On 12/4/19 3:04 pm, DecadentLinuxUserNumeroUno@decadence.org wrote:> Clifford Heath <no.spam@please.net> wrote in > news:ypTrE.86002$dN3.67291@fx20.iad: >> Some of the radiation used to make that picture came from the >> Earth... > Quite doubtful. >> 110 million years ago, and bent right around the black >> hole and back to us. > > Maybe you need to rethink/relearn what a black hole is.The picture was made by analysing radiation bent but not absorbed by the black hole. There are elliptic orbits with an exit asymptote 180 degrees from their entrance - i.e. one that returns to Earth some radiation that originated here.
OT black hole pic.
Started by ●April 11, 2019
Reply by ●April 12, 20192019-04-12
Reply by ●April 12, 20192019-04-12
On 12/4/19 9:54 pm, Clifford Heath wrote:> On 12/4/19 3:04 pm, DecadentLinuxUserNumeroUno@decadence.org wrote: >> Clifford Heath <no.spam@please.net> wrote in >> news:ypTrE.86002$dN3.67291@fx20.iad: >>> Some of the radiation used to make that picture came from the >>> Earth... >> Quite doubtful. >>> 110 million years ago, and bent right around the black >>> hole and back to us. >> >> Maybe you need to rethink/relearn what a black hole is. > > The picture was made by analysing radiation bent but not absorbed by the > black hole.Or maybe it wasn't - but the orbits still exist.
Reply by ●April 12, 20192019-04-12
On 4/11/19 11:15 PM, Clifford Heath wrote:> On 12/4/19 11:54 am, George Herold wrote: >> On Thursday, April 11, 2019 at 9:24:11 PM UTC-4, Dave Platt wrote: >>> In article <q8oo590a0m@drn.newsguy.com>, >>> Winfield Hill <hill@rowland.harvard.edu> wrote: >>> >>>>> It's always hard to tell real pictures from animations >>>>> and "artists conceptions." There should be a convention >>>>> to identify unreal images. >>>> >>>> These images have been called pictures, i.e., photographs, >>>> and I think that's a fair name. They're created from a >>>> 200GHz, "telescope" with a diameter of the whole earth. >>>> Made from data from multiple simultaneous radio telescope >>>> images, in perfect phase synchronization. The more you >>>> read about it, the more you'll agree this is a real image. >>> >>> The full set of papers which make up this report (there are six of >>> them) go into a lot of detail about the processing that was done. If >>> I recall correctly, there were no less than four independent teams, >>> working with several different sets of data-processing "pipelines", >>> working on the data, blinded to one anothers' results until the last. >>> I'm only partway through the reading, and I don't pretend to >>> understand all of the math (or even more than a fraction of it) but >>> it's a worthy learning effort nevertheless! >>> >>> Any form of image which is based on interferometry is necessarily >>> somewhat synthetic - the image which results is a best-fit result >>> generated from the data. There are, necessarily, interpolations made >>> in the process (that is, the data is "under-constrained") because the >>> interferometric relationship between any two of the radio telescopes >>> "sweeps out" only a limited set of parts of the image field during any >>> single recording pass. >>> >>> The teams seem to have gone to a lot of effort to make sure their >>> analysis process resulted in image data corresponding to "what was >>> there" rather than "what we expected to see". They tested the >>> analysis pipelines with synthetic image data first, artifically >>> generating this based on various models of what the emission source >>> might "look like", and confirming that the computed images actually >>> matched up to the models that generated the test data. >> >> It's very cool. I read that there was so much data, they transported >> it on planes, by wire would have taken too long. >> We should put a dish on the moon. :^) > > It's hard to beat the bandwidth of a jumbo jet full of disk drives. > > Some of the radiation used to make that picture came from the Earth... > 110 million years ago, and bent right around the black hole and back to > us. If we could increase the resolution a lot(*), we could get video of > live dinosaurs! > > (*) Quite a lot. In fact, a lot a lot alot! > > Clifford Heath.Probably not. At 110 million light years, the r**4 falloff would be a factor of roughly 350 dB on an areal basis. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20192019-04-12
On 4/11/19 11:27 PM, upsidedown@downunder.com wrote:> On Thu, 11 Apr 2019 18:54:27 -0700 (PDT), George Herold > <gherold@teachspin.com> wrote: > >> >> It's very cool. I read that there was so much data, they transported >> it on planes, by wire would have taken too long. >> We should put a dish on the moon. :^) > > This has been used for decades in VLBI. Previously each radio > telescope recorded the signal and clock sync on tape and the tapes > were flown to the correlator site, The different tapes were > synchronized and run through the correlator.So apparently they now use > disks instead of tapes. > > It is surprising that they still use disks, since for at least a > decade there has been a protocol for transferring very high data rate > interferometric data. Standard TCP/IP is useless, since the > transmission window would be filled, before the acknowledge frame > would be received from intercontinental distances. You might need > hundreds or thousands parallel TCP/IP tubes to fully utilize the > available bandwidth (up to 800 Gbit/s on a single DWDM fibre). > >You have to put the data someplace, so why make it more complicated? Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20192019-04-12
On 4/11/19 11:48 PM, upsidedown@downunder.com wrote:> On 11 Apr 2019 18:03:37 -0700, Winfield Hill > <hill@rowland.harvard.edu> wrote: > >> John Larkin wrote... >>> >>> On Thu, 11 Apr 2019, George Herold wrote: >>> >>>> My son shared this video by Vertasium on the black hole pic, >>>> https://www.youtube.com/watch?v=zUyH3XhpLTo >>>> >>>> https://www.youtube.com/watch?v=S_GVbuddri8 >>> >>> It's always hard to tell real pictures from animations >>> and "artists conceptions." There should be a convention >>> to identify unreal images. >> >> These images have been called pictures, i.e., photographs, >> and I think that's a fair name. They're created from a >> 200GHz, "telescope" with a diameter of the whole earth. >> Made from data from multiple simultaneous radio telescope >> images, in perfect phase synchronization. The more you >> read about it, the more you'll agree this is a real image. > > It is definitively a false color (black / red / yellow) image :-) The > recording was done on a single 1.3 mm wavelength.It's a 'flame palette'. I use them for rendering things like energy density and power dissipation in my EM simulator--they're pretty widely used. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20192019-04-12
On 4/12/19 12:28 AM, John Larkin wrote:> On 11 Apr 2019 18:03:37 -0700, Winfield Hill > <hill@rowland.harvard.edu> wrote: > >> John Larkin wrote... >>> >>> On Thu, 11 Apr 2019, George Herold wrote: >>> >>>> My son shared this video by Vertasium on the black hole pic, >>>> https://www.youtube.com/watch?v=zUyH3XhpLTo >>>> >>>> https://www.youtube.com/watch?v=S_GVbuddri8 >>> >>> It's always hard to tell real pictures from animations >>> and "artists conceptions." There should be a convention >>> to identify unreal images. >> >> These images have been called pictures, i.e., photographs, >> and I think that's a fair name. They're created from a >> 200GHz, "telescope" with a diameter of the whole earth. >> Made from data from multiple simultaneous radio telescope >> images, in perfect phase synchronization. The more you >> read about it, the more you'll agree this is a real image. > > I meant the other animations of the black hole that are mixed up with > the actual, very fuzzy radio telescope image. But more generally, the > silly artists' conceptions that are not always identified. > > I've seen versions of that actual image that are zoomed or otherwise > manipulated to look like movies. > > It sure was a ton of extended hype over that one fuzzy image. > >It's a pretty cool achievement, though. I remember seeing Gerd Binnig's first pictures of atoms taken with his STM thirty-odd years ago. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20192019-04-12
On 4/12/19 6:07 AM, Martin Brown wrote:> On 12/04/2019 10:35, Rodney Pont wrote: >> On Fri, 12 Apr 2019 09:44:45 +0100, Martin Brown wrote: >> >>> They have a very hard time of it. Every individual scope measures the >>> signal it sees with an H-maser timestamp. Then they combine every base >>> station with every other in pairs and aim to find the white light fringe >>> (the scopes use a finite bandwidth). Doing it at these frequencies >>> requires knowing all the baselines to a fraction of a wavelength. >> >> Do they only get one pixel at a time with radio telescopes and build up >> the image by putting them together after the session. I know visible >> and a bit either side can be done with sensors similar to those in my >> camera but I've not heard of a camera that can go down to radio >> frequencies. > > It is all interferometry so basically using Young's slits in reverse to > measure what you would see by placing a sine & cosine mask on the sky > and measuring total intensity passing through that shadow mask. > > You literally compute painstakingly the coherence function of every pair > of dishes along the track that each of the baselines sweep out as the > Earth rotates and then compute a model brightness distribution that is > consistent with those hard observational constraints. > > Everything gets measured and computed in the u-v plane of Fourier space > and is only converted into an x-y image plane at the very final step. > > There are a heck of a lot of tricky technical issues to make it work! >Yup. Synthetic aperture radar works in a similar way. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20192019-04-12
On 4/12/19 3:31 AM, N_Cook wrote:> On 11/04/2019 18:42, George Herold wrote: >> My son shared this video by Vertasium on the black hole pic, >> https://www.youtube.com/watch?v=zUyH3XhpLTo >> >> I thought it was nice. >> >> and this, >> https://www.youtube.com/watch?v=S_GVbuddri8 >> >> Amazing stuff. >> >> George H. >> > > A very scrappy pic for 4 petabytes (4 million gigabytes) of data >Its angular subtense is very very small. With that dataset, they could have made images at that resolution millions of times that size if there had been anything interesting enough and bright enough to look at. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●April 12, 20192019-04-12
Clifford Heath <no.spam@please.net> writes:> The picture was made by analysing radiation bent but not absorbed by > the black hole. There are elliptic orbits with an exit asymptote 180 > degrees from their entrance - i.e. one that returns to Earth some > radiation that originated here.A friend of mine was in the group, check out the 3rd last page (46) in this presentation to see how light originates and bends. Also describes the sites and data flows - there's not reasonable cost fiber everywhere, so HDDs are used: https://www.utu.fi/en/units/finca/research/Tuorla2015/programme/PublishingImages/Pages/home/Turku_2015_VLBI_lect_web.pdf
Reply by ●April 12, 20192019-04-12
On Friday, April 12, 2019 at 8:57:39 AM UTC-4, Mikko OH2HVJ wrote:> Clifford Heath <no.spam@please.net> writes: > > > The picture was made by analysing radiation bent but not absorbed by > > the black hole. There are elliptic orbits with an exit asymptote 180 > > degrees from their entrance - i.e. one that returns to Earth some > > radiation that originated here. > > A friend of mine was in the group, check out the 3rd last page (46) in > this presentation to see how light originates and bends. Also describes > the sites and data flows - there's not reasonable cost fiber everywhere, > so HDDs are used: > > https://www.utu.fi/en/units/finca/research/Tuorla2015/programme/PublishingImages/Pages/home/Turku_2015_VLBI_lect_web.pdfThe veritasium video does a nice 'high school level' explanation of where the light comes from. George H.
