PHY.Preface:6 - Consequences and Architectural Rationale

This arrangement makes physical construction accessible before a complete equation is supplied. A constraint can guide a model, a balance can locate a missing response, an observable distinction can select an experiment, and a physical limit can redirect development. The cost depends on which contribution is missing. A short derivation may suffice; a new interaction or difficult measurement can require substantial specialist work.

The methods are organized by recurring work rather than by mechanics, optics or another chapter of physics. Those subjects supply theories and techniques used in applications. Organizing a reference by subject remains useful when a practitioner already knows which law is needed; it does less to resolve the preceding choice of physical account or the relation between different accounts.

The separation from Mathematical Thinking and Mathematical Modeling follows the work that remains. A variational calculation does not choose its physical action or boundary freedom. A reduced mathematical system does not by itself establish that discarded physical effects are negligible. Conversely, the physical argument can use a mathematical construction unchanged across several subjects. Keeping that construction available from its supplier prevents each physical method from developing an incompatible version.

There is no universal order of mathematics, physics and computation. A mathematical obstruction can finish a physical proposal; a computed discrepancy can reveal an omitted interaction; a measuring procedure can change what the model has to retain. B.5.MPC governs that connected reasoning. The physical patterns supply methods for the physical contributions.

This is also a way to develop methods of work. A team can change who constructs, interprets or computes a contribution, provided the next contribution can still use its result and conditions. New theory, a changed instrument or a better computational construction can reopen a local choice without replacing the whole repertoire.