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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

#51

Post by zeven7 »

rootbear wrote: post #31
markus_zhang wrote: post #19

Earlier quoted context omitted.

Thanks. Can you please point me to some popular science article that explains why the two do not agree with each other?

Brian Greene's "The Elegant Universe" does a very good, completely non-technical, job of explaining the conflict between the two theories. It then goes on to explain why String Theory is one possible solution to the problem.

There's also a Nova documentary version if parent would prefer to watch something: https://www.pbs.org/wgbh/nova/series/the-elegant-universe/

I'll add an additional recommendation: Stephen Hawking - The Theory Of Everything

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

#52

Post by mabbo »

kloch wrote: post #41
jrgd wrote: post #32

I find the whole thing amazing and captivating - yet the image is … huh … slightly underwhelming. It looks like some gaussian blurred random image. I wish it could be the kind of crisp image JWST ‘sent’. It’s difficult to force oneself to not romanticise these un-visible things based on artists visualisation we got accustomed to.

It's actually one of the sharpest images ever made - in terms of angular resolution. The Sag.A* ring is about 51 microarcseconds in diameter. The EHT has a theoretical resolution of ~25 micro arcseconds. For comparison NirCam on Webb has a pixel resolution of 70 miliarcseconds (about 2800 times worse resolution than EHT). The reason it looks blurry is that the black hole features are close to the resolution of EHT so…

> The only way to get higher angular resolution is to use higher frequencies (which they are working on) or use radio telescopes in space to get longer baselines than the diameter of the Earth.

Would it be possible to use the same trick in space? IE: get a baseline the diameter of Earth's orbit (roughly)?

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

#53

Post by h2odragon »

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…

I loved to pick on my astrophysicain buddies about their over-reliance on interpolation. It's not invalid in itself but they do seem fond of making sweeping generalizations that fit neatly into the smooth spots in their spectrums.

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

#54

Post by zeven7 »

BurningFrog wrote: post #50
onceiwasthere wrote: post #14

Earlier quoted context omitted.

They want an exciting disruption to current theory.

Basically they're bored/want mysteries to solve.

tbf, there is already a mystery to solve. This just means we have no new information to help us solve it.

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

#56

Post by zeven7 »

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?

For quasars, don't the beams shoot out of the poles? Let's hope our nearby buddy doesn't become that active.

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

#57

Post by kloch »

mabbo wrote: post #52
kloch wrote: post #41

Earlier quoted context omitted.

It's actually one of the sharpest images ever made - in terms of angular resolution. The Sag.A* ring is about 51 microarcseconds in diameter. The EHT has a theoretical resolution of ~25 micro arcseconds. For comparison NirCam on Webb has a pixel resolution of 70 miliarcseconds (about 2800 times worse resolution than EHT). The reason it looks blurry is that the black hole features are close to the resolution of EHT so…

> The only way to get higher angular resolution is to use higher frequencies (which they are working on) or use radio telescopes in space to get longer baselines than the diameter of the Earth. Would it be possible to use the same trick in space? IE: get a baseline the diameter of Earth's orbit (roughly)?

For Interferometry to work the data from different baselines has to be collected at the same time so waiting 6 months does not help. Spacecraft could theoretically be used to extend the baselines but the volume of data to be transferred is prohibitive with current spacecraft comm tech.

Even on Earth they resort to shipping cases of hard drives instead of transferring over the Internet.

One technique where simply waiting 6 months works very well is in measuring parallax. The Gaia spacecraft takes advantage of this.

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

#58

Post by dotnet00 »

jeremyjh wrote: post #49
adgjlsfhk1 wrote: post #17

Earlier quoted context omitted.

GR and quantum field theory don't work together, so at least one of them is wrong, and it would be good to figure out which and how.

Why would that matter at this scale ?

Black holes are extreme enough to be one of the places where both can matter.

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

#59

Post by solarist »

yawz wrote: post #35

> EHT team members talk about a sharpness of vision akin to being able to see a bagel on the surface of the Moon. This is truly amazing!

Math actually checks out:

https://www.wolframalpha.com/input?i=diameter+of+moon+%2F+0....

~= 9 cm object on the moon

Google says donuts are 12-14 cm in length on average…

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

#60

Post by [deleted] »

mabbo wrote: post #48
markus_zhang wrote: post #11

Earlier quoted context omitted.

Just curious but why?

Quantum Physics and General Relativity make different predictions in specific circumstances which are beyond our ability to test to figure out which one is wrong. They can't both be perfectly correct. But in every test we can make, both seem to model reality really well. The best place to look for new data where we might find reality disagreeing with either model is in the extreme parts of the universe, like black ho…

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