Dark Matter and Physical Constant Evolution from Five-Dimensional Hydrodynamic Spacetime

We extend the five-dimensional hydrodynamic spacetime framework developed in our previous work to address two fundamental problems in modern physics: the nature of dark matter and the evolution of physical constants. We demonstrate that the speed of light varies systematically across different w-layers, leading to electromagnetic confinement within each layer while gravity couples universally. This naturally explains dark matter as ordinary matter residing in parallel w-layers, gravitationally interacting but electromagnetically invisible. We further show that w₀, previously treated as a fundamental constant, is dynamically determined and decreases over cosmic time due to gravitational effects, with black holes playing a dominant role. This decrease predicts observable evolution in the fine structure constant α(z), consistent with recent observations by Webb et al. The framework provides specific, testable predictions for dark matter distribution, physical constant evolution, and black hole physics.