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: Imagine for a second you're driving down this long, flat
Speaker 2: stretch of highway, you know, the kind where you can
Speaker 2: just see for miles totally clear day. You're cruising along
Speaker 2: and you pass a police car parked on the shoulder.
Speaker 2: The officer points a radar gun at you clocks your speed.
Speaker 3: I think most of us have felt that specific spike
Speaker 3: of adrenalist.
Speaker 2: Absolutely. But then a mile down the road there's another
Speaker 2: police officer, also an expert, also holding a state of
Speaker 2: the art, perfectly calibrated radar gun, and he clocks you too. Okay, Now,
Speaker 2: imagine both of these officers are the best in the business.
Speaker 2: Their equipment is flawless, They technically never make mistakes. But
Speaker 2: a week later you get the ticket. The first officer
Speaker 2: says you were going seventy three miles per hour. Right,
Speaker 2: the second officer says you were going sixty seven miles
Speaker 2: per hour.
Speaker 3: That is a very confusing court date.
Speaker 2: Right, who do you believe? They're both experts. They're using
Speaker 2: top gear technology to measure the exact same event, your
Speaker 2: car moving, but the numbers don't match.
Speaker 3: In our world, you'd probably blame it on a faulty battery.
Speaker 2: Or something exactly. But in astrophysics, this isn't about a
Speaker 2: speeding ticket. It's about the speed of the universe itself,
Speaker 2: and this discrepancy it is, and this is not an exaggeration,
Speaker 2: the single biggest headache in modern cosmology.
Speaker 3: You were referring to the hubble tension. Yeah, and you're
Speaker 3: right to frame it as a headache. It's it's really
Speaker 3: more of a crisis. We aren't talking about a car.
Speaker 3: We're talking about the fabric of space.
Speaker 2: Expanding, the universe getting bigger, and.
Speaker 3: We have two very different, very precise ways of measuring
Speaker 3: that exp ancient and for the last decade they have
Speaker 3: just refused to agree.
Speaker 2: It's the cosmic speed trap. And usually when we talk
Speaker 2: about this, the solutions people propose are I mean, they're
Speaker 2: incredibly wild.
Speaker 3: Oh yeah, you get into some really high concept stuff.
Speaker 2: People start talking about dark energy changing over time or
Speaker 2: gravity leaking into other dimensions. But today we're looking at
Speaker 2: a new contender. A new paper just dropped literally today
Speaker 2: February fifteenth, twenty twenty six, that suggests the answer isn't
Speaker 2: some new phantom force. It might be something, well, something
Speaker 2: surprisingly domestic.
Speaker 3: Domestic is an interesting word for it, considering the scale.
Speaker 3: But yes, the fundamental force is certainly something you encounter
Speaker 3: in your kitchen every day.
Speaker 2: We were talking about magnetism. The same force that holds your
Speaker 2: grocery list to the fridge might just be the key
Speaker 2: to fixing the biggest broken number in physics.
Speaker 3: Although to be fair, the magnets we're discussing today are
Speaker 3: a little different than a fridge magnet. We're talking about
Speaker 3: primordial magnetic fields.
Speaker 2: Primordial, so ancient.
Speaker 3: Incredibly ancient. These are invisible fields that were generated mere
Speaker 3: milliseconds after the Big Bang, and we think stretch across
Speaker 3: the entire cosmos.
Speaker 2: So on today's deep dive, we are going to look
Speaker 2: at why the universe's speedometers seems broken. We're going to
Speaker 2: unpack this new paper by researchers Pagosian, Jadamziic and Abel
Speaker 2: we'll find out what a peicogus.
Speaker 3: Is, and why clumping is the technical.
Speaker 2: Term you need to know, and how these invisible magnetic
Speaker 2: webs might be the bridge between two numbers that just
Speaker 2: won't play nice.
Speaker 3: And I think this is the most exciting part. We're
Speaker 3: going to explore how this research doesn't just fix a
Speaker 3: math problem. It potentially opens a window into high energy
Speaker 3: physics that we could never ever hope to replicate in
Speaker 3: a lab on.
Speaker 2: Earth, using the universe as its own particle collider precisely. Okay,
Speaker 2: let's unpack this. We have to start with the problem itself,
Speaker 2: the Hubble tension. I feel like we hear this term
Speaker 2: a lot, but let's really drill down. It all starts
Speaker 2: with Edwin Hubble, doesn't.
Speaker 3: It does. You have to go back to thenineteen twenties,
Speaker 3: before Hubble, the scientific consensus was that the universe was static.
Speaker 3: It was just there, eternal, unchanging.
Speaker 2: The way it is now is the way it's always
Speaker 2: been exactly.
Speaker 3: But Hubble pointed his telescope at the night sky and
Speaker 3: just fundamentally shattered that view of reality. He showed that
Speaker 3: the universe is actually getting bigger. Galaxies are moving away
Speaker 3: from us.
Speaker 2: And it wasn't just random movement, right. There was a
Speaker 2: distinct pattern to it.
Speaker 3: Very clear pattern. He found that the farther away a
Speaker 3: galaxy is the faster it's receding from us. It's the
Speaker 3: classic analogy of dots on.
Speaker 2: A balloon, right as you inflate it.
Speaker 3: As you inflate the balloon, every dot moves away from
Speaker 3: every other dot. But the dots that start further apart
Speaker 3: seem to move away from each other much faster because
Speaker 3: there's just more balloon expanding between them.
Speaker 2: And that rate of recession, that specific relationship between speed
Speaker 2: and distance, that's the Hubble constant.
Speaker 3: Correct, it's the fundamental expansion rate of the cosmos. Now,
Speaker 3: the units we used to measure it are a bit
Speaker 3: of a mouthful kilometers per second per megaparsec.
Speaker 2: Okay, hold on, let's break that down per second. That's easy,
Speaker 2: that's just speed. But per megaparsec. What on Earth is
Speaker 2: a megaparsec?
Speaker 3: Right, Let's build up to it. So, a parsek is
Speaker 3: a unit of distance we use in astronomy. One parsek
Speaker 3: is about three point twenty six light years.
Speaker 2: Which is already an incomprehensibly huge distance.
Speaker 3: Massive, but a megaparsek is one million parsecs.
Speaker 2: So we are talking about a distance of roughly three
Speaker 2: point twenty six million light years.
Speaker 3: That's the one. So we say the Hubble constant is,
Speaker 3: for example, seventy kilometers mpc. It means that for every
Speaker 3: megaparsek you go further out into space.
Speaker 2: A galaxy appears to be moving away from US seventy
Speaker 2: kilometers per second faster.
Speaker 3: Precisely, it's a rate of stretching. If a galaxy is
Speaker 3: one megaparsec away, it's moving its seventy kilometers. If it's
Speaker 3: two away, it's one hundred and forty kilometers. It just
Speaker 3: scales up.
Speaker 2: Okay, got it. So we have the speed limit we're
Speaker 2: trying to measure now. As we said in the intro,
Speaker 2: there are two police officers, two ways to measure this number.
Speaker 2: And this is where the fight starts. Let's call the
Speaker 2: METHODA and method B. Method A is the approach, the
Speaker 2: look out the window method.
Speaker 3: That's a good way to put it. Method A looks
Speaker 3: at the late universe, the universe as it exists now
Speaker 3: or in the relatively recent cosmic past. This is the
Speaker 3: method that follows directly in Edwin Hubble's footsteps. We look
Speaker 3: at galaxies and we measure how fast they're moving away.
Speaker 2: Okay, speed seems easy enough to measure, right, You just
Speaker 2: use red shift.
Speaker 3: Speed is very straightforward. Yeah, we look at the light spectrum.
Speaker 3: If it's shifted toward the red that's moving away, we
Speaker 3: can measure that to an incredibly high precision. The tricky part,
Speaker 3: the absolute nightmare of observational astronomy, is knowing exactly how
Speaker 3: far away the object is. You can't just use a
Speaker 3: tape measure.
Speaker 2: Because in space you completely lose depth perception. A really
Speaker 2: bright thing far away can look exactly the same as
Speaker 2: a dim thing that's close up exactly.
Speaker 3: To solve this, astronomers use something called standard candles.
Speaker 2: I love this analogy. Break it down for us.
Speaker 3: Okay, so imagine you are standing in a long dark
Speaker 3: field at night. You see a light in the distance.
Speaker 3: Is it a dim, little flashlight ten feet away or
Speaker 3: is it a massive search light ten miles away? You
Speaker 3: can't really tell just by looking. But what if you
Speaker 3: knew for a fact that the light was a specific
Speaker 3: brand of sixty watt light.
Speaker 2: Bulb, then you'd know exactly how bright it should be at.
Speaker 3: The source, exactly if you know, it's intrinsic brightness. The wattage,
Speaker 3: you can measure how dim it appears to your eye,
Speaker 3: and then some simple physics tells you exactly how far
Speaker 3: away it must be to look that dimp.
Speaker 2: So we need to find the universe's sixty watt light bulbs.
Speaker 3: And we have them. Our primary standard candles are what
Speaker 3: we call Type EA supernovae exploding stars.
Speaker 2: But why are they all the same brightness? Explosions seem
Speaker 2: like they'd be messy and you know, kind of random.
Speaker 3: They're incredibly messy, but the physics that triggers them is
Speaker 3: remarkably consistent. A type as supernova happens in a binary
Speaker 3: star system. You have a white dwarf, which is a dead,
Speaker 3: super dense star core orbiting a companion star. Okay, the
Speaker 3: white dwarf's gravity is so strong it starts to steal
Speaker 3: matter from its companion. It just siphons it off, getting
Speaker 3: heavier and heavier. But there is a strict fundamental limit
Speaker 3: to how heavy a white.
Speaker 2: Dwarf can get, the Chundra Sicar limit.
Speaker 3: That's the one. It's about one point four times the
Speaker 3: mass of our Sun. Once the white dwarf hits that
Speaker 3: exact limit, it can no longer support its own weight
Speaker 3: against gravity. It collapses and detonates in a thermonuclear explosion.
Speaker 2: And because the mass at the moment of detonation is always.
Speaker 3: The same, the brightness of the explosion is always the same.
Speaker 3: It's nature's standard bomb.
Speaker 2: Wow.
Speaker 3: We also use another kind of star, cephade variables, which
Speaker 3: pulse and the speed of their pulse is directly related
Speaker 3: to their intrinsic brightness. So by combining these measurements using
Speaker 3: the Whole Space telescope, and now that James webistronomers have
Speaker 3: built this very precise cosmic distance ladder.
Speaker 2: They climb that ladder, they check the speedometer, and what
Speaker 2: number do they get?
Speaker 3: Consistently, when looking at the late universe with supernovae and cephades,
Speaker 3: we get a hubble constant of roughly seventy three kilometers
Speaker 3: per second per mega parsek.
Speaker 2: Okay, seventy three. Lock that number in. That's officer number one.
Speaker 2: Now let's look at method B, the indirect approach. This
Speaker 2: is the look at the baby pictures method.
Speaker 3: Yes, this method is completely different. It has nothing to
Speaker 3: do with stars or galaxies. It looks at the cosmic
Speaker 3: microwave background the CMB.
Speaker 2: The after glow of the Big Bang.
Speaker 3: Itself the oldest light in the universe. It was released
Speaker 3: when the cosmos was only about three hundred and eighty
Speaker 3: thousand years old. Before that moment, the universe was this hot, dense,
Speaker 3: opaque fog like a plasma exactly. And when it cooled
Speaker 3: enough that fog cleared and light could finally travel freely.
Speaker 3: That light has been streaming through space for thirteen point
Speaker 3: eight billion years, stretching as the universe expands, until today
Speaker 3: it falls into the microwave part of the spectrum.
Speaker 2: So we have this picture, the snapshot of the baby universe,
Speaker 2: and when we look at it, it's not perfectly smooth,
Speaker 2: is it.
Speaker 3: No, not at all. It has tiny fluctuations, hot spots
Speaker 3: and cold spots that correspond to tiny, tiny ripples in density.
Speaker 2: So we have a map, a map of the infant cosmos.
Speaker 2: What on Earth do you get a speed limit out
Speaker 2: of a static map?
Speaker 3: Ah? Well, we use our best understanding of physics. It's
Speaker 3: called the Standard Model of cosmology. It's this incredible mathematical
Speaker 3: framework for gravity, matter, dark energy, everything. We take the
Speaker 3: data from that baby picture, which was measured with incredible
Speaker 3: precision by the Plank Space telescope and we plug it
Speaker 3: into the model. We basically hit fast forward on a
Speaker 3: giant cosmic simulation.
Speaker 2: You're simulating the entire thirteen point eight billion year history
Speaker 2: of the universe.
Speaker 3: In a sense, yes, we say, okay, if the universe
Speaker 3: started with these specific ingredients and these specific density patterns,
Speaker 3: and if the laws of physics are what we think
Speaker 3: they are, how fast should the universe be expanding today?
Speaker 2: So it's a prediction. It's like looking at a Toddler's
Speaker 2: growth chart and predicting how tall I'll be when they
Speaker 2: turn twenty.
Speaker 3: It's a very very precise prediction based on what we
Speaker 3: believe to be fundamental physics. And when we do that calculation,
Speaker 3: the number we get is not seventy three.
Speaker 2: What is it?
Speaker 3: It is roughly sixty seven kilometers per second per megaparsec.
Speaker 2: Sixty seven versus seventy three. Now I have to play
Speaker 2: Devil's advocate here for a second. To someone on the street,
Speaker 2: that sounds I mean, that sounds pretty close. If I
Speaker 2: guessed a jar had sixty seven jelly beans and it
Speaker 2: turned out to have seventy three, I'd be thrilled with myself.
Speaker 2: Are we sure this matters.
Speaker 3: In many many fields, that would be a celebratory agreement,
Speaker 3: but in precision cosmology it is a disaster. Or a disaster, yes,
Speaker 3: because over the last decade both sides have refined their
Speaker 3: measurements again and again. The air bars, you know, the
Speaker 3: margins of uncertainty, have shrunk to be incredibly small, and
Speaker 3: they do not overlap anymore.
Speaker 2: So it's definitely not just a rounding error.
Speaker 3: The statistical significance is over what we call five sigma
Speaker 3: in science. That means the odds of this being a
Speaker 3: random fluke are less than one in three point five million.
Speaker 3: It is a genuine, undeniable conflict.
Speaker 2: So either the police officer looking at the supernovae is wrong,
Speaker 2: maybe our understanding of cosmic dust is off, or our
Speaker 2: light bulbs aren't as standard as we.
Speaker 3: Think, or the officer looking at the baby picture is.
Speaker 2: Wrong, or the law of the road itself is wrong.
Speaker 2: The physics we're using to connect to the two is broken.
Speaker 3: Exactly. If the measurements are as good as we think
Speaker 3: they are, then our standard model, our entire understanding of
Speaker 3: how the universe evolved, is missing a piece. We get
Speaker 3: a tiebreaker, or a whole new rule of physics.
Speaker 2: And this brings us to the new research this paper
Speaker 2: published today, authored by Pagosian, Jadamziic and Abel. They are
Speaker 2: suggesting the missing piece is magnetism.
Speaker 3: Yes, primordial magnetic fields. And to understand why this is
Speaker 3: such a compelling idea, we actually have to talk about
Speaker 3: another mystery, a totally different problem in astrophysics that seems
Speaker 3: unrelated but might just be the key to the whole thing.
Speaker 2: I love a good subplot. What's the second mystery.
Speaker 3: It's the mystery of where cosmic magnetic fields come from.
Speaker 2: In the first place, I feel like we take magnetism
Speaker 2: for granted. I mean, Earth has a magnetic field. It
Speaker 2: protects us from solar radiation. The Sun has one, We
Speaker 2: have magnets on our fridge. It just seems like it's everywhere.
Speaker 3: It is everywhere, And we understand planetary instellar fee fields
Speaker 3: pretty well. They're generated by dynamos basically churning conducting fluids
Speaker 3: inside the planet or star. The spinning molten iron in
Speaker 3: Earth's core is what creates our field.
Speaker 2: It's like a generator, a natural.
Speaker 3: Generator, yes, But when we look out at the cosmos
Speaker 3: on a grander scale, we see something puzzling. We see
Speaker 3: massive magnetic fields threading through entire galaxies.
Speaker 2: You mean the Milky Way itself is magnetic, very much so, and.
Speaker 3: Not just galaxies. We see magnetic fields in the gas
Speaker 3: between galaxies and clusters, and we think they might even
Speaker 3: exist in the great cosmic voids, the emptiest parts of space.
Speaker 3: The question is where did those come from?
Speaker 2: It's the classic chicken and egg problem, isn't it. Did
Speaker 2: the galaxy form first and then spin up a magnetic field,
Speaker 2: or was a magnetic field there first, maybe helping the
Speaker 2: galaxy to form.
Speaker 3: And here's the problem with the galaxy first idea. It
Speaker 3: is very, very difficult to explain the strength of the
Speaker 3: galactic fields we see today just by spinning them up
Speaker 3: from nothing. You need a seed You need some tiny
Speaker 3: initial bit of magnetism to get the dynamo process started.
Speaker 2: A starter used for the sourdough, if you will.
Speaker 3: That's a perfect analogy. Without a seed field, the math
Speaker 3: just doesn't work to grow the strong fields we observe.
Speaker 3: And this is what leads to the theory of primordial
Speaker 3: magnetic fields. The idea is that magnetism wasn't made by
Speaker 3: stars and galaxies. It arose in the chaos of the
Speaker 3: Big Bang itself.
Speaker 2: So the universe was born with magnetism warven right into
Speaker 2: the fabric of space time.
Speaker 3: That's the theory. It could have been generated during cosmic
Speaker 3: inflation or during one of the big phase transitions in
Speaker 3: the first fraction of a second. But for a long
Speaker 3: time this was just a hypothesis to solve that one problem,
Speaker 3: the seed problem.
Speaker 2: But now these authors Pagosian, Jadamziic, and Abel are asking
Speaker 2: a much bigger question. They're asking, if these primordial fields exist,
Speaker 2: could they do more than just seed galaxies? Could they
Speaker 2: actually fix the Hubble tension exactly?
Speaker 3: They wondered if this one invisible force could solve two
Speaker 3: of the biggest problems in cosmology at the same time,
Speaker 3: the seed problem and the broken speedometer problem.
Speaker 2: Okay, so let's get into the mechanics of this. How
Speaker 2: does a magnetic field, primordial or not, actually change the
Speaker 2: expansion rate of the universe. It feels like those two
Speaker 2: things shouldn't be related at all.
Speaker 3: To understand the mechanism, we have to go back to
Speaker 3: that moment I mentioned earlier, the formation of the cosmic
Speaker 3: microwave background. It's an era of the universe called recombination.
Speaker 2: Right, let's set the scene. The universe is about three
Speaker 2: hundred thousand years old. It's hot, it's dense, it's a soup.
Speaker 3: It's a plasma, and that means it's just too hot
Speaker 3: for atoms to hold together. The electrons, which have a
Speaker 3: negative charge have been ripped away from the protons, which
Speaker 3: have a positive charge. They're just flying around independently.
Speaker 2: And because those electrons are free, they scatter light like crazy,
Speaker 2: like a.
Speaker 3: Thick, impenetrable fog. A photon, a particle of light, can't
Speaker 3: travel more than a tiny distance before it smacks into
Speaker 3: a free electron and gets bounced in a random direction,
Speaker 3: and the universe is opaque.
Speaker 2: But all this time, the universe is expanding, and it's cooling.
Speaker 3: Down right, And eventually it gets cool enough down to
Speaker 3: about three thousand kelvin that the protons can finally capture
Speaker 3: the electrons, they can finally bond. They form the first
Speaker 3: neutral hydrogen atoms.
Speaker 2: They hold hands.
Speaker 3: And this is the crucial part. Neutral hydrogen does not
Speaker 3: scatter light the same way the fog lifts. The universe
Speaker 3: in an instant goes from opaque to transparent. That moment
Speaker 3: is called recombination.
Speaker 2: Okay, so that's the standard story. Now let's throw a
Speaker 2: primordial magnetic field into that hot, foggy soup. What changes.
Speaker 3: Well, magnetic fields interact with charged particles. They push and
Speaker 3: pall on them. It's called the Lorentz force. So now
Speaker 3: imagine you have this plasma. Gravity is trying to pull
Speaker 3: the matter together into little clumps, but the intense pressure
Speaker 3: of all that radiation is trying to push it apart.
Speaker 3: It's a constant tug of war.
Speaker 2: And the magnetic field jumps in as a third player.
Speaker 3: Yes, And what it does is it creates what we
Speaker 3: call baryon clumping. The magnetic fields create these lowize spots
Speaker 3: of pressure and tension in the plasma. They force the
Speaker 3: charged particles, the protons and electrons, to clump together just
Speaker 3: a little bit more than gravity would do on its own.
Speaker 2: So the soup gets lumpy, a little bit lumpier than
Speaker 2: it would have been.
Speaker 3: The soup gets lumpy. And here is the key bit
Speaker 3: of chemistry. Recombination. The process of protons and electrons forming
Speaker 3: those hydrogen atoms happens faster in denser regions.
Speaker 2: Why is that?
Speaker 3: Think of it like a crowded party or a singles mixer.
Speaker 3: If you have one hundred people spread out across a
Speaker 3: huge football field, it might take a long time for
Speaker 3: people to find each other and.
Speaker 2: Pair up right the too far apart.
Speaker 3: But if you crowd all one hundred people into one
Speaker 3: corner of the room, they're constantly bumping into each other,
Speaker 3: They're going to pair up much much faster.
Speaker 2: That is a surprisingly perfect analogy. So by clumping the
Speaker 2: matter together, the magnetic fields make it easier for protons
Speaker 2: to find their electron dance partners exactly.
Speaker 3: And the consequence of that is that recombination as a
Speaker 3: whole finishes sooner, sooner.
Speaker 2: That's the key word, isn't it. The fog lifts earlier
Speaker 2: than our standard model assumes it does.
Speaker 3: The universe becomes transparent earlier. The baby picture is taken
Speaker 3: earlier in cosmic history.
Speaker 2: Okay, I'm following the physics, I think, but I'm still
Speaker 2: missing the final connection to the sixty seven versus seventy
Speaker 2: three number. Why does the fog lifting a bit early
Speaker 2: change the speed reading we get today?
Speaker 3: This is the most technical part, but it's also the
Speaker 3: most elegant. Nora method B the indirect method, the one
Speaker 3: using the baby picture.
Speaker 2: The one that gives us sixty seven.
Speaker 3: Yes, it relies on measuring the size of the patterns
Speaker 3: in the CMB. Those patterns, those hot and cold spots,
Speaker 3: are essentially sound waves that were traveling through the plasma.
Speaker 2: Sound waves in the early universe. That's just wild to
Speaker 2: think about.
Speaker 3: We call them veryan acoustic oscillations. Imagine dropping a stone
Speaker 3: in a pond. Ripples spread out. In the early universe.
Speaker 3: These ripples of pressure traveled through the plasma until the
Speaker 3: moment of recombination. As soon as the universe became transparent,
Speaker 3: the plasma turned into neutral gas, and the sound way
Speaker 3: is basically froze in place.
Speaker 2: So the size of those frozen ripples we see in
Speaker 2: the CMB is determined by how long they had to
Speaker 2: travel before everything froze.
Speaker 3: Exactly the distance they were able to travel is called
Speaker 3: the sound horizon, and for decades it has been our
Speaker 3: standard ruler for the early universe. We know, or at
Speaker 3: least we thought we knew exactly how long that ruler is.
Speaker 2: Ah. But if the magnetic fields made recombination happen sooner, then.
Speaker 3: The sound waves didn't have as much time to travel.
Speaker 2: The ripples are smaller.
Speaker 3: The ruler is shorter.
Speaker 2: Oh wow, okay, let me just restate this and make
Speaker 2: sure I've got it straight. We have been looking at
Speaker 2: these patterns in the sky, these ripples, assuming they were
Speaker 2: made with a ruler that is say twelve inches long, right,
Speaker 2: But because of the magnetic field speeding everything up, the
Speaker 2: ruler was actually only say eleven inches long.
Speaker 3: That's the perfect way to describe it.
Speaker 2: And if you measure a giant room with a ruler
Speaker 2: that you think is the full length, but it's actually
Speaker 2: too short, you're going to get the dimensions of the
Speaker 2: room wrong.
Speaker 3: You will miscalculate the distance to the CNA, and as
Speaker 3: a result, you will miscalculate the expansion rate required to
Speaker 3: get from there to hear. If you correct for the
Speaker 3: magnetic fields, if you shrink the ruler in your calculations
Speaker 3: to its true shorter size, then the inferred hubble constant
Speaker 3: has to shift.
Speaker 2: It goes up.
Speaker 3: It goes up, It moves from sixty seven toward seventy.
Speaker 2: Three boom the magnetic bridge magnetic bridge.
Speaker 3: By accounting for these fields, the baby picture prediction can
Speaker 3: be brought into alignment with the supernova measurement. The two
Speaker 3: police officers are actually agreeing, we just interpreted the second
Speaker 3: officer's data wrong because we didn't know about the magnetic
Speaker 3: interference on the road.
Speaker 2: That is just incredibly elegant. It doesn't require inventing some new,
Speaker 2: weird kind of dark energy. It's just saying, hey, everyone,
Speaker 2: we forgot to account for the magnetism.
Speaker 3: It is elegant. But elegance doesn't automatically mean it's true.
Speaker 3: For that, you need proof, or at the very least,
Speaker 3: you need rigorous simulation. And that is what this new
Speaker 3: paper finally provides.
Speaker 2: Right because up until now this was mostly a back
Speaker 2: of the napkin, wasn't it, or at least the simplified
Speaker 2: one dimensional calculation.
Speaker 3: Correct Back in twenty twenty two of the authors, Karston,
Speaker 3: Jadamzic and Levon Pegosian, first demonstrated this effect was possible
Speaker 3: with a simplified model. But real plasma physics is messy,
Speaker 3: it's turbulent. You can't just approximate three dimensional chaos on
Speaker 3: a piece of paper.
Speaker 2: So what did they do differently? This time?
Speaker 3: They ran the first full three dimensional magnetohydrodynamic MHD simulations
Speaker 3: of the primordial plasma with magnetic fields embedded in it.
Speaker 2: They built a virtual baby universe in a supercomputer.
Speaker 3: A virtual size of one. Yes, they tracked the history
Speaker 3: of hydrogen formation in three D. They didn't just guess
Speaker 3: at the clumping effect. They simulated the fluid dynamics, the
Speaker 3: magnetic stresses, the photon interactions.
Speaker 2: Everything, and what did the computer say?
Speaker 3: The results were compelling. They compared their simulation data against
Speaker 3: the actual observations from the Plank satellite and other cosmological
Speaker 3: data sets, and they found that the real world data
Speaker 3: shows a consistent mild preference for the existence of these
Speaker 3: magnetic fields.
Speaker 2: Mild preference. That sounds a little cautious.
Speaker 3: Scientists are professionally cautious. It's in our DNA. We rely
Speaker 3: on sigma values to quantify this stuff. In statistical terms,
Speaker 3: the preference they found ranges from about one point five
Speaker 3: to three standard deviations or sigma.
Speaker 2: Okay, translate that for us. What does that mean?
Speaker 3: Well, five sigma is the gold standard for a discovery.
Speaker 3: That's when you pop the champagne and start booking your
Speaker 3: flight to Stockholm for the Nobel Prize. Three sigmas generally
Speaker 3: considered strong evidence. So one point five to three is
Speaker 3: a meaningful hint. It's like finding a clear fingerprint at
Speaker 3: the crime scene. It doesn't prove who did it yet,
Speaker 3: maybe there's another explanation for the fingerprint, but it matches
Speaker 3: your main suspect. It tells you that you are definitely
Speaker 3: on the right track.
Speaker 2: So it's not a done deal, but it's a very
Speaker 2: very strong lead exactly.
Speaker 3: But there's a second piece of evidence in the paper that,
Speaker 3: in my opinion, makes it even stronger. It's the specific
Speaker 3: strength of the magnetic fields required.
Speaker 2: This is the peico Gauss thing we mentioned in the intro.
Speaker 3: It is the simulation tells us not just if there
Speaker 3: were fields, but how strong they would need to be
Speaker 3: to solve the hubble tension. The number of the data
Speaker 3: seems to favor is between five and ten piico gause.
Speaker 2: Okay, let's contextualize that a pika gaus. I have a
Speaker 2: magnet on my fridge.
Speaker 3: How many gass is that a typical fridge magnet is
Speaker 3: about fifty to one hundred gaus. The Earth's magnetic field,
Speaker 3: the one that moves your compass needle is about.
Speaker 2: Half a gas, and this is a peico gous.
Speaker 3: Piker gous is one trillionth of a gaus.
Speaker 2: So these are I mean they're unbelievably weak fields, vanishingly weak,
Speaker 2: you would never ever feel them.
Speaker 3: But remember they are pervasive. They span the entire cosmos,
Speaker 3: so the total energy involved across that scale is actually significant.
Speaker 3: But here's the real aha moment. I'm ready remember the
Speaker 3: seed problem, the other great mystery of where galactic magnetic
Speaker 3: fields came from.
Speaker 2: Yes, the sourdok starter for galaxies.
Speaker 3: Right. Well, astrophysicists have calculated, independently, in a totally separate
Speaker 3: line of research, completely unrelated to the Hubble tension, how
Speaker 3: strong a seed field would need to be in the
Speaker 3: early universe to eventually grow through dynamo effects into the
Speaker 3: galactic fields we see today. And let me guess the
Speaker 3: required strength they calculated is roughly five to ten picogaus.
Speaker 2: No way, yes, way, it's the same number.
Speaker 3: The Goldilocks strength needed to fix the Hubble tension. Is
Speaker 3: the exact same strength needed to explain why galaxies are
Speaker 3: magnetic in the first place.
Speaker 2: That feels like more than a coincidence. That feels like
Speaker 2: a major puzzle piece just clicking perfectly into place.
Speaker 3: It fits both locks with a single key. That is
Speaker 3: what makes this paper so exciting to the community. Nature
Speaker 3: tends to be efficient. It seems highly unlikely that the
Speaker 3: universe would have one field to solve the Hubble tension
Speaker 3: and a totally different, unrelated field to seed galaxies when
Speaker 3: one field can do both jobs perfectly.
Speaker 2: So if this turns out to be true, it really
Speaker 2: does rewrite the history of the early universe.
Speaker 3: It absolutely does. It means that magnetism was a fundamental
Speaker 3: player from the very very beginning. We usually think of
Speaker 3: gravity as the main sculptor of the universe, but this
Speaker 3: suggests magnetism was holding the chisel too.
Speaker 2: And that leads to some pretty profound implications. You mentioned
Speaker 2: at the start that this could be a window into
Speaker 2: physics we can't do on Earth.
Speaker 3: Well, think about where these fields would have to come from.
Speaker 3: We said primordial. That means they were generated in the
Speaker 3: first fraction of a second after the Big Bang.
Speaker 2: During the era of inflation, or maybe the electro weak
Speaker 2: phase transition.
Speaker 3: Precisely, these are moments when the universe was incredibly hot
Speaker 3: and dense, energy levels that are billions or even trillions
Speaker 3: of times higher than anything we could generate in the
Speaker 3: large Hadron collider.
Speaker 2: We just can't build a machine that big or that powerful.
Speaker 3: No but the universe was that machine. And if we
Speaker 3: can confirm these magnetic fields exist, and if we can
Speaker 3: measure their properties precisely, their strength, their shape, they act
Speaker 3: as fossils from that era. They are like a diary
Speaker 3: entry from the moment of creation.
Speaker 2: That is just mind blowing. We're analyzing a glitch and
Speaker 2: a cosmic spitamen to try and read a diary from
Speaker 2: the first Peko second of the Big Bang.
Speaker 3: That is the beauty and the madness of cosmology. Everything
Speaker 3: is connected. You pull on one tiny thread here, a
Speaker 3: small discrepancy and expansion rates, and you find yourself unraveling
Speaker 3: the fundamental physics of the first second of time.
Speaker 2: So what's the next step. How do we go from
Speaker 2: a meaningful hint to a confirmed discovery. How do we
Speaker 2: get from three sigma to that five sigma gold standard?
Speaker 3: We need better maps. The paper notes that this theory
Speaker 3: survives the most detailed test available today, but available today
Speaker 3: is the key phrase there.
Speaker 2: We need better eyes on the sky.
Speaker 3: We need to look at the cosmic microwave background with
Speaker 3: even higher precision, and specifically, we need to look for
Speaker 3: very particular patterns in the polarization of that ancient.
Speaker 2: Light polarization is the direction the light waves are sort
Speaker 2: of wiggling correct.
Speaker 3: And magnetic field should leave a specific twisting signature, a
Speaker 3: kind of fingerprint on the polarization of the CMB. If
Speaker 3: the fields are there, they should have twisted the light
Speaker 3: in a very predictable way we could look for.
Speaker 2: Are there missions planned to do that?
Speaker 3: There are. There's the Simon's Observatory being built right now
Speaker 3: in the Atacama Desert in Chile. There's a satellite mission
Speaker 3: from Japan called light Bird, and the huge CMBs four project.
Speaker 3: These are all upcoming experiments designed specifically to map the
Speaker 3: CMB polarization with unprecedented sensitivity.
Speaker 2: And if they see that specific twist.
Speaker 3: If they see that signature, then the Hubble tension is
Speaker 3: likely resolved. We can say with confidence the universe is
Speaker 3: expanding at seventy three kilometers mpc. And the reason we
Speaker 3: thought otherwise is because we forgot to include the magnetism
Speaker 3: in our baby pictures.
Speaker 2: And the standard model of cosmology.
Speaker 3: It survives, but it gets an important update. It's not broken,
Speaker 3: it was just incomplete. We add primordial magnetism to the
Speaker 3: official Recipe Book of the Universe.
Speaker 2: It's amazing how science works like that. We hate it
Speaker 2: when the numbers don't add up. It's frustrating, But that frustration,
Speaker 2: that tension is actually where the discovery lives.
Speaker 3: Precisely, if the numbers had matched perfectly ten years ago go,
Speaker 3: if both methods gave us a clean seven eight, we
Speaker 3: never would have looked this hard for these magnetic fields.
Speaker 3: We might have missed this entire layer of reality. The
Speaker 3: tension is what forced the innovation.
Speaker 2: The grit in the oyster makes the pearl a.
Speaker 3: Poetic way to put it, but yes, completely accurate.
Speaker 2: So to recap our journey today, we started with a
Speaker 2: broken speedometer, two trusted methods giving us different answers for
Speaker 2: the expansion of the universe, A sixty seven versus a
Speaker 2: seventy three.
Speaker 3: We introduced a suspect, Yeah, these weak, invisible, ancient primordial
Speaker 3: magnetic fields.
Speaker 2: We then looked at the mechanism. These fields made the
Speaker 2: plasma in the early universe a little bit clumpy, which
Speaker 2: caused neutral hydrogen to form sooner than.
Speaker 3: We thought, which in turn shrinks the sound horizon our
Speaker 3: cosmic ruler, and when we use the correct shorter ruler,
Speaker 3: our measurement of the expansion rate shifts up, moving from
Speaker 3: sixty seven to match the seventy three from the local observations.
Speaker 2: And finally we saw that the new three D simulations
Speaker 2: back this all up, showing that the specifics strength of
Speaker 2: magnetism needed to fix the tension those five to ten
Speaker 2: picogaus is the exact same strength needed to solve a
Speaker 2: totally different problem, why galaxies are magnetic at all.
Speaker 3: A single unifying solution to two major cosmic puzzles.
Speaker 2: It really makes you think about the invisible scaffolding of
Speaker 2: the universe, doesn't it. We look up at the stars
Speaker 2: and we think that's it, that's the universe. But there
Speaker 2: are these vast, invisible webs of force, magnetism, gravity, dark
Speaker 2: matter that are really running the show.
Speaker 3: We are just seeing the foam on top of the ocean.
Speaker 3: The deep currents underneath are what dictate where all that
Speaker 3: foam goes. This paper suggests that magnetism is one of
Speaker 3: those deep, powerful currents that has been pushing and pulling
Speaker 3: on the cosmos since the very beginning.
Speaker 2: It's a powerful reminder that the universe is a connected system.
Speaker 2: You can't tweak the beginning without fundamentally changing the end.
Speaker 3: And you can't fully understand the end without knowing exactly
Speaker 3: what happened at the beginning.
Speaker 2: I want to leave our listeners with a final thought. Then,
Speaker 2: we've been talking about magnetic fields today, something we usually
Speaker 2: associate with you fridge magnets, and compasses. But if these
Speaker 2: fields really did shape the early universe, if they really
Speaker 2: did alter the timeline of creation, what other invisible forces
Speaker 2: might be out there pushing and pulling on the cosmos
Speaker 2: that we haven't even thought to put into our equations yet.
Speaker 3: That is the ultimate question, isn't it. If we could
Speaker 3: miss something as fundamental as magnetism for this long, what
Speaker 3: else are we missing? Is our standard model incomplete? In
Speaker 3: other ways? Are there other fossils from the Big Bang
Speaker 3: hiding in plain sight, in the data, just waiting for
Speaker 3: someone to ask the right question.
Speaker 2: Something to wonder about next time you look up at
Speaker 2: the night sky, or I suppose next time you look
Speaker 2: at your refrigerator. Indeed, thanks for joining us on this
Speaker 2: deep dive into the magnetic universe. Keep looking up and
Speaker 2: keep wondering.
Speaker 3: MS