Holes in Big Bang

[Perpetual Student]

I'm not sure I follow PS; the estimated age of the universe owes essentially nothing to what's in the paper that PR you provide a link to is based on (see my earlier posts) ... perhaps it would be of interest to you if I outlined how the age of the observable universe is estimated?

Or did you have some other question?

Sorry that my point was not clear. Well, the error in the estimate for "small stars" causes one to speculate about how many other errors there might be in our current assumptions about astronomical phenomena -- it simply causes a lack of confidence in the whole process of making astronomical estimates. The extrapolations to the big bang depend on many current estimates of the universe as we currently see it. Is that not true? Perhaps we get a pass on the number of "small stars" as it effects estimates of the age of the universe, but that cannot be true of every estimate we make about astronomical phenomena.

Yes I would very much like to see an outline of how the age of the universe is estimated to such an astonishingly precise number.

 

[QED]

Does anyone know where I can find figures on the distribution of baryonic matter? Ie. what percentage of all baryonic matter makes up stars? What percentage the IGM? Planets and other small bodies and hard to detect bodies etc?

I couldn't find these figures, I tried various terms but all that kept popping up is the percentage of baryonic matter in the universe (compared to non-baryonic matter and dark energy). Not how the baryonic mass is distribution among its constituents.

ETA:

Well, the error in the estimate for "small stars" causes one to speculate about how many other errors there might be in our current assumptions about astronomical phenomena -- it simply causes a lack of confidence in the whole process of making astronomical estimates.

DeiRenDopa is certainly more qualified than I am to answer your question about the big bang, but I want to throw in one fact that really impressed me when I read up on measuring distances in space.

Astronomers are extremely ingenuous when it comes to finding mutually independent ways to measure the same attribute of something. Since it is THE most important aspect of astronomy to get reliable measurements they try every conceivable way to do it and are in general very tentative. Compared to most other sciences astronomical objects can't be studied in the laboratory, so methodology is essential. Close attention is paid to systematic errors that could corrupt the results and astronomers love to put error bars on everything.

So when we are talking about one kind of measurement being off to some decree, there normally are still completely independent ways that show to WHAT DECREE the measurement could potentially be off. Since those mutually independent methods produce results on the same order of magnitude.

I like to compare this to geology were many different and independent radiometric dating methods are used to date a rock and while all have quite big error bars, they together give us a good and reliable estimate on the age. The same is true for astronomy.

 

[Michael Mozina]

Does anyone know where I can find figures on the distribution of baryonic matter? Ie. what percentage of all baryonic matter makes up stars? What percentage the IGM? Planets and other small bodies and hard to detect bodies etc?

I couldn't find these figures, I tried various terms but all that kept popping up is the percentage of baryonic matter in the universe (compared to non-baryonic matter and dark energy). Not how the baryonic mass is distribution among its constituents.

When you do get your explanation, make sure the number they come up with includes those recent revelations that galaxies are twice as bright as we realized and there are four times as many stars in a galaxy as we first assumed.

 

[Ziggurat]

Does anyone know where I can find figures on the distribution of baryonic matter? Ie. what percentage of all baryonic matter makes up stars? What percentage the IGM? Planets and other small bodies and hard to detect bodies etc?

I couldn't find these figures, I tried various terms but all that kept popping up is the percentage of baryonic matter in the universe (compared to non-baryonic matter and dark energy). Not how the baryonic mass is distribution among its constituents.

Any object which we can see is primarily baryonic matter - the non-baryonic component being just electrons, which make up a very small mass fraction. That includes planets and other smaller objects. Non-baryonic dark matter interacts weakly, and should not form compact objects.

 

[ben m]

Does anyone know where I can find figures on the distribution of baryonic matter? Ie. what percentage of all baryonic matter makes up stars? What percentage the IGM? Planets and other small bodies and hard to detect bodies etc?

You're looking for the Cosmic Baryon Budget. The classic paper is Fukugita, Hogan, and Peebles. (I think there's a more-recent paper by some of the same authors.)

http://arxiv.org/abs/astro-ph/9712020

 

[Michael Mozina]

Thanks for that. While I do find that MM's objections to standard cosmology far fetched, he does occasionally make some good points. When I see statements like:


FROM: link

followed by the discovery that we have this magnitude of error LINK in our observations, I become quite perplexed. There appears to be quite a bit of hubris in a number like 13.75 +/- .12 years. If we do not have an accurate reading of "small stars" to the degree of a four-fold error, how can we come by such an exact estimate for the age of the universe.

Good question.

 

[Michael Mozina]

You're looking for the Cosmic Baryon Budget. The classic paper is Fukugita, Hogan, and Peebles. (I think there's a more-recent paper by some of the same authors.)

http://arxiv.org/abs/astro-ph/9712020

Note that the "classic' paper neither includes the revelation that galaxies are twice as bright as we realized in 1998, or the fact that galaxies have four times as many smaller stars in them than we thought in 1998.

 

[Dancing David]

Thanks for that. While I do find that MM's objections to standard cosmology far fetched, he does occasionally make some good points. When I see statements like:


FROM: link

followed by the discovery that we have this magnitude of error LINK in our observations, I become quite perplexed. There appears to be quite a bit of hubris in a number like 13.75 +/- .12 years. If we do not have an accurate reading of "small stars" to the degree of a four-fold error, how can we come by such an exact estimate for the age of the universe.

The universe that can be seen is smaller thna the universe that possibly exists?

The determination of the age of the universe is made rather accurately, the Hubble constant gets narrowed every year. But it is based upon the Hubble constant.

This is kind of interesting:
http://hubblesite.org/newscenter/archive/releases/2009/08/

 

[DeiRenDopa]

Sorry that my point was not clear. Well, the error in the estimate for "small stars" causes one to speculate about how many other errors there might be in our current assumptions about astronomical phenomena -- it simply causes a lack of confidence in the whole process of making astronomical estimates.

First, I invite you to join Skwinty ... download the paper (NOT the PR!), read it, and then ask questions (I'll be happy to try to help you understand the paper, and also show you how misleading the PR is).

Second, every conclusion drawn from astronomical observations comes with estimates of uncertainty. Further, in nearly every case, how the 'error budget' is determined is at least described (and in some cases, it is the sole topic of a string of very long papers!). Then, again in nearly every case, a clear distinction is made between estimated uncertainty due to known, essentially random factors, and estimated uncertainty due to systematic effects.

Systematic effects are the bane of astronomers' lives (or, to some, their primary research topic), and vast amounts of time and effort go into studying them. However, it is a fact of modern life that this 'back story' sells no papers, so you rarely see it (in PRs, popsci articles, etc, etc, etc). One unfortunate consequence is that all kinds of weird ideas start to float around the internet, based on little more than ignorance of estimates of uncertainty in astronomical results (and some folk apparently seek out this sort of thing to the exclusion of everything else).

Bottom line: if you are interested in the degree of confidence that can reasonably be given to any particular astronomical result, I think you have no choice but to roll up your sleeves and learn how the result was obtained, and what those engaged in doing the research have (and have not) already painstakingly taken account of.

OK, I'll climb down now.

The extrapolations to the big bang depend on many current estimates of the universe as we currently see it. Is that not true? Perhaps we get a pass on the number of "small stars" as it effects estimates of the age of the universe, but that cannot be true of every estimate we make about astronomical phenomena.

Yes I would very much like to see an outline of how the age of the universe is estimated to such an astonishingly precise number.

Happy to oblige!

First, though, the sources.

This LAMBDA ("Legacy Archive for Microwave Background Data Analysis") webpage is by far the best single source ("Bibliography of WMAP Science Team Publications Five Year Data Scientific Papers"). The single paper you should read is "Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from WMAP Data" (third from the bottom). If you haven't already done so, familiarise yourself with the cosmology tutorial on Ned Wright's website; the FAQs include one called "Age of the Universe"; I think that should answer your question.

The number you quoted earlier comes from a newspaper (!), but its likely source is a PR from the WMAP team, probably from their Three-Year results; you can learn about how observations of the CMB can be used to estimate the age of the universe from the LAMBDA webpage (above).

 

[Michael Mozina]

Ages and assumptions....

>># The age of the chemical elements.
>># The age of the oldest star clusters.

FYI, these two "measurements" are based upon the 'assumption' that elements do not mass separate (much) in stars. Iron and Nickel presumably somehow stay mixed with hydrogen and helium. If you remove that specific assumption, these particular methods become highly suspect, in fact they become useless.

 

[DeiRenDopa]

Does anyone know where I can find figures on the distribution of baryonic matter? Ie. what percentage of all baryonic matter makes up stars? What percentage the IGM? Planets and other small bodies and hard to detect bodies etc?

I couldn't find these figures, I tried various terms but all that kept popping up is the percentage of baryonic matter in the universe (compared to non-baryonic matter and dark energy). Not how the baryonic mass is distribution among its constituents.

The paper ben m cited is a good starting place ... though, as he notes, "there's a more-recent paper by some of the same authors" ... indeed; this classic has been cited 735 times (according to ADS)!

This may be what he had in mind: The Cosmic Energy Inventory

If this isn't what you're looking for, just holler ...

ETA:


DeiRenDopa is certainly more qualified than I am to answer your question about the big bang, but I want to throw in one fact that really impressed me when I read up on measuring distances in space.

Astronomers are extremely ingenuous when it comes to finding mutually independent ways to measure the same attribute of something. Since it is THE most important aspect of astronomy to get reliable measurements they try every conceivable way to do it and are in general very tentative. Compared to most other sciences astronomical objects can't be studied in the laboratory, so methodology is essential. Close attention is paid to systematic errors that could corrupt the results and astronomers love to put error bars on everything.

So when we are talking about one kind of measurement being off to some decree, there normally are still completely independent ways that show to WHAT DECREE the measurement could potentially be off. Since those mutually independent methods produce results on the same order of magnitude.

I like to compare this to geology were many different and independent radiometric dating methods are used to date a rock and while all have quite big error bars, they together give us a good and reliable estimate on the age. The same is true for astronomy.

Quite.

And it gets much, much worse when the Chinese whispers converts what's in Meurer et al. paper into something like "we do not have an accurate reading of "small stars" to the degree of a four-fold error"! As you can see, above, RC did a sterling job of trying to address MM's wild imagination wrt interpreting the PR (it seems MM did not read the actual paper), but if you are completely blind to the details of what was actually studied, what the scope of the results is, what the uncertainties are, etc, etc, etc it's all too easy to get confused.

 

[QED]

You're looking for the Cosmic Baryon Budget. The classic paper is Fukugita, Hogan, and Peebles. (I think there's a more-recent paper by some of the same authors.)

http://arxiv.org/abs/astro-ph/9712020

Thanks! That's exactly what I've been looking for.

ETA:

The paper ben m cited is a good starting place ... though, as he notes, "there's a more-recent paper by some of the same authors" ... indeed; this classic has been cited 735 times (according to ADS)!

This may be what he had in mind: The Cosmic Energy Inventory

I think it's the right one, thanks!

[...] Our inventory includes the mass densities in the various
states of baryons. This is an updated version of the baryon
budget of Fukugita et al. (1998, hereafter FHP98).Most entries
in this part of the inventory have not changed much in the past
half-decade, while substantial advances in the observational
constraints have considerably reduced the uncertainties. It appears
that most of the baryonic components are observationally
well constrained, apart from the largest entry, for warm plasma,
which still is driven by the need to balance the budget rather
than more directly by the observations. [...]

 

[Michael Mozina]

The universe that can be seen is smaller thna the universe that possibly exists?

The determination of the age of the universe is made rather accurately, the Hubble constant gets narrowed every year. But it is based upon the Hubble constant.

This is kind of interesting:
http://hubblesite.org/newscenter/archive/releases/2009/08/

Of course that particular measurement is based upon two primary assumptions:

A) Redshift is related *only* to expansion.
B) Everything (all matter and energy) was once condensed to a point.

The first assumption isn't all that difficult to defend, but the second assumption is virtually impossible to defend.

 

[QED]

Of course that particular measurement is based upon two primary assumptions:

A) Redshift is related *only* to expansion.
B) Everything (all matter and energy) was once condensed to a point.

The first assumption isn't all that difficult to defend, but the second assumption is virtually impossible to defend.

Let's disregard for a moment that no one claims redshift is *only* related to expansion (only that it is the dominant factor over large distances), B) isn't even an assumption at all, it is a consequence of A).

 

[DeiRenDopa]

Of course that particular measurement is based upon two primary assumptions:

A) Redshift is related *only* to expansion.
B) Everything (all matter and energy) was once condensed to a point.

The first assumption isn't all that difficult to defend, but the second assumption is virtually impossible to defend.

Let's disregard for a moment that no one claims redshift is *only* related to expansion (only that it is the dominant factor over large distances), B) isn't even an assumption at all, it is a consequence of A).

Quite ...

... except that there are caveats; for example, no matter what density and/or temperature you are no longer comfortable with, when you 'run the clock backwards' on the observable universe, you won't get 'a point' ... there are those who run with some theory (perhaps too grand a word) which reconciles the deep inconsistencies between GR and QM in the Planck regime, but if you take a conservative view, you'll stop even well before then, at ~ten times the physics probed by the Tevatron perhaps.

You are quite right, of course, that estimates of the local (time) value of the Hubble constant* are quite independent of the details in cosmological models earlier than the time of BBN (say).

You could also have added, for MM's benefit, that the Hubble distance-redshift relationship has been studied intensively for many decades now, and is well supported by huge numbers of observations, of many different (independent) kinds. John Huchra's webpage on it is a good read.

* I'm guessing that's what MM is referring to

 

[Michael Mozina]

Let's disregard for a moment that no one claims redshift is *only* related to expansion (only that it is the dominant factor over large distances), B) isn't even an assumption at all, it is a consequence of A).

B) is most certainly an assumption. Alfven's "bang" did nothing of the sort. While you might be able to demonstrate *some* degree of concentration of matter and energy, you could never demonstrate it all came from a single point.

 

[Perpetual Student]

First, I invite you to join Skwinty ... download the paper (NOT the PR!), read it, and then ask questions (I'll be happy to try to help you understand the paper, and also show you how misleading the PR is).

Second, every conclusion drawn from astronomical observations comes with estimates of uncertainty. Further, in nearly every case, how the 'error budget' is determined is at least described (and in some cases, it is the sole topic of a string of very long papers!). Then, again in nearly every case, a clear distinction is made between estimated uncertainty due to known, essentially random factors, and estimated uncertainty due to systematic effects.

Systematic effects are the bane of astronomers' lives (or, to some, their primary research topic), and vast amounts of time and effort go into studying them. However, it is a fact of modern life that this 'back story' sells no papers, so you rarely see it (in PRs, popsci articles, etc, etc, etc). One unfortunate consequence is that all kinds of weird ideas start to float around the internet, based on little more than ignorance of estimates of uncertainty in astronomical results (and some folk apparently seek out this sort of thing to the exclusion of everything else).

Bottom line: if you are interested in the degree of confidence that can reasonably be given to any particular astronomical result, I think you have no choice but to roll up your sleeves and learn how the result was obtained, and what those engaged in doing the research have (and have not) already painstakingly taken account of.

OK, I'll climb down now.


Happy to oblige!

First, though, the sources.

This LAMBDA ("Legacy Archive for Microwave Background Data Analysis") webpage is by far the best single source ("Bibliography of WMAP Science Team Publications Five Year Data Scientific Papers"). The single paper you should read is "Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from WMAP Data" (third from the bottom). If you haven't already done so, familiarise yourself with the cosmology tutorial on Ned Wright's website; the FAQs include one called "Age of the Universe"; I think that should answer your question.

The number you quoted earlier comes from a newspaper (!), but its likely source is a PR from the WMAP team, probably from their Three-Year results; you can learn about how observations of the CMB can be used to estimate the age of the universe from the LAMBDA webpage (above).

OK, thanks again; I will look at the information you provided. What amazes me about the presumed accuracy of the universe's age estimate is that, not only does it depend on the accuracy of observations, but that the age is not based on a simple extrapolation of a uniform rate. The rate has been accelerating for at least 9 billion years. So the actual beginning of the acceleration is not known exactly. But nevertheless: +/- .12 billion years (that's quite a feat)!

 

[Perpetual Student]

OK, thanks again; I will look at the information you provided. What amazes me about the presumed accuracy of the universe's age estimate is that, not only does it depend on the accuracy of observations, but that the age is not based on a simple extrapolation of a uniform rate. The rate has been accelerating for at least 9 billion years. So the actual beginning of the acceleration is not known exactly. But nevertheless: +/- .12 billion years (that's quite a feat)!

I have been following this for many years now. If I could, I would bet that the current consensus estimate will be different by at least a billion years ten years from now. Some new observations will surface, errors will be found, and/or new theories will develop.

 

[sol invictus]

Of course that particular measurement is based upon two primary assumptions:

A) Redshift is related *only* to expansion.
B) Everything (all matter and energy) was once condensed to a point.

The first assumption isn't all that difficult to defend, but the second assumption is virtually impossible to defend.

Good thing, then, that no results in cosmology depend on B), nor is B) a prediction or claim of the theory.

But we've discussed that more times than I can recall and it hasn't stopped you from posting exactly the same thing again and again, so I'm not going to bother.

 

[DeiRenDopa]

I have been following this for many years now. If I could, I would bet that the current consensus estimate will be different by at least a billion years ten years from now. Some new observations will surface, errors will be found, and/or new theories will develop.

The Wright FAQ page gives three independent methods of estimating the age of the universe, in addition to an estimate based on cosmological models (plus estimates of key parameters).

The 'error bars' on estimates based on each method (several estimates per method!) are far larger than +/- 0.12 billion years (Gyr), but the ranges all overlap.

The WMAP Five-Year paper I cited gives estimates of the densities of matter and dark energy; the Huchra website I cited gives a good summary of the history of estimates of the Hubble constant.

This LAMBDA/WMAP webpage is a table of the estimated values of the parameters, including the age of the universe. It is based on a WMAP Three-Year paper, and gives the age of the universe as 13.69 +/- 0.13 and 13.72 +/- 0.12 Gyr, with several critical footnotes, perhaps the most important of which is "The first value assumes the 6 parameter ΛCDM model using WMAP data only, the second using WMAP+BAO+SN data" (I've edited the footnote somewhat).

You'd need to read all relevant papers quite closely to determine just what the error bars are (typically, 68% confidence limits), and what key assumptions have been made in deriving those uncertainties.

Over the next few years perhaps the biggest single input to further constraining the age estimate (and estimated uncertainty) will be data from Planck ... and that data should also improve your comfort with the results (nothing better than independent validation, is there!). There's also a great deal of work going on on BAO (baryon acoustic oscillations) and SN (supernovae); results from that work will also, no doubt, further constrain the estimated age (and, perhaps, reduce the uncertainty).

A Gyr? Such a large change in the estimated age, derived from cosmological models, would seem unlikely; naively, that'd be ~8 sigma, which is as close to "impossible" as never mind. However, the error analysis that came up with +/- 0.12 Gyr is considerably more detailed and careful than what you find in a Statistics 101 textbook! Then there's the dependency on the actual model (who can say what will replace a six-parameter ΛCDM one?), as well as the values of the parameters in any such model.