Dichronauts - Orreadi

No cover — 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

(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 …

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 orbit and the narrow habitable zone it creates. Cities are being constantly disassembled at one edge and rebuilt at the other, with surveyors mapping safe routes ahead.

But when Seth and Theo join an expedition to the edge of the habitable zone, they discover a terrifying threat: a fissure in the surface of the world, so deep and wide that no one can perceive its limits. As the habitable zone continues to move, the migration will soon be blocked by this unbridgeable void, and the expedition has only one option to save its city from annihilation: descend into the unknown.

4 editions

Soh Kam Yung 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 …

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 or south. In the course of the story, they become surveyors who survey the landscape that their city would migrate to.

On a particularly long survey journey, they encounter a city which, to them, has committed a species wide crime. But that is small compared to what they ultimately encounter; the apparent edge of their world, whose depths they would have to survey to discover whether it can be bypassed when their city eventually encounters the edge.

In this adventure into the depths, their knowledge of the geometry of their world would be tested as they encounter strange new lifeforms and then perform some personal sacrifices to be able to return to their city with knowledge that will be vital to their survival.

As usual, Greg Egan provides a supplementary website that explains the geometry of the world [ www.gregegan.net/DICHRONAUTS/DICHRONAUTS.html ]. While not strictly necessary, I found it to be very helpful in understanding the challenges the characters have in living in this kind of universe and how things work.

Yet another interesting book by Egan for those who are more interested in strange world-building.