Ya that's definitely true. You might check out JLN labs, they have a bunch of over unity and reactionless rocket experiments drawing from the work by TT Brown:
Some of the more fascinating ones are in near-vacuum. I remember reading that asymmetric fields might be able to propel virtual pairs or interact with the interstellar medium, but unfortunately the effect seems to fall too quickly in relation to density.
There was another article about how since cooper pairs are delocalized in a superconductor, they may not interact with gravity. It was trying to explain things like the electrogravitic effects near spinning superconductors:
I keep thinking that if any of these do stray from physics, it will be interesting to see how they reconcile it. So far it hasn't happened but days like today make me wonder if it's just around the corner.
