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Imaging a black hole - the EHT


Green Baron
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The "Interstellar" black hole image was based on scientific calculations... BUT, that image is seeing the accretion ring nearly edge on, while the M87 accretion disk is nearly face on. AND (and this is important) the people who made the movie said they deliberately left out some effects predicted by the calculations because they thought the asymmetries would not 'look right' to the movie-going public.

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gargantua makes the assumption of a rather uniform accretion disk. but data trumps predictions. everything else that we dont see in the image is likely due to orientation of the disc in relation to our viewpoint. 

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18 hours ago, Starstruck69 said:

Its not a photo as such. I think image better describes it.

Best description :-)
"Artist's impressions are often created to represent concepts and objects that cannot be seen by the naked eye"

10 hours ago, Brotoro said:

The "Interstellar" black hole image was based on scientific calculations... BUT, that image is seeing the accretion ring nearly edge on, while the M87 accretion disk is nearly face on. AND (and this is important) the people who made the movie said they deliberately left out some effects predicted by the calculations because they thought the asymmetries would not 'look right' to the movie-going public.

citation needed

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4 hours ago, Cassel said:

citation needed

Article from New Scientist :

https://www.newscientist.com/article/dn26966-interstellars-true-black-hole-too-confusing/

Spoiler

Interstellar's true black hole too confusing

 

153
 

SPACE 13 February 2015

Interstellar black hole

Classical and Quantum Gravity, 2015. Reproduced by permission of IOP Publishing

By Jacob Aron

Even black holes wear makeup in Hollywood. Last year’s hit film Interstellar used real scientific equations to depict what happens when a team of space farers venture near a supermassive black hole. Now, a joint paper published in the journal Classical and Quantum Gravity from the movie’s visual effects team and scientific consultant reveal that the real black hole (see above) was deemed too confusing for audiences, and some of the science had to be toned down.

Interstellar’s premise was first conceived by physicist Kip Thorne of the California Institute of Technology, who wanted to make a realistic movie about black holes. He got together with director and co-writer Christopher Nolan, and also with London-based visual effects studio Double Negative to create the movie’s black hole, Gargantua.

“I’d ask him a question and maybe a week later, sometimes a month, I’d get a beautifully presented paper that he’d laid out with references going into the history of the problems I’d been asking about,” says Oliver James, chief scientist of Double Negative.

“We base it in science, but we always give control so that artists can change it”

It’s not the first time physicists have used Albert Einstein’s equations of general relativity to produce images and movies of a black hole’s space-warping properties. But these were much lower resolution and less detailed than a Hollywood production, so the team had to make a few changes. To avoid flickering discontinuities, rather than tracing the paths of individual light rays to generate an image, they used bundles of rays, which serve to smooth out the resulting movie. “That involved quite a lot of research to calculate what would happen,” says James.

Black and blue

The most striking element of Interstellar’sGargantua is its accretion disc, the glowing ring of matter that encircles it. The team started out using a simple, rainbow-coloured flat disc to figure out how it would be warped by the black hole, then exchanged it for a more wispy disc with realistic colours.

The result looked good, but the central black hole seemed to be squashed up against one side. That’s because the movie’s time dilation effects meant the black hole had to spin very fast, causing it to drag the light to one side. Nolan didn’t like this asymmetry and thought moviegoers wouldn’t understand why, so the team slowed it down, says James.

Interstellar black hole Gargantua

Classical and Quantum Gravity, 2015. Reproduced by permission of IOP Publishing

Gargantua’s disc in the movie is also redder and brighter than it would be in real life (see above). As the team worked on the movie, they added levels of scientific detail. They found that the black hole’s rotation turned the glowing red matter a cool blue, thanks to the Doppler effect shortening the wavelength of the light it gave off. It also made one side of the disc much darker, to the point of almost being invisible. Again, Nolan vetoed these details.

“We base it in science, but we always give control so that artists can change it,” says James. “The first images we gave him didn’t have the Doppler shift, and I think he fell in love with them.”

Far from realism

“When I saw the movie, I immediately saw that the black hole did not look as it should for a near maximally spinning black hole,” says Andrew Hamilton of the University of Colorado in Boulder. Now that he has read the paper, he’s glad to see they slowed it down for a reason. “I had not realised just how careful the Interstellarteam had been with their renderings.”

Alain Riazuelo of the Paris Institute of Astrophysics says he appreciates the team’s efforts, but a pure science project would have done things differently, because astronomers want to create models of what their telescopes might see from afar. “From an astrophysics perspective you would want to simulate different configurations of matter around the black hole, then try to predict what your observations would give you,” he says – the team just choose a disc they thought looked nice.

Riazuelo met with Thorne a few years ago and gave him some early visualisations, so was slightly disappointed when the film wasn’t totally realistic. “I understood after a few minutes why they had done this, but I would have preferred they stick a little more close to realism,” he says, though it could have been much worse. “You should keep in mind there was nothing that obliged Christopher Nolan to try to stick to realistic science.”

The techniques developed for Interstellar could have unexpected benefits beyond black holes. James says he’s been emailed by researchers on a NASA project planning to study spinning neutron stars who say the team’s equations could help them interpret real astronomical data. “Initially when the film came out everyone was really excited that real science was being used to make films,” says James. “As film makers we’re now really excited that our science might get used in NASA projects to do things we’ve never thought of.”

Journal reference: Classical and Quantum Gravity

Read about the astronomer planning to photograph the black hole at the heart of the Milky Way

Link to the 42-pages long research paper, including a 2m40s long abstract video :

https://iopscience.iop.org/article/10.1088/0264-9381/32/6/065001/

Edited by YNM
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16 hours ago, Cassel said:
On 4/13/2019 at 5:20 PM, Brotoro said:

The "Interstellar" black hole image was based on scientific calculations... BUT, that image is seeing the accretion ring nearly edge on, while the M87 accretion disk is nearly face on. AND (and this is important) the people who made the movie said they deliberately left out some effects predicted by the calculations because they thought the asymmetries would not 'look right' to the movie-going public.

citation needed

The Science of Interstellar, by Kip Thorne, ISBN 978-0393351378, Chapter 9...

"Gargantua's space whirl (space moving toward us on the left and away from us on the right) distorts the disk images. It pushes the disk away from the shadow on the left and toward the shadow on the right, so the disk looks a bit lopsided. (Can you explain why?). To get further insight, Eugénie von Tunzelmann and her team replaced their variant of the color-swatch disk (Figure 9.7) with a more realistic thin accretion disk: Figure 9.9. This was much more beautiful, but it raised problems. Chris did not want his mass audience to be confused by the lopsidedness of the disk and the black-hole shadow, and the shadow's flat left edge, and the complicated star-field patterns near that edge (discussed in Chapter 8). So he and Paul slowed Gargantua's spin to 0.6 of the maximum, making these weirdnesses more modest. (Eugénie had already omitted the Doppler shift caused by the disk's motion toward us on the left and away from us on the right. It would have made the disk far more lopsided: bright blue on the left and dim red on the right—totally confusing a mass audience!)"

TL;DR: The images from Interstellar that some people are treating as scientific gospel were deliberately made wrong by the director and artists for the 'viewing comfort' of an audience who doesn't understand science. Imagine that.

Edited by Brotoro
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18 hours ago, Brotoro said:

The images from Interstellar that some people are treating as scientific gospel were deliberately made wrong by the director and artists for the 'viewing comfort' of an audience who doesn't understand science. Imagine that.

If they had applied special relativity and doppler shift, this scene would've looked... confusing.

So actually, for once, I applaud the artistic insight the director had. But it is clear proof that the scene is made for cinematic purpose, and not for scientific truthfulness. (Cc: @Cassel)

Edited by YNM
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  • 3 years later...
1 hour ago, Gargamel said:

Did _not_ realize the first images from this telescope were that old... seems fairly recent to me :D

https://www.space.com/milky-way-monster-black-hole-first-image-eht

Sag A* first pics.

Interesting that they claim it as a first confirmation.  I don't remember the name of the researcher but IIRC she confirmed the BH at SagA via stellar images and exceptionally tight orbital paths. 

 

I'll try to find it. 

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I'm curious where they think the orientation of the accretion disk is in relation to the galactic plane. It looks like we're looking closer to the edge than M87 (I certainly hope so, since I wouldn't want to be flying into the poles of a black hole at the wrong time!)

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On 5/12/2022 at 11:41 AM, JoeSchmuckatelli said:

I don't remember the name of the researcher but IIRC she confirmed the BH at SagA via stellar images and exceptionally tight orbital paths. 

 

Andrea Ghez, and she won a Nobel for it.  

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7 hours ago, cubinator said:

Today I was happy to be able to show TWO pictures of black holes in the planetarium.

Both were totally black, because they were depicting the central area in great resolution.

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  • 2 weeks later...
On 5/12/2022 at 5:07 PM, cubinator said:

I'm curious where they think the orientation of the accretion disk is in relation to the galactic plane. It looks like we're looking closer to the edge than M87 (I certainly hope so, since I wouldn't want to be flying into the poles of a black hole at the wrong time!)

Wdym at the wrong time? The relativistic jets don't necessarily stop.

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2 hours ago, Bej Kerman said:

Wdym at the wrong time? The relativistic jets don't necessarily stop.

Well the Earth could have been in an orbit that flies through a jet at some point in the future, or doing it right now, or not at all.

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