The document discusses visualization challenges and opportunities in training, machines, and the metaverse. It summarizes a UK pilot project that used virtual reality for collective military training. Recognition issues and communication challenges in virtual environments are explored. The rise of the metaverse is discussed as the convergence of computing power, networking, storage, and augmented/virtual reality enabling persistent virtual worlds. Some contemporary developments moving toward a metaverse like Microsoft Mesh, Nvidia Omniverse, and gaming platforms are mentioned. Defense implications of the metaverse include exploiting related standards and technologies to provide a unifying vision for future modeling and simulation.