In the near future of Robert Charles Wilson's Last Year, the technology exists to open doorways into the past - but not our past, not exactly. Each "past" is effectively an alternate world, identical to ours but only up to the date on which we access it. And a given "past" can be reached only once. After a passageway is open, it's the only road to that particular past; once closed, it can't be reopened.

Cassie Klyne, 19 years old, lives in the United States in the year 2015 - but it's not our United States, and it's not our 2015. Cassies world has been at peace since the Great Armistice of 1918. There was no World War II, no Great Depression. Poverty is declining, prosperity is increasing everywhere; social instability is rare. But Cassie knows the world isn't what it seems. Her parents were part of a group who gradually discovered the awful truth: That for decades - back to the dawn of radio communications - human progress has been interfered with, made more peaceful and benign, by an extraterrestrial entity.

For Oxford student Kivrin, traveling back to the 14th century is more than the culmination of her studies - it's the chance for a wonderful adventure. For Dunworthy, her mentor, it is cause for intense worry about the thousands of things that could go wrong.

Three remarkable journeys into the stars: Worlds of Exile and Illusion includes Rocannon's World, Planet of Exile, and City of Illusions. These three spacefaring adventures mark the beginning of grand master Ursula K. Le Guin’s remarkable career. Set in the same universe as Le Guin’s groundbreaking classics The Left Hand of Darkness and The Dispossessed, these first three books of the celebrated Hainish series follow travelers of many worlds and civilizations in the depths of space.

What could be more commonplace than grass or a world covered over all its surface with a wind-whipped ocean of grass? But the planet Grass conceals horrifying secrets within its endless pastures. And as an incurable plague attacks all inhabited planets but this one, the prairie-like Grass begins to reveal these secrets - and nothing will ever be the same again.

A human diplomat creates an interstellar incident when he kills an alien diplomat in a most unusual way. To avoid war, Earth's government must find an equally unusual object: A type of sheep ("The Android's Dream"), used in the alien race's coronation ceremony. To find the sheep, the government turns to Harry Creek, ex-cop, war hero and hacker extraordinaire.

Neanderthals have developed a radically different civilization on a parallel Earth. A Neanderthal physicist, Ponter Boddit, accidentally passes from his universe into a Canadian underground research facility. Fortunately, a team of human scientists, including expert paleo-anthropologist Mary Vaughan, promptly identifies and warmly receives Ponter. Solving the language problem and much else is a mini-computer, called a Companion, implanted in the brain of every Neanderthal. But it can't help his fellow scientist back in his world, Adikor Huld, when the authorities charge Adikor with his murder.

William Mandella is a soldier in Earth's elite brigade. As the war against the Taurans sends him from galaxy to galaxy, he learns to use protective body shells and sophisticated weapons. He adapts to the cultures and terrains of distant outposts. But with each month in space, years are passing on Earth. Where will he call home when (and if) the Forever War ends?

“It happened fast. Thirty-two minutes for one world to die, another to be born". An epic and gripping tale of catastrophe and survival, The Passage is the story of Amy - abandoned by her mother at the age of six, pursued, and then imprisoned by the shadowy figures behind a government experiment of apocalyptic proportions. But Special Agent Brad Wolgast, the lawman sent to track her down, is disarmed by the curiously quiet girl and risks everything to save her. As the experiment goes nightmarishly wrong, Wolgast secures her escape - but he can’t stop society’s collapse.

The world outside has grown toxic, the view of it limited, talk of it forbidden. The remnants of humanity live underground in a single silo. But there are always those who hope, who dream. These are the dangerous people, the residents who infect others with their optimism. Their punishment is simple. They are given the very thing they want: They are allowed to go outside.

In this Hugo Award-winning classic, Enoch Wallace is an ageless hermit, striding across his untended farm as he had done for over a century, still carrying the gun with which he had served in the Civil War. But what his neighbors must never know is that, inside his unchanging house, he meets with a host of unimaginable friends from the farthest stars.

Eleven-year-old George Washington Black—or Wash—a field slave on a Barbados sugar plantation, is initially terrified when he is chosen as the manservant of his master’s brother. To his surprise, however, the eccentric Christopher Wilde turns out to be a naturalist, explorer, inventor, and abolitionist. Soon Wash is initiated into a world where a flying machine can carry a man across the sky, where even a boy born in chains may embrace a life of dignity and meaning, and where two people, separated by an impossible divide, can begin to see each other as human.

Winner of the 1973 National Book Award, Gravity's Rainbow is a postmodern epic, a work as exhaustively significant to the second half of the 20th century as Joyce's Ulysses was to the first. Its sprawling, encyclopedic narrative and penetrating analysis of the impact of technology on society make it an intellectual tour de force.

Amber is the one real world, of which all others including our own Earth are but Shadows. Amber burns in Corwin's blood. Exiled on Shadow Earth for centuries, the prince is about to return to Amber to make a mad and desperate rush upon the throne.

Nobody remembers how the Causality War started. Really, there's no-one to remember and nothing for them to remember if there were; that's sort of the point. We were time warriors and we broke time. I was the one who ended it. Ended the fighting, tidied up the damage as much as I could. Then I came here, to the end of it all, and gave myself a mission: to never let it happen again.

Scott Warden is a man haunted by the past-and soon to be haunted by the future. In early 21st-century Thailand, Scott is an expatriate slacker. Then, one day, he inadvertently witnesses an impossible event: the violent appearance of a 200-foot stone pillar in the forested interior. Its arrival collapses trees for a quarter mile around its base, freezing ice out of the air and emitting a burst of ionizing radiation. It appears to be composed of an exotic form of matter.

Cassie Klyne, 19 years old, lives in the United States in the year 2015 - but it's not our United States, and it's not our 2015. Cassies world has been at peace since the Great Armistice of 1918. There was no World War II, no Great Depression. Poverty is declining, prosperity is increasing everywhere; social instability is rare. But Cassie knows the world isn't what it seems. Her parents were part of a group who gradually discovered the awful truth: That for decades - back to the dawn of radio communications - human progress has been interfered with, made more peaceful and benign, by an extraterrestrial entity.

Robert Charles Wilson, says The New York Times, "writes superior science fiction thrillers." His Darwinia won Canada's Aurora Award; his most recent novel, The Chronoliths, won the prestigious John W. Campbell Memorial Award. Now he tells a gripping tale of alien contact and human love in a mysterious but hopeful universe.

In our rapidly-changing world of "social media", everyday people are more and more able to sort themselves into social groups based on finer and finer criteria. In the near future of Robert Charles Wilson's The Affinities, this process is supercharged by new analytic technologies - genetic, brain-mapping, behavioral.

Lise Adams is a young woman attempting to uncover the mystery of her father's disappearance ten years earlier. Turk Findley is an ex-sailor and sometimes-drifter. They come together when an infall of cometary dust seeds the planet with tiny remnant Hypothetical machines. Soon, this seemingly hospitable world will become very alien indeed--as the nature of time is once again twisted, by entities unknown.