### Casimir Energies in Light of Quantum Field Theory

**Noah Graham**

*Bicentennial Hall*

Middlebury College

Middlebury, VT 05753

Traditional Casimir calculations are done by imposing perfect
boundary conditions on surfaces. Of course, no real material creates
a boundary condition at arbitrarily high energies; there is always
an effective cutoff above which the material appears transparent.
Although this idealization is justified in many useful problems,
such the Casimir force between rigid bodies, there are situations
where it can be hazardous, such as Casimir stress problems or
general relativity applications. We present an efficient

calculational program in which we study the Casimir energy of
a background potential that approximates a Dirichlet boundary
condition. We conclude that the stress on the Dirichlet sphere
depends on the details of the material that implements the cutoff,
and thus is infinite in the limit of an

ideal boundary. This approach might also shed new light on the
classic Boyer results for a conducting sphere.