Many people have been quick to point out that things don't ever seem to get any better. First we had the elements to explain, then nuclei; there was a pleasant time when the world consisted only of photons, electrons, neutrinos, protons, neutrons and pions - but we had to spoil it by looking more closely and making higher energy accelerators. Then the ``hadron zoo'' collapsed to three quarks and the gluon, and things were looking up again; but now there are six quarks (one of which, the t, still hasn't been completely unambiguously observed, or at least some people don't think it has) and as many leptons, and at least 4 different intermediaries.
Is this just another round of simplification followed by more complexity
at a deeper level? Possibly. It has been proposed that quarks and
leptons may themselves be composite particles, and further that
every particle must have a `` supersymmetric'' (or SUSY)
partner of the opposite sort of statistics
- for each fermion there must be a supersymmetric boson, and
vice versa.
There is no shortage of new theories, nor is arrogance in
short supply - one model called `` superstrings''
has been touted as a TOE (Theory Of Everything) by the
New York Times (which loves to get into these
debates).
There is, however, a small practical problem.
All the Grand Unification Theories (or GUTs) predict wonderful simplifications at enormously high energies on the scale of the first moments of the Big Bang - Cosmologists work closely with particle physicists these days - but such energies cannot be achieved on Earth. The current forefront projects, like the cancelled SSC (Superconducting SuperCollider) in the USA or the not-yet-cancelled LHC (Large Hadron Collider) at CERN in Europe, cost billions of dollars and take up thousands of square kilometers of space. Particle physicists hope they will find the next ``round'' of new structure at these energies, but there are plausible theories that predict the next ``interesting'' break will come at stupendous energies far beyond those of either LHC or the SSC. If this is true, although experimental particle physics may not end forever [we may one day build a synchrotron in orbit about the Sun], the present socioeconomic structures will not be able to support further pushes toward higher energy. Particle physics will then be forced to go back and take longer, harder looks at the particles already observed, and the `` Excelsior!'' school of particle physics will be at an end.
Still, it's been a great ride!