 Over a century after Einstein’s first derivation of mass-energy equivalence, as his famous result is called because one can select units in which one can express it with an equation of the form \(E = m\), the result continues to receive outstanding empirical support. Furthermore, as the physicist Wolfgang Rindler has pointed out, the result “has been found applicable and valid in many branches of physics, from electromagnetism to general relativity” (Rindler 1991, p. 74). Thus, from Rindler’s perspective, which is shared by many physicists, mass-energy equivalence “… is truly a new fundamental principle of physics” (Rindler 1991, p. 74). 