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Last edited by shunyadragon; 04-12-2019, 09:48 AM.Glendower: I can call spirits from the vasty deep.
Hotspur: Why, so can I, or so can any man;
But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:
go with the flow the river knows . . .
Frank
I do not know, therefore everything is in pencil.
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I was wondering what ‘shadow’ meant.
When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42±3 μas, which is circular and encompasses a central depression in brightness with a flux ratio 10:1. The emission ring is recovered using different calibration and imaging schemes, with its diameter and width remaining stable over four different observations carried out in different days. Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M=(6.5±0.7)×109 Me. Our radio- wave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible.
Some special characters lost in translation.
Some addition reading needed!Last edited by firstfloor; 04-12-2019, 10:45 AM.“I think God, in creating man, somewhat overestimated his ability.” ― Oscar Wilde
“And if there were a God, I think it very unlikely that He would have such an uneasy vanity as to be offended by those who doubt His existence” ― Bertrand Russell
“not all there” - you know who you are
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Originally posted by firstfloor View PostI was wondering what ‘shadow’ meant.
https://iopscience.iop.org/article/1...41-8213/ab0ec7
Some special characters lost in translation.
Some addition reading needed!
Below is an annotated photo of the cluster, with m87 found in the lower center portion.
Virgo-Cluster-galaxies-768x768.jpg
below is a high resolution image of the jet from the black hole:
The-radio-jet-of-the-elliptical-galaxy-M87-is-also-visible-in-the-optical-range-Detailed.jpg
JimLast edited by oxmixmudd; 04-12-2019, 12:32 PM.My brethren, do not hold your faith in our glorious Lord Jesus Christ with an attitude of personal favoritism. James 2:1
If anyone thinks himself to be religious, and yet does not bridle his tongue but deceives his own heart, this man’s religion is worthless James 1:26
This you know, my beloved brethren. But everyone must be quick to hear, slow to speak and slow to anger; James 1:19
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Originally posted by Sparko View PostWhy did they try to photograph one so far away instead of something closer? Like Sagittarius A-Star?
Black holes are interesting in that since their diameter is determined by the escape velocity being c (the speed of light), their diameter scales linearly with their mass, not with the square-root of their mass like most normal objects. So The black hole in the center of our galaxy, while only 26,000 ly away, is, at 4.5 million solar masses, about 10 time the diameter of the sun. OTOH, the 6.5 billion solar mass black hole in the center of m87 is 1500 times larger, about the size of our entire solar system. So it turns out there really isn't as much difference in their apparent size (about 50uarcsecs for sagitarius A and about 40uarcsec for the m87 black hole) as one might expect, because m87, though 2000 times farther away, is about 1500 times bigger.*
Jim
*lots of rounding with the numbers ... just concerned about orders of magnitude in this case.Last edited by oxmixmudd; 04-12-2019, 01:15 PM.My brethren, do not hold your faith in our glorious Lord Jesus Christ with an attitude of personal favoritism. James 2:1
If anyone thinks himself to be religious, and yet does not bridle his tongue but deceives his own heart, this man’s religion is worthless James 1:26
This you know, my beloved brethren. But everyone must be quick to hear, slow to speak and slow to anger; James 1:19
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Originally posted by oxmixmudd View PostThey actually did Image Sagittarius A (the milky way's central black hole), but our galaxy's heart is not active like m87, and so the image looks a bit more like a half-circle than the nice silhouette from m87.
Black holes are interesting in that since their diameter is determined by the escape velocity being c (the speed of light), their diameter scales linearly with their mass, not with the square-root of their mass like most normal objects. So The black hole in the center of our galaxy, while only 26,000 ly away, is, at 4.5 million solar masses, about 10 time the diameter of the sun. OTOH, the 6.5 billion solar mass black hole in the center of m87 is 1500 times larger, about the size of our entire solar system. So it turns out there really isn't as much difference in their apparent size (about 50uarcsecs for sagitarius A and about 40uarcsec for the m87 black hole) as one might expect, because m87, though 1500 times bigger, is about 2000 times farther away.
Jim
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Originally posted by Sparko View PostYeah I always wondered how you could have a "bigger" black hole if they were all singularities with no size at all. The event horizon would change with the mass but the size of the singularity would always be at zero. Which is just weird. Where IS the mass then?
JimLast edited by oxmixmudd; 04-12-2019, 01:23 PM.My brethren, do not hold your faith in our glorious Lord Jesus Christ with an attitude of personal favoritism. James 2:1
If anyone thinks himself to be religious, and yet does not bridle his tongue but deceives his own heart, this man’s religion is worthless James 1:26
This you know, my beloved brethren. But everyone must be quick to hear, slow to speak and slow to anger; James 1:19
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This "telescope" is going to grant us a better look at the might and majesty of God's creation. If nothing else that is way cool.
I'm always still in trouble again
"You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
"Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
"Of course, human life begins at fertilization that’s not the argument." --Tassman
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Originally posted by oxmixmudd View PostThey actually did Image Sagittarius A (the milky way's central black hole), but our galaxy's heart is not active like m87, and so the image looks a bit more like a half-circle than the nice silhouette from m87.
Black holes are interesting in that since their diameter is determined by the escape velocity being c (the speed of light), their diameter scales linearly with their mass, not with the square-root of their mass like most normal objects. So The black hole in the center of our galaxy, while only 26,000 ly away, is, at 4.5 million solar masses, about 10 time the diameter of the sun. OTOH, the 6.5 billion solar mass black hole in the center of m87 is 1500 times larger, about the size of our entire solar system. So it turns out there really isn't as much difference in their apparent size (about 50uarcsecs for sagitarius A and about 40uarcsec for the m87 black hole) as one might expect, because m87, though 2000 times farther away, is about 1500 times bigger.*
Jim
*lots of rounding with the numbers ... just concerned about orders of magnitude in this case.
JimMy brethren, do not hold your faith in our glorious Lord Jesus Christ with an attitude of personal favoritism. James 2:1
If anyone thinks himself to be religious, and yet does not bridle his tongue but deceives his own heart, this man’s religion is worthless James 1:26
This you know, my beloved brethren. But everyone must be quick to hear, slow to speak and slow to anger; James 1:19
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I was introduced to the idea of black holes in a book by Alan Dean Foster, "The End of the Matter". I don't care much for his style but the book's plot around the black hole was interesting.
I don't really know WHY black holes would exist but they sound interesting.Watch your links! http://www.theologyweb.com/campus/fa...corumetiquette
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Originally posted by DesertBerean View PostI don't really know WHY black holes would exist but they sound interesting.Glendower: I can call spirits from the vasty deep.
Hotspur: Why, so can I, or so can any man;
But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:
go with the flow the river knows . . .
Frank
I do not know, therefore everything is in pencil.
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Originally posted by DesertBerean View PostI was introduced to the idea of black holes in a book by Alan Dean Foster, "The End of the Matter". I don't care much for his style but the book's plot around the black hole was interesting.
I don't really know WHY black holes would exist but they sound interesting.
It turns out that when a big enough star goes supernova it is indeed possible to get enough mass into that small a space, and once that happens, there is no way to undo it, at least not in the lifetime of our universe so far.
Galaxies all seem to have at their cores really big black holes. Though we dont yet know which came first, the black hole or the galaxy.
JimLast edited by oxmixmudd; 04-13-2019, 01:16 PM.My brethren, do not hold your faith in our glorious Lord Jesus Christ with an attitude of personal favoritism. James 2:1
If anyone thinks himself to be religious, and yet does not bridle his tongue but deceives his own heart, this man’s religion is worthless James 1:26
This you know, my beloved brethren. But everyone must be quick to hear, slow to speak and slow to anger; James 1:19
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Originally posted by oxmixmudd View PostI guess in one sense they exist because nothing can go faster than light, and because of how gravity works. The more mass you can get into a certain volume of space, the stronger the gravity. The stronger the gravity, the faster you have to be moving to get away from the thing itself, and the faster you have to move to stay in orbit. So basically, if you can pack enough mass into a small enough space, you have to be able to go faster than light to get away or to orbit. And since nothing can go faster than light, all you can do is fall in. And that goes for light itself. Hence 'black hole'.
It turns out that when a big enough star goes supernova it is indeed possible to get enough mass into that small a space, and once that happens, there is no way to undo it, at least not in the lifetime of our universe so far.
Galaxies all seem to have at their cores really big black holes. Though we dont yet know which came first, the black hole or the galaxy.
Jim
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