They discuss this in the introduction of the paper and cite Gibson et al (2000) . Specifically, Gibson et al did not find the predicted amount of blending influence in the residuals of type Ia SN and Tully-Fisher residuals. Gibson et al argue that the high stellar background of the LMC and M-31 fields is not representative of the more distant galaxies. Also see Ferrarese et al (2000) .

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"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

Ah, I see. Thank you.

What Vilardell et al. have done is to define "blending" as the mixing of light from a target Cepheid and any gravitationally bound companion stars, while using the term "crowding" to refer to the mixing of light from a target Cepheid and "unrelated" stars which appear in the same general area. Using these terms, "blending" is important only in nearby galaxies, because it is only in (VERY) nearby galaxies that we can hope to resolve most of the "unrelated" stars from a target Cepheid.

It's not clear to me that the distinction is very important. After all, the major effect of both "blending" and "crowding" is to diminish the amplitude of a Cepheid's apparent variation in light.

It is really not correct to say blending is not important either. What Gibson et al really demonstrated was that the effects of blending/crowding ultimately did not have a global influence on the distance scale.

I also have my doubts about their claim that the NGC 4603 Cepheid distance may be underestimated by > 1.0 mag because of extreme crowding effects. They make this statement based upon the H-band TFR distance the HKP found for the Centaurus cluster. However, the SBF distance to the Centaurus cluster (Tonry et al) is the same distance as the Newman et al Cepheid distance. I also find that the TFR distance is consistent with the SBF distance using 2MASS Ks band magnitudes. My own investigation suggests that the HKP I-band TFR distances have overestimated cluster distances.

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"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

It is interesting how the spread in values for the hubble parameter has been shrinking over the years. Few groups are still getting results of Ho in the 50s and 80s, but many more groups are getting results in the 60s and 70s. Even Sandage et al, an adamant proponent of a lower value for Ho, recently published a paper which put Ho at 62. So I think that, unless some unlikely trick of nature or coincidence is at work, the Hubble constant is almost surely between 60 and 80-- and probably right around 70. Perhaps one could do a statistical analysis of the narrowing of the spread of Ho over time and then extrapolate to determine roughly when Ho will be "nailed down." Lastly, as antoniseb touched on, the GAIA mission will significantly improve measurements of the cosmic distance ladder thereby ending the debate over the exact value of Ho. Here is a paper which describes the missions like impact on this very important part of astrophysics:
GAIA and the Extragalactic Distance Scale or http://arxiv.org/abs/astro-ph/0208178

This is my reason for starting this thread. It doesn't require any tricks of nature for the current value of H0 to be underestimated. Recall some points I made in the OP:

This is not me making stuff up - it comes right from the HKP final report and the other papers mentioned. Everybody likes to think "The HKP used 5 methods to find H0=72. They've nailed H0."

But wait - only 4 Type II SN were used - with only 3 zero point calibrators. The Type II SN result is irrelevant. And only 6 galaxies with SBF distances were used - again the result is irrelevant.

That leaves 3 methods: Fundamental Plane, SN Ia, and the I-band TFR. The Fundamental Plane gives H0=82 - not 72, but you never hear people talk about that.

The SN Ia give H0=~71, but only 6 zero point calibrators were available. The I-TFR also gives H0=~71, but where comparisons are available, their cluster distances severely overestimate the distances relative to the distances derived from other methods as I noted in the last bullet above. If you overestimate distances, you underestimate H0.

And none of the above touches upon the recent results of van Leeuwen et al (linked to in a number of earlier posts) and other groups that find a downward revision of the Cepheid P-L zero point which would systematically reduce the distances of all the Cepheid calibrators and the resulting zero points of the secondary distances indicators.

And as for Sandage, he gets a low value of H0 by advocating huge bias corrections under the assumption of much larger intrinsic scatter in the distance indicators than is observed empirically. In fact, van Leeuwen et al showed that he adopted a Cepheid P-L slope too steep which makes his value of H0 meaningless.

The studies that find H0 adopt different assumptions and methods. Such an analysis would not really tell you anything. It would be much like what Lyndon Ashmore does when he adopts H0=64 because it is the average of numerous studies in the literature.

Here is the key point from their abstract:

Gaia may lead to a refinement of the slope and zero point of the Cepheid P-L relation, thus reducing the statistical uncertainty of those factors, but that may only result in a negligible change in the distance scale. You then must apply that to the secondary distance indicators to get a value of H0 - and we're right back to looking at fixing the problems with the HKP results.

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"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

Sandage was getting beat over the head and shoulders about how far his surface brightness methology diverged from relativistic predictions. He adapted, because luminosity evolution became the 'most reasonable' explanation, not because his raw technique produced higher values for Ho.

To any degree that the convergence around a consensus value is driven by the desire for an uncontroversial consensus, confidence in this trend is misplaced. A better question is why surface brightness studies require luminosity evolution that is not consistent with large scale metallicity trends?

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jwj

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

I just found this, which would appear to be right in the middle of this entire subject area.

http://www.seds.org/messier/m/m064.html

Here are a couple of questions if someone wants to take a stab at them.

1. Is this the first/only galaxy that has been found to have the inner stars rotating in the opposite direction of the outer disc stars...IF that is really the case!?

2. What is the farthest galaxy where we can accurately determine the galaxy rotation curves of one side of the galaxy being redshifted moving away from us, and MORE IMPORTANTLY, actually 'measure' the 'Blue-shifted' stars moving toward us???

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

Dgruss23 said: "The studies that find H0 adopt different assumptions and methods. Such an analysis would not really tell you anything. It would be much like what Lyndon Ashmore does when he adopts H0=64 because it is the average of numerous studies in the literature."

Maybe I am reading him/her wrong, but I get the impression that dgruss23 thinks the Hubble constant is 80 or above, or, its actual value will forever remain elusive due to....

It's just not fair.
There's no way of getting at what's out there.
There's no objective truth.
Don't fool yourself mortal, forget about proof.
All analyses have their flaws.
Careful thought will only run up against nature's impervious walls!

There is a conspiracy afoot to suppress all alternatives.
It is easier to criticize than to produce your own results.
We are now really no closer to understanding anything about the large scale Universe than what we were during the neolithic.
But if astrophysics is akin to literary critical theory, then what is the point of engaging in expensive astrophysical research?
The cosmos is shrouded in mystery.
Let's be reluctant cosmologists and radical skeptics.
Cosmology has no direct benefit to humanity even close to research in the life sciences.
And if there really is some fundamental reason why we will never be close to understanding anything about the large scale properties of the Universe, then why should we trust the assumptions/methods behind the ATM Universe-students?

Or, alternatively, we could accept that astrophysicists are making significant progress assembling a giant "Universe story jigsaw" and some unforeseen technological breakthrough which may benefit life will come from the practice of astrophysics.

Jerry,

Jerry and his fellow ATMers should be careful not to continue to engage in inevitable divergence from a consensus value because of their unceasing desire for controversy as the consensus!

There is no such thing as an uncontroversial analysis, including Jerry-like ATM analyses which inevitably exhibit the same flawed methodology:

Jerry et al boldly try to lift away the proverbial fog (all the while making assumptions of his own) and set us straight in an I am holier than thou manner--hardly the kind of humility one might expect from a true radical skeptics. Jerry et al view is that most of modern physics is still up for grabs, very little of what is said to be known is actually known, life is full of mystery, etc. Essentially, Jerry et al seem to hold a philosophical assumption which is, at least in my opinion, pretty nihilistic and gloomy--that is, they assume that the Universe is inherently unknowable and impervious to human understanding. Hence, Nereid's "Jerry radical skepticism" phrase is quite apt. Yet time and again, very strangely, Jerry et al DESIRE to have it both ways-- they act like so much is unknown or unknowable about the Universe; however, uncannily, precisely enough stuff is known so they can use at least something as a foundation for their ATM idea. Thus, Jerry et aL, like most ATMers, hold a philosophical assumption/methodology which they themselves persistently violate, time after time after time...

Well, I've stated that the reason I started the thread is to show how it is still possible for H0 to be above 80.

Is this the best you can do? I've made very specific points on this thread - as always backed up by journal citations and explanation. You could respond to those points. I really don't understand what your tantrum is all about. I'm trying to have an intellectual discussion here. If you're uninterested or incapable then please feel free to ignore this thread. Your little dramatic fit deserves no further comment.

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"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

Why single out one method, especially one that has the largest systematic errors? The FP involves the measurement of three observables with an intrinsic scatter of 10-20%, an indirect Cepheid calibration (since there are no Cepheids in fundamental plane ellipticals), assumptions that M/L ratios always scale with galaxy structural parameters in the same way and that early type galaxies always have similar stellar populations for a given galaxy mass, etc.

So it is not surprising that the FP is a particularly error prone method and is seldom used. Add to this the fact that the HKP used only 3 targets to calibrate the FP (Leo I group, Virgo cluster, Fornax cluster) and - according to the most recent determinations in the literature - may have underestimated their distance.

Except that I did not single out one method. If take another look at my posts, you'll see I've commented on all 5 methods the HKP used. In fact, the extent of what I've said about the FP is that the HKP found H0=82 with it. Why single out my comments on one method only?


I'm well aware of all this. You'll note that I have not argued the Hubble constant could be in the 80's based upon the FP. I've made other points that support my contention.

But it seems then, that - if you find the 3 target clusters problematic, you would also find the dearth of calibrators for the Type II SN (3); Type Ia SN (6) and SBF method (6) problematic?

What references would you be referring to in this instance? I did an ADS search, but I'm not sure if you're referring to the FP itself, or the 3 clusters used to calibrate the FP.

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"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

You dismissed other methods, even going as far as calling SBF "irrelevant" even though it actually has smaller systematic and random errors than the FP result that you accepted at face value - then paraded the 82 figure multiple times in the thread. You drew attention to the number (6) of SN Ia calibrators used by the HKP, but not even mentioned that the FP used only 3 and that they were indirect. You completely ignored the very numerous and complicated sources of error in the FP method that I summarized in my previous post, then asked why you never hear people talk about that result. Well... Either you were not aware of all this or your personal bias is obvious.

I did not call the SBF irrelevant. I stated that the HKP result with the SBF was irrelevant because they only used 6 galaxies in their analysis. That's a big difference in meaning. And I don't ignore the smaller systematic errors in the SBF method, but the HKP only used 6 galaxies and therefore their determination of H0 from this method is irrelevant. The sample is too small.


You're drawing the conclusion that I "accept the FP result at face value" on very meager information. Here is the sum total of what I've said about the FP on this thread:

How do you conclude that I accept the FP H0 result at face value from that? I mentioned it twice and expanded on those mentions zero times.

My point from the start on this thread has been that H0 could be in the 80's. Everybody likes to think that the HKP used 5 methods to get H0 = 72 and because of the use of 5 methods the 80's is not possible. Sure they used 5 methods, but only 4 of those methods led to H0=~70-72. The FP result did not support the rest. And I maintain that the samples are too small for the SBF and Type II SN samples used by the HKP. So now that 5 methods has been trimmed down to 2 methods: the Tully-Fisher Relation and Type Ia SN.

As I said before, if you go back through this thread and look at my comments you'll see that the primary support I've offered for the possibility that H0 could be in the 80's involves the NGC 4258 maser distance, van Leeuwen et al study, and the Tully&Pierce (2000) I-band Tully Fisher result (Luminosity-Linewidth actually - Dr. Tully never uses the name "Tully-Fisher" in his papers). Please take notice that I have not argued that H0 could be in the 80's because the FP gave H0=82.

As I stated above - and I realize I didn't clearly explain my meaning on this point when it was mentioned - but my reason for stating the HKP FP result is that only 4 of the 5 methods the HKP used gave H0=72. The calibration limitations with the FP are not relevant to that point. The fact is that one method did not give H0=72.

Now if I was arguing H0=82 based upon the FP result (which I have not and if you don't believe me carefully re-read the thread) - then this point you've made would be important.

As I told you I was aware of the limitations with the FP. As I said to folkhemmet, I'm trying to have an intellectual discussion here on the possibility that H0 could still be in the 80's despite the HKP results.

You've responded to nothing that I've stated except two sentences on the fundamental plane and then tell me I have a personal bias.

BTW, you never did answer these questions:

I ask questions when I'm genuinely interested in the answer, not to make my posts longer.

Edited to add:

I just remembered I did have one other mention of the FP in the fifth bullet from the first post:

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"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

We seem to stay with a value of Hubble constant for a few years then change it by a few percent, so we should not be surprised if the Hubble constant changes a few more times. Neil

The historical context of how the consensus value for the Hubble Constant has been established is very important.

The slippery-ness of the zero-point in the calibration of the Hubble flow is not trivial: This is where the baton is passed between local and cosmic scaling, and a careful reading of HKP reveals this is where there is the greatest descrepancy in the methods used to establish the consensus Hubble value!

Like it or not, since 2001, the widening family of light-curves observed has eroded the prior confidence placed in our understanding of the absolute magnitude of supernova-like events:

http://arxiv.org/PS_cache/astro-ph/p.../0612198v1.pdf

http://arxiv.org/PS_cache/astro-ph/p.../0512574v1.pdf

The fog is scientific uncertainty. What is not known, is if the types of errors identified by the researchers quoted above, and other yet-undetermined errors, shift the baseline enough that the real nature of the the Hubble flow is obscured. Looking at the failure of the HKP to resolve a solid zero point for the Hubble flow, the results can be just as easily be interpreted as evidence one or more of the methodologies used to determine the Hubble constant must be flawed.

Absolutely. It is not a convergence of opinions and/or theories that governs the scientific method, it is a convergence of observations, and the universe keeps getting bigger.

For more than a century it was considered 'scientifically' unsafe to swim after eating. Someone finally sorted through all of the observational data, and concluded there was no scientific bases for this long-held consensus theory propagated by thousands of scientists within the medical community. It can happen again.

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jwj

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

Sure it could. Problem is that you have not provided evidence that you're the one who is going to make "it" happen.

Why does this read like an ATM thread??

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"The facts gentlemen, and nothing but the facts, for careful eyes are narrowly watching." Isaac Asimov

It was certainly not my intention for this to be an ATM thread. I'm not promoting an ATM theory in this thread. But I suppose - given that most people have accepted H0=72, that it will sound ATM if someone suggests that H0 could still be in the 80's.

But I would not classify that argument as ATM. We're just talking about the value of the Hubble Constant. Even Tully&Pierce pointed out that they would get H0=86 from their Luminosity-Linewidth analysis if the maser distance to NGC 4258 was used to fix the Cepheid P-L zero point rather than the LMC distance.

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"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

Actually, most astronomers I know -- including myself -- are well aware that the Hubble constant could range anywhere between, say, 60 and 85 km/s/Mpc. We understand that significant systematic errors are possible, even likely.

For convenience, however, when we publish quantities which depend on the value of the Hubble constant -- the luminosity of a sample of galaxies between z=0 and z=0.2, for example -- we often quote the results for one particular value of the Hubble constant; in many cases, H0 = 70. Why? So that it's easier to compare these results against others.

Sometimes astronomers publish quantities with a little factor of "h" included; that stands for "the value of the Hubble constant, divided by 100 km/s/Mpc." By inserting one's favorite value into the "h" factor, and carrying out whatever computations are indicated, one can then convert the published value to the equivalent for another choice of H0.

In this case, I think that the astronomical community as a whole isn't as dogmatic as the press may portray it. We're not always so stupid ...

I'm not interested to play word games with you, dgruss23. If it was not due to ignorance, you deliberately misled BAUT readers by dismissing the Hubble Key Project SBF result as "irrelevant" even though it has smaller systematic AND random errors than the FP result. It is completely laughable to claim that a result with +/- 5 random and +/- 6 systematic errors (the SBF result) is "irrelevant" and then present another without any discussion of systematic or random errors that both are larger. If this was deliberate, it was incredibly rude and offensive to anyone who understands these things. As for the water maser distance, it has recently been determined by many authors that the maser and cepheid distances now agree and that the resulting H₀ value is still in the 70s. If there was a contemporary case to be made for H₀ in the 80s, somebody would make it but nobody has. It is possible, but unlikely.

For Leo I, Fornax and Virgo distances, search the ADS.

Thank you, but I'm well aware of all this. I don't know where I fit into this when you talk about "astronomers". As an independent researcher - using previous published data - I've published research in The Astrophysical Journal and Astrophysics&Space Science. So I understand much more than you might think - although I wouldn't necessarly consider myself an "astronomer".

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"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

I don't play word games. I choose my words carefully. I cannot help it if you choose to interpret meanings that I did not state and thus put me in the position of needing to explain the subtlety of the English language for you. You would do well to actually ask me what I mean if you suspect I have made an error rather than assume I have some deceptive intent.

Like it or not, there is a difference between saying that the SBF distance method is irrelevant and saying that the HKP SBF estimate of H0 is irrelevant because they had too small a sample size. That is not playing word games. That is distinguishing between different meanings. You interpreted what I said incorrectly and then want to get all offended and cranky about it.

Did you actually read what I wrote???? There are no word games here. I was very clear when I responded to you:

I stand by what I've stated. The HKP used 6 galaxies for their SBF analysis. That is not enough galaxies to determine H0. I once had a referee tell me that a sample of ~ 240 galaxies I was using was too small and you want me to take an H0 estimate from 6 SBF distances seriously?

The small systematic uncertainty of the SBF distances does not change this situation. If they had even used 3 galaxies per cluster instead of one the situation would be changed. The HKP's single SBF distance to the Coma cluster galaxy NGC 4881 gives a distance of 102.3 Mpc whereas they (the HKP again) get 85.8 Mpc from the I-band TFR (using 28 galaxies)- in line with what Tully&Pierce (2000) got with the TFR (86.3 Mpc - using 28 galaxies). The SBF distance to NGC 4881 can be bang on and it doesn't make it an accurate estimate of the distance to the Coma cluster (and therefore H0). A single galaxy could be on the backside of the cluster and not representative of the mean cluster distance. And that is why I say their SBF determination of H0 is irrelevant.

You want to accuse me of misleading the BAUT readers??? That is something I take offense to!!! People may disagree with me and as with everybody I'm occasionally wrong or unware of other relevant results. But I do not appreciate being accused of intentionally misleading.

You seem to be claiming expertise here - surely you must know that a single distance estimate to a cluster is very risky because the galaxy in question may be on the front or backside of the cluster? Any H0 estimate from a single galaxy in a cluster should not be trusted - no matter how small the systematics of the method of finding distance. Should I claim you are misleading BAUT readers by failing to note/acknowledge this flaw in the HKP SBF sample size?

Now that is part of what we're discussing. The van Leeuwen study is one example of what you've mentioned here. They find a much closer agreement between the maser distance and the cepheid distance than the HKP found. But they revise the cepheid zero point which pushes the HKP H0 estimate to 76 and would push the Tully&Pierce H0 estimate to 81.

There is also the result of An et al that suggests a slightly larger downward revision in the distance scale than found by van Leeuwen et al.

Did you have specific studies in mind? You're the one that made the statement. Why should I try and guess which study(s) you meant? If you want to contribute something substantive to the discussion how about linking to the papers.

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"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

An ADS search from 2001 to present using the Keywords "Virgo cluster distance" gives over 200 hits. It looks like one of those is a SBF distance study that finds a mean distance of 16.5 Mpc.

The same search for Fornax gives 85 hits. For Leo I there is a handful of hits but nothing relevant to our discussion that I noted. Again it would be helpful if you would provide specific studies.

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"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

And from the latest paper submitted upon LMC distance:

THE DISTANCES TO OPEN CLUSTERS FROM MAIN-SEQUENCE FITTING. IV.
GALACTIC CEPHEIDS, THE LMC, AND THE LOCAL DISTANCE SCALE

http://arxiv.org/PS_cache/arxiv/pdf/...707.3144v1.pdf

Keep in mind this is an absolute error in the Hubble value driven by baseline constraints. There are also possible systemics in the Supernovae observations I mentioned above, which would be additive, and beyond the 0.15m limits upon supernova luminosities used in error estimates by HKP.

DT&P claims to be consistent with the maser results, and pushes the value of Ho to 79 without even touching the supernovae-derived curve. Whether it could be even higher or not is not limited by current observationally-derived limits, but theoretical challenges imposed by higher numbers.

(I don't have a preferred value for what Ho is or should be, but I will admit I like theoretically challenging observational data!)

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jwj

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

First dgruss wrote:

I attempted to address his claim that "most people have accepted H0=72":

The reply:

??

I guess you're more interested in semantic games than science.

Actually, I hate semantic games. I'd much prefer to talk about the science. And I think I've addressed more science than anyone on this thread. Your comment had nothing to do with the science I've discussed. Of all the points I've made dealing with the HKP final results and other papers, you choose to respond to none of that, but a statement I made about what people think - most "people" having accepted H0=72? And then you tell me I'm not interested in science??

Do you understand why I responded as I did to your post? Apparently not so let me be more specific.

Your explanation about the use of "h" and the adoption of H0=70 for ease of comparison is nothing new to me. I've read enough papers to be familiar with both those points and published my own work in ApJ. Your comments about "h" and the like are very basic applications that anyone who has published research on the distance scale should be familiar with. So I was attempting to save you the trouble of lecturing me about such basics by letting you know that I have enough background to be familiar with that type of information. However, as an independent researcher I wouldn't want to be so bold as to call myself an "astronomer". After all, astronomers have training I don't have and access to resources I don't have access to. I didn't want the fact that I've published a few papers to lead to an incorrect inference that I've got a PhD in astrophysics or am claiming to have expertise I don't have.

So what you are characterizing as a "semantic game" was actually my attempt to give you a little more background about myself so you have a better frame of reference when you respond to my posts. I'm not employed as an astronomer, but I'm not your typical poster here either. I thought it might save you some time to have that information ... that's all.

Seriously, I hate the semantic games. It frustrates me that I attempt to discuss evidence and zahl tells me I'm attempting to mislead BAUT members and then you tell me I'm playing semantic games. However, if some people wish to play semantic games, I'll do so in the interest of trying to move the discussion back to the science. Sometimes you have to get people past the semantics before you can discuss the science.

Ok, let me try again. I'm sorry that you feel I didn't respond appropriately to this part of your comments. And I'm being serious, not sarcastic in what follows:

That's great to know! So if we take your experience as a correct representation of what most astronomers would think, then the problem would seem to be that this understanding is lost in translation when the information is communicated to laymen? We have two populations here - researchers and laymen.

The comments so far on this thread suggest that most people that have responded think that it is unlikely that H0 could be in the 80's based upon the fact that most studies (or at least reported in popular literature I guess) find H0 ~ 70.

In this thread I've pointed to a few reasons to be cautious about the HKP final results and why it is still a viable possibility that H0 could be in the 80's. You can see my earlier posts for those reasons. But then based upon what you're saying, if evidence was presented that H0 is in the 80's most astronomers would not simply brush that aside by assuming that the researchers in question must have done something wrong because most studies point to lower H0 and WMAP results and concordance cosmology ... They would at least look carefully at the analysis?

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"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

Yes. In fact, what you write above is ignorant nonsense. When finding h₀ with the Surface Brightness Fluctuations method a distance is determined to a galaxy (not cluster) by measuring SBF in that galaxy and finding a Cepheid in that galaxy for calibration. Redshift is then found and h₀ calculated. There is no need for the SBF galaxy to be representative of the mean cluster distance. Now, anybody reading this and wondering what to believe - ask yourselves if the authors and the referee of one of the most important and heavily cited papers in the business had "irrelevant" results published because of a trivial error ("only 6 galaxies for their SBF analysis") or if some poster on an internet forum doesn't know what the heck he is talking about.

77, not 79. And it was +7%±8% so the increase is not even statistically significant.

My comments are for everyone following this discussion. And first, if you do a search on Zahl's posting history you'll note that he is quite liberal with telling people they're ignorant or don't know what they're talking about - even KenG who has demonstrated himself to be very knowledgeable.

For the sake of clarity, here is what Zahl is claimed I've said that is ignorant nonsense:

The point I've made is that for the SBF and Type II supernova H0 estimates, the HKP used a limited number of galaxies (6 and 4 respectively) - which is not enough to determine H0.

However, zahl's understanding of what the HKP did is different:

So zahl claims here that the HKP did not use one galaxy per cluster as I have stated. He is wrong. Here is what the HKP did:

1. They derived the SBF zero point by using local calibrators with cepheid distances.

2. They utilized SBF measurements to the brightest cluster galaxy (BCG) in 6 clusters assuming that the BCG is at the mean cluster distance.

3. They used a larger sample of galaxies within the cluster to determine the mean cluster redshift.

4. They calculated H0 by dividing the mean cluster redshift by the SBF distance to the BCG.

As I said - 6 galaxies were used in 6 clusters. Now unlike zahl, I'll actually link to papers to support what I state instead of just lazily accusing people of being ignorant.

Here is the paper in which the HKP initially presented their SBF analysis. The calibration of the SBF method is discussed in section 6 and its application to H0 is discussed in section 8. For those that don't want to read the technical discussion in the paper you need look no farther than Table 4 in the paper. The table is titled "Sample of F814W-SBF Galaxies for Deriving H0". The first data column is titled "Cluster". The second column is titled "Galaxy ID". Note there are only 6 galaxies listed in Table 4 -- one galaxy for each cluster.

Now the HKP did here the next best thing to have a sample of multiple galaxies per cluster. They selected the BCG - which might fairly be assumed to be at the cluster center. However, we can see that Zahl was flat out wrong - the HKP did use a single galaxy to represent the mean cluster distance for 6 clusters.

The HKP final results are presented in this paper . If you look at sections 6.4 and Table 10 you'll see the same 6 galaxies with SBF distances listed as Table 4 of the previous paper. In section 6.4 the following is stated:

I'm not sure how Zahl missed this. If he wants to tell me I'm "ignorant" one would think he would have read the relevant papers closely enough to be certain about that. One should not be so careless when leveling accusations of "ignorance". It makes one look quite foolish when they are so easily shown to be wrong in their proclamation.

I stand by what I've said in this thread. The HKP sample sizes for the SBF method and Type II SN are too small.

I think the lesson for BAUT readers is that you should not trust someone that so willingly accuses others of ignorance when they refuse to link to a single paper. We can now see that in fact the referee's did allow a SBF analysis with only 6 galaxies to be published. I'm not saying they were wrong to allow it to be published. My point is that the sample is too small to be truly relevant support for H0=70. And it is not as if the HKP workers are not aware that more work is needed. Ferrarese et al (2000 - linked to above) noted that more SBF work is needed at the end of section 6 of their paper:

Speaking of the slope of the color dependence they said this in the preceding paragraph:

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"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

Yes, I agree that this is the main issue. It is difficult to write a successful article for the popular press without simplifying, or over-simplifying.

I agree with you. It is possible that H0 could be in the 80s. Unlikely, in my opinion, with the current weight of evidence against it, but possible.

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.

A shift in the baseline is always significant. In this case, it 'formally' rules out values of the Hubble constant less than 69, and 'formally' increases the range of likely Hubble values to 85.

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.

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jwj

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