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PeterDonis's latest activity
PeterDonis
replied to the thread
A
Horndeski: denominator null implies an infinite quantity
.
It involves a functional derivative with respect to the function that is the derivative with respect to ##x^\beta## of ##A_\alpha##. The...
Yesterday, 10:32 PM
PeterDonis
replied to the thread
A
Horndeski: denominator null implies an infinite quantity
.
Where did you get that from? You need to give a reference.
Yesterday, 8:59 PM
PeterDonis
replied to the thread
A
Horndeski: denominator null implies an infinite quantity
.
Per my post #7 just now, this equation isn't even well-defined. Where are you getting it from?
Yesterday, 6:45 PM
PeterDonis
replied to the thread
A
Horndeski: denominator null implies an infinite quantity
.
That expression isn't even well-defined. ##g_{\sigma \tau, \beta}## means ##\partial / \partial \beta ( g_{\sigma \tau} )##. You can't...
Yesterday, 6:42 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
Perhaps so, but in any event that is not the standard interpretation of time zones. Nobody actually treats 9 am Eastern and 9 am Central...
Yesterday, 6:38 PM
PeterDonis
replied to the thread
B
E-field of a constant velocity charged particle
.
Thread closed for moderation.
Yesterday, 5:27 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
Yes, we discussed that before. To recap briefly, time zones and dates don't define a foliation that has timelike tangent vectors on its...
Yesterday, 4:57 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
I agree that this case (timelike integral curves, spacelike foliation surfaces) will be the one that most clearly matches our intuitive...
Yesterday, 4:34 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
I think that would make the most sense, but there are examples of null foliations (for example Eddington-Finkelstein coordinates). I...
Yesterday, 4:33 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
No, I don't. I gave a counterexample: Painleve coordinates inside the horizon of a black hole. The integral curves of ##T## there are...
Yesterday, 4:31 PM
PeterDonis
reacted to
renormalize's post
in the thread
B
E-field of a constant velocity charged particle
with
Like
.
Since the 1s ground state of the hydrogen atom is spherically-symmetric, can you tell us in which direction this electric field points?
Yesterday, 4:29 PM
PeterDonis
replied to the thread
I
Experimental evidence of the existence of an event horizon
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The OP question has been answered. Thread will remain closed.
Yesterday, 12:07 PM
PeterDonis
replied to the thread
How Dangerous is Editing the Windows Registry?
.
I'm having difficulty imagining something requiring that that would be worth the risk.
Yesterday, 12:56 AM
PeterDonis
replied to the thread
How Dangerous is Editing the Windows Registry?
.
No, this is not good advice. The very fact that you put "claims" in scare quotes should be a red flag.
Yesterday, 12:56 AM
PeterDonis
replied to the thread
I
Can “speed of light” distinguish all Timelapse videos from real motion?
.
No, you wouldn't, since it is impossible to observe a line of simultaneity. Thread closed due to personal speculation.
Saturday, 11:04 PM
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