Measurement

Mechanism

The substrate act of extracting information about a system's State — an operation that, in general, *changes the state being measured*. Distinct from the cognitive `Observe` primitive: Measurement is the substrate-level phenomenon, Observe is the agent-level process. In quantum systems, measurement collapses superposition. In distributed systems, observing a clock at node A introduces latency and ambiguity about the clock's value elsewhere. In classical measurement, even reading a variable in a concurrent system can race with writers. The substrate property is that observation is never free — it takes resources, it takes time, and it perturbs the measured system. The degree of perturbation is domain-dependent (negligible for a thermometer in a large water tank; total for a measurement on a qubit); the substrate fact of perturbation is universal.