Is the Conventional Wisdom About the Universe Wrong?

[wolram]

http://www.sciencedaily.com/releases/2010/06/100613212708.htm

ScienceDaily (June 14, 2010) — New research by astronomers in the Physics Department at Durham University suggests that the conventional wisdom about the content of the Universe may be wrong.

Although at the bottom of the page he says (standard model may survive).

 

[bapowell]

This appears to be a criticism of the techniques used by the WMAP team to perform beam smoothing. The claim is that the technique used might adversely effect the resolution of the CMB measurements, widening the errors. If this does turn out to be the case (I would personally be interested in hearing what the WMAP science team has to say about it before making a conclusion), then the result would be that the error bars on the temperature spectrum of the CMB would widen, allowing more different kinds of models to be in agreement with data. The old standard model would certainly survive: if it fits the data now with smaller error bars, it will still fit it if these error bars widen (unless they do so in some asymmetric fashion). We should stay tuned and see what comes of this.

 

[nicksauce]

While it would be very interesting if wmap's accuracy was different than previously thought, the reaction to this I've seen on the internet has been "OMG dark matter and dark energy don't exist anymore", and it is very annoying. The press releases given by the authors aren't helping either. This is interesting, but it is also important to separate fact from fiction.

 

[bapowell]

While it would be very interesting if wmap's accuracy was different than previously thought, the reaction to this I've seen on the internet has been "OMG dark matter and dark energy don't exist anymore", and it is very annoying. The press releases given by the authors aren't helping either. This is interesting, but it is also important to separate fact from fiction.

Yes, I think it's very important to stress that there is no reason to expect that models that fit current data won't, for some reason, fit the same data with larger errors. Of course, the data could get so bad that you no longer need CDM or dark energy to fit CMB data (that would be hard to imagine), but even then, we have complementary astrophysical data that still supports these models.

 

[George Jones]

The press releases given by the authors aren't helping either.

Were the press releases written by the authors, or by PR people at the university?

 

[nicksauce]

Were the press releases written by the authors, or by PR people at the university?

Well,

Prof. Shanks comments "CMB observations are a powerful tool for cosmology and it is vital to check for systematic effects. If our results prove correct then it will become less likely that dark energy and exotic dark matter particles dominate the Universe. So the evidence that the Universe has a 'Dark Side' will weaken!"

This seems like an overstatement of the case. For all they know, the constraints could change hardly at all. I think they should wait until wmap data is analyzed with a revised error estimate before making a statement like this.

 

[Chalnoth]

I sincerely doubt it'd make much of any difference, as most of the effects of the beam smoothing would be on the third harmonic peak, where with WMAP the dark energy signal is primarily at very low mulipoles and at the first harmonic peak, while the dark matter signal is primarily from the ratio of the first and second harmonic peaks.

Improving the beam smoothing in WMAP data would slightly improve the error estimates and values, but I don't buy for an instant that it would significantly change any conclusions about dark matter or dark energy. The most it might potentially do is change the constraints on some of the inflation parameters, but then that was at the limit of detection with WMAP anyway.

 

[Chronos]

I think dark matter is safe for now. There is plenty of other evidence that gives it legs aside from WMAP.

 

[Saul]

http://www.sciencedaily.com/releases/2010/06/100613212708.htm

ScienceDaily (June 14, 2010) — New research by astronomers in the Physics Department at Durham University suggests that the conventional wisdom about the content of the Universe may be wrong.

Although at the bottom of the page he says (standard model may survive).

If you read Shanks' other papers, he questions the scientific validity of cosmological constant tuning, inflation, dark matter, and dark energy. The evidence at this point in time is indicating dark matter will not survive.

I believe his comment means he believes some version of the big bang theory will survive (i.e. he is not challenging the foundation of the theory) and in the specific case of his paper concerning the CMB calculation he is also appropriately and politely leaving himself a way out if his paper is challenged and shown to be incorrect.

 

[Chalnoth]

If you read Shanks' other papers, he questions the scientific validity of cosmological constant tuning, inflation, dark matter, and dark energy. The evidence at this point in time is indicating dark matter will not survive.

Yeah, sounds like he's off his rocker. Dark matter, in particular, is strongly evidenced by a wide body of mutually-corroborating evidence. Yes, there are a small number of cosmologists/astrophysicists who continue to claim that dark matter is bunk, and a slightly larger number who rail against dark energy. A few of the ones who rail against dark energy (such as Rocky Kolb) are, in my opinion, quite good scientists. But most of the rest, and especially those who are fighting dark matter, seem to me to have gone the way of Halton Arp and Fred Hoyle.

I really don't understand why it happens, but for some reason many formerly very good scientists occasionally turn crackpot. At this point, the evidence for dark matter, for instance, is just far too strong. Especially when the primary arguments against it (and against dark energy) are not evidence-based but philosophical.

Here is the basic, basic problem: when cosmologists cite the evidence of dark matter, they don't cite any one, single discovery. They cite a wide array of mutually-corroborating pieces of evidence. Those arguing against it typically point at this one little discovery over here, or that one over there, and then proceed to use a very weak argument in an attempt to show that it doesn't work. The rest of us just say, "Yeah, not only is that a weak argument, but we've also got this and this and that and that over there."

It doesn't help that the stated reasons for arguing against dark matter and dark energy are ridiculous in the first place.

 

[Saul]

Let’s backup and summarize. What do we agree on? What are the different logical possibilities?

This is a summary of the Sawangwit and Shanks paper.

http://www.sciencedaily.com/releases/2010/06/100613212708.htm

Sawangwit and Shanks used astronomical objects that appear as unresolved points in radio telescopes to test the way the WMAP telescope smoothes out its maps. They find that the smoothing is much larger than previously believed, suggesting that its measurement of the size of the CMBR ripples is not as accurate as was thought. If true this could mean that the ripples are significantly smaller, which could imply that dark matter and dark energy are not present after all.

This a link to a specialists forum where another specialist in CMB interpretation discusses the Sawangwit and Shanks paper with Sawangwit and Shanks and other CMB specialists.

http://telescoper.wordpress.com/2010/06/14/cosmology-on-its-beam-ends/

Read and think about what the authors and other specialists are saying.

(This is a link to the two Sawangwit and Shanks papers.)

http://arxiv.org/PS_cache/arxiv/pdf/0912/0912.0524v2.pdf

http://arxiv.org/PS_cache/arxiv/pdf/1006/1006.1270v1.pdf

The CMB specialists are stating there is evidence as the original WMAP team knew what resultant they wanted to match the dark matter and dark energy ΛCDM predicted curve they used observations of Jupiter rather than a distant object to calibrate their data.

(The specialists noted that in past when everyone thought a theory was correct data was interpreted to support the theory in question. When it became evident the theory in question was incorrect, people found errors in the original assumptions and analysis. i.e. Scientists are human and will from time to time unknowingly curve fit the analysis to fit the prediction.)

If one uses a distance object (Sawangwit and Shanks used multiple distance objects) the resultant is roughly 30% less which no longer supports the existence of dark matter and dark energy. The specialists are stating that the CMB resultant with the beam correction, no longer supports the existence of dark matter and dark energy.

One more time. No longer supports the existence of dark matter and dark energy. Is that statement correct? Yes or no?

What do we know and what do we not know?

There are a number of anomalous observations that require a physical explanation. I believe we all agree. Yes or no? (For example, the anomalous rotational velocities of spiral galaxies.)

That fact does not mean dark matter and dark energy exist. Dark matter and dark energy are hypothesized physical entities. Anomalous observations that require a physical explanation cannot be used as support for the existence of dark matter and dark energy. Dark matter and dark energy are called dark matter and dark energy as they are placeholders for a physical mechanism to explain the observations.

Logical proof of the existence of dark matter and dark energy requires specific observational data than can only be explained by dark matter and dark energy. What has been found is that observational data of galaxies does agree with dark matter predictions. If someone disagrees with that statement they need to provide specific observational data and papers that specifically supports the existence of dark matter and dark energy.

The statement that there is plenty of other evidence to support the existence of dark matter and dark energy is an empty statement without proof. There is nothing to discuss, refute, or defend.

My point is Sawangwit and Shanks’ finding, the Zenon (the most sensitive dark matter detection device every made.) negative finding for direct detection of dark matter, the spiral galaxy morphological observational disagreement between prediction and observation, the spiral galaxy rotational disagreement between prediction and observation, the number of satellite galaxies disagreement between prediction and observation indicates that the field must now start looking at other explanations for what is observed than dark matter and dark energy.

It is very possible now based on analysis and observation that dark matter and dark energy does not exist.

If dark matter and dark energy does not exist, the anomalous observations still requires a physical explanation.

 

[Chalnoth]

Er, with WMAP's smallest beam size at 13 arc minutes, and with Jupiter having an angular size of about half an arc minute, a 30% overestimation of the beam size due to Jupiter not being a perfect point source isn't really plausible.

And besides, as I've stated previously, it wouldn't change the WMAP results in the way suggested anyway.

One more time. No longer supports the existence of dark matter and dark energy. Is that statement correct? Yes or no?

That statement is completely wrong.

 

[bapowell]

If one uses a distance object (Sawangwit and Shanks used multiple distance objects) the resultant is roughly 30% less which no longer supports the existence of dark matter and dark energy. The specialists are stating that the CMB resultant with the beam correction, no longer supports the existence of dark matter and dark energy.

One more time. No longer supports the existence of dark matter and dark energy. Is that statement correct? Yes or no?

A couple things worth pointing out. 1) Sawangwit and Shanks make no mention about what their results mean for dark matter/dark energy. This appears to be purely sensationalist hype generated by the pop-science media. People who make such claims lack an understanding of how cosmological parameters are derived from cosmological data. 2) No, it doesn't support that. At least nobody's shown this. With regards to the statement you quote, "If true this could mean that the ripples are significantly smaller, which could imply that dark matter and dark energy are not present after all.", I don't even know what that means. The effect of dark energy on the CMB has to do with the position of the first acoustic peak and the increase in power at low-l. Neither of these observations should be directly effected by making the "ripples smaller". The effect of DM is more directly related to the peaks -- in particular, the relative amplitudes of the 1st and 2nd peaks; and so of course there's a chance that the conclusions we draw from the CMB with regards to DM might be affected! We should absolutely investigate this! But nobody's done that yet, so we should cool it. Lastly, why is everyone acting like the only piece of scientific evidence for DM/DE comes from the CMB? It doesn't. If the CMB didn't exist, our evidence for DM/DE would weaken, but there are other astrophysical sources. This is a classic case of cherry-picking the data that supports the point. That's bad science and people should be called out on it.

There are a number of anomalous observations that require a physical explanation. I believe we all agree. Yes or no? (For example, the anomalous rotational velocities of spiral galaxies.)

That fact does not mean dark matter and dark energy exist. Dark matter and dark energy are hypothesized physical entities. Anomalous observations that require a physical explanation cannot be used as support for the existence of dark matter and dark energy. Dark matter and dark energy are called dark matter and dark energy as they are placeholders for a physical mechanism to explain the observations.

Wait...so you're using semantics to discount the physical validity of the concepts of dark matter and dark energy? I don't follow. Of course DM/DE are hypothetical entities -- all such physical explanations for a collection of phenomena are hypotheses until sufficient data accumulates to accept them into a theory. The underlying physics from which DM/DE arise is not fully understood -- hence the funny language. However, the hypothesis that particulate dark matter exists (a suggestion pretty well founded in modest extensions of the standard model of particle physics, and well accommodated as a cold thermal relic in the early universe) is reasonably well motivated. So far, its predictions agree well with cosmological observations. Will such a hypothesis stand up to all observations?? Probably not -- few do. Nobody should be claiming we have all the answers, we don't. As for dark energy, the proposition that vacuum energy gravitates is a reasonable hypothesis. The observational consequences of such a hypothesis are well supported by data (SN data, ISW, flat universe).

Logical proof of the existence of dark matter and dark energy requires specific observational data than can only be explained by dark matter and dark energy.

Sorry, but that's not how science works. Physics is an empirical science, and as such, we don't have the luxury of formulating 'logical proofs' of phenomena. Surely you know that science as a framework is not meant to prove things. In science, one should propose a hypothesis and work out its predictions. These predictions should be matched against data. Competing hypotheses should be compared. At the end of the day, all we can do is make inferences, and choose the model that is statistically favored by the data. If there are other theories that compete with DM/DE, they should be (and are) considered.

The statement that there is plenty of other evidence to support the existence of dark matter and dark energy is an empty statement without proof. There is nothing to discuss, refute, or defend.

Does the act of citing these additional sources of evidence constitute 'proof'? There are plenty.

My point is Sawangwit and Shanks’ finding, the Zenon (the most sensitive dark matter detection device every made.) negative finding for direct detection of dark matter, the spiral galaxy morphological observational disagreement between prediction and observation, the spiral galaxy rotational disagreement between prediction and observation, the number of satellite galaxies disagreement between prediction and observation indicates that the field must now start looking at other explanations for what is observed than dark matter and dark energy.

These should be investigated. But is dark matter not capable of being adjusted to accommodate these new findings? How statistically relevant are these new findings anyway (compared to, say, CMB and LSS data)? That's important. Also, what do any of the things you listed have to do with dark energy? Just because they share the word "dark" doesn't mean that the possible refutation of one has anything to do with the other.

It is very possible now based on analysis and observation that dark matter and dark energy does not exist.

Maybe. So let's do the analysis.

If dark matter and dark energy does not exist, the anomalous observations still requires a physical explanation.

Yes, and science will march on.

 

[Chalnoth]

The effect of DM is more directly related to the peaks -- in particular, the relative amplitudes of the 1st and 2nd peaks; and so of course there's a chance that the conclusions we draw from the CMB with regards to DM might be affected! We should absolutely investigate this!

I doubt it. Basically, these sorts of issues tend to fix things in the low signal-to-noise regime, which would likely mean a fix on the amplitude of the third acoustic peak, which wouldn't significantly impact the dark matter results.

The fundamental reason why they tend to fix things in the low signal-to-noise regime is because in the high signal-to-noise regime multiple cross-checks of the results are available, and WMAP has consistently and repeatedly passed these cross-checks (edit: well, not always. Every once in a while somebody finds an issue, but it's always turned out to be relatively minor).

 

[bapowell]

Thanks Chalnoth, apologies. By the way...shouldn't BAO data serve as a valuable cross-check here? I mean...the ripples are there too...in like...the exact same places.

 

[Chalnoth]

Thanks Chalnoth, apologies. By the way...shouldn't BAO data serve as a valuable cross-check here? I mean...the ripples are there too...in like...the exact same places.

Well, BAO isn't my field of expertise, but my suspicion is that no, it wouldn't, because a modification of the beam would change the amplitudes of the peaks, not their positions, while from what I understand the BAO data is most sensitive as a measurement of the position, not the amplitude.

Anyway, as I said previously, I think the most significant changes would be in the measured values of inflation parameters such as the spectral index.

Edit, small caveat: changing the amplitudes of peaks will, in general, slightly adjust their positions, but usually much less than the change in amplitude itself.

 

[Saul]

Sorry, but that's not how science works. Physics is an empirical science, and as such, we don't have the luxury of formulating 'logical proofs' of phenomena. Surely you know that science as a framework is not meant to prove things. In science, one should propose a hypothesis and work out its predictions. These predictions should be matched against data. Competing hypotheses should be compared. At the end of the day, all we can do is make inferences, and choose the model that is statistically favored by the data. If there are other theories that compete with DM/DE, they should be (and are) considered.


Does the act of citing these additional sources of evidence constitute 'proof'? There are plenty.

If you could site a paper that has proof of dark matter and dark energy, then we will have something to discuss.

I have sited papers that shows observed spiral galaxy morphology does not agree with dark matter predictions, that observed spiral galaxy radial velocity profile does not agree with dark matter predictions, and that the observed number of satellite galaxies does not agree with dark matter predictions. Three strikes and you are out?

I have sited the xenon paper that notes the most sensitive dark matter detection experiment has not detected dark matter.

The scientific observations and analysis in published papers does not support the existence of dark matter. If you have any specific data and analysis that supports dark matter start a thread. I would be interested in discussing it.

Anomalous observations that currently do not have an explanation does not proof dark matter exists and is that it is the cause of the anomalous observations. The papers I have sited show dark matter is logically not the cause, in the thread "Dark Matter, On the Ropes?" in the astrophysics section.

That is how science works.

People come up with hypothesis and then test the hypothesis against its predictions. When the hypothesis fails against multiple predictions, which is what has happened in this case, it is back to drawing board.

 

[bapowell]

Are you seriously suggesting that there are no studies that support the existence of dark matter? People in this thread and elsewhere all over this forum have discussed these additional pieces of evidence at length. If you wish to learn about them, you simply need to go and look. I addressed the individual pieces of evidence that you list here...any thoughts on what I wrote? You do not appear to be approaching this problem with an open mind, since you are deliberately neglecting data that supports dark matter. I think you should admit that you probably have a personal, not necessarily scientifically derived, aversion to dark matter, and it really appears to be clouding your judgment. As a result, I don't think there's much point in continuing a scientific discussion on these topics.

And again, science can't prove things. And again, you keep bringing up observations that disagree with current models of dark matter -- you haven't mentioned a single contention with dark energy, yet you keep including it in the discussion. So as not waste my time listing all the sources of evidence for DM/DE, I'll list one and see how you digest it: how about the SN1a data from Riess et al http://arxiv.org/abs/astro-ph/9805201 and Perlmutter et al http://arxiv.org/abs/astro-ph/9812133 .

EDIT: Also, your rail against dark matter has really taken us far away from the intent of the thread, which was to discuss the findings of Sawangwit and Shanks. I think that has been satisfactorily addressed by people in this thread.

 

[Chalnoth]

If you could site a paper that has proof of dark matter and dark energy, then we will have something to discuss.

I have sited papers that shows observed spiral galaxy morphology does not agree with dark matter predictions, that observed spiral galaxy radial velocity profile does not agree with dark matter predictions, and that the observed number of satellite galaxies does not agree with dark matter predictions. Three strikes and you are out?

I have sited the xenon paper that notes the most sensitive dark matter detection experiment has not detected dark matter.

The scientific observations and analysis in published papers does not support the existence of dark matter. If you have any specific data and analysis that supports dark matter start a thread. I would be interested in discussing it.

Anomalous observations that currently do not have an explanation does not proof dark matter exists and is that it is the cause of the anomalous observations. The papers I have sited show dark matter is logically not the cause, in the thread "Dark Matter, On the Ropes?" in the astrophysics section.

That is how science works.

People come up with hypothesis and then test the hypothesis against its predictions. When the hypothesis fails against multiple predictions, which is what has happened in this case, it is back to drawing board.

Wow. Just wow. Dark matter, in particular, is strongly supported by a wide body of evidence. Studies of galaxy clusters, the CMB, and baryon acoustic oscillations are particularly telling. Discrepancies in much more complex systems, such as individual galaxies, are more likely telling us something interesting about galaxies themselves instead of about dark matter. Larger systems tend to be less sensitive to these complexities, and are thus much better evidence for dark matter.

Dark energy is less well-evidenced, but the alternative explanations are getting increasingly ridiculous.

 

[Saul]

Are you seriously suggesting that there are no studies that support the existence of dark matter? People in this thread and elsewhere all over this forum have discussed these additional pieces of evidence at length.

And again, science can't prove things. And again, you keep bringing up observations that disagree with current models of dark matter -- you haven't mentioned a single contention with dark energy, yet you keep including it in the discussion. So as not waste my time listing all the sources of evidence for DM/DE, I'll list one and see how you digest it: how about the SN1a data from Riess et al http://arxiv.org/abs/astro-ph/9805201 and Perlmutter et al http://arxiv.org/abs/astro-ph/9812133 .

EDIT: Also, your rail against dark matter has really taken us far away from the intent of the thread, which was to discuss the findings of Sawangwit and Shanks. I think that has been satisfactorily addressed by people in this thread.

There are two paper sited in your comment to support the existence of dark matter and dark energy.

One paper that has observational data the universe is accelerating. Yes the universe is is accelerating however that does not prove dark energy is the cause.

The second paper, is somewhat better. It is a 1998 paper that uses supernova data to support the total amount of energy and mass in the standard model. That does not prove dark energy or dark matter exist.

Subsequent papers on supernova analysis has questioned the accuracy of the supernova explosion that is used for the standard candle.

Now back to the Shanks' paper.

I noticed no one was commented on the discussion by the authors and the specialists themselves on this subject. They appear to be senior scientists with many years experience in the field. Name calling and adjectives does not prove a point.

http://telescoper.wordpress.com/2010/06/14/cosmology-on-its-beam-ends/

The Shanks' paper shows problems in the CMB interpretation which removes the last pillar that was purported to support dark matter.

Believe whatever you want. Understanding the cosmological problems that are and are not solved is a fundamental part of what the practice of science is. (i.e.That is why Shanks' wrote the paper.)

Think of the issue in another way. What is or is not correct does not change. If dark matter does not exist, cosmology is on hold until observation data and analysis in papers such as Shanks, and the papers noted in Dark Matter, On the Ropes? are written.

20 years ago people did not know that the xenon experiment would give negative detection for dark matter, that observed spiral galaxy morphology does not agree with dark matter predictions, that spiral rotational velocity does not agree with dark matter predictions, that the number of observed satellite galaxies does not agree with dark matter predictions.

Let's wait for new data and new papers to discuss.

 

[Chalnoth]

Saul, really, science doesn't deal in proof.

As for the rest of the points you've raised, well, none of them noticeably impact the conclusion that dark matter exists, or that the expansion of the universe is accelerating. You can't go from, "Well, look, this particular experimental result has an error that may shift the measured abundance of dark matter by 0.5 standard deviations," to the conclusion that it's all bunk.

 

[bapowell]

I noticed no one was commented on the discussion by the authors and the specialists themselves on this subject. They appear to be senior scientists with many years experience in the field. Name calling and adjectives does not prove a point.

I read it, nothing to comment on. It was an interesting discussion, with some good input from people whom also disagree with some of the conclusions drawn from the analysis. As I've said before, I think it's important to investigate this further.

The Shanks' paper shows problems in the CMB interpretation which removes the last pillar that was purported to support dark matter.

No it doesn't. They have not shown this. Did you read the paper? They mention specifically at the end of the paper, "It will be interesting to see if a revised estimate of the WMAP beam profile then allows a simpler cosmological model to be fitted than LCDM." THEY HAVE NOT DONE THE ANALYSIS YET! Also, it makes little sense to compare their data with the LCDM concordance model as obtained by the WMAP team using the original data. What one needs to do is reperform the parameter estimation from scratch using the new data, and see what happens to the parameters $$\Omega_{CDM}$$ and $$\Omega_\Lambda$$. What people have been suggesting in this thread, and what you have routinely ignored, is that any change is expected to be small. Why not simply wait until more analysis can be done before drawing sweeping conclusions and saying things like the "last pillar" of evidence for DM/DE has been obliterated by these recent findings. They haven't and to say they have is dishonest.

 

[Saul]

There are two paper concerning alleged CMB calibration error.

If you check figure 1 in the second paper it shows the raw CMB data from WMAP and then shows how much it was adjusted based on measurements of Jupiter. When a distance source is used for calibration both the amplitude and position of the first CMB peak changes.

http://arxiv.org/PS_cache/arxiv/pdf/1006/1006.1270v1.pdf

ΛCDM and the WMAP power spectrum beam profile sensitivity

We first discuss the sensitivity of the WMAP CMB power spectrum to systematic errors by calculating the raw CMB power spectrum from WMAP data. We find that the power spectrum is surprisingly sensitive to the WMAP radiometer beam profile even at the position of the first acoustic peak on approx. 1 degree scales. Although the WMAP beam profile core is only 12.06 FWHM at W, there is a long power-law tail to the beam due to side-lobes and this causes significant effects even at the first peak position. We then test the form of the beam-profile used by the WMAP team which is based on observations of Jupiter.

Finally, we show that the uncertainty in the WMAP beam profile allows the position as well as the amplitude of the first peak to be changed and how this could allow simpler cosmologies than standard ΛCDM to fit the CMB data.

Figure 1: The red line shows the raw WMAP W band power spectrum estimated from the cross-correlation of the WMAP5 W1 and W2 maps. The blue diamonds + line shows the final WMAP5 spectrum after ‘de-beaming’ using the Jupiter beam( +‘cut-sky’ correction). The large effect of de-beaming even at the first acoustic peak (apprxo.. 1deg) is caused by beam sidelobes, even though the beam’s Gaussian core has a width of only 12.06 FWHM.

The discovery of observational anomalies does not prove the existence of dark matter. The word dark is applied when astrophysicists do not know what is causing the anomalous observations.

For example dark energy.

There are three parts to the process to resolve the anomalies. The first is to confirm the anomalous observations are real. Could the observations be due to something else such as incorrect assumptions, instrumentation error, or due selection errors?

The second part is a search for more information about the anomalous observations to determine its cause. Do all galaxies exhibit the anomaly?

The third step is develop logical arguments with an analysis of observational data and simulations that support or do not support the mechanism which it hypothesized is causing the anomalies. Note in the case of this problem there is a whole set of anomalous observations to explain.

 

[Chalnoth]

Yeah, they seriously attempted to fit their data with an $\Omega_b=1$ model? Wow. That's pretty absurd. I'll note that in order to get this model to work, they have to use a value of $H_0$ which is approximately half the value we measure using other experiments.

Never mind that they didn't bother to compare their power spectrum to WMAP's power spectrum.

 

[Saul]

Yeah, they seriously attempted to fit their data with an $\Omega_b=1$ model? Wow. That's pretty absurd. I'll note that in order to get this model to work, they have to use a value of $H_0$ which is approximately half the value we measure using other experiments.

Never mind that they didn't bother to compare their power spectrum to WMAP's power spectrum.

I suppose you missed the new paper discussing problems with the supernova standard candle.

The Shanks et al's CMB paper is significant as it comes at time when there are other related papers that challenge what was once assumed were pillars of the theory.

 

[Chalnoth]

I suppose you missed the new paper discussing problems with the supernova standard candle.

Huh? $H_0$ isn't measured via supernovae (it's completely degenerate with their intrinsic brightness). What are you talking about?

The Shanks et al's CMB paper is significant as it comes at time when there are other related papers that challenge what was once assumed were pillars of the theory.

Yeah, no, not going to change anything. It basically can't because the CMB power spectrum is already tightly-constrained by a large number of experiments besides WMAP.

 

[Saul]

Huh? $H_0$ isn't measured via supernovae (it's completely degenerate with their intrinsic brightness). What are you talking about?

Start a thread if you would like to discuss how Ho is determined. We could also in that thread discuss how supernova are used to a calibrate distances. The discovery is of supernova that are anomalous bright.

Yeah, no, not going to change anything. It basically can't because the CMB power spectrum is already tightly-constrained by a large number of experiments besides WMAP.

If you want to make a point quote a paper with specific observational data that supports your point. (i.e. Non CMB analysis.) I have quoted a paper that refutes the WMAP analysis. As the authors of that paper noted they are waiting for an explanation of their results.

I note that I have quoted a series of papers that show the dark matter hypothesis cannot explain fundamental spiral galaxy parameters such as their rotational velocity change with radius and the size of the spiral galaxy's bulge. There are other dark matter problems such as the dark matter simulation prediction that the number of dwarf galaxies should be greater by a factor of 10 from what is observed.

You response was the unscientific galaxy simulation is complicate with an appeal to more effort solving the simulation paradoxes. Logically the explanation could also be that dark matter does not exist. I also quoted the Xenon paper that notes the most sensitive dark matter detector on the planet has not detected dark matter.

Those papers and the above CMB calibration paper indicate the dark matter hypothesis is in trouble.

The new Planck satellite data and analysis will be interesting. I have heard that the axis of evil and the cold spot remain.

The authors of the CMB error paper note it is possible to calibrate the CMB data such that it closes matches the theoretical predictions. If people believe a theory is correct there is a natural human tenacity to do just that.

Did you look at figure 1 in their paper that shows how much the CMB raw data was adjusted?


http://en.wikipedia.org/wiki/Planck_( spacecraft )

 

[Chalnoth]

If you want to make a point quote a paper with specific observational data that supports your point. (i.e. Non CMB analysis.) I have quoted a paper that refutes the WMAP analysis. As the authors of that paper noted they are waiting for an explanation of their results.

You cited no paper which refutes any of the science results of WMAP. The one paper which you did cite claims to show that the true beam is different from the WMAP-estimated beam. But they didn't do any actual analysis on the power spectrum to show what this different beam would mean. They make some hand-wavy comparison to a universe with $\Omega_b = 1$, but that can be safely discarded as being ridiculous, in part because the measured value of $H_0$ is nowhere near $35km/s/Mpc$.

I note that I have quoted a series of papers that show the dark matter hypothesis cannot explain fundamental spiral galaxy parameters such as their rotational velocity change with radius and the size of the spiral galaxy's bulge.

The fundamental problem here is that you have two main things that could be mistaken: the model of the galaxy/galaxy formation, or our understanding of fundamental physics (the amount and nature of dark matter is ultimately a question of fundamental physics). Because the evidence for dark matter is quite clear and unambiguous in situations where we are much more confident of the physical systems in question, the smart money is on the model of the galaxies/galaxy formation being wrong.

There are other dark matter problems such as the dark matter simulation prediction that the number of dwarf galaxies should be greater by a factor of 10 from what is observed.

Which could also be a problem with the observations (dwarf galaxies are extremely faint, some have been detected with mass-to-light ratios as high as 1000), or a problem with the simulations (tidal stripping has been proposed as a mechanism for larger galaxies to "eat" dwarf galaxies).

The path of this conversation is absolutely clear. You don't like dark matter. You don't think it exists. So you're going to pull out every discrepancy, every finding that somehow might be construed as not showing dark matter, and claim it's a demonstration it doesn't exist.

Sorry, but you're flat-wrong. A wide variety of mutually-independent observations strongly and conclusively confirm the existence of dark matter. You have shown nothing that casts any doubt on that.

Did you look at figure 1 in their paper that shows how much the CMB raw data was adjusted?

That's, uh, not what you think it is. That's just a plot showing how the beam correction changes the estimate of the power spectrum. That is not a plot comparing their analysis to WMAP's analysis.

http://en.wikipedia.org/wiki/Planck_( spacecraft )

Why is this URL randomly at the bottom of your post? Did you intend to say something about the Planck satellite?

 

[bapowell]

The path of this conversation is absolutely clear. You don't like dark matter. You don't think it exists. So you're going to pull out every discrepancy, every finding that somehow might be construed as not showing dark matter, and claim it's a demonstration it doesn't exist.

Exactly. Stop wasting your breath Chalnoth. Saul has convinced himself that Dark Matter doesn't exist (and dark energy for some reason) and he has erected a wall around this idea. Nothing will get through. You've fought valiantly.

 

[Saul]

Exactly. Stop wasting your breath Chalnoth. Saul has convinced himself that Dark Matter doesn't exist (and dark energy for some reason) and he has erected a wall around this idea. Nothing will get through. You've fought valiantly.

I am expecting you to present logic arguments and observations to support dark matter which is somewhat different than fighting valiantly or with great effort to defend a theory.

I have presented observational data that directly refutes dark matter, in the thread dark matter on the ropes? Multiple papers have been presented that show dark matter cannot explain the observations concerning spiral galaxies. Your response is that galaxies are complicated and perhaps faster computers or different models will explain what is observed. I would assume you are stating that because you believe dark matter must exist. I am not sure however why you have that belief. The laboratory detection of dark matter has to this point failed.

The astronomical anomalies do not go away if dark matter does not exist. A different explanation is required.

We agree the astronomical observations need an explanation. More detail analysis is now however starting to change what is known about the anomalies. i.e. Disney et al's finding.

This thread is about Shanks' finding that the CMB data interpretation changes significantly if a distance object is used for calibration rather than Jupiter. The point is it was claimed that the CMB data shows within less than 1% that the standard model assumptions are correct (precision cosmology I believe was the tone of the belief.) That is no longer true as we are now aware that specific tuning assumptions were made to get the tuning of the CMB data to match the prediction. If Shanks' distance object is used that significantly changes the resultant such that the magnitude and the position of the first peak changes.

I provided a link the Planck satellite as it is expected there will be additional and better data to answer some of these questions. Let's keep watching for new data and new papers. That is what makes it interesting for me. Unanswered problem and additional data on the way to provide answers.

As to the question of whether dark energy does or does not exist, recent analysis of fluctuations in the CMB in the Northern Hemisphere do not support an accelerating universe. (The CMB is affected by clusters if the cluster velocity changes during the period in which the CMB passes by the cluster. The timing of the falling into and out of the gravity well is different if the universe is accelerating.) The Shanks announcement referenced this finding.

A universe that suddenly starts to accelerated was not expected and requires a change to the laws of physics to explain. As I said there are multiple phases in explaining anomalies. The first is confirmation the anomaly actually exists before enthusiastically supporting changing the laws of physics.

 

[bapowell]

A universe that suddenly starts to accelerated was not expected and requires a change to the laws of physics to explain.

Not expected based on what...a naive extrapolation of our recent expansion history?
As far as needing new physics, if you accept the existence of scalar fields, then no, it doesn't. If you don't accept the existence of scalar fields, then I'm sure you are equally as discontent with the Higgs mechanism, gauge theories, and inflation.

As to the question of whether dark energy does or does not exist, recent analysis of fluctuations in the CMB in the Northern Hemisphere do not support an accelerating universe. (The CMB is affected by clusters if the cluster velocity changes during the period in which the CMB passes by the cluster. The timing of the falling into and out of the gravity well is different if the universe is accelerating.) The Shanks announcement referenced this finding.

That doesn't sound right. The integrated Sachs-Wolfe effect depends on the time dependence of the gravitational wells of intervening galaxy clusters -- not on the velocity of the cluster. Besides, there you go again citing a single study that may claim results that contradict some model of dark energy. When faced with many data sources that seek to test a particular hypothesis, scientists should consider all of them, taking into account sample sizes, quality of the data, etc. If a scientist has several, high quality results with good statistics that say one thing, and one result that says another, he doesn't simply throw his hands up and call it a wash. He needs to do a little thing called Bayesian analysis, and rigorously investigate the problem. Surely you'd agree that if I did a single experiment with one data point that (somehow) refuted Newton's 2nd law, nobody in their right mind would consider my single experiment sufficient to overturn centuries of experimental work which support Newton's 2nd law. This is essentially what you are doing by cherry-picking a small number of studies that run counter to a large body of accumulated evidence in support of dark matter (and dark energy, but less so). For example, why would you conclude that results from a study done of the Northern Hemisphere only should trump (or even strongly call into question) results from (nearly) full sky studies??

 

[Chalnoth]

I provided a link the Planck satellite as it is expected there will be additional and better data to answer some of these questions. Let's keep watching for new data and new papers. That is what makes it interesting for me. Unanswered problem and additional data on the way to provide answers.

Well, that's not going to be for a couple of years yet, so it really doesn't have much bearing on the current discussion.