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: Picture this, Okay, you are standing out in the absolute
Speaker 2: dead of night, pitch black, pitch black. You are looking
Speaker 2: up at the sky and you're waiting for something, anything,
Speaker 2: to happen, right, and then bam, a flash exactly a flash,
Speaker 2: a cosmic firework.
Speaker 3: Going off, but not just a normal one.
Speaker 2: Right, because you don't just see one explosion. You see
Speaker 2: the exact same explosion, the exact same burst of light,
Speaker 2: happening in five different places in the.
Speaker 3: Sky at the exact same moment, Yes, at.
Speaker 2: The exact same moment, and they are arranged in this
Speaker 2: perfect geometric cross.
Speaker 3: Pattern surrounding those two faint glowing orbs right in the center.
Speaker 2: It looks like a glitch, like the rendering software for
Speaker 2: the universe just stuttered and copied and pasted a star
Speaker 2: five times.
Speaker 3: It is a really striking visual. I mean, it completely
Speaker 3: challenges your intuition about how reality is supposed to work.
Speaker 3: It really does, because we are wired to believe that
Speaker 3: one object occupies one location in space.
Speaker 2: Right, basic physics for everyday life.
Speaker 3: Exactly, So when you see five of them, your brain
Speaker 3: instantly wants to reject it.
Speaker 2: It feels like science fiction.
Speaker 3: It does. But we aren't talking about sci fi today, No,
Speaker 3: we are not.
Speaker 2: We are talking about a very real, very hard data
Speaker 2: discovery that dropped in February twenty twenty six.
Speaker 3: A massive discovery. Right.
Speaker 2: This is the story of Sen Winni or Sen twenty
Speaker 2: twenty five Winni. If we want to use the formal catalog.
Speaker 3: Mam Winni is definitely easier to say.
Speaker 2: Much easier. It's a super nova that astronomers caught in
Speaker 2: the act.
Speaker 3: Ten billion light years away ten.
Speaker 2: Billion, and it's appearing has five distinct images.
Speaker 3: And while the image itself is beautiful, I mean, it
Speaker 3: really is a cosmic firework, just like the researchers called it.
Speaker 3: The esthetics are just the bait they draw you in, exactly.
Speaker 1: Yeah.
Speaker 3: The real hook here is what this specific glitch in
Speaker 3: the sky allows us to do.
Speaker 2: Because It's not just a stamp collecting exercise for astronomers.
Speaker 3: Not at all. This might actually be the solution to
Speaker 3: the biggest headache in modern physics.
Speaker 2: We are talking about the Hubble tension.
Speaker 3: The Hubble tension, the absolute crisis in cosmology right now.
Speaker 2: It's basically a one hundred year old argument that has
Speaker 2: split the physics community right down the middle.
Speaker 3: I feel like argument is almost putting it lightly at
Speaker 3: this point, more of a standoff. Definitely a standoff. Yeah.
Speaker 3: We have two very precise ways to measure how fast
Speaker 3: the universe is.
Speaker 2: Expanding, and they are giving us two completely different answers.
Speaker 3: Right, and they cannot both be right.
Speaker 2: If one side is right, the other is.
Speaker 3: Wrong, or even more excitingly, both are right in their
Speaker 3: own way, and our fundamental understanding of gravity or the
Speaker 3: early universe.
Speaker 2: Is just fly, which would be huge.
Speaker 3: It will re write the textbooks. We have been waiting
Speaker 3: for a tie breaker for years.
Speaker 2: A third way, Yes.
Speaker 3: A third way to measure the cosmos that doesn't rely
Speaker 3: on all the baggage of the previous.
Speaker 2: Methods, And that is exactly what sn winny it represents.
Speaker 2: It's the independent arbiter.
Speaker 3: It really is the Goldilock scenario. It's this one in
Speaker 3: a million alignment that lets us bypass the messy assumption
Speaker 3: heavy calculations we have been stuck with.
Speaker 2: So in this exploration today, we are going to look
Speaker 2: at how we found it, the insane technology required to
Speaker 2: actually see it, and the geometry, actual time delay physics. Right,
Speaker 2: the physics that turns a pretty picture into a literal
Speaker 2: ruler for the universe.
Speaker 3: It's fascinating.
Speaker 2: Let's get into the weeds. Then we need to start
Speaker 2: with the object itself. Sn winny.
Speaker 3: Right.
Speaker 2: We mentioned it's a supernova, but you don't get visible
Speaker 2: explosions ten billion light years away from just run of
Speaker 2: the mill dying stars, do you, No.
Speaker 3: You don't. This has to be something mass.
Speaker 2: So what are we actually looking at here?
Speaker 3: Well, a standard type EA supernova, which we use a
Speaker 3: lot in cosmology, is very.
Speaker 2: Bright, right, they are standard candles exactly.
Speaker 3: It can outshine its entire host galaxy for.
Speaker 2: A few weeks, which is wild to think about.
Speaker 3: It is, but at a red shift of two, which
Speaker 3: is the distance we are talking about here, roughly ten
Speaker 3: billion light years, a normal supernova would be incredibly.
Speaker 2: Faint, barely a pixel on a screen.
Speaker 3: Barely even that, But s and Winnie is a super
Speaker 3: luminous supernova super lumina.
Speaker 2: I always love how literal astronomers are with their naming conventions,
Speaker 2: very practical. It's like, well, it's a supernova, but it's super.
Speaker 3: It does exactly what it says on the tin.
Speaker 2: Right, So how much brighter are we talking?
Speaker 3: These are rare events. They are ten to one hundred
Speaker 3: times brighter than a standard supernova. Wow, we are talking
Speaker 3: about a release of energy that is genuinely difficult to
Speaker 3: even comprehend.
Speaker 2: So we have this absolute beacon of light going off
Speaker 2: in the distant universe. Right, But the light isn't traveling
Speaker 2: to to us in a straight line.
Speaker 3: No, it's not. And this is where Einstein enters.
Speaker 2: The chat general relativity exactly.
Speaker 3: General relativity tells us that mass curves space.
Speaker 2: Right, if you put a massive object in the fabric
Speaker 2: of space time, it creates a divot. Oh wow, the
Speaker 2: classic bowling ball on a trampoline analogy.
Speaker 3: It's classic for a reason. Now, imagine rolling a marble,
Speaker 3: which represents a photon of light across that trampoline. Okay,
Speaker 3: if it goes near the bowling ball, it's path curves.
Speaker 2: It doesn't go straight right, it.
Speaker 3: Follows the curve of the trampoline. Now scale that up
Speaker 3: to the cosmos. We have SN Whinni exploding way in
Speaker 3: the background.
Speaker 2: Ten billion light years back.
Speaker 3: Yes, and directly between us and that explosion, sitting right
Speaker 3: in the line of sight are two galaxies.
Speaker 2: These are the Lens galaxy.
Speaker 3: It's correct. The gravity of these foreground galaxies is bending
Speaker 3: space so severely that the light from SN Winni has
Speaker 3: no choice but to curve around.
Speaker 2: Them like a funhouse mirror.
Speaker 3: Exactly like a funhouse mirror. But here is the key.
Speaker 3: The alignment is so perfect. The light doesn't just curve
Speaker 3: one way.
Speaker 2: It splits. It splits, so it's taking multiple routes simultaneously.
Speaker 3: Think of it like a river flowing around a large island.
Speaker 2: Okay, I can picture that.
Speaker 3: The water splits, goes around both sides of the island,
Speaker 3: and then meets up again downstream.
Speaker 2: So the light from the supernova streams around these galaxies, taking.
Speaker 3: Different paths through the curved space.
Speaker 2: Time, and those paths converge.
Speaker 3: At Earth exactly so when our telescope points at that
Speaker 3: exact spot, it catches photons arriving from the left path.
Speaker 2: And photons arriving from the right.
Speaker 3: Path, photons coming over the top, and so on.
Speaker 2: And our brain or I guess the PERMERA sensor interprets
Speaker 2: those different arrival angles as completely different objects.
Speaker 3: Yes, we see five distinct images of the exact same event.
Speaker 3: This is what we call strong gravitational lensing.
Speaker 2: Now, we have seen lensing before, right, we have. The
Speaker 2: Einstein cross is a famous one where a quasar is
Speaker 2: split into four images.
Speaker 3: Right, that's a very well known example.
Speaker 2: So what makes sn WINNI so special? Why are researchers
Speaker 2: so incredibly excited about this one specifically?
Speaker 3: That is a great question. You are right. We have
Speaker 3: seen lensed quoasars.
Speaker 2: Quasars being those supermassive black holes actively feeding in the
Speaker 2: centers of galaxies.
Speaker 3: Exactly. They are incredibly bright and they stay bright.
Speaker 2: They are permanent fixtures.
Speaker 3: Basically, Yes, they flicker a bit, they have some variability,
Speaker 3: but they are always on.
Speaker 2: Meaning they don't have a distinct start and end date.
Speaker 3: Right. But a supernova is a transient event.
Speaker 2: It explodes, it brightens, it hits a peak, and.
Speaker 3: Then it fades away. It has a very distinct light curve.
Speaker 2: And that timing is crucial for what we want to
Speaker 2: do here, isn't it? It is everything, because if we
Speaker 2: want to measure the universe, we need a.
Speaker 3: Clock and go. We need a clock, and the supernova
Speaker 3: is the absolute perfect cosmic stop watch.
Speaker 2: That makes sense.
Speaker 3: But before we get into the how of the measurement,
Speaker 3: we really have to appreciate the.
Speaker 2: Odds here, right, the rarity.
Speaker 3: Sherry Suyu, who is a heavy hitter in this field
Speaker 3: over at the Technical University of Munich and the Max
Speaker 3: Planck Institute, she quantified the probability of this alignment.
Speaker 2: I read that quote she said, finding this is quote
Speaker 2: lower than one in a million.
Speaker 3: And that is not hyperbole really truly. You need a
Speaker 3: superluminous supernova, which is already incredibly rare on its own right.
Speaker 3: You need it to happen at the exact right distance
Speaker 3: from us. You need it to happen directly behind a
Speaker 3: galaxy that is massive enough and compact enough to act as.
Speaker 2: A lens, and you need to actually be looking at
Speaker 2: it at the right time exactly, so it's not just
Speaker 2: something you stumble upon while casually standing the.
Speaker 3: Sky, not at all. You have to actively hunt for it.
Speaker 2: And this was a long hunt, a.
Speaker 3: Six year hunt. The team, including researchers like Stefan Taalbenberger,
Speaker 3: spent years just compiling a list of potential lenses.
Speaker 2: So they basically mapped out the sky and said, okay,
Speaker 2: here are a bunch of galaxies that could act as
Speaker 2: lenses if something happens to explode behind them.
Speaker 3: That's exactly what they did, and then they waited.
Speaker 2: It's like setting up a bunch of camera traps in
Speaker 2: the jungle and just waiting for a very specific, very
Speaker 2: rare albino tiger to.
Speaker 3: Walk by and not just walk by, but explode while
Speaker 3: walking by. Right, They were monitoring these candidates constantly looking
Speaker 3: for a sudden blip.
Speaker 2: As light, and then in August twenty twenty five, the
Speaker 2: alert finally went off.
Speaker 3: It did this wiki transient facility picked it up.
Speaker 2: That's the wide field survey telescope that scans the sky
Speaker 2: every night.
Speaker 3: Right, Yes, it picked up a transient event.
Speaker 2: So when they pointed the big guns at it, did
Speaker 2: they see the five images immediately?
Speaker 3: Well not immediately, oh really, no, they saw that it
Speaker 3: was a candidate, it was a blip. But to really
Speaker 3: confirm the five images and see the actual structure, they
Speaker 3: needed the heavy artillery.
Speaker 2: They needed the large binocular telescope exactly, the LBT. That
Speaker 2: telescope is an Arizona right on Mount Graham.
Speaker 3: Yes it is, and it is an absolute beast of
Speaker 3: an instrument.
Speaker 2: It has two huge mirrors.
Speaker 3: Two eight point four meter diameter mirrors sitting side by side.
Speaker 2: But even with a telescope that massive, you still have
Speaker 2: a huge.
Speaker 3: Problem to deal with the atmosphere.
Speaker 2: Right The atmosphere is the enemy of high resolution astronomy,
Speaker 2: it really is.
Speaker 3: It's turbulent. It's what makes stars.
Speaker 2: Twinkle, and that twinkling smears out the fine detail.
Speaker 3: Exactly. If you are trying to resolve five tiny points
Speaker 3: of light that are huddled really close together ten billion
Speaker 3: light years.
Speaker 2: Away, the atmosphere just turns them into a fuzzy blob.
Speaker 3: And you cannot do precision cosmology with a blob.
Speaker 2: So they used adeptive optics they did. I always find
Speaker 2: this technology completely mind blowing. Can you break down how
Speaker 2: that actually works for us? Because it sounds like literal magic,
Speaker 2: like we just unqwinkle the stars.
Speaker 3: It is effectively magic, but it is deeply rooted in physics.
Speaker 2: Okay, walk me through it.
Speaker 3: They shoot a laser, usually a powerful sodium laser high
Speaker 3: up into the atmosphere. How high maybe ninety kilometers up
Speaker 3: into the mesosphere. Okay, this laser excites the sodium atoms
Speaker 3: up there and creates a glowing artificial star, a fake star,
Speaker 3: exactly a guide star.
Speaker 2: So they have a perfect reference point. They know exactly
Speaker 2: what that laser spot should look like.
Speaker 3: They know it should be a perfect sharp point of light. Right.
Speaker 3: But because of the atmospheric turbulence, the wind, the heat rising,
Speaker 3: the different pockets of air, the image of that laser
Speaker 3: dot gets distorted on its way back down.
Speaker 2: It dances around.
Speaker 3: Yes, and the telescope monitors that exact dissortion thousands of
Speaker 3: times per second, and then it corrects it in real time.
Speaker 2: That is insane.
Speaker 3: The telescope actually has a secondary mirror that is.
Speaker 2: Deformable, meaning it literally changes shape.
Speaker 3: Yes, it has hundreds of tiny little actuators behind it
Speaker 3: that physically push and pull the thin glass.
Speaker 2: Of the mirror, so it ripples the mirror.
Speaker 3: It ripples it in the exact opposite pattern of the
Speaker 3: atmospheric distortion.
Speaker 2: So if the atmosphere zigs the mirror zag.
Speaker 3: Precisely, it actively cancels out.
Speaker 2: The blur that is brilliant engineering.
Speaker 3: The result is that you get an image almost as
Speaker 3: sharp as if you were in space.
Speaker 2: Like Hubble or jwst right.
Speaker 3: But with the massive light gathering power of an eight
Speaker 3: meter ground telescope.
Speaker 2: That is how they got the first high resolution color
Speaker 2: image of s N WINNI.
Speaker 3: Yes, it revealed those five bluish points of light perfectly
Speaker 3: arranged around the two red or four ground galaxies.
Speaker 2: It's an incredible technical achievement just to get the picture
Speaker 2: it is, but that image is what allows us to
Speaker 2: actually start doing the math.
Speaker 3: The real work begins after the photo is taken.
Speaker 2: So we have the object, we have the pristine data.
Speaker 2: Now let's talk about the actual problem.
Speaker 3: This is supposed to solve, the big one.
Speaker 2: We mentioned the Hubble tension earlier, and I want to
Speaker 2: drill down into this because I think a lot of
Speaker 2: people hear, oh, the universe is expanding, and they just think, okay, cool,
Speaker 2: science knows.
Speaker 3: That, right. They think it's settled.
Speaker 2: They don't realize that we are actually in a massive
Speaker 2: crisis regarding how fast it's expanding.
Speaker 3: It is arguably the most significant disagreement in fundamental physics today.
Speaker 2: It's not just a rounding error, is it?
Speaker 3: No, it is a glaring contradiction.
Speaker 2: Let's define the terms for everyone, the hubble constant or
Speaker 2: h not. It's essentially the speed.
Speaker 3: Limit of the expand it's the rate of expansion. It
Speaker 3: tells us how fast a galaxy is receding from US,
Speaker 3: based entirely on its distance.
Speaker 2: Okay, and the units for this are notorious.
Speaker 3: Kilometers per second per megaparsec, which is a complete mouthful,
Speaker 3: it is, but it makes sense when you break it down.
Speaker 2: Let's do that.
Speaker 3: Basically, it means for every megaparsec you go out into spaces.
Speaker 2: And a megaparsec is about three point two six million
Speaker 2: light years, right exactly, So for.
Speaker 3: Every three point twenty six million light years you travel outward,
Speaker 3: how much faster is space itself expanding?
Speaker 2: So if the number is seventy, for example, then.
Speaker 3: A galaxy one megaparsec away is moving away from US
Speaker 3: at seventy kilometers per second.
Speaker 2: In a galaxy ten megaparsex.
Speaker 3: Away is moving away at seven hundred kilometers per second.
Speaker 2: Simple enough concept. Measure the speed, measure the distance, divide
Speaker 2: the two, and you.
Speaker 3: Have your number in theory.
Speaker 2: Why is this so hard in practice?
Speaker 3: Because measuring true distance in space is incredibly, incredibly difficult.
Speaker 2: We don't exactly have a cosmic tape measure.
Speaker 3: We don't. We have two main methods that we use,
Speaker 3: and they represent two completely different philosophies of looking at the.
Speaker 2: Universe, the ladder and the CMBA.
Speaker 3: Right, Let's start with the ladder, the cosmic distance ladder. Yes,
Speaker 3: this is the local universe method.
Speaker 2: It's empirical, meaning it relies on direct observation of things
Speaker 2: relatively nearby.
Speaker 3: Exactly. You start with objects close to Earth, where you
Speaker 3: can measure distance using simple geometry like parallax. Yes, exactly,
Speaker 3: like how your eyes jeedge distance. You mentioned the distance
Speaker 3: to a nearby star. Then you find a specific type
Speaker 3: of star called a syphiid variable in that same star cluster.
Speaker 2: Cipheids are what we call standard candles.
Speaker 3: Right. Yes, they physically pulse, they get brighter and dimmer,
Speaker 3: and their pulse rate is directly tied to their intrinsic brightness.
Speaker 2: So if you know how fast it pulses, you know
Speaker 2: exactly how bright it truly is.
Speaker 3: And if you know how bright it truly is, and
Speaker 3: you measure how dim it appears to us here.
Speaker 2: On Earth, you know exactly how far away it must
Speaker 2: be exactly.
Speaker 3: It's the inverse square law of light.
Speaker 2: So you use the really close sephades to calibrate the
Speaker 2: slightly further sephades.
Speaker 3: Yes, And then you look for cephiedes in galaxies that
Speaker 3: also happen to have Type E a supernova in them.
Speaker 3: Augh use the sefees to calibrate the brightness of the supernova.
Speaker 2: And supernova are much brighter so you can see them
Speaker 2: much further away exactly.
Speaker 3: Then you use those supernovae to measure distances to galaxies
Speaker 3: way way out in marble.
Speaker 2: Flow, where the expansion of the universe is the dominant
Speaker 2: force pushing them away.
Speaker 3: Right. So it's a ladder rung by rung by run,
Speaker 3: and that is its greatest.
Speaker 2: Weakness because it has systematics.
Speaker 3: Right, If your very first rung is slightly off.
Speaker 2: Because of dust extinction making the stars look just a
Speaker 2: tiny bit dimmer than they actually are.
Speaker 3: Or metallicity effects changing the internal physics of the sephids.
Speaker 2: That tiny error propagates up the entire ladder.
Speaker 3: It compounds at every single step. It's like a game
Speaker 3: of telephone.
Speaker 2: So what number does the latter team actually get?
Speaker 3: The team led by Adam Reese and others. Using this
Speaker 3: method consistently gets a number around seventy three or seventy four.
Speaker 2: Seventy three kilometers per second per megaparsec.
Speaker 3: Yes, they have refined this over and over for decades.
Speaker 3: They are incredibly confident in that number.
Speaker 2: Okay, so hold on to seventy three ish. Now, let's
Speaker 2: look at method two.
Speaker 3: The cosmic microwave background the CMB. This is the echo
Speaker 3: of the Big Bang itself, right.
Speaker 2: It's the oldest light we can possibly see.
Speaker 3: It's the ambient radiation left over from when the universe
Speaker 3: was only three hundred and eighty thousand years.
Speaker 2: Old, basically a baby picture of the cosmos exactly.
Speaker 3: The Plank satellite mapped this radiation with truly insane precision.
Speaker 3: We look at the tiny microscopic temperature fluctuations in that
Speaker 3: early universe.
Speaker 2: The little hot and cold spots in the map.
Speaker 3: Yes, but here's the catch with this method.
Speaker 2: There's always a catch.
Speaker 3: The CMB does not directly measure the expansion rate today.
Speaker 2: Because it's a picture from thirteen point eight billion years ago.
Speaker 3: Right. To get the expansion rate for today, we have
Speaker 3: to use a mathematical model.
Speaker 2: We have to plug that baby picture into our standard model.
Speaker 3: Of cosmology lamed a CDM.
Speaker 2: And we just run the clock forward.
Speaker 3: We simulate thirteen point eight billion years of cosmic evolution
Speaker 3: to predict what the expansion rate should be right now.
Speaker 2: So one team measures the universe exactly as it is locally,
Speaker 2: and the other team predicts what it ought to be
Speaker 2: based on exactly how it started.
Speaker 3: That is a perfect way to put it. And when
Speaker 3: the CMB team does that massive calculation, they get sixty
Speaker 3: seven point four.
Speaker 2: Sixty seven point four, So we have sixty seven on
Speaker 2: one side and seventy three on the other.
Speaker 3: And the airbars are tiny now.
Speaker 2: They don't overlap at all.
Speaker 3: Not even close. The sixty seven team says, look, we
Speaker 3: are right plus or minus point five.
Speaker 2: And the seventy three team says, no, we are right
Speaker 2: plus or minus one. So we have a five sigma discrepancy,
Speaker 2: which in physics is the absolute gold standard for saying
Speaker 2: this is not a fluke.
Speaker 3: It means the probability of this just being a statistical
Speaker 3: accident is basically one in millions.
Speaker 2: So someone is wrong either.
Speaker 3: The latter people have a systematic air they just cannot find.
Speaker 3: Maybe they really don't understand dust, or they don't understand
Speaker 3: cephaides as well as they think, or the CMB people
Speaker 3: are using a broken.
Speaker 2: Model which implies new physics. Yes, it means maybe the
Speaker 2: universe extanded differently in the past. Maybe dark energy isn't
Speaker 2: a constant force.
Speaker 3: That is the incredibly tantalizing possibility.
Speaker 2: But we can't claim new physics until we definitively rule out.
Speaker 3: The errors exactly. We need a tiebreaker.
Speaker 2: We need a method that is totally independent of cephaides
Speaker 2: and totally independent of the CMB.
Speaker 3: Model, completely fresh look.
Speaker 2: And this brings us right back to S. N.
Speaker 3: Winny time delay cosmography.
Speaker 2: This is the third way. Yes, so how does it
Speaker 2: actually work? How on Earth do we get a hubble
Speaker 2: constant out of five blips of light?
Speaker 3: It all comes down to geometry in time. Okay, remember
Speaker 3: those five images of the supernova.
Speaker 2: The ones bent around the galaxy right.
Speaker 3: The light in each of those images took a completely
Speaker 3: different physical path through space to get here.
Speaker 2: Half a path B, palf C, and so on.
Speaker 3: Those paths have different lengths.
Speaker 2: It's like driving from your house.
Speaker 3: To the office, perfect analogy.
Speaker 2: You can take the highway, which is maybe a straight shot, or.
Speaker 3: You can take the back roads which wind around.
Speaker 2: The highway might be ten miles and back roads might
Speaker 2: be twelve miles.
Speaker 3: And if you drive at the exact same speed on
Speaker 3: both routes, you arrive at different times.
Speaker 2: And light always drives at the same speed constantly the
Speaker 2: speed limit of the universe. So the light taking the
Speaker 2: shorter path through the curved space arrives here first.
Speaker 3: And the light taking the longer path arrives later.
Speaker 2: This means we don't actually see the five explosions simultaneously.
Speaker 3: No, we see them in a sequence.
Speaker 2: So image one brightens up in the sky, then maybe
Speaker 2: a few days or weeks later, Image two brightens up.
Speaker 3: Then Image three, and so on.
Speaker 2: We are literally watching a cosmic replay exactly.
Speaker 3: We measure those time delays. We could say Image A
Speaker 3: arrived exactly twenty days before Image B.
Speaker 2: That time delay is a hard observable data point.
Speaker 3: It is.
Speaker 2: But wait, it's not just the physical length of the
Speaker 2: path that matters, right right, There is also the Shapiro
Speaker 2: delay to consider. We have to get a little deeper
Speaker 2: into the general relativity of it all.
Speaker 3: You are absolutely right to bring that up. It's actually
Speaker 3: two effects combined into one delay.
Speaker 2: Okay.
Speaker 3: One is the geometric delay. Literally, path A is a
Speaker 3: longer physical distance than pass B.
Speaker 2: Got it.
Speaker 3: The other is the gravitational time dilation.
Speaker 2: This is the interstellar effect. Time runs slower when you
Speaker 2: are deeper in a gravity well.
Speaker 3: Exactly, the light that passes closer to the dense core
Speaker 3: of the Lens galaxy is passing through a much deeper
Speaker 3: gravitational potential, so it.
Speaker 2: Has to physically climb out of that gravity well, and.
Speaker 3: That struggle slows it down relative to the light that
Speaker 3: passed further out where the gravity is weaker.
Speaker 2: So the total time delay is a combination of how
Speaker 2: far did I drive and how much traffic or gravity
Speaker 2: did I get stuck in.
Speaker 3: That is a perfect way to visualize it. Thanks, And
Speaker 3: here is the absolute beauty of this method. Both of
Speaker 3: those things, the physical distance and the depth of the
Speaker 3: gravitational potential, they directly depend on the overall scale of
Speaker 3: the universe.
Speaker 2: They depend on the vast distances between Earth, the Lens galaxy,
Speaker 2: and the supernova.
Speaker 3: And those absolute distances depend directly on the Hubble constant.
Speaker 2: Right, Because the Hubble constant dictates the size and scale
Speaker 2: of the expanding universe.
Speaker 3: Yes. So the core equation is basically time delay equals
Speaker 3: the time delay distance multiplied by the potential difference. Okay,
Speaker 3: we measure the time delay directly with our telescope by
Speaker 3: watching the flashes. Check. We model the potential difference using
Speaker 3: the mass of the Lens galaxy. The only variable left
Speaker 3: in the equation is the time delay distance. We solve
Speaker 3: for that, and boom, we extract the Hubble constant.
Speaker 2: In one single step. One step, no distance ladder.
Speaker 3: No calibration of standard candles.
Speaker 2: No massive assumptions about the physics of the Big Bang.
Speaker 3: It is purely geometric. Stefan Tobenberger, who is a leading
Speaker 3: member of the team, calls it the one step method
Speaker 3: for a very good reason.
Speaker 2: It cuts out all the middlemen.
Speaker 3: It really does.
Speaker 2: But there is a catch. There's always catchin astrophysics always.
Speaker 2: You said we have to model the potential, right, That
Speaker 2: means we have to know the exact mass of the
Speaker 2: Lens galaxy. Yes, how do you weigh a galaxy that
Speaker 2: is ten billion light years away? Because if you get
Speaker 2: the weight wrong, you get the potential wrong, and you
Speaker 2: get the Hubble constant wrong.
Speaker 3: This is the absolute crux of the problem with this method,
Speaker 3: it is known as the mass sheet degeneracy.
Speaker 2: That sounds ominous.
Speaker 3: It is the nemesis of lens cosmography.
Speaker 2: What does it actually mean.
Speaker 3: Basically, you can imagine a mathematical transformation where you make
Speaker 3: the lens galaxy much heavier, but you move it slightly
Speaker 3: closer to us okay, or you change the distribution of
Speaker 3: the mass within the galaxy and it produces the exact
Speaker 3: same visual lensing image on our telescopes.
Speaker 2: Oh wow, so the image alone doesn't uniquely tell you
Speaker 2: the mass.
Speaker 3: No, you could have a really heavy lens or a
Speaker 3: slightly lighter lens with a different shape, and they would
Speaker 3: look absolutely identical to the LBT.
Speaker 2: And if you don't know which one it is, you
Speaker 2: can't solve for the accurate distance exactly.
Speaker 3: To break this degeneracy, you need more data.
Speaker 2: What kind of data you need.
Speaker 3: The velocity dispersion of the stars inside the lens.
Speaker 2: Galaxy, meaning you need to measure how fast the stars
Speaker 2: inside that distant lens are zipping around.
Speaker 3: Right, Because faster moving stars mean there's more gravity holding them.
Speaker 2: In, which means more mass exactly.
Speaker 3: And this is where sn winny really really shines compared
Speaker 3: to past discoveries. Why is that usually gravitational lenses are
Speaker 3: incredibly messy.
Speaker 2: Because they are usually massive galaxy clusters, right.
Speaker 3: Yes, swarms of hundreds of galaxies, massive dark matter halos,
Speaker 3: huge clouds of hot X ray gas.
Speaker 2: Trying to mathematically model the mass distribution of a cluster
Speaker 2: sounds like a nightmare.
Speaker 3: It is heavily lumpy, it's chaotic.
Speaker 2: It's like trying to calculate the aerodynamics of a tumbling
Speaker 2: bag of rocks versus a single smooth.
Speaker 3: Sphere that is very accurate.
Speaker 2: But S and WINNY is different.
Speaker 3: Very different. The lens in this case is just two galaxies.
Speaker 2: It's a binary system.
Speaker 3: Yes, Alan Schweinfurth and Leonecker, who are researchers at TUM
Speaker 3: and LMU, they pointed this out.
Speaker 2: They built the mass model for it, and.
Speaker 3: They found it was remarkably clean.
Speaker 2: It's a clean lab for physics.
Speaker 3: The galaxies have very smooth light profiles. They are close
Speaker 3: to each other, but they haven't actually started merging yet.
Speaker 2: So they aren't distorted and tidal stripped and messy.
Speaker 3: No, they are just two massive, relatively simple objects sitting there.
Speaker 2: So the modeling uncertainty is much much lower.
Speaker 3: Drastically lower. Schweinfurth noted that this specific simplicity offers an
Speaker 3: unprecedented opportunity to measure the expansion rate with high accuracy.
Speaker 2: Because we don't have to guess where the dark matter
Speaker 2: is hiding in some giant complex cluster.
Speaker 3: We can model these two galaxies with extreme precision.
Speaker 2: I do want to push back on that slightly, just
Speaker 2: playing devil's advocation. We have two galaxies, doesn't that make
Speaker 2: it a three body problem, or at least a very
Speaker 2: dynamic complex gravitational inter isn't a single isolated galaxy much
Speaker 2: easier to model?
Speaker 3: A single isolated galaxy would be easier, yes, right, But
Speaker 3: single galaxies usually are not massive enough to create this
Speaker 3: wide five image split.
Speaker 2: You need a huge amount of mass to bend the
Speaker 2: light that much.
Speaker 3: Exactly. Usually to get this kind of dramatic separation, you
Speaker 3: need a cluster. Ah, So, finding a binary pair that
Speaker 3: is massive enough to act like a cluster, but simple
Speaker 3: enough to be modeled like individual galaxies.
Speaker 2: That is the absolute sweet spot.
Speaker 3: That is exactly why this is a one in a
Speaker 3: million fine.
Speaker 2: It's the Goldilocks zone of complexity, massive enough to work,
Speaker 2: simple enough.
Speaker 3: To understand perfectly said, and because it is a supernova,
Speaker 3: the time delays are likely very short.
Speaker 2: Like weeks or months, yes, as opposed to lensed quasars,
Speaker 2: where the time delays can be what years easily.
Speaker 3: Quasars are often lensed by those huge clusters where the
Speaker 3: path differences are enormous.
Speaker 2: You might have to wait a decade just to see
Speaker 2: the flicker repeat.
Speaker 3: Which is incredibly frustrated. If you want an answer in
Speaker 3: your lifetime. With s N. Winnie, the whole show will
Speaker 3: be over in a year or so.
Speaker 2: We get the answer quickly, we do. So where are
Speaker 2: we in the actual process right now? The discovery was
Speaker 2: announced in February twenty twenty six.
Speaker 3: Right now, every available major telescope is tracking it.
Speaker 2: Both ground based and space based.
Speaker 3: Yes, they are furiously building the light curves.
Speaker 2: They are measuring exactly when image A hits its peak brightness,
Speaker 2: when image B peaks, and so on.
Speaker 3: They are gathering the raw observational data for the time delays,
Speaker 3: and simultaneously, simultaneously they're using spectrographs to get that critical
Speaker 3: velocity dispersion data we.
Speaker 2: Talked about to properly weigh the two lens galaxies exactly. Okay,
Speaker 2: so prediction time. Let's play the game. What happens when
Speaker 2: the final number actually comes out?
Speaker 3: Okay, let's look at the scenarios.
Speaker 2: Scenario A, the number comes back as seventy three.
Speaker 3: If the number is seventy three or very close to it,
Speaker 3: it is a massive, massive victory for the local ladder team.
Speaker 2: It totally vindicates the Cepheide's standard candle method.
Speaker 3: It completely suggests that the systematic errors they were constantly
Speaker 3: accused of having simply aren't there.
Speaker 2: And it puts the CMB team right in the hot seat.
Speaker 3: It means the standard model of cosmology Lambda CDM is
Speaker 3: fundamentally missing something.
Speaker 2: It means the universe we see today is expanding significantly
Speaker 2: faster than the early universe physics predicted it should.
Speaker 3: Be, and that requires a major physical.
Speaker 2: Explanation like early dark energy.
Speaker 3: That's a popular theory, a birth of accelerated expansion that
Speaker 3: happened shortly after the Big Bang and then just turned off.
Speaker 2: Or maybe dark matter interacts with normal matter in a
Speaker 2: way we completely failed to account for exactly.
Speaker 3: It throws the door wide open to exotic new physics.
Speaker 2: Okay, Scenario B, the number comes back as sixty seven.
Speaker 3: Then the tables turned entirely.
Speaker 2: It vindicates the Plank satellite data and the standard model.
Speaker 3: It strongly suggests that our theoretical understanding of the universe's
Speaker 3: evolution over thirteen point eight billion years is actually perfect.
Speaker 2: But it implies the latter team messed up somehow.
Speaker 3: It would strongly suggest that there is a local hole
Speaker 3: in our cosmic neighborhood, or a very stubborn calibration issue
Speaker 3: with cepheides that we just haven't untangled yet.
Speaker 2: It would be a huge blow to the new physics.
Speaker 3: Crowd, it would, but it would restore order to the universe,
Speaker 3: so to speak.
Speaker 2: Right, And then there's scenario C. Let me guess the
Speaker 2: number is seventy right, smack in the middle.
Speaker 3: That would honestly be the most annoying possible outcome for cosmologists.
Speaker 2: The ultimate compromise candidate.
Speaker 3: It wouldn't actually solve the tension. It would just muddy
Speaker 3: the waters even further.
Speaker 2: It would mean everyone is a little bit wrong.
Speaker 3: Which is possible. But honestly, any result is.
Speaker 2: Good because it's a completely independent result exactly.
Speaker 3: It's not just another team reanalyzing the exact same old
Speaker 3: CEPHEID or CMB data.
Speaker 2: It's a first look at reality itself.
Speaker 3: And we should definitely mention this is just the beginning.
Speaker 2: Because of the new observatories, Yes.
Speaker 3: The Verra Ruben Observatory is coming.
Speaker 2: Online and the Nancy Gray Roman Space Telescope, we are going.
Speaker 3: To find many more of these lensed supernovae.
Speaker 2: So S and Winny is the first of its kind
Speaker 2: to be this perfect, but it won't be the last.
Speaker 3: Exactly. We are actively entering the era of time delay
Speaker 3: cosmography as a standard, reliable tool.
Speaker 2: But S and Winnie will always be the historic one, the.
Speaker 3: Pathfinder, the one that proved it could be done with
Speaker 3: this level of pristine precision.
Speaker 2: It's really a testament to human curiosity and ingenuity when
Speaker 2: you think about it.
Speaker 3: It is.
Speaker 2: Think about all the steps involved here. Someone had to
Speaker 2: come up with the math for general relativity Einstein right,
Speaker 2: and someone else had to physically build the LBT on
Speaker 2: a freezing mountain in Arizona.
Speaker 3: Engineers had to invent adapting optics using actual lasers to
Speaker 3: unblur the sky.
Speaker 2: Astronomers had to painstakingly catalog thousands and thousands of faint galaxies.
Speaker 3: And then, after all that preparation, we had to get
Speaker 3: lucky enough to catch a single star exploding ten billion
Speaker 3: years ago. It really is a cumulative triumph of science.
Speaker 3: It requires every single piece of that massive puzzle to
Speaker 3: be in exactly the right place.
Speaker 2: I want to circle back to that cosmic firework image
Speaker 2: one last time before we close out this discussion. Sure,
Speaker 2: we talked a lot about the hard physics, but there
Speaker 2: is something deeply philosophical about looking at that picture. There
Speaker 2: is we are seeing the exact same event at completely
Speaker 2: different times.
Speaker 3: Right.
Speaker 2: We are seeing the distant past and the slightly less
Speaker 2: distant past, all at the exact same moment on our screen.
Speaker 3: It completely blurs the line of what now even means.
Speaker 3: It does when you look at that image, you aren't
Speaker 3: seeing a snapshot of a single moment in universal time.
Speaker 2: You are seeing a collage.
Speaker 3: A collage of different moments intricately stitched together by gravity.
Speaker 2: It reminds us that simultaneity is entirely relative.
Speaker 3: The universe is a funhouse mirror.
Speaker 2: A very strict, incredibly mathematical funhouse mirror. Exactly so to
Speaker 2: quickly distill the takeaways for everyone who might have gotten
Speaker 2: the little lost in all the megaparsex and gravitational wells.
Speaker 3: It's a lot to take in.
Speaker 2: We found a superluminous supernova s N winny, perfectly split
Speaker 2: into five images by the immense gravity of two foreground.
Speaker 3: Galaxies, a very rare alignment.
Speaker 2: And by precisely timing the delay between when these five
Speaker 2: images arrive at Earth, we can independently measure the expansion
Speaker 2: rate of the universe in a single.
Speaker 3: Step, cutting through the noise.
Speaker 2: Which could finally resolve the Hubble tension, that massive discrepancy
Speaker 2: between how fast the universe is expanding nearby versus how
Speaker 2: fast the early universe models say it should be expanding.
Speaker 3: A perfect summary, the universe provided the ultimate test, and
Speaker 3: now we are basically just grading the paper.
Speaker 2: And those final results should be out within a year
Speaker 2: or two.
Speaker 3: We will be watching very closely.
Speaker 2: I want to leave you all with a final provocative thought. Okay,
Speaker 2: we tend to think of the laws of physics as
Speaker 2: these rigid, unshakable things that are written in stone. We do,
Speaker 2: but the Hubble tension reminds us that our laws are
Speaker 2: really just our current best descriptions of reality.
Speaker 3: They're models, right, So if S.
Speaker 2: And Winnie gives us a number that completely breaks the
Speaker 2: standard model, it doesn't mean the actual universe is broken,
Speaker 2: not at all. It just means our imagination was too small.
Speaker 3: It means that there is a hidden piece of reality
Speaker 3: out there, a.
Speaker 2: Particle, a fundamental force, a weird curve in geometry that
Speaker 2: we simply haven't discovered yet.
Speaker 3: And honestly, isn't that exactly why we do this.
Speaker 2: It's the anomalies that always lead to the breakthroughs. You
Speaker 2: have to follow the glitch.
Speaker 3: Always follow the glitch.
Speaker 2: Tonight, if the sky is clear, go outside, look up.
Speaker 3: You won't be able to see s and Winnie.
Speaker 2: Of course, Oh it's way too faint for your eyes.
Speaker 2: But you can imagine that light.
Speaker 3: Light traveling for ten billion years.
Speaker 2: Splitting apart, racing itself around massive galaxies, taking the scenic route,
Speaker 2: just to land on a mirror in Arizona and tell
Speaker 2: us how big our home really is.
Speaker 3: It's a very big universe out there.
Speaker 2: It certainly is. Thanks for joining us for today's exploration.
Speaker 2: Keep questioning everything, and keep looking up.
Speaker 3: Good Bye everyone, Sai