I was not aware that physics had any bounds except those imposed by the universe - and even then there may be places with different physics beyond that. so It embraces both the probable and the improbable
But the job of physics is to supply bounds (or, more accurately, predict bounds).
If it does not, physics doesn't supply much useful information.
Of course mainstream physics can be wrong.
But more often then not, there are new domains where new bounds apply that were not predicted before.(ex speeds near light speed, dimensions near subatomic sizes, etc)
Well established bounds that have been tested over centuries (for example "no free energy from the vacuum") are typically not broken by Italian philosophers with a criminal record and a penchant for lying about sock puppets.