im only halfway through, but this seems simple. when he said ''what do you think will happen. i was like, itll do the same thing, its only the perspective that changing really right. like, if you stuck a camera on the screw as it turned, itd look like it wasnt moving and the outside was. the screw being still just means its the cylinder thats moving the particles up the screw. a mi the only one that thought this seemed logical as soon as they saw it?