Re: Cosmic Background Radiation


Spoonfed wrote:
George Dishman wrote:
"jmetolius" <jmetolius@xxxxxxxxx> wrote in message
news:1148761125.216761.251840@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
It is generally accepted that the uniformity of the cosmic background
radiation provides a ready made test of whether the observer is
actually moving with the cosmic flow of space.
In our case, the background radiation shows a slight blue shift in one
direction that is explained by our 600km/sec relative motion withn that
cosmic flow...(our Earth's motion around the Sun, the Sun's motion
around the galactic center and the entire Milky Way has velocity, in
excess of the cosmic expansion, in the direction of the constellation
Hydra).


I realize it is impolite to mention this, but this calculation of 600
km/second is based on the *assumption* that the CBR is coming from a
source which is moving nonrelativistically.

Also, contrary to popular belief, the speed of the earth around the sun
is not enough to affect the measurment of the CBR dipole. In the WMAP
paper, you might notice that this effect is lumped into a heading with
other possible sources of error.

"The dipole signal seen by an observer moving with speed v relative to
the rest frame of the CMB is T0 v c, where T0 is the absolute
temperature of the CMB, and c is the speed of light. Thus, additional
sources of error that could affect the absolute calibration of the
WMAPdata include errors in the determination of WMAP's velocity with
respect to the solar system barycenter (the point of reference for the
COBEdipole) and errors in the absolute temperature of the CMB. The
velocity of WMAPis routinely measured with respect to geocentric
inertial coordinates (GCI) with an accuracy of  1 cm s-1. The velocity
of the Earth is determined from the JPL ephemeris with similar
accuracy. The combined uncertainty from velocity errors is 0.1 nK. The
uncertainty in the absolute temperature of the CMB is 0.1% (Mather et
al. 1999). Combining these uncertainties with the results of the
simulation, we conservatively estimate an absolute calibration error of
0.5% for the first-year WMAPdata."

Source: http://map.gsfc.nasa.gov/m_mm/pub_papers/firstyear.html
Data Processing Methods and Systematic Error Limits
G. Hinshaw et al, 2003, ApJS, 148, 63
ps (5.7 Mb) / pdf (3.3 Mb) / astro-ph

Let me repeat the most important line in here. The combined
uncertainty from velocity errors is 0.1 nK! That is 1 ten-millionth of
a milliKelvin.

Sure, you can calibrate 1 ten-thousandth of a milliKelvin into your
calculations and still produce perfectly good results when you are
generally mapping on milliKelvin scales or even microKelvin scales. It
won't make too much of a difference whether you are of by 1
ten-millionth of a milliKelvin, or 1 ten-thousandth of a microKelvin.

Unless you or they have data that shows Kelvin temperature of the CBR
to 10 or more decimal places then your concept, and the WMAP team's
concept of the CBR is every bit as hypothetical as mine.

.

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