physicists-from-israel

"Ultimately, we hope to find a fundamental theory that explains everything with no input parameters."

"Supersymmetry arises naturally in string theory. (It was originally motivated by string theory.)"

"The quantum dualities, which are known as S-duality or U-duality, extend the classical T-duality and lead to a beautiful and coherent picture of stringy dualities. These exchange highly quantum situations with semiclassical backgrounds, exchange different branes, etc. As in the classical dualities, among all dual descriptions there is at most one description which is natural because it is semiclassical. All other dual descriptions are very quantum mechanical."

"Most string theorists are very arrogant ... If there is something [beyond string theory], we will call it string theory."

"Gravity is not an option in string theory. It is a logical consequence of it!"

"Whenever you work on something and try to solve one problem, and you end up helping or solving many other problems, it is a sign that what you are doing is good."

"Black holes set a limitation on the number of species of elementary particles—quarks, leptons, neutrinos—which may exist. And black holes lead to a fundamental limitation on the rate at which information can be transferred for given message energy by any communication system."

"In a previous paper we showed that a static (nonrotating) black hole cannot be endowed with exterior scalar-meson or massive vector-meson fields. Here we show that the same is true for massive spin-2 meson fields. We also extend the above results to the case of a rotating stationary black hole. We conclude from our results that a black hole in its final (static or stationary) state cannot interact with the exterior world via the strong interactions which are mediated by meson fields such as the π (scalar), ρ (vector), and ƒ (spin-2). A direct consequence of this is the impossibility of determining the baryon number of the black hole by means of exterior measurements alone. This results in the transcendence of the law of baryon-number conservation as originally predicted by Wheeler."

"We show that it is natural to introduce the concept of black-hole entropy as the measure of information about a black-hole interior which is inaccessible to an exterior observer. Considerations of simplicity and consistency, and dimensional arguments indicate that the black-hole entropy is equal to the ratio of the black-hole area to the square of the Planck length times a dimensionless constant of order unity. A different approach making use of the specific properties of Kerr black holes and of concepts from information theory leads to the same conclusion, and suggests a definite value for the constant."

"Jacob was the first physicist to hear from me about MOND. It was 1982; Jacob was still at Ben Gurion University in Beer Sheba. I went there from Rehovot with my initial MOND trilogy of preprints in my bag to tell Jacob and benefit from his advice. I had not prepared him for what was in these preprints. Jacob was immediately captured, but he also warned me — as I vividly remember — that this is going to encounter much opposition, but also that I should not heed such opposition. He was drawing on his own experience with black-hole entropy and on how his ideas had been received a decade earlier."

"Bekenstein incorporated black hole entropy into a generalized second law—that the sum of the entropy outside black holes plus the newly proposed entropy of black holes must never decrease—and carefully considered processes that might violate it. To avoid violations, he found that he had to assume limitations on how close to the black hole’s horizon one could lower matter. Those ideas eventually evolved into a proposal for a bound on the entropy-to-energy ratio of matter confined to a region of given size."

"There is a prescription that works well, MOND, but the reason it works so well is not known. You may say that MOND tells us how the real theory of gravity should look."

"Within the DM paradigm the Tully-Fisher law must arise from galaxy formation since it connects luminosity of baryonic matter with a dynamical property, rotation, which is seen as dominated by the DM halo. But it has not been easy to derive Tully-Fisher from any natural connection between the two components. And as R. H. Sanders has pointed out, the messiness of galaxy formation is hardly the natural backdrop for such a sharp correlation between galaxy properties. The sharpness needs a dynamical reason as opposed to an evolutionary one."

"The DM halo hypothesis is evidently an attempt to resolve the acceleration discrepancy within orthodox gravitation theory. But in coming to terms with this discrepancy, suspicion fell on Newtonian gravity already early in the game. Zwicky, who had exposed the acceleration discrepancy in clusters of galaxies ..., opined much later that the discrepancy may reflect a failure of conventional physics ..."

"It seems to me that in understanding MOND and its fundamentals we have only scratched the surface. If the developments of quantum mechanics and relativity are any lesson here, departures of such magnitude from long- and well-tested physics may bring with them completely new concepts, not summarized by mere modifications of the governing actions or the equations of motion. MOND may also turn out to bring in concepts that are presently beyond our ken (as hinted perhaps by the cosmological connotations of a0)."

"What struck me was some regularity in the anomaly. The rotational velocities were not just larger than expected, they became constant with radius. Why? Sure, if there was dark matter, the speed of stars would be greater, but the rotation curves, meaning the rotational speed drawn as a function of the radius, could still go up and down depending on its distribution. But they didn't. That really struck me as odd. So, in 1980, I went on my Sabbatical in the Institute for Advance Studies in Princeton with the following hunch: If the rotational speeds are constant, then perhaps we’re looking at a new law of nature. If Newtonian physics can’t predict the fixed curves, perhaps we should fix Newton, instead of making up a whole new class of matter just to fit our measurements."

"The nice thing is that MOND has not had to change or adjust itself to the many observations that came after it was proposed. … In the end, the process that might sway people's minds could be a slow one, in which they become disillusioned and dissatisfied with DM, while MOND explains more and more of the observations. And, if MOND does turn out to have some truth to it, the fact that it encountered so much opposition will just show how nontrivial a thought it was."

"I did encounter much opposition and sheer disregard, and this was against my expectation. I was surprised that people thought that this was not a legitimate avenue to explore. Many times I heard people say that it is too early to start considering such heretical ideas. Why? I wondered. I thought it was legitimate to consider anything."

"What makes MOND particularly intriguing is that it predicted many effects that could not even be tested when I formulated it."

"Of all of the many mysteries of modern astronomy, none is more vexing than the nature of dark matter... This dark matter has eluded every effort by astronomers and physicists to bring it out of the shadows. A handful of us suspect that it might not really exist, and others are beginning to consider this possibility seriously."

"Dark matter cannot be any sort of matter that is known to science."

"To explain the appearance in MOND of a cosmological acceleration constant, a0, I suggest that MOND inertia — as embodied in the actions of free particles and fields — is due to effects of the vacuum. The same vacuum effects enter both MOND (through a0) and cosmology e.g. through a cosmological constant Λ)."

"[Operating expense is defined as] all the money the system spends in turning inventory into throughput."

"My system does not make sense at all, but by God it’s working."

"I smile and start to count on my fingers: One, people are good. Two, every conflict can be removed. Three, every situation, no matter how complex it initially looks, is exceedingly simple. Four, every situation can be substantially improved; even the sky is not the limit. Five, every person can reach a full life. Six, there is always a win / win solution. Shall I continue to count?"

"If the goal is to make money, then (putting it in terms Jonah might have used), an action that moves us toward making money is productive. And an action that takes away from making money is non-productive."

"There are three measurements which express the goal of making money perfectly well, but which also permit you to develop operational rules for running your plant. Their names are throughput, inventory and operational expense."

"Fundamentally, a manager is looking to answer these questions: ‘what to change?’,’ what to change to?’ and ‘ how to cause the change?’"

"[Throughput is the] rate at which the system generates money through sales."

"[Inventory is measured by] the money the system invests in purchasing things the system intends to sell."

"Tell me how you measure me, and I will tell you how I will behave."

"Companies are so immersed in the mentality of saving money that they forget that the whole intention of a project is not to save money but to make money."

"Quantum phenomena do not occur in a Hilbert space. They occur in a laboratory."

"Unperformed experiments have no results."

"Some authors state that the last stage in this chain of measurements involves "consciousness," or the "intellectual inner life" of the observer, by virtue of the "principle of psycho-physical parallelism." Other authors introduce a wave function for the entire universe. In this book, I shall refrain from using concepts that I do not understand."

"Necessary truth is merely the subject-matter of mathematics, not the reward we get for doing mathematics. The object of mathematics is not, and cannot be, mathematical certainty. It is not even mathematical truth, certain or otherwise. It is, and must be, mathematical explanation."

"Any theory about improvement raises the question: how is the knowledge of how to make that improvement created? Was it already present at the outset? The theory that it was is creationism. Did it ‘just happen’? The theory that it did is spontaneous generation."

"That progress is both possible and desirable is perhaps the quintessential idea of the Enlightenment. It motivates all traditions of criticism, as well as the principle of seeking good explanations. But it can be interpreted in two almost opposite ways, both of which, confusingly, are known as ‘perfectibility’. One is that humans, or human societies, are capable of attaining a state of supposed perfection – such as the Buddhist or Hindu ‘nirvana’, or various political utopias. The other is that every attainable state can be indefinitely improved. Fallibilism rules out that first position in favour of the second."

"The misconception that knowledge needs authority to be genuine or reliable dates back to antiquity, and it still prevails. To this day, most courses in the philosophy of knowledge teach that knowledge is some form of justified, true belief, where ‘justified’ means designated as true (or at least ‘probable’) by reference to some authoritative source or touchstone of knowledge."

"Experience is indeed essential to science, but its role is different from that supposed by empiricism. It is not the source from which theories are derived. Its main use is to choose between theories that have already been guessed. That is what ‘learning from experience’ is."

"Kuhn's theory suffers from a fatal flaw. It explains the succession from one paradigm to another in sociological or psychological terms, rather than as having primarily to do with the objective merit of the rival explanations. Yet unless one understands science as a quest for explanations, the fact that it does find successive explanations, each objectively better than the last, is inexplicable."

"Time travel may be achieved one day, or it may not. But if it is, it should not require any fundamental change in world-view, at least for those who broadly share the world view I am presenting in this book."

"Mathematical knowledge may, just like our scientific knowledge, be deep and broad, it may be subtle and wonderfully explanatory, it may be uncontroversially accepted; but it cannot be certain."

"If something is permitted by the laws of physics, then the only thing that can prevent it from being technologically possible is not knowing how."

"Let me define that [wealth] in a non-parochial way as the repertoire of physical transformations that they would be capable of causing."

"Could it be that the moral imperative not to destroy the means of correcting mistakes is the only moral imperative? That all other moral truths follow from it?"

"As I understand it, the claim is that the less you use Homeopathy, the better it works. Sounds plausible to me."

"The rational thing for a layperson to do is to take seriously the prevailing scientific theory."

"Native slipstream thinking, which has been around for millennia, anticipated recent cutting-edge physics, ironically suggesting that Natives have had things right all along. The closest approximation in quantum mechanics is the concept of the "multiverse," which posits that reality consists of a number of simultaneously existing alternate worlds and/or parallel worlds. Interested readers will enjoy John Gribbin's In Search of the Multiverse: Parallel Worlds, Hidden Dimensions, and the Quest for the Frontiers of Reality (2010) and David Deutsch's seminal The Fabric of Reality: The Science of Parallel Universes and Its Implications (1998). Deutsch's approach describes reality as "an infinite library full of copies of books that all start out the same way on page one, but in which the story in each book deviates more and more from the versions in the other books the farther into the book you read." The further twist of Deutsch's theory is that it "allows universes to merge back together... as if two of the books in the library have the same happy ending arrived at by different routes.""

"Reality contains not only evidence, but also the means (such as our minds, and our artefacts) of understanding it. There are mathematical symbols in physical reality. The fact that it is we who put them there does not make them any less physical."