Fixed points of quantum gravity in extra dimensions

The mysteries of the atom Quantum mechanics The atom is one of the most fundamental building blocks of matter, and its mysteries have fascinated scientists for centuries. The study of the atom has led to the development of quantum mechanics, a branch of physics that seeks to understand the behavior of atoms and other subatomic particles. Quantum mechanics has led to many groundbreaking discoveries, but it is also a field that is full of mysteries and unanswered questions.One of the most intriguing mysteries of the atom is its behavior at the quantum level. At this level, particles do not behave in the same way as they do in our everyday world. They can be in two places at once, and they can exist in multiple states simultaneously. This strange behavior is known as superposition, and it is one of the key principles of quantum mechanics.Another mystery of the atom is the concept of entanglement. This is a phenomenon in which two particles become linked in such a way that the state of one particle is dependent on the state of the other, no matter how far apart they are. This idea was first proposed by Albert Einstein, who famously referred to it as \"spooky action at a distance.\" Despite its strangeness, entanglement has been observed in numerous experiments and is now considered to be a fundamental aspect of quantum mechanics.The mysteries of the atom also extend to the nature of particles themselves. In our everyday world, particles are either matter or energy, but at the quantum level, these distinctions break down. Particles can exist as both matter and energy simultaneously, and they can even transform from one to the other. This is known as wave-particle duality, and it is another key principle of quantum mechanics.The behavior of particles at the quantum level has led to some of the most remarkable discoveries in modern science. One of these is the concept of quantum computing, which uses the principles of quantum mechanics to perform calculations that would be impossible for classical computers. Quantum computing has the potential to revolutionize fields such as cryptography, drug discovery, and artificial intelligence.Despite these exciting developments, there is still much that we do not understand about the atom and the behavior of particles at the quantum level. One of the biggest challenges facing scientists today is the development of a theory that can unify quantum mechanics with general relativity, the theory of gravity. This is known as the problem of quantum gravity, and it is one of the most important unsolved problems in physics.In conclusion, the mysteries of the atom and quantum mechanics have captivated scientists and laypeople alike for centuries. From the strange behavior of particles at the quantum level to the potential of quantum computing, this field has led to some of the most groundbreaking discoveries in modern science. However, there is still much that we do not understand, and the search for answers continues. As we continue to explore the mysteries of the atom, we may unlock even more secrets of the universe and our place within it.。

a r Xiv:g r-qc/41127v 13Jan24February 4,20081:40WSPC/Trim Size:9.75in x 6.5in for Proceedings main ON THE FRAME FIXING IN QUANTUM GRA VITY S.MERCURI ICRA —International Center for Relativistic Astrophysics G.MONTANI ICRA —International Center for Relativistic Astrophysics Dipartimento di Fisica,Universit`a di Roma “La Sapienza”,Piazzale Aldo Moro 5,I-00185,Roma,Italy We provide a discussion about the necessity to fix the reference frame before quantizing the gravitational field.Our presentation is based on stressing how the 3+1-slicing of the space time becomes an ambiguous procedure as referred to a quantum 4-metric.In the Wheeler-DeWitt (WDW)approach 3,the quantization of gravity is per-formed in the canonical way,starting from the Arnowitt-Deser-Misner (ADM)ac-tion.The use of the ADM formalism 1is justified by the necessity to obtain Hamil-tonian constraints,but the straightforward quantization of such (3+1)-picture con-tains some relevant ambiguities.In fact,the aim of the WDW approach is to quantize the gravitational field in a particular representation and its outcoming provides essentially information on the quantum dynamics of the 3-metric tensordefined on spatial hypersurfaces.To use the ADM splitting is equivalent to a kind of “gauge fixing”,because it is pre-served only under restricted coordinates transformations (time displacements and 3-diffeomorphisms);the point here is that the “gauge fixing”depends on the field we are quantizing and therefore the canonical approach seems to be an ambiguous procedure.Since in the ADM action the conjugate momenta,πand πi ,respectively to the lapse function N and to the shift vector N i are constrained to vanish,then,on a quantum level,the wave functional of the system does not depend on the lapse function and on the shift vector.The ambiguity relies on regarding as equivalent the fully covariant approach and the “gauge fixed”ADM one,in fact passing from g µνto ADM variables involves a metric dependent procedure,in the sense that we must be able to define a unit time-like normal field n µ(g µνn µn ν=−1),which ensures the space-like nature of h ij (in this respect we recall that h ij≡g µν∂i y µ∂j y νcorresponds to the spatial components of the 4-tensor h µν=g µν+n µn ν).Now the following question arises:how is it possible to speak of a unit time-like normal field1February4,20081:40WSPC/Trim Size:9.75in x6.5in for Proceedings main2for a quantum space-time?Indeed such a notion can be recognized,in quantum regime,at most in the sense of expectation values;therefore assuming the existence of nµbefore quantizing the system dynamics makes the WDW approach physically ill defined.Our point of view is that the canonical quantization of the gravitationalfield can be performed in a(3+1)-picture only if we add,to such a scheme,some information about the existence of the time-like normalfield,as shown in7,5,this result can be achieved by including in the dynamics the kinematical action4,already adopted to quantize“matter”fields on afixed background4.The physical interpretation of such new term either on a classical as well as on a quantum level leads to recognize the existence of a referencefluid and in this sense the analysis of7,5,6converges with the literature on the framefixing problem(see2and references therein).We observe that to include the kinematical action can be regarded as a consequence of fixing in the gravity action the lapse function and the shift vector and,therefore, to choose four independent components of the gravitationalfield,which is just the outcoming of the framefixing.A more physical manner to ensure the existence of a time-like vector consistsoffilling the space time with afluid which plays the role of real reference frame.Here we discuss on a phenomenological ground,the canonical quantization of the gravitationalfield plus a dust referencefluid,outlining some relevant differences between the classical and quantum behavior of this system.The Einstein equations and the conservation law,for the coupled gravity-fluid sys-tem,take the formGµν=χεuµuν,uν∇νuµ=0,∇ν(εuν)=0,(1) where Gµνandχdenotes respectively the Einstein tensor and constant.Remembering a well-known result,it is easy to show that the following relations take place8Gµνuµuν=−H(h ij,p ij)h=χε,Gµνuµhνi=H i(h ij,p ij)h=0.(2)Here h ij(ij=1,2,3)denotes the3-metric of the spatial hypersurfaces orthogo-nal to uµand p ij its conjugate momenta,while H and H i refer respectively to the super-Hamiltonian and to the super-momentum of the gravitationalfield.The above relations hold if we make reasonable assumption that the conjugate momen-tum p ij is not affected by the matter variables(i.e.thefluid term in ADM formalism should not contain the time derivative of the3-metric tensor).Only the Hamilto-nian constraints are relevant for the quantization procedure and,in the comoving frame,when the4-velocity becomes uµ={1,0}(N=1N i=0),we have to retain also the conservation lawε√February4,20081:40WSPC/Trim Size:9.75in x6.5in for Proceedings main3 Thus,when the coordinates system becomes a real physical frame,the Hamiltonianconstraints readH=ω(x i)H i=0.(3) Now,to assign a Cauchy problem for such a system,for which equations(3)play therole of constraints on the Cauchy data,corresponds to provide on a(non-singular)space-like hypersurface,sayΣ(0),the values{h(0)ij,p(0)ij,ε(0)};from these values ω(0)can be calculated by(3).It follows that,by specifying a suitable initial condition,the value ofω(0)can bemade arbitrarily small;from the constraints point of view,a very small value ofω(0)means,if h(0)is not so,that thefluid becomes a test one(beingωa constant ofthe motion);we emphasize that forfinite values ofω,h should not vanish to avoidunphysical diverging energy density of thefluid.The canonical quantization of this system is achieved as soon as we implementthe canonical variables into quantum operators and annihilate the state functionalΨvia the Hamiltonian operator constraints.Thus the quantum dynamics obeysthe following eigenvalue problem:HΨ({hij},ω)=ωΨ({h ij},ω),(4) where{h ij}refers to a whole class of3-geometries,so that the super-momentum constraint holds automatically.We stress how the above result is equivalent to the eigenvalues problem obtainedin7.In the above equation(4),the spatial functionωplays the role of the super-Hamiltonian eigenvalue;in this respect,we observe how its values can no longerbe assigned by the initial values,but they have to be determined via the spectrumof H.We conclude that,in the quantum regime,a real dust referencefluid never approaches a test system.Moreover the presence of non zero eigenvalues for the super-Hamiltonian removesthe so called“frozen formalism”of the WDW equation and confirms the idea thatintroducing a physical unit time like vector provides a consistent and evolutivecanonical quantum gravity dynamics.References1.R.Arnowitt,S.Deser,C.Misner,(1959),Phys.Rev.116,1322.2.J.Bicak,K.Kuchaˇr,(1997),Phys.Rev.D56,4878.3. B.S.DeWitt,(1967),Phys.Rev.160,1113.4.K.Kuchaˇr,Canonical Methods of Quantization,(1981),‘Quantum Gravity2:A Sec-ond Oxford Symposium’,Clarendon Press,Oxford,pp.329-374.5.S.Mercuri,G.Montani,(2003),to appear on Int.Jour.Mod.Phys.D,available ong r-qc/0310077.6.S.Mercuri,G.Montani,(2003),submitted to Class.Quant.Grav.,available on g r-qc/0312077.7.G.Montani,(2002),Nucl.Phys.B634,370.8.T.Thiemann,(2001),available gr-qc/0110034.。

新编研究生英语系列教程博士研究生英语综合教程（第二版/教师用书）北京市研究生英语教学研究会主编陈大明徐汝舟副主编刘宁王焱华许建平编者赵宏凌邹映辉杨凤珍来鲁宁张剑柳君丽曹莉郑辉中国人民大学出版社KEY TO THE EXERCISESUnit One ScienceText 1 Can We Really Understand Matter?I. Vocabulary1. A2. B3. A4. C5. D6. B7. B8. CII. Definition1. A priority2. Momentum3. An implication4. Polarization5. the distance that light travels in a year, about 5.88 trillion miles or 9.46 trillion km.6. a contradictory or absurd statement that expresses a possible truth7. a device that speeds up charged elementary particles or ions to high energiesIII. Mosaic1. The stress: (Omitted)Pronunciation rule: An English word ended with–tion or –sion has its stress on the last syllable but one.2. molecule3. A4. B5. C6. B7. A8. AIV. TranslationA.(Refer to the relevant part of the Chinese translation)B.In September 1995, anti-hydrogen atom—an anti-matter atom—was successfullydeveloped in European Particle Physics Laboratory in Switzerland. After the startling news spread out, scientists in the West who were indulged in the research of anti-matter were greatly excited. While they were attempting to produce and store anti-matter as the energy for spacecraft, they raised a new question: Many of the mysterious nuclear explosions in the recent one hundred years are connected with anti-matter. That is to say, these hard-to-explain explosions are tricks played by anti-mat ter. They are the “destruction”phenomenon caused by the impact between matter and anti-matter.V. GroupingA.Uncertainty:what if, illusory, indescribable, puzzle, speculation, seemingly, in some mysterious wayB.Contrast:more daunting, the hardest of hard sciences, do little to discourage, from afar, close scrutiny, work amazingly wellC. Applications of Quantum mechanics:the momentum of a charging elephant, building improved gyroscopes1. probabilities2. illusory3. discourage4. scrutinyVI. Topics for Discussion and Writing(Omitted)WRITING•STRATEGY•DEFINITIONI. Complete the following definitions with the help of dictionaries.1. To bribe means to influence the behavior or judgment of others (usually in positions ofpower) unfairly or illegally by offering them favors or gifts.2. Gravity is defined as the natural force by which objects are attracted to each other,especially that by which a large mass pulls a smaller one to it.3. The millennium bug refers to the computer glitch that arises from an inability of thesoftware to deal correctly with dates of January 2000 or later.4. Globalization is understood as the development so as to make possible internationalinfluence or operation.II. Write a one-paragraph definition of the following words.1. hypothesisA hypothesis is an idea which is suggested as a possible way of explaining facts,proving an argument, etc. Through experiments, the hypothesis is either accepted as true (possibly with improvements) or cast off.2. scienceScience is defined as the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment.3. superstitionSuperstition refers to a belief which is not based on reason or fact but on old ideas about luck, magic, etc. For example, it is a common superstition that black cats are unlucky.4. pessimismPessimism is a tendency to give more attention to the bad side of a situation or to expect the worst possible result. A person with pessimism is a pessimist who thinks that whatever happens is bad.5. individualismIndividualism is the idea that the rights and freedom of the individual are the most important rights in a society. It has a bad sense in that little attention is paid to the rights of the collective or a good one in that independence is emphasized rather than dependence on others.Text 2 Physics Awaits New Options as Standard Model IdlesI. Vocabulary1. C2. A3. B4. A5. C6. D7. D8. BII. Definition1. A refrain2. A spark3. A jingle4. Symmetry5. develops or studies theories or ideas about a particular subject.6. studies the origin and nature of the universe.7. studies the stars and planets using scientific equipment including telescopes.III. Mosaic1. gravity2. anti-/opposite3. D4. B5. A6. A7. B8.AIV. TranslationA.(Refer to the relevant part of the Chinese translation)B.The Standard Model of particle physics is an unfinished poem. Most of the pieces are there,and even unfinished, it is arguably the most brilliant opus in the literature of physics. With great precision, it describes all known matter – all the subatomic particles such as quarks and leptons –as well as the forces by which those particles interact with one another.These forces are electromagnetism, which describes how charged objects feel each other’s influence: the weak force, which explains how particles can change their identities, and the strong force, which describes how quarks stick together to form protons and other composite particles. But as lovely as the Standard Model’s description is, it is in pieces, and some of those pieces – those that describe gravity – are missing. It is a few shards of beauty that hint at something greater, like a few lines of Sappho on a fragment of papyrus. V. GroupingA.Particle physics:supersymmetry, equation, superpartners, stringB.Strangeness:bizarre, beyond the ken ofC.Antonyms:gravity–antigravity1. novelty2. revelatory3. Symmetry4. gravityVII. Topics for Discussion and Writing(Omitted)WRITING • STRATEGY• EXEMPLIFICATION AN D ILLUSTRATION(Omitted)Text 3 Supporting ScienceI. Vocabulary1. D2. C3. A4. C5. C6. A7. B8. A9. C 10. D 11. B 12. AII. Definition1. A portfolio2. A vista3. Cryptography4. Paleontology5. a business or an undertaking that has recently begun operation6. a group of people having common interests7. a person with senior managerial responsibility in a business organizationIII. Rhetoric1. pouring money into2. column3. unbridled4. twilight5. blossomed intoIV. Mosaic1. phenomenon criterion datum medium(because these words originated from Latin and retain their Latin plural form)2. A3. A4. B5. B6. B7. C8. BV. TranslationA.(Refer to the relevant part of the Chinese translation)B. The five scientists who won the 1996 Nobel Prize point out that the present prosperityand development are based on the fruits of basic scientific research and the negligence of basic scientific research will threaten human development of the 21st century.EU countries noticed that one of their weaknesses is “insufficient investment in research and development.” Korea and Singapore do not hesitate to pour money into research and development. The developed countries in the West have used most of the scientific and technological development resources for the research and development of new and high technology. This has become an obvious trend at present. It is evident from the experiences of various countries that new and high technology can create and form new industries, open up and set up new markets. The innovation of traditional industries with new and high technology is a key method to strengthen the competitive competency of an enterprise.VI. Grouping:A.Negligence of basic research:corporate breakups, cut back on research, ignore it, subject to a protracted dissection and review, second-guessing, dropped dramatically, subjected to a scrutiny, skirling our supportB.Significant examples of basic research:computing, biotechnology, the Internet, number theory, complex analysis, coding theory, cryptography, dinosaur paleontology, genetics research)C.Ways to intensify arguments:moved support for science from a “want to have” squarely into the “need to have”column1. resounding2. second-guessing3. downsized4. subjectedVII. Topics for Discussion and Writing(Omitted)WRITING • STRATEGY • COMPARISON, CONTRAST, AND ANALOGY (Omitted)Text 4 Why Must Scientists Become More Ethically Sensitive Than They Used to Be?I. Vocabulary1. B2. B3. A4. C5. B6. D7. D8. A9. D 10. B 11. B 12. DII. Definition1. A constraint2. Algorithm3. A prerequisite4. Ethics5. an important topic or problem for debate or discussion6. a person’s principles or standards of behaviour; one’s judgement of what is important inlife.7. a formal plan put forward for consideration to carry out a projectIII. Rhetoric1. brushed under the carpet2. smell3. hands and brains4. battle front5. module . . . moduleIV. Mosaic1. /z/ /s/ /s/ /z/ /s//s/ /iz/ /z/ /s/ /z//iz/ /z/ /s/ /z/ /z//z/ /s/ /s/ /z/ /z//s/ after voiceless consonants/z/ after voiced consonants/iz/ after a word ended with –es2. B3. D4. A5. D6. A7. CV. TranslationA.(Refer to the relevant part of the Chinese translation)B. Scientists and medical ethicists advocate the prohibition of human cloning as a way toproduce life. They all agree that human cloning exerts severe threats on human dignity.Social critics point out that cloned children will lack personality and noumenon. G. Annas, professor of health laws in Boston university, points out that “human cloning should be banned because it may fundamentally alter the definition of ourselves.”VI. Grouping:A.The change of attitudes towards ethical consideration:occupy media slots and Sunday supplements, latest battle front, can no longer be swept aside, more sensitiveB.Academic science:a worldwide institutional web, peer review, respect for priority of discovery,comprehensive citation of the literature, meritocratic preferment, smuggle ethical considerations from private life, from politics, from religion, from sheer humanitariansympathyC.Industrial science:intimately involved in the business of daily lifeD.Post-academic science:a succession of “projects”, compound moral risks with financial risks, largely the work ofteams of scientists1. individualistic2. energized3. comprehensive4. heterogeneousVII. Topics for Discussion and Writing(Omitted)WRITING • STRATEGY • CAUSE AND EFFECT(Omitted)Text 5 Beauty, Charm, and Strangeness: Science as MetaphorI. Vocabulary1. B2. A3. C4. B5. C6. B7. A8. B9. A 10. CII. Rhetoric1. pitch2. landscape3. unblinking4. yawn5. wringsIII. Mosaic1.physical poetic political scientific optical atomic2. (Omitted)3. B4. B5. A6. C7. DIV. TranslationA.(Refer to the relevant part of the Chinese translation)B. There are only two forms of human spiritual creation: science and poetry. The formergives us convenience; and the latter gives us comfort. In more common words, the former enables us to have food to eat when we are hungry; and the latter makes us aware that eating is something more than eating, and it is very interesting as well. To have science without poetry, atomic bomb will be detonated; to have poetry without science, poets will starve to death.Scientists should not despise poets; and poets should not remain isolated from scientists.If the two fields conflict each other, human beings would be on the way to doom. In fact, the greatest scientists like Newton, Einstein and Mrs. Currie were all endowed with poetic spirit.I assert that in observing the apple falling to the ground, Newton not only discovered thegravity of the earth, he also wrote a beautiful poem.V. GroupingA.Human reason:guilty of hubris, cramped imagination, commonsense logic, an ignorant manB.Differences between art and science:different in their methods and in their ends, a scientific hypothesis can be proven, new combinations of old materials, transform the ordinary into extraordinary, a practical extension into technology, the sense of an endingC.Similarities between art and science:in their origin, quest to reveal the world1. indistinguishable2. transform3. poetic4. extension5. subdueVI. Topics for Discussion and Writing(Omitted)WRITING • STRATEGY • DIVISION AND CLASSIFICATIONI. Organize the following words into groups.People: physician; driver; boxer; mother; teacherSchools: school; college; institute; kindergarten; universityColors: brown; purple; violet; black; yellowPrepositions: along; toward; upon; without; intoVerbs:listen; read; write; hear; lookII. Complete the following lists.1. College students can be classified according to:A.academic achievementB.attitude toward politics, friendship, etc.C.sexD.heightE.place of originF.value of lifeG.major2. Transportation means can be classified according to:A.speedB.sizeeD.fuelfortF.historyG.water, land, or airIII. Write a paragraph of classification on the books which you like to read.(Omitted)Text 6 Is Science Evil?I. Vocabulary1. C2. A3. D4. B5. B6.A7. C8. C9. D 10. AII. Definition1. Canon2. Validity3. A premise4. Disillusionment5. the process of establishing the truth, accuracy, or correctness of something6. a mode of thinking based on guessing rather than on knowledgeIII. Mosaic1. 1) / / illusion dis-=not -ment=noun ending2) / / science pseudo-=false3) / / conscious -ness=noun ending4) / / question -able=adjective ending5) / / extenuate -ation=noun ending6) / / indict -ment=noun ending7) / / rebut -al=noun ending8) / / perpetrate -ion=noun ending9) / / problem -ic=adjective ending10) / / dissolute -ion=noun ending2. Para. 13: Only when scientific criticism is crippled by making particulars absolute can aclosed view of the world pretend to scientific validity –and then it is a falsevalidity.Para.14: Out of dissatisfaction with all the separate bits of knowledge is born the desire to unite all knowledge.Para. 15: Only superficially do the modern and the ancient atomic theories seem to fit into the same theoretical mold.1) Para. 13: Only + adverbial clause of time + inverted orderPara. 14: Prepositional phrase + inverted orderPara. 15: Only + adverb + inverted order2) Inverted order is used to emphasize.3. C4. B5. A6. CIV. TranslationA.(Refer to the relevant part of the Chinese translation)B. At present there exist two conflicting tendencies towards the development of science andtechnology. The opponents of science hold that the development of modern science has not brought blessings to human beings, instead it has brought human beings to the very edge of disaster and peril. On the other hand, the proponents of scientific and technological progress maintains that the crises facing human beings today—such as environmental pollution, ecological unbalance, natural resource exhaustion—are the natural consequences of the development of science, and the solution to which lies in the further development of science. Both of the above tendencies are reasonable in a sense with their respective one-sided view. If we view the development of modern science and technology from the point of view of our times and with dialectic viewpoints, we can find out that the problem facing modern science and technology is not how to understand the progress of modern science and technology, but how to find out the theoretical basis for the further development of science and technology in order to meet the needs of the times.V. GroupingA.Attitudes toward science:expect to be helped by science and only by science, the superstition of science, the hatred of science, the one great landmark on the road to truthB.Characteristics of science:powerful authority, solve all problems, thoroughly universalC.Scientific knowledge:a concrete totality, cannot supply us with the aims of life, cannot lead usD.Contrast between ancient and modern science:progress into the infinite, making particulars absolute, not as an end in itself but as a tool of inquiry1. corruption2. totality3. inquiry4. superstition5. landmarkVI. Topics for Discussion and Writing(Omitted)WRITING • STRATEGY • GENERALIZATION AND SPECIFICATIONWRITING • STRATEGY • COMBINATION OF WRITING STRATEGIES (Omitted)Unit Two EngineeringText 7 Engineers’ Dream of Practical Star FlightI. Vocabulary1. D2. C3. B4. D5. A6. C7.CII. Definition1. Annihilation2. A skeptic3. A cosmic ray4. Anti-matter5. A workshop6. the curved path in space that is followed by an object going around another larger object7. any one of the systems of millions or billions of stars, together with gas and dust, heldtogether by gravitational attractionIII. Mosaic1. 闭音节, 字母u 发/ / 的音，如A, C and D.2. (Omitted)3. (Omitted)4. C5. C6. B7. A8. BIV. TranslationA.(Refer to the relevant part of the Chinese translation)B. Human beings have long been attempting sending unmanned devices, called interstellarprobes, into the outer space to understand the changes of climates, geological structures and the living beings on the stars and planets out there. A probe is usually sent into the orbit of the earth by “riding” a spacecraft or carrier rockets. After its orbital adjustments are made, the rocket engine is ignited and the probe continues its journey to the orbit of the other star or planet. With the rocket engine broken off, the probe immediately spreads its solar-cell sails and antenna, controlling its posture with sensors. When convinced that it is in the orbit of the targeted star, the probe starts its propeller and flies to the preset destination.V. GroupingA.Astronomical phenomena:interstellar medium, a wind of particles, galaxy, reserves of comets, the Kuiper Belt,orbit, Pluto, the Oort Cloud, the bombardment photonB.Space equipment:interstellar probe, gravitational lens, chemical rocket, thruster, reflective sailC.To explore the universe:scoop, bend, sampleD.Challenges and solutions in interstellar flights:carry its own supply of propellant, matter-antimatter, nuclear power1. gravitational2. propulsion3. probed4. interstellarVI. Topics for Discussion and Writing(Omitted)WRITING • RHETORIC • SIMILE AND METAPHORI. Complete the following similes with the words given, using one word once only.1. as drunk as a ___ bear 11. as cool as ___ cucumber______2. as faithful as a ___ dog_____ 12. as white as ____ snow ________3. as greedy as ____Jew_____ 13. as cunning as a ____ fox__________4. as rich as _____ king_____ 14. to fight like a ____ _lion_________5. as naked as a ___ frog_____ 15. to act like a stupid __ ass_________6. as red as a _ _lobster_ 16. to spend money like __ water_______7. as beautiful as a _ butterfly__ 17. to eat like a _ wolf________8. as busy as a ____ bee______ 18. to sleep like a _____ log ______9. as firm as a ____ rock _____ 19. to swim like a ____ fish________10. as rigid as a ___stone____ 20. to tremble like a _____ _ leaf_________II. Explain the following metaphors.1. Creaking doors hang the longest.creaking door: anything or anybody in a bad condition2. I could hardly put up with his acid comment.acid comment: bitter remark.3. Her eyes were blazing as she stormed at me.blazing: filled with angerstormed: shouted; screamed4. She burnt with love, as straw with fire flames.burnt with love: extremely excited with love5. The talk about raising taxes was a red flag to many voters.a red flag: a danger signal (that might stop the support of many voters)6. The charcoal fire glowed and dimmed rhythmically to the strokes of bellows.glowed and dimmed: became bright and gloomy7. The city is a jungle where nobody is safe after the dark.a jungle: a disorderly place8. To me he is power—he is the primitive, the wild wolf, the striking rattlesnake, thestinging centipede.the primitive, the wild wolf, the striking rattlesnake, and the stinging centipede: the most terrifying creatureText 8 Blinded By The LightI. Vocabulary1. A2. C3. A4. C5. D6. A7. BII. Rhetoric1. riveted2. pack3. pours4. creepsIII. Mosaic1. 开音节发字母读音, 如A, B and C.2. (Omitted)3. (Omitted)4. C5. D6. D7. C8. AIV. TranslationA.(Refer to the relevant part of the Chinese translation)B. The energy released from nuclear fusion is much more than that from nuclear fission, andthe radioactivity given out from fusion is only one hundredth of that from fission. The major fuel used for nuclear fusion is hydrogen and its isotopes, deuterium and tritium, among which deuterium could be directly extracted from sea water. The energy of deuterium contained in one liter of sea water is equal to 300 liters of petroleum. In the ocean there are about 35,000 billion tons of deuterium, which could be used for more than one billion years. Compared to the fission energy, the fusion energy on the earth is nearly limitless.V. GroupingA. Nuclear-fusion:the doughnut-shaped hollow, reactor, the Tokamak Fusion reactor, fusion, generate, consumeB. Verbs related to nuclear-fusion reaction:ignite, release, stickC. Excitement and cool-down:not a few tears, The experiment is an important milestone, but fusion power is still along way . . . , But no one knows for sure whether…, Even then it will take decades of engineering before…1. nuclear fusion2. repel3. blastVI. Topics for Discussion and Writing(Omitted)W RITING • R HETORIC • METONYMY AND SYNECDOCHEI. Study the uses of metonymy in the following sentences and then put them into Chinese.1.The election benched him in the district court.他在这次竞选中当上了地区法官。

Quantum Gravity.Peter C.ChindoveDecember23,2010It would seem to me that paragraphs like this serve one main purpose-to make the reader aware of the reputation of the author and their ability to satisfy the proposition made by the chosen title.Basically,by the time the reader has read this abstract they will have become either more eager or more suspicious.In my estimation,this is a kind of courtship ritual among scientists.I am like a peacock,I spread my feathers and type/whisper’whype’sweet things that entice you into some kind of delusion.Sadly,for you,you have neither heard of me nor are you at this stage frothing at the mouth,chomping at the bit to read on.But,surely you must be mad to stop here.1Courtship Ritual/The Admonishing.The proposition of a theory of everything is such a kind of a delusion.It en-tices and seduces.You,the reader,are interested in reading anything captioned ’Quantum Gravity’if not for anything but to have a good laugh at me,the writer.To your annoyance and utter disappointment,I will show myself ap-proved,insightful and revolutionary.Whilst you stutter and mutter in your grand delusion-or delusions,some read both String Theory and Loop Quan-tum Gravity-of unification.Unification.Sounds like something German,or Soviet-Stalinsky.Now,be-fore I appear utterly scathing;there is need to explain what I mean by delusion.I mean that set of propositions,in physics,which make no physical predictions (weak delusion)or cannot be used to measure experimentally verified and known parameters(strong delusion).In introducing the strong and weak principles of delusion in physics,I have also introduced a measure of the extent to which one may be regarded a crack-pot.We simply,qualitatively measure the position of a theory on the Delusion Index.A crackpot being that person fallen into the charms of a strong delusion.According to our Delusional Index,the history of theoretical physics sug-gests that most revolutions in physics begin with crackpots.Strongly delusional thinkers with no experimental evidence.In fact,it would seem as though the norm is a progression from strongly delusional to weakly delusional.Sadly,and1back again as theorists age and the desire for revolution overcomes the prereq-uisite elbow grease.2The Beginning Of A New Chapter In Physics. You are probably thinking that I am some sort of historian or archivist whichever the fancier.Well,again,I must deflate your epileptic,apoplectic expectations.I am neither,nor am I a crackpot.At least not according to the Delusion Index which I have just made up.Not according to t’Hoot’s own criteria either.We know now that the one most deluded is the unadulterated,living,breath-ing cracked pot.Not that that is such a bad thing either!String Theorists are hoping the LHC will prove to them,more than to anyone else,that over the years they have progressed from strong delusions to weaker ones.The point being that,it is not being a crackpot that is bad.It is remaining one that is bad.Not Michael Jackson bad...but bad bad.3Forward,Onward To A Weak Delusion Or Less.Well,you and I know that what I am about to propose to you is a delusion of some kind.I hope it will be at worst weak.Whereas,you the reader,may hope that it is strong,After all,there must be some entertainment value in what I am doing.Perhaps that is an unfair statement.Perhaps you are a congenial sort of chap(or chap-her)willing to cut me some slack.Even if you have to be patronising to do so.I appreciate your patronage(cheeky-n tongue).I will leave my email address and bank details for you to commiserate and fatten.In that order.4Magnetic InductionWe can the write the expression for magnetic induction dEdx =dBdt.We nowsuggest a similar expression that is equivalent in some limit;d E†dx =d B†dt+d2B†γdx2+d B†γdxwhere we make a notational adjustment B†γ:=B†γ,E†is a conjugate ex-pression for the induced electricfield E,B†is an expression for the magnetic field that is also,in some broad sense,conjugate to a partnerfield with the expression B.We will look at these more closely,for now let it suffice to simply state what they represent.We now write a similar expression but for B.d E dx =d Bdt−d2Bγdx2−d Bγdx2where the nicer looking Bγis notation,Bγ:=Bγ.There is a whole host of ideas that these formulae generate.In fact,it turns out that what we actually have are a pair of Feynman-Kac solvable(FKs)partial differentiable equations(PDE).In particular,we have represented magnetic induction in terms of a special case of these FKs,the Langevin equation.We are not at the moment interested in a generalization to FKs,something which we shall leave for a future project.5Electro-Magnetic DiffusionIn what follows we propose that one of the consequences of our equation is that the magneticfield,likewise the electricfield,can under reasonable conditions behave like heat.We notice that the magneticfield B and its conjugate B†can behave analogously to temperature if we set the condition for the Heat Diffusion equation asd B dt −d2Bγdx2=0...ConditionA(CI)It is worth thinking carefully about this because it suggests that the magnetic field behaves like temperature.That is to say that we can,in this context, discuss a kind of Electromagnetic Diffusion.For example,in superconductors, induction isfinite up to the point where the superconductor expels the magnetic field.This can be compared to a similar scenario with heat.Where temperature flows into a cold thermal object from a hot one until equilibrium is reached.CI is an important means to obtaining the usual expressions for magnetic induction.Another way of thinking about superconductors,in light of these formulae,is that they exhibit all the characteristic behaviour of heat transfer systems.The electromagneticfields involved behave much like the movement of heat from regions of higher temperatures(read:higher concentration of electromagnetic charge)to regions of lower temperature(read:lower numbers/concentration of electromagnetic charge).That is,the electricfield induced into a supercon-ductor reaches a critical point which,analogous to heat,we may regard as the equilibrium stage.In fact,it turns out that for our purposes it is indeed neces-sary to consider this electromagnetic diffusion in order to retrieve the classical expression for magnetic induction.Hence,in our theory,it is completely plau-sible that there exists a kind of electromagnetic diffusion,however,it is not necessary.We can retrieve the classical expression in a more straightforward interpretation of the theory.6The Dirac Quantisation ConditionIn our theory,the Dirac quantisation Condition falls out naturally from the covariant representation of the theory.We write down the covariant expres-sion from which the expression given above is derived.We here consider the conjugate case;3/∂G†µ=/∂B†µ+/∂2B†µγµn+2m+ µ/∂B†µγµThis is the D=d+1dimensional theory of electromagnetism from which we derive the classical theory.We can see that the factor n+2m is precisely the Dirac quantisation condition,that is if we rewrite our theory as;n 2/∂Gµ=n2/∂Bµ+/∂2Bµγµ2+4mn+n2µ/∂Bµγµwhere the last equation is on the non-conjugate side.Now,we define n,m as elements of the set Z of integers.In our case,these integers can take on both positive and negative integer values.Having moved into the covariant representation,it would seem as though we have lost our previous claim,the electromagnetic diffusion part of our the-ory appears to exist only the in1+1dimensional theory.However,I hope to make it explicit(at a later date)that the formulation persists even in this pic-ture.In other words,there exists a D-dimensional theory of the diffusion of electromagnetic charge.7Explicit Form Of The Dirac Quantisation Con-ditionBoth(n,m)arise independently of the specific nature of the magneticfield. Hence,we would like to imagine that we can choose from a set of such theories,clusters of magneticfields which a multiples of n2/∂Gµ.Butfirst,if we specifythe Dirac quantisation condition as;n 2=qeqm¯h cwith qe the electric charge and qmthe magnetic charge.Which is quitetrivial.However,in our theory we realised that there is a special restriction which we state as n+2m=1.The Dirac quantisation condition in a general form,is a contour integral given as;q e q m¯h c =e4πdS iεiµνFµνIt is possible to hypothesize that there exists a non-trivial relationship be-tween what we have so far established and the Dirac quantisation.I am unable to understand any connection between the two at the present moment.It is something worth considering for future work.47.1Clusters Of The Electromagnetic FieldWe can imagine that the effect of n2is to divide up the magneticfield/∂Gµsothat it is in some sense quantized.As we discussed perviously,m and n are integers which may be negative,zero or positive.It is interesting,however,that our theory in which we are discussing magnetic induction gives us a derivation of a kind of quantisation.Moreover,rather than assuming magnetic monopoles, this Dirac-type quantisation is as a consequence of the interaction between the magneticfield and the background geometry.We have not specified a particular type of geometry only the type of non-linear equation.8Previous Analogues/ReferencesThere is a lot of work similar to this that has been done.The point is that it is similar but not quite it.For example,papers on relativistic thermodynamics Also see the online M.I.T lectures on the Classical Model Of A Su-perconductor,in particular the Two Fluid Model.The PHD thesis by M˚arten Sj¨o str¨o m on Hysteresis Modelling Of High Temperature Superconductors is also particularly useful.The lectures by Terry P.Orlando(M.I.T,2003)on superconductivity.There is a lot of literature out there that the reader can use.9Special ReferenceThere is a paper by A.R.Hadjesfandiari,Field Of The Magnetic Monopole in which he discusses the Paul Dirac’s own view on the electromagneticfield strength tensor stated as;Fαβ=∂αAβ−∂βAα+4πGαβWhat we are doing here is in effect to write something similar,without the extra tensor,which we write down schematically as;Fαβ+∂βAα=G†αβOr,a much clearer statement-clearer in terms of showing the not-so-evident stochastic behaviourFαβ=∂2βAαγαn+2m−λβ∂βAαγαwhere Fαβis the usual Maxwell tensor,as are the derivatives the usual terms.However,we introduce new termsλβ,G†αβandγαwhich we will make clear infollowing work.For now,the author resteth deservedly and enjoyeth les joyeux saint´e.Here is my email:**********************.Scant reward for reading this far.5。

universe英文作文Title: Exploring the Vastness of the Universe。

The universe, a boundless expanse of galaxies, stars, planets, and cosmic wonders, has intrigued humanity since time immemorial. It embodies the ultimate frontier of exploration, challenging our understanding and pushing the boundaries of our knowledge. In this essay, we delve into the enigmatic depths of the universe, pondering its mysteries and marvels.At the heart of our fascination with the universe liesa fundamental question: what is our place in the cosmos? Through centuries of scientific inquiry and philosophical contemplation, we have sought to unravel this cosmic enigma. From the ancient civilizations gazing up at the night skyto the modern astronomers peering through powerful telescopes, humanity's quest to comprehend the universe has been relentless.One of the most profound realizations in our exploration of the universe is its sheer vastness. The observable universe spans billions of light-years, containing billions of galaxies, each teeming with countless stars and planets. Within this cosmic tapestry, Earth appears as but a tiny speck, a pale blue dot in the vastness of space. Such enormity both humbles and inspires us, reminding us of the infinite possibilities that lie beyond our terrestrial confines.Yet, despite the staggering scale of the universe, we have barely scratched the surface of its mysteries. The quest to unlock its secrets drives scientific inquiry on a global scale. Through telescopes, space probes, and advanced computational models, astronomers and astrophysicists endeavor to decipher the cosmic code, piecing together the story of our universe's origins and evolution.One of the most tantalizing questions in cosmology is the nature of dark matter and dark energy, which together constitute the vast majority of the universe's mass-energycontent. Despite their pervasive influence on the cosmos, these enigmatic entities remain elusive, their properties and origins shrouded in mystery. Unraveling the secrets of dark matter and dark energy holds the key to understanding the fundamental dynamics of the universe and its ultimate fate.Furthermore, the search for exoplanets—planets orbiting stars beyond our solar system—has captivated the imagination of scientists and the public alike. With each new discovery, we inch closer to answering the age-old question: are we alone in the universe? The prospect of finding Earth-like worlds orbiting distant stars fuels speculation about the existence of extraterrestrial life, igniting dreams of interstellar exploration and contact with alien civilizations.Moreover, the universe serves as a cosmic laboratory, allowing us to probe the laws of physics under extreme conditions. From the intense gravity near black holes to the searing temperatures of distant stars, celestial phenomena provide insights into the fundamental forces andparticles that govern the universe. By studying these cosmic crucibles, physicists strive to unlock the mysteries of quantum gravity, unified theories, and the ultimate nature of reality itself.In addition to its scientific significance, the universe also holds profound cultural and existential implications for humanity. The contemplation of our cosmic origins and destiny fosters a sense of interconnectedness and wonder, transcending cultural and ideological boundaries. Across civilizations and millennia, humanity has sought solace and inspiration in the cosmic symphony, finding solace in the realization that we are but fleeting passengers on a cosmic journey.In conclusion, the universe stands as a testament to the boundless wonders of existence, inviting us to explore its mysteries and contemplate our place within its vast expanse. Through scientific inquiry, philosophical reflection, and artistic expression, humanity endeavors to unlock the secrets of the cosmos and glimpse the infinite possibilities that lie beyond. As we continue our journeyof exploration, may we embrace the awe and wonder of the universe, ever mindful of the profound mysteries that await our discovery.。

a rXiv:h ep-th/94419v15A pr1994Quantum Gravity:A Mathematical Physics Perspective Abhay Ashtekar Center for Gravitational Physics and Geometry Penn State University,University park,PA16802-63001.Introduction The problem of quantum gravity is an old one and over the course of time several distinct lines of thought have evolved.However,for several decades,there was very little communication between the two main communities in this area:particle physicists and gravitation theorists.Indeed,there was a lack of agreement on even what the key problems are.By and large,particle physics approaches focused on perturbative techniques.The space-time metric was split into two parts:g µν=ηµν+Gh µν,ηµνbeing regarded as a flat kinematic piece,h µνbeing assigned the role of the dynamical variable and Newton’s constant G playing the role of the coupling constant.The field h µνwas then quantized on the ηµν-background and perturbative techniques that had been so successful in quantum electrodynamics were applied to the Einstein-Hilbert action.The key problems then were those of handling the infinities.The gravity community,on the other hand,felt that a central lesson of general relativity is that the space-time metric plays a dual role:it is important that one and the same mathematical object determine geometry and encode the physical gravitational field.From this perspective,an ad-hoc split of the metric goes against the very spirit of the theory and must be avoided.If one does not carry out the split,however,a theory of quantum gravity would be simultaneously a theory of quantum geometry and the notion of quantum geometry raises a variety of conceptual difficulties.If there is no background space-time geometry –but only a probability amplitude for various possibilities–how does one do physics?What does causality mean?What is time?What does dynamics mean?Gravity theorists focused on such conceptual issues.To simplify mathematics,they often truncated the theory by imposing various symmetry conditions and thus avoided the field theoretic difficulties.Technically,the emphasis was on geometry rather than functional analysis.It is not that each community was completely unawareof the work of the other (although,by and large,neither had fully absorbed what the other side was saying).Rather,each side had its list of central problems and believed that once these issues were resolved,the remaining ones could be handled without much difficulty.To high energy theorists,the conceptual problems of relativists were perhaps analogous to the issues in foundations of quantum mechanics which they considered to be “unimportant for real physical predictions.”To relativists,the field theoretic difficulties of high energy physicists were technicalities which could be sorted out after the conceptual issues had been resolved.This is of course a simplified picture.My aim is only to provide an impression of the general state of affairs.Over the last decade,however,there has been a certain rapprochement of ideas on quantum gravity.Each side has become increasingly aware of the difficulties that wereemphasized by the other.By and large,high energy theorists now agree that the non-perturbative techniques are critical.They see that the underlying diffeomorphism in-variance should be respected.Even if one introduces a background structure for,e.g., regularization of operators,thefinal result should not make reference to such structures (unless of course they are physically important).Relativists have come to recognize that thefield theoretic divergences have to be faced squarely.There is now a general agreement that although the truncated theories are interesting and provide insights into the concep-tual(and certain mathematical)problems faced by the full theory,they are essentially toy models whose value,in thefinal analysis,is quite limited since they have only afinite number of degrees of freedom.Thus,the sets of goals of the two communities have moved closer.These recognitions do not imply,however,that there is a general consensus on how all these problems are to be resolved.Thus,there are again many approaches.But this diversity in the lines of attack is very healthy.In a problem like quantum gravity,where directly relevant experimental data is scarce,it would be an error if everyone followed the same path.As Feynman(1965)put it:It is very important that we do not all follow the same fashion....It’s necessaryto increase the amount of variety...and the only way to do is to implore you fewguys to take a risk with your lives that you will not be heard of again,and go offin the wild blue yonder to see if you canfigure it out.And quite a few groups have taken the spirit of this advice seriously and“gone offin the yonder tofigure it out.”What is striking is that,in spite of the diversity of their methods,some their results are qualitatively similar.One message that seems to keep coming back is that not only can one not assume aflat Minkowskian geometry at the Planck scale but in fact even the more general notions from Riemannian geometry would fail.The continuum picture itself is likely to break down.The lesson comes from certain computer simulations of4-dimensional Euclidean gravity,(see e.g.Agishtein&Migdal (1992))from string theory(see e.g.Gross&Mende(1988),Amati et al(1990),Aspinwall (1993))and from canonical quantization of4-dimensional general relativity(Ashtekar et al(1992)).The detailed pictures of the micro-structure of space-time that arises in these approaches is quite different at least atfirst sight and it is not clear that these pictures can be reconciled with one another in detail.Nonetheless,there are certain similarities in the results and most of them are obtained by using genuinely non-perturbative techniques.The purpose of this article is to give aflavor of these ideas and techniques to mathemat-ical physicists.I should emphasize that this is not a systematic survey.In particular,I will concentrate just on one approach–non-perturbative,canonical treatment of4-dimensional, Lorentzian general relativity.Even within this approach,there are over350papers and I can not do justice to them in this limited space.(For detailed reviews,see,e.g.,Ashtekar (1991,1992)and Pullin(1993).)Rather,I will just present a few results that may be of interest to this audience,indicating,wherever possible,the degree of precision and rigor of the underlying calculations.However,since the goal of the conference is to look to future,“towards the21st cen-tury,”and since the organizers asked us to try to“inspire rather than merely inform,”I will begin in section2with a few remarks that may perhaps seem provocative to some mathe-matical physicists.In doing so,however,I am following the lead of other speakers and my hope is the same as theirs:these remarks may lead to stimulating exchanges of ideas and perhaps a re-examination of some of the basic premises.In section3,the main difficulties of quantum gravity are outlined from the perspective of mathematical physics.Section4 summarizes some recent developments.While general relativity is normally regarded as a theory of metrics,it can be recast as a dynamical theory of connections(Ashtekar,1987). This shift of emphasis has two important consequences.First,it brings general relativity closer to theories of other interactions and one can draw on the numerous techniques that have been developed to quantize these theories.Second,the shift simplifies the basic equa-tions considerably making them low order polynomials in the basic variables.(They are non-polynomial in the metric variables.)Recently,a number of rigorous results have been obtained to analyze theories of connections,particularly the ones such as general relativity in which there is an underlying diffeomorphism invariance.The main idea here is to use algebraic methods to develop an integration theory on the space A/G of connections mod-ulo gauge transformations and to explicitly construct a measure which is diffeomorphism invariant.These results now provide the foundation for a non-perturbative approach to quantum gravity based on Hamiltonian methods.They may also have other applications in mathematical physics.In section5,this framework is used to show the existence of states in the full,non-perturbative quantum gravity which approximate a classical metric when coarse-grained at scales much larger than the Planck length and which exhibit a specific discrete structure at the Planck scale.If such a state is used in place of Minkowski space-time,the ultra-violet difficulties of Minkowskianfield theories may disappear altogether. This is a concrete illustration of the results in non-perturbative quantum gravity that may have an impact on quantumfield theory.2.The ultraviolet catastrophe:A matter of gravity?As we all know,for over40years,quantumfield theory has been in a somewhat peculiar situation as far as realistic models are considered.On the one hand,perturbative treatments are available for,say,the electro-weak interaction and the results are in excellent agreement with experiments.It is clear therefore that there is something“essentially right”about these theories.On the other hand,their mathematical status has continued to be dubious and it has not been possible to say precisely what is right with them.And this is not because of lack of effort.Already by early sixties,quantumfield theory had become an intellectually coherent subject(recall that PCT spin and statistics and all that was published in1964).A considerable amount of imaginative–and often heroic–effort has gone in to thefield since then.And yet none of the physically realistic quantumfield theories has reached a sound status in4space-time dimensions.I think it is fair to say that the general attitude in the mathematical physics community is that the difficulties are of a mathematical nature.Realistic4-dimensional theories are extremely involved;as Professor Wightman put it at the conference,“handling them with the present techniques is hellishly complicated.”So,the overall feeling seems to be that there is no obstacle of principle to construct a non-Abelian gauge theory such as QCD in 4-dimensions,but new mathematical tools are needed to make the task practicable.One might worry about the fact that in all these theories,one uses Minkowski space as the underlying space-time,thereby ignoring all the Planck scale effects.Could this be a source of the difficulty?The general belief in the community seems to be that this is not the case;no new physical input from the Planck scale is needed to rigorously construct the quantum theory that underlies the standard model of particle physics.(This view was,for example,expressed in Professor Buchholtz’s talk.)Sure,the theory would be an approximation in that one would not be able to trust its predictions below,say10−17cm. But it would be internally consistent and agree with Nature as far as laboratory physics is concerned.Sure,we are idealizing the space-time geometry.But one does this all the time and such idealizations always work:our general experience in physics tells us that, somehow,the phenomena at different scales decouple approximately.Indeed,very little progress could have occurred in absence of this decoupling.After all,when engineers build bridges,they don’t have to worry about the fact that it is quantum mechanics that governs the atoms of the bridge;they just use classical,Newtonian physics.They succeed because there is a factor of1012between the scale of the bridge and the atomic scale.There is a factor of1016between(say)the weak-interaction scale and the Planck length!Surely,one says,the Planck-size effects are unimportant to the problem of constructing a consistent (and therefore in particular,finite)quantum theory underlying the standard model.I would like to argue that this is not necessarily the case.Recall,first,that the key difficulties of quantumfield theory are the ultra-violet divergences.These arise precisely because we allow virtual processes involving arbitrary number of loops,each carrying an integral over arbitrarily large momenta.And it is not our choice to allow or disallow them:we are forced into it by the general principles of quantumfield theory which include Poincar´e invariance.Surely,as the energy involved becomes bigger,the approximation that one can ignore the gravitational effects becomes worse.If the microstructure of space-time is qualitatively different from that given by the continuum picture,the whole procedure isflawed;we shouldn’t–and couldn’t–integrate to arbitrarily high momenta since that is equivalent to integrating to arbitrarily small distances.Let us consider an analogy with atomic physics where we can successfully use non-relativistic quantum mechanics.Suppose for a moment that there was a general requirement that arose from the quantum principles which forced us,in the calculation of,say,the ground state energy of the hydrogen atom, to consider electrons with velocities arbitrarily close to the speed of light.Then,had we ignored special relativity altogether,we would probably have got an inconsistent theory: The hypothetical quantum principle would have forced us to bring special relativity into the treatment.The standard treatment of atomic physics in non-relativistic quantum mechanics is internally consistent because the calculation scheme does not involve steps which violate the basic premise and limitation of non-relativistic quantum mechanics.(It agrees well with experiments because,in addition,these approximations are met in Nature.) Let us return to quantumfield theory.In spite of the fact that we are interested here in processes in which physical energies(and masses of particles)are small compared to the Planck mass,we are forced to allow virtual processes involving arbitrarily high energies and these do probe the Planck-scale structure of the space-time geometry.But we insist on ignoring this structure altogether.That,it may well be,is the physical source of the ultraviolet catastrophe;it may be a matter of gravity.Indeed,there are other instances in physics where mathematical difficulties signalled the need for changing the basic physical premise.Consider for instance the action at a distance models in classical,relativistic physics†.The system of integro-differential equations one obtains is hard to manage mathematically and,if taken seriously,raises questions of predictibility in relativistic physics.The“origin”of these difficulties lies in the physical inadequacy of the basic assumptions.Once we bring in thefield degrees of freedom,these mathematical problems go away.Now,classical physics is described by a system of hyperbolic differential equations and causality is manifest.Another example is the birth of quantum mechanics itself.The mathematical description of the black-body radiation broke down in the framework of classical physics and pointed to the necessity of a radical revision of that framework.There are a number of other examples.Indeed, most radical changes of the conceptual framework are inspired,at least in part,by the fact that the older framework ran into serious mathematical difficulties.This does not of course imply that the same must happen with the ultra-violaet divergences.These are only analogies.And there is no irrefutable evidence that more sophisticated mathematical techniques will not suffice to construct a consistent quantumfield theory for the standard model.However,the examples suggest that we should be open to such a possibility.I will conclude with a related but somewhat different point.Let me again use an analogy.Suppose,for a moment that special relativity had not been discovered.One might have learnt painfully that the predictions of Newtonian mechanics are not quite correct and have to be supplemented by powers of v/c where v is the velocity of the object under consideration.If we had been sufficiently clever,we would have discovered that to compute any physical effect,one can use a perturbation series in the powers of v/c. One could get sophisticated and worry about whether such series actually converge.This is perhaps similar to the present situation with the perturbation theory for the electro-weak interaction.In the hypothetical case of“special relativity”,proving convergence and other mathematical properties of the resulting series would be instructive.Like Lorentz and Poincar´e,one could have even discovered the Lorentz transformations and found all sorts of equations which are“true.”However,without the physical shift of scenario that was provided to us by Einstein–that there is no absolute simultaneity–we would still be missing key insights.In a real sense,we would not really“understand”what the equations were telling us.The situation could be similar with the standard model.Suppose we do succeed in giving a mathematical meaning to the perturbative results.We will have a nice,consistent theory with convergence proofs.But it is possible that we may still be missing some key insights because we ignored the Planck scale physics.Indeed,it is not obvious that all effects of the quantum nature of geometry will be confined to the Planck scale.Let us take special relativity.It is true that most effects are corrections in powers of v/c to the predictions of non-relativistic physics.But now and again,there are also qualitative predictions that have nothing to do with how large the velocity v of the particles involved is.Conversion of mass into enormous amount of energy happens in nuclear processes where all velocities are small.There is a prediction that associated with every particle there is an anti-particle.There is the CPT theorem.These are all qualitative effects completely unrelated to how fast the particles in question are moving.They come about because special relativity shifts the very paradigm within which one operates.The entire mathematical framework of quantum physics changes abruptly.The problems change.The tools change.The concepts change.There is a possibility that quantumfield theory may undergo a similar radical change once the concepts from quantum gravity are brought in.Indeed,we will see in the subsequent sections that quantum gravity does make strong demands on how one should formulate and analyze problems.It insists on diffeomorphism invariance whence there is no background metric or causal structure; it trivializes the Hamiltonian and puts the burden of dynamics on the constraints of the theory;it introduces an essential non-locality through physical observables.The ground rules therefore seem quite different from those we are used to in Minkowskian quantum field theories.Mathematical physicists can raise an immediate objection against the all these pos-sibilities.After all,there do exist well-defined,consistent quantumfield theories in2and 3space-time dimensions.Why don’t the Planck scale problems raise their annoying head there?†It turns out that there is a dramatic change in the properties of the gravitational field starting precisely at4dimensions!It acquires its local degrees of freedom only in4 and higher dimensions.In dimension3or lower,there are no gravity waves and no gravi-tons.Therefore,the ultraviolet problems offield theories are,in a sense,decoupled from the quantum gravitationalfield.Indeed,one can turn the argument around and ask if it is a pure coincidence that the number of dimensions for which the ultra-violet problems of field theories seem so difficult to handle happens to be precisely the one at which gravity comes on its own.Or,is there a lesson lurking here that we have ignored?I want to emphasize again that I do not regard the arguments given in this section as conclusive.It is a viable,logical possibility that a consistent quantumfield theory incorpo-rating the standard model will exist in4-dimensions and will contain all the physics that is relevant to the scale of these interactions.Quantum gravity may have no effect whatsoever on this physics.However,I feel that this“mainstream”viewpoint in mathematical physics is also not watertight.There are differences between the current situation infield theory and previous examples in the history of physics where a clean decoupling occurred between physics at one scale and that at another.And,in the interest of variety,I believe it is important not to ignore altogether the possibility that the ultra-violet catastrophe may,in the end,be a matter of gravity.3.Difficulties of quantum gravityThe importance of the problem of unification of general relativity and quantum theory was recognized as early as1930’s and a great deal of effort has been devoted to it in the last three decades.Yet,we seem to be far from seeing the light at the end of the tunnel. Why is the problem so hard?What are the principal difficulties?Why can we not apply the quantization techniques that have been successful in theories of other interactions?In this section,I will address these questions from the perspective of mathematical physics.The main difficulty,of course,is the lack of experimental data with a direct bearing on quantum gravity.One can argue that this need not be an unsurmountable obstacle.Afterall,one hardly had any experimental data with a direct bearing on general relativity when the theory was invented.Furthermore,the main motivation came from the incompatibility of Newtonian gravity with special relativity.We face a similar situation;we too are driven by what appears to be a fundamental tension between general relativity and quantum theory.However,it is also clear that the situation with discovery of general relativity is an anomaly rather than a rule.Most new physical theories–including quantum mechanics–arose and were continually guided and shaped by experimental input.In quantum gravity, we are trying to make a jump by some twenty orders of magnitude–from a fermi to a Planck length.The hope that there is no dramatically new physics in the intermediate range is probably just that–a hope.The experimental status,however,makes the situation even more puzzling.If there is hardly any experimental data,theorists should have a ball;without these“external, bothersome constraints,”they should be able to churn out a theory a week.Why then do we not have a single theory in spite of all this work?The brief answer,I think,is that it is very difficult to do quantum physics in absence of a background space-time.We have very little experience in constructing physically realistic,diffeomorphism invariant field theories.Indeed,until recently,there were just a handful of examples,obtained by truncating general relativity in various ways.It is only in the last three years or so that a significant number of diffeomorphism invariant models with an infinite number of degrees of freedom has become available,still,however,in low space-time dimensions.As mentioned in the Introduction,one way out of this quandary–tried by the high energy physicists–was to simply break the diffeomorphism invariance to start with and introduce aflat background metric.As is well-known,however,the resulting perturbative quantumfield theory is non-renormalizable.In the high energy community,this was con-sidered a fatalflaw.Atfirst,it was thought that the problem is with the starting point –general relativity.Therefore,attempts were made to modify Einstein’s theory.Perhaps the most notable of these modifications were the higher derivative theories and supergrav-ity.However,these attempts at defining a local quantumfield theory for gravity(with matter)which is consistent order by order in the perturbation expansion failed.Finally, these developments led,in the mid-eighties,to string theory.Since there were several talks on this subject in the conference,I will restrict myself just to a one line summary here: The perturbation series in string theory is believed to befinite order by order(in the string tension)but the series is believed not to be even Borel-summable.As a result,a great deal of effort is being devoted to constructing the theory non-perturbatively.Returning to quantum general relativity,the failure of perturbation theory would, presumably,not upset the mathematical physicists a great deal.After all,they know that in spite of perturbative non-renormalizability,a quantumfield theory can exist non-perturbatively.This point was discussed in some detail in Professor Klauder’s talk and Professor Wightman commented on it in the context of the Gross-Neveu model in3-dimensions.Indeed,in the case of(GN)3,there appears to be no fundamental difference from renormalizable models.In particular,we learnt in this conference that the conjec-ture that such models should be based on distributions which are worse behaved than tempered distributions has been shown to be false.So,at a basic mathematical level, non-renormalizability seems not be a fundamental consideration.Returning to gravity,as I will indicate below,there is some evidence from numerical simulations that quantum general relativity itself may exist non-perturbatively.One might therefore wonder:whyhave the standard methods developed by mathematical physicists not been applied to the problem of quantum gravity?What are the obstacles?Let me therefore consider somenatural strategies that one may be tempted to try and indicate the type of difficulties one encounters.First,one might imagine defining the goal properly by writing down a set of axioms.In Minkowskianfield theories the Wightman and the Haag-Kastler axioms serve this purpose.Can we write down an analogous system for quantum gravity,thereby spelling out the goals in a clean fashion?Problems arise right away because both systems of axioms are rootedin the geometry of Minkowski space and in the associated Poincar´e group.Let me considerthe Wightman system(Streater&Wightman1964)for concreteness.The zeroth axiom asks that the Hilbert space of states carry an unitary representation of the Poincar´e groupand that the4-momentum operator have a spectrum in the future cone;the second axiom states how thefield operators should transform;the third axiom introduces micro-causality,i.e.,the condition thatfield operators should commute at space-like separations;and,the fourth and the last axiom requires asymptotic completeness,i.e.,that the Hilbert spacesH±of asymptotic states be isomorphic with the total Hilbert space.Thus,four of thefive axioms derive their meaning directly from Minkowskian structure.It seems quite difficultto extend the zeroth and the fourth axioms already to quantumfield theory in topologically non-trivial space-times,leave alone to the context in which there is no background metricwhat so ever.And if we just drop these axioms,we are of course left with a frameworkthat is too loose to be useful.The situation is similar with the Osterwalder-Schrader system.One might imagineforegoing the use of specific axioms and just using techniques from Euclidean quantumfield theory to construct a suitable mathematical framework.This is the view recently adapted by some groups using computer simulations.These methods have had a great deal of success in certain exactly soluble2-dimensional models.The techniques involve dynamical triangulations and have been extended to the Einstein theory in4dimensions(see,e.g., Agishtein&Migdal(1992)).Furthermore,there is some numerical evidence that there is a critical point in the2-dimensional parameter space spanned by Newton’s constant and the cosmological constant,suggesting that the continuum limit of the theory may well exist. This is an exciting development and interesting results have now been obtained by several groups.Let us be optimistic and suppose that a well-defined Euclidean quantum theory of gravity can actually be constructed.This would be a major achievement.Unfortunately,it wouldn’t quite solve the problem at hand.The main obstacle is that,as of now,there is no obvious way to pass from the Euclidean to the Lorentzian regime!The standard strategy of performing a Wick-rotation simply does not work.First,we don’t know which time coordinate to Wick-rotate.Second,even if we just choose one and perform the rotation, generically,the resulting metric will not be Lorentzian but complex.The overall situation is the following.Given an analytic Lorentzian metric,one can complexify the manifold and extend the metric analytically.However,the resulting complex manifold need not admit any Euclidean section.(Conversely,we may analytically continue an Euclidean metric and the resulting complex space-time need not have any Lorentzian section.)This。

In our society,there are individuals who,despite facing physical or mental challenges,continue to inspire us with their resilience and determination.These individuals are often referred to as disabled or persons with disabilities,but their stories are anything but limiting.Here is an essay that celebrates the spirit of perseverance and the inspirational journeys of those who defy the odds.Title:The Unyielding Spirit:Inspiration from the DisabledIn the tapestry of human experience,the stories of those who overcome adversity are the threads that weave in the most vibrant colors.The disabled community is a testament to the indomitable human spirit,where individuals not only survive but thrive in the face of challenges that many of us cannot even begin to comprehend.This essay aims to shed light on the inspirational journeys of those who,despite their disabilities,have made significant contributions to society and have become beacons of hope for many.The Power of PerseveranceThe story of Stephen Hawking is a prime example of the power of perseverance. Diagnosed with amyotrophic lateral sclerosis ALS at the age of21,he was given only a few years to live.Yet,Hawking defied all odds,living well into his70s and making groundbreaking contributions to the fields of cosmology and quantum gravity.His work on black holes and the origins of the universe has left an indelible mark on the scientific community.Breaking Barriers in SportsIn the world of sports,we have seen残疾人disabled individuals break barriers and redefine what is possible.Take,for instance,the Paralympic Games,where athletes with disabilities compete at the highest level,showcasing their incredible skills and determination.One such athlete is Oscar Pistorius,a doubleamputee who became the first person to compete in both the Paralympics and the Olympic Games.His achievements serve as a reminder that physical limitations do not define ones ability to excel.Art and Creativity UnleashedThe arts have long been a platform for expressing the human experience,and the disabled community has made significant contributions in this realm.Frida Kahlo,a renowned Mexican painter,continued to create her iconic selfportraits despite suffering from polioand a debilitating accident.Her work is a testament to the power of art as a means of communication and a way to explore the depths of the human condition.Advocacy and AwarenessMany individuals with disabilities have become advocates for change,raising awareness about the challenges they face and working towards a more inclusive society.Helen Keller,who was both deaf and blind,became a leading activist for the disabled, campaigning for equal rights and opportunities.Her life serves as a powerful reminder of the potential that lies within each of us,regardless of our circumstances. ConclusionThe stories of disabled individuals are not tales of tragedy but rather narratives of triumph. They inspire us to look beyond our own limitations and to recognize the potential that exists within each person.As we celebrate the achievements of these inspirational figures, we are reminded that the human spirit is capable of incredible feats when faced with adversity.It is our collective responsibility to ensure that society is inclusive and supportive,allowing everyone to reach their full potential,regardless of their abilities or disabilities.。

A TRUE DEHLER –SPEED MEETS QUALITY_ SINCE 1963, Dehler has been developing sailing yachts that epitomise performance cruising and the power of innovation. This continuous quest for excellence has resulted in yet another leap forward. It is a yacht that carries the founding principles inits very name: the Dehler 38SQ.DETAILS MAKE THE DIFFERENCE_ State of the art performance cruiser. With smartnew developments, the Dehler 38SQ scores in all areas: comfort, quality and performance. For an enhancedsailing experience from the first to the last moment.Additional windows in the coach-roof bring in lots of natural light.Retractable footrests , flush-mounted into the cockpit sole, allow an especially comfortable footing on the heel.The fixed bowsprit with built-in anchor arm puts the tack point for a gennaker or Dehler Freeride even further forward.Choose high-performance squaretop sails to increaseefficiency and reduce heel.The yacht’s sharp, distinctive lines reflect her progressive design and impressive dynamics.STIRRING PERFORMANCE TURBO CHARGED _ Take on the sporting challenge. Give your Dehler 38SQ that extra bit of dynamism and trim the yacht for maximum sailing performance. Select carbon rigging, squaretop membrane sails, extended bowsprit and racing winches.EFFORTLESS CRUISING. LAID-BACK MOOD._Let the sea breeze carry you. The wind and the Dehler 38SQ do all the work for you. Sheets and halyards run directly to the helm, putting everything within reach. Sail handling becomes truly relaxing.LAP OF LUXURY_Once you have reached your anchorage, the Dehler 38SQ will continue to inspire you.The cockpit offers plenty of space to relax – and the perfect atmosphere at any time.The full teak decking is enhanced with an all-round LED light strip for ambient lighting.WATCH EXTERIORGALLERY HERE_ Let your soul take a holiday. The bathing platform with handrail andflush-mounted bathing ladder is the perfect place for it. Celebrate the end of an unforgettable day on the large, comfortable cockpit benches.SUPREME COMFORT.FLAWLESSLY FINISHED._ A cockpit for sailing enthusiasts. Everything is just so: from sports steering wheels with Y-spokes to the flush-mounted traveller. The entire cockpit is on a single level, with free access to the bathing platform. The cockpit coaming flows smoothly into the rounded instrument consoles, which noticeably lengthen the benches.EVERY LINE WORKS IN HARMONY_Magnetic attraction from every angle. Cleaner lines. A sportier look. More striking hull windows - and a bowsprit perfectly integrated into the deckline. The newly designed coachroof now offers an extra saloon window on each side.CLASS TAKES MANY FORMS. HERE ARE THREE.STANDARD MAST HEIGHT ABOVE WL 17.70m / 58'1"MAINSAIL 43.00m 2 / 463sq ft HULL LOA 12.07m / 39'7"Hull length 11.30m / 37'1"LWL 10.40m / 34'1"Beam 3.75m / 12'4DRAUGHT Standard 2.03m / 6'8"Competition 2.24m / 7'5"Shallow 1.60m / 5'3"DISPLACEMENT Standard 7.50t / 16,534lbs Competition 7.00t / 15,432lbs Shallow 7.60t / 16,755lbs BALLAST Standard 2.38t / 5,247lbs Competition 2.05t / 4,508lbs Shallow 2.75t / 6,062lbs ENGINE Diesel 29PS / hp TANKS Fresh water 295l / 77.93gal Fuel tank 160l / 42.27gal HULL DESIGN judel / vrolijk & co CE CERTIFICATE A - 6 / B - 10SPINNAKER competition 101.70m 2 / 1,095sq ft GENNAKER standard 103.70m 2 / 1,116sq ft competition 121.00m 2 / 1,302sq ft DEHLER 82.10m 2 / 884sq ftCOMPETITION CARBON MAST HEIGHT ABOVE WL 17.80m / 58’5“COMPETITION ALU MAST HEIGHT ABOVE WL 17.70m / 58’1“MAINSAIL DOWNLOAD SPECIFICATIONSHERE21AN AMBIENCE SHAPED BY ELEGANCE_ A homage to light. Brightness characterises the noble interior of the Dehler 38SQ. Every surface contributes to the friendly, sunny atmosphere. One design element in particular is lavishly exploited: natural light. Noticeably larger windows in the saloon and cabins make you forget you are below deck.WATCH INTERIOR GALLERYHERE23 22SUPERB FABRICSNATURALLY ILLUMINATED_Coherent interior design. Off-white walls perfectly match any upholsteryfabric. Handrails in black add an effective highlight. The double-leafsaloon table connects both sofas – or, when folded, leaves the way to theforward cabin free.The first-class collectionof upholstery has beencarefully matched to theinterior design.2524Fine furniture woods are used extensively. Each variation features its special, characteristic grain.TIME FOR GREAT CUISINE_ Enjoyment with all the trimmings. A refrigerator with top and side access, a pull-out wine rack in the saloon table: the living area is full of smart details. There is enough storage space for all your crew’s culinary desires.27PURE LUXURY BATHED IN LIGHT_ Exquisite fittings. Larger hull windows bring natural light into the owner’s cabin. Clever indirect lighting adds the finishing touches. The large designer bathroom with separate shower area also owes its charm to this use of light.28CABIN LAYOUT| STANDARD| OPTION DECK LAYOUT| OPTIONLarge master cabinA1B1Bathroom,L-pantry andlong sofa1 large doubleberth cabinand 1 largestorage roomC1Large mastercabin with islanddouble berthA2Bathroom,L-pantry andsofa with fixedchart tableB2C22 large doubleberth cabinsLarge mastercabin with islanddouble berthA2Bathroom,L-pantry andsofa with slidablechart tableB32 large doubleberth cabinsC2Dehleruni doorconceptDehleruni doorconceptDehleruni doorconceptLAYOUT FORYOUR LIFESTYLE_Tailored to your lifestyle.saloon, an island bed for the owners or a second cabinaft for your guests: your way of life decides.DOWNLOAD CABINCONCEPTS HERE321.EXTRA HIGH GUARDRAILfor maximum safety at the helm.2.FULL SANDWICH HULLBalsa wood sandwich core laminated with premium quality vinylester resin –rigid and lightweight.3. COMPOSITE BULKHEADThe shower compartment is designed as a separate bulkhead. It integrates seamlessly into the hull design and is particularly easy to clean.4.SMARTLY PLACED PUMPTo reduce noise, the freshwater pump is installed outside the cabins.5. K EEL STEPPED MASTfor optimal distribution of forces, more stability, better trim.6. B OW THRUSTERfolds out when needed.7. EXTRA STRONG CHAINPLATES Reinforced with ten layers of glass fibre, the chainplates can withstand enormous tensile forces.8. D EHLER CARBON CAGEThe floor structure is reinforced with carbon fibre at key stress points.Torsion in the hull is minimised under high rig loads and in high seas,enab-ling it to better withstand the forces of water and wind.9. H OT-AIR HEATING SYSTEMDiesel-operated, programmable.1. E XTRA HIGH GUARDRAIL2.FULL SANDWICH HULLPOSITE BULKHEADADVANCED ENGINEERING. IN EVERY DETAIL.4.SMARTLY PLACED PUMP5.KEEL STEPPED MAST6.BOW THRUSTERFRESHWATER TANK295 litresBATTERIES90Ah starter, 160Ah service7.EXTRA STRONG CHAINPLATES8.DEHLER CARBON CAGE9.HOT AIR HEATING SYSTEMENGINE 29HP / 21kWFUEL TANK 160 litres3534| Durable, UV protective gray taffeta | Ultralight film (layers 2 & 4)| H igh-tenacity carbon and aramid fibre and filament matrix UNPARALLED MEMBRANE CONSTRUCTION| Durable, UV protective gray taffeta | Ultralight film (layers 2 & 5)| 60° High-tenacity polyester | 0° High-tenacity polyester QUALITY CRAFTSMANSHIP Every panel is precision cut and hand assembled.PROTECTIVE LAYER Taffeta skins layer each panel for added durability and shape retention.LOW-STRETCHCOMPOSITE PANELS Carefully mappedstretch-resistant polyester composite panels for optimal performance.POWERFUL SAILS FOR PASSIONATE SAILORS_ Fueled by the best sailors, sailmakers and designers in the world and comprehensive data and insights from every project they’ve worked on – from superyachts to dinghies – Quantum developed their latest high-tech products for Dehler yachts.The result is a custom sail engineered to achieve the perfect shapes that, simply put, give you confidence through control and ease of use for the best experience on the water time and time again.DEHLER FREERIDE | 62.80M 2UV-PROTECTEDINTEGRATED TORSION CABLE AND ENDLESS is the perfect intermediate size between genoa and gennaker, offering the largest wind range in its class. That means, the FREERIDE speeds up your Dehler, no matter if you are sailing a close reach or broad reach course. Fully optimised for single-handed sailing, it is set out of the specially designed sailbag at deck level. Attaching it to the anchor bracket and gennaker halyard takes two simple clicks. The rolled-up sail can remain set as second forestay in the marina. It is operated with the gennaker sheets using any winch in37dark grey T 7156dark blue RAL 5004palma blue M 5922 (metallic)off white T 9130oyster white T 9128 flag blue T 5153GELCOAT HULL,WATERLINE & COVELINE PAINTED HULL,WATERLINE & COVELINEsunfast red T 3150off white T 91303938EXTERIOR | COVERS & UPHOLSTERY_ Top-quality fabrics defy any weather and shape the appearance of your Dehler with contemporary maritime colors.EXTERIOR |NATURAL TEAK & SYNTHETIC TEAKMAINDROP, SPRAYHOOD, STEERING WHEEL COVER, COCKPIT TABLE COVER OPTIONSdark grey light grey creamblack light grey dark grey dark blue beige weathered look | white caulking weathered look | black caulking teakNATURAL TEAK OPTIONCOCKPIT CUSHIONS OPTIONSscrubbed look | black caulking scrubbed look | grey caulking scrubbed look | white caulking teak look | black caulkingteak look | grey caulking teak look | white caulking SYNTHETIC TEAK OPTIONS41OPTIONINTERIOR | SURFACESFURNITURE WOOD STANDARDmahoganyteakoak dark grey OPTIONSclassic stripesaustralian acacia FLOORBOARDS STANDARDnoce neroOPTIONSWORKTOP GALLEY STANDARDmuscat / silver piping oyster / black piping cliffside / blue piping graphite / gold pipingFINEST MATERIALS TO SUIT YOUR TASTEINTERIOR | UPHOLSTERY Mix and match as you wish. All interior upholstery can be matched with the following piping colours: gold, silver, red, blue and black.PACIFIC OPTIONSADRIATIC LEATHER OPTIONSmud / black piping ivory / blue piping clay / red piping basalt / gold pipingINTERIOR | UPHOLSTERYstone / silver piping silver / red piping ARCTIC OPTIONStaupe / blue piping denim / gold piping BALTIC STANDARDcream / gold piping43High-end sound meets high-class livingYour first impression: brilliance. Even the finest acoustic nuances are brought out. Two pairs of loudspeakers – one in the cockpit, one in the saloon – overwhelm your ears with their outstanding clarity. Simplicity is the second thing you’ll notice. We’ve brought the design and operation of the system back to the essentials, for intuitive control via the chart plotter or the separate control head. And thirdly, you’ll enjoy the thrill of cutting-edge technology. The system is wireless, very compact and almost limitlessly flexible. This is the connectivity of the future.RemoteJL Audio MMR-40Audio Head Unit JL Audio MM 50 BEwith bluetoothControl via B&G Zeus³ 7“ chartplotterSpeakers 2 x 2 JL AudiospeakersJL Entertainment Package:DEHLER CONNECT – BE SMART, BE INTELLIGENT AND UP TO DATEThe MyDehler Safety Cloud enables real-time monitoring of your Dehler: anytime, anywhere, simply via the app. Protect your precious yacht remotely, as if you lived on board. You can organise maintenance and service with unprecedented ease. Thanks to the electronic logbook, a smartphone is all you need to share your sailing experiences with others. In short: this system will add a whole new dimension to your sailing passion.*MyDehler Safety CloudAlertsNotifications for battery, bilge, shore power, anchor, geo fencing and more.Report IssueDirect contact to the dealer.SensorsReal-time monitoring of battery levels and devices.Switch ControlControl of lighting and electrical devices (optional).TripsElectronic logbook with archive and share function for social media platforms.InsuranceExclusive in-app offers and conclusion of all insurances around the boat by Pantaenius.MaintenancePush notifications before due dates for maintenance of all components.Shop & PartsFeature for ordering equipment, supplies and spare parts.Manuals and operating instructions for all units and components on board.* The range of functions depends on the selected equipment. Please ask your dealer.MyDehler Sound Theatre424544CRUISINGCRUISING PACKAGEI Teak on coach roof, cockpit bottom and bathing platform I Bathing platform, manual fold-out with swimming ladder I 2 additional cleats, midship, retractable (1 each side)I A nchor windlass, electrical with automatic fuse, remote control with chain counterI Delta-anchor 16kg, galvanised with 30m galvanised chain I 2 vents for coach roof hatches I M yDehler Safety Cloud with 24 months subscription and device installed on boardI Battery set, capacity: 1x 90Ah + 2x 160Ah AGM I Blind set with flyscreens for hatchesI Blinds for hull windows and side coach roof windows I Wind indicator I FlagpoleI 6 fenders, 4 mooring lines, plaited I Dehler maintenance kitUPGRADE I FLEXITEEK (colour selection)I F lexiteek on coach roof, cockpit bottom, cockpit benches and bathing platformUPGRADE I STAINLESS STEEL ANCHOR WITH CHAIN I D elta-anchor 16kg, stainless steel, with ‘Power Ball’ swivel and 50m stainless steel chain I Upgrade – Battery set Lithium-ionI Battery set, capacity: 1x 90Ah + 3x 105Ah Li-ion batteriesCOMPETITIONCOMPETITION PACKAGE I Cove line – Competition I Rudder – Competition I 2 LEWMAR 45 Race Plus manual halyard winches I 2 LEWMAR 50 Race Plus manual secondary winches I 2 LEWMAR 50 Race Plus manual mainsheet winches I G enoa tracks (Competition), ball bearing sliders, adjustable from cockpitI Jib barber hauler with low-friction ring I Spinlock removable throttleUPGRADE | ELECTRIC HALYARD WINCH I 2 LEWMAR 45 Race halyard winches, port: manual – stb: electric with automatic fuse UPGRADE | COMPETITION KEEL I T -keel, cast iron/lead, (Competition) draught: 2.24mENTERTAINMENTJL ENTERTAINMENT PACKAGE I J L Audio MediaMaster 50 with bluetooth – for saloon and cockpit I 2x 2 JL Audio speakers in saloon and cockpitI JL Audio MMR-40 remote controlGENNAKERGENNAKER PACKAGEI QUANTUM Gennaker (colour selection)I Squeezer for Gennaker I G ennaker/Freeride package incl. halyard, 2 sheets, 2 blocks and padeyes UPGRADE I COMPETITION GENNAKER I C ompetition composite bowsprit with integrated anchor fitting I Q UANTUM Competition Gennaker (colour selection)Market availability and production capacity may vary. Consult the price list or contact your dealer for specific information.REFINE YOUR DEHLER WITH THE BEST_ Top quality equipment packages for your Dehler 38SQ. You will find full details of each component in the price list. Or contact your Dehler dealer.NAVIGATIONB&G NAVIGATION PACKAGE | CRUISING I Instrument pod on helm station stb I 2 B&G Triton² multifunction displays, 1 per helm station, incl. transducer (wind/depth/speed/temperature)I B &G VHF V60 at chart table, incl. wireless remote handset H60I B&G Zeus³ 7“ chartplotter, stb helm station I B &G Autopilot with Triton² control unit and Precision 9 compass I V HF preparation with antenna and splitter for FM and AISUPGRADE I COMPETITION I 2 B&G H5000 multifunction displays, 1 per helm station, incl. transducer(depth/speed/temperature) and wind sensor at vertical carbon mast head unit I B &G Autopilot with H5000 control unit and Precision 9 compass I B &G CPU Hydra computer(only with B&G H5000 instrument)UPGRADE I SECOND CHARTPLOTTER I Instrument pod on helm station psI B&G Zeus³ 7“ chartplotter, ps helm stationhave been delivered by Dehler since 1963 –an experience that results in excellence.932 INNOVATIONSthat made sailing and living on board significantlymore enjoyable were invented by Dehler.65 MODELSin all sizes up to 60 feet were createdby our designers and developers.58 YEARSof yacht building have continuously increasedthe demands we place on ourselves and made usone of the leading sailing boat manufacturers.1 PROMISEfollows from all that we’ve achieved so far:To build our next Dehler 38SQ exactly as you desire it.47Dehler Yachts UKChandlery Building, Hamble Point Marina, Hamble, Southampton SO31 4NBDesign: www.smz.de | Print: Eggers Druckerei & Verlag GmbH | Photos: Nico Krauss, HanseYachts AG. This brochure is not contractual. The yachts depicted partly comprise special equipment not included in the standard scope of supply. Illustrations may not correspond with current versions. Subject to alterations in design and equipment without notice and errors excepted.©2021 Dehler I CIBD38SQ/A/0321。

修正引力模型原理The principle of gravity was first introduced by Sir Isaac Newton in the 17th century. 引力模型是由艾萨克·牛顿爵士在17世纪首次提出的原理。

According to Newton's law of universal gravitation, every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. 根据牛顿的普遍引力定律，宇宙中的每个粒子都会以与其质量乘积成正比、与它们中心的距离平方成反比的力吸引其它粒子。

This law has been used successfully to explain and predict the motion of celestial bodies within the solar system and beyond. 这个定律已经成功地被用来解释和预测太阳系内和太阳系外天体的运动。

However, as our understanding of the universe has deepened, it has become clear that Newton's law of universal gravitation is not the whole story. 然而，随着我们对宇宙的理解不断加深，很明显，牛顿的普遍引力定律并不是全部的故事。

In fact, it is incompatible with certain observations, such as the precession of the perihelion of Mercury and the properties of gravitational waves. 事实上，它与某些观测结果不相容，比如水星近日点的岁巡进动和引力波的性质。

物理专业英语词汇(F) f band f 带f center f 心f center laser f 心激光器f center maser f心微波激射器f layer f 层f value振子强度f/d ratio f/d 比face centered crystal 面心晶体face centered cubic lattice 面心立方晶格face centered cubic structure 面心立方结构face centered lattice 面心点阵factor因子factor group 剩余群facula光斑faddeev equation法捷耶夫方程faddeev popov ghost法捷耶夫波波夫鬼态fading衰退;褪色fahrenheit scale 华氏温标fahrenheit temperature scale 华氏温标fahrenheit thermometer 华氏温度计fall降低fall of potential 电压降fall time下降时间falling sphere viscometer 落球粘度计fallout放射性沉降物false image 鬼象family 族family of asteroids 小行星族family of comets 彗星族fano factor 法诺因子far field pattern 远场图样far infrared远红外区far infrared laser远红外激光器far infrared radiation 远红外卜辐射far infrared rays 远红外卜线far point 远点far ultraviolet 远紫外区far ultraviolet laser 远紫外激光器far ultraviolet radiation 紫外线辐射far ultraviolet rays 远紫夕卜线farad 法faraday法拉第faraday cage法拉第笼faraday cell 法拉第盒faraday constant 法拉第常数faraday cup法拉第笼faraday dark space 法拉第暗区faraday effect 磁致旋光faraday rotation 磁致旋光faraday tube法拉第管faraday,s law法拉第定律farvitron线振质谱仪fast迅速的fast breeder reactor 快增殖堆fast fission快中子裂变fast fission effect快中子裂变效应fast fourier transform快速傅里叶变换fast neutron 快中子fast neutron reactor 快中子堆fast nova快新星fast reactor 快中子堆fatigue 疲劳fatigue limit疲劳极限fatigue strength 疲劳强度fcc structure面心立方结构feedback 反馈feedback amplifier 反馈放大器feedback circuit 反馈电路feedback control 反馈控制feedback factor 反馈系数feedback ratio 反馈比feeder馈电线femto 飞femtometer 费密femtosecond 飞秒femtosecond region 飞秒区域fermat,s principle 费马原理fermi费密fermi acceleration 费密加速fermi age费密年龄fermi dirac statistics 费密统计法fermi distribution 费密分布fermi energy 费密能fermi gas费密气体fermi glass费密玻璃fermi hole费密空穴fermi interaction 费密相互酌fermi level费密能级fermi liquid费密液体fermi particle 费密子fermi pasta ulam problem费密巴斯德乌拉姆问题fermi resonance 费密共振fermi selection rule 费密选择定则fermi statistics费密统计法fermi surface 费密面fermi temperature 费密温度fermi transition 费密跃迁fermi's golden rule费密黄金定律fermiology费密面学fermion费密子fermionic dark matter 费密子暗物质fermium 镄ferrielectricity 亚电性ferrimagnetic resonance 亚铁磁共振ferrimagnetism铁氧体磁性ferrite铁氧体ferrite magnetostrictive vibrator 铁氧体磁致伸缩振子ferro resonance 铁磁共振ferroelastic phase transition 铁弹性相变ferroelasticity 铁弹性ferroelectric 铁电的ferroelectric domain 铁电畴ferroelectric mode 铁电模ferroelectric phase transition 铁电相变ferroelectric semiconductor 铁电半导体ferroelectric substance 铁电性材料ferroelectricity 铁电性ferrofluid 铁磁铃ferromagnet 铁磁体ferromagnetic 铁磁的ferromagnetic dielectrics 铁磁电介质ferromagnetic fluid 铁磁铃ferromagnetic material 铁磁性材料ferromagnetic resonance 铁磁共振ferromagnetic substance 铁磁性材料ferromagnetic superconductor 铁磁超导体ferromagnetic thin film 铁磁薄膜ferromagnetism 铁磁性feynman diagram 费因曼图feynman path integral费因曼的路径积分feynman spectrum 费因曼谱ffag synchrotron固定场交变梯度回旋加速器fiber纤维fiber bundle 纤维丛fiber electrometer 悬丝静电计fiber laser纤维激光器fiber optics纤维光学fiber structure 纤维结构fibonacci semiconductor superlattice 菲博纳奇半导体超晶格fibril小纤维fibril structure 纤维结构fick,s law斐克定律fictitious spin quantum number 假想自旋量子数fictitious year 假年field场;体field adsorption 场吸附field current 励磁电流field density 场密度field desorption 场致退吸field distortion 场畸变field distribution 场的分布field effect transistor 场效应晶体管field electron emission 场致电子发射field emission 场致发射field emission microscope场致发射显微镜；自动电子显微镜field emitted electron 场致发射电子field equation 场方程field intensity 场强field ion microscope场致离子显微镜field lens 场镜field magnet 场磁铁field of forces 力场field of gravity 重力场field of view 视场field of vision 视场field operator 场算符field particle 场粒子field quantum 场量子field stop 场栏field strength 场强field structure 场结构field theory 场论fifth force第五种力fifth fundamental force 第五种基本力figure图形figure of merit 优值figure of noise 噪声指数file文件filled band 满带filled level满带能级filled shell 满壳层film软片film badge胶片剂量计film boiling膜态沸腾film dosimeter胶片剂量计film type condensation 膜状凝结filter滤器滤光器滤波器filtration 过滤final product最终产物final state interaction 终态相互酌final vacuum极限真空finder取景器finding telescope 寻星镜fine particle 微粒子fine structure 精细结构fine structure constant 精细结构常数fine structure splitting 精细结构劈裂finesse 锐度finite difference method 差分法finite element method 有限元法finite group 有限群finite universe 有限宇宙fireball 火球fireball model 火球模型first harmonics 基波first integral 初积分first law of thermodynamics 热力学第一定律first order phase transition 一级相转变first point of aries 春分点first quarter 上弦first resonance 一次共振first sound第一次声波fish finder鱼群探测器fissible可裂变的fissile可裂变的fissile nucleus可分裂的核fissility可分变性fission 分裂fission chain reaction 裂变链式反应fission chamber 裂变室fission counter 裂变计数器fission energy 裂变能量fission event裂变事件fission fragment 裂变碎片fission neutron 裂变中子fission yield裂变产额fissionable可裂变的fissionable nucleus 可裂变核 fissioning isomer 裂变同质异能素 fit适合five minute oscillations 五分钟振动 fixation 定影fixed capacitor固定电容器fixed point 定点fixed resistor固定电阻器fixed star 恒星fixing定影fixing solution 定影液fizeau fringe 菲佐条纹fizeau interferometer 菲佐干涉仪flame火焰flame photometer 火焰光度计flame photometry火焰光度法flame spectrum 火焰光谱flare太阳耀斑flare star 耀星flash闪光flash of light 闪光flash photolysis 闪烁光解flash spectrum 闪光光谱flat surface 平面flatness problem平坦性问题flattening 扁率flavor 味flexibility 挠性flexible polymer挠性聚合体flexural rigidity 弯曲刚度flexural strength 抗挠强度flexure 挠曲flexure vibration 弯曲振动flicker 闪烁flicker effect 闪烁效应flicker noise闪变噪声flicker photometer 闪烁光度计flight path飞越距离flight time飞越时间flint glass火石玻璃flip flop触发器flip flop circuit双稳态触发电路floating body 浮体floating point representation 浮点表示floating zone melting method 浮区熔炼法flocculation 凝聚flood and ebb 潮汐flooding 溢流floppy disk 软磁盘flow 流flow birefringence 怜双折射flow counter柳式计数管flow dichroism 怜二色性flow equation 怜方程flow parameter 怜参数flow pattern 镣flow proportional counter 怜正比计数器flow rate 量flow visualization 辽视化flowmeter 量计fluctuating force 涨落力fluctuation 起伏fluctuation dissipation theorem 涨落耗散定理fluctuon起伏量子fluent变数fluid 铃fluid dynamics 铃动力学fluid elasticity 水弹性fluid model 铃模型fluidal 铃的fluidic 铃的fluidity 怜性fluorescence 荧光fluorescence center 荧光中心fluorescence dosimeter 荧光剂量计fluorescence spectrophotometer 荧光分光光度计fluorescence spectrum 荧光光谱fluorescence yield 荧光产额fluorescent 萤光的fluorescent indicator tube 荧光指示管fluorescent lamp 荧光灯fluorescent material 萤光材料fluorescent radiation 特狰射fluorescent scattering 荧光散射fluorescent screen 荧光屏fluorescent x rays 荧光 x 射线fluorimeter 荧光计fluorine 氟fluorite structure 萤石型结构fluorography荧光照相法fluorometer 荧光计fluorometric analysis 荧光分析fluoroscope 荧光镜fluoroscopy荧光检查法fluorspar structure 萤石型结构flux通量flux creep磁通量蠕变flux density通量密度flux flow磁通量流flux jump磁通量跃变flux method 熔剂法flux motion 磁通量运动flux of energy 能通量flux of light 光通量flux of radiation 辐射通量flux pinning 通量锁住flux pump 通量泵flux quantization 磁通量量子化flux quantum磁通量子fluxmeter磁通计fluxoid磁通量子fluxon磁通量子fly苍蝇座flying spot electron microscope 扫描电子显微镜fm receiver档接受器focal distance 焦星巨focal length 焦星巨focal line 焦线focal plane 焦面focal point 焦点focal power 光焦度focal surface 焦曲面fock representation 福克表示fock space福克空间focometer焦距计focon聚焦锥focus焦点focused ion beam聚焦离子束focusing 倒focusing camera 倒照相机focusing coil聚焦线圈focusing cone 聚焦锥focusing lens 聚焦透镜focusing quadrupole magnet 聚焦四极磁铁focuson聚焦子foil 箔fokker planck equation 福克普朗克方程follow up control 随动控制foot pound second system 英尺磅秒单位制forbidden禁戒的forbidden band 禁带forbidden decay 禁戒衰变forbidden line 禁线forbidden lines in astrophysics 天体物理学中的禁线forbidden reflection 禁戒反射forbidden transition 禁戒跃迁forbiddenness 禁戒force 力force function 力函数force of attraction 弓|力force of gravity 重力force of inertia 惯性力force of repulsion 斥力force of rolling friction 滚动摩擦力force of sliding friction 滑动摩擦力force polygon力的多边形force triangle力的三角形forced circulation 强制循环forced convection 强制对流forced emission 强迫发射forced oscillations 受迫振荡forced vibration 受迫振荡forced vortex 强迫涡流fore vacuum 前级真空forecast 预报forecast of solar activity 太阳活动预告foreign atom 杂质原子forepump预备真空泵fork mounting 叉式装置form drag 型阻form factor形状因子formant共振峰formation of order 秩序形成formula 公式formulation 公式化fornax天炉座fortran程序语言forward scattering 前方散射foucault currents 涡电流foucault knife edge test 傅科刀口检验foucault's pendulum 傅科摆fountain effect 喷水效应four current 四维电流four dimensional space 四维空间four dimensional structure of the universe 宇宙四维结构four dimensionality 四维性four factor formula 四因子公式four force四维力four momentum 四维动量four potential 四维势four terminal network 四端网络four vector 四维矢four velocity四维速度four wave mixing 四波混合fourier component 谐波分量fourier integral傅里叶积分fourier number 傅里叶数fourier series傅里叶级数fourier spectroscopy 傅里叶光谱学fourier transform hologram傅里叶变换全息图fourier transform spectrometer 傅里叶光谱仪fourier transformation 傅里叶变换fourth sound第四次声波fractal 分形fractal dimension 分形维数fractional charge 分数电荷fractional crystallization 分级结晶fractional quantum hall effect 分数量子霍尔效应fracton分形子fracture 破裂fracture mechanics 断裂力学fragility 脆性frame antenna环形天线frame of reference 参考系francium 钫franck condon principle 富兰克康登原理franck hertz,s experiment 富兰克赫兹实验 frank read source弗朗克里德源franklin富兰克林fraunhofer diffraction 夫琅和费衍射fraunhofer hologram夫琅和费全息图fraunhofer line夫琅和费谱线fre量子free自由的free charge自由电荷free convection自由对流自然对流free electron自由电子free electron laser自由电子激光器free energy 自由能free energy of activation 激活的自由能free field自由场free free transition 自由自由跃迁free group自由群free gyroscope自由陀螺仪free motion自由运动free neutron自由中子free oscillation 自由振动free path自由程free pendulum 自由摆free rotation自由旋转free space自由空间free state自由态free surface 自由面free system 自由系free vibration 自由振动free volume自由体积free volume theory自由体积理论freedom 自由freezing 凝固freezing mixture 冷冻剂freezing point 凝固点frenkel defect夫伦克尔缺陷frenkel exciton 夫伦克尔激子frequency 频率frequency analysis 频率分析frequency band 频带frequency characteristic 频率特性frequency converter 变频器frequency converter tube 变频管frequency counter 频率计数器frequency divider 分频器frequency domain 频域frequency factor 频率因子frequency meter 频率计frequency modulation 档frequency multiplier倍频器频率倍增器frequency range 频率范围frequency response 频率响应frequency response method 频率特性法frequency shift 移频frequency spectrum 频谱frequency stability 频率稳定度frequency stabilized laser 稳频激光器frequency transfer function 频率传递函数fresnel diffraction 菲涅耳衍射fresnel half period zones 菲涅耳半周期带fresnel hologram菲涅耳全息图fresnel lens菲涅耳透镜fresnel prism 菲涅耳棱镜fresnel rhomb菲涅耳斜方系fresnel zone 菲涅耳带fresnel,s biprism菲涅耳双棱镜fresnel's dragging coefficient 菲涅耳曳引系数fresnel,s zone plate 菲涅耳波带片friction 摩擦friction coefficient 摩擦系数friction cone 摩擦锥friction layer 摩擦层friction loss摩擦损失friction of fluid lubrication 液体润滑摩擦frictional drag 摩擦阻力frictional electricity 摩擦电frictional force 摩擦力frictional oscillation 摩擦振动frictional resistance 摩擦阻力 friedel sum rule弗里德尔的求和定则 friedmann equation 弗里德曼方程friedmann universe弗里德曼宇宙frigorimeter 深冷温度计fringes with white light 白光干涉条纹froude number 弗劳德数frozen in magnetic field 冻结磁场frustrated total internal reflection 衰减全内反射frustration 抑止ft value ft 值fuel assembly燃料组件fuel cell燃料电池fuel cycle燃料循环fuel regeneration 燃料再生fuel reprocessing 燃料再生fuel rod燃料元件棒fugacity挥发性fulcrum 支点full load 满载full moon 望月full wave rectification 全波整流full width at half maximum 半宽度fullerene球壳状碳分子function 函数functional 泛函functional analysis 泛函分析functional ceramics 机能陶瓷functional derivative 泛函微分fundamental absorption 基本吸收fundamental catalog 基本星表fundamental constants 基本常数fundamental doublet 基本双重线fundamental frequency 基频率fundamental interaction 基本相互酌fundamental law 基本定律fundamental magnitude 基本量fundamental mode 关Bfundamental particle 基础粒子fundamental research 基础研究fundamental series 伯格曼系fundamental star 基本星fundamental theorem 基本定理fundamental tone 基音fundamental unit 基本单位furnace 炉furry,s theorem 弗里定理fuse熔断器保险丝fused quartz 熔融石英fusible alloy易熔合金fusing point 熔点fusion熔化fusion fission hybrid reactor核聚变裂变混合反应堆fusion point 熔点fusion reaction 聚变反应fusion reactor 热核堆fusion temperature 聚变温度。