HENRY FRISCH is hot on the trail of an elusive form of matter.
Physicists generally are convinced that it exists. They need it
to complete the set of elementary particles that current theory
requires. Yet they have never seen it in spite of many years of
Now the University of Chicago physicist says he is "willing to
bet even odds on $1,000" that it will turn up in the data his group
plans to collect next spring at the nearby Fermi National
Accelerator Laboratory (Fermilab).
Dr. Frisch's confidence, such as it is, also is a measure of the
progress physicists have made in understanding the basic structure
of matter and the challenge they believe they now face.
Using their current best concept - the so-called Standard Model
- particle physicists describe all the matter they know in terms of
a limited set of particles and the forces acting between them.
There are six particles of the type called quarks and six of the
type called leptons.
The quarks are grouped into three families of two quarks each -
the up and down quark family, the charm and strange quark family,
and the top and bottom quark family.
Each of these families also contains two leptons - an
electron-like particle and its associated neutrino. Neutrinos are
shadowy particles with little, if any, mass. They interact so
weakly with other particles that they zip through a solid mass like
Earth as though it weren't there. They emerge from particle
interactions mainly as entities that carry some of the associated
Besides gravity, which the Standard Model scheme doesn't cover,
these particles interact through three forces - the electromagnetic
force, the weak force involved in some forms of radioactivity, and
the strong force that binds quarks together.
For example, the strong force binds up and down quarks in
various combinations to form protons and neutrons and some other
particles. The protons and neutrons join to form atomic nuclei. The
electromagnetic force, in turn, forms the chemical elements by
binding different nuclei to ordinary electrons, which are part of
the up and down quark family.
Other quark families form more exotic particles seen only
fleetingly when particles collide in high-energy
Special force-carrying particles mediate these interactions.
Gluons carry the strong force. Photons (particles of light) carry
the electromagnetic force. And particles known by the letters W and
Z carry the weak force. Actually, physicists now know that these
latter two forces are just different aspects of a single underlying
force they call the electro-weak interaction. …