Full Idea
Space, like matter, is a subjective form. Time is not. Space first emerged through the assumption of empty space. This doesn't exist. Force is everything.
Gist of Idea
Unlike time, space is subjective. Empty space was assumed, but it doesn't exist
Source
Friedrich Nietzsche (Unpublished Notebooks 1881-82 [1882], 1[003])
A Reaction
I would think modern physics endorses his opinion of space. The original atomists proposed a 'void', to prevent traffic jams of atoms. Now we see space as fields, so it is never empty.
Book Reference
Nietzsche,Friedrich: 'The Joyful Science, and 1881-82 fragments (v 6)', ed/tr. Del Caro,Adrian [Stanford 2023], p.3