PeterDonis's latest activity
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.I fail to see how this is relevant to the discussion at all. Please note that, as I said in post #109, a metric tensor is a differential... -
PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.No, I would make no such claim. The stretched rubber band has a nonzero stress and strain in it. This is physically measurable and...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.So how is your hypothetical in which we say that a particular tensor is not the metric tensor relevant to this at all? No, it isn't...
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PeterDonis reacted to martinbn's post in the thread Undergrad Why is gravity a fictitious force? with
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The topology comes with the manifold, no matter what tensors you consider. There is no room for interpretations. -
PeterDonis reacted to Dale's post in the thread Undergrad Why is gravity a fictitious force? with Like.
Sure one can. One doesn’t need to bring in irrelevant topics to hijack a thread. This is utterly irrelevant to the discussion here...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.None, of course. I've already said that the objects we currently call "black holes" might not actually be described by that particular...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.What would that even mean? Until you tell me what this is supposed to model physically, how can I possibly say anything about it?
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.Yes, there is--if we only focus on the exterior, we're not using a "black hole spacetime" at all. We're just using one particular piece...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.There is no interpretation involved in the statement I made about global topology. Whether the actual, physical objects we call "black...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?."The exact Schwarzschild metric" is not the same as "a black hole spacetime". The issue here isn't the local solution; it's been known...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.This can only represent "gravitational fields" on the chosen background. It can't, for example, represent a black hole spacetime...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.Then you are doing quantum field theory, not classical GR. This is the classical GR forum, so here, we use the GR definition of force.
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.Tidal gravity can be measured--it's not "fictitious"--but in GR it is not a force. A force is something that causes nonzero proper...
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PeterDonis reacted to PAllen's post in the thread Undergrad Is there a zero-mass, vacuum Schwarzschild GR solution? with Like.
A singularity is does not make a mean a manifold is not a pseudo-Riemannian manifold. A singularity is a feature some manifolds have...
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PeterDonis replied to the thread Undergrad Why is gravity a fictitious force?.The test masses inside LIGO are in free fall, at least in the horizontal direction (of course they are suspended vertically and have...