Every evening, Wilmington daily commercial., 1921-04-19
EINSTELN EXPLAINS HIS
THEORY OF RELATIVELY
Everything in the Universe Always Moving and the Relation
Everything Else is Constantly Changing Says That
Only Change is Permanent.
From the New York World.


Giving his frat address on scien-
tiilc subject Prof. Albert Etnstein,
who came TO America In the interests
of Zlonism. spoke for nn hour yes
terday afternoon to an audience of
about five hundred Columbia Univer-
sity professors and students In the
auditorium Of tho Horace Mann
School. t20th Street and broadway;
lie was introduced ms a former pro-
fcssor at tho University OF Zurich
and professor ut present In the Uni
versity of Leyden by Prof. Pupin OF
Columbia, who announced that the
topic of his address would hc the
much discussed theory of reiatiVity
Prof. flnstein. who spoke through
out I'm German. began by saying that.
though the theories of space. time.
matter and force which created such
sensation when first enumerated,
and apparently confirmed 10y the oh
scrvation made during an eclipse of the
sun, that light rays follow curved paths
instead Of travelling invariably in
straight lines. had been called revo-
lutionary. they were in reality only
evolutionary They marked. he be-
lievcd. a process of growth.
Old Theories Remain Good.
New stories were to be added to the
structure of physical science. but the
foundations were still the same. Much
of the physics Of Newton the as
tronomy of Calico and kcpler re-
mained good physics and astronomy.
Partly because of the difficulty of
language. partly because of the ab-
strusenesa of the matter under discus
sion. Prof. Einsteln spoke to al
ffFt nfaHfqnrn He
brought the first instant Of relief from
the tension when. in dismisaing the
preliminary phase of his discussion. he
said:
What | have been describing Is
the special theory Of relatively. II
IL really very simple. because II takes
into consideration only the changing
relations Of two moving factors. II
everything else stood still. Whereas
everything in the universe is always
moving. and the relations Of everything
else are constantly changing.
Herer at last, after more than half
an hour Of listening was something
which il seemed the hearers. az a group
could grasp The assertion brought
from most Of them something like "A
gasp of ast0nshment The older ply
steal conception of the universe. In which
they had grown up had treated mat
| ter and forces as almost tangible things
set in fixed rca tions' And here was
Prof. Einstein stating hia belief that
only change is permanent. and that the
only essential quality OF matter II the
shifting relation of points IN 1t to each
other.
Not BASED on Hypothesis.
The theory Of relatively. he said. is
based not on hypothesis. but on ac-
! tually observed phenomena. TO un-
| derstand It. one must first understand
the principles on which Il IL based
And at the beginning. ne added. it is
| necessary to understand that the theory
IL hko house with two stories. The
| special relatively theory and the gen
/ eral relauvity theory must be con
! sidered separately.
| The only way 10 describe the mo-
| ton Of a body. he went on. is by
reference 70 another body. as the mo-
/ ton Of a train Is described with ref
erence to the ground. IN physics. the
bodies TO which motions are specially
referred are termed systems OF CO.
/ ordinates. the reference Of the motion
/ OF a planet to the earth's celestial
merdians and equator being very
simple Illustration.
Systems OF co-ordinates. just Ike
| their bodies. move. But If there Is
no twisting or acceleration. the NOV
ing coordinate system IS in itself IN
"A state OF inertia. And the first prla-
! ciple Of the special relatively theory
is that any law Of nature which holds
good with respect to one co-ordiuate e
system must also hold good for any
other similar coordinate system. pro
vided both systems are in uniform
| movement.
Coupled with this IS the second prin-
ciple of the constant velocity OF light
in a vacuum. Light in vacuum has
a constant and definite velocity inde-
| pendent of the velocity of its source
/ Hating at this point to discuss
velocity. Prof. Einstein pointed out that
there can be no such thing as alb
solute time. distance. or mass. or that
at least there can be no possib bihty OF
measuring them. If two observers are