On 31/10/2011 09:20, Szczepan Bialek wrote:
napisal w wiadomosci
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On 30/10/2011 20:31, Szczepan Bialek wrote:
napisal w wiadomosci
...
On 30/10/2011 15:37, Szczepan Bialek wrote:
It seems to me that the only way to measure the angle of refraction is
to
measure the absorption line position.
You are mistaken. Arago's experiment simply looked at the angle or
refraction.
But the line position was the same for stars:
"http://www.archive.org/stream/spectrumanalysis00esterich/spectrumanalysis00esterich_djvu.txt
"Indeed, these observations would scarcely be
possible, were it not that in the dark lines crossing the spec-
tra of the sun and fixed stars, the places of some of which
may be accurately ascertained, we have fixed positions in
the spectrum, the degree of refrangibility or wave-length of
which may be determined beforehand, both for the sun and
terrestrial substances, and also for the stars or other sources
of light supposed to be at rest. "
What you can't see, because Fig X is not included, is that the positions
of the lines is displaced because of the relative movements. So, the line
position was NOT the same. The following text makes this clear.
Below is the problem of the radial speeds of planets. Also the result
is
null:
http://articles.adsabs.harvard.edu//...00243.000.html
You are mistaken. That experiment was to detect oxygen lines in the
atmosphere of Venus.
You are right.
The Vogel's result do not fit to them.
Why not?
In all textbooks is wrote that Arago, Mchelson-Morley and
Truton-Noble
fit
together.
So what (in your own words) is the problem with Vogel's result?
The problem will appear if it is confirmed.
What problem?
Now it is mentioned only in Wiki. Without any comments.
If it is right than: "This experiment, which
demonstrated the effect of the earth's orbital movement on refraction
is of great historical interest. "
Arago's result yes.
I still don't know why you think there's a problem with Vogel's
result.
I know that in the whole World students are told that at measuring of
the
radial speed of stars they should take into account the orbital speed
of
the
Earth.
Yes.
The reason is the Vogel's result.
Sort of. More accurately, Vogel's result is a measurement of the earth's
orbital speed, hence, it needs to be taken into account.
Arago's result is "yes" and Vogel's result is "yes". Is it possible?
Of course it's possible. The speed of the incoming light is not changed by
the relative motion of the source and detector (Arago), but the frequency
of the spectral feature is changed (Vogel).
It is some problem because in 1905 Einstein wrote that it is impossible
to
detect the orbital speed. So are the two possibilities:
1. Brace and Einstein did not know about Vogel's result.
2. Vogel's result become wrong.
You are mistaken. Einstein wrote no such thing. What he wrote (in
effect)
is that the earth's orbital speed has no effect on the measured speed of
light, which is the explanation behind Arago's null result.
For me refraction = line position ("the dark lines crossing the spectra
of
the sun and fixed stars").
That's a mistake.
The only detail which can be measured are the position of that dark
lines.
Arago used the achromatic prism.
So you agree he couldn't have been looking at spectral lines if he was
using an achromatic prism. What he measured was the simple angle of
refraction.
He tried to see if the different speed of the Earth relative to the source
star made a difference to the angle of refraction. It doesn't
But the next used the dark lines.
But is possible that Arago's measurements and that to 1904 were not
accurate.
No, they were accurate enough -
Why than the Vogel's result is totally unknown?
Because he measured something that was not unexpected.
The spectra methods are a little mystery. And what with the radioscopy:
"In 1931, a Bell Telephone engineer, Karl Jansky (1905-1950), was trying to
find where the interference disrupting transatlantic radiophone circuits
came from. He discovered that some of the radio noise was not from the
Earth--it was extraterrestrial. The primary source was the center of the
Milky Way, in the constellation of Sagittarius. In 1936, an Illinois radio
engineer, Grote Reber (b. 1911), pursued the phenomenon farther." From:
http://physics.gmu.edu/~jevans/astr1..._txt.htm#5.2.1.
The radio frequences are easy to measure.
Are there the diurinal and annual effests?
I'm sure there are, but to detect them you would need to have a radio
receiver with good spectral resolution and a sources with narrow
frequency spectral features.
A bit of googling (using the words astronomical radio doppler effect
diurnal) has brought up the user guide for the Miriad software package
used by the Australia Telescope Compact Array (ACTA).
http://www.atnf.csiro.au/computing/software/miriad/
The section related to Spectral Line Data Reduction makes it clear that
the diurnal effect needs to be taken into account for fine velocity
resolution observations
http://www.atnf.csiro.au/computing/s...e/node134.html