This is then about the largest black hole that could be used for a simple 1g suprahole planet.

- Paul Birch

The Virgo Birch Planet is light year-sized artificial planet with a hypermassive black hole at its core. The planet was constructed by the Kardeshev III Builder Civilisation from all the mass of their home Pristini Galaxy. The planet is currently inhabited by many races but is dominanted by the descendants of the Builders, the Virgonian Civilisation.

In principle, a Birch planet is an artificial world where the surface gravity is provided by a galactic-mass black hole at the planet's core. The livable area on the surface exists as many shell-worlds of material that are held apart from falling into the black hole by active support.

The Virgo Birch Planet is one of the largest and mysterious single objects in the vicinity of the whole First Gigaquadrant. Because of its huge mass and surface area, the planet can be classified as a galaxy, although not in the conventional, natural sense.

Astrography Edit

Location Edit

The Virgo Birch Planet exists in the former location of the Pristini Galaxy, 5 million light years from its nearest neighbor, Cyrannus. This places the planet just outside the galactopolitical region known as the First Gigaquadrant as it does not fall inside any of the galaxy groups considered to be part of that entity.

The planet sits alone is space, not orbiting any other body. However, many smaller bodies orbit it in a geocentric pseudo-star system. These bodies include rouge planets, stars, and even multiple Dyson Spheres. Over time, the planet has also accumulated a halo of new dark matter.

Observability Edit

Birch Planet Icon - Redshift

The Virgo Birch Planet as it appears without accounting for the gravitational redshift of the black hole.

As the planet does not orbit any star, it gives of very little light. This, coupled with the fact that the physical size of the planet is actually very small on an intergalactic scale, makes the planet virtually impossible to see directly. Additionally, the relativisti effects of the black hole mean that any light emitted from the surface has its frequency reduced to only 53% from the perspective of a distant observer, decreasing the amount of visible light. This explains why the planet went undiscovered by modern 29th century civilisation until relatively recently.

Detection of the planet is possible through observation of its indirect gravitational effects on nearby dwarf galaxies such as the PGC 170257 and PGC 45628 irregular galaxies. In the past, the flurry of gravitational waves emitted from the thousands of black hole-merger events that occurred in the planets construction would have also been detectable from the Gigaquadrant galaxies and may have been recorded by ancient civilisations. Also, the visible disappearance of the Pristini Galaxy over this period of constructed would have been directly observable.

Architecture Edit

Birch Planet Diagram

The hypermassive black hole at the core of the planet, Azathoth-3S, occupies 36% of the planet's internal volume. An empty space known as the void mantle occupies most of the remaining volume and is very sparsely filled with structure. The outer 253 AU of the sphere comprises the crust, a series of 280 million shellworld layers each an average of 100 km apart. This gives the birch planet a total surface area of approximatley 180 decilion square meters.

The immediate neighbourhood of the surface is also filled with a lot of less dense structure that hovers up to billions of km above the surface of the planet, extending in the wider planetary system.

Time Dilation Edit

Birch Planet Time Dilation

A graphical representation of the time acceleration factor as the event horizon (black line) is approached. The green line represents the distance of the crust.

Due to the general relativistic effects of the black hole, time on the crust runs an average of 53% slower than in the rest of the universe. This means that one year passing on the planet is equivalent to about 22.5 months passing in the outside universe. The difference in time dilation between layers is only 0.8%, meaning the upper most layer gains an additional 3 days per year compared to the bottom most.

Closer to the black hole, time dilation will increase. This allows for ships flying through the void mantle to return to the surface centuries after they first left, but only hours later from their own perspective. This measurement doesn't account for the special relativistic time dilation that would come from the extreme velocity an approach to the black hole this close would generate.

Temporal Acceleration Factor Distance from Event Horizon (AU) 1 Hour Equivelant
10x 300 10 hours
50x 12 2 days
100x 3 4 days
1000x 0.03 6 weeks
10,000x 0.0003 13.7 months
100,000x 0.000003 (450 km) 11.4 years
1 Million x 0.00000003 (4.5 km) 114 years

Geography Edit

Desert atlas pillar

An alien desert biome with religious iconography constructed around the supporting Atlas pillars by an unknown civilisation.

Due to its vast surface area, every imaginable biome/terrain is represented on one of the surfaces of the planet. Whole regions with surface area comparable to a natural planet that have common composition and features are called "scapes", and can often be treated for all intents and purposes like a planet. some scapes are walled off from each other by barriers dozens of kilometers high called Svadilfari Walls, while others have no clear border except for a gradual change in terrain between them, allowing much easier exchange of material between them. These walls, or their transparent equivalent referred to as Firmaments, are also used to separate regions of the planet with incompatible conditions such as very different atmospheric compositions, pressures, or different water levels. The horizon of the planet is never visible because the huge size leads to almost imperceptible curvature, and because the opaqueness of most atmospheres over the distance that would be needed to view such a curvature leads to distant objects disappearing into a fog long before they would drop below the horizon.

it is unknown how much of the planets surfaces may have been designed deliberately by the Builders, and what percentage was generated procedurally.

Extreme Environments Edit

Some regions mimic the conditions of more extreme types of planets by having the high atmospheric pressure of gas giants, or the abyssal depths of water worlds. Often, scapes such as these will span multiple standard layers, attaining vertical distances of more than 100 km. There are also vast urban and industrialized regions of the planet. Here, the layers are usually much closer together with only 10 or even 1 km of separation between. Some of these regions were constructed when the planet was first built, but other have arisen due to the construction of the planet's own endogenous civilisations.

Carollian Environments Edit

Some regions of the planet have environmental conditions that don't occur naturally in the universe and may seem absurd. These include examples like regions where the rocks are made of chocolate, or regions where it rains flower petals and the wind smells of roses. Some of these environments also have very extreme conditions like the ground being one continuous mass of living flesh, or there being a continuous hail of rocks under an atmosphere of huge pressure. The unpredictability of these environments means they must be studied extensively to eliminate risk before entering.

Life Edit

Many decillions of species live on the surface of the Virgo Birch Planet at various stages of biological and technological development. Life has independently arisen octillions of times in different places on the surface and evolved and diversified into connected or isolated ecologies. One way of drawing the boundaries between connected scapes that two areas are considered different scapes if they have a different life origin. This has lead to a variety of biochemistries, adaptations, and philosophies across the many surfaces of this titanic world.

The Virgonian Civilisation Edit


The Virgonians are the most powerful civilisation on the planet and could be considered its "owners". The civilizations is an amalgam of the original Builder Civilisation as well as civilisations that have arisen on the planet and become powerful enough to join them.

The Virgonians exist mostly as vast minds that dwarf the Elder AIs of the Technoosphere. They are supported on the Cerebrum but can shift components of themselves to other computers on the planet such as orbital Matrioska Brains. Virgonians can also manifest via avatar bodies to walk among their creations and appreciate the planet's natural and artificial beauty.

Mountain Avatar

A Virgonian Avatar emerges from a wormhole in a mountainous biome on the planet's surface to roam the landscape.

Biological Life Edit

The most common type of life is purely biological, naturally evolving flora, fauna, and cells. These civilizations may develop technology can even fully explore their own and adjacent scapes. They aren't usually aware of the true nature of the object they live on unless explicitly told by another civilization, or if the Virgonians have some purpose for them other than to naturally develop. Notable is the fact that almost every civilization will not be aware of the existence of the rest of the universe as they are unable to see outer space.

Many K1 civilizations have arisen over time on the planet. They completely control a scape and will usually be aware that the planet is artificial but possibly not who built it or be aware of its true extent

K2 civilizations also arise and have full control over a large number of scapes or their whole megastructural satellite. When very advanced, the Virgonian Civilisation may make their presence known to them

Notable Examples Edit

  • Add your fiction here

Simulated Life Edit

There are many, many simulated species as well that may or may not have a real-world analogue. These simulations are typically run in orbital or crust-embedded Matrioska brains or may be run on the cerebrum as a component of a greater Virgonian entity. A hierarchical system exists were a Virgonian mind may have many Seraphim components, which may have Cherubium components and so on, all the way down to average simulated people.

AI Seraphim Edit

The AI Seraphim is the name given to the various K2 single minds that totally occupy the computer space of a number of Matrioska brains. They are analogous to the Elder AIs of the Technoosphere.

AI Cherubium Edit

Cherubium are smaller AIs that still vastly dwarf a person in terms of computational power. They run on smaller computers such as J-brains or a smaller section of a Matrioska brain.

Technology Edit

The technology of the Virgo Birch planet is vast and powerful. As a Kardeshev III+ object, the planet can freely manipulate, create, and destroy stellar objects and manipulate spacetime into unusual geometries. The planet is fully Azothic, meaning it can freely convert between different types of matter though technologies like large-scale quantitative fusion, matter enlightenment, leptogenesis and strange matter conversion.

The planet also boasts proficent time travel technology, allowing various computers to send information to each other across both space and time. The planet also has significant control over its structure in local hyperspace. Together these mean the planet can be loosely considered a 5 dimensional object, at least in terms of ability if not structure.

Much Birch technology operates using principles that are incomprehensible to lower lifeforms and even Technoospheric Gods. Such technology is called Clarktech and includes such things as teleportation, hard light, and Essence use.

History Edit

Construction Edit

The Builder Civilisation began construction of the Birch Planet between 1.5 and 1.2 billion years ago in the now totally converted Pristini Galaxy. This involved feeding the central supermassive black hole of the galaxy, K37 Gem 9, the vast majority of the matter making up the galaxy so that it would be of appropriate mass to act as the core of the vast planet. The hypermassive Azathoth-3S black hole that would go on to become the core of the planet was formed as a result. This was accomplished through the movement of all 800 billion stars in the galaxy towards the center by renovation of the billions Dyson spheres that already comprised the Builder's empire into Shkadov thrusters. To avoid crowding of the central galactic area with too many stars, many were merged into smaller intermediate-mass black holes to compact many dozens of solar masses into a smaller volume. These were the actual objects fed into K37 Gem 9. By some unknown means, the diffuse gas and dark matter that made up a significant portion of the galaxy's mass was also fed into the black hole. This process occurred first as many Dyson spheres had vital functions to the empire that needed to be maintained as long as possible. This period changed the face of the Pristini Galaxy forever and is known as the Great Contraction.

This subluminal, brute-force approach was chosen by the Builders rather than the large scale superluminal transport of matter through structures such as wormholes. The actual time it would take to contract the whole galaxy was a largely unimportant factor to consider due to the Builder's extreme automation technology and due to the fact that virtually all Builder citizens lived as digital beings in simulated realities on the vast technoospheric network of matryoshka brains that extended across Pristini. These simulation could slimply be run at a slower speed so that the speed of the exterior real universe accelerated by comparison.


The first 100,000-layer sections being moved into position

The shell of the planet was build by large spacebourne robots in large terastructural sections which were then lowered down and put into place by robots closer to the black hole. This was done because all the shellworlds at a lower altitude than the black hole's photon sphere, and thus ships would require a more energy-expensive superluminal propulsion systems to remain in orbit. The matter used to construct the shell itself came only comprises a miniscule amount of what used in the construction of Azathoth-3S. Thus, most of it came from just the residual Dyson spheres that weren't vital to the black hole. Stellar plasma and diffuse interstellar hydrogen could be made into the heavier elements needed by very large-scale industrial fusion. The process of Matter Enlightenment was also used to convert dark matter into standard elements.

It is not known why the Builders decided to construct the Virgo Birch Planet as there are many other K3 megastructures that would provide vastly more surface area to live on, or power generation. The answer to this ancient civilisation's motives puzzles xenoanthropologists and philosophers to this day.

Quotes Edit

I am not a religious man. But when I happened to gaze upon this gargantuan specimen of a world, I could not help but feel deeply humbled by the experience. Here stood something so magnificent that not even the most wicked of minds could possibly concieve it. This undertaking, so grand and vast, looked to me as nothing less but the work of technological gods.

- Exerpt from the jounral of Oji'b, explorer of the Waptoria Alliance of Species

Music 🎶 Edit

To set the mood for the various regions of the planet

Trivia Edit

  • The Birch Planet was originally described by Paul Birch in his 1991 paper, Supramundane Planets. The term "Birch Planet" was coined in his honor by Isaac Arthur.
    • However, as far as I can tell, in the original paper the "surface gravity" parameter of black holes was misunderstood to be analogous to the surface gravity of a Newtonian body. Thus, the layer where gravity was 1g was placed on the event horizon, unlike in the Virgo Birch Planet.
  • With it's current parameters the Virgo Birch Planet has approximately 11.8x as much surface area as every naturally occurring planet in the observable universe combined.
  • The distance between the lowest stable orbit at the Photon Sphere and the surface of the planet is ≈3,000 AU. This distance would take over 2.5 weeks to traverse without superluminal travel.
  • The crust is 253 AU thick, meaning there is room for over 250 decently sized Dyson Spheres to be stacked end-to-end spanning it
  • The Void Mantle is easily large enough to house whole star systems inside the planet, if any orbits at that depth were stable.

Navigation Edit

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