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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

#301

Post by aortega »

panda-giddiness wrote: post #261
wumpus wrote: post #34

Earlier quoted context omitted.

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.

Science is not religion and contrarian opinions strengthen science results. I think it's healthy to always have a dose of skepticism, and is not uncommon for astrophysics papers to be retracted or refuted.

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

#302

Post by panda-giddiness »

aortega wrote: post #301
panda-giddiness wrote: post #261

Earlier quoted context omitted.

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.

Science is not religion and contrarian opinions strengthen science results. I think it's healthy to always have a dose of skepticism, and is not uncommon for astrophysics papers to be retracted or refuted.

Absolutely, but those retractions are led by other astronomers/astrophysicists, not lay people presenting straw men.

I think people's priors here are out of whack -- perhaps the truth does lie somewhere in the middle, but if so, it will be much closer to ETH's version than the OP's.

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

#303

Post by belter »

panda-giddiness wrote: post #302
aortega wrote: post #301

Earlier quoted context omitted.

Science is not religion and contrarian opinions strengthen science results. I think it's healthy to always have a dose of skepticism, and is not uncommon for astrophysics papers to be retracted or refuted.

Absolutely, but those retractions are led by other astronomers/astrophysicists, not lay people presenting straw men. I think people's priors here are out of whack -- perhaps the truth does lie somewhere in the middle, but if so, it will be much closer to ETH's version than the OP's.

Astronomers/astrophysicists started first, by misrepresenting the process and bringing the talk of taking photos and having "visual evidence".

"...We have seen, and taken a picture, of a Black Hole."

https://youtu.be/lnJi0Jy692w?t=456

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

#304

Post by denton-scratch »

whitesilhouette wrote: post #274
denton-scratch wrote: post #222

I am impressed. I have a few ignorant questions: 1. There are three bright blobs on the image; I assume they are the same object, behind the BH. What are they/is it? They said the image was averaged; so presumably whatever the blobs are wasn't moving? 2. Is it correct that the rest of the ring, ignoring the three blobs, is the far side of the accretion disk? Why can't I see this side of the accretion disk? 3. Accordi…

1. Doppler boost https://www.bbc.co.uk/news/science-environment-61412463

Thanks; but that's confusing.

If "doppler boost" is regions that are moving towards us, then they presumably aren't swirling around the BH at near-light speed?

Is the ring of light the accretion disk or not? If it is the accretion disk, why is some of it moving towards us?

And why does it seem that the ring of light is oriented perpendicular to our line-of-sight? Is that really coincidence? Don't most accretion disks rotate on roughly the axis of the host galaxy's rotation? If we're looking directly at one of the poles of the BH, shouldn't we see some sort of beam pointing right at us?

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

#305

Post by JacobThreeThree »

dotnet00 wrote: post #234
JacobThreeThree wrote: post #231

Earlier quoted context omitted.

If general relativity based models have struggled to help predict or explain planetary system formation and exoplanet observations, I think we should have the same level of expectation about how helpful a general relativity based black hole model will be.

You might as well be saying that if fluid dynamics models have struggled to help predict or explain CPU performance increases, we should have the same level of expectation about how helpful a fluid dynamics based model of aerodynamics will be, i.e. complete nonsense

Planet formation is a subset of system formation which is a subset of galaxy formation and all are within the same observational astrophysics domain.

CPU performance and aerodynamics are two completely unrelated domains.

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

#306

Post by JacobThreeThree »

DiogenesKynikos wrote: post #246
JacobThreeThree wrote: post #231

Earlier quoted context omitted.

If general relativity based models have struggled to help predict or explain planetary system formation and exoplanet observations, I think we should have the same level of expectation about how helpful a general relativity based black hole model will be.

General Relativity has pretty much nothing to do with planet formation. Newtonian gravity is good enough for that problem, and the problems have nothing to do with not understanding gravity well enough. The problems have to do with things like complex chemistry in stellar accretion disks, how grains in these disks stick to one another to eventually form rocks, and so on.

Whether the problems with the models are with general relativity, Newtonian gravity or other issues, the point is that the models have problems.

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

#308

Post by edgyquant »

px43 wrote: post #198
kloch wrote: post #10

One of the findings they announced at the press conference is that the spin of the black hole is not aligned with the galactic plane but is tilted "towards us" so that it is viewed face on. How unexpected is that?

Kind of makes me nervous that both black holes we've imaged are pointing right at us. I'm imagining some super advanced civilization somehow using black holes as powerful telescopes that are for some reason intent on mapping out our region of space. I know M87 is 55 million light years away, so that makes no sense, but I'd really like to see some black holes that are looking in some other direction. Is it at all poss…

From our perspective would not all black holes we can see appear the same? Considering that what we seek is simply light not escaping.

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

#309

Post by edgyquant »

murat124 wrote: post #24

This image apparently has not captured as much attention as the image of M87, but anyway, I have a question, maybe someone with the knowledge can answer: Between the images of M87 and Sgr A, one noticeable difference is that the image of M87 appears to have a single cluster of light "below" the blackhole whereas the image of Sgr A has three surrounding the blackhole. Is this because of the mass and spin differences b…

The first image of a black hole is cool to everyone, an image of a black hole in the center of the Galaxy is cool to a vastly smaller group I’d imagine.

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

#310

Post by codethief »

SiempreViernes wrote: post #297
codethief wrote: post #291

Earlier quoted context omitted.

An observer at infinity won't see anything cross the horizon, though, by the very definition of what a horizon is.

The light crossing time refers to the time needed to traverse a diameter of distance.

Sorry, I misread.
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