Knowing a little something on this subject (I like to read popularizations of theoretical physics) I can tell you that physicists would love to make it simple (as the Fermi quote in a post below indicates). They want a Grand Unified Theory (GUT). Nature has its own ideas, though.
Many things are based on energy conservation and symmetry - nature loves symmetry. Nature makes and breaks symmetry in all kinds of places (complexity theory delves into this extensively). Subatomic theory predicted that, for certain high-energy collisions to make sense, there had to be very short-lived, supermassive particles (many of the particles mentioned have lives so short that a computer cycle on an Itanium 2 is an eternity). That doesn't make them "theoretical" though - they are real.
(Aside: the sqrt -1 is not "unreal" - it is "imaginary" by naming convention but it is as real as a rock. Without it, there would be no radio, computers, TV's or even AC current.)
Bosons have been proven. Recently, all 6 quarks (strange, charm, colored etc.) were proven. They had 5 and were looking for the 6th to fulfill theoretical/symmetrical demands. It took some serious high-energy physics to find it, but they did. Many of these so-called "theoretical" particles are not "unreal" but they may be "virtual". The problem is that virtual particles are often counterparts of "visible/tangible" particles, with whom they combine in tiny multiples of Planck times to form other particles. This makes them extremely difficult to "prove" but are absolutely necessary, otherwise we have to assume that energy is created or destroyed in some reactions (this is the way the neutrino was first theorized). Since conservation of energy has served so long and so well, scientists are quite loathe to dispense with it until there are no other avenues of investigation. And we are a long, long way from having no other avenues of investigation.
Hope that helps.
Cheers,
Bryan
You are only wretched and unworthy if you choose to be.
