Overall, we have to accept that (a) we, in real life, have no idea how any Trek physics (beyond what is based upon real physics) works, and (b) most of the "magic physics" we see in Star Trek relates either to "magic particles" or the ability to manipulate gravity (which also occasionally strays into "magic gravity particles")
Warp drive is very likely one of those "magic gravity-related" technologies. How does this relate to actual gravity (as it exists in the real world)?
Simple... IT'S MAGIC. Or, in scriptwriting terms, it's a "McGuffin."