  The absence of other viable momentum sources for collimated flows leads to
the likelihood that magnetic fields play a fundamental role in jet launch
and/or collimation in astrophysical jets. To best understand the physics of
jets, it is useful to distinguish between the launch region where the jet is
accelerated and the larger scales where the jet propagates as a collimated
structure. Observations presently resolve jet propagation, but not the launch
region. Simulations typically probe the launch and propagation regions
separately, but not both together. Here, I identify some of the physics of jet
launch vs. propagation and what laboratory jet experiments to date have probed.
Reproducing an astrophysical jet in the lab is unrealistic, so maximizing the
benefit of the experiments requires clarifying the astrophysical connection.
