HIGGS FACTORIES, accelerators devoted to high-precision studies of the Higgs boson, will probably be lepton colliders rather than proton machines since beams of leptons (electrons or their heavier cousins, muons) transport energy in pointlike parcels, whereas protons are messy composite objects made of quarks and gluons. Physicists are eager to know the Higgs intimately since, according to the standard model, it is the Higgs that confers mass on most of the known particles. One prospective Higgs factory is the Next Linear Collider (NLC), at which electrons would be fired down a straight barrel into oncoming positrons; the straight-forward approach is used to avoid the ruinous loss of energy through synchrotron radiation suffered by electrons in tracing out arcing trajectories in a circular collider. To produce a TeV of collision energy, however, the NLC might have to be tens of km in length. (Physics Today, November.) Muons are much less vulnerable to synchrotron energy loss and parts of a circular acceleration scheme could be retained, albeit at the expense of having to make the unstable muons in a separate step. Even then, argues Robert Palmer of Brookhaven, for the same collision energy a muon collider could be built for one-sixth the cost of an electron linac. Palmer, who acknowledged that muon technology has not been tried out, made his claim earlier this month at the New Horizons in Science meeting in Roanoke, Virginia.