PeterDonis's latest activity
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PeterDonis reacted to Ibix's post in the thread High School Can a black hole become a white hole? with
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No, white hole spacetimes look nothing like the big bang spacetime. And the big bang was not a point as far as we know. Black holes are... -
PeterDonis reacted to Ibix's post in the thread High School Do Dark Energy and the Casimir effect indicate Exotic Matter could exist? with Like.
I don't think the Casimir effect does, no. My limited understanding is that it can be rewritten as an effect of van der Waals forces...
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PeterDonis replied to the thread Graduate Why is 0 K unattainable?.Thread closed for moderation.
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Noooo. The 1972 pic was taken of the sunward side of the Earth - almost full sun. The 2026 pic was taken of the Earth's night side -...
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Please remember that we do not allow AI as a source or reference in the technical forums here (like where your thread is posted). AI is...
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You are right. If the lowest possible energy is positive, then the factor ##e^{-\beta H}## vanishes at zero temperature even for the...
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PeterDonis replied to the thread Graduate Why is 0 K unattainable?.This is not correct. There is no requirement that the ground state of the Hamiltonian have zero uncetainty in position and momentum. All...
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PeterDonis replied to the thread Seeking clarity on the physical definition of an observer.Is that like the difference between all dead and mostly dead?
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PeterDonis reacted to mfb's post in the thread Undergrad Is the Wavefunction Speed in Quantum Mechanics Wrong? with Like.
The phase velocity (what you calculated) is not the group velocity (the propagation of your wave packet, and the change of the...
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PeterDonis reacted to DrClaude's post in the thread Undergrad Orbital electrons in stationary states? with Like.
Indeed, I maintain that stationary states are eigenstates of the Hamiltonian, and vice versa. I completely agree that superposition of...
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PeterDonis replied to the thread Seeking clarity on the physical definition of an observer.Moderator's note: Thread moved to the QM interpretations subforum.
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PeterDonis replied to the thread Undergrad Are Alternative Dark Energy Models Treated More Favorably Than MOND?.Thread closed for moderation.
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PeterDonis replied to the thread Undergrad Are Alternative Dark Energy Models Treated More Favorably Than MOND?.Note that we've had some previous threads on issues with this model--including one that you started...
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PeterDonis replied to the thread Graduate Gauge conditions in interaction theory.None of the above. You need to go back to the beginning and specify a consistent scenario.
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PeterDonis replied to the thread Graduate Gauge conditions in interaction theory.I think you're missing Paul Colby's point. The EM field equations only make sense in the first place if the current ##J^\mu## satisfies...