This paper gives an overview of a newly discovered method to simulate interconnects and integrated passive elements. The method has its origin in the developments that were realized in differential geometry that led to the insight that electromagnetism has a geometrical structure that goes beyond the simple analogy with hydrodynamical flows. It is argued that one also needs to exploit ideas that were developed for generalized gauge theories. Ghost fields play an important role in this context. Starting from these new insights, a new simulation tool was constructed, that allows the simulation of the Maxwell equations together with the constitutive laws, such as Ohm's law and/or the drift-diffusion equations. As a consequence a unified approach is realized for solving the electromagnetic field and semiconductor equations. (c) 2005 Elsevier Ltd. All rights reserved.