Glossary
Fourth Dimension
Time, treated by Sparrow as a physical construct that is normally stable but can be corrupted, producing a Tangent Universe.
"The Fourth Dimension of Time is a stable construct, though it is not impervious to corruption." Sparrow never explains what corrupts it. The film offers no cause either: the Tangent Universe simply happens, above Donnie's house, on October 2.
Professor Monnitoff's physics lessons on wormholes and Stephen Hawking are the film's scientific counterpart to Sparrow's Fourth Dimension.
Defined in The Philosophy of Time Travel