Physicists From England

"as quoted by Maria Shtilmark in:"

"From 1980 through 1984 Michael Green worked with Schwarz to develop superstring theory, and in 1984 they showed that apparent inconsistencies between superstring theory and quantum theory are circumvented in certain special cases. This work kindled the "first superstring revolution," which led to an explosion of interest in this novel approach to quantum gravity and the unification of the forces."

"String theory has a close relationship to quantum field theory — indeed in some sense it encompasses all interesting quantum field theories."

"How would you get supergravity out of string theory?"

"Woit ... is a blogger – he runs an anti-strings blog, he's an ex-physicist, a PhD I think. ... He has strong views about string theory, which he's entitled to, and he blogs them. And good for him."

"Earthquakes generate elastic waves when one block of material slides against another; the break between the two blocks being called a fault. Explosions generate elastic waves by an impulsive change in volume in the material. Small explosive charges are used in controlled-source seismic experiments in which the waves penetrate only a few kilometres into the earth."

"... since the Second World War ... the proton magnetometer has revolutionized measurements, satellites have given new impetus to magnetic surveying, discoveries of large mineral deposits have maintained activity in conventional magnetic prospecting, and geomagnetism has continued to play a central role in major scientific developments such as plate tectonics (where the time scale of reversals of the polarity of the Earth's magnetic field still provides the main source of information on the movement of the plates.)"

"Two recent studies of the geomagnetic field in the last 1Myr have found 14 excursions, large changes in direction lasting 5–10kyr each, six of which are established as global phenomena by correlation between different sites. The older picture of the geomagnetic field enjoying long periods of stable polarity may not therefore be correct; instead, the field appears to suffer many dramatic changes in direction and concomitant reduction in intensity for 10–20 per cent of the time. During excursions the field may reverse in the liquid outer core, which has timescales of 500yr or less, but not in the solid inner core, where the field must change by diffusion with a timescale of 3kyr. This timescale is consistent with the remarkably uniform duration of well-dated excursions. The disparity of dynamical timescales between the inner and outer cores, a factor of 10, is consistent with the 10 excursions between full reversals."

"Earthquakes radiate waves with periods of tenths of seconds to several minutes. Rocks behave like elastic solids at these frequencies. Elastic solids allow a variety of wave types and this makes the ground motion after an earthquake or explosion (called an event) quite complex. There are two basic types of elastic wave: one involving compression and rarefaction of the elastic material in the direction of propagation of the wave, and one involving no compression but shear of the elastic material perpendicular to its direction of propagation. These are called P and S waves respectively, for primary and secondary since the P wave travels fastest and arrives first."

"After a large earthquake the earth "rings" like a bell; this motion can be observed on sensitive instruments up to a month after a large event. These oscillations have specific frequencies which are properties of the whole earth and which can be measured very accurately indeed. The lowest frequency oscillation has a period of about one hour. Any combination of seismic waves can be represented as an equivalent combination of normal modes. In practice the mode representation is most useful at low frequency — for seismic waves above about 40 s — since at higher frequencies the number of modes becomes prohibitively large."

"The ether was very important and very real to British physicists toward the end of the nineteenth century: to few was it more so than Oliver Lodge (1851–1940)."

"It must be admitted that among a certain number of advanced mathematical physicists whose work has lain mainly in the twentieth century, the ether is regarded with suspicion, or even with contempt. And some of the opponents go so far as to as to say that the nineteenth century idea of the ether has failed to establish itself, and that in consequence the whole idea of the ether is under a cloud, and that it is only upheld by a few antiquated supporters, who, though are willing to admit many modifications in the original nineteenth century notions of an ether, feel the need of a medium capable of performing the functions attributed to it."

"All we know at present of locomotion is the locomotion of one piece of matter with reference to other pieces. That can be freely granted, and the whole edifice of physics is consistent with the idea that locomotion through the ether is impossible to measure. But the impossibility has never been proved, and some day an exceptional phenomenon may be found."

"Our memories are thronged with the past; our anticipations range over the future; and it is in the past and the future that we really live. It is so even with the higher animals: they too order their lives by memory and anticipation."

"It is rather remarkable that the majority of learned men have closed their minds to what seemed bare and simple facts to many people."

"The things to be investigated are either true or false. If false, pertinacious inquiry will reveal their falsity. If true, they are profoundly important. For there are no half-truths in Nature; every smallest departure has portentous consequences; our eyes must open slowly, or we should be overwhelmed."

"Microscopic organisms may have troublesome and destructive effects, but in themselves they can be be studied with interest and avidity."

"I am as convinced of continued existence, on the other side of death, as I am of existence here. It may said, you cannot be sure as you are of sensory experience. I say I can. A physicist is never limited to direct sensory impressions, he has to deal with a multitude of conceptions and things for which he has no physical organ ...."

"Death is not extinction. Neither the soul nor the body is extinguished or put out of existence. The body weighs just as much as before, the only properties it loses at the moment of death are potential properties. So also all we can assert concerning the vital principle is that it no longer animates that material organism: we cannot safely make further assertion regarding it, or maintain its activity or inactivity without further information."

"Death is not a word to fear, any more than birth is. We change our state at birth, and come into the world of air and sense and myriad existence; we change our state at death and enter a region of—what?"

"Every great revelation is likely to have been foreshadowed in more or less imperfect forms, so as to prepare our minds and make ready the way for complete perception hereafter. It is probable that the human race is quite incompetent to receive a really great idea the first time it is offered."

"Life must be considered sui generis; it is not a form of energy, nor can it be expressed in terms of something else."

"It is not the germ cell itself, but the bodily accretion or appendage, which is abandoned by life, and which accordingly, dies and decays."

"What properties are essential to a medium capable of transmitting wave motion? Roughly, we may say two: elasticity and inertia."

"The waves of light are not anything mechanical or material, but are something electrical and magnetic—they are, in fact, electrical disturbances periodic in space and time, and travelling with a known and tremendous speed through the ether of space. Their very existence depends upon the ether, and their speed of propagation is its best known and most certain quantitative property."

"All potential energy exists in the ether. It may vibrate, and it may rotate, but as regards locomotion it is stationary—the most stationary body we know: absolutely stationary, so to speak; our standard of rest."

"Motion and force are our primary objects of experience and consciousness; and in terms of them all other less familiar occurrences may conceivably be studied and grasped."

"A body can only act immediately on what it is in contact with; it must be by the action of contiguous particles—that is, practically, through a continuous medium, that force can be transmitted across space."

"I have made no secret of my conviction, not merely that personality persists, but that its continued existence is more entwined with the life of every day than has been generally imagined; that there is no real breach of continuity between the dead and the living; and that methods of intercommunion across what has been deemed a gulf can be set going in response to the urgent demand of affection,—that in fact as Diotima told Socrates (Symposium, 202 and 203),"

"The oldest and best known function for an ether is the conveyance of light, and hence the name "luminiferous" was applied to it, though at the present day many functions are known, and more will almost certainly be discovered."

"I will add another thing which I also had from Dr. Bentley himself. Mr. Halley was then thought of for successor, to be in a mathematick professorship at Oxford; and bishop Stillingfleet was desired to recommend him at court; but hearing that he was a sceptick, and a banterer of religion, he scrupled to be concern'd; 'till his chaplain, Mr. Bentley, should talk with him about it; which he did. But Mr. Halley was so sincere in his infidelity, that he would not so much as pretend to believe the christian religion, tho' he thereby was likely to lose a professorship; which he did accordingly; and it was then given to Dr. Gregory: Yet was Mr. Halley afterwards chosen into the like professorship there, without any pretence to the belief of christianity. Nor was there any enquiry made about my successor Mr. Sandersons christianity, even when the university of Cambridge had just banished me for believing and examining it so throughly, that I hazarded all I had in the world for it."

"The principal Use therefore of this Table of the Elements of their Motions, and that which induced me to construct it, is, That whenever a new Comet shall appear, we may be able to know, by comparing together the Elements, whether it be any of those which has appear'd before, and consequently to determine its Period, and the Axis of its Orbit, and to foretell its Return. And, indeed, there are many Things which make me believe that the Comet which Apian observ'd in the Year 1531, was the same with that which Kepler and Longomontanus took Notice of and describ'd in the Year 1607, and which I my self have seen return, and observ'd in the Year 1682."

"All the Elements agree, and nothing seems to contradict this my Opinion, besides the Inequality of the Periodick Revolutions: Which Inequality is not so great neither, as that it may not be owing to Physical Causes. For the Motion of Saturn is so disturbed by the rest of the Planets, especially Jupiter, that the Periodick Time of that Planet is uncertain for some whole Days together. How much more therefore will a Comet be subject to such like Errors, which rises almost Four times higher than Saturn, and whose Velocity, tho' encreased but a very little, would be sufficient to change its Orbit, from an Elliptical to a Parabolical one."

"[I]n the Year 1456, in the Summer time, a Comet was seen passing Retrograde between the Earth and the Sun, much after the same Manner: Which, tho' no Body made Observations upon it, yet from its Period, and the Manner of its Transit, I cannot think different from those I have just now mention'd. Hence I dare venture to foretell, That it will return again in the Year 1758. And, if it should then return, we shall have no Reason to doubt but the rest must return too: Therefore Astronomers have a large Field to exercise themselves in for many Ages, before they will be able to know the Number of these many and great Bodies revolving about the common Center of the Sun; and reduce their Motions to certain Rules."

"s production was not without drama. ... ... The had promised to publish the work, but now pulled out, citing financial embarrassment. The year before the society had backed a costly flop called ', and they now suspected that the market for a book on mathematical principles would be less than clamorous. Halley, whose means were not great, paid for the book's publication out of his own pocket. Newton, as was his custom, contributed nothing. To make matters worse, Halley at this time had just accepted a position as the society's clerk, and he was informed that the society could no longer afford to provide him with a promised salary of £50 per annum. He was to be paid instead in copies of The History of Fishes."

"I design to treat of all these Things in a larger Volume, and contribute my utmost for the Promotion of this Part of Astronomy, if it shall please God to continue my Life and Health."

"In the mean time, those that desire to know how to construct Geometrically the Orb of a Comet, by Three accurate Observations given, may find it at the End of the Third Book of Sir Isaac Newtons Principles of Natural Philosophy, entituled De Systemate Mundi, in the Words of its renowned Inventor. Which have since been more fully explained by my very worthy Collegue Dr. Gregory, in his Learned Work of Astronomia Physica & Geometrica."

"The Construction and Use of the general Table.As the Planets move in Elliptick Orbs, so do the Comets in Parabolick ones, having the Sun in their common Focus, and describe equal Areas in equal Times. But now because all s are similar to one another, therefore if any determinate Part of the Area of a given Parabola, be divided into any Number of Parts at Liberty, there will be a like Division made in all Parabolas, under the same Angles, and the Distances will be proportional: And consequently this one Table of ours will serve for all Comets."

"These necessary Things premis'd, let it be propos'd to compute the apparent Place of any one of the mention'd Comets, for any Given Time."

"5. From these Things given (by the very same Rules that we find the Planets Places, from the Suns Place and Distance given) we may obtain the Apparent or Geocentrick Place of the Comet, together with the Apparent Latitude. And this it may be worth while to illustrate by an Example or two."

"A General Table for Calculating the Motions of Comets in a Parabolical Orbit."

"Not long after, that Great Geometrician, the Illustrious Newton, writing his Mathematical Principles of Natural Philosophy, demonstrated not only that what Kepler had found, did necessarily obtain in the Planetary System; but also, that all the Phænomena of Comets wou'd naturally follow from the same Principles; which he abundantly illustrated by the Example of the aforesaid Comet of the Year 1680, shewing, at the same time, a Method of Delineating the Orbits of Comets Geometrically; wherein he (not without the highest Admiration of all Men) solv'd a Problem, whose Intricacy render'd it worthy of himself. This Comet he prov'd to move round the Sun in a Parabolical Orb, and to describe Area's (taken at the Center of the Sun) proportional to the Times."

"Wherefore (following the Steps of so Great a Man) I have attempted to bring the same Method to Arithmetical Calculation; and that with desired Success. For, having collected all the Observations of Comets I could, I fram'd this Table, the Result of a prodigious deal of Calculation, which, tho' but small in Bulk, will be no unacceptable Present to Astronomers. For these Numbers are capable of Representing all that has been yet observ'd about the Motion of Comets, by the Help only of the following General Table; in the making of which I spar'd no Labour, that it might come forth perfect, as a Thing consecrated to Posterity, and to last as long as Astronomy it self."

"After this manner... the Astronomical Reader may examine these Numbers, which I have calculated, with all imaginable Care, from the Observations I have met with. And I have not thought fit to make them publick before they have been duly examin'd, and made as accurate as 'twas possible, by the Study of many Years. I have publish'd this Specimen of Cometical Astronomy, as a Prodromus of a designed future Work, left, happening to die, these Papers might be lost, which every Man is not capable to retrieve, by reason of the great Difficulty of the Calculation."

"The Astreonomical Elements of the Motions in a Parabolick Orb of all the Comets that have been hitherto duly obferv'd. ...This Table needs little Explication, since 'tis plain enough from the Titles, what the Numbers mean. Only it maybe observ'd, that the Perihelium Distances, are estimated in such Parts, as the Middle Distance of the Earth from the Sun, contains 100000."

"Next to Ticho, came the Sagacious Kepler. He having the Advantage of Tichos Labours and Observations, found out the true Physical System of the World, and vastly improv'd the Astronomical Science. For he demonstrated that all the Planets perform their Revolutions in Elliptick Orbits, whose 'Plains pass thro' the Center of the Sun, observing this Law, That the Area's (of the Elliptick Sectors, taken at the Center of the Sun, which he proved to be in the common Focus of these Ellipses) are always proportional to the Times, in which the correspendent Elliptical Arches are describ'd. He discover'd also, That the Distances of the Planets from the Sun are in the Ratio [3:2] of the Periodical Times, or (which is all one) That the Cubes of the Distances are as the Squares of the Times. This great Astronomer had the Opportunity of observing Two Comets, one of which was a very remarkable one. And from the Observations of these (which afforded sufficient Indications of an Annual Parallax) he concluded, That the Comets mov'd freely thro' the Planetary Orbs, with a Motion not much different from a Rectilinear one; but of what Kind, he cou'd not then precisely determine."

"Next, Hevelius (a Noble Emulator of Ticho Brahe) following in Keplers Steps, embraced the same Hypothesis of the Rectilinear Motion of Comets, himself accurately observing many of them. Yet, he complain'd, that his Calculations did not perfectly agree to the Matter of Fact in the Heavens: And was aware, that the Path of a Comet was bent into a Curve Line towards the Sun."

"By comparing together the Accounts of the Motions of these Comets, 'tis apparent, their Orbits are dispos'd in no manner of Order; nor can they, as the Planets are, be comprehended within a Zodiack, but move indifferently every Way, as well Retrograde as Direct; from whence it is clear, they are not carry'd about or mov'd in 'Vortices'. Moreover, the Distances in their Perihelium's are sometimes greater, sometimes less; which makes me suspect, there may be a far greater Number of them, which moving in Regions more remote from the Sun, become very obscure; and wanting Tails, pass by us unseen."

"At length, came that prodigious Comet of the Year 1680, which descending (as it were) from an infinite Distance Perpendicularly towards the Sun, arose from him again with as great a Velocity. This Comet, (which was Seen for Four Months continually) by the very remarkable and peculiar Curvity of its Orbit (above all others) gave the fittest Occasion for investigating the Theory of the Motion. And the Royal Observatories at Paris and Greenwich having been for some time founded, and committed to the Care of most excellent Astronomers, the apparent Motion of this Comet was most accurately (perhaps as far as Humane Skill cou'd go) observ'd by Mrs. Cassini and Flamsteed."

"Hitherto I have consider'd the Orbits of Comets as exactly Parabolick; upon which Supposition it wou'd follow, that Comets being impell'd towards the Sun by a Centripetal Force, descend as from Spaces infinitely distant, and by their Falls acquire such a Velocity, as that they may again run off into the remotest Parts of the Universe, moving upwards with such a perpetual Tendency, as never to return again to the Sun. But since they appear frequently enough, and since none of them can be found to move with an Hyperbolick Motion, or a Motion swifter than what the... Comet might acquire by its Gravity to the Sun, 'tis highly probable they rather move in very Excentrick Orbits, and make their Returns after long Periods of Time: For so their Number will be determinate, and, perhaps, not so very great. Besides, the Space between the Sun and the fix'd Stars is so immense, that there is Room enough for a Comet to revolve, tho' the Period of its Revolution be vastly long."