  In this second part of our series of two papers, where spacetime is modelled
by a graph, where Planck size quantum black holes lie on the vertices, we
consider the thermodynamics of spacetime. We formulate an equation which tells
in which way an accelerating, spacelike two-surface of spacetime interacts with
the thermal radiation flowing through that surface. In the low temperature
limit, where most quantum black holes constituting spacetime are assumed to lie
in the ground state, our equation implies, among other things, the Hawking and
the Unruh effects, as well as Einstein's field equation with a vanishing
cosmological constant for general matter fields. We also consider the high
temperature limit, where the microscopic black holes are assumed to lie in
highly excited states. In this limit our model implies, among other things,
that black hole entropy depends logarithmically on its area, instead of being
proportional to the area.
