Roberto Pavani's latest activity
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Roberto Pavani reacted to PeterDonis's post in the thread High School The problem of energy appearing out of nowhere with
Agree.
More precisely: a photon emitted by a comoving observer and measured to have a certain energy at emission by that comoving observer... -
Roberto Pavani replied to the thread High School The problem of energy appearing out of nowhere.My 2 cent: A standard example: In any expanding universe, photon energy decreases (cosmological redshift) without being transferred...
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Roberto Pavani reacted to Matterwave's post in the thread High School The problem of energy appearing out of nowhere with
Like.
Do you define GR to "obey relativity" (or do you read "obey relativity" as global Lorentz invariance)? Depending on the reading of the... -
Roberto Pavani replied to the thread A question about quantum entanglement.Just a small note: von Neumann was actually very interested in the foundations of QM (collapse postulate, hidden variables proof, etc.)...
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Where in the world did you even get this from?
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Roberto Pavani replied to the thread Undergrad Why ##a^0=1##?.Equation 1 has no solution: ##2^x > 0## for all ##x \in \mathbb{R}##. The only "value" satisfying ##2^x = 0## is ##x = -\infty##, which...
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Roberto Pavani reacted to .Scott's post in the thread Do you 'see' the CMB map as a 3D glass sphere/ellipsoid? with Like.
It's easy for me to imagine that green/yellow/red is foreground facing "out" and the light/dark blues are a view of the background...
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Roberto Pavani posted the thread Do you 'see' the CMB map as a 3D glass sphere/ellipsoid? in General Discussion.When I look at the standard Mollweide projection of the CMB, after a few seconds my brain seems to "un-project" it into a 3D object, as...
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Roberto Pavani reacted to Matterwave's post in the thread Undergrad FLRW metric challenged, Einstein-Euler equations as alternative? with Like.
The universe is certainly not strictly isotropic. Even around us, the cmb has fluctuations. My statement was about the mathematics and...
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Roberto Pavani reacted to nomadreid's post in the thread Undergrad FLRW metric challenged, Einstein-Euler equations as alternative? with Like.
Thank you; I have downloaded it from arXiv.
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Roberto Pavani replied to the thread Undergrad FLRW metric challenged, Einstein-Euler equations as alternative?.No, I was thinking of Buchert's original paper (gr-qc/9906015). I might be oversimplifying things though, I'm not an expert on this.
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Roberto Pavani replied to the thread Undergrad FLRW metric challenged, Einstein-Euler equations as alternative?.Interesting point, but I'm not sure this is the only possibility. What about the Buchert averaging stuff? If I understand it...
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Roberto Pavani reacted to kuruman's post in the thread High School Does this equation (Einstein’s field equations in general relativity) equal 12? with
Haha.
The girl got it wrong. Actually, the answer is 42. See https://simple.wikipedia.org/wiki/42_(answer) -
Roberto Pavani replied to the thread High School Is it possible for matter to be completely destroyed to nothingness.(high school answer): You can break matter down as far as a proton + electron + photon + neutrino plasma, that's the simplest form. You...
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Roberto Pavani reacted to Matterwave's post in the thread High School The One Electron Universe suggested by Wheeler with Like.
Maybe the 1-electron universe was simply a stepping stone for Wheeler to get to the 0-electron universe haha. Charge without charge...