''Orthogonal'' is a

science fiction Science fiction (often shortened to sci-fi or abbreviated SF) is a genre of speculative fiction that deals with imaginative and futuristic concepts. These concepts may include information technology and robotics, biological manipulations, space ...

trilogy by

Australian Australian(s) may refer to: Australia * Australia, a country * Australians, citizens of the Commonwealth of Australia ** European Australians ** Anglo-Celtic Australians, Australians descended principally from British colonists ** Aboriginal Aus ...

author

Greg Egan Greg Egan (born 20 August 1961) is an Australian science fiction writer and mathematician, best known for his works of hard science fiction. Egan has won multiple awards including the John W. Campbell Memorial Award, the Hugo Award, and the Lo ...

taking place in a universe where, rather than three dimensions of space and one of time, there are four fundamentally identical dimensions. While the characters in the novels always perceive three of the dimensions as space and one as time, this classification depends entirely on their state of motion, and the dimension that one observer considers to be time can be seen as a purely spatial dimension by another observer. The plot involves the inhabitants of a planet that comes under threat from a barrage of high-velocity meteors known as 'hurtlers', who launch a

generation ship A generation ship, generation starship or world ship, is a hypothetical type of interstellar ark starship that travels at sub- light speed. Since such a ship might require hundreds to thousands of years to reach nearby stars, the original occup ...

that exploits the distinctive relativistic effects present in this universe which allow far more time to elapse on the ship than passes on the home world, in order for the ship's inhabitants to have enough time to develop the technology needed to protect the planet. The three novels deal with a succession of increasingly advanced scientific discoveries, as well as a number of radical social changes in the culture of the generation ship's passengers. Technically, the space-time of the universe portrayed in the novels has a positive-definite

Riemannian metric In differential geometry, a Riemannian manifold is a geometric space on which many geometric notions such as distance, angles, length, volume, and curvature are defined. Euclidean space, the N-sphere, n-sphere, hyperbolic space, and smooth surf ...

, rather than a

pseudo-Riemannian In mathematical physics, a pseudo-Riemannian manifold, also called a semi-Riemannian manifold, is a differentiable manifold with a metric tensor that is everywhere nondegenerate. This is a generalization of a Riemannian manifold in which the r ...

metric, which is the kind that describes our own universe. The ''Orthogonal'' trilogy consists of the novels ''

The Clockwork Rocket The Clockwork Rocket is a hard science-fiction novel by Australian author Greg Egan and the first part of the Orthogonal trilogy. The novel was published by Night Shade Books on 1 July 2011 with a cover art by Cody Tilson and by Gollancz on 15 ...

(''published in 2011), '' The Eternal Flame'' (published in 2012)' and ''

The Arrows of Time ''The Arrows of Time'' is a hard science-fiction novel by Australian author Greg Egan and the third part of the ''Orthogonal'' trilogy. The novel was published by Gollancz on 21 November 2013 with a cover art by Greg Egan and by Night Shade B ...

'' (published in 2013).

Footnotes

External links

Official website
2011 Australian novels Novels by Greg Egan Australian science fiction novels 2010s science fiction novels Fiction about physics Fictional dimensions Night Shade Books books {{2010s-sf-novel-stub