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Taking a sharper look at the M87 black hole

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Re: Taking a sharper look at the M87 black hole

#11

Post by weego »

brokeAstronomer wrote: post #7
ckastner wrote: post #4

Earlier quoted context omitted.

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.

Since the EHT is an interferometer, the observations contain less information than what would be available from a single telescope of the same equivalent size. Therefore to reconstruct the 'full image' you need to find the model which best fits your interferometric observables. As far as I can tell, what they've done with PRIMO is basically a fancy version this kind of modelling. The data isn't necessarily being guid…

As I had to explain to the execs at a lab on a chip startup I was helping to put together, you're generating the proposition of what the data might be that still needs to be qualified with physical testing, and not actual data.

This concept seems to be worryingly lost in the flurry of excitement at using ML/AI in academic research by some.

Re: Taking a sharper look at the M87 black hole

#12

Post by ryanjamurphy »

weego wrote: post #11
brokeAstronomer wrote: post #7

Earlier quoted context omitted.

Since the EHT is an interferometer, the observations contain less information than what would be available from a single telescope of the same equivalent size. Therefore to reconstruct the 'full image' you need to find the model which best fits your interferometric observables. As far as I can tell, what they've done with PRIMO is basically a fancy version this kind of modelling. The data isn't necessarily being guid…

As I had to explain to the execs at a lab on a chip startup I was helping to put together, you're generating the proposition of what the data might be that still needs to be qualified with physical testing, and not actual data. This concept seems to be worryingly lost in the flurry of excitement at using ML/AI in academic research by some.

This is well-said. We're looking for what the best guess should be, but we still need to test the guess.

Re: Taking a sharper look at the M87 black hole

#13

Post by hn8305823 »

mach1ne wrote: post #3
ckastner wrote: post #2

> 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…

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

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.

Re: Taking a sharper look at the M87 black hole

#14

Post by toss1 »

ckastner wrote: post #2

> 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…

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.

Re: Taking a sharper look at the M87 black hole

#15

Post by dylan604 »

hn8305823 wrote: post #13
mach1ne wrote: post #3

Earlier quoted context omitted.

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

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.

>Unfortunately our baseline is currently limited by the diameter of the earth

Is there a way to use the diameter of the earth "at this point in the orbit" to effectively make it into the diameter of the earth's orbit?

Re: Taking a sharper look at the M87 black hole

#16

Post by dylan604 »

pyinstallwoes wrote: post #10
ckastner wrote: post #2

> 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…

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

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

Re: Taking a sharper look at the M87 black hole

#18

Post by torrance »

dylan604 wrote: post #15
hn8305823 wrote: post #13

Earlier quoted context omitted.

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.

>Unfortunately our baseline is currently limited by the diameter of the earth Is there a way to use the diameter of the earth "at this point in the orbit" to effectively make it into the diameter of the earth's orbit?

Interferometry relies on measuring the interference pattern between two points simultaneously measuring incoming radio waves. Each element of a baseline must be measured at the same time.

If we were to allow the Earth to rotate around the Sun and measure components of the same baseline at different times, we would violate this.

Re: Taking a sharper look at the M87 black hole

#19

Post by dylan604 »

torrance wrote: post #18
dylan604 wrote: post #15

Earlier quoted context omitted.

>Unfortunately our baseline is currently limited by the diameter of the earth Is there a way to use the diameter of the earth "at this point in the orbit" to effectively make it into the diameter of the earth's orbit?

Interferometry relies on measuring the interference pattern between two points simultaneously measuring incoming radio waves. Each element of a baseline must be measured at the same time. If we were to allow the Earth to rotate around the Sun and measure components of the same baseline at different times, we would violate this.

what about space telescopes in orbit at earth's radius at various points in the orbit?

Re: Taking a sharper look at the M87 black hole

#20

Post by godshatter »

torrance wrote: post #18
dylan604 wrote: post #15

Earlier quoted context omitted.

>Unfortunately our baseline is currently limited by the diameter of the earth Is there a way to use the diameter of the earth "at this point in the orbit" to effectively make it into the diameter of the earth's orbit?

Interferometry relies on measuring the interference pattern between two points simultaneously measuring incoming radio waves. Each element of a baseline must be measured at the same time. If we were to allow the Earth to rotate around the Sun and measure components of the same baseline at different times, we would violate this.

One telescope each at the L4 and L5 Earth-Sun Lagrange points, coordinating their activities?
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