We can't deal with these kind of serious questions now, Carbie:( why doesn't Brie cheese have holes in it??? You ever think about that? No? I didn't think so. ;)
In a late stage of cheese production, the propionibacteria consume the lactic acid excreted by the other bacteria and release acetate, propionic acid, and carbon dioxide gas. The carbon dioxide slowly forms the bubbles that develop the "holes". The acetate and propionic acid give Swiss its nutty and sweet flavor.