Your [1] <https://arxiv.org/abs/1307.6167 https://arxiv.org/abs/1307.6167> is a really interesting choice for examining the use of "emergence" in the broad amon

Your [1] <https://arxiv.org/abs/1307.6167 https://arxiv.org/abs/1307.6167> is a really interesting choice for examining the use of "emergence" in the broad among quantum gravity researchers. I think looking down to the start of §6 of your [1] is even more fruitful than §2.2: "... novel form of dynamics that can be applied to a unique system -- the universe as a whole [--] that is neither quantum mechanics nor general relativity[,] from which quantum physics and space-time emerge as approximate descriptions of systems that may be regarded to a sufficient degree of approximation as isolated subsystems." Or, more succintly and focusing on the gravitational content, "the Einstein Field Equations may be derived for some part(s) of a universe described by our theory", with the additional constraint, "but our theory cannot be derived from General Relativity". Compare with Newton's gravitation and its ability to be derived in the weak field, low speed limit of General Relativity (and that physically interesting generally curved spacetimes have large regions that are effectively flat). Generalizing, a theory of gravity is emergent when its fundamental equation(s) can be derived from a different dynamical theory, and the derivation is a one-way street. However, "emergent" gets used in a different sense only a few paragraphs later in [1]: "Time reversal invariance is amongst the symmetries that must emerge from the coarse graining that neglects the unique identity of each event. From our perspective fundamental physics is time asymmetric and the apparent time symmetry of the laws of nature is approximate and emergent." In this case they are not strictly speaking deriving time symmetry from their dynamical theory, but rather they are claiming that averaging the behaviour of their theory across some region(s) matches observation.