> If a slinky slinks, and nobody is watching, does it matter?
Man, asking all the hard questions. It reminds me of the "If a tree falls in a forest and no one is around to hear it, does it make a sound?" question. Maybe you could live stream it though.
Also note that there are juggling machines that are stable without any active control [1]. Designing a self stabilizing slinky escalator could be really hard though (if not impossible).