PHY.3:2 - Problem

A physical proposal usually names the desired effect more readily than the whole change needed to produce it. “Return the machine to service,” “copy an input” and “extract more work” can leave different resources, input families and end conditions implicit. Those differences determine which physical restrictions apply.

Detailed calculation of one design can reveal its failure while leaving other designs available. Conversely, a quoted limit can be applied outside its premises and suppress a useful construction. The difficulty is to derive a restriction whose physical description covers the proposals being considered, and then use it to decide what to change or investigate.