Complex sentence: The notion of complex spacetime may be an area of interest in it's own mathematical right, however it's appearance in physics can be rooted to attempts of unifying the fundamental interactions, originally gravity and electromagnetism.
Split into simpler sentences: The notion of spacetime having more than four dimensions is of interest in it's own mathematical right. It's appearance in physics can be rooted to attempts of unifying the fundamental interactions, originally gravity and electromagnetism.