Taking a sharper look at the M87 black hole

https://phys.org/news/2023-04-sharper-m87-black-hole.html

by wglb • 3 years ago

44 21 3 years ago

ckastner2• 3 years ago

With PRIMO, computers analyzed over 30,000 high-fidelity simulated images of black holes accreting gas.

That means that the new image better conforms to the simulated data. I understand why it makes sense to do this (simulated data generated following the laws of physics, etc.) but it seems to me that the original point of the EHT was to experimentally verify that black holes actually look as we've modeled them for decades, so sharpening images using modeled data seems somewhat backwards.

mach1ne• 3 years ago

Didn’t the original image also have a lot of designer choices made which, in some sense, contaminate the results?

ckastner2• 3 years ago

I can only assume so, given the nature of the experiment. But it seems counterintuitive to add yet more of it. Naively speaking, it feels a bit like the actual data is being "guided" towards the simulation.

However, I have zero subject matter expertise with physics, so my intuition is probably not worth much.

alephnil• 3 years ago

The data clearly supported the hole in the middle, and only reconstructions with a hole did fit the data. The data support the hole and that one side is brighter, but not much more than that. Thus a blurred image does not make one believe that we know more than we do.

hn8305823• 3 years ago

Yes, but those choices had good scientific basis which was the best we could do at that time.

They are just starting data collection at a higher frequency band that will allow higher resolution. Unfortunately our baseline is currently limited by the diameter of the earth so the only way to get sharper data is by using shorter wavelengths.

teenbear• 3 years ago

The original image was an amalgamation of several different reconstruction techniques with varying dependence on prior information. They also had data driven techniques during the original analysis but I don't think they were used to generate the final image shown to the public

pyinstallwoes• 3 years ago

Literally erecting the matrix through self fulfilling prophecies predicated on models as a consequence of dogma. Oh holy simulacrum.

dylan6044• 3 years ago

Does this mean that the AI/humans apocalypse is also self fulfilling since not once have I come across a prophetic use of AI that did not end in the AI attempting to wipe out the humans

toss1• 3 years ago

Yup. The results look beautiful.

My first question here was how do we know the results are not 'hallucinated' or infilled by the ML system?

The fact that it was fed simulated data makes this really circular. If the goal is to get hard real-world data to validate the simulations, then training the machine that generates an "improved" data set on the simulation data itself would greatly increase the likelihood that the results will match the inputs, but not because that is what is actually out in reality.

Obviously, the people doing this are vastly more expert than I am, but it'd be good to see an explanation of how they are avoiding this fundamental issue.

raverbashing• 3 years ago

Is it just me or the 'new' image looks like it's mirrored w.r.t the old one?

dylan6044• 3 years ago

That's because the AI is so smart, it remembered that images from the telescope are flipped from the physics of the lens /s

denton-scratch• 3 years ago

The way I read this:

"Our imaging system lacks sufficient resolution to confirm or disprove our theories. But we can achieve better resolution by generating images based on our theories, and combining those generated images with the data from the imaging system. We are astonished to find that the resulting high-resolution images confirm our theories."

Isn't this some kind of anti-science?

rcxdude2• 3 years ago

No, but it is worth being careful about what such fitting means: What it's saying is "given this set of theories about what the black hole might look like, here's what it most likely looks like" (and hence what theory of those in the set is most likely). That's still usefully improving your knowledge, even though in theory there could be some other shape it looks like with theories you have not considered. And stating with the prior it could look like literally anything is not necessarily reasonable: no-one expects that it would look like a tree, for example, and that's because of other things we have observed about the universe. Science, especially astrophysics and cosmology, is a lot like a gigantic crossword: the clues and answers to other parts of the puzzle constrain the other parts, and while it's theoretically possible that there is some completely different model for everything that fits all the observations done so far, generally the bits which are less clearly known still have a pretty well-defined shape, because they are constrained by other information and the models which fit that.

Taking a sharper look at the M87 black hole

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