The Principle of Relativity

by Albert Einstein; H. Minkowski

Further f₂₃, f₃₁, f₁₂, f₁₄, f₂₄, f₃₄

for m_x, m_y, m_z, -i(e_x, e_y, e_z),

and F₂₃, F₃₁, F₁₂, F₁₄, F₂₄, F₃₄

for M_x, M_y, M_z, -i(E_x, E_y, E_z)

lastly we shall have the relation f_{k h} = - f_{h k}, F_{k h} = -F_{h k}, (the letter f, F shall denote the field, s the (i.e. current).

Then the fundamental Equations can be written as

(A)

∂f₁₂/∂x₂ + ∂f₁₃/∂x₃ + ∂f₁₄/∂x₄ = s₁

∂f₂₁/∂x₁ + + ∂f₂₃/∂x₃ + ∂f₂₄/∂x₄ = s₂

∂f₃₁/∂x₁ + ∂f₃₂/∂x₂ + + ∂f₃₄/∂x₄ = s₃