Dichronauts

By: Greg Egan

Narrated by: Paul Boehmer

Length: 10 hrs and 49 mins

Publisher's summary

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.

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-northeast is impossible.

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.

©2017 Greg Egan (P)2017 Tantor

It's not an easy book

I loved this book, but if you are not a fan of hard sci-fi, consider whether to go for it. The world is very interesting and it's fascinating how the author could picture life in a completely different space-time, but it takes effort to understand (of course). If you are not afraid to test your imagination however, then enjoy.

A compelling tale with non-optional math

So good. A world with two dimensions of space and two dimensions of time, where all arcs are parabolas so all spheres are parabolic. The edges of the sun scorch the earth, and being directly below the sun is a cone of darkness. The physics of the world are enthralling, and dictate the evolution, culture, and geology of an alien universe where the world is slowly and literally tipping out of balance.

Unsatisfying

Generally I find Greg Egan's hard Sci-Fi thought provoking and enlightening, even without knowing all the math behind the universes his stories paint they still stand up as great stories, and there's enough description to paint a picture of the world and it's usually unusual physics in vivid Technicolor, this book was a departure from the norm, the universe the book is predicated on is lacking any explanation within the book and even after studying the physics on his website it was still as clear as mud for a while. While the story thread itself seems to be well put together to a point as an exploration of the universe it inhabits the conclusion is lacking, with little to tie off the dangling plot threads the reader or listener is left to imagine a happily ever after a fairy tale ending to a not very fairy tale plot so far.

Spoilers ahead

Geometry, the book is predicated on a novel geometry with a universe based on 2 time dimensions (hence dichrone from the books title) and 2 space ones but one of the time dimensions isn't explained to be as such and is treated like a space dimension where turning into it is impossible and skews your perspective. The physics does seem to hold as true but there's no exploration of the 2nd time dimension as anything but a novel spacial one. And since it's not explained at all in the text at some point you will go looking on the web for the explanation on Greg's website for why the universe acts the way it does.

Plot, the book's plot is well crafted as an exploration of the world of the protagonist, a shifting axis in effect causing the creatures in the book to migrate with the seasons being the setup for the society and our intrepid dichronauts being some of the people who map the world in advance of the migration. The protagonists are a dual symbiotic entity that rely on one another in a way to provide the vision in their blind dimension(s) but they lack for a good long while a full description that allows you to picture them in the mind's eye. They become surveyors and map the world for the migration and one is clearly a genius because from first principles he figures out, A hot air balloons, B the way the sun orbits the world and the way the world rotates to explain the migration (though without enough detail to let the reader grasp that without the website foot notes) C the edge of the world hypothesis, D more, mostly from first principles. There's moral and personal dilemmas and after getting some real answers about the world and just as the whole thing seemed ready to get resolved the book ends with no conclusion. No epilogue, it just ends. Almost right as the action seems set to start again but with no resolution to the lost companions on the way, no resolution to the thread of what would be done about the migration with the information available. No real resolution of the moral dilemma. The ending being implied to be and everyone lives happily ever after, the people who got lost on the journey made it home and that the protagonist makes it home without further trouble (in spite of a challenging journey ahead) that the moral issue is resolved by something and more questions than answers.

So it just ends with so many unsatisfactory dangling threads I can't really recommend the book at all.

Very Interesting Premise

If I hadn't read the blurb first, I would have been confused and annoyed.

Plot seems very secondary, main purpose of the book is to explore the world Egan creates. Although this universe really is fascinating, I think the plot didn't get its dues, and in my opinion, the ending is cut short. I wish I could give 3.5 stars for plot, as it really is a close thing for me.

I liked all the characters, and the developments in the Sider/Walker relationships were just as fascinating as the wider universal physics.

Google the book to read his website about the Dichronauts universe, was a great help in understanding the reasons behind things.

Humanistic story in a mathematics settting.

This is a case when the book would be useful. You need diagrams to keep some of the plot in your head. There is an interactive web tool to see how objects behave which is really fun to play with. So the setting is just awesome and the idea to put a real human story into is great, but the only think lacking was that the overall story line was not as robust and cleanly executed as it might have been. Perhaps it is an intrinsic problem with wanting a story to be told when the maths is the main reason for telling it. Definitely read it, but don't worry about the ending.