Re: Missing Matter

Charles Francis <charles@xxxxxxxxxxxxxxxx> writes
>Thus spake Oz <Oz@xxxxxxxxxxxxxxxxxxxx>
>>Charles Francis <charles@xxxxxxxxxxxxxxxx> writes
>>>
>>>But I have been overlooking more obvious stuff, and it has made me think
>>>about it. Now, if I have the astronomers right they actually observe
>>>less than 3% critical mass, and get about 27% cold dark matter. So if I
>>>dispense with the cdm, and only need 1/4 critical mass I still have only
>>>10% of the matter needed for a closed universe.
>>
>>I don;t think this is right. I think they can account for something like
>>25% to 30% of the mass required for closure if they include galaxies,
>>large gas clouds, known dark matter, neutrino energy and so on.
>
>Turns out we are both cosmologically challenged.

Cosmically would be better.

>I should have looked in
>a text book straight away, but I generally find looking in Peebles about
>as effective as a pan galactic gargle blaster,

blows your mind, so clearly you mean a glass of water (ie ineffective).

>and with the same kind of
>effect. I seriously scared myself just before I left Wales, since after
>I had rashly been on amazon a package turned up containing three books
>of cosmology & Kant (who has gone right down in my estimation, having
>read a bit of him).

Pah! You wealthy chicken farmers...

>Turns out one of the books is quite readable, however: Andrew Liddle,
>Intro to modern Cosmology. It looks like a course a bear of little brain
>could manage and even enjoy. Only 160 pages total. Published 2003, so up
>to date.

$$$$?

>Baryonic matter calculated from nuclear synthesis is only about 2%
>critical mass. Observed stars are less than 1%.

Yes. There are some hypermassive H2 gas clouds etc etc so 2% seems
reasonable. To which we add neutrino mass contribution etc etc.

>CDM in galaxies is
>reckoned about ten times more, and by studying the motions of galaxies
>they have established the existence of 30% dark matter, the bulk of
>which has to be non-baryonic. Trouble is, of course, the motions of
>galaxies fall into the MONDIAN regime.

Of course, so we ignore this hypothetical extra mass.

>That brings me down to 2%
>critical density, or rather 8% with the teleconnection.

Yup. There is no law that says the universe must be closed.

>>>This being based on the universe having 1/1000 its
>>>current size at decoupling.
>>>
>>>But the square law would have the universe at 1/30 its current size at
>>>decoupling. If decoupling is at a particular density (is it?)
>>
>>Probably, its a particular temperature.
>
>You have to predict the relative abundances of light elements and
>measure them. The relative abundances give mass density at decoupling.
>AFAICS The density has to be the same whatever redshift law is used.

Didn't I say just that?

>>>then I get
>>>30^3 times the amount of matter at decoupling. That seems like a lot too
>>>much.
>>
>>Hang on though, you are confused. You can't do it quite as naively as
>>that.
>>>
>>>This calculation is probably rubbish.
>>
>>I agree.
>
>The problem has to be that I wildly stated that the universe should be
>1/30 current size at decoupling, taking sqrt(1/1000). I should use
>proper formula for black body radiation and calculate the size of the
>universe from that.

How do you do this?

>I'm too tired. You're the physicist, you have a go.
>You probably even know the formula for black body radiation.

Stefan's law, yes.

>Don't talk to Carr or anyone just now.

I wasn't intending to. I need a better paper from you that says it all
more clearly, simply and non-crankily.

>This calculation is pretty
>essential to the claim that the model has been compared to observational
>data that could have falsified it.

Yes.

>I need to end up with something
>within range of critical mass.

Not needed, must match observation, which is quite another thing.

>Missing it was a serious oversight, which
>I blame on my perpetual ignorance.

Join the club.

--
Oz
This post is worth absolutely nothing and is probably fallacious.

Use oz@xxxxxxxxxxxxxxxxxxxx [ozacoohdb@xxxxxxxxxxxxx functions].
BTOPENWORLD address has ceased. DEMON address has ceased.

.

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