The Capital Trap of Urban Density: Toward a New Equilibrium in National Production

This paper investigates the structural causes of capital stagnation and regional collapse in Japan’s modern economy, framing urban population density as a gravitational gauge field that traps human, financial, and material resources. The capital inflow into cities becomes one-way and irreversible, forming an economic “black hole” that undermines the nation's systemic stability. The author introduces a geometric-fiscal interpretation using the relation: d(capital)/dx = -d(capital)/dt This expresses capital’s spatial convergence and temporal depletion. The imbalance of capital flow velocity—Δv ≠ 0—manifests as massive dormant funds (over ¥300 trillion) in urban financial institutions and paralyzing labor shortages in essential rural industries. The study critiques neoliberal infrastructure privatization as a key accelerator of regional abandonment and urban overdependence. Once rural regions lose the ability to supply cities, the urban system faces inevitable collapse. As a solution, the paper proposes a comprehensive recovery model: adopting PBMT (Public Balance Monetary Theory), establishing a production-based reward fund, promoting non-speculative primary industries, and restoring capital and population decentralization. The ultimate goal is to achieve Δv = 0—a balanced, circulatory national economy. Author Tetsuo Konno(今野哲夫)https://orcid.org/0009-0002-1842-7865