Virtual representation A fundamental challenge for digital twins is the vast range of spatial and temporal scales that the virtual representation may need to address. In many applications, the scale at which computations are feasible falls short in resolving key phenomena and does not achieve the fidelity needed to support decisions. Investments in both computing resources and mathematical/algorithmic advances are necessary elements for closing the gap between what can be simulated and what is needed to achieve trustworthy digital twin. Particular areas of importance include multiscale modeling, hybrid modeling