8 XXX : gonwild

Wow shit this makes a bizarre amount of sense. Sense might be the wrong word, but I feel like I know what I'm looking at more than with other 4-d gif representation thingies. This is really well done!
That shadow of a "rotating cube" on the bottom is fundamentally blowing my mind right now.
This is amazing
Is that shape physically possible?
This .gif intrigues me way too much to ignore. Can someone explain to me why the shadows are different in a mathematical sense? What do they represent? why does one look the same as the projection of a rotating cube?