Jeff Foust in The Space Review:
Last week came word of something of a setback in the quest for understanding the nature of dark matter, the mysterious substance that is far more abundant in the universe than the ordinary matter that makes up stars, planets, and people. An instrument on NASA’s Fermi spacecraft failed to detect a surge of electrons and positrons at high energies that was seen last year by a balloon-borne instrument. That peak had been thought to be the signature of the annihilation of weakly interacting massive particles (better known by their acronym, which is, yes, WIMP), a theoretical particle posited by some astrophysicists as the composition of dark matter. But with Fermi providing more and better data than the earlier experiment, that discovery may have been only a false alarm.
If things like WIMPs and dark matter (or its even more mysterious acquaintance, dark energy) leave your scratching your head, a good place to turn is Evalyn Gates’ new book, Einstein’s Telescope. Gates, the assistant director of the Kavli Institute for Cosmological Physics at the University of Chicago, provides an overview of what we know—and what we don’t—about dark energy, dark matter, and related mysteries of the universe that’s accessible to those who can’t tell the difference between a WIMP and a MACHO—in the astronomical sense, at least.