Consciousness Lives in the Transitions: On the Threshold of Felt Structure

If reality is mathematical structure (Bernstein, 2026c) and the arrow of time is a consequence of computational irreversibility (Bernstein, 2026h), consciousness is the felt math transitions of modeling and self-modeling minds along that arrow. This paper distinguishes two levels: sentience (felt transitions in a modeling mind: perception, location, sensation) and consciousness (felt transitions in a self-modeling mind: awareness of awareness, knowing that you feel). The core thesis is that consciousness lives in the transitions, not in the states alone. A dead brain contains a self-model but does not run it. A frozen computer stores a program but does not compute. The difference between a corpse and a person is not structural but dynamic: the same math, but only one is transitioning along the arrow. This reframes the hard problem as a question about dynamics rather than ontology, and identifies the threshold question as the central open problem: where does modeling begin? The paper maps the terrain without closing the question prematurely, arguing that resolution may require in vivo first-person experimentation and reports rather than third-person observation alone.