What does it mean to exist? A thing exists specifically when it affects something else. What is measurement? It's a reciprocal affecting.
So does a thing which is not affecting anything else and not being measured exist? No! QED
So does a thing which is not affecting anything else and not being measured exist? No! QED
What really still gets me is the way it's not simply that the atom wasn't interacted with, but that if the information about the interaction never leaks to the outside world - if it's "erased" after the interaction takes place - then the system still behaves as if the interaction never took place.
It undermines not just the concept that matter really exists, but time as well.
All that's starting to sound an awful lot like Orthodox Christian theology about the essence of God…