PeterDonis's latest activity

There is such a thing as null dust in the literature. :wink: But it's not intended to cover this kind of case. I think @Demystifier...

It is if we are using a typical continuum model, where "dust" is just another name for "a perfect fluid with zero pressure and stress"...

It's not. It's a matter of "that's how we make accurate predictions". That's how any physical theory works: you figure out what...

No, that's not what "no collapse" interpretations (like the MWI) say. They say unitary evolution just continues, all the time. Yes, part...

Um, because that's how the theory works? And doing it that way makes correct predictions? Um, the latter? Since that "mathematical...

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But there is additional stress-energy in the problem, because the little rockets have to have fuel and rocket exhaust, and the direction...

I think the properties of the final state are important for that. But I don't think the spin-up process is. I agree that, in the final...

Yes, there is. It is perfectly possible to have a disk whose motion is rigid at a constant angular velocity ##\omega##. SR does not rule...

I understand that, I just don't see how it's relevant to what's in the OP. The OP is just describing the final state, not how it's...

I think the answer to this depends on which QM interpretation you adopt. Your step 3 (which is usually called "collapse" or "state...

I'm not sure this is true. There is no spin-up process described in the OP or in the integral there--the angular velocity ##\omega## is...

As far as I can see, your question has already been answered in this thread--by you yourself. @Dale and I have simply concurred with...

OP needs to read: How to Better Define Information in Physics

In the sense of the last paragraph of my post #9, they are, yes. Yes. What do you mean by "after collapse"? I explained in post #4 why...