 Like Einstein, many physicists and philosophers who wish to derive Einstein’s equation do so by considering an idealized physical configuration. Typically, one considers a physical object \(B\) involved in a symmetric physical interaction. For example, in Einstein’s original derivation from 1905, \(B\) emits two equally energetic pulses of light in opposite directions. Mermin and Feigenbaum have shown how one can also derive Einstein’s equation by considering the case where \(B\) emits two physical bodies, instead of pulses of light (Mermin and Feigenbaum 1990). 