PREFACE
A
distinguished German authority on mathematical physics, writing
recently on the theory of Relativity, declared that if his
publishers
had been willing to allow him sufficient paper and print he could
have explained what he wished to convey without using a single
mathematical formula. Such success is conceivable. Mathematical
methods present, however, two advantages. Their terminology is
precise and concentrated, in a fashion which ordinary language
cannot
afford to adopt. Further, the symbols which result from their
employment have implications which, when brought to light, yield
new
knowledge. This is deductively reached, but it is none the less new
knowledge. With greater precision than is usual, ordinary language
may be made to do some, if not a great deal, of this work for which
mathematical methods are alone quite appropriate. If ordinary
language can do part of it an advantage may be gained. The
difficulty
that attends mathematical symbolism is the accompanying tendency to
take the symbol as exhaustively descriptive of reality. Now it is
not
so descriptive. It always embodies an abstraction. It accordingly
leads to the use of metaphors which are inadequate and generally
untrue. It is only qualification by descriptive language of a wider
range that can keep this tendency incheck.
A new school of mathematical physicists, still, however, small in
number, is beginning to appreciate this.But
for English and German writers the new task is very difficult.
Neither Anglo-Saxon nor Saxon genius lends itself readily in this
direction. Nor has the task as yet been taken in hand completely,
so
far as I am aware, in France. Still, in France there is a spirit
and
a gift of expression which makes the approach to it easier than
either for us or for the Germans. Lucidity in expression is an
endowment which the best French writers possess in a higher degree
than we do. Some of us have accordingly awaited with deep interest
French renderings of the difficult doctrine of Einstein.M.
Nordmann, in addition to being a highly qualified astronomer and
mathematical-physicist, possesses the gift of his race. The Latin
capacity for eliminating abstractness from the description of facts
is everywhere apparent in his writing. Individual facts take the
places of general conceptions, of
Begriffe. The
language is that of the
Vorstellung, in a
way that would hardly be practicable in German. Nor is our own
language equal to that of France in delicacy of distinctive
description. This book could hardly have been written by an
Englishman. But the difficulty in his way would have been one as
much
of spirit as of letter. It is the lucidity of the French author, in
combination with his own gift of expression, that has made it
possible for the translator to succeed so well in overcoming the
obstacles to giving the exposition in our own tongue this book
contains. The rendering seems to me, after reading the book both in
French and in English, admirable.M.
Nordmann has presented Einstein’s principle in words which lift the
average reader over many of the difficulties he must encounter in
trying to take it in. Remembering Goethe’s maxim that he who would
accomplish anything must limit himself, he has not aimed at
covering
the full field to which Einstein’s teaching is directed. But he
succeeds in making many abstruse things intelligible to the layman.
Perhaps the most brilliant of his efforts in this direction are
ChaptersVand VI,
in which he explains with extraordinary lucidity the new theory of
gravitation and of its relation to inertia. I think that M.
Nordmann
is perhaps less successful in the courageous attack he makes in
his third chapteron
the obscurity which attends the notion of the “Interval.” But
that is because the four-dimensional world, which is the basis of
experience of space and time for Einstein and Minkowski, is in
itself
an obscure conception. Mathematicians talk about it gaily and throw
its qualities into equations, despite the essential exclusion from
it
of the measurement and shape which actual experience always in some
form involves. They lapse on that account into unconscious
metaphysics of a dubious character. This does not destroy the
practical value of their equations, but it does make them very
unreliable as guides to the character of reality in the meaning
which
the plain man attaches to it. Here, accordingly, we find the author
of this little treatise to be a good man struggling with adversity.
If he could make the topic clear he would. But then no one has made
it clear excepting as an abstraction which works, but which,
despite
suggestions made to the contrary, cannot be clothed for us in
images.This,
however, is the fault, not of M. Nordmann himself, but of a
phaseof
the subject. With the subject in its other aspects he deals with
the
incomparable lucidity of a Frenchman. I know no book better adapted
than the one now translated to give the average English reader some
understanding of a principle, still in its infancy, but destined,
as
I believe, to transform opinion in more regions of knowledge than
those merely of mathematical physics.Haldane
INTRODUCTION
This
book is not a romance. Nevertheless.... If love is, as Plato says,
a
soaring toward the infinite, where shall we find more love than in
the impassioned curiosity which impels us, with bowed heads and
beating hearts, against the wall of mystery that environs our
material world? Behind that wall, we feel, there is something
sublime. What is it? Science is the outcome of the search for that
mysterious something.A
giant blow has recently been struck, by a man of consummate
ability,
Albert Einstein, upon this wall which conceals reality from us. A
little of the light from beyond now comes to us through the breach
he
has made, and our eyes are enchanted, almost dazzled, by the rays.
I
propose here to give, as simply and clearly as is possible, some
faint reflex of the impression it has made upon us.Einstein’s
theories have brought about a profound revolution in science. In
their light the world seems simpler, more co-ordinated, more in
unison. We shall henceforward realise better how grandiose and
coherent it is, how it is ruled by an inflexible harmony. A little
of
the ineffable will become clearer to us.Men,
as they pass through the universe, are like those specks of dust
which dance for a moment in the golden rays of the sun, then sink
into the darkness. Is there a finer or nobler way of spending this
life thanto
fill one’s eyes, one’s mind, one’s heart with the immortal, yet
so elusive, rays? What higher pleasure can there be than to
contemplate, to seek, to understand, the magnificent and astounding
spectacle of the universe?There
is in reality more of the marvellous and the romantic than there is
in all our poor dreams. In the thirst for knowledge, in the mystic
impulse which urges us toward the deep heart of the Unknown, there
is
more passion and more sweetness than in all the trivialities which
sustain so many literatures. I may be wrong, after all, in saying
that this book is not a romance.I
will endeavour in these pages to make the reader understand,
accurately, yet without the aid of the esoteric apparatus of the
technical writer, the revolution brought about by Einstein. I will
try also to fix its limits; to state precisely what, at the most,
we
can really know to-day about the external world when we regard it
through the translucent screen of science.Every
revolution is followed by a reaction, in virtue of the rhythm which
seems to be an inherent and eternal law of the mind of man.
Einstein
is at once the Sieyès, the Mirabeau, and the Danton of the new
revolution. But the revolution has already produced its fanatical
Marats, who would say to science: “Thus far and no farther.”Hence
we find some resistance to the pretensions of over-zealous apostles
of the new scientific gospel. In the Academy of Sciences M. Paul
Painlevé takes his place, with all the strength of a vigorous
mathematical genius, between Newton, who was supposed to be
overthrown, and Einstein. In my final pages I will examine the
penetratingcriticisms
of the great French geometrician. They will help me to fix the
precise position, in the evolution of our ideas, of Einstein’s
magnificent synthesis. But I would first expound the synthesis
itself
with all the affection which one must bestow upon things that one
would understand.Science
has not completed its task with the work of Einstein. There remains
many a depth that is for us unfathomable, waiting for some genius
of
to-morrow to throw light into it. It is the very essence of the
august and lofty grandeur of science that it is perpetually
advancing. It is like a torch in the sombre forest of mystery. Man
enlarges every day the circle of light which spreads round him, but
at the same time, and in virtue of his very advance, he finds
himself
confronting, at an increasing number of points, the darkness of the
Unknown. Few men have borne the shaft of light so deeply into the
forest as has Einstein. In spite of the sordid cares which harass
us
to-day, amid so many grave contingencies, his system reveals to us
an
element of grandeur.Our
age is like the noisy and unsubstantial froth that crowns, and
hides
for a moment, the gold of some generous wine. When all the
transitory
murmur that now fills our ears is over, Einstein’s theory will rise
before us as the great lighthouse on the brink of this sad and
petty
twentieth century of ours.