Cosmologists

"I... propose that time and its passage are fundamental and real and the hopes and beliefs about timeless truths and timeless realms are mythology."

"The positive energy theorem was for half a century or more an open challenge to relativists. Many attempts were made to prove flat spacetime was stable, but none completely succeeded completely until a majestic tour de force of geometric reasoning of Shoen and Yau. This was followed two years later by a proof of Witten, which was as elegant as it was short. It is this proof of Witten’s that we take as a template here for the quantum theory."

"If we believe that the task of physics is the discovery of a timeless mathematical equation that captures every aspect of the universe, then we believe that the truth about the universe lies outside the universe."

"The hypothesis underlying all approaches to the landscape is that there is a cosmological setting in which different regions or epochs of the universe can have different effective laws. This implies the existence of spacetime regions not directly observable... These regions must either be in the past of our big bang, or far enough away from us to be causally unrelated."

"The landscape problem represents a serious problem in the development of science. Its solution requires... the construction of speculative cosmological scenarios, which posit regions or epochs of our universe for which we presently have no observable evidence. Nonetheless we must insist on taking seriously only scenarios and hypotheses that make falsifiable or strongly verifiable predictions, otherwise people can just make stuff up and the distinction between science and mythology becomes porous. ...there are already candidate solutions that make real, falsifiable predictions."

"The landscape problem and the problem of background independence are closely linked. The latter is the only route the former has to experimental confirmation."

"Special pleading that the standards of science should be lessened to admit explanations with no falsifiable consequences, in order to keep alive a bold speculative idea, should be strongly resisted. ...ultimately science is not interested in what might be true, it is interested only in what can be convincingly demonstrated by deductions from observational evidence."

"Many of the founders of quantum mechanics, including Einstein, Erwin Schrödinger, and Louis de Broglie... were realists. For them quantum theory... was not a complete theory, because it did not provide a picture of reality absent our interaction with it. On the other side were Niels Bohr, Werner Heisenberg, and many others. Rather than being appalled, they embraced this new way of doing science."

"Many of us believed in the possibility of a principled explanation for the laws of nature. We hoped to discover a short list of principles, which could be realized in a unique theory, which would retrodict the standard model and uniquely predict the physics to be discovered beyond it. The shocking implication of the results of Strominger reported in 1986 was that it was not to be, at least within the confines of string theory. ...String theory offered more, however... It offered the promise of a setting in which the different perturbative string theories are realized as expansions around solutions of a still more fundamental theory. ...That more fundamental theory would have to be background independent..."

"Having begun my life in science searching for the equation beyond time, I now believe that the deepest secret of the universe is that its essence rests in how it unfolds moment by moment in time."

"Unfortunately, so far... a truly background independent formulation of string theory has not been achieved... [It is] often called the search for M theory..."

"Relativity and... quantum... remain incomplete. ...the main reason each is incomplete is the existence of the other. The mind calls for a third theory to unify all of physics, and for a simple reason. Nature is... "unified." …interconnected, in that everything interacts with everything else."

"Combine general relativity and quantum theory into a single theory that can claim to be the complete theory of nature. This is called the problem of quantum gravity."

"In both quantum theory and general relativity, we encounter predictions of physically sensible quantities becoming infinite. This is likely the way that nature punishes impudent theorists who dare to break her unity. ...If infinities are signs of missing unification, a unified theory will have none. It will be what we call a finite theory."

"Quantum theory can be described as a new kind of language to be used in a dialogue between us and the systems we study with our instruments. ...It tells us nothing about what the world would be like in our absence."

"We seem to have an ingrained idea that if something is valuable, it exists outside of time."

"Time is that which is measured by a clock. This is a sound way of looking at things. A quantity like time, or any other physical measurement, does not exist in a completely abstract way. We find no sense in talking about something unless we specify how we measure it. It is the definition by the method of measuring a quantity that is the one sure way of avoiding talking nonsense about this kind of thing."

"The landscape has been so totally changed, the ways of thinking have been so deeply affected, that it is very hard to get hold of what it was like before... It is very hard to realize how total a change in outlook Isaac Newton has produced."

"All science is full of statements where you put the best face on your ignorance, where you say: true enough, we know awfully little about this, but more or less irrespective of the stuff we don't know about, we can make certain useful deductions."

"The kind of lecture which I have been so kindly invited to give, and which now appears in book form, gives one a rare opportunity to allow the bees in one's bonnet to buzz even more noisily than usual."

"On the most usual assumption, the universe is homogeneous on the large scale, i. e. down to regions containing each an appreciable number of nebulae. The homogeneity assumption may then be put in the form: An observer situated in a nebula and moving with the nebula will observe the same properties of the universe as any other similarly situated observer at any time."

"The Big Bang theory has been extremely successful in describing the history and evolution of the Universe, and new experiments and observations continue to confirm the basic predictions of this theory. But we do not yet know the answer to the question"

"Neutrinos are fundamental subatomic particles produced in nuclear reactions, like those in the sun. We always talk about the fact that we can’t see neutrinos or dark matter and that basically they’re invisible, but if you think about it from the other side, we’re also invisible to them."

"Nothing in nature or the cosmos is ever completely still — as I write this, several wild Mallards have returned to the Museum courtyard and are creating a frantic spectacle of water and wings as they dive and attack in their annual spring ritual. Further from home, a supermassive black hole at the center of a galaxy 56 million light years from Earth has recently been observed to be spinning at close to the speed of light."

"William Gilbert of Colchester, Physician of London: On the Load Stone and Magnetic Bodies by William Gilbert, Edward Wright; J. Wiley & Sons (1893) public domain @GoogleBooks."

"Gilbert does not seem to have known that there were any other bodies than iron or the lodestone that possessed magnetic properties; for he called particular attention to the fact that all other substances that possessed magnetism to some degree owe their power to the presence of iron in some condition or other."

"When Gilbert of Colchester, in his “New Philosophy,” founded on his researches in magnetism, was dealing with tides, he did not suggest that the moon attracted the water, but that “subterranean spirits and humors, rising in sympathy with the moon, cause the sea also to rise and flow to the shores and up rivers”. It appears that an idea, presented in some such way as this, was more readily received than a plain statement. This so-called philosophical method was, in fact, very generally applied, and Kepler, who shared Galileo’s admiration for Gilbert’s work, adopted it in his own attempt to extend the idea of magnetic attraction to the planets."

"In 1626 Bacon succumbed to the results of his ill timed experiment in preserving chickens with snow... The Bacon manuscripts were sent to [Sir William] Boswell's residence at the Hague, and there lay until Boswell, who died in 1647, confided them to the editorial care of Isaac Gruter who... published them all together in 1653. Among the papers which thus came into his hands, Gruter found the two manuscripts of William Gilbert, of Colchester, which William Gilbert, of Melford, had prepared, and these he edited and issued... in 1651."

"The significant fact lies in the possession of the manuscripts by Bacon during his lifetime. He studied them, he knew their contents. And in those great Monuments wherein he has invoked for his own fame the judgment of the next age, he attacks and condemns over and over again the opinions of a man who could neither speak for himself, being in his grave, nor be spoken for by the only written words wherein he had set them forth, and which in the cabinet of my Lord Verulam, were as effectually silenced and entombed."

"The "New Philosophy" [De Mundo Nostro Sublunari Philosophia Nova] of Gilbert came to be published half a century after his death in the following curious circumstances. Within the period of apparently some two years after his demise, William Gilbert, of Melford, his elder brother, bearing, oddly enough, the same name... found, among Gilbert's scattered papers, the fragmentary New Philosophy and the Meteorology. These (as he says, being governed by fraternal affection, as well as by an appreciation of the importance of the arguments advanced, whereof he felt unwilling to deprive the world), he arranged, caused to be translated into Latin, and prefixed to them a dedication... That he intended to publish the book is clear; nevertheless, he departed, as its author had done with his purpose unfulfilled."

"The famous treatise which opened the modern era by treating magnetism and electricity on a scientific basis appeared just 300 years ago. The author, William Gilbert, M.D., of Colchester... was an exact and diligent explorer, first of chemical and then of magnetic and electric phenomena. ...Working nearly a century before the time when the astronomical discoveries of Newton had originated the idea of attraction at a distance, he established a complete formulation of the interaction of magnets by what we now call the exploration of their fields of force. His analysis of the facts of magnetic influence, and incidentally of the points in which it differs from electric influence, is virtually the one which Faraday reintroduced. A cardinal advance was achieved, at a time when the Copernican Astronomy had still largely to make its way, by assigning the behavior of the compass and the dip needle to the fact that the earth itself is a great magnet, by whose field of influence they are controlled. His book passed through many editions on the Continent within forty years; it won the high praise of Galileo. Gilbert has been called the 'father of modern electricity' by Priestley, and 'the Galileo of magnetism' by Poggendorff."

"[Gilbert] has himself become a magnet; that is, he has ascribed too many things to that force and built a ship out of a shell."

"Gilbert shall live till loadstones cease to draw, Or British fleets the boundless ocean awe."

"The Alchemists have made a philosophy out of a few experiments of the furnace and Gilbert our countryman hath made a philosophy out of observations of the lodestone."

"How far away from the earth are those remotest of stars: they are beyond the reach of eye, or man's devices, or man's thought. What an absurdity is this motion (of spheres). He also argues for the extreme variability of the distance to the various heavenly bodies and states that situated "in thinnest aether, or in the most subtle fifth essence, or in vacuity - how shall the stars keep their places in the mighty swirl of these enormous spheres composed of a substance of which no one knows aught?"

"In the discovery of hidden things and in the investigation of hidden causes, stronger reasons are obtained from sure experiments and demonstrated arguments than from probable conjectures and the opinions of philosophical speculators of the common sort."

"Gilbert... repeatedly asserts the paramount value of experiments. He himself, no doubt, acted up to his own precepts; for his work contains all the fundamental facts of the science [of magnetism], so fully examined, indeed, that even at this day we have little to add to them."

"We, therefore, having directed our inquiry toward a cause that is manifest, sensible, and comprehended by all men, do know that the earth rotates on its own poles, proved by many magnetical demonstrations to exist. For not in virtue only of its stability and its fixed permanent position does the earth possess poles and verticity; it might have had another direction, as eastward or westward, or toward any other quarter. By the wonderful wisdom of the Creator, therefore, forces were implanted in the earth, forces primarily animate, to the end the globe might, with steadfastness, take direction, and that the poles might be opposite, so that on them, as at the extremities of an axis, the movement of diurnal rotation might be performed."

"The electric effluvia differ much from air, and as air is the earth's effluvium, so electric bodies have their own distinctive effluvia; and each peculiar effluvium has its own individual power of leading to union, its own movement to its origin, to its fount, and to the body emitting the effluvium."

"Only on the superficies of the globes is plainly seen the host of souls and of animate existences, and their great and delightful diversity the Creator taketh pleasure"

"Gilbert, in his work, De Magnete printed in 1600 has only some vague notions that the magnetic virtue of the earth in some way determines the direction of the earth's axis, the rate of its diurnal rotation, and that of the revolution of the moon about it. Gilbert died in 1603, and in his posthumous work (De Mundo nostro Sublunari Philosophia nova, 1631) we have already a more distinct statement of the attraction of one body by another. "The force which emanates from the moon reaches to the earth, and, in like manner, the magnetic virtue of the earth pervades the region of the moon: both correspond and conspire by the joint action of both, according to a proportion and conformity of motions, but the earth has more effect in consequence of its superior mass; the earth attracts and repels, the moon, and the moon within certain limits, the earth; not so as to make the bodies come together, as magnetic bodies do, but so that they may go on in a continuous course." Though this phraseology is capable of representing a good deal of the truth, it does not appear to have been connected... with any very definite notions of mechanical action in detail."

"Neither in any if the stars, nor in the sun, nor in the planets that are most operant in the world, can organs be disntinguished or imagined by us; nevertheless, they live and endow with life small bodies at the earth's elevated points. If there is aught of which man may boast, that of a surety is soul, is mind; and the other animals, too, are ennobled by soul; even God, by whose rod all things are governed, is soul."

"Lucid gems are made of water; just as Crystal, which has been concreted from clear water, not always by a very great cold, as some used to judge, and by very hard frost, but sometimes by a less severe one, the nature of the soil fashioning it, the humour or juices being shut up in definite cavities, in the way in which spars are produced in mines."

"The year 1600 was the first in which England produced a remarkable work in physical science; but this was one sufficient to raise a lasting reputation to its author. Gilbert, a physician, in his Latin treatise on the magnet, not only collected all the knowledge which others had possessed on that subject, but became at once the father of experimental philosophy in this island, and by a singular felicity and acuteness of genius, the founder of theories which have been revived after the lapse of ages, and are almost universally received into the creed of the science. The magnetism of the earth itself, his own original hypothesis... was by no means one of those vague conjectures... He relied on the analogy of terrestrial phenomena to those exhibited by what he calls a terrella, or artificial spherical magnet. ...Gilbert was also one of our earliest Copernicans, at least as to the rotation of the earth; and with his usual sagacity inferred, before the invention of the telescope, that there are a multitude of fixed stars beyond the reach of our vision."

"This is the only sure way I know to counter the anti-Copernican idea that the universe is accelerating in our epoch - to get rid of the problem entirely!"

"Indeed, there is a now a minority of cosmologists who question a beginning of the universe at all; instead they favor a cyclic model with a series of expansions and contractions."

"A large part of the relativity community is in denial - refusing even to contemplate the idea that black holes may not exist in nature, or seriously consider the idea that any kind of new matter such as the new putative dark energy can play a fundamental role in gravity theory."

"To physicists such as myself, the huge amount of invisible dark matter needed to make Einstein's theory fit the astrophysical data is reason enough for exploring modified gravity theories."

"It is difficult to falsify the hypothesis of dark matter, because, as with Ptolemy's epicycles, true believers can always add additional arbitrary features and free parameters to overcome any conceivable difficulties that occur with the dark matter models."

"This is an extraordinary time in the history of science, in that we cannot only theorize about the beginning of the universe, but actually study the celestial fossils of how it happened."