New-York tribune., 1920-06-13

Einstein's reported statement
that there were not more than
twelve men in the world who could
read and fully understand his book
was probably quite within the facts.
But the elementary ideas on which
the theory Of relativity is based do
not involve any difficult mathema-
tics, and the only obstacle to grasp
ing or holding them is their remark
able novelty. We can understand
them easily enough, or at least un-
derstand what they are about, if
only we begin at the beginning.
Our Complicated Movements
It probably has not occurred to
all of you that while / was speak
ing the last sentence we travelled
several hundred miles. Yet, of
course, we did. If we had not, the
earth would have left US behind it
somewhere in empty space.
In fact, we are undergoing very
complicated series of motions, car
ried around with the rotating earth
and swinging along much more ra-
pidly and in a much vaster curve
with it's orbital motion.
But of this fact we are blissfully
unconscious. Why? Because the
motion is perfectly smooth, without
jar or shock, and in particular be-
cause not merely we ourselves but
all the objects that constitute our
environment are moving together.
So we come to one Of the main
conceptions of the theory Of relativ
ity, the moving frame Of reference.
We ordinarily refer our measure
ments and indeed our notions Of dis
tance and of motion to some frame,
what the mathematician would call
some system Of co0rdinates, which,
SO to speak, is "tied" to some def
rite objects-ordinarily to that por-
ton of the earth's surface on which
we may have set ourselves or over
which we may be travelling at the
moment.
Though we and all our we'll in
formed ancestors for two centuries
have known very we'll that this
frame Of reference is not at rest but
is in rapid and intricate motion, we
are, nevertheless, still accustomed to
referring our motions to this moving
frame and saying that thing has
not budged when its position with
respect to the ground has not al
tered.
A Working Basis
And in doing this we not only fol-
low the promptings Of common
sense but find practical and work
ing basis for the scientific descrip-
ton of almost all terrestrial affairs.
But the moment we begin to look
off the earth into space things are
different. It then becomes obvious
that the earth is not at rest but NOV
ing, both on it's own axis and about
the sun.
say "obvious"; but it is worth
remembering that these facts-at
present so familiar even to the man
in the street-aroused, when their
truth was first advocated, the most
violent disbelief and agitation, and
that it took century or more Of
controversy to displace the old, in
nate belief in the fixity Of the earth,
that is, of our frame Of reference,
and substitute the belief that it was
II motion.
So far as our solar system goes
We may comfortably treat the sun
as being at rest and attach our
frame Of reference to it. But when
we come to look still further aheld
at the stars we find them in motion
and later detect a drifting tendency
among them which indicates beyond
question that our sun itself is
moving.
Sun Moving, Too
SO next we hitch our frame of
reference onto a sort Of average
position of all the stars visible to the
naked eye, and find that with re-
spect to this new frame Of reference
the sun and planets are moving at
the rate Of about twelve miles a
Eecond in definitely known direc-
tion.
We were content with this until
within the last decade, when obser-
vations upon the nebule, which we
know nov to be enormously further
cA than the naked eye stars, re-
Yealed extremely rapid motions.
II We try now TO hang frame of
reference, 70 to speak, to the
acreage OF these nebul@, it begins to
look AZ IL our solar system was
moving, compared with this, at q |