Symbol mu

The passage around this formula

Nothing above touches curved spacetime, and this section exists to keep it that way explicitly rather than by omission, because a construction with the words “ledger” and “missing energy” in its own title is exactly the kind of object this subject’s cranks reach for first. State the settled physics plainly before anything else: the local conservation law of general relativity, $\nabla_\mu$ $T^{\mu\nu}$ = 0 , is a differential identity following from the Einstein field equations via the contracted Bianchi identity, and it holds in every spacetime — flat, curved, static, or violently dynamical — without exception. Nothing that follows questions it, qualifies it, or needs it to be anything other…

Read this part in the article →