Enormous Fluid Antenna Systems (E-FAS): Rethinking the Future of Wireless Communications

For decades, wireless communication embodied the promise of ubiquitous connectivity---radio waves weaving invisible paths through obstacles to connect distant nodes. However, as next-generation mobile systems increasingly shift toward higher frequency bands to meet escalating data demands, the wireless channel has become more fragile---exhibiting reduced penetration, limited coverage, and heightened sensitivity to environmental conditions. Concurrently, with the majority of mobile services now taking place indoors, it is both timely and imperative to rethink how wireless connectivity is delivered to achieve greater performance and efficiency. In this article, we address this challenge by reviewing a novel concept that reimagines intelligent surfaces---not merely as passive smart reflectors, as in conventional reconfigurable intelligent surfaces (RIS)---but as multifunctional electromagnetic (EM) interfaces capable of both signal routing and emission. This expanded functionality introduces a fundamentally new degree of control over signal propagation. We define the concept of the enormous fluid antenna system (E-FAS), which conceptualizes a distributed ensemble of intelligent surfaces as a single, massive, reconfigurable antenna embedded within the environment itself. E-FAS enables signal propagation to predominantly occur along surfaces, thereby enhancing energy efficiency, reducing interference, and ensuring reliable service delivery. Crucially, it guarantees that users are served with a line-of-sight (LoS) path---either through direct contact with the surface itself or via short-range wireless links radiated from nearby surface elements. We further explore the potential of deploying E-FAS on building exteriors to guide radio waves around structural obstructions, enabling the restoration of LoS connectivity for users located behind buildings. This vision positions E-FAS as a transformative architectural paradigm for future wireless systems.