The value of Digital Twins can only be realized if Digital Twins and their virtual environment contain the same data and resulting information as their corresponding Physical Twins and real-world environment. This means that the need for more extensive, faster, and richer sensing of the physical world will dramatically increase as valuable use cases proliferate. In addition, we will evolve from working in physical or virtual environments to integrating and working simultaneously in both environments. Dr. Grieves discusses his views on the opportunities and issues of this evolution.