Id say that physics never ends, it just becomes more abstract. As we venture outside things we can percieve with our senses, such as other dimensions, Gods, time, etc, it beomes more imagination than knowledge. We can always theorize about things. "Imagination is more important than knowledge."
Physics is the study of motion. Anything that cannot be demonstrably shown to involve motion then is not in the realm of physics. Mysticism for example, is definitely not physics, although it can most certainly be incorporated within physics and vice versa.
Physics is a philosophy of the relational, and does not attempt to speak about intrinsic properties, or properties-in-themselves. Nor should it, as that would constitute extending beyond its scope.
One philosophical effect of this limitation is made apparent when attempting to create a complete and coherent picture of reality: it's not entirely clear how a system of relationships can enjoy an actual existence without there being some sort of intrinsic properties to play the role of "things being related." Additionally, phenomenal consciousness appears to be a construct of intrinsic properties, and thus physics would seem to be ill-equipped to broach the subject of phenomenal consciousness, aside from its relational aspects. (eg, physics can tell us what functional role sensory input of 600nm light can play in the brain, but it can't tell us anything about the subjective experience of redness qua subjective redness)
Physics is an invention of the human mind, that came into being, just as the six blind men were colliding with the elephant.
Just then they were theorizing that grouped up, they made a larger body in black space, that they were safer as a group, at about that time the elephant ran his snout up the leg of the guy in the back, who was heard to exclaim, "Space is tubular, it winds around !"
At which point the ear of the elephant had brushed back against the cheek of one of the first men, who exclaimed, "I beg to differ my dear colleague, it is obvious that space is made up of thin planes, see here, I have just discovered one of them."
Meanwhile the third of the men had run straight into the side of the beast, and murmured out of his faceplant, that topologically speaking the elephant seemed spherical, but with some other inner qualities, and he could not quite make an accurate estimate of the scope of its immensity.
At which point the man who had fallen under the elephant, had reached around a leg, and was exclaiming about the foundations of the firmament.
At the rear the small tail had whipped the fifth of the men in the head, and sensing the shape of the tail was in concurrence with man number one, that space did have some tubular aspects.
Man number six had to also concur, having run up against the tusk, like a man at a turnstile without a token.
So generally the six blind men decided that space was somewhat tubular, perhaps funnel shaped based on a series of close observations.
Physics is an invention of the human mind, and is therefore subject to the limitations of the human mind. Though we are made up of the same stuff as the rest of the universe, and we have some interesting qualities, they don't necessarily give us enough information to accurately conceive of the whole picture. In our limited framework, we are in danger from our delusions of grandeur. In fact we are in greater danger as a species, because the study of physics exists, than if we loved our life here enough, and cherished it enough, that we sought to help it along, rather than pick it apart, for gain, as we do.