HELP!!! CMB help required...

the_avenging_bucket
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HELP!!! CMB help required...

Please guys, if anyone would like to rip this one apart...
I am not that clued up on this stuff... would like to know more.

These guys are saying that CMB dating of the universe is not accurate...

http://www.answersingenesis.org/tj/v15/i1/microwave.asp


KSMB
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Unfortunately, I am not a

Unfortunately, I am not a cosmologist, but even I can spot some completely incorrect statements in that article. In order to learn more, I asked the friendly neighbourhood cosmologist over at AN, Chalnoth. This is what he had to say:

Chalnoth wrote:
Some seriously ridiculous stuff there Smiling

The first paragraph is good. The second paragraph goes on about a red herring. The principle of relativity, which seems to be correct but isn't set in stone, states that physical laws are independent of inertial reference frame. In every region of space, there is an average velocity of galaxies. This doesn't break the principle of relativity in the least.

As for the supposed cosmological models that are consistent with observation, such as the one proposed by Gentry, my own General Relativity professor has this to say:

Quote:
In a recent article in Modern Physics Letters A, Gentry proposed a new static cosmological model that seeks to explain the Hubble relation as a combination of gravitational and Doppler red shifts. We show that Gentry’s model, although supposedly based on general relativity, is inconsistent with the Einstein field equations; that it requires delicate fine tuning of initial conditions; that it is highly unstable, both gravitationally and thermodynamically; and that its predictions disagree clearly with observation.

http://arxiv.org/abs/astro-ph/9808021

You really can't get any more wrong than that, while still remaining somewhat coherent Smiling

The Cosmological Principle also need not apply: stuff outside our horizon won't affect us anyway. So we use it to make or equations work out nicely.

The paper regarding the required size of the anisotropies was written in 1991, and is, as such, too old to be of much value as providing doubts for modern cosmology. I think it's likely that the problem is solved by introducing dark energy, but I haven't studied structure formation in great detail. I have heard of no significant issues with modern n-body simulations related to the amplitude of perturbations.

I also love how they, without even citing a source, claim that the blotches can be explained by having a negative curvature! Absolutely absurd. You don't suddenly take a completely and utterly smooth feature (overall spatial curvature) and produce small-scale fluctuations! I haven't read the paper that they quoted before claiming this, but I suspect they just found that it was likely for there to be a slightly negative curvature given the experimental data. This doesn't say that the blotches can be explained by the negative curvature, but rather that the blotches seem to indicate one.

As for dark matter, that has pretty conclusively been detected by the observation of the bullet cluster. The paper in question where they claim that Boomerang suggests a purely baryonic universe (as in no dark matter) is just plain wrong: the experiment in question was not capable of properly measuring the feature on the CMB in question, as it just didn't cover enough area of the sky. That feature has since been detected by the WMAP satellite, which provides a strong signal for dark matter.

As far as the structure of galaxies, this is, computationally, a very difficult problem. We have astrophysicists working on the problems, and have a fair amount of understanding, but there is still much more to do. Anyway, really enjoyed it, was a fun read, no matter how absurdly wrong it was Smiling

From my understanding, the variations in the CMB at the 10^-5 level is as large as would be expected from the inflated Big Bang model. I don't know much more than that.

What I do now is when the article states "creationist cosmology" by a guy at the institute for creation research, then you can stop taking it seriously right there. The 6000 year time frame is not only inconsistent with all plausable cosmology, it is of course inconsistent with results from dating methods on the earth, moon and meteorites.

Lastly, I do not know why they even mention spiral galaxies in the cosmological context of the rest of the article. Cosmology operates on MUCH larger scales than galactic spiral arms. The problems with the spiral arms do not in any way invalidate the observations of orbital motions of stars. Dark matter is still needed for that, there is no way the baryonic component alone can account for the orbits.


Yellow_Number_Five
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If only CMBR were the ONLY

If only CMBR were the ONLY way we dated the universe.

What of Hubble's Law?

What of the Magellic Cloud about 150,000 light years away?(1)

What of radiometric dating that puts the earth at 4.5 billion years old?

What of the thousands of other pieces of evidence that agree with an old universe? I'm much too tired and sick to start listing them all here and now, so feel free to add a few if you wish.

(1)Cole, Andrew A., 2000. The distance to the Large Magellanic Cloud. Science 289: 1149-1150.

I am against religion because it teaches us to be satisfied with not understanding the world. - Richard Dawkins

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