Subspace field mechanics is a division of physics.
Doctor Telek R'Mor was surprised by B'Elanna Torres' feat of binding a transporter beam into visual link between the Talvath and the USS Voyager through a micro-wormhole, when she matched his data transmission to the phase amplitude of the com signal. While the technology existed in the 2370s, it did not exist in the 2350s, the time period that R'Mor lived in. His learning of this technology was described by R'Mor as "an incredible breakthrough in subspace field mechanics." (VOY: "Eye of the Needle")