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Quasar variation - no time-dilation found by Mike Hawkins
The observed frequency spectrum of quasar luminosity variation should be
good probe for time dilation. If quasar redshift is caused by Doppler, then high redshift quasars should show slower variations in luminosity due to time-dilation caused by their rapid movement away from us. A paper on this topic was written in 2001 by Mike Hawkins of Edinburgh University. I find it very impressive. It is cited by Jerry Jenkins paper "Supernovae Light Curves: An Argument for a New Distance Modulus" http://arxiv.org/abs/astro-ph/0404207. Time Dilation and Quasar Variability M.R.S. Hawkins http://www.roe.ac.uk/roe/staff/ http://arxiv.org/abs/astro-ph/0105073 http://adsabs.harvard.edu/cgi-bin/np...pJ...553L..97H The timescale of quasar variability is widely expected to show the effects of time dilation. In this paper we analyse the Fourier power spectra of a large sample of quasar light curves to look for such an effect. We find that the timescale of quasar variation does not increase with redshift as required by time dilation. Possible explanations of this result all conflict with widely held consensus in the scientific community. Hawkins convincingly shows that the degree of optically observed luminosity variation - measured at frequencies such one cycle per 10 years to one cycle per fraction of a year - is not correlated with the quasar's redshift. He also determines the relationship between shorter wavelengths and faster variation - and shows that this can at best explain only a fraction of the observed effect. This is based on his own measurements of two decades or so of photographic plates - he is not relying on anyone else's observations or interpretations. He seems unwilling to consider this findings a challenge to the Big Bang Theory: Taking the various arguments outlined above at face value, and accepting the case against microlensing, there does not appear to be a satisfactory explanation for the absence of a time dilation effect in quasar power spectra. The arguments resting on an expanding Universe and cosmological distances for quasars seem beyond challenge. The argument against microlensing is not so secure. I see a parallel here with the researchers whose apparently assiduous research failed to find the expected Transverse Proximity Effect with a foreground quasar. (See: http://astroneu.com/plasma-redshift-1/#TPE ) I see both the lack of TPE and this work on the lack of quasar time-dilation as separate, excellent, disproofs of the Big Bang Theory. But the researchers themselves either fail to consider this or silently reject it, preferring what to me and to many others seems an impossible alternative explanation. For the TPE people, it is that quasars turn on and off, or have very limited lifetimes. For Mike Hawkins, it is that quasar variations are caused primarily by the gravitational microlensing effects of many dark matter bodies traversing the line of sight. I think that these researchers evident consternation at their own results, combined with what appears to be excellent research and data reduction, makes these two sets of research all the more convincing as evidence against the BBT. Below I chase references and Google links for this paper. I found nothing of substance beyond the Jerry Jensen citation and what follows: First, two citations from papers by the same author: Colour changes in quasar light curves Hawkins, M. R. S. MNRAS Vol 344 Issue 2 Page 492 - September 2003 http://arxiv.org/abs/astro-ph/0406161 http://adsabs.harvard.edu/cgi-bin/np...MNRAS.344..492 Naked active galactic nuclei M.R.S. Hawkins 2004 June 7 http://arxiv.org/abs/astro-ph/0406163 but I don't think these add much to the original paper - they seem to pursue his microlensing theme. Here are two papers which seem promising. Fourier Analysis of Gamma-Ray Burst Light Curves: Searching for a Direct Signature of Cosmological Time Dilation Chang, Heon-Young http://arxiv.org/abs/astro-ph/0106220 http://adsabs.harvard.edu/cgi-bin/np...pJ...557L..85C Heon-Young Chang has some other papers of potential interest. Can microlensing explain the long-term optical variability of quasars? Zackrisson, E.; Bergvall, N.; Marquart, T.; Helbig, P. http://arxiv.org/abs/astro-ph/0306434 http://www.astro.uu.se/~ez/papers/variability.pdf http://adsabs.harvard.edu/cgi-bin/np...6A...408...17Z Although controversial, the scenario of microlensing as the dominant mechanism for the long-term optical variability of quasars does provide a natural explanation for both the statistical symmetry, achromaticity and lack of cosmological time dilation in quasar light curves. (They accept Haw kins' research and go fishing for microlensing.) Here, we investigate to what extent dark matter populations of compact objects allowed in the currently favored OmegaM=0.3, OmegaLambda =0.7 cosmology really can explain the quantitative statistical features of the observed variability. We find that microlensing reasonably well reproduces the average structure function of quasars, but fails to explain both the high fraction of objects with amplitudes higher than 0.35 mag and the mean amplitudes observed at redshifts below one. Even though microlensing may still contribute to the long-term optical variability at some level, another significant mechanism must also be involved. This severely complicates the task of using light-curve statistics from quasars which are not multiply imaged to isolate properties of any cosmologically significant population of compact objects which may in fact be present. The problems with microlensing seem to be severe enough to write it off as the major explanation for Hawkins' observations - but they don't seem to consider that maybe the Universe is not expanding. I think Mike Hawkins' paper is important and should be discussed more widely. - Robin http://astroneu.com |
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Quasar variation - no time-dilation found by Mike Hawkins
Thanks Phillip for responding and clarifying some things about your paper.
RW The problems with microlensing seem to be severe enough to write it RW off as the major explanation for Hawkins' observations PH I agree. Further objections to microlensing being the sole cause include the time delays in the longer-wavelength changes compared to shorter-wavelength changes. Here are two diagrams showing 20 or so years of variation in optical, IR and microwave wavelengths by 3C 273: http://astroneu.com/misc-files/3c273...-curves-x5.gif http://astroneu.com/misc-files/3c273...with-lines.gif derived from: 30 years of multi-wavelength observations of 3C 273 Türler M., Paltani S., Courvoisier T.J.-L., et al., 1999, A&AS, 134, 89 http://obswww.unige.ch/3c273/ Peaks at various wavelengths tend to be correlated in time, with longer wavelengths lagging the shorter. I think the 3C 273 curves stand as a good example of a phenomena which has been well studied, for instance: Optical and radio variability in blazars Hufnagel, Beth R.; Bregman, Joel N. http://adsabs.harvard.edu/cgi-bin/np...pJ...386..473H I think that most or all of the observed variations are compatible with current theories of black hole accretion disks, with their emissions energising and reflecting from material at greater distances. Such variations seem to be required by any black-hole theory, which seems unavoidable in explaining many other quasar observations. This seems to rule out microlensing as the sole cause of the observed variation. Furthermore, if the Universe really is expanding, then if microlensing was the cause of the observed variations, we would expect time dilation in the statistical properties of the microlensing of more distant objects since some or most of that microlensing would be caused by more distant objects which would be receding from us at higher velocities. Put another way, if microlensing is responsible for the variations, and we see no time correlation between its statistics and the redshift of the quasar, then, if the distance scales with redshift, we might have to conclude that the microlensing was always occurring close to Earth, which seems unacceptable for a number of reasons. I think we can agree that the observed variations in quasar emissions are entirely, or very largely, due to processes intrinsic to the quasar. That being the case, since I can't fault Mike Hawkins' observations or analysis, I propose that his work stands as good, and so-far unchallenged, evidence that there is no time dilation between our observations of quasars in two redshift bins: 0.5 to 1.7 and 1.7 to 3.5. If one group of quasars were receding, on average, faster from Earth than the other, then we would observe time dilation by differing energy in their variability time-scale spectrums, unless that effect was compensated exactly by an equal and opposite change in the nature of quasars, in general, over time ("evolution"). Such a compensatory "evolution" seems extraordinarily unlikely, and is rejected by Mike Hawkins. So I think these observations constitute good evidence that low redshift quasars are not receding from us any faster than high redshift quasars. Assuming the Cosmological Principle is true, then I believe that these observations constitute good evidence that the average velocity of both groups of quasars with respect to Earth is zero - which is a direct contradiction of the Big Bang Theory. I won't comment on "the big bang has been disproved" since Occam's razor STILL favours it. Even if not everything in heaven and earth is understood, a lot of stuff DOES jibe well with the BBT, and any alternative theory has to explain that as well . . . It only takes one really good observation, if we decide it is valid, to disprove a theory. The fact that a theory gives convincing explanations - and predictions which were later verified - about a whole bunch of things is neither here nor there. Likewise, the fact that 99% of astronomers believe the theory to be valid, or that it is an "established fact", is not relevant. It is not necessary to replace a disproven theory with anything at all - it is good scientific progress to cast off the disproven theory and admit that we don't currently have a theory which explains as much as we previously thought we had explained. The Big Bang Theory depends entirely on an interpretation of observations that extra-galactic (or is it extra-galactic-cluster) objects are moving away from each other in all directions, though this is sometimes described as "expansion of space-time" rather than actual movement. In either case, for the BBT to be regarded as valid, this observed expansion of the positions of galaxies and quasars etc. must withstand all observational challenges. and the burden of proof is on the person who favours an explanation other than the BBT. I think that is what Mike Hawkin's research provides - a robust challenge to this theory of explosive expansion. While the BBT has built a vast array of theoretical constructs on the basis of this theory of expansion, as far as I know, there are only two reasons to believe in this expansion exists (not counting potential GRB light curve time-dilation, which I haven't studied closely). The first is the general correlation with redshift and apparent-distance - coupled with the failure so far to show in the laboratory any mechanism other than Doppler and gravitational redshift which could explain it. This should be regarded as a tentative finding, at best. CREIL and two Plasma Redshift theories attempt to provide a non-Doppler explanation for this redshift - see other threads on sci.astro.research and my site for references. (Put another way, the BBT is based on the notion that "photons" always traverse gas and plasma for billions of years without depositing any energy at all in this medium. A tired light explanation of "70 km per second per megaparsect" redshift only needs to account for about 1 part in 13 billion energy loss per year of travel in the IGM.) The second is the interpretation of supernovae light-curves - which is conventionally thought to show direct evidence of time-dilation of distant supernovae - an effect which most people agree could only result from the supernovae moving away from us (or appearing to as a result of the "expansion of space-time") at fractional relativistic speeds. However this has come under challenge recently, by: Supernovae Light Curves: An Argument for a New Distance Modulus http://arxiv.org/abs/astro-ph/0404207 Jerry Jensen 2004-04-06 I think the evidence for Big Bang style expansion is extraordinarily thin - it seems that the supernova time dilation interpretations rest primarily with a small number of observations and one or more papers published around 1996. Jerry Jensen challenges these supernovae interpretations on several fronts, including that the more distant SNe are not actually type 1a, and that some corrections applied to the data early in the processing chain are invalid, because these corrections assumed the existence of time dilation. The supernovae work relies on some very challenging "correction" procedures, based on assumptions about the statistical nature of type 1a SNe which are now being challenged by Jerry Jenson and other more mainstream researchers he cites. I think that Mike Hawkins' work depends on a much larger, more statistically robust, set of observations, and involves a far simpler set of "corrections", with few, if any, questionable assumptions about the nature of the distant objects or the mechanisms responsible for the variation we observe. I think the onus is on BBT supporters to establish one or more of the following, or to agree that Mike Hawkins' observations constitute a robust challenge to the Theory. 1 - Show that the observations are biased in some way which counteracts the time dilation predicted by the BBT. For instance by showing systematic errors in the selection process or data reduction - or by conducting, or analysing, entirely independent observations which provide evidence about the time dilation of distant quasars. 2 - Show that the "no time-dilation" interpretation of the observations is incorrect. 3 - Propose that quasars on average have changed their nature over time so their spectrum of variation frequencies, after time-dilation, leads to little or no observable change, as apparently found by Mike Hawkins. This could take the form of a theoretical argument and/or observations which support this view, including if no theoretical mechanism is proposed for it. It doesn't matter whether we have observations or theory to show how the redshift occurs without the BBT's explosive expansion - all that is needed for scientific progress to occur is to successfully challenge these observations and their interpretations, or to recognise that they stand as a robust challenge to the BBT. - Robin http://astroneu.com |
#4
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[[Mod. note -- I apologise for the long delay in posting this article.
The author originally antispam-mangled his domain, and the news server from which I now post doesn't accept such articles. Since I haven't been able to contact the author, I've decided not to delay the article any longer, so I've edited the antispam-mangling to mangle the username instead. Alas, this means that spam will now get to the author's local machine. -- jt]] In article , (Robin Whittle) writes: Furthermore, if the Universe really is expanding, then if microlensing was the cause of the observed variations, we would expect time dilation in the statistical properties of the microlensing of more distant objects since some or most of that microlensing would be caused by more distant objects which would be receding from us at higher velocities. Put another way, if microlensing is responsible for the variations, and we see no time correlation between its statistics and the redshift of the quasar, then, if the distance scales with redshift, we might have to conclude that the microlensing was always occurring close to Earth, which seems unacceptable for a number of reasons. One has to be careful here. The optical depth for lensing tends to peak around a redshift of 1, with just a weak dependence on the source redshift (and on the cosmological model). Also, what about the velocity: a combination of the velocities of source, lenses and observer. Depending on how the lenses interact with other matter, their velocity might increase or decrease with redshift. That being the case, since I can't fault Mike Hawkins' observations or analysis, I propose that his work stands as good, and so-far unchallenged, evidence that there is no time dilation between our observations of quasars in two redshift bins: 0.5 to 1.7 and 1.7 to 3.5. True, but if these observations are deemed to be important, then they should be confirmed by a completely independent observational programme. It only takes one really good observation, if we decide it is valid, to disprove a theory. Right. But, as Sagan said, extraordinary claims require extraordinary evidence. Such a result would at the very least have to be confirmed by completely independent observations. The fact that a theory gives convincing explanations - and predictions which were later verified - about a whole bunch of things is neither here nor there. It's actually quite important. Suppose one finds one observation which contradicts a given theory. If one can be sure that all observations are correct, then as you say this disproves the theory. In practice, however, systematic errors play a role---by definition, an unknown role. One has to way the probability of this observation being wrong against the "logical economy" of the theory. An alternative theory which accomodates this one special observation must also accomodate all the OTHER observations the first theory did---without resorting to ad-hoc mechanisms. Likewise, the fact that 99% of astronomers believe the theory to be valid, or that it is an "established fact", is not relevant. It is not necessary to replace a disproven theory with anything at all - it is good scientific progress to cast off the disproven theory and admit that we don't currently have a theory which explains as much as we previously thought we had explained. Again: in an ideal world, yes; in practice, one has to consider the fact that that observation might be wrong. Early microscopists reported observations of homunculi in sperm, and moral theologians of the time took this as supporting their view that masturbation is murder. But that observation was wrong (and more than one microscopist saw the homunculi.) I think that Mike Hawkins' work depends on a much larger, more statistically robust, set of observations, and involves a far simpler set of "corrections", with few, if any, questionable assumptions about the nature of the distant objects or the mechanisms responsible for the variation we observe. Even if his observations are better, one has to keep in mind that a) there are two quite independent supernova groups and b) the current wisdom is that we know less about QSOs than supernovae, so the interpretation is more difficult. |
#5
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[[Mod. note -- I apologise for the long delay in posting this article.
The author originally antispam-mangled his domain, and the news server from which I now post doesn't accept such articles. Since I haven't been able to contact the author, I've decided not to delay the article any longer, so I've edited the antispam-mangling to mangle the username instead. Alas, this means that spam will now get to the author's local machine. -- jt]] In article , (Robin Whittle) writes: Furthermore, if the Universe really is expanding, then if microlensing was the cause of the observed variations, we would expect time dilation in the statistical properties of the microlensing of more distant objects since some or most of that microlensing would be caused by more distant objects which would be receding from us at higher velocities. Put another way, if microlensing is responsible for the variations, and we see no time correlation between its statistics and the redshift of the quasar, then, if the distance scales with redshift, we might have to conclude that the microlensing was always occurring close to Earth, which seems unacceptable for a number of reasons. One has to be careful here. The optical depth for lensing tends to peak around a redshift of 1, with just a weak dependence on the source redshift (and on the cosmological model). Also, what about the velocity: a combination of the velocities of source, lenses and observer. Depending on how the lenses interact with other matter, their velocity might increase or decrease with redshift. That being the case, since I can't fault Mike Hawkins' observations or analysis, I propose that his work stands as good, and so-far unchallenged, evidence that there is no time dilation between our observations of quasars in two redshift bins: 0.5 to 1.7 and 1.7 to 3.5. True, but if these observations are deemed to be important, then they should be confirmed by a completely independent observational programme. It only takes one really good observation, if we decide it is valid, to disprove a theory. Right. But, as Sagan said, extraordinary claims require extraordinary evidence. Such a result would at the very least have to be confirmed by completely independent observations. The fact that a theory gives convincing explanations - and predictions which were later verified - about a whole bunch of things is neither here nor there. It's actually quite important. Suppose one finds one observation which contradicts a given theory. If one can be sure that all observations are correct, then as you say this disproves the theory. In practice, however, systematic errors play a role---by definition, an unknown role. One has to way the probability of this observation being wrong against the "logical economy" of the theory. An alternative theory which accomodates this one special observation must also accomodate all the OTHER observations the first theory did---without resorting to ad-hoc mechanisms. Likewise, the fact that 99% of astronomers believe the theory to be valid, or that it is an "established fact", is not relevant. It is not necessary to replace a disproven theory with anything at all - it is good scientific progress to cast off the disproven theory and admit that we don't currently have a theory which explains as much as we previously thought we had explained. Again: in an ideal world, yes; in practice, one has to consider the fact that that observation might be wrong. Early microscopists reported observations of homunculi in sperm, and moral theologians of the time took this as supporting their view that masturbation is murder. But that observation was wrong (and more than one microscopist saw the homunculi.) I think that Mike Hawkins' work depends on a much larger, more statistically robust, set of observations, and involves a far simpler set of "corrections", with few, if any, questionable assumptions about the nature of the distant objects or the mechanisms responsible for the variation we observe. Even if his observations are better, one has to keep in mind that a) there are two quite independent supernova groups and b) the current wisdom is that we know less about QSOs than supernovae, so the interpretation is more difficult. |
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