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.

GENERAL RELATIVITY PATERNITY SUIT SETTLED. Albert Einstein customarily gets credit for the modern theory of gravity. But a minor, long-running dispute over priority has lingered until now. Einstein's crucial relativity paper was submitted on 25 November 1915 and published on 2 December. But a paper by Einstein's colleague David Hilbert, published on 31 March 1916 with almost identical equations, had originally been submitted on 20 November 1915, five days before Einstein's submission. Some concluded that Einstein had pilfered his equations from Hilbert, but a new study shows that the borrowing was in the other direction. Newly discovered proofs of Hilbert's paper show that the important equations were missing from the 20 November version and had been added by Hilbert in December, presumably after Hilbert had seen them in Einstein's manuscript; the two men were in close contact during these critical weeks. (Science, 14 November 1997.)

HOW DOES THE SUN'S CORONA, at a temperature of millions of K, draw energy from the sun, whose surface is a much cooler 6000 K? New measurements by the SOHO satellite reveal the presence of tens of thousands of magnetic dipoles at work in the sun's surface layer. The SOHO researchers surmise that the magnetic-field loops rising up from the surface are so dense that they clash, creating "short circuits" in which powerful electrical currents can flow, delivering energy to the corona above. (Science News, 8 November.)

SPARE TIME. Descartes gave us co-ordinate geometry, with its three spatial dimensions. Einstein put time on an equivalent footing, creating 4-dimensional spacetime. String theory added six more spatial dimensions, and M theory added yet one more for a total of eleven (see Update 329). Now Cumrun Vafa of Harvard has added still another----an extra element of time---to make the existing theories more compatible with each other. Because of possible side effects, such as faster-than-light travel or questionable causality (time would not be measured sequentially along an axis but would spread out into a plane), Vafa's "F Theory" has not found many adherents yet. (New Scientist, 1 November.)