philosophy of mathematics suited well the ‘‘general emphasisin later nineteenth-century mathematics on revisiting foundationalquestions’’ (p. 61). Pure geometry as it emerged from Frege, Paschand Hilbert, provided a diagram-free, purely sentential notion ofproof, which has lasted unto our own day.In the second, and greater, part of the book, Greaves traces outthe interre...

The status of the search for pentaquark baryon states is reviewed in light of new results from the first two dedicated experiments from CLAS at Jefferson Lab and of new analyses from several labs on the Θ + (1540). Evidence for and against the heavier pentaquark states, the Ξ(1862) and the Θ 0 c (3100) observed at CERN and at HERA, respectively, are also discussed. I conclude that the evidence ...

1492 Journal of Chemical Education • Vol. 77 No. 11 November 2000 • JChemEd.chem.wisc.edu The purpose of this article is to comment on the pedagogical ramifications of the recently claimed observation of d orbitals and the way in which these results were first announced and subsequently reported (1–6 ). Atomic orbitals—their use in writing electronic configurations and as a means of rationalizi...

Over the last few years, several close orbiting (∼ 0.05 AU) large mass planets (M ∼ M Jupiter) of nearby stars have been discovered. Their existence has been inferred from tiny doppler shifts in the light from the star. We suggest that these planets may be made of mirror matter. We also suggest that some stars such as our sun may also have a similar amount of mirror matter, which has escaped de...

Observations by the MACHO collaboration suggest that a significant proportion of the galactic halo dark matter is in the form of compact objects with typical masses M ∼ 0.5M ⊙. One of the current mysteries is the nature and origin of these objects. We suggest that these objects are stars composed of mirror matter. This interpretation provides a plausible explanation for the inferred masses and ...

Recently there is a suggestion about the star RXJ1856.5−3754, being a possible candidate for quark star. While from the estimates of the radiation radius, given by the authors, it does not seem to fit with any of the known models for such stars, the mass radius diagram admits the possibility of this being a quark star of mass M ⊙ < M < 1.4M ⊙ , provided the radius mentioned is the actual radius...