Dichronauts

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Greg Egan: Dichronauts (2017, Night Shade Books)

Hardcover, 320 pages

English language

Published Aug. 28, 2017 by Night Shade Books.

ISBN:
978-1-59780-892-7
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4 stars (1 review)

Seth is a surveyor, along with his friend Theo, a leech-like creature running through his skull who tells Seth what lies to his left and right. Theo, in turn, relies on Seth for mobility, and for ordinary vision looking forwards and backwards. Like everyone else in their world, they are symbionts, depending on each other to survive.

In the universe containing Seth's world, light cannot travel in all directions: there is a “dark cone” to the north and south. Seth can only face to the east (or the west, if he tips his head backwards). If he starts to turn to the north or south, his body stretches out across the landscape, and to rotate as far as north-north-east is every bit as impossible as accelerating to the speed of light.

Every living thing in Seth’s world is in a state of perpetual migration as they follow the sun’s shifting …

1 edition

reviewed Dichronauts by Greg Egan

Adventures in a strange, geomeric world

4 stars

Another interesting Hard SF read by Egan. It's not as mind-bending or physics-bending as his "Orthogonal" series but contains intriguing ideas and characters. In contrast to his previous books where the characters slowly learn (and educate the reader about) the physics of their environment, here they are already well versed in the strange (to us) geometry of their universe and its consequences.

In this book, Egan posits a world that has two space dimensions and two time-like dimensions. The resulting geometry is a hyperboloid world orbited by a sun that is slowly wandering south. The inhabitants of various cities are thus forced to migrate to remain in the habitable zone of their world.

The story starts with two characters, a 'walker' named Seth, who can only face eastwards or westwards, and his parasitic companion Theo, who lives in his head and apparently uses echo location to see what is north …