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Are you sure we can't visualize 4D objects? Or rather, what exactly does that mean?

Can we visualize 3D objects? Or do we reason about 3D objects, but only visualize a 2D projection of 2D boundary surfaces embedded in 3D space? I'm definitely not thinking about the inside of my desk lamp, or even its back side, even though those are as much a part of the 3D object as the front surface.

Can you visualize a 1D projection of a 2D object? Probably, but is it a little tricky? How about a 1D projection of a 3D object? And when that 3D object moves? How about a 2D projection of a 3D object, but seen from the inside out with a Hammer retroazimuthal projection, instead of viewed from a distance with the embodied camera eye and wonderfully simple rectilinear(ish) projections that we're so familiar with?

Arguably, I think we can visualize 4D objects. They just look the same as 3D objects, because the visualization is itself a 2D projection. If they move, they look like wobbly 3D objects, as we pick up a different "slice" or "surface".

Now, we don't know very many 4D shapes, because we don't encounter them in our lives. But I think that's fully explained by familiarity, without invoking the idea of an arbitrary limitation. We've all seen lines, sheets, boxes, balls, pyramids— Try describing to a random stranger what a Strandbeest or a Klein bottle looks like.`

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