Simplify the following text for a Grade 14 native English-speaking person.
Original: The theory of special relativity is believed to hold throughout the universe , provided that the spatial and temporal length scales are sufficiently short ; otherwise , the more general theory of general relativity must be applied .
Simplified: The idea of special relativity is thought to hold in all of the universe , provided that the spatial and temporal length scales are sufficiently short ; otherwise , general relativity must be applied .