Recent content by PeterDonis

I just looked up the theorem in Wald to see how it is explicitly stated. Theorem 9.5.1 states a maximum length to the past of the given Cauchy surface for all timelike curves, not just geodesics. The geodesics are the only such curves that must be incomplete, because a complete geodesic must be...

First, even if this happened, you would still have incomplete geodesics. So it wouldn't change the conclusion that incomplete geodesics must exist. Second, there must be geodesics passing through every event in a spacetime. (The simplest way to see this is to observe that the tangent space at...

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The correlations associated with "thermal nonlocality" can't violate the Bell inequalities, so no, I would not say they're "similar enough", since Bell inequality violations are the key issue that undermines intuitive "classical" explanations of the correlations.

If you use the restrictive definition of "planet" by which Pluto got demoted to, IIRC, a "dwarf planet" (and the others further out are also "dwarf planets"), yes.

These are two different questions. "Moving in a specific direction" is a question about momentum. Photons do have a well-defined momentum operator, so yes. "Localised" is a question about position. Photons do not have a well-defined position operator, so no.

Is it? That's the question. The fact that you can write down a force equation with a damping term, so that mechanical energy is not conserved, does not prove that that equation is part of a self-consistent model. I haven't been able to find a non-paywalled version of the paper you referenced, so...

Lack of global conservation of what? In FLRW spacetime, the issue is not that there is a global invariant that is not conserved. The issue is that, since there is no timelike KVF, there is no such global invariant to begin with. It doesn't make sense to say that something that doesn't even...

Actually, "conventional physics" does have a concept something like what you describe--indeed, that's how the concept of a "field" arose in physics in the first place, in order to explain how charged objects could be accelerated without anything visible appearing to push on them. The...

This is personal speculation and is off limits here.

That's correct. It's a consequence of the Einstein Field Equation, plus including all forms of local stress-energy in your model. In a case like the relativistic damped oscillator that @Dale posted a reference for, the appearance of energy being lost in the oscillator arises from the fact that...

Only if you think correlations that violate the Bell inequalities is of no concern. Which is certainly a possible point of view, but it doesn't appear to be a very common one.

It appears to be paywalled, unfortunately. Yes, that makes sense. A damping term in the relativistic force equation would result in energy loss if you're only modeling the oscillator's motion and not including heat or other energy sinks.

It's the standard one accepted by physicists who work on GR, and has been ever since the Bianchi identities satisfied by the EFE were understood. Also, as you appear to agree, it captures the intuitive notion of "energy can't appear out of nowhere" (or disappear into nowhere). Nor does there...

More precisely: a photon emitted by a comoving observer and measured to have a certain energy at emission by that comoving observer, will be measured to have decreasing energy by future comoving observers as it passes them. However, the stress-energy contained in the photon is still locally...