Stanford University Faculty

"Newton would have been laughed out of the country if Kepler hadn't done the measurement. ... The facts speak for themselves. ... History has shown that you need a little luck — and if you don't have the luck, you're out of luck. (1:00:00 to 1:01:00 in video)"

"The reminds me of the scene in Mel Brooks's ' where asks his hunch-backed servant, , how he lives with his hump, and Igor answers, "What hump?" ... The potential of overcoming the ultraviolet problem is also the deeper reason for the allure of string theory, a microscopic model for the vacuum that has failed to account for any measured thing."

"Science is about measurement, dammit — it's not about ideas. (55:20 in video)"

"What we live in, unfortunately, is a time when we are infected by what I call quantum field theory idolatry. (39:30 in video)"

"If you think, as a Western person, that you are not affected by religious traditions, you are sadly mistaken. (22:30 in video)"

"When a thing gets very, very small, you can't tell the difference between a solid and a liquid. (16:30 in video)"

"It has been my experience that good theoretical physics is empowering, in that it enables thinking to take place that would otherwise not occur, and, in its highest form, facilitates experiments that would otherwise not be done."

"My rule is simply to do for my students exactly what I hope someone else will do for my sons when the time comes: I teach them to have faith in themselves and in their own compass, to listen to nature to find truth, to love knowledge for the sake of itself, and to strive for greatness."

"Bell Labs had been a kind of holy place of solid state physics since the 1950's when it was built up by Shockley after the invention of the transistor. I had no idea at the time of the significance of this placement, but I did notice during my job talk that everybody understood what I was saying immediately — this had never happened before — and that the audience had an irresistible urge to interrupt, heckle, and argue about the subject matter loudly among themselves during the talk so as to lob hand grenades into it, just like back-benchers do in the House of Commons. Being a combative person I rather liked this and lobbed a few grenades of my own to maintain control of my seminar. I later came to understand that this heckling was a sign of respect from these people, that the ability to handle it was a test of a person's worth, and that polite silence from them was an extremely bad sign, amounting to Pauli's famous criticism that the speaker was "not even wrong.""

"I learned about X-ray diffraction, neutron scattering, raman scattering, infrared absorption spectroscopy, heat capacity, transport, time-dependent transport, magnetic resonance, electron diffraction, electron energy loss spectroscopy — all the experimental techniques that constitute the eyes and ears of modern solid state physics. As this occurred I slowly became disillusioned with the reductionist ideal of physics, for it was completely clear that the outcome of these experiments was almost always impossible to predict from first principles, yet was right and meaningful and certainly regulated by the same microscopic laws that work in atoms. Only many years later did I finally understand that this truth, which seems so natural to solid state physicists because they confront experiments so frequently, is actually quite alien to other branches of physics and is vigorously repudiated by many scientists on the grounds that things not amenable to reductionist thinking are not physics."

"I most enjoy helping to build something up, taking an unformulated enterprise and making it into what it could become."

"It is better to have one seven-foot jumper on your team than any number of six-foot jumpers."

"But in the 1950s, many universities saw an advantage in building up all of the sciences and engineering with an eye toward obtaining federal grant money. No single institution did this better than Stanford University. And no one person was more attuned to using federal grants to build a university than its dean of engineering and eventual provost, Frederick Terman. Dr. Terman, trained as an electrical engineer, was an aggressive man with insight and boundless energy. When he began as dean, Stanford University was considered a good private regional school. When he retired as provost, it was arguably the best university for research in the nation."

"Remember, Aristotle's De Anima is a seamless mixture of the science and philosophy of his time. We can aim at something similar, i.e. we should feel very comfortable using scientific results in philosophy. It does not mean philosophers must become scientists."

"Modern experimentation is often like driving an automobile. The details and theory of the instruments being used in the experiment are not known to the experimenter except in a very general way. (...) Experimenters are taught in an explicit way, often, how to write up reports of their experiments. But the tradition here is like sports reporting. Only the results of the experiment are reported in any serious detail. The procedures are not."

"A semantic definition of a particular set of command types, then, is a rule for constructing, for any command of one of these types, a verification condition on the antecedents and consequents."

"If there is ever a science of programming language design, it will probably consist largely of matching languages to the design methods they support."

"Although my own previous enthusiasm has been for syntactically rich languages like the Algol family, I now see clearly and concretely the force of Minsky's 1970 Turing lecture, in which he argued that Lisp's uniformity of structure and power of self reference gave the programmer capabilities whose content was well worth the sacrifice of visual form."

"If the advancement of the general art of programming requires the continuing invention and elaboration of paradigms, advancement of the art of the individual programmer requires that he expand his repertory of paradigms."

"It is, therefore, possible to extend a partially specified interpretation to a complete interpretation, without loss of verifiability, [...] This fact offers the possibility of automatic verification of programs, the programmer merely tagging entrances and one edge in each innermost loop."

"The establishment of formal standards for proofs about programs [...] and the proposal that the semantics of a programming language may be defined independently of all processors for that language, by establishing standards of rigor for proofs about programs in the language, appears to be novel."

"For having a clear influence on methodologies for the creation of efficient and reliable software, and for helping to found the following important subfields of computer science: the theory of parsing, the semantics of programming languages, automatic program verification, automatic program synthesis, and analysis of algorithms."

"To the designer of programming languages, I say: unless you can support the paradigms I use when I program, or at least support my extending your language into one that does support my programming methods, I don't need your shiny new languages. [...] To persuade me of the merit of your language, you must show me how to construct programs in it."

"If I ask another professor what he teaches in the introductory programming course, whether he answers proudly "Pascal" or diffidently "FORTRAN," I know that he is teaching a grammar, a set of semantic rules, and some finished algorithms, leaving the students to discover, on their own, some process of design."

"There's no point in going out into space if the future that we'll see there is a sterile future living in tin cans. We have to able to recreate in space habitats which are as beautiful as earth-like as the loveliest parts of planet Earth and we can do that."

"We should ask, critically and with appeal to the numbers, whether the best site for a growing advancing industrial society is Earth, the Moon, Mars, some other planet, or somewhere else entirely. Surprisingly, the answer will be inescapable — the best site is "somewhere else entirely.""

"Is the surface of a planet really the right place for expanding technological civilization?"

"Clearly our first task is to use the material wealth of space to solve the urgent problems we now face on Earth: to bring the poverty-stricken segments of the world up to a decent living standard, without recourse to war or punitive action against those already in material comfort; to provide for a maturing civilization the basic energy vital to its survival."

"The increasing demand for electricity, the shortage of fuels on earth, and concern about widespread use of nuclear energy have led to consideration of . ... has studied the SSPS concept, which is the location in geosynchronous orbit of stations converting solar into electrical energy, to be sent down as microwave power for conversion to direct current or to a power line frequency at the earth's surface."

"Surely, after 62 years, we should have an exact formulation of some serious part of quantum mechanics? By 'exact' I do not of course mean 'exactly true'. I mean only that the theory should be fully formulated in mathematical terms, with nothing left to the discretion of the theoretical physicist . . . until workable approximations are needed in applications. By 'serious' I mean that some substantial fragment of physics should be covered. Nonrelativistic 'particle' quantum mechanics, perhaps with the inclusion of the electromagnetic field and a cut-off interaction, is serious enough."

"In a theory in which parameters are added to quantum mechanics to determine the results of individual measurements, without changing the statistical predictions, there must be a mechanism whereby the setting of one measuring device can influence the reading of another instrument, however remote. Moreover, the signal involved must propagate instantaneously, so that such a theory could not be Lorentz invariant. Of course, the situation is different if the quantum mechanical predictions are of limited validity. Conceivably they might apply only to experiments in which the settings of the instruments are made sufficiently in advance to allow them to reach some mutual rapport by exchange of signals with velocity less than or equal to that of light. In that connection, experiments of the type proposed by Bohm and Aharonov, in which the settings are changed during the flight of the particles, are crucial."

"1 + P(b, c) ≥ |P(a, b) － P(a, c)|"

"More generally, the hidden variable account of a given system becomes entirely different when we remember that it has undoubtedly interacted with numerous other systems in the past and that the total wave function will certainly not be factorable. The same effect complicates the hidden variable account of the theory of measurement, when it is desired to include part of the 'apparatus' in the system. Bohm of course was well aware of these features of his scheme, and has given them much attention. However, it must be stressed that, to the present writer's knowledge, there is no proof that any hidden variable account of quantum mechanics must have this extraordinary character. It would therefore be interesting, perhaps, to pursue some further 'impossibility proofs,' replacing the arbitrary axioms objected to above by some condition of locality, or of separability of distant systems."

"To know the quantum mechanical state of a system implies, in general, only statistical restrictions on the results of measurements. It seems interesting to ask if this statistical element be thought of as arising, as in classical statistical mechanics, because the states in question are averages over better defined states for which individually the results would be quite determined. These hypothetical 'dispersion free' states would be specified not only by the quantum mechanical state vector but also by additional 'hidden variables' - 'hidden' because if states with prescribed values of these variables could actually be prepared, quantum mechanics would be observably inadequate."

"Bohr was inconsistent, unclear, willfully obscure and right. Einstein was consistent, clear, down-to-earth and wrong."

"The discomfort that I feel is associated with the fact that the observed perfect s seem to demand something like the ‘genetic’ hypothesis [identical twins, carrying with them identical genes]. For me, it is so reasonable to assume that the photons in those experiments carry with them programs, which have been correlated in advance, telling them how to behave. This is so rational that I think that when Einstein saw that, and the others refused to see it, he was the rational man. The other people, although history has justified them, were burying their heads in the sand. I feel that Einstein’s intellectual superiority over Bohr, in this instance, was enormous; a vast gulf between the man who saw clearly what was needed, and the obscurantist. So for me, it is a pity that Einstein’s idea doesn’t work. The reasonable thing just doesn’t work."

"The theorem tells you that maybe there must be something happening faster than light, although it pains me even to say that much. The theorem certainly implies that Einstein's concept of space and time, neatly divided up into separate regions by light velocity, is not tenable. But then, to say that there's something going faster than light is to say more than I know."

"It can be argued that in trying to see behind the formal predictions of quantum theory we are just making trouble for ourselves. Was not precisely this the lesson that had to be learned before quantum mechanics could be constructed, that it is futile to try to see behind the observed phenomena?"

"While the founding fathers agonized over the question 'particle' or 'wave', de Broglie in 1925 proposed the obvious answer 'particle' and 'wave'. Is it not clear from the smallness of the scintillation on the screen that we have to do with a particle? And is it not clear, from the diffraction and interference patterns, that the motion of the particle is directed by a wave? De Broglie showed in detail how the motion of a particle, passing through just one of two holes in screen, could be influenced by waves propagating through both holes. And so influenced that the particle does not go where the waves cancel out, but is attracted to where they cooperate. This idea seems to me so natural and simple, to resolve the wave-particle dilemma in such a clear and ordinary way, that it is a great mystery to me that it was so generally ignored."

"John S. Bell (1928–1990, right) and I at in Bell’s office 10 years after the neutrino experiment. We were the quasi-official theorists of that experiment. We did not do very well, all things considered, because of inexperience and ignorance. After the experiment, in 1963, we both went to SLAC, where I wrote my computer program and he developed his famous inequalities. We also discussed other things, even wrote a paper together that was never published. He considered his work on the fundaments of quantum mechanics as a hobby, mainly to be done in the evening, at home. He told me that he intended to do away definitely with this nonsense of hidden variables, and so he did. Later he drifted more and more into this subject, and as I consider it as some sort of foolishness not good for anything having to do with the real world, I once asked him: “Why are you doing this? Does it make the slightest difference in the calculations such as I am doing?” To which he answered: “You are right, but are you not interested and curious about the interpretation?” He was right too, up to a point. While his work became very important, as it could be verified by experiment, often in this branch of physics the discussions are on the level of finding out how many angels can dance on the point of a needle. But even so: there are interesting things there."

"It was John Bell who investigated quantum theory in the greatest depth and established what the theory can tell us about the fundamental nature of the physical world. Moreover, by stimulating experimental tests of the deepest and most profound aspects of quantum theory, Bell's work led to the possibility of exploring seemingly philosophical questions, such as the nature of reality, directly through experiments. And this was just Bell's "hobby"."

"In my opinion, John Bell performed an extremely important role then, and also later, in generally supporting - thereby making respectable - the apparently "fringe" activities of such people as Karolyhazy, Bohm, [Philip M.] Pearle, Ghirardi, and many others (including myself) in suggesting schemes that go beyond standard quantum mechanics, in the intended direction of realism. No physicist could doubt the scientific credentials of John Bell. The fact that he was prepared to go out of his way to support research of this kind gave it a previously unaccustomed status."

"I told Wheeler that I had had a number of conversations with Bell about quantum theory. "He’s a wonderful fellow," Wheeler noted. "Did he say to you," Wheeler asked, laughing, "‘I’d rather be clear and wrong, than foggy and right’?" I told Wheeler that Bell had not used exactly those words, but that it certainly sounded like him. I also told Wheeler that from the time that Bell began to study the quantum theory, he had conceptual problems with it, and that I had asked Bell if, at that time, he thought that the theory might simply be wrong—to which Bell had answered, "I hesitated to think it might be wrong, but I knew that it was rotten." At this, Wheeler burst into a marvelous peal of laughter. The idea of the young Bell rebelling against the "rottenness" of the quantum theory struck Wheeler as incredibly funny."

"I had never met Bell, nor heard him lecture, but in my reading of his scientific papers I have developed a great admiration for him and his work. I have especially admired his attempts to dismantle the orthodox Copenhagen interpretation of quantum theory, written with such tremendous style and obvious enjoyment. Although in this book I have tried to present a balanced account - arguing one way and then another - I hope that I have done justice to Bell's superbly constructed criticisms. The debate over the meaning of quantum theory will certainly be poorer without him."

"We must thank John Bell for having shown us that philosophical questions about the nature of reality could be translated into problems for physicists, where naive experimentalists can contribute."

"The orthodox approaches, whether the authors think they have made derivations or assumptions, are just fine FAPP — when used with the good taste and discretion picked up from exposure to good examples."

"The idea that elimination of coherence, in one way or another, implies the replacement of 'and' by 'or', is a very common one among solvers of the 'measurement problem'. It has always puzzled me."

"The first charge against 'measurement', in the fundamental axioms of quantum mechanics, is that it anchors there the shifty split of the world into 'system' and 'apparatus'. A second charge is that the word comes loaded with meaning from everyday life, meaning which is entirely inappropriate in the quantum context."

"Einstein said that it is theory which decides what is . I think he was right—'observation' is a complicated and theory-laden business. Then that notion should not appear in the formulation of fundamental theory. Information? Whose information? Information about what? On this list of bad words from good books, the worst of all is 'measurement'. It must have a section to itself."

"The concepts 'system', 'apparatus', 'environment', immediately imply an artificial division of the world, and an intention to neglect, or take only schematic account of, the interaction across the split. The notions of 'microscopic' and 'macroscopic' defy precise definition. So also do the notions of 'reversible' and 'irreversible'."