APOD: Circling a Black Hole at its Photon... (2013 Jul 02)

Comments and questions about the APOD on the main view screen.
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APOD: Circling a Black Hole at its Photon... (2013 Jul 02)

Post by APOD Robot » Tue Jul 02, 2013 4:09 am

Image Circling a Black Hole at its Photon Sphere

Explanation: What would it look like to go right up to a black hole? One particularly interesting place near a black hole is its photon sphere, where photons can orbit in circles, a sphere 50 percent further out than the event horizon. Were you to look out from the photon sphere of a black hole, half of the sky would appear completely black, half of the sky would appear unusually bright, and the back of your head would appear across the middle. The above computer-animated video depicts this view from the photon sphere. The reason that the lower region, as shown, appears black is because all light paths from this dark region comes up from the black hole -- which classically emits no light. The upper half of the sky now appears unusually bright, blueshifted, and shows increasingly many complete sky images increasingly close to the dark-light divide across the middle. That dark-light divide is the photon sphere -- your location -- and since photons can do circles there, light from the back of your head can circle the black hole and come to your eye. No place on the sky is hidden from you -- stars that would normally pass behind the black hole now appear to zip quickly around an Einstein ring, a ring that appears above as a horizontal line about a quarter of the way down from the video top. The above video is part of a sequence of videos visually exploring the space near a black hole's event horizon. (Disclosure: Video creator Robert Nemiroff is an editor for APOD.)

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Beyond » Tue Jul 02, 2013 4:33 am

Hmm... APOD seems to have started the off in a hole this week, but may be climbing it's way out. I wonder if it's going to be doing that the hole whole week :?: It would seem that if you're in the right spot, you can see what's behind you without turning around, because the light from what's behind you, comes around to be in front of you. Not quite like having eyes in the back of your head, but IF you did have eyes in the back of your head, would you actually see the light from the same thing coming at you from both directions at the same time? That, may be just a bit confusing.
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Boomer12k » Tue Jul 02, 2013 4:55 am

Beyond wrote:Hmm... APOD seems to have started the off in a hole this week, but may be climbing it's way out. I wonder if it's going to be doing that the hole whole week :?: It would seem that if you're in the right spot, you can see what's behind you without turning around, because the light from what's behind you, comes around to be in front of you. Not quite like having eyes in the back of your head, but IF you did have eyes in the back of your head, would you actually see the light from the same thing coming at you from both directions at the same time? That, may be just a bit confusing.
Nah...my optometrist told me the brain would compensate for any of that... :D

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Beyond » Tue Jul 02, 2013 5:08 am

Boomer12k wrote:
Beyond wrote:Hmm... APOD seems to have started the off in a hole this week, but may be climbing it's way out. I wonder if it's going to be doing that the hole whole week :?: It would seem that if you're in the right spot, you can see what's behind you without turning around, because the light from what's behind you, comes around to be in front of you. Not quite like having eyes in the back of your head, but IF you did have eyes in the back of your head, would you actually see the light from the same thing coming at you from both directions at the same time? That, may be just a bit confusing.
Nah...my optometrist told me the brain would compensate for any of that... :D

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by ta152h0 » Tue Jul 02, 2013 5:36 am

ok, that is it. I am junking my state of the art photon torpedo launcher and invest in a new photon sphere..
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by moontrail » Tue Jul 02, 2013 8:25 am

Thought APOD page was not updated today! at first glance it seems quite similar to the last one.

About the image speed, I suposse it tries to be realistic, it isn`t so?

Anyway I would find helpfull, and maybe my optometrist so, a low speed (1/10?) version of the very interesting videos. Thanks to Robert for them.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by bystander » Tue Jul 02, 2013 11:38 am

Yesterday, [url=http://asterisk.apod.com/viewtopic.php?f=9&t=31652#p202483][b]SsDd[/b][/url] wrote:Here is the link to a slower paced version of the video I made a few months ago, using Dr.Nemiroff's simuation.
Click to play embedded YouTube video.
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Ron-Astro Pharmacist » Tue Jul 02, 2013 3:44 pm

Black holes have got to be the most interesting of phenomena we are currently investigating in physics, astronomy and cosmology. I welcome both the last two days of depictions. How black holes interact with photons, one of the three force carries would seemingly tell us much the nature of our universe. It makes me wonder if the other force carriers are similarly altered in that area where gravity is so dominant. That’s probably know; but not by me.

Earlier this week I made a comment about dark matter – tongue-in-cheek. My curiosity often gets the best of me with dark matter too but it interacts with gravity in some way. Photons also have an interaction with gravitational objects such as black holes. Could there be some type of symmetry between the two? Again, probably known or the just an idle daydream of an old ignorant guy.
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by emc » Tue Jul 02, 2013 4:06 pm

If you ever want to get rid of something... throw it in a black hole... and if you get close enough... no one will see you do it.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by geckzilla » Tue Jul 02, 2013 4:11 pm

emc wrote:If you ever want to get rid of something... throw it in a black hole... and if you get close enough... no one will see you do it.
Until someone sets up the all sky black hole observation network. Your x-ray blip will not go unnoticed!
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by emc » Tue Jul 02, 2013 5:47 pm

You are probably right Geckzilla. But we shouldn’t give out too much information... but in this case, I will... “getting rid” implies some sort of criminal intent, therefore, the tip to proceed close enough to not be seen is a tactic to reduce crime.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Beyond » Tue Jul 02, 2013 6:44 pm

emc wrote:You are probably right Geckzilla. But we shouldn’t give out too much information... but in this case, I will... “getting rid” implies some sort of criminal intent, therefore, the tip to proceed close enough to not be seen is a tactic to reduce crime.
ED, doesn't that sort of come under... if a tree falls in the forest, does it make a sound? Well, if a crime is committed and no one sees it, is it still a crime?
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by emc » Tue Jul 02, 2013 7:23 pm

From your vantage in Beyonder Land, you must know that falling trees make sound regardless of human presence... the universe does not revolve around us you know. But how I do wish it were the other way around.

Committing a crime is never off one’s conscious, even if you have a slick defense lawyer with black holes in his/her pockets.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by geckzilla » Tue Jul 02, 2013 7:37 pm

emc wrote:Committing a crime is never off one’s conscious . . .
With exception.
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by RJN » Tue Jul 02, 2013 9:17 pm

A personal comment (that I also posted to my Google Plus stream). What I really like about this video is how the bizarre meets the normal. They really meet, optically, at different horizontal lines across the movie. I remember when I first completed this movie sequence, I thought it was wrong and kept replaying it over and over (and over) in an attempt to figure out why. Then I kept going "OH, I GET IT NOW" after more and more of the motions starting making more and more sense. Now, when giving a talk about this, it might seem like I always knew!

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by emc » Tue Jul 02, 2013 9:45 pm

I am very appreciative of your work Dr. Nemiroff. Although many aspects of astronomy ellude me. At least, I believe I can appreciate the work that went into the video. It is a severity of organized numbers.

I only hope that you are not too dismayed by my attempts at humor amidst what I see as a gathering of very intelligent people.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by emc » Tue Jul 02, 2013 9:50 pm

geckzilla wrote:
emc wrote:Committing a crime is never off one’s conscious . . .
With exception.
Then my black hole trap would be ineffective against a person with no conscious. Without a conscious wouldn't there be no incentive to dispose of evidence? Which brings to mind, is there really such a mental condition as void of conscious?

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by geckzilla » Tue Jul 02, 2013 10:02 pm

Sure. Human brains are as varied as anything on this planet.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Boomer12k » Wed Jul 03, 2013 3:28 am

emc wrote:
geckzilla wrote:
emc wrote:Committing a crime is never off one’s conscious . . .
With exception.
Then my black hole trap would be ineffective against a person with no conscious. Without a conscious wouldn't there be no incentive to dispose of evidence? Which brings to mind, is there really such a mental condition as void of conscious?
I think you might be using the wrong term here...Conscious....or....Conscience....one is a state of awareness...and the other is a sense of right and wrong...."His Conscience bothered him..." for example....which do you mean?

Other than that...Yes....Non-Caring....people with no conscience, don't care...that is an emotional state, and a mental condition. A person of conscience, one who cares...would never do such a thing....

A person of no Conscious, is not aware...or asleep..or knocked out...so, he would not actually BE doing anything...he is incapacitated basically...or "insane"....or like an accident...not aware of his surroundings, in spite of being conscious....

Hope that helps.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Boomer12k » Wed Jul 03, 2013 3:29 am

The effect of Gravity on Spacetime....is to make it CURVED....

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by geckzilla » Wed Jul 03, 2013 3:33 am

I'm sure he knew what he was talking about, Boomer, just a little spelling mistake. :)
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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by Markus Schwarz » Wed Jul 03, 2013 7:54 am

Ron-Astro Pharmacist wrote:It makes me wonder if the other force carriers are similarly altered in that area where gravity is so dominant. That’s probably know; but not by me.
The other fundamental forces, the strong and weak nuclear force, are altered mathematically in the same way as electromagnetism around a black hole. The main difference, however, is that these two forces have a range limited to that of the atomic nucleus, that is 10^-15m. This is different for photon, which can travel over arbitrary long distances. For gravity to significantly effect the nuclear forces, it would have to be strong on the nuclear scale. Put in another way, the black hole's radius would have to be of the order of the proton radius of 10^-15m. Another problem is that the nuclear forces are much harder to calculate with, even without gravity.
Ron-Astro Pharmacist wrote:Earlier this week I made a comment about dark matter – tongue-in-cheek. My curiosity often gets the best of me with dark matter too but it interacts with gravity in some way. Photons also have an interaction with gravitational objects such as black holes. Could there be some type of symmetry between the two? Again, probably known or the just an idle daydream of an old ignorant guy.
Everything that has an energy density interacts with gravity. This is a common property of photons and dark matter. But we have solid experimental evidence that photons and dark matter are different (for instance from the cosmic microwave background). There is the idea of a so-called supersymmetry, which relates different particles to each other, and also explains dark matter. However, recent experimental results (at the LHC for instance) have found no such super-partners, disfavoring supersymmetry.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by moontrail » Thu Jul 04, 2013 7:52 am

bystander wrote:
Yesterday, [url=http://asterisk.apod.com/viewtopic.php?f=9&t=31652#p202483][b]SsDd[/b][/url] wrote:Here is the link to a slower paced version of the video I made a few months ago, using Dr.Nemiroff's simuation.
Click to play embedded YouTube video.
Many thanks to Dr.Nemiroff and "bystander" for the outstanding simulations and postprocess.

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Re: APOD: Circling a Black Hole at its Photon... (2013 Jul 0

Post by emc » Fri Jul 05, 2013 4:59 pm

geckzilla wrote:I'm sure he knew what he was talking about, Boomer, just a little spelling mistake. :)
Thanks for your kind understanding and Boomer’s help. Yes, I meant to spell conscience.