Unveiling the first-ever image of a black hole [video] • Hacker News Board

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

#221

Post by greeneggs » Wed, Apr 10, 2019, 4:03 PM UTC

fsakura wrote: post #160

I always thought we have photographed black holes. Any idea/link to article where it explains why this took so long and why it was difficult?

Here's an NY Times article about the project:

https://www.nytimes.com/2018/10/04/magazine/how-do-you-take-...

The author, Seth Fletcher, also wrote a book about it, "Einstein's Shadow: A Black Hole, a Band of Astronomers, and the Quest to See the Unseeable", if you want more details.

https://www.goodreads.com/book/show/36300597-einstein-s-shad...

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

#222

Post by kristofferR » Wed, Apr 10, 2019, 4:03 PM UTC

The US unveiling is WAY better than the EU unveiling that is linked to above. They have images, animations and graphs that's easily understandable by the layperson, and it's scientists instead of politicians speaking.

https://www.youtube.com/watch?v=2DxjuE7WDlk

They talk about how the image was produced, and how they made such a small image out of the 5 PetaByte of data they gathered from stations all over the world.

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

#223

Post by GuB-42 » Wed, Apr 10, 2019, 4:04 PM UTC

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

Smart move by Veritasium, making a video commenting the news just before the news actually happens. Time works in weird ways around black holes.

Anyways, it is a good one. So is that channel in general.

It is also a good video if you just watched Interstellar, because it also explains why the black hole looks the way it does in the movie. Note that the movie black hole rendering is slightly incorrect for artistic reasons, the video shows the more scientifically accurate version.

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

#224

Post by trickstra » Wed, Apr 10, 2019, 4:04 PM UTC

Pigo wrote: post #206

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

Not sure if I missed it, but can we tell which way the accretion disk is from our view of it?

perpendicular - we see it almost exactly from the top. Mentioned during the Q&A (41:33 to be exact)

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

#225

Post by the8472 » Wed, Apr 10, 2019, 4:04 PM UTC

fsakura wrote: post #160

I always thought we have photographed black holes. Any idea/link to article where it explains why this took so long and why it was difficult?

There have been plenty of indirect observations such as their jets, stars in very tight orbits around Sagittarius A*, xray binaries etc.

This is a direct observation of the immediate environment of a black hole, i.e. its accretion disk and other light bent around it.

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

#226

Post by dugluak » Wed, Apr 10, 2019, 4:04 PM UTC

Can the equipment used from several places on earth for this be deployed in space (may be to a geostationary orbit)? Not thinking about cost for a moment is this a far-fetched thought or such a thing is technically possible.

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

#227

Post by kristofferR » Wed, Apr 10, 2019, 4:05 PM UTC

zaph0d_ wrote: post #117

Are there any papers already out which focus on the technical aspect of reconstructing the image? I heard that they analyzed 3.5 Petabytes of data for this.

5 PB. The American unveiling focus on just what you talk about: https://www.youtube.com/watch?v=2DxjuE7WDlk

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

#228

Post by chicob » Wed, Apr 10, 2019, 4:08 PM UTC

ckugblenu wrote: post #46

The EU is finally learning from the US when it comes making a lot of fanfare for discoveries and other inventions.

Why is the European Commission doing this? When I recognized Carlos Moedas I immediately skipped to what mattered. The reason why he was ever appointed as Commissioner for Research, Science and Innovation is, to me, more remote than the black hole about which he knows absolutely nothing.

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

#229

Post by 317070 » Wed, Apr 10, 2019, 4:08 PM UTC

thanatropism wrote: post #49

hrdwdmrbl wrote: post #32

Earlier quoted context omitted.

Does that image have a weird pulsing optical illusion for anyone else?

It's the color scheme. I think in matplotlib it's called "hot". I do a lot of 2D kernel density plots that by having a black zero level and dozens of contour levels produce a smooth look with aesthetics similarities to this. I used to use that scheme because "heatmaps" but stopped because of the pulsing illusion. I'm not sure if this image is real color or just lightness value and they used a color scheme for drama.

It's the latter. This is an image in radio-frequency brightness of the object, so not visible frequencies of light. But yeah, it also looks like the 'hot' colormap to me.

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

#230

Post by wallace_f » Wed, Apr 10, 2019, 4:09 PM UTC

bdamm wrote: post #212

wallace_f wrote: post #193

Earlier quoted context omitted.

Ok, wait a second. I liked a lot of this video, but there are some aspects which are kind of ridiculous. He says his reason for his confidence in this prediction is "I think it's going to look like a fuzzy coffee mug stain." He doesn't give an actual reason. He does talk a lot about theory, a lot of it interesting and novel to me, but by the end of the video, most of this theory suggests a different-looking image!

The entire video is his description of the reasons for why it'll look like a fuzzy coffee mug stain. It's "fuzzy" because of the low resolution, not because the black hole itself is fuzzy. Undoubtedly there will be work to improve the best quality photograph of a black hole, now that we have one at all.

That's not correct. Around 25% of the video is discussion around the concept of the radius of photon sphere to the event horizon, and what constitutes the light surrounding the photon sphere (one explanation he gives is that there are infinite reflections). Then he spends the last 30% of the video talking about reflections of the acretion disk. This is the theory that he never included in his original prediction, but doesn't explain why he made that call.