Reflecting on Hempel's dilemma, Carlo Beenakker has proposed a new boundary to demarcate physics from metaphysics- viz. what is computable within the age of the Universe.
A short essay of his on this theme can be read here.
We are familiar with computational constraints on computers e.g those arising from physical constants like the speed of light, Boltzmann's constant and Planck's constant-
Beenaker argues that if the Universe is a computer and if constants, like those above, don't evolve in an inflationary manner, and if the Universe has an end in time, then certain problems- such as the question of the immortality of the soul- will always remain metaphysical because there isn't enough time to do the necessary computations to reduce the question to one of physics.
I suppose someone has stated the dual to this proposition- viz. the metaphysics/ physics boundary arises from evolved diachronicity (otherwise Hempel's dilemma is meaningless) and thus Computability theory exists only in the vanishing present of its P versus NP problem.
For which I, personally, blame David Cameron. That boy aint right.