I think the science behind it is not necessarily the thickness of the strings but how much tension is there, Freddie Green was said to have the action about an inch from the fretboard to get all the volume he could. However, the last time I saw Marty Grosz play he had light strings on a 1938 16" (obviously) L5, plus a really thin pick and he just blew me away. So there are obviously more factors to consider, but strings seem to be a necessarily element.