Inflation, holography, and the choice of vacuum in de Sitter space
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《复辛空间中完全Lagrangian子空间以及耗散子空间的构造》篇一复辛空间中完全Lagrangian子空间及耗散子空间的构造一、引言在复数和辛空间的理论研究中,完全Lagrangian子空间及耗散子空间是两个重要的概念。
Lagrangian子空间和辛空间中的对称性及稳定性紧密相关,而耗散子空间则与能量的耗散和系统的稳定性有密切联系。
本文将探讨复辛空间中完全Lagrangian子空间的构造,以及与耗散子空间的关系及其构造方法。
二、复辛空间及Lagrangian子空间的基本概念复辛空间是一种特殊的线性空间,其上的运算满足一定的辛结构,即存在一个双线性形式,称为辛式。
而Lagrangian子空间则是这种双线性形式下具有特殊性质的一个子空间。
它是一类在复辛空间中同时与自己正交且与其他部分成辛的特殊结构。
其重要特征是在给定的复辛空间中能提供良好的对称性和稳定性。
三、完全Lagrangian子空间的构造完全Lagrangian子空间的构造主要依赖于复辛空间的性质和Lagrangian子空间的基本性质。
首先,我们需要选择一组合适的基底,使得在给定的复辛空间中,这组基底构成的子空间满足Lagrangian条件。
然后,通过线性变换和矩阵运算,我们能够逐步调整和优化这个子空间的构造,直到满足完全Lagrangian的要求。
此外,利用Lagrangian的辛正交特性,我们可以在特定的投影映射下进行Lagrangian的精确重构,为进一步的稳定性和控制性能研究奠定基础。
四、耗散子空间的引入及其与Lagrangian子空间的关系耗散子空间是一个描述系统能量耗散特性的重要概念。
在复辛空间中,耗散子空间的存在使得系统具有更好的稳定性和控制性能。
由于耗散过程与系统的Lagrangian结构紧密相关,因此我们可以通过调整Lagrangian子空间的构造来影响耗散子空间的特性。
例如,我们可以通过设计合适的投影映射和线性变换来控制Lagrangian子空间的分布和形态,从而实现对耗散子空间的调整和控制。
《复辛空间中完全Lagrangian子空间以及耗散子空间的构造》篇一摘要本文探讨了复辛空间中完全Lagrangian子空间及耗散子空间的构造。
我们首先给出了相关概念的界定和预备知识,随后探讨了这两种子空间的具体构造方法和性质。
重点强调了复辛结构对这两种子空间构造的影响以及其在复几何、复分析和量子力学等领域的应用。
一、引言复辛空间是复数域上的一个特殊空间结构,具有独特的数学性质和物理应用。
其中,Lagrangian子空间和耗散子空间是两种重要的子空间类型。
它们在复几何、复分析、量子力学以及信号处理等领域有着广泛的应用。
本文旨在探讨复辛空间中完全Lagrangian子空间及耗散子空间的构造方法及其性质。
二、预备知识2.1 复辛空间基本概念复辛空间是指一个复数域上的向量空间,具有特殊的线性结构和内积关系。
其中,内积不仅取决于两个向量的模长,还与它们的相对相位有关。
2.2 Lagrangian子空间定义Lagrangian子空间是指一个向量子空间,其内任意两个向量的内积都为零。
这种子空间在复辛空间中具有特殊的性质和重要性。
2.3 耗散子空间定义耗散子空间是指一个向量子空间,其内任意向量与另一个固定向量的内积都为零。
这种子空间在描述物理系统的耗散现象时具有重要作用。
三、完全Lagrangian子空间的构造3.1 构造方法完全Lagrangian子空间的构造通常基于复辛空间的基底选择和特定的线性变换。
通过选择合适的基底,可以构造出满足Lagrangian条件的子空间。
3.2 性质与定理完全Lagrangian子空间具有特殊的性质,如内积的封闭性、正交性等。
这些性质可以通过数学定理进行证明,并应用于复几何和复分析等领域。
四、耗散子空间的构造4.1 构造方法耗散子空间的构造通常依赖于特定的向量选择和内积关系。
通过选择与固定向量正交的向量集,可以构造出耗散子空间。
4.2 性质与定理耗散子空间在描述物理系统的耗散现象时具有重要作用。
庞加莱猜想-前言Wir m\"ussen wissen! Wir werden wissen!(我们必须知道!我们必将知道!)—— David Hilbert两年前科学版举行过一次版聚,我报告了低维拓扑里面的一些问题和进展,其中有一半篇幅是关于Poincar\'e 猜想。
版聚后,flyleaf 要求大家回去后把自己所讲的内容发在版上。
当时我甚至已经开始写了一两段,但后来又搁置了。
主要是因为自己对于低维拓扑还是一个门外汉,写出来的东西难免有疏漏之处,不敢妄下笔。
两年过去,我对低维拓扑这门学科的了解比原先多了,说话的底气也就比原先足了。
另外,由于Clay 研究所的百万巨赏,近年来Poincar\'e 猜想频频在媒体上曝光;而且Perelman 最近的工作使数学家们有理由相信我们已经充分接近于这一猜想的最后解决。
所以大概会有很多人对Poincar\'e 猜想的来龙去脉感兴趣,我也好借机一偿两年来的宿愿。
现代科学的高速发展使各学科之间的鸿沟加大,不同学科之间难以互相理解,所以非数学专业的读者在阅读本文时可能会遇到一些困难。
但限于篇幅和文章的形式,我也不可能对很多东西详细解释。
一些最基本的拓扑概念如“流形”,我将在本文的附录中解释。
还有一些“同调群”、“基本群”之类的名词,读者见到时大可不去理会它们的确切含义。
我将尽量避免使用这一类的专业术语。
作者并非拓扑方面的专家,对下面要说的很多内容都是道听途说,只知其然而不知其所以然;作者更不善于写作,写出来的东东总会枯燥无味,难登大雅之堂。
凡此种种,还请读者诸君海涵。
问题的由来Consid\'erons maintenant une vari\'et\'e [ferm\'ee] $V$ \`a trois dimensions ... Est-il possible que le groupe fondamental de $V$ ser\'eduise \`a la substitution identique, et que pourtant $V$ ne soit pas simplement connexe?—— Henri Poincar\'e在拓扑学家的眼里,篮球、排球和乒乓球并没有什么不同,它们都同胚于三维空间中的球面S^2. (我们把n+1维欧氏空间中到原点距离为1的点的集合记作S^n,称为n维球面(sphere)。
第60卷第1-2期2021年1月Vol.60No.1-2Jan.2021中山大学学报(自然科学版)ACTA SCIENTIARUM NATURALIUM UNIVERSITATIS SUNYATSENI天琴对宇宙膨胀的探测能力研究*李霄栋1,肖小圆1,王凌风2,赵泽伟2,张鑫21.中山大学物理与天文学院,广东珠海5190822.东北大学理学院,辽宁沈阳110004摘要:经过近几十年的发展,宇宙学的研究已经进入精确宇宙学时代。
根据Planck测量结果和ΛCDM模型,只需要6个参数就可以在统计意义上重现出与观测数据基本符合的宇宙演化历史。
但是实际上,当前宇宙学领域中还存在许多未解决的重要科学问题,而且不同的观测数据在基于基本ΛCDM模型进行宇宙学参数推断时会出现一些不一致性。
这些问题的回答都需要对基本ΛCDM模型进行扩展,并对额外引入的参数进行精确的测量。
目前主流的宇宙学探针主要是针对宇宙的膨胀历史和宇宙的结构增长进行观测的光学(以及近红外)项目,因此它们可能存在着相似的系统误差。
发展全新的非光学观测手段的宇宙学探针对于宇宙学未来的研究至关重要。
因为引力波振幅携带了绝对光度距离的信息,所以能够帮助建立真正的距离——红移关系,用以研究宇宙的膨胀历史。
这种引力波观测被称为“标准汽笛”。
宇宙学研究是天琴、LISA等空间引力波探测器的重要研究目标之一。
这些探测器预计都可以在未来观测到大量的引力波事件,为宇宙学研究(特别是高红移宇宙)提供珍贵的观测数据。
本文参考相关的文献,介绍了天琴标准汽笛数据限制宇宙学参数能力的情况。
考虑了popⅢ、Q3nod和Q3d三种大质量黑洞双星模型,结果表明,对于不同的大质量黑洞双星模型,天琴项目对宇宙学参数的限制能力各有不同,其中Q3nod模型下的限制能力最强。
天琴的标准汽笛探测有助于打破其他观测手段所导致的宇宙学参数简并,从而有效地提升宇宙学参数的测量精度。
我们有理由相信,未来的引力波观测与光学和射电观测相结合将把宇宙膨胀历史的探索推进至一个全新的层面,为探测哈勃常数大小、揭示暗能量的本质属性提供帮助。
高三戏剧物理英语阅读理解25题1<背景文章>Drama Physics, an interdisciplinary field that combines elements of drama and physics, has a rather interesting origin and development. It emerged from the realization that the principles of physics could be used to enhance the understanding and creation of dramatic works.The origin of Drama Physics can be traced back to the early 20th century when some avant - garde artists and physicists started to explore the relationship between the physical world and the world of drama. At that time, with the rapid development of physics, concepts such as relativity and quantum mechanics were shaking the foundation of people's understanding of the physical world. These new concepts inspired artists to think about how to apply them to the field of drama.During its development, Drama Physics gradually formed its main theories. One of the important theories is the "space - time theory in drama". According to this theory, just as in physics, the space - time in drama is not simply a static background, but can be distorted and reshaped according to the needs of the plot and the psychological state of the characters. Another theory is the "energy transfer theory in drama", which believes that the emotional and plot development in drama is similar to the transfer ofenergy in physics.There are also many famous researchers in the field of Drama Physics. For example, Dr. John Smith, a physicist - turned - drama theorist, made great contributions to the combination of the two fields. He used his in - depth knowledge of physics to analyze classic dramas and put forward many innovative concepts.In modern science, Drama Physics has a wide range of applications. In the field of theater performance, it helps directors and actors better understand the physical environment and character relationships in the play, so as to create more vivid and profound performances. In the field of drama education, it provides students with a new perspective to understand drama, making the learning process more interesting and in - depth.1. What was the main inspiration for the origin of Drama Physics?A. The development of modern art forms.B. The new concepts in physics in the early 20th century.C. The demand for new drama theories in the market.D. The emergence of new performance techniques.答案:B。
中国科学院3月博士硕士入学考试试题PARTⅡVOCABULARY (15 minutes, 10 points, 0.5 point each)Directions: Choose the word or word below each sentence that best complete the statement, and mark the corresponding letter of your choice with a single bar across the square brackets on your Machinescoring Answer Sheet.21. A knowledge of history us to deal with the vast range of problems confronting the contemporary world.A. equipsB. providesC.offersD. satisfies22. In assessing the impact of the loss of a parent through death and divorce it was the distortion of family relationships not the of the bond with the parent in divorce that was vital.A. dispositionB. distinctionC.distributionD. disruption23. Finally, let's a critical issue in any honest exploration of our attitudes towards old people, namely the value which our society ascribes to them.A. stick toB. turn toC.lead toD. take to24. Smuggling is a____________activity which might bring destruction to our economy; therefore, it must be banned.A. pertinentB. fruitfulC.detrimentalD. casual25. The manufacturer was forced to return the money to the consumers under____________of law.A. guidelineB. definitionC.constraintD. idetity26. The food was divided____________according to the age and size of the child.A. equallyB. individuallyC.sufficientlyD. proportionally27. Horseback riding____________both the skill of handing a horse and the mastery of diverse riding styles.A. embracesB. encouragesC.exaggeratesD. elaborate28. Plastic bags are useful for holding many kinds of food,____________their cleanness, toughness, and low cost.A. by virtue ofB. in addition toC.for the sake ofD. as opposed to29. He cannot____________the fact that he was late again for the conference at the university yesterday.A. contribute toB. account forC.identify withD. leave out30. Please do not be____________by his had manners since he is merely trying to attract attention.A. disgustedB. embarrassedC.irritatedD. shocked31. For nearly 50 years, Spock has been a____________author writing 13 books including an autobiography and numerous magazine articles.A. prevalentB. stand up toC.prospectiveD. prolific32. Workers in this country are getting higher wages while turning out poor products that do not____________the test of international competition.A. keep up withB. stand up toply withD. attend to33. The business was forced to close down for a period but was____________revived.A. successivelyB. subsequentlyC.predominantlyD. preliminarily34. The book might well have____________had it been less expensive.A. worked outB. gone throughC.caught onD. fitted in35. We had been taken over by another firm, and a management____________was under way.A. cleanupB. setupC.breakoutD. takeout36. The poor quality of the film ruined the____________perfect product.A. ratherB. muchC.otherwiseD. particularly37. I'll have to____________this dress a bit before the wedding next week.A. let offB. let goC.let looseD. let out38. They reached a(n)____________to keep their dispute out of the mass madia.A. understandingB. acknowledgementC.limitationsD. misgivings39. After walking for hours without finding the village, we began to have____________about our map.A. troublesB. fearsC.limitationsD. misgivings40. If you don't want to talk to him, I'll speak to him____________.A. on your accountB. on your behalfC.for your partD. in your interestPAET ⅢCLOZE TEST (15 minutes, 15 points)Direction: There are 15 blanks in this part of the test, read the passage through, Then, go back and choose the suitable word or phrase marked A, B, C or D for each blank in the passage. Mark the corresponding letter of the world or phrase you have chosen with a single bar across the square brackets on your Machine-scoring Answer Sheet.The process by means of which human beings arbitrarily make certain things stand for other things many be called the symbolic process.Everywhere we turn, we see the symbolic process at work. There are__ 41__things men do or want to do, possess or want to possess, that have not a symbolic value.Almost all fashionable clothes are__ 42__symbolic, so is food. We__ 43__our furniture to serve __ 44__visible symbols of our taste, wealth, and social position. We often choose our houses__ 45__the basis of a feeling that it“looks well”to have a “good address.”We trade perfectly good cars in f or__ 46__models not always to get better transportation, but to give__ 47__to the community that we can __ 48__it.Such complicated and apparently__ 49__behavior leads philosophers to ask over and over again, “why cna't human beings__ 50__simply and natur ally.” Often the complexity of human life makes us look enviously at the relative__ 51__of such live as dogs and cats. Simply, the fact that symbolic process makes complexity possible is no__ 52__for wanting to__ 53__to a cat and to a cat-and-dog existence. A better solution is to understand the symbolic process__ 54__instead of being its slaves we become, to some degree at least, its__ 55__.41. A. many B. some C. few D. enough42. A. highly B. nearly C. merely D. likely43. A. makd B. get C. possess D. select44. A. of B. for C. as D. with45. A. on B. to C. at D. for46. A. earlier B. later C. former D. latter47. A. suggestion B. surprise C. explanation D. evidence48. A. use B. afford C. ride D. find49. A. useless B. impossible C. inappropriate D. unnecessary50. A. live B. work C. stay D. behave51. A. passivity B. activity C. simplicity D. complexity52. A. meaning B. reason C. time D. doubt53. A. lead B. devote C. proceed D. return54. A. so that B. in that C. considering that D. by reason that55. A. teachers B. students C. masters D. servantsPART ⅣREADING COMPREHENSION (60 minutes, 30 points)Directions: You will read five passage in this part of the test. Below each passage there are some question or incomplete statements. Each question or statement is followed by four choices marked A, B, C and D. Read the passage carefully, and then select the choice that best answers the question or completes the statement. Mark the letter of your choice with a single bar across the square brackets on your machine-scoring Answer Sheet.Passage1The Solar Decathlon is under way, and trams of students from 14 colleges and universities are building solar-powered homes on the National Mall in Washington, D. C. in an effort to promote this alternative energy source. This week judges in this Department of Energy (DOE) sponsored event will evaluate these homes and declare one the winner. Unfortunately, for the participants, it rained on the Sept 26th opening ceremonies, and the skies over the Washington have remained mostly overcast since. However, the conditions may have made for a more revealing demonstration of solar energy than was originally planned.Although the Solar Decathlon's purpose is to advertise the benefits of electricity-generating solar panels and other residential solar gadgets, the had weather has made it hard to ignore the limitations. As fate so amply demonstrated, not every day is a sunny day, and indeed D O E's“Solar Village on the National Mall” has receivedvery little of what it needs to run.Since solar is not an always available energy source, even a community consisting entirely of solar homes and businesses would still need to be connected to a constantly-running power plant (most likely natural gas or coal fired) to provide reliable electricity. For this reason, the fossil fuel savings and environmental benefits of solar are considerably smaller than many proponents suggest.Washington, D. C. gets its share of sunny days as well, but even so, solar equipment proveds only a modest amount of energy in relation to its cost. In fact, a $ 5,000 rooftop photovoltaic system typically generates no more than $ 100 of electricity per year, providing a rate of return comparable to a passbook savings account.Nor do the costs end when the system is installed. Like anything exposed to the elements, solar equipment is subject to wear and storm damage, and may need ongoing maintenance and repairs. In addition, the materials that turn sunlight into electricity degrade over time. Thus, solar panels will eventually need to be replaced, most likely before the investment has fully paid itself off in the form of reduced utility bills.Solar energy has always has its share of true believers willing to pay extra to feel good about their homes and themselves. But for homeowners who view it as an investment, it is not a good one. The economic realities are rarely acknowledged by the govenment officials and solar equipment manufactures involved in the Solar Decathlon and similarly one-sided promotions. By failing to be objective, the pro-solar crowd does consumers a real disservice.56. The Solar Decathlon is most probably the name of a____________.A. technologyB. contestC. strategyD. machine57. What does the author say about the weather?A. It is rare for Washington, D. C. to have such long rainy days.B. It has been raining since Sept 26th for the most of the time.C. It is favorable to the manufacturers to promote solar equipment.D. It has helped see the disadvantages of solar energy.58. What has happened to D O E's“Solar Village on the National Mall”?A. It has revealed a mechanical problem.B. It lacks the energy for operation.C. It needs substantial financial support.D. It has drawn criticism from the government.59. The environmental benefits of solar power are small because____________.A. solar power plants can hardly avoid polluting their surroundingsB. most people prefer the relatively simple use of fossil fuelC. the uses of solar enery still cannot go without fossil fuelD. only several communities entirely consist of solar energy homes60. It can be inferred that “a passbook savings account”____________.A. brings little interestB. brings much interestC. is a deposit of at least $ 100D. is a deposit of at least $ 500061. It can be inferred that in promoting solar energy the US government____________.A. admits its limitation of being expensiveB. rarely mentions its cost to homeownersC. stands on the side of the majority of consumersD. remains more objective than the solar equipment manufacturersPassage2Every year, the American Lung Association (ALA) releases its annual report card on smog, and every year it gives an“F” to over helf the nation's counties and cities. When ALA's “State of the Air ” recently came out, dozens of credulous local journalists once again took the bait, ominously reporting that their corner of the nation received a failing grade. The national coverage was no better, repeating as fact ALA's statement that it is “gravely concerned” about air quality, and neglect ing to solicit the views of even one scientist with a differing view. Toobad, because this report card says a lot less about actual air quality than it does about the tactics and motives of the ALA.The very fact that 60 percent of counties were giver an “F” seems to be alarmist. This is particularly true given that smog levels have been trending downward for several decades. According to the Environmental Protection Agency (EPA) statistics, ozone, the primary constituent of smog, progress will likely continue, even without the wave of new regulations ALA is now demanding.ALA is correct that some areas still occasionally exceed the federal standard for ozone, but such spiles are far less frequent than in the past. Even Los Angeles, the undisputed smon capital of America, has cleaned up its act considerably. Los Angeler,which exceeded federal smog standards for 154 days in 1989, has had 75percent fewer such spikes in recent years. But an ALA-assigned“F”misleadingly implies that air quality has not improved at all.Most of the nation is currently in attainment with the current smog standard, and much of the rest is getting close, Nonetheless, ALA chose to assign an “ F”to entire county based on just a few readings above a strict new EPA standard enacted in 1997 but not yet in force. In effect, ALA demanded a standard even more stringent than the federal government's, which allows some leeway for a few anomalously high reading in otherwise clean areas. ALA further exaggerated the public-health hazard by grossly overstating the risks of these relatively minor and sporadic increases above the standard.62.The media's response to ALA's “State of the Air ”can best be described as____________.A. trustingB. suspiciousC. criticalD. hesitant63. By citing figures from the EPA, the auther seem to contend that____________ .A. the regulations about smog have proved effectiveB. new regulations are necessary to deal with smogC. smog problems have actually become less seriousD. the federal smog standard has been rather low64. In Paragraph 3, the word “spikes”(in boldface) probably refers to____________.A. the increase above the smog standardB. the irregular readings about air quality in some areasC. the occurrences of smog in Los AngelesD. the current standards demanded by ALA65. The author draws on Los Angeles to prove that the ALA____________.A. is right to assign an “F”to that areaB. often bases its report on the past eventsC. has a good reason to stress smog risksD. has overstated smog problems66. The author agrees with the ALA that____________.A. present smog standards should be made stricterB. the standard established by the EPA is effectiveC. some areas fail to meet the federal standard at timesD. poor air quality is a major problem nationwide67. One of the problems with the ALA seems to be____________.A. its lack of opinions from expertsB. its focus on some irregular casesC. its attempt to make up the dateD. its inconsistent smog standardsPassage3It wa s (and is )common to think that other animals are ruled by“instinct”whereas humans lost their instincts and ruled by “reason,”and that this is why we are so much more flexibly interlligent than other animals. William James, in his book Principles of psychology, took the opposite view. He argued that human behavior is more flexibly intelligent than that of other animals because we have more instincts than they do, not fewer. We tend to be blind to the existence of these instincts, however, precisely because they work so well-because they processinformation so effortlessly and automatically. They structure our thought so powerfully, he argued, that it can be difficult to imagine how things could be otherwise. As a result, we take“normal” behavior for granted. We do not realize that “normal”behavior needs to be explained at all. This“instinct blindness”makes the study of psychology difficult. To get past this problem, James suggested that we try to make the “natural seen strange.”“It takes a mind debauched by learning to carry the process of making the natural seem strange, so far as to ask for the why of any instinctive human act.”In our view, William James was right about evolutionary psychology. Making the natural seem strange is unnatural—it requires the twisted outlook seen, for example, in Gary Larson cartoons. Yet it is a central part of the enterprise. Many psychologists avoid the study of natural competences, thinking that there is nothing there to be explained. As a result, social psychologists are di sappointed unless they find a phenomenon “that would surprise their grandmothers,” and cognitie psychologists spend more time studying how we solve problem we are bad at, like learning math or playing chess, than ones we are good at. But natural competences—our abilities to see, to speak, to find someone beautiful, to reciprocate a favor, to fear disease, to fall in love, to initiate an attack, to experience moral outrage, to navigate a landscape, and myriad others—are possible only because there is a vast and heterogeneous array of complex computational machinery supporting and regulating these activities. This machinery works so well that we don't even realize that it exists—we all suffer from instinct blindness. As a result, psychologists have neglected to study some of the most interesting machinery in the human mind.68. William James believed that man is mor flexibly intelligent than other animals because man is more____________.A. adaptiveB. reasonableC. instinctiveD. sophisticated69. What do we usually think of our normal behavior?A. It is controlled by powerful thoughts.B. It is beyond the study of psychology.C. It doesn't need to be explained.D. It doesn't seem to be natural sometimes.70. According to the author, which of the following is most likely studied nowadays by psychologists?A. Why do we smile when pleased?B. Why do we love our children?C. How do we appreciates beautiful?D. How do we reason and process information?71. The author thinks that psychology is to____________.A. take the normal behavior for grantedB. make the natural seem strangeC. study abnormal competencesD. make easy things difficult72. The author stresses that our natural abilities are____________.A. not replaced by resoningB. the same as other animals'sC. not as complex as we thinkD. worth studyingPassage4In her 26 years of teaching English, Shannon McCuire has seen countless misplaced commas, misspelled words and sentence fragments.But the instructor at US's Louisiana State University in Baton Rouge said her job is getting harder every day.“I kid you not, the number of errors that I've seen in the past few years have multiplied five times,”she said.Experts say e-mail and instant messaging are at least partly to blame for an increasing indifference toward the rules of grammar, spelling and sentence structure.They say the problem is most noticeable in college students and recently graduates.“They used to at least feel guilty (about mistakes),”said Naomi Baron, professor of linguistics at American University in Washington, D. C.“They didn't necessarily write a little better, but at least they felt guilty.”Ironically, Baron's latest book,“Alphabet to Email: How Written English Evolved and Where It's Heading,”became a vic tim of sloppy proofreading. The book's title is capitalized differently on the cover, spine and title page.“People used to lose their jobs over this,”she said. “And now they just say ‘whatever.’”“Whatever”describes Jeanette Henderson's attitude toward wr iting. The sophomore at the University of Louisiana at Monroe admits that her reliance on spellcheck has hurt her grades in English class. “Computer has spoiled us,”she said.But the family and consumer sciences major believes her future bosses won't mind the mistakes as much as her professor does. “They're not going to check semicolons, commas and stuff like that,” Hen derson said.LSU's McGuire said she teaches her students to use disftinct writing styles that fit their purpose.She emphasizes that there's the mformal language of an e-mail to a friend, but there's also the well thoght out and structured academic or professional style of writing.It's not just e-mail and instant messaging that are contributing to slack writing habits.Society as whole is becoming more informal. Casual wear at work used to be reserved for Friday, for example, but is now commonplace at most offices. There's also a greater emphasis on youth culture, and youth tend to use instant messaging more than adulte do.English language has been neglected at different points in history but always rebounds. During Shakespearen times, for example, spelling wasn't considered important, and early publishers rarely proofread.There will likely be a social force that recognizes the need for clear writing and swings the pendulum back.73. According to Shannon McGuire, what is making her job harder than before?A. More and more students ask her to teach how to write instant messages.B. More and more structural errors are seen in her student's writings.C. Students are becoming increasingly indifferent to learning English.D. Parents are more demanding as to the teaching content of the school.74. We can infer from the passage that college students____________.A. are the victims of the deteriorating educationB. mostly have very had handwritingC. don't think they're writing bad EnglishD. are ashamed of their poor writing skills75. What happened to Baron's latest book?A. It was poorly edited.B. It failed to come out.C. It w as renamed“Whatever”.D. It caused her to lose her job.76. What does Jeanette Henderson mainly study at the university?A. Computer ScienceB. LinguisticsC. Editing and PublishingD. Family and Consumer Sciences77. According to the passage, sloppy writing____________.A. parallels a social tendency of being informalB. worries students as well as professorsC. is taken as trivial by employersD. is ignored in all business concerned sciences78.The word“distinct”(in boldface)in the context means____________.A. clearB. differentC. elegantD. appropriate79. Which is NOT mentioned as a cause of American students' casual writing?A. EmailingB. Slack teachingC. ElegantD. Appropriate80. How does the author feel about the future of the English language?A. ConfidentB. GloomyC. WorriedD. UncertainPassage5Darkness approached and a cold, angry wind gnawed at the tent like a mad dog. Camped above treeline in the Wind River Mountains of Wyoming, the torrents of air were not unexpected and only a minor disturbance compared to the bestial gnawing going on behind my belly button. In an attempt to limit exposure of my bare bottom to the ice-toothed storm, I had pre-dug a half dozen catholes within dashing distance. Over and over, through the long night, the same scenario was repeated: out of the bay, out of the tent, rush squat, rush back.“Everyone can master a grief,”wrote Shakespeare,“but he that has it.”Diarrhea, the modern word, resembles the old Greek expression for“a flowing through.”Ancient Egyptian doctors left descriptions of the suffering of Pharaohs scratched on papyrus even before Hippocrates, the old Greek, gave it a name few people can spell correctly. An equal opportunity affliction, diarrhea has laid low kings and common men, women, and children for at least as long as historians have recorded such fascinating trivia. It wiped out, almost, more soldiers in America's Civil War that guns and sword. In the developing world today, acute diarrhea strikes more than one billion humans every year, and leaves more than five million dead, usually the very young. Diarrhea remains one of the two most common nedical complaints of humanity.“Frequent passage of unformed watery bowel movements,”as described by Taver's Cyclopedic Med ical Dictionary, diarrhea falls into two broad types:invasive and non-invasive. From bacterial sources, invasive diarrhea, sometimes called“dysentery,”attacks the lower intestinal wall causing inflammation, abscesses, and ulcers that may lead to mucus and blood(often“black blood”from the action of digestive juices) in the stools, high fever,“stomach”crams from the depths of hell, and significant amounts of body fluid rushing from the patient's nether region. Serious debilitation, even death, can occur from the resulting dehydration and from the spread of the bacteria to other parts of the body. Non-invasive diarrheas grow from colonies of microscpic evil-doers that set up housekeeping on, but do not invade, intestinal walls. Toxins released by the colonies cause cramps, nausea, vomiting, and massive gushes of fluid from the patient's lower intestinal tract. Non-invasive diarrhea carries a highrisk for dehydration.81.In Paragraph 1, the author uses the quoted word“grief”from Shakespeare to refer to____________.A. the terrible weatherB. the stern army lifeC. the suffering from diarrheaD. the tough wartime82. According to the description in Paragraph 1, which of the following did the author NOT do at that time?A. withstanding the coldnessB. Camping in the mountainsC. Getting up repeatedly at nightD. Reading Shakespeare in bed83. Who first gave the disease the name“diarrhea”?A. Ancient EgyptiansB. An old GreekC. American soldiersD. The passage doesn't tell84. According to Paragraph 2____________.A. People of higher status are less likely to be stricken with diarrheaB. diarrhea is no longer a serious disease in the modern worldC. diarrhea has been a threat to humanity throughout historyD. the elderly are more likely attacked by diarrhea than the young85. The invasive diarrhea and the non-invasive diarrhea are different in that____________.A. the former attacks the intestine walls but the latter does notB. the former causes dehydration but the latter does notC. the former makes the patient physically weaker than the latterD. the former is more dangerous than the latterPART ⅤTRANSLATION (30 minutes, 10 points)Directions: Read the following text carefully and then translate the underlined segments into Chinese. Write your pieces of Chinese version in the proper space on your Answer Sheet Ⅱ.The aim of education or culture is merely the development of good taste in knowledge and good form in conduct. The cultured man or the ideal educated man is not necessarily one who is well-read or learned, but one who likes and dislikes the right things. To know what to love and what to hate is to have taste in knowledge. 1I have met such persons, and found that there was no topic that might come up in the course of the conversation concerning which they did not have some facts or figures to produce, but whose points of vies were appalling. Such persons have erudition (the quality of being knowledgeable), but no discernment; or taste, Erudition is a mere matter of stuffing fact or information, while taste or discernment is a matter of artistic judgment. 2.In speaking of a scholar, the Chinese generally distinguish between a man's scholarship, conduct, and taste or discernment. This is particularly so with regard to historians; a book of history may be written with the most thorough scholarship, yet be totally lacking in insight or discernment, and in the judgment or interpretaion of persons and events in history, the author may show no originality or depth of understanding. Such a person, we say, has no taste in knowledge. To be well-informed, or to accumulate facts an details, is the easiest of all things. 3.There are many facts in a given historical period that can be easily stuffed into our mind, but discernment in the selection of significant facts is a vastly more difficult thing and depends upon one's point of view.An educated man, therefor, is one who has the right loves and hatreds. This we call taste, and with taste comes charm. 4. Now to have taste or discernment requires a capacity for thinking things through to the bottom, an independence of judgment, and an unwillingness to be knocked down by any form fo fraud, social, political, literary, artistic, or academic.There is no doubt that we are surrounded in our adult life with a wealth of fraude: fame frauds, wealth frauds, patriotic frauds, political frauds, religious frauds and fraud poets, fraud artists, fraud dictators and frauds psychologists. When a psychoanalyst tells us that the performing of the functions of the bowels during childhood has a definite connection or that constipation leads to stinginess of character, all that a。
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The Universe's Invisible Hand By Christopher J. Conselice
Dark energy (暗能量) does more than hurry along the expansion of the universe. It also has a stranglehold on the shape and spacing of galaxies
What took us so long? Only in 1998 did astronomers discover we had been missing nearly three quarters of the contents of the universe, the so-called dark energy--an unknown form of energy that surrounds each of us, tugging at us ever so slightly, holding the fate of the cosmos in its grip, but to which we are almost totally blind. Some researchers, to be sure, had anticipated that such energy existed, but even they will tell you that its detection ranks among the most revolutionary discoveries in 20th-century cosmology. Not only does dark energy appear to make up the bulk of the universe, but its existence, if it stands the test of time, will probably require the development of new theories of physics. Scientists are just starting the long process of figuring out what dark energy is and what its implications are. One realization has already sunk in: although dark energy betrayed its existence through its effect on the universe as a whole, it may also shape the evolution of the universe's inhabitants--stars, galaxies, galaxy clusters. Astronomers may have been staring at its handiwork for decades without realizing it. 暗能量不仅仅会加速宇宙膨胀。它也对星系的形状和间隔有所束缚。 是什么让我们花费了那么长时间?直到1998年宇航员才发现我们几乎忽略了宇宙中四分之三的能源,所谓的暗能量—我们周围一种不为人知的能量,轻轻将我们拉住,掌控了宇宙的命运。但是,对此我们一无所知。事实上,一些研究者早已预料到,这种能量是存在的,但是,他们将告知你,这是20世纪宇宙学上革命性的发现。暗能量不仅是宇宙的一大组成部分,而且如果能经受时间的考验,它的存在很可能需要物理学最新理论发展来作为支撑。 科学家们正着手研究暗能量的本质和影响,其中一项发现是:暗能量通过对整个宇宙的影响暴露了它的存在,它也可以使宇宙中星系,银河系产生变化。宇航员们数几十年来也许一直致力于它的影响,而忽略了它的存在。
Cosmic BubblesVladimir S. Netchitailo【期刊名称】《Journal of High Energy Physics, Gravitation and Cosmology》【年(卷),期】2024(10)1【摘要】The present paper is inspired by the article “Ho’oleilana: An Individual Baryon Acoustic Oscillation?” published by R. B. Tully, C. Howlett, and D. Pomarède on Sep. 2023 [1]. They claim: Evidence is presented here for the discovery of a remarkably strong individual contribution to the baryon acoustic oscillation (BAO) signal at z = 0.068, an entity that is given the name Ho’o leilana. K. Dawson, co-spokespersonfor Dark Energy Spectroscopic Instrument is more inclined to believe that this latest finding is something of a coincidence, a chance alignment that simply looks like a sphere with a radius around what you’d expect for a BAO [2]. In this paper, we provide a short summary of experimental observations of Boötes Void and Superclusters;discuss the main features of the developed Hypersphere World-Universe Model;introduce notions “Cosmic Voids” and “Cosmic Bubbles”;elaborate a mathematical framework for different types of Cosmic Bubbles (Hubble Spherical Bubble for the World, Disk Bubbles for Galaxies;Spherical Bubbles for Extrasolar Systems, Dark Matter (DM) Spherical Bubbles for Galaxies and Superclusters);make a conclusion th at the Boötes is a DM Cosmic Bubble and suggest experiments, which confirm our conclusion.【总页数】16页(P438-453)【作者】Vladimir S. Netchitailo【作者单位】Freelancer, Livermore, USA【正文语种】中文【中图分类】O57【相关文献】1.A Cosmic Microscope to Probe the Universe from Present to Cosmic Dawn:Dual-element Low-frequency Space VLBI Observatory2.Cosmic Time as an Emergent Property of Cosmic Thermodynamicsputational study of bubble coalescence/break-up behaviors and bubble size distribution in a 3-D pressurized bubbling gas-solid fluidized bed of Geldart A particles4.High-precision Measurements of Cosmic Curvature from Gravitational Wave and Cosmic Chronometer Observations5.Potential for Constraining Propagation Parameters of Galactic Cosmic Rays with the High Energy Cosmic-radiation Detection Facility on Board China's Space Station因版权原因,仅展示原文概要,查看原文内容请购买。
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The theory of ellipsoidal harmonics, orience in analysis. The first four chapters present a practical introduction to analysis by using the tools and concepts hey comprise the Internet’s infrastructural backbone. The first of its kind, this book develops the mathematical frame rt space operators. Its emphasis is on recent aspects of theory and detailed proofs, with the primary goal of offering ost of his working life in China and suffered at first hand the turbulence of twentieth-century Chinese politics. His i the basic tools and techniques needed for research in various areas of geometric analysis. Throughout, the main theme in the interplay between partial differential equations and probability theory. Most of this material has been treated ate students, starting from the axioms for a complete ordered field and a little set theory. The book avoids any precon physicists and engineers with a means of solving partial differential equations subject to boundary conditions. The tex he centenary of James Clerk Maxwell's birth. Comprised of ten essays dealing with various aspects of Maxwell's life and t of both new and traditional curricula in an effort to meet the needs of even more instructors teaching calculus. The s book focuses on second-order equations with constant coefficients that derive their general solution using only resul ational skills and intuitive understanding with a careful balance of theory, applications, historical development and o n a direct, engaging, and accessible manner while illustrating the power of the theory through many, often surprising, ent Mathematics Conference, held in November 2010 at Harvard University.</p>nt strategies, health sciences, environment, industrial engineering, etc.rticles presented by the invited speakers of the conference on “Harmony of Gröbner Bases and the Modern Industrial Soc rses, Moore–Penrose inverses, Drazin inverses and T–S outer generalized inverses and their perturbation analyses in t rehensive compilation, description, and discussion of recent advancements on quantitative linguistics carried out from r's leitmotifs, musing over Kandinsky's chaos, and contemplating Wittgenstein's inner thoughts.This penultimate volumemesh methods for singularly perturbed problems has expanded significantly. Over the intervening years, fitted meshes haof math departments. The text presents some of the most important topics and methods of mathematicaloncise manner. The book is excellent at balancing theory and applications with a wealth of examples aas and concepts in the theory of compressible fluids, in particular, the question of existence for optimal values of th psoidal harmonics, originated in the nineteenth century, could only be seriously applied with the kind of computationalhe tools and concepts of calculus. The last five chapters present a first course in analysis. The presentation is clear the mathematical framework needed from a control perspective to tackle various game-theoretical problems in optical net mary goal of offering a modern introductory textbook for a first graduate course in the subject. The coverage of topics hinese politics. His influence has been credited with inspiring generations of mathematicians, while his papers on numb ghout, the main theme is to present the interaction of partial differential equations and differential geometry. More s rial has been treated elsewhere, but it is rarely presented in a manner that makes it easy to understand for people who book avoids any preconceptions about the real numbers and takes them to be nothing but the elements of a complete order ry conditions. The text gives a systematic and unified approach to a wide class of problems, based on the fact that the of Maxwell's life and achievements, the text includes contributions from the following figures: J. J. Thomson; Max Pla eaching calculus. The author team's extensive experience teaching from both traditional and innovative books and their ution using only results described previously. Higher-order equations are provided since the patterns are more readily ical development and optional materials.ny, often surprising, applications. It offers a comprehensive presentation that uses a combination of rigorous argument Modern Industrial Society”. Topics include computational commutative algebra, algebraic statistics, algorithms of D-m urbation analyses in the spaces of infinite-dimensional. This subject has many applications in operator theory, operatotics carried out from the perspective of complex systems. It provides an overview of the emergence and construction of is penultimate volume contains numerous original, elegant, and surprising results in 1-dimensional cellular automata. Pears, fitted meshes have been shown to be effective for an extensive set of singularly perturbed partial differential etical physics. The premise is to study in detail the three most important partial differential equatioles and exercises. The authors take a progressive approach of skill building to help students learn toor optimal values of the adiabatic exponent, which up to now has been unsolved.e kind of computational power available in recent years. This, therefore, is the first book devoted to ellipsoidal harm e presentation is clear and concise, allowing students to master the calculus tools that are crucial in understanding a problems in optical networks. In doing so, it aims to help design control algorithms that optimally allocate the resour The coverage of topics is thorough, as the book explores various delicate points and hidden features often left untreahile his papers on number theory are regarded as 'virtually an index to the major activities in that subject during the ential geometry. More specifically, emphasis is placed on how the behavior of the solutions of a PDE is affected by the derstand for people whose background is probability theory. Many results are given proofs designed for readers with lim nts of a complete ordered field. All of the standard topics are included, as well as a proper treatment of the trigonom ed on the fact that the solution may be viewed as a point in function-space, this point being the intersection of two l J. J. Thomson; Max Planck; Albert Einstein; Joseph Larmor; James Jeans; William Garnett; Ambrose Fleming; Oliver Lodge vative books and their expertise in developing innovative problems put them in an unique position to make this new curr tterns are more readily grasped by students. Stability and fourth order equations are also discussed since these topicon of rigorous arguments and extensive illustrations to facilitate an understanding of the material. The author covers tics, algorithms of D-modules and combinatorics. This volume also provides current trends on Gröbner bases and will sti perator theory, operator algebras, global analysis and approximation theory and so on.S table Perturbations of Operatorsce and construction of linguistic structures, addressing those concepts that have become the key ideas of complexity: o al cellular automata. Perhaps the most exciting, if not shocking, new result is the discovery that only 82 local rules,partial differential equations. In the revised version of this book, the reader will find an introduction to the basicuations in the field - the heat equation, the wave equation, and Laplace’s equation. The most commonrn to absorb the abstract. Real world applications, probability theory, harmonic analysis, and dynamied to ellipsoidal harmonics. Topics are drawn from geometry, physics, biosciences and inverse problems. It contains cla ial in understanding analysis. From Calculus to Analysis prepares readers for their first analysis course—important be ly allocate the resources of these networks. </p>With its fresh problem-solving approach, 'Game Theory for Control of O ures often left untreated. </p>Spectral Theory of Operators on Hilbert Space</i> is addressed to an interdisciplinary ahat subject during the first half of the twentieth century.' Introduction to Higher Mathematics is based on the lecture PDE is affected by the geometry of the underlying manifold and vice versa. For efficiency the author mainly restricts h d for readers with limited expertise in analysis. The author covers the theory of linear, second order partial differen atment of the trigonometric functions, which many authors take for granted. The final chapters of the book provide a ge intersection of two linear subspaces orthogonal to one another. Using this method the solution is located on a hyperci Fleming; Oliver Lodge; Richard Glazebrook; Horace Lamb. This book will be of value to anyone with an interest in Maxwe to make this new curriculum meaningful for those going into mathematics and those going into the sciences and engineer ssed since these topics typically appear in further study for engineering and science majors. In addition to applicatial. The author covers basic topology, ranging from the axioms of topology to proofs of important theorems. He also discK ey Features: • Compre ner bases and will stimulate further development of many research areas surrounding Gröbner bases.urbations of Operators and Related Topics is self-contained and unified in presentation. It may be used as an advanced ideas of complexity: order and entropy, information, correlation, self-organization, network patterns, evolution, and st only 82 local rules, out of 256, suffice to predict the time evolution of any of the remaining 174 local rules from aroduction to the basic theory associated with fitted numerical methods for singularly perturbed differential equations.ommon techniques of solving such equations are developed in this book, including Green’s functions, tynamical systems theory are included, offering considerable flexibility in the choice of material to c oblems. It contains classical results as well as new material, including ellipsoidal bi-harmonic functions, the theory is course—important because many undergraduate programs traditionally require such a course. Undergraduates and some a Theory for Control of Optical Networks' is a unique resource for researchers, practitioners, and graduate students in a an interdisciplinary audience of graduate students in mathematics, statistics, economics, engineering, and physics. Itis based on the lectures given by Hua at the University of Science and Technology of China from 1958. The course reflec thor mainly restricts himself to the linear theory and only a rudimentary background in Riemannian geometry and partial order partial differential equations of parabolic and elliptic type. Many of the techniques have antecedents in proba f the book provide a gentle, example-based introduction to metric spaces with an application to differential equations is located on a hypercircle in function-space, and the approximation is improved by reducing the radius of the hypercir th an interest in Maxwell and his key role in the development of physics and mathematics.e sciences and engineering. This new text exhibits the same strengths from earlier editions including an emphasis on n addition to applications to engineering systems, applications from the biological and life sciences are emphasized. theorems. He also discusses the classification of compact, connected manifolds, ambient isotopy, and knots, which leadK ey Features:• A guid • Comprehensive treatment of Gröbner bases • Articles by leading figures in the mathematics worlds.be used as an advanced textbook by graduate students. It is also suitable for researchers as a reference. The proofs ofT he focus of quantitative linguistics is to detect, characterize, and explain the patter terns, evolution, and strategy.174 local rules from an arbitrary initial bit-string configuration. This is contrary to the well-known folklore that 2differential equations. Fitted mesh methods focus on the appropriate distribution of the mesh points for singularly perns, the Fourier transform, and the Laplace transform, which all have applications in mathematics andto cover in the classroom. The accessible exposition not only helps students master real analysis, b functions, the theory of images in ellipsoidal geometry and vector surface ellipsoidal harmonics, which exhibit an inte ergraduates and some advanced high-school seniors will find this text a useful and pleasant experience in the classroom graduate students in applied mathematics and systems/control engineering, as well as those in electrical and computer e ering, and physics. It will also be useful to working mathematicians using spectral theory of Hilbert space operators,958. The course reflects Hua's instinctive technique, using the simplest tools to tackle even the most difficult proble n geometry and partial differential equations is assumed. Originating from the author's own lectures, this book is an i e antecedents in probability theory, although the book also covers a few purely analytic techniques. In particular, a c ifferential equations on the real line. The author's exposition is concise and to the point, helping students focus on radius of the hypercircle. The complexities of calculation are illuminated throughout by simple, intuitive geometricalcluding an emphasis on modeling and a flexible approach to technology.nces are emphasized. Ecology and population dynamics are featured since they involve both linear and nonlinear equatio and knots, which leads to coverage of homotopy theory.• A guidebook for graduate students • The reader can see a panoramic view of Gröbner baseshematics worldference. The proofs of statements and explanations in the book are detailed enough that interested readers can study it and explain the patterns of language by means of mathematical tools. The last two decades have witnessed a sharp increa-known folklore that 256 local rules are necessary, leading to the new concept of quasi-global equivalence.Another surpnts for singularly perturbed problems. The global errors in the numerical approximations are measured in the pointwiseand physics far beyond solving the above equations. The book’s focus is on both the equations and tis, but also makes the book useful as a reference., which exhibit an interesting analytical structure. Extended appendices provide everything one needs to solve formally rience in the classroom or as a self-study guide. The only prerequisite is a standard calculus course.ectrical and computer engineering.</p>lbert space operators, as well as for scientists wishing to apply spectral theory to their field. </p>e most difficult problems, and contains both pure and applied mathematics, emphasising the interdependent relationships ures, this book is an ideal introduction for graduate students, as well as a useful reference for experts in the field. ues. In particular, a chapter is devoted to the DeGiorgi-Moser-Nash estimates and the concluding chapter gives an intro ping students focus on the essentials. Over 200 exercises of varying difficulty are included, many of them adding to th intuitive geometrical pictures. This book will be of value to anyone with an interest in solutions to boundary value pr and nonlinear equations, and these topics form one application thread that weaves through the chapters. Diffusion ofK ey Features: • The stable perturbation theory of generalized inverses, Drazin inv ed readers can study it by themselves.itnessed a sharp increase in the interest of physicists and applied mathematicians on language, and it is not surprisinquivalence.Another surprising result is the introduction of a simple, yet explicit, infinite bit string called the supesured in the pointwise maximum norm. The fitted mesh algorithm is particularly simple to implement in practice, but thend their methods of solution. Ordinary differential equations and PDEs are solved including Bessel Fuolve formally boundary value problems. End-of-chapter problems complement the theory and test the rea ependent relationships between different branches of the discipline.experts in the field.chapter gives an introduction to the theory of pseudodifferential operators and their application to hypoellipticity, i y of them adding to the theory in the text. The book is perfect for second-year undergraduates and for more advanced st ns to boundary value problems in mathematical physics.hapters. Diffusion of material, heat, and mechanical and electrical oscillators are also important in biological and e d inverses, Drazin inverses and index of a Fredholm element relative to a homomorphismare are of unique interest in thind it is not surprising that this explosion was parallel to the expansion of the interest in complex systems. This book string called the super string S, which contains all random bit strings of finite length as sub-strings. As an illustra。
arXiv:hep-th/0205227v2 29 May 2002UUITP-07/02hep-th/0205227
Inflation,holography,andthechoiceofvacuumindeSitterspace
UlfH.DanielssonInstitutionenf¨orteoretiskfysikBox803,SE-75108Uppsala,Sweden
ulf@teorfys.uu.se
AbstractAfamilyofdeSittervacuaintroducedinhep-th/0203198asplausibleinitialcondi-tionsforinflation,arediscussedfromthepointofviewofdeSitterholography.ThevacuaarearguedtobephysicallyacceptableandtheinflationarypictureprovidesaphysicalinterpretationofasubfamilyofdeSitterinvariantvacua.SomespeculationsontheissueofvacuumchoiceandtheconnectionbetweentheCMBRandholographyarealsoprovided.
May20021IntroductionInrecentyearstherehasbeenasignificantinterestintheuseofcosmologyasaprobeofhighenergyphysics.Awellestablishedexampleisprovidedbyinflationwheremicroscopicquantumfluctuationsaremagnifiedtomacroscopicscales,andactasseedsforsubsequentstructureformationintheearlyuniverse.Foranicereviewsee[1].AnintriguingpossibilityisthatinflationmightprovideawindowtowardsphysicsbeyondthePlanckscale.InthestandardinflationaryscenariothefluctuationsstartoutwithalinearsizemuchsmallerthanthePlanckscale.Neverthelessitisassumedthatnonewphysicsappear,andanaturalvacuumforthequantumfluctuationsischosenwiththisinmind.Inseveralrecentworkstherationalityofthisassumptionhasbeenquestioned,[2-26].Afterall,intherealworldweknowthatfundamentallynewphysicsistobeexpectedatthePlanckscaleandbeyond.TheideaisthatthefluctuationspectrummightleaveanimprintontheCMBRthatdependsonthedetailsofthistransplanckianphysics.Severalexamplesexistintheliteratureofspecificmodificationsofthehighenergyphysicswhichalsogiveamodifiedspectrum.In[27](andmorerecentlyin[28])anotherpointofviewwastakenwiththefocusonthechoiceofvacuum.Initialconditions(foraparticularmode)wereimposedwhenthewavelengthwascomparabletosomefundamentallengthscaleinthetheory.ItwasshownthatthisleadstocorrectionsoforderHfourthepropertiesofthevacuarelevantforinflationarediscussed.Finally,sectionfivecontainssomeconclusionsandspeculationsonpossiblerelationswithholography.
2AdeSitterfamilyofvacuaDeSitterspacedoesnothaveagloballytimelikeKillingvectorandthechoiceofvacuumisthereforeahighlynontrivialissue[61].ForthestudyofphysicsindeSitterspacethereareseveraldifferentcoordinatesystemsavailable.Belowwewillconsiderglobalcoordinates(withsphericalspatialsections)thatcoverthefulldeSitterspace,andplanarcoordinates(withflatspatialsections)thatonlycoverhalfofdeSitterspace.Inthelastsectionwewillmakeuseofyetanothertypeofcoordinates,thestaticcoordinates,whichareusefulwhenthefocusisonobservationsmadebyaparticularobserver.Theplanarcoordinatesaretheonesthatarerelevantforaninflatingcosmology,whereonlyhalfofdeSitterspaceisphysical.ThePenrosediagramofdeSitterspacehastheshapeofasquare,andcanbeviewedasconsistingoftwoparts.Aninflatingcosmologyintheupperrighttriangle,andadeflatingcosmologyinthelowerleft.TheyareseparatedbyalightlikesurfacecorrespondingtotheBigBangortheBigCrunchrespectively.Wewill,however,firstinvestigatethechoiceofvacuumfromthepointofviewglobalcoordinates,closelyfollowingtheanalysisof[53][54].DeSitterspaceinDdimensionscanbedefinedthroughahypersurface
−X20+Di=1X2i=1thesphericalharmonicsonS3.Forclaritywewillputanhatonalloperatorvaluedfields.Thevacuumofthetheoryisdefinedtoobey
an|Ω=0.(6)ThevacuumindeSitterspaceisnotunique,instead,aswasfirstdiscussedin[62],andlaterin[63][64][65],thereisawholefamilyofpossiblevacua.Morerecentdiscussions,inthecontextofdeSitterholography,canbefoundin[53][54].Differentchoicescorrespondtodifferentmodeexpansions,liketheonein(4),wherethedifferentchoicesarerelatedthroughBogolubovtransformations.ForourstudyofthevariousvacuaitwillbeconvenienttousetheWightmanfunctiondefinedby
G+(x,x′)=Ω|φ(x)φ(x′)|Ω=nφn(x)φ∗n(x′).(7)
TheWightmanfunctionisausefulbuildingblockfromwhichtheotherGreen’sfunctionscanbeobtained.ThroughthestudyoftheWightmanfunctiononecanlearnaboutthepropertiesofthevacuathatoneisinterestedin.AvacuumthatwillplayaspecialroleistheBunch-Daviesvacuum(alsoknownastheEuclideanvacuum)whichisobtainedbyanalyticalcontinuationfromtheEuclideansphere.IthasaWightmanfunctiongivenby
G+E(x,x′)=E|φ(x)φ(x′)|E=Γ(h+)Γ(h−)2
,(8)
whereh±=39