P-Branes Challenge Pea Brains in Survey of Physics Frontier 2005-09-06 02:02 (New York) (Book review. Jeffrey Tannenbaum is a reporter for Bloomberg News. The opinions expressed are his own.) By Jeffrey Tannenbaum Sept. 6 (Bloomberg) -- An unintentionally funny footnote reveals the earnestness of author Lisa Randall as she explains physicists' latest theories of particles and cosmology. The comment, found on page 201 of ``Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions'' (Ecco, 500 pages, $27.95), aims to ensure that Randall hasn't flummoxed anybody by mentioning an Oreo. That's ``a cookie consisting of a sandwich of two round wafers with `creme' in between,'' Randall clarifies.* Naturally, Randall, 43, a professor of theoretical physics at Harvard University in Cambridge, Massachusetts, is diligent in expounding on the ``Higgs mechanism,'' ``gauge bosons'' and dozens of other terms needed to brush up on atomic particles as a prelude to grasping why the universe may contain invisible sectors. She opens a window on the cerebral world of scientists who are trying to uncover the physical world's remaining secrets. Her book is an excellent refresher course on Albert Einstein's theories of special and general relativity, the quantum mechanics of Max Planck, and Werner Heisenberg's uncertainty principle -- and that's just for starters. Randall recaps decades of developments since Einstein and his peers left the scene, covering theories of ``supersymmetry'' and ``branes'' including one whimsically called the ``p-brane,'' a theoretical object that extends infinitely far in only some directions. Tough Reading ``Warped Passages'' reads at times like a textbook, and the author helpfully suggests that readers may wish to skip certain sections that don't cover essential ground. The prose comes alive when she ponders, say, the Higgs mechanism, named for Scottish physicist Peter Higgs of Edinburgh University. He and others tried to salvage the so-called Standard Model of fundamental particles such as electrons and quarks and how they interact. Randall spells out how the model falls short, why the Higgs insights help, and why the updated theories still have defects. ``Supersymmetry'' -- still unproved -- is a new stab at resolving the contradictions to account, for instance, for the surprising weakness of gravity. (``A tiny magnet can lift a paper clip, even though all the mass of the Earth is pulling it in the opposite direction,'' Randall notes.) This theory says there must be still-undiscovered heavier particles to pair with known ones; hence the need to find so-called stop squarks, new partners for top quarks. Hadrons, Gluinos, Squarks Readers of ``Warped Passages'' will come to acquire a rich vocabulary and to appreciate why Einstein's successors are eagerly awaiting the 2007 startup of the Large Hadron Collider, the world's largest particle accelerator, at the European Organization for Nuclear Research, in Switzerland. Hadrons are strongly interacting particles made from quarks. High-energy colliders can produce particles up to a certain mass, so a larger machine may yield bigger particles not seen before. Physicists may use the Large Hadron Collider to verify the existence -- under the right conditions -- of gluinos, squarks, sleptons, and winos (``pronounced `weenos,' not like Bowery bums,'' Randall writes). These and other envisioned components are necessary to complete a bulletproof account of how the world works. A Mystery Still, no theory that stops with particles may prove sufficient to explain the nature of the physical world, beginning with the Big Bang that scientists believe created the universe. Randall also discusses ``string'' theory and ``superstring'' --attempts to solve puzzles left behind by general relativity and quantum mechanics. ``At tiny distances, quantum mechanics and gravity cry out for a more fundamental theory,'' Randall writes. One candidate, string theory, posits that the most basic indivisible objects are vibrating loops of energy. Everything else, including electrons and quarks, consists of oscillations by the strings. But the theory isn't able to explain ``why the universe's vacuum energy is as small as we know it must be,'' the author writes. The most mind-bending section concerns branes, which can occupy multiple dimensions. Branes and ``braneworlds'' have stood at the forefront of string theory for a decade. One idea: Known particles -- including those of our bodies -- may be trapped by a brane with four dimensions (time included) that is part of a universe with one or more extra dimensions. Warped World Randall explores a warped five-dimensional world ``that could help to explain the vast range of masses that are relevant to particle physics'' but are the bane of other theories. Warped extra dimensions can be invisible, she says, drawing on pioneering research she performed with Raman Sundrum, now a professor at Johns Hopkins University in Baltimore. ``We could be living in an isolated pocket of space that appears to be four-dimensional,'' she writes, while conceding that the notion of ``dimension'' may be fuzzy enough to require more work. So hold on to your wallets: Randall warns that ``it's probably too soon to invest in property in other dimensions.'' --Editors: Hoelterhoff, Schatz, West. Story illustration: To learn more about ``Warped Passages,'' see http://www.harpercollins.com. To learn more about Lisa Randall, see http://www.physics.harvard.edu/randall.htm. *I'm not quite that earnest. The British copy editor wanted to remove the cookie reference altogether since English people don't know what Oreo cookies are. I compromised and inserted a footnote. He's right about the English not knowing about Oreo cookies--the footnote initially came back with an accent on creme!