New Reading of Relativity. 49 



Ingenious device contrives a mathematical status for the 

 last term in equation (2), whose recognition at first hand 

 constancy of inertia excludes. 



The natural inferences that equation (13) has forced upon 

 attention by restating the situation of equation (16), offer 

 more than a glimpse of a self-selected frame, basic for physical 

 phenomena in this sense : Departures from it, either by 

 rotation or by translation impress distortions of common type 

 upon dynamical magnitudes. To render that deeply-seated 

 symmetry convincing might crown our instinctive search 

 better than inventing for physical laws a formal indifference 

 among base-frames. If such ideal outlook has restricted 

 appeal, there is practical service in coordinating at the same 

 time elements of potential. That a potential is available 

 which gives coherence to all phases of our electron's energy, 

 the work equation indicates through its sole dependence upon 

 terminals of the interval. Equations (39, 40) are another 

 aspect of that thought. Moreover, the initial supposition of 

 equation (5) and its probable connexions at equations (9, 

 10, 11) fit at sight the more standard form of the Lagrange 

 function (L) as measuring appropriately a difference of 

 energy-states. Write 



OJ 



L=-m c'( ' s/<:i - vi -l\ =m c 2 -m(c 2 -v 2 ). . (47) 



Fixing the zero-phase as rest in the frame (F), the last 

 member sets down an expectation then bounded bv bringing 

 (?» ) to the limiting speed (c). In the general phase, (m ) 

 has become (m) by gathered increment : so reading (mv 2 ) as 

 a fact of realization the last term exhibits what other energy 

 of (m) at that epoch is outstanding for final conversion into 

 kinetic form; at the limit-value (c), whatever (m) may be 

 attained by accretion. The form (2E— L) for total energy 

 agrees with equation (6) for work done from rest. 



Whatever cumulative pressure from these arguments is 

 felt will carry us toward restoring to fuller proportions the 

 shrunken claim that Lorentz urges for " Wahre Zeit " and 

 for frames " Die im Ather ruhen ; " a passage remarkable for 

 its scientific candour *. The complications due to curvilinear 

 path, to radiation, and to other causes do not weaken this 

 primary correlation of Einstein with Newton. Both lines of 

 thought alike must cope with the superposed difficulties. 



University of California. 



* Sammlung, p. 75. 



Phil. May. Ser. 0. Vol. 40. No. 235. July 1920. E 



