For the sake of us in the "peanut gallery" trying to follow this, would you folks clarify your numbers please.

Zahl : Does +7%+/-8% mean -1% to +15% or something else? And what is the base number you apply this to, 70 or 72 or something else?

Jerry : How did you get 69 and 85?

Thanks for any clarification.

TomT

The HKP (Hubble Key Project) Used the Distance to the Cephieds in the Small Magellenic Cloud (SMC) to create a basic ruler. Change the distance to the cloud and the ruler length changes proportionately.

The Distance Modulus to the SMC used by HKP was 18.5+/-0.1. The 'new' modulus is 18.34+/-0.06. It is a little difficult to extrapolate this value to a new Hubble Value (Changing the distance to the SMC changes both the slope and offset of the Hubble flow), but Zahl's 7% figure is probably more correct than my eyeballed 9% estimate.

10% is the total, formal error estimated in HKP from all sources. If the new distance to the SMC is more certain, the formal error should be less as well. HKP states that the uncertainty in the distance to the SMC is 5%; and the total quadratic error from all sources results in the 10% figure. I don't know where Zahl's 8% figure comes from, but it is a reasonable number, if the error estimated in the distance to the SMC has been reduced, which it has (From 0.1 to 0.06).


77+/- 8%, which is ~71 to ~83; or if the formal error is left at 10%, ~69 to ~85 m/s/kps.

__________________
jwj

It's a big universe out there...is it really unwinding, really burning out?

Here is an extract from the Summary (section 11) of the Freedman et al. HKP paper:Although I'm not certain, it seems the "±" numbers are 1 sigma (see section 3.4). For more details, re Cepheid distances, "further discussion of errors can be found in Madore et al. 1999; Ferrarese et al. 2000b".

So, the "simply combine the total errors in quadrature" value of H₀, from the Freedman et al. HKP paper is [64, 80] (1 sigma), [56, 88] (2 sigma), [48, 96] (3 sigma).

However, as I think has been made very clear in this thread, reducing the results of many projects which set out to determe H₀ to only "H₀ = 72 ± 8 km s⁻¹Mpc⁻¹" can be misleading.

The Freedman et al. HKP paper, in Section 9, briefly discusses two independent methods of determining H₀ - the SZ effect and time delays from gravitational lenses. These two methods are, potentially, hugely valuable, if only because they are free of all the systematics of all the other methods discussed (in Freedman et al.) Unfortunately, each has its own systematic errors to wrestle with. To date, the good news is that the results are consistent with "H₀ = 72 ± 8 km s⁻¹Mpc⁻¹". For example:

Indeed. When self-proclaimed "researchers" make obviously incorrect assertions it is a prudent thing to expose that nonsense. From my posting history you will find [url=http://www.bautforum.com/astronomy/57127-local-features-wmap-map-3.html]this[/url thread where a preprint by Gerrit Verschuur was discussed. He argued that the small-scale structure in the "WMAP data" (later changed to "WMAP ILC data" in the refereed v2 preprint) and HI are related. I refuted some of the nonsense in that preprint while some misguided individuals such as yourself claimed that I had misunderstood Verschuur's argument. Later I summarized the numerous changes in v2 of the preprint, showing that the content I had criticized had been duly removed.

What a pathetic straw man. I did not dispute the fact that they used 6 galaxies in 6 clusters for the SBF result, I disputed your crazy claim that this makes their SBF result "irrelevant".

Note how dgruss23 does not quote the papers. Nonsense is still nonsense even if it is written in red. Let's see what the HKP paper (http://arxiv.org/abs/astro-ph/0012376) really says:

"As part of the Key Project, Ferrarese et al. (2000a) applied an HST Cepheid calibration to the 4 Lauer et al. (1998) SBF galaxies, and derived H0 = 69 ± 4r ± 6s km/s/Mpc. The results are unchanged if all 6 clusters are included. The largest sources of random uncertainty are the large–scale flow corrections to the velocities, combined with the very sparse sample of available galaxies. Most of the systematic uncertainty is dominated by the uncertainty in the Cepheid calibration of the method itself(Ferrarese et al. 2000a, Tonry et al. 2000). These three factors account for the 10% difference between the SBF-based values of H0 derived by the KP and that by Tonry et al. (2000). Flow–corrected velocities, distances, and H0 values for the 6 clusters with SBF measurements are given in Table 10. Applying our new calibration, we obtain H0 = 70 ± 5r ± 6s km/s/Mpc applying a metallicity correction of –0.2 mag/dex, as described in §3."

The small sample size objection is specifically addressed. While it is one of the larger sources of error, the total error is still less than in the Fundamental Plane result that dgruss23 promoted without any mention of its error budget. Note that there is no mention whatsoever of this alleged error rising from "assuming that the SBF galaxy is at the mean cluster distance" that supposedly renders the SBF result "irrelevant".

As I said, it is not statistically significant. This is because +/-0% is within 1 sigma.

I don't know what you mean by "likely", but if we take 77, 80+ has a probability of about 1/3. I would call that possible, but unlikely. Still, 77 is on the high side of recent measurements.

+7%+/-8% (from this paper: http://arxiv.org/PS_cache/arxiv/pdf/...707.3144v1.pdf) means that the "true correction" to HKP's "best value" for H₀ is -1% to +15% (68% confidence). Not all figures within this interval are equally likely, their "best value for correction" being +7%.

And 72*1.07=77.04

Here is the ADS webpage for Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant, by Wendy Freedman and 14 others.

From this webpage, you can get the published 2001 ApJ paper (PDF), as well as the arXiv e-print (arXiv:astro-ph/0012376).

You will also find links to the 1115 papers that cite this HKP one.

Your words zahl:

Perhaps what you wrote was not what you meant, but how else should one interpret the above other than to conclude that you thought there were more than 6 SBF galaxies used in the H0 determining sample? How does one measure the distance to a single galaxy in a cluster (which you now claim you always understood that they did - despite the above quote) and not have that single galaxy represent the cluster distance?

Oh - and by the way, what you wrote above is not even a correct description of what they did. What you wrote states that they find the distance to a galaxy, then find a cepheid distance to that galaxy for calibration (zero point calibration), then measure the redshift, and then calculate H0. For someone that is telling me I'm ignorant, pathetic, intentionally misleading Baut readers ... this is a very profoundly incomplete description of the process to the point of fault because it leaves out important steps. You left out that part about how they extend the local calibration in which Cepheids are used to more distant galaxies for which Cepheids are not used. As you wrote it you make it sound like every SBF galaxy used to calculate H0 also has a Cepheid distance. Even the 4 step process I provided in my previous post leaves a lot out - but at least it it doesn't give an incorrect perception about the basic procedure.


What????? I didn't quote the paper???? I would like everybody to note that in yesterday's response to Zahl I quoted from both papers I linked to - including the very paragraph that precedes the one Zahl has just quoted. Specifically this quote:


Could you explain further how it is addressed? They state that most of the systematic uncertainty is due to the Cepheid calibration, they don't explain how they arrive at that conclusion - do they? They do not specifically explain how they can be certain that the galaxies with SBF distances are actually at the mean cluster distance.

For example, - as I've already noted - they find a distance of 102.3 Mpc for the Coma cluster using NGC 4881, but using 28 galaxies with I-band TFR distances they get 85.8 Mpc. So how do they know NGC 4881 is not on the backside - or that there is not a systematic error in the SBF distance?


Is this an intentional mischaracterization of what I've said earlier on this thread? I already responded to this in an earlier post:

You chose to call the above word games. The fact is I did not "promote" (talk about creating straw man arguments) the FP. I explained above the reason it was mentioned. It is there for everyone to judge for themselves. But it really doesn't surprise me that one who so liberally states people are ignorant, half-senile old men, don't know what they're talking about, pathetic ... would continue to repeat faulty mischaracterizations of what a person stated that have already been adequately explained.

Whether intentional or not Zahl, this is a very old debate tactic you're using - making your opponent respond to false charges. Happens in politics all the time. Unless you are ignorant as you stated I was, you should be capable of grasping my earlier explanation on the FP. Is there anybody besides Zahl following this discussion that would like to share your thoughts as to whether or not my earlier response to Zahl regarding the FP is a clear enough description of what I meant. Note that you would not be endorsing anything I've said by contributing in this regard - simply confirming that my explanation is or is not understandable.

Now zahl, keep in mind you have accused me of promoting FP which I have stated I did not. Since we're talking in this instance about my intentions in bringing up the FP - your choices are to either accept my explanation of my intentions and stop repeating your mischaracterization or reject my explanation. If you reject my explanation about my intentions then you are accusing me of lying. So which is it?

Right - they don't mention it. That is my point --- they take it to be a good assumption that the galaxies in question are good representatives of the average distance of the cluster. You seem to think that because they don't mention it, it doesn't need to be explained? How do you determine a cluster distance from a single galaxy without assuming that galaxy is at the average distance zahl? And if you do take that single galaxies distance as the mean cluster distance, how do you rule out that the galaxy is not on the backside or frontside of the cluster?

__________________
"The scientist who asks the right question reconnoiters a new patch of the unknown, and may, with luck, bring it within the constricted but expanding boundaries of the known."

~Timothy Ferris (The Red Limit) 1982

If you want to get into some published estimate (a distance, say), in a deep way, you have (IMHO) no choice but to learn how the authors of the relevant published papers came up with their estimate ... and the nature of the uncertainties and errors in all key parts of the chains that lead to those published estimates.

If, on the other hand, you want a nice 'sound bite' summary, but also want to avoid looking foolish by over-simplifying ... can you?

Let's take an example.

Suppose the widely used estimate ("the canonical distance") is 480 ± 80 parsecs. Suppose a new estimate, based on a single measurement, using a new technique, is published; suppose it is 389 +24 −21 parsecs. Suppose you wish to avoid looking foolish. Would the following be prudent "a luminosity error of 1.5 magnitudes [...] has the potential of requiring a major revision in distance scaling"? (Assume, for now, that a distance difference of ~90 pc translates to a luminosity difference of 1.5 mag.)

Clearly, the two distance estimates, at the 1 sigma level, overlap (480 - 80 < 389 + 24); in the future, perhaps the distance estimate will be refined, to settle on 405 ± 2 pc, so both the widely used (older, canonical) estimate AND the newer, single measurement estimate are consistent with this (possible, future) value. If this turns out to be the case, then your "luminosity error" statement would look exceedingly foolish.

And so on ... we could explore a number of possibilities (including unknown, or mis-estimated, systematics in the newer, single measurement; more nuanced uncertainties - including systematics - in the canonical estimate, nuances clearly stated in the original paper but dropped in subsequent references; and the errors quoted being something other than 1 sigma/68% confidence), but at the sound bite level, the fact that the 1 sigma distance estimates overlap should be sufficient to rule out anything that implies an inconsistency.

For those interested in digging deeper into this, you might look at how researchers come up with error/uncertainty estimates, both random and systematic. In particular, read up a bit on the differences between 'frequentist' and 'Bayesian' approaches (the former almost universally used by astronomers of yore; the latter now regarded as better, though not yet in universal use).

Relevance of the above to this thread? The Freedman et al. HKP paper, in Section 7, discusses how the authors combined five sets of estimates of H₀, obtained using five different methods, into a single estimate (Section 8 looks at common systematics); it's a quite interesting read, and (among other things) illustrates well the pitfalls of:
"H₀ = 72 ± 8 km s⁻¹ Mpc⁻¹".

HKP makes it clear the distance to the SMC is a key parameter in the method they used to refine the value of the Hubble constant. A revised distance to the cloud automatically shifts the value of Ho. I don't see this as an inconsistancy, and would not, even if it changed the Hubble value more than one sigma, because it was known at the time of publishing that the distance to the SMC is still in limbo.

Reducing the distance to the SMC does cause a seperation between the HKP Ho value, and methods which do not depend upon the SMC distance; and predict a Ho value in the mid 60's. This included the gravitational lensing and supernova type II methods. (There was a paper within the last year that identified probable selection effects in supernova type II distance studies, I will try to find it.)

I don't like this consensus approach, because it exudes unreasonable confidence in assumptions common to some or all of the methods. This could drag the Ho away from the 'true' value, whatever that might be.

A gross error in Ho remained undetected for a half a century because a pair of systemic errors within our own galaxy were nearly offsetting. There is a potential for an almost identical pair of errors to exist today: Dust extinction and Malmquist bias of supernovae on a cosmic scale. The irony here, is that the Ho value may be very close to correct, but the wider implications of selection bias and incorrect extinction estimates overlooked.

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jwj

It's a big universe out there...is it really unwinding, really burning out?

The above was refuting your mistaken claim that a single galaxy is used to represent the cluster distance that you have repeated several times. You have provided no quotes to that effect, because it is not what they have done. Such nonsense is a figment of your imagination and you have provided nothing but your deluded words to support that crazy assertion. Instead, the HKP paper clearly states that the SBF method uses distances to galaxies and their recession velocities to derive the H₀ result, not clusters. Table 10, Surface Brightness Fluctuation Hubble Constant, documents this fact plainly.

http://www.journals.uchicago.edu/ApJ...417/52417.html

Six galaxies with their measured recession velocities and distances with the calculated H₀ values are given. There is no need for the SBF galaxy to be representative of the mean cluster distance, just like I wrote, because it is the distance to the galaxy they are after. The error budget is discussed elsewhere as I already noted and it does not support dgruss23's dreamed up errors. And that's all there is to it. I don't wish to dive any deeper into dgruss23's word games.

A side comment: There seems to be an obvious difference of opinion or interpretation between dgruss23 and Zahl. Zahl, your use of such terms as "nonsense, figment of your imagination, deluded words, crazy assertions, word games, etc" isn't fitting for a forum where questions are asked by either seasoned researchers to clear up a point, or more inexperienced observers who want to understand. I am surprised the Moderators don't rein this in on a Q/A forum. I can understand somewhat how emotions get more in play on the ATM forum, but not here.
Anyway, such rhetoric isn't appreciated by those trying to follow what should be a scholarly discussion that should be free of this stuff.
TomT

Zahl, they did use a single galaxy per cluster. I have provided the quotes and reference to Table 4 of Ferrarese et al 2000:

Please look at Table 4 of Ferrarese et al. I believe that any rational individual can see from that description and a look at Table 4 that the HKP did in fact use one galaxy per cluster. However, I also provided in an earlier post the following quote from the Freedman et al HKP final report:



So this quote establishes that the HKP in fact only used 6 galaxies for the SBF analysis - and Table 4 from Ferrarese et al 2000 shows which cluster each of those galaxies is in. Zahl, this point is irrefutable. It is what they did. Anybody following this thread can read it for themselves. And it seems that I have already in prior posts provided quotes you're saying I didn't provide.

But now you seem to be taking a different approach. Now you're saying that they used 6 galaxies only and the redshift from the galaxy was used, not the cluster -- so you're now taking the position that the redshifts used were not cluster redshifts, but individual galaxy redshifts:

There are two parts to this - (1) whether or not what you're proposing is what they actually did (one galaxy distance, redshift for said galaxy not the whole cluster, H0), and (2) whether or not what you're proposing they did would be a good idea if they did in fact did do it that way. I'll dissect each in turn.

1. Did the Hubble Key project use a mean cluster redshift or the redshift of the galaxy for which the SBF distance was determined when they found H0 from the SBF method?
Well, let's go by their own words. From Ferrarese et al (2000):

Note Ferrarese et al did not say the last difficulty was to find the "galaxies" cosmic velocities. They said "clusters". Why would they say "clusters" if they meant "galaxies" Zahl?

And from Freedman et al 2001 (the very paragraph you quoted earlier this morning zahl!):

Again they use the term "clusters". But we've already established above that the SBF involved 6 galaxies and we've already established that there is one SBF in each clusters. And we know that the distance to the SBF galaxy is what they are using. So either the HKP used the term cluster incorrectly, or they really did caculate cosmic velocities for the cluster sample as a whole and applied it to the individual distances of the SBF galaxies as representations of the mean cluster distance.

However, there is another way to check this out. Table 4 of Ferrarese et al (2000) lists the heliocentric velocity of the Coma cluster as 6965 km s-1. Is that the mean cluster redshift or the redshift of the SBF galaxy NGC 4881?

Well here is the list of redshifts for NGC 4881 from NED. Note that all these redshifts except for one value are ~6750 km s-1 - over 200 km s-1 less than the redshift given in Table 4. This certainly supports the interpretation that the redshift in Table 4 was not the NGC 4881 redshift, but rather the Coma cluster redshift derived as the mean of multiple galaxies within the cluster.


(2) Would it be wise for the HKP to determine the value of H0 from individual galaxies in clusters using the individual redshift of the galaxy as Zahl is proposing they did?

The answer is absolutely not - it would be absurd and while I'm critical of the SBF and Type II SN sample sizes they used, I give them a lot more credit than to think they would be foolish enough to compound using a single galaxy's distance in a cluster with the redshift of that single galaxy.

Here is where Zahl's idea about what they did goes wrong. Galaxies in clusters have peculiar motions. If you take any of the other cluster samples the HKP used such as the I-band TFR or the Fundamental Plane cluster samples, they anywhere from ~ 7 to 80 galaxies in those clusters and they did not use the individual galaxy redshifts, they used mean redshifts of cluster members corrected for various gravitationally induced flows (discussed in their papers). Any individual galaxy might have a redshift as much as 1000 km s-1 larger or smaller than the cluster mean so you cannot use an individual galaxy's redshift to represent a cluster.

The lowest redshift members of the Coma cluster have redshifts of ~ 6000 km s-1 while the largest redshifts of cluster members are ~ 8000 km s-1. Such a range provides huge range of H0 values. So you take the mean of multiple members in the cluster and hope that the cluster is close to being at rest relative to the Hubble flow. If it is, then the mean of the cluster members will be the clusters cosmic velocity.

I simply do not believe that the HKP made that mistake of using an individual galaxy redshift and the quotes I've provided above support my position, not Zahl's.

What the HKP did do - which I've urged caution about, is with the SBF method they - due to data availability - used only the brightest cluster galaxy for each of the 6 clusters. What they are counting on when they do that is that the BCG is close to the cluster center - which is a very plausible possibility - although you have to watch out for significant substructure such as what we see in Virgo.

__________________
"The scientist who asks the right question reconnoiters a new patch of the unknown, and may, with luck, bring it within the constricted but expanding boundaries of the known."

~Timothy Ferris (The Red Limit) 1982

Now I want to comment on the behavior exhibited in Zahl's comments:

It is possible to have polite debates. My tone tends to be a mirror of the tone directed toward me when someone responds to my posts. In the case of Zahl, I cannot fully mirror his tone because most of what I've highlighted in red is unnecessary and rude.

What is troublesome about this is that Zahl has been repeatedly shown to be wrong and each time I demonstrate this with quotes from papers and explanation he responds with more vitriol than his previous response. Let's take a look at all this when put together:

Accusation of personal bias:

Accusation of word games and deliberately misleading BAUT readers:

Statement that I'm ignorant:

Flat out incorrect statement that I have not supported my points with quotes from the papers:

And finally we come to the most recent post made by zahl which I've quoted above and in which he includes six rude and/or unnecessary descriptors highlighted in red.

Individually these comments might not be a big deal, but there is a pattern of poor behavior on Zahl's part. What makes it worse is that his justification for the various insults and characterization is based upon specific assertions he has made that I am mistaken - assertions he made that have been easily shown to be wrong - to the point he should be embarrassed that he would use such insults.

Frankly, I don't understand what all the rudeness is about Joshua. But it is no different than when you went by "JS Princeton" or "Astronomy" or "Q" on the Universe Today forum or "Science Apologist" in other venues.

Seriously, it is time for you to grow up and learn how to have debate with some dignity and respect. All the rude comments are unnecessary.

And Zahl, if you're not the latest incarnation of JS Princeton (as I believe you are), my apologies, but there is only one person I've ever encountered on these discussion forums that is as consistently and needlessly rude and insulting in debate as what you are exhibiting in this thread - JS Princeton.

__________________
"The scientist who asks the right question reconnoiters a new patch of the unknown, and may, with luck, bring it within the constricted but expanding boundaries of the known."

~Timothy Ferris (The Red Limit) 1982

Zahl, as TomT and dgruss23 have both noted, your language and tone is in violation of Rule 2 ("Civility and Decorum") of this forum. You are welcome to disagree and to disagree strongly, but please confine yourself to addressing the specifics and don't make sweeping, dismissive statements that only serve to offend.

TomT and dgruss23, I understand your efforts to preserve decorum on this thread, but trying to handle Rule 2 violations on your own is in itself a violation of Rule 2. In future, please notify a moderator and leave the driving to us.

As for the claim that Zahl is JS Princeton, unless the latter has moved to Finland (where all of Zahl's IP addresses hail from), that seems unlikely. In any case, the user "JS Princeton" was unbanned as part of the general amnesty created by the BA-UT merger and could use that same account if he so desired.

__________________
Everything I need to know I learned through Googling.

I'm sorry about that ToSeek. I considered I might be out of bounds with that last post, but I also know sometimes people defend themselves in regard to the personal attacks, so I felt the cummulative effect was worth pointing out. I did e-mail a moderator a few days ago as a warning that this discussion might go in this direction (under the assumption that Zahl was JS Princeton - which you corrected below), but never heard back so perhaps that mod is on vacation.

I'll certainly accept that correction and apologize to Zahl for suggesting he/she is someone he/she is not. JS Princeton is still in the USA. The parallels in posting style are extremely similar in a number of ways - as is the frustration it creates. Now I guess I've observed that style not once - but twice.

Thanks ToSeek.

__________________
"The scientist who asks the right question reconnoiters a new patch of the unknown, and may, with luck, bring it within the constricted but expanding boundaries of the known."

~Timothy Ferris (The Red Limit) 1982

Reguardless if Zahl is really Zahl or another entity, Zahl is well aware of this rule and has been advised by a Mod on this previously.

Here is that post and this same 'attitude' is evident throughout his postings there as well.

Local features in the WMAP map?
The thread

Local features in the WMAP map?
The warning from a Mod

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

Please don't tell the moderators how to do their jobs. We have processes in place to keep track of just this sort of thing.

__________________
Everything I need to know I learned through Googling.

My humble appologies ToSeek.

I was definitely not trying to suggest or 'tell' Mods anything.

This was strictly meant as support of dgruss' position and Everyone's concern for decorum on BAUT.

See the other thread for exactly the same concern from everyone.

Again, sorry if this was not appropriate.

__________________
RussT
________________________________
Everything is, as it should be, otherwise, it wouldn't be!

This comment is coming from way out in left field, so take it as you wish.

I have spent a lot of time studying cycles in many things. I have found that very often that cycles are accompanied by the presence of waves (well that bit isn't way out ) and that these two aspects are often observed in different ways and not linked up. An example is Kotov's observations in the Solar System of 160 minute oscillation in the Sun and the outer planets being at ~10 AU regular spacings which are therefore on the nodes of a 160 minute period wave.

There is a geological cycle that is reported as nearly 600 million years and a series of other ones at repeated halvings of that, and the period of which has been determined accurately by Prof S Afanasiev of Moscow University as 586 million years.

Some time ago a paper was published showing very regular walls of galaxies, see http://ray.tomes.biz/gallwallc.gif which has the graphic and the references. The stated periodicity is 128 Mpc which should also have one of those H adjustments. When H had been stated as ~71 km/s/Mpc a few years back, I did the calculation and found that this gave a wavelength of about 588 million light years. I know you astronomers don't use light years these days, but if you did you would increase your chances of noticing these things.

If the regular walls of galaxies are taken as being due to some wave phenomenon as has been suggested by others, then it is not surprising that it would also show up in geological phenomena, because the forces must be very large. Assuming that the geological period is accurately determined by Afansiev (he actually gives 586.24 million years), then with the redshift periodicity of the walls this can be used to calculate the Hubble constant accurately. The answer I get is 71.2 km/s/Mpc. This is limited to the accuracy of the 128 Mpc stated figure and I think within 1%. (Note that this figure is really a redshift periodicity not a distance).

The method could potentially be made more accurate and has the wonderful advantage of not being dependent on the whole distance scale ladder at all.

Jerry said: “This is also significant because there have been several attempts to determine the Hubble constant, such as lensing an SZ effects, (not included in the HKP) that places the value in the mid to low sixties, and are not dependent upon LMC scaling.”

Actually, Jerry, just for reference, the most recent determination of the Hubble constant derived from SZ measurements is in the mid-70s rather than the mid to low sixties. Here is a link to the paper I am referring to: arXiv:astro-ph/0512349

Let’s assume that Jerry is correct and all of modern physics is up for grabs. Advocates of this view, at least until they, of course, enlighten the ignorant masses, (as ATM aficionados often tend to be as much or more dogmatic than the people they criticize) would be hard pressed to explain why we cannot do certain things in certain ways no matter how much we might want to do them. If all of modern physics is up for grabs, as Jerry clearly admitted to believing, then where are our light sabers, FTL travel and communication, routine time travel into the distant past, perpetual motion machines, etc? It’s just a brute fact that breakthroughs in our understanding of nature have led to technological advances. The fact that certain breakthroughs have not occurred and most likely never will occur is a strong sign that nature is telling us something about itself- namely that the Universe is almost surely constructed in a definite way that allows intelligent beings to accomplish a finite number of fundamental technical feats. It is “scientific uncertainty” that allows for the very remote possibility that light sabers, FTL technology, and the wrongness of the current cosmological model are allowed for—even if most people would bet against each of those possibilities. Lastly, one cannot simultaneously (without massively contradicting himself or herself), as Jerry clearly does, admit that all of modern physics is up for grabs and then shop around and cherry pick certain parts of modern physics to buttress his or her own views.

Perhaps it's worth taking a look at the OP again, and comparing it with Section 7 of the Freedman et al. final HKP paper.

In particular, Table 12 (I'm not going to try to reproduce it here) and Figure 3.

My impression is that the biggest single aspect missing from the otherwise good overview in the OP is an analysis of what Freedman et al. call uncertainties and errors.

Starting with "Error (random)", I think it is pertinent to ask how much the OP's summary in the form of "only {x} used ..." is blind to the frequentist, Bayesian, and Monte Carlo analyses which are reported in the Freedman et al. paper. Specifically, in the absence of any alternative analyses of the random error, is it reasonable to ignore such comments (in the OP)?

Moving on to the outlier in the HKP paper (the FP): a snippet from Figure 3 may serve as an appropriate sound bite "The systematic uncertainties for each method are indicated by the horizontal bars near the peak of each Gaussian" - the horizontal [FP] bar overlaps the horizontal bars of each of the four other methods.

Which brings up the general point of systematics ...

Here's what the final HKP paper says, in summary, on the systematics of the five methods they examined:A quick scan of the ~1100 refereed papers which cite the final HKP one suggests that considerable effort has been put into addressing "the zero point of the Cepheid PL relation" systematic; indeed, the updates cited in the OP are all, I think, about this systematic.

Perhaps the most interesting question is then something like "in terms of the estimated uncertainty, in the zero point of the Cepheid PL relation, discussed in the final HKP paper, how big are the deltas from more recent estimates of this zero point?"

Specifically, do the one sigma (systematic uncertainty) bars (reported in the final HKP paper and in more recent papers) overlap?

You raise some good points for discussion Nereid. I'm actually going to address them in reverse order:

No, but how much the difference is depends upon how you compare them.

The HKP adopted a LMC distance modulus of 18.50 +/- 0.10. van Leeuwen et al find a LMC distance modulus of 18.39 +/- 0.05. An et al found a LMC distance modulus of 18.34 +/- 0.06.

So you can see that the 1 sigma errors of the recent van Leeuwen and An studies overlap. The difference between the HKP value and van Leeuwen et al is 1.1 sigma, between HKP and An et al is 1.6 sigma.

Taking the results of the new studies, the adopted HKP LMC distance modulus is 2.2 sigma larger than the van Leeuwen distance modulus and 2.7 sigma larger than the An distance modulus.


In any case, both new studies make all extragalactic Cepheid distances distances closer. Since the Cepheid galaxies are the zero point calibrators for the secondary distance indicators, this makes all the secondary distance indicator distances closer and H0 larger.


The point of this thread is to discuss whether or not H0 could be in the 80's. Do you see the above as something that establishes H0 could not be in the 80's?

Your point about the overlap of the FP uncertainty is very valid, but keep in mind - as I explained to Zahl - the fundamental plane result is not why I have suggested H0 could still be in the 80's.

__________________
"The scientist who asks the right question reconnoiters a new patch of the unknown, and may, with luck, bring it within the constricted but expanding boundaries of the known."

~Timothy Ferris (The Red Limit) 1982

Hi Nereid

Yes, I have read the rules for posting, thanks.

While there is a relationship between what I posted on the Hubble Constant and my posts in the other thread in that both are related to cycles, I disagree that this post is a promotion of those ideas. It is based only on published work by geologists and astronomers, none of which is has any knowledge of Harmonics theory, and I have not referenced that here in any way.

Certainly it is a new idea to measure the Hubble constant in this way, but the idea that there is a wave structure responsible for regular galaxy walls has appeared in astrophysics journals, and so looking at geophysical manifestations of such a wave is not a way out idea. The fact that recent values of the Hubble constant show the correspondence to be realistic should make it acceptable to the mainstream.

The idea is easily tested because there are observed to be a number of other related shorter geological cycles and these can be searched for in the redshift fluctuations in the data referenced. The longer of these cycles are quite obviously present (particularly a 4th harmonic), but the full test requires the actual data to be further analysed. I would expect the various mass-extinction cycles to show up in the data. They have shorter periods and so the periods are known more accurately and would allow an even more accurate determination of the Hubble constant.

I have tried to contact the authors of paper to get the data but have had no response. If anyone knows how to contact them I would appreciate information.

FWIW, there are considerably more than two, I think.

There are those who, as SM points out, are well aware that there's a great deal more to estimates of H₀ than just "72 ± 8", particularly the systematics (esp the importance of the zero point of the Cepheid PL relation).

There are those* who are happy to run with "72 ± 8" and neglect (or are ignorant of) the carefully stated caveats in the relevant papers.

There are those who cherry pick juicy pieces from papers here and there and string them together with winks, nudges, and idiosyncratic views of the underlying science.

And there are many sub-populations within the H₀ = 72 (or 70) population.I'd go further than SM on this^: even leaving aside the usual caveats about who did the research, where they published it, and so on, I think it's very difficult to say, in general, what the response of a sub-population of astronomers might be.

For example, if the paper also did a nice job of showing consistency with a large subset of earlier (published) observations - reconciling new research findings with old data, for example - in other words anticipating many of the likely questions that would be asked, it would more likely be given more serious scrutiny than a paper which merely, baldly, presented an analysis of a small set of observations.

Then there's the surprise factor: if the paper presenting the "H0 is in the 80's" conclusion comes out of the blue, with an approach that's never been used before, data that was not gathered using 'telescope time' granted on the basis of a (much) earlier proposal, and so on, then, cet. par., rather a lot of astronomers would likely not read it very carefully.

*Actually, this may be a null set ... almost no one seems to address the ± 8 part, unless they also indicate they are well aware that there's a much richer background.

^"Yes.

However, let me point out that there are two ways one might "present evidence that H0 is in the 80s".

One way is to use a single method --- say, surface-brightness fluctuations --- to measure the distance to a small set of galaxies, calculate the value of H0 based on those distance and radial velocities, and claim "H0 is 82". This will sway very few scientists, because it will be a small bit of evidence for a high value of H0, whereas there exists a much larger body of evidence for a smaller H0.

Another way is to find an important systematic error in one of the earlier steps on the distance ladder. For example, if the distance modulus to the LMC could be shown to be much smaller than 18.50, due to (this is just an example) some kind of previously undetected anamolous extinction between it and the Milky Way, then _that_ would probably cause more astronomers to take the idea seriously."

RTomes,

While you may disagree, a moderator has judged it to be promotion of an ATM idea outside of a dedicated ATM thread. Consequently, this is not a judgement open to debate. Incidentally, I concur with Neried and issue the same warning, and add, as a reminder, per rule #17 - if you disagree with a moderator's action, pm another moderator or an administrator. A moderator's decision isn't to be followed merely if you happen to agree. Please take this time to contact another moderator, Phil, or Fraser, if you are in further disagreeance with this action. The request will be fairly evaluated. In the meantime, the decision has been made, and compliance expected. Thank you.

__________________
"I have this theory that the Apollo missions were faked when NASA found out that general relativity was wrong because the Earth was expanding due to the Sun's iron core being influenced by magnetic waves from the electric universe after being perturbed by Planet X and thereby causing global warming. Where should I start a thread about this?" ~ ToSeek

"Those are the people that wonder how a thermos knows whether to keep something hot or keep something cold." ~ NeoWatcher

Since the expansion of the universe is accelerating, perhaps the real Hubble constant increased by about 1% over the duration of this thread? Neil

This illustrates part of what I'm talking about. The HKP used 5 methods, but the SBF method analysis involved 6 galaxies for determining H0 and the Type II SN analysis only had 4 galaxies for determining H0. Neither of these samples are large enough to stand on their own for reasons I indicated in my exchange with Zahl. In other words, if a researcher published an analysis based upon just 6 SBF distances and determined H0, the paper would not be heavily cited. As an example this paper has only been cited 3 times - by the authors of the paper.

But if the SBF and Type II SN cannot stand on their own as independent analyses, then they really don't add anything significant to the overall result of the HKP.

Since the FP gives H0=82, that leaves you with H0=72 being primarily held up not by 5 methods, but by 2 methods -- the Tully-Fisher Relation and Type Ia SN. The latter method has a high internal precision, but only 6 Cepheid calibrators at the time of the HKP final report - creating the possibility for a systematic error in the absolute calibration of the SN Ia.

The Tully-Fisher relation is subject to larger uncertainty from data errors, but has a small intrinsic scatter if data errors are managed.

Quote:

Another way is to find an important systematic error in one of the earlier steps on the distance ladder. For example, if the distance modulus to the LMC could be shown to be much smaller than 18.50, due to (this is just an example) some kind of previously undetected anamolous extinction between it and the Milky Way, then _that_ would probably cause more astronomers to take the idea seriously.

Quote:

"

The van Leeuwen et al study and An et al studies that I've cited speak to this issue.

__________________
"The scientist who asks the right question reconnoiters a new patch of the unknown, and may, with luck, bring it within the constricted but expanding boundaries of the known."

~Timothy Ferris (The Red Limit) 1982