  It is well known that the cosmological constant term in the Einstein field
equations can be interpreted as a stress tensor for dark energy. This stress
tensor is formally analogous to an elastic constitutive equation in continuum
mechanics. As a result, the cosmological constant leads to a "shear modulus"
and "bulk modulus" affecting all gravitational fields in the universe. The form
of the constitutive equation is also analogous to the London constitutive
equation for a superconductor. Treating dark energy as a type of
superconducting medium for gravitational waves leads to a Yukawa-like
gravitational potential and a massive graviton within standard General
Relativity. We discuss a number of resulting phenomenological aspects such as a
screening length scale that can also be used to describe the effects generally
attributed to dark matter. In addition, we find a gravitational wave plasma
frequency, index of refraction, and impedance. The expansion of the universe is
interpreted as a Meissner-like effect as dark energy causes an outward
"expulsion" of space-time similar to a superconductor expelling a magnetic
field. The fundamental cause of these effects is interpreted as a type of
spontaneous symmetry breaking of a scalar field. There is an associated
chemical potential, critical temperature, and an Unruh-Hawking effect
associated with the formulation.
