Which is the better e-reader: the Kindle or the iPad? It's impossible to say for at least one reason—neither provides the physical feedback we expect from turning the pages of a paperback book. Until an e-reader arrives that can simulate physical interaction, many people will prefer to stick with dead trees. But designer Fabian Hemmert thinks such a simulation could be possible. He imagines an electronic device that could shift its weight or size to indicate how far along you are in a book, or a cell phone that could react to touch like a physical being. Sound crazy? It might not seem so far-fetched after watching Hemmert explain his ideas in this video from TEDxBerlin.