To make a discovery is not necessarily the same as to understand a discovery. Not only Planck but also other physicists were initially at a loss as t… - Abraham Pais

To make a discovery is not necessarily the same as to understand a discovery.

Deliberately or not, every author is of course present in every book he or she writes — even in a scientific text.

The ultimate unification of weak and electromagnetic interactions has probably not yet been achieved, but a solid beach-head appears to have been established in terms of local non-Abelian gauge theories with spontaneous symmetry breakdown. As a result, it is now widely believed that weak interactions are mediated by massive vector mesons. Current expectations are that such mesons will be observed within the decade. It is widely believed that strong interactions are also mediated by local non-Abelian gauge fields. Their symmetry is supposed to be unbroken so that the corresponding vector mesons are massless. The dynamics of these 'non-Abelian photons' are supposed to prohibit their creation as single free particles. The technical exploration of this theory is in its early stages.

Progress leads to confusion leads to progress and on and on without respite. Every one of the many major advances … created sooner or later, more often sooner, new problems. These confusions, never twice the same, are not to be deplored. Rather, those who participate experience them as a privilege.