The problem of energy appearing out of nowhere

[PeterDonis]

The question was if an alternative universe without that feature is self consistent. And it clearly is.

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 I can't look to see if it addresses this.

 

[Roberto Pavani]

Very interesting discussion. I'd note that the arXiv preprint I referenced in a related thread (Hobson, Barker & Lasenby, arXiv:2605.19719), proving that no local gauge-invariant energy-momentum tensor exists for the linearised gravitational field, seems relevant here as well.

 

[Dale]

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.

Of course it does. That is the whole point of writing the equations of motion and finding solutions. If you have a system of equations and that system of equations has a solution then it is self-consistent. It may be inconsistent with other models or principles, and it may be inconsistent with experiment, but it is self consistent.