Watch The Fourth Dimension Full Movie Free Online 123Movies. The film begins with methodical descriptions of one-dimensional, two-dimensional, and three-dimensional space. It then looks at a two-dimensional world inhabited by flat mice. It imagines how a human, from the third dimension could interact with that world. It then suggests how beings from a fourth dimension might interact with us. Next the film posits time as a fourth dimension, with scenes to aid comprehension. An off-screen narrator, graphs, and clever photography provide explanations and illustrations. The film asks viewers to use their imaginations.