A topopolis is a proposed tube-shaped
space habitat
A space settlement (also called a space habitat, spacestead, space city or space colony) is a Human settlement, settlement in outer space, sustaining more extensively Space habitat (facility), habitation facilities in space than a general space ...
, rotating to produce
artificial gravity
Artificial gravity is the creation of an inertial force that mimics the effects of a gravitational force, usually by rotation.
Artificial gravity, or rotational gravity, is thus the appearance of a centrifugal force in a rotating frame of ...
via
centrifugal force
Centrifugal force is a fictitious force in Newtonian mechanics (also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It appears to be directed radially away from the axi ...
on the inner surface, which is extended into a loop around the local planet or star. The concept was invented by writer
Patrick Gunkel.
Varieties of topopolises and similar fictional structures
A topopolis has been compared to an
O'Neill cylinder, or a
McKendree cylinder, that has been extended in length so that it encircles a
star
A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...
. A "normal" topopolis would be hundreds of millions of miles/kilometers long and at least several miles (kilometers) in diameter.
Topopoles can be looped several times around the local star, in a geometric figure known as a
torus knot
In knot theory, a torus knot is a special kind of knot (mathematics), knot that lies on the surface of an unknotted torus in R3. Similarly, a torus link is a link (knot theory), link which lies on the surface of a torus in the same way. Each t ...
. Topopolises are also called cosmic spaghetti.
A topopolis with big enough
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...
could theoretically have multiple levels of concentric cylinders.
Larry Niven
Laurence van Cott Niven (; born April 30, 1938) is an American science fiction writer. His 1970 novel ''Ringworld'' won the Hugo Award for Best Novel, Hugo, Locus Award, Locus, Ditmar Award, Ditmar, and Nebula Award for Best Novel, Nebula award ...
(1974) mentioned the idea in a much-reprinted magazine article "
Bigger Than Worlds".
[
]
::reprinted that same year in
::reprinted 17 years later in
Paul Birch referred to this design as the "macaroni habitat". He suggested that, aside from looping around a star, it could instead extend between one star and another, resulting in a habitable area about 100 million times that of the Earth.
Examples in fiction
In the novel ''
Matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic pa ...
'',
Iain M. Banks (2008)
depicts a topopolis that loops its system star many times in various braidings, and houses trillions of sapient residents. The topopolis was so massive that stray gases from the system collected within the major spacing within the braids by gravitation alone, producing a slight atmosphere between the strands, that the author describes as a "haze".
Dennis E. Taylor (2020)
in the book ''Heaven’s River'' features an alien civilization inhabiting a topopolis.
The setting of the worldbuilding project
Orion's Arm
Orion's Arm (also called the Orion's Arm Universe Project, OAUP, or simply OA) is a multi-authored online hard science fiction world-building project, first established in 2000 by M. Alan Kazlev, Donna Malcolm Hirsekorn, Bernd Helfert and And ...
has topopoli among the various kinds of megastructures.
The system of Cableville is notable for having three topopoli of different sizes and orbits, with names referencing long objects: the innermost is
Spaghetti
Spaghetti () is a long, thin, solid, cylindrical pasta.[spaghetti](_blank)
Dictionary.com. Dictionary.com Una ...
, the one outside it is
Ouroboros
The ouroboros or uroboros (; ) is an ancient symbol depicting a serpent symbolism, snake or European dragon, dragon Autocannibalism, eating its own tail. The ouroboros entered Western tradition via Egyptian mythology, ancient Egyptian iconogra ...
, and the outermost is
Wyrme.
See also
*
Big dumb object
In discussion of science fiction, a Big Dumb Object (BDO) is any mysterious object, usually of extraterrestrial or unknown origin and immense power, in a story which generates an intense sense of wonder by its mere existence. To a certain extent, ...
*
Ringworld
''Ringworld'' is a 1970 science fiction novel by Larry Niven, set in his Known Space universe and considered a classic of science fiction literature. ''Ringworld'' tells the story of Louis Wu and his companions on a mission to the Ringworld, an ...
References
{{Science fiction
Megastructures
Fictional space stations