# The First 3D Thermal Map of Interstellar Space

An episode of [Bedtime Astronomy](https://invisiblenetwork.ai/podcast/1736397134), 17 Aug 2026, 42 min.

Audio: https://dts.podtrac.com/redirect.mp3/api.spreaker.com/download/episode/73278707/starmapp.mp3

Astronomers have created the first 3D thermal map of the interstellar space around our solar system, revealing a far more dynamic environment than expected. Instead of existing only as hot or cold gas, much of the material lies in a turbulent transitional state, constantly cycling between phases. Surprisingly, while the space between stars is chaotic, the interstellar clouds themselves remain remarkably calm. Built with the new 3D mapping tool, this discovery offers an entirely new view of our galactic neighborhood. Thank you for listening to Bedtime Astronomy — your guide to the cosmos. New episodes on space exploration, NASA missions & the latest astronomy breakthroughs.

## Transcript

[0:03] Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
[0:07] Speaker 1: with our soothing Bedtime Astronomie podcast. Each episode offers a
[0:12] Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
[0:16] Speaker 1: unwinding after a long day. Let's travel through the mysteries
[0:20] Speaker 1: of the universe as you drift off into a peaceful
[0:22] Speaker 1: slumber under the night sky.
[0:27] Speaker 2: When you look up at the night sky, you're basically
[0:30] Speaker 2: looking at one of the most persistent, i mean, truly
[0:33] Speaker 2: convincing and just utterly incorrect optical illusions in human history.
[0:38] Speaker 1: Oh.
[0:38] Speaker 3: Absolutely, it's the ultimate trick of the eye.
[0:40] Speaker 2: Right, because we've all done it. You drive out past
[0:44] Speaker 2: the city limits, you know, you get away from the
[0:46] Speaker 2: light pollution. You lean back against the hood of your
[0:49] Speaker 2: car and you just look up.
[0:50] Speaker 3: Yeah, you're trying to take it all.
[0:51] Speaker 2: In exactly, and which your brain registers is this vast,
[0:55] Speaker 2: inky black canvas. It feels completely still, totally silent, and
[1:01] Speaker 2: it's just sprinkled with these brilliant pinpoint diamonds of light, which.
[1:06] Speaker 3: Is beautiful, but it's well, it's a massive biological lie.
[1:10] Speaker 2: Exactly. If I were to ask you, the person listening
[1:12] Speaker 2: to this right now, what that blackness actually is, Like,
[1:15] Speaker 2: what makes up the seemingly infinite gap between our sun
[1:18] Speaker 2: and the next star over. You probably give the answer
[1:20] Speaker 2: we've literally all been taught since grade school.
[1:22] Speaker 3: You call it empty space?
[1:24] Speaker 2: Yeah, you'd say it is a void, a vacuum, just
[1:26] Speaker 2: this freezing, dead, completely featureless backdrop whose only job is
[1:30] Speaker 2: to basically hold the stars in place.
[1:32] Speaker 3: Which honestly is entirely understandable because your brain is just
[1:35] Speaker 3: doing exactly what it evolved to do.
[1:37] Speaker 2: Right Wait, what do you mean by that, like an evolutionary.
[1:39] Speaker 3: Filter, Yeah, exactly. It's prioritizing the discrete, high energy sources
[1:44] Speaker 3: of light, the things that stand out, and it's actively
[1:47] Speaker 3: filtering out the dark. But that biological filter has fundamentally
[1:51] Speaker 3: blinded us to the reality of the cosmos.
[1:54] Speaker 2: So the whole idea of the empty vacuum of space.
[1:57] Speaker 3: Is a complete myth. The reality that's act residing in
[2:00] Speaker 3: that darkness between those stars is a violently churning, wildly complex,
[2:06] Speaker 3: immensely physical environment.
[2:08] Speaker 2: And completely destroying that misconception is our singular mission today.
[2:13] Speaker 2: We are going to map out our local cosmic neighborhood
[2:16] Speaker 2: for you, and I mean map it out in glorious
[2:19] Speaker 2: high definition three dimensions.
[2:20] Speaker 3: It really changes everything once you see it.
[2:22] Speaker 2: It really does. By the end of this conversation, we're
[2:25] Speaker 2: going to reveal a hidden boiling, just immense atmospheric weather
[2:29] Speaker 2: system that absolutely fills the so called empty space surrounding
[2:33] Speaker 2: our solar system. You're going to look at the gaps
[2:35] Speaker 2: between the stars completely differently tonight.
[2:37] Speaker 3: But to even begin doing that, we first have to
[2:40] Speaker 3: establish what is actually out there, right, Like, we have
[2:44] Speaker 3: to understand the baseline material that is filling.
[2:47] Speaker 2: This void, the stuff in the dark.
[2:49] Speaker 3: Right In astrophysics, this is known as the interstellar medium,
[2:53] Speaker 3: or the.
[2:54] Speaker 2: Ism for sure, the ism.
[2:56] Speaker 3: Exactly when we refer to the ism, we are talking
[2:59] Speaker 3: about a sprawling, incredibly diffuse ocean of gas. It's mostly
[3:04] Speaker 3: hydrogen and helium, but it's mixed with these tiny microscopic
[3:08] Speaker 3: grains of carbon and silicate dust.
[3:11] Speaker 2: Okay, let's unpack this because calling it gas and dusk
[3:13] Speaker 2: almost makes it sound like I don't know the stuff
[3:16] Speaker 2: sitting under your refrigerator.
[3:17] Speaker 3: Yeah, it doesn't sound very glamorous.
[3:19] Speaker 2: Not at all. But we're talking about something far more
[3:21] Speaker 2: vital here. This is literally the fundamental raw material of
[3:25] Speaker 2: the universe. I always like to think of it as
[3:27] Speaker 2: cosmic clay.
[3:27] Speaker 3: Oh, I like the cosmic clay.
[3:29] Speaker 2: Yeah, because it's this primal, formless matter that just holds
[3:33] Speaker 2: the potential for literally everything, every single star, every gas giant,
[3:37] Speaker 2: every rocky planet, and by extension, you and me, we
[3:41] Speaker 2: were all formed from this specific material.
[3:43] Speaker 3: That analogy of clay holds up really well physically actually,
[3:46] Speaker 3: because clay has to be molded, and the forces that
[3:49] Speaker 3: muldi ism dictate the entire life and death of the universe.
[3:53] Speaker 2: So it's not just passive background material.
[3:55] Speaker 3: Not even a little bit. The stakes of understanding this
[3:58] Speaker 3: gas just cannot be overstocked. A star is not a
[4:02] Speaker 3: permanent fixture. It has a birth, a life cycle, and
[4:06] Speaker 3: a death, and all of those stages are entirely dependent
[4:09] Speaker 3: on the physical state, the temperature, and the density of
[4:13] Speaker 3: the interstellar medium that surrounds it.
[4:14] Speaker 2: It's like the soil plant grows, and you have to
[4:16] Speaker 2: know the soil to understand the plant.
[4:18] Speaker 3: That's a great way to put it. When we map
[4:20] Speaker 3: the ism, we are not just doing some abstract form
[4:24] Speaker 3: of cosmic cartography just to hang a pretty picture on
[4:26] Speaker 3: a wall. We are trying to isolate the precise physical
[4:30] Speaker 3: environments that allow gravity to win the battle against pressure.
[4:33] Speaker 2: To collapse that gas and ignite a new sun.
[4:35] Speaker 3: Exactly, if you don't understand the complex behavior of this gas,
[4:40] Speaker 3: you are missing the entire opening chapter of the origin
[4:43] Speaker 3: story of our own solar system.
[4:44] Speaker 2: Which makes our historical blindness to all this even more
[4:47] Speaker 2: baffling to me. I mean, if this cosmic clay is
[4:50] Speaker 2: the birthplace of stars, and it is literally everywhere around us,
[4:54] Speaker 2: why did we spend the better part of a century
[4:57] Speaker 2: believing space was just this dead empty vacuum sprinkled with
[5:01] Speaker 2: isolated hot stars.
[5:03] Speaker 3: It does seem crazy in retrospect, right.
[5:05] Speaker 2: To truly grasp the magnitude of this new three dimensional
[5:08] Speaker 2: thermal weather map we're going to talk about, yeah, you
[5:11] Speaker 2: have to realize how fundamentally flawed our old rule book was.
[5:15] Speaker 3: Well, the old rule book wasn't born out of ignorance, exactly.
[5:18] Speaker 3: It came from a very elegant theoretical, mathematical balance. It's
[5:22] Speaker 3: just that it ultimately proved way too simple for reality.
[5:25] Speaker 2: So where did we go wrong?
[5:26] Speaker 3: To understand that, you have to look at the violent
[5:28] Speaker 3: physics governing the interstellar medium. It is an eternal tug
[5:32] Speaker 3: of war playing out across light years.
[5:34] Speaker 2: Okay, tug of war? Who are the players?
[5:36] Speaker 3: On one side? You have heating stars, particularly the young
[5:40] Speaker 3: massive stars. They are essentially massive cosmic heat lamps. They
[5:44] Speaker 3: blast unimaginable amounts of high energy ultraviolet radiation out into
[5:49] Speaker 3: the void, so just tons of UV light exactly. And
[5:52] Speaker 3: when those UV photons collide with the atoms and dust
[5:55] Speaker 3: grains of the interstellar gas, they transfer their kinetic energy.
[6:00] Speaker 3: The radiation literally kicks electrons loose.
[6:03] Speaker 2: Wow, just knock them right off the atom.
[6:05] Speaker 3: Right, and it sends those electrons speeding through the gas,
[6:08] Speaker 3: colliding with other atoms and rapidly raising the overall temperature.
[6:12] Speaker 3: So the starlay is relentlessly trying to boil the gas,
[6:15] Speaker 3: forcing it to expand and become diffuse.
[6:17] Speaker 2: It's basically the equivalent of leaving a black car in
[6:20] Speaker 2: a scorching parking lot in the middle of July. Right.
[6:23] Speaker 2: The solar radiation is just pummeling it, transferring energy and
[6:26] Speaker 2: driving the heat inside out and up.
[6:28] Speaker 3: That's spot on. But obviously space isn't just one infinitely
[6:31] Speaker 3: expanding fireball. There has to be a counterforce.
[6:34] Speaker 2: Right, So what's pulling on the other side of the rope,
[6:36] Speaker 2: On the other.
[6:37] Speaker 3: Side of the tug of war, you have radiation cooling,
[6:39] Speaker 3: which I know sounds a bit contradictory.
[6:41] Speaker 2: Yeah, radiation cooling, How does that work?
[6:43] Speaker 3: Well, the gas and dust itself can actually act as
[6:46] Speaker 3: a massive cosmic radiator. When those heated atoms collide with
[6:49] Speaker 3: one another or when the electrons recombine, they emit energy
[6:53] Speaker 3: in the form of infrared light.
[6:55] Speaker 2: Oh okay, And unlike the trapped heat in your car analogy,
[6:58] Speaker 2: this infrared light easily escapes the gas cloud. It travels
[7:02] Speaker 2: out into deep space, carrying the heat energy away with it. Oh.
[7:05] Speaker 3: I see, so it's venting the heat exactly.
[7:07] Speaker 2: So you have this relentless battle. The intense UV starlight
[7:11] Speaker 2: is furiously trying to boil the gas, and the gas
[7:14] Speaker 2: itself is constantly radiating that heat away into the dark,
[7:18] Speaker 2: basically trying to freeze.
[7:19] Speaker 3: And for decades, classical astrophysics looked at this epic tug
[7:23] Speaker 3: of war and basically concluded that it only ever ended
[7:26] Speaker 3: in a tie in two extremely specific ways.
[7:29] Speaker 2: Yes, the infamous binary theory of the cosmos.
[7:32] Speaker 3: Right, the established math dictated that the cosmic clay would
[7:35] Speaker 3: always cleanly separate into two completely stable extremes. State one
[7:40] Speaker 3: was the cold phase. These were dense, thick clouds of
[7:43] Speaker 3: gas sitting at roughly two hundred.
[7:44] Speaker 2: Kelvin, which is incredibly cold.
[7:46] Speaker 3: Yeah, for context for your listening, two hundred calvin is
[7:49] Speaker 3: about minus one hundred degrees fahrenheit. It is profoundly cold.
[7:52] Speaker 2: And that coldness is absolutely physically necessary.
[7:55] Speaker 3: Why is that because at two hundred kelvin, the thermal
[7:58] Speaker 3: kinetic energy, like the gen and bouncing of the atoms,
[8:01] Speaker 3: is so sluggish that it can no longer resist the
[8:04] Speaker 3: inward pull of the cloud's.
[8:06] Speaker 2: Own gravity, so it starts to clump up.
[8:08] Speaker 3: Exactly, This dense cold state is the only environment where
[8:12] Speaker 3: gas can begin to clump together heavily enough to eventually
[8:14] Speaker 3: spark star formation.
[8:16] Speaker 2: Okay, so that's state one. Then you had the total
[8:19] Speaker 2: opposite end of the spectrum, which was state two. This
[8:22] Speaker 2: was the warm, highly diffuse, super thin gas baking at
[8:27] Speaker 2: roughly seven thousand kelvin.
[8:29] Speaker 3: Which is hotter than the visible surface of our own sun.
[8:32] Speaker 2: Right, So, the textbook picture of the galaxy was just
[8:34] Speaker 2: this vast, boiling seven thousand degree ocean dotted with a
[8:38] Speaker 2: few freezing cold two hundred degree ice cubes floating around
[8:42] Speaker 2: and virtually nothing in between.
[8:43] Speaker 3: What's fascinating here is how the old theoretical models actively
[8:47] Speaker 3: rejected the existence of any material in the middle.
[8:50] Speaker 2: That's the part that always gets me. Logically, you would
[8:52] Speaker 2: just assume there's a spectrum, right, Like, if you have
[8:54] Speaker 2: gas at two hundred kelvin and gas at seven thousand kelvin,
[8:57] Speaker 2: surely there is a transition zone at I don't know,
[8:59] Speaker 2: three thousand than four thousand kelvin.
[9:01] Speaker 3: You would think so. But the classic mathematical models, particularly
[9:05] Speaker 3: the cooling curves we used to calculate this stuff, categorized
[9:08] Speaker 3: anything in the middle as an unstable neutral medium. The
[9:12] Speaker 3: theory treated this middle ground gas as a fleeting, nearly
[9:17] Speaker 3: impossible anomaly.
[9:18] Speaker 2: Wait, but why impossible? I mean, if you heat an
[9:21] Speaker 2: ice cube in your kitchen, it has to pass through
[9:23] Speaker 2: a loopwarm stage before it boils. Why did the maths
[9:26] Speaker 2: say the gas couldn't just sit at three thousand degrees.
[9:29] Speaker 3: It comes down to the efficiency of those cooling mechanisms
[9:32] Speaker 3: I mentioned earlier. The math showed that at those middle temperatures,
[9:36] Speaker 3: the rate at which the gas radiates heat away accelerates
[9:40] Speaker 3: drastically it acts like a trapdoor.
[9:42] Speaker 2: A trap door.
[9:43] Speaker 3: Yeah. If a patch of gas somehow found itself at
[9:46] Speaker 3: three thousand kelvin, the theory dictated that it would instantly
[9:49] Speaker 3: radiate its energy away and plummet straight down to two
[9:52] Speaker 3: hundred kelvin. Or if the starlight hitting it was too intense,
[9:56] Speaker 3: it would instantly be pushed all the way up to
[9:58] Speaker 3: seven thousand.
[9:59] Speaker 2: Kelvin, so it could never just chill in the middle.
[10:01] Speaker 3: Right, It was modeled as a ball bearing perfectly balanced
[10:04] Speaker 3: on the very sharp tip of a mountain peak.
[10:06] Speaker 2: Oh that's a good visual.
[10:07] Speaker 3: Yeah, the absolute slightest perturbation would send it violently rolling
[10:11] Speaker 3: down into the cold valley on one side, or the
[10:13] Speaker 3: hot valley on the other. It was this mathematical ghost
[10:16] Speaker 3: that was just never meant to stick around long enough
[10:19] Speaker 3: to be a meaningful part of the galaxy.
[10:20] Speaker 2: Which came to a very neat, very clean binary picture
[10:24] Speaker 2: of the universe. Except, and here is the kicker, it
[10:28] Speaker 2: was completely wrong. It was a total fabrication born from
[10:33] Speaker 2: how we were looking.
[10:33] Speaker 3: At the sky, a very limiting way of looking at it.
[10:36] Speaker 2: Exactly, which begs the question for all of us. Yeah,
[10:39] Speaker 2: how did generations of brilliant astronomers get the fundamental makeup
[10:43] Speaker 2: of our galaxy so monumentally backwards.
[10:46] Speaker 3: It was entirely a limitation of our methodology. At the time,
[10:49] Speaker 3: we are trying to understand a wildly complex three dimensional
[10:53] Speaker 3: physical structure using a one dimensional tool.
[10:56] Speaker 2: We were essentially blinded.
[10:57] Speaker 3: Yes, blinded by what we call the single line of sight.
[11:00] Speaker 2: I want to try an analogy here, because when I
[11:02] Speaker 2: finally understood how astronomers used to measure this stuff, the
[11:04] Speaker 2: flaw became incredibly obvious to me.
[11:06] Speaker 3: Go for it.
[11:07] Speaker 2: Okay. Imagine you are tasked with creating a weather map
[11:11] Speaker 2: for the entire continent of North America. You need to
[11:15] Speaker 2: map out the blizzards and the rockies, the rain in Seattle,
[11:18] Speaker 2: the massive heat waves in Texas, the whole system. Right,
[11:22] Speaker 2: But you are stationed on the Moon and you are
[11:24] Speaker 2: only allowed to look at the Earth through a single,
[11:27] Speaker 2: incredibly narrow, one dimensional telescope tube.
[11:30] Speaker 3: Okay, I see where this is going.
[11:32] Speaker 2: You point the tube straight down through the atmosphere, and
[11:35] Speaker 2: your instrument is only capable of capturing the average of
[11:38] Speaker 2: whatever light hits it.
[11:39] Speaker 3: That is a highly illustrative way to look at the
[11:41] Speaker 3: spectroscopic methods we were relying on right.
[11:44] Speaker 2: So you look through the tube and the single beam
[11:46] Speaker 2: of light passes through a freezing blizzard at thirty thousand feet,
[11:50] Speaker 2: and it passes through a temperate cloudy layer lower down,
[11:53] Speaker 2: and finally it hits a one hundred degree desert on
[11:56] Speaker 2: the ground.
[11:57] Speaker 3: And your instrument catches all of that simultaneous.
[12:00] Speaker 2: Yes, it catches all that, jumbles it together and spits
[12:03] Speaker 2: out a single average. You look at the data and say, ah,
[12:06] Speaker 2: the entire continent of North America is a perfectly mild
[12:09] Speaker 2: sixty five degrees with a light drizzle.
[12:11] Speaker 3: You completely miss the desert.
[12:12] Speaker 2: You completely miss the desert, and you completely miss the blizzard.
[12:16] Speaker 2: By flattening the data into an average, you completely obliterate
[12:20] Speaker 2: the structure of the weather system.
[12:22] Speaker 3: Which is exactly exactly what astronomers were doing with the
[12:25] Speaker 3: interstellar medium.
[12:26] Speaker 2: It's just wild to think about it.
[12:27] Speaker 3: It is. We would point a telescope at a bright,
[12:31] Speaker 3: distant background star. As the light from that star traveled
[12:35] Speaker 3: thousands of light years to reach our lenses, it would
[12:38] Speaker 3: pass through various clouds of interstellar.
[12:40] Speaker 2: Gas, acting just like the weather layers exactly.
[12:43] Speaker 3: The atoms in those gas clouds would absorb very specific
[12:47] Speaker 3: microscopic wavelengths of that star light depending on their exact
[12:51] Speaker 3: temperature and density. By analyzing the missing gaps in the
[12:54] Speaker 3: light spectrum that finally arrived at Earth, we could calculate
[12:57] Speaker 3: the temperature of the gas the light had passed through.
[13:00] Speaker 2: But just like the weather tube, you're getting an average, right.
[13:03] Speaker 3: We were taking an average over thousands of light years.
[13:06] Speaker 3: If the starlight passed through a freezing cold cloud, then
[13:09] Speaker 3: a blistering hot region, and then another cold cloud, the
[13:12] Speaker 3: resulting data was just a flattened, smeared amalgamation.
[13:16] Speaker 2: So we were looking at this magnificent complex three D
[13:20] Speaker 2: sculpture and trying to understand it by projecting its shadow
[13:24] Speaker 2: against a flat two D wall. We had absolutely no
[13:27] Speaker 2: depth perception.
[13:29] Speaker 3: And without depth perception you cannot see spatial relationships. You
[13:32] Speaker 3: can't see how the hot gas interacts with the cold gas,
[13:35] Speaker 3: or where the boundaries are. It's just impossible.
[13:38] Speaker 2: The cracks were starting to show, right.
[13:39] Speaker 3: Oh, yes, It is vital to point out that we
[13:42] Speaker 3: weren't completely without clues that the binary theory was failing.
[13:45] Speaker 3: Beginning in the late twentieth century, early radio astronomy started
[13:49] Speaker 3: picking up whispers that simply did not fit the model.
[13:52] Speaker 2: The ghost gas started showing up on the instruments.
[13:54] Speaker 3: Precisely, radio telescopes, which measure the faint emissions from cold
[13:58] Speaker 3: neutral hydrogen, started detecting vast quantities of gas that appeared
[14:03] Speaker 3: to be sitting squarely in that supposedly impossible, unstable middle ground.
[14:07] Speaker 2: The three thousand degree trap door.
[14:09] Speaker 3: Yes, the math said the ball bearing should immediately roll
[14:12] Speaker 3: off the mountain peak, but the radio data suggested there
[14:15] Speaker 3: were billions of solar masses of gas just hovering there
[14:18] Speaker 3: flat out, refusing to cool down or heat up.
[14:21] Speaker 2: That sounds like an astrophysics nightmare, because if the gas
[14:24] Speaker 2: is wildly unstable and physically wants to violently drop in temperature,
[14:29] Speaker 2: but it isn't dropping, I mean, what is holding it up?
[14:32] Speaker 3: That was the absolute crisis in the field. It implied
[14:35] Speaker 3: that the interstellar medium was not a quiet, settled place
[14:38] Speaker 3: where gas simply relaxed into a hot or cold state.
[14:42] Speaker 3: It implied a violent, chaotic, continuous turbulence.
[14:45] Speaker 2: Something had to be shaking the mountain exactly.
[14:48] Speaker 3: Some massive unseen cosmic force had to be constantly injecting
[14:52] Speaker 3: energy into the system, aggressively stirring the pot to prevent
[14:55] Speaker 3: the gas from settling into those binary states, the whispers
[14:59] Speaker 3: in the data demas, and a revolution in how we observe.
[15:02] Speaker 2: We couldn't just keep looking through space with single beams
[15:05] Speaker 2: of light. We had to figure out how to map
[15:06] Speaker 2: the actual volume we needed three D. We had to
[15:09] Speaker 2: ditch the telescope tube and essentially build a three D
[15:11] Speaker 2: weather satellite for the galaxy. And that brings us to
[15:14] Speaker 2: the real paradigm shift. A team led by Jonathan Schllist
[15:17] Speaker 2: at the Technique Israel Institute of Technology decided to stop
[15:21] Speaker 2: relying on those one D shadows. They built a groundbreaking
[15:24] Speaker 2: computational tool known as three D.
[15:27] Speaker 3: It's a phenomenal piece of work, and.
[15:28] Speaker 2: This tool is the mechanism that finally finally pulled the
[15:32] Speaker 2: veil back on our local cosmic neighborhood.
[15:34] Speaker 3: You know, the genius of the three D tool is
[15:37] Speaker 3: not that it relied on a brand new magical telescope. Rather,
[15:41] Speaker 3: it is a master class in data synthesis. It takes
[15:44] Speaker 3: three distinct layers of modern astronomical data, layers that had
[15:48] Speaker 3: never been fully integrated in three dimensional space before, and
[15:52] Speaker 3: stacks them to calculate the exact thermodynamic reality of the void.
[15:56] Speaker 2: Okay, let's break those layers down, because this is where
[15:59] Speaker 2: the map actually gets build.
[16:00] Speaker 3: The first fundamental layer is a three dimensional map of interstellar.
[16:03] Speaker 2: Dust, right, the dust mixed in with the gas.
[16:05] Speaker 3: Yeah. Historically dust was a massive nuisance to astronomers. It
[16:09] Speaker 3: blocks and scatters the visible light of the stars we
[16:12] Speaker 3: actually wanted to study.
[16:13] Speaker 2: It was just in the way the cosmic smudge on
[16:15] Speaker 2: the lens exactly.
[16:16] Speaker 3: But recently, large scale surveys have turned that nuisance into
[16:19] Speaker 3: an incredible tool. By measuring exactly how the light of
[16:22] Speaker 3: billions of background stars is reddened and dimmed by the dust,
[16:26] Speaker 3: supercomputers can essentially run a massive game of cosmic Sudoku
[16:31] Speaker 3: to figure out exactly where the dust clouds are located
[16:34] Speaker 3: in three D space.
[16:35] Speaker 2: Oh wow, so they reversed engineer the dust by seeing
[16:37] Speaker 2: what light didn't.
[16:38] Speaker 3: Make it exactly, and it tells us exactly how dense
[16:41] Speaker 3: those dust clouds are.
[16:42] Speaker 2: So layer one gives us a high definition three D
[16:44] Speaker 2: topographical map of the cosmic dirt. We know exactly where
[16:48] Speaker 2: the clumps are and exactly where the empty patches are.
[16:50] Speaker 3: Correct. Now, the second layer is a three dimensional map
[16:54] Speaker 3: of the heating sources. Remember our initial tug of war, the.
[16:58] Speaker 2: UV starlight acting as the heat lamp trying to boil
[17:00] Speaker 2: the gas.
[17:01] Speaker 3: Right, The team utilized massive astronomical catalogs to pinpoint the
[17:06] Speaker 3: exact three D coordinates of all the massive Young O
[17:10] Speaker 3: and B type stars in our galactic neighborhood.
[17:13] Speaker 2: The really hot ones, the heavy hitters.
[17:14] Speaker 3: Yeah, they are pumping out the most extreme ultraviolet radiation.
[17:19] Speaker 3: By knowing where they are and how bright they are,
[17:21] Speaker 3: the team created a comprehensive three D radiation field. They
[17:25] Speaker 3: basically mapped exactly how much UV energy is striking any
[17:29] Speaker 3: given point in space at any time.
[17:30] Speaker 2: Okay, so we have the three D map of the dust,
[17:32] Speaker 2: which we know helped shield and cool the gas, and
[17:34] Speaker 2: we have the three D map of the heat lamps
[17:36] Speaker 2: blasting the.
[17:37] Speaker 3: Radiation, which leads perfectly to the third and most demanding layer,
[17:41] Speaker 3: the thermodynamic calculation. The three D tool takes a microscopic
[17:46] Speaker 3: cube of space, what we call a vauxel, and.
[17:48] Speaker 2: Looks at it, just one tiny coordinated at a time.
[17:50] Speaker 3: Yes, it checks layer one and asks how much dust
[17:54] Speaker 3: is shielding this specific cube. Then it checks layer two
[17:57] Speaker 3: and ask how much UV radiation is bombarding this specific cube.
[18:00] Speaker 3: And then it crunches the complex physics of that tug
[18:03] Speaker 3: of war.
[18:03] Speaker 2: It does the math on who wins exactly.
[18:05] Speaker 3: It calculates the thermal equilibrium. It determines whether the gas
[18:09] Speaker 3: in that exact microscopic cue is cold, hot, or caught
[18:13] Speaker 3: in that unstable middle. And it does this calculation millions
[18:17] Speaker 3: and millions of times, building a complete volumetric picture of
[18:20] Speaker 3: the gas.
[18:21] Speaker 2: It essentially calculated the cosmic weather at every single coordinate
[18:25] Speaker 2: it did. But I really really want to pause here
[18:27] Speaker 2: to make sure you the listener, comprehend the sheer, staggering
[18:31] Speaker 2: scale of the map they generated. We aren't talking about
[18:34] Speaker 2: mapping a small little pocket of a nebula.
[18:35] Speaker 3: Here.
[18:36] Speaker 2: The three D tool generated a continuous thermal weather map
[18:39] Speaker 2: spanning a one kiloparsec wide region. Center did squarely on
[18:43] Speaker 2: our sun.
[18:44] Speaker 3: And a kilo parsec is a unit of measurement that
[18:46] Speaker 3: often causes the human brain to just shut down because
[18:49] Speaker 3: we have no earthly frame of reference for it exactly.
[18:51] Speaker 2: So let's give it a frame of reference. A kiloparsec
[18:53] Speaker 2: is roughly three thousand, two hundred and sixty light years across,
[18:57] Speaker 2: which is huge, right, and light travels at a h
[19:00] Speaker 2: one hundred and eighty six thousand miles per second. It
[19:03] Speaker 2: is moving fast enough to orbit the Earth seven times
[19:06] Speaker 2: before you can even blink. If you were to shine
[19:09] Speaker 2: a laser pointer from the left edge of this new map,
[19:13] Speaker 2: that like traveling at that unimaginable speed, would take two
[19:18] Speaker 2: hundred and sixty years just to reach the right edge.
[19:20] Speaker 3: It's a timescale we can barely fathom.
[19:22] Speaker 2: Think about it this way. If someone on the edge
[19:25] Speaker 2: of this map fired a laser beam toward the other
[19:27] Speaker 2: side on the exact day the ancient Egyptians lay the
[19:30] Speaker 2: very first stone of the Great Pyramid of Giza, that
[19:33] Speaker 2: beam of light is just barely reaching the other side
[19:35] Speaker 2: of the map today.
[19:36] Speaker 3: That is a phenomenal way to picture it.
[19:37] Speaker 2: That is the volume of space we are talking about.
[19:39] Speaker 2: It is a vast, unfathomable ocean, and our entire solar
[19:42] Speaker 2: system is just one microscopic speck floating right in the
[19:46] Speaker 2: middle of it.
[19:46] Speaker 3: And when the team finally let the supercomputers render that
[19:49] Speaker 3: vast ocean of data in three dimensions, the results completely
[19:53] Speaker 3: shattered the old binary models. What emerged was not a chaotic,
[19:57] Speaker 3: random jumble of hot and cold.
[19:59] Speaker 2: Patches's where it gets really interesting. The map revealed a
[20:03] Speaker 2: highly organized, deeply structured physical architecture. The gas wasn't just existing,
[20:09] Speaker 2: it was organizing itself.
[20:10] Speaker 3: Yes, there was a clear anatomy to it.
[20:12] Speaker 2: The map showed distinct massive cold clouds, those dense freezing
[20:17] Speaker 2: two hundred kelvin pits we talked about, But they were
[20:20] Speaker 2: not sitting naked in the voice.
[20:21] Speaker 3: They weren't isolated.
[20:22] Speaker 2: No, every single one of these cold clouds was completely wrapped,
[20:26] Speaker 2: encased and closed in a thick, massive shell of that
[20:29] Speaker 2: supposedly rare, supposedly impossible unstable gas.
[20:32] Speaker 3: The three thousand degree gas.
[20:34] Speaker 2: Exactly, and all of these wrap clouds were suspended floating
[20:37] Speaker 2: inside a sprawling, overarching background pool of the warm, diffuse
[20:42] Speaker 2: seven thousand kelvin material.
[20:43] Speaker 3: The spatial relationship of the gas phases was just the
[20:46] Speaker 3: critical revelation here. The unstable gas was not a mathematical ghost,
[20:51] Speaker 3: nor was it a fleeting anomaly scattered at random like
[20:53] Speaker 3: we thought. It had a defined structural purpose in the
[20:57] Speaker 3: anatomy of the interstellar medium.
[20:58] Speaker 2: I stared at the visualistations of this for a really
[21:01] Speaker 2: long time, trying to find a way to picture it,
[21:04] Speaker 2: and the absolute best analogy I can offer is a
[21:07] Speaker 2: cosmic avocado floating in a warm bath.
[21:10] Speaker 3: A cosmic avocado. Okay, I'm listening.
[21:13] Speaker 2: It sounds absurd, I know, but physically attracts perfectly.
[21:16] Speaker 3: Walk me through it.
[21:16] Speaker 2: Okay. The dense hard pit in the absolute center of
[21:20] Speaker 2: the avocado. That is your freezing cold, dense cloud. The thick,
[21:25] Speaker 2: fleshy green part of the avocado that wraps entirely around
[21:28] Speaker 2: the pit. That is the shell of unstable gas. And
[21:30] Speaker 2: the warm bathwater that the whole avocado's bobbing around in.
[21:34] Speaker 2: That is the diffuse hot seven thousand kelvin gas that
[21:38] Speaker 2: fills the bulk of the space.
[21:39] Speaker 3: You know, I will grant you the avocado analogy because
[21:42] Speaker 3: physics explaining why that structure forms is brilliantly logical when
[21:45] Speaker 3: you actually view it in three d Oh.
[21:46] Speaker 2: It all comes back to the dust, right.
[21:48] Speaker 3: It all circles back to the tug of war between
[21:51] Speaker 3: heating and cooling. Let's start the center the pit. Why
[21:55] Speaker 3: is it two hundred kelvin Because the gas there is
[21:58] Speaker 3: highly compressed, which means the microscopic dust mixed in with
[22:01] Speaker 3: it is also highly compressed.
[22:03] Speaker 2: So the dust is packed tight.
[22:05] Speaker 3: Very tight. That density creates a physical barrier. It acts
[22:09] Speaker 3: like a lead wall, or like a cosmic umbrella, utterly
[22:13] Speaker 3: blocking the incoming ultraviolet starlight.
[22:15] Speaker 2: So the heat lamps are completely blocked.
[22:17] Speaker 3: Right. Because the UV heat lamps are blocked, the radiation
[22:20] Speaker 3: cooling mechanisms run unchecked in the center. The temperature plummets,
[22:24] Speaker 3: the gas condens is even tighter, and the pit remains frozen.
[22:28] Speaker 2: Okay, so the pit is heavily armored against the heat.
[22:31] Speaker 2: But what happens when you start moving outward.
[22:33] Speaker 3: As you move radially outward from that dense core, entering
[22:36] Speaker 3: the fleshy green part of your avocado, the gas naturally
[22:39] Speaker 3: begins to thin out. The density drops, and because the
[22:42] Speaker 3: density is dropping, there are fewer dust grains.
[22:44] Speaker 2: So the cosmic umbrella starts to tear it gets hold
[22:47] Speaker 2: in it. The UV light from the massive stars starts
[22:49] Speaker 2: leaking through.
[22:50] Speaker 3: The cracks exactly. The environment changes entirely at this boundary.
[22:54] Speaker 3: The gas is no longer dense enough to rely on
[22:56] Speaker 3: the highly efficient cooling mechanisms found in the core. But simultaneously,
[23:01] Speaker 3: there is still just enough dust present that the gas
[23:04] Speaker 3: isn't entirely baked by the full unfiltered wrath of the
[23:07] Speaker 3: UV radiation outside.
[23:09] Speaker 2: Oh, so it's stuck.
[23:10] Speaker 3: It is caught in a physical and thermodynamic stalemate. It
[23:14] Speaker 3: cannot plummet to the two hundred kelvin cold state because
[23:17] Speaker 3: there's too much UV leaking in, but it is shielded
[23:20] Speaker 3: just enough that it cannot boil up to the seven
[23:22] Speaker 3: thousand kelvin warm state.
[23:24] Speaker 2: It gets physically trapped on the tip of the mountain.
[23:26] Speaker 3: Yes, it becomes a spatial transition zone. The unstable gas
[23:31] Speaker 3: is the physical interface between the protected cold core and
[23:34] Speaker 3: the exposed warm bath. The three D map proved that
[23:38] Speaker 3: the unstable medium isn't a mistake in the old calculations.
[23:41] Speaker 3: It is a permanent structural skin that must exist whenever
[23:44] Speaker 3: a dense cloud interacts with a diffuse hot environment.
[23:47] Speaker 2: That makes so much sense when you visualize it that way.
[23:50] Speaker 2: So we solve the mystery of where the unstable gas lives.
[23:53] Speaker 2: It's the skin of the avocado.
[23:54] Speaker 3: Yes, the skin.
[23:55] Speaker 2: But knowing where it is didn't prepare anyone for the
[23:58] Speaker 2: next major bombshell of the study, because knowing where it
[24:01] Speaker 2: is is one thing, but calculating how much of it
[24:03] Speaker 2: is actually out there, I mean that completely destroyed whatever
[24:07] Speaker 2: fragments of the classical models were left.
[24:09] Speaker 3: Stand Oh, without a doubt, the location made thermodynamic sense,
[24:13] Speaker 3: But the mass fractions, the literal percentage of the total
[24:17] Speaker 3: gas mask that exists in this volatile state, is what
[24:20] Speaker 3: truly shocked the astrophysics community.
[24:23] Speaker 2: Let's look at the numbers they pulled from the map,
[24:25] Speaker 2: specifically when they focused on the region near the galactic plane.
[24:28] Speaker 2: For those visualizing this, the galactic plane is the flat,
[24:31] Speaker 2: dense disc of the Milky Way where the vast majority
[24:33] Speaker 2: of the stars, gas, and dust are heavily concentrated.
[24:37] Speaker 3: It's the busy part of the galaxy.
[24:38] Speaker 2: Very busy. When the team calculated the mass of all
[24:41] Speaker 2: the gas in this turbulent disc, they found that twenty
[24:44] Speaker 2: seven percent of the mass was the cold gas the pits.
[24:47] Speaker 2: They found that thirty two percent of the mass was
[24:49] Speaker 2: the warm gas the hot bath water them, and a staggering,
[24:53] Speaker 2: utterly massive forty one percent of the total gas mass
[24:57] Speaker 2: was made up of the unstable shell material.
[25:00] Speaker 3: Is an important question, a question that strikes at the
[25:02] Speaker 3: very heart of how we understand fluid dynamics in space,
[25:06] Speaker 3: which is, if classical theory dictated that this gas was
[25:09] Speaker 3: in a state of highly unstable rapid transition. You know,
[25:13] Speaker 3: a ball on the tip of a peak that violently
[25:15] Speaker 3: wants to roll down into the cold or hot valleys.
[25:19] Speaker 3: How is it physically possible that it makes up the
[25:21] Speaker 3: overwhelming forty one percent plurality of the gas mass in
[25:24] Speaker 3: the galactic disk.
[25:25] Speaker 2: It's insane. It outnumbers the cold gas, and it outnumbers
[25:29] Speaker 2: the hot gas. It's like being told by meteorologists that
[25:33] Speaker 2: storm clouds are a mathematical anomaly that barely exists, and
[25:37] Speaker 2: then you launch a weather satellite and realize forty one
[25:40] Speaker 2: percent of the Earth's entire atmosphere is made of Category
[25:43] Speaker 2: five hurricane clouds.
[25:44] Speaker 3: The anomaly is actually the dominant.
[25:46] Speaker 2: Feature, right, So how does it stay there?
[25:47] Speaker 3: To maintain forty one percent of the interstellar mass in
[25:50] Speaker 3: a mathematically unstable state requires a staggering amount of kinetic energy.
[25:54] Speaker 3: It proves that the interstellar medium is far from a calm, subtled.
[25:57] Speaker 2: Fluid, so it's not just sitting there.
[25:59] Speaker 3: No. The only way you can keep that much gas
[26:02] Speaker 3: balance on the tip of the mountain is if the
[26:04] Speaker 3: mountain is undergoing a massive earthquake. The gas is cycling
[26:07] Speaker 3: violently and rapidly across the temperature boundaries.
[26:10] Speaker 2: But what does cycling actually mean in the vacuum of space.
[26:14] Speaker 2: I think we really need to visualize this sheer violence
[26:16] Speaker 2: of what is happening to this gas. It's not just
[26:19] Speaker 2: quietly changing temperature.
[26:21] Speaker 3: Not at all. We're talking about extreme astrophysical violence. Here.
[26:25] Speaker 3: Picture the hot seven thousand degree diffuse gas. Suddenly, a
[26:30] Speaker 3: massive star nearby reaches the end of its life and
[26:34] Speaker 3: detonates in a supernova.
[26:35] Speaker 2: A massive explore right.
[26:37] Speaker 3: That explosion sends a colossal supersonic shockwave plowing through the
[26:41] Speaker 3: warm gas, physically slamming it together, compressing it, forcing its
[26:45] Speaker 3: density up until it is violently shoved into the unstable state.
[26:48] Speaker 2: So the shockwave forces it up the mountain exactly.
[26:51] Speaker 3: And simultaneously, you have galactic gravity creating immense sheer forces
[26:55] Speaker 3: squeezing vast regions of space.
[26:57] Speaker 2: On the flip side, you have the cold clouds being
[26:59] Speaker 2: tore apart from the inside.
[27:01] Speaker 3: Right precisely inside those dense cold pits, gravity triggers the
[27:06] Speaker 3: birth of new massive stars, and the moment those stars ignite,
[27:10] Speaker 3: they unleash torrential stellar winds and blistering UV radiation, physically
[27:16] Speaker 3: blasting the cold cloud apart. From the inside out.
[27:19] Speaker 2: So it's heating the cold gas and forcing it back
[27:21] Speaker 2: up into the unstable state from the bottom. You've got it.
[27:24] Speaker 3: The mass of the galaxy is constantly flowing back and
[27:26] Speaker 3: forth across these boundaries, driven by supernova, stellar winds and
[27:30] Speaker 3: galactic gravity. The universe is relentlessly stirring the pot and.
[27:34] Speaker 2: The map allowed researchers to actually calculate the time scale
[27:37] Speaker 2: of this stirring, which is amazing. They found that the
[27:39] Speaker 2: gas cycles between the hot, cold and unstable states roughly
[27:43] Speaker 2: every three to six million years, which is a crucial number. Now,
[27:47] Speaker 2: if I say three million years to you, the listener,
[27:50] Speaker 2: your brain probably registers that as an incomprehensibly long time.
[27:53] Speaker 2: To put it in perspective, three million years ago on Earth,
[27:56] Speaker 2: early hominids like Astrolopithecus were just figuring out how how
[28:00] Speaker 2: to walk upright across the African savannah. From the dawn
[28:02] Speaker 2: of human bipedalism to the invention of the iPhone, that
[28:05] Speaker 2: is one cycle.
[28:06] Speaker 3: It feels like forever to us it.
[28:09] Speaker 2: Is an eternity. But how does that clock read in
[28:12] Speaker 2: cosmic terms?
[28:13] Speaker 3: In astrophysics, three million years is a frantic, anxious blink
[28:17] Speaker 3: of an eye. You really have to scale your perspective.
[28:20] Speaker 3: The universe is roughly thirteen point eight billion years old.
[28:24] Speaker 3: Our own sun has been burning for four point six billion.
[28:27] Speaker 2: Years, so three million is nothing.
[28:29] Speaker 3: It's blindingly fast. What this number tells us is that
[28:32] Speaker 3: the thermal relaxation timeli like the millions of years it
[28:35] Speaker 3: would take for a patch of hot gas to slowly
[28:37] Speaker 3: cool down and peacefully settle into a stable cold cloud,
[28:41] Speaker 3: is perfectly matched by the timescale of the violent turbulence
[28:44] Speaker 3: stirring it up.
[28:44] Speaker 2: Oh, the turbulence never gives the gas a chance to
[28:47] Speaker 2: rest exactly. The gas is desperately trying to slide down
[28:50] Speaker 2: the mountain into a calm state, But every three million years,
[28:53] Speaker 2: a supernova or a gravity wave sweeps through and whips
[28:56] Speaker 2: it back into the chaotic, unstable green flesh of the avocado.
[29:00] Speaker 2: The pot never ever.
[29:01] Speaker 3: Stops boiling, and that boiling is highly localized, which the
[29:04] Speaker 3: three D map captured beautifully. The forty one percent mass
[29:07] Speaker 3: fraction of unstable gas is a feature of the galactic
[29:09] Speaker 3: plane the dense disk, but the three D tool also
[29:12] Speaker 3: map the volume vertically.
[29:13] Speaker 2: Right, it looked above and below the disk.
[29:15] Speaker 3: Yes, it looked up and down away from the flat
[29:17] Speaker 3: disk and into the galactic halo. And they discovered that
[29:20] Speaker 3: geography matters immensely.
[29:22] Speaker 2: Because as you travel further away from the dense galactic plane,
[29:25] Speaker 2: moving higher up, the cosmic environment undergoes a massive shift.
[29:30] Speaker 2: The overall density of the interstellar matter just drops off
[29:33] Speaker 2: a cliff.
[29:34] Speaker 3: Which fundamentally alters the thermodynamic tug of war. As the
[29:37] Speaker 3: density drops, the concentration of.
[29:39] Speaker 2: Dust plummets, and without the dust.
[29:42] Speaker 3: Without the dust to act as a cosmic umbrella or
[29:44] Speaker 3: a radiant cooler, the cooling mechanisms become entirely inefficient. Consequently,
[29:49] Speaker 3: the turbulent unstable storm dissipates and the warm, diffuse seven
[29:53] Speaker 3: thousand kelvin gas completely takes over as the dominant mass component.
[29:58] Speaker 2: Space gets thinner and wildly hotter the higher you go.
[30:00] Speaker 2: It's like an inverted version of Earth's atmosphere honeymoon. On Earth,
[30:04] Speaker 2: if you start at sea level and climb Mount Everest,
[30:06] Speaker 2: the air gets thinner and colder, but in the Milky Way,
[30:08] Speaker 2: if you start at the dense galactic plane and climb
[30:10] Speaker 2: up into the halo, the gas gets thinner and blistering hot.
[30:14] Speaker 2: You leave the chaotic forty one percent unstable hurricane of
[30:17] Speaker 2: the disk, and you emerge into a vast, thin, baking
[30:20] Speaker 2: hot desert.
[30:21] Speaker 3: Which honestly serves as a perfect vindication for.
[30:24] Speaker 2: The three D mapping technique.
[30:26] Speaker 3: Why is that, well, imagine if your single line of
[30:28] Speaker 3: sight telescope just happened to be pointed straight up out
[30:31] Speaker 3: of the galactic disc. You would analyze the light and
[30:34] Speaker 3: conclude that the entire galaxy is just a calm, warm,
[30:38] Speaker 3: diffuse desert. You would entirely miss the raging multi phase
[30:43] Speaker 3: storm churning just below you.
[30:45] Speaker 2: You'd be totally fool completely. So we have established a
[30:48] Speaker 2: completely new reality here. The space between the stars in
[30:52] Speaker 2: our galactic neighborhood is a violently swirling, rapidly cycling, turbulent
[30:57] Speaker 2: ocean of gas being blasted by supernoe and whipped around
[31:01] Speaker 2: every few million years.
[31:02] Speaker 3: That is the reality.
[31:03] Speaker 2: Yes, the unstable gas is the dominant feature, Which is
[31:06] Speaker 2: why I really need to push back on the final
[31:08] Speaker 2: discovery outland of the data, because honestly, it feels like
[31:11] Speaker 2: a massive contradiction to everything we just said.
[31:13] Speaker 3: It is undoubtedly the most counterintuitive finding to emerge from
[31:16] Speaker 3: the three D map, and yet it is the finding
[31:19] Speaker 3: that will arguably have the most profound lasting impact on
[31:22] Speaker 3: the field of astrophysics moving forward.
[31:24] Speaker 2: Let me voice the confusion that I had when I
[31:26] Speaker 2: read this, and that I'm sure you listening are having
[31:28] Speaker 2: right now. We just painted a picture of absolute, unyielding chaos.
[31:35] Speaker 2: We have these freezing cold pits of gas and they
[31:38] Speaker 2: are completely encased in massive, thick shells of unstable gas.
[31:43] Speaker 2: Right we know this shell makes up forty one percent
[31:45] Speaker 2: of the mass, and we know it is violently churning,
[31:48] Speaker 2: rapidly cycling, being bombarded by UV radiation in supernova shockwaves
[31:53] Speaker 2: every three million years. If you have a raging category
[31:57] Speaker 2: five multi phase storm violently threating the outside of the cloud,
[32:01] Speaker 2: wouldn't the inside of that cold cloud be incredibly chaotic
[32:05] Speaker 2: and highly turbulent too, You'd think so, I mean, how
[32:08] Speaker 2: could the outside be boiling while the inside remains unaffected?
[32:11] Speaker 3: Logic, and indeed, decades of prior astronomical modeling would completely
[32:15] Speaker 3: agree with your assumption. If you are sitting inside a
[32:17] Speaker 3: house while a tornado rips through your neighborhood, the walls
[32:20] Speaker 3: are shaping, the windows are bowing. The interior is absolutely
[32:23] Speaker 3: compromised by the exterior kinetic energy, but the three D
[32:26] Speaker 3: thermal map revealed the exact opposite behavior in the interstellar medium.
[32:31] Speaker 3: The most unexpected result was that despite the raging volatile
[32:35] Speaker 3: multiphase storm detonating within the unstable shells, the internal density
[32:39] Speaker 3: of the cold clouds themselves remains remarkably constant.
[32:43] Speaker 2: The turbulence inside them is surprisingly mild.
[32:46] Speaker 3: Mild, quiescent, serene. Even the cold clouds are basically the
[32:51] Speaker 3: eye of the hurricane.
[32:52] Speaker 2: That is just baffling to me. How is the physics
[32:55] Speaker 2: of that even possible? How does the violence of a
[32:57] Speaker 2: supernova shock wave hitting the unstable shell not penetrate into
[33:01] Speaker 2: the core.
[33:02] Speaker 3: It speaks to the incredible, almost unbelievable insulating power of
[33:05] Speaker 3: that transition zone. The unstable shell is not just a
[33:08] Speaker 3: byproduct of the turbulence. It is actively acting as a
[33:11] Speaker 3: cosmic shock absorber.
[33:13] Speaker 2: A shock absorber, yes.
[33:14] Speaker 3: Because the gas in the shell is in that thermodynamic
[33:17] Speaker 3: middle ground, it is highly compressible but also highly expansive.
[33:21] Speaker 3: When a kinetic shockwave hits the shell, the unstable gas
[33:23] Speaker 3: takes the brunt of the impact.
[33:25] Speaker 2: It squishes instead of shattering.
[33:27] Speaker 3: Exactly, it dissipates the kinetic energy absorbs the UV radiation
[33:31] Speaker 3: and buffers all that galactic stirring. It bleeds off the
[33:35] Speaker 3: violence before it can ever penetrate into the deepest, most
[33:38] Speaker 3: dense parts of the cold core. Wow, the core remains
[33:42] Speaker 3: completely protected, isolated, thermly and kinetically. It maintains a steady,
[33:46] Speaker 3: calm density, while its outer layers just boil and thrash.
[33:50] Speaker 2: Wait, if the inside of these clouds is actually calm,
[33:53] Speaker 2: then everything we thought we knew about how stars are
[33:55] Speaker 2: born is wrong.
[33:56] Speaker 3: If we connect this to the bigger picture, it completely
[34:00] Speaker 3: he writes the fundamental models for star formation. And this
[34:03] Speaker 3: really is the crux of why mapping the cosmic clay
[34:06] Speaker 3: matter so deeply.
[34:07] Speaker 2: Let's break down exactly why this is a scientific earthquake.
[34:10] Speaker 2: Think about what a cold cloud actually is. It isn't
[34:13] Speaker 2: just a floating ice cube. It is a stellar nursery,
[34:16] Speaker 2: the birthplace of suns. These dense two hundred kelvin dust
[34:20] Speaker 2: shielded pits are the exact specific locations where gravity finally
[34:24] Speaker 2: gets the upper hand in the universe. Gravity pulls the cold,
[34:27] Speaker 2: sluggish gas together, compressing it tighter and tighter, until the
[34:30] Speaker 2: pressure in the center becomes so intense that nuclear fusion ignites.
[34:34] Speaker 3: And a brand new star violently flares to life.
[34:37] Speaker 2: Understanding this process, Understanding exactly how and when stars ignite
[34:42] Speaker 2: is basically the holy grail of astrophysics. But for decades,
[34:46] Speaker 2: scientists built their star formation models based on the assumption
[34:49] Speaker 2: that these nurseries were highly turbulent on the inside.
[34:51] Speaker 3: Because they couldn't see the shock absorber exactly.
[34:54] Speaker 2: The old computational models treated cold gas as an isolated,
[34:58] Speaker 2: violently shaking box. They assumed the turbulence inside the cloud
[35:02] Speaker 2: was the primary antagonist that gravity had overcome. Right.
[35:06] Speaker 3: If a nursery is shaking violently, the kinetic energy acts
[35:08] Speaker 3: as a support mechanism, physically pushing outward, making it incredibly
[35:12] Speaker 3: difficult for gravity to pull the material together into a
[35:16] Speaker 3: dense enough point to form a star.
[35:18] Speaker 2: It makes gravity's job a lot harder.
[35:20] Speaker 3: But the map proves the box isn't shaking. We were
[35:23] Speaker 3: wrong about the very environment of stellar birth. If the
[35:26] Speaker 3: unstable shell is absorbing all the turbulence and the inside
[35:28] Speaker 3: of the nursery is actually calm and mild, gravity has
[35:32] Speaker 3: a vastly easier time doing its job. It alters the
[35:35] Speaker 3: entire timeline and efficiency rate of star formation. If the
[35:39] Speaker 3: interior is quiescent, gravity doesn't have to fight nearly as
[35:42] Speaker 3: much internal pressure. Gas can collapse more efficiently, which.
[35:46] Speaker 2: Means stars might form faster or in different ways than
[35:48] Speaker 2: we simulated exactly.
[35:51] Speaker 3: But the implications stretch even further than just recognizing the
[35:54] Speaker 3: internal calm. The three D map demands a complete paradigm
[35:58] Speaker 3: shift in how we bound our simulations. We can no
[36:01] Speaker 3: longer treat these cold clouds as isolated floating islands.
[36:04] Speaker 2: You can't just draw a mathematical box around the cold gas,
[36:07] Speaker 2: pretend it exists in a vacuum, and hit calculate. The
[36:10] Speaker 2: new scientific mandate is that cold gas cannot be treated
[36:13] Speaker 2: as a standalone reservoir.
[36:15] Speaker 3: It must be treated as a highly dynamic, interconnected component
[36:18] Speaker 3: of a massive, restless, three part multi phase system.
[36:22] Speaker 2: Everything is connected.
[36:23] Speaker 3: Yes, the cold core is bleeding gas into the unstable shell,
[36:27] Speaker 3: The unstable shell is exchanging material with the warm diffuse bath,
[36:30] Speaker 3: and the warm bath is being compressed back into the shell.
[36:33] Speaker 3: When astrophysicists simulate the birth of a star, from now on,
[36:36] Speaker 3: they have to simulate the entire avocado.
[36:39] Speaker 2: They have to include the skin and the bath water exactly.
[36:42] Speaker 3: They have to account for the continuous million year cycling
[36:45] Speaker 3: of mass across these summill boundaries, even as the heavily
[36:49] Speaker 3: protected center provides a calm sanctuary for gravity to pull
[36:53] Speaker 3: a new sun into existence.
[36:55] Speaker 2: It's a beautifully holistic view of the cosmos. We aren't
[36:58] Speaker 2: just looking at isolated, dead eye objects hanging on a
[37:01] Speaker 2: black backdrop anymore. We were looking at a living, breathing,
[37:05] Speaker 2: deeply interconnected ecosystem.
[37:07] Speaker 3: It feels much more alive.
[37:08] Speaker 2: So what does this all mean. Let's take a step
[37:10] Speaker 2: back and look at the massive conceptual journey we've just
[37:13] Speaker 2: gone on here. We started this hour with the classic
[37:16] Speaker 2: stubborn image of the night sky, the myth of the dark, cold,
[37:19] Speaker 2: empty void, the.
[37:21] Speaker 3: Vacuum, a myth that, as we discussed, was deeply ingrained
[37:25] Speaker 3: by the physical limitations of our own single line of
[37:27] Speaker 3: sight instruments. We literally couldn't see the forest for the trees.
[37:31] Speaker 2: We were looking through the weather tube. Then we evolved
[37:34] Speaker 2: our understanding slightly into the binary theory. We realized the
[37:37] Speaker 2: void wasn't completely empty, but we falsely assumed it was
[37:40] Speaker 2: a stark, extreme battle between freezing cold ice cubes and
[37:43] Speaker 2: boiling hot gas, with nothing allowed to exist.
[37:46] Speaker 3: In between, and then the three D revolution tore that
[37:48] Speaker 3: assumption down. By layering the three D topography of interstellar dust,
[37:53] Speaker 3: the three D radiation fields of massive stars, and rigorous
[37:56] Speaker 3: thermodynamic models, we finally gained depth, and.
[38:00] Speaker 2: That three D depth perception revealed the absolute truth of
[38:03] Speaker 2: our local universe. A massive, violently churning weather system spanning
[38:08] Speaker 2: thousands of light years, a volatile system where forty one
[38:11] Speaker 2: percent of the gas mass is caught in a rapid cycling,
[38:14] Speaker 2: unstable transition zone, constantly being whipped by supernovae.
[38:18] Speaker 3: The cosmic avocado in all its glory.
[38:20] Speaker 2: Yes, we discovered the cosmic avocado, dense, profoundly calm, cold pits,
[38:25] Speaker 2: tightly wrapped in violent shock absorbing unstable shells, all bobbing
[38:29] Speaker 2: in a hot, diffuse bath.
[38:30] Speaker 3: We moved from a static dead view of the universe
[38:34] Speaker 3: to a dynamic, multi phase reality. We discovered that the
[38:38] Speaker 3: interstellar medium is a raging, relentless storm, and yet paradoxically,
[38:43] Speaker 3: the very violence of that storm creates the insulated, quiet
[38:46] Speaker 3: nurseries required to birth new stars.
[38:49] Speaker 2: Which leads me with one final, slightly unnerving, deeply provocative
[38:53] Speaker 2: thought for you to mull over throughout this entire conversation,
[38:57] Speaker 2: we've been talking about this one kiloparsec map as if
[39:00] Speaker 2: it's some distant object we are safely observing through a window.
[39:04] Speaker 3: It's not.
[39:04] Speaker 2: No, Remember the scale and remember the location. The map
[39:08] Speaker 2: is centered squarely on our Sun, our solar system, our Earth,
[39:11] Speaker 2: our Moon, our atmosphere, our entire existence is sitting directly
[39:14] Speaker 2: inside this mapped region.
[39:15] Speaker 3: Oh, we are right in the thick of it.
[39:17] Speaker 2: We are not just observing this cosmic weather system. We
[39:19] Speaker 2: are physically adrift inside it. And here's the kicker. Our
[39:23] Speaker 2: Sun is not stationary. It is orbiting the supermassive black
[39:26] Speaker 2: hole at the center of the Milky Way galaxy at
[39:28] Speaker 2: a speed of roughly half a million miles per hour.
[39:30] Speaker 2: Our entire Solar system is actively moving, plowing through this
[39:34] Speaker 2: cosmic environment.
[39:35] Speaker 3: Which invites the ultimate question regarding our long term existence.
[39:38] Speaker 3: What's that if the interstellar medium is constantly churning, if
[39:42] Speaker 3: it is structured with these vast warm diffuse pools and
[39:46] Speaker 3: these thick cold clouds wrapped in highly unstable turbulent shells,
[39:51] Speaker 3: what happens to a solar system when it inevitably drifts
[39:54] Speaker 3: across one of these massive thermal boundaries.
[39:57] Speaker 2: Oh wow.
[39:57] Speaker 3: Our Sun has been traveling on its galactic orbit for
[40:00] Speaker 3: four point six billion years. It has undoubtedly passed through warm,
[40:04] Speaker 3: diffuse regions, plunged through unstable shells, and perhaps even graze
[40:08] Speaker 3: the edges of dense cold clouds.
[40:11] Speaker 2: Could the cosmic weather eventually impact the physical climate of
[40:15] Speaker 2: the planet's traveling within it, like if our solar system
[40:17] Speaker 2: plunges straight into one of these dense two hundred kelvin
[40:21] Speaker 2: cold clouds. Does the massive influx of interstellar dust choke
[40:25] Speaker 2: the Sun's heliosphere?
[40:27] Speaker 3: It's a very real possibility.
[40:28] Speaker 2: Does it strip away the magnetic bubble that protects the Earth.
[40:31] Speaker 2: Does it drastically change the amount of high energy cosmic
[40:34] Speaker 2: radiation bombarding the Ear's atmosphere. Would a million year journey
[40:37] Speaker 2: through an unstable shell trigger ice ages or alter the
[40:40] Speaker 2: evolution of life on our planet.
[40:42] Speaker 3: It's entirely possible that the weather of the space between
[40:44] Speaker 3: the stars actually shapes the history and the future of
[40:47] Speaker 3: the life around the stars.
[40:48] Speaker 2: It is a staggering, humbling reality to confront. We are
[40:52] Speaker 2: just a tiny, fragile ship sailing through a churning, invisible,
[40:57] Speaker 2: infinitely powerful.
[40:58] Speaker 3: Ocean, and thanks to this new three D fives thermal map.
[41:00] Speaker 3: We finally, for the first time in human history, have
[41:04] Speaker 3: a true chart of the waters we are sailing through.
[41:07] Speaker 2: So tonight, do me a favor. Go outside, step away
[41:10] Speaker 2: from the street lights, look up at the night sky,
[41:13] Speaker 2: and when your brain tries to tell you that the
[41:15] Speaker 2: blackness between those brilliant pinpoint diamonds of light is avoid
[41:19] Speaker 2: ignore it. Erase the vacuum from your mind. I want
[41:22] Speaker 2: you to look up and see the cosmic clay. Visualize
[41:25] Speaker 2: the churning, boiling, in visible ocean of gas. See the quiet,
[41:28] Speaker 2: serene nurseries tightly wrapped in violent protective storms. See the
[41:32] Speaker 2: weather of the universe is all right there, swirling around us.
[41:36] Speaker 2: Finally brought into light,

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