"Engineer" in the military sense - digging trenches, bridging rivers and setting up siege engineers. It comes closer to the modern "sapper".
In France the fire-brigades are (mostly) called sapeurs-pompiers
because they were re-purposed military engineers.
Prospero comes fairly close to the modern phsyicist, perhaps because he was modelled on Dr. John Dee.
Admittedly, Dee was an astrologer, but string theory physicists aren't all that different.