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Unveiling the first-ever image of a black hole [video]

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Re: Unveiling the first-ever image of a black hole [video]

#271

Post by kaycebasques »

JumpCrisscross wrote: post #27

Good video that correctly predicted the image and describes why it looks the way it does [1]. TL; DR The dark area is the entire surface of the event horizon, including the side facing away from us, plus some more due to photons missing the event horizon "directly" being drawn in. One side is brighter due to its being Doppler boosted. [1] https://www.youtube.com/watch?v=zUyH3XhpLTo

I just stumbled upon Veritasium a week ago while learning about the double slit experiment in quantum theory and trying to see some actual evidence [1] of the experiment.

[1]: https://youtu.be/Iuv6hY6zsd0

Re: Unveiling the first-ever image of a black hole [video]

#272

Post by jazzyjackson »

chirau wrote: post #269

MASSSIVELY UNDERWHELMING As a person who has no interest in these intergalactic shenanigans, it looks just like another ball on fire. I wanted to be excited, I really was, but this is just another picture. A giant leap for mankind, and i fully recognize that, but the awe... nada. It's just another picture really. There is nothing fascinating about it. Hats off to the people who brought this to us though. I know gravi…

If it fails to pique your interest, oh well, but the more you read about black holes and what is observable about them, the stranger it feels to be looking at it face to face.

Re: Unveiling the first-ever image of a black hole [video]

#273

Post by ceejayoz »

shireboy wrote: post #261

I understand this was done by coordinating multiple telescopes to create a virtual earth size scope. Why is this not done more? It seems like cloud services would make this relatively easy to share bits technically. Are the issues mostly political or are there tech issues making this harder to do more often? Tangential question: if we can do this with an earth-size virtual scope, what could we do with a larger one? S…

It's been done since the 1970s.

https://en.wikipedia.org/wiki/Astronomical_interferometer

There are some proposals to do it in space.

https://www.universetoday.com/139566/instead-of-building-sin...

https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Ant...

Re: Unveiling the first-ever image of a black hole [video]

#274

Post by jcoffland »

ben_w wrote: post #218
forgot-my-pw wrote: post #200

Earlier quoted context omitted.

Einstein predicted the existence of black hole back in early 1915. Pretty amazing.

I thought (relativistic) black holes were first predicted by Schwarzschild in 1916? (As an aside, I have found a whole extra level to nominative determinism since starting to learn German — Schwarzschild = Black shield)

This is also called an aptronym.

https://en.m.wikipedia.org/wiki/Aptronym

Re: Unveiling the first-ever image of a black hole [video]

#275

Post by pavanred »

a_d wrote: post #266

Previous work on this was done for the movie Interstellar. The resolution of the rendering software was so high that team members were able to examine the black hole very closely - Because Gargantua was spinning at almost the speed of light, the rendering showed that spacetime warped into shapes never seen before. This led to the publication of —> https://arxiv.org/abs/1502.03808 Kip Thorne describes his work not thi…

Sean Caroll has a great podcast, mindscape [0]. One of the recent episode featured Kip Thorne as a guest and had some great discussions about Gravitational Waves, Time Travel, and Interstellar [1]. It's a very informative and entertaining podcast, I recommend it.

[0] https://www.preposterousuniverse.com/podcast/

[1] https://www.preposterousuniverse.com/podcast/2018/11/26/epis...

Re: Unveiling the first-ever image of a black hole [video]

#276

Post by jjeaff »

I am not trying to throw cold water on this, but I have some questions.

This ted talk has a very basic explanation of how they constructed this image. I was curious if anyone with image interpolation experience could weigh in on the method. https://www.youtube.com/watch?v=P7n2rYt9wfU

When she first starts explaining their method around 8:00m in, I was initially very skeptical of this result because she said that they feed images of what we "think" a black hole should look like and use algorithms to compare the captured data with those images.

She then goes into explaining the measure they take to keep the resulting image from being biased by passing environmental images and images of other astronomical anomaly to make sure that those images return similar results.

But I can't for the life of me figure out how passing non-stellar imagery could return something similar. And if it does, why do we need to feed it an example of what we think it should look like at all?

Re: Unveiling the first-ever image of a black hole [video]

#277

Post by jjeaff »

noir_lord wrote: post #167
jjeaff wrote: post #119

Earlier quoted context omitted.

So amazing that scientists were able to predict what something would look like that we have never seen before.

It's good science. Been able to make testable predictions and then confirming them or disproving them is the entire (awesome) point.

After having said that, I did a bit more research into how the image was made. I am of course reserving judgement as I don't fully understand the underlying technology. But it sounds like they used an interpolation algorithm to come up with the image based on renderings of what we "think" a black hole should look like. This high level overview from a ted talk goes into how they 'unbias' the data. But it is obviously on a very basic overview: https://www.youtube.com/watch?v=P7n2rYt9wfU

Re: Unveiling the first-ever image of a black hole [video]

#278

Post by vanderZwan »

localhostdotdev wrote: post #238
piker wrote: post #30

Higher resolution official release seems to be: https://www.nsf.gov/news/special_reports/blackholes/download...

editing that image reveals all kinds of details: https://imgur.com/a/TvQsgbA (and I don't even know what I'm doing)

Mind you, that's a JPG you are editing, so in the 8 bit sRGB color space. That means manipulations can lead to errors and illusions due to the color space being non-linear and clipped[0].

The original data was likely linear and at a much higher precision. If the source was a 16 bit linear grayscale PNG for example you could be much more assured you're not seeing the effects of JPG compression and things that were actually measured.

EDIT: Found better sources:

16-bit sRGB PNG: https://eventhorizontelescope.org/files/eht/files/20190410-7...

180 MiB original TIFF: https://www.eso.org/public/images/eso1907a/

[0] https://www.youtube.com/watch?v=LKnqECcg6Gw

Re: Unveiling the first-ever image of a black hole [video]

#279

Post by ttul »

chirau wrote: post #269

MASSSIVELY UNDERWHELMING As a person who has no interest in these intergalactic shenanigans, it looks just like another ball on fire. I wanted to be excited, I really was, but this is just another picture. A giant leap for mankind, and i fully recognize that, but the awe... nada. It's just another picture really. There is nothing fascinating about it. Hats off to the people who brought this to us though. I know gravi…

Perhaps consider this: "VLBI allows the EHT to achieve an angular resolution of 20 micro-arcseconds — enough to read a newspaper in New York from a sidewalk café in Paris [6]."

What's surprising about this image is how utterly microscopic the thing is that was observed - from our location. The width of the event horizon is 40 billion kilometers. That's only 267x the diameter of our orbit around the Sun. But the M87 black hole is 26,000 light years away. 26,000 light years is 2.45979e+17 km, or 639,903,746,098 times farther away than the moon.

Re: Unveiling the first-ever image of a black hole [video]

#280

Post by muterad_murilax »

zenzen wrote: post #241
muterad_murilax wrote: post #236

Earlier quoted context omitted.

If we see it almost exactly from the top, then why is one half of the ring so much brighter than the other?

Relativistic beaming! https://youtu.be/zUyH3XhpLTo?t=490

Already watched the video, thanks. However in his example the disk is not perpendicular to the viewer so the beaming makes more sense there I think.

On the other hand, "almost exactly from the top" is not the same as "exactly from the top".

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