Bernstein J. Quantum profiles

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BESSO

general relativity isn’t the correct theory. The mathematical dif-

ﬁculties in confronting it with experiment are, for the moment,

insurmountable. However that turns out, we are as far from a

truly rational theory (of the duality of light quanta and particles)

as we were ﬁfty years ago!’’

Besso replied at once to this letter. His response persuaded

Einstein—and now, having read it several times, also me—that

he hadn’t really grasped what Einstein was getting at. This pro-

voked a still more detailed letter from Einstein, written on the

eighth of October. It is this letter that, in my view, gives one of

the clearest accounts of Einstein’s position to be found any-

where. He writes,

Dear Michele,

Your letter of 21.IX. consists, it seems to me, of two parts that

are more or less independent of each other. The object of the ﬁrst

part is quantum theory and physical reality. What relation is there

between the ‘‘state’’ (‘‘quantum state’’) described by a function ψ

and a real deterministic situation (that we call the ‘‘real state’’)?

Does the quantum state characterize completely (1) or only in-

completely (2) a real state?

One cannot respond unambiguously to this question, because

each measurement represents a real uncontrollable intervention in

the system (Heisenberg). The real state is not therefore some-

thing that is immediately accessible to experience, and its appreci-

ation always rests hypothetical. (Comparable to the notion of

force in classical mechanics, if one doesn’t ﬁx a priori the law of

motion.) Therefore suppositions (1) and (2) are, in principle, both

possible. A decision in favor of one of them can be taken only after

an examination and confrontation of the admissibility of their

consequences.

I reject (1) because it obliges us to admit that there is a rigid

connection between parts of the system separated from each other

in space in an arbitrary way (instantaneous action at a distance,

which doesn’t diminish when the distance increases.) Here is the

demonstration:

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BESSO

A system S

, with a [wave] function ψ

, which is known, is

composed of two systems ψ

, and ψ

, which are very far from each

other at the instant t. If one makes a ‘‘complete’’ measurement on

, which can be done in different ways (according to whether one

measures, for example, the momenta or the coordinates), depend-

ing on the result of the measurement and the function ψ

one can determine by current quantum-theoretical methods, the

function ψ

of the second system. This function can assume different

forms, according to the procedure of measurement applied to S

But this is in contradiction with (1) if one excludes action at a dis-

tance. Therefore the measurement on S

has no effect on the real

state S

, and therefore assuming (1) no effect on the quantum state

of S

described by ψ

I am thus forced to pass to the supposition (2) according to

which the real state of a system is only described incompletely by

the function ψ

If one considers the method of the present quantum theory as

being in principle deﬁnitive, that amounts to renouncing a com-

plete description of real states. One could justify this renunciation

if one assumes that there is no law for real states—i.e., that their

description would be useless. Otherwise said, that would mean:

laws don’t apply to things, but only to what observation teaches us

about them. (The laws that relate to the temporal succession of

this partial knowledge are however entirely deterministic.)

Now, I can’t accept that. I think that the statistical character of

the present theory is simply conditioned by the choice of an in-

complete description....

Your Albert

As I read these letters, I kept hearing Bell’s musical Irish voice

saying, ‘‘For me, it is a pity that Einstein’s idea doesn’t work.

The reasonable thing just doesn’t work.’’

Besso responded poetically. On the tenth of December he

wrote, ‘‘This morning the radio overwhelmed me with the

powerful last phrase of the Trout Quintet. On this occasion, I

thought, in an orchestra the conductor is visible—in a quartet, it

163

BESSO

is the invisible creator of the music. Invisible lines link the musi-

cians: as the canvas of probabilities links everything, everything

that is realized, all reality. The most solid lines link mother and

child. Solid lines link us two . . . ’’

✜

Besso died on March 15, 1955, and Einstein’s last letter in the

collection, written to Vero and Bice, is one of the most moving

and personal of all his writings. He reveals feelings about himself

that I have never seen expressed anywhere else. Einstein writes:

Dear Vero and Dear Mme. Bice:

It was truly very good of you to give me, in these so painful

days, so many details concerning the death of Michele. His end

was in harmony with the image of his entire life and the image of

the circle of people that surrounded him. The gift of leading a

harmonious life is rarely joined to such a keen intelligence, espe-

cially to the degree one found in him. But what I admired most

about Michele was the fact that he was able to live so many years

with one woman, not only in peace but also in constant unity,

something I have lamentably failed at twice.

Einstein’s second wife died in 1936, and this remarkable ad-

mission is the only hint I know of that their married life was not

successful. (Besso’s wife died in 1944.) The letter continues:

Our friendship was born when I was a student in Zurich, where

we met regularly at musical evenings. He, the older and wiser, was

there to stimulate us. The circle of his interests appeared truly

without boundaries. Nevertheless, it was his critical philosophical

preoccupations that seemed most characteristic of him.

Later, it was the patent ofﬁce that brought us together. Our

conversations as we returned from the ofﬁce had an incomparable

charm—it was as if human contingencies did not exist at all. How-

ever, later on we had more difﬁculty understanding each other

when we wrote. His pen did not succeed in following his versatile

mind—to such an extent that it was impossible in most cases for

his correspondent to guess at what he had omitted to note.

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BESSO

So in quitting this strange world he has once again preceded me

by a little. That doesn’t mean anything. For those of us who be-

lieve in physics, this separation between past, present, and future

is only an illusion, however tenacious.

In thanking you cordially, I send you my best thoughts.

Your

A. Einstein

A few weeks later, Einstein, too, had quit ‘‘this strange world.’’

165

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✜ Select Bibliography ✜

Bell, J. S. Speakable and Unspeakable in Quantum Mechanics. New York:

Cambridge University Press, 1987.

Bernstein, J. The Tenth Dimension. New York: McGraw-Hill, 1989.

Bohm, D. Quantum Theory. New York: Prentice Hall, 1951.

Born, M. The Born-Einstein Letters. New York: Walker, 1971.

D’Espagnat, B. Conceptual Foundations of Quantum Mechanics.2ded.

Reading, Mass.: Addison-Wesley, 1976.

Einstein, A. Correspondence avec Michele Besso 1903–1955. Edited by

P. Speziali. Paris: Hermann, 1979.

Kuhn, T. S. Black-Body Theory and the Quantum Discontinuity, 1894–

1912. Chicago: University of Chicago Press, 1987.

Misner, C. W., K. Thorne, and J. A. Wheeler. Gravitation. San Fran-

cisco: Freeman, 1973.

Moore, W. Schrödinger. New York: Cambridge University Press, 1989.

Pais, A. Subtle Is the Lord. New York: Oxford University Press, 1982.

Sakurai, J. J. Modern Quantum Mechanics. Reading: Benjamin/Cum-

mings, 1985.

Wheeler, J. A., and W. H. Zurek. Quantum Theory and Measurement.

Princeton: Princeton University Press, 1983.

167

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✜ Index ✜

19–20; on Copenhagen interpreta-accelerators: design of, 11–12; strong

focusing principle, 16 tion of quantum theory, 53; early

aging, reversibility of physical pro- life and education, 12–15, 50–51;

cess and, 150–51 Eastern religions—quantum the-

Albert Einstein: Philosopher Scientist, 38 ory connection, 80–83; on Ein-

American Association for the Ad- stein’s abandonment of quantum

vancement of Science, 131 theory, 84; Einstein-Podolsky-

Rosen experiment discussed, 7, 49;American Physical Society, 44

elementary-particle physics re-Ames, Joseph Sweetman, 103–4

ampliﬁcation, quantum theory and, search, 18–19; Heisenberg evalu-

ated by, 52–53; on hidden vari-137–38

Anderson, Carl, 49 ables, 64–65, 68–69; impossibility

angular momentum, 57–62 proof, 73; Large Electron Project

Annalen der Physik, 27 (LEP), 86–88; Maharishi Mashesh

antimatter, development of, 49 Yogi and, 83–84; marriage to

apparatus, importance of, in quan- Mary, 17; on correlations, 62–64;

tum theory, 51–53 Peierls’s work with, 67; personal

life, 7–11; reservations about quan-Ashbel Smith and Roland Blumberg

tum theory, 8–9, 20, 84–86; strongProfessorship, 130

focusing principle, 16–17; TCPAspect, Alain, 76

theorem, 17–18; uncertainty princi-astronomy, locality and, 71

ple discussed, 50–51; violon d’In-atomic bomb research and testing

gres of, 74; on von Neumann’s(Los Alamos), 124

atomic clocks, gravitation and relativ- theorem and, 64–65; Wheeler’s as-

ity theory, 43–44 sessment of, 136–37

Bell, Mary: CERN career, 8–10, 19–Atomic Energy Commission, 126–29

20; early life and education, 15–Atomic Energy Research Establish-

16; Large Electron Project and,ment (Harwell), 15–19

86–87; marriage to John, 17; retire-atomic spectra, electron orbits and,

ment of, 11; Stanford visit of, 67–32

atomic theory of matter, 54 68

Bell’s inequality (Bell’s theorem), 7,

Baldwin, Lydia, 101 73–77; impact of, on popular cul-

ture, vii–viii, 77–80; Wheeler’sBaltimore Federation of Church and

view of, 131–32Synagogue Youth, 106–7

Belfast Technical High School, 13 Beowulf, Wheeler’s writing compared

Bell, John Stewart: Bohm’s work ana- to, 130–31, 135–36

‘‘Bertlmann’s Socks and the Naturelyzed by, 65–67, 72–73; Bohr eval-

uated by, 51–53; California visits of Reality,’’ 8; EPR experiment

of, 67–68; CERN appointment, and, 45–46

169

INDEX

Besso, Bice Margherita Luisa, 150 quantum theory, 20, 59; Wheeler

Besso, Michele: analyzes friendship inﬂuenced by, 107–8, 131–32

with Einstein, 154–55; conversion Bohr orbit, 29

to Christianity, 157; correspon- Boltzmann, Ludwig, 54

Born, Max, 64, 66; Einstein corre-dence with Einstein, 144–62;

spondence with, 37, 48–49, 146,death of, 164; early life and family

history, 148–49; education of, 149; 161; Nobel Prize awarded to, 37;

inﬂuence on Einstein’s relativity re- Pauli correspondence with, 76;

search, 144; failure to understand Schrödinger equation, 35

quantum theory, 162–63; meeting Breit, Gregory, 106, 108

Brown’s molecular motion, 4, 55,with Einstein, 149–50; quantum

152theory evolves, in correspondence,

Buddhism, quantum theory and, 81–150–51, 158–59

83Besso, Vero, 147–48

Big Bang theory, 81–82 Buhler-Broglin, Manfred, 86–87

blackbody radiation, 21–23 Bureau of Standards, 128

‘‘Can Quantum-Mechanical Descrip-

black hole theory, 117; geon as

model of, 132–33

tion of Physical Reality Be Consid-Bohm, David, 49; Einstein and, 158;

EPR experiment analyzed by, 57, ered Complete?,’’ 44

60–62; on nonlocality, 72–73; on Carnegie Institute for Terrestrial

Magnetism, 105–6hidden variables, 64–65; publishes

CERN (Conseil Européen pour laQuantum Theory, 53–54; reactions

Recherche Nucleaire): Bell’s ca-to papers by, 65–67; relations with

reer at, 7, 9–10; Dalai Lama visitEinstein, 56–57

Bohr, Aage, 138–39 to, 80–81; elementary-particle

Bohr, Eric, 111 physics, 88–89; Large Electron

Bohr, Niels: Bell’s evaluation of, 51– Project (LEP) and, 87–88; organiz-

53; on Bell’s inequality, 7; Born in- ational structure, 19; origins of,

ﬂuenced by, 38; double-slit experi- 10–11, 19; Proton Synchrotron at,

ment, 41–42; Einstein’s relations 17; work habits at, 67

with, 38–40, 43–45, 158; Ein- Cern Courrier,80

stein’s superiority over, 84; Heisen- chemical bonding, quantum theory

berg inﬂuenced by, 37; interest in and, 49

China, science and civilization in, 82Eastern religions, 80; ‘‘liquid-drop

model’’ of nucleus, 109; nuclear ﬁs- Christoﬁlos, Nicholas, 16

sion research and, 110–18; origins Clauser, John, 75–76

of quantum theory and, 4; plane- Colgate, Sterling, 102

community relations, nuclear re-tary atomic model of, 28–30, 104;

plutonium reactors and, 123; prin- search and, 87–88

ciple of complementarity, 42; re- Compton, Arthur, 118, 160

computers: early developments in,buttal of EPR experiment, 46–49;

Rutherford’s inﬂuence on, 107; 106; role of, in early atomic re-

Schrödinger debates with, 55–56; search, 128; solid–state (con-

densed-matter) theory, 27–28schwindlig (dizzy) thinking and

170

INDEX

Condon, E. U., 109 Eastern religions: Oppenheimer and,

conjugate quantities (position and 6; quantum theory and, 80–83;

momentum), quantum theory and, Schrödinger’s study of, 33

36. See also momentum; position The Economist,5

Ehrenfest, Paul, 58, 105Copenhagen interpretation of quan-

Einstein, Albert: abandons quantumtum theory, 52–53; gravitation, 69;

planetary atomic model, 28–29; theory, 7, 37, 44, 54, 84–85, 159–

Schrödinger visits, 55 62; Besso correspondence with,

correlations: spin concept and, 60– 144–62; Bohm’s relations with,

62; ‘‘twins’’ analogy of, 62–63 56–57, 66; Bohr’s relations with,

38–40, 43–45; on blackbody radia-cosmic radiation, elementary-particle

tion, 23–26; on death of Besso,physics and, 124–25

164; defense work in World WarCoulomb, Charles Augustin, 69

II, 78; ‘‘dice-playing’’ analogy criti-Courant, Ernest, 16

Crick, Francis, 33 cizing quantum theory, 37, 40,

Dalai Lama, 80–81

48–49, 117, 139–40; divorce of

Mileva, 153; double-slit experi-

ment, 41–42; emigration to U.S.,The Dancing Wu Li Masters, 6, 77–

156–57; EPR experiment and, 48–78, 130–31

49; family and marriages, 151–54;Davisson, C., 14, 31

de Broglie, Louis (Prince), 33–34, Habicht correspondence with, 3–

4, 23–24; letter of recommenda-66; early research, 30–31; opposi-

tion for Besso, 156; local realismtion to statistical mechanics, 38;

and quantum theory, 73–74, 76;quantum theory and, 55

marriage to Elsa Lowenthal, 154;de Broglie, Maurice (Prince), 30

Descartes, René, 69–70 on mathematical foundations of

determinism: quantum theory and, quantum theory, 56; molecular the-

65–66; wave theory and, 35–37 ory of heat, 55; 1905 papers, 4, 27,

55, 143, 152–53; Olympia Acad-DeWitt, Bryce, 134

dice-playing analogy in quantum the- emy and, 3; opposition to statisti-

ory (Einstein), 37, 40, 48–49, 117, cal mechanics, 38; Patent Ofﬁce

139–40 work, 147–48, 152–53; pilot waves

Dictionary of Scientiﬁc Biography, (Führungsfelder), 34; on planetary

atomic model, 29–32; in Prague,146

20–21; probability amplitudes anddiffraction, 24–25

quantum theory, 117; quanta unitsDirac, Paul, 4, 34; quantum theory

and relativity, 49–50 developed by, 23; relativity theory

Discourses and Mathematical Demon- developed by, 153–54; solid-state

(condensed-matter) theory, 27–28;strations Concerning Two New Sci-

ences, 69 ‘‘spooky actions at a distance’’

Domash, Larry, 83–84 (spukhafte Fernwirkungen), 44, 62,

73; on theory vs. experimental sci-double-slit experiment, 40–41, 139

Du Pont Company, nuclear reactor ence, 145; uncertainty principle

research, 118–24 and, 43–44; uniﬁed ﬁeld theory,

110, 157–58, 160; wave equationDyson, Freeman, 15, 130, 145–46

171