The Einstein Theory of Relativity | Page 8

itself felt upon
the ray at a distance eight times removed from its centre.
The displacements calculated according to the theory are, just because
of the way in which they are calculated, in inverse proportion to the
distance to the centre. Now that the observed deviations also accord
with the same rule, it follows that they are surely proportionate with the
calculated displacements. The proportion of the first and the last
observed sidewise movements is 4.2, and that of the two most extreme
of the calculated numbers is 4.4.
This result is of importance, because thereby the theory is excluded, or
at least made extremely improbable, that the phenomenon of refraction
is to be ascribed to, a ring of vapor surrounding the sun for a great
distance. Indeed, such a refraction should cause a deviation in the
observed direction, and, in order to produce the displacement of one of
the stars under observation itself a slight proximity of the vapor ring
should be sufficient, but we have every reason to expect that if it were
merely a question of a mass of gas around the sun the diminishing
effect accompanying a removal from the sun should manifest itself
much faster than is really the case. We cannot speak with perfect
certainty here, as all the factors that might be of influence upon the

distribution of density in a sun atmosphere are not well enough known,
but we can surely demonstrate that in case one of the gasses with which
we are acquainted were held in equilibrium solely by the influence of
attraction of the sun the phenomenon should become much less as soon
as we got somewhat further from the edge of the sun. If the
displacement of the first star, which amounts to 1.02-seconds were to
be ascribed to such a mass of gas, then the displacement of the second
must already be entirely inappreciable.
So far as the absolute extent of the displacements is concerned, it was
found somewhat too great, as has been shown by the figures given
above; it also appears from the final result to be 1.98 for the edge of the
sun--i.e., 13 per cent, greater than the theoretical value of 1.75. It
indeed seems that the discrepancies may be ascribed to faults in
observations, which supposition is supported by the fact that the
observations at Prince's Island, which, it is true, did not turn out quite
as well as those mentioned above, gave the result, of 1.64, somewhat
lower than Einstein's figure.
(The observations made with a second instrument at Sobral gave a
result of 0.93, but the observers are of the opinion that because of the
shifting of the mirror which reflected the rays no value is to be attached
to it.)

DIFFICULTY EXAGGERATED
During a discussion of the results obtained at a joint meeting of the
Royal Society and the Royal Astronomical Society held especially for
that purpose recently in London, it was the general opinion that
Einstein's prediction might be regarded as justified, and warm tributes
to his genius were made on all sides. Nevertheless, I cannot refrain,
while I am mentioning it, from expressing my surprise that, according
to the report in The Times there should be so much complaint about the
difficulty of understanding the new theory. It is evident that Einstein's
little book "About the Special and the General Theory of Relativity in
Plain Terms," did not find its way into England during wartime. Any
one reading it will, in my opinion, come to the conclusion that the basic
ideas of the theory are really clear and simple; it is only to be regretted
that it was impossible to avoid clothing them in pretty involved
mathematical terms, but we must not worry about that.

I allow myself to add that, as we follow Einstein, we may retain much
of what has been formerly gained. The Newtonian theory remains in its
full value as the first great step, without which one cannot imagine the
development of astronomy and without which the second step, that has
now been made, would hardly have been possible. It remains, moreover,
as the first, and in most cases, sufficient, approximation. It is true that,
according to Einstein's theory, because it leaves us entirely free as to
the way in which we wish to represent the phenomena, we can imagine
an idea of the solar system in which the planets follow paths of peculiar
form and the rays of light shine along sharply bent lines--think of a
twisted and distorted planetarium--but in every case where we apply it
to concrete questions we shall so arrange it that the planets describe
almost exact ellipses and the rays of light almost straight lines.
It is not necessary to give up entirely even the ether. Many natural
philosophers