The Arrows of Time by Greg Egan

Greg Egan’s The Arrows of Time is the third volume of the Orthogonal trilogy (Gollancz £16.99)

“After generations of travel, the spaceship Peerless may finally have achieved its goal – but the decision to return home may create more tensions than ever before.

In an alien universe where space and time play by different rules, interstellar voyages last longer for the travellers than for those they left behind. After six generations in flight, the inhabitants of the mountain-sized spacecraft the Peerless have used their borrowed time to develop advanced technology that could save their home world from annihilation.

But not every traveller feels allegiance to a world they have never seen, and as tensions mount over the risks of turning the ship around and starting the long voyage home, a new complication arises: the prospect of constructing a messaging system that will give the Peerless news of its own future.

While some of the crew welcome the opportunity to be warned of impending dangers - and perhaps even hear reports of the ship's triumphant return – others are convinced that knowing what lies ahead will be oppressive, and that the system will be abused. Agata longs for a chance to hear a message from the ancestors back on the home world, proving that the sacrifices of the travellers have not been in vain, but her most outspoken rival, Ramiro, fears that the system will undermine every decision the travellers make.”