PHY.Preface:2 - Problem and forces - Keep the physical question through the calculation
A physical calculation operates on mathematical objects chosen to describe participants, states, interactions and observations. A consequence of those objects answers the physical question only through the interpretation and premises that connect them. A correct calculation can therefore expose an omitted physical distinction without supplying the law that repairs it.
Several tensions shape the choice of method:
| Working tension | Choice that changes the result |
|---|---|
| A complete mechanism and a useful first consequence | Can a direction, bound or constrained family answer before the whole law is known? |
| Physical detail and obtainable calculation | Which scale, state or interaction can be omitted for this consequence? |
| A mathematical comparison and a changed physical situation | Which participants, preparation and surroundings must transform together? |
| A predicted difference and an observable difference | Can the actual interaction and readout expose the distinction? |
| Agreement and criticism | Does the observation separate the accounts, or do their free parameters and apparatus effects still overlap? |
| Further inquiry and available effort | Would another computation or experiment change a decision worth its cost? |
These choices can occur in theory construction as well as in an applied project. An unexplained dependence, a failed comparison or an impossibility can open a useful new question. The next question may seek another law, a different observation, a new way to prepare the system or an application of an established result.