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#11
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Critical Test for the Big Bang and Discrete Fractal Paradigms
Joseph Lazio wrote:
While interesting, if you're using intraday variability (IDV) in the usual sense, it is not mysterious. There have been quite convincing observations that IDV results from a radio-wave propagation effect in our Galaxy. replied: Would you please explain a bit more about the physics involved? What would be the cause of the "radio-wave propagation effect in our Galaxy"? Go to ADS http://adsabs.harvard.edu/abstract_service.html Type "scintillation radio waves interstellar" into the "Abstract words" box. Click on "submit". Scan the returned list of titles. Read a few abstracts, then a paper or two. Michael Richmond |
#12
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Critical Test for the Big Bang and Discrete Fractal Paradigms
Stupendous_Man wrote:
Go to ADS http://adsabs.harvard.edu/abstract_service.html Type "scintillation radio waves interstellar" into the "Abstract words" box. Click on "submit". Scan the returned list of titles. Read a few abstracts, then a paper or two. Michael Richmond Thanks for the recommendation. If you could identify a specific review paper that gives a good, up-to-date summary, I would welcome that. I had also downloaded astro-ph/0610737 by Mark A. Walker entitled Extreme Scattering Events: Insights Into The Interstellar Medium On AU-Scales", and started reading it. Is it generally accepted that there are previously-largely-unknown AU-sized, spherically symmetric "objects" composed of plasma, and in numbers possibly approaching 10^5 times the number of stars? Am I reading this correctly? Who ordered these objects? Robert L. Oldershaw |
#13
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Critical Test for the Big Bang and Discrete Fractal Paradigms
"re" == rloldershaw@amherst edu writes:
re Stupendous_Man wrote: Go to ADS http://adsabs.harvard.edu/abstract_service.html Type "scintillation radio waves interstellar" into the "Abstract words" box. Click on "submit". Scan the returned list of titles. Read a few abstracts, then a paper or two. re Thanks for the recommendation. If you could identify a specific re review paper that gives a good, up-to-date summary, I would re welcome that. Rickett (1990, ARAA, URL: http://adsabs.harvard.edu/cgi-bin/np...%26A..28..561R ) is a good place to start. Although a bit obscure, an extremely lucid discussion is in Narayan (1992, Proc. R. Soc. London A, 341, 1510. Finally, there are a couple of conference proceedings that are also useful: Cordes, James M.; Rickett, Barney J.; Backer, Donald C. Radio wave scattering in the interstellar medium; Proceedings of the AIP Conference, University of California, San Diego, CA, Jan. 18, 19, 1988 (I forget the title, but the proceedings are Astrophysics and Space Science, v. 278, Issue 1/2, p. 5-10, 2001.) re I had also downloaded astro-ph/0610737 by Mark A. Walker entitled re Extreme Scattering Events: Insights Into The Interstellar Medium re On AU-Scales", and started reading it. re Is it generally accepted that there are previously-largely-unknown re AU-sized, spherically symmetric "objects" composed of plasma, and re in numbers possibly approaching 10^5 times the number of stars? re Am I reading this correctly? I wouldn't say "previously-largely-unknown." Their effects were first reported by Fielder et al. (1987). As for their numbers, densities, and geometries, by-and-large all we measure are one-dimensional cuts through these objects (though that may be changing with some of Dan Stinebring's work). *If* one models them as spherically symmetric objects, then, yes, they do appear to have extreme properties. However, even a casual perusal of a dust cloud or similar image may cause one to wonder about the appropriateness of assuming spherical symmetry. re Who ordered these objects? I often wonder if the casual sci.astro reader understands my comment that I wasn't consulted about the design of the Universe. -- Lt. Lazio, HTML police | e-mail: No means no, stop rape. | http://patriot.net/%7Ejlazio/ sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html |
#14
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Critical Test for the Big Bang and Discrete Fractal Paradigms
Joseph Lazio wrote:
During the past month there have been no major developments regarding the critical paradigmatic test discussed above, but there has been at least one notable, although tentative, addition to the observational evidence. M.R.S. Hawkins has submitted a paper to A&A regarding timescale variations in AGN. Free copies can be obtained at www.arxiv.org , by searching on Hawkins or looking up astro-ph/0611491. In this paper data from two largescale AGN monitoring programs have been combined and analyzed for timescale variations. At this point one cannot unambiguously say whether the observed variations are due to microlensing or due to intrinsic variations by the quasar (or presumably some combination of the two). However, if the timescale variations are due to microlensing, then 1. the lower limit mass for the lenses is ~ 0.4 solar masses, and 2. the number of lenses must be significantly more abundant than the abundance inferred from the MACHO results (Alcock, et al, ApJ, 486, 697, 1997); moreover 3. the results are consistent with derived lens estimates of ~/ 0.2 solar masses for Q2237+0305 (Kochanek, C.S., ApJ, 605, 58, 2004) and ~/ 0.5 solar masses for Q0957+561 (Refsdal et al, A&A, 360, 10, 2000). So the new results are still tentative, but it cannot escape notice that this study joins a large and growing list of observations that *suggest* a very large number of dark matter objects within the conservative mass range of 0.1 - 0.6 solar masses. Excuse me for pointing this out again, but I think it is very important. The full range of possible masses for dark matter candidates extends over a range of 10^70. From within this enormous range, the Discrete Fractal paradigm predicted (see ApJ reference above) that the dominant galactic dark matter populations would be observed to fall within the mass range of 0.1 - 0.6 solar masses (two sharp peaks at 0.15 and 0.58 solar masses). Surely, the wait for a definitive resolution of the test cannot last too much longer (he says with a wistful sigh). Robert L. Oldershaw |
#15
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Critical Test for the Big Bang and Discrete Fractal Paradigms
In article ,
" writes: M.R.S. Hawkins has submitted a paper to A&A regarding timescale variations in AGN. Free copies can be obtained at www.arxiv.org , by searching on Hawkins or looking up astro-ph/0611491. In this paper data from two largescale AGN monitoring programs have been combined and analyzed for timescale variations. At this point one cannot unambiguously say whether the observed variations are due to microlensing or due to intrinsic variations by the quasar (or presumably some combination of the two). However, if the timescale variations are due to microlensing, then 1. the lower limit mass for the lenses is ~ 0.4 solar masses, and 2. the number of lenses must be significantly more abundant than the abundance inferred from the MACHO results (Alcock, et al, ApJ, 486, 697, 1997); moreover In other words, there must be a contradiction with the well studied MACHO result. Excuse ME for pointing this out again, but I've pointed out a couple of times here before (with refereed-journal references) that Hawkins's idea that QSO variability is mainly caused by microlensing is interesting, but doesn't stand up to a quantitative analysis. To those who work in the field, citing Hawkins as support of your idea is not going to lend it credibility; quite the opposite. To quote: "If the variations are interpreted as due to gravitational microlensing". Even if everything else is correct, this is an ASSUMPTION. However, this assumption has been ruled out, since if the variations were due to microlensing, the statistical properties of QSO light curves published by Hawkins himself should be different than what they are. Actually, one could probably rule out your idea, since if all the dark matter is in these objects, it WOULD cause significant QSO variability by microlensing, but that has been ruled out. You're in good company: your theory makes a testable prediction and was tested. It was ruled out. End of theory. No amount of selective citing will save it. |
#16
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Critical Test for the Big Bang and Discrete Fractal Paradigms
Phillip Helbig---remove CLOTHES to reply wrote:
Actually, one could probably rule out your idea, since if all the dark matter is in these objects, it WOULD cause significant QSO variability by microlensing, but that has been ruled out. You're in good company: your theory makes a testable prediction and was tested. It was ruled out. End of theory. No amount of selective citing will save it. You are remarkably sure of yourself! Would you go so far as to say that there is absolutely no chance that you could be wrong? My post clearly noted the tentative nature of the Hawkins paper. You say (without citing actual scientific evidence) that the microlensing interpretation for at least part of the variability has been ruled out. Apparently the editors and referees at A&A take a more open-minded view of the situation. Otherwise they would have rejected the paper or insisted that the microlensing interpretation be removed. Are we sure that we have considered an adequate range of possibilities for the spatial distribution and velocity distribution of the dark matter objects in the AGN setting, before summarily dismissing the whole idea? I suspect that those who do reject the whole idea are basing their rejection on an over-simplified models for those distributions. I think that it is quite possible that our understanding of QSOs is still rudimentary and contains significant gaps. Summary dismissals based on current understanding are probably premature. Robert L. Oldershaw |
#17
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Critical Test for the Big Bang and Discrete Fractal Paradigms
I am currently reading "A Survey of 56 Midlatitude EGRET Error Boxes
For Radio Pulsars" (ApJ 652, 1499-1507, Dec 1, 2006). Basically the story is as follows. The EGRET observations detected 50 to 100 gamma-ray sources at mid-Galactic latitudes. These sources are quite faint and have steeper spectra than their counterparts at lower latitudes; their energies are 100 Mev. The questions a What are these very faint but very energetic sources, and are we seeing the "tip-of-the-iceberg" type of situation where a very large population of high-energy sources is out there but are mostly just below current detection and resolution capabilities? The cited paper explores the possibility that these mystery sources are pulsars. Of the 56 source error boxes tested, 13 contained pulsars and 43 mystery sources remain a mystery. The authors conclude: "Non-pulsar source classes should therefore be investigated further" and noted that microquasars (black holes in binary systems) might be a possibility. It seems to me that a second front is opening up in the critical test of paradigms that is the topic of this thread. Previously I believed that microlensing were the best way to resolve the issue of whether or not there is a huge Galactic population of stellar-mass black holes, as predicted by the Discrete Fractal Paradigm. Now I am beginning to think that gamma-ray experiments may provide an equally important, and possibly more definitive, source of data for this test. Does anyone have updated information on the status of the advanced AGILE and GLAST satellites which were scheduled for launch somewhere in the 2006-2008 time frame? These missions offer order-of-magnitude increases in sensitivity in the important energy range of 1 Gev to 200 Gev. The combination of microlensing results and gamma-ray results should be extremely useful in answering the key question of this thread. Robert L. Oldershaw |
#18
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Critical Test for the Big Bang and Discrete Fractal Paradigms
wrote:
Regarding the critical test between the Discrete Fractal Paradigm and the Standard (Big Bang+Inflation) Cosmological Paradigm, which is the subject of this thread, some interesting observational results were made available last week. In astro-ph/0701325 at www.arxiv.org, Raiteri et al report on optical spectroscopic monitoring of the BL Lac object AO 235+164. Results for the broad line region do not fit well with a microlensing interpretation. Variations in the continuum flux coming from a smaller and more central region, on the other hand, are consistent with a microlensing interpretation. Most relevant to this discussion is the fact that the typical timescale of the variations (2-3 months) implies lens masses of ~10^-4 solar masses, as reported by the authors of this preprint. This is quite consistent with the predicted 8 x 10^-5 solar mass ultracompacts specified by the Discrete Fractal Paradigm. This class of planetary-mass dark matter objects is highly diagnostic since no other theory predicts anything remotely similar. These results are limited and tentative, but once again one of the two specific masses uniquely predicted by the DFP has found *empirical* support. Microlensing in a quasar (QSO 2237+0305) has recently been unambiguously identified and reported (astro-ph/0701300), but no mass estimates are given in their preprint. RLO |
#19
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Critical Test for the Big Bang and Discrete Fractal Paradigms
On Jan 15, 3:40 am, "
wrote: wrote: In an effort to keep this thread alive, since I hope that in the not- too-distant future some highly significant test results will become available, I offer a brief report on some new data on BL Lac variability and its possible interpretation in terms of microlensing. In astro-ph/0701420 at www.arxiv.org the authors Ciprini et al discuss the variability of the BL Lac object PKS 0735+178. This system had been monitored for decades and characteristic timescales in the variations are reported. The "rather achromatic behavior" has two general times scales: short-term events with timescales of roughly 27-79 days, and long-term events with timescales of 4.5-13 years. If my memory serves me well, numerous authors who have studied QSO microlensing, such as Refsdal, Gunn, Schild, Hawkins, Schneider, and many others, have demonstrated that the approximate timescales for stellar-mass lenses should be on the order of 10 years, and the approximate time scales for planetary-mass lenses should be on the order of 90 days. These two timescales are rough estimates that have to be refined to take into account the actual parameters of the system being studied. It is interesting that the newly reported data for PKS 0735+178 once again suggests the *possibility* of microlensing by two distinct populations of lenses: a planetary-mass population and a stellar-mass population. Clearly, one cannot claim that this new data changes the status of the "Critical Test" of this thread. It is one more piece of evidence that could be interpreted in a number of different ways. However, the new results reaffirm previous observations of two distinct timescales in the variability of distant QSOs and AGN. In the long run, this may be an important and diagnostic feature of QSO variability, and its possible microlensing interpretation. Robert L. Oldershaw |
#20
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Critical Test for the Big Bang and Discrete Fractal Paradigms
" wrote:
In an effort to keep this thread alive, since I hope that in the not-too-distant future some highly significant test results will become available, Thanks for reminding me of a question I've been wanting to ask here. I read that the Hubble suffered some major breakdown just short of its expected lifespan. I'm not claiming I have any idea what was lost in terms of hardware. I'm not claiming I know what the planned 2008 mission can return to service, either. What I want to know is, what was lost in terms of expected data that would have been settling or lending support/dismissal to some proposed solutions of some of the "big questions" here? What was "upcoming" that is now "indefinitely delayed"? Are other, planned tools going to provide this data later, or are we "back to square one" in some cases? IMWTK xanthian. |
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