Edward Witten. Witten is a Fields Medalist and a leading exponent of
string theory. The lecture was attended by many leading scientists, and
there was a question-and-answer period after the lecture. One of the
questions directed at Witten was “Do you really believe that this is the
way things are?” Witten’s answer was unequivocal: “If I didn’t believe it, I
wouldn’t have spent ten years working on it.” That convinced me—at the
time of the lecture. On my way home, it struck me that centuries earlier
Isaac Newton, who had expended ten years working on an explanation for
alchemy, might have answered a question regarding the validity of al-
chemy in the same fashion.
More Posited Particles
There are two major classes of particles that have yet to be detected, but
are nonetheless the subject of investigation. The first class of particles
consists of those that are part of the Standard Model, but have not yet
been detected. The star in this particular firmament is the Higgs parti-
cle, which is the vehicle by which mass is imparted to all nonmassless
particles (photons, the particles of light, are examples of massless parti-
cles). As observed earlier, the Higgs particle seems to remain tantaliz-
ingly out of reach of whatever energy range the current generation of
particle accelerators can deliver, but many physicists feel it’s just a matter
of time before one turns up in the snares that have been set for it.
More interesting, from a mathematical standpoint, are the supersym-
metric particles. These particles are the ephemeral dance partners for the
chorus line of particles making up the Standard Model, and exist in most
of the currently popular variations of string theory. Like Dirac’s antielec-
tron, they emerge as the result of a pairing process in the underlying
mathematics. For Dirac, however, the pairing process resulted from hav-
ing opposite charge. Supersymmetric particles occur from a pairing in-
volving spin—the mass particles of the Standard Model have spin^1 ⁄ 2 ,
their supersymmetric particles have spin 0.
The detection of a Higgs particle, or a supersymmetric one, depends
upon the mass of these particles. All the unobserved particles are heavy
(when measured as a multiple of the mass of the proton); the projected
mass of these particles varies with which theory is being employed. What
does not vary is what is necessary to create them—lots of energy. Einstein’s
great mass-energy equation, Emc^2 , can be compared to the exchange rate
between varying currencies. The atomic bomb, or the energy generated by
thermonuclear fusion in the heart of a star, is the result of converting mass
into energy—a very little mass generates a lot of energy, because that mass
142 How Math Explains the World