In A Wrinkle In Time, the children use a process called tessing to teleport to different worlds and dimensions Below you will find a little more information on how modern science explains what a Tesseract is and how wormholes function.
In mathematics, a tesseract is a four-dimensional shape (hypercube) that, when represented in three dimensions, looks, e.g., like a cube inside of a cube with spokes connecting the corners of the two cubes together. In the novel, the tesseract functions more or less like what in modern science-fiction is called a space warp or a wormhole, a portal from one area of space to another which is possible through the bending of the structure of the space-time continuum. A similar concept occurs in Frank Herbert’s Dune novel where it is called the Holtzman effect.
Wormhole / Time travel
A wormhole, also known as an Einstein-Rosen Bridge is a hypothetical topological feature of space-time that would be, fundamentally, a “shortcut” through space-time. For a simple visual explanation of a wormhole, consider space-time visualized as a two-dimensional (2D) surface. If this surface is folded along a third dimension, it allows one to picture a wormhole “bridge”. (Please note, though, that this is merely a visualization displayed to convey an essentially unvisualisable structure existing in 4 or more dimensions. The parts of the wormhole could be higher-dimensional analogues for the parts of the curved 2D surface; for example, instead of mouths which are circular holes in a 2D plane, a real wormhole’s mouths could be spheres in 3D space.) A wormhole is, in theory, much like a tunnel with two ends each in separate points in space-time.