If there are 4 (or more) physical dimensions, and physical objects can move through the 4th dimension in paths perpendicular to our 3 dimensions, the physical objects must pass through our 3-dimensional universe every now and then. To an observer, it would appear that a physical object appeared out of nothing, grew, shrank, and disappeared. Mass would appear to be created and destroyed.
So why haven't we ever witnessed that? Does the lack of that kind of observation mean one of the following?
- There are only 3 physical dimensions.
- Physical objects can't move perpendicular to our 3 dimensions.
- There may be 4 dimensions, but physical objects only ever move parallel to our 3 dimensions, so they don't intersect our 3-dimensional space.