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Nice site Geezer, and I agree on that looked at as a system the 'internal energy' have changed for it. But a system is very much a conceptual exercise wherein you are free to define it like you need, for the validation of your experiment, within limits of course but..The 'internal energy' you refer too I see a as a common description for all relations involved between, and in, the objects you defined as belonging to that same 'system'. And you need only to change what objects you refer to to get a new and different 'system'. As I see it not unlike the idea of 'potential energy'. But even so, that book has no extra energy collected in it by you lifting it up on a table. The potential energy that it refer too is not measurable as any new mass, its atoms are not jiggling faster. In fact, nothing have changed for the book itself. The only thing changing is the relation it will have relative gravity. And that's the plain truth, nothing more But the 'systems' possible energy have changed, if we remember that it's the 'possible' energy we're talking about, that is the 'potential energy'.Gravity is no force, to me it's more of a 'topology'. What you could assume, possibly, is that when getting compressed, like moved close to the event horizon, or past, it should express itself as more mass. At least it seems reasonable to assume that, also there is the question about what a Lorentz contraction does to a piece of lasting matter. Those two are really interesting
Well, we define 'potential energy' too Geezer. We have a lot of laws describing transformations, but as for how they are measurable? A compression should be measurable.
Did that machinery gain any energy? (final state) Nope.
If you define the universe as 'closed' you might want to define the same happening there.
You're right there I assume that you mean a 'closed system' for that though.
And in neither case the book will weight more, that is have an added 'energy'.
Can you tell me what you mean by the system having an 'added energy'?
As for the 'big hand' Okay, i kind'a like that one. But when it comes to comparing doing mechanical work on a spring, winding it up and storing the energy, that also will express itself as a added 'invariant mass' if measured with lifting a book? Nope. It's not the same.
Are you saying gravity is a force containing a energy Geezer?
Though if we were gnomes living inside the book we would not find any gravitation acting upon us, making it inseparable from any other uniform motion,