  The principle of `absoluteness of cause' (AC) assumes the cause-effect
relation to be observer independent and is a distinct assertion than
prohibiting occurrence of any causal loop. Here, we study implication of this
novel principle to derive a fundamental no-go result in quantum world. AC
principle restrains the `time order' of two spacelike separated
events/processes to be a potential cause of another event in their common
future, and in turn negates existence of a quantum device that transforms an
arbitrary pure state to its orthogonal one. The present {\it no-go} result is
quite general as its domain of applicability stretches out from the standard
linear quantum theory to any of its generalizations allowing deterministic or
stochastic nonlinear evolution. We also analyze different possibilities of
violating the AC principle in generalized probability theory framework. A
strong form of violation enables instantaneous signaling, whereas a weak form
of violation forbids the theory to be locally tomographic. On the other hand,
impossibility of an intermediate violation suffices to discard the universal
quantum NOT logic.
