We construct a vector field E from the real and imaginary parts of an entire function xi(z) which arises in the quantum statistical mechanics of relativistic gases when the spatial dimension d is analytically continued into the complex z plane. This function is built from the Gamma and Riemann zeta functions and is known to satisfy the functional identity xi(z) = xi(1 - z). E satisfies the conditions for a static electric field. The structure of E in the critical strip is determined by its behavior near the Riemann zeros on the critical line R(z) = 1/2, where each zero can be assigned circle plus or circle minus parity, or vorticity, of a related pseudo-magnetic field. Using these properties, we show that a hypothetical Riemann zero that is off the critical line leads to a frustration of this "electric" field. We formulate this frustration more precisely in terms of the potential Phi satisfying E = -del Phi and construct Phi explicitly. The main outcome of our analysis is a formula for the nth zero on the critical line for large n expressed as the solution of a simple transcendental equation. Riemann's counting formula for the number of zeros on the entire critical strip can be derived from this formula. Our result is much stronger than Riemann's counting formula, since it provides an estimate of the nth zero along the critical line. This provides a simple way to estimate very high zeros to very good accuracy, and we estimate the 10(106) -th one.