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PPAllen replied to the thread Some thoughts about self-education.So am I.
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PPAllen replied to the thread High School Estimates — True Size of the Universe?.You can, but many people have a hard time picturing how this is possible. My suggestion provides a way to picture this that was helpful...
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PPAllen reacted to javisot's post in the thread High School Estimates — True Size of the Universe? with
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(When I said it was a property of all spacetime, I didn't say it was a property of all spacetimes. We're talking specifically about an... -
PPAllen replied to the thread High School Estimates — True Size of the Universe?.Actually, it is only a possible property of very special spacetimes. It is a feature of geometry that is hard to visualize in a 3x1...
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PPAllen replied to the thread High School Estimates — True Size of the Universe?.I’ve used the following analogy to picture an infinite expanding universe. Consider the universe as an (countably) infinite collection...
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PPAllen replied to the thread High School Am I understanding the concept of proper frame of reference?.I found an explicit statement in this section of MTW (13.6 bottom of p. 331 in my edition) that makes clear that they have the meaning I...
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PPAllen replied to the thread High School Am I understanding the concept of proper frame of reference?.The wording “proper reference frame of an accelerated observer” implies, in ordinary English, the notion of proper reference frame of a...
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PPAllen replied to the thread High School Am I understanding the concept of proper frame of reference?.Well, MTW calls it the proper reference frame of an accelerated observer, implying that a standard inertial frame is the proper...