Are you talking about the physics in the current cooled universe? In that case particles appear and disappear all the time
exactly. "appear" being the key.
if truly nothing, nothing comes of nothing. which means although nothing is "apparent" we know because something is, that the nothing part is only apparent, and that there is "something" we cant see.
keep your mind from this way of enquiry, for never will you show that not-being is
~parmenides