PeterDonis's latest activity
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PeterDonis replied to the thread Undergrad Are Alternative Dark Energy Models Treated More Favorably Than MOND?.Agreed. I would say that how the proponents describe it is a very significant contribution to how the community perceives it. -
PeterDonis replied to the thread Undergrad Hawking radiation may smooth black hole singularities.For some values of "Hawking radiation", yes. :wink: Physically speaking, "backreaction" isn't something that needs to be "added". It...
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PeterDonis replied to the thread Undergrad Are Alternative Dark Energy Models Treated More Favorably Than MOND?.It's worth noting, though, that from the perspective of deriving the Einstein Field Equation from a Lagrangian, the presence of a...
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PeterDonis replied to the thread Undergrad Are Alternative Dark Energy Models Treated More Favorably Than MOND?.Whether its proponents claim it does, yes, I'll agree with that. I'm just pointing out that those claims, even by model proponents...
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PeterDonis replied to the thread Undergrad Are Alternative Dark Energy Models Treated More Favorably Than MOND?.Note that when you try to construct relativistic "MOND" theories, the boundary gets somewhat blurred. For example, TeVeS adds a scalar...
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PeterDonis reacted to Jaime Rudas's post in the thread Undergrad Are Alternative Dark Energy Models Treated More Favorably Than MOND? with
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I think the issue has to do with the fact that General Relativity is one of the most successful theories in history, so any model that... -
PeterDonis replied to the thread Undergrad Hawking radiation may smooth black hole singularities.I don't know that I'll be able to find a reference in the QFT literature that specifically says the thing you appear to be looking...
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PeterDonis replied to the thread Undergrad Hawking radiation may smooth black hole singularities....to the Einstein-Hilbert action, i.e., by modifying GR. But you don't need to do that to get a "regular black hole" such as the...
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PeterDonis replied to the thread Undergrad Hawking radiation may smooth black hole singularities.The causal structure of the Bardeen black hole is the same as that of Minkowski spacetime. AFAIK it's well understood in the QFT...
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PeterDonis replied to the thread Graduate Relationship between superconductors and gravity.Searching on his name here at PF will get you to plenty of previous PF threads discussing his work and the issues with it. I don't know...
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PeterDonis replied to the thread High School Calculating an impossible reference frame as my own homework problem.Which you would do how? By firing rockets? No, firing rockets doesn't cause you to "enter a new reference frame". You're always "in"...
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PeterDonis replied to the thread Undergrad Does the Alcubierre drive shorten distances?.It seems to me that there's an obvious diagonalization: just define a coordinate ##\zeta## such that ##d \zeta = dx - v f dt##. Then ##d...
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PeterDonis replied to the thread Undergrad Does the Alcubierre drive shorten distances?.Yes, I've had a couple of tries at constructing such a chart, but haven't had enough time to get there. It would be interesting to see...
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PeterDonis reacted to PAllen's post in the thread Undergrad Does the Alcubierre drive shorten distances? with Like.
I would like to summarize conclusions scattered across this thread. The following are key references: The main document that...
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PeterDonis replied to the thread Undergrad Does the Alcubierre drive shorten distances?.Not on the obvious layman's meaning of "stationary": not all Eulerian observers have constant spatial coordinates with respect to this...