Fifth-Force Windows from Micrometres to Astronomical Units: Where a New Yukawa Interaction Could Still Hide

Plotting the best published limits on a Yukawa fifth force against its range, from a micrometre to an astronomical unit, reveals a landscape spanning 20 orders of magnitude in permitted strength. The interaction is fenced to 1.0e-10 of gravitational strength at planetary ranges and to 1.0e-05 at a centimetre, yet at a micrometre a strength of 1e+10 times gravity remains formally permitted by Casimir-regime comparisons, and the geophysical decade near a kilometre is softer than its neighbours. A new interaction from the frame would find its only room at the shortest ranges or in couplings that the range plot does not capture at all, such as spin dependence. The limits tabulated are order-of-magnitude summaries of the published literature and are labelled as such. Computed, not measured.