fourth dimension

A Little Leaguer is transported back to King Arthur's time and given the mission of saving Camelot from the evil Lord Belasco.

"Flatland is a world that exists entirely on a two-dimensional plane. All different kinds of shapes live, work and play in this world. The story follows Arthur Square and his curious granddaughter Hex. When a mysterious visitor arrives from Spaceland, Arthur and Hex must come to terms with the truth of the third dimension, risking dire consequences from the evil Circles that have rules Flatland for thousands of years."--Container.

Time-travel researcher Ned Henry shuttles back and forth between the 21st century and the 1940s in order to correct an incongruity brought forward from the past.

On a class trip to an ancient monument you are chosen to journey into the past. There you meet a huge, green man who orders you to cut off his head. You're sure this is some sort of test -- but what is the right answer?.

Steven Whitefeather, a member of the Temporal Corps, a group of men and women who travel in time to make sure that history is not altered,is sent to London in 1940 to prevent the assassination of Winston Churchill.

Lawrence Krauss examines humans' fascination with parallel universes, veiled dimensions, and places beyond normal perception, describing how alternate realities have been explored and explained from ancient times to the present and profiling influential theories.

A. Square, a resident of Flatland--a place limited to two dimensions and peopled by a hierarchy of geometrical forms--stirs up trouble when he is visited by a sphere and begins to speak openly about worlds with three and four dimensions.

Chronologist Sam Magruder is sucked into the age of dinosaurs while working on an experiment on the quantum theory of time-motion in the year 2162, and leaves slabs of writing that chronicle his experiences for future generations to find.