  We study the effects of heavy fields on 4D spacetimes with flat, de Sitter
and anti-de Sitter asymptotics. At low energies, matter generates specific,
calculable higher derivative corrections to the GR action which perturbatively
alter the Schwarzschild-$(A)dS$ family of solutions. The effects of massive
scalars, Dirac spinors and gauge fields are each considered. The six-derivative
operators they produce, such as $\sim R^{3}$ terms, generate the leading
corrections. The induced changes to horizon radii, Hawking temperatures and
entropies are found. Modifications to the energy of large $AdS$ black holes are
derived by imposing the first law. An explicit demonstration of the replica
trick is provided, as it is used to derive black hole and cosmological horizon
entropies. Considering entropy bounds, it's found that scalars and fermions
increase the entropy one can store inside a region bounded by a sphere of fixed
size, but vectors lead to a decrease, oddly. We also demonstrate, however, that
many of the corrections fall below the resolving power of the effective field
theory and are therefore untrustworthy. Defining properties of black holes,
such as the horizon area and Hawking temperature, prove to be remarkably robust
against higher derivative gravitational corrections.
