Evening star., 1937-10-07
STARS, MEN AND ATOMS
Notebook of Science Progress in Field,
Laboratory and Study.
BY THOMAS r. HENRY.

The theory Of relativity has just been
supported by "the most accurate ex-
pertinent ever performed in physics"
involving measurement Of . change in
length of less than a biIionth Of an
inch.
Back at the turn of the century SCI
ence was in a quandry. Space was sup
posed to be filled by a queer substance
known as "ether," through which the
stars and planets moved and through
which light travelled. The earth pre-
sumsbly was rushing constantly through
this ether, which permeated all things.
Now, supposing two shots are fired
simultaneously from moving automo-
bile, one in the direction of motion and
the other at right angles to it. Sup
posing, furthermore, that both are
echoed back from points At equal dis
tances from the point At which they
were fired. The automobile is moving
to meet one returning echo. 1t is NOV
ing away from the other. Consequently,
the passengers should hear the echo OF
the shot fired in the direction of their
motion before they hear the other echo.
This would be true, at least, if sound
waves could be propagated in one direc-
ton only.
Consider two beams of light sent out
simultaneously from the same point in
the same way-one in the direction of
the earth's motion and the other at
right angles to it. The first should be
reflected back sooner because it has
less distance to travel. The earth is
rushing to meet the reflection. just as
the automobile is moving to meet the
echo.
It was difficult, however, to verify this
experimentally considering the enormous
speed of hght-nearly 200 600 miles 4
second-compared with any speeds OBJ
tainable on earth. The test was accom-
pliShed by the late Dr. A. A. Nicholson,
working with extremely sensitive appa-
ratus. He found that, within the limits
Of experimental error, the two beams of
light came back simultaneously.
This seemed to be q contradition of
the obvious. The experimental pro-
cedure, it was demonstrated, was logical
enough. 1t has been repeated many
times since and usually has resulted in
essentially the same findings. Various
theories were offered to resolve the para
dox. One Of the most celebrated was
the so-called Fitsgerald-Lorenz hypoth-
esis to the effect that the length of a
moving object automatically was Short
ened in the direction Of its motion-that
is. it was held the length OF the table
upon which DR.. Nicholson performed
his experiments contracted by the pre-
else amount necessary to make up for
the change in distance.
Another answer was the theory of
relativity. This could, to some extent,
be verified experimentally. The Fits
gerald-Lorenz hypothesis could not, be-
cause the dimensions involved were far
too minute for any known means of
measurement. If this explanation ever
could have been verified it would have
constituted serious-but not necessarily
fataEobjection to the Einstein theory.
Recently Drs. A. B. Wood and G.. A.
Tomlinson of the National Physical Lab
oratory, in Great Britain, which cOrre-
spends in some ways to the National
Bureau of Standards in the United
States, hit upon an experiment by which
the contraction effect, if it actually ex-
listed. might be verified. They have just
published their results in the proceedings
of the British Royal Society.
The outcome of their tests leaves the
theory of relativity apparently mistaken,
since the methods used would have per-
mitted detection of contraction much
lees than that called for BY the E1ts-
sefald.Ioren1 hypothesis. They do not