It can be undone though, right? https://en.wikipedia.org/wiki/Quantum_eraser_experiment https://en.wikipedia.org/wiki/Quantum_eraser_experiment Or do you mean

It can be undone though, right? https://en.wikipedia.org/wiki/Quantum_eraser_experiment https://en.wikipedia.org/wiki/Quantum_eraser_experiment Or do you mean that the point where it can no longer be undone in principle can be considered as a cutoff for "collapse"?