dμFνλ+dνFλμ+dλFμν=0
given that
Fμν=dμAν−dνAμ=dAνdxμ−dAμdxν
assuming
μ=0 and
ν=j=(1,2,3) in the first equation, we get
d0Fjλ+djFλ0+dλF0j=0
now let’s write
λ=(0,k) where k = (1,2,3)
d0Fj0+d0Fjk+djF00+djFk0+d0F0j+dkF0j=0
d0(−Ej)+d0(−Bk)+dj(−Ek)+d0(+Ej)+dk(+Ej)=0
d0(−Bi)+dj(−Ek)+dk(+Ej)=0
d0(−Bi)+(∇×E)i=0
similarly when
ν=0 and
λ=0, we get two more equations
d0(−Bj)+(∇×E)j=0
d0(−Bk)+(∇×E)k=0
in general we can write
−d0B+∇×E=0
−1cdBdt+∇×E=0
when
d=(d0,di)=(1cddt,−∇)
now, assuming
μ=i and
ν=j
diFjλ+djFλi+dλFij=0
now, for
λ=(0,k) where
k=(1,2,3) as before
diFj0+diFjk+djF0i+djFki+d0Fij+dkFij=0
diFj0+djF0i+d0Fij+diFjk+djFki+dkFij=0
di(−Ej)+dj(+Ei)+d0(−Bk)+di(−Bi)+dj(−Bj)+dk(−Bk)=0
di(−Bi)+dj(−Bj)+dk(−Bk)=0
∇⋅B=0