The Talk.Origins Archive Post of the Month: July 2010

Subject:    | The CMB is isotropic and its energy distrubution is that of perfect blackbody (at thermal equilibrium)
Date:       | 13 Jul 2010
Message-ID: | i1gfr0$uiu$1@speranza.aioe.org

Note: This post responds to a claim that a model of the cosmos with Earth fixed and unmoving at its center is in agreement with observation. A more complete discussion by the author was posted three days later, here.

The deviation from isotropy has now been measured, in a reproducible way, with great accuracy. It agrees very precisely with theoretical predictions. In particular, the angular correlation power spectrum -- the measure of the relationship between the temperature fluctuations at different angles -- is a rather complicated curve, which nevertheless agrees exquisitely with theory. You can find a graph of the observed power spectrum, with the error bars, at http://arxiv.org/abs/1001.4635 (see figure 1), along with separate measurements of the temperature- polarization spectrum (figure 3). Both figures also show the predicted curves; note the very good fit.

This spectrum gives us detailed information about the very early Universe. When the Universe was very young and very hot, the ordinary matter was almost entirely a plasma of ionized hydrogen. The small perturbations in the density of this plasma propagated as what were essentially sound waves, with speeds that can be predicted accurately from ordinary laboratory physics. This resulted in correlations of the density at predictable distances -- the plasma was denser at crests of sound waves, and less dense at troughs -- and these show up in the measured CMB temperature.

(When the plasma cooled, the denser areas also served as seeds for galaxy formation. This is also testable -- we observe correlations in the number of galaxies that match the correlations in the CMB temperature fluctuations. The relevant key words are "baryon acoustic oscillations.")

> and as pointed out by Guth the energy distribution is
> perfectly black body; that is, at thermal equilibrium.

Note that this means that the Universe was once very hot and at thermal equilibrium. More on this later.

> Guth also points out that the isotropy is predicted by Big Bang as well
> as the minor temperature variations.

> But what of the very small temperature fluctuations. Guth (and Smoot
> for that matter) considered the variations as corroborative of the
> Inflationary Model and evidence of the formation of the large scale
> structure in the universe.

As supported by the fact that the correlation among large scale structures matches that of the CMB fluctuations -- see above.

> However, all Inflationary Models require cold dark matter/energy
> which no one can find.

The evidence for cold dark matter predated measurements of the CMB by decades. The main evidence comes from observing the orbits of stars in galaxies, and gas in galaxy clusters, along with newer observations of gravitational bending of light. The CMB observations nicely match the independent measures of cold dark matter. If they hadn't that would have been a problem for the theory.

Similarly, the evidence for dark energy is independent of the CMB, coming from observations of the brightness of supernovae at various distances. Again, the CMB observations nicely match independent observations.

> And when it is assumed
> that these minor temperature variations are due to some sort of random
> quantum fluctuations (the usual assumption) in the early "Big Bang"
> universe, it becomes impossible to explain the surprisingly regular
> arrangement of galaxies and clusters of galaxies (with Earth at the
> center).

You're making this up. No such arrangement exists. Take a look at http://www.sdss.org/includes/sideimages/sdss_pie2.html for a map of the galaxies and clusters around the Earth. If you call this "regular," you might want to visit an optometrist.

> DeLaney hung his hat on some very minor variations which Guth claims
> only ruled out the Steady State Model. What it does not rule out is
> a Euclidean, non inflationary, rotating universe with Earth at the
> center. And the geoCentric Model does not require conjuring of non
> existent cold dark matter/energy.

Really, now? Then perhaps you can explain how this geocentric model explains the following? [Prediction: Tony will not answer.]

1. When an object moves with respect to the CMB, the light in the direction of motion is Doppler shifted toward the blue, and the light in the opposite direction is shifted toward the red, making a distinctive ("dipole") pattern. The observed CMB has such a dipole, corresponding to a speed of 370 km/sec. How does the geocentric model explain this?

2. In addition to this overall dipole, there is another dipole component that changes direction from day to day, with a period of a year. The Doppler shift of this component corresponds to a circular motion with a period of one year and a speed of about 30 km/sec -- see Kogut et al., Ap. J. 419 (1993) 1. The standard explanation is that this Doppler shift is due to the Earth's orbit around the Sun. What, exactly, is the geocentric model's explanation?

3. As you pointed out above, the observed CMB has, on average, a very good black body spectrum, which, as you say, implies that it was produced at thermal equilibrium. In standard cosmology, this is taken as evidence that the Universe was, in early times, at thermal equilibrium. What is the geocentric model's explanation? (Note that black body spectra of objects at different temperatures do *not* add up to a single black body spectrum; your answer will have to explain why it appears that the whole Universe was once at a single temperature.)

4. You say the geocentric model does not require cold dark matter. How, then, does it explain galaxy rotation curves, which do not match Newtonian gravity if only the directly observed matter is present? How does it explain X-ray temperatures of galactic clusters? How does it explain gravitational lensing observations of masses? How does it explain the Bullet Cluster?

5. You say the geocentric model does not require dark energy. How does it explain the observed brightness/distance relationship of supernovae?

Is the Earth the fixed center of the Universe?

(The motion of the earth around the sun causes a doppler shift in the light of the Cosmic Microwave Background (CMB).)

Post of the Month: July 2010