I understand that vacuum authenticity (i.e. true or false vacuum) is really a QFT notion but when I had a QFT class, I was told that, in class, I should mainly be concerned with vacua of the same authenticity. My research is a whole another story, where I am concerned with vacua of different authenticities. I read Coleman's classic paper and interactions between vacua of different authenticities will result in the decay of the false vacuum, with some characteristic time that depends on the Euclidean action. However, is there any other use to vacuum authenticity other than inflationary studies, the very early universe and superconductors?