We describe a time-domain passivity control methodology that uses programmable eddy current viscous dampers to prevent a user from extracting energy from a haptic interface. A passivity observer monitors the energy flow of the virtual environment, and damping hardware is used to remove any energy contributions from the virtual environment that violate passivity constraints. Experiments illustrate that the programmable physical damper method improves the performance of a haptic device that has minimal inherent dissipation.