Jaime Rudas's latest activity
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Jaime Rudas reacted to Ibix's post in the thread High School Am I understanding the concept of proper frame of reference? with
Informative.
Note that the English meaning of "proper" has drifted over time to mean "correct". In this context, though, it's being used in an older... -
Jaime Rudas reacted to A.T.'s post in the thread High School Why is the constant speed of light so unique? with
Like.
Only in the rest frame of the medium you have sound propagating at the same speed in all directions. Light propagates at the same speed... -
Jaime Rudas replied to the thread Undergrad How to define a vector field?.Wikipedia lists ten books written by that author.
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Jaime Rudas reacted to PAllen's post in the thread Undergrad The quintessence as variable dark energy with Informative.
That is an exceedingly narrow statement of the equivalence principle. The most commonly accepted meaning of strong equivalence principle...
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Jaime Rudas reacted to PAllen's post in the thread Undergrad The quintessence as variable dark energy with Like.
While the FLRW metric, when used for a realistic universe, is purely an emergent approximation at large scales, there is one aspect of...
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Jaime Rudas reacted to PeroK's post in the thread Undergrad The quintessence as variable dark energy with Like.
There are no voids in a homogeneous universe. If you want to study a local region of the universe, then you need to set up the...
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Jaime Rudas reacted to PAllen's post in the thread Undergrad The quintessence as variable dark energy with Informative.
Yeah, but if you are talking about galaxies, you are outside the FLRW idealized model - that has only perfect fluid with different...
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Jaime Rudas reacted to PAllen's post in the thread Undergrad The quintessence as variable dark energy with Like.
As far as I know, the common models of quintessence still use the FLRW equation metric, just with particular forms of ##a(t)##. In...
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Jaime Rudas reacted to PeterDonis's post in the thread Undergrad The quintessence as variable dark energy with Like.
"Space" isn't an invariant. It varies in spacetime. Whether that means variation in "space" depends on your choice of coordinates...
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Wikipedia says: Does the quintessence really vary in space? Wouldn't that imply violating the cosmological principle? Or perhaps it...
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Jaime Rudas reacted to PeterDonis's post in the thread Graduate Couldn't the cosmological constant also have some sort of "dynamics"? with Like.
It's straightforward to write down the model; indeed doing that is an exercise in some advanced GR textbooks. The usual way is to use a...
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Jaime Rudas reacted to PeterDonis's post in the thread Graduate Couldn't the cosmological constant also have some sort of "dynamics"? with Like.
Because a constant is the simplest model, and we have no evidence that it's not constant, so we use the simplest model that's consistent...
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Jaime Rudas replied to the thread Undergrad Euclidean geometry and gravity.Ah, yes, now I understand: its area is equal to that of a sphere of the same radius 4πR².
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Jaime Rudas replied to the thread Undergrad Euclidean geometry and gravity.In what sense the pseudo-sphere isn't "a global embedding – the complete unbounded hyperbolic plane in ##E^3##"? Is it, perhaps, because...
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Jaime Rudas reacted to PAllen's post in the thread Undergrad Euclidean geometry and gravity with Informative.
I can’t seem to let this go, partly because some have asked for how to make the embedding result (part of Euclidean plane in 3-sphere)...