  In this short introductory commentary on the paper (Hessels et al 2006,
Science, 311, 1901) reporting the discovery of the shortest spin period
millisecond pulsar (MSP) Ter5-ad in the globular cluster Terzan 5, I also point
out a new explanation for possible minimum spin periods, P, of MSPs without
requiring gravitational radiation (or other) slow-down torques. If the
accretion of matter required to spinup a MSP also reduces (buries) the neutron
star (NS) magnetic field, B, as commonly believed, an inverse correlation
between neutron star mass, M, and B is expected together with a positive
correlation between P and B. Both are suggested for the 4 MSPs with NS mass
measures reported (Latimer and Prakash 2004, Science, 304, 536) to have <~10%
uncertainties. The correlations imply the Ter5-ad NS has ~2.5 Msun, B ~5 x 10^7
G and thus Pdot ~3 x 10^-21 s/s -- which can be tested when a timing solution
is found. If confirmed, the highest spin frequency NSs do not pulse simply
because their B fields are too low.
