5\times 10^{41}\ dyn\ cm^{-2}(10\ m/b_m)^2$.

    2.  (Field equations)+(absence of horizon at throat) $\Rightarrow$ $\tau>\rho c^2$ in throat $\Rightarrow$ traveler moving through throat at very high speed sees negative mass-energy density $\Rightarrow$ violation of weak, strong, and dominant energy conditions in throat. \[9082013q\]

    3.  One might wish to require $\rho \geq 0$ everywhere (static observers see nonnegative mass-energy density), which implies $b'\geq 0$ everywhere. \[9082013r\]

In Ref. [@PhysRevD.56.4745], Hochberg and Visser define a traversable wormhole throat as the two-dimensional hypersurface of minimal area taken in one of the constant-time spatial slices. When the minimal value of the area can be found by extremizing the area, one can show that the trace of the extrinsic curvature $K_{ab}$ of this two-surface vanishes. Besides, its derivative with respect to the normal coordinate $n$ (in Gaussian normal coordinates) is negative when one uses the definition $$K_{ab}=-\frac{1}{2}\frac{\partial g_{ab}}{\partial n}. \label{26062014b}$$

This definition of wormhole encompasses the Morris-Thorne one, which is limited to two asymptotically flat regions that are spherically symmetric.

Wyman’s solution {#1032014a}
================

Wyman’s solution corresponds to the spherically-symmetric solution of the following Einstein’s field equations $$\begin{aligned}
G_{\mu \nu}=-\mu \left( V_{,\mu}V_{,\nu}-\frac{1}{2}g_{\mu \nu}V_{,\lambda}V^{,\lambda} \right),
\\
\Box V=0,\end{aligned}$$ where $V$ is a scalar field and $\mu$ is 