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Spinning Shadows
Author(s) -
SORENSEN Roy
Publication year - 2006
Publication title -
philosophy and phenomenological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 39
eISSN - 1933-1592
pISSN - 0031-8205
DOI - 10.1111/j.1933-1592.2006.tb00564.x
Subject(s) - shadow (psychology) , spinning , motion (physics) , point (geometry) , movement (music) , physics , classical mechanics , geometry , mathematics , psychology , engineering , acoustics , mechanical engineering , psychotherapist
If a spinning sphere casts a shadow, does the shadow also spin? This riddle is the point of departure for an investigation into the nature of shadow movement. A general theory of motion will encompass all moving things, not just physical objects. Ultimately, I argue that round shadows do indeed spin. Shadows are followers of the objects that cast them. Parts of the shadow correspond to parts of the leader, so motion of the caster's parts accounts for motions of the shadow's parts. I conclude with a discussion of how the dynamic aspects of shadows impose subtle constraints on other puzzles about shadows.