An
English translation of
Translation
by Julie Newton. Final smoothing by R.S. Fritzius (in progress). Installed
as a web page on 11 Jul 2011. Latest update, 03 Nov 2011. The question of whether the
speed of light is dependent on the movement of the light source is of such
interest to the view of modern physics, that “an astronomical proof of the constant
speed of light,” such as seen in the article from Mr. W. de Sitter[1]
published in this journal, would be of extraordinary importance. Because I immediately became uncertain as to whether
the current facts permit such an absolute conclusion, I undertook a more exact
discussion[2]
of such and reached the conclusion that in my opinion, no such “proof” can be enunciated. Mr. de Sitter examines the
influence that the emission theory assumption, that the speed of light in any
direction equals the sum of the speed of the light source in the same direction
plus the speed of light of stationary light sources, would have on the apparent
motion of spectroscopic binary stars, and finds that their motion could not be Keplerian
and that it would become evident that the time interval between two digressions
[side-to-side excursions] would in one instance amount to [* - See diagram
at end.], and at another time, it would be where and can even
become negative beyond that. This
odd occurrence has never been observed, therefore Mr. de Sitter draws the
conclusion that the speed of light would have to be independent of the movement
of the light source. In fact, the conclusion made by
Mr. de Sitter is without a doubt strong, if one uses emission theory in its
unaltered state as a foundation; that is, if one assumes that the only possible
effect of a light source’s motion is a complete the two speeds Mr. de Sitter’s argument
that the measured shift in the lines of a spectroscopic binary star cannot be interpreted
by Keplerian motion if the speed of light were to be variable does not apply to
the entire field of possible movements, because the orbital movement with a variable
speed of light, as Mr. de Sitter views it, is primarily identical to the Keplerian
orbital motion of an ellipse, whose line of apsides is directed towards us,
while the periastron lies on the side pointed away from us. The speed in the direction of the line of sight,
as it is measured in spectroscopic observations, is in the first case
and
in the second case in which ( whereas we want to make
<2 remains. Under these restrictions our above assertion that both
forms of movement agree to the first order is valid, if one disregards the
higher powers of eccentricity. Mr. P.
Guthnick drew the two commensurate speed curves for instance, In any case we can say that for
all orbits whose eccentricities amount to smaller than 0.5, it may not always
be simple to separate the two forms of movement discussed above, and thus to
judge whether the eccentricity given is real or Now, it could be that a certain
percentage of these smaller eccentricities is more There is a further argument I
would like to raise. The systematic
variations between the speed curves of both motion phenomena show regular
cycles with amounts of In order to make a decision
about the questions brought up here, one would have to examine especially
opportune/advantageous spectroscopic binary stars from this angle, and
exclusively such binary stars whose parallax, i.e. the distance from us, is as
precisely known as possible. As of
today, we know with few exceptions the parallaxes of stars only by their orders
of magnitude, and therefore the assumed values can vary by ± 100 percent or
more from the actual values. If
variations from Keplerian motion are established though a more precise
discussion of the observations, it would depend on whether one could exhibit
these variations by way of a single value of the parameter (Received 1 July 1913.) [*] Derivation of Digression Delays: Δ = Distance to Observer (Not in original document.) [2] Mr. Paul Guthnick, to whom I am indebted
for the reference on the various features of spectroscopic binary stars theory,
will at the same time highlight the astronomically interesting views on this
question in a more general manner in [3] See Lick Observatory Bulletin 181, 1910. [4] Journal of the
Royal Astronomical Society of Canada, Volume II, 1908 and Ludendorff, [5] Shortly before sending this manuscript I
found that a work by Mr. D.F. Comstock is appearing in Top |