  In this essay, dedicated to the one hundredth anniversary of Hermann
Minkowski's talk "Space and Time", I argue that physicists should face the
issue of the reality of spacetime and worldtubes of physical objects for two
reasons. First, this issue is not a philosophical question, as some appear to
think, since the kinematical special relativistic effects would be impossible,
as will be demonstrated, if the physical objects involved in these effects did
not exist as four-dimensional worldtubes. Second, taking into account that
worldtubes are real four-dimensional objects provides an unexpected insight
into the origin of inertia, the nature of the force acting on a body supported
in a gravitational field, and possibly even the nature of quantum objects.
