The Arrows of Time is a hard science-fiction novel by Australian author Greg Egan and the third part of the Orthogonal trilogy. The novel was published by Gollancz on 21 November 2013 with a cover art by Greg Egan and by Night Shade Books on 5 August 2014 with a cover art by Cody Tilson.[1][2][3] The novel describes the return journey of the generation ship Peerless, which has been launched in The Clockwork Rocket[4][5][6] and traveled into the void in The Eternal Flame,[7][8][9] and the reverse enabling the construction of a device to receive messages from the own future as well as the journey to a world where time runs in reverse. The universe of the novel is therefore based on a Riemannian instead of a Lorentzian manifold (which describes our own universe, where time only flows in one direction or the corresponding region being hidden behind an event horizon otherwise), changing the rules of physics. The details are described by Greg Egan on his website.[10]