Einstein's Miraculous Year: Five Papers That Changed the Face of Physics

215 Pages·1998·2.14 MB·English

by  Albert Einstein

Einstein’s Miraculous Year
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Einstein’s
Miraculous Year
(cid:1)
Five Papers That Changed
the Face of Physics
EDITED AND INTRODUCED BY
John Stachel
WITH THE ASSISTANCE OF
Trevor Lipscombe, Alice Calaprice,
and Sam Elworthy
AND
WITH A FOREWORD BY
Roger Penrose
PRINCETON UNIVERSITY PRESS
Copyright©1998byPrincetonUniversityPress
PublishedbyPrincetonUniversityPress,41WilliamStreet,
Princeton,NewJersey08540
IntheUnitedKingdom:PrincetonUniversityPress,
Chichester,WestSussex
AllRightsReserved
LibraryofCongressCataloging-in-PublicationData
Einstein’smiraculousyear:fivepapersthatchangedthe
faceofphysics/editedandintroducedbyJohnStachel;
withtheassistanceofTrevorLipscombe,
AliceCalaprice,SamElworthy;
withaforewordbyRogerPenrose.
p. cm.
ISBN0-691-05938-1(cloth:alk.paper)
1.Physics—History—20thcentury. 2.Einstein,Albert,
1879–1955. I.Stachel,JohnJ.,1928– .
QC7.E52 1998
530.1—dc21 97-48441
ThisbookhasbeencomposedinCaledonia
PrincetonUniversityPressbooksare
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http://pup.princeton.edu
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CONTENTS
foreword, byRogerPenrose vii
publisher’spreface xv
introduction, byJohnStachel 3
PART ONE
Einstein’s Dissertation on the Determination of
Molecular Dimensions 29
Paper 1. A New Determination of Molecular Dimensions 45
PART TWO
Einstein on Brownian Motion 71
Paper 2. On the Motion of Small Particles Suspended in
Liquids at Rest Required by the Molecular-Kinetic
Theory of Heat 85
PART THREE
Einstein on the Theory of Relativity 99
Paper 3. On the Electrodynamics of Moving Bodies 123
Paper 4. Does the Inertia of a Body Depend on Its
Energy Content? 161
PART FOUR
Einstein’s Early Work on the Quantum Hypothesis 165
Paper 5. On a Heuristic Point of View Concerning the
Production and Transformation of Light 177
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FOREWORD
In the twentieth century, we have been greatly privileged
to witness two major revolutions in our physical picture of
the world. The first of these upturned our conceptions of
space and time, combining the two into what we now call
space-time, a space-time which is found to be subtly curved
in a way that gives rise to that long-familiar, omnipresent
but mysterious, phenomenon of gravity. The second of these
revolutions completely changed the way in which we under-
stand the nature of matter and radiation, giving us a picture
ofrealityinwhichparticlesbehavelikewavesandwaveslike
particles, where our normal physical descriptions become
subject to essential uncertainties, and where individual ob-
jects can manifest themselves in several places at the same
time. We have come to use the term “relativity” to encom-
pass the first of these revolutions and “quantum theory” to
encompass the second. Both have now been observationally
confirmed to a precision unprecedented in scientific history.
I think that it is fair to say that there are only three pre-
vious revolutions in our understanding of the physical world
that can bear genuine comparison with either. For the first
of these three, we must turn back to ancient Greek times,
wherethenotionofEuclideangeometrywasintroducedand
someconceptionwasobtainedofrigidbodiesandstaticcon-
figurations. Moreover, there was a beginning of an appreci-
ation of the crucial role of mathematical reasoning in our
insights into Nature. For the second of the three, we must
leap to the seventeenth century, when Galileo and Newton
vii
FOREWORD
told us how the motions of ponderable bodies can be under-
stood in terms of forces between their constituent particles
and the accelerations that these forces engender. The nine-
teenth century gave us the third revolution, when Faraday
and Maxwell showed us that particles were not enough, and
we must consider, also, that there are continuous fields per-
vading space, with a reality as great as that of the particles
themselves. These fields were combined into a single all-
pervasive entity, referred to as the electromagnetic field, and
the behavior of light could be beautifully explained in terms
of its self-propagating oscillations.
Turning now to our present century, it is particularly re-
markable that a single physicist—Albert Einstein—had such
extraordinarily deep perceptions of the workings of Nature
thathelaidfoundationstonesofbothofthesetwentieth-cen-
tury revolutions in the single year of 1905. Not only that,
but in this same year Einstein also provided fundamental
new insights into two other areas, with his doctoral disserta-
tion on the determination of molecular dimensions and with
his analysis of the nature of Brownian motion. This latter
analysis alone would have earned Einstein a place in his-
tory. Indeed, his work on Brownian motion (together with
the independent and parallel work of Smoluchowski) laid
the foundations of an important piece of statistical under-
standing which has had enormous implications in numerous
other fields.
This volume brings together the five papers that Einstein
published in that extraordinary year. To begin with, there is
the one just referred to on molecular dimensions (paper 1),
followed by the one on Brownian motion (paper 2). Then
come two on the special theory of relativity: the first initi-
ates the “relativity” revolution, now so familiar to physicists
viii
FOREWORD
(and also perceived by the public at large), in which the no-
tion of absolute time is abolished (paper 3); the second is a
short note deriving Einstein’s famous “E = mc2” (paper 4).
Finally, the (only) paper that Einstein himself actually re-
ferred to as “revolutionary” is presented, which argues that
we must, in some sense, return to the (Newtonian) idea that
light consists of particles after all—just when we had be-
come used to the idea that light consists solely of electro-
magnetic waves (paper 5). From this apparent paradox, an
important ingredient of quantum mechanics was born. To-
gether with these five classic Einstein papers, John Stachel
has provided fascinating and highly illuminating introduc-
tions that set Einstein’s achievements in their appropriate
historical settings.
I have referred above to the twentieth century’s two ex-
traordinary revolutions in physical understanding. But it
should be made clear that, fundamental as they were, Ein-
stein’s papers of 1905 did not quite provide the initial shots
of those revolutions; nor did these particular papers set out
the final nature of their new regimes.
The revolution in our picture of space and time that Ein-
stein’s two 1905 relativity papers provided concerned only
what we now call the special theory. The full formulation
of the general theory of relativity, in which gravitation is in-
terpreted in terms of curved space-time geometry, was not
achieved until ten years later. And even for special relativity,
the wonderful insights presented by Einstein in 1905 pro-
vided a theory that was not totally original with him, this
theory having been grounded in earlier ideas (notably those
of Lorentz and Poincare´). Moreover, Einstein’s viewpoint
in 1905 still lacked one important further insight—that of
space-time—introduced by Hermann Minkowski three years
ix