particles
Speaker 3: in modern astrophysics. It bridges the gap between the highest
Speaker 3: energy particles we know of and the oldest light in existence.
Speaker 2: Okay, let's break down the mechanics of this hypothesis because
Speaker 2: we have to look at the interactions dictated by a
Speaker 2: concept called the GZK limit. Right, the riisens ots of
Speaker 2: ben Kuzmin limit.
Speaker 3: Yes, the GZK limit, and to understand it we need
Speaker 3: two components. The first component is an ultra high energy
Speaker 3: cosmic ray or UACR.
Speaker 2: These are typically stray protons that have been accelerated to
Speaker 2: the absolute maximum theoretical limits of the universe. I mean,
Speaker 2: their velocity is so unimaginably close to the speed of
Speaker 2: light that their kinetic energy makes the two hundred and
Speaker 2: twenty PAVI neutrino look weak in comparison.
Speaker 3: Oh. Absolutely, We are talking about protons carrying exelection bolts,
Speaker 3: billions of tear electron vaults.
Speaker 2: So we have this impossibly fast, impossibly energetic proton tearing
Speaker 2: through the intergalactic void. That is ingredient one.
Speaker 3: Ingredient two is the cosmic microwave background, or the CMB.
Speaker 3: Right around three hundred and eighty thousand years after the
Speaker 3: Big Bang, the universe had cooled enough for the first
Speaker 3: neutral atoms to form. This period, called recombination, basically allowed
Speaker 3: photon's light to finally travel freely through space without constantly
Speaker 3: scattering off a dense plasma, and.
Speaker 2: That initial burst of light has been traveling through the
Speaker 2: universe ever since it has.
Speaker 3: But the universe isn't static. It has been expanding for
Speaker 3: thirteen point eight billion years, and.
Speaker 2: As the fabric of space expands, the wavelengths of those
Speaker 2: ancient photons stretch with it. So what started as intensely hot,
Speaker 2: high energy light has been stretched out over billions of
Speaker 2: years into long low energy microwave.
Speaker 3: Radiation exactly today, the CMB is just a faint cold
Speaker 3: bath of microwave photons that permeates every single cube millimeter
Speaker 3: of the cosmos. It sits at about two point seven
Speaker 3: degrees above absolute zero.
Speaker 2: Okay, so space isn't an empty vacuum. It is a
Speaker 2: physical sea of ancient microwave photons. But a microwave is
Speaker 2: low energy. I mean, if I fire a proton through
Speaker 2: a microwave oven in my kitchen, proton doesn't care, just
Speaker 2: passes straight through.
Speaker 3: Right.
Speaker 2: So how does a low energy ambient glow interact with
Speaker 2: an ultra high energy cosmic ray? I mean it sounds
Speaker 2: like trying to crash a speeding car into a sunbeam.
Speaker 3: That is a great visual, but this is where we
Speaker 3: have to shift our frame of reference. The interaction only
Speaker 3: makes sense when you apply the relativistic Doppler effect.
Speaker 2: A Doppler effect like with sound.
Speaker 3: Exactly Like with sound, think of an ambulance driving past you.
Speaker 3: As it speeds toward you, the sound waves compress and
Speaker 3: the pitch goes up. As it speeds away, the waves
Speaker 3: stretch and the pitch drops, So.
Speaker 2: The relative velocity changes the frequency of the wave. You perceive.
Speaker 3: The exact same principle applies to light. If you are
Speaker 3: sitting still in space, the CMB looks like a harmless,
Speaker 3: low energy microwave. But if you are a proton traveling
Speaker 3: head on into that photon sea at ninety nine point
Speaker 3: nine nine nine nine percent, the speed of light, relativity
Speaker 3: dramatically alters the geometry of the collision, because.
Speaker 2: From the fring of reference of the speeding proton, the
Speaker 2: wavelengths of the oncoming CMB photons are catastrophically compressed.
Speaker 3: Yes, the Doppler shift is so extreme that the low
Speaker 3: energy microwave gets blue shifted into a devastatingly high energy
Speaker 3: gamma ray.
Speaker 2: Wow, So the proton doesn't see a cold bath of
Speaker 2: microwaves at all. It sees a blinding lethal wall of gamma.
Speaker 3: Radiation exactly, And when the kinetic energy in the center
Speaker 3: of mass frame of that collision crosses a specific threshold,
Speaker 3: the photon physically shatters the proton.
Speaker 2: It hits the proton with enough force to overcome the
Speaker 2: strong nuclear force holding its quirks together.
Speaker 3: Specifically, the photon excites the proton into a highly unstable
Speaker 3: state called a delta baryon resonance.
Speaker 2: Okay, delta barion resonance, and.
Speaker 3: This delta resonance survives for an infinitesimally small fraction of
Speaker 3: a second before decaying violently. The proton essentially falls apart,
Speaker 3: creating a secondary nucleon and a particle called a pion.
Speaker 2: And the pion is also highly unstable, right very unstable.
Speaker 3: It immediately decays into a muon and a neutrino, a
Speaker 3: cosmogenic neutrino born from the ashes of a proton shattering
Speaker 3: against the cosmic microwave background.
Speaker 2: That is just wild, it is.
Speaker 3: And this entire process, the GZK suppression, acts as an
Speaker 3: absolute speed limit for cosmic rays. Protons above a certain
Speaker 3: energy simply cannot travel across the vastness of the universe
Speaker 3: because the CMB acts like an embrace of friction.
Speaker 2: It slowly degrades them through these violent collisions until their
Speaker 2: energy drops below the threshold exactly. But while the proton
Speaker 2: is destroyed, the neutrino at births carries away a massive
Speaker 2: fraction of its energy. And because the neutrino has no charge,
Speaker 2: it ignores the CMB completely. It ignores the magnetic fields.
Speaker 2: It just takes the momentum of that ancient collision and
Speaker 2: flies perfectly straight, unbothered until it reaches the Mediterranean Sea.
Speaker 3: And this is exactly why the detection is so provocative.
Speaker 3: The theoretical energy profile calculated for cosmogenic neutrinos, the energy
Speaker 3: they should inherit from those GK collisions, align staggeringly well
Speaker 3: with the two hundred and twenty pay v signature we saw.
Speaker 2: Because the energy is so high that it is difficult
Speaker 2: for standard astrophysical models to explain without introducing a lot
Speaker 2: of complicated, tailored variables. The cosmogenetic hypothesis, while bold offers
Speaker 2: a mechanically clean explanation for the sheer power of the.
Speaker 3: Event, it does if it's the data beautifully So if
Speaker 3: this is.
Speaker 2: True, if all we caught in the kapopiserocite is genuinely
Speaker 2: a primordial cosmogenic neutrino, how does that alter the landscape
Speaker 2: of modern physics.
Speaker 3: Well, it changes everything.
Speaker 2: The researchers actually call this potential conformation a scientific bonanza.
Speaker 2: But why what does an invisible piece of shrapnel from
Speaker 2: a dead proton actually allow us to do?
Speaker 3: Well? Primarily, it gives us a probe that penetrates the
Speaker 3: deepest fog of the early universe.
Speaker 2: Because cosmogenic neutrinos are continuously produced wherever ultra high energy came,
Speaker 2: cosmic rays interact with the CMB, so they represent an
Speaker 2: integrated history of the universe's most violent inbox.
Speaker 3: Exactly, by catching enough of them and tracing their energies
Speaker 3: and trajectories, we can look far beyond the optical horizons
Speaker 3: of current telescopes. We could basically map the cosmic evolution
Speaker 3: of ultra high energy sources.
Speaker 2: Effectively viewing the high energy architecture of the cosmos billions
Speaker 2: of years ago. We are reading the fossil record of
Speaker 2: the universe's most extreme gravitational engines.
Speaker 3: We are, but the implications honestly go much deeper than astronomy.
Speaker 3: The true prize here is particle physics itself. Because the
Speaker 3: energy domain we are looking at two twenty PV is
Speaker 3: entirely inaccessible on Earth.
Speaker 2: Right because of the limitations of the LAC we discussed earlier,
Speaker 2: we max out at fourteen TV.
Speaker 3: We simply cannot build a machine large enough or generate
Speaker 3: magnetic fields powerful enough to accelerate particles to peavy energies.
Speaker 3: I mean, to do so with current technology, you would
Speaker 3: need a particle accelerator the size of the Earth's equator.
Speaker 2: So if we want to understand how the fundamental forces
Speaker 2: of nature behave at the absolute extreme upper limits of energy,
Speaker 2: our only option is to use the universe itself as
Speaker 2: the accelerator and.
Speaker 3: Build deep sea nets to catch the results.
Speaker 2: Right and observing behavior at those extreme upper limits is
Speaker 2: critical because our current rule book for reality, the Standard
Speaker 2: Model of particle physics, is known to be incomplete, very incomplete.
Speaker 3: It is a beautiful mathematically predictive framework, sure, but it
Speaker 3: has gaping holes when you push it too hard.
Speaker 2: You mentioned physics beyond the Standard Model. But to the
Speaker 2: person listening right now, the standard model is just a
Speaker 2: chart on a chalkboard. Why does breaking the Standard model
Speaker 2: actually matter to human progress?
Speaker 3: Well, the Standard model is really just a low energy approximation.
Speaker 3: It exquisitely describes the electromagnetic force, the strong force, and
Speaker 3: the weak force. It classifies all the quarks and leptones,
Speaker 3: but it operates under specific localized conditions.
Speaker 2: And the most glaring emission is gravity.
Speaker 3: Yes, general relativity, our theory of gravity deals with smooth,
Speaker 3: continuous curves in space time. The standard model deals with quantize,
Speaker 3: discrete erratic jumps of energy. The mathematical frameworks of the
Speaker 3: two models are fiercely incompatible.
Speaker 2: When you try to combine the math of quantum mechanics
Speaker 2: with the math of general relativity, the equations just break
Speaker 2: down completely. They spit out infinities, they stop making sense.
Speaker 3: Furthermore, the Standard model offers no explanation for dark matter
Speaker 3: or dark energy.
Speaker 2: Which cosmological observations tell us comprise about ninety five percent
Speaker 2: of the total mass energy content of the universe.
Speaker 3: Right the standard model literally only describes five percent of reality.
Speaker 2: That puts it in perspective.
Speaker 3: So to find the theories that unify gravity with quantum mechanics,
Speaker 3: to find theories that explain dark matter, physicists believe we
Speaker 3: need to observe physics at exponentially higher energy scales, where
Speaker 3: the distinct fundamental forces might begin to merge into a
Speaker 3: single unified force.
Speaker 2: In a two twenty pevy neutrino might be carrying the
Speaker 2: data of that high energy behavior, it might show signs
Speaker 2: of Lorenz invariance violation.
Speaker 3: That is one of the most tantalizing prospects. Lorentz invariance
Speaker 3: is the foundational principle of special relativity the idea that
Speaker 3: the laws of physics, including the speed of light in
Speaker 3: a vacuum, are identical for all observers, regardless of their
Speaker 3: relative motion. But some theories of quantum gravity suggest that
Speaker 3: at incredibly high energies, space itself is not smooth but quantized,
Speaker 3: meaning it's made of tiny, discrete, bubbling pixels of space
Speaker 3: time at the Plank scale.
Speaker 2: Oh wow, So if space time is pixelated, then high
Speaker 2: energy particles might experience a sort of drag as they
Speaker 2: move across those pixels, slightly altering their speed or how
Speaker 2: they oscillate.
Speaker 3: Exactly. A new trino traveling billions of light years at
Speaker 3: two hundred and twenty pv would amplify those microscopic quantum
Speaker 3: gravity effects into something macroscopic that a detector like KM
Speaker 3: three net might actually be able to measure.
Speaker 2: So if we observe anomalies in the flavor oscillations of
Speaker 2: these ultra high energy neutrinos, or even delays in their
Speaker 2: arrival times compared to photons, it could provide the first
Speaker 2: experimental evidence of physics beyond the standard model.
Speaker 3: It could be the crack in the dam that leads
Speaker 3: to a unified theory of quantum gravity.
Speaker 2: That is the ultimate stakes of the game here. It
Speaker 2: is not just about cataloging another particle. It is about
Speaker 2: finding the thread that, when pulled, unravels the incomplete physics
Speaker 2: of the twentieth century and allows us to weave the
Speaker 2: actual fundamental architecture of reality.
Speaker 3: Which perfectly explains why the CAM three net project is
Speaker 3: not just resting on this single.
Speaker 2: Detection right the Kepopacero site is actively expanding. The cubic
Speaker 2: kilometer array is designed to be highly modular. By adding
Speaker 2: more strings of photo multiplier tubes, they increase the total
Speaker 2: effective volume of the detector.
Speaker 3: And more volume means more target water molecules, which linearly
Speaker 3: increases the statistical probability of catching the next PEAVI interaction.
Speaker 2: They're widening the net to catch more ghosts, and with
Speaker 2: more data points they can reduce those angular resolution errors
Speaker 2: we talked about.
Speaker 3: Yes, if they can catch of these two hundred and
Speaker 3: twenty peavy neutrinos and trace their trajectories back with sharper precision,
Speaker 3: they can definitively answer whether these are coming from feeding
Speaker 3: black holes or if they are a diffuse isotropic wash
Speaker 3: of cosmogenic particles born from the cosmic microwave background.
Speaker 2: We are moving from a single isolated detection to a
Speaker 2: whole new era of ultra high energy neutrino astronomy. Every
Speaker 2: new capture provides another massive data point for high energy physics,
Speaker 2: slowly illuminating the dark, unseen machinery of the universe.
Speaker 3: It is genuinely a breathtaking scientific narrative when you zoom
Speaker 3: out and look at the whole picture.
Speaker 2: It really is. Yeah, I mean, just think about it.
Speaker 2: An ultra high energy cosmic ray, accelerated to the limits
Speaker 2: of physical reality by a primordial black hole, tears across
Speaker 2: the early Universe. It collides head on with a fopon
Speaker 2: leftover from the Big Bang, shattered by the relativistic Doppler shift.
Speaker 3: And from that violent decay, a ghostly, massless messenger is born.
Speaker 2: An impossible two hundred and twenty million billion electron voltsa momentum.
Speaker 2: It travels in mathematical perfection for eons, ignoring magnetic fields,
Speaker 2: passing through nebulae and dust. It enters our solar system,
Speaker 2: plunges through the Mediterranean, and hits a single oxygen nucleus.
Speaker 3: And the resulting shrapnel rips through the water faster than
Speaker 3: light tearing a blue optical shock wave into the absolute darkness.
Speaker 2: Or a grid of glass feres perfectly times the flashes,
Speaker 2: transmitting the data to the surface, a single flash of
Speaker 2: blue light containing the secrets of the ancient cosmos and
Speaker 2: the potential keys to quantum gravity.
Speaker 3: It is the pinnacle of human curiosity and engineering. I mean,
Speaker 3: we are using the entire Earth as a shield and
Speaker 3: a cubic kilometer of the deep ocean as a lens
Speaker 3: to read the echoes of the Big.
Speaker 2: Bang, which leaves a really profound physical reality to consider.
Speaker 2: As we conclude, as you sit here processing all of this,
Speaker 2: the universe is not stopped. The high energy engines are
Speaker 2: still firing constantly. Right now, every single second, tens of
Speaker 2: billions of neutrinos are passing straight through your body. They
Speaker 2: stream from the Sun, from the atmosphere, and from the
Speaker 2: deep extragalactic void. They pass through the roof of your house,
Speaker 2: through your cells, through the floor, and out the other
Speaker 2: side of the planet, entirely.
Speaker 3: Unnoticed, without you feeling a thing.
Speaker 2: Exactly, And if just one of those microscopic phantoms slamming
Speaker 2: into the dark depths of the sea holds the power
Speaker 2: to rewrite our fundamental understanding of reality. What other, invisible,
Speaker 2: unmeasured truths are flowing right through us at this very moment,
Speaker 2: simply waiting for humanity to build the right net to
Speaker 2: catch them.