  I discuss three mutually-supportive notions or assumptions regarding jets and
accretion. The first is magnetocentrifugal acceleration (MCA), the
overwhelmingly favored mechanism for the production of jets in most steady
accreting systems. The second is the zero-torque inner boundary condition. The
third is that effective viscous dissipation is like real dissipation, leading
directly to heating. All three assumptions fit nicely together in a manner that
is simple, persuasive, and mutually-consistent. All, I argue, are incorrect.
For concreteness I focus on protostars. Magnetohydrodynamic (MHD) turbulence in
accretion is not a sink of energy, but a reservoir, capable of doing mechanical
work directly and therefore efficiently, rather than solely through ohmic
("viscous") heating. Advection of turbulence energy reduces the effective
radiative efficiency, and may help solve the missing boundary-layer emission
problem. The angular momentum problem, whereby accretion spins up a protostar
to breakup, is resolved by allowing direct viscous coupling to the protostar,
permitting substantially greater energy to be deposited into the accretion flow
than otherwise possible. This goes not into heat, but into a turbulent,
tangled, buoyant toroidal magnetic field. I argue that there is neither an
angular momentum problem nor an efficiency problem that MCA is needed to solve.
Moreover, the turbulent magnetic field has ample ability not just to collimate
but to accelerate gas, first radially inwards through tension forces and then
vertically through pressure forces, without any MCA mechanism. I suggest then
that jets, particularly the most powerful and well-collimated protostellar
jets, are not magnetocentrifugally driven.
