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Feb9-12, 03:43 PM
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P: 706
Quote Quote by Ken G View Post
2) worse, it is against the genius of GR to encorporate fundamentally observer-dependent concepts into the structure of the theory. To understand GR (and SR for that matter), it is necessary to recognize the importance of the difference between what is an objectively supportable statement about the nature of some situation, which must be expressed in invariant form, versus what is just a matter of coordinates, which is like a word that sounds different in English and Italian. In English, we have the word "love", in Italian, "amore". The words sound totally different, so in your approach to the concept of love, we would have the statement that love is language dependent because amore sounds completely different. However, the whole point of the concept of love is that it ought to be there no matter what language you use, or even if you have invented language at all. When the same cannot be said about the concept of a global inertial frame, it exposes the fact that such a concept is not a physically real object that should appear in any theory of physics. Rather, it is simply a matter of coordinates, which is important in the practice of getting useful numbers, but has no place in any theory of physics. Indeed, that is pretty much the breakthrough realization that underpins all of relativity.
GR says no such thing, nor does this claim have anything to do with the concept of a global inertial frame. You are confusing "happening at a place and time" with "being able to be given coordinates that exist in some particular global system." Those are just not the same thing.
There is a big difference between language dependence, and observer dependence.

(To distinguish between observer dependency and description dependency: )

With language dependency love is the same thing whether I say it in Latin or English.

But with observer dependency, my experience of love is certainly a different experience than your experience of love. We don't love the same things; we don't love the same people; we don't even know the same people.

If ANY theory of physics cannot account for observer dependency, it is flawed.