Editing The Culture (section)

==Living space==
Much of the Culture's population lives on orbitals, vast artificial worlds that can accommodate billions of people. Others travel the galaxy in huge space ships such as General Systems Vehicles (GSVs) that can accommodate hundreds of millions of people. Almost no Culture citizens are described as living on planets, except when visiting other civilisations. The reason for this is partly because the Culture believes in containing its own expansion to self-constructed habitats, instead of colonising or conquering new planets. With the resources of the universe allowing permanent expansion (at least assuming non-exponential growth), this frees them from having to compete for living space.

The Culture, and other civilisations in Banks' universe, are described as living in these various, often constructed habitats:

===Airspheres===
These are vast, [[brown dwarf|brown dwarf-sized]] bubbles of atmosphere enclosed by force fields, and (presumably) set up by an ancient advanced race at least one and a half billion years ago (see: [[Look to Windward]]). There is only minimal gravity within an airsphere. They are illuminated by moon-sized orbiting planetoids that emit enormous light beams.

Citizens of the Culture live there only very occasionally as guests, usually to study the complex ecosystem of the airspheres and the dominant life-forms: the "dirigible behemothaurs" and "gigalithine lenticular entities", which may be described as inscrutable, ancient intelligences looking similar to a cross between gigantic blimps and whales. The airspheres slowly migrate around the galaxy, taking anywhere from 50 to 100 million years to complete one circuit. In the novels no one knows who created the airspheres or why, but it is presumed that whoever did has long since sublimed but may maintain some obscure link with the behemothaurs and lenticular entities. Guests in the airspheres are not allowed to use any force-field technology, though no reason has been offered for this prohibition.

The airspheres resemble in some respects the orbit-sized ring of breathable atmosphere created by [[Larry Niven]] in ''[[The Integral Trees]]'', but spherical not [[toroid]]al, require a force field to retain their integrity, and arose by artificial rather than natural processes.

===Orbitals===
One of the main types of habitats of the Culture, an orbital is a ring structure orbiting a star as would a [[megastructure]] akin to a bigger [[Bishop Ring (habitat)|Bishop ring]]. Unlike a [[ringworld]] or a Dyson sphere, an orbital does not enclose the star (being much too small). Like a ringworld, the orbital rotates to provide an analog of gravity on the inner surface. A Culture orbital rotates about once every 24 hours and has gravity-like effect about the same as the gravity of Earth, making the diameter of the ring about {{Convert|3700000|km}} (nearly five times the diameter of the Moon's orbit around Earth), and ensuring that the inhabitants experience night and day. Orbitals feature prominently in many Culture stories.

===Planets===
Though many other civilisations in the Culture books live on planets, the Culture as currently developed has little direct connection to on-planet existence. Banks has written{{citation needed|date=April 2019}} that he presumes this to be an inherent consequence of space colonisation, and a foundation of the liberal nature of the Culture. A small number of home worlds of the founding member-species of the Culture receive a mention in passing, and a few hundred human-habitable worlds were colonised (some of them [[Terraforming|terraformed]]) before the Culture elected to turn towards artificial habitats, preferring to keep the planets it encounters wild. Since then, the Culture has come to look down on terraforming as inelegant, ecologically problematic and possibly even immoral. Less than one per cent of the population of the Culture lives on planets, and many find the very concept somewhat bizarre.

This attitude is not absolute though; in ''Consider Phlebas'', some Minds suggest testing a new technology on a "spare planet" (knowing that it could be destroyed in an antimatter explosion if unsuccessful). One could assume – from Minds' usual ethics – that such a planet would have been lifeless to start with. It is also quite possible, even probable, that the suggestion was not made in complete seriousness.

===Rings===
[[Ringworld]]-like megastructures exist in the Culture universe; the texts refer to them simply as "Rings" (with a capital ''R''). As opposed to the smaller orbitals which revolve around a star, these structures are massive and completely encircle a star. Banks does not describe these habitats in detail, but records one as having been destroyed (along with three Spheres) in the Idiran-Culture war. In ''Matter'', the Morthanveld people possesses ringworld-like structures made of innumerable various-sized tubes. Those structures, like [[Larry Niven| Niven]]'s Ringworld, encircle a star and are about the same size.

===Rocks===
These are asteroids and other non-planetary bodies hollowed out for habitation and usually spun for centrifugal artificial gravity. Rocks (with the exception of those used for secretive purposes) are described as having faster-than-light space drives, and thus can be considered a special form of spaceship. Like Orbitals, they are usually administered by one or more Minds.

Rocks do not play a large part in most of the Culture stories, though their use as storage for mothballed military ships (''Pittance'') and habitats (''Phage Rock'', one of the founding communities of the Culture) are both key plot points in ''Excession''.

===Shellworlds===
Shellworlds are introduced in ''Matter'', and consist of multilayered levels of concentric spheres in four dimensions held up by countless titanic interior towers. Their extra dimensional characteristics render some products of Culture technology too dangerous to use and yet others ineffective, notably access to hyperspace. About 4000 were built millions of years ago as vast machines intended to cast a forcefield around the whole of the galaxy for unknown purposes; less than half of those remain at the time of ''Matter'', many having been destroyed by a departed species known as the Iln. The species that developed this technology, known as the Veil or the Involucra, are now lost, and many of the remaining shellworlds have become inhabited, often by many different species throughout their varying levels. Many still hold deadly secret defence mechanisms, often leading to great danger for their new inhabitants, giving them one of their other nicknames: Slaughter Worlds.

===Ships===
Ships in the Culture are intelligent individuals, often of very large size, controlled by one or more Minds. The ship is considered by the Culture generally and the Mind itself to be the Mind's body (compare avatars). Some ships (GSVs, for example) are tens or even hundreds of kilometres in length and may have millions or even billions of residents who live on them full-time; together with Orbitals, such ships represent the main form of habitat for the Culture. Such large ships may temporarily contain smaller ships with their own populations, and/or manufacture such ships themselves.

In ''Use of Weapons'', the protagonist Zakalwe is allowed to acclimatise himself to the Culture by wandering for days through the habitable levels of a ship (the GSV ''Size Isn't Everything'', which is described as over {{Convert|80|km}} long), eating and sleeping at the many locations which provide food and accommodation throughout the structure and enjoying the various forms of contact possible with the friendly and accommodating inhabitants.

===Spheres===
[[Dyson sphere]]s also exist in the Culture universe but receive only passing mention as "Spheres". Three spheres are recorded as having been destroyed in the Idiran-Culture war.{{sfn|Banks|1987}}