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Do you mind elaborating? Or pointing me in the direction of material that explains the space goo issue. thx

The biggest issue I see with the goo metaphor, is that it seems to suggest some sort of stationary ether that we move through as we move through space. That is to say, the mathaphor suggests that it makes sense to differentiate between stationary objects and moving objects in an objective sense. However, the core insight of relativity is that there is no such distinction.

This seems like a inevitable issue with any metaphor. It will always supply unwanted associations.

Yes, but its still worth being intentional about which ones you allow/support and which ones you don't.

I'm reading the whole book right now and the chapter after the one from the article is about time and goes more into spacetime according to relativity.

So far it seems to me that they sometimes provide an oversimplified analogy which they revise in a later chapter.

> So far it seems to me that they sometimes provide an oversimplified analogy which they revise in a later chapter.

Welcome to every high-school, undergrad and postgrad physics course. That's just how most sciences are taught. Physics especially, because all analogies lead to misunderstandings because they are an attempt to simplify the mathematics underlying the physics[1]. Such analogies will always result in certain subtleties being lost on the student, but if the student is not familiar with the subject then the mathematics would also be lost on them.

The reason why this method works is that physics operates on approximations, so an approximately accurate analogy is a step in the right direction for a more accurate mathematical model (which is still ultimately an approximation).

[1]: https://xkcd.com/895/

I'm really loving the book (half way through it!).

Part of me knows that a lot of this is being simplified down for me, but I also trust the authors to not steer the reader too far off course.

I may not have all the math and physics understanding, but I get that dark matter is real. I didn't before. That's the kind of thing the book is about, imho.

There is currently no way to differentiate between Einsteinian relativity and Lorentzian relativity. The latter proposes an absolute reference frame. The CMB frame would be a reasonable choice for a stationary structure at the Planckian level that would host the energy bundles (quarks etc) that make up objective reality, cf. loop quantum gravity.

A one-way measurement of the speed of light is needed to differentiate between the two theories, and that has not been accomplished. In fact, it may not be possible in principle to do so. Choice then becomes a matter of taste and philosophical/physical economy.

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