Vacuum polarisation is about as simple as QFT gets and very well understood. Nuclear decay less so, but it’s nuts to say it’s theoretical - it actually has whole practical industries built around it.
While I’m at it, “frame of reference” means something pretty specific, you should be careful not to use it in a physics context unless you really do mean a usually-inertial choice of coordinate system for movement.
Vacuum polarisation is about as simple as QFT gets and very well understood. Nuclear decay less so, but it’s nuts to say it’s theoretical - it actually has whole practical industries built around it.
While I’m at it, “frame of reference” means something pretty specific, you should be careful not to use it in a physics context unless you really do mean a usually-inertial choice of coordinate system for movement.