Thursday, October 14, 1999

Femtosecond Spectroscopy and Top Quark

The Royal Swedish Academy of Sciences has awarded the 1999 Nobel Prize in Chemistry to Professor Ahmed H. Zewail, California Institute of Technology, Pasadena, USA, for showing that it is possible with rapid laser technique to see how atoms in a molecule move during a chemical reaction.

The Academy's citation [1] says that the Egyptian scientist Zewail won the prize "for his studies of the transition states of chemical reactions using femtosecond spectroscopy." I am glad that "femto" used in the name of my essays has become famous also among nonscientists by Zewail's winning of the prize.

The 1999 Nobel Prize in Physics was won jointly by Professor Gerardus 't Hooft, University of Utrecht, Utrecht, the Netherlands, and Professor Emeritus Martinus J.G. Veltman, Bilthoven, the Netherlands "for elucidating the quantum structure of electroweak interactions in physics."

One particular quantity obtained by the calculation method of 't Hooft and Veltman is the mass of the top quark [2] (quarks are the constituents of the proton, the neutron and the like, which were once considered to be elementary particles). This quark was observed directly for the first time in 1995 at the Fermilab in the USA [3], but its mass had been predicted several years earlier. Thus the correctness of their theory was established. It is to be noted that the work related to the existence of the top quark was initiated by the Japanese physicists M. Kobayashi and K. Maskawa [4].

Besides the predictions already confirmed, the Academy's press release [2] mentions also about an as yet unfound particle termed the Higgs particle, which is an important ingredient in the theory 't Hooft and Veltman have developed. The demonstration of this particle is expected to come around 2005 after the completion of an accelerator called the Large Hadron Collider (LHC) at the European high-energy physics center CERN.

Veltman is quoted as telling Dutch radio news, "The social benefit of my theory is absolutely nil -- you won't eat any more or less as a result." (CNN website news, 12 Oct, 1999). However, the understanding of one of the deepest levels of nature is very probable to open up new technological possibilities in the future.

A good explanation for the layperson of the work done by 't Hooft and Veltman is found in a book by John Gribbin [5]. See also Physics New Update Nos. 452-1 and 452-2 for this year's Nobel Prizes in Physics and Chemistry [6, 7].
  1. Nobel Foundation, "The 1999 Nobel Prize in Chemistry"
  2. Nobel Foundation, "The 1999 Nobel Prize in Physics"
  3. T. M. Liss and P. L. Tipton, "The Discovery of the Top Quark" Sci. Amer. (September issue, 1997).
  4. G. 't Hooft, "In Search of the Ultimate Building Blocks" (Cambridge University Press, 1997).
  5. J. Gribbin, "The Search for Superstrings, Symmetry, and the Theory of Everything" (Little, Brown, 1998).
  6. The 1999 Nobel Prize for Physics, Physics News Update No. 452-1 (1999, American Institute of Physics)
  7. The 1999 Nobel Prize in Chemistry, Physics News Update No. 452-2 (1999, American Institute of Physics)

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