SubtleIsTheLord

Subtle is the Lord (Abe Pais)

  • Great history.
  • Einstein never stopped pondering the meaning of Quantum theory. He would always return to the QM and its interpretation. "I have thought 100 times as much about quantum problems as I have about general relativity theory"
  • Lorentz was the one father figure in his life. He claimed that without Lorentz he would never have been able to discover special relativity.
  • Special Relativity brought clarity to old physics (E&M, the ether) and created new physics E=mc2
  • Einsteins one revolutionary contribution to physics was his assumption that light, in its coupling to matter, is created and destroyed in discrete particles of energy. Never was a proposal for a new fundamental particle resisted more strongly than this one for the photon. No one resisted the photon longer than Bohr. All resistance came to an end when experiments on the scattering of light by electrons (the Compton effect) proved Einstein was right. QM was born within a few months of settling the photon issue.
  • Einstein never had a good word for QFT.
  • In all the history of physics there has never been a period of transition as abrupt, unanticipated and over a wide front as the decade from 1895 to 1905. X-rays (1895), Zeeman effect (1896), radioactivity (1896), the electron (1897) the extension of IR spectroscopy into the 3mu to 60um region (critical for the study of black-body radiation).
  • When SR appeared it was at once all there. There was no "old" relativity. By contrast "old" QM, developed from 1900 to 1925, progressed by unprincipled, but tasteful, invention and application of ad hoc rules rather than by a systematic investigation of a set of axioms.
  • Its remarkable that the old quantum theory would originate from something as complex as black-body radiation. Long before anyone knew what the principles of the quantum theory where, the successes of the black-body radiation (and the the heat capacity) made it evident that such a theory had to exist.
  • The main virtue of the relativistic velocity addition formula is that it simultaneously answers two questions: where does the new begin ? where does the old fit in? The presence of the new indicates a clear break with the past. The immediate recognizablity of the old shows that this break is an "orderly transition".
  • Einstein could be radical, but he was not a rebel.
  • Einstein developed theoretically three independent methods for finding Avogadro's number. With Brownian motion, the conclusion is that Avogadro's number can be determined from observations with a an ordinary microscope.
  • All of Einsteins principle contributions to QM are statistical in nature.
  • He could be very enthusiastic about his own ideas and then, when necessary, drop them some time later without any pain, as being of no consequence.
  • Boltzmann's grave is marked by the monument on which the formula S=klogW is written. Boltzmann never wrote this equation. Planck did. k was introduced by Planck not Boltzmann.
  • The insight that the second law of thermodynamics can be understood only in terms of a connection between entropy and probability, is one of the great advances of the 19C.
  • Until 1913, the days of the Bohr atom, all evidence for quantum phenomena came either from black body radiation or from specific heat, where statistical consideration play a key role.
  • Birth of modern chemistry John Dalton "New system of chemical philosophy": Summary all modes of matter are reducible to a finite number of atomic species (18 elements were known at the time).
  • The principle debate among chemists was whether atoms were real objects or only mnemonic devices for coding chemical regularities and laws.
  • Avogadro's law is the oldest of those physical-chemical laws that rest on the explicit assumption that molecules are real things.
  • Some older chemists of high authority referred publicly to the atomic theory as something they would glad to dispense with, and which they are ashamed of using. They seemed to look upon it as something distinct from the general facts of chemistry, and something which the science would gain by throwing off entirely… On the one hand, all chemists use the atomic theory, and .. on the other, a considerable number view it with mistrust, some with positive dislike. IF the theory really is as uncertain and unnecessary as they imagine it to be, let its defects be laid bare and examined. see Everett QM
  • The issue of atoms was settled once and for all b/c of the extraordinary agreement in the values of N obtained by many different methods. Matters were clinched not by a determination, but by an over determination of N. From subjects as diverse as radioactivity, Brownian motion, and the blue in the sky, it was possible to state by 1909, that a dozen independent ways of measuring N yielded results all of which lay between 6-9 1023.
  • Michelson, a genius in instrumentation and experimentation, never felt comfortable with relativity.
  • In the early days its was easier to understand the math of relativity than the physics.
  • Relativity: The one preferred coordinate system in absolute rest is forsaken. Its place is taken by an infinite set of preferred coordinate systems, the inertial frames. By definition any two of these are in uniform motion with respect to each other. The preference for uniformity of relative motion makes this version of relativity a special one.
  • The addition of velocity theorem should be taught in high schools as the simplest example of the ways in which modern physics goes beyond everyday intuition.
  • Thomas procession: it seemed unbelievable that a relativistic effect could give a factor of 2 instead of something of order v/c… Even the cognoscenti of the relativity theory (including Einstein) were quite surprised. The heart of the effect is the fact that a Lorentz transformation which velocity v1 followed by a second one with velocity v2 in a different direction does not lead to the same inertial frame as one single LT with velocity v1 + v2.
  • Twin paradox: as Einstein himself explained some time later, the logic of SR does not suffice for the explanation of the phenomena since frames other than inertial ones come into play.
  • In 1934 Einstein gave the Gibbs lecture in Pittsburgh and deduced E = mc2 from the validity in all inertial frames of energy and mom. conservation for a system of point like particles.
  • Minkowski published a detailed paper in which for the first time the Maxwell-Lorentz equation are presented in their modern tensor form. Terms like space-like vector, time-like vector light code and world line stem from this paper.
  • Relativity turned Newtonian mechanics and classical chemistry into approximate sciences, not diminished but better defined in the process.
  • Einstein re politics: "Why should one not be able to live contentedly as a member of the service personnel in the lunatic asylum? After all one respects the lunatics as the one for whim the building in which one lives exists"
  • Einstein read a paper on behalf of Karl Schwarzschild who was in the German army at the Russian front at the time. The paper contained the exact solution of the static isotropic gravitational field of a mass point, the first instance of a rigorous solution of Einsteins full field equations. Einstein read another paper introducing the Schwarzschild radius. Schwarzschild died shortly there after from illness on the Russian front.
  • Non-relativistic theories contain not only statements about things but also statements which refer to things and the coordinate systems which are needed for their description; from a logical point of view such a theory is less satisfactory than a relativistic one, the content of which is independent of the choice of coordinates.
  • The clearest expression of Einsteins profound belief in a description of the world exclusively in terms of everywhere-continuous fields. "In E&M the continuous field appears side-by-side with the material particle as the representative of physical reality. This dualism, though disturbing to any systematic mind, has today not yet disappeared. Since Maxwell's time, physical reality has been thought of as being represented by continuous fields, governed by partial differential equations, and not capable of any mechanical interpretation… It must be confessed that the complete realization of the program contained in this idea has so far by no means been attained. The successful physical systems that have been set up since then represent rather a compromise between these two programs (Newtons and Maxwell's) and it is precisely this character of compromise that stamps them as temporary and logically incomplete, even thought in their separate domains they have led to great advances".
  • In the divorce Mileva would received all of Einsteins Nobel prize money.
  • Several quirks of history save Einstein from the embarrassment of banking on his wrong result. An Argentinian eclipse expedition had gone to Brazil in 1912 and was rained out. In 1914 a German expedition headed for the Crimea to observe the eclipse of August. When war broke out the part had to return home.
  • "Dont be too hard on me. Everyone has to sacrifice at the altar of stupidity from time to time." - Einstein
  • Not until 1919 did scattering experiments give a first intimation that all was not electrical. Not until 1921 did experiments show that the 1/r2 force law beaks down at small distances. James Chadwick stated the need to find these strong forces first. This was his 2nd great discovery the first was that the beta spectrum was continuous.
  • Nuclear physics began with a nucleus without neutrons, beta decay without neutrinos. Matter was made of protons and electrons. there were neither strong nor weak interactions. In the beginning there was only E&M and gravitation. This was the natural setting for Einstein when he started his unified field theory.
  • Then it came to pass that physics veered toward a different course, neither led nor followed by Einstein. First QM then QFT took center stage.
  • Einstein had three distinct motivations for generalization of GR. 1) to join gravity with E&M. 2) obtain singularity-free solutions of the source-free general relativistic field equations which could represent particles. 3) explain the quantum theory
  • The last four months of 1859 changed the course of science:
    • Announcement of the unexplained advance of the perihelion of Mercury.
    • Origin of Species is published
    • Kirchhoff challenged scientists to explain the black-body radiation.
  • Einsteins view that the quantum theory is provisional in nature. The persistence of this opinion of Einstein is one of the main themes of this book.
  • From 1900 to 1905 Planks formula was generally considered to be neither more nor less that a successful representation of the data. Only in 1905 did it begin to dawn, and then only on a few, that a crisis in physics was at hand.
  • Five experimental observations made within the space of one decade shaped the physics of the 20C.
    • photoelectric effect
    • X-rays
    • radioactivity
    • the Zee-man effect
    • the electron
  • The photoelectric effect was the "second coming of h" The equation made very new and strong predictions. E should vary linearly with nu. The slope of (E,v) is a universal constant, independent of the nature of the irradiated material.
  • Planks reasoning alleged to involve only a modification of the interaction between matter and radiation. This did not seem too outlandish, since the interaction problem was full of obscurities in any event. By contrast, when Einstein proposed the photon he had dared to tamper with the Maxwell equations for free fields, which were believed (with good reason) to be much better understood.
  • The first three revolutionary papers on QM: Plank, Einstein and Bohr
  • Physicists – good physicists – enjoy scientific speculation in private but tend to frown upon it when done in public. They are conservative revolutionaries, resisting innovation as long as possible and at all intellectual cost, but embracing it when the evidence is incontrovertible.
  • Until 1906 Planck's quantum had played a role only in the rather isolated problem of black-body radiation. Einsteins work on specific heats is above all important b/c it made clear for the first time that quantum concepts have a far more general applicability.
  • "That this insecure and contradictory foundation of physics in the years 1910 to 1920 was sufficient to enable a man of Bohr's unique instinct and tact to discover the major laws of the spectral lines and of the electron shells of the atoms together with their significance for chemistry appeared to me like a miracle – and appears to me as a miracle even today. This is the height form of musicality in the sphere of human thought" – Einstein
  • With Bose's paper two new ideas enter physics almost stealthily. One, the concept of a particle with two states of polarization, mildly puzzled Bose. The other is the non-conservation of photons.
  • Schrodinger retained reservations on the interpretations of QM for the rest of his life.
  • After 1933 it was his almost solitary position that QM is logically inconsistent but that it is an incomplete manifestation of an underlying theory in which an objectively real description is possible.
  • "Momentary success carries more power of conviction for most people that reflections on principle" – Einstein

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