D O C U M E N T 4 2 2 J A N U A R Y 1 9 2 3 3 6 3 . If one therefore sets , one thus obtains an elegant form for the energy-momentum equation: (!) __________________________________________ . _________________________________________ The third term of the expression thereby yields the components, at rest: = . Esteemed Professor! How do you choose?—between whether 1) should be symmetric, or 2) should assume a natural, mathematically (as well as probably also physically) so elegant a form! In great respect, yours most sincerely, Jun Ishiwara. ∂ ∂xν ------- -– εϕναψμα 1 μ -- - ϕμαψνα + + εϕνα∂xν( ∂ ------- - ϕμα ψμα) + 1 μ -- - ψνα------- ∂ ∂xν -( ϕμα ψμα) + + Tμν –εϕμαϕνα 3 4 --δμνϕαβ2 - + = 1 μ -- - ψμαψνα – 1 4μ ------δμνϕαβ2 + εϕναψμα 1 μ -- - ϕ μα ψνα + – ∂Tμν ∂xν ----------- - ϕμα ψμα)Iα + ( 1 4∂xμ ---------- - ∂ εϕαβ 2 1 μ -- - ψαβ 2 + + = εϕνα∂xν( ∂ ------- - ϕμα ψμα) + – 1 μ -- - ψνα∂xν( ∂ ------- - ϕμα ψμα) + – Tμν εϕναψμα 1 μ -- - ϕμαψνα + 0 0 0 iε( eybz ezby) – 0 0 0 iε( ezbx exbz) – 0 0 0 iε( -------------) i μ -- - eybz ezby) – ( i μ -- - --------) ( i μ -- - --------) ( 0 Tμν ∂Tμν ∂xν ----------- -