Fourth derivative of position?

FredGarvin

I really can't comment on the 4th derivative stuff because I abhor controls stuff. However it doesn't seem to make much sense to me either.

On the other hand, you read some good books. Arthur Young is a helicopter legend. Among other things, he came up with the stabilizing bar concept for rotor heads. I never knew he got into the whole metaphysics stuff later in life.

SW VandeCarr

There's nothing wrong with "good" metaphysics as long as we draw a clear boundary between metaphysics (not verifiable or falsifiable) and science. In this case, I was drawn in by the "mathematical" Arthur Young and generally took his metaphysics for what it was worth. As far as the other reference, I only read the first part dealing with harmonic and circular motions and never got into the perpetual motion stuff. As sylas indicated, you can make a very narrow special case for the fourth derivative as iterated position, but there's no general principle involved and apparently no connection with formal Control Theory.