Comment Comment by curt15 I come from maths, not physics, but their constructiong_{\mu \nu} = A_\mu A_\nulooks a little weird to me. The left side is a tensor, but isn't the electromagnetic four-potential is a gauge field, not a tensor? parent curt15 5 years ago
g_{\mu \nu} = A_\mu A_\nu
looks a little weird to me. The left side is a tensor, but isn't the electromagnetic four-potential is a gauge field, not a tensor?