What are your favourite science fiction books (or authors)? Why are they a must-read?
My top favourite science fiction author is Greg Egan. He has written some of the most compelling and fascinating hard science fiction books. Deeply philosophical, captivating, and full of strange ideas.
Let’s start with some of his coolest books. I’ll quote the book descriptions from his homepage. They are descriptive and cool enough 
Diaspora:
In 2975, the orphan Yatima is grown from a randomly mutated digital mind seed in the conceptory of Konishi polis. Yatima explores the Coalition of Polises, the network of computers where most life in the solar system now resides, and joins a friend, Inoshiro, to borrow an abandoned robot body and meet a thriving community of “fleshers” in the enclave of Atlanta.
Twenty-one years later, news arrives from a lunar observatory: gravitational waves from Lac G-1, a nearby pair of neutron stars, show that the Earth is about to be bathed in a gamma-ray flash created by the stars’ collision — an event that was not expected to take place for seven million years. Yatima and Inoshiro return to Atlanta to try to warn the fleshers, but meet suspicion and disbelief. Some lives are saved, but the Earth is ravaged.
In the aftermath of the disaster, the survivors resolve to discover the cause of the neutron stars’ premature collision, and they launch a thousand polises into interstellar space in search of answers. This diaspora eventually reaches a planet subtly transformed to encode a message from an older group of travellers: a greater danger than Lac G-1 is imminent, and the only escape route leads beyond the visible universe.
Orthogonal (book series):
In Yalda’s universe, light has no universal speed and its creation generates energy.
On Yalda’s world, plants make food by emitting their own light into the dark night sky.
As a child Yalda witnesses one of a series of strange meteors, the Hurtlers, that are entering the planetary system at an immense, unprecedented speed. It becomes apparent that her world is in imminent danger — and that the task of dealing with the Hurtlers will require knowledge and technology far beyond anything her civilisation has yet achieved.
Only one solution seems tenable: if a spacecraft can be sent on a journey at sufficiently high speed, its trip will last many generations for those on board, but it will return after just a few years have passed at home. The travellers will have a chance to discover the science their planet urgently needs, and bring it back in time to avert disaster.
Orthogonal is the story of Yalda and her descendants, trying to survive the perils of their long mission and carve out meaningful lives for themselves, while the threat of annihilation hangs over the world they left behind. It will comprise three volumes:
Interestingly, the universe of Orthogonal results from simply switching a sign in the equations of special relativity. In some sense, the Orthogonal is more symmetrical than ours! This book series is a truly magnificent and natural exploration of alternative physics! The theme of book 3 is causality and time-travel, and very mind-bending, so please read the whole series!
Permutation City: Ok, the except from Egan’s homepage is not cool enough to tell how amazing this book is. It’s about the creation of a whole new, autonomous (quasi-virtual) reality into which the minds of many people are transferred. These transferred persons participate in creating a great city, but everyone will face his own personal psychological dilemmas. And great surprises await.
Schild’s Ladder:
For twenty thousand years, every observable phenomenon in the universe has been successfully explained by the Sarumpaet Rules: the laws governing the dynamics of the quantum graphs that underlie all the constituents of matter and the geometric structure of spacetime. Now Cass has stumbled on a set of quantum graphs that might comprise the fundamental particles of an entirely different kind of physics, and she has travelled three hundred and seventy light years to Mimosa Station, a remote experimental facility, in the hope of bringing this tantalising alternative to life. The “novo-vacuum” is predicted to begin decaying the instant it’s created, but even a short-lived, microscopic speck could shed light on the origins of the universe, and test the Sarumpaet Rules more rigorously than ever before.
Cass’s experiment turns out to be more successful than anticipated: the novo-vacuum is more stable than the ordinary vacuum around it, and a region in which the new physics holds sway proceeds to expand out from Mimosa at half the speed of light.
Six hundred years later, more than two thousand inhabited systems have been lost to the novo-vacuum. On the Rindler, a ship that has matched velocities with the encroaching border, people have come from throughout inhabited space to study the phenomenon. Most are Preservationists, hunting for a way to turn back the tide, but a few belong to another faction: Yielders, who believe that the challenge of adapting to survive on the far side of the border would reinvigorate a civilisation that has grown stale and insular.
Tchicaya has come to the Rindler to join the Yielders, but when Mariama — a childhood friend whose example inspired him to abandon his own home world and traditions for a life of travel — arrives soon after, he is shocked to discover that she plans to help the Preservationists find a way to destroy the novo-vacuum.
As a theoretical breakthrough leads to a sequence of experiments that begins to reveal the true richness of the world behind the border, tensions between the opposing factions grow. When a splinter group responds to these revelations with violent, unilateral action, Tchicaya and Mariama are forced into an uneasy alliance, and travel together through the border, balancing old and new loyalties against the fate of two incomparably different universes.
Ok, now let me briefly mention some books by other authors before this post gets too long:
The Cuture Series by Iain M. Banks: A fanciful far future vision of an anarcho-democratic galactic civilization.
Accelerando by Charles Stross: In some sense this is a “classical” depiction of a Technological Singularity in which mankind is threatened by an advanced machine civilization is has created itself. Also, aliens. And wonderfully interesting ideas and technologies.
Down and out in the Magic Kingdom by Cory Doctorow: Uploading, reputation economy, ad-hoc organizations running society. Very cool stuff!
The Golden Age trilogy by John C. Wright: Another far future vision, with a very radical anarcho-capitalist angle. One of the most compelling and thoughtful visions of an advanced solar civilization, even though it may have a few flaws (yes, the anarcho-capitalism, but it seems to work better than anyone one would reasonably expect).
Lady of Mazes by Karl Schroeder: Multiple overlapping virtual/augmented realities are the norm in the future depicted in this novel. The general topic is explored in great detail and is truly mind-boggling. In some sense, it’s a post-singularity scenario that looks rather attractive in many respects. Everyone lives in the reality in which she feels most at home and which reflects her values the most. Why not? 
Nexus by Ramez Naam: In a relatively close future a substance called Nexus is developed that can connect the minds of different people. For government it’s a drug that poses a threat to society, so it’s ban must be enforced brutally. For Nexus users, it’s a tool to free humanity. The depiction of telepathic and empathic communication and group mind in this novel is quite interesting and rather realistic.
A Fire Upon the Deep by Vernor Vinge: The galaxy is divided into zones of thought. Very fast computing devices only work in the outer regions of the galaxy, and there they allow for faster than light travel. Towards the core of the galaxy even human level intelligence becomes hard to achieve. In this novel, the outer regions get haunted by a hostile superintelligence that suddenly gets awakened from slumber. Among other cool stuff, this novel features galactic information networks and a species who evolved group minds naturally.
A Deepness in the Sky by Vernor Vinge: This is the official prequel to A Fire Upon the Deep. Two very different human civilizations – one information traders, the other a mind-controlling tyranny – meet at a mysterious star that switches itself on and off periodically. To their surprise, one of its planet is inhabited by intelligent life which adapted to the weird cycles of their sun. While the human factions fight a desperate sometimes open, sometimes subversive psychological, informational, and physical battle in their star ships, the inhabitants of the alien world are about to enter the atomic age in the hope to become more independent from their host sun. And when they discover ancient alien materials, things become really crazy.
