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Grinkle's latest activity
Grinkle
reacted to
Nugatory's post
in the thread
B
Falling into a black hole
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I expect that it is largely historical. When we're solving the EFE for a spherically symmetrical spacetime, it's just another...
Yesterday, 10:53 AM
Grinkle
reacted to
Ibix's post
in the thread
B
Falling into a black hole
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What happens is that when ##r<R_S## the ##1-R_S/r## terms flip sign, and one of the spacelike coordinates inside the horizon has the...
Yesterday, 10:52 AM
Grinkle
replied to the thread
B
Falling into a black hole
.
Sorry if the answer is in the paper that @Nugatory linked, I have it printed but haven't read it yet. In what sense is it less...
Yesterday, 8:53 AM
Grinkle
reacted to
Ibix's post
in the thread
B
Falling into a black hole
with
Like
.
The Kruskal diagram deliberately has the same property as the Minkowski diagram that light travels on 45° lines. All timelike paths are...
Yesterday, 8:41 AM
Grinkle
replied to the thread
B
Falling into a black hole
.
Is the following question purely a choice of co-ordinates, or is there some physics involved? Sorry to get so "meta", asking a question...
Yesterday, 8:23 AM
Grinkle
reacted to
Nugatory's post
in the thread
B
Falling into a black hole
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Like
.
In quadrant II the ##r## coordinate is timelike, so curves of constant ##r## are at less than a 45-degree angle and as @PeterDonis says...
Yesterday, 7:54 AM
Grinkle
reacted to
PeterDonis's post
in the thread
B
Falling into a black hole
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They are best viewed as moments of time that the infalling particle passes through between the horizon and the singularity.
Yesterday, 7:54 AM
Grinkle
replied to the thread
B
Falling into a black hole
.
@Nugatory Thanks for linking this. In quadrant II, what is the interpretation of the constant 'r' curves? The infalling particle path...
Saturday, 6:54 PM
Grinkle
reacted to
Vanadium 50's post
in the thread
B
Will we ever communicate with extraterrestial life in a reasonable time frame?
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Well, when you looked it up on Wikipedia, you would have discovered there are 130 K, G and F type stars within 50 light years. You also...
Friday, 6:34 AM
Grinkle
reacted to
Ibix's post
in the thread
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Detection of red-shifted photons near an event horizon
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The simplest explanation is that the horizon crossing leaves your future light cone but never enters your past lightcone. So there is...
Tuesday, 3:06 PM
Grinkle
reacted to
jbriggs444's post
in the thread
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Detection of red-shifted photons near an event horizon
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It is flatly wrong. It assumes a framework of absolute simultaneity -- that everything that happens does so at a particular knowable...
Tuesday, 3:06 PM
Grinkle
replied to the thread
B
Detection of red-shifted photons near an event horizon
.
Thanks - very helpful and gives me some hooks for further study.
Tuesday, 3:05 PM
Grinkle
reacted to
PeterDonis's post
in the thread
B
Detection of red-shifted photons near an event horizon
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Like
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This works in flat spacetime, but not in curved spacetime; there is no well-defined global concept of "speed" in curved spacetime. What...
Tuesday, 3:05 PM
Grinkle
replied to the thread
B
Detection of red-shifted photons near an event horizon
.
This might be the best way to look at it. My attempts to relate it all back to things I am familiar with may be a dead end.
Tuesday, 2:07 PM
Grinkle
replied to the thread
B
Detection of red-shifted photons near an event horizon
.
This may be a place where if I don't know the math, I am as far as I can come. I'll try to articulate my conceptual problems...
Tuesday, 2:05 PM
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