The Universe is 95% Empty, and It’s Tearing Itself Apart

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2:01So, while other companies might deliver a lot of hey, zipper Cruder finds you what you're looking for. The needle in the haystack. See why four out of five employers who post a job on zipper Cruder get a quality candidate within the first day. Zipper Cruder, the smartest way to hire. And right now, you can try zipper Cruder for free. That's right. Free at zipper Cruder.com slash zip. That zipper Cruder.com slash zip zipper Cruder.com slash zip. Imagine just for a moment that you were suddenly dropped right into the very middle of a pitch black ocean. Oh, that is a terrifying thought to start with. Right, but this is in the notion of water on Earth. There is absolutely no light. Like zero. None. Just absolute darkness. Exactly. If you hold your hand up in front of your face, there is literally nothing to see. Not a single photon of visible light is bouncing off of it. Wow. There's no concept of up, you know, a no concept of down. You have zero sense of movement because there's just nothing to move in relation to.

3:04And no reference points at all. The silence is absolute. Yeah. It is this this ocean of pure nothingness and it stretches out in every conceivable direction for hundreds of millions of light years. You are completely utterly alone in a bubble of eternal night. It's basically the ultimate sensory deprivation chamber. Yes. I mean, if you were floating in that space, the only physical interaction you would have with the broader universe would be this faint microscopic bombardment of the cosmic microwave background, you know, the afterglow of the Big Bang itself. Just that tiny hiss of radiation. Right. Beyond that whispering static, there are no galaxies, no stars, no dust clouds. It's just an unfathomable expanse of emptiness. That completely defies human comprehension. It really challenges everything we think we know about cosmic architecture. Well, welcome to Thrilling Threads. I am so glad you're joining us today because our mission for this deep dive into this source material is, it's pretty simple but incredibly ambitious. We are going to completely shatter your perception of the universe.

4:06I love it. Because, you know, when you were I look up at the night sky, we think of spaces this bustling crowded campus. We picture billions of stars whirling galaxies nebulous bursting with radiation and color, which is a very localized bias really. Exactly. But today, we are exploring an overwhelming, terrifying and frankly fascinating truth. The vast majority of our cosmos is actually made up of gigantic, unfathomably empty spaces known as cosmic voids. The nothingness is the rule. It really is. Stuff like the stars, the planets, the literal atoms that make up your body, that is the very rare exception. And what's fascinating here is that the scientific consensus has fundamentally shifted on this. These empty spaces aren't just passive, you know, inert rooms. They're not just empty boxes. Right. They aren't just missing puzzle pieces or blank spots on a map where we just haven't found the galaxies yet. These voids are highly dynamic engines of cosmic evolution. Weight engines? Yeah, they are growing, drifting,

5:06and pressing against one another. Inside them, the very fabric of space is being stretched. And ultimately, these bubbles of nothingness contain the physical mechanisms that will decide the fate of the entire observable universe. Okay, let's unpack this, because before we can truly appreciate the mechanics of that emptiness, we kind of have to establish a baseline, right? We need a sense of scale. We do. We need to look at our own neighborhood first. Right. Let's look at the something before we stare into the abyss of the nothing. So, to comprehend the void, you first have to understand the physical scaffolding that borders it. Imagine zooming away from Earth, not just in a rocket, but traveling at millions of times the speed of light. Just ripping through the solar system. Exactly. You pull back, pass the solar system, pass the Orion arm, until you can see our entire home galaxy, the Milky Way, just glowing in its entirety. Which is staggering all on its own. I mean, we are looking at a barred spiral galaxy containing roughly 200 billion stars. It's massive. And it's not even isolated.

6:07We have dozens of dwarf galaxies, like the large and small Magellanic clouds, and they're caught in our gravitational pull, basically orbiting us like tiny moons. Like a swarm of bees. Yeah, it feels incredibly crowded, like a massive metropolitan center. And then you look a little further out, about 2.5 million light years away, and there is the Andromeda galaxy. And Andromeda is even more massive than the Milky Way. It has its own swarm of satellite galaxies, and it is crucial to understand the kinematics here. Right, the movement. Yes. Despite the fact that the universe overall is expanding, the Milky Way and Andromeda are gravitationally bound to each other. Really, the expansion isn't pushing us apart. No, because our mutual gravitational pull is strong enough to completely overpower the underlying expansion of space in our local region. We are actually hurtling toward each other at roughly 110 kilometers per second. Oh, wow. So we're going to hit it. Oh, absolutely. We're locked on a direct collision course that will culminate in a massive galactic merger,

7:08billions of years from now. That's insane. So, okay, we keep zooming out to get the broader context. We pull back further and see what astronomers call the local group. Right. This is our specific, gravitationally bound pocket of the universe. It's roughly 10 million light years across, containing over 50 galaxies. And they aren't just floating independently, either. No, they're embedded within this massive, invisible halo of dark matter, right? Exactly. This dark matter acts as the structural foundation. It exerts the gravitational force necessary to keep this entire group tethered together. It's a hyper-connected neighborhood. And because of that gravitational binding, the reality is that no human being, and like no probe we ever build, will naturally leave this 10 million light-year pocket. The escape velocity required to break free of the local group's collective gravitational well is just immense. It is, for all intents and purposes, a sealed perimeter. We are locked in. It is an isolated island

8:08in a much larger, highly structured archipelago. Because if you continue zooming out past our local group, you encounter the Virgo Supercluster. Okay, now we're talking about the big stuff. Massive stuff. This is a colossal structure containing thousands of galaxies spread over roughly 100 million light years. The sheer density of barionic matter, that's the normal matter that makes up stars and gas along with the staggering concentrations of dark matter. It creates a gravitational environment of intense violence and activity. Just constant churning. Galaxies are continuously stripped of their gas, merging and, you know, triggering these massive bursts of star formation. And see, this is exactly where I get stuck. This is where I have to push back a little on the source text narrative about emptiness. Oh, how so? Think about the analogy of moving from a bustling city to an absolute wilderness. We live in the cosmic equivalent of time square on New Year's Eve. That's a great way to put it. Right. Our immediate neighborhood is so violently busy

9:10that our entire galaxy is literally crashing into Andromeda. We have dwarf galaxies swarming us. We belong to this tight cluster of 50 galaxies, which is part of a massive thousand strong supercluster. It's very chaotic locally. Exactly. So if our universe is defined by all these massive superstructures, heavy gravitational binding, and just constant collisions, how could the universe possibly be mostly empty? It seems like a contradiction. It totally does. Yeah. The observational data we have from our own backyard seems completely opposed to the idea of a void-dominated universe. Well, what's fascinating here is that your intuition perfectly mirrors the assumptions of early 20th century cosmologists. Really? They thought the same thing. Oh, absolutely. Before the advent of deep space red shift surveys, astronomers operated under a strict interpretation of the cosmological principle. Which is what exactly? It's the idea that on a large enough scale, the universe is homogenous and isotropic. They assumed that if you zoomed out far enough, the universe would look like a smooth,

10:12uniform soup of galaxies spread relatively evenly in all directions. Right. It made intuitive sense based on the local clustering we could observe. Like, if you take a couple water from the ocean and it's full of salt and plankton, you naturally assume the rest of the ocean is made of the exact same composition. Exactly. If we see galaxies everywhere around us, we naturally assume the universe is just an endless, relatively uniform sea of galaxies. Soon. Access to affordable credit helps me pay my employees that I don't really need it. Infliction is killing me. But who cares? Big retailers and making record profits. That's why we support the German Marshall credit card bill. Banks and credit unions help small businesses make payroll. This bill would cut the vital resources they need. While increasing Megastore profits. They deserve it. Don't they? Tell Congress, stop the German Marshall money grab for corporate megastores, paid for by the Electronic Payments Coalition. Warning, the following Zippercruder radio spot

11:13you are about to hear is going to be filled with F words. When you're hiring, we at Zippercruder know you can feel frustrated for Lauren even. Like your efforts are futile and you can spend a fortune trying to find fabulous people. Only to get flooded with candidates who are just fine. Fortunately, Zippercruder figured out how to fix all that. And right now, you can try Zippercruder for free at zippercruder.com slash zip. With Zippercruder, you can forget your frustrations because we find the right people for your roles fast, which is our absolute favorite F word. In fact, four out of five employers who post on Zippercruder get a quality candidate within the first day. Fantastic. So whether you need to hire four, 40 or 400 people, get ready to meet first rate talent. Just go to zippercruder.com slash zip to try Zippercruder for free. Don't forget that zippercruder.com slash zip. Finally, that zippercruder.com slash zip. Warning, the following Zippercruder radio spot

12:13you are about to hear is going to be filled with F words. When you're hiring, we at Zippercruder know you can feel frustrated for Lauren even, like your efforts are futile. And you can spend a fortune trying to find fabulous people only to get flooded with candidates who are just fine. Fortunately, Zippercruder figured out how to fix all that. And right now, you can try Zippercruder for free at zippercruder.com slash zip. With Zippercruder, you can forget your frustrations because we find the right people for your roles fast, which is our absolute favorite F word. In fact, four out of five employers who post on Zippercruder get a quality candidate within the first day. Fantastic. So whether you need to hire four, 40, or 400 people, get ready to meet first rate talent. Just go to zippercruder.com slash zip to try Zippercruder for free. Don't forget that zippercruder.com slash zip. Finally, that zippercruder.com slash zip. What broke that assumption? The paradigm shift really occurred in the late 1970s and 80s.

13:16It was driven by researchers like Margaret Geller and John Hutra at the Harvard Smithsonian Center for Astrophysics. Oh, right. They did the big mapping project. They did. They didn't just look at the 2D positions of galaxies in the sky. They measured their red shift. Okay, explain red shift for us real quick. Sure. As the universe expands, the light from distant galaxies is physically stretched into longer, redder wavelengths. By measuring that red shift, astronomers could calculate exactly how fast a galaxy is moving away from us. And because of Hubble's law, that speed tells us the distance. Precisely. It tells us exactly how far away it is. This allowed them to map the universe in three dimensions for the very first time. And what they found completely broke the smooth soup model. It dismantled it entirely. When you plot the 3D positions of millions of galaxies, you don't see an even distribution, not at all. You see a highly complex interconnected structure that we now call the cosmic wind. The cosmic wave. It sounds like a sci-fi movie. It really does.

14:17But the universe looks remarkably like a three-dimensional spiderweb or like the neural pathways in a human brain. There's these glowing threads everywhere. Right. You have these incredibly long dense filaments. These are massive threads of dark matter and intergalactic gas studied with thousands of galaxies. And where these cosmic filaments intersect, they form massive dense knots. And those knots are the superclusters. Exactly. Like the Virgo supercluster we reside in. Okay, let's just pause and internalize that. Our entire local group. This massive 10 million light-year expanse containing the Milky Way and Dramada 50 other galaxies and literally all of our future human destiny. It's all right there. In the grand scheme of the cosmic web, we are just a microscopic speck clinging to one single thread. We are locked inside this pocket, woven into a dark matter scaffold, and it's the absolute limit of our physical reality. It provides a deeply humbling perspective, but to truly grasp the architecture of the universe,

15:18you have to look at what isn't there. Okay, you've got my attention. Think about a spider web again. While the structural integrity comes from the silk threads, the actual volume of the web is almost entirely composed of the empty air between those threads. Oh, wow. Yeah. Without the empty gaps, it isn't a web. It's just a solid block of silk. Right. The negative space defines the structure. Exactly. The cosmic web operates on the same geometric principle. The glowing filaments and dense superclusters are just the incredibly thin borders. The vast, overwhelming majority of the physical volume of the universe, roughly 80% of it, is found in the enormous dark gaps between the threads. So that takes us right back to our journey. We've zoomed out past the Milky Way, past the local group, and we are standing on the very edge of the Virgo supercluster. We are basically standing on the edge of the thread. Yes. And right over the edge of this incredibly dense, violent filament is the gap. You have reached the cosmic cliff, right at the boundary of the Virgo supercluster.

16:19The density of matter just drops off a precipice. You are staring into a region known as the local void. The local void? Yeah. Just the name alone gives me chills. It's quite literal. We're looking at an empty bubble of space that spans roughly 200 million light years across. Let me try to conceptualize that physical distance. It's almost impossible for the human brain to picture. Right. Light, the fastest thing in the universe. Traveling at 300,000 kilometers per second takes 200 million years, just across from one side of this empty room to the other. That's a long time to travel through nothing. If this void were a bright glowing object instead of absolute darkness, it would take up a massive portion of our night sky on Earth. But instead, it's just nothing. And, you know, mapping the local void has been notoriously difficult for astrophysicists. A large portion of it lies behind the Milky Way's Galactic Center. Oh, so our own galaxies blocking the view? Exactly. It's a region heavily obscured by dust and gas known as the zone of avoidance.

17:20We can't easily see through our own galaxy using visible light. So how do we know it's there? Well, by utilizing radio and infrared astronomy and by carefully measuring the peculiar velocities of galaxies that is, how they are moving independent of the universe's baseline expansion, we can infer the void's immense size and influence. Wait, explain that peculiar velocity measurement. How does tracking the movement of a galaxy tell us there's an invisible empty space behind our own galaxy? It comes down to gravitational vectors. When astronomers map the motion of galaxies in our local universe, they notice that we, along with our neighboring galaxies, aren't just drifting randomly. Okay. We are actively streaming in a specific direction. We are being pulled toward a massive concentration of mass known as the great attractor. All right, the great attractor. I've heard of that. But that pull only accounts for about half of our velocity. The other half of our speed comes from the fact that we are being powerfully repelled away from the local void. Hold on, I need to push back on the word repell.

18:21Okay, fair enough. Because we just established that voids are incredibly empty. They don't have mass. If gravity is the attraction between masses, how can an empty space repel anything? It doesn't have a force field. That is the crucial mechanical paradox of cosmic voids. You are absolutely correct. Voids do not possess a repulsive force field. Okay, so what's happening? The repulsion is actually a relative effect of uneven gravity. Let me give you an analogy. Imagine you are standing in the exact center of a perfectly spherical room and all the walls have the exact same mass. All right, I'm in the room. The gravitational pull on you from all directions is equal. So you stay perfectly still in the center. But what happens if someone removes the entire left wall? Well, suddenly there's no mass pulling me to the left. But the right wall is still there, so its gravity takes over and I get dragged to the right. Precisely. The empty space where the left wall used to be didn't push you. It simply stopped pulling. Oh wow. Because a void lacks mass,

19:22it exerts almost zero gravitational pull. Meanwhile, the incredibly dense filaments and superclusters surrounding the void have immense gravitational power. So matter drains out of the voids? Exactly. It gets pulled toward the dense walls. The local void isn't actively pushing the Milky Way, rather, the lack of mass behind us means there is nothing balancing the massive gravitational pull of the structures ahead of us. We are falling away from the emptiness. That is a brilliant way to conceptualize it. It's like a reverse black hole. That's a very apt comparison. With a black hole, you have a singularity in the center with so much mass that its gravity pulls everything inside and nothing can escape. But a void is the exact opposite. It's an area with absolutely zero mass in the center, surrounded by an edge with unimaginable mass. So instead of everything falling in, everything falls out. And this drainage system is a compounding, accelerating process. It is a fundamental feature of cosmic evolution driven by gravitational instability.

20:22How so? Like it feeds itself. Yes. The emptier a void gets, the less mass it has. The less mass it has, the weaker its gravitational pull becomes. Meanwhile, the matter that was drained to the edges makes the superclusters even denser, increasing their gravitational dominance. Like a tug of war where one side isn't even trying. Exactly. Over billions of years, it is a system where the dense regions get denser and the empty regions get emptier. The rich get richer, and the poor get poorer. Okay, if the local void is just the appetizer, let's jump to the main course. We've talked about our neighboring emptiness. But let's travel towards the greatest, most profound expanse of nothing we have ever documented. Let's dive right into the Booth Supervoid. Oh, the Booth Supervoid. It is a true anomaly of scale. It was discovered in 1981 by Robert Kirschner and his colleagues during a redshift survey of the Booth's constellation. Just looking at a patch of sky and finding absolutely nothing. Quite literally, it is a nearly spherical region of space,

21:24spanning and astonishing 330 million light years in diameter. 330 million. Yes. And to put the statistical improbability of this structure into perspective, based on the average density of the universe, a volume of space that large should theoretically contain over 2,000 massive galaxies. But it doesn't. At last count, astronomers have found roughly 60 galaxies scattered throughout that massive 330 million light-year expanse. It is a total cosmic desert. It is functionally empty. And this brings me back to the thought experiment we started with. Put yourself in the dead center of the Booth Supervoid. Imagine teleporting a human being in a space suit right into the middle of that desert. It would be profoundly disturbing. You are surrounded by a darkness so perfect, so absolute, that the human mind can barely process the sensory deprivation. You look up, down, left, right. There is not a single photon of light reaching your eyes from any distant star. Because the nearest star is over 150 million light-years away.

22:26From a purely observational standpoint, without highly specialized equipment designed to detect deep infrared or radio waves, the universe would appear to consist solely of yourself. It would be terrifying. You wouldn't just feel alone. You would feel like reality itself had ceased to exist. There is not a single visual indicator that an outside universe is out there. It honestly brings up this intense feeling of existential dread. I can see why. Think about the trajectory of human history. If Earth had somehow formed in the center of the Booth Supervoid, instead of in the Milky Way's bustling neighborhood, our entire understanding of reality would be fundamentally different. How do you mean? Well, if you looked up into the sky from a planet in the middle of Boots, you would see the stars of your own isolated galaxy. And beyond that, just an endless black wall, we would have naturally assumed that our single galaxy was the entire universe. Yes, because there would mean no visible evidence to the contrary. Right. We wouldn't have even conceptualized that other galaxies existed until the late 20th century

23:28when we invented highly advanced orbital telescopes. For thousands of years of human philosophy and science, we would have been convinced we were entirely alone in an endless dark room. While that thought experiment feels isolating to us, you know, the mathematics of the cosmos suggests a different perspective. Really? How so? We view the densely packed, highly interactive environment of the Milky Way as normal, because it produced us. But volumetrically speaking, our crowded neighborhood is the freak occurrence. We are the weird ones. Exactly. To an objective observer looking at the universe as a whole, that silent, perfectly black, motionless environment of the Butte Supervoid is the standard state of the universe. Okay, so the mechanics of voids dictate that matter drains outward toward the dense filaments. It's an incredibly efficient sorting mechanism. But as we look at the dynamic nature of the cosmic web, where galaxies are constantly in motion, moving at millions of kilometers an hour, orbiting and crashing into each other,

24:29why don't galaxies accidentally fly into the voids? That's a very logical question. Like, if you have a crowded room of people running around randomly, eventually people are going to spill out into the empty hallway. Why don't rogue galaxies just shoot off the filaments and gradually fill up these voids over the course of billions of years? Because the fluid dynamics of the universe prevent that from happening. You have to look at the mathematical models of how voids expand, like the Zelda Vitch approximation. Okay, tell me about that. The cosmic web isn't static. The voids themselves are expanding, pushing outward. The visual analogy often cited in hydrodynamical simulations is that galaxies cling to the edges of voids like reflections of light on soap bubbles. I love the soap bubble analogy. Let's expand on that, because it's a great functional way to picture this. When you blow a bubble, all the soapy water is trapped in that incredibly thin, high surface tension film on the outside, while the inside is just empty air. Exactly. The water doesn't drift into the center of the bubble. It is locked to the edge. And as the bubble expands,

25:30the film gets thinner and thinner, but the water stays on the surface. The physics underlying the cosmic version of that bubble involves the interplay between the expansion of space and local gravitational collapse. As a void expands, it essentially acts as a massive spherical under-density. It presses outward against the surrounding matter. So the bubbles are pushing against each other? Yes. When two expanding voids press against each other, the matter caught between them is squeezed into a flat sheet or a pancake of dark matter and gas. As multiple voids expand and press together from different angles, these sheets intersect to form filaments and the filaments intersect to form dense nodes. So the whole web is just the boundaries of expanding bubbles. Exactly. A galaxy wandering into a void is physically opposed by the outward flow of the voids expansion and the intense gravitational pull of the wall it just left. To enter a void, a galaxy would have to fight against the primary structural currents of the universe.

26:30It's like trying to paddle a canoe up a violently flowing waterfall. The physics of the environment just drag you back down to the dense basin. But wait, what if we didn't wait for nature to do it? What do you mean? What if we bypass the natural gravitational currents? Let's say a highly advanced type 3 civilization built an incredible propulsion system and intentionally forced its way off the cosmic web aiming straight for the darkest place in the universe? Could we physically enter a void? Is there a literal barrier? No, there is no physical barrier. The space inside a void is structurally the exact same space-time continuum as the space here. So we could just fly in. Technically, yes. The primary engineering challenge wouldn't be surviving the void itself. The challenge is achieving the massive estate velocity required to break free from the deep gravitational well of your home supercluster. Which would take an unimaginable amount of energy. Precisely. Once you overcome that intense initial drag, you could theoretically coast into the emptiness.

27:30But from an astrophysical perspective, the question isn't whether you could do it but why you would expend the energy to do so. You are traversing hundreds of millions of light years to visit a region defined by its lack of material resources. Because there's nothing there. But honestly, when I dug into the research on this, my mind instantly went to an incredibly cool science fiction premise. Oh, let's hear it. Why would a civilization need to travel into a cosmic void? To hide. Oh, a cosmic refuge. Exactly. Think about life on the cosmic web. The environment inside a massive cluster like Virgo is incredibly violent. Galaxies are constantly colliding. Supermassive black holes are actively feeding firing off jets of relativistic particles. It is a high radiation environment, yes. The immense gravity of neighboring galaxies is constantly warping solar systems, triggering massive bursts of star formation that inevitably lead to localized ways of deadly supernovas. That floods whole regions with lethal gamma radiation.

28:31Living on the cosmic web is like trying to build a house in an active war zone. That is a very apt description of cluster kinematics. So if you were a highly advanced civilization and you saw the... Finding great candidates to hire can be like, well, trying to find a needle in a haystack. Sure, you can post your job to some job board, but then all you can do is hope the right person comes along. Which is why you should try Zippercrooter for free. Add zippercrooter.com slash zip. Zippercrooter doesn't depend on candidates finding you. It finds them for you. It's powerful technology identifies people with the right experience and actively invites them to apply to your job. You get qualified candidates fast. So while other companies might deliver a lot of, hey, Zippercrooter finds you what you're looking for. The needle in the haystack. See why four out of five employers who post a job on Zippercrooter get a quality candidate within the first day? Zippercrooter, the smartest way to hire. And right now, you can try Zippercrooter for free. That's right.

29:32Free at zippercrooter.com slash zip. That zippercrooter.com slash zip zippercrooter.com slash zip. Warning, the following Zippercrooter radio spot you are about to hear is going to be filled with F words. When you're hiring, we at Zippercrooter know you can feel frustrated. For Lauren, even, like your efforts are futile. And you can spend a fortune trying to find fabulous people only to get flooded with candidates who are just fine. F**k. Fortunately, Zippercrooter figured out how to fix all that. And right now, you can try Zippercrooter for free at zippercrooter.com slash zip. With Zippercrooter, you can forget your frustrations because we find the right people for your roles fast, which is our absolute favorite F word. In fact, four out of five employers who post on Zippercrooter get a quality candidate within the first day. Fantastic. So, whether you need to hire four, 40, or 400 people, get ready to meet first-rate talent. Just go to zippercrooter.com slash zip to try zippercrooter for free.

30:35Don't forget that zippercrooter.com slash zip. Finally, that zippercrooter.com slash zip. Warning, the following Zippercrooter radio spot you are about to hear is going to be filled with F words. When you're hiring, we at Zippercrooter know you can feel frustrated. For Lauren, even, like your efforts are futile. And you can spend a fortune trying to find fabulous people, only to get flooded with candidates who are just fine. Fortunately, Zippercrooter figured out how to fix all that. And right now, you can try Zippercrooter for free at zippercrooter.com slash zip. With Zippercrooter, you can forget your frustrations because we find the right people for your roles fast, which is our absolute favorite F word. In fact, four out of five employers who post on Zippercrooter get a quality candidate within the first day. Fantastic. So whether you need to hire four, 40, or 400 people, get ready to meet first rate talent. Just go to zippercrooter.com slash zip to try Zippercrooter for free.

31:36Don't forget that zippercrooter.com slash zip. Finally, that zippercrooter.com slash zip. Universe slowly grinding itself down in these violent, high energy collisions. You might look at that perfectly empty, perfectly silent void and think that is the ultimate cosmic panic room. The concept of a void as a refuge is fascinating when you consider the long-term habitability of the universe. And if a civilization did manage to penetrate the deep void, they would find that it isn't completely devoid of resources. It is a desert, but even deserts have micro ecosystems. Wait, I thought the whole point was that all the matter drained out to the edges. What's left inside? Well, high-resolution n-body simulations, like the Millennium Run, which modeled the distribution of dark matter across cosmic history, reveal that voids are not perfectly clean. So there is some stuff floating around? Yes. While the vast majority of matter is swept to the walls, extremely faint, delicate tendrils of dark matter remain inside the voids. Like little cobwebs? Exactly. They criss-cross the darkness, like microscopic threads of mycelium growing in a dark cave.

32:39They are a much thinner, more diffuse echo of the massive dark matter filaments that make up the primary cosmic web. And if you follow these faint tendrils deep into the void where the dark matter density is just barely high enough to attract a halo of hydrogen gas, you find something truly remarkable. The void galaxy. Yes, suspended in this massive ocean of darkness are incredibly faint isolated galaxies. They are the absolute rarest classification of galaxies we have identified. They are completely cut off from the rest of the universe, existing in a state of profound astronomical isolation. So mechanically, how does a void galaxy differ from a galaxy like our Milky Way? Because they don't have neighbors constantly talking at them, they are engaged in that constant cosmic warfare we just talked about. How does that isolation change their physical evolution? It alters their evolutionary timeline entirely. In a crowded cluster environment, the gravitational interference from neighboring galaxies, what we call tidal forces, constantly churns up the intergalactic gas.

33:42Right, the war is on effect. Exactly. This triggers explosive, rapid periods of star formation called starbursts. But these interactions also violently strip galaxies of their remaining gas, a process known as rampressure stripping. So they just lose all their shule? They do. It's a live fast, die young life cycle. The galaxy burns through its star forming material incredibly quickly and eventually transitions into a red and dead elliptical galaxy. Full of aging stars with no new ones being born. But a void galaxy doesn't experience any of that tidal trauma. No, they don't. They exist in a state of undisturbed equilibrium. Because they have no neighbors to violently strip their gas or disturb their rotational structure, they accrete pristine, unpolluted hydrogen gas from the surrounding intergalactic medium at an incredibly slow, steady rate. They just sip their fuel instead of checking it. Exactly. As a result, void galaxies are typically smaller, retain a distinct blueish hue, and are absolutely saturated with raw star forming fuel.

34:43Let's break down the color difference. Why does slow star formation make them look blue while the older cluster galaxies look red? The color of a galaxy is a direct indicator of its stellar demographics. Hot, massive, young stars, specifically ONV type stars, burning incredibly bright and emit primarily in the blue and ultraviolet spectrum. Because of void galaxies continuously gently forming new stars, it is always populated by these bright blue giants. And a crowded cluster galaxy that has had its gas stripped away star formation ceases. And the blue stars burn out. Right. The massive blue stars burn out and die quickly, leaving only the smaller, cooler, longer-lived red dwarf stars. Furthermore, void galaxies lack the heavy concentrations of cosmic dust that accumulate in highly active galaxies, so the blue light from their young stars isn't obscured. They're pristine, glowing, blue beacons in the dark. So going back to my alien panochrome theory, a void galaxy is essentially preserving its fuel while the rest of the universe violently burns through its supply.

35:46If you're a civilization trying to outlive the natural life span of the cosmos, a void galaxy is precisely where you want to be. It is the most strategic location for long-term survival. Right. As the trillions of years tick by, the crowded galaxies on the cosmic web are going to exhaust their resources. They will use up all their hydrogen, their stars will die off, and those massive glowing superclusters will go completely dark. That is the inevitable thermodynamic fate. But these isolated little blue fireflies, these void galaxies will still be slowly, calmly turning out new stars. They're hoarding the life-giving resources of the universe. The astrophysics of their isolation leads to a deeply profound projection regarding the distant future. Because void galaxies are hoarding their primordial gas and aging in slow motion, it is highly probable that as the universe enters the degenerate era, the phase when star formation across the cosmos largely ceases, these isolated islands will be the very last bastions of stellar ignition. Billions upon billions of years after the Milky Way has gone dark,

36:48a void galaxy will still be glowing. It is statistically likely that the very last start to ever shine in our universe will be born, and will eventually die deep inside a cosmic void. The last light in the universe will be surrounded by the greatest darkness, as incredibly poetic. It frames these terrifying empty spaces not as dead zones, but as the ultimate safe havens, the final sanctuaries for light and potentially for life. They certainly act as time capsules, but before we get too comfortable characterizing voids as peaceful sanctuaries, we have to look at the underlying cosmology that governs their future. Oh, there's a catch. There's always a catch. Because while the voids themselves are practically empty of matter, they are completely saturated with a force that makes them the most dangerous regions in the universe on a cosmological timeline. Okay, I'm listening. A force that guarantees that the peace of the void galaxy is ultimately temporary. We are talking about dark energy. We are. Dark energy is arguably the most profound, unresolved mystery in modern theoretical physics.

37:50It is an unseen, poorly understood phenomenon, often modeled mathematically as a cosmological constant, or lambda that is actively driving the accelerated expansion of the universe. Right. It is the mechanism that will ultimately dismantle the cosmos. Dark energy is one of those concepts that sounds like absolute magic until you dig into the physics. If this energy is a property of space itself, and it is everywhere actively pushing the universe apart, why don't I feel it right now? That's a common point of confusion. Well, why isn't dark energy pushing the Earth away from the Sun? If the universe is expanding, why aren't the atoms in my body flying apart? That touches on the critical concept of scale dependence in cosmology. Dark energy is everywhere, permeating every cubic centimeter of space. However, its energy density is incredibly low. Oh, it's very weak locally. Exactly. On a localized scale like inside a solar system, or even within a massive galaxy cluster, the fundamental forces of nature completely overpower it.

38:53The electromagnetic force holds your atoms together. The gravitational force holds the Earth to the Sun, and gravity binds the Milky Way to Andromeda. So gravity just beats it in an arm-wrestling match? Yes. These local binding forces are orders of magnitude stronger than the repulsive push of dark energy. We cannot observe dark energy doing anything inside our local neighborhood, because gravity is the absolute dominant force in a high density environment. So dark energy is a weak pusher, but a very persistent one. It only wins if there's no gravity fighting back. It brings us right back to the voids. Can you see the connection? If you go into the Benutesupervoid, where there is virtually zero mass, there is virtually zero gravity. Exactly. Inside the voids, gravity is so incredibly weak that it offers no resistance. Here, in the absolute nothingness, dark energy is entirely unopposed. It dominates the physical environment. As a result, the voids are the primary engines of cosmic acceleration. Inside the voids is where space itself is stretching violently.

39:54Okay, but how do we actually know that? Because we can't physically see dark energy and the void is empty, so we can't see the void expanding directly. How do astrophysicists actually measure the effect of dark energy inside a void? We measure it through an incredibly subtle phenomenon known as the late-time integrated saxwolf effect. The saxwolf effect. Okay, break that down for us. It involves tracking photons from the cosmic microwave background as they travel across the universe to reach our telescopes. When a CMB photon enters a massive supercluster, it falls into a gravitational well, gaining energy. Reeling down a hill. Exactly. When it climbs back out of the cluster, it loses that energy. In a static universe, this would be a zero-sum game. The photon leaves with the exact same energy it entered with. But the universe isn't static. Space is expanding while the photon is moving. Precisely. And this is where the voids provide the proof of dark energy. When a photon enters a massive expanding void, it has to climb out of an ever-shallow gravitational environment. Wait, why is it getting shallower?

40:55Because dark energy is actively stretching the void while the photon is inside it. The physical dimensions of the void change before the photon can exit. The photon actually loses energy crossing the void. Oh, wow. So we can read that energy loss. We can. By looking at tiny temperature fluctuations in the CMB and correlating them with the locations of massive voids, we can physically measure the exact rate at which dark energy is stretching the nothingness. So the voids aren't just sitting there. They are actively inflating, like balloons being pump full of air. But the air is the intrinsic energy of the vacuum itself. That's a perfect visualization. And because there is no matter to generate gravity and stop the expansion, they just keep blowing up, getting bigger and bigger at an accelerating rate. Yes. And as we established earlier, the borders of these inflating bubbles are the cosmic web, the dense filaments of dark matter and superclusters where all the galaxies reside. As the voids inflate, they push outward, applying immense relentless pressure to the very architecture of the universe.

41:59Which means the nothing is actively attacking the something. The empty space is physically dismantling the structures of matter. That is the grim mechanical reality of the cosmos. As the voids grow larger and larger, propelled by dark energy, they encroach upon the filaments. The delicate galaxy clusters are slowly being stretched and pulled apart by the expansion of the voids around them. Just ripping the web apart. Exactly. Imagine a massive dense wall of thousands of galaxies. As the void bubble on either side expands against it, the gravitational binding of that wall is overcome. The galaxies are pulled further and further apart, thinning the filament until eventually it snaps. And when the filament's separating two void bubbles finally breaks, what happens? The voids merge. Two massive pockets of nothingness join forces to become an even larger supervoid. It is hydrodynamically similar to watching soap bubbles pop and merge in the sink, but on a scale of hundreds of millions of light years. The voids are systematically consuming the cosmic web

43:00that completely flips the script on how we view astronomy. For centuries, human beings have looked up and studied the light. We have charted the stars, mapped the galaxies, and tracked the clusters. We followed the bright spots. Exactly. We spent all our time analyzing the stuff because we naturally assumed the stuff was the story. But when you look at the cosmological models of the far future, the stars and galaxies are just the leftover debris. They are the crumbling scaffolding of a dying structure. If we truly want to understand the mechanics and the ultimate fate of our universe, we cannot just study the light. The most important physics in the universe are happening in the dark. Because the darkness is the dominant mechanism. The projections based on our current understanding of dark energy and void kinematics are stark. This is the path toward the big freeze or the big rip. The end of everything. Yes. In the far future, these supervoids will continue to expand relentlessly. They will crush and isolate the remaining galaxy clusters, pushing them so far apart that their light will never reach one another.

44:03The acceleration will continue until the voids consume everything. Just one big empty room. Eventually, the entire observable universe will be nothing more than a single, infinitely expanding void. The loneliest place in existence won't just be a specific region of space you can visit. It will be all of space. The nothingness is going to eat everything until there's only nothing left. That is an incredibly heavy physical realization to carry around. It is profound. It really does bring us back down to earth with a completely altered perspective. We started this discussion by talking about the experience of looking up at a night sky full of stars. The time square analogy. Right. But now, when you go outside tonight and look up at that canjus, the light doesn't seem quite so dominant anymore. Now, you know that just beyond those stars, wrapping around our entire cosmic neighborhood are these invisible, massive, actively inflating voids. They are always there. They are surrounding us. They are stretching the fabric of reality, and they are quietly, methodically dictating the final destiny of everything we know.

45:06The emptiness isn't just the backdrop of the cosmos. The emptiness is the main character. It forces a profound paradigm shift. It is physically humbling. But, you know, it also highlights the incredible statistical privilege of existing in the specific bustling era of the universe's lifespan, the stiliferous era. The era of light? Exactly. We happen to exist on the specific dense thread of the cosmic web at a time when we can still see the stars before the expanding voids isolate them forever. It really makes you appreciate the light while we still have the physics to support it. And before we go, I want to leave you with one final thought. To ponder a thought experiment based on those lonely little void galaxies we talked about earlier. It should be good. Imagine, if you will, that the specific stellar nucleosynthesis and biological evolution that created humanity hadn't happened here in the chaotic, crowded Milky Way. Imagine if Earth had formed around a pristine blue star deep inside one of those rare, isolated void galaxies

46:07in the center of the booth's supervoid. The completely different vantage point. If early humans had looked up at the night sky and seen absolutely nothing, know where their stars, no bright band of the Milky Way galaxy spanning the horizon, just an endless suffocating black void in every single direction. How do you think human history would have changed? That's a fascinating question. How would our philosophy, our early religions, and the foundations of our sciences have developed differently if our immediate environment looked like the ultimate sensory deprivation chamber? Would a civilization surrounded by total darkness ever develop the desire to invent telescopes and explore space? Or would the psychological weight of the dark keep us entirely focused inward? It's hard to even imagine the psychological impact of that. It really is. What do you think? Drop your theories in the comments. We would absolutely love to read your take on this cosmic what if? Thank you so much for joining us on this deep dive into the source material on thrilling threats. Thanks for listening. Keep looking up, but more importantly, stay intensely curious

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