CONTENTS INTRODUCTION Greek Origins 19th Century Revival The Electron Isotopes Wave Character of the Electron Spin The Neutron Transformation of Particles JUST GIVE THE NEWS The Photon Electromagnetic Properties Interactions Mass Spin HOW DO YOU KNOW? Experimental Method Conservation Laws Quantitative Study of Radioactive Nuclei Decay Paradox of the Energy-Momentum Balance Enrico Fermi's Little Neutral One Particle-Antiparticle The Conservation of Leptons The Fall of Parity THERE ARE FOUR OF THEM! Neutrino Catching Cowan-Reines Experiments Conservation of Lepton Number in Neutrino Reactions Hideki Yukawa and the Strong Interactions The Muon and the Conservation Laws TWINKLE, TWINKLE, LITTLE STAR READING LIST Jeremy Bernstein is that unique combination-a physicist and a writer who can write about science for the general public. In his own words, "Theoretical physics gives me joy; writing gives me pleasure." Since 1961 he has been on the staff of The New Yorker, where he has written book reviews, profiles (Arthur Clarke and Stanley Kubrick), and articles on science and mountain climbing. His published works include four collections of his New Yorker articles. In 1964 he was awarded the Westinghouse Prize for Science Writing, he was later awarded the 1970 American Institute of Physics-U. S. Steel Foundation Science Writing Award in Physics and Astronomy for The Elusive Neutrino. The award was made for "noteworthy writing about physics and astronomy in the media of mass communications." Dr. Bernstein received his B.A., M.A., and Ph.D. degrees from Harvard University. He has been research associate at the Harvard Cyclotron Laboratory and the Institute for Advanced Study at Princeton. On aNational Science Foundation Post-Doctoral Fellowship, he traveled to Paris, Vienna, and Geneva, and has also worked as a physicist at the Brookhaven National Laboratory and the Los Alamos Scientific Laboratory. Dr. Bernstein is now professor of physics at the Stevens Insti