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#201
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Good News for Big Bang theory
In article , "Chalky"
writes: No. You can equate observable z to some sort of velocity ONLY at low redshift This is incorrect. See below for further elucidation, and references. (and even then, it's nothing deep, more "all things are linear to first order). I would agree that Hubble's Law is a first order approximation, if for no better reason than that it relates D to V to first order, with no higher order terms present. However, that point aside, what you say is probably only necessarily true if you wish to interpret reality exclusively within the context of GR, AND interpret GR exclusively within the context of the mathematical apparatus of the field equation that Einstein published during World War 1. If you interpret GR more generally (and, I would thus argue, more rigorously), to mean ANY logically and mathematically viable solution of the relativistic axioms, which is consistent with empirical observation, then it seems to me that your argument is no longer necessarily valid. Velocity (change in proper distance with time) being proportional to proper distance follows directly from homogeneous and isotropic expansion. No physics. Neither of these quantities is observable. At low redshift, where all distances are approximately the same, this holds approximately for all distances. Proof: if z tells you the velocity, is it independent of the cosmological parameters? Yes, at least relative to us. So what is your proof? Let me rephrase that: If z tells you the velocity, is the VELOCITY independent of the cosmological parameters? (The fact that z is, is obvious, since it is an observed quantity.) 1) Hubble derived the Law from observational data, not theory. Yes, but, as all evolutionary biologists know, origin and current function are two different things. Also, Hubble's data were EXTREMELY low redshift by modern standards, so he could get away with this. Sure. But I am actually talking about something more sophisticated now. Consequently, in the context of 2007, your argument can actually be used to support my thesis. 4) It is thus clear to me, in the context of the above, that by distance, Hubble estimated and meant light travel distance not 'proper' distance. Actually, he meant luminosity distance, but again the redshifts were so low it didn't matter. Although Hubble may well have used luminosity distance to arrive at his conclusions, I seriously doubt that he could have been sloppy enough, as a scientist, to equate luminosity distance with real distance, in formulating his general law. Even if Hubble knew nothing about SR or GR, he should still have known, even in the context of a Euclidean Universe, that luminosity distance is, by definition, (1 + z) times real distance, just from the 19th century Doppler shift formula, and related elementary (degree course) matriculation level physics. Actually, his redshifts were so low that it didn't matter. Do the maths. |
#202
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Good News for Big Bang theory
Although Hubble may well have used luminosity distance to arrive at his
conclusions, I seriously doubt that he could have been sloppy enough, as a scientist, to equate luminosity distance with real distance, in formulating his general law. Even if Hubble knew nothing about SR or GR, he should still have known, even in the context of a Euclidean Universe, that luminosity distance is, by definition, (1 + z) times real distance, just from the 19th century Doppler shift formula, and related elementary (degree course) matriculation level physics. Why don't you read Hubble's own paper for yourself? For example, you can find a copy of one of the first papers discussing the distance-velocity relationship at http://spiff.rit.edu/classes/phys240.../hub_1929.html In this paper, he does not distinguish between the several types of "distance" which have been discussed in this thread. I suspect that he didn't bother because the data would not permit one to make any distinction at that time. |
#203
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Good News for Big Bang theory
Phillip Helbig---remove CLOTHES to reply wrote:
In article , "Chalky" writes: No. You can equate observable z to some sort of velocity ONLY at low redshift This is incorrect. See below for further elucidation, and references. (and even then, it's nothing deep, more "all things are linear to first order). I would agree that Hubble's Law is a first order approximation, if for no better reason than that it relates D to V to first order, with no higher order terms present. However, that point aside, what you say is probably only necessarily true if you wish to interpret reality exclusively within the context of GR, AND interpret GR exclusively within the context of the mathematical apparatus of the field equation that Einstein published during World War 1. If you interpret GR more generally (and, I would thus argue, more rigorously), to mean ANY logically and mathematically viable solution of the relativistic axioms, which is consistent with empirical observation, then it seems to me that your argument is no longer necessarily valid. Velocity (change in proper distance with time) being proportional to proper distance follows directly from homogeneous and isotropic expansion. No physics. Neither of these quantities is observable. That is half of the reason why I no longer use such metaphysical concepts myself. The other half of the reason is that such de facto unobservable abstractions tempt one back down the slippery slope towards formulating a field equation which collapses repeatedly into paradoxical singularities, just like Einstein's preliminary effort was soon found to do. I now prefer to understand observable reality in terms of things which are themselves observable, such as real measuring devices, and real events. This would seem to have the advantage of being both logical, and empirically scientific. Proof: if z tells you the velocity, is it independent of the cosmological parameters? Yes, at least relative to us. So what is your proof? Let me rephrase that: If z tells you the velocity, is the VELOCITY independent of the cosmological parameters? YES. That velocity, for at least the lion's share of the visible universe, IS independent of the cosmological parameters that are required to give EFE any semblance of credibility, on that scale. This should come as no surprise to anybody. The effects of known matter had to be boosted by a factor of about 7 via the introduction of the speculative concept of dark matter, just to explain galactic rotation curves in the context of EFE. This, along with the contribution of extragalactic dark matter, has now been dwarfed by the still more exotic speculation of dark energy, just to explain the observational evidence of accelerating expansion. An empirical scientist (or cynic), could thus now claim with perfect justifiication that the current EFE cosmological model is now driven by ~ 97% speculative metaphysics, and only ~ 3% the locally verified physics of known matter. Einstein exhorted us to think locally. It looks to me like the devotees of the concordance model decided not to listen. 1) Hubble derived the Law from observational data, not theory. Yes, but, as all evolutionary biologists know, origin and current function are two different things. Also, Hubble's data were EXTREMELY low redshift by modern standards, so he could get away with this. Sure. But I am actually talking about something more sophisticated now. Consequently, in the context of 2007, your argument can actually be used to support my thesis. 4) It is thus clear to me, in the context of the above, that by distance, Hubble estimated and meant light travel distance not 'proper' distance. Actually, he meant luminosity distance, but again the redshifts were so low it didn't matter. Although Hubble may well have used luminosity distance to arrive at his conclusions, I seriously doubt that he could have been sloppy enough, as a scientist, to equate luminosity distance with real distance, in formulating his general law. Even if Hubble knew nothing about SR or GR, he should still have known, even in the context of a Euclidean Universe, that luminosity distance is, by definition, (1 + z) times real distance, just from the 19th century Doppler shift formula, and related elementary (degree course) matriculation level physics. Actually, his redshifts were so low that it didn't matter. Do the maths. I agree that it didn't matter for the arithmetic then. It doesn't even matter for the corresponding arithmetic now, since magnitude deviations from what an inertial model would predict, are interpreted in terms of ratios of predicted distance (or more accurately, flux) at the same z. However, it does matter for understanding what is physically going on out there. Hubble should have had an adequate grasp of such basic natural philosophy to appreciate the difference between luminosity distance and physical distance. Consequently, if he had actually INTERPRETED the data to mean that recession velocity was proportional to luminosity distance, he would have said so, instead of defining the law as he did. The same is equally true now for "Chalky's Law" (http://www.1stlight.org/z8.asp#CL). Chalky |
#204
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Good News for Big Bang theory
Thus spake Oh No
Thus spake Chalky Phillip Helbig---remove CLOTHES to reply wrote: This law, now christened 'Chalky's Law' by John, was formally defined, copyright protected, and published, at http://www.1stlight.org/z8.asp#CL , at the precise start of 2007 (Greenwich Mean Time). I don't see any curve fitting on your site at all. For a start you haven't even plotted a curve, let alone shown a chi^2 test, so you can't claim a better fit. Fortunately I happen to have a fitting program into which I can very easily plug Chalky's law. Rather amusingly, far from being a fit to the data, Chalky's law doesn't even lie on the graph. Whereas, for 225 points of the combined Riess04 and Astier Data sets the standard model produces a best fit chi^2 value of 212.5 and the teleconnection produces a best fit of 210.8 (both excellent fits, btw), Chalky's law gives a best fit of chi^2 = 4,363,667. I wondered if I had been a little unfair on Chalky. He might have been expected to do a bit better than that. Then I noticed that there was an error in the units of Chalky's law. In fact if you multiply by the speed of light, and also optimise for errors in Hubble's constant, you get chi^2 = 209.5. Actually quite good for a naive law even if it does have no physics justification. In fact it is quite interesting to see how good a fit can be obtained by a simple quadratic law, since it gives you an idea as to how close the physical models are to an optimum fit. I know chalky is more interested in the Riess06 data, and I needed to run the tests anyway. Not withstanding the possible calibration problems which still exist in the cleaned up data (particularly the HZSST data set), I find for the Gold06 set with 182 SN Standard Teleconnection Chalky Chi^2 158.75 156.67 158.38 Omega 0.34 2.01 n/a So I win this time, but its a close thing. Chalky still beats the standard model. I'm struck by how close to Omega=2 the teleconnection comes out. I don't know any reason for that. For the silver set, which contains SN for which the spectral determination is less clear, but which contains 285 points Standard Teleconnection Chalky Chi^2 393.49 387.55 383.05 Omega 0.32 1.985 n/a Chalky wins again, but this is the data which he designed his law to fit. A big warning is present in these figures. The cleaned up 06 data gave a chi^2 value a bit less than the number of data points. That is what one expects for valid data if the error margins are slightly generous, as they should be. But here the value of chi^2 is substantially above the number of data points. In fact, so much higher that it goes right off chi^2 table. http://people.msoe.edu/~jorgense/ChiSquare_Table.pdf#search='Percentage% 20po So the only thing we say on the basis of the silver set is that it contains invalid data with rather more than 99.5% certainty. Regards -- Charles Francis substitute charles for NotI to email |
#205
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Good News for Big Bang theory
Thus spake Oh No
I know chalky is more interested in the Riess06 data, and I needed to run the tests anyway. Not withstanding the possible calibration problems which still exist in the cleaned up data (particularly the HZSST data set), I find for the Gold06 set with 182 SN Standard Teleconnection Chalky Chi^2 158.75 156.67 158.38 Omega 0.34 2.01 n/a So I win this time, but its a close thing. Chalky still beats the standard model. I'm struck by how close to Omega=2 the teleconnection comes out. I don't know any reason for that. For the silver set, which contains SN for which the spectral determination is less clear, but which contains 285 points Standard Teleconnection Chalky Chi^2 393.49 387.55 383.05 Omega 0.32 1.985 n/a Chalky wins again, but this is the data which he designed his law to fit. It is usual in problems of this sort to remove outliers which can reasonably be suspected of being false data. This data is particularly suspect, since it is potentially contaminated from another type of supernova. The larger chi^2 values which have most influence on the fit are also the most likely to be false data. In addition all the errors as given include a constant error due to peculiar velocities. I felt it justifiable to exclude points outside of a 99% confidence limit. There should normally be less three points in a sample the size of the silver set, but there are eleven silver (one had chi^240!) and three gold. Since the bulk of those will not be type 1A supernova, it is reasonable think that others in both sets may be also not type 1A. This leaves a sample of 270 points for the silver set, for which spectral determination is less clear. Standard Teleconnection Chalky Chi^2 223.94 219.31 218.73 Omega 0.327 1.997 n/a Chalky still wins, but only just. The influence of dodgy data starts to become clear though as the margins is much reduced. When the three outliers are removed from the gold set the result, for 179df is Standard Teleconnection Chalky Chi^2 139.12 136.54 139.27 Omega 0.342 2.05 n/a The standard model now pips Chalky to second place, while the teleconnection increases its lead in the gold set, which is the highest quality data. Interesting that the gradually increasing prediction for Omega with better quality data is starting to push the standard model toward a timescale problem. With Omega=0.34 the age of the universe comes out at 12.8 Gyears, 0.8 Gyrs less than the best age of the Milky way from beryllium abundances. I think the margin is about 1Gyr, so not quite a timescale problem yet. I must emphasise that it is not possible to draw any firm conclusion from these results. They are much too close to call. In terms of odds this represents something like 10:9 in favour of the teleconnection, and it should be pretty obvious that the result is fairly sensitive to variations in the sample. Nonetheless I find it encouraging that every way I split the data (I have tried other splits based on the teams which collected data), I get a very similar picture, that the teleconnection is marginally preferred to the standard model. Chalky's law behaves as one would expect of a law constructed to fit data - the optimum law for any given data set is always going to produce a better fit than the true law, but when applied to a different data set, that is no longer the case. Regards -- Charles Francis substitute charles for NotI to email Regards -- Charles Francis substitute charles for NotI to email |
#206
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Good News for Big Bang theory
Oh No wrote:
Thus spake Oh No Thus spake Chalky Phillip Helbig---remove CLOTHES to reply wrote: This law, now christened 'Chalky's Law' by John, was formally defined, copyright protected, and published, at http://www.1stlight.org/z8.asp#CL , at the precise start of 2007 (Greenwich Mean Time). I don't see any curve fitting on your site at all. For a start you haven't even plotted a curve, let alone shown a chi^2 test, so you can't claim a better fit. Fortunately I happen to have a fitting program into which I can very easily plug Chalky's law. Rather amusingly, far from being a fit to the data, Chalky's law doesn't even lie on the graph. Whereas, for 225 points of the combined Riess04 and Astier Data sets the standard model produces a best fit chi^2 value of 212.5 and the teleconnection produces a best fit of 210.8 (both excellent fits, btw), Chalky's law gives a best fit of chi^2 = 4,363,667. I wondered if I had been a little unfair on Chalky. He might have been expected to do a bit better than that. Then I noticed that there was an error in the units of Chalky's law. In fact if you multiply by the speed of light, Poor Chalky. He got jibed for leaving the c in his formulae, and then gets in hot water again, for then using natural units, as previously advised, when publishing his Law. and also optimise for errors in Hubble's constant, you get chi^2 = 209.5. Actually quite good for a naive law even if it does have no physics justification. Actually, its physics justification was its whole raison d'etre, which is why we wanted to get this particular prediction published asap, in 2007 (without waiting for the pretty graphs). In fact it is quite interesting to see how good a fit can be obtained by a simple quadratic law, since it gives you an idea as to how close the physical models are to an optimum fit. I know chalky is more interested in the Riess06 data, and I needed to run the tests anyway. Not withstanding the possible calibration problems which still exist in the cleaned up data (particularly the HZSST data set), I find for the Gold06 set with 182 SN Standard Teleconnection Chalky Chi^2 158.75 156.67 158.38 Omega 0.34 2.01 n/a So I win this time, but its a close thing. Chalky still beats the standard model. I'm struck by how close to Omega=2 the teleconnection comes out. I don't know any reason for that. For the silver set, which contains SN for which the spectral determination is less clear, but which contains 285 points Standard Teleconnection Chalky Chi^2 393.49 387.55 383.05 Omega 0.32 1.985 n/a Chalky wins again, Most gracious of you. You actually won on the first throw, but I guess Chalky did win overall, since he didn't change Omega, which is irrelevant, in context. but this is the data which he designed his law to fit. Not so. He derived his law from theory. We had the devils own job reinterpreting the original prediction in a way that could be seen as consistent with the way the data has been presented by astronomers (i.e. in the context of EFE). When Chalky got it, he then tested the Law against the full 290 supernova data set that had been already (helpfully) been statistically analysed by Ned Wright. Most of these were gold. (Ned's reference here is: http://braeburn.pha.jhu.edu/~ariess/R06/sn_sample ) A big warning is present in these figures. The cleaned up 06 data gave a chi^2 value a bit less than the number of data points. That is what one expects for valid data if the error margins are slightly generous, as they should be. But here the value of chi^2 is substantially above the number of data points. In fact, so much higher that it goes right off chi^2 table. http://people.msoe.edu/~jorgense/ChiSquare_Table.pdf#search='Percentage% 20po So the only thing we say on the basis of the silver set is that it contains invalid data with rather more than 99.5% certainty. Yes, but the importance of that invalid data (which may be just one Sn) gets watered down more, the more samples one includes in the set. On this argument, including the silver set as Ned and Chalky did, is probably still better than excluding it. Actually though, the numbers don't add up. I counted 290 Snae altogether in Ned's set, which, quoting from ref. "To match primary fits in Riess et al. 2007 (astro-ph/0611572) Please cite Riess et al. 2007 (astro-ph/0611572). 1) Discard all SNe Ia with z0.0233 2) Discard all SNe with quality='Silver' This should leave 182 SNe Ia." That looks like 100 silvers to me, in their analysis.. (Your revised response was most gracious and welcome, and I am sure that Chalky will agree.) Perhaps you could now also try throwing the whole lot in the number cruncher together, and see what you come up with. Regards John |
#207
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Good News for Big Bang theory
Oh No wrote:
Thus spake Oh No Thus spake Chalky This law, now christened 'Chalky's Law' by John, was formally defined, copyright protected, and published, at http://www.1stlight.org/z8.asp#CL , at the precise start of 2007 (Greenwich Mean Time). for 225 points of the combined Riess04 and Astier Data sets the standard model produces a best fit chi^2 value of 212.5 and the teleconnection produces a best fit of 210.8 (both excellent fits, btw), Chalky's law optimise for errors in Hubble's constant, you get chi^2 = 209.5. And what is that optimised value for Ho? (so we can check that prediction too) Let us take your above 225 points as set A, your next 182 point (gold set) as set B and your final 285 point (silver set) as set C. You get: Model: Chalky's Law EFE Teleconnection No. of Data Points chi^2 A: 209.5 212.5 210.8 225 chi^2 B: 158.38 158.75 156.67 182 chi^2 C: 383.05 393.49 387.55 285 That is three tests out of three which confirm that Chalky's Law is more accurate than EFE. Ditto for your teleconnection model. Now let us get more ambitious. What do you find for: (D) the 290 point (mostly gold) set used by Ned Wright and adopted by Chalky? (http://braeburn.pha.jhu.edu/~ariess/R06/sn_sample) (E) the entire ~ 570? point (complete) set using the whole ~204? gold, 285 silver, and ~ 81? Astier supernovae, without preference or prejudice? Given the models are so close thus far, any peculiar motion at low z, or otherwise duff data elsewhere, should affect all 3 runners similarly. Regards, John |
#208
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Good News for Big Bang theory
Thus spake "John (Liberty) Bell"
Oh No wrote: Thus spake Oh No Thus spake Chalky Phillip Helbig---remove CLOTHES to reply wrote: This law, now christened 'Chalky's Law' by John, was formally defined, copyright protected, and published, at http://www.1stlight.org/z8.asp#CL , at the precise start of 2007 (Greenwich Mean Time). I don't see any curve fitting on your site at all. For a start you haven't even plotted a curve, let alone shown a chi^2 test, so you can't claim a better fit. Fortunately I happen to have a fitting program into which I can very easily plug Chalky's law. Rather amusingly, far from being a fit to the data, Chalky's law doesn't even lie on the graph. Whereas, for 225 points of the combined Riess04 and Astier Data sets the standard model produces a best fit chi^2 value of 212.5 and the teleconnection produces a best fit of 210.8 (both excellent fits, btw), Chalky's law gives a best fit of chi^2 = 4,363,667. I wondered if I had been a little unfair on Chalky. He might have been expected to do a bit better than that. Then I noticed that there was an error in the units of Chalky's law. In fact if you multiply by the speed of light, Poor Chalky. He got jibed for leaving the c in his formulae, and then gets in hot water again, for then using natural units, as previously advised, when publishing his Law. It can be important simply to state what you mean. But I do feel a bit guilty and have to apologise. It should have occurred to me to think of this sooner. As it was, I posted too quickly. Sorry about that, Chalky. and also optimise for errors in Hubble's constant, you get chi^2 = 209.5. Actually quite good for a naive law even if it does have no physics justification. Actually, its physics justification was its whole raison d'etre, which is why we wanted to get this particular prediction published asap, in 2007 (without waiting for the pretty graphs). I may be able to email you some before too long. In fact it is quite interesting to see how good a fit can be obtained by a simple quadratic law, since it gives you an idea as to how close the physical models are to an optimum fit. I know chalky is more interested in the Riess06 data, and I needed to run the tests anyway. Not withstanding the possible calibration problems which still exist in the cleaned up data (particularly the HZSST data set), I find for the Gold06 set with 182 SN Standard Teleconnection Chalky Chi^2 158.75 156.67 158.38 Omega 0.34 2.01 n/a So I win this time, but its a close thing. Chalky still beats the standard model. I'm struck by how close to Omega=2 the teleconnection comes out. I don't know any reason for that. For the silver set, which contains SN for which the spectral determination is less clear, but which contains 285 points Standard Teleconnection Chalky Chi^2 393.49 387.55 383.05 Omega 0.32 1.985 n/a Chalky wins again, Most gracious of you. You actually won on the first throw, but I guess Chalky did win overall, since he didn't change Omega, which is irrelevant, in context. There I cannot agree with you. It's true that chalky does not have free parameters, but the rate of change of expansion is determined by gravitational force. The more dense matter is in the universe the more rapidly Hubble expansion slows down, and that is what is being determined in these tests. This would be true even in a Newtonian theory of gravity. but this is the data which he designed his law to fit. Not so. He derived his law from theory. We had the devils own job reinterpreting the original prediction in a way that could be seen as consistent with the way the data has been presented by astronomers (i.e. in the context of EFE). When Chalky got it, he then tested the Law against the full 290 supernova data set that had been already (helpfully) been statistically analysed by Ned Wright. Most of these were gold. (Ned's reference here is: http://braeburn.pha.jhu.edu/~ariess/R06/sn_sample ) That is also the data I used. A big warning is present in these figures. The cleaned up 06 data gave a chi^2 value a bit less than the number of data points. That is what one expects for valid data if the error margins are slightly generous, as they should be. But here the value of chi^2 is substantially above the number of data points. In fact, so much higher that it goes right off chi^2 table. http://people.msoe.edu/~jorgense/ChiSquare_Table.pdf#search='Percentage% 20po So the only thing we say on the basis of the silver set is that it contains invalid data with rather more than 99.5% certainty. Yes, but the importance of that invalid data (which may be just one Sn) gets watered down more, the more samples one includes in the set. On this argument, including the silver set as Ned and Chalky did, is probably still better than excluding it. I have posted a follow-up on the results of removing the most questionable points. Actually though, the numbers don't add up. I counted 290 Snae altogether in Ned's set, which, quoting from ref. Actually we have both made a mistake. The set is from Riess's site (note URL includes ariess). I loaded it into my text editor and have 292 lines of data which I pasted into my application. I failed to check that my application then counted these lines correctly, and actually had a bug which I have now found. Thanks for that. The bug only affected the count of the number of data points, not the values of chi^2 or the predicted values of Omega. "To match primary fits in Riess et al. 2007 (astro-ph/0611572) Please cite Riess et al. 2007 (astro-ph/0611572). 1) Discard all SNe Ia with z0.0233 2) Discard all SNe with quality='Silver' This should leave 182 SNe Ia." That looks like 100 silvers to me, in their analysis.. In fact I count (with the corrected program) 206 gold points and 86 silver points. I used all of these for the full analysis (like Ned I am not sure that it is really right to drop points z0.023. I can't see that it will do much harm either. Maybe it is safer to drop them. For the gold set analysis I pasted the data from arXiv:astro-ph/0612653v1 which has already been restricted to 182 points of gold set data with z=0.023 In respect of that paper, btw, I also tried removing the 6 points of HZSST data which they mark as questionable, and also, I tried removing all the HZSST data on the ground that if that much of it is questionable then it all is. I did not feel this made any great difference to the results and did not think that I would share their conclusions, so in the end I decided to include all the HZSST data. I confess, my analysis was not as thorough as theirs. Had I thought it was going to support their position I would have continued it, but the problems appeared to me to be to do with individual data in different sets, not with any particular set taken as a whole. The HZSST data does have a wider spread than other sets, but it also has wider error margins for individual points and so has less affect on a chi^2 test than better sets. Their analysis was based on predictions for changes in Lambda, and I personally doubt the validity of that enquiry. If either the teleconnection or Chalky's law turns out to be correct, it would show up in an analysis like that as apparently incompatible data sets. That said, there is always a risk of incompatibility between different sets when using unhomogeneous data. If two instruments are not calibrated correctly together then we will get a much higher chi^2 than we should, and also spurious predictions for Omega. Nonetheless, Riess has done a lot of work to make sure the data is correctly calibrated, and I see no particular reason as yet to think that work should be rejected. (Your revised response was most gracious and welcome, and I am sure that Chalky will agree.) Perhaps you could now also try throwing the whole lot in the number cruncher together, and see what you come up with. More on that in answer to your next post. Regards -- Charles Francis substitute charles for NotI to email |
#209
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Good News for Big Bang theory
Thus spake "John (Liberty) Bell"
Oh No wrote: Thus spake Oh No Thus spake Chalky This law, now christened 'Chalky's Law' by John, was formally defined, copyright protected, and published, at http://www.1stlight.org/z8.asp#CL , at the precise start of 2007 (Greenwich Mean Time). for 225 points of the combined Riess04 and Astier Data sets the standard model produces a best fit chi^2 value of 212.5 and the teleconnection produces a best fit of 210.8 (both excellent fits, btw), Chalky's law optimise for errors in Hubble's constant, you get chi^2 = 209.5. And what is that optimised value for Ho? (so we can check that prediction too) It's not possible to calculate H0 from this data on its own. A value of H0 is already built into the magnitude figures. This cancels out of the fits. This may be slightly different for Chalky's law. One of the fitting parameters is the absolute magnitude of a type 1A supernova. Varying that is equivalent to varying Hubble's constant. To be fair on all three models I allowed that to vary in all cases. It comes out that the absolute magnitude is almost identical for the teleconnection and the standard model, but is slightly less for Chalky's law - by just under 0.08 mag. It is possible that there is other info on nearby supernovae that puts this difference outside margins of error, but that takes me beyond my current level of knowledge. If constrained to use a value closer to that of the standard model, Chalky's law could get pushed out of contention. Let us take your above 225 points as set A, your next 182 point (gold set) as set B and your final 285 point (silver set) as set C. You get: Model: Chalky's Law EFE Teleconnection No. of Data Points chi^2 A: 209.5 212.5 210.8 225 chi^2 B: 158.38 158.75 156.67 182 chi^2 C: 383.05 393.49 387.55 285 That is three tests out of three which confirm that Chalky's Law is more accurate than EFE. Ditto for your teleconnection model. Incidentally the teleconnection does use the EFE, and also Friedmann's equation. It only differs from the standard model in predictions concerning cosmological redshift. The impact of this difference is quite dramatic, however. Instead of an infinite universe with accelerating expansion and cold dark matter, it comes up with an "Einstein preferred" closed, finite universe with no cosmological constant and no cold dark matter. Now let us get more ambitious. What do you find for: (D) the 290 point (mostly gold) set used by Ned Wright and adopted by Chalky? (http://braeburn.pha.jhu.edu/~ariess/R06/sn_sample) As explained in previous post, I was actually using 292 points from this set, which I counted incorrectly. (E) the entire ~ 570? point (complete) set using the whole ~204? gold, 285 silver, and ~ 81? Astier supernovae, without preference or prejudice? The complete set is actually the 292 points we have used. This includes the original Reiss04 gold and silver sets, the entire Astier set, plus, 26 (iirc) new HST points. The 225 points I used before consists of the original Reiss04 gold set, less (iirc) 3 outliers together with the Astier set less two outliers also discarded by Astier. These outliers are now included as silver points (i.e. don't fit Riess's spectroscopy criteria for type 1A supernovae), as are a number of other Astier points. Many of the points in Riess's original set have been recalibrated for the new 06 set, and he has also calibrated the Astier data to the other sets, which I had done separately. He has made other small adjustments to the Astier data which I don't know about. He is much more expert on this data and how it is collected and preprocessed than I am. I think we have to take the new gold and silver sets as being the most complete and accurate data available so far. Neither set is perfect. Just by looking at the data statistically, it seems to me the bulk of silver points are type 1A. OTOH quite a few are not. Certainly, by applying his spectroscopy condition Riess removes almost all the points which lie away from the curves (all three curves), and that is a good indication that his criterion works. He removes some points also which are close to the curves. These may or may not be type 1A. I suspect quite a few of them are type 1A, but the quality of observation was not good enough to be sure. Including wrong data in a chi^2 test in general has much more affect than discounting right data, so it seems to me that it is better to go with the gold set than the silver one. I've been reviewing what I did yesterday and it still seems to me that the Gold set is not perfect. I think there is an underlying distribution which is tighter than first appears to be the case, but it is difficult to see how to establish this. It may be impossible to establish in any convincing way after allowing for random factors. I still think it is right to take out the one point beyond 3sigma for the distribution (99.9%) but I can't really justify taking out the two others beyond 99%. One might expect two points beyond that level anyway. Also, when I looked more carefully I realised that removing one of those points was unfair on Chalky, because it wasn't beyond 99% from his curve. The result, for 181 data points, slightly reduces the teleconnection's lead and moves Chalky firmly back into second place. Standard Teleconnection Chalky Chi^2 150.75 148.34 149.78 Omega 0.334 1.997 n/a Given the models are so close thus far, any peculiar motion at low z, or otherwise duff data elsewhere, should affect all 3 runners similarly. All three curves are very close, and a lot of very accurate data will be needed to distinguish them. With around 180 points you really want a difference of about 20 in the value of chi^2 to say anything approaching conclusive. Potentially, with a lot of data, Chalky's law can be distinguished from the other two in the range z0.4. Unfortunately they don't seem to be looking much in that range at the moment. We could do with more recent, (more accurate), LR supernovae. The teleconnection and the standard laws are almost indistinguishable right up to z=1. It really needs a lot of data above z=1.5 to have a chance of distinguishing it. Above z=1, Chalky's law lies between the teleconnection and the standard model, perhaps a little closer to the teleconnection up to about z=2. The data we need will come. SNAP is being designed to find thousands of supernovae at up to about z=2. We just have to wait - about ten years I think. Regards -- Charles Francis substitute charles for NotI to email |
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Good News for Big Bang theory
Potentially, with a lot of data, Chalky's law can be distinguished from
the other two in the range z0.4. Unfortunately they don't seem to be looking much in that range at the moment. We could do with more recent, (more accurate), LR supernovae. The SDSS Supernova Search team has found quite a few low-redshift SNe over the past two years. Let me do a hasty estimate ... of order 140 Type Ia during the 2005 season and of order 200 Type Ia during the 2006 season. Only a fraction of these events has really frequent followup, which is necessary to determine the peak magnitudes, but it's better than chopped liver :-) You can find more information at http://sdssdp47.fnal.gov/sdsssn/sdsssn.html but I suspect you won't find a nice table with observed peak magnitudes; the team is still working on the data reduction and analysis. Several team members are presenting posters at next week's AAS meeting, so watch your local news sources for tidbits. You could also look at the AAS meeting website, which will make some presentations available after they have been made, I think. See special session 32, "The SDSS Supernova Survey": http://www.abstractsonline.com/viewer/viewSession.asp The teleconnection and the standard laws are almost indistinguishable right up to z=1. It really needs a lot of data above z=1.5 to have a chance of distinguishing it. Above z=1, Chalky's law lies between the teleconnection and the standard model, perhaps a little closer to the teleconnection up to about z=2. The data we need will come. SNAP is being designed to find thousands of supernovae at up to about z=2. We just have to wait - about ten years I think. Hmmmm ... the usual SNAP simulations go up to z=1.7 or so, not z=2.0, but that's basically the plan. I may be a bit pessimistic, but ten years might take us to the launch, not the final results being published :-( Michael Richmond |
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