  A simple quantum interaction is analyzed, where the paths of two superposed
particles asymmetrically cross, while a detector set to detect an interaction
between them remains silent. Despite this negative result, the particles'
states leave no doubt that a peculiar interaction has occurred: One particle's
momentum changes while the other's remains unaffected, in apparent violation of
momentum conservation. Revisiting the foundations of the quantum measurement
process offers the resolution. Prior to the macroscopic recording of no
interaction, a brief Critical Interval prevails, during which the particles and
the detector's pointer form a subtle entanglement which immediately dissolves.
It is this self-cancellation, henceforth "Quantum Oblivion (QO)," that lies at
the basis of some well-known intriguing quantum effects. Such is
Interaction-Free Measurement (IFM) [1] and its more paradoxical variants, like
Hardy's Paradox [2] and the Quantum Liar Paradox [3]. Even the Aharonov-Bohm
(AB) effect [4] and weak measurement [5] turn out to belong to this group. We
next study interventions within the Critical Interval that produce some other
peculiar effects. Finally we discuss some of the conceptual issues involved.
Under the time-resolution of the Critical Interval, some nonlocal phenomena
turn out to be local. Momentum is conserved due to the quantum uncertainties
inflicted by the particle-pointer interaction, which sets the experiment's
final boundary condition.
