Speaker 1: 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 isn't a nocean of water on Earth. There is
absolutely no light, like zero.
Speaker 2: None, just absolute darkness.
Speaker 1: 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 it. Wow.
There's no concept of up, you know, and no concept
of down. You have zero sense of movement because there's
just nothing to move in relation.
Speaker 2: To I no reference points at all.
Speaker 1: The silence is absolute. Yeah, it is 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.
Speaker 2: 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 after glow of the Big Bang itself, Just.
Speaker 1: That tiny hiss of radiation.
Speaker 2: 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.
Speaker 1: 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.
Speaker 2: I love it.
Speaker 1: Because you know, when you or I look up at
the night sky, we think of space as this bustling,
crowded canvas. We picture billions of stars, swirling galaxies, nebulas,
bursting with radiation and color.
Speaker 2: Which is a very localized bias really exactly.
Speaker 1: But today we are exploring and overwhelming, terrifying and frankly
fascinating truth. The vast majority of our cosmos is actually
made up of gigantic, unfathomably empty space is 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.
Speaker 2: 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.
Speaker 1: They're not just empty boxes, right.
Speaker 2: 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, and 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.
Speaker 1: 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.
Speaker 2: We need to look at our own neighborhood first, Right,
Let's look.
Speaker 1: At the something before we stare into the abyss of
the nothing.
Speaker 2: 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.
Speaker 1: Of light, just ripping through the Solar System exactly.
Speaker 2: You pull back past the Solar System, past the Orion arm,
until you can see our entire home galaxy, the Milky Way,
just glowing in its entirety, which is.
Speaker 1: Staggering all on its own. Yeah. I mean, we are
looking at a barred spiral galaxy containing roughly two hundred
billion stars.
Speaker 2: It's massive, and it's not even isolated.
Speaker 1: We have dozens of dwarf galaxies like the large and
small magelantic clouds, and they're caught in our gravitational poll
basically orbiting us like tiny.
Speaker 2: Moons, like a swarm of bees.
Speaker 1: Yeah, it feels incredibly crowded, like a massive metropolitan center.
And then you look a little further out, about two
point five million light years away, and there is the
Andromeda galaxy.
Speaker 2: And Andromeda is the 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.
Speaker 1: To each other. Really the expansion isn't pushing us apart.
Speaker 2: 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 one
hundred and ten kilometers per second.
Speaker 1: Oh wow, so we're going to hit it.
Speaker 2: Oh? Absolutely, We're locked on a direct collision course that
will culminate in a massive galactic merger billions of years
from now.
Speaker 1: 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 ten million
light years across, containing over fifty galaxies.
Speaker 2: And they aren't just floating independently either.
Speaker 1: No, they're embedded within this massive invisible halo of dark
matter right exactly.
Speaker 2: 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.
Speaker 1: And because of that gravitational binding, the reality is that
no human being, and like no probe we ever build,
will naturally leave this ten million light your pocket.
Speaker 2: The escape velocity required to break free of the local
group's collective gravitational well is just immense.
Speaker 1: It is, for all intents and purposes, a sealed perimeter.
We are locked in.
Speaker 2: It is an isolated island in a much larger, highly
structured archipelago, because if you continue zooming out past our
local group, you encounter the Virgo supercluster.
Speaker 1: Okay, now we're talking about the big stuff.
Speaker 2: Massive stuff. This is a colossal structure containing thousands of
galaxies spread over roughly one hundred million light years. The
sheer density of buryonic 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.
Speaker 1: Just constant churning.
Speaker 2: Galaxies are continuously stripped of their gas, merging and triggering
these massive bursts of star formation.
Speaker 1: 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.
Speaker 2: Oh, how so, think.
Speaker 1: About the analogy of moving from a bustling city to
an absolute wilderness. We live in the cosmic equivalent of
times square on New Year's Eve.
Speaker 2: That's a great way to put it right.
Speaker 1: Our immediate neighborhood is so violently busy that our entire
galaxy is literally crashing into Andromeda. We have dwarf galaxies
swarming us. We belong to this tight cluster of fifty galaxies,
which is part of a massive thousand strong supercluster.
Speaker 2: It's very chaotic locally exactly.
Speaker 1: So, if our universe is defined by all these massive superstructures,
gravitational binding and just constant collisions, how could the universe
possibly be mostly empty?
Speaker 2: It seems like a contradiction.
Speaker 1: It totally does. Yeah, the observational data we have from
our own backyard seems completely opposed to the idea of
avoid dominated universe.
Speaker 2: Well, what's fascinating here is that your intuition perfectly mirrors
the assumptions of early twentieth century cosmologists.
Speaker 1: Really, they thought the same thing.
Speaker 2: Oh absolutely, Before the advent of deep space redshift 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 homogeneous and isotropic. They
assumed that if you zoomed out far enough, the universe
would look like a smooth, uniform soup of galaxies spread
relatively evenly in all directions.
Speaker 1: Right, it made intuitive sense based on the local clustering
we could observe. Like if you take a cup of
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.
Speaker 2: Exactly. If we see galaxies everywhere around us, we naturally
assume the universe is just an endless, relatively uniform sea
of galaxies.
Speaker 1: What broke that assumption?
Speaker 2: The paradigm shift really occurred in the late nineteen seventies
and eighties. It was driven by researchers like Margaret Geller
and John Houtra at the Harvard Smithsonian Center for Astrophysics.
Speaker 1: Oh right, they did the big mapping project.
Speaker 2: They did. They didn't just look at the two D
positions of galaxies in the sky. They measured their red shift.
Speaker 1: Okay, explain redshift for us really quick.
Speaker 2: 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.
Speaker 1: Us, and because of Hubble's law, that speed tells.
Speaker 2: 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.
Speaker 1: They found completely broke the smooth soup model.
Speaker 2: It dismantled it entirely. When you plot the three D
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 web.
Speaker 1: The cosmic web. It sounds like a sci fi movie, it.
Speaker 2: Really does, but the universe looks remarkably like a three
dimensional spider web, or like the neural pathways in a
human brain.
Speaker 1: This is these glowing threads everywhere.
Speaker 2: Right, you have these incredibly long, dense filaments. These are
massive threads of dark matter and intergalactic gas studded with
thousands of galaxies. And where these cosmic filaments intersect, they
form massive dense knots.
Speaker 1: And those knots of the superclusters.
Speaker 2: Exactly like the Virgo supercluster. We reside in.
Speaker 1: Okay, let's just pause and internalize that. Ye, our entire
local group, this massive ten million light year expanse, containing
the Milky Way, Andromeda, fifty other galaxies, and literally all
of our future human destiny, all right there in the
grand scheme of the cosmic web. We are just a
micro scopic 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.
Speaker 2: It provides a deeply humbling perspective. But to truly grasp
the architecture of the universe, you have to look at
what isn't there.
Speaker 1: Okay, you've got my attention.
Speaker 2: 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.
Speaker 1: Right. The negative space defines the structure exactly.
Speaker 2: 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 eighty percent of it is found in
the enormous dark gaps between the threads.
Speaker 1: So that takes us right back to our journey. We've
zoomed out past the Milky Way, 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.
Speaker 2: You have reached, the cosmic cliff. Right at the boundary
of the Virgo supercluster, the density of matter just drops
off a precipice. You were staring into a region known
as the local void.
Speaker 1: The local Void. Yeah, just the name alone gives me chills.
Speaker 2: It's quite literal.
Speaker 1: We're looking at an empty bubble of space that spans
roughly two hundred million light years across. Let me try
to conceptualize that physical distance.
Speaker 2: It's almost impossible for the human brain to picture.
Speaker 1: Right light, the fastest thing in the universe, traveling at
three hundred thousand kilometers per second, takes two hundred million
years just across from one side of this empty room
to the other.
Speaker 2: That's a long time to travel through nothing.
Speaker 1: If this void we're 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.
Speaker 2: 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.
Speaker 1: Oh so our own galaxies blocking the view exactly.
Speaker 2: It's a region heavily obscured by dust and gas, known
as the zone of avoidance. We can't easily see through
our own galaxy using visible.
Speaker 1: Lights, So how do we know it's there?
Speaker 2: 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.
Speaker 1: Wait explain that peculiar velocity measurement. How does treking the
movement of a galaxy tell us there's an invisible empty
space behind our own galaxy.
Speaker 2: 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.
Speaker 1: All right, the great Attractor, I've heard of that.
Speaker 2: 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.
Speaker 1: Hold on, I need to push back on the word repel. Okay,
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.
Speaker 2: That is the crucial mechanical paradox of cosmic voids. You
are absolutely correct. Voids do not possess a repulsive force field.
Speaker 1: Okay, so what's happening.
Speaker 2: 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.
Speaker 1: Right, I'm in the room.
Speaker 2: The gravitational pull on you from all directions is equal
so you stay perfect still in the center. But what
happens if someone removes the entire left wall.
Speaker 1: Well, suddenly there's no mass pulling me to the left,
but the right wall is still there, so it's gravity
takes over and I get dragged to the right.
Speaker 2: Precisely, the empty space where the left wall used to
be didn't push you. It simply stopped pulling.
Speaker 1: Oh wow.
Speaker 2: Because a void lacks mass, it exerts almost zero gravitational pull. Meanwhile,
the incredibly dense filaments and superclusters surrounding the void have
immense gravitational.
Speaker 1: Power, so matter drains out of the.
Speaker 2: 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.
Speaker 1: That is a brilliant way to conceptualize it. It's like
a reverse black hole.
Speaker 2: That's a very apt comparison with.
Speaker 1: A black hole. You have a singularity in the center
with so much mass that its gravity pulls everything inside
and nothing can escape. 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.
Speaker 2: And this drainage system is a compounding, accelerating process. It
is a fundamental feature of cosmic evolution, driven by gravitational instability.
Speaker 1: How So, like it feeds itself.
Speaker 2: Yes, the emptier avoid 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.
Speaker 1: Like a tug of war where one side isn't even.
Speaker 2: 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.
Speaker 1: 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
Booths supervoid.
Speaker 2: Oh, the Booth supervoid. It is a true anomaly of scale.
It was discovered in nineteen eighty one by Robert Kushner
and his colleagues during a red shift survey of the
Boots constellation.
Speaker 1: Just looking at a patch of sky and finding absolutely nothing.
Speaker 2: Quite literally, it is a nearly spherical region of space
spanning an astonishing three hundred and thirty million light years
in diameter.
Speaker 1: Three hundred and thirty million.
Speaker 2: 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
two thousand massive galaxies, but it doesn't.
Speaker 1: At last count, astronomers have found roughly sixty galaxies scattered
throughout that massive three hundred and thirty million light year expanse.
It is a total cosmic desert.
Speaker 2: It is functionally empty.
Speaker 1: And this brings me back to the thought experiment we
started with. Put yourself in the dead center of the
boat supervoid. Imagine teleporting a human being in a spacesuit
right into the middle of that desert.
Speaker 2: It would be profoundly disturbing.
Speaker 1: 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 one hundred and fifty
million light years away.
Speaker 2: From 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.
Speaker 1: 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.
Speaker 2: I can see why.
Speaker 1: Think about the trajectory of human history. If Earth had
somehow formed in the center of the Boots supervoid instead
of in the Milky Way's bustling neighborhood, our entire unders
standing a 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.
Speaker 2: Ah, yes, because there would mean no visible evidence to
the contrary, Right.
Speaker 1: We wouldn't have even conceptualized that other galaxies existed until
the late twentieth century when 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.
Speaker 2: While that thought experiment feels isolating to us, you know,
the mathematics of the cosmos suggest a different perspective. Really,
how so, we viewed 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.
Speaker 1: We are the weird ones.
Speaker 2: Exactly. To an objective observer looking at the universe as
a whole, that silent, perfectly black, motionless environment of the
Boutet supervoid is the standard state of the universe.
Speaker 1: 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.
Why don't galaxies accidentally fly into the voids.
Speaker 2: That's a very logical question.
Speaker 1: 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.
Speaker 2: 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 Zildavich approximation.
Speaker 1: Okay, tell me about that.
Speaker 2: The cosmic web isn't static. The voids themselves are expanding,
pushing outward. The visual announ aloga, often cited in hydrodynamical simulations,
is that galaxies cling to the edges of voids like
reflections of light on soap bubbles.
Speaker 1: 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.
Speaker 2: Exactly.
Speaker 1: The water doesn't drift into the center of the bubble.
It is locked to the edge, and as the bubble expands,
the film gets thinner and thinner, but the water stays
on the surface.
Speaker 2: 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.
Speaker 1: So the bubbles are pushing against each other.
Speaker 2: 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.
Speaker 1: So the whole web is just the boundaries of expanding
bubbles exactly.
Speaker 2: A galaxy wandering into a void is physically opposed by
the outward flow of the void's 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.
Speaker 1: It's like trying to paddle a canoe up of violently
flowing waterfall. The physics of the environment just drag you
back down to the dense space. 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.
It's say a highly advanced Type three 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 avoid Is there a literal barrier?
Speaker 2: No, there is no physical barrier. The space inside a
void is structually the exact same space time continuum as
the space.
Speaker 1: Here, so we could just fly in.
Speaker 2: Technically, yes, The primary engineering challenge wouldn't be surviving the
void itself. The challenge is achieving the massive escape velocity
required to break free from the deep gravitational well of
your home supercluster.
Speaker 1: Which would take an unimaginable amount of energy.
Speaker 2: Precisely, once you overcome that intense initial drag, you could
theoretically coast into the emptiness. But 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.
Speaker 1: 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.
Speaker 2: Oh, let's hear it.
Speaker 1: Why would a civilization need to travel into a cosmic
void to hide?
Speaker 2: Oh, a cosmic refuge exactly.
Speaker 1: 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.
Speaker 2: It is a high radiation environment.
Speaker 1: 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. Living on the cosmic web
is like trying to build a house in an active
war zone.
Speaker 2: That is a very apt description of cluster kinematics.
Speaker 1: So if you were a highly advanced civilization and you
saw the 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.
Speaker 2: The concept of a void as a refuge is fascinating
when you consider the long term habitability of the universe,
and you know, 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.
Speaker 1: Wait, I thought the whole point was that all the
matter drained out to the edges. What's left inside well.
Speaker 2: High resolution and body simulations like the Millennium Run, which
model the distribution of dark matter across cosmic history, reveal
that voids are not perfectly clean.
Speaker 1: So there is some stuff floating around.
Speaker 2: Yes, While the vast majority of matter is swept to
the walls, extremely faint, delicate tendrils of dark matter remain
inside the voids.
Speaker 1: Like little cobwebs.
Speaker 2: Exactly, They crisscross the darkness like microscopic threads of mycelium
growing in a dark cave. They 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.
Speaker 1: The void galaxy.
Speaker 2: Yes, suspended in this massive ocean of darkness are incredible
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.
Speaker 1: So mechanically, how is avoid galaxy different from a galaxy
like our Milky Way? Because they don't have neighbors constantly
tugging at them. They aren't engaged in that constant cosmic
warfare we just talked about. How does that isolation change
their physical evolution?
Speaker 2: 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.
Speaker 1: Gas right the war zone effect exactly.
Speaker 2: 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 ram pressure stripping.
Speaker 1: So they just lose all their shoel they do.
Speaker 2: It's a live, fast, die young life cycle. The galaxy
burns through its star format material incredibly quickly and eventually
transitions into a red and dead elliptical galaxy full of
aging stars with no new ones being born.
Speaker 1: But avoid galaxy doesn't experience any of that tidal trauma.
Speaker 2: 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 innergalactic medium at an incredibly slow,
steady rate.
Speaker 1: Do they just sip their fuel instead of.
Speaker 2: Checking it exactly. As a result, void galaxies are typically smaller,
retain a distinct bluish hue, and are absolutely saturated with
raw star forming fuel.
Speaker 1: Let's break down the color difference. Why does slow star
formation make them look blue while the older cluster galaxies
look red?
Speaker 2: The color of a galaxy is a direct indicator of
its stellar demographics. Hot massive young stars, specifically O n
B type stars burn incredibly bright and emit primarily in
the blue and ultraviolet spec 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.
Speaker 1: And the blue stars burn out right.
Speaker 2: 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 dusts that
accumulate in highly active galaxies, so the blue light from
their young stars isn't obscured their pristine glowing blue beacons
in the dark.
Speaker 1: So, going back to my alien panic room theory, avoid
galaxy is essentially preserving its fuel while the rest of
the universe violently burns through its supply. If you are
a civilization trying to outlive the natural life span of
the cosmos, avoid galaxy is precisely where you want to be.
Speaker 2: It is the most strategic location for long term survival.
Speaker 1: 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.
Speaker 2: That is the inevitable thermodynamic fate.
Speaker 1: But these isolated little blue fireflies, these void galaxies, will
still be slowly, calmly churning out new stars. They are
hoarding the life giving resources of the universe.
Speaker 2: 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, a void galaxy will still be glowing.
It is statistically likely that the very last star to
ever shine in our universe will be born and will
eventually die deep inside a cosmic void.
Speaker 1: 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.
Speaker 2: 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.
Speaker 1: Oh there's a catch.
Speaker 2: There is always a catch, because while the moids 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.
Speaker 1: Okay, I'm listening.
Speaker 2: A force that guarantees that the piece of the void
galaxy is ultimately temporary.
Speaker 1: We are talking about dark energy. We are.
Speaker 2: Dark energy is arguably the most profound, unresolved mystery in
modern theoretical physics. It is an unseen, poorly understood phenomenon
often modeled mathematically as a cosmological consonant or lambda, that
is actively driving the accelerated expansion of the universe. Right,
it is the mechanism that will ultimately dismantle the cosmos.
Speaker 1: 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?
Speaker 2: That's a common point of confusion.
Speaker 1: 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?
Speaker 2: 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. 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. The electromagnetic force holds your
atoms together, the gravitational force holds the Earth to the Sun,
and gravity binds them Milky Way to Andromeda.
Speaker 1: So gravity just beats it in an arm wrestling match.
Speaker 2: 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.
Speaker 1: So dark energy is a weak pusher, but a very
persistent one. It only wins if there's no gravity fighting back,
which brings us right back to the voids.
Speaker 2: You see the connection.
Speaker 1: If you go into the Benuth supervoid, where there is
virtually zero mass, there is virtually zero.
Speaker 2: 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.
Speaker 1: Okay, 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 directly, how do astrophysicists
actually measure the effect of dark energy inside a void.
Speaker 2: We measure it through an incredibly subtle phenomenon known as
the late time integrated sax Wolf.
Speaker 1: Effect the sax Wolf effect. Okay, break that down for us.
Speaker 2: 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.
Speaker 1: Rolling down a hill.
Speaker 2: 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.
Speaker 1: But the universe isn't static. Space is expanding while the
photon is.
Speaker 2: 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.
Speaker 1: Wait, why is it getting shallower?
Speaker 2: Because 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.
Speaker 1: Oh wow, so we can read that energy loss.
Speaker 2: 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.
Speaker 1: So the voids aren't just sitting there, they are actively
inflating like balloons being pumped full of air, but the
air is the intrinsic energy of the vacuum itself.
Speaker 2: That's a perfect visualization.
Speaker 1: And because there is no matter to generate gravity and
stop the expansion, they just keep blowing up, getting bigger
and bigger and accelerating rate.
Speaker 2: 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.
Speaker 1: Universe, which means that nothing is actively attacking the something.
The empty space is physically dismantling the structures of matter.
Speaker 2: 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.
Speaker 1: Them, just ripping the web apart exactly.
Speaker 2: 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 than ing the filament, until
eventually it snaps.
Speaker 1: And when the filament separating two void bubbles finally breaks,
what happens.
Speaker 2: 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 a sink,
but on a scale of hundreds of millions of light years.
The voids are systematically consuming the cosmic web.
Speaker 1: That completely lips 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 track
the clusters.
Speaker 2: We followed the bright spots exactly.
Speaker 1: We spend all our time analyzing the stuff because we
naturally assume 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.
Speaker 2: They are the crumbling scaffolding of a dying structure.
Speaker 1: 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.
Speaker 2: 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.
Speaker 1: Freeze or the Big rip, the end of everything.
Speaker 2: 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 light will never reach
one another. The acceleration will continue until the voids consume.
Speaker 1: Everything, just one big empty room.
Speaker 2: 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.
Speaker 1: The nothingness is going to eat everything until there's only
nothing left. That is an incredibly heavy physical realization to
carry around.
Speaker 2: It is profound.
Speaker 1: 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.
Speaker 2: The times square analogy.
Speaker 1: Right. But now when you go outside tonight and look
up at that Kansas, 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.
Speaker 2: They are always there.
Speaker 1: They are surrounding us. They are stretching the fabric of reality,
and they are quietly, methodically dictating the final destiny of
everything we know. The emptiness isn't just the backdrop of
the cosmos. The emptiness is the main character.
Speaker 2: It forces a profound paradigm shift. It is physically humbling,
but you know, it also highlights the incredible statistical privilege
of existing in this specific bustling era of the universe's
life span, the stiliferous era, the.
Speaker 1: Era of lights.
Speaker 2: 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.
Speaker 1: 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 cut. Imagine if
you will, that the specific stellar nucleosynthesis in biological evolution
that created humanity hadn't happened here in the chaotic, crowded
Milky Way. Imagine if Earth had formed around a risteam
blue star deep inside one of those rare isolated void
galaxies in the center of the Bood's supervoid, the.
Speaker 2: Completely different vantage point.
Speaker 1: If early humans had looked up at the night sky
and seen absolutely nothing, no weather star, is, 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?
Speaker 2: That's a fascinating question.
Speaker 1: 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 in explore space, or would the psychological weight of
the dark keep us entirely focused inward?
Speaker 2: It's hard to even imagine the psychological impact.
Speaker 1: 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 Threads. Thanks for listening, Keep
looking up, but more importantly, stay intensely curious about the
massive dark spaces between those stars. Until next time,