From the April 2010 issue

What’s the maximum number of spatial dimensions a universe could have?

Reader question: What is the maximum number of spatial dimensions any universe could have? -Johnnie Smilinski, Winnipeg, Manitoba
By | Published: April 26, 2010 | Last updated on May 18, 2023
Quantum level
At extremely close distances, the quantum level, the concept of dimension may break down. Additional dimensions could be curled up in rings or spheres; and the closer we zoom in, the more detail we see.
Astronomy: Roen Kelly

Physicists have been considering the possibility that there are dimensions additional to those three. (How many is unknown.) Those extra dimensions clearly are not visible in everyday life, but would play a role on tiny scales.