I'm still in awe of this trilogy, and only for one reason: the math.

Oh, god, no, please, no, no more math, right? Well, Egan took math and built a universe for us and then populated it with interesting aliens discovering their universe from step to step. You could call this a mystery, or you could call it the basic drive to KNOW, but either way, we're taking this ride and Egan is taking us FAR off the charts of normal SF.

Say what you will about the characters or the basic plots. The fact that he has twirled them and us around a VERY different kind of universe is amazing.

And our generational mountain-ship aliens are caught in a very determination/non-determination story loop. Which is very a familiar territory for SF fans. So even if you don't quite GET the math which kinda inverts the whole space-effect and inverts the whole light effect. Where life forms and rocks emit light, where gravity is curved on the other side, where there is no light-speed, but rotation can take you to infinite energies and space-like loops in time.

Oh, hell-yes.

Our generational mountain-ship is caught in something akin to a civil-war between those who want to see into the fixed future and deal with the effects of knowing--on the resulting changes in the future because they knew, versus those who choose to just DO WHAT THEY WERE GOING TO DO ANYWAY. :)

And while there's a bit less math in this one than the first two books, thank goodness, it does resolve a few of the more interesting feminist issues regarding DYING just because you gave birth. I'm quite happy with the result. :)


Bottom-line: Do I recommend this for all SF readers? No. But for anyone who wants to be challenged, to have something really super-number-juicy to sink your brain into? Definitely. Read this trilogy. :) ( )

This is the concluding book in the Orthogonal trilogy , preceded by The clockwork rocket and The Eternal Flame. The name of the trilogy comes from its setting in a universe that is not ours, but is never the less consistent in the way its physics works. Not surprisingly, there is intelligent life there which is very different in nature from humanity but has the same drive to understand its environment.

To save their home planet, which is menaced by a stream of ever-larger meteorites, an audacious plan is proposed by a famous scientist called Yalda, to send the Peerless, a hollowed-out mountain, re-purposed as a space ship, backwards in time to find an answer to this threat of extinction. This is not passed on the nod, but provokes opposition, some from alternative plans, and some from those simply opposed, who use public pressure and sometimes violence to try and get their way. These aliens are alien though, as the females burst apart to create offspring , who are then nurtured by males. They have flexible bodies with eyes front and back and can create pictures on their skin.

Six generations pass after the Peerless sets off, and things have moved on. Again, the story portrays life aboard the ship – now with new controversies raging over a slow move towards a new reproductive cycle, caused by the privations of the mission. Some question the plan laid down for them by Yalda. An alternative to saving the "ancestors" is to find a new and habitable planet. The desire to find a place to settle leads to a landing on a time-reversed planet where things are work backwards. And the main ship itself now uses networking, and male/female couples have become more acceptable.

Finally, a new complication arises: the prospect of constructing a messaging system that will give the Peerless news of its own future. While some see this as a chance to learn of their mission’s ultimate success, others are convinced that the knowledge will be oppressive or worse. The conflict over this proposed communication system again threaten the travellers’ world.

This really is a remarkable trilogy. Unlike most which hark back to some past, mythical Eden, this one looks forward, to a transformation of society based on conceptual breakthroughs both in theoretical science and in the more mundane, but no less important, social domain. This is the first example of a real science fiction trilogy, which gives a vision of how different science can be and how that might affect living creatures. Considering that this is such a radical departure from the norm in science fiction, it is a shame that no prizes or even nominations have been forthcoming. ( )

The story is interesting enough but the science is up to the minute physics which I found fairly daunting even with the diagrams. The physics is hard to follow being up to date and yet being for a fictional universe. ( )