HN Theater @HNTheaterMonth

If the black hole is not spinning, it should look the same from every angle. A spinning black hole is deformed (like the spinning Earth.)

Anyway, we are not seeing the black hole (because it looks just like a black circle in front of a black background). The interesting part of the image is a disk of material spinning around it. There is a nice 3d cardboard simulation and clear explanation in a video by Veritasium https://www.youtube.com/watch?v=zUyH3XhpLTo

Veritasium made an excellent youtube video explaining how this effect works (before the image was released!) https://www.youtube.com/watch?v=zUyH3XhpLTo

There's a clearer explanation of why the disk looks that way and how the gravitational warp makes those light paths https://www.youtube.com/watch?v=zUyH3XhpLTo

Derek explains the physics in a reasonably understandable manner in this video on his Youtube channel: https://www.youtube.com/watch?v=zUyH3XhpLTo

⬐ wruza

So, at 6:38 he says that we would mostly see just a disk, if viewing strictly from the jet vector, yet PaulHoule’s comment fades below and the original empath75’s is intact. For now I assume there is some relativistic effect in action which makes me see them this way.

⬐ michaelcampbell

I've watched it, but his explanation (which is the best I've seen; don't misread me), basically goes into why it looks "thus" when viewed edge-on of the accretion disk. But there are as few like that as there are viewed from the poles; so why do they ALL look like this?

If that's just the way it is I'll accept it, but I haven't heard or seen a good explanation yet.

This video by Derek Muller (Veritasium) helped me understand this phenomenon.

https://www.youtube.com/watch?v=zUyH3XhpLTo

⬐ woogiewonka

The article states that the photon sphere does not exist, therefore his explanation is incorrect.

A very good explanation on what we are looking at: https://www.youtube.com/watch?v=zUyH3XhpLTo

> Then the data was compiled and rendered into an image

A digital camera is just an array of tiny sensors that detect how much light hit them and a computer takes those values and renders an image from them.

> you really think it's that bright?

If you take a photo in a dark room with increased exposure then the resulting image is brighter than what you see with your own eyes. This was taken over a long period of time, effectively a long exposure. If you were close enough to see it at the scale you are seeing it on your computer screen it would probably be far brighter.

> How about orange?

As mentioned in another comment on this thread, it's just the colour scheme used in the output to show the brightness differences. The accretion disk is not necessarily orange, this photo is essentially greyscale mapped to a black -> orange -> white scale.

This is just an array of relatively large sensors with very high exposure gathering information from something very far away and combining that data in greyscale.

> I wonder why it's not symmetrical?

See Veritasium's video [1] on why it looks like it does, in short, the effects of the black hole and our angle to the accretion disk.

[1] https://www.youtube.com/watch?v=zUyH3XhpLTo

The black hole itself is spherical, but the light we're seeing around it isn't projected by the event horizon; rather, it's light from behind/around the black hole that isn't blocked. This video explains in much more detail: https://www.youtube.com/watch?v=zUyH3XhpLTo

⬐ usaphp

But if it's spherical, should not the light be all around it?

⬐ Neeek

The light is emitted from an accretion disk, which does not envelope the entire sphere.

⬐ codethief

Actually, this particular black hole is (probably) not exactly spherically symmetric but only axisymmetric since it is rotating (i.e. it is a so-called Kerr black hole). But disregard the lack of spherical symmetry for a moment (it can still be approximated quite well by a sphere for our purposes, see below), the crucial points are the following:

1. Along with its rotation comes the fact that the black hole drags the surrounding spacetime along with it (whatever this means), including matter. So matter near such a Kerr black hole will start orbiting it automatically. Closely related(×) to this is the fact that, in the close vicinity of a black hole, you typically find a so-called accretion disk of matter that is orbiting the black hole and slowly being eaten by it, while also emitting light because the infalling matter is heating up in the process. Now, the important point is that the disk is really a disk, though(!), meaning that it doesn't completely surround the black hole in all directions, so there are (lots of) angles from which you could actually "look at" the black hole and your view would not be (entirely) blocked by the matter (and the light it emits). I hope this answers your question as to whether the light "should not […] be all around it".

2. In the case of M87 it seems like the axis of rotation is pretty much parallel to our line of sight, meaning that we're actually looking at the black hole "from above" and that our line of sight is pretty much perpendicular to the accretion disk surrounding the hole. In particular, this means we get to see the accretion disk and the black hole's "bald head" in their full glory. Moreover, since we're looking at the black hole "from above", its slight deviation from spherical symmetry doesn't matter and it still looks like a disk to us due to its rotational symmetry in the direction in which it rotates. (Think of how a cylinder looks like a disk/sphere from above.)

(×) To be precise, infalling matter often carries angular momentum (as measured with respect to the black hole's location), i.e. it doesn't fall into the black hole exactly radially but rather sideways, possibly after having orbited the black hole multiple times. This means that when it finally gets absorbed by the black hole, the latter will absorb the matter's angular momentum, too, and start spinning.(××) So the rotation of the black hole, on the one hand, and of the matter outside, on the other hand, are tightly coupled phenomena and disentangling what came first is a "chicken or egg" kind of problem.

(××) Side note: Infalling matter transferring angular momentum to a black hole is the reason why we expect most, if not all black holes in nature to carry angular momentum, i.e. to be of the (axisymmetric) Kerr type instead of the simpler (non-rotating and perfectly spherically symmetric) Schwarzschild type.

⬐ tempestn

If it were emitting the light, yes, but it's not. It's more complicated than this, but imagine holding a black sphere in front of a light bulb. You'll see a ring of light around the sphere.

Somewhat separately, there's the accretion disk, which again is a disk not a sphere, much like other orbiting systems like solar systems or galaxies−the gravity between bodies orbiting the same central gravity source causes them to arrange roughly into a plane, rather than all having their own unrelated orbits. We're not seeing the accretion disk directly though, but rather the light from it, and from other sources, that is able to pass around the black hole. (ie the black sphere in front of the light bulb.)

Watch that video; it explains it in a very approachable way.

This was a great explanation:

https://www.youtube.com/watch?v=zUyH3XhpLTo

It's really amazing that human mind can predict and tell the things without even seeing it.

How come we even know and predicted the radius and things far away in galaxy without even seeing it. It's just amazing. Wow it just amazes you that scientist even have predicted the radius of thing and how it work etc.[1]

[1] https://www.youtube.com/watch?v=zUyH3XhpLTo

If you mean the brightness asymmetry, it's because the accretion disc is spinning. This video predicts pretty well all of the features we expected to find, and it lines up with the actual image.

https://www.youtube.com/watch?v=zUyH3XhpLTo

And a really great explanation of why it looks the way it does:

https://www.youtube.com/watch?v=zUyH3XhpLTo

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

⬐ mrandish

Wow, the video you posted is even more informative and clear than the actual press conference, and it was created by someone who hadn't even seen the image yet based purely on the mathematical predictions of what we would see.

Kind of sad that after all the amazing effort and resources that have gone into the creating the image that the international team couldn't have featured an explanation as clear as this in their actual press conference.

⬐ teej

Different target audiences for a science YouTube channel and a scientific findings press conference.

⬐ rtkwe

It'd be extremely shocking if he hadn't been able to. The math has been known for a very long time the largest differences would be based on the orientation of disk relative to us but that has been mostly known since the original Hubble picture. If he'd been significantly wrong that'd mean our understanding of the physics was wrong or something unknown was happening at a pretty large scale.

⬐ jessriedel

Everyone knew what the image was going to look like, so it's not any harder to prepare in advance.

⬐ arriu

The video by Veritasium is by a guy who literally got a PHD on the subject of making physics more approachable through videos. He is exactly the person I would expect to provide a more clear and understandable explanation.

https://www.youtube.com/watch?v=S1tFT4smd6E&feature=youtu.be...

⬐ rexpop

Why doesn't he work with the actual astronomers, then?

⬐ cicloid

Just by sharing the news he is working with them helping the global effort.

⬐ code_duck

Because he’s busy making physics more approachable through videos.

⬐ rexpop

Perhaps I should have phrased it as "why don't astronomers work with _him_?"

⬐ mgalgs

You don't have to watch his channel for very long to learn that he often does (see his video about the recent gravitational wave detection [1], plus a bunch more).

[1] https://youtu.be/iphcyNWFD10

⬐ awb

Here's the follow up video after the image was released: https://www.youtube.com/watch?v=S_GVbuddri8

⬐ jjeaff

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

⬐ forgot-my-pw

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

⬐ ben_w

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)

⬐ dmix

It's a little of both, but yes Schwarzschild technically first predicted them.

> In 1915, Albert Einstein developed his theory of general relativity, having earlier shown that gravity does influence light's motion. Only a few months later, Karl Schwarzschild found a solution to the Einstein field equations, which describes the gravitational field of a point mass and a spherical mass.

https://en.wikipedia.org/wiki/Black_hole#History

⬐ limbicsystem

Or was it the Revd. John Michell? https://en.wikipedia.org/wiki/John_Michell

⬐ TheOtherHobbes

Michell. And maybe Laplace.

Of course they "invented" Newtonian black holes, not relativistic black holes.

Even so - well ahead of the rest.

⬐ jcoffland

This is also called an aptronym.

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

⬐ WhitneyLand

Einstein first developed the theory and the equations that allowed for them to be discovered.

You can imagine that space-time equations have many solutions and properties that can't be contemplated all at once even having them right in front of you.

Schwarzschild took the equations and obsessed over them for countless hours and eventually discovered that one solution to them implied this phenomenon and therefore he discovered black holes by discovering a specific solution to Einstein's equations.

Of course no one knew at the time if the mathematical solution represented real physical objects that exist in the universe, because it doesn't always happen that way. Occasionally some obscure corner of the math predicts something that's a dead end or anomaly that doesn't have any meaning of value as far as it is known.

They had no way to know one possibility from the other.

⬐ noir_lord

It's good science.

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

⬐ trickstra

ad Good science, I just randomly bumped into this video today that very nicely explains the differences between good science and bad science. https://www.youtube.com/watch?v=umo6pMCkcXs (safely skip the first 3 minutes)

⬐ jjeaff

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

⬐ codethief

Not sure why you're getting downvoted because (as a physicist) I'd say that especially in the face of a high-level discovery like today's, a healthy amount of scepticism is a good thing.

That being said, it seems your concerns are being addressed in the TED talk you linked to from 8:45 onward?

Moreover, in the NSF press conference today it was said that they had four different teams in four different locations across the globe last year, working on interpolating the data and generating the images and they basically asked the teams to lock themselves in, i.e. to not communicate with each other at all, and use (more or less) whatever interpolation algorithm they thought would fit the data best. And at the end, when the four teams met up last year, they had supposedly arrived at very similar-looking images.

I briefly(!) looked at the papers that were published today ("First M87 Event Horizon Telescope Results" I-VI) and while I'm anything but an expert when it comes to radioastronomy and imaging technology (I'm more a theoretical physics/mathematical general relativity kind of guy), I came across the following statements which, to me, all suggest that they've at least evaluated the data with due diligence (emphases all mine):

"IV. Imaging the Central Supermassive Black Hole" (https://iopscience.iop.org/article/10.3847/2041-8213/ab0e85):

Section 5.2 confirms the statements from the press conference today:

> The imaging teams worked on the data independently, without communication, for seven weeks, after which teams submitted images to the image comparison website using LCP data (because the JCMT recorded LCP on April 11). After ensuring image consistency through a variety of blind metrics (including normalized cross-correlation, Equation (15)), we compared the independently reconstructed images from the four teams.

> Figure 4 shows these first four images of M87. All four images show an asymmetric ring structure. For both RML teams and both CLEAN teams, the ring has a diameter of approximately 40 μas, with brighter emission in the south. In contrast, the ring azimuthual profile, thickness, and brightness varies substantially among the images. Some of these differences are attributable to different assumptions about the total compact flux density and systematic uncertainties (see Table 2).

Section 6, in turn, confirms the statements from the TED talk:

From the introduction to section 6:

> To explore the dependence of the reconstructed images on imaging assumptions and impartially determine a combination of fiducial imaging parameters, we introduced a second stage of image production and analysis: performing scripted parameter surveys for three imaging pipelines. To objectively evaluate the fidelity of the images reconstructed by our surveys—i.e., to select imaging parameters that were independent of expert judgment—we performed these surveys on synthetic data from a suite of model images as well as on the M87 data. The synthetic data sets were designed to have properties that are similar to the EHT M87 visibility amplitudes (e.g., prominent amplitude nulls). This suite of synthetic data allowed us to test the scripted reconstructions with knowledge of the corresponding ground truth images and, thereby, select fiducial imaging parameters for each method. These fiducial parameters were selected to perform well across a variety of source structures, including sources without the prominent ring observed in our images of M87.

From section 6.2:

> We then reconstructed images from all M87 and synthetic data sets using all possible parameter combinations on a coarse grid in the space of these parameters. We chose large ranges for each parameter, deliberately including values that we expected to produce poor reconstructions.

Finally, in the caption of figure 4 of "I. The Shadow of the Supermassive Black Hole" (https://iopscience.iop.org/article/10.3847/2041-8213/ab0ec7) they write:

> Note that although the fit to the observations is equally good in the three cases, they refer to radically different physical scenarios; this highlights that a single good fit does not imply that a model is preferred over others

…which, assuming that I'm understanding this correctly, means that the bias in the fits towards one model over another is low.

--

Again, I cannot stress enough that I've only skimmed the papers but from what I did read, I see no good reason not to trust their results.

⬐ salty_biscuits

This sort of reconstruction problem from VLBI measurements is under-determined so you need to insert priors/regularization to get anything at all. The priors in this case are pretty weak (from a quick read of the CHIRP paper). https://arxiv.org/pdf/1512.01413.pdf

⬐ sandworm101

Indeed. Whenever you go looking for something you think is already exists, as opposed to stumbling across an object, there is a danger that the parameters of your search will favor your preconceived notions. One will also tend to describe observed objects in terms that tends to fit your theory. I'm not saying that happened here just that it is a danger.

Astronomy/cosmology is one of those strange disciplines where rather than discover new objects in situ, one discovers their possibility in the mathematics and then goes out to find them. So I and many others were hoping that this image was radically different than the math, potentially opening the door to some new theories. Confirmation just isn't as much fun as raw discovery of the unknown. Example: the recent "cannonball star" observations. We are going to need some new science to explain how that is a thing.

⬐ vbuwivbiu

The Event Horizon Telescope site has had predicted images up for ages https://eventhorizontelescope.org/science

⬐ z3t4

Side observation: This video, and the video you linked to got two million views in just a few hours. I didn't know black holes where this popular. (market opportunity here)

⬐ int_19h

It's a very well made pop-sci video, which probably substantially increases the likelihood of it being reshared.

⬐ eu

If one needs an intro, this video should be watched before watching the press release..

⬐ Abishek_Muthian

In the video he talks about the Schwarzchild radius but doesn't go into details. It is the distance from the center of the black hole to the event horizon.

Anything which is not in that radius or not already in a path towards it should be safe from not getting sucked by the black hole.

E.g. If our sun becomes a black hole, Schwarzchild radius would be 2.954Km i.e. anything outside ~3Km would be safe.

This was explained in the scishow video on that topic[1].

[1]:https://youtu.be/Mm_ks1ce3C4

⬐ Retric

That “not already on a path towards it” is very misleading. A random object passing anywhere near the Schwarzchild radius is will be eaten by the black hole. The only way for something to escape ‘at 3km’ is for an object falling into a back hole to emit light which just happens to be pointing in the opposite direction from the black hole.

Even light can’t orbit at that distance.

⬐ ben_w

That’s an oversimplification. The Schwarzschild radius is where to find an uncharged & non-rotating black hole’s event horizon, and the event horizon is the surface at which newly generated photos (and all causal influences) can no longer escape.

The innermost stable circular orbit is further out than the event horizon, 3 times the Schwarzschild radius IIRC. Anything closer to that has an unstable orbit.

⬐ mattfrommars

If the general theory of relatively was tested again and it proved to provide the next result, what does it say about actually is an black hole?

Thus far, from all the experiment and result observed, the theory has been proven to be correct.

Hence, it can be said with 99% certainty whatever it predicts must be correct. I hope it does mention about possibility of creating a worm hole.

⬐ r_c_a_d

No, that is not how science works. We can say with 100% certainty that the theory has not been falsified by any test to date.

⬐ SiempreViernes

A very good (technical) talk about the EHT project and the physics they try to do here: https://www.youtube.com/watch?v=JiS1OJNBrvk

It is a bit old (2012), but comprehensive and with both good audio and readable* slides.

*: In the sense that you can see the letters on them

⬐ jtr_47

Another link describing what a black hole is:

Part I: https://www.youtube.com/watch?v=VnJYo6LKzgA

Part II: https://www.youtube.com/watch?v=Nlry6LqWwJ0

Peace

⬐ kaycebasques

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

⬐ Pigo

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

⬐ return0

apparently from the top. i hope we get to find another one sideways because they look cool ;)

⬐ trickstra

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

⬐ pjungwir

The video JumpCrisscross shared above says this is the black hole at the center of our galaxy, so why isn't its accretion disk oriented the same as the rest of the galaxy? Isn't that weird?

⬐ alpaca128

It's actually in a galaxy called Messier 87 which is 55 million lightyears away.

⬐ manigandham

The observed both supermassive black holes at the center of M87 and our Milky Way galaxy Sagittarius A

⬐ wahern

And FWIW, we don't orbit in the galactic plane. Per Wikipedia, "the galactic plane is inclined by about 60° to the ecliptic (the plane of Earth's orbit)." https://en.wikipedia.org/wiki/Milky_Way And "the Sun is currently 5–30 parsecs (16–98 ly) from the central plane of the Galactic disk." Id.

⬐ alpaca128

Not according to Veritasium's comment on his own video as well as the RelAstro group who produced the material[1]: "As there seems to be some general confusion, please note that the image shown here is a simulated one and not an actual image. So far we only have an image of M87. Kind regards, the RelAstro group. "

[1] https://www.youtube.com/watch?v=VnsZj9RvhFU

⬐ manigandham

Ah you're right. Looks like they all should've skipped Sagittarius A instead of adding confusion.

⬐ pjungwir

Oh, interesting! Wouldn't it be easier to photograph our own? :-)

⬐ jug

During the press conference, they said photographing the M87 black hole was like shooting a hibernating bear, and photographing the Sag A* black hole of our galaxy like photographing a quickly moving toddler. Something about the speed making it much harder. It is also much smaller, but that's less of a problem because it's much closer. All in all apparently making it about the same angular size. But it sounds like they'll get to it, it's just harder.

⬐ SamBam

That's a... weird analogy.

⬐ salthound

I think the actual analogy was lost in translation: the point is that, unlike its older brother, Sgr A* is not going to "pose" when you point your camera at it.

⬐ SamBam

Ah, I thought it was about actually shooting bears and toddlers.

⬐ hannasanarion

M87's black hole is currently eating something big, which makes it brighter. The black hole at the center of the milky way doesn't seem to have eaten anything lately, so it's accretion disk may be small or nonexistent.

⬐ schlowmo

> is currently eating something big

You mean: was eating something big 55 million years ago ;)

⬐ losteric

Nope, for the same reason we had photos of the Moon before we had photos of Earth.

⬐ nazgul17

Can you expand on this?

⬐ CydeWeys

What they're saying is that we had to send a camera away from the Earth (in a rocket) in order to photograph it properly, and similarly you'd need to send a camera away from our galaxy (in a biiiig rocket) in order to be able to photograph it properly.

⬐ wahern

Our solar system orbits at a 60 degree inclination from the galactic plane. See https://web.archive.org/web/20160809194418im_/http://sob.nao...

There's a great general description here: https://medium.com/starts-with-a-bang/ask-ethan-37-the-earth...

I'm not an astronomer nor is geometry my strong suit, so I don't quite know how to interpret and convey the descriptions of our relative motion. But AFAIU while quite low we're nonetheless currently outside the galactic plane. How well positioned we are to see our black hole free of obstruction would, I imagine, depend on the average inclination of everything else. But it seems like our inclination is relatively extreme and for the next 50 million years or so our view should become increasingly more clear.

⬐ CydeWeys

Nope. The view of our own galaxy's supermassive black hole is completely obstructed by matter within our own galaxy. You can't see to the core of our galaxy; it's too dense. You'd have to send a rocket quite some distance outside of the galactic plane to get a good view of it.

⬐ nwallin

The images are made with radio telescopes, which cuts through the dust quite easily. We have many other radio observations of Sagittarius A* [1], albeit at much lower resolutions. There are also numerous observations of Sagittarius A* in X-ray wavelengths, which is also fine because they are so energetic they simply punch through. All the dust and gas in the galaxy is transparent at most wavelengths except the visible one.

The Event Horizon Telescope is interesting because it is, in essence, a radio telescope that uses a "sensor" that is the size of the entire Earth. As such, it is able to make much higher resolution observations.

[1] https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:Clo...

[2] https://en.wikipedia.org/wiki/Sagittarius_A*#/media/File:X-R...

⬐ codethief

Actually not. M87 is a 1000 times farther away than Sgr A* but also a 1000 heavier and thus a 1000 times bigger in diameter. (Diameter/radius scale proportionally with the black hole's mass.) Therefore, the actual angular size on our night sky is the same for both black holes and, from this point of view, both would be equally difficult to observe.

However, as they mention in the press conference, Sgr A* moves a lot faster relative to us than M87, so it's much harder to take a still image. (In the press conference they used the example of trying to take a photo of a toddler with an exposure time of 8 hours.)

⬐ muterad_murilax

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

⬐ zenzen

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

⬐ muterad_murilax

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".

⬐ hypothete

So that would mean that the right side is tipped slightly away from us, right? Because the matter in the accretion disk starts approaching us at about halfway down the ring on the right side?

⬐ thro_away_n

Yes, from paper 1:

"Third, adopting an inclination of 17° between the approaching jet and the line of sight (Walker et al. 2018), the west orientation of the jet, and a corotating disk model, matter in the bottom part of the image is moving toward the observer (clockwise rotation as seen from Earth). "

⬐ fspeech

He appeared to have released a new video that incorporates the actual image: https://m.youtube.com/watch?v=S_GVbuddri8

⬐ meko

That was a great video, never grasped why interstellar and such showed black holes with the rings on top and bottom.

⬐ None

None

⬐ nsxwolf

So is that hazy diagonal line in the image the accretion disc, viewed edge-on from the Earth?

⬐ CamperBob2

Great video but he really doesn't do himself any favors by flapping his arms like a rabid goose. Distracting as heck.

⬐ wallace_f

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!

⬐ bdamm

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.

⬐ wallace_f

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.

⬐ bdamm

Uh.. It's the reason that the "shadow" is larger than the Schwarzschild radius. He's describing the ratio of the "rim" to the "hole". So while the picture may be fuzzy, there's information in it anyway about what the pictures means relative to how large/spin we think the black hole is. In fact I wish he'd said more about the Doppler effect.

⬐ wallace_f

Ok I mean, now what you're writing, that's not even wrong. The black part of the image being larger than the actual radius of the blackhole is a discussion about the relative size of the black area you see in the image, to the actual black hole itself. I think that should make sense to you? It's not an argument about why he predicts it will look like a "fuzzy coffee stain," as opposed to other simulated images. Are you able to see the difference between those two ideas?

I think you have some other discussion you were having confused with this one. To remind you about your earlier comment, you stated disagreement with me, saying this video was him only talking about why he predicted the image to look like a "fuzzy coffee stain" as opposed to some other simulated and theorized predicgions. I think the above paragraph and reply should obviously show you why this is actually not true. Are you still with me?

I do think most of the video is interesting, but he never states an argument about why he chose that prediction. That was what I thought was ridiculous. Science is about reason and evidence, not just saying "believe me."

Maybe you watched a different video? You should watch this video, the last 30% talks about simulations done in which the acretion disk reflects around the black hole, he uses example images which look a bit different!

⬐ darkpuma

The reason for the fuzziness should be obvious. It's really far away and it's really hard to see. Expecting a jump from "never seen before" to "seen in amazing visual clarity" is unrealistic.

⬐ wallace_f

That's also not even wrong. You can't see why?

Let's say we're imagining what Uranus would look like. I draw a picture, and say it should look like a "fuzzy Jupter." But you ask, why should it look that way? Do you have a reason? And I say you should be confident, but don't provide an argument. By the end, I start talking about how it might look like Saturn.

Then I come along and say, "it should be obvious the fuzziness is because it is far away."

That final statement is not even wrong. It misses the point.

⬐ darkpuma

Are you upset that the Veritasium video didn't explicitly spell out for you that this black hole is very far away, so the first image of it ever is basically certain to be fuzzier than IMAX fidelity computer simulations used in a Hollywood movie?

I think you're being very silly.

⬐ wallace_f

What? You obviously didn't read what I wrote.

⬐ darkpuma

> "What? You obviously didn't read what I wrote. Are you ok?"

You're ranting about Saturn and Jupiter for some reason. Why don't you calm down and look at page eight of the paper that Veritasium video was based on: https://ve42.co/luminet "Image of a spherical black hole with thin accretion disk Astronomy and Astrophysics, vol. 75, no. 1-2, May 1979, p. 228-235"

Look at that last image, and squint at it until it gets fuzzy. Lo and behold, a fuzzy coffee mug stain!

Perhaps it was a mistake for him to make the focus of the video on the physics of black holes, rather than the limitations of state of the art radio interferometry... but I don't think so.

⬐ wallace_f

It's really strange that you are unable to understand such a simple complaint I made, even after going to extra effort to spell it out. You even have even become aggressive insulting. I understand that some people become that way when they get confused, but how is it possible you are confused here?

I think you are literally not even reading my comments. Either that, or you are going through some personal issues right now.

I think it might help you if you tried to first understand that I am not complaining about the image being fuzzy. I have no idea why you keep going back to that. I spelled out an analogy to explain this to you and you got angry and insulting.

Are you really sure you are ok? You clearly have something going on.

⬐ darkpuma

Mate, you insulted me first, and have just repeated that insult again. I've tried to be charitable with you.

⬐ wallace_f

How did you come to the conclusion that I "insulted you first?"

⬐ castis

Everyone present can clearly see which person in this conversation is getting their jimmies rustled.

⬐ albedoa

You truly believe that all of the downvotes on all of your comments are the work of one account?

⬐ CydeWeys

Really awesome link, thanks for that! It's always interesting to see theory that is decades out in front of experimental confirmation, and then proves to be dead right.

⬐ darkpuma

Yeah, I did a double-take when I saw that was published in 1979. I think that's really cool.

⬐ khamoud

He isn't explaining why the blackhole would look like a fuzzy coffee mug stain. He's explaining why the _picture_ of the blackhole will look like a fuzzy coffee mug stain.

To your point, it's like taking a picture of Uranus with film and waiting for it to develop. People familiar with the matter can guess what the _image_ will look like not what Uranus actually looks like.

This is all very clear in the first 25 seconds of the video if you actually listen to what he's saying.

⬐ wallace_f

The first 25 seconds of this video actually does not have sound. The 25 seconds after he begins talking is him talking about Einstein and history.

Unless I'm misunderstanding your intentions and you just meant that as a condescending insult?

⬐ bdamm

I think what you're hoping for is a more exhaustive survey of what black holes are theorized to look like, with different possibilities. Is that right?

The problem here is your expectation does not match the product. It's like you went to a car dealer and are upset they didn't sell you an airplane.

It isn't surprising to me that Derek focuses on one form, since Veritassium is providing content for the armchair consumer, that he chooses what he believes to be the best model and presents that. This isn't a PhD defense, after all, it's just a timely video so that folks can appreciate the image that the EHT group has released (is going to release, at the time of Veritassium's video.)

Did you have some other models in mind?

Interesting to me is that Veritassium's presented model doesn't explain the corona-like features, nor any attempt at explaining the "blobs" although he does say that blobs would be exiting to see. And there they are! What fun.

⬐ wallace_f

Yea sort of. I mean I said I liked the episode, I just think this part is bad form (I'm paraphrasing):

>why can you expect it to look like this? well because it's just going to look like this.

Now, I'm not trying to say his prediction was unwise. I just think it's first of all bad form to say something like "the reason is just trust me," in scientific discussions (even if you are correct)... but second I actually do want to know at least some explanation to that question. Granted, I'm not saying the video does not explain anything about the image. I wanted to know: why can we be sure it will look like this, and not other simulated images?

That's all.

You can see on the EHT's own website a gallery of other simulated models of what could be expected from a radio image.

And the second part of my criticism, was that by the end of the video, he was using images inspired by other models, and particularly of one where the accretion disk dominated the image.

I dont care how many downvotes I get, I know the difference between right and wrong and this is a perfectly reasonable criticism.

Anyways, since my posts lost 60 karma in 1 hour somehow (almost uniformly coming from posts in other threads, wtf?) some other opportunistic types see it as a chance for bullying. Even writing stuff like 'you've obviously got your jimmies rustled mate!' or other extremely bad faith assumptions like 'if you cant understand why it's fuzzy, it's far away!' The best is the troll bait comment, 'do you really think one person is downvoting you?' Groupthink, bullying, and authority define right and wrong for some people--they can't even write something that even addresses an actual comment or argument. People are crazy. Eventually they just start addressing the negativity itself, abandoning any substantive argument, and focusing on the negativity itself. The next step is using the negativity as its own justification (you deserve negativity because otherwise you wouldnt be receiving negativity kind of assumptions implicig in the above troll bait comment).

But still all that I dont think explains why comments in unrelated posts (even ones that were being complimented) got the same time-unform mass-downvotes?? I think I haven't experienced anything like this before on this site until recently. I lost 60 karma in the a few hours.

⬐ bdamm

Well, for the record, it wasn't me. I did however read through your comments just now, and it seems there is a pattern of not really engaging in dialogue but just blasting your opinion over and over. Looking at your comments on Julian Assange, for example, it seems clear that you do not think there is any difference between what a NYTimes reporter does and what Assange did. I can't speak to everyone else but to me the difference is quite obvious, and probably that has something to do with why you're being downvoted. You're repeatedly stating that they're the same, without describing why you believe this, and then kind of insulting other people for their belief that in fact they are different. So anyway, I've spent way, way too much time responding to you. Good luck to you sir.

⬐ wallace_f

Hmm there is some groupthink, lack of reason, or bullying going on here.

Look at this image for yourself. The article is titled: "Here is what scientists think a black hole. Looks like:" https://www.sciencemag.org/news/2019/04/here-s-what-scientis...

There are not massive differences in the images, but the Vetiasium prediction was (and this is very plain) much more accurate.

This isn't controversial at all.

I also thought the particular statement, "why is it like this, because it is just going to look like this" was bad form.

This is very plainly reasonable.

I think the fact that you and a few other users turned this into an opportunity to go through the effort of writing belittling comments and even put downs and troll bait over something as plain and ordinary as this is indicative of some bad qualities of humanity expressing themselves here.

Of course, your only response will be further negativity as bad people dont possess the ability to admit when they were wrong.

And the statement about Assange is very widely expressed. See here(1). There are articles all over the media, just like that one, echoing the same exact view. They are literally everywhere.

Finally, I noticed over the last 30 minutes all my recent comments went down by -1 each. That really makes it look like I'm engaging with some quite petty and insecure people.

Edit: see, right after I wrote this comment, all my recent comments each, in perfect synchronization, down by -1 again haha.

⬐ coldtea

>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 doesn't need to give a reason. The reasons why it would look like a "fuzzy coffee mug stain" are well known since Hawkings...

⬐ manigandham

Did you see the movie Interstellar? He included it in his video. That's what the black hole looks like, except with the relativistic beaming make one side brighter than the other.

Here's the image from the movie: https://www.wired.com/wp-content/uploads/2014/10/ut_interste...

Now imagine that image being taken far away by several ground-based telescopes put together at the edge of their capabilities and using math to error correct and stitch together the final result. What you get is what we saw.

⬐ wallace_f

Ah, sure. Also, if you go to the EHT's own website, they have a gallery of predicted, simulated images.

Here is another prediction: https://www.sciencemag.org/news/2019/04/here-s-what-scientis...

I just wanted to know why he went with that one because his prediction was really accurate. And I thought him saying 'just trust me' was bad form.

He did talk some about this, but he didn't really say anything about why he thought his illustration would be so accurate compared to a lot of other stuff seen in the press.

I dont care (or have any idea why) how many downvotes or insults I get. It is a perfectly reasonable question and criticism.

⬐ manigandham

I don't see the difference, the predictions are the same.

The only changes in the image depend on what angle the black hole is being viewed at which would influence whether we see a band across the middle and the slimmer inner ring.

⬐ wallace_f

Lol the image I linked is obviously very different.

There is some groupthink going on here affecting people like you and others. The above is obviously plain.

⬐ manigandham

There are 4 images on that page, 1 of which is the Interstellar movie rendition that I already linked to. They are also all the same model only in better detail as graphics technology has improved.

Perhaps you should post exactly what image you're talking about and what you think is different.

⬐ wallace_f

In the images I linked to, the black hole images don't have any "blobbiness," and seem to have these perfect gradiants.

In the veritasium video the "coffee stain" was not really as blobby as the real image, but it seemed a lot closer than the smooth-gradiant, no blobbiness and no irregularities predictions.

I dont just mean the fuzziness from low resolution.

This isn't really a big deal, but it's also obvious that I am just stating plain facts about what is in these images.

At the time I saw this video when he said "you can be confident, because... (no reason given)" was really the thing that I thought was annoying.

I think you can see the differences in the images. They're not huge but the smooth gradiants vs irregularities/coffee stain/blobbiness is plain to see I think.

Edit: from the horses mouth himself, one of the lead researchers says he didn't expect the image to look like it did: https://youtu.be/ZrDhHDBHkQY

Some of the people here in other parts of this thread have been really offensive for this. It's honestly pretty ridiculous.

⬐ manigandham

The general model of what a black hole looks like is well understood. The highest definition rendering is that in Interstellar, except for one side being brighter than the other due to the relativistic beaming. They kept that part out of the movie to just make it look nicer.

All the models are the same, and the real picture is "blobby" only because of the process in how it was taken. I think you are refusing to accept that but there's nothing else to say about it. It wasn't a direct photo, it was a complex assembly of several different radio telescopes around the world stitching data together. If we were actually next to it, it would very much look like the one from interstellar.

The video you linked isn't about the prediction being wrong, more that he just didn't expect to really see a black hole at all. Even though black holes are generally understood for decades, there's a certain shock and awe to seeing it real for the first time.

⬐ wallace_f

Lol ok then we can agree to disagree. Even the YT video I just linked to opens with an intro containintlf a simulation, which once again, has subtle but pretty obvious and appreciable differences.

Also, my complaint was in fact that I didnt know why Veritasium was confident in their prediction. This complaint is for a matter of fact completely consistent with one of the lead researchers outright saying they didn't know what to expect. I never said I was exclusively complaining about there being simulated models which have some differences. You and others criticized me after I said he should have substantiated why he was confident in his prediction. I gave what I believed was my the foremost reasoning for saying that.

I had little idea what the picture would look like...

I have no idea why you're so intent in disagreeing with me. I'm substantiating my ideas with facts. And saying 'just bbelieve me' I think is also bad form.

At this point I feek like your disagreement has to do with psychological or social biases unless you are able to address the factual content of my comment.

But the one thing you said that was interesting was about the blobbiness. I think what you are trying to saya is that it is fully expected by the researchers to be error. Do you have a good interview or other source on this?

⬐ acqq

How about forgetting that video for a moment and trying to consider the following picture:

https://static.projects.iq.harvard.edu/files/styles/os_files...

Taken from here: https://eventhorizontelescope.org/science (the official site of the project).

On the left is how it would look like if we weren't so far -- we are 55 million light years far from that. You know the distance from us to our Sun, which you see on the sky but can cover with your own thumb? That object is 3,500,000,000,000 times farther than the Sun is far from us.

On the right is what we can reconstruct from the signals measured because we are so far and we have "only" the telescope the size of the Earth. More details would be visible (the picture would look more like the one on the left) either if we had even much bigger telescope than the Earth, or if the black hole of the same size were much closer to us, which it is not.

⬐ m87

It doesn't seem to be that accurate, as expectation was for it to have smoother photo sphere, but it has irregular bulges (5 of them). I think they discussed it briefly in the press conference as well. It would be interesting to see if this would change understanding of general relativity and may be give a hint for a theory of quantum gravity.

⬐ acqq

Look at the expectation examples in the scientific paper from 2013 that is, from ca. 6 years ago:

https://arxiv.org/abs/1309.3519

It matches quite good, I'd say. Page 4.

⬐ wallace_f

What bothered me more about the video is that of you watch the whole thing, he ends up talking about some theory which leads to another type of image prediction. He never actually explains why he chose to go with the former prediction rather than the latter.

⬐ albedoa

The whole video was him explaining why the image would look the way it ended up looking. darkpuma was overly patient when explaining this to you.

⬐ wallace_f

You were a user acting in bad faith that very literally jumped in at the end just to write a troll bait comment in that thread. Your comment had nothing substantive to even do with any discussion, or even any relation to anything I said.

There is nothing complex about my original statement there. The EHT website itself has a gallery of simulated images and I'd like to know why he chose that one specifically.

In the video he says "just trust me."

This is a perfectly reasonable criticism, I don't care how many downvotes or personal attacks I get.

It has nothing to do with anyone "being patient." That thread was 90% bullying, which you are taking part of.

⬐ albedoa

Can you link to the comment of yours that I replied to? I can't see it for some reason.

⬐ jjeaff

I'm not sure how much we can truly draw from small irregularities in the image. This isn't actually a low resolution image. It is an algorithmically interpolated image created by comparing possible interpretations of the spotty and noisy data gathered from multiple points at different times processed against images of what we think a black hole should look like.

⬐ amelius

> Good video that correctly predicted the image and describes why it looks the way it does

This is of course a bummer, since this means that the acquired image does not give us any new clues of where our understanding of physics is wrong.

⬐ jug

It's probably a bit too early to say because e.g the magnetic field data that was also collected hasn't even been scrutinized yet. This will also almost for sure lend a better understanding of the relativistic jets, in order to hopefully one day tell why they are this way or another depending on the particular black hole rather than just "they are somehow often there".

It's still very early and like the detection of gravitational waves, I think it feels like more of a symbolic step into a new era of space science. It's easy to forget that yesterday, black holes were a result of mathematics and only indirectly shown that they "ought to exist".

So first, I think we need to cut them some slack! Second, I think that if we at all WANT to shatter the Standard Model, I think we first need to be able to do science at the extremes of it! The LHC is one way, probing into the details of black hole mechanics might end up being another

⬐ Obi_Juan_Kenobi

We've furthered our understanding of the truth of the universe. That's not a bummer.

⬐ vanderZwan

I expect that at the resolution that this picture is taken it would be surprising if new radically physics was found, since it would require our current models to be very different from reality to see significantly different results

⬐ mxwsn

I think this is unhelpful parroting of comments on actual cutting edge physics experiments like the LHC. The degree matters substantially - there, we have good guesses of what we might see, but there's uncertainty and new data is immensely valuable for narrowing hypotheses. It's the research frontier.

Reasoning about an image of a black hole is very much within the realm of standard science. Veritasium was able to explain the prediction using essentially ideas that are so basic they're at the high school level. If our basic understanding of physics down to the high school level was wrong (e.g., very far from the research frontier), there would be very very serious issues.

⬐ GuB-42

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.

⬐ koheripbal

It's too bad we cannot see the accretion disk edge-on as in the video. That would have made it a perfect prediction. Maybe it's so thin that it's overwhelmed by the projections of the top and bottom of the back side of the disk.

⬐ darkhorn

May be we can see higher resolution if we build an additional telescope.

⬐ dredmorbius

More distant (longer baseline), not merely additional sensors.

Resolving power is proportional to the (virtual) aperture size, not the total sensor area (that gives more signal strength).

⬐ exelius

So put some telescopes in orbit around the Moon and Mars.

⬐ Cthulhu_

A guy on Reddit actually asked this in the AMA. While that would increase the resolution, it would also be extremely difficult. The algorithms used to combine the data from the dishes relies on the exact position of the dish being known at the time of measuring, to a precision of fractions of millimeters. It's already hard to do on the earth's surface, but imagine doing it with a sattelite zipping around the earth at 20K km/s, or the moon at >1 km/s around the earth, or Mars at 24K km/s around the sun.

⬐ ataturk

I predict we'll do it, though.

⬐ wool_gather

Not to mention getting the data back down here. For the analysis of M87, there were multiple petabytes generated: they had to use good old sneakernet and ship hard drives.

⬐ ben_w

Given the observation period has been multiple years, does that virtual size include the orbit of the Earth? Or is there something that limits it to still being Earth-sized?

⬐ tqkxzugoaupvwqr

As far as I know, Veritasium and others occasionally join efforts and coordinate around soon to be published scientific discoveries in a goal to increase exposure. Don’t know if this was the case with the black hole image.

⬐ hannasanarion

It probably wasn't coordinated, because he got the black hole that was being imaged wrong.

He said we would see a picture of Sagittarius A*, but we actually got the black hole at the center of M87.

⬐ juliansimioni

I thought we got both, which is the best possible outcome: no one is wrong and there are more black hole photos.

⬐ hannasanarion

We didn't get both, we only got M87. Sgr A is dimmer, so it needs more number crunching to get a good image

⬐ manigandham

They observed both, watch the follow-up: https://www.youtube.com/watch?v=S_GVbuddri8

"The Event Horizon Telescope Collaboration observed the supermassive black holes at the center of M87 and our Milky Way galaxy (SgrA*) finding the dark central shadow in accordance with General Relativity, further demonstrating the power of this 100 year-old theory."

⬐ misnome

But in the press conference they specifically said they weren’t releasing SgrA* yes because they hadn’t completed their analysis. They released pictures after that?

⬐ manigandham

You're right, it looks like they are still observing Sagittarius A but what they released was only a simulation for that one.