The measured slowing of clocks in a gravitational field may possibly be an special instance (i.e., not restricted to gravitation) of time-dilation in composite force-fields more generally. If such centripetal force (as gravitation) will result a slowing of clocks, then a centrifugal force (such as that produced by rapid rotation) ought to result in the opposite effect, namely a speeding of clocks. [This may be somewhat difficult to measure, as other physical effects of the circumfuge may obscure this effect on the quartz-vibration clock.]

Because a composite force-field (with two forces mutually perpendicular) would appear to be necessary to produce these effects on clocks, non-composite force-fields (e.g., magnetic or electric) would not appear to produce the effects. Gravitation is believed to be a composite force-field (with "gravito-magnetic" and "gravito-electric" components). Heat may not be capable to producing noticeable (macroscopic) time-dilation effects simply on account of mutually cancelling influences of multiple and varying wavelengths (of phonons photons involved), and lack of co-ordinated macroscopic orientation among the internal quantum-level force-fields.

If each photon be a vortex (this is the usual model of it), then its activity is explained by the speeding of time by its centrifugal structure – in the special relativity-theory, however, it is assumed to be halted in time, making it inert and incapable of activity.