Stargazing Event Horizon Telescope Results Released Yesterday (April 10, 2019)

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The Event Horizon Telescope (EHT) has released groundbreaking results, revealing the first image of a black hole, specifically Sagittarius A* at the center of the Milky Way and another in the Messier 87 galaxy. This image was created by combining data from a global network of radio telescopes, effectively forming a virtual telescope the size of Earth. The image shows the shadow of the black hole against its accretion disk, visualized through colorization that represents varying intensities of radio wave emissions. Discussions highlight the significance of this achievement in astrophysics, noting it as the first direct visual evidence of a black hole's presence rather than just a point-like object. The release has sparked interest in the implications for black hole theories, including Hawking radiation, and the need for clearer communication about the nature of the images presented to the public.
  • #121
sysprog said:
and no-one has examined all celestial objects to ensure that no 3 objects ever move along the same line for longer than an instant, and even given that a line has only 1 dimension, three moving 3-dimensional objects could as far we know remain aligned along some line forever, or at least for a lot longer than an instant, however long that might be.

The problem is that all objects are moving around in orbits, which don't allow for such a situation to occur. Even three objects initially moving along the same line would immediately deviate from that line as soon as gravity started acting on them. (Assuming we mean that the line passes through the center of each object, not just that the line passes through the object at any location)
 
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  • #122
sysprog said:
That would still be not only for an instant, but would instead be for as long as the size and speed and paths of concurrent line traversal of the objects allowed for them to remain co-aligned; however, the statement that I was suggesting might be more accurate if modified didn't include any provision that the objects had to be moving in different directions, and no-one has examined all celestial objects to ensure that no 3 objects ever move along the same line for longer than an instant, and even given that a line has only 1 dimension, three moving 3-dimensional objects could as far we know remain aligned along some line forever, or at least for a lot longer than an instant, however long that might be.
The problem is that all objects paths are determined by the effects of gravity and the laws of motion.
So for example, the Earth orbits the Sun in a (nearly) circular path. M87, the galaxy the telescopes were pointed at in in Virgo, so it pretty much is close to the orbital plane of the Earth. It is a distant galaxy, so the sight lines are for all practical purposes parallel, as represented by the white lines in this diagram.
SIGHTLINES.png

This shows sight lines for a 6 month period. white lines are sightlines to M87 An asteroid in between us an m87 would be orbiting further out ( and with a longer orbital period). And while it could just be possible for it to align with the sight lines joining Earth and m87 at three points during that 6 mo period if it were at the exact right distance from the Sun, the rest of the time, it would not be, as shown by the red lines. The type of trajectory the asteroid can follow is limited by the laws of physics and there just isn't any such trajectory that would keep it perfectly in line between Earth and M87 for more than brief moments.
 
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  • #123
Does anyone have any number on the total duration of exposure for this (radio) image?
Objects this distant are so faint they require long exposures just to get enough data.

Were this to be an alignment phenomena, such as an occultation by a dark body (one that would have to be a truly massive to create an Einsteinian Ring at all) it would have to stay aligned for the entire duration of all exposures.

And the brightness profile would be unique. As it passed into and out of alignment, we should see a partial ring before and after.

Also, we'd never see it again.

[ EDIT ] Oh. Duh. Six months duration.
 
  • #124
Drakkith said:
The problem is that all objects are moving around in orbits, which don't allow for such a situation to occur. Even three objects initially moving along the same line would immediately deviate from that line as soon as gravity started acting on them. (Assuming we mean that the line passes through the center of each object, not just that the line passes through the object at any location)
The statement to which I was taking mincing exception did not include your curative parenthetical restriction.
Janus said:
The problem is that all objects paths are determined by the effects of gravity and the laws of motion.
So for example, the Earth orbits the Sun in a (nearly) circular path. M87, the galaxy the telescopes were pointed at in in Virgo, so it pretty much is close to the orbital plane of the Earth. It is a distant galaxy, so the sight lines are for all practical purposes parallel, as represented by the white lines in this diagram.
View attachment 245404
This shows sight lines for a 6 month period. white lines are sightlines to M87 An asteroid in between us an m87 would be orbiting further out ( and with a longer orbital period). And while it could just be possible for it to align with the sight lines joining Earth and m87 at three points during that 6 mo period if it were at the exact right distance from the Sun, the rest of the time, it would not be, as shown by the red lines. The type of trajectory the asteroid can follow is limited by the laws of physics and there just isn't any such trajectory that would keep it perfectly in line between Earth and M87 for more than brief moments.
Thanks for that excellent illustration and explanation; please understand that I wasn't for a moment trying to argue that any possibility of occultation had anything to do with the M87 image. I opined that @sophiecentaur's statement that "... the motion of all celestial objects is such that no three objects can lie on a straight line (i.e. the same as a beam of light) for longer than an instant" was an overstatement of something that is almost, but not quite true. Sand falling in an hourglass can produce 3 moving grains lying along a straight line for longer than an instant.
 
  • #125
Itsnotablackhole said:
And Why are there no objects, stars planets, space debris being sucked into the black hole? And accelerating towards the black hole?
Things have to get pretty close to get sucked in but we can see them orbiting.


This time-lapse video from the NACO instrument on ESO's Very Large Telescope in Chile shows stars orbiting the supermassive black hole that lies at the heart of the Milky Way over a period of nearly 20 years.
 
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  • #126
Itsnotablackhole said:
"NO" I don't think all of these things are considered. I think people make mistakes. I think that people see what they want to see,,,, they look for the result they want to see,,,,, and do not look for the truth, with an open mind.

Then you're living in a make-believe world where science and engineering don't produce useful results and technologies, and one where people are so inept and close minded that they can do their work everyday and produce nothing useful, yet still think that they did.

That's not how the real world works the overwhelming majority of the time. Scientists and engineers are, on the whole, extremely competent people who try very hard to avoid the exact mistakes you're accusing them of making.

Itsnotablackhole said:
like when you said it can't be an asteroid, (rock) because it would transit (pass) the star more quickly, but that all depends on the direction of the asteroid, (rock) ,,,,,,not all asteroids move left to right,, across the telescope image, ,,,some move towards or away from the observer, slowing a transit time.

This has already been discussed in several posts before this. Over the time period required to take the images the Earth moved halfway through its orbit. There is absolutely no way for an asteroid to keep itself between us and our target for anywhere close to that length of time. It is impossible in every sense of the word.

Itsnotablackhole said:
However, I think they are looking in the right place for the black hole, but they have not found it, they have just found a rock, so far.

This is nonsense. Our telescopes are not seeing radio waves bending around a rock. It's hard to overstate the difference between the image of the black hole and an image generated by looking at the diffraction of radio waves around an object. Scientists simply aren't going to confuse the two.

Itsnotablackhole said:
We are all learning from each other, so

Forgive me, but I don't feel that you're making a serious effort to learn anything here.

Itsnotablackhole said:
I would appreciate any insight as to why there is no swirl? On the edge of the black hole disc.

Why would there be?

Itsnotablackhole said:
And Why are there no objects, stars planets, space debris being sucked into the black hole? And accelerating towards the black hole?

Because black holes are not vacuum cleaners. They don't suck anything in. If the Sun collapsed into a black hole right now, the Earth and all the planets and other objects in the solar system would simply go about orbiting just as they always have. There would be essentially no change. None of them would be sucked into the new black hole.

In order for something to fall into a black hole, it has to lose enough energy to lowers its orbit to within a very close distance to the event horizon. Gas clouds do this by losing energy between collisions of gas atoms. The gas is heated because of these collisions and the energy is radiated away as EM radiation. This energy initially came from the energy the gas had in its orbit, so parts of the gas gradually fall closer and closer to the black hole as more and more energy is radiated away.

But with large objects like planets, there is rarely anything to interact with that can drop their orbits to the point needed to fall into a black hole.
 
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  • #127
Itsnotablackhole said:
"NO" I don't think all of these things are considered. I think people make mistakes. I think that people see what they want to see,,,, they look for the result they want to see,,,,, and do not look for the truth, with an open mind.
Thanks for parsing your ideas into paragraphs this time.

I agree with nearly all of what @Borg and @Drakkith said; they posted while I was composing this post. I also agree with nearly all of what @sophiecentaur and other prior posters said in this thread.

Your third sentence looks to me as if you are saying something that would entail that the scientists who created and presented the M87 work and the commentary about it are not really honest enough to be scientists, but you've presented nothing in support of such a charge.
You say that these things are considered for no more than a second,

like when you said it can't be an asteroid, (rock) because it would transit (pass) the star more quickly, but that all depends on the direction of the asteroid, (rock) ,,,,,,not all asteroids move left to right,, across the telescope image, ,,,some move towards or away from the observer, slowing a transit time.
Are you using extra commas to indicate longer pauses? That's not necessary when you're writing things here on PF. The ideas are what matters.
I double check everything,
Some errors that might otherwise be missed can be caught that way.
Asteroids can travel in more directions than just left to right .
The observers of the radio-telescope arrays can reliably distinguish an asteroid inside the solar system from a supermassive object that is thousands of light-years away. It may be possible that the M87 object is "not a black hole", as your username appears to postulate, but it's not even remotely close to reasonable to suggest that it might be a local asteroid.
Maybe the entire problem, is, some don't spend a long enough time with the problems of what if?
Scientists spend a great deal of time pondering 'what if' questions; however, human lives are of limited duration, so everyone who ponders such questions must prioritize, in order to avoid spending too much time on thinking about things with too little likelihood of ever turning out to yield worthy insight.
However, I think they are looking in the right place for the black hole, but they have not found it, they have just found a rock, so far.
Please double-check that sentence. Apparently, you agree with the idea that there is a supermassive black hole somewhere near the center of the galaxy, and you agree that "they", i.e. people who are among our most competent and best equipped scientists, are "looking in the right place for the black hole", and yet you apparently think that their best efforts are susceptible to the error of mistaking an asteroid for it.
I want to see the real deal myself, as well, but I want to be sure it is the real deal.
I can relate.
There are many people who have serious doubts about the validity of the first black hole photo.
Do you have any sources that you can cite in support of that assertion?
We are all learning from each other, so
We're not all equals in that regard. Some of us know a great deal more than others about some things. I'm confident that many people know much more than I do about many things. Not only that, it is also apparent to me that some people here on PF are not only more knowledgeable in their subject areas than I am, but are also better at imagining and reasoning about them than I am.
I would appreciate any insight as to why there is no swirl? On the edge of the black hole disc.

And Why are there no objects, stars planets, space debris being sucked into the black hole? And accelerating towards the black hole?
I concur with the responses of @Borg and @Drakkith on this.
Thank you
Your courtesy is appreciated.

Scientists are not strangers to skepticism; however, the questions and speculations that you are posing appear, at least to me, to not pass basic criteria of reasonableness.
 
Last edited:
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  • #128
Itsnotablackhole said:
It was assumed I meant asteroid in this solar system, I did not, sorry, I should have been clearer. Asteroid in any solar system between us and the centre of the galaxy.
You should use simple geometry to calculate how big such an asteroid would need to be. Then you'll realize how impossible that idea is.
 
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  • #129
russ_watters said:
You should use simple geometry to calculate how big such an asteroid would need to be.

Further, if you had an asteroid that large, it would become a black hole.
 
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  • #130
lpetrich said:
Messier 87 - Wikipedia -- someone updated that article very quickly. For the central black hole, M87*, the article quoted mass estimates like ##(3.5 \pm 0.8) \times 10^9## and ##(6.6 \pm 0.4) \times 10^9## solar masses, with a 2016 estimate of ##7.22{}^{+0.34}_{-0.40} \times 10^9## solar masses. The EHT consortium's estimate is ##(6.5 \pm 0.2_{stat} \pm 0.7_{sys}) \times 10^9## solar masses.

Those other mass estimates were made using the velocities of the stars and interstellar gas that surround the BH. They are well within the Newtonian limit, so the success of extrapolating toward the BH's event horizon is a success for GR, along with the approximately circular shape of the BH's shadow.

I read that there are actually two different results, one assumes that dark matter exits and other doesn't , assuming dark matter is real, calculations say it's mass is around 6.6 billion solar masses and without dark matter, calculations say it around 3.5 billion solar masses.

https://qr.ae/TWtsod
 

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