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Uh, Oh: BICEP2 Results In Jeopardy?
In article , jacob navia
writes: Yes. That would completely destroy my argument. You have a reference where I could take a deeper look at that? Or the whole issue of foreground object contamination when studying the CMB? Put "CMB foregrounds" into your favourite search engines. There have been entire conferences devoted to this. Read the proceedings. |
#12
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Uh, Oh: BICEP2 Results In Jeopardy?
In article , "Robert L.
Oldershaw" writes: On Monday, May 19, 2014 3:00:49 PM UTC-4, Phillip Helbig---undress to reply wrote: papers on this. Someone once said that we know more about the centre of the Sun than the centre of the Earth. (1) If we understood the center of the Sun, we could explain the 22-year solar cycle, but it remains a mystery that we have not yet understood. I wrote MORE, not EVERYTHING. No, scientists don't know everything. That is why they continue to do science. (2) When I look at the cosmos and all of its structure on all the different scales, I would not call it "smooth". It is inhomogeneous right up to the largest reliably observable scales. To me a "smooth" and non-turbulent BB is a Platonic fiction First, there is a difference between the initial state and the current state. Otherwise, there would be no field of study called "structure formation". Second, the universe IS homogeneous on the largest scales; it is not inhomogeneous right up to the largest reliably observed scales. Yes, there are 2 or 3 people who---regardless of the state of observations---have been claiming that the universe has a fractal structure, but suffice it to say that they are a VERY small minority. Just because someone claims something doesn't make it true. I do not think we understand the details of the Big Bang event any better than we understand the center of the Sun, stellar formation, or especially galaxy formation. Just-so stories don't count as explanations. Who said it is a just-so story? The big bang is SIMPLE. Known physics predicts the light-element abundances, the CMB power spectrum etc etc. And I still doubt the preservation fine details about what was going on at 10^-30 sec after eons of time and what I believe to be turbulent expansion. Your "doubt" and what you "believe" are not science. Look at the detailed structure of a typical supernova remnant, then compare it with the detailed structure of the vast filamentary cosmic web, which is definitely not smooth. See any self-similarity? I see lots of that. Some people see Jesus on a burnt piece of toast. |
#13
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Uh, Oh: BICEP2 Results In Jeopardy?
Robert L. Oldershaw wrote:
(1) If we understood the center of the Sun, we could explain the 22-year solar cycle, but it remains a mystery that we have not yet understood. Solar neutrino fluxes do not show a 22-year time dependence, so we know that there is NOT a 22-year solar cycle in the center of the sun (which is where solar neutrinos are generated). So understanding the center of the sun doesn't really have much to do with understanding the solar cycle. -- -- "Jonathan Thornburg [remove -animal to reply]" Dept of Astronomy & IUCSS, Indiana University, Bloomington, Indiana, USA "There was of course no way of knowing whether you were being watched at any given moment. How often, or on what system, the Thought Police plugged in on any individual wire was guesswork. It was even conceivable that they watched everybody all the time." -- George Orwell, "1984" |
#14
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Uh, Oh: BICEP2 Results In Jeopardy?
On 5/20/14, 1:29 AM, jacob navia wrote:
Yes. That would completely destroy my argument. You have a reference where I could take a deeper look at that? Or the whole issue of foreground object contamination when studying the CMB? Thanks Don't forget that CMB is a Blackbody spectrum with maximum energy at 2.725K 160.6 GHz that theoretically continues to +or- infinity A millikelvin difference at T = 2.725 degrees may not be the same at .1 K or 1000 K. This may be reflected in: Planck 2013 results. XVI. Cosmological parameters http://arxiv.org/abs/1303.5076 "Despite the success of the standard LCDM model, this cosmology does not provide a good fit to the CMB power spectrum at low multipoles, as noted previously by the WMAP team. While not of decisive significance, this is an anomaly in an otherwise self-consistent analysis of the Planck temperature data." See figure 1."Planck foreground-subtracted temperature power spectrum--" Richard D Saam |
#15
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Uh, Oh: BICEP2 Results In Jeopardy?
In article , "Richard D. Saam"
writes: Don't forget that CMB is a Blackbody spectrum with maximum energy at 2.725K 160.6 GHz that theoretically continues to +or- infinity A millikelvin difference at T = 2.725 degrees may not be the same at .1 K or 1000 K. This may be reflected in: Planck 2013 results. XVI. Cosmological parameters http://arxiv.org/abs/1303.5076 "Despite the success of the standard LCDM model, this cosmology does not provide a good fit to the CMB power spectrum at low multipoles, as noted previously by the WMAP team. While not of decisive significance, this is an anomaly in an otherwise self-consistent analysis of the Planck temperature data." See figure 1."Planck foreground-subtracted temperature power spectrum--" This is more or less OK as far as it goes. However, note that the puzzle with low multipoles is mostly LACK of power. So, you would need foreground objects which somehow make the already smooth CMB even smoother at scales of several degrees to several tens of degrees. |
#16
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Uh, Oh: BICEP2 Results In Jeopardy?
In article ,
Martin Hardcastle writes: It is very, very hard to see how the large-scale structure in the CMB could be related to any known cosmological foreground object, so your conjecture can only be true if there are otherwise unknown, invisible, extremely large-scale foreground objects that affect the CMB via physical mechanisms that are not understood but that exactly mimic the expectations for primordial fluctuations in their power and frequency spectral properties. Just to emphasize, "spectral properties" means the supposed effect has to be the same at all frequencies. Most known foreground effects are strongly frequency-dependent, gravitational lensing being the only exception I can think of. -- Help keep our newsgroup healthy; please don't feed the trolls. Steve Willner Phone 617-495-7123 Cambridge, MA 02138 USA |
#17
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Uh, Oh: BICEP2 Results In Jeopardy?
On 5/21/14, 7:46 AM, Phillip Helbig---undress to reply wrote:
This is more or less OK as far as it goes. However, note that the puzzle with low multipoles is mostly LACK of power. So, you would need foreground objects which somehow make the already smooth CMB even smoother at scales of several degrees to several tens of degrees. Another interpretation of the CMB low multipoles anomaly is not in the foreground but in a non homogenous background: that there is something in the BBN process that generates a non continuous or clumpy phase incongruous with and perturbing the CMB continuous spectrum at low multipoles. Richard D Saam [Mod. note: quoted text trimmed -- mjh] |
#18
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Uh, Oh: BICEP2 Results In Jeopardy?
In article , "Richard D. Saam"
writes: On 5/21/14, 7:46 AM, Phillip Helbig---undress to reply wrote: This is more or less OK as far as it goes. However, note that the puzzle with low multipoles is mostly LACK of power. So, you would need foreground objects which somehow make the already smooth CMB even smoother at scales of several degrees to several tens of degrees. Another interpretation of the CMB low multipoles anomaly is not in the foreground but in a non homogenous background: that there is something in the BBN process that generates a non continuous or clumpy phase incongruous with and perturbing the CMB continuous spectrum at low multipoles. Again, at low multipoles there is LESS power, i.e. the CMB is SMOOTHER than one would otherwise expect. It seems rather a stretch to think that some clumpy phase during BBN (for which there is no evidence whatsoever) just happens to be the right size at the right place to smooth out the CMB. |
#19
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Uh, Oh: BICEP2 Results In Jeopardy?
On 5/27/14, 1:50 PM, Phillip Helbig---undress to reply wrote:
Again, at low multipoles there is LESS power, i.e. the CMB is SMOOTHER than one would otherwise expect. It seems rather a stretch to think that some clumpy phase during BBN (for which there is no evidence whatsoever) just happens to be the right size at the right place to smooth out the CMB. CMB power density 3.15E-03 erg/cm^2/sec as an expression of Black Body at 2.73 K does not vary across the sky. It is smooth at the millikelvin. (There is not smoother than smooth) In the = millikelvin range, it is perturbed by the foreground and/or background and in a particularly anomalous manner in the low multipoles. |
#20
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Uh, Oh: BICEP2 Results In Jeopardy?
In article , "Richard D. Saam"
writes: Again, at low multipoles there is LESS power, i.e. the CMB is SMOOTHER than one would otherwise expect. It seems rather a stretch to think that some clumpy phase during BBN (for which there is no evidence whatsoever) just happens to be the right size at the right place to smooth out the CMB. CMB power density 3.15E-03 erg/cm^2/sec as an expression of Black Body at 2.73 K does not vary across the sky. Of course it does. The structure in the CMB are temperature fluctuations. Yes, the strongest single is an almost perfect black body. The second is a strong dipole (due mostly to our motion). At a much lower level are temperature fluctuations. It is smooth at the millikelvin. (There is not smoother than smooth) Right. In the = millikelvin range, it is perturbed by the foreground and/or background and in a particularly anomalous manner in the low multipoles. Right. But at LOW multiples, i.e. LARGE scales, it has LESS power than the otherwise best-fit cosmological model suggests. So, if you think that the lack of power is due to foreground objects, these foreground objects would have to make the CMB more smooth than it would otherwise be on LARGE scales. (Again, at the mK level, of course.) |
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