IT’S A comforting thought in these times of change: fashions come and go,
reputations rise and fall, but diamonds—or, at least, the atoms from which
they are built—are forever.
Or are they? Theoretical physicists have been questioning the supposed
permanence of matter for years. They already know that neutrons aren’t stable:
once plucked from the hearts of atoms they decay into protons, electrons and
antineutrinos in a little over 10 minutes. Protons are certainly more stable
than that. But for years the suspicion has been growing that protons might also
be doomed.
Although neutrons are unstable, when they decay they do at least have the
decency to keep things in the family and produce some protons to compensate. But
many theorists now believe that the proton can pull off an altogether more
radical trick, and decay into particles bearing no obvious relationship to their
progenitor, marking the end of matter as we know it. Their conviction is based
on attempts to forge so-called grand unified theories (GUTs) of the forces that
bind together the subatomic world: the weak force, which causes many subatomic
particles to decay; the strong force, which binds nuclei together; and the
electromagnetic force, which holds atoms together. Even in their most primitive
form, GUTs point to an astonishing new feature of our Universe. They predict
that every proton—whether bound into atoms or not—should be slowly
but ineluctably disintegrating. Or, to put it more poetically, diamonds may not
be forever after all.
Yet theorists are now admitting that there’s something pretty bizarre about
the prediction. For despite their very best efforts to catch…
