Physicists widely doubt that quantum particles are truly 0D points as represented in Standard Model, which offers "formalism"—mathematical devices whose strokes predict phenomena of interest upon input of data—not "interpretation" of the mechanisms determining those phenomena. Yet string theorists do tend to optimistically conjecture that the strings are both real and explanatory, not merely predictive devices. It is far beyond the capacity of today's particle accelerators to propel any probing particles at energy levels high enough to overcome a quantum particle's own energy and determine whether it is a string. Yet this limitation also exists on testing other theories of quantum gravity. Developments suggest other strategies to "observe" the structure of quantum particles.