WEBVTT

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<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos

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<v Speaker 1>with our soothing Bedtime Astronomy podcast. Each episode offers a

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<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for

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<v Speaker 1>unwinding after a long day. Let's travel through the mysteries

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<v Speaker 1>of the universe as you drift off into a peaceful

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<v Speaker 1>slumber under the night sky.

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<v Speaker 2>So imagine you are looking up at the night sky,

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<v Speaker 2>You're just taking in all those stars, and you suddenly

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<v Speaker 2>realize that for decades, astronomers have been staring directly at

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<v Speaker 2>a massive, completely missing piece of a cosmic puzzle.

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<v Speaker 3>Right, it's a massive blind spot. We've essentially been trying

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<v Speaker 3>to understand the deep ocean by you only looking at

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<v Speaker 3>the bioluminescent algae glowing on the surface.

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<v Speaker 2>Exactly and just completely ignoring the water itself. Which sounds absurd,

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<v Speaker 2>but that is basically what we've been doing when we

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<v Speaker 2>look back at the early universe.

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<v Speaker 3>Yeah, we have. I've always known the early universe had

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<v Speaker 3>to be absolutely saturated with hydrogen gas. I mean, it's

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<v Speaker 3>the fundamental building block.

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<v Speaker 2>Of everything, right, It's what makes up the stars, which

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<v Speaker 2>then forged the heavier elements that make planets and well.

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<v Speaker 3>Us exactly, but actually finding that foundational hydrogen out there

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<v Speaker 3>in the deep dark that has been honestly one of

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<v Speaker 3>the most frustrating optical illusions in modern astrophysics.

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<v Speaker 2>And that's exactly what we're getting into today. We're traveling

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<v Speaker 2>back roughly eleven point three billion years to uncover how

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<v Speaker 2>a really revolutionary telescope project finally illuminated the dark.

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<v Speaker 3>Yeah, and they didn't just find a little bit of

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<v Speaker 3>this missing gas either.

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<v Speaker 2>No, not at all. They revealed tens of thousands of

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<v Speaker 2>these gigantic, glowing clouds of hydrogen structures that are rewriting

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<v Speaker 2>our whole understanding of how the cosmos grew up.

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<v Speaker 3>It really is a complete paradigm shift because seeing this

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<v Speaker 3>invisible stuff, it doesn't just require looking harder at the.

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<v Speaker 2>Sky, right. You can't just stare longer, exactly.

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<v Speaker 3>You have to look fundamentally differently. It requires a total

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<v Speaker 3>shift in how we capture and process the light of

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<v Speaker 3>the universe.

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<v Speaker 2>But to really get why finding this hydrogen is such

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<v Speaker 2>a monumental breakthrough, I think we first need to understand

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<v Speaker 2>why everyone was so desperately looking for it to begin with.

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<v Speaker 3>That's a good point we have to go back to

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<v Speaker 3>a very specific, incredibly chaotic era in the universe's timeline.

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<v Speaker 2>Right, the era cosmologists call cosmic.

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<v Speaker 3>Noon, Yeah, cosmic noun. So if we want to understand

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<v Speaker 3>the universe we live in today, like our mature, relatively

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<v Speaker 3>quiet Milky Way, we have to look back to those formative.

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<v Speaker 2>Years, the wild teenage years of the universe.

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<v Speaker 3>Exactly. We are talking about a period roughly ten billion

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<v Speaker 3>to twelve billion years ago in astronomical terms, that corresponds

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<v Speaker 3>to a redshift of about two to three Okay.

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<v Speaker 2>And why cosmic noon specifically.

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<v Speaker 3>Because this was the absolute peak of the universe's star

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<v Speaker 3>forming day. The universe was only about two to three

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<v Speaker 3>billion years.

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<v Speaker 2>Old at that point, so still pretty young.

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<v Speaker 3>Very young. And this was the era when galaxies were rowing,

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<v Speaker 3>merging and forming stars at their absolute fastest rates.

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<v Speaker 2>To give some context for that, our Milky Way currently

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<v Speaker 2>forms about one solar mass, so one sun's worth of

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<v Speaker 2>new stars per year.

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<v Speaker 3>Right, It's pretty sedate now, But during cosmic Noon, some

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<v Speaker 3>of these early starburst galaxies were churning out hundreds, even

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<v Speaker 3>thousands of solar masses per year.

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<v Speaker 2>Thousands a year.

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<v Speaker 3>Yeah, it was an epoch of just explosive, unparalleled cosmic construction.

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<v Speaker 2>Just pause and think about that scale for a second.

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<v Speaker 2>The light from those galaxies has been traveling through the

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<v Speaker 2>vacuum of space for over eleven billion years just to

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<v Speaker 2>reach our telescopes.

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<v Speaker 3>It's ancient history playing out right in front of us.

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<v Speaker 3>We are seeing these systems in their absolute prime.

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<v Speaker 2>But here is the crux of the whole problem. Right,

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<v Speaker 2>Galaxies don't just magically expand out of nowhere.

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<v Speaker 3>No, they definitely do not. Star formation requires fuel, Right.

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<v Speaker 2>A galaxy doesn't just decide to double its size and

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<v Speaker 2>spawn a thousand new stars out of empty space.

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<v Speaker 3>Exactly. It requires massive, really dense molecular clouds to gravitationally collapse,

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<v Speaker 3>and the raw building block for those clouds is hydrogen gas.

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<v Speaker 2>So to sustain that kind of insane explosive growth across

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<v Speaker 2>the universe, there had to be vast reservoirs of hydrogen feeding.

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<v Speaker 3>Them, vast easily accessible oceanic reservoirs. Because if a galaxy

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<v Speaker 3>is churning out one thousand stars a year, it is

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<v Speaker 3>burning through its internal gas reserves incredibly.

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<v Speaker 2>Fast, like a cosmic teenage growth spurt.

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<v Speaker 3>That is the perfect analogy.

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<v Speaker 2>Right, because if you have a teenager growing that fast,

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<v Speaker 2>they're constantly emptying the refrigerator. They need thousands of calories

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<v Speaker 2>a day just to maintain it.

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<v Speaker 3>Exactly without a constant influx of fresh gas from the

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<v Speaker 3>surrounding environment, those galaxies would just.

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<v Speaker 2>Quench quench, meaning they just burn out.

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<v Speaker 3>Yeah, they would run out of fuel and stop forming

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<v Speaker 3>stars entirely in a matter of a few tens of

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<v Speaker 3>millions of years, which is just a blink of an

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<v Speaker 3>eye in cosmic terms.

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<v Speaker 2>So, if we knew these early galaxies were growing at

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<v Speaker 2>record breaking speeds, and we knew they had to be

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<v Speaker 2>pulling in unfathomable amounts of hydrogen to feed that growth,

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<v Speaker 2>how could we possibly misplace the refrigerators?

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<v Speaker 3>That's the billion dollar question. How do you lose something

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<v Speaker 3>that massive?

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<v Speaker 2>Right Where was all the hydrogen?

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<v Speaker 3>Well, the answer lies in the deeply frustrating physics of

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<v Speaker 3>neutral hydrogen itself. It's not that we misplace the gas.

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<v Speaker 3>They're siding completely dark. To our standard methods of observation,

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<v Speaker 3>hydrogen gas in the early universe, especially in the vast

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<v Speaker 3>spaces between galaxies, the intercalactic medium is mostly cold.

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<v Speaker 2>And neutral, meaning it doesn't generate its own visible light, right.

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<v Speaker 3>It just sits there, invisible against the black background of space.

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<v Speaker 3>To actually see it, you need a very specific physical

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<v Speaker 3>interaction with an intense energy source.

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<v Speaker 2>It essentially needs to be eliminated by the galaxy it's surrounding, exactly.

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<v Speaker 3>But it's not simply reflecting light like a mirror. It's

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<v Speaker 3>a quantum physical process.

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<v Speaker 2>Okay, let's break that down.

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<v Speaker 3>So it requires a galaxy packed full of massive, young

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<v Speaker 3>hot stars that are just blasting out extreme ultraviolet radiation debeators. Right.

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<v Speaker 3>When those highly energetic UV photons hit the cold, neutral

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<v Speaker 3>hydrogen gas surrounding the galaxy, they interact with the hydrogen atoms.

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<v Speaker 2>And the hydrogen atoms is one proton and one electron, right, very.

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<v Speaker 3>Simple, very simple. So the UV photon transfers its energy

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<v Speaker 3>to that single electron, bumping it up to a higher

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<v Speaker 3>energy state.

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<v Speaker 2>It gets excited exactly, but.

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<v Speaker 3>It can't stay in that excited state forever. When the

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<v Speaker 3>electron inevitably drops back down to its original ground state,

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<v Speaker 3>it releases that stored.

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<v Speaker 2>Energy, and that release is what we can actually see.

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<v Speaker 3>Yes, it emits a photon at a very specific, highly

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<v Speaker 3>precise wavelength down to the decimal one hundred and twenty

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<v Speaker 3>one point six nanometers one.

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<v Speaker 2>Hundred and twenty one point six nanometers, and that specific

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<v Speaker 2>wavelength is what astronomers are always hunting for.

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<v Speaker 3>Precisely in astrophysics, this emission is known as the Liman.

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<v Speaker 2>Alpha line Limon alpha. Okay.

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<v Speaker 3>And when you have an entire massive cloud of hydrogen

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<v Speaker 3>doing this all at once, absorbing UV light and re

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<v Speaker 3>emitting it at one hundred and twenty one point six nanimeters,

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<v Speaker 3>the entire cloud begins to glow.

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<v Speaker 2>Which creates what astronomers call Liman alpha nebulae exactly. Okay,

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<v Speaker 2>so let me try and synthesize this. It sounds like

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<v Speaker 2>an invisible ink scenario, but you know, playing out in

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<v Speaker 2>three dimensions on a cosmic scale.

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<v Speaker 3>I like that invisible ink.

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<v Speaker 2>The neutral hydrogen gas is the invisible ink, permeated all

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<v Speaker 2>throughout the early universe. It's everywhere but completely undetectable until

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<v Speaker 2>someone shines a specific UV black light on it.

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<v Speaker 3>Right. The hyperactive Young galaxy is the black light, and that.

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<v Speaker 2>Activates the ink, causing it to glow at that Liman

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<v Speaker 2>alpha wavelength.

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<v Speaker 3>That's a great starting point, but it's actually even more

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<v Speaker 3>chaotic than just shining a black light on a page.

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<v Speaker 2>Oh, how so.

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<v Speaker 3>Because when that liman alpha photon is emitted by the

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<v Speaker 3>relaxing electron, it doesn't just travel in a nice straight

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<v Speaker 3>line toward our telescopes. Why not, Because the surrounding cloud

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<v Speaker 3>is made of the exact same hydrogen atoms, So that

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<v Speaker 3>newly emitted photon almost immediately hits another hydrogen atom, excites

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<v Speaker 3>it and gets re emitted in a totally random direction. Wow,

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<v Speaker 3>And then it hits another one and another. It's a

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<v Speaker 3>process called resonance scattering.

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<v Speaker 2>So it's bouncing around them like.

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<v Speaker 3>A pinball in a machine. It can bounce around inside

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<v Speaker 3>that massive gas cloud for thousands of years, just trapped

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<v Speaker 3>in the fog. Exactly. By the time the photon finally

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<v Speaker 3>escapes the outer edge of the cloud and begins it's

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<v Speaker 3>eleven billion year journey toward Earth, the light has been

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<v Speaker 3>completely diffused, which explains.

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<v Speaker 2>Why these structures don't look like sharp, crisp rings of light.

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<v Speaker 2>They look like massive, blurry, glowing halos, the morphous halos. Yes, okay,

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<v Speaker 2>that pinball effect makes perfect sense. But wait, I have

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<v Speaker 2>to push back on the historical timeline here for a second. Sure,

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<v Speaker 2>if we have understood the quantum mechanics of this Linman

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<v Speaker 2>alpha line for decades, and we knew about these glowing halos.

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<v Speaker 2>Why did it take until now to map them out?

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<v Speaker 3>That is the big question.

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<v Speaker 2>I mean, we have the James web Space Telescope sitting

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<v Speaker 2>out there right now. It is the most sensitive advanced

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<v Speaker 2>optical technology humanity has ever built. Why couldn't JWST just

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<v Speaker 2>sweep the sky and find all of this invisible ink?

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<v Speaker 3>Because of a fundamental trade off in astronomical optics. It's

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<v Speaker 3>the battle of depth versus.

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<v Speaker 2>Breadth, depth versus breath. Okay, explain that.

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<v Speaker 3>You're absolutely right that JWST is phenomenal. Its sensitivity is unmatched.

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<v Speaker 3>But JWST is essentially a hyper powered microscope.

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<v Speaker 2>So its field of view is tiny.

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<v Speaker 3>Incredibly tiny. The actual chunk of the sky it can

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<v Speaker 3>see at any given moment is minuscule. If you wanted

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<v Speaker 3>to map a statistically significant portion of the early universe

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<v Speaker 3>using JOUST, it would take millennia of continuous observation.

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<v Speaker 2>Time millenniaow, So it's just not practical for sweeping surveys.

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<v Speaker 3>Not at all. JWST is designed to stare deeply at individual,

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<v Speaker 3>pre selected targets it's not meant to blindly survey massive

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<v Speaker 3>swaths of empty space.

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<v Speaker 2>So JWST is like taking a macro lens close up

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<v Speaker 2>of a single pour on someone's skin. You get amazing detail,

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<v Speaker 2>but you completely miss the rest of the face, let

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<v Speaker 2>alone the room they are standing in.

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<v Speaker 3>That's spot on, and previous astronomical surveys were trapped by

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<v Speaker 3>this dual problem.

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<v Speaker 2>What do you mean by dual problem?

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<v Speaker 3>Well, on one hand, older wider field instruments simply lacked

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<v Speaker 3>the sensitivity to pick up the incredibly faint liman alpha emissions.

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<v Speaker 2>So they were looking wide, but they couldn't see the

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<v Speaker 2>dim stuff right.

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<v Speaker 3>They could only catch the absolute brightest, most extreme outlier

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<v Speaker 3>examples of these halos, usually the ones illuminated by hyper

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<v Speaker 3>luminous quasars.

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<v Speaker 2>And they missed the normal stuff entirely exactly.

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<v Speaker 3>And on the other hand, highly sensitive telescopes like Hubble

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<v Speaker 3>and now JWST were so zoomed in on the central

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<v Speaker 3>galaxies themselves that they inadvertently cropped out the surrounding environment.

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<v Speaker 2>Oh, they were staring so intensely at the uv black

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<v Speaker 2>light that they missed the ink spreading out into the

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<v Speaker 2>dark around it.

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<v Speaker 3>Precisely the vast middle ground. The normal, everyday hydrogen halos

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<v Speaker 3>that surrounded the majority of typical galaxies during cosmic noon

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<v Speaker 3>remain entirely hidden, so they were.

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<v Speaker 2>Either two zoomed in or just not sensitive enough.

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<v Speaker 3>Right. To solve the problem of missing that middle ground,

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<v Speaker 3>astronomers realized they couldn't just build a bigger, conventional telescope.

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<v Speaker 2>They needed a totally different kind of tool.

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<v Speaker 3>They needed an instrument that could simultaneously look at massive

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<v Speaker 3>areas of the sky while also dissecting the light with

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<v Speaker 3>enough precision to pick out that exact one hundred and

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<v Speaker 3>twenty one point six ninimeter Lineman alpha wavelength.

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<v Speaker 2>Against all the noisy background of space.

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<v Speaker 3>No less exactly, And that crazy engineering requirement is what

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<v Speaker 3>birthed the instrument we're talking about today, eighth eight decads.

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<v Speaker 2>Located at the McDonald Observatory in West Texas.

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<v Speaker 3>Right, the Hobby Eberly Telescope Dark Energy Experiment.

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<v Speaker 2>Let's unpack eh dicks because the name itself is super interesting.

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<v Speaker 2>It's the dark energy Experiment. But we are talking about

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<v Speaker 2>revolutionizing our map of hydrogen gas. Right. How did a

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<v Speaker 2>project build to study dark energy end up solving the

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<v Speaker 2>mystery of the universe's missing hydrogen refrigerators.

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<v Speaker 3>It's one of those great stories of scientific cross pollination.

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<v Speaker 3>The primary goal of HX really was to study dark energy.

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<v Speaker 2>That mysterious force accelerating the expansion of the universe.

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<v Speaker 3>Exactly, to measure the effects of dark energy over time,

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<v Speaker 3>cosmologists need to map the precise three D positions of

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<v Speaker 3>millions of distant objects. They need to see how the

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<v Speaker 3>fabric of space has stretched.

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<v Speaker 2>So they need a reliable marker to map the grid.

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<v Speaker 3>Yes, a tracer, and the most abundant reliable tracers at

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<v Speaker 3>that specific distance eleven billion light years away are galaxies

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<v Speaker 3>that emit strongly in the Liman alpha line.

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<v Speaker 2>Ah, so the Liman alpha emitters yes laees.

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<v Speaker 3>To build a map of dark energy, they first had

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<v Speaker 3>to build a map of these hydrogen glowing galaxies.

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<v Speaker 2>The hydrogen was just the ink they were using to

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<v Speaker 2>draw the grid lines of the universe's.

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<v Speaker 3>Expansion, That's exactly it. But to build that map, they

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<v Speaker 3>had to engineer an instrument with capabilities that are genuinely staggering.

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<v Speaker 2>Because hate X isn't just snapping pretty pig the sky right, No.

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<v Speaker 3>Not at all. It is actively capturing and analyzing the

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<v Speaker 3>spectra of over one million galaxies.

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<v Speaker 2>A million galaxies. That's insane, it.

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<v Speaker 3>Really is, and the way it does this is a

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<v Speaker 3>marvel of modern engineering. They equipped the telescope with an

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<v Speaker 3>instrument called.

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<v Speaker 2>VIRUS VIRUS, which stands for the Visible Integral Field Replicable

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<v Speaker 2>Unit Spectrograph. Astrotomers really do have a unique talent for

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<v Speaker 2>forcing acronyms, don't they.

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<v Speaker 3>Oh, they absolutely do. It's practically a requirement in astrophysics.

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<v Speaker 3>But the technology behind VIRUS is incredible.

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<v Speaker 2>How does it actually work.

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<v Speaker 3>It consists of over one hundred and fifty individual spectrographs.

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<v Speaker 3>When the telescope points at a patch of sky, it

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<v Speaker 3>doesn't just take one measurement. It utilizes an array of

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<v Speaker 3>thirty five thousand optical fibers. Thirty five thousand, yes, think

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<v Speaker 3>of them as tiny, highly precise light pipes. Each fiber

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<v Speaker 3>captures the light from a tiny specific point in the

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<v Speaker 3>sky and feeds it into the spectrograph.

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<v Speaker 2>A spectrograph acts kind of like a.

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<v Speaker 3>Prism, exactly like a highly advanced prism. It takes the

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<v Speaker 3>incoming light and stretches it out into its constituent wavelengths,

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<v Speaker 3>creating a spectrum.

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<v Speaker 2>So they can look at that spectrum and hunt for

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<v Speaker 2>that exact spike in intensity at the Liman alpha wavelength exactly.

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<v Speaker 3>But there's a catch. Because the universe is expanding, that

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<v Speaker 3>one hundred and twenty one point six nanimeter light gets

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<v Speaker 3>stretched out as it travels to.

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<v Speaker 2>Us the cosmological redshift.

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<v Speaker 3>Right by the time that ultraviolet photon reaches West Texas

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<v Speaker 3>eleven billion years later, it has been stretched all the

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<v Speaker 3>way into the visible blue or green part of the spectrum.

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<v Speaker 2>So by measuring exactly how much the light has been

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<v Speaker 2>stretched into the blue or green htdd X can determine

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<v Speaker 2>exactly how far away the gas is Precisely.

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<v Speaker 3>It gives them the three D position of the gas cloud,

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<v Speaker 3>not just a two D coordinate.

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<v Speaker 2>So instead of just taking a flat photograph, they are

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<v Speaker 2>taking a deep three D core sample of the universe. Yes,

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<v Speaker 2>but the scale of what they're doing is what truly

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<v Speaker 2>blows my mind. The researchers noted that the footprint of

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<v Speaker 2>this observation area covers a region of the sky measuring

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<v Speaker 2>over two thousand and full moons.

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<v Speaker 3>It's massive.

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<v Speaker 2>Just think about that. When you look at the moon,

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<v Speaker 2>it takes up a tiny fraction of a degree in

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<v Speaker 2>the sky. Imagine painting two thousand of them across the dark.

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<v Speaker 3>Right, It's unparalleled coverage.

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<v Speaker 2>This isn't just moving from looking through a straw to

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<v Speaker 2>opening at bay window. This is knocking down the entire

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<v Speaker 2>wall of the observatory.

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<v Speaker 3>And because of that massive footprint, combined with those thirty

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<v Speaker 3>five thousand optical fibers, h et Dex produces one hundred

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<v Speaker 3>thousand distinct spectra in a single observation, one hundred thousand

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<v Speaker 3>in a single shot. The raw data generation is mind boggling.

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<v Speaker 3>Over the course of the survey, we are talking about

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<v Speaker 3>capturing nearly half a petabite of raw observational data.

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<v Speaker 2>Half a petabite, so a petabyte is a thousand terabytes, right.

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<v Speaker 3>Imagine a massive data center full of the largest commercial

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<v Speaker 3>hard drives available, completely filled with nothing but raw light frequencies.

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<v Speaker 2>Processing that much data has to require a massive leap

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<v Speaker 2>in computational power. I mean, you can't just have a

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<v Speaker 2>team of grad students eyeballing a million spectra looking for

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<v Speaker 2>a little Linman alpha spike.

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<v Speaker 3>No, absolutely not. It's not just finding a needle in

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<v Speaker 3>a haystack. It's like programming a system to sort through

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<v Speaker 3>a million haystacks and identify only the specific needles that

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<v Speaker 3>are vibrating at one exact frequency.

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<v Speaker 2>So how did they do it?

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<v Speaker 3>Well, The astronomical data pipeline is just as important as

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<v Speaker 3>the telescope itself. To sift through that half a petabyte

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<v Speaker 3>of data, the HPDX team utilized massive supercomputers.

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<v Speaker 2>At the Texas Advanced Computing Center, right.

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<v Speaker 3>Yeah, Specifically they're Fronterra and Stampede systems. They had to

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<v Speaker 3>design highly sophisticated algorithms that could automatically clean the data.

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<v Speaker 2>Cleaned it how.

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<v Speaker 3>By subtracting the noise of our own atmosphere, filtering out

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<v Speaker 3>closer foreground galaxies that were contaminating the image, basically isolating

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<v Speaker 3>only the distant early galaxies.

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<v Speaker 2>So, out of the one point six million early galaxies

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<v Speaker 2>they eventually identified in the overall data, how many did

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<v Speaker 2>they focus on for this specific breakthrough?

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<v Speaker 3>The supercomputers filtered that down to focus on the seventy

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<v Speaker 3>thousand brightest ones.

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<v Speaker 2>Okay, so the bay window is open, the thirty five

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<v Speaker 2>thousand optical fibers are pulling down the light, and the

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<v Speaker 2>supercomputers are crunching the spectra of these seventy thousand prime targets, right,

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<v Speaker 2>What exactly did they see swimming out there in the

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<v Speaker 2>cosmic ocean. When they finally looked closely at the empty

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<v Speaker 2>spaces between the galaxies, they.

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<v Speaker 3>Saw the physical manifestation of the universe's fuel lines. They

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<v Speaker 3>found the massive hydrogen halos that had been hiding in

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<v Speaker 3>planes sight this whole time.

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<v Speaker 2>What did that actually look like in the data?

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<v Speaker 3>The supercomputers were specifically trained to look for a distinct

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<v Speaker 3>structural signature, a highly compact central region of intensely glowing hydrogen,

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<v Speaker 3>which is the galaxy itself, okay, and that central region

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<v Speaker 3>is completely surrounded by a thinner, much more expansive, diffuse

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<v Speaker 3>cloud of lime and alpha mission extending far out into

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<v Speaker 3>the deep space around it and out.

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<v Speaker 2>Of the seventy thousand galaxies, they looked at how many

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<v Speaker 2>had this signature.

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<v Speaker 3>Nearly half of them showed clear, indisputable evidence of this

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<v Speaker 3>surrounding hydrogen halo.

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<v Speaker 2>Nearly half. That is a staggering hit rate, it really is.

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<v Speaker 2>It basically means that if you randomly pointed at a

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<v Speaker 2>bright galaxy during cosmic noon, there was a coin flip

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<v Speaker 2>chance that was surrounded by this massive, invisible reservoir exactly.

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<v Speaker 2>We really need to contextualize the physical characteristics of these

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<v Speaker 2>structures because the numbers are hard to wrap the human

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<v Speaker 2>brain around. Just how big are these hydrogen halos.

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<v Speaker 3>They are immense. The newly revealed halos range in size

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<v Speaker 3>from tens of thousands to hundreds of thousands of light

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<v Speaker 3>years across.

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<v Speaker 2>Just from some local perspective, here, our entire Milky Way galaxy,

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<v Speaker 2>which contains hundreds of billions of stars, massive black holes,

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<v Speaker 2>vast stellar nurseries, all of that is roughly one hundred

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<v Speaker 2>thousand light years across.

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<v Speaker 3>Right.

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<v Speaker 2>It takes light, the fastest thing in the universe, a

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<v Speaker 2>hundred millennia, just to cross from one edge of our

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<v Speaker 2>galaxy to the other. And you're saying, some of these

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<v Speaker 2>single gas clouds are significantly larger than our entire galaxy.

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<v Speaker 3>Easily larger. But it's not just their sheer size that

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<v Speaker 3>is so groundbreaking, it is their structure. What do you

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<v Speaker 3>mean when we picture cosmic phenomena, we are super biased

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<v Speaker 3>by our local solar system. We tend to picture clean,

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<v Speaker 3>symmetrical spheres like planets or stars, or even the neat

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00:19:13.920 --> 00:19:16.799
<v Speaker 3>spiral arms of a mature galaxy, nice and tidy, right,

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00:19:17.079 --> 00:19:19.759
<v Speaker 3>but the structures they found at cosmic noon were completely

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<v Speaker 3>asymmetrical and chaotic, messy, very messy. Some of the clouds

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00:19:23.599 --> 00:19:27.319
<v Speaker 3>surrounding isolated single galaxies were relatively simple shaped, somewhat like

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<v Speaker 3>giant cosmic footballs.

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00:19:28.799 --> 00:19:30.119
<v Speaker 2>Okay, footballs, I can picture.

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00:19:30.200 --> 00:19:34.039
<v Speaker 3>But the truly fascinating discoveries were the halos surrounding groups

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<v Speaker 3>of multiple galaxies.

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00:19:35.960 --> 00:19:40.000
<v Speaker 2>Right, the sprawling, irregular blobs. I love how the researchers

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<v Speaker 2>literally describe them as giant amobas with tendrils extending into space.

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00:19:44.279 --> 00:19:47.359
<v Speaker 2>It's a great visual it is. But when an astrophysicist

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00:19:47.519 --> 00:19:53.240
<v Speaker 2>abandons neat geometric classifications and resorts to biological terms like amoeba,

397
00:19:54.279 --> 00:19:57.599
<v Speaker 2>you know they're looking at something inherently messy. Oh absolutely,

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<v Speaker 2>What is the physical mechanism eating these tendrils? I mean,

399
00:20:01.559 --> 00:20:04.039
<v Speaker 2>why don't they just form a massive neat sphere of

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00:20:04.119 --> 00:20:06.160
<v Speaker 2>gas under their own gravity.

401
00:20:06.400 --> 00:20:09.319
<v Speaker 3>Because what we are looking at is a highly volatile

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00:20:09.359 --> 00:20:12.799
<v Speaker 3>region known as the circungalactic medium or the CGM.

403
00:20:13.039 --> 00:20:16.000
<v Speaker 2>CGM yeah, space just outside the galaxy, right.

404
00:20:15.839 --> 00:20:18.960
<v Speaker 3>It is the dynamic battleground between the galaxy and the cosmos.

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00:20:19.119 --> 00:20:22.920
<v Speaker 3>Those tendrils are actually the physical manifestation of the cosmic

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00:20:22.960 --> 00:20:25.359
<v Speaker 3>web itself. How so, well, the universe isn't just a

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00:20:25.440 --> 00:20:29.759
<v Speaker 3>uniform soup of matter. Dark matter clumps together into massive filaments,

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00:20:29.759 --> 00:20:33.000
<v Speaker 3>creating this huge web like structure across the universe.

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00:20:33.000 --> 00:20:35.480
<v Speaker 2>Okay, and the galaxy sit at the intersections of that web.

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00:20:35.799 --> 00:20:40.960
<v Speaker 3>Exactly, These dark matter filaments exert immense gravitational pull, funneling

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00:20:41.160 --> 00:20:46.240
<v Speaker 3>massive streams of cold, pristine hydrogen gas directly into the

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00:20:46.279 --> 00:20:48.400
<v Speaker 3>gravitational well of the galaxy.

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00:20:48.480 --> 00:20:51.559
<v Speaker 2>So the tendrils reaching outward, those are the actual fuel

414
00:20:51.599 --> 00:20:55.480
<v Speaker 2>lines pulling the gas in. Yes, the teenagers relentlessly mpying

415
00:20:55.519 --> 00:20:56.960
<v Speaker 2>the refrigerator.

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00:20:56.480 --> 00:21:00.319
<v Speaker 3>Exactly, that's the cold gas flowing in. But remember it

417
00:21:00.359 --> 00:21:01.640
<v Speaker 3>is a two way street.

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00:21:01.480 --> 00:21:03.880
<v Speaker 2>Because the galaxy is also doing something right.

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00:21:04.200 --> 00:21:07.039
<v Speaker 3>Because the galaxy is pulling all this gas and frantically

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00:21:07.079 --> 00:21:09.799
<v Speaker 3>forming stars at a rate of hundreds of solar masses

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00:21:09.839 --> 00:21:13.200
<v Speaker 3>a year, it is also experiencing massive.

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00:21:12.880 --> 00:21:14.920
<v Speaker 2>Violent feedback back from the stars.

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00:21:14.640 --> 00:21:19.119
<v Speaker 3>From the supernovae. When those massive young stars die, they explode.

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<v Speaker 3>Thousands of supernovae exploding simultaneously create immense galactic winds. These

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00:21:24.680 --> 00:21:28.680
<v Speaker 3>winds blast superheated gas, radiation and newly forged heavy elements

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00:21:28.720 --> 00:21:31.279
<v Speaker 3>back out of the galaxy and millions of miles per hour.

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00:21:31.359 --> 00:21:34.680
<v Speaker 2>And that outward blast slams into the incoming cold gas

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00:21:34.720 --> 00:21:35.720
<v Speaker 2>stream precisely.

429
00:21:36.160 --> 00:21:39.599
<v Speaker 3>It's an incredibly violent traffic jam that is wild.

430
00:21:40.000 --> 00:21:43.240
<v Speaker 2>You have gravity mercilessly pulling cold gas in along the

431
00:21:43.359 --> 00:21:49.440
<v Speaker 2>dark matter filaments, while explosive supernova feedback is aggressively blasting

432
00:21:49.480 --> 00:21:50.559
<v Speaker 2>hot gas back out.

433
00:21:50.799 --> 00:21:55.839
<v Speaker 3>It is a messy, turbulent feeding frenzy and the shockfronts,

434
00:21:56.079 --> 00:21:59.279
<v Speaker 3>the interplay between the inflows and outflows, that is what

435
00:21:59.359 --> 00:22:03.160
<v Speaker 3>creates these sprawling, amorphous amoeba like shapes.

436
00:22:03.359 --> 00:22:06.480
<v Speaker 2>So they aren't just static clouds. They are highly complex,

437
00:22:06.640 --> 00:22:08.440
<v Speaker 2>multi phase environment, very much so.

438
00:22:08.920 --> 00:22:10.759
<v Speaker 3>And the fact that we can now trace the shape

439
00:22:10.799 --> 00:22:13.640
<v Speaker 3>of these amibas gives us direct visual evidence of how

440
00:22:13.759 --> 00:22:15.079
<v Speaker 3>galaxies breathe.

441
00:22:14.759 --> 00:22:17.839
<v Speaker 2>How they inhale fuel and exhale the byproducts of stellar

442
00:22:17.839 --> 00:22:21.119
<v Speaker 2>evolution exactly. And just to keep the scale anchored for you,

443
00:22:21.480 --> 00:22:24.119
<v Speaker 2>a single wiggling tendril on one of these giant space

444
00:22:24.160 --> 00:22:27.480
<v Speaker 2>ambas could easily dwarf our entire Milky Way galaxy.

445
00:22:27.599 --> 00:22:29.079
<v Speaker 3>It's almost incomprehensible.

446
00:22:29.279 --> 00:22:33.640
<v Speaker 2>We're talking about structures so unimaginably large they defy human comprehension,

447
00:22:33.720 --> 00:22:36.200
<v Speaker 2>just churning away in the dark of cosmic noons. Yeah,

448
00:22:36.240 --> 00:22:38.720
<v Speaker 2>but you know, finding a few of these massive space

449
00:22:38.720 --> 00:22:41.480
<v Speaker 2>amvas would just be a neat curiosity fun anomenally for

450
00:22:41.519 --> 00:22:45.720
<v Speaker 2>a textbook, right, But finding a massive, sprawling population of

451
00:22:45.759 --> 00:22:50.759
<v Speaker 2>them that completely alters our statistical understanding of the universe's mechanics.

452
00:22:50.880 --> 00:22:54.319
<v Speaker 3>And that is the ultimate breakthrough of the hate TECH study.

453
00:22:54.400 --> 00:22:57.160
<v Speaker 3>It isn't just the discovery of the halos themselves, it

454
00:22:57.279 --> 00:23:00.039
<v Speaker 3>is the sheer, overwhelming volume.

455
00:23:00.119 --> 00:23:02.440
<v Speaker 2>The data put that into perspective for us. How many

456
00:23:02.480 --> 00:23:03.839
<v Speaker 2>of these did we know about before this?

457
00:23:03.920 --> 00:23:07.279
<v Speaker 3>Well, prior to this release, our entire known catalog of

458
00:23:07.319 --> 00:23:11.200
<v Speaker 3>these massive hydrogen halos, built up painstakingly over twenty years

459
00:23:11.200 --> 00:23:14.519
<v Speaker 3>of targeted observations, was roughly three thousand.

460
00:23:14.200 --> 00:23:16.839
<v Speaker 2>Okay three thousand, and After HATESECH, thanks.

461
00:23:16.720 --> 00:23:20.000
<v Speaker 3>To the massive blind sweep of the survey, that number

462
00:23:20.079 --> 00:23:22.119
<v Speaker 3>jumped to over thirty three thousand.

463
00:23:22.039 --> 00:23:25.200
<v Speaker 2>A tenfold increase overnight overnight. That is the kind of

464
00:23:25.200 --> 00:23:28.920
<v Speaker 2>statistical leap that fundamentally changes a whole scientific field.

465
00:23:29.079 --> 00:23:32.599
<v Speaker 3>It is absolutely crucial because a leap of that magnitude

466
00:23:32.640 --> 00:23:35.880
<v Speaker 3>proves definitively that these halos are not rare anomalies.

467
00:23:36.000 --> 00:23:39.119
<v Speaker 2>They aren't just weird cosmic curiosities that only happen under

468
00:23:39.119 --> 00:23:39.920
<v Speaker 2>freak conditions.

469
00:23:40.000 --> 00:23:43.079
<v Speaker 3>Right. They aren't just forming near hyper luminous quasars. They

470
00:23:43.119 --> 00:23:46.480
<v Speaker 3>are a fundamental standard feature of the early universe.

471
00:23:46.759 --> 00:23:49.880
<v Speaker 2>So if you were a normal star forming galaxy growing

472
00:23:49.960 --> 00:23:52.799
<v Speaker 2>up during cosmic noon, you almost certainly had one of

473
00:23:52.839 --> 00:23:56.480
<v Speaker 2>these massive glowing hydrogen amibas surrounding you.

474
00:23:56.839 --> 00:24:00.279
<v Speaker 3>It was the default state of galactic evolution. But what

475
00:24:00.400 --> 00:24:04.000
<v Speaker 3>is even more staggering is that the researchers readily admit

476
00:24:04.079 --> 00:24:07.559
<v Speaker 3>that thirty three thousand is a severe underestimate of the

477
00:24:07.680 --> 00:24:08.759
<v Speaker 3>true population.

478
00:24:09.079 --> 00:24:13.160
<v Speaker 2>Wait, how so if the supercomputers just found thirty thousand

479
00:24:13.240 --> 00:24:15.599
<v Speaker 2>new ones in the data, how could they still be

480
00:24:15.640 --> 00:24:17.400
<v Speaker 2>missing a significant portion of them?

481
00:24:17.519 --> 00:24:21.079
<v Speaker 3>Because we are still limited by the physics of the invisible.

482
00:24:20.599 --> 00:24:22.799
<v Speaker 2>Ink ah the black light effect. Right.

483
00:24:22.880 --> 00:24:25.359
<v Speaker 3>Remember, the hydrogen only glows when it is hit by

484
00:24:25.480 --> 00:24:28.000
<v Speaker 3>enough ultraviolet radiation from the central galaxy.

485
00:24:28.160 --> 00:24:30.480
<v Speaker 2>So what happens with the fainter galaxies.

486
00:24:30.039 --> 00:24:32.319
<v Speaker 3>The faintest systems in the survey, the ones that are

487
00:24:32.319 --> 00:24:35.599
<v Speaker 3>forming stars but maybe not at the extreme frantic rates

488
00:24:35.599 --> 00:24:38.920
<v Speaker 3>of the brightest ones. They simply aren't producing quite enough

489
00:24:39.000 --> 00:24:42.759
<v Speaker 3>blinding UV light to fully illuminate the massive halo surrounding them.

490
00:24:42.880 --> 00:24:45.319
<v Speaker 2>So the central galaxy is acting as a black light,

491
00:24:45.759 --> 00:24:48.079
<v Speaker 2>but the bulb just isn't strong enough to light up

492
00:24:48.079 --> 00:24:48.920
<v Speaker 2>the outer edges of.

493
00:24:48.920 --> 00:24:52.920
<v Speaker 3>The room exactly. The gas is physically there, continuing to

494
00:24:52.920 --> 00:24:56.519
<v Speaker 3>feed the galaxy, but the resonant scattering of the liman

495
00:24:56.599 --> 00:25:00.880
<v Speaker 3>alpha photons drops below the detection threshold of instruments.

496
00:25:01.039 --> 00:25:04.400
<v Speaker 2>So even with thirty three thousand confirm there's a massive

497
00:25:04.440 --> 00:25:07.160
<v Speaker 2>population of halos out there where we are only seeing

498
00:25:07.200 --> 00:25:11.200
<v Speaker 2>the very core, missing the sprawling tendrils entirely, without a doubt.

499
00:25:11.240 --> 00:25:13.839
<v Speaker 2>It is such a brilliant example of the scientific method

500
00:25:13.839 --> 00:25:16.759
<v Speaker 2>in action, and it completely shifts the burden over to

501
00:25:16.799 --> 00:25:18.880
<v Speaker 2>the theoretical side of astrophysics, doesn't it.

502
00:25:18.960 --> 00:25:19.759
<v Speaker 3>Oh completely?

503
00:25:19.839 --> 00:25:22.640
<v Speaker 2>I mean, for years, cosmologists have been running these incredibly

504
00:25:22.680 --> 00:25:27.160
<v Speaker 2>complex supercomputer simulations of how the universe evolved. They built

505
00:25:27.160 --> 00:25:31.039
<v Speaker 2>these models for cosmic noon based on the physics they understood.

506
00:25:30.599 --> 00:25:33.400
<v Speaker 3>But they admittedly had massive gaps and holes.

507
00:25:33.079 --> 00:25:36.359
<v Speaker 2>Because they were forced to base their assumptions on a

508
00:25:36.440 --> 00:25:41.440
<v Speaker 2>highly biased sample of just three thousand extreme exceptionally bright outliers.

509
00:25:41.559 --> 00:25:45.680
<v Speaker 3>Right, and now suddenly they have a robust catalog of

510
00:25:45.759 --> 00:25:48.880
<v Speaker 3>thirty three thousand normal representative examples.

511
00:25:48.960 --> 00:25:51.519
<v Speaker 2>The problem has entirely shifted from the agony of finding

512
00:25:51.599 --> 00:25:55.359
<v Speaker 2>these structures to the overwhelming paralysis of processing them. Is

513
00:25:55.400 --> 00:25:59.960
<v Speaker 2>it terrifying for a theoretical astrophysicist to wake up, look

514
00:26:00.160 --> 00:26:03.680
<v Speaker 2>this massive data dump from a DEX and realize they

515
00:26:03.759 --> 00:26:07.720
<v Speaker 2>might have to essentially scrap or radically alter their old

516
00:26:07.759 --> 00:26:09.200
<v Speaker 2>models and start all over again.

517
00:26:09.240 --> 00:26:13.839
<v Speaker 3>Honestly, far from terrifying. It is absolutely thrilling. Really, oh yeah,

518
00:26:13.880 --> 00:26:17.279
<v Speaker 3>this is the moment every scientist hopes for. The apprehension

519
00:26:17.319 --> 00:26:20.599
<v Speaker 3>of finding out your old model was incomplete is immediately

520
00:26:20.640 --> 00:26:24.279
<v Speaker 3>replaced by the excitement of having a clear, highly detailed

521
00:26:24.319 --> 00:26:25.880
<v Speaker 3>map of reality to replace it with.

522
00:26:26.039 --> 00:26:26.920
<v Speaker 2>I guess that makes sense.

523
00:26:27.200 --> 00:26:30.240
<v Speaker 3>The old models had gaps because theorists were forced to

524
00:26:30.279 --> 00:26:33.680
<v Speaker 3>extrapolate what the vast middle ground look like based purely

525
00:26:33.759 --> 00:26:35.279
<v Speaker 3>on the extremes.

526
00:26:34.960 --> 00:26:39.319
<v Speaker 2>Like trying to understand human biology by only studying Olympic weightlifters.

527
00:26:39.400 --> 00:26:41.480
<v Speaker 3>That's a perfect way to put it. Now, the ATDEX

528
00:26:41.559 --> 00:26:45.839
<v Speaker 3>catalog provides a massive representative sample of general population. This

529
00:26:45.960 --> 00:26:48.799
<v Speaker 3>is basically the holy grail for cosmologists.

530
00:26:48.160 --> 00:26:50.880
<v Speaker 2>Because they can finally run real statistical analysis. They aren't

531
00:26:50.920 --> 00:26:51.559
<v Speaker 2>guessing anymore.

532
00:26:51.680 --> 00:26:55.960
<v Speaker 3>Exactly. With thirty three thousand distinct data points, astronomers can

533
00:26:56.039 --> 00:26:59.759
<v Speaker 3>utilize advanced statistical techniques like cross correlation.

534
00:26:59.400 --> 00:27:00.960
<v Speaker 2>Functions, and what do they let them do?

535
00:27:01.240 --> 00:27:05.279
<v Speaker 3>They can mathematically analyze how these halos cluster together. They

536
00:27:05.279 --> 00:27:07.799
<v Speaker 3>can map out exactly how the dark matter must be

537
00:27:07.880 --> 00:27:11.440
<v Speaker 3>distributed to hold these massive gas clouds together against the

538
00:27:11.480 --> 00:27:13.519
<v Speaker 3>explosive outflow of the supernovae.

539
00:27:13.559 --> 00:27:16.359
<v Speaker 2>They can study the actual physics, the real world movement

540
00:27:16.400 --> 00:27:17.279
<v Speaker 2>of the gas yes.

541
00:27:17.519 --> 00:27:20.559
<v Speaker 3>And track the evolutionary life cycles of these structures in

542
00:27:20.640 --> 00:27:24.279
<v Speaker 3>granular detail. They can finally see how a simple football

543
00:27:24.319 --> 00:27:29.680
<v Speaker 3>shaped halo surrounding an isolated galaxy eventually evolves, merges, and

544
00:27:29.720 --> 00:27:33.759
<v Speaker 3>warps into a massive multi galaxy amba over millions of years.

545
00:27:33.880 --> 00:27:36.759
<v Speaker 2>They finally have the hard numbers to ground their simulations

546
00:27:36.799 --> 00:27:38.000
<v Speaker 2>in actual observation.

547
00:27:38.319 --> 00:27:39.359
<v Speaker 3>It's game changing.

548
00:27:39.519 --> 00:27:42.720
<v Speaker 2>It really is an epic journey of scientific discovery. I mean,

549
00:27:42.759 --> 00:27:46.160
<v Speaker 2>we started at a point where the universe's primary hydrogen reservoirs,

550
00:27:46.519 --> 00:27:49.839
<v Speaker 2>the very cosmic fuel that built the stars, that eventually

551
00:27:49.880 --> 00:27:52.440
<v Speaker 2>forge the carbon and oxygen that make up our bodies,

552
00:27:52.759 --> 00:27:54.160
<v Speaker 2>were just a theoretical.

553
00:27:53.799 --> 00:27:55.599
<v Speaker 3>Necessity right a mathematical assumption.

554
00:27:55.759 --> 00:27:58.599
<v Speaker 2>We logically knew the early galaxies had to be consuming

555
00:27:58.599 --> 00:28:01.799
<v Speaker 2>massive amounts of gas, but the reservoirs themselves were completely

556
00:28:01.880 --> 00:28:05.960
<v Speaker 2>hidden in the dark, invisible to our standard telescopes, and we.

557
00:28:05.960 --> 00:28:09.480
<v Speaker 3>Had to rethink our entire approach to find them exactly.

558
00:28:10.039 --> 00:28:13.160
<v Speaker 2>And that shift in thinking led us to the chaotic,

559
00:28:13.359 --> 00:28:18.359
<v Speaker 2>explosive era of cosmic Noon, where massive tendrilled space samibas

560
00:28:18.759 --> 00:28:22.079
<v Speaker 2>fueled the rapid, violent growth of the earliest galaxies. It's

561
00:28:22.119 --> 00:28:24.759
<v Speaker 2>quid a picture, and finally, all of this hidden architecture

562
00:28:24.799 --> 00:28:27.680
<v Speaker 2>was brought into the light, not by building a bigger

563
00:28:27.720 --> 00:28:32.000
<v Speaker 2>conventional lens, but by the sheer, brute force data crunching

564
00:28:32.039 --> 00:28:33.160
<v Speaker 2>power of heat decks.

565
00:28:33.400 --> 00:28:34.759
<v Speaker 3>That's the real hero here.

566
00:28:34.880 --> 00:28:38.599
<v Speaker 2>Deploying thirty five thousand optical fibers across a massive swathe

567
00:28:38.680 --> 00:28:41.599
<v Speaker 2>of the Texas Knight Sky, capturing half a petabite of

568
00:28:41.680 --> 00:28:45.400
<v Speaker 2>light spectra, and utilizing supercomputers to filter out the noise,

569
00:28:46.039 --> 00:28:48.079
<v Speaker 2>we finally saw the universe as it truly was.

570
00:28:48.319 --> 00:28:51.599
<v Speaker 3>It serves as a powerful reminder of how observational bias

571
00:28:51.680 --> 00:28:54.839
<v Speaker 3>shapes our understanding of reality. How so well for centuries,

572
00:28:54.880 --> 00:28:57.359
<v Speaker 3>astronomy has been defined by looking closely at the bright,

573
00:28:57.440 --> 00:29:02.039
<v Speaker 3>shiny localized objects, the star, the planet's, the dense galactic core.

574
00:29:01.960 --> 00:29:04.039
<v Speaker 2>The things that are easy to see exactly.

575
00:29:04.359 --> 00:29:08.880
<v Speaker 3>But this project demonstrates that sometimes the most profoundly important discoveries,

576
00:29:09.359 --> 00:29:12.880
<v Speaker 3>the structures that actually dictate how the universe evolves, are

577
00:29:12.880 --> 00:29:16.200
<v Speaker 3>found by having the technological capability and the scientific vision

578
00:29:16.559 --> 00:29:20.480
<v Speaker 3>to look closely at the supposedly empty dark spaces in between.

579
00:29:20.720 --> 00:29:24.440
<v Speaker 2>Wow, and that leaves us with a truly incredible lingering

580
00:29:24.480 --> 00:29:27.039
<v Speaker 2>thought to chew on. Yeah, think about this the next

581
00:29:27.039 --> 00:29:29.720
<v Speaker 2>time you were standing outside looking up at the stars

582
00:29:29.720 --> 00:29:32.839
<v Speaker 2>on a clear night. If an innovative wide field tool

583
00:29:33.039 --> 00:29:37.720
<v Speaker 2>like eighty days can fundamentally rewrite our understanding of galactic evolution,

584
00:29:38.119 --> 00:29:40.960
<v Speaker 2>increasing our knowledge of these massive structures by a factor

585
00:29:41.000 --> 00:29:44.880
<v Speaker 2>of ten, and finding thirty thousand new cosmic leviathans simply

586
00:29:44.880 --> 00:29:47.400
<v Speaker 2>by analyzing the dark spaces between the galaxies we were

587
00:29:47.440 --> 00:29:51.440
<v Speaker 2>already studying. What other massive invisible structures are currently floating

588
00:29:51.559 --> 00:29:53.920
<v Speaker 2>right in front of our telescope lenses, just waiting for

589
00:29:54.000 --> 00:29:55.480
<v Speaker 2>us to figure out the right way to see them,