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Abstract: In quantum mechanics we usually consider the observer to be external to the system being studied, but in the context of gravity, especially in a closed universe, it may be necessary to explicitly take into account the observer and the observer's gravity.  After a general discussion of what an observer can observe, I will describe the example of de Sitter space, where it is necessary to explicitly take into account the gravity of the observer.   (This example was analyzed in arXiv:2206.10780 with V. Chandrasekharan, R. Longo, and G. Penington.)