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The Darkest Place in the Universe Isn_t a Black Hole · Boring Science

• 0:00
  Speaker 1: Hello, and welcome to Boring Science to Sleep, a quiet
• 0:04
  Speaker 1: place where science becomes slow, soft, and easy to drift through. Tonight,
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  Speaker 1: you're going to gently explore one of the strangest places
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  Speaker 1: in the universe, a place where galaxies become rare, light
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  Speaker 1: grows faint, and enormous stretches of space seem to contain
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  Speaker 1: almost nothing at all. Before you settle in, if you
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  Speaker 1: enjoy these quiet journeys through science … you're welcome to
• 0:29
  Speaker 1: like this video and subscribe, only if it feels right
• 0:33
  Speaker 1: for you. And if you'd like, let me know in
• 0:36
  Speaker 1: the comments where you're listening from, and what time it
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  Speaker 1: is there. Now, dim the lights, get comfortable, and let
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  Speaker 1: your breathing slow naturally. You are safe. There's nothing to do,
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  Speaker 1: just listen and drift. And somewhere beyond the quiet night
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  Speaker 1: sky above you, an immense darkness is already waiting. So,
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  Speaker 1: Very gently, let's begin. You can begin exactly where you are.
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  Speaker 1: There is no need to imagine yourself somewhere uncomfortable, and
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  Speaker 1: there is no need to travel anywhere quickly. You are
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  Speaker 1: simply lying still, perhaps beneath a blanket, perhaps with the
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  Speaker 1: room around you becoming quieter as the evening continues, while
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  Speaker 1: somewhere far above the roof, beyond the clouds and beyond
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  Speaker 1: the familiar blue of the daytime sky, the universe is
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  Speaker 1: already stretching away in every direction. If you could see
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  Speaker 1: through the ceiling now, you might notice the night sky.
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  Speaker 1: Perhaps there would be only a few stars visible from
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  Speaker 1: where you are. Perhaps there would be many. But even
• 1:40
  Speaker 1: when the sky looks crowded, it is giving you only
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  Speaker 1: a tiny glimpse of what is really there. Because when
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  Speaker 1: you look upward from Earth, you are mostly looking at
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  Speaker 1: points of light. And between those points of light there
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  Speaker 1: is space. A great deal of space. more space than
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  Speaker 1: the human mind was ever designed to picture comfortably. You
• 2:01
  Speaker 1: might think of the night sky as being filled with stars,
• 2:05
  Speaker 1: because stars are what your eyes notice first, little points
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  Speaker 1: of brightness scattered across the darkness. But the stars are
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  Speaker 1: not the main thing. The darkness is. The spaces between
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  Speaker 1: them are. And as you slowly change your perspective, allowing
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  Speaker 1: yourself to drift farther and farther away from Earth, The
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  Speaker 1: importance of that darkness becomes easier to feel. You rise
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  Speaker 1: gently above your home. The lights of the city, if
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  Speaker 1: there are any below you, become smaller. The roads become
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  Speaker 1: thin lines. Buildings become tiny shapes. And then earth itself
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  Speaker 1: begins to appear as something very small, floating quietly in space.
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  Speaker 1: You continue outward. There is no sound here. No wind.
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  Speaker 1: No traffic. No footsteps. only the quiet image of a
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  Speaker 1: small world surrounded by an enormous amount of darkness. You
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  Speaker 1: pass beyond the familiar neighbourhood of the solar system, and
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  Speaker 1: the planets become distant companions scattered around the sun. Then
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  Speaker 1: you continue farther still, until the solar system itself becomes
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  Speaker 1: only a tiny part of something much larger. The Milky
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  Speaker 1: Way begins to unfold around you. From far away, It
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  Speaker 1: is a great galaxy filled with stars, gas, dust and
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  Speaker 1: unseen matter arranged in a broad spiral structure. It looks enormous.
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  Speaker 1: And it is enormous. But even this great galaxy is
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  Speaker 1: only one small structure inside a much larger cosmic landscape.
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  Speaker 1: You continue drifting. Other galaxies begin to appear. Some are bright,
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  Speaker 1: some are faint, some are large, some are small. and
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  Speaker 1: slowly something strange begins to happen. You notice that the
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  Speaker 1: galaxies are not spread evenly through space. They do not
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  Speaker 1: form a perfectly smooth mist. Instead, they gather into long,
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  Speaker 1: delicate structures. There are regions where galaxies become more numerous,
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  Speaker 1: places where groups and clusters gather together, and enormous strands
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  Speaker 1: that stretch across unimaginable distances. Between these structures are vast
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  Speaker 1: regions where galaxies become much less common. These are called
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  Speaker 1: cosmic voids. The word void might sound as though it
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  Speaker 1: means absolutely nothing, but that is not quite what a
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  Speaker 1: cosmic void is. A cosmic void is better imagined as
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  Speaker 1: a region where matter is extraordinarily thin compared with the
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  Speaker 1: denser structures around it. There can still be faint gas.
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  Speaker 1: There can still be dark matter. There can still be
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  Speaker 1: an occasional galaxy. But compared with the crowded regions of
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  Speaker 1: the cosmic web, These spaces are remarkably empty, and this
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  Speaker 1: is where the universe begins to look very different from
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  Speaker 1: the way it appears from Earth. From your small place
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  Speaker 1: beneath the night sky, the universe can seem full of light.
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  Speaker 1: From far away you begin to see that the light
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  Speaker 1: is gathered into islands, threads, sheets and clusters, surrounded by
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  Speaker 1: immense stretches of darkness. The darkness is not simply what
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  Speaker 1: remains after the galaxies have been placed somewhere else. The
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  Speaker 1: emptiness itself is part of the structure. It is part
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  Speaker 1: of the architecture. And these empty regions are not frozen.
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  Speaker 1: They are not perfectly still rooms in an otherwise moving universe.
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  Speaker 1: They change. They grow. They drift relative to the structures
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  Speaker 1: around them. Some can become connected with neighbouring empty regions.
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  Speaker 1: forming larger and larger areas of low density. Everything happens
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  Speaker 1: so slowly that, from the perspective of a human lifetime,
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  Speaker 1: the universe can look almost completely motionless. A galaxy appears
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  Speaker 1: fixed in the sky, a cluster appears unchanged, a distant
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  Speaker 1: filament seems to hang there forever. But this apparent stillness
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  Speaker 1: is partly an illusion created by distance. The distances are
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  Speaker 1: simply too enormous for you to watch the cosmic web
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  Speaker 1: changing with your own eyes. Galaxies are moving. Matter is gathering.
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  Speaker 1: Other matter is becoming more spread out. The great structures
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  Speaker 1: of the universe are slowly changing shape, even while the
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  Speaker 1: night sky above you seems peaceful and still. You can
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  Speaker 1: imagine floating beside one of these enormous cosmic structures now,
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  Speaker 1: Perhaps you see a long filament extending into the distance.
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  Speaker 1: Along it are galaxies, like tiny lights following an almost
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  Speaker 1: invisible thread. Then you look away from the filament. There
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  Speaker 1: are fewer lights, then fewer still, and eventually there may
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  Speaker 1: be almost none. You have not reached the edge of
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  Speaker 1: the universe. You have simply entered a quieter region. A
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  Speaker 1: region where matter is much more thinly spread. a region
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  Speaker 1: where the darkness has become wider than the light, and
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  Speaker 1: perhaps that is the first strange thing to understand about
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  Speaker 1: cosmic voids. They are not holes in the universe. They
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  Speaker 1: are not empty spaces outside the universe. They are part
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  Speaker 1: of the universe itself. They are enormous regions that formed
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  Speaker 1: naturally as matter gathered into denser structures, leaving other regions
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  Speaker 1: increasingly sparse. So when you look at the stars tonight,
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  Speaker 1: you are not really looking at a universe filled with
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  Speaker 1: countless lights. You are looking at a universe where countless
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  Speaker 1: lights have gathered into relatively small islands within an ocean
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  Speaker 1: of space, and between those islands are distances so vast
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  Speaker 1: that the darkness can stretch for hundreds of millions of light-years.
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  Speaker 1: You can let that thought become very simple. The universe
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  Speaker 1: is large, the galaxies are small, and the spaces between
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  Speaker 1: them are larger still You do not need to calculate
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  Speaker 1: those distances. You do not need to picture every galaxy.
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  Speaker 1: You can simply imagine yourself floating quietly between them, surrounded
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  Speaker 1: by darkness that is not threatening, darkness that is not
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  Speaker 1: waiting for anything, darkness that simply exists. There is nothing
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  Speaker 1: here that you need to solve, nothing you need to reach,
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  Speaker 1: nothing you need to fear. You are only drifting through
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  Speaker 1: a place where matter becomes increasingly rare, while the space
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  Speaker 1: around it continues, quietly and endlessly. And far ahead, beyond
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  Speaker 1: the familiar glow of the Milky Way, there are even
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  Speaker 1: larger regions of this cosmic emptiness waiting in the darkness,
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  Speaker 1: so vast that a journey through them would make our
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  Speaker 1: entire galaxy feel like a tiny point of light behind you.
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  Speaker 1: You are still drifting beneath the night sky, and for
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  Speaker 1: a moment you can simply remain there, looking upward without
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  Speaker 1: needing to name every star. The sky can stay quiet,
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  Speaker 1: the darkness can stay dark, and somewhere beyond that darkness
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  Speaker 1: the Milky Way is waiting, not as a distant band
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  Speaker 1: of light anymore, but as a vast structure that you
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  Speaker 1: can slowly begin to see from the outside. So, very gently,
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  Speaker 1: you begin to drift away from Earth. There is no
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  Speaker 1: sudden movement, no feeling of being pulled forward, only the
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  Speaker 1: quiet sensation of distance opening around you. Your home becomes smaller.
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  Speaker 1: The continents soften into shapes. The oceans become darker patches
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  Speaker 1: of blue. Clouds move slowly across the surface, and then
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  Speaker 1: even the clouds disappear from view. Earth becomes a small,
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  Speaker 1: delicate world, floating in a much larger darkness. You continue outward,
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  Speaker 1: The moon becomes a small companion. The sun becomes a
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  Speaker 1: small companion. more distant. The familiar planets become tiny points
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  Speaker 1: moving through an enormous region of space. And as you
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  Speaker 1: leave the solar system behind, you begin to notice something
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  Speaker 1: that is easy to forget when you are standing on Earth.
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  Speaker 1: Space is not crowded. Even here, In our own small
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  Speaker 1: neighbourhood around the sun, the distances between objects are enormous.
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  Speaker 1: There is no continuous road between the planets. There is
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  Speaker 1: mostly space. And beyond the distant outer reaches of the
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  Speaker 1: solar system, that space becomes even quieter. You continue drifting.
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  Speaker 1: The sun gradually becomes one star among many. Then the
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  Speaker 1: stars begin to gather around you. You have reached the
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  Speaker 1: Milky Way. From inside the galaxy... you usually see only
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  Speaker 1: a small part of it. But from far away, its
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  Speaker 1: larger shape begins to appear, a broad spiral of stars, gas, dust,
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  Speaker 1: and unseen matter, turning slowly through space. Hundreds of billions
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  Speaker 1: of stars are spread across this enormous structure, and yet,
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  Speaker 1: even within such a crowded galaxy, there is still an
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  Speaker 1: extraordinary amount of empty space between one star and another.
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  Speaker 1: You can imagine yourself floating above the Milky Way now.
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  Speaker 1: Below you is a glowing spiral, a river of stars,
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  Speaker 1: a vast collection of suns, worlds, clouds, and dark regions,
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  Speaker 1: and surrounding all of it is darkness. You might think
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  Speaker 1: that leaving the Milky Way would mean leaving most of
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  Speaker 1: the emptiness behind, but the opposite is true. As you
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  Speaker 1: move beyond the galaxy, the distances become larger, the stars
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  Speaker 1: become fewer, the Milky Way slowly becomes a single glowing
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  Speaker 1: island behind you, and then another galaxy appears in the distance, Andromeda.
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  Speaker 1: It is separated from the Milky Way by roughly two
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  Speaker 1: and a half million light years, an interval so enormous
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  Speaker 1: that even light, moving faster than anything else we know,
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  Speaker 1: needs millions of years to cross it. Between these two
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  Speaker 1: galaxies there is no bridge, no visible road, no wall.
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  Speaker 1: only an immense volume of space, and yet the Milky
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  Speaker 1: Way and Andromeda are not strangers drifting completely alone. They
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  Speaker 1: belong to a larger neighbourhood called the Local Group. The
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  Speaker 1: Local Group contains the Milky Way, Andromeda, the Triangulum Galaxy,
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  Speaker 1: and many smaller companion galaxies, all held together by the
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  Speaker 1: quiet influence of gravity. From your distant viewpoint, this neighbourhood
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  Speaker 1: looks almost like a tiny collection of lights floating in darkness.
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  Speaker 1: You can see galaxies here and there, surrounded by enormous distances.
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  Speaker 1: The whole group spans roughly 10 million light years. And still,
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  Speaker 1: this is only one small neighbourhood inside a much larger structure.
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  Speaker 1: You drift farther. The local group becomes smaller. The galaxies
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  Speaker 1: that once seemed enormous now look like faint points. And
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  Speaker 1: then another pattern begins to emerge. Galaxies are not scattered randomly.
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  Speaker 1: They gather into broader structures. Some appear in long threads.
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  Speaker 1: Some gather into flattened sheets. Some form dense knots where
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  Speaker 1: many galaxies and galaxy clusters collect together. These enormous patterns
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  Speaker 1: are part of the cosmic web. You can think of
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  Speaker 1: it as a very delicate framework extending across space, with
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  Speaker 1: bright galaxies resting along certain regions, while huge quiet spaces
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  Speaker 1: open between them. And somewhere near our own cosmic neighbourhood,
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  Speaker 1: one of those quiet spaces begins to appear. At first
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  Speaker 1: you might not notice it. There are still galaxies around you.
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  Speaker 1: There is still light. There are still distant structures. But
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  Speaker 1: the farther you drift, the fewer lights you see. The
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  Speaker 1: cosmic landscape begins to thin. The familiar glow of crowded
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  Speaker 1: space slowly fades. You are approaching the local void. It
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  Speaker 1: is not an empty hole cut out of the universe.
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  Speaker 1: It is more like an enormous region where matter is
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  Speaker 1: much more thinly spread than in the surrounding structures. The
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  Speaker 1: local void is thought to extend across roughly 150 million light-years,
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  Speaker 1: although its exact boundaries depend on how astronomers define and
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  Speaker 1: map such regions. Its nearest boundary is surprisingly close in
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  Speaker 1: cosmic terms, only a few million light-years from our own galaxy.
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  Speaker 1: And this means that the darkness we have been imagining
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  Speaker 1: is not some impossibly distant feature on the other side
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  Speaker 1: of the universe. A vast region of cosmic emptiness exists
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  Speaker 1: relatively near our own neighbourhood. You approach its edge. Behind you,
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  Speaker 1: the Milky Way is becoming smaller. The local group has
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  Speaker 1: almost disappeared into the distance. Ahead of you, the number
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  Speaker 1: of galaxies begins to fall. The space between the remaining
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  Speaker 1: lights grows wider, and for a moment you might imagine
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  Speaker 1: that you are approaching the edge of a great cosmic ocean.
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  Speaker 1: But there is no physical edge. Nothing suddenly changes. There
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  Speaker 1: is simply less matter ahead, less light, fewer nearby galaxies,
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  Speaker 1: more space. And this is an important part of understanding
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  Speaker 1: a cosmic void. The void does not need to be
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  Speaker 1: completely empty to feel empty. It only needs to contain
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  Speaker 1: far less matter than the regions around it. There may
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  Speaker 1: still be faint gas. There may still be dark matter.
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  Speaker 1: There may still be a few lonely galaxies. But compared
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  Speaker 1: with the denser regions surrounding it, the void is remarkably quiet.
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  Speaker 1: You can pause here, just at the boundary. There is
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  Speaker 1: no need to enter quickly. there is nowhere you need
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  Speaker 1: to reach. Behind you is the familiar structure of your
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  Speaker 1: cosmic neighbourhood. Ahead is a region where the lights become
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  Speaker 1: increasingly rare, and although everything around you appears almost motionless,
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  Speaker 1: the universe has not stopped. The galaxies are still moving.
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  Speaker 1: Gravity is still shaping the large-scale structure. Space itself continues
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  Speaker 1: to expand. The cosmic web continues its almost impossibly slow evolution.
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  Speaker 1: You simply cannot see most of that movement, because the
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  Speaker 1: distances are too large and the changes are too gentle.
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  Speaker 1: So you remain suspended there, between the familiar and the empty,
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  Speaker 1: with the Milky Way fading quietly behind you. And as
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  Speaker 1: you look into the widening darkness ahead, you may begin
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  Speaker 1: to notice something even stranger. The emptiness is not merely
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  Speaker 1: somewhere beyond the galaxies. It is woven between them. It
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  Speaker 1: surrounds them. It helps define where they gather. And the
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  Speaker 1: deeper you drift into the larger architecture of the universe,
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  Speaker 1: the more clearly you may begin to see that these
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  Speaker 1: enormous quiet regions are not accidents at the edge of creation.
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  Speaker 1: They are part of the pattern itself. You remain near
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  Speaker 1: the quiet edge of the local void. looking back toward
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  Speaker 1: the faint collection of galaxies that marks the neighbourhood you
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  Speaker 1: came from. Nothing appears to be happening. There is no sound,
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  Speaker 1: no sudden movement, no bright event unfolding in front of you.
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  Speaker 1: Only distant galaxies, suspended across enormous stretches of darkness. And yet,
• 17:40
  Speaker 1: beneath this apparent stillness, the universe is changing, very slowly,
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  Speaker 1: so slowly that even millions of years can pass. without
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  Speaker 1: producing a scene that would look different to human eyes.
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  Speaker 1: The galaxies move. Matter gathers. The empty regions become more pronounced.
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  Speaker 1: And if you could somehow speed up the universe and
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  Speaker 1: watch billions of years pass in a single quiet moment,
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  Speaker 1: the structure around you would begin to reveal itself. You
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  Speaker 1: would see that the galaxies were never simply scattered everywhere
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  Speaker 1: at random. They were gradually drawn into patterns. Long strands
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  Speaker 1: would appear. Broad sheets would emerge, dense knots would grow,
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  Speaker 1: and between them, enormous regions of lower density would open
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  Speaker 1: wider and wider. This is the cosmic web. You can
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  Speaker 1: imagine it without needing to picture an actual web hanging
• 18:34
  Speaker 1: in space. It is more like a vast arrangement of
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  Speaker 1: connected neighbourhoods, with galaxies gathering along certain paths while immense
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  Speaker 1: quiet regions occupy the spaces between them. The remarkable part
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  Speaker 1: is that this structure began with something much smaller. In
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  Speaker 1: the very early universe, matter was not distributed with perfect smoothness.
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  Speaker 1: There were tiny differences. Some regions contained just a little
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  Speaker 1: more matter than others. Some regions contained just a little less.
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  Speaker 1: The differences were extraordinarily small. Nothing dramatic. Nothing that would
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  Speaker 1: have looked important at the time. But gravity is patient.
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  Speaker 1: Given enough time, even a tiny difference can begin to matter.
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  Speaker 1: A region containing slightly more matter has a little more
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  Speaker 1: gravitational influence. It can gather a little more material. As
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  Speaker 1: it gathers more, its influence grows, and as its influence grows,
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  Speaker 1: still more matter can gather around it. It is a
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  Speaker 1: very slow process of accumulation. You can imagine a faint
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  Speaker 1: preference becoming a stronger preference, and then, after an unimaginably
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  Speaker 1: long time, becoming a structure. The denser regions gradually became
• 19:49
  Speaker 1: places where matter gathered, galaxies formed within them, galaxies gathered
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  Speaker 1: into groups, groups gathered into clusters, and the spaces between
• 19:59
  Speaker 1: these denser regions became increasingly sparse. This is one of
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  Speaker 1: the quiet secrets of cosmic voids. They did not necessarily
• 20:07
  Speaker 1: begin as enormous empty bubbles. They became empty as matter
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  Speaker 1: gathered elsewhere. The emptiness grew because the surrounding regions became
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  Speaker 1: more crowded. You might imagine standing beside a slowly forming city.
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  Speaker 1: At first, there are only a few homes. Then more
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  Speaker 1: homes appear. Then roads. Then neighbourhoods. Then larger districts. As
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  Speaker 1: the city becomes denser, the open land between the neighbourhoods
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  Speaker 1: becomes more noticeable. Cosmic structure is not exactly like a city,
• 20:38
  Speaker 1: of course. But the basic visual idea can help. Matter gathered.
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  Speaker 1: The surrounding regions became richer in structure. And the quieter
• 20:47
  Speaker 1: regions became quieter still. From far enough away, this begins
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  Speaker 1: to resemble a universe made of enormous bubbles. Not bubbles
• 20:56
  Speaker 1: with solid surfaces. Not bubbles that you could touch. But
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  Speaker 1: broad regions of relatively empty space surrounded by walls and
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  Speaker 1: filaments where galaxies are more common. You can now pull
• 21:09
  Speaker 1: farther away from the local void. The region you were
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  Speaker 1: watching becomes only one small part of a much larger pattern.
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  Speaker 1: Another void appears. Then another. Between them are faint structures.
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  Speaker 1: A long filament stretches across the darkness. Another curves away
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  Speaker 1: from it. A dense cluster sits where several structures meet.
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  Speaker 1: From this distance, the universe begins to look less like
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  Speaker 1: a collection of separate galaxies and more like a gigantic architecture.
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  Speaker 1: The galaxies are the lights, the filaments are the faint threads,
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  Speaker 1: the clusters are the denser knots, and the voids are
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  Speaker 1: the enormous quiet spaces between them. You can let that
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  Speaker 1: picture remain with you for a while. There is no
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  Speaker 1: need to memorise the names, no need to remember every structure.
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  Speaker 1: Just imagine countless faint lights gathered around enormous regions of darkness.
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  Speaker 1: And remember that the darkness itself is changing. A void
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  Speaker 1: can grow. As matter continues to gather into surrounding structures,
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  Speaker 1: the region of lower density can become increasingly spacious. Its
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  Speaker 1: boundaries can shift. Its shape can slowly change. Neighbouring voids
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  Speaker 1: can approach one another. Sometimes their boundaries become less distinct,
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  Speaker 1: and the empty regions can merge into larger areas of
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  Speaker 1: low density. Again, none of this happens quickly. There is
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  Speaker 1: no cosmic explosion. There is no sudden tearing apart. It
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  Speaker 1: is more like watching a shadow slowly spread across a
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  Speaker 1: wall while you remain almost completely still. The universe has
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  Speaker 1: all the time it needs. And because it has so
• 22:50
  Speaker 1: much time, even the gentlest processes can create structures on
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  Speaker 1: an astonishing scale. You can imagine speeding up the cosmic clock.
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  Speaker 1: Millions of years pass. Then millions more. Galaxies drift. Clusters grow.
• 23:09
  Speaker 1: Filaments stretch. Voids widen. Then you slow the clock again.
• 23:14
  Speaker 1: Everything becomes quiet. The familiar stillness returns. This is why
• 23:19
  Speaker 1: the universe can look frozen when you look at the
• 23:21
  Speaker 1: night sky. The stars seem fixed. The galaxies seem permanent.
• 23:27
  Speaker 1: The great darkness seems unchanged. But the apparent stillness is
• 23:31
  Speaker 1: only a tiny snapshot of a much longer story. The
• 23:35
  Speaker 1: cosmic web is alive with slow movement, not alive in
• 23:39
  Speaker 1: the biological sense but alive with change. Matter is constantly
• 23:44
  Speaker 1: responding to gravity, structures are gradually becoming more defined, and
• 23:49
  Speaker 1: the enormous empty regions are part of that same process.
• 23:53
  Speaker 1: You drift toward one of the voids again. Its interior
• 23:57
  Speaker 1: looks almost blank, but around its edge galaxies gather more closely.
• 24:03
  Speaker 1: You can see that the darkness has a boundary, not
• 24:06
  Speaker 1: a sharp boundary, not a wall, but a gradual transition,
• 24:11
  Speaker 1: fewer galaxies, then fewer, then almost none. And as you
• 24:17
  Speaker 1: look at that transition, you begin to understand something that
• 24:20
  Speaker 1: seems strange at first. The universe does not have empty
• 24:24
  Speaker 1: space on one side and galaxies on the other. The
• 24:28
  Speaker 1: two are connected. The emptiness helps define where matter gathers.
• 24:33
  Speaker 1: and the matter helps define the shape of the emptiness.
• 24:36
  Speaker 1: They are part of the same enormous pattern. You can
• 24:39
  Speaker 1: stay with that thought for a moment. The universe is
• 24:43
  Speaker 1: not a perfectly filled room. It is not a collection
• 24:46
  Speaker 1: of lights floating randomly through darkness. It is a slowly
• 24:50
  Speaker 1: changing arrangement of dense places, and quiet places, of glowing
• 24:56
  Speaker 1: structures and enormous spaces between them, and somewhere within that pattern,
• 25:01
  Speaker 1: the local void is only one of countless regions where
• 25:04
  Speaker 1: matter has become unusually sparse. Farther away, there are voids
• 25:09
  Speaker 1: much larger. Some stretch across hundreds of millions of light-years,
• 25:15
  Speaker 1: and as you continue drifting toward them, another gentle question
• 25:19
  Speaker 1: begins to appear. If galaxies are surrounded by all this
• 25:22
  Speaker 1: empty space, and if gravity is constantly moving matter toward
• 25:27
  Speaker 1: denser regions... then why do some galaxies remain near the
• 25:30
  Speaker 1: edges of the voids at all? Why do they not
• 25:33
  Speaker 1: simply disappear into the darkness? The answer is hidden in
• 25:37
  Speaker 1: the quiet pull of everything around them. You are drifting
• 25:43
  Speaker 1: near the edge of the great emptiness now. Behind you,
• 25:46
  Speaker 1: the galaxies of the surrounding cosmic web form a faint
• 25:50
  Speaker 1: pattern of light. Ahead of you, the darkness becomes wider.
• 25:55
  Speaker 1: There are still a few distant galaxies here and there,
• 25:58
  Speaker 1: but they are becoming harder to find, separated from one
• 26:02
  Speaker 1: another by enormous distances. You can simply remain here for
• 26:06
  Speaker 1: a while. There is nothing to reach, nothing to measure,
• 26:10
  Speaker 1: nothing you need to understand all at once, just this
• 26:13
  Speaker 1: quiet boundary, where the brighter parts of the cosmic web
• 26:17
  Speaker 1: slowly give way to the darker spaces between them. And
• 26:21
  Speaker 1: as you remain still, you may begin to wonder why
• 26:24
  Speaker 1: the galaxies seem to gather here. If the universe is
• 26:27
  Speaker 1: expanding and And if galaxies are always moving, why do
• 26:31
  Speaker 1: so many of them remain near the edges of these
• 26:33
  Speaker 1: enormous empty regions? Why don't they simply wander deeper into
• 26:38
  Speaker 1: the darkness? The answer begins with something very familiar. Gravity.
• 26:44
  Speaker 1: You already know gravity from your everyday life. It keeps
• 26:47
  Speaker 1: your feet on the ground. It keeps the moon near Earth.
• 26:52
  Speaker 1: It keeps Earth moving around the sun. But on the
• 26:55
  Speaker 1: largest scales, gravity has another quiet role. It helps shape
• 27:00
  Speaker 1: where matter gathers across the universe. Imagine yourself surrounded by
• 27:04
  Speaker 1: an enormous landscape of matter. In one direction, there are
• 27:08
  Speaker 1: galaxy clusters, dense collections of galaxies containing huge amounts of matter.
• 27:15
  Speaker 1: In another direction, there are long filaments, those faint threads
• 27:19
  Speaker 1: of the cosmic web where galaxies gather. Behind you, there
• 27:24
  Speaker 1: may be another wall of galaxies, and around you, inside
• 27:28
  Speaker 1: the void, there is much less matter. The difference is
• 27:31
  Speaker 1: subtle at first, but across hundreds of millions of light years,
• 27:36
  Speaker 1: even subtle differences can shape the motion of galaxies. A
• 27:40
  Speaker 1: galaxy does not need to be pushed away from a void.
• 27:44
  Speaker 1: There does not need to be an invisible wall. Instead,
• 27:48
  Speaker 1: the surrounding matter simply has a stronger gravitational influence. You
• 27:53
  Speaker 1: can imagine standing in a very wide, shallow valley. There
• 27:57
  Speaker 1: is no visible force telling you where to go but
• 28:00
  Speaker 1: the landscape itself gently guides your movement. Cosmic voids are
• 28:05
  Speaker 1: not exactly valleys of course but the image gives you
• 28:08
  Speaker 1: a feeling for what is happening. Matter has gathered more
• 28:12
  Speaker 1: strongly around the surrounding structures. The regions inside the void
• 28:16
  Speaker 1: contain much less matter so galaxies near the boundary are
• 28:20
  Speaker 1: influenced by the larger structures around them. They tend to
• 28:24
  Speaker 1: move with the broader flow of matter rather than simply
• 28:27
  Speaker 1: wandering freely into the empty centre. This is why the
• 28:31
  Speaker 1: edges of voids can become surprisingly interesting places. The boundary
• 28:37
  Speaker 1: is not a sharp line. There is no sign telling
• 28:40
  Speaker 1: you that you have crossed from one kind of space
• 28:42
  Speaker 1: into another. Instead, the number of galaxies slowly changes. You
• 28:48
  Speaker 1: see one, then another, then several more, and as you
• 28:52
  Speaker 1: move farther toward the interior, those lights become less frequent.
• 28:56
  Speaker 1: The transition is gradual. It feels almost like walking away
• 29:00
  Speaker 1: from a distant town at night. At first you can
• 29:03
  Speaker 1: still see many lights behind you, then only a few,
• 29:07
  Speaker 1: then perhaps one light far away, then darkness. But unlike
• 29:11
  Speaker 1: a town, a cosmic void has no road leading back home.
• 29:16
  Speaker 1: The distances are simply too large. And there is something
• 29:19
  Speaker 1: else quietly happening here. The universe itself is expanding. On
• 29:25
  Speaker 1: very large scales, distant regions of space become increasingly separated,
• 29:30
  Speaker 1: but gravity continues to hold together structures that are close
• 29:34
  Speaker 1: enough to remain bound. This creates a delicate balance. Some
• 29:38
  Speaker 1: groups of galaxies remain together because their mutual gravity is
• 29:43
  Speaker 1: strong enough to keep them connected. Other structures, separated by
• 29:47
  Speaker 1: enormous distances, gradually become more isolated as cosmic expansion continues.
• 29:54
  Speaker 1: Inside a void, where matter is already sparse, The effects
• 29:59
  Speaker 1: of this large-scale expansion become especially important. The void can
• 30:04
  Speaker 1: continue to grow relative to the denser structures around it.
• 30:08
  Speaker 1: Its interior becomes more sparse, its boundaries slowly shift, and
• 30:13
  Speaker 1: the surrounding filaments can become increasingly separated from one another. Again,
• 30:19
  Speaker 1: nothing happens quickly. If you watched the same region for
• 30:22
  Speaker 1: a thousand years, you would not see a dramatic transformation.
• 30:27
  Speaker 1: Even over many human generations, the change would be almost
• 30:31
  Speaker 1: impossible to notice. But the universe is patient. Give it
• 30:35
  Speaker 1: millions of years. Then billions. And the slow movements begin
• 30:40
  Speaker 1: to add up. A galaxy can gradually change its position
• 30:44
  Speaker 1: within the cosmic landscape. A filament can evolve. A void
• 30:48
  Speaker 1: can become larger. Two neighbouring voids can slowly approach one another.
• 30:53
  Speaker 1: The great architecture changes. but it changes on a timescale
• 30:57
  Speaker 1: far beyond ordinary human experience. You can let yourself drift
• 31:01
  Speaker 1: deeper into the quiet region now. The galaxies behind you
• 31:05
  Speaker 1: become dimmer. The gravitational structures around you become more distant.
• 31:10
  Speaker 1: The sky becomes increasingly empty. But it is important not
• 31:14
  Speaker 1: to imagine that the centre of a void is completely
• 31:17
  Speaker 1: cut off from the rest of the universe. There can
• 31:20
  Speaker 1: still be faint matter here. There can still be thin
• 31:23
  Speaker 1: clouds of gas. there can still be dark matter. And,
• 31:27
  Speaker 1: very occasionally, there can be galaxies. These rare galaxies are
• 31:32
  Speaker 1: among the most interesting inhabitants of the cosmic web. Because
• 31:36
  Speaker 1: a galaxy living in a crowded region has a very
• 31:39
  Speaker 1: different neighbourhood from a galaxy living in a sparse one.
• 31:43
  Speaker 1: In a dense region, galaxies may pass relatively close to
• 31:46
  Speaker 1: one another. Their gravity can disturb their shapes. Some can collide,
• 31:52
  Speaker 1: some can merge. Gas can be compressed. Star formation can change.
• 31:57
  Speaker 1: The galaxy can be constantly responding to the presence of
• 32:01
  Speaker 1: its neighbours. But a galaxy inside a sparse environment may
• 32:05
  Speaker 1: experience far fewer of these encounters. Its surroundings can be quieter.
• 32:10
  Speaker 1: Its history can be more isolated. It may spend enormous
• 32:14
  Speaker 1: stretches of cosmic time without another galaxy coming close enough
• 32:19
  Speaker 1: to strongly disturb it. You can imagine one such galaxy now,
• 32:23
  Speaker 1: a faint point of light surrounded by almost nothing, it
• 32:27
  Speaker 1: is not completely alone. It is simply very, very far
• 32:31
  Speaker 1: from its neighbours. Its stars continue to shine. Its gas
• 32:36
  Speaker 1: continues to move. Its gravity continues to hold the galaxy together.
• 32:41
  Speaker 1: And around it, the void remains almost silent. There is
• 32:45
  Speaker 1: something strangely peaceful about this picture. The emptiness is not
• 32:50
  Speaker 1: attacking the galaxy. It is not pulling it into some
• 32:53
  Speaker 1: dark centre. It simply provides fewer things to interact with.
• 32:58
  Speaker 1: The galaxy is allowed to remain in its quiet corner
• 33:01
  Speaker 1: of the cosmic landscape. And perhaps this is why cosmic
• 33:05
  Speaker 1: voids are so fascinating. They reveal that loneliness in the
• 33:09
  Speaker 1: universe is not just about distance. It is also about environment.
• 33:15
  Speaker 1: A galaxy surrounded by thousands of neighbouring galaxies belongs to
• 33:19
  Speaker 1: one kind of cosmic neighbourhood. A galaxy separated from most
• 33:23
  Speaker 1: of its neighbours by enormous stretches of space belongs to another.
• 33:28
  Speaker 1: The same laws of nature are present in both places.
• 33:32
  Speaker 1: Gravity still works, stars are still born, gas still moves,
• 33:37
  Speaker 1: light still travels, but the rhythm can be different. And
• 33:41
  Speaker 1: as you continue floating here, watching the faint galaxy ahead
• 33:44
  Speaker 1: of you, you may begin to wonder what happens to
• 33:47
  Speaker 1: a galaxy that when almost all of its neighbours are
• 33:50
  Speaker 1: gone from sight? Does it become quieter? Does it age differently?
• 33:55
  Speaker 1: Could some of these lonely galaxies continue forming stars long
• 33:59
  Speaker 1: after more crowded regions have grown still? For now, the
• 34:03
  Speaker 1: answer waits in that tiny blue point of light, shining
• 34:06
  Speaker 1: softly inside the darkness. You remain suspended near the quiet
• 34:13
  Speaker 1: edge of the void, with the faint galaxy behind you
• 34:16
  Speaker 1: slowly becoming smaller. There is still light in that direction.
• 34:21
  Speaker 1: A few distant galaxies remain visible, tiny points scattered across
• 34:25
  Speaker 1: the darkness, reminders that somewhere behind you there are clusters, filaments,
• 34:31
  Speaker 1: and great gatherings of matter. But you are drifting farther
• 34:35
  Speaker 1: away from them now. The lights become thinner, the spaces
• 34:39
  Speaker 1: between them become wider, and after a while, the universe
• 34:43
  Speaker 1: begins to feel less like a collection of places, and
• 34:46
  Speaker 1: more like an enormous distance. You continue outward, gently, without
• 34:52
  Speaker 1: any sense of urgency. The local void gradually disappears behind you.
• 34:57
  Speaker 1: Then the larger structures surrounding it begin to fade as well.
• 35:01
  Speaker 1: From this distance you can start to see just how
• 35:04
  Speaker 1: many empty regions exist between the denser parts of the
• 35:07
  Speaker 1: cosmic web. There are vast spaces here and there, separated
• 35:12
  Speaker 1: by long threads of galaxies and great concentrations of matter.
• 35:17
  Speaker 1: Some are relatively modest. Others stretch across hundreds of millions
• 35:21
  Speaker 1: of light-years, and among these enormous regions is one that
• 35:25
  Speaker 1: has become famous for its unusual emptiness. The Boötes Supervoid.
• 35:31
  Speaker 1: You begin moving toward it. At first, nothing looks especially different.
• 35:36
  Speaker 1: There are still galaxies in the distance. There is still
• 35:39
  Speaker 1: a faint glow. But as you continue, those galaxies become
• 35:44
  Speaker 1: less common. One disappears behind you. then another, then another.
• 35:49
  Speaker 1: The familiar points of light are slowly replaced by longer
• 35:53
  Speaker 1: stretches of darkness. You might imagine yourself walking away from
• 35:57
  Speaker 1: a small village on a clear night. At first, every
• 36:00
  Speaker 1: window behind you is visible. Then only a few lights remain.
• 36:05
  Speaker 1: Eventually the village becomes one faint glow, and then even
• 36:09
  Speaker 1: that disappears. But here, the distance is not measured in footsteps.
• 36:14
  Speaker 1: It is measured in millions of light-years. the Boötes supervoid,
• 36:19
  Speaker 1: is often described as roughly 300 million light-years across, an
• 36:24
  Speaker 1: almost unimaginable scale. You could travel through such a distance
• 36:28
  Speaker 1: for longer than the entire span of human civilisation, and
• 36:32
  Speaker 1: still be crossing what is, on a cosmic map, only
• 36:36
  Speaker 1: one enormous region of emptier space. And this is what
• 36:40
  Speaker 1: makes the supervoid so strange. A region this large might
• 36:44
  Speaker 1: seem as though it should be filled with galaxies. There
• 36:47
  Speaker 1: is so much room, so many places where stars could shine,
• 36:52
  Speaker 1: so many possible paths through space. And yet, compared with
• 36:57
  Speaker 1: the surrounding cosmic landscape, remarkably few galaxies are found within it.
• 37:03
  Speaker 1: You continue toward the centre. The darkness grows deeper. Not
• 37:07
  Speaker 1: because some curtain has fallen across the universe, and not
• 37:11
  Speaker 1: because light has suddenly stopped existing, but simply because there
• 37:15
  Speaker 1: are fewer nearby sources of light. There are fewer galaxies
• 37:19
  Speaker 1: to illuminate the darkness around you, fewer familiar landmarks, fewer
• 37:24
  Speaker 1: bright structures. Your sense of direction becomes almost meaningless. There
• 37:30
  Speaker 1: is no natural floor beneath you, no ceiling above you,
• 37:34
  Speaker 1: no nearby horizon, only distance in every direction, and you
• 37:39
  Speaker 1: can let yourself become very still here. You do not
• 37:43
  Speaker 1: need to imagine the darkness as frightening. There is nothing
• 37:46
  Speaker 1: chasing you. Nothing waiting for you. Nothing moving toward you.
• 37:51
  Speaker 1: The darkness is simply the result of distance, sparsity, and
• 37:55
  Speaker 1: the enormous spaces between the places where matter has gathered.
• 38:00
  Speaker 1: You are safe. There is nothing to do. You can
• 38:03
  Speaker 1: simply drift. And yet, the deeper you move into the supervoid,
• 38:08
  Speaker 1: the more interesting the emptiness becomes. Because even here the
• 38:12
  Speaker 1: universe has not completely disappeared. There are traces. faint structures,
• 38:18
  Speaker 1: subtle threads of matter. Dark matter, invisible to your eyes,
• 38:23
  Speaker 1: can still be associated with the underlying architecture of the
• 38:27
  Speaker 1: cosmic web. You cannot look at dark matter directly and
• 38:31
  Speaker 1: see a glowing strand crossing the darkness. Instead, astronomers infer
• 38:36
  Speaker 1: its presence from the way gravity shapes visible matter and light.
• 38:41
  Speaker 1: So imagine something almost invisible beneath the darkness. like a
• 38:45
  Speaker 1: delicate framework that you cannot see directly but whose influence
• 38:49
  Speaker 1: can still be felt. The emptiness has structure beneath it.
• 38:54
  Speaker 1: Even the quietest places are connected to the larger universe,
• 38:58
  Speaker 1: and sometimes among these faint structures there are galaxies, rare ones,
• 39:03
  Speaker 1: small ones, distant ones. A tiny bluish point might appear
• 39:08
  Speaker 1: far ahead of you. It seems almost too faint to
• 39:11
  Speaker 1: be a galaxy at all, but it is. A collection
• 39:15
  Speaker 1: of stars, gas, dust and dark matter existing inside an
• 39:20
  Speaker 1: environment where neighbouring galaxies are extraordinarily far away. You drift closer.
• 39:26
  Speaker 1: The point remains tiny. There is no dramatic transformation. It
• 39:30
  Speaker 1: simply becomes a little easier to recognise. A galaxy. One
• 39:35
  Speaker 1: small island of light in an enormous cosmic desert. Then
• 39:39
  Speaker 1: you look around again, and the darkness returns. This is
• 39:43
  Speaker 1: what makes the BOTUS supervoid so difficult to imagine from Earth.
• 39:47
  Speaker 1: Your mind naturally expects large spaces to contain many things.
• 39:51
  Speaker 1: A large room has furniture. A large city has buildings.
• 39:56
  Speaker 1: A large ocean has islands, ships, waves, and life. But
• 40:01
  Speaker 1: a cosmic void can be enormous and still contain remarkably
• 40:04
  Speaker 1: little visible matter. Its emptiness does not become less strange
• 40:08
  Speaker 1: because it is large. It becomes stranger because the larger
• 40:13
  Speaker 1: you make the empty space... the more difficult it becomes
• 40:16
  Speaker 1: for the human mind to picture what almost nothing actually means.
• 40:21
  Speaker 1: You can stay with that thought for a moment. 300
• 40:24
  Speaker 1: million light years. Not as a number you need to calculate,
• 40:28
  Speaker 1: just as a feeling of distance. A journey so long
• 40:31
  Speaker 1: that ordinary human measurements stop being useful. A region so
• 40:36
  Speaker 1: broad that your entire galaxy would become almost insignificant within it.
• 40:41
  Speaker 1: And yet … Somewhere inside this enormous darkness, stars still shine. Somewhere,
• 40:47
  Speaker 1: gas still moves. Somewhere, gravity still gathers matter. Somewhere, a
• 40:53
  Speaker 1: small galaxy continues its quiet existence. The supervoid is therefore
• 40:58
  Speaker 1: not truly a place where nothing happens. It is a
• 41:01
  Speaker 1: place where almost everything is separated by an extraordinary amount
• 41:05
  Speaker 1: of space. And perhaps that is the deeper meaning of
• 41:08
  Speaker 1: cosmic emptiness. Emptiness does not mean that the universe has stopped.
• 41:13
  Speaker 1: It means that the distances between the remaining things have
• 41:17
  Speaker 1: become enormous. You drift past the faint galaxy, allowing its
• 41:21
  Speaker 1: light to become smaller behind you. Ahead, the darkness opens again.
• 41:26
  Speaker 1: Behind you, another tiny point of light begins to fade,
• 41:31
  Speaker 1: and somewhere between those two distant galaxies, there is almost
• 41:34
  Speaker 1: nothing for your eyes to hold onto. Only space. Only darkness.
• 41:40
  Speaker 1: Only the quiet architecture of a universe whose largest structures
• 41:43
  Speaker 1: may be defined not by what is there, but by
• 41:46
  Speaker 1: what is missing. For a little while, you can simply
• 41:50
  Speaker 1: float here, without direction, without destination, surrounded by an emptiness
• 41:56
  Speaker 1: that stretches farther than you can comfortably imagine. And perhaps,
• 42:01
  Speaker 1: somewhere within that vast darkness, another faint blue light is waiting,
• 42:06
  Speaker 1: almost too small to notice. belonging to a galaxy that
• 42:09
  Speaker 1: has learned to live in one of the loneliest environments
• 42:12
  Speaker 1: the universe can provide. The faint blue light remains ahead
• 42:19
  Speaker 1: of you. You have been drifting through the darkness for
• 42:22
  Speaker 1: what feels like an immeasurable amount of time, although in
• 42:25
  Speaker 1: this place time is difficult to feel. There are no clocks,
• 42:29
  Speaker 1: no sunrise, no sunset, only distant light moving across enormous
• 42:35
  Speaker 1: stretches of space. And there... Almost hidden inside the darkness
• 42:40
  Speaker 1: is one small galaxy. You can drift toward it slowly.
• 42:44
  Speaker 1: There is no need to hurry. At first, it is
• 42:47
  Speaker 1: only a point, a tiny blue glow, surrounded by blackness. Then,
• 42:53
  Speaker 1: as you imagine yourself moving closer, the point begins to
• 42:56
  Speaker 1: reveal a little more of its shape. A collection of stars.
• 43:01
  Speaker 1: A small reservoir of gas. A quiet gravitational system. A galaxy.
• 43:07
  Speaker 1: It is not the largest galaxy in the universe. It
• 43:10
  Speaker 1: is not surrounded by a crowded neighbourhood. In fact, that
• 43:14
  Speaker 1: may be the most interesting thing about it. It is
• 43:17
  Speaker 1: living in a place where there are very few other
• 43:20
  Speaker 1: galaxies nearby. Most galaxies are not completely isolated. They exist
• 43:25
  Speaker 1: within groups, clusters, filaments, and other parts of the cosmic web.
• 43:31
  Speaker 1: They have neighbours, sometimes many neighbours, and those neighbours matter greatly.
• 43:36
  Speaker 1: Gravity can reach across enormous distances. Galaxies can pass near
• 43:41
  Speaker 1: one another. Their shapes can be disturbed. Their gas can
• 43:45
  Speaker 1: be rearranged. Sometimes two galaxies can slowly come together and
• 43:49
  Speaker 1: merge into a larger system. These encounters are part of
• 43:53
  Speaker 1: the long history of galaxy evolution. But imagine living somewhere
• 43:57
  Speaker 1: with almost no neighbours. No nearby galaxy passing across your sky.
• 44:02
  Speaker 1: No large cluster surrounding you. No constant gravitational disturbance from
• 44:07
  Speaker 1: a crowded cosmic environment. That is the unusual world of
• 44:11
  Speaker 1: a galaxy inside a cosmic void. The same laws of
• 44:16
  Speaker 1: nature are still present. Gravity still holds the galaxy together.
• 44:20
  Speaker 1: Stars still move around the centre. Gas still drifts through
• 44:25
  Speaker 1: the galaxy. Stars are still born and, eventually, fade away.
• 44:30
  Speaker 1: But the neighbourhood is quieter. and that quiet environment can
• 44:34
  Speaker 1: leave a different imprint. Some galaxies found in voids tend
• 44:38
  Speaker 1: to be smaller and relatively blue. The blue colour is
• 44:42
  Speaker 1: not a strange colour painted across the galaxy. It can
• 44:45
  Speaker 1: come from the light of relatively young stars. Stars that
• 44:49
  Speaker 1: formed more recently can contribute strongly to the blue appearance
• 44:53
  Speaker 1: of a galaxy. So when you see that faint blue
• 44:56
  Speaker 1: glow in the darkness, you can imagine that some of
• 44:59
  Speaker 1: its light is coming from stars that are still comparatively young.
• 45:04
  Speaker 1: The galaxy has not completely stopped changing. It still has
• 45:08
  Speaker 1: a history unfolding. Gas can remain available. New stars can
• 45:12
  Speaker 1: continue to form. And because the galaxy is surrounded by
• 45:16
  Speaker 1: so much empty space, some parts of its history can
• 45:20
  Speaker 1: unfold without the same frequency of close encounters found in
• 45:23
  Speaker 1: denser environments. You can imagine two galaxies now. One lives
• 45:29
  Speaker 1: in a crowded region of the cosmic web, Around it
• 45:32
  Speaker 1: are many neighbours. Gravity is always doing something. A nearby
• 45:36
  Speaker 1: galaxy passes by. Another approaches. Gas shifts. Structures interact. The
• 45:42
  Speaker 1: galaxy is part of a busy cosmic neighbourhood. The other
• 45:46
  Speaker 1: galaxy lives here, inside the quiet. Its nearest neighbours may
• 45:50
  Speaker 1: be incredibly far away. Nothing is completely still, but there
• 45:54
  Speaker 1: are fewer large disturbances. The galaxy has more room to
• 45:58
  Speaker 1: simply remain itself. This does not mean that every void
• 46:02
  Speaker 1: galaxy evolves slowly, and it does not mean that every
• 46:06
  Speaker 1: isolated galaxy forms stars in exactly the same way. Nature
• 46:10
  Speaker 1: is more varied than that. But the environment matters. A
• 46:14
  Speaker 1: crowded region can bring more gravitational interactions, a sparse region
• 46:19
  Speaker 1: can bring fewer, and fewer interactions can mean fewer opportunities
• 46:23
  Speaker 1: for certain kinds of disruption. So, in a very gentle sense,
• 46:28
  Speaker 1: Some void galaxies may experience a quieter evolutionary history. You
• 46:33
  Speaker 1: might think of them as galaxies living in slow neighbourhoods.
• 46:37
  Speaker 1: Not frozen, not inactive, simply less disturbed. The distinction is subtle,
• 46:44
  Speaker 1: but across billions of years, subtle differences can become important.
• 46:48
  Speaker 1: You can let yourself drift around this small galaxy now.
• 46:52
  Speaker 1: Perhaps you see a faint spiral shape. Perhaps it is
• 46:56
  Speaker 1: less organised. Perhaps it is simply a soft patch of light.
• 47:01
  Speaker 1: You do not need to decide exactly what it looks like.
• 47:04
  Speaker 1: Just imagine the stars. Countless tiny suns moving through a
• 47:08
  Speaker 1: gravitational landscape. Some are old. Some are young. Some are
• 47:13
  Speaker 1: forming now. Others have already completed their long lives. And
• 47:18
  Speaker 1: between all of them is more space. Even inside a
• 47:21
  Speaker 1: galaxy there is an extraordinary amount of emptiness. The stars
• 47:25
  Speaker 1: are not packed together like grains of sand. They are
• 47:29
  Speaker 1: separated by enormous distances. So there are layers of emptiness here. First,
• 47:35
  Speaker 1: the space between galaxies. Then the space between stars. And
• 47:40
  Speaker 1: then the quiet regions between the smaller pieces of matter
• 47:43
  Speaker 1: that make up those stars and their surrounding worlds. The
• 47:47
  Speaker 1: universe repeats this feeling of spaciousness at many scales. You
• 47:51
  Speaker 1: can remain with the galaxy for a while. Its light
• 47:54
  Speaker 1: is faint, but it is persistent. It has crossed an
• 47:58
  Speaker 1: enormous distance to reach you, and somewhere inside that light
• 48:02
  Speaker 1: is information about the galaxy's history, the ages of its stars,
• 48:07
  Speaker 1: the gas from which some stars formed, the effects of
• 48:11
  Speaker 1: its surroundings. All of this is carried outward as light,
• 48:16
  Speaker 1: a tiny messenger crossing the darkness. You may also wonder
• 48:20
  Speaker 1: whether such a galaxy could remain active for a very
• 48:22
  Speaker 1: long time, This is where the story becomes more speculative.
• 48:27
  Speaker 1: If a galaxy in a sparse environment retains enough gas,
• 48:31
  Speaker 1: it may continue forming stars for longer than some galaxies
• 48:34
  Speaker 1: in more crowded environments. That does not mean that a
• 48:38
  Speaker 1: void galaxy will live forever. Stars still use fuel, gas
• 48:42
  Speaker 1: still changes, galaxies still evolve. But the quiet surroundings may
• 48:47
  Speaker 1: allow certain galaxies to remain relatively undisturbed for immense periods
• 48:52
  Speaker 1: of cosmic time. And this leads to a strangely beautiful possibility.
• 48:57
  Speaker 1: Far in the future, when many regions of the universe
• 49:00
  Speaker 1: have become quieter, some isolated galaxies may still contain stars.
• 49:06
  Speaker 1: Perhaps a small galaxy in a sparse region could continue
• 49:09
  Speaker 1: shining while much of the surrounding cosmic landscape grows darker.
• 49:14
  Speaker 1: Perhaps some of the later generations of stars could form
• 49:18
  Speaker 1: in these long-lived environments. This is not a prediction carved
• 49:22
  Speaker 1: into the future. It is a possibility that depends on
• 49:25
  Speaker 1: how galaxies retain gas, how stars form, and how the
• 49:30
  Speaker 1: expansion of the universe continues. But it gives the void
• 49:34
  Speaker 1: a different meaning. The emptiness is not only a place
• 49:37
  Speaker 1: where galaxies are missing. It can also be a place
• 49:40
  Speaker 1: where a few galaxies have room to endure. You look
• 49:44
  Speaker 1: again at the faint blue point. It is surrounded by darkness.
• 49:49
  Speaker 1: Yet it is not insignificant. Its stars are shining. Its
• 49:53
  Speaker 1: gas is moving. Its gravity is holding everything together. And
• 49:58
  Speaker 1: for now, it continues quietly. Perhaps that is one of
• 50:02
  Speaker 1: the most peaceful things about the cosmic web. Even in
• 50:06
  Speaker 1: the emptiest places there can still be light. Even where
• 50:10
  Speaker 1: galaxies are rare, a galaxy can still exist. And even
• 50:14
  Speaker 1: when the surrounding universe seems almost completely silent, a small
• 50:19
  Speaker 1: island of stars can continue its slow life. You drift
• 50:23
  Speaker 1: a little farther away. The galaxy becomes smaller again. Its
• 50:27
  Speaker 1: blue light softens. The darkness around it becomes larger, and
• 50:32
  Speaker 1: as that tiny glow remains behind you, another possibility begins
• 50:36
  Speaker 1: to emerge. one that belongs not to the present universe,
• 50:40
  Speaker 1: but to an unimaginably distant future, when the spaces between
• 50:45
  Speaker 1: galaxies may become even wider, and the great empty regions
• 50:49
  Speaker 1: may quietly continue to grow. You are still floating inside
• 50:55
  Speaker 1: the great quiet. The faint galaxy from before has almost
• 50:59
  Speaker 1: disappeared behind you, its blue light becoming softer and smaller.
• 51:04
  Speaker 1: until it is difficult to tell whether you are still
• 51:06
  Speaker 1: seeing the galaxy itself, or simply remembering where it was.
• 51:11
  Speaker 1: Ahead of you, there is mostly darkness. Around you, there
• 51:15
  Speaker 1: is mostly space. And for a moment, everything feels perfectly still.
• 51:21
  Speaker 1: But the universe is not still. Space itself is changing.
• 51:25
  Speaker 1: Very slowly, very gently, across distances so large that the
• 51:30
  Speaker 1: movement is almost impossible to imagine. You can think of
• 51:33
  Speaker 1: yourself as floating inside a vast fabric, one that is
• 51:37
  Speaker 1: being stretched so gradually that you would never feel the
• 51:40
  Speaker 1: motion beneath you. The galaxies are not simply racing through
• 51:44
  Speaker 1: a fixed, unchanging room. On the largest scales, the room
• 51:49
  Speaker 1: itself is expanding. Distances between many distant galaxies increase with time,
• 51:55
  Speaker 1: and this expansion has been happening for billions of years.
• 51:58
  Speaker 1: For a long time, gravity worked to slow that expansion.
• 52:03
  Speaker 1: Matter gathered together, galaxies formed, clusters became denser, the cosmic
• 52:09
  Speaker 1: web took shape. But the universe contains something else, something
• 52:14
  Speaker 1: much harder to understand, something astronomers call dark energy. The
• 52:20
  Speaker 1: name sounds mysterious because, in many ways, it is. Dark
• 52:25
  Speaker 1: energy is not a substance that you can hold in
• 52:27
  Speaker 1: your hands. It is not a glowing cloud hidden somewhere
• 52:31
  Speaker 1: between the galaxies. Instead, it is the name given to
• 52:35
  Speaker 1: whatever is responsible for the accelerated expansion of the universe
• 52:39
  Speaker 1: in our current cosmological picture. You do not need to
• 52:43
  Speaker 1: know exactly what dark energy is to follow its quiet effect.
• 52:47
  Speaker 1: You can simply imagine that the fabric of cosmic space
• 52:50
  Speaker 1: is gradually being stretched, and as it stretches, distant structures
• 52:55
  Speaker 1: become farther apart. This becomes especially important inside the emptier regions.
• 53:01
  Speaker 1: Remember the void. a region where matter is already sparse,
• 53:06
  Speaker 1: a region surrounded by denser structures, a region where galaxies
• 53:10
  Speaker 1: are separated by enormous distances. Now imagine that the space
• 53:15
  Speaker 1: around this region continues to expand. The void does not
• 53:19
  Speaker 1: sit inside a frozen universe. Its surroundings are changing too.
• 53:23
  Speaker 1: The distances between its boundaries and nearby structures can grow.
• 53:28
  Speaker 1: The empty region can become more pronounced. And the matter
• 53:31
  Speaker 1: that remains tends to become increasingly concentrated in the surrounding
• 53:35
  Speaker 1: walls and filaments. So the contrast grows. The empty becomes emptier.
• 53:41
  Speaker 1: The dense becomes more distinct. The cosmic landscape slowly separates
• 53:46
  Speaker 1: into brighter islands and wider oceans of darkness. You can
• 53:50
  Speaker 1: imagine looking at this from very far away. At first,
• 53:54
  Speaker 1: the universe appears like a delicate network. Many galaxies are visible.
• 53:59
  Speaker 1: Filaments connect one region to another. Clusters shine like small
• 54:03
  Speaker 1: knots of light. The voids are large, but they are
• 54:07
  Speaker 1: surrounded by plenty of structure. Now allow billions of years
• 54:11
  Speaker 1: to pass. The expansion continues. The distances increase. The filaments
• 54:17
  Speaker 1: become more separated. The clusters remain bound together where gravity
• 54:22
  Speaker 1: is strong enough. But the space between those structures grows wider.
• 54:27
  Speaker 1: Another enormous stretch of darkness opens between them, then another,
• 54:32
  Speaker 1: and another. Nothing tears apart suddenly. There is no cosmic explosion.
• 54:37
  Speaker 1: The universe simply becomes more spacious, more distant, more isolated.
• 54:42
  Speaker 1: You can let yourself drift through this changing landscape. Imagine
• 54:47
  Speaker 1: one galaxy cluster far behind you. It remains together, its
• 54:51
  Speaker 1: galaxies still orbiting within the gravitational influence of the cluster.
• 54:56
  Speaker 1: Far ahead, Another cluster continues its own quiet existence. Between
• 55:01
  Speaker 1: them is a growing distance. The two structures are not
• 55:05
  Speaker 1: necessarily being ripped apart internally. They are simply becoming increasingly
• 55:10
  Speaker 1: separated from one another as the universe expands. This distinction
• 55:15
  Speaker 1: is gentle, but important. Gravity can hold smaller structures together.
• 55:20
  Speaker 1: The Milky Way remains a galaxy. Stars remain bound to it.
• 55:26
  Speaker 1: A galaxy cluster, can remain a cluster. But on the
• 55:29
  Speaker 1: largest scales, cosmic expansion continues to increase the distance between
• 55:34
  Speaker 1: structures that are not gravitationally bound to one another, and
• 55:38
  Speaker 1: the voids lie naturally within this expanding landscape. Because they
• 55:43
  Speaker 1: contain less matter, they are already the quietest parts of
• 55:47
  Speaker 1: the cosmic web. As time passes, their emptiness can become
• 55:51
  Speaker 1: increasingly pronounced. You might imagine an enormous room in which
• 55:56
  Speaker 1: a few groups of people are standing together. At first,
• 56:00
  Speaker 1: the groups are separated by moderate distances. Then the room
• 56:04
  Speaker 1: itself begins to expand. The people within each group can
• 56:08
  Speaker 1: remain together. But the groups move farther apart because the
• 56:11
  Speaker 1: space between them is becoming larger. The empty spaces between
• 56:16
  Speaker 1: the groups become the dominant feature. Again, the universe is
• 56:20
  Speaker 1: not exactly a room, but the image gives you something
• 56:24
  Speaker 1: soft to hold on to. Expansion changes the distances. Gravity
• 56:29
  Speaker 1: preserves some connections. And the combination gradually reshapes the cosmic web.
• 56:35
  Speaker 1: There is another quiet consequence. As galaxies become more isolated,
• 56:40
  Speaker 1: opportunities for interaction become rarer. A galaxy that once had
• 56:45
  Speaker 1: several nearby neighbours may eventually find those neighbours far beyond
• 56:50
  Speaker 1: its immediate cosmic neighbourhood. The sky around it becomes darker.
• 56:55
  Speaker 1: Not because its stars stop shining, not because the galaxy disappears,
• 57:00
  Speaker 1: but because fewer other galaxies remain close enough to provide
• 57:03
  Speaker 1: visible light. The universe becomes quieter one distance at a time.
• 57:09
  Speaker 1: You can imagine standing inside such a future galaxy. The
• 57:13
  Speaker 1: night sky would look very different. Many of the galaxies
• 57:17
  Speaker 1: that are visible to us today would eventually become too
• 57:20
  Speaker 1: distant to see. The familiar cosmic web would no longer
• 57:24
  Speaker 1: appear like a connected network. It would seem more like
• 57:28
  Speaker 1: scattered islands, separated by enormous darkness. And the voids would
• 57:33
  Speaker 1: have grown larger around them. This is why cosmic voids
• 57:37
  Speaker 1: are so interesting when thinking about the distant future. They
• 57:40
  Speaker 1: are already the places where matter is scarce. They are
• 57:44
  Speaker 1: already the quiet spaces between the brighter structures. And continued
• 57:49
  Speaker 1: cosmic expansion may make that difference increasingly important. The universe
• 57:54
  Speaker 1: does not necessarily become empty everywhere at once. Instead, the
• 57:59
  Speaker 1: empty regions gradually occupy more of the cosmic landscape. The
• 58:04
  Speaker 1: dense structures remain as islands for a much longer time.
• 58:08
  Speaker 1: Galaxies continue shining. Stars continue burning. But the distance between
• 58:13
  Speaker 1: the islands keeps increasing. You can let that image become
• 58:17
  Speaker 1: very slow. A faint cluster. A dark space. Another faint galaxy.
• 58:23
  Speaker 1: another dark space, and farther still, another tiny island of light.
• 58:28
  Speaker 1: There is no urgency in any of this. The universe
• 58:31
  Speaker 1: has billions and billions of years. It can change without rushing.
• 58:36
  Speaker 1: It can become larger without making a sound. And perhaps
• 58:40
  Speaker 1: that is what makes cosmic expansion feel so strange. Nothing
• 58:44
  Speaker 1: needs to move dramatically for the universe to become dramatically different.
• 58:49
  Speaker 1: Sometimes the most important change is simply that there is
• 58:52
  Speaker 1: more space between things than there used to be. You
• 58:56
  Speaker 1: drift onward. Behind you, the galaxy is now almost completely invisible. Ahead,
• 59:02
  Speaker 1: the darkness continues. Somewhere beyond your view, filaments are slowly
• 59:07
  Speaker 1: becoming more separated. Somewhere else, galaxy clusters remain bound together,
• 59:13
  Speaker 1: holding onto their stars. And between them, enormous voids continue
• 59:18
  Speaker 1: their patient growth. The universe is not rushing toward darkness.
• 59:23
  Speaker 1: It is simply expanding. And if that expansion continues for
• 59:27
  Speaker 1: an unimaginably long time, The quiet regions may occupy more
• 59:31
  Speaker 1: and more of the cosmic landscape, until the great web
• 59:34
  Speaker 1: of galaxies begins to resemble something much simpler, a scattering
• 59:39
  Speaker 1: of distant lights surrounded by almost endless space. For now, though,
• 59:44
  Speaker 1: the stars are still shining. The galaxies are still there,
• 59:48
  Speaker 1: the cosmic web is still visible, and you remain suspended
• 59:51
  Speaker 1: inside it, quietly watching a universe that is changing so
• 59:55
  Speaker 1: slowly that that its greatest transformations can only be felt
• 59:59
  Speaker 1: when you allow your imagination to travel far beyond the
• 1:00:02
  Speaker 1: length of a human life. Somewhere in that distant future,
• 1:00:06
  Speaker 1: the last bright structures may become increasingly alone, and the
• 1:00:10
  Speaker 1: question that remains is not whether the universe will become quieter,
• 1:00:15
  Speaker 1: but what the final faint lights might look like when
• 1:00:18
  Speaker 1: almost everything around them has faded into the dark. You
• 1:00:24
  Speaker 1: are drifting through a universe that has become quieter. The
• 1:00:28
  Speaker 1: great structures of galaxies are still there, but they no
• 1:00:31
  Speaker 1: longer seem as closely connected as they once did. The
• 1:00:35
  Speaker 1: spaces between them have grown. The dark regions have widened.
• 1:00:40
  Speaker 1: And when you look back, the galaxies appear less like
• 1:00:42
  Speaker 1: a great gathering and more like scattered lights, each one
• 1:00:46
  Speaker 1: surrounded by an enormous amount of space. There is no
• 1:00:50
  Speaker 1: sudden ending. Nothing breaks apart in a single moment. The
• 1:00:54
  Speaker 1: universe simply continues to expand, slowly changing the distances between things.
• 1:01:00
  Speaker 1: You can imagine returning to the cosmic web you saw earlier.
• 1:01:04
  Speaker 1: Once it appeared almost delicate, with filaments stretching between dense
• 1:01:08
  Speaker 1: knots of galaxies, broad walls surrounding enormous voids, and clusters
• 1:01:15
  Speaker 1: gathered where many structures came together. Now imagine allowing the
• 1:01:19
  Speaker 1: cosmic clock to move forward by billions of years. The
• 1:01:23
  Speaker 1: voids continue to grow. Their boundaries become larger. Neighbouring empty
• 1:01:28
  Speaker 1: regions can gradually come closer together. Where two voids once
• 1:01:32
  Speaker 1: had a filament or a wall between them, that structure
• 1:01:35
  Speaker 1: can become increasingly thin and stretched. Eventually, two neighbouring regions
• 1:01:40
  Speaker 1: of low density may become part of a larger empty region.
• 1:01:45
  Speaker 1: The distinction between them becomes less important. One quiet space
• 1:01:49
  Speaker 1: has become connected with another. The universe now contains a
• 1:01:53
  Speaker 1: larger darkness. You can drift through one of these growing regions.
• 1:01:59
  Speaker 1: There may be a galaxy far behind you. Another one
• 1:02:02
  Speaker 1: might be far ahead. But the distance between them is
• 1:02:06
  Speaker 1: becoming difficult to imagine. The cosmic web has not vanished.
• 1:02:10
  Speaker 1: It has become more delicate. The bright structures are increasingly
• 1:02:14
  Speaker 1: separated by darkness. And if you could watch this from
• 1:02:18
  Speaker 1: a great distance … The universe might begin to resemble
• 1:02:21
  Speaker 1: a collection of tiny islands floating in an expanding sea.
• 1:02:26
  Speaker 1: The islands are the gravitationally bound structures. The sea is
• 1:02:30
  Speaker 1: the enormous space between them. And that sea continues to grow.
• 1:02:35
  Speaker 1: Inside a galaxy, however, something different can happen. The stars
• 1:02:39
  Speaker 1: can remain bound to the galaxy. They continue orbiting through
• 1:02:43
  Speaker 1: the galaxy's gravitational field. A galaxy can remain a stable
• 1:02:48
  Speaker 1: home for stars. Even while the space between distant galaxies
• 1:02:52
  Speaker 1: grows enormously, the same is true for many galaxy groups
• 1:02:56
  Speaker 1: and clusters. Their internal gravity can remain strong enough to
• 1:03:00
  Speaker 1: keep them together. So the future is not necessarily a
• 1:03:04
  Speaker 1: universe in which every galaxy flies apart from every other galaxy. Instead,
• 1:03:10
  Speaker 1: it can be a universe of increasingly isolated islands. Each
• 1:03:15
  Speaker 1: island contains its own stars, its own planets. its own history.
• 1:03:20
  Speaker 1: But the space between islands becomes larger and darker. You
• 1:03:24
  Speaker 1: can imagine standing inside one of these future galaxies. The
• 1:03:28
  Speaker 1: sky above you might still contain stars. The nearest stars
• 1:03:32
  Speaker 1: would remain where they are, moving quietly through the galaxy.
• 1:03:36
  Speaker 1: But when you look beyond your own galaxy, the sky
• 1:03:39
  Speaker 1: would gradually become emptier. Some distant galaxies would become too
• 1:03:44
  Speaker 1: faint to see, Others would move beyond the region of
• 1:03:47
  Speaker 1: the universe whose light can ever reach you. This is
• 1:03:50
  Speaker 1: connected to an important idea about the observable universe. You
• 1:03:55
  Speaker 1: can only see objects whose light has had enough time
• 1:03:58
  Speaker 1: to reach you. As cosmic expansion continues, the relationship between
• 1:04:02
  Speaker 1: distance and light becomes increasingly important. Some regions of the
• 1:04:07
  Speaker 1: universe can become so distant and can recede from us
• 1:04:10
  Speaker 1: so quickly because of the expansion of space that that
• 1:04:14
  Speaker 1: their future light will never reach us. They are not
• 1:04:17
  Speaker 1: necessarily disappearing. They are simply becoming permanently separated from our
• 1:04:22
  Speaker 1: observable sky. You do not need to picture a physical
• 1:04:26
  Speaker 1: wall surrounding what you can observe. There is no cosmic
• 1:04:30
  Speaker 1: curtain being pulled across the sky. It is more like
• 1:04:33
  Speaker 1: a horizon, created by the history and expansion of space itself.
• 1:04:38
  Speaker 1: Beyond that horizon, there may still be galaxies. There may
• 1:04:42
  Speaker 1: still be stars. There may still be entire cosmic structures,
• 1:04:47
  Speaker 1: but their light may never arrive here. You can let
• 1:04:51
  Speaker 1: that thought remain very quiet. Somewhere beyond what you can
• 1:04:55
  Speaker 1: ever see, the universe may continue for an unimaginably long distance.
• 1:05:01
  Speaker 1: Yet from your future galaxy, the visible universe could gradually
• 1:05:05
  Speaker 1: contain fewer and fewer distant lights. The darkness would become
• 1:05:09
  Speaker 1: more complete. Not because darkness is taking anything away, but
• 1:05:14
  Speaker 1: because distance is increasing, and as the great voids continue
• 1:05:18
  Speaker 1: to expand, that growing distance becomes one of the most
• 1:05:22
  Speaker 1: important features of the cosmic landscape. The filaments between galaxies
• 1:05:27
  Speaker 1: can become increasingly stretched. They are not ropes that snap.
• 1:05:32
  Speaker 1: They are not solid structures. They are regions where matter
• 1:05:35
  Speaker 1: has gathered more strongly than in the surrounding space. As
• 1:05:39
  Speaker 1: expansion continues, The distances between these concentrations can grow. The
• 1:05:45
  Speaker 1: cosmic web becomes increasingly sparse. Some of its smaller structures
• 1:05:50
  Speaker 1: may disappear from practical view. Some remain as isolated clusters.
• 1:05:55
  Speaker 1: Some galaxies continue their quiet lives. And the voids between
• 1:05:59
  Speaker 1: them become enormous. You can drift through one of these
• 1:06:03
  Speaker 1: regions now. There is almost nothing to see. No bright
• 1:06:07
  Speaker 1: cluster nearby. No long chain of galaxies. only a distant
• 1:06:11
  Speaker 1: point of light, then another, and between those points, darkness.
• 1:06:17
  Speaker 1: You may begin to notice that the emptiness feels different now. Earlier,
• 1:06:21
  Speaker 1: the void seemed like a strange region inside a busy universe.
• 1:06:25
  Speaker 1: Now the emptiness is becoming a larger part of the picture.
• 1:06:29
  Speaker 1: The void is no longer simply the space between the structures.
• 1:06:33
  Speaker 1: The structures themselves are becoming small compared with the space
• 1:06:37
  Speaker 1: around them. This is one possible direction of the far future,
• 1:06:41
  Speaker 1: if cosmic expansion continues in the way current observations suggest.
• 1:06:47
  Speaker 1: The universe becomes increasingly dominated by vast regions of low density.
• 1:06:52
  Speaker 1: Galaxies and galaxy groups remain as long-lived islands of matter
• 1:06:56
  Speaker 1: and light. But they become more isolated, more distant, more alone.
• 1:07:02
  Speaker 1: You can think about the Milky Way again, the galaxy
• 1:07:05
  Speaker 1: you once called home is only one galaxy among countless others. Today,
• 1:07:11
  Speaker 1: the night sky contains a rich collection of distant galaxies,
• 1:07:15
  Speaker 1: although most are too faint to see with your eyes.
• 1:07:18
  Speaker 1: In the distant future, many of those galaxies may no
• 1:07:22
  Speaker 1: longer be visible from our local region. The universe around
• 1:07:25
  Speaker 1: you could appear much simpler, a few nearby galaxies, a
• 1:07:30
  Speaker 1: great darkness, and the faint background glow left behind from
• 1:07:34
  Speaker 1: the early universe. gradually becoming colder and more difficult to detect.
• 1:07:40
  Speaker 1: There would still be physics. There would still be gravity.
• 1:07:44
  Speaker 1: There would still be stars. There would still be matter.
• 1:07:47
  Speaker 1: The universe would not become literally nothing. It would simply
• 1:07:51
  Speaker 1: become increasingly quiet. And this is where the idea of
• 1:07:55
  Speaker 1: cosmic voids becomes more than a story about empty regions.
• 1:07:59
  Speaker 1: The voids help you imagine the direction in which the
• 1:08:02
  Speaker 1: large-scale universe may be heading. not toward an abrupt ending,
• 1:08:07
  Speaker 1: not toward a single final event, but toward increasing separation,
• 1:08:13
  Speaker 1: increasing darkness, increasing isolation, a universe where the brightest structures
• 1:08:19
  Speaker 1: are surrounded by more and more space. You continue drifting.
• 1:08:24
  Speaker 1: A distant galaxy shines softly. Its light has travelled across
• 1:08:28
  Speaker 1: an enormous stretch of space. You watch it for a moment,
• 1:08:32
  Speaker 1: then you turn away. There are fewer lights in this direction.
• 1:08:36
  Speaker 1: The darkness is wider, and somewhere far beyond your sight,
• 1:08:40
  Speaker 1: another void is growing into another void, while the ancient
• 1:08:44
  Speaker 1: cosmic web continues its slow transformation. The universe remains vast.
• 1:08:50
  Speaker 1: The universe remains beautiful. But its future may become quieter
• 1:08:55
  Speaker 1: with every passing age. And if you allow yourself to
• 1:08:58
  Speaker 1: drift even farther into that future, one gentle question begins
• 1:09:02
  Speaker 1: to appear. What happens to the last galaxies that remain,
• 1:09:07
  Speaker 1: when the great darkness has grown around them, and when
• 1:09:10
  Speaker 1: the universe has become almost entirely a collection of distant
• 1:09:14
  Speaker 1: islands beneath an enormous, quiet sky? And so, Our journey
• 1:09:21
  Speaker 1: drifts quietly to its end. You can let the great
• 1:09:24
  Speaker 1: darkness become softer now. There is nothing more you need
• 1:09:27
  Speaker 1: to follow, nothing you need to remember, nothing you need
• 1:09:31
  Speaker 1: to understand. You have travelled far beyond the familiar night sky,
• 1:09:36
  Speaker 1: past the earth, beyond the quiet neighbourhood of the Milky Way,
• 1:09:40
  Speaker 1: through the local group, toward the enormous spaces between galaxies
• 1:09:45
  Speaker 1: and into the vast emptiness of cosmic voids. You have
• 1:09:49
  Speaker 1: seen how the universe is not simply filled with galaxies.
• 1:09:53
  Speaker 1: You have seen the spaces between them, the great quiet
• 1:09:56
  Speaker 1: regions where matter is sparse, where galaxies become rare, where
• 1:10:01
  Speaker 1: darkness can stretch across distances so enormous that ordinary words
• 1:10:06
  Speaker 1: begin to feel very small. And perhaps now, the emptiness
• 1:10:10
  Speaker 1: feels a little different. It may no longer seem like nothing.
• 1:10:15
  Speaker 1: It can simply be space, vast and patient, surrounding the
• 1:10:19
  Speaker 1: galaxies that remain. You can imagine the cosmic web one
• 1:10:23
  Speaker 1: last time, faint filaments, distant clusters, tiny islands of stars,
• 1:10:30
  Speaker 1: and between them, enormous regions of darkness, slowly expanding as
• 1:10:36
  Speaker 1: the universe continues its quiet journey. The voids do not rush,
• 1:10:41
  Speaker 1: they do not announce themselves, they simply become larger, little
• 1:10:45
  Speaker 1: by little, across timescales far beyond a human lifetime. And
• 1:10:50
  Speaker 1: somewhere inside one of those quiet regions, a small galaxy
• 1:10:54
  Speaker 1: may still be shining. Its stars are still moving. Its
• 1:10:58
  Speaker 1: gas is still drifting. A few new stars may still
• 1:11:02
  Speaker 1: be forming. Perhaps its sky contains only a handful of
• 1:11:05
  Speaker 1: distant galaxies. Perhaps, far in the future, even those lights
• 1:11:10
  Speaker 1: will become harder to see. But for now, somewhere in
• 1:11:14
  Speaker 1: the immense universe... Light continues to travel. A tiny beam
• 1:11:19
  Speaker 1: leaves a distant star. It crosses the darkness. It continues onward.
• 1:11:24
  Speaker 1: And eventually, perhaps, it reaches another world. You can let
• 1:11:28
  Speaker 1: yourself become still with that image. A single small light
• 1:11:32
  Speaker 1: moving through an almost endless space. No urgency. No destination
• 1:11:38
  Speaker 1: you need to reach. Just light travelling quietly through the dark.
• 1:11:42
  Speaker 1: The universe will continue expanding. The galaxies will continue moving.
• 1:11:48
  Speaker 1: Stars will continue to shine for as long as their
• 1:11:50
  Speaker 1: lives allow. And the great voids will continue to grow
• 1:11:54
  Speaker 1: around them, slowly reshaping the cosmic landscape. You do not
• 1:11:58
  Speaker 1: need to stay awake to watch it happen. There is
• 1:12:01
  Speaker 1: nothing you need to do. You are safe. You can rest.
• 1:12:05
  Speaker 1: The universe is large enough to continue without you watching it.
• 1:12:09
  Speaker 1: The stars can keep shining. The galaxies can keep turning.
• 1:12:13
  Speaker 1: The great empty spaces can keep widening. And while all
• 1:12:17
  Speaker 1: of that continues far beyond you, here, in this quiet moment,
• 1:12:22
  Speaker 1: you can simply breathe. Slowly. Gently. Allow your body to
• 1:12:27
  Speaker 1: become heavier. Allow the room around you to become quieter.
• 1:12:31
  Speaker 1: Let the distant galaxies fade from your imagination if they
• 1:12:34
  Speaker 1: wish to. Let the stars become softer. Let the darkness
• 1:12:39
  Speaker 1: become comfortable. Perhaps the scariest place in the universe was
• 1:12:43
  Speaker 1: never frightening because there was something there. Perhaps it was
• 1:12:47
  Speaker 1: frightening because there was almost nothing there at all. And yet,
• 1:12:52
  Speaker 1: even within that emptiness, you found traces of structure, a
• 1:12:56
  Speaker 1: faint galaxy, a distant star, a little gas, invisible matter,
• 1:13:02
  Speaker 1: a slow gravitational pull, tiny pieces of a universe that
• 1:13:06
  Speaker 1: remains connected even across unimaginable distances. so you can let
• 1:13:11
  Speaker 1: the final image remain very simple. A dark sky, a
• 1:13:16
  Speaker 1: few distant lights, an enormous quiet space between them, and you,
• 1:13:22
  Speaker 1: resting safely beneath it all. Whether you're still listening beneath
• 1:13:26
  Speaker 1: the glow of your screen, or already floating somewhere between
• 1:13:29
  Speaker 1: dreams and distant stars, thank you for travelling here tonight,
• 1:13:34
  Speaker 1: through silent galaxies, ancient particles, enormous voids, and the quiet
• 1:13:40
  Speaker 1: laws that hold the universe together. If this wandering brought
• 1:13:44
  Speaker 1: you a little calm, you're welcome to subscribe or share
• 1:13:47
  Speaker 1: it with someone who could use a gentler night beneath
• 1:13:50
  Speaker 1: the cosmos. For now, rest well. The stars will keep burning,
• 1:13:56
  Speaker 1: the planets will keep turning, the galaxies will keep drifting,
• 1:14:01
  Speaker 1: the voids will keep expanding, and the universe will carry
• 1:14:05
  Speaker 1: on softly around you while you sleep.