ld wrote:One of the crux questions in stylus-groove mechanics is 'does indentation happen ?'. And convention has it that intuitively the answer is yes. But I think this visualisation of how fast the stylus-groove interface changes alters that intuition. I venture it reverses it. So that it's intuitive it doesn't indent, rather it skids the surface ?!
I'm not sure intuition cuts it here, either way. You wouldn't intuitively expect a solid enough object like a golf ball to do this either:http://www.youtube.com/watch?v=aMqM13EUSKw
This clip illustrates, I think, the perils of hypothesing behaviour based on only what we can detect with our senses. Technology extends our vision, especially, in dramatic fashion. That golf ball would have just hit the plate with a thud and dropped to the ground, with the viewer none the wiser to the dramatic temporary change of form and maybe even of state. If I've calculated correctly that action took place over a time period of 2 milliseconds.
Yes, the record groove moves under the stylus at a relatively huge speed, in our terms, but that doesn't preclude the possibility of a lot of interesting and unexpected things going on that we have no idea about.