Academics From France

"It is only mental habit that prevents us from realizing how miraculous it is that motion can be passed from one body to another. Once our eyes have opened, nothing is so striking. For those who have never thought about it, it doesn't seem mysterious; by contrast, those who have meditated on it may despair of ever understanding it."

"Research into motion was not to the liking (or perhaps not within the scope) of the ancients, so that we may consider it as a completely new science. How could the ancients have discovered the laws of moiton, given that some philosophers reduced all their speculations about motion to sophistic disputes, whereas others denied that motion existed at all?"

"The quantity of action is the product of the mass of the bodies times their speed and the distance they travel. When a body is transported from one place to another, the action is proportional to the mass of the body, to its speed and to the distance over which it is transported."

"It is interesting to note that Newton was not impressed by Descartes' great argument for God's existence derived from the idea of a perfect Being, nor by other metaphysical arguments that we have mentioned; yet Newton's own arguments for God's existence from the uniformity and suitability of different parts of the universe would not have seemed like proofs to Descartes."

"Despite the disorder observed in Nature, one finds enough traces of the wisdom and power of its Author that one cannot fail to recognize Him."

"One should not be deceived by philosophical works that pretend to be mathematical, but are merely dubious and murky metaphysics. Just because a philosopher can recite the words lemma, theorem and corollary doesn't mean that his work has the certainty of mathematics. That certainty does not derive from big words, or even from the method used by geometers, but rather from the utter simplicity of the objects considered by mathematics."

"On the 15th of April 1744, I described the principle upon which the following work is based, in the public assembly of the Royal Academy of Sciences of Paris, as reported in the Acts of that academy. At the end of the same year, Professor Euler published his excellent book Methodus inveniendi lineas curvas maximi minimive proprietate gaudentes. In a supplement to his book, this illustrious geometer showed that, in the trajectory of a particle acted on by a central force, the velocity multiplied by the line element of the trajectory is minimized. This observation gave me great pleasure, as a beautiful application of my principle to the motion of the planets, which is determined by this principle. From the same principle, I will now try to derive higher and more important truths."

"May we not say that, in the fortuitous combination of the productions of Nature, since only those creatures could survive in whose organizations a certain degree of adaptation was present, there is nothing extraordinary in the fact that such adaptation is actually found in all these species which now exist? Chance, one might say, turned out a vast number of individuals; a small proportion of these were organized in such a manner that the animals' organs could satisfy their needs. A much greater number showed neither adaptation nor order; these last have all perished.... Thus the species which we see today are but a small part of all those that a blind destiny has produced."

"The most beautiful discoveries since the Renaissance, indeed since the beginnings of all science, are the laws governing light, whether moving through a uniform medium, or being reflected from an opaque surface, or changing direction upon entering another transparent medium."

"Let us calculate the motion of bodies, but also consult the plans of the Intelligence that makes them move. It seems that the ancient philosophers made the first attempts at this sort of science, in looking for metaphysical relationships between numbers and material bodies. When they said that God occupies himself with geometry, they surely meant that He unites in that science the works of His power with the perspectives of His wisdom. From the all too few ancient geometers who undertook such studies, we have little that is intelligible or well-founded. The perfection which geometry has acquired since their time puts us in a better position to succeed, and may more than compensate for the advantages that those great minds had over us."

"The supreme Being is everywhere; but He is not equally visible everywhere. Let us seek Him in the simplest things, in the most fundamental laws of Nature, in the universal rules by which movement is conserved, distributed or destroyed; and let us not seek Him in phenomena that are merely complex consequences of these laws."

"I must now explain what I mean by the quantity of action. A certain action is necessary for the carrying of a body from one point to another: this action depends on the velocity which the body has and the space which it describes; but it is neither the velocity nor the space taken separately. The quantity of action varies directly as the velocity and the length of path described; it is proportional to the sum of the spaces, each being multiplied by the velocity with which the body describes it. It is this quantity of action which is here the true expense (dépense) of nature, and which she economizes as much as possible in the motion of light."

"Nature always uses the simplest means to accomplish its effects."

"Everything is so arranged that the blind logic of mathematics executes the will of the most enlightened and free Mind."

"We cannot doubt that all things are regulated by a supreme Being, who, while he has imprinted on matter forces which show his power, has destined it to execute effects which mark his wisdom... Let us calculate the motion of bodies, but let us also consult the designs of the Intelligence which makes them move."

"In many different fields, empirical phenomena appear to obey a certain general law, which can be called the Law of Large Numbers. This law states that the ratios of numbers derived from the observation of a very large number of similar events remain practically constant, provided that these events are governed partly by constant factors and partly by variable factors whose variations are irregular and do not cause a systematic change in a definite direction."

"That which can affect our senses in any manner whatever, is termed matter."

"La vie n'est bonne qu'à deux choses : à faire des mathématiques et à les professer. (The only two good things in life are doing mathematics and teaching it.)"

"[W]e obtain the same correlations of polarizations as in Aspect's first experiments."

"In the ensuing decades, experimentalists performed increasingly sophisticated tests of Bell’s inequalities. But these tests have always had at least one “loophole,”..."

"[B]y closing the two main loopholes at the same time, three teams have independently confirmed that we must definitely renounce local realism... Although their findings are... no surprise, they crown decades of experimental effort. The results... place several fundamental quantum information schemes... as device-independent and s, on firmer ground."

"One of the most puzzling results in modern physics, based originally on... EPR... is the apparent non-locality of measurements in . The experiments performed on pairs of entangled photons, beginning with the experiments by Alain Aspect in 1982, seem to prove... that the two measurements are not independent. The measurements are usually interpreted in terms of the Bell inequalities which assert that their violation, corresponding to the experimental results and... predictions of quantum optics, amounts to a nonlocal connection... There has been... debate on whether such... implies superluminal effects... for example Maudlin's book. The present consensus is that... no information travels faster than light..."

"[In] 1964... John Stewart Bell... discovered inequalities that allow an experimental test of the predictions of local realism against those of standard quantum physics."

"As a witness of that period, I am also deeply convinced that John Bell indirectly played a crucial role in the progress of the application of quantum mechanics to individual objects, microscopic and mesoscopic. The example of his , that had led to the recognition of the importance of entanglement, was no doubt an encouragement to those who were contemplating the possibility of developing new approaches, beyond the so-efficient paradigm developed decades earlier. His example opened the gate for new quantum explorations."

"John Bell devoted most of his efforts to conceptual and theoretical questions. Would he have liked that I also stress the importance of the technological revolutions that were, and will be, enabled by the conceptual revolutions? I cannot tell, but we know that he started his career in accelerator design, and that he always showed a profound respect for technological achievements. I like to think that he would have loved quantum-jumps-based s, as well as entangled s."

"In 1935, Albert Einstein, Boris Podolsky, and (EPR) wrote a now famous paper questioning the completeness of the formalism of quantum mechanics. Rejecting the idea that a measurement on one particle in an entangled pair could affect the state of the other—distant—particle, they concluded that one must complete the quantum formalism in order to get a reasonable, "local realist," description of the world. This view says a particle carries... locally, all the properties determining the results of any measurement... (The ensemble of these properties constitutes the particle’s physical reality.)"

"[W]e... approach... from a new angle. ...[W]e start from the assumption that quantum optics contains, in its mathematical formalism, the answer.... [T]he conceptual difficulty... has been due to the lack of transparency in its mathematical framework. We can formulate this hypothesis in two distinct statements: 1. Quantum optics is complete. 2. The connection between the two photons is due to their common source."

"La principale difficulté pour vulgariser la physique quantique, c'est qu'on ne sait pas très bien comment en fabriquer des images dans notre monde. C'est en ce sens qu'elle est vraiment contre-intuitive."

"The most remarkable feature of Bell's work was undoubtedly the possibility it offered to determine experimentally whether or not Einstein's ideas could be kept. The experimental tests of Bell inequalities gave an unambiguous answer: entanglement cannot be understood as usual correlations, whose interpretation relies on the existence of common properties, originating in a common preparation, and remaining attached to each individual object after separation, as components of their physical reality."

"I think it is not an exaggeration to say that the realization of the importance of entanglement and the clarification of the quantum description of single objects have been at the root of a second quantum revolution, and that John Bell was its prophet. And it may well be that this once purely intellectual pursuit will also lead to a new technological revolution."

"We pretend that if I get result +1 here, immediately the photon there is in the state |x>, but if I find -1, immediately the other photon assume[s] another state of polarization... [T]his image is not acceptable for Einstein because it seems as [though] something is going . ...It is by this ...reasoning that Einstein said... "If you want to make sense of this correlation at a distance, you have to accept that before they arrive at the measuring apparatus, the particles have already a property determining the outcome." ...Bohr disagreed immediately. ...I don't know anybody who finds Bohr's reply understandable. It's not a joke, what I'm going to say, although it sounds [like] a joke. Bohr is so cautious in his wording that he makes it almost impossible to understand... Bohr insisted on... complimentarity, and at one point he declared... that "Clarity and truth are complimentary," and he made all efforts to be as true as possible."

"The second statement relates... that a common source for both photons of an entangled pair is a common feature in all Aspect-type experiments. ...[T]hese ...insights are sufficient to develop a model of photon entanglement accounting for all features in the experiments."

"On graduating from the school, a studious young man who would withstand the tedium and monotony of his duties has no choice but to lose himself in some branch of science or literature completely irrelevant to his assignment."

"Now comes the Einstein–Podolsky–Rosen entangled state. Now I see faces, people saying, "Oh..?" Don't worry! When you go to the concert, you don't need to be able to read the music, to enjoy the music. ...So here... [are] equations. It's a pleasure for my colleague physicists. If you can't read the equation, listen to me. I'm not going to sing, but... listen to the words... the words are... a way of describing the equations, and you don't need to know the mathematics..."

"Certainly we do not need quantum mechanics for macroscopic objects, which are well described by classical physics – this is the reason why quantum mechanics seems so foreign to our everyday existence."

"A mathematician, then, will be defined in what follows as someone who has published the proof of at least one non-trivial theorem."

"In the labs, the young make things move, and the older ones follow like parents evolving with their children."

"Experiments with time-like separation... were only possible about twenty years after the first experiments by Aspect."

"... à plusieurs époques on a pu croire que l'optique était une science finie, où le dernier mot avait été dit, ou presque. Chaque fois la découverte de faits nouveaux, le renversement ou l'élargissement des théories admises, venaient rappeler que la science n'est jamais finie. Cette impression qu'une science est terminée s'est produite bien des fois, dans diverses branches du savoir humain; elle a eu souvent pour cause une explosion de découvertes faites par un homme de génie ou par un petit groupe d'hommes, en un temps si court que les esprits moyens avaient de la peine à suivre et avaient l'inconscient désir de reprendre haleine, de s'habituer aux choses inattendues qui venaient de leur être révélées. Comme éblouis par ces vérités nouvelles, ils ne pouvaient voir ce qui était au-delà. Parfois un siècle entier n'a pas suffi à produire cette accoutumance."

"My whole existence has been devoted to science and to teaching, and these two intense passions have brought me very great joy."

"In fact, without any exaggeration, the current mechanism of money creation through credit is certainly the "cancer" that's irretrievably eroding market economies of private property."

"Too many theorists have a tendency to ignore facts that contradict their convictions."

"Any author who uses mathematics should always express in ordinary language the meaning of the assumptions he admits, as well as the significance of the results obtained. The more abstract his theory, the more imperative this obligation. In fact, mathematics are and can only be a tool to explore reality. In this exploration, mathematics do not constitute an end in itself, they are and can only be a means."

"Anyone who dares to speak about an aether is regarded as an ignorant and backward mind and he can only lose his credibility in scientific circles, although in reality those who criticize him use the same concept of intermediate medium in other words, whether it be fields, an associated fluid, a probability fluid, a pilot fluid, a quantum fluid, etc."

"A theory is only as good as its assumptions. If the premises are false, the theory has no real scientific value. The only scientific criterion for judging the validity of a scientific theory is a confrontation with the data of experience."

"La soumission aux données de l'expérience est la règle d'or qui domine toute discipline scientifique."

"Si l'on s'est quelquefois égaré en voulant simplifier les éléments d'une science, c'est qu'on a établi des systèmes avant d'avoir rassemblé un assez grand nombre de faits. Telle hypothèse, très-simple quand on ne considère qu'une classe de phénomènes, nécessite beaucoup d'autres hypothèses lorsqu'on veut sortir du cercle étroit dans lequel on s'était d'abord renfermé. Si la nature s'est proposé de produire le maximum d'effets avec le minimum de causes, c'est dans l'ensemble de ses lois qu'elle a dû résoudre ce grand problème. Il est sans doute bien difficile de découvrir les bases de cette admirable économie, c'est-à-dire les causes les plus simples des phénomènes envisagés sous un point de vue aussi étendu. Mais, si ce principe général de la philosophie des sciences physiques ne conduit pas immédiatement à la connaissance de la vérité, il peut néanmoins diriger les efforts de l'esprit humain, en l'éloignant des systèmes qui rapportent les phénomènes à un trop grand nombre de causes différentes, et en lui faisant adopter de préférence ceux qui, appuyés sur le plus petit nombre d'hypothèses, senties plus féconds en conséquences."

"We completely ignore the human value of the information. A selection of 100 letters is given a certain information value, and we do not investigate whether it makes sense in English, and, if so, whether the meaning of the sentence is of any practical importance. According to our definition, a set of 100 letters selected at random (according to the rules of Table 1.1), a sentence of 100 letters from a newspaper, a piece of Shakespeare or a theorem of Einstein are given exactly the same informational value."

"With Heisenberg's uncertainty principle, the fundamental role of experimental errors became a basic feature of physics."

"Both the uncertainty principle and the negentropy principle of information make Laplace's scheme [of exact determinism] completely unrealistic. The problem is an artificial one; it belongs to imaginative poetry, not to experimental science."