I'm using a non-standard definition of chirality. I don't know what the standard definition of what I'm looking for is. Informally it's "if and only if in a space there are two or more types of rotation of spheres that are always distinguishable then rotation in that space is chiral." The spheres have to have no recognizable features other than their rotations.
Here in 3D a view from above the North Pole sees the Earth rotating counterclockwise. A view from above the South Pole sees the Earth rotating clockwise. So 3D is non-chiral by my definition. Or looking at a sphere you say it is rotating clockwise. Stand on your head and look at the sphere and it appears to be rotation counter-clockwise relative to you. Or consider the planet Uranus. It has no surface features and its plane of rotation is perpendicular to the ecliptic so no one can say its rotation is clockwise or counter clockwise. All odd-dimensional spaces are like this.
I once convinced myself geometrically that all even-dimensional spaces were chiral but I don't quite trust geometry and others think differently. I want an algebraic proof or a counterexample.
Here's what ChatGPT has to say about it.
You're essentially looking at the behavior of rotations in different-dimensional spaces and whether they can be consistently distinguished under all transformations (such as reflection or inversion).
From an algebraic standpoint, the key structure governing rotations is the special orthogonal group, SO(n):
In odd dimensions, SO(2k+1) has a determinant of +1, and its rotations include reflections that flip handedness (parity transformations exist within O(n), the full orthogonal group, which contains both proper and improper rotations). This allows different rotations to appear indistinguishable under reflection, making the space non-chiral.
In even dimensions, SO(2k) is fundamentally different because it has two distinct connected components in its double cover, Spin(2k), corresponding to left- and right-handed rotations. This often leads to an inherent chirality.
This supports my conclusion so naturally I like it. I'm going to have some humans check it out.
Silence. Apparently the humans don't understand this either.