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Astronomers reveal first image of the black hole at the heart of our galaxy

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Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#261

Post by panda-giddiness »

wumpus wrote: post #34
fasteddie31003 wrote: post #29

I am very skeptical of the Event Horizon Telescope (EHT) images because they are not following a scientific method that results in a true representative image of their target. In my opinion astronomy is jumping the shark with these images by making this a big PR stunt. I've looked at their methods for their earlier images and they seem to be hunting for a circle that looks like a black hole in their data. The EHT's f…

Didn’t I already reply to you weeks ago about a similar comment? Now you can read the actual papers which explain in detail why your comment is incorrect.

Thanks for calling them out (again). Honestly people in this forum are too eager to upvote contrarian opinions. I hold a PhD in physics, and I wouldn't feel qualified to challenge ETH's work.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#262

Post by imglorp »

nuccy wrote: post #20
imglorp wrote: post #8

Earlier quoted context omitted.

Yes, IR better penetrates the dust cloud hiding Sgr A*, so here's hoping.

The EHT reveals the black hole shadow of about 50 micro-arcseconds [1], while JWST has resolution of about 0.1 arcsec [2], thus resolution of JWST is more than 2000 worse. It is physically impossible (regardless of the exposure time) for JWST to resolve Sgr A*. 1. https://physicsworld.com/wp-content/uploads/2022/05/First-SG... 2. https://webb.nasa.gov/content/about/faqs/facts.html

Interesting, thank you.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#263

Post by heyitsguay »

queuebert wrote: post #202
photochemsyn wrote: post #86

Earlier quoted context omitted.

You mean, this? https://iopscience.iop.org/article/10.3847/2041-8213/ac6615 >"Since the interferometric measurements are often incomplete in the Fourier domain, the inverse problem of reconstructing an image from the observed data set is usually underdetermined. Consequently, the image reconstruction requires prior information, assumptions, or constraints to derive a reasonable image from the infinite number of possi…

>"Since the interferometric measurements are often incomplete in the Fourier domain, the inverse problem of reconstructing an image from the observed data set is usually underdetermined. Consequently, the image reconstruction requires prior information, assumptions, or constraints to derive a reasonable image from the infinite number of possibilities that can explain the measurements." If the original commenter has a…

It's the usual HN physics thread stuff - for some reason physics really brings out the confidently incorrect crowd.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#264

Post by terramex »

chrsw wrote: post #248
sandworm101 wrote: post #230

Earlier quoted context omitted.

JWST is nowhere near the caliber of telescopes necessary to resolve black holes. Very literally, we would need an optical telescope bigger than new york city to even make an attempt.

What about an array of space telescopes creating a kind of "virtual lens"? Putting aside the engineering scale and cost of such a project, would something like that even be possible? Or would that be pure science fiction?

It is possible in principle, but gets harder as wavelength of captured light gets smaller and so far it is done only for long radio waves on planet scale.

https://en.wikipedia.org/wiki/Astronomical_optical_interfero... https://en.wikipedia.org/wiki/Aperture_synthesis

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#265

Post by jepler »

perardi wrote: post #195
jepler wrote: post #162

Earlier quoted context omitted.

On the timescale from now until the sun goes nova, confident "no". Roughly speaking, the sun orbits the galactic center at a velocity of 220km/s. To fall into, or to be sucked into, the central black hole would require the loss of all this velocity, which means applying acceleration to the sun opposite the direction of its orbit. Lots of acceleration. That has to come from somewhere. I suppose there's some extremely…

[pushes up glasses] The Sun is nowhere near massive enough to become supernova. https://en.wikipedia.org/wiki/Sun#After_core_hydrogen_exhaus... It will become a red giant, and then eventually end up a white dwarf.

Thanks for the correction. You're right, current scientific thinking is that the sun is not capable of going "supernova".

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#266

Post by Saint_Genet »

gilbetron wrote: post #228
Mehringotio wrote: post #107

Earlier quoted context omitted.

Either you are an expert in this field than it should be you who writes a clear argument and present it or you are not an expert. Aren't they are peer reviewed? What is your expertise in astrophysics?

He has a theoretical degree in astrophysics.

He still didn’t read and understand 10 papers this fast

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#267

Post by ClumsyPilot »

jankovicsandras wrote: post #232
hbrav wrote: post #219

Earlier quoted context omitted.

I think there's some confusion on your part about what the image purports to show. I shall put aside the parent comments concern about the signal analysis techniques. Those may be valid concerns, and I don't know enough to assess them. > I'm not sure it's physically possible to take a visible light picture of a "naked" event horizon The event horizon telescope isn't purporting the image emission from the event horizo…

Thanks for your reply! I also think it's scientifically interesting and appreciate the work. But it should be called a model or illustration, because a human could never see this with bare eyes.

A picture is not reserved for something we can see with bare eyes - an infrared camera produces a photo, we don't call that an illustration - such cameras are used in military, geology, earth mapping and agriculture, etc. Most images in industry and astronomy could never be seen with bare eyes, because our eyes can see only 1% of what our instruments can.

Ofcourse each wavelength of light works a bit differently, like with the X-ray example, you need to understand how X-ray works to understand what you are looking at.

A model or illustration is something that would be product of our calculation or imagination, that was given visual form.

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#268

Post by ugh123 »

chrsw wrote: post #248
sandworm101 wrote: post #230

Earlier quoted context omitted.

JWST is nowhere near the caliber of telescopes necessary to resolve black holes. Very literally, we would need an optical telescope bigger than new york city to even make an attempt.

What about an array of space telescopes creating a kind of "virtual lens"? Putting aside the engineering scale and cost of such a project, would something like that even be possible? Or would that be pure science fiction?

This is what the Event Horizon telescope does https://en.wikipedia.org/wiki/Event_Horizon_Telescope

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#269

Post by ajcp »

gilbetron wrote: post #228
Mehringotio wrote: post #107

Earlier quoted context omitted.

Either you are an expert in this field than it should be you who writes a clear argument and present it or you are not an expert. Aren't they are peer reviewed? What is your expertise in astrophysics?

He has a theoretical degree in astrophysics.

Welcome aboard!

Re: Astronomers reveal first image of the black hole at the heart of our galaxy

#270

Post by shakezula »

chrsw wrote: post #248
sandworm101 wrote: post #230

Earlier quoted context omitted.

JWST is nowhere near the caliber of telescopes necessary to resolve black holes. Very literally, we would need an optical telescope bigger than new york city to even make an attempt.

What about an array of space telescopes creating a kind of "virtual lens"? Putting aside the engineering scale and cost of such a project, would something like that even be possible? Or would that be pure science fiction?

There are proposals for scientific missions utilizing the gravitational lensing of light around the Earth (or other planets) being fed into a network of satellites to do exactly this. And as another comment pointed out, the EHT already does this for imaging black holes, just with satellites on Earth.
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