In answer to Jonathan West: Because relativistic mass increase is inertial,
not gravitational, no matter how much it was accelerated a particle could
never become a black hole. No increase in gravitational field ever has
been or ever could be detected in an accelerated particle. This means that
when such a particle has acquired relativistic mass increase equivalent
to the rest mass of a mountain, it would have the inertia of a mountain
but not a mountain’s gravitational field.
Michael Walsley Hereford
