# Industrial Metaverse: A Comprehensive Review, Environmental Impact, and Challenges
## 3 Industrial Metavere's Architecture, Roadmap, and Core Technologies Overview
### Digital Twins
Because of its predictive nature and ability to access its physical counterpart remotely, the DT can lessen the likelihood of dangerous malfunctions and mishaps. DTs also have the advantage of waste reduction as the simulation and testing of products are performed virtually. Before a product is manufactured, prototype designs can be virtually tested in many conditions to ensure that the final design is good. This reduces development costs and time to market, in addition to preventing material waste. Documentation and communication comprise another advantage, where data that are dispersed throughout several software programs, databases, and hard copies must be synchronized to establish a data dictionary (DT), which makes it easier to retrieve and maintain the data in one location. By improving the comprehension of system responses, the DT makes it possible to record and convey the behavior and workings of the physical twin. The main advantage is realized in training. The DT can be used to create safety training programs that are more effective and instructive than those that follow conventional methods. Operators can be taught to utilize a DT to reduce the risks before working on a high-risk location or hazardous machinery. By exposing and teaching them about various processes or scenarios, they will become more comfortable handling the same problems in person. For instance, the DT can be used to train new staff in the high-risk field of mining on how to operate machinery and handle emergencies. Lastly, the DT can be a very useful tool in bridging the knowledge gap between seasoned and new employees. High fidelity, dynamic, self-evolving, recognizable, multi-physical, multi-scale, and multidisciplinary are just a few of the attributes that define DTs [40; 41]. Firstly, high fidelity means a DT can replicate every detail of its physical twin thanks to an incredibly lifelike dig ital model. Computer models with extremely high fidelity are thought to be the foundation of the DT. When DT simulation and prediction tools are presented with a set of alternative actions or scenarios, this level of detail makes them more reliable. Moreover, the DT is also dynamic, meaning it changes with time in tandem with changes in the physical twin. This is achieved by a continuous exchange of data between the physical and virtual worlds. The concerned data can be either dynamic, wherein they vary with time, or static. A DT is also characterized as self-evolving, meaning the changes during its life cycle are in tandem with its physical counterpart. A closed feedback loop is produced when modifications are made to either the physical or digital twin because they are mirrored in each other. Because a DT uses its physical twin's data to gather information in real-time, it can adapt and self-optimize, evolving throughout its lifetime alongside its physical counterpart. Furthermore, the data and information about a product change as it progresses through its lifecycle, and this also applies to the models--which can include functional, manufacturing, usage, and 3D geometric models, among others. The development of such models for DTs enables a DT to be uniquely distinguished from its physical twin or vice versa, anywhere in the world and throughout its life cycle. In digital twin technology, the macroscopic geometric aspects of the physical twin, including the size, form, and tolerance, as well as the microscopic features, like surface roughness, serve as the basis for the virtual model. Since a DT is based on both the physical and material properties of the physical twin--such as stress analysis models, fatigue damage models, and thermodynamic models--as well as the previously mentioned geometric properties, it is also multiphysical. The material properties of the physical twin include stiffness, strength, hardness, and fatigue strength. Lastly, the fact that Industry 4.0 is centered on multiple disciplines makes DTs multidisciplinary.