The New York herald., 1921-04-22

along the line time then you are In the
future: il In the opposite direction, then
you are in the past' So iEforms US
the novelist Wells ''and to the man in
the street." said Prof. Einstein, "the
theory of relativity consists I'm the dis
covery Of the fourth dimension" OF
course. MinkowslSi's method of analysis
merely put a powerful tool in the hands
of Einstein.
The special or earlier theory had
drawbacks. To begin with. II ignored
that most universal property OF matter
--gravitation. Then again II dealt only
with motions In a certain direction. But
for theory to be universally applicable
1t must include all rlotions---lt must re-
gard all motions as equivalent. ana II
must include gravitational phenomena.
In this way we are Inevitably led to .he
general theory. In contradistinctlon 70
the special theory Of relatively.
The mathematical details involved in
the development of the general theory
were hardly touched upon by Prof Elm
stein. And well ii was that he did not !;
for outside OF Prof. Kastner OF So'um-
bia, and perhaps Prof, conen of City
College, and few others wh,se fame
has not reached me, I could think of
none In that audience who could have
followed him with very much profit.
The Origin Of Gravitation.
Gravitational effects, according to
E,instein, may be regarded as being due
to accelerated motions. If we are I'm a
train and 1t starts moving the result on
US is q sudden push backwards. Now
imagine such body as the train con-
stantly changing its velocity Exhibiting
what we call an accelerated motion).
and imagine still further that it Is NOV
ing vertically, upwards instead of hori-
zontally; and yet again. imagine this
train so situated In space that II Is
completely removed from any other
body so that no gravitational effects
are possible. A man In this train will
notice bodies falling TO the ground just
as they do on the earth, and this simply
because the train Is moving upward with
an accelerated motion.
Prof Einstein next introduced his
sudience to consideration OF rotary
motions, the outcome OF which was
to show that only non-euclidian
mathematics would satisfy all the
requirements. Here again E1instein was
helped considerably by the work Of
Gauss, who had developed the mathe-
matical technique of spherical or non
euclidian surfaces.
stein finally deduced proved itself to be
more comprehensive than the Newtonian
equation, for, unlike the latter. 1t could
Predict the extent or the bending Of q
ray of light coming from a fixed star
and passing near a huge body like the
sun. Furthermore. 1t explained to a
nicety the motion or mercury. Not the
least important in the Einstein equation
Is that. provided the velocities are small
as compared to light. it reduces itself
to Newton's law.
The third requirement of the theory,
the shdfting or spectral lines, has not yet
been verified Such is the sublime con-
fidence of Einstein In his theory that,
as he told his audience. my theory
either stands or falls on the result Of
this test"
Universe Shaped Like a Spheroid.
In concluding his third lecture Prof.
Einstein lightly touched upon q fairly
logical outcome of the relativity theory,
namely that the universe Is really finite /;
that 1t Is probably shaped In the manner
of a spheroid.
The fourth and last lecture dealt with
the quantum theory, the "schmertzens-
kind" (the child OF sorrows) OF physics,
as Einstein humorously described It..
This quantum theory is really not Elm
STEMS at all, but Planck-s-another one
of those extraordinary physicists at the
university OF Berlin. The idea underly-
ing "quantum'' Is that radiations-say
light radiations---are not sent out In con-
tinuous streams. but in small units
called ''quanta.' These 'quanta,"
though smaller than electrons have def
mite weight and are of quite a funda-
mental nature. The theory has been
applied with a great measure of success
70 spectrum analysis