đđđ On Fri, May 13, 2022 at 12:45 AM David Eric Smith <[email protected]> wrote:
> Hi Gil, > > Yes, several good questions, some with answers, some not known. > > Ok now that I got that out my system: > I had wondered if this is the same science stunt we used to image a > blackhole...but what are they using as a light source > > > The light is actually being generated by gas or dust that spirals very > fast around the black hole itself. Things that swirl around a central > object donât move cleanly. There is a lot of turbulence and collision, and > they heat up. Because the infall around BHs is so fast, they get very hot > and glow. > > As for what frequencies they use to observe, I think it is an intersection > of three considerations: 1) it has to be a wavelength long enough that the > telescopes can get phase coherence, which I think means somewhere in the > radio (microwave might be possible in principle, but quite difficult); 2) > it has to be a wavelength that somewhat gets through all the dust between > the center of the galaxy and us (I think this is the main limitation); and > 3) it has to be some frequency that the BH actually emits. Small ones like > BHs from single stars might emit in X-rays, but I think the large ones in > galaxy centers are mostly radio sources, unless they produce jets that > create a secondary source of light. (Check me on this; I could be way off.) > > and how do decide on the galaxy's center > > > I think people now believe that most galaxy centers have these large BHs > in them. Itâs remarkable that 50 years ago, that had not been suspected. > When I was a kid, I read an old Asimov book âQuasar, quasar, burning > brightâ, in which none of this was even a main theory. > > was this also created by the sheer weight of the galaxy? > > > This is the thing nobody knows. They are so large, and the seem to have > formed so early, that it doesnât seem possible for star-sized BHs to form > and then to merge. BHs tend to clean out the dust from the environments > where they are for a long time, and without extra frictions, things just > orbit for a long time, but donât collide. I donât know the details on how > people think about this in the best version. > > or did a star go kaboom their good knows when and it just happened to be > more or less dead center of the galaxy? > > > It seems people believe that the gathering that forms the galaxy is > somehow related to the formation of dense things, and eventually BHs, at > the center. But I donât know. > > and are they all shaped like a toilet? > > > They are actually among the roundest things in the universe. The ring, I > think, is a very special kind of orbital effects. > > I taught with a physics prof. In Austin who used to explain mechanics to > students in a way I liked. He said âThe moon is falling toward the earth, > just like an apple would. Itâs just that the moon is moving sideways, so > it keeps missingâ. And thatâs all orbits are. Theyâre falling inward, but > they keep missing. > > Where spacetime starts to tip very strongly near the event horizon, you > can do that with light. There is a certain radius where light, traveling > sideways, just goes in an orbit. A bit further in, light shining directly > outward never gets further out (that is the event horizon). So I think the > ring effect isnât so much that the glowing gas makes any kind of a ring, > but because there the light gets condensed into orbits, and when we look at > it, it is the light just outside that orbital radius that eventually beams > at us. The orbits can be going all around the BH, covering the sphere in > any direction, but where we look at the central region of the disk, it is > shining âsidewaysâ, and doesnât eventually beam out to us in a way that > looks like it came from there. > > There are images of GR models, some of which got used in that Matthew > McConaughey movie, to suggest what it would look like if you were close by, > and didnât have the combination of lensing distortions, dust, and telescope > resolution limitations. I think it gives that ring look from any > direction, so this doesnât have anything to do with rotating disks. In any > case, if there were a disk, we wouldnât see it face-on, because it would be > in the same plane of the galaxy as we are. > > Eric > > > > On Thu, May 12, 2022 at 8:08 PM David Eric Smith <[email protected]> > wrote: > >> Yeah, good stuff. >> >> Iâm not sure when I first heard about the ALMA upgrade that would give >> them phase coherence across the telescopes at the frequencies the EHT is >> using, and data archiving that would allow them to try to coherently >> register telescopes sited all around the world. It feels like about a >> decade ago. I have been waiting, since that first notice, to see this >> picture. The M87 image a couple years ago was the resolution of the real >> cliffhanger â whether they could get it to work at all â but this one was >> even 2+ years harder to push through technically. >> >> I donât imagine I would want to do that work. It seems like an >> incredible tedious grind, made for real professionals. But I am very glad >> to be a consumer of the outcome. >> >> Eric >> >> >> >> On May 13, 2022, at 11:02 AM, Gillian Densmore <[email protected]> >> wrote: >> >> https://www.nytimes.com/2022/05/12/science/black-hole-photo.html >> >> and it looks a bit like something melting on icecream. fudge or caramel >> -. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. . >> FRIAM Applied Complexity Group listserv >> Fridays 9a-12p Friday St. Johns Cafe / Thursdays 9a-12p Zoom >> https://linkprotect.cudasvc.com/url?a=https%3a%2f%2f%2f%2fbit.ly%2fvirtualfriam&c=E,1,g4nNB9lId8M23hD2WsamUUHKMiSCjJePmyzMOQcT1owkCEiv33l21SxdXAuWv6NnKPbMuEQEkoMHTtKZmQdubAMCmkFwpBKkaeVptVwgtnIO7FUMXA,,&typo=1 >> un/subscribe >> https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fredfish.com%2fmailman%2flistinfo%2ffriam_redfish.com&c=E,1,tB-5WFDpRpXnEpC__CblcLZYsVkkK_KcQSrz2RFubdvXeUO3mNsX66x1bRINNwyULXBWnuuxT30OrrBQUoWE9bBzCt0yhzfyOkXthh4iKRjM0GTea0mZFpL6Bg,,&typo=1 >> FRIAM-COMIC >> https://linkprotect.cudasvc.com/url?a=http%3a%2f%2ffriam-comic.blogspot.com%2f&c=E,1,E9TNNRcyezY-Riuyjhrs0n5KeGguwDXKiSiiMtspnqfNgCgmlFYyf-UHQLcz4Va7UXpP6-TXvUHvgndjZl6bmNjjadexHY7xJyplJe0sVazKrMBEA2qDug,,&typo=1 >> archives: 5/2017 thru present >> https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fredfish.com%2fpipermail%2ffriam_redfish.com%2f&c=E,1,2RdcgQPrfWS0dIFzI4AgZcrhu4Z1MTuSaXb_lBaw2mkjtx6IPReajVomwTdtitLSRSNRyllE9Q_1mBoPjNDfKL6dqdT93iJXEX02vjDYG6xOKFHur8IX&typo=1 >> 1/2003 thru 6/2021 http://friam.383.s1.nabble.com/ >> >> >> -. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. . >> FRIAM Applied Complexity Group listserv >> Fridays 9a-12p Friday St. Johns Cafe / Thursdays 9a-12p Zoom >> bit.ly/virtualfriam >> un/subscribe >> <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fbit.ly%2fvirtualfriamun%2fsubscribe&c=E,1,Sx3h8uJK34nQWYXVzGsGDxnk0rHQ8vs3rTIXtmjzGTQMWAi7q-PtLzN9gtf6XdpDY3eWfy7Ny2tyK73b9tHFgG_oG0_-4rLIxuMhK8NOKM2txixXZbjWXWW4&typo=1> >> http://redfish.com/mailman/listinfo/friam_redfish.com >> <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fredfish.com%2fmailman%2flistinfo%2ffriam_redfish.com&c=E,1,yODfz8ytxLHPLBSlgEnq3--9ZKYJtkmzd1PvZIsBdn_LN6HqcbXDNYHMEfy2r-3_aahs6n6Y649laf79Sx7P9KvRhz9zWxGwqeqiAF5-aVXuLA,,&typo=1> >> FRIAM-COMIC http://friam-comic.blogspot.com/ >> <https://linkprotect.cudasvc.com/url?a=http%3a%2f%2ffriam-comic.blogspot.com%2f&c=E,1,btLMPsMn6rNtuGbWV3mgDPiRQBjaWp4ylDJmEyfFPw0OI5wpMSHNixvSJAX3yeNgg96XXZORNLhZqOFw5ySogDO2ArNxrXmOidKwwFiXn0oi&typo=1> >> archives: 5/2017 thru present >> https://redfish.com/pipermail/friam_redfish.com/ >> <https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fredfish.com%2fpipermail%2ffriam_redfish.com%2f&c=E,1,oEL4y-gfeageAoLW48CqJK9RSG3Q-2yZ-F72RCUKtLNYK5hq5feP9XhmQ1fT0nV2gHGj0LzaFBNoSDiAJhRq0mdBPcuHAbjLFHJKHUvBRBk4EVxsi4RDLlc,&typo=1> >> 1/2003 thru 6/2021 http://friam.383.s1.nabble.com/ >> > -. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. . > FRIAM Applied Complexity Group listserv > Fridays 9a-12p Friday St. Johns Cafe / Thursdays 9a-12p Zoom > https://linkprotect.cudasvc.com/url?a=https%3a%2f%2f%2f%2fbit.ly%2fvirtualfriam&c=E,1,-craH6Ofllo6j_c7CFw4Jl4DZKO9ZMnfRDGag8UJEneyEspbe4pdqVcP1mYTXfUZl7yfXsBNwD0T5pSA5XxnU-vuR0Tk1iCuDQo1QCMewEGYNwhEDQ,,&typo=1 > un/subscribe > https://linkprotect.cudasvc.com/url?a=http%3a%2f%2fredfish.com%2fmailman%2flistinfo%2ffriam_redfish.com&c=E,1,srn6mFvgclpO3Xlj9XX0x95b2sr8rUKUxz9xbLHGkagWmIZdZKdqRjTbXJ75hZByvGmoLcUxh_ihEMTQN0UGSEz4EswSZtMQg5p8rb7LmN-0lA,,&typo=1 > FRIAM-COMIC > https://linkprotect.cudasvc.com/url?a=http%3a%2f%2ffriam-comic.blogspot.com%2f&c=E,1,YP5RESa6jnatzUfnA1Mrjhajyqku4wCQhv68y-n6BGD05sKbhyq8-COKqr4LToHQLEdt6_sL8mAetmPYBKHDlUbIg1u31B3UFw1nFT4uaZ5w_5c5iFgukmqO1A,,&typo=1 > archives: 5/2017 thru present > https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fredfish.com%2fpipermail%2ffriam_redfish.com%2f&c=E,1,juyiU48N0DT61UEuODpbAQIYCA30iBr_EoaJP3J-0BDmXATfNPRAdMYBc99rCkMo5KKZ5yD8rAI8ZxJV1Xf7EYVUdadv5gr6EdFaIKj1WVQKDfHu5ek,&typo=1 > 1/2003 thru 6/2021 http://friam.383.s1.nabble.com/ > > > -. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. . > FRIAM Applied Complexity Group listserv > Fridays 9a-12p Friday St. Johns Cafe / Thursdays 9a-12p Zoom > bit.ly/virtualfriam > un/subscribe <http://bit.ly/virtualfriamun/subscribe> > http://redfish.com/mailman/listinfo/friam_redfish.com > FRIAM-COMIC http://friam-comic.blogspot.com/ > archives: 5/2017 thru present > https://redfish.com/pipermail/friam_redfish.com/ > 1/2003 thru 6/2021 http://friam.383.s1.nabble.com/ >
-. --- - / ...- .- .-.. .. -.. / -- --- .-. ... . / -.-. --- -.. . FRIAM Applied Complexity Group listserv Fridays 9a-12p Friday St. Johns Cafe / Thursdays 9a-12p Zoom bit.ly/virtualfriam un/subscribe http://redfish.com/mailman/listinfo/friam_redfish.com FRIAM-COMIC http://friam-comic.blogspot.com/ archives: 5/2017 thru present https://redfish.com/pipermail/friam_redfish.com/ 1/2003 thru 6/2021 http://friam.383.s1.nabble.com/
