This really is a very, very good book. One really gets a feeling for the a) "personalities" of the players; b) relationships among the players; c) the development of the theory. And because of the way it is written, the information tends to be "sticky."
1913: Bohr -- solved the problem of the "stable" atom
1925: Max Born (Gottingen), a mathematician, coined "quantum mechanics" and Heisenberg/Pauli would "produce" it.
1926: things starting to move a bit faster. Heisenberg, particles; Schrodinger, waves; Max Born, putting the two together. Heisenberg says Dirac, through mathematics, has made quantum mechanics as complete as relativity. Bohr frustrated with Schrodinger.
1927: Solvay.
1931: the year of Einstein's box and the particle. Well on the way to EPR. Podolsky and Rosen both coming of age.
1932: split the atom. 1932 a most momentous year for other reasons. Heisenberg called it the golden year of physics, 40 years later.
1933: everything started to fall apart; dispersed, as Hitler came to power
***********************
Miscellaneous Observations
1913: Bohr, 28 y/o; solved the problem of the stable atom; quantum leaps; gave off light (p. 33) -- so, in one paper, many breakthroughs.
1923: a conversation on a streetcar in Copenhagen between two of the founders of the quantum theory, Albert Einstein and Niels Bohr, and its first great teacher, Arnold Sommerfeld: all three were depressed over the challenges of quantum. Einstein: "The theory of relativity was only a sort of respite which I gave myself during my struggles with the quanta." -- wow.
*******************************
Miscellaneous Observations, Continued
Quantum leaps were unsettling in the new theory, but so was the concept of frequency. Frequency of an electron is not the same as frequency in the classical sense. In Bohr's atom (p. 34), the frequency of the electron's orbit is not the same as the frequency of the light it emits. Incredibly, it is a single, pure frequency, equal to the difference between the energies of the starting and ending orbits (divided by Planck's constant, h) -- as if the electron, radiating the light, already knew where it was going to stop.
***********************
1920s: Einstein, Sommerfeld, and Bohr in frequent communication
Sommerfeld: supervised the PhD theses of four future Nobel laureates
- Heisenberg
- Pauli
- Debye, molecular structure using x-rays; Miller's Deciphering The Cosmic Code, p. 109
- the fourth?
The Arguments: 1909 - 1935
The Search and the Indictment: 1940 - 1952
The Discovery: 1952 - 1979
Entanglement Comes of Age: 1981 - 2005
Introduction: Entanglement
- EPR, 1935: Einstein-Podolsky-Rosen -- most cited Einstein paper; most cited paper in Physics Review
- John Stewart Bell: resurrected the EPR paper in 1964; cited as much as the EPR paper
- Bell: "briefly and beautifully demonstrated the utter lack of any commonsense mechanism to correlate these entangled particles."
Entanglement emerged early in quantum mechanics: "but it was Bell, with his simple algebra and deep thinking, who laid open the central paradox."
Four groups:
- orthodox: three of the founders of QM (Bohr, Heisenberg, Pauli) -- the Copenhagen interpretation
- heretics: something "rotten" in QM (Einstein, Schrodinger, de Broglie)
- pragmatic: time is not yet ripe for understanding
- confused: dismissed the mysteries with simplistic explanations
- The Copenhagen Interpretation (p. 5): Bohr ("complementarity" of waves); most enthusiastic support: Heisenberg; best critic: Pauli. Pauli would go so far as to say that "atoms had no properties before being measured."
- Something is rotten (p. 6): nine years after quantum theory's tentative debut, Einstein started worrying about "spooky action-at-a-distance"
- The time is not ripe (p. 6): Paul Dirac -- "his equation describing electrons was one of the most astonishingly powerful results of quantum theory; he felt it was too soon to be wasting time worrying about entanglement. It would make sense someday.
- Dismissive incomprehension (p. 6): Max Born -- "a lifelong friend of Einstein's and contributor to the Copenhagen interpretation, could never understand why the others thought the meaning of the theory was such an important and difficult issue."
After the 1930's it seemed clear that the analyses of Einstein, Schrodinger, and de Broglie were dead ends, and, in fact, most of the great and lasting triumphs of the quantum theory did come from one of the other schools of thought.
But no one following Bohr, Heisenberg, Pauli, Dirac, or Born dared grasp, measure, or even name the deepest of all the puzzles, entanglement. Then along came John Bell. An admirer of Einstein, Schrodinger, and de Broglie, he followed their minority views to their natural conclusions and brought unexpected clarity where before there had been fog. And what the fog had been hiding was vividly and wonderfully strange.
pic: John Stewart Bell
The age of entanglement <--> John Stewart Bell
Reinhold Bertlmann -- contemporary of Bell's (1978, they met)
1909 - 1945
Albert Einstein and Paul Ehrenfest, 1920
Niels Bohr: fin de siecle (b. 1885); age 26 in 1911; he had come to study with JJ Thomson at Cavendish Laboratory, Cambridge. One of JJ's students was Rutherford, who was now at Manchester. Rutherford and Niels Bohr become fast friends.
Section One of Four Sections In The Book
The Arguments
The Arguments
Chapter 1
The Socks
1978 and 1981
pic: Reinhold Bertlmann
1978: John Bell first met Reinhold Bertlmann, CERN, near Geneva
I will come back to this chapter.
Chapter 2
Quantized Light
September 1909 - June 1913
Einstein's contributions early on.
At the first conference he attended,
At the first conference he attended,
Einstein stepped in, describing what he would later call his Gespensterfelder -- ghost waves. An electron, he noted, is surrounded by an electric field, and each quantum might similarly emanate a field through which these ghost waves would ripple. On this hopeful note the meeting ended.
In the ensuing years Einstein tried to make this separable, one-wave-per-particle description work. The reason for the failure of this idea would slowly emerge over the decades with ever-greater clarity: entanglement, where two particles are not really separable because a single wave describes them.
A short biographical sketch of Ehrenfest: never felt at home in Russia; wife, a Russian physicist; suffered from depression -- p. 30.
1905: Einstein: light or particle?
1908 / 1909:
- Einstein: Switzerland, Zurich
- Lorentz: Holland, Leiden
- Max Planck: Germany, Berlin
Planck: to get the correct formula
had to count energy iinn "quanta" -- p. 26
quanta = hv
v = color, frequency
h = tiny, new constant
then in 1905: Einstein discovered more about quanta; bottom of page 26!!!
Everyone depending on Boltzmann (Vienna)
62 y/o: crazy, suicide, 1906
student: 25 y/o Paul Ehrenfest
the UV catastrophe!! -- p. 27
Only over concerned -- 1908
Einstein, Planck, Lorentz, Ehrenfest
Einstein, 1909
working theory of liight -- how to fuse wave / particle
top of p. 29: what Planck's formula meant!!!
Johannes Stark -- p. 28
p. 29: key page: 1909 - 1913
what physicists were seeing was downright bizarre; absolutely not explainable
defied anything they had seen before
at its simplest -- truly seeing what looked like particles but experimentally also wave-like phenomena
1913:
Zurich: Einstein, Ehrenfest, Max von Laue
1912:
von Laue's spectacular discovery -- Munich
CuSO4 diffracts x-rays
like the double-slit experiment? is that what Gilder is describing?
von Laue: student of Planck
24 y/o: Laue and Einstein
Laue and Ehrenfest moved to Zurich to be near Einstein
Laue: Prussian
Ehrenfest: Russian
Ehrenfest: heard Lorentz in 1903
Chapter 3
The Quantized Atom
November 1913
pic: Niels Bohr
Otto Stern and Max von Laue talking about the subject du jour: the atom
Ever since it became clear in 1911 that the atom was something like a tiny solar system (its sun the positively charged nucleus, exerting a constant electrical pull on its planets, the negatively charged electrons), there were problems. A charged object like an electron is inseparable from the electric field it emanates; if it moves, it generates a magnet field, too; and if it changes its speed (speeding up, slowing down, or turning), that change makes a wave in the electric and magnetic fields surrounding it. This electromagnetic wave is what we call light. The electrons, charged and orbiting the heart of the atom, should be making constant light-wave ripples in their electromagnet fields, leaking energy with each wave until every atom in the universe goes flat like a punctured tire. This, of course, does not happen.
And here is where Niels Bohr -- 1913 -- 28 y/o -- comes into play:
one year in Manchester -- had illogical explanation
light from e- only when it made a quantum jump
really, really bizarre!!
In 1913, a few weeks before Stern and von Laue climbed the Uetliberg, the theoretical problem of the inexplicably stable atom had been declared solved by an unknown 28-y/o Danish physicist, Niels Bohr, just returned home to Copenhagen after a year in Manchester, England (where he had studied with Rutherford, a student of JJ Thomson, Cavendish Laboratory, Cambridge).This was the explanation:
It had taken him 71 dense pages, and his explanation was illogical. Rather than radiating light all the time, Bohr said, the electrons would emit light only when they made a kind of ineffable transition (the famous "quantum jump"). These jumps or leaps were nothing like the smooth bounding of a cat. They were a baffling, quantized, all-or-nothing disappearance in one orbit and emergence in another -- like Earth suddenly materializing in the orbit of Mars.And one more quote:
The quantum leaps alone were like nothing that had ever happened in a physical theory before, but just as unsettling was the frequency of the light that the leaping electron emitted. -- p. 34
frequency - cycle
frequency: number of passes / time
e.g., one cycle / sec
p 34: but frequency of the e- -- not the frequency of light it emits
frequency of light = (orbit [energy] - orbit [energy]) / h
The Rydberg constant:
The Rydberg constant had been for 30 years an unexplained number in the equation predicting the colors of light each element of the periodic table might emit. Bohr's preposterous theory had accidentally and effortlessly yielded this heretofore arbitrary number, producing meaning where before there had only been mandate. -- p. 34
The Rydberg constant: each element emits a specific light;
Rydberg constant predicts the frequency
Bohr --> Cambridge, Caveendish, JJ Thomson, 1911
--> Manchester, Rutherford -- atomic nucleus (1911)
Bohr explained his atomic theory to Rutherford, 1912
Bohr re-discovered Balmer, 1885 -- Basel, Switzerland
-- predicted yet unseen spectral lines
-- Fraunhofer / Melvill --
-- Melvill: emission spectrum -- leaping inward; to lower state; losing energy by emission of light
-- Fraunhofer: absorption spectrum -- just the opposite; leap to higher energy state;
See bottom of p. 38.
A short history of the atom -- p. 35. Melvill, a Scot. Gustav Kirchhoff, U of Heidelberg; Bunsen burner, spectroscopy.
Spectroscopy; discovery of helium.
Short biographical sketch of Niels Bohr. Father: nominated several times for Nobel Prize in medicine. In 1913, published his paper. Stern and van Laue vowed to give up physics if Bohr was right. -- p. 37 - 38. Ehrenfest won over by the theory in 1919.
Ehrenfest loves Bohr's theory, p. 34.
-- according to Einstein writing to his lifelong friend Max Born 99 they met at Einstein's speech, Sallzburg)
Chapter 4
The Unpicturable Quantum World
Summer 1921
pic: Werner Heisenberg
Bohr: his atomic model solved the problem of the stability of the atom. Bohr succeeded in associating the strange stability of atoms with Planck's quantum hypothesis, which had not yet been properly interpreted either.
Begins with conversation among: Heisenberg, Pauli, and Laporte. Note: Heisenberg and Pauli join Bohr in the triad with the Copenhagen interpretation (see above)
Begins with conversation among: Heisenberg, Pauli, and Laporte. Note: Heisenberg and Pauli join Bohr in the triad with the Copenhagen interpretation (see above)
Remember: Bohr published his paper in 1913; Ehrenfest won over in 1919; and, now this is 1921 with Pauli and Heisenberg.
Arguing over whether electrons really orbit within the atom.
The three were in Munich studying under Max von Laue's friend and former colleague, Arnold Sommerfeld. Heisenberg, 19. Pauli, nearly 21. Laporte, just arrived, just ready to turn 19.
1920, the year before, 20-y/o Pauli wrote a monumental 200-page review of Einstein's theory of general relativity which impressed Einstein. Now both Heisenberg and Pauli were starting to publish on the new and confused field of QM under Sommerfeld (Munich).
Come back to this chapter; more discussion of the atom.
See p. 46: how Heisenberg and Pauli worked together to come to a solution, taking three years -- a bit of "inexplicable inspiration by Heisenberg." Heisenberg made it work by introducing "half-quantum" into Sommerfeld's equation.
Second time reading:
Summer, 1921 -- Heisenberg, 19 y/o, and Pauli, 21 y/o -- talking with Otto Laporte, 18 y/o
Pauli and Heisenberg -- Sommerfeld: Max von Laue's friend.
1920: Pauli -- 200 page review explaining all of general relativity impressing even Einstein;
see footnote, p. 41 -- Laporte
-- entanglement -- p. 41 -- again
Ernst Mach -- p. 42 -- Pauli's grandfather
Bohr - Sommerfeld model of the atom
Frankfurt -- Sommerfeld / Max Born!!
-- as a child, Max Born lived near Einstein in Berlin!!
Walter Gerlach
experiment on p. 45!!
Classical: Ag -- magnet --> clump on screen
Sommerfeld: AG -- magnet --> break into three distinct clumps
Actual: AG --magnet --> two distinct clumps
Second reading:
Stern -Gerlach experiment
-- a sensation in 1922
Ag -- magnet / magnet --> two different clumps; binary; "yes" / "no"
described as "spin-1/2 particles."
Chapter 5
On The Streetcar
Summer 1923
This is the chapter discussing X-rays as waves, particles, and that neither waves nor particles alone would be able to describe quantum theory.
This is the chapter in which a mistake was made (Sommerfeld was not on the streetcar) and which Louisa discussed in the introduction.
Einstein and Niels Bohr on the streetcar; Bohr had been to the port of Copenhagen to pick up Einstein, after the astronomical confirmation of general relativity in November, 1919. Einstein was in Europe to make up for his nonattendance at his Nobel Prize ceremony in December 1922.
Short biographical look at Einstein.
Von Laue, while working with Sommerfeld in Munich, had proved that X-rays were waves; now Compton demonstrated that they were particles -- p. 55.
Compton's work did mark the beginnings of acceptance of light-quanta, strong enough by 1926 the light-quantum would merit a name of its own: the photon. The word -- approximate Greek for "light-being" -- came from G. N. Lewis of Berkeley, the white-mustahced "father of physical chemistry" (who also suggested that the time that light takes to travel a centimeter be called a jiffy). The next year, Compton would receive his Nobel Prize. But neither particles nor waves alone would be able to describe the quantum world, and the wave-particle fusion Einstein had been predicting since 1909 lay just around the bend, in several unexpected guises -- p. 59.
Chapter 6
Light Waves and Matter Waves
November 1923 -- December 1924
Return to Einstein's "ghost waves."
John Slater supported "ghost waves." Twice more they were proposed: four years later by de Broglie and after WWII, another American, David Bohm. Always rejected. But the problem of waves/particles would most clearly highlight the mysteries of entanglement to its most perceptive sleuth, John Bell. -- p. 60
The Bohr-Kramers-Slater paper: the fastest written paper of Bohr's life.
Heisenberg and Pauli also visited Copenhagen about this time, falling under the spell of the Copenhagen interpretation.
In the spring of 1924, as Slater was leaving Copenhagen, two letters heading toward Einstein:
1) a dissertation for 32-y/o Louis de Broglie at the Sorbonne (Paris); his papers were the first step toward the new quantum theory -- p. 65
2) Satyendra Nath Bose, a lecturer at the brand-new University of Dacca; almost same age and education as de Broglie; Bose, too, started with the premise that light-quanta were real; derived startling results -- p. 65. Bose's paper: 4 pages; Einstein translated; got it published; Bose's idea: the complete indistinguishability of light-quanta, making meaningless any system that treated them as individuals. This indistinguishability meant strange things for quantum states. The likelihood of one of these fundamentally indistinguishable particles entering a given state is affected by the states of the particles that surround it. [Footnote: a notoriously elusive concept, quantum state is perhaps best defined as what can be known about a quantum object. Bose-Einstein statistics allow amazing feats to be performed by unentangled particles in a definite quantum state. By contrast, entangled particles, are in an indefinite state -- neither here nor there, neither yea nor nay -- until one is measured.]This exotic behavior was still leading to Nobel prizes in 2001 -- p. 66.
Bose-Einstein statistics -- .... the particles are not only indistinguishable but also moving in perfect harmony; together they become a quantum matter wave, visible to the naked eye. Soon to be known as Bose-Einstein condensation, this is what makes a laser's light so piercing, what allows a superconductor to carry a current of electricity forever, what makes a superfluid able to flow up walls. -- p. 67 Remember: one wave formula describes two entangled particles. "They become one."
Chapter 7
Pauli and Heisenberg at the Movies
January 8, 1925
pic: Wolfgang Pauli, 1930
Heisenberg, 23, and Pauli, 25, visiting Munich, their old university town. Pauli on his way to Hamburg as professor; Heisenberg on his way to Copenhagen.
Gottingen, center of mathematics, the third city in the quantum theorists' trinity (Copenhagen, Munich (Sommerfeld)/Hamburg (Pauli), Gottingen). Math necessary to try to explain QM. QM inconsistencies bothered everyone, especially Bohr.
Almost simultaneous with Einstein's papers on Bose-Einstein, Pauli published two papers. One on the Stern-Gerlach experiment of 1922. The other, to become his most famous paper, on what Dirac eventually called "Pauli's exclusion principle." Heisenberg and Ehrenfest called it the Pauli Verbot. Pauli: unlike the particles (i.e., light-quanta and many atoms) that Bose and Einstein were writing about, electrons would never gather sociably in a single quantum state. The electrons liked making opposite pairs (spin up and spin down) but would not get closer than that.
QM being explained with prohibitions, formal rules, incomprehensibilities -- not explanations, models, or pictures. -- p. 71.
1925: Heisenberg (Copenhagen) and Pauli (Hamburg) struggling with QM. Max Born was writing in the mathematical citadel of Gottingen. Mechanics -- physics that describes motion and the forces that make things move -- had failed for the atom, and a new mathematical structure was needed. He called for a "Quanten-mechanik," not yet knowing that he and Heisenberg would produce it. -- p. 72
Heisenberg, now an assistant to Max Born, the mathematician in Gottingen, travels to Helgoland (Germany). Alone.
Heisenberg, with the Kramers, in Copenhagen had come a long way, but Heisenberg wanted to work on this alone for awhile.
Very quickly the slate was wiped clean. "His quantum mechanics would declare time and space nonexistent within the walls of the atom." -- p. 75
Deeply troubled. "As Max Born had predicted, a quantum mechanics would be very different from any description of forces and motion that physics had ever known before." -- p. 76
Returns to Gottingen, via Pauli and Hamburg.
Heisenberg's time in Helgoland led to new thinking. Max Born played with it mathematically, using matrices. Came up with p q − q p = h/2πi.
A lot of things in that equation: first, matrices are not commutative.
Second, the origin of the "p" and "q." "Mass is m, so, since the time of Newton, momentum has been p (for impetus), forcing position to be abbreviated by the counterintuitive q.
Third: i, the first imaginary number, is a common math took, but this was "the first use of the imaginary unit in a seemingly essential way in the history of natural science." -- p. 77. WOW.
December 25, 1925: Einstein writes a letter -- "The most interesting recent theoretical achievement is the Heisenberg-Born-Jordan theory of quantum states." p q − q p = h/2πi.
Schrodinger to TB sanitorium high in the Alps. Reads the book of his friend Hermann Weyl who wrote a book well known in the world of physics, Space - Time - Matter, based on a series of mathematical lectures on relativity during the war. at E.T.H. in Zurich.
Shrodinger noticed a point that Weyl made which, if followed thorugh, suggested that the electron in an orbit behaves like a standing wave (whose crests and troughs oscillate up and down without advancing). His product from this: "On a Remarkable Property of the Quantized Orbits of a Single Electron." -- gave no further thought to the paper.
1925, three years later: at E.T.H./University of Zurich -- Schrodinger given de Broglie's recent paper on waves of matter. Schrodinger gave lecture, November 23, 1925 -- a week after Heisenberg, Born, and Jordan had submitted their famous paper "On Quantum Mechanics" for publication.
Felix Bloch, 20 y/o, had become Heisenberg's first pupil (Copenhagen) and then one of Pauli's assistants (you can see how this came about). Schrodinger plunged into waves: "he hoped to take seriously the Broglie-Einstein wave theory of the moving particle, according to which the particle is nothing more than a kind of 'whitecap' on the wave radiation that forms the basis of the world."
A bit of Schrodinger biography. Schrodinger's wife was with with Weyl (her lover, and her husband's closest friend; Weyl's wife, was the mistress of Pauli's friend, the physicist Paul Scherrer).
Four years later, 1929, Weyl helped Schrodinger solve the equation: a solution to the Schrodinger equation, describing the state or condition of a given quantum entity, is known as a wavefunction. The wavefunction is symbolized by the Greek letter psi. -- p. 84.
Einstein noting two solutions: the matrix results which replicated the wave equation. "Until now we had no exact quantum theory, and now we suddenly have two. You will agree with me that the two exclude each other. Which theory is correct? Perhaps neither is." -- p. 85.
So, if I understand this correctly, Heisenberg mathematical/matrix formula explained one aspect of QM (particle) and the wavefunction also explained their observations (waves). Particle vs wave?
So, Heisenberg: particle. Schrodinger: wave. Shrodinger: the particle was simply a passenger on the wave.
Heisenberg in Berlin with Einstein (note, it is 1926, well before WWII). Discussing the electron, orbits, jumping, quantum states. And then a competing theory, that the electron continuously emits a wave. -- p. 88 - 89.
The short biographical sketch of Schrodinger, and Itha Junger, age 14 years old. Roswitha was her twin sister. Itha and Roswitha's mother was a friend of Schrodinger's wife, Anny, who had persuaded him to give them math lessons once a week during the summer. Schrodinger tells them of his wave theory but is perplexed that Heisenberg has come up with a particle-based theory which also seems to fit.
Heisenberg's quantum mechanics and Schrodinger's wave mechanics were two ways of saying the same thing. -- p. 91.
Two decisive moments had come in late June, 1926:
The chapter ends with Schrodinger about to meet Bohr for the first time, and "not knowing what he was getting into."
Schrodinger and Bohr arguing; Schrodinger visiting Bohr; Heisenberg lives upstairs at the institute.
So, together: Schrodinger, Bohr, and Heisenberg.
Heisenberg (particles) - Schrodinger (waves): "arguing."
Schrodinger: "The moment we say there are no point-particle electrons, only electron waves or waves of matter, then everything looks quite different. The emission of light is as easily explained as the transmission of radio waves through the aerial of the transmitter, and what seemed to be insoluble contradictions have suddenly disappeared." Bohr continued to disagree; saying that "the very intereaction between light and matter that had caused Planck, 26 years earlier, to introduce the concept of quantization requires discontinuity," he reminded Schrodinger. -- p. 96.
Schrodinger shocked at Bohr's intransigence. Schrodinger felt, that as the questions got more difficult, Bohr became more philosophical.
Correspondence principle mentioned for second time -- p. 98. It was first mentioned on p. 58: Sommerfeld. "Bohr has actually achieved most of his amazing successes not through mathematics but through an intuition, his 'analogy principle,' from which almost no one but he can extract any results. It involves building a quantum theory out of features that would average out, on a large scale, to produce this world we see. In 1920, Bohr renamed it 'the correspondence principle,' which made it no easier to operate or fathom.""A magic wand," said Sommerfeld in the most recent edition of his indispensable and religiously updated textbook of quantum theory." -- p 58
Back to p. 98.
Mentions "uniformity," p. 99.
Bohr read one of Schrodinger's letters on a walk with PAM Dirac and J Robert Oppenheimer, who described the scene to the stuttering quantum mechanician Pascual Jordan. -- p. 99
Oppenheimer gave the definitive description of Gottingen physics: "They are working very hard here, and combining a fantastically impregnable metaphysical disingenuous with the go-getting habits of a wallpaper manufacturer. The result is that the work done here has an almost demoniac lack of plausibility to it, and is highly successful." -- p. 99
The ideas: no longer matrices, but [Max] Born's waves of probability.
Einstein's Gespensterfeld again discussed.
Christmas, 1926.
Heisenberg: giving up on using classical terms particle and wave. "But the mathematics, on the other hand, is now perfect: Dirac has made quantum mechanics as complete as relativity." -- p. 101
Despair. Heisenberg "alone" at Copenhagen institute.
Need to return to this chapter to complete.
Short biographical sketch of Walterh Bothe. Bothe alerte Einstein to a problem in a paper Einstein had just submitted; Einstein immediately asked the Prussian Academy to remove it and they did -- p. 109.
Brussels. Thirty (30) attendees. Would become one of the most famous conferences ever. Bohr, Born, Schrodinger, Heisenberg, Ehrenfest, Einstein, de Broglie. It was at this conference, Einstein, disenchanted with Heisenberg's uncertainty principle, said, "God does not play dice."
Heisenberg: remembered it as a great success for the "Copenhagen interpretation."
de Broglie, spoke early: the wave guided/carried the particle. This meant he added position for the particles in the wave, and those positions came to be called "hidden variables" -- hidden from quantum mechanics.
Schrodinger denied the existence of particles, and thus did not accept de Broglie's interpretation.
Einstein spoke. "This interpretation presupposes a very particular mechanism of instantaneous action-at-a-distance to prevent the wave from acting at more than one place on the screen." (Recall that relativity denies simultaneity any meaning, declaring that no information can travel faster than the speed of light.) "It seems to me that this difficulty cannot be overcome unless the description of the process in terms of the Schrodinger wave is supplemented by some detailed specification of the location of the particle."
Einstein: "I think Monsier de Broglie is right in searching in this direction." "If one works only with Schrodinger waves, the interpretation contradicts the principle of relativity." He sat down.
Bohr's comments on waves, p. 112. But "Ominously," as Andrew Whitaker, John Bell's biographer, writes of this exchange, "Einstein and Bohr were already talking past each other."
Bohr fixated on complementarity.
Bohr won everyone over, but "Bohr could not, however, defeat Einstein's simple objection, which lives on unsolved as "the collapse of the wavefunction" or, more generally "the measurement problem." The wave corresponding to any particle spreads out over the whole world, but the particle itself is discovered in one tiny discrete location, and nowhere else. The vast wave collapses down to the size of a single particle. Quantum mechanics does not describe this moment of discovery, but only gives the probability that the discovery will occur in the place it does. There is no explanation of the particle's doings while unobserved (or, alternatively, of its genesis, if the act of measurement somehow created a particle where before there was only a wave).
From a wide-ranging, matterless probability wave to an incarnation as one specific being -- it is a postulate so nonintuitive as to sound like the tenet of a religion. Einstein, who did not believe in a personal deity either, found this strange. As if teh moment some mystic had the idea of searching for God -- poof! -- he's not a huge, disembodied, omnipresent spirit-mind anymore, but just a little tyke in a barn in a specific hamlet in a specific countryside. -- p. 113.
The measurement problem is one symptom of the nonseparability of quantum systems; another, to which the conversation naturally turned, is the uncertainty principle -- uncertainty is what you get when you try to treat nonseparable things as separate. -- p. 113.
It came down to this: Bohr vs Einstein. -- p. 114.
Gottingen, center of mathematics, the third city in the quantum theorists' trinity (Copenhagen, Munich (Sommerfeld)/Hamburg (Pauli), Gottingen). Math necessary to try to explain QM. QM inconsistencies bothered everyone, especially Bohr.
Almost simultaneous with Einstein's papers on Bose-Einstein, Pauli published two papers. One on the Stern-Gerlach experiment of 1922. The other, to become his most famous paper, on what Dirac eventually called "Pauli's exclusion principle." Heisenberg and Ehrenfest called it the Pauli Verbot. Pauli: unlike the particles (i.e., light-quanta and many atoms) that Bose and Einstein were writing about, electrons would never gather sociably in a single quantum state. The electrons liked making opposite pairs (spin up and spin down) but would not get closer than that.
QM being explained with prohibitions, formal rules, incomprehensibilities -- not explanations, models, or pictures. -- p. 71.
1925: Heisenberg (Copenhagen) and Pauli (Hamburg) struggling with QM. Max Born was writing in the mathematical citadel of Gottingen. Mechanics -- physics that describes motion and the forces that make things move -- had failed for the atom, and a new mathematical structure was needed. He called for a "Quanten-mechanik," not yet knowing that he and Heisenberg would produce it. -- p. 72
Chapter 8
Heisenberg in Helgoland
June 1925
Heisenberg, now an assistant to Max Born, the mathematician in Gottingen, travels to Helgoland (Germany). Alone.
Heisenberg, with the Kramers, in Copenhagen had come a long way, but Heisenberg wanted to work on this alone for awhile.
Very quickly the slate was wiped clean. "His quantum mechanics would declare time and space nonexistent within the walls of the atom." -- p. 75
Deeply troubled. "As Max Born had predicted, a quantum mechanics would be very different from any description of forces and motion that physics had ever known before." -- p. 76
Returns to Gottingen, via Pauli and Hamburg.
Heisenberg's time in Helgoland led to new thinking. Max Born played with it mathematically, using matrices. Came up with p q − q p = h/2πi.
A lot of things in that equation: first, matrices are not commutative.
Second, the origin of the "p" and "q." "Mass is m, so, since the time of Newton, momentum has been p (for impetus), forcing position to be abbreviated by the counterintuitive q.
Third: i, the first imaginary number, is a common math took, but this was "the first use of the imaginary unit in a seemingly essential way in the history of natural science." -- p. 77. WOW.
December 25, 1925: Einstein writes a letter -- "The most interesting recent theoretical achievement is the Heisenberg-Born-Jordan theory of quantum states." p q − q p = h/2πi.
Chapter 9
Schrodinger in Arosa
Christmas and New Year's Day, 1925 - 1926
pic: Erwin Schrodinger
Schrodinger to TB sanitorium high in the Alps. Reads the book of his friend Hermann Weyl who wrote a book well known in the world of physics, Space - Time - Matter, based on a series of mathematical lectures on relativity during the war. at E.T.H. in Zurich.
Shrodinger noticed a point that Weyl made which, if followed thorugh, suggested that the electron in an orbit behaves like a standing wave (whose crests and troughs oscillate up and down without advancing). His product from this: "On a Remarkable Property of the Quantized Orbits of a Single Electron." -- gave no further thought to the paper.
1925, three years later: at E.T.H./University of Zurich -- Schrodinger given de Broglie's recent paper on waves of matter. Schrodinger gave lecture, November 23, 1925 -- a week after Heisenberg, Born, and Jordan had submitted their famous paper "On Quantum Mechanics" for publication.
Felix Bloch, 20 y/o, had become Heisenberg's first pupil (Copenhagen) and then one of Pauli's assistants (you can see how this came about). Schrodinger plunged into waves: "he hoped to take seriously the Broglie-Einstein wave theory of the moving particle, according to which the particle is nothing more than a kind of 'whitecap' on the wave radiation that forms the basis of the world."
A bit of Schrodinger biography. Schrodinger's wife was with with Weyl (her lover, and her husband's closest friend; Weyl's wife, was the mistress of Pauli's friend, the physicist Paul Scherrer).
Four years later, 1929, Weyl helped Schrodinger solve the equation: a solution to the Schrodinger equation, describing the state or condition of a given quantum entity, is known as a wavefunction. The wavefunction is symbolized by the Greek letter psi. -- p. 84.
Einstein noting two solutions: the matrix results which replicated the wave equation. "Until now we had no exact quantum theory, and now we suddenly have two. You will agree with me that the two exclude each other. Which theory is correct? Perhaps neither is." -- p. 85.
So, if I understand this correctly, Heisenberg mathematical/matrix formula explained one aspect of QM (particle) and the wavefunction also explained their observations (waves). Particle vs wave?
So, Heisenberg: particle. Schrodinger: wave. Shrodinger: the particle was simply a passenger on the wave.
Chapter 10
What You Can Observe
April 28 and Summer 1926
Heisenberg in Berlin with Einstein (note, it is 1926, well before WWII). Discussing the electron, orbits, jumping, quantum states. And then a competing theory, that the electron continuously emits a wave. -- p. 88 - 89.
The short biographical sketch of Schrodinger, and Itha Junger, age 14 years old. Roswitha was her twin sister. Itha and Roswitha's mother was a friend of Schrodinger's wife, Anny, who had persuaded him to give them math lessons once a week during the summer. Schrodinger tells them of his wave theory but is perplexed that Heisenberg has come up with a particle-based theory which also seems to fit.
Heisenberg's quantum mechanics and Schrodinger's wave mechanics were two ways of saying the same thing. -- p. 91.
Two decisive moments had come in late June, 1926:
a) a Schrodinger paper describing how wave mechanics dealt with more than one particleBorn brought together particles and waves with his mathematics. Heisenberg didn't want waves; and Schrodinger didn't want particles, so both felt "betrayed." -- p. 92
b) a Born paper (Max Born, the Gottingen mathematician): Born gave the wave its modern interpretation. It became a very useful tool.... p. 91
The chapter ends with Schrodinger about to meet Bohr for the first time, and "not knowing what he was getting into."
Chapter 11
This Damned Quantum Jumping
October 1926
October 1926
Schrodinger and Bohr arguing; Schrodinger visiting Bohr; Heisenberg lives upstairs at the institute.
So, together: Schrodinger, Bohr, and Heisenberg.
Heisenberg (particles) - Schrodinger (waves): "arguing."
Schrodinger: "The moment we say there are no point-particle electrons, only electron waves or waves of matter, then everything looks quite different. The emission of light is as easily explained as the transmission of radio waves through the aerial of the transmitter, and what seemed to be insoluble contradictions have suddenly disappeared." Bohr continued to disagree; saying that "the very intereaction between light and matter that had caused Planck, 26 years earlier, to introduce the concept of quantization requires discontinuity," he reminded Schrodinger. -- p. 96.
Schrodinger shocked at Bohr's intransigence. Schrodinger felt, that as the questions got more difficult, Bohr became more philosophical.
Correspondence principle mentioned for second time -- p. 98. It was first mentioned on p. 58: Sommerfeld. "Bohr has actually achieved most of his amazing successes not through mathematics but through an intuition, his 'analogy principle,' from which almost no one but he can extract any results. It involves building a quantum theory out of features that would average out, on a large scale, to produce this world we see. In 1920, Bohr renamed it 'the correspondence principle,' which made it no easier to operate or fathom.""A magic wand," said Sommerfeld in the most recent edition of his indispensable and religiously updated textbook of quantum theory." -- p 58
Back to p. 98.
Mentions "uniformity," p. 99.
Bohr read one of Schrodinger's letters on a walk with PAM Dirac and J Robert Oppenheimer, who described the scene to the stuttering quantum mechanician Pascual Jordan. -- p. 99
Oppenheimer gave the definitive description of Gottingen physics: "They are working very hard here, and combining a fantastically impregnable metaphysical disingenuous with the go-getting habits of a wallpaper manufacturer. The result is that the work done here has an almost demoniac lack of plausibility to it, and is highly successful." -- p. 99
The ideas: no longer matrices, but [Max] Born's waves of probability.
Einstein's Gespensterfeld again discussed.
Chapter 12
Uncertainty
Winter 1926 - 1927
Christmas, 1926.
Heisenberg: giving up on using classical terms particle and wave. "But the mathematics, on the other hand, is now perfect: Dirac has made quantum mechanics as complete as relativity." -- p. 101
Despair. Heisenberg "alone" at Copenhagen institute.
Need to return to this chapter to complete.
Short biographical sketch of Walterh Bothe. Bothe alerte Einstein to a problem in a paper Einstein had just submitted; Einstein immediately asked the Prussian Academy to remove it and they did -- p. 109.
Chapter 13
Solvay
1927
Brussels. Thirty (30) attendees. Would become one of the most famous conferences ever. Bohr, Born, Schrodinger, Heisenberg, Ehrenfest, Einstein, de Broglie. It was at this conference, Einstein, disenchanted with Heisenberg's uncertainty principle, said, "God does not play dice."
Heisenberg: remembered it as a great success for the "Copenhagen interpretation."
de Broglie, spoke early: the wave guided/carried the particle. This meant he added position for the particles in the wave, and those positions came to be called "hidden variables" -- hidden from quantum mechanics.
Schrodinger denied the existence of particles, and thus did not accept de Broglie's interpretation.
Einstein spoke. "This interpretation presupposes a very particular mechanism of instantaneous action-at-a-distance to prevent the wave from acting at more than one place on the screen." (Recall that relativity denies simultaneity any meaning, declaring that no information can travel faster than the speed of light.) "It seems to me that this difficulty cannot be overcome unless the description of the process in terms of the Schrodinger wave is supplemented by some detailed specification of the location of the particle."
Einstein: "I think Monsier de Broglie is right in searching in this direction." "If one works only with Schrodinger waves, the interpretation contradicts the principle of relativity." He sat down.
Bohr's comments on waves, p. 112. But "Ominously," as Andrew Whitaker, John Bell's biographer, writes of this exchange, "Einstein and Bohr were already talking past each other."
Bohr fixated on complementarity.
Bohr won everyone over, but "Bohr could not, however, defeat Einstein's simple objection, which lives on unsolved as "the collapse of the wavefunction" or, more generally "the measurement problem." The wave corresponding to any particle spreads out over the whole world, but the particle itself is discovered in one tiny discrete location, and nowhere else. The vast wave collapses down to the size of a single particle. Quantum mechanics does not describe this moment of discovery, but only gives the probability that the discovery will occur in the place it does. There is no explanation of the particle's doings while unobserved (or, alternatively, of its genesis, if the act of measurement somehow created a particle where before there was only a wave).
From a wide-ranging, matterless probability wave to an incarnation as one specific being -- it is a postulate so nonintuitive as to sound like the tenet of a religion. Einstein, who did not believe in a personal deity either, found this strange. As if teh moment some mystic had the idea of searching for God -- poof! -- he's not a huge, disembodied, omnipresent spirit-mind anymore, but just a little tyke in a barn in a specific hamlet in a specific countryside. -- p. 113.
The measurement problem is one symptom of the nonseparability of quantum systems; another, to which the conversation naturally turned, is the uncertainty principle -- uncertainty is what you get when you try to treat nonseparable things as separate. -- p. 113.
It came down to this: Bohr vs Einstein. -- p. 114.
Chapter 14
The Spinning World
1927 - 1929
pic: Max Born
It is irony, here, I suppose, that I praise the writing of Louisa Gilder. I have said that her style makes the story difficult to follow, and there seems to be a lot of unnecessary "fluff." However, having read about the short interchange between de Broglie and his hero-since-youth, Einstein, I find it (her style) wonderful and enlightening. This is one of those books one cannot "speed read." Incidentally, de Broglie was returning to Paris, and Einstein was on his was to Paris to visit. They would enter Paris at Gare du Nord, which our family knows well. Gare du Nord for Paris is what Grand Union Station is for New York City.
De Broglie still on Einstein's side (against Bohr). Einstein quotes Planck from 20 years earlier.
But a few months later, de Broglie "converted" to the Copenhagen interpretation -- p. 116. This left only Einstein and Schrodinger standing together, alone.
Schrodinger was still a skeptic in late May of 1928, when he wrote Einstein.
A discussion of E=hv. That relation is fundamental to quantum mechanics. The energy emitted when an electron falls from one energy level to another, a light-quantum of energy, is proportional to the frequency of a corresponding light wave. -- p. 117
If Einstein could find a field that would subsume both waves and particles, then quantum theory would become part of general relativity, the most beautiful field theory of all. -- p. 117
Then this: In January of 1928, four months before, quantum mechanics had made its uneasy truce with special relativity (the part of relativity that deals with frames of reference moving at constant speeds), in an astonishing equation from Dirac.
Dirac's formula had actually started four years earlier (1924) (before quantum mechanics), when Pauli and then Heisenberg unleashed their ridicule on the idea of the spinning electron. -- p. 118
The problem, or actually two problems:
Heisenberg and Dirac bet on time it would take to understand the spinning electron. -- p. 118
Dirac scooped Kramers. -- p. 118
Dirac's equation had two solutions, and one solution was a positive antimatter electron, which had never been heard of before. -- p. 119
Einstein proposed de Broglie, Schrodinger, or Heisenberg for Nobel Prize; de Broglie won.
Vignette of Max Bron meeting Dr Albert Schweitzer -- p. 120.
1929: Bohr's Copenhagen institute triumphant. -- p. 121
2nd to last debate between Bohr and Einstein.
Einstein's famous box thought experiment.
Einstein had decisively sharpened his two decades of worry about separability into a picture of entanglement over half a light-year's distance. If the light-quantum was to be disturbed by the act of observation, as Bohr insisted, this disturbance would have to be nonlocal, spookily acting at an effectively infinite distance. -- p. 125
Bohr saved Einstein -- p. 127
De Broglie still on Einstein's side (against Bohr). Einstein quotes Planck from 20 years earlier.
But a few months later, de Broglie "converted" to the Copenhagen interpretation -- p. 116. This left only Einstein and Schrodinger standing together, alone.
Schrodinger was still a skeptic in late May of 1928, when he wrote Einstein.
A discussion of E=hv. That relation is fundamental to quantum mechanics. The energy emitted when an electron falls from one energy level to another, a light-quantum of energy, is proportional to the frequency of a corresponding light wave. -- p. 117
If Einstein could find a field that would subsume both waves and particles, then quantum theory would become part of general relativity, the most beautiful field theory of all. -- p. 117
Then this: In January of 1928, four months before, quantum mechanics had made its uneasy truce with special relativity (the part of relativity that deals with frames of reference moving at constant speeds), in an astonishing equation from Dirac.
Dirac's formula had actually started four years earlier (1924) (before quantum mechanics), when Pauli and then Heisenberg unleashed their ridicule on the idea of the spinning electron. -- p. 118
The problem, or actually two problems:
- the electron was so small that if it spun on its axis, its equator would be moving much faster than the speed of light
- it also mysteriously took two full rotations to get back to where it started
Heisenberg and Dirac bet on time it would take to understand the spinning electron. -- p. 118
Dirac scooped Kramers. -- p. 118
Dirac's equation had two solutions, and one solution was a positive antimatter electron, which had never been heard of before. -- p. 119
Einstein proposed de Broglie, Schrodinger, or Heisenberg for Nobel Prize; de Broglie won.
Vignette of Max Bron meeting Dr Albert Schweitzer -- p. 120.
1929: Bohr's Copenhagen institute triumphant. -- p. 121
Chapter 15
Solvay
1930
2nd to last debate between Bohr and Einstein.
Einstein's famous box thought experiment.
Einstein had decisively sharpened his two decades of worry about separability into a picture of entanglement over half a light-year's distance. If the light-quantum was to be disturbed by the act of observation, as Bohr insisted, this disturbance would have to be nonlocal, spookily acting at an effectively infinite distance. -- p. 125
Bohr saved Einstein -- p. 127
INTERLUDE
Things Fall Apart
1931 - 1933
May be the most important chapter to date in the book. A lot comes together in this chapter.
Flashback: Einstein, first wife separated in 1914. One son, Tetel, was four; would be schizophrenic by 1930.
Flashback: Einstein, first wife separated in 1914. One son, Tetel, was four; would be schizophrenic by 1930.
Short biographical history of California Institute of Technology, founded by three physicists in 1921.
Einstein visiting CIT in 1930; in attendance was Boris Podolsky; co-authored paper with CIT physicists and Einstein. Podolsky had been a student of Heisenberg in Leipzig. -- p. 130
Podolsky: bachelor's degree in electrical engineering; master's in math; doctorate in physics. Designed copper piping to bring power to LA from Boulder Dam; discovered that the best indicator of the timing of the important spring melt was not the one the company was using -- snow depth in the mountains above the dam -- but high temperatures in Tokyo. -- p. 130
Sommerfeld accompanied Pauli to America because his old student desperately needed him -- p. 131. Short bio of Pauli's life at the time; marriage falling apart, etc.
1931: the year of Einstein's particle and the box. Einstein working his way toward EPR. -- p. 132
Einstein's musing would lead him to the EPR paradox, paving the way for Bell's theorem and all the experimental magic of long-distance entanglement.
In Cambridge, MA, Nathan Rosen was investigating the structure of the hydrogen molecule, producing the first reliable calculation of its two bound-together hydrogen atoms. It is a strange object. Only the molecule as a whole has a quantum state; the quantum atoms are entangled. They have no states of their own, and, as far as quantum theory is concerned, a measurement performed on one instantly affects its twin. When the logical analysis of Podolsky married Einstein's light-blitz box to Rosen's entangled hydrogen atoms, the EPR paradox would be born. -- p. 133. -- first mention of EPR?
NO physics prize in 1931. Committee thrown into disarray when Einstein could not decide between Heisenberg and Schrodinger.
December, 1931: Einstein on cruise liner to the US -- makes decision never to return to his home in Germany on a permanent basis. Wanderlust.
Page 134: full page important
No one took Dirac's theory seriously until positron found in cloud chamber -- p. 135
Rutherford, predicted a proton, in 1920. James Chadwick at Cavendish found it in 1932. The proton was necessary to explain how atoms, especially, the heavier ones, held together. -- p. 136
Neutron different from the neutrino.
Split the atom April 13/14, 1932.
Nobel Prize nomination in 1932 (de Broglie, waves, won in 1929; Schrodinger, waves, 1932; Heisenberg, particles would have to wait until 1933).
Ehrenfest: struggling with QM -- p. 137
Schrodinger: story of Shrodinger, his wife Itha Junger (former 14-y/o student; intimate relationship began after she turned 17 or 18), mistress, pregnancy, abortion, etc...
Schrodinger, unpublished notes of 1932 and 1933: he began investigating mathematically the action-at-a-distance in his equation that so agonized Einstein and Ehrenfest. Once in contact, two particles were described only by a shared wavefunction, long after they lost all physical contact. -- p. 137
De Broglie noted that but did not follow up on that independently until someone else articulated it more clearly -- and that would be Einstein, Podolsky, and Rosen, three years later (1935).
It sent chills up my back to re-read this page after reading the last page, page 336, of the book.
1932: Copenhagen, again. Most were there, but NOT Gamow (trapped in Stalinist Ukraine).
Lise Meitner was there. Lise Meitner was the first to understand the "portentous" fission of uranium. (In 1938, "From the chilly safety of Stockholm, Meitner guided Hahn, back in Berlin, in splitting the uranium atom late that year -- the first step to a nuclear bomb." -- p. 149.)
Max Delbruck -- to become one of the founding fathers of molecular biology -- spoke early. He introduced a funny, funny play: the physicists in the Faust play.
1933: Hitler comes to power. Everybody is leaving, trying to leave. Heisenberg stayed behind. Pauli one of the last to leave, but he left also.
Pascual Jordan (Heisenberg and Born's stuttering co-creator of matrix mechanics -- see page 76) joined the Nazi Party.
Max Born, wife, and son left to Selva, Italy, where with several other refugee physicists, professors and students, started the "University of Selve" -- a bench in the forest in the mountains. Weyl showed up. Anna Shrodinger, devoted to Weyl, showed upo.
Einstein brought up the paradox: action-at-a-distance, although not sure if he called it that.
The story of Ehrenfest -- unable to solve the problem; Down syndrome son to be killed by Nazi; he killed his son and then himself. -- p. 147
Notes at the beginning of the chapter: read this chapter slowly, very closely.
The story of Grete Hermann visitng Heisenberg and Carl Friedrich von Weizsacker in Leipzig; a skeptic.
The story of Pauli's depression and surviving with the help of Carl Jung.
Einstein, Podolsky, and Rosen
At the time, Einstein and von Neumann made up half of the math department at Princeton.
Einstein invites 25 y/o Rosen (from Brooklyn) to work with him; initial discussion on a star collapsing under its own gravity to form a tiny rip in space-time -- if two such events occurred -- a "wormhole" -- but that word not used then.
Also at IAS (Princeton) was Boris Podolsky. Podolsky was the one who put two and two together and realized that Rosen's intertwined twin hydrogen atoms formed a pre-existing case capable of demonstrating what Einstein had been talking about but never published.
EPR paper: "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?"
It was written by Podolsky; Einstein knew only 500 words of English.
The EPR argument traveled along the same lines as Einstein's thought experiments regarding the light-blitz box, though presented more thoroughly and with more complicated logical and quantum-mechanical analysis.
So, at this stage in the argument: either measure the momentum here to learn the momentum there, or measure the position here to learn the position there.
But the paper famously (and significantly) defined an "element of reality": "If, without in any way disturbing a system, we can predict with certainty the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity." In that case, should not both characteristics of the faraway "system" -- position and momentum -- be deems elements of reality? And if so, was not quantum mechanics incomplete for stating otherwise? -- p. 160. It continues.
The last two paragraphs of the paper were similarly significant. "One would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted, EPR admitted. "On this point of view, since either one or the other -- but not both simultaneously -- of the quantities P [momentum] and Q [position] can be predicted, they are not simultaneously real."
But they were skeptical. "This makes the reality of P and Q depend upon the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this."
"While we have thus shown that hte wave function does NOT provide a complete description of the physical reality, we have left open the question of whether or not such a description exists. We believe, however that such a theory is possible."
Newspaper headlines: "Einstein attacks quantum mechanics."
Published in May, 1935. Three radically different responses from the three people who matter the most: Bohr, Pauli, and Schrodinger.
See page 162.
Bohr: "had to sleep on it"; a day later, ready to write a paper answering Einstein -- p. 164
Pauli: quoted a nonsense poem
Schrodinger: inspired him
Bohr: "The very existence of the quantum entails the necessity of a final renunciation of the classical ideal of causality and a readical revision of our attitude toward the problem of physical reality." But Bohr and Rosenfeld still struggling to understand. Bohr: "I want to work out what role the idea of time plays in the description of this phenomenon ...'
Shrodinger's reply to Einstein, begins on page 167.
.... to page 174 -- needs to be re-read sometime.
"But I cannot for a moment believe that God plays dice and makes use of 'telepathic' means (as the current quantum theory alleges he does)." -- Einstein, 1942, p. 174
David Bohm talking with assistant professor Eugene Gross at Princeton regarding his subpoena to testify at the Oppenheimer trial.
Short bio of Oppenheimer.
nim-nim-nim boys
Oppenheimer imparted two theories to David Bohm in the short time that Bohm was his student. "One theory was Oppenheimer's entire intellectual life, and the other almost took that life away from him." -- -. 186
The first theory: quantum theory as put forth by Bohr and his students; Bohm had left Caltech in 1941 "a convinced classicist" deeply skeptical of quantum theory. But Oppenheimer....p. 187
Then Oppenheimer disappeared...he was doing something for the government -- the Manhattan Project.
The story of security issues at Los Alamos....
Interesting interlude, the bio of Bohm and Oppenheimer.
Intellectual work by Bohm continues.
Bohm called the EPR paper the ERP paper. -- p. 195
"We conclude then," Bohm said, "that no theory of mechanically determined hidden variables can lead to all of the results of the quantum theory." In a footnote: "Mechanical" meaning "separable parts obeying causal laws." A characteristic footnote elsewhere in the book reads "The term 'quantum mechanics' is very much a misnomver. It should, perhaps, be called 'quantum non-mechanics.'" -- p. 196.
September 23, 1949: Soviets had tests "an atomic device," four months after Bohm was brought before the House Un-American Activities Committee.
Bohm still at Princeton; new companion was physics' new wonder boy: Murray Gell-Mann.
Gell-Mann: early undergraduate sprint through Yale; then PhD from MIT.
Bohm had been acquitted (Supreme Court agreed that 5th Amendment protected him) but he had not been re-appointed to Princeton.
Gell-Mann's excitement: "You think you can convince Einstein?"
Two days later: Bohm despondent. Einstein talked Bohm out of it. Einstein was still not convinced. -- p. 200.
Bohm left Princeton; Einstein wrote a letter of recommendation for him to go to Manchester, England.
Bohm publishes Quantum Theory in 1951.
"Never a great reader of other people's work, Bohm did not know until after he had finished [his next] article that this "new physical interpretation" of the wavefunction was actually a resurrection, in a more fully realized form, of de Broglie's pilot wave that guides the quantum particle. -- p. 203
Big paragraph on p. 203 is a must-read.
The story of Bohm leaving for Brazil -- after the House hearings. -- p. 207
Bohm working with Jayme Tiomno on "hidden variables."
Feynman came down to visit. Feynman was his usual practical self. "You can't have determinism and quantum leaps." -- Feynman, p. 212.
Feynman mentioned he had talked with Fermi; writing back and forth about mesons -- mysterious new particles just found in 1947. -- p. 213.
Bohm was not shy to speak of the "instantaneous interactions between distant particles" (i.e., nonlocality) of his "quantum potential," which depends directly on the state of the whole, not on individual parts. -- p. 215
Bohm allowed for a clear and sharp perception of how the two theories (quantum vs classical) differ. -- Bohm would have to wait for Bell before this was appreciated. -- p. 215
Joe Weinberg, "Scientist X," Russian spy -- p. 216
Miriam Yevick, p. 218
Gespensterfelder: ghost waves guiding the particles. -- p. 219
Standing Up To Oppenheimer
1952 - 1957
The story of Max Dresden; left Amsterdam shortly before the war to get PhD at U of Michigan, Ann Arbor. Wrote a masterly biography of Bohr's "cardinal," Kramers. It tells the larger story of the great era of quantum physics. -- p. 221
Neumann's argument did not apply to Bohm's hidden variables.
Oppenheimer: if we cannot disprove Bohm, then we much agree to ignore him. -- p. 222. Wow.
The story of John Nash, p. 222.
"The quantum theory seemed to have almost destroyed Bohm, too, but the story was not finished. His theory would not have such a grand comeback as Nash's, but, in the hands of an obscure physicist in a remote land, it would reveal the mysterious mathematical inequality of Bell's Theorem -- an idea that would prove even more important than equilibrium. -- p. 222
1952, Max Born and Einstein both in their early 70's. Max Born wrote to Einstein about death.
Einstein: "Have you noted that Bohm believes (as de Broglie did, by the way, 25 years ago) that he is able to interpret the quantum theory in deterministic terms?" -- p. 223
Bohm: "I am beginning to think in a new direction." He was still searching for a causal underlayer to the quantum theory. -- p. 225.
"It took a long time for Bohm to forgive Oppenheimer, and it certainly did not happen until Oppenheimer had more or less destroyed himself during his appearance before the House Un-American Committee. By all accounts, he came out a shattered man, and was perhaps easier to forgive that way." -- p. 227
Bohm, 1957, ever unsatisfied, moved on to Britain.
Quotable Feynman, p. 228. -- about no one understanding quantum mechanics.
Page 229: a lot about Feynman describing wave-particle issue. He very clearly said the hidden variable theory cannot be true. "It is impossible, he continued, to explain the interference pattern as merely the sum of the contributions of electrons going through one hole or the other -- a corollary to what John Bell (unmentioned by Feynman) had shown earlier that same year." -- p. 229
Acausality: p. 229.
Bohm: hidden variable theory needs to be explained
Feynman: hidden variable theory cannot be correct
Sommerfeld accompanied Pauli to America because his old student desperately needed him -- p. 131. Short bio of Pauli's life at the time; marriage falling apart, etc.
1931: the year of Einstein's particle and the box. Einstein working his way toward EPR. -- p. 132
Einstein's musing would lead him to the EPR paradox, paving the way for Bell's theorem and all the experimental magic of long-distance entanglement.
In Cambridge, MA, Nathan Rosen was investigating the structure of the hydrogen molecule, producing the first reliable calculation of its two bound-together hydrogen atoms. It is a strange object. Only the molecule as a whole has a quantum state; the quantum atoms are entangled. They have no states of their own, and, as far as quantum theory is concerned, a measurement performed on one instantly affects its twin. When the logical analysis of Podolsky married Einstein's light-blitz box to Rosen's entangled hydrogen atoms, the EPR paradox would be born. -- p. 133. -- first mention of EPR?
NO physics prize in 1931. Committee thrown into disarray when Einstein could not decide between Heisenberg and Schrodinger.
December, 1931: Einstein on cruise liner to the US -- makes decision never to return to his home in Germany on a permanent basis. Wanderlust.
Page 134: full page important
John von Neumann: showed that the mathematical structure of quantum theory could be reduced to a pure and austerely abstract group of foundational mathematical statements -- which mathematicians call axioms
- Von Neumann's book was a tour de force
- "Von Neumann has shown ..." entered the quantum physicist's lexicon as a debate killer
- Von Neumann had already done this with a paradoxical branch of mathematics (set theory)
- Von Neumann had come with the insight that would found a whole new discipline of mathematics and economics (game theory)
- within a year, he would join Einstein as one of his few colleagues at IAS, Princeton
- "The five years after ... Solvay 1927 ... golden age of physics
- Pauli and Dirac each predicted a particle
- Pauli's came first: the neutrino, chargeless, massless; only thing that could explain a form of mystifying nuclear radiation (beta decay) [described elsewhere very nicely in Miller's book on Jung and Pauli]
- Dirac: a solution which predicted both positive and negative solutions for electron charge -- it couldn't be the proton -- his friend Oppenheimer pointed out that all matter would have collapsed into itself in a blaze of light only 10^-10 seconds after the Big Bang; positron
No one took Dirac's theory seriously until positron found in cloud chamber -- p. 135
***************
Rutherford, predicted a proton, in 1920. James Chadwick at Cavendish found it in 1932. The proton was necessary to explain how atoms, especially, the heavier ones, held together. -- p. 136
Neutron different from the neutrino.
Split the atom April 13/14, 1932.
Nobel Prize nomination in 1932 (de Broglie, waves, won in 1929; Schrodinger, waves, 1932; Heisenberg, particles would have to wait until 1933).
Ehrenfest: struggling with QM -- p. 137
Schrodinger: story of Shrodinger, his wife Itha Junger (former 14-y/o student; intimate relationship began after she turned 17 or 18), mistress, pregnancy, abortion, etc...
Schrodinger, unpublished notes of 1932 and 1933: he began investigating mathematically the action-at-a-distance in his equation that so agonized Einstein and Ehrenfest. Once in contact, two particles were described only by a shared wavefunction, long after they lost all physical contact. -- p. 137
De Broglie noted that but did not follow up on that independently until someone else articulated it more clearly -- and that would be Einstein, Podolsky, and Rosen, three years later (1935).
It sent chills up my back to re-read this page after reading the last page, page 336, of the book.
*****************
1932: Copenhagen, again. Most were there, but NOT Gamow (trapped in Stalinist Ukraine).
Lise Meitner was there. Lise Meitner was the first to understand the "portentous" fission of uranium. (In 1938, "From the chilly safety of Stockholm, Meitner guided Hahn, back in Berlin, in splitting the uranium atom late that year -- the first step to a nuclear bomb." -- p. 149.)
Max Delbruck -- to become one of the founding fathers of molecular biology -- spoke early. He introduced a funny, funny play: the physicists in the Faust play.
***********************
1933: Hitler comes to power. Everybody is leaving, trying to leave. Heisenberg stayed behind. Pauli one of the last to leave, but he left also.
Pascual Jordan (Heisenberg and Born's stuttering co-creator of matrix mechanics -- see page 76) joined the Nazi Party.
Max Born, wife, and son left to Selva, Italy, where with several other refugee physicists, professors and students, started the "University of Selve" -- a bench in the forest in the mountains. Weyl showed up. Anna Shrodinger, devoted to Weyl, showed upo.
Einstein brought up the paradox: action-at-a-distance, although not sure if he called it that.
The story of Ehrenfest -- unable to solve the problem; Down syndrome son to be killed by Nazi; he killed his son and then himself. -- p. 147
Chapter 14
The Quantum-Mechanical Description of Reality
1934 - 1935
Notes at the beginning of the chapter: read this chapter slowly, very closely.
The story of Grete Hermann visitng Heisenberg and Carl Friedrich von Weizsacker in Leipzig; a skeptic.
The story of Pauli's depression and surviving with the help of Carl Jung.
Einstein, Podolsky, and Rosen
At the time, Einstein and von Neumann made up half of the math department at Princeton.
Einstein invites 25 y/o Rosen (from Brooklyn) to work with him; initial discussion on a star collapsing under its own gravity to form a tiny rip in space-time -- if two such events occurred -- a "wormhole" -- but that word not used then.
Also at IAS (Princeton) was Boris Podolsky. Podolsky was the one who put two and two together and realized that Rosen's intertwined twin hydrogen atoms formed a pre-existing case capable of demonstrating what Einstein had been talking about but never published.
EPR paper: "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?"
It was written by Podolsky; Einstein knew only 500 words of English.
The EPR argument traveled along the same lines as Einstein's thought experiments regarding the light-blitz box, though presented more thoroughly and with more complicated logical and quantum-mechanical analysis.
So, at this stage in the argument: either measure the momentum here to learn the momentum there, or measure the position here to learn the position there.
But the paper famously (and significantly) defined an "element of reality": "If, without in any way disturbing a system, we can predict with certainty the value of a physical quantity, then there exists an element of physical reality corresponding to this physical quantity." In that case, should not both characteristics of the faraway "system" -- position and momentum -- be deems elements of reality? And if so, was not quantum mechanics incomplete for stating otherwise? -- p. 160. It continues.
The last two paragraphs of the paper were similarly significant. "One would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted, EPR admitted. "On this point of view, since either one or the other -- but not both simultaneously -- of the quantities P [momentum] and Q [position] can be predicted, they are not simultaneously real."
But they were skeptical. "This makes the reality of P and Q depend upon the process of measurement carried out on the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this."
"While we have thus shown that hte wave function does NOT provide a complete description of the physical reality, we have left open the question of whether or not such a description exists. We believe, however that such a theory is possible."
Newspaper headlines: "Einstein attacks quantum mechanics."
Published in May, 1935. Three radically different responses from the three people who matter the most: Bohr, Pauli, and Schrodinger.
See page 162.
Bohr: "had to sleep on it"; a day later, ready to write a paper answering Einstein -- p. 164
Pauli: quoted a nonsense poem
Schrodinger: inspired him
Bohr: "The very existence of the quantum entails the necessity of a final renunciation of the classical ideal of causality and a readical revision of our attitude toward the problem of physical reality." But Bohr and Rosenfeld still struggling to understand. Bohr: "I want to work out what role the idea of time plays in the description of this phenomenon ...'
Shrodinger's reply to Einstein, begins on page 167.
.... to page 174 -- needs to be re-read sometime.
"But I cannot for a moment believe that God plays dice and makes use of 'telepathic' means (as the current quantum theory alleges he does)." -- Einstein, 1942, p. 174
Section Two of Four Sections In The Book
The Search and the Indictment
1940 - 1952
pic: David Bohm
Chapter 17
Princeton
April - June 10, 1949
David Bohm talking with assistant professor Eugene Gross at Princeton regarding his subpoena to testify at the Oppenheimer trial.
Chapter 18
Berkeley
1941 - 1945
Short bio of Oppenheimer.
nim-nim-nim boys
Oppenheimer imparted two theories to David Bohm in the short time that Bohm was his student. "One theory was Oppenheimer's entire intellectual life, and the other almost took that life away from him." -- -. 186
The first theory: quantum theory as put forth by Bohr and his students; Bohm had left Caltech in 1941 "a convinced classicist" deeply skeptical of quantum theory. But Oppenheimer....p. 187
Then Oppenheimer disappeared...he was doing something for the government -- the Manhattan Project.
The story of security issues at Los Alamos....
Interesting interlude, the bio of Bohm and Oppenheimer.
Chapter 19
Quantum Theory at Princeton
1946 - 1948
Intellectual work by Bohm continues.
Bohm called the EPR paper the ERP paper. -- p. 195
"We conclude then," Bohm said, "that no theory of mechanically determined hidden variables can lead to all of the results of the quantum theory." In a footnote: "Mechanical" meaning "separable parts obeying causal laws." A characteristic footnote elsewhere in the book reads "The term 'quantum mechanics' is very much a misnomver. It should, perhaps, be called 'quantum non-mechanics.'" -- p. 196.
Chapter 20
Princeton
June 15 - December 1949
September 23, 1949: Soviets had tests "an atomic device," four months after Bohm was brought before the House Un-American Activities Committee.
Chapter 21
Quantum Theory
1951
Bohm still at Princeton; new companion was physics' new wonder boy: Murray Gell-Mann.
Gell-Mann: early undergraduate sprint through Yale; then PhD from MIT.
Bohm had been acquitted (Supreme Court agreed that 5th Amendment protected him) but he had not been re-appointed to Princeton.
Gell-Mann's excitement: "You think you can convince Einstein?"
Two days later: Bohm despondent. Einstein talked Bohm out of it. Einstein was still not convinced. -- p. 200.
Bohm left Princeton; Einstein wrote a letter of recommendation for him to go to Manchester, England.
Chapter 22
Hidden Variables and Hiding Out
1951 - 1952
Bohm publishes Quantum Theory in 1951.
"Never a great reader of other people's work, Bohm did not know until after he had finished [his next] article that this "new physical interpretation" of the wavefunction was actually a resurrection, in a more fully realized form, of de Broglie's pilot wave that guides the quantum particle. -- p. 203
Big paragraph on p. 203 is a must-read.
The story of Bohm leaving for Brazil -- after the House hearings. -- p. 207
Chapter 23
Brazil
1952
Bohm working with Jayme Tiomno on "hidden variables."
Feynman came down to visit. Feynman was his usual practical self. "You can't have determinism and quantum leaps." -- Feynman, p. 212.
Feynman mentioned he had talked with Fermi; writing back and forth about mesons -- mysterious new particles just found in 1947. -- p. 213.
Chapter 24
Letters From The World
1952
Bohm was not shy to speak of the "instantaneous interactions between distant particles" (i.e., nonlocality) of his "quantum potential," which depends directly on the state of the whole, not on individual parts. -- p. 215
Bohm allowed for a clear and sharp perception of how the two theories (quantum vs classical) differ. -- Bohm would have to wait for Bell before this was appreciated. -- p. 215
Joe Weinberg, "Scientist X," Russian spy -- p. 216
Miriam Yevick, p. 218
Gespensterfelder: ghost waves guiding the particles. -- p. 219
Chapter 25
1952 - 1957
The story of Max Dresden; left Amsterdam shortly before the war to get PhD at U of Michigan, Ann Arbor. Wrote a masterly biography of Bohr's "cardinal," Kramers. It tells the larger story of the great era of quantum physics. -- p. 221
Neumann's argument did not apply to Bohm's hidden variables.
Oppenheimer: if we cannot disprove Bohm, then we much agree to ignore him. -- p. 222. Wow.
The story of John Nash, p. 222.
"The quantum theory seemed to have almost destroyed Bohm, too, but the story was not finished. His theory would not have such a grand comeback as Nash's, but, in the hands of an obscure physicist in a remote land, it would reveal the mysterious mathematical inequality of Bell's Theorem -- an idea that would prove even more important than equilibrium. -- p. 222
Chapter 26
Letters From Einstein
1952 - 1954
1952, Max Born and Einstein both in their early 70's. Max Born wrote to Einstein about death.
Einstein: "Have you noted that Bohm believes (as de Broglie did, by the way, 25 years ago) that he is able to interpret the quantum theory in deterministic terms?" -- p. 223
Bohm: "I am beginning to think in a new direction." He was still searching for a causal underlayer to the quantum theory. -- p. 225.
Epilogue To The Story Of Bohm
1954
"It took a long time for Bohm to forgive Oppenheimer, and it certainly did not happen until Oppenheimer had more or less destroyed himself during his appearance before the House Un-American Committee. By all accounts, he came out a shattered man, and was perhaps easier to forgive that way." -- p. 227
Bohm, 1957, ever unsatisfied, moved on to Britain.
Quotable Feynman, p. 228. -- about no one understanding quantum mechanics.
Page 229: a lot about Feynman describing wave-particle issue. He very clearly said the hidden variable theory cannot be true. "It is impossible, he continued, to explain the interference pattern as merely the sum of the contributions of electrons going through one hole or the other -- a corollary to what John Bell (unmentioned by Feynman) had shown earlier that same year." -- p. 229
Acausality: p. 229.
Bohm: hidden variable theory needs to be explained
Feynman: hidden variable theory cannot be correct
Section Three of Four Sections In The Book
The Discovery
1952 - 1979
pic: John F Clauser with his machine inspired by John S Bell, 1976
Chapter 27
Things Change
1952
Finally, we are introduced to John Bell, the "central figure" of this book. Short bio.
It was 1952; he had just read Bohm's paper: "Bohm had accomplished what Bell had dreamed of -- a theory with entities that were real regardless of the actions of experimentalists, which nonethess produced the same results as quantum mechanics." -- that was Einstein's goal, p. 233
"Bell saw that the great von Neumann 'must have been just wrong' when he declared such a hidden-variable theory impossible. Bell would soon identify the same logical flaw that Grete Hermann had descried some seventeen years before, though her remarks were now buried by history." -- p. 233
Brookhaven National Laboratory: Long Island
Stanford Linear Accelerator Center (SLAC): soon
CERN: yet to come
Bohm marries Mary Ross, p. 234 - 235.
Bell mentions Franz Mandl who translated von Neumann's book and Bell ended up being one of the few to have actually read it. Upon reading it, he saw von Neumann's "unreasonable axiom." -- p. 235
Bell (Irish) goes to Birmingham. Option to talk about Bohm or talk about accelerators. Thinking about his career, he decided, smartly, to talk about accelerators.
CERN: a proton synchrotron.
Very good description of CERN -- it was fun to read this description -- p. 237.
Mentions Hideki Yukawa, 1935, predicted the existence of mesons (two types of hadrons -- mesons and baryons; hadrons are held together by the "strong force" whereas atoms are held together by the electromagnetic force. Neutrons and protons are the most well-known mesons. Baryons, less important in nature after the Big Bang).
John Bell, 35, arguing with Josef Maria Jauch, 50, over the no-hidden-variables theorem. Jauch comes off as a jerk; Bell is serious.
Bell: why do people go on constructing impossibility proofs? Why is the pilot-wave picture ignored in textbooks? -- p. 239
Copenhagen solution vs Einstein.
Copenhagen solution vs Bohm.
Cophenhagen solution vs Bell.
Bell brought up the EPR paper; Jauch said Bohr explained why that paper was wrong; complementarity, was almost metaphysics, religious. -- p. 241
Bell: we have this beautiful mathematics, and we don't know which part of the world it should be applied to. -- p. 243
Bell: "Bohr very, very bright, but isn't it a bit strange that you don't find any discussion of where the division between his classical apparatus and quantum system occurs. For me (Bell), it is the indispensability, and above all the shiftiness, of such a division that is the big surprise of quantum mechanics ... and the hidden-variable approach isone way to get rid of that division. If you gave definite properties -- 'hidden variables' -- to the elementary particles, you don't have to be concerned that the classical apparatus has definite properties. Everything has definite properties. It is just that they are more under our control for big things than for little things." -- p. 243
[From wiki: the division between classical and quantum occurs at the level of the nucleons -- protons and neutrons.]
Jauch: now you are back to your hidden variables -- p. 243
p. 244: end of discussion between Jauch and Bell.
Through the following decade, Bell was not the only one who continued to think about the hidden-variable problem -- p. 244
The story of Jauch's book.
Bell writes a paper on the problem of hidden variables and moves to California -- p. 246
John and Mary Bell arrive at Stanford, November 23, 1963 -- day after JFK was shot. -- p. 246
SLAC
Esoteric particles Bell was writing about: pi-mesons that hold the nucleus together, and the neutrinos that emerge from its decay -- no longer thought about them. He was consumed by Jauch's impossibility proof and his own thought: "what is proved by impossibility proofs is lack of imagination." -- p. 247
Mary suggests John should give a "local account" of quantum mechanics. -- p. 247
Bell had come to the same conclusion that Grete Hermann had: the same point that Einstein had made to Bergmann and Bargmann -- Einstein had never published anything on this and Grete's comments lost... p. 247
Mary asked John (Bell) if he thought Einstein was wrong (EPR) -- Bell: "I suspect that action-at-a-distance has NOT been disposed of yet." -- p. 248
Again, the ghost of von Neumann, for the third time, delaying progress -- Bell's paper is "lost" for two years. Not found until 1966. -- p. 248
But in 1964 when he wrote his paper, Bell was feeling more and more confident that it was this requirement of locality that created the essential difficulty to the hidden-variables scheme. One weekend, his ideas coalesced, and it was Bell's turn to make an impossibility proof: no local hidden-variables theories. -- p. 248
The equation he came up with was to become famous, known as the Bell inequality. A pair of distant particles may exhibit a certain amount of correlation. The requirements of locality and separability together restrict the amount to beneath a certain level. If the correlations surpass that limit, either locality or separability is violated. Entangled particles violate this inequality with disconcerting frequency: they are flagrantly more correlated than they have any right, by common sense, to be. The fabric of reality requires some form of either nonlocality or nonspearability.
Bell's paper actually found its critical reader immediately, and this, improbably, in the philosophy department of MIT -- p. 249.
This was a great, great chapter.
It was 1952; he had just read Bohm's paper: "Bohm had accomplished what Bell had dreamed of -- a theory with entities that were real regardless of the actions of experimentalists, which nonethess produced the same results as quantum mechanics." -- that was Einstein's goal, p. 233
"Bell saw that the great von Neumann 'must have been just wrong' when he declared such a hidden-variable theory impossible. Bell would soon identify the same logical flaw that Grete Hermann had descried some seventeen years before, though her remarks were now buried by history." -- p. 233
Brookhaven National Laboratory: Long Island
Stanford Linear Accelerator Center (SLAC): soon
CERN: yet to come
Bohm marries Mary Ross, p. 234 - 235.
Bell mentions Franz Mandl who translated von Neumann's book and Bell ended up being one of the few to have actually read it. Upon reading it, he saw von Neumann's "unreasonable axiom." -- p. 235
Bell (Irish) goes to Birmingham. Option to talk about Bohm or talk about accelerators. Thinking about his career, he decided, smartly, to talk about accelerators.
Chapter 28
What Is Proved By Impossibility Proofs
1963 - 1964
CERN: a proton synchrotron.
Very good description of CERN -- it was fun to read this description -- p. 237.
Mentions Hideki Yukawa, 1935, predicted the existence of mesons (two types of hadrons -- mesons and baryons; hadrons are held together by the "strong force" whereas atoms are held together by the electromagnetic force. Neutrons and protons are the most well-known mesons. Baryons, less important in nature after the Big Bang).
John Bell, 35, arguing with Josef Maria Jauch, 50, over the no-hidden-variables theorem. Jauch comes off as a jerk; Bell is serious.
Bell: why do people go on constructing impossibility proofs? Why is the pilot-wave picture ignored in textbooks? -- p. 239
Copenhagen solution vs Einstein.
Copenhagen solution vs Bohm.
Cophenhagen solution vs Bell.
Bell brought up the EPR paper; Jauch said Bohr explained why that paper was wrong; complementarity, was almost metaphysics, religious. -- p. 241
Bell: we have this beautiful mathematics, and we don't know which part of the world it should be applied to. -- p. 243
Bell: "Bohr very, very bright, but isn't it a bit strange that you don't find any discussion of where the division between his classical apparatus and quantum system occurs. For me (Bell), it is the indispensability, and above all the shiftiness, of such a division that is the big surprise of quantum mechanics ... and the hidden-variable approach isone way to get rid of that division. If you gave definite properties -- 'hidden variables' -- to the elementary particles, you don't have to be concerned that the classical apparatus has definite properties. Everything has definite properties. It is just that they are more under our control for big things than for little things." -- p. 243
[From wiki: the division between classical and quantum occurs at the level of the nucleons -- protons and neutrons.]
Jauch: now you are back to your hidden variables -- p. 243
p. 244: end of discussion between Jauch and Bell.
Through the following decade, Bell was not the only one who continued to think about the hidden-variable problem -- p. 244
The story of Jauch's book.
Bell writes a paper on the problem of hidden variables and moves to California -- p. 246
John and Mary Bell arrive at Stanford, November 23, 1963 -- day after JFK was shot. -- p. 246
SLAC
Esoteric particles Bell was writing about: pi-mesons that hold the nucleus together, and the neutrinos that emerge from its decay -- no longer thought about them. He was consumed by Jauch's impossibility proof and his own thought: "what is proved by impossibility proofs is lack of imagination." -- p. 247
Mary suggests John should give a "local account" of quantum mechanics. -- p. 247
Bell had come to the same conclusion that Grete Hermann had: the same point that Einstein had made to Bergmann and Bargmann -- Einstein had never published anything on this and Grete's comments lost... p. 247
Mary asked John (Bell) if he thought Einstein was wrong (EPR) -- Bell: "I suspect that action-at-a-distance has NOT been disposed of yet." -- p. 248
Again, the ghost of von Neumann, for the third time, delaying progress -- Bell's paper is "lost" for two years. Not found until 1966. -- p. 248
But in 1964 when he wrote his paper, Bell was feeling more and more confident that it was this requirement of locality that created the essential difficulty to the hidden-variables scheme. One weekend, his ideas coalesced, and it was Bell's turn to make an impossibility proof: no local hidden-variables theories. -- p. 248
The equation he came up with was to become famous, known as the Bell inequality. A pair of distant particles may exhibit a certain amount of correlation. The requirements of locality and separability together restrict the amount to beneath a certain level. If the correlations surpass that limit, either locality or separability is violated. Entangled particles violate this inequality with disconcerting frequency: they are flagrantly more correlated than they have any right, by common sense, to be. The fabric of reality requires some form of either nonlocality or nonspearability.
Bell's paper actually found its critical reader immediately, and this, improbably, in the philosophy department of MIT -- p. 249.
This was a great, great chapter.
Chapter 23
A Little Imagination
1969
pic: Abner Shimony
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