query: What's the name of this sci-fi story with a wall that cannot be crossed?
positive_passages.docid: 19817
positive_passages.text: Identify a short story about a wall on a planet at the edge of a tiny universe
negative_passages.docid: 98805
negative_passages.text: Trying to identify a short story in which aliens turned an entire city block into a spaceship
negative_passages.docid: 16119
negative_passages.text: Identify this story about the end of the world (possibly the Big Rip)?
negative_passages.docid: 42386
negative_passages.text: Seeking a story about a subway train journey, through a universe made entirely of city
negative_passages.docid: 36075
negative_passages.text: Identifying a short story about time travel and paradoxes
negative_passages.docid: 81680
negative_passages.text: Story featuring smart people sent on a space mission to nowhere
negative_passages.docid: 55772
negative_passages.text: Time/space traveling story where a person travels through a portal in the London Underground
negative_passages.docid: 67118
negative_passages.text: Short story about alien invasion with a twist.
negative_passages.docid: 73275
negative_passages.text: Pre-1972 sci-fi short story or novel: alien(?) tunnel where people try new moves and get destroyed if they're not the correct ones
negative_passages.docid: 97727
negative_passages.text: Children's short story about material that accelerates away from gravity
negative_passages.docid: 8281
negative_passages.text: Science fiction story where an older person (alien) is barricaded in a house and attacked by flying lights; ends up in Stonehenge and another planet
negative_passages.docid: 26391
negative_passages.text: SF Story about human adapting to alien environment
negative_passages.docid: 75047
negative_passages.text: Scifi novel where humans defeat an ancient AI enemy by firing a wave of "slowness", preventing hyperdive space travel
negative_passages.docid: 2463
negative_passages.text: Story ID - Humans of various epochs are transported to a world
negative_passages.docid: 136911
negative_passages.text: A story about the world split into three realms
negative_passages.docid: 135160
negative_passages.text: Story about two lovers who can stop time when they're touching - maybe in Omni
negative_passages.docid: 154725
negative_passages.text: Looking for identification of SF story where humans are the "ancient evil"