My favourite random thought so far: Ghosts are 4 dimensional creatures. Now hear me out. We human are living in 3d spaces and we cast 2d shadow and projected it on the flat ground right? If we assume that there are 2d flat living beings within their 2d space then our shadows are accidentally passing through, we would be seen as ghosts appearing out of nowhere to them wouldn't it? Based on that then, does the logic should also apply the same on higher dimension and so on?