radial limits of subharmonic functions Let $u$ be a non-negative subharmonic function on the unit ball in $\Bbb{R}^n$. Does it follow that there exists a radial limit (including limits of infinity or negative infinity) along almost every line through the origin.
 A: The answer is no, even in dimension $2$. Consider a simply connected region $D$ in the unit disc which approached the boundary with infinite spiraling (that is such region where a continuous branch of the $\arg z$ exists and tends to $+\infty$ as $|z|\to 1$ in the region).
Let $u=Re f$, where $f$ is a conformal map of $D$ onto the right half-plane, so that every
boundary point of $D$ inside the unit disc goes to the imaginary axis. 
Alternatively, $u$ is the positive harmonic function in $D$ zero on the part of the boundary of $D$ which is inside of the unit disc.
Extend this $u$ to the rest of the disc by setting it to $0$. The resulting subharmonic
function has no radial limit on any radius (upper limit is $+\infty$ and lower is $0$).
Similar examples exist in any dimension. Function $u$ exists in any dimension by Martin's
construction, for example: $$u(z)=\lim_{|\zeta|\to 1} g(z,\zeta)/g(z_0,\zeta),$$
where $g$ is the Green function of $D$, and $|\zeta|\to 1$ in $D$. 
Just take $D$ which intersects every radius nicely.
