Author Topic: Sagittarius A*  (Read 8638 times)

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Offline TimFoxTopic starter

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Re: Sagittarius A*
« Reply #50 on: May 14, 2022, 06:34:12 pm »
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If the accretion disk is visible as a ring from earth, it seems to be near orthogonal to the plane of our galaxis

The initial video from Veritasium explains that the accretion disk would appear to be orthogonal regardless of it's actual attitude (jump to around 19:45).

My understanding is that the reconstruction from interferometric data, being two dimensional with multiple baselines, produces a map in a plane orthogonal to the vector from the terrestial locations of the observatories to the object being imaged, which vector would be in (very close to) the galactic plane for an object near the center of the galaxy.
 

Offline aetherist

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Re: Sagittarius A*
« Reply #51 on: May 14, 2022, 09:18:15 pm »
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214 times 214 is 46,000 pixels of resolution.
32,000,000 pixels (the pixels in their blackhole image) divided by 46,000 is 700.
Hence the resolution of their blackhole image is  700 times the resolution of their array.

I think you are conflating capture resolution with display resolution.
Quote
According to Pierre Marie Robitaille
Maybe you should treat what he says more critically.
Yes capture resolution is 1/700 times the display resolution.
Have u seen/heard what Robitaille says?
His ground breaking MRI development probly was not based on array interference, but his analysis of the horizon array interference method looks good to me (if i could understand it).
 

Offline PlainName

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Re: Sagittarius A*
« Reply #52 on: May 14, 2022, 09:34:51 pm »
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Have u seen/heard what Robitaille says?

Precis the relevant part. I'm not going to sit through 3 hours of random videos trying to figure out which bit you think will make your point. If you understand it you can say it yourself.
 

Offline aetherist

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Re: Sagittarius A*
« Reply #53 on: May 14, 2022, 09:39:28 pm »
The massive object has an event horizon. The physics inside the event horizon is unknown and it will remain unknown. Everybody can use their own fantasy. For a scientist a singularity is enough of a model.
Of course the new images don't show the black hole but its cosmic ambient outside of its event horizon. As far as i understand gravitational red shift makes hard x-ray radiation observable as mm waves here on earth.
Regards, Dieter
I am thinking that xrays created near a blackhole would be created by atomic processes that are slower due to slower ticking of atomic processes due to the slowing of light & em radiation near a blackhole.
If so then the supposed xrays created near a blackhole would have a slower frequency (instead of having an xray frequency), ie they would have the same frequency as say ultraviolet radiation (depending on how far they were created from the blackhole).
Then when the ultraviolet frequency radiation reaches Earth it would be still have an ultraviolet frequency.
But u might be correct, it might have been a microwave all along (if it was created very close to the blackhole).
Anyhow i would not call that a redshift.
And of course i don’t believe in blackholes, but i do believe in supermassive bodies (brown holes).
 

Offline TimFoxTopic starter

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Re: Sagittarius A*
« Reply #54 on: May 14, 2022, 09:58:38 pm »
An interesting thing in the real physics of black holes in General Relativity is the case where the body is axially-symmetric (around a rotation axis) with angular momentum.  This is the "Kerr metric".
(The earlier Schwarzschild metric is for a spherically-symmetric case, where the body is not rotating.)  The math is very complicated, and I won't quote any of it here, but it is covered in the real textbooks, and even in Wikipedia.
It was published in 1963, followed by the "Kerr-Newman" metric for a rotating charged object.
A collapsed object that obeys this metric, as Sag A* is described to be, has two event horizons, instead of the single one in the Schwarzschild metric.
It leads to the "Penrose process" (q.v.), which can lead to loss of energy from the hole due to weird stuff happening between the two horizons.
This stuff was still new (1971) when I started grad school, and there was much discussion about the implications (which interested me, but I studied other stuff), since Chicago had a strong Astrophysics department.
Perhaps the best summary is in Chandrasekhar, Subrahmanyan (1999) Mathematical Theory of Black Holes Oxford University Press. ISBN 0-19-850370-9.
The late Prof. Chandrasekhar, whose name lives on in the modern x-ray observatory satellite, was the wisest man I ever had the fortune to meet (although I doubt he remembered me).
 

Offline aetherist

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Re: Sagittarius A*
« Reply #55 on: May 14, 2022, 10:13:34 pm »
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Have u seen/heard what Robitaille says?
Precis the relevant part. I'm not going to sit through 3 hours of random videos trying to figure out which bit you think will make your point. If you understand it you can say it yourself.
This Robitaille youtube might be the best of his i think 4. It is only 10 minutes 27 seconds long. I mention it in my reply#31. The bits at  7:00 & at  7:59 are gooder.
   
Sky Scholar     38K subscribers      Comments    814   length is 10:27.
The Black Hole Image - Data Fabrication Masterclass!    25,405 views  Jan 7, 2020  The Event Horizon Telescope Collaboration, First M87 Event Horizon Telescope Results.
Link to Professor Robitaille’s papers on Vixra: Pierre Marie Robitaille's…. https://vixra.org/author/pierre-marie_robitaille

In my reply#4 i mention another of his anti-blackhole youtubes which is  13:28 long.
Plus in #4 i mention some of his other youtubes that relate to blackholes – the durations are  11:49  &  6:41  &  14:42  &  7:59.
Plus in #4 i mention 2 youtubes by Stephen Crothers that relate to the silliness of Einsteinian blackholes – 6:42  &  5:24 duration.
These 8 youtubes add to  78 minutes.

A list of some of Pierre Marie Robitaille's papers.  But none appear to specifically target blackholes.
https://vixra.org/author/pierre-marie_robitaille
 

Offline PlainName

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Re: Sagittarius A*
« Reply #56 on: May 14, 2022, 11:28:01 pm »
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These 8 youtubes add to  78 minutes.

I don't care if they are 10 minutes. That's still 9:30 longer than it takes to read.

Quote
The bits at  7:00 & at  7:59 are gooder

Thank you.
 

Offline PlainName

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Re: Sagittarius A*
« Reply #57 on: May 14, 2022, 11:49:00 pm »
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The bits at  7:00

I am not sure how they work this stuff out, but I note that the data was acquired over 5 nights, and presumably the final is a composite of 5 sets of data. There will be subtle differences between each set and that could be used to enhance the resolution. Think of using a single sensor to scan along a line - the result is not one pixel wide. Although the result might have distinct steps (which would be your resolution), if you repeat the scan the steps would be in a slightly different place. Put them together and you have a higher resolution scan.

Further, my understanding is that each data point is not like a screen pixel, either on or off. As the sensor tracks across the target the signal will increase in magnitude and then fall off again as the signal received at each array machine goes in and out of phase with the other. So the pixels yon Pierre shows are probably incorrect as I think the real thing would not have sharp edges. Perhaps he was just demonstrating a grid, but then why fill them in?
 

Offline aetherist

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Re: Sagittarius A*
« Reply #58 on: May 15, 2022, 02:06:00 am »
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The bits at  7:00
I am not sure how they work this stuff out, but I note that the data was acquired over 5 nights, and presumably the final is a composite of 5 sets of data. There will be subtle differences between each set and that could be used to enhance the resolution. Think of using a single sensor to scan along a line - the result is not one pixel wide. Although the result might have distinct steps (which would be your resolution), if you repeat the scan the steps would be in a slightly different place. Put them together and you have a higher resolution scan.

Further, my understanding is that each data point is not like a screen pixel, either on or off. As the sensor tracks across the target the signal will increase in magnitude and then fall off again as the signal received at each array machine goes in and out of phase with the other. So the pixels yon Pierre shows are probably incorrect as I think the real thing would not have sharp edges. Perhaps he was just demonstrating a grid, but then why fill them in?
I am really impressed & pleased at modern technology. But at the limit i think that we naturally tend to push & fudge & cherrypick a little.

It reminds me of the beautiful LIGO ring down signal version of the quadrupolar gravitational waves emitted by 2 colliding blackholes, which as admitted later was merely an artist's masterpiece made for public consumption by their public relations team.

Meanwhile back at the ranch we need to ask how we could say see say a doughnut on the moon, if Earth's atmosphere causes so much twinkling, while at the same time there is say a bit of say haze & fog.

Robitaille says that the horizon team claim (explicitly or praps implicitly) a resolution 1250 times better than the resolution of a single dish (or praps he meant the resolution at a small array, if a small array) based on the problem of diffraction at a dish.

Just realized. I think that the horizon team invoke planar waves.
Why should the light etc from the BH be in the form of planar waves?
Why & how did the photons gladly form formations of waves?
I know that photons are sticky, & readily form waves (eg lasers), if given a good chance. So, duz propagating for thousands of years give photons enuff time to form formations?
Can photons form formations at 2 certain frequencies, while these photons are in the middle of lots of other photons having lots of other frequencies.
Do photons having the same frequency find each other, & then form formations (planar waves)?
And then retain these formations whilst surrounded by formations having other frequencies.
And then retain these formations whilst some parts of that wavefront is slowed by going throo or near to mass (eg stars, dust, air).

Nah, it smells fishy.


« Last Edit: May 15, 2022, 02:22:47 am by aetherist »
 

Offline TimFoxTopic starter

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Re: Sagittarius A*
« Reply #59 on: May 15, 2022, 02:50:33 am »
Do you know the meaning of "plane wave" in classical electrodynamics and electromagnetic waves?
 

Offline aetherist

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Re: Sagittarius A*
« Reply #60 on: May 15, 2022, 04:08:17 am »
Do you know the meaning of "plane wave" in classical electrodynamics and electromagnetic waves?
1.  Yes, a (cosmic) plane wave is an impossibility, as i explained above in my previous reply.
2.  And a (cosmic) non-plane wave is an impossibility.
3.  And  a (cosmic) wave is an impossibility.
4.  However, i am ok with there being a cosmic forced radio wave of sorts, with a forced wave shape, & a forced wavefront of sorts.
5.  But the wave in  4 can't be planar, no such thing, natural or forced.
6.  But, there can be versions that are nearly planar etc.
7.  1 & 2 & 3 are supposed to be a natural wave, ie waves of the standard rolling E to H to E etc supposed em radiation or somesuch associated with supposed photons. Nope, impossible.

https://en.wikipedia.org/wiki/Plane_wave#:~:text=In%20physics%2C%20a%20plane%20wave,a%20fixed%20direction%20in%20space.
 

Offline PlainName

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Re: Sagittarius A*
« Reply #61 on: May 15, 2022, 09:40:08 am »
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Meanwhile back at the ranch we need to ask how we could say see say a doughnut on the moon, if Earth's atmosphere causes so much twinkling, while at the same time there is say a bit of say haze & fog.

Well, let's not try and conflate things too much. First, when the talk is about seeing a doughnut on the moon, that isn't saying we can do that (successfully, anyway). It was said as being the equivalent of what they're doing with the black hole. That is, the angular resolution is equivalent. Doesn't matter if there was a brick wall in the way, the equivalence would be the same.

Next, you showed a photo of a doughnut and simulated what it might look like (I think - couldn't quite work out what that was about). When they say you could see a doughnut on the moon I take that NOT to mean you can see the sprinkles and all that stuff. I would seriously expect that they mean it would resolve to a single pixel. If you could see detail like pixels they'd say, instead, you could see a rice grain on the moon. See?

Moving on, with optical telescopes the distortion caused by the atmosphere is countered somewhat by using lasers to probe the local distortions and then compensate the capture appropriately. Don't know if the same thing, or similar, can be used for interferometry, but I reckon they would have taken that into account in some way. [Edit: something nags me that this technique isn't used to combat twinkling but something else. Naturally, IANAA.]

As to the image we are shown, I would assume that the bright spots we see are probably discrete pixels, and the whole is smoothed for public consumption. Imagine a 3x3 grid where our doughnut lights up the 2,4,6,8 pixels. On the nightly news that's going to look a bit shit, but feed it through a filter and there is your round hole, etc. No idea if that's what's done, but it is hardly cheating if they did.
« Last Edit: May 15, 2022, 09:50:42 am by dunkemhigh »
 

Offline aetherist

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Re: Sagittarius A*
« Reply #62 on: May 15, 2022, 10:19:06 am »
Quote
Meanwhile back at the ranch we need to ask how we could say see say a doughnut on the moon, if Earth's atmosphere causes so much twinkling, while at the same time there is say a bit of say haze & fog.
Well, let's not try and conflate things too much. First, when the talk is about seeing a doughnut on the moon, that isn't saying we can do that (successfully, anyway). It was said as being the equivalent of what they're doing with the black hole. That is, the angular resolution is equivalent. Doesn't matter if there was a brick wall in the way, the equivalence would be the same.

Next, you showed a photo of a doughnut and simulated what it might look like (I think - couldn't quite work out what that was about). When they say you could see a doughnut on the moon I take that NOT to mean you can see the sprinkles and all that stuff. I would seriously expect that they mean it would resolve to a single pixel. If you could see detail like pixels they'd say, instead, you could see a rice grain on the moon. See?

Moving on, with optical telescopes the distortion caused by the atmosphere is countered somewhat by using lasers to probe the local distortions and then compensate the capture appropriately. Don't know if the same thing, or similar, can be used for interferometry, but I reckon they would have taken that into account in some way. [Edit: something nags me that this technique isn't used to combat twinkling but something else. Naturally, IANAA.]

As to the image we are shown, I would assume that the bright spots we see are probably discrete pixels, and the whole is smoothed for public consumption. Imagine a 3x3 grid where our doughnut lights up the 2,4,6,8 pixels. On the nightly news that's going to look a bit shit, but feed it through a filter and there is your round hole, etc. No idea if that's what's done, but it is hardly cheating if they did.
Yes i think i am ok with all of that.
Yes the references to a doughnut on the moon is always simply to give an idea of a comparison of the angles of the dangles.
A doughnut would show that the usofa had been on the moon. A rice grain would show that the Chinese had been there.

My fuzzy pix of doughnuts were a failure. I wanted to show various levels of pixilation, but i don’t know of a program that duz that, so, i tried levels of fuzziness, but i couldn’t even do that properly.

I suppose that if one had 100 pix, each with say only 9 large pixels, then praps they could be combined to give a pseudo pix with 900 faux small pixels, & then a NASA computer could create some pseudo edges & pseudo outlines that might or might not be quasi accurate.

But my main problem with interferometry is that they assume a perfectly plane wavefront.
I have already said that there is no such thing as a wave, photons can't make such a wave (excluding small local manmade effects), ie 2 separate sets of waves, ie at 2 distinct frequencies, ie in the middle of an infinite number of sets of waves at every frequency.

I have not already said that a perfect planar wavefront is impossible, ie even before it gets near Earth, & even before it enters the atmosphere.
It appears to me that the horizon team require a perfect planar wavefront, to within one wavelength, or to within a small part of one wavelength, praps 0.001 wavelength.
And this perfection has to happen at the detector.
No, it has to happen at the counter-recorder, ie where the detector signal is finally recorded.

Now, here we have a problem. The signal has to go from the detector to the counter-recorder. Via wires probly.
Are the wires insulated?  What length of wire is needed? What effect duz temperature (of the Cu)(& of the insulation) have on the speed of electricity on the wire?
What is the Velocity Factor for electric energy on the wire (which is an antenna) for each of the 2 GHz? Bearing in mind that the VF varies with GHz.
How many individual waves are gained or lost along the wire due to temp etc at different times on different days?
Is the electric energy on the wires in the Poynting Vector?  Or is it in the electons? 
Have the horizon team watched the Veritasium youtubes?  Have the horizon team been following the EEVblog forum?
« Last Edit: May 17, 2022, 08:50:24 pm by aetherist »
 

Offline PlainName

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Re: Sagittarius A*
« Reply #63 on: May 15, 2022, 01:42:20 pm »
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Now, here we have a problem. The signal has to go from the detector to the counter-recorder. Via wires probly.
Are the wires insulated?  What length of wire is needed? What effect duz temperature (of the Cu)(& of the insulation) have on the speed of electricity on the wire?

Isn't that why you calibrate stuff? So you can determine that kind of offset and allow for it?
 

Offline TimFoxTopic starter

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Re: Sagittarius A*
« Reply #64 on: May 15, 2022, 02:14:23 pm »
Another lecture from a meeting in 2015:
https://www.eso.org/sci/meetings/2015/eris2015/L6_Heald_calibration.pdf
Those seriously concerned with this interesting engineering problem should consult the references contained therein.
 
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Offline aetherist

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Re: Sagittarius A*
« Reply #65 on: May 15, 2022, 02:25:49 pm »
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Now, here we have a problem. The signal has to go from the detector to the counter-recorder. Via wires probly.
Are the wires insulated?  What length of wire is needed? What effect duz temperature (of the Cu)(& of the insulation) have on the speed of electricity on the wire?
Isn't that why you calibrate stuff? So you can determine that kind of offset and allow for it?
Yes i suppose that u can calibrate for lots of factors.

But consider a large array of dishes. If each dish is identical to the others, & if each one has its own counter-recorder then u don’t have to worry about the length of wires (eg wires going to a central control room with the counter-recorder). But u still have the problem of the temp being different in different dishes. And, u also have the problem of having to synchronise the clock in each dish.

Or, if all of the dishes in the array are wired to a central counter-recorder (with a central clock) then u don’t have to worry about synchronising lots of clocks, but u do have to worry about different lengths of very long wires (which can be calibrated ok), but that calibration will not be able to handle any temp differences of the wires (temp affects the speed of electricity on the wires).

So, even if waves & wavefronts existed (which they don’t), & even of plane wavefronts existed (which they don’t), & even if the nearness of the mass of the Earth did not affect the plane of the wavefront (which it duz), & even if the atmosphere did not affect the plane wavefront (which it duz), then the problem of the varying speed of the signal along wires to the counter-recorder (due to temp diff)  would be an impossible problem.
Bearing in mind that they are looking at  1.3 mm long waves (i think), hence a difference of 1.3 mm in the speed of electricity in the wire (due to a diff of temp) would represent a full wavelength, & i am guessing that their image (for that array)  is messed up if the diff is merely a very small fraction of  1.3 mm.
 

Offline aetherist

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Re: Sagittarius A*
« Reply #66 on: May 15, 2022, 02:55:15 pm »
Another lecture from a meeting in 2015:
https://www.eso.org/sci/meetings/2015/eris2015/L6_Heald_calibration.pdf
Those seriously concerned with this interesting engineering problem should consult the references contained therein.
In my previous reply i mentioned the problem of the speed of electricity on a wire due to temperature.
In other threads on this forum i have advised that the speed of electricity along a wire will be affected by the aetherwind, which blows south to north through Earth at  500 km/s (which is c/600).

The horizontal component of the aetherwind at some locations on Earth can vary from say  140 km/s to 480 km/s during a sidereal day.  That’s a difference of  340 km/s (ie c/882).  Depending on the alignment of any wiring on a dish that  340 km/s might be a headwind or a tailwind or a crosswind (for the electricity), all of which affect the speed of electricity along the wire.
If the length of wire is 1 m then a diff of c/882 will show as in effect a diff of  1/882 in the length of the wire during the course of a day (here i mean that the wire might seem longer or shorter based on the time for electricity to propagate along the wire), & this 1/882 is  1.13 mm, which is almost one full wavelength (1.3 mm).
Do the horizon team calibrate for the aetherwind?  Nope.

However, the aetherwind would not be a big factor if each dish in an array had its own clock-counter-recorder, koz they would all be affected in equal measure.
But if there were long wires connecting to a central clock-counter-recorder then the aetherwind would be fatal.

More potential problems re the changing aetherwind during each 24 hrs, & during each orbit of the Moon, & during each orbit of the Sun.
The lengths of wires contract or dilate, which will change the time taken for electricity to propagate along a wire.
And dishes  change shape.
And atomic clocks change their rate.
« Last Edit: May 15, 2022, 03:08:19 pm by aetherist »
 

Offline PlainName

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Re: Sagittarius A*
« Reply #67 on: May 15, 2022, 02:55:57 pm »
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But consider a large array of dishes

I encourage you to check out the document Tim linked to.
 

Offline aetherist

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Re: Sagittarius A*
« Reply #68 on: May 15, 2022, 03:09:25 pm »
Quote
But consider a large array of dishes
I encourage you to check out the document Tim linked to.
I didnt see any calibration for aetherwind. At least not by name.
 

Offline PlainName

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Re: Sagittarius A*
« Reply #69 on: May 15, 2022, 03:20:14 pm »
One only needs to calibrate for things that exist.
 

Offline dietert1

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Re: Sagittarius A*
« Reply #70 on: May 15, 2022, 03:27:02 pm »
Your complaints may just reflect the complexity of the project and you may need to study one of the more technical papers cited in the publication that describe how the interferometry gets done. In youtube videos they show those disk packs and talk about jumbo jets full of them, but that won't answer your questions. Since i don't know a way to digitize a 220 GHz signal, i'd guess they use the hydrogen masers to mix the radio signls down into a 40 GHz or so bandwidth for which continuous digitization and recording exists. Then they probably use some pattern matching to recover phase relation between recordings at different telescopes.
I liked this video:

Obviously there will be a quest to improve the current measurement.

Regards, Dieter
 

Offline aetherist

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Re: Sagittarius A*
« Reply #71 on: May 15, 2022, 09:26:14 pm »
One only needs to calibrate for things that exist.
In many ways changes in the km/s of the aetherwind cancels itself out of measurements of length contraction & ticking dilation & can be ignored. 
Also, the aetherwind effect on the ticking of atomic clocks at an array in one location could be kept under control by ensuring that clocks were identical & orientated in the same direction & at the same level.
And dishes at an array are we know automatically kept in parallel alignments, nearnuff.

I mentioned that the speed of electricity will be faster if a tailwind along the wire. If the aetherwind increases in km/s then the speed of electricity increases by the same proportion. And, the true length of the wire contracts, possibly in accord with the standard equation for gamma (but i don’t think that that equation is good). Anyhow, these 2 effects would tend to negate at any one dish. Anyhow, these effects would tend to be identical at all dishes at that location, & hence would tend to negate overall.

But the aetherwind will hurt them every day, & every year, especially if they don’t minimize the hurt, or make allowances for the hurt.
 

Offline aetherist

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Re: Sagittarius A*
« Reply #72 on: May 15, 2022, 09:38:16 pm »
Your complaints may just reflect the complexity of the project and you may need to study one of the more technical papers cited in the publication that describe how the interferometry gets done. In youtube videos they show those disk packs and talk about jumbo jets full of them, but that won't answer your questions. Since i don't know a way to digitize a 220 GHz signal, i'd guess they use the hydrogen masers to mix the radio signls down into a 40 GHz or so bandwidth for which continuous digitization and recording exists. Then they probably use some pattern matching to recover phase relation between recordings at different telescopes.
I liked this video:
Obviously there will be a quest to improve the current measurement. Regards, Dieter
The only way out of their silly planar wave etc mess is if they use a fiducial marker of some kind to establish a zero point or a max point or somesuch.
This would automatically overcome lots of known shortcomings & praps non-known shortcomings.
The fiducial marker could enable simple analysis at any one location. And it might enable simpler analyses tween locations.
And then they could continue to crow about their naïve stupid skoolkid planar wavefronts, whilst actually not needing planar wavefronts & not using planar wavefronts.
The original Sagnac spinning mirrors X successfully used a fiducial zero marker.  It was the midpoint tween max fringe shifts on each exposed half of the photo, one half for each direction of spin.
Sagnac used his fiducial marker to help to show that the aetherwind existed.
The horizon team could use a fiducial marker for the opposite reason to Sagnac, they could use it to obviate the aetherwind.
https://en.wikipedia.org/wiki/Fiducial_marker
« Last Edit: May 15, 2022, 10:28:29 pm by aetherist »
 

Offline aetherist

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Re: Sagittarius A*
« Reply #73 on: May 15, 2022, 10:43:21 pm »
 

Offline aetherist

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Re: Sagittarius A*
« Reply #74 on: May 15, 2022, 10:52:16 pm »
https://arxiv.org/pdf/2202.04472.pdf

.....to simulate its full azimuthal extent; by contrast, we have truncated the polar range near the symmetry
axis to minimize numerical difficulties associated with having the polar axis in the domain. Our fiducial 2D and 3D
runs do not have synchrotron cooling. In the following, we
denote by me the mass of the electron.....

« Last Edit: May 15, 2022, 10:56:11 pm by aetherist »
 


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