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大学物理-电磁学(英文授课)

大学物理-电磁学（英文授课）IntroductionElectromagnetism is a field of physics that concerns itself with the study of electromagnetic forces and fields. It is a branch of physics that focuses on the interaction between electrically charged particles, including charged particles at rest and moving charges. This course is designed to help students understand the basic principles of electromagnetism, including electric and magnetic fields, electromagnetic radiation, and electromagnetic waves.Electric FieldsElectric fields are created by electric charges, which are either positive or negative. The electric field is said to be the space surrounding a charged particle. If another charged particle is placed in the electric field, it will experience a force. The direction of the force depends on the charge of the particle and the direction of the electric field.Magnetic FieldsMagnetic fields are created by moving charges. A magnetic field is said to be the space surrounding a magnetic object. If a charged particle is placed in a magnetic field, it will move in a circular path. The direction of the circular path depends on the charge of the particle and the direction of the magnetic field. Electromagnetic FieldsAn electromagnetic field is created by the interaction of an electric field and a magnetic field. Electromagnetic fields have both electric and magnetic components, and they travel through space at the speed of light. Electromagnetic waves are a form of electromagnetic radiation that carries energy. Electromagnetic radiation includes radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.Maxwell's EquationsMaxwell's equations describe the behavior of electric and magnetic fields. They are a set of partial differential equations that relate the electric and magnetic fields to the electric charges and currents that are present. The equations describe how an electric field can produce a magnetic field, and a magnetic field can produce an electric field. They also describe how the electromagnetic fields propagate through space.Electromagnetic WavesElectromagnetic waves are waves of energy that are propagated through space by the interaction of electric and magnetic fields. Electromagnetic waves do not require any medium to propagate through. They can travel through a vacuum, which is why they are also known as vacuum waves.Electromagnetic waves are classified based on their frequency and wavelength. Radio waves have the lowest frequency, and gamma rays have the highest frequency. Radio waves have the longest wavelength, and gamma rays have the shortest wavelength.Applications of ElectromagnetismElectromagnetism has many practical applications in our daily lives. Some of the most common applications include electric motors, generators, transformers, telecommunication devices, medical imaging devices, and microwave ovens. Electromagnetism has also played a significant role in the development of modern technology, including computers, television, radio, and mobile phones.ConclusionElectromagnetism is a fascinating field of physics that has wide-ranging applications in our daily lives. This course provides students with a comprehensive understanding of electric and magnetic fields, electromagnetic radiation, and electromagnetic waves. By studying electromagnetism, students can gain a deeper appreciation for the fundamental principles that govern the behavior of the universe around us.Electromagnetism is one of the four fundamental forces of nature, along with gravity, strong nuclear force, and weak nuclear force. It is a field of physics with numerous applications in our modern society. Without the understanding of electromagnetism, we would not have the modern comforts that we have today, including electricity, the internet, cell phones, and many other devices.One of the most significant contributions of electromagnetism to modern society is the use of electric motors. Electric motors are devices that convert electrical energy into mechanical energy.They are used in a wide range of applications, from household appliances to transportation systems. The underlying principle of electric motors is electromagnetic induction, which is the process of inducing an electric current in a conductor by varying the magnetic field around it.Another important application of electromagnetism is in generators. Generators are devices that convert mechanical energy into electrical energy. They are often used in power plants to generate electricity that is distributed to homes and businesses. The principle of electromagnetic induction is also used in generators. When a conductor moves through a magnetic field, an electric current is induced in the conductor.Electromagnetism also plays a central role in the functioning of transformers. A transformer is a device that changes the voltage of an alternating current (AC) power supply. Transformers are used to step up or step down the voltage of an AC power supply. They are used in power grids to maintain a constant voltage throughout the grid. The principle used in transformers is electromagnetic induction, with the primary and secondary coils of wire interacting with the magnetic field to produce the desired voltage change. Telecommunication devices, including radios, televisions, and cell phones, also rely on the principles of electromagnetism. The radio waves used for communication are a form of electromagnetic radiation. Radio waves are used to transmit and receive signals between devices. The workings of these devices depend on the principles of electromagnetic induction and electromagnetic radiation.In addition to powering devices, electromagnetism is used in medical imaging devices. Magnetic resonance imaging (MRI) machines use magnetic fields and radio waves to produce images of the body's internal structures. The patient is placed in a powerful magnetic field, which causes the protons in their body to align with the field. A radio wave is then sent through the body, causing the protons to produce a signal. The signal is detected, and an image is produced based on the strength and location of the signal.Microwave ovens are another example of electromagnetism in action. These appliances use microwaves to cook food. Microwaves are a type of electromagnetic radiation with a frequency of around 2.4 GHz. The microwaves cause the water molecules in the food to vibrate rapidly, producing heat. This heats the food quickly and evenly, making it a popular method for cooking.The study of electromagnetism has also led to the development of modern technology. Computers, televisions, radios, and cell phones all rely on the principles of electromagnetism. The development of these technologies has revolutionized the way we live and communicate. The internet, for example, would not exist without the principles of electromagnetism.In conclusion, electromagnetism is a fascinating field of physics with numerous practical applications in our daily lives. It is the foundation of modern technology, and our society would not be the same without it. By studying electromagnetism, we can gain a deeper understanding of the world around us and appreciate thefundamental principles that govern our universe. As technology advances, we can expect even more exciting and innovative applications of electromagnetism in the years to come.。

第三章磁共振现象

生物组织中存在很多磁性核，如
1H
14 N
13 C
19 F 23 Na 31 P 39 K
但目前能用于临床MRI的只有氢核。影响磁共振信号强度两个因素
一是磁性核在组织中的浓度二是磁性核的相对灵敏度
第三章磁共振物理
16
四、用于磁共振成像的磁性核
O
26 H1 1 H
一个水分子
水
十个核外电子两个氢核一个氧核
25
一、微观描述
2、旋进原子核旋进称为拉摩尔旋进（Larmor precession）
磁性核和陀螺的旋进
第三章磁共振物理
26
一、微观描述
2、旋进
核磁矩TI在磁I 力B0矩T
作用下绕
磁场 B
0旋进
T I B0sin
dLI LI sin d
根据角动量定理
1 2 1 2
Iz
1 2
gI

N

1 2
gI

N
第三章磁共振物理
13
三、物质的磁性
物质构成分子或原子宏观上物质有可能表现
顺磁性逆磁性
外逆磁性
磁
场顺磁物质
作
用下
铁磁性物质
附加磁场与外磁场方向相反
附加磁场与外磁场方向相同
附加磁场与外磁场方向相同强度远大于外磁场
铁、钴、镍
第三章磁共振物理
Ni Ne Ei kT
N i表示第i个能级上的核数 Ei为该能级上的能量
N为系统的总核数
T为绝对温度
k=1.381×10-23 J/K为玻尔兹曼常数
处于热平衡状态的高低能级核数之比为

费曼物理学讲义英文版

费曼物理学讲义英文版Feynman Lectures on PhysicsPhysics is a fascinating and complex field of study that has captivated the minds of countless individuals throughout history. One of the most renowned and influential figures in the world of physics is Richard Feynman, whose legendary lectures on the subject have become a cornerstone of scientific education. The Feynman Lectures on Physics, originally published in the 1960s, are a testament to Feynman's extraordinary ability to explain complex concepts in a clear and engaging manner.Feynman's approach to teaching physics was unique and groundbreaking. Rather than simply reciting facts and formulas, he emphasized the importance of understanding the underlying principles and the interconnectedness of various physical phenomena. His lectures were not merely a collection of dry, theoretical discussions, but rather a dynamic exploration of the natural world, where he encouraged his students to question, experiment, and discover.One of the key strengths of the Feynman Lectures on Physics isFeynman's ability to simplify complex ideas without sacrificing their depth or accuracy. He had a remarkable talent for breaking down seemingly daunting concepts into their most fundamental components, making them accessible to a wide range of audiences, from seasoned physicists to curious laypeople.Throughout the lectures, Feynman's infectious enthusiasm and genuine love for the subject matter shine through. He was not content to merely transmit information; instead, he sought to ignite a passion for learning and discovery in his students. His lectures were peppered with thought-provoking analogies, engaging demonstrations, and a keen sense of humor, all of which served to make the study of physics more engaging and enjoyable.One of the most notable aspects of the Feynman Lectures on Physics is the breadth and depth of the topics covered. From the fundamental laws of mechanics and thermodynamics to the intricacies of quantum mechanics and the mysteries of the universe, Feynman's lectures provide a comprehensive and authoritative exploration of the physical world. Each lecture is meticulously crafted, with Feynman guiding the reader through complex ideas step by step, building a solid foundation of understanding.Perhaps one of the most striking features of Feynman's teaching style is his ability to make the seemingly abstract and theoreticalconcepts of physics come alive. He often used practical examples and thought experiments to illustrate the principles he was discussing, helping his students to visualize and internalize the material. This approach not only made the lectures more engaging but also reinforced the relevance and applicability of physics in the real world.Another remarkable aspect of the Feynman Lectures on Physics is the way in which Feynman challenged his students to think critically and independently. He did not simply present information as a set of immutable facts; instead, he encouraged his students to question assumptions, to explore alternative perspectives, and to develop their own analytical and problem-solving skills. This emphasis on active learning and critical thinking has been a hallmark of Feynman's legacy, inspiring generations of physicists and scientists to approach their work with a similar sense of curiosity and intellectual rigor.The Feynman Lectures on Physics have become a revered and influential work in the field of physics education. They have been translated into numerous languages and are widely used as a reference and teaching resource around the world. The lectures have not only shaped the understanding and appreciation of physics for countless individuals, but they have also served as a model for effective and engaging scientific communication.In conclusion, the Feynman Lectures on Physics are a testament to the genius and pedagogical prowess of Richard Feynman. Through his innovative teaching methods, his deep understanding of physical principles, and his unwavering dedication to inspiring curiosity and discovery, Feynman has left an indelible mark on the field of physics and the way it is taught and learned. The lectures continue to be a source of inspiration and enlightenment for students and scholars alike, and their enduring legacy is a testament to the transformative power of knowledge and the joy of scientific exploration.。

物理学专业英语

华中师范大学物理学院物理学专业英语仅供内部学习参考！2014一、课程的任务和教学目的通过学习《物理学专业英语》，学生将掌握物理学领域使用频率较高的专业词汇和表达方法，进而具备基本的阅读理解物理学专业文献的能力。

通过分析《物理学专业英语》课程教材中的范文，学生还将从英语角度理解物理学中个学科的研究内容和主要思想，提高学生的专业英语能力和了解物理学研究前沿的能力。

培养专业英语阅读能力，了解科技英语的特点，提高专业外语的阅读质量和阅读速度；掌握一定量的本专业英文词汇，基本达到能够独立完成一般性本专业外文资料的阅读；达到一定的笔译水平。

要求译文通顺、准确和专业化。

二、课程内容课程内容包括以下章节：物理学、经典力学、热力学、电磁学、光学、原子物理、统计力学、量子力学和狭义相对论三、基本要求1.充分利用课内时间保证充足的阅读量（约1200~1500词/学时），要求正确理解原文。

2.泛读适量课外相关英文读物，要求基本理解原文主要内容。

3.掌握基本专业词汇（不少于200词）。

4.应具有流利阅读、翻译及赏析专业英语文献，并能简单地进行写作的能力。

四、参考书目录1 Physics 物理学 (1)Introduction to physics (1)Classical and modern physics (2)Research fields (4)V ocabulary (7)2 Classical mechanics 经典力学 (10)Introduction (10)Description of classical mechanics (10)Momentum and collisions (14)Angular momentum (15)V ocabulary (16)3 Thermodynamics 热力学 (18)Introduction (18)Laws of thermodynamics (21)System models (22)Thermodynamic processes (27)Scope of thermodynamics (29)V ocabulary (30)4 Electromagnetism 电磁学 (33)Introduction (33)Electrostatics (33)Magnetostatics (35)Electromagnetic induction (40)V ocabulary (43)5 Optics 光学 (45)Introduction (45)Geometrical optics (45)Physical optics (47)Polarization (50)V ocabulary (51)6 Atomic physics 原子物理 (52)Introduction (52)Electronic configuration (52)Excitation and ionization (56)V ocabulary (59)7 Statistical mechanics 统计力学 (60)Overview (60)Fundamentals (60)Statistical ensembles (63)V ocabulary (65)8 Quantum mechanics 量子力学 (67)Introduction (67)Mathematical formulations (68)Quantization (71)Wave-particle duality (72)Quantum entanglement (75)V ocabulary (77)9 Special relativity 狭义相对论 (79)Introduction (79)Relativity of simultaneity (80)Lorentz transformations (80)Time dilation and length contraction (81)Mass-energy equivalence (82)Relativistic energy-momentum relation (86)V ocabulary (89)正文标记说明：蓝色Arial字体（例如energy）：已知的专业词汇蓝色Arial字体加下划线（例如electromagnetism）：新学的专业词汇黑色Times New Roman字体加下划线（例如postulate）：新学的普通词汇1 Physics 物理学1 Physics 物理学Introduction to physicsPhysics is a part of natural philosophy and a natural science that involves the study of matter and its motion through space and time, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Over the last two millennia, physics was a part of natural philosophy along with chemistry, certain branches of mathematics, and biology, but during the Scientific Revolution in the 17th century, the natural sciences emerged as unique research programs in their own right. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry,and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms of other sciences, while opening new avenues of research in areas such as mathematics and philosophy.Physics also makes significant contributions through advances in new technologies that arise from theoretical breakthroughs. For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products which have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus.Core theoriesThough physics deals with a wide variety of systems, certain theories are used by all physicists. Each of these theories were experimentally tested numerous times and found correct as an approximation of nature (within a certain domain of validity).For instance, the theory of classical mechanics accurately describes the motion of objects, provided they are much larger than atoms and moving at much less than the speed of light. These theories continue to be areas of active research, and a remarkable aspect of classical mechanics known as chaos was discovered in the 20th century, three centuries after the original formulation of classical mechanics by Isaac Newton (1642–1727) 【艾萨克·牛顿】.University PhysicsThese central theories are important tools for research into more specialized topics, and any physicist, regardless of his or her specialization, is expected to be literate in them. These include classical mechanics, quantum mechanics, thermodynamics and statistical mechanics, electromagnetism, and special relativity.Classical and modern physicsClassical mechanicsClassical physics includes the traditional branches and topics that were recognized and well-developed before the beginning of the 20th century—classical mechanics, acoustics, optics, thermodynamics, and electromagnetism.Classical mechanics is concerned with bodies acted on by forces and bodies in motion and may be divided into statics (study of the forces on a body or bodies at rest), kinematics (study of motion without regard to its causes), and dynamics (study of motion and the forces that affect it); mechanics may also be divided into solid mechanics and fluid mechanics (known together as continuum mechanics), the latter including such branches as hydrostatics, hydrodynamics, aerodynamics, and pneumatics.Acoustics is the study of how sound is produced, controlled, transmitted and received. Important modern branches of acoustics include ultrasonics, the study of sound waves of very high frequency beyond the range of human hearing; bioacoustics the physics of animal calls and hearing, and electroacoustics, the manipulation of audible sound waves using electronics.Optics, the study of light, is concerned not only with visible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light.Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy.Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamics with moving charges, and magnetostatics with magnetic poles at rest.Modern PhysicsClassical physics is generally concerned with matter and energy on the normal scale of1 Physics 物理学observation, while much of modern physics is concerned with the behavior of matter and energy under extreme conditions or on the very large or very small scale.For example, atomic and nuclear physics studies matter on the smallest scale at which chemical elements can be identified.The physics of elementary particles is on an even smaller scale, as it is concerned with the most basic units of matter; this branch of physics is also known as high-energy physics because of the extremely high energies necessary to produce many types of particles in large particle accelerators. On this scale, ordinary, commonsense notions of space, time, matter, and energy are no longer valid.The two chief theories of modern physics present a different picture of the concepts of space, time, and matter from that presented by classical physics.Quantum theory is concerned with the discrete, rather than continuous, nature of many phenomena at the atomic and subatomic level, and with the complementary aspects of particles and waves in the description of such phenomena.The theory of relativity is concerned with the description of phenomena that take place in a frame of reference that is in motion with respect to an observer; the special theory of relativity is concerned with relative uniform motion in a straight line and the general theory of relativity with accelerated motion and its connection with gravitation.Both quantum theory and the theory of relativity find applications in all areas of modern physics.Difference between classical and modern physicsWhile physics aims to discover universal laws, its theories lie in explicit domains of applicability. Loosely speaking, the laws of classical physics accurately describe systems whose important length scales are greater than the atomic scale and whose motions are much slower than the speed of light. Outside of this domain, observations do not match their predictions.Albert Einstein【阿尔伯特·爱因斯坦】contributed the framework of special relativity, which replaced notions of absolute time and space with space-time and allowed an accurate description of systems whose components have speeds approaching the speed of light.Max Planck【普朗克】, Erwin Schrödinger【薛定谔】, and others introduced quantum mechanics, a probabilistic notion of particles and interactions that allowed an accurate description of atomic and subatomic scales.Later, quantum field theory unified quantum mechanics and special relativity.General relativity allowed for a dynamical, curved space-time, with which highly massiveUniversity Physicssystems and the large-scale structure of the universe can be well-described. General relativity has not yet been unified with the other fundamental descriptions; several candidate theories of quantum gravity are being developed.Research fieldsContemporary research in physics can be broadly divided into condensed matter physics; atomic, molecular, and optical physics; particle physics; astrophysics; geophysics and biophysics. Some physics departments also support research in Physics education.Since the 20th century, the individual fields of physics have become increasingly specialized, and today most physicists work in a single field for their entire careers. "Universalists" such as Albert Einstein (1879–1955) and Lev Landau (1908–1968)【列夫·朗道】, who worked in multiple fields of physics, are now very rare.Condensed matter physicsCondensed matter physics is the field of physics that deals with the macroscopic physical properties of matter. In particular, it is concerned with the "condensed" phases that appear whenever the number of particles in a system is extremely large and the interactions between them are strong.The most familiar examples of condensed phases are solids and liquids, which arise from the bonding by way of the electromagnetic force between atoms. More exotic condensed phases include the super-fluid and the Bose–Einstein condensate found in certain atomic systems at very low temperature, the superconducting phase exhibited by conduction electrons in certain materials,and the ferromagnetic and antiferromagnetic phases of spins on atomic lattices.Condensed matter physics is by far the largest field of contemporary physics.Historically, condensed matter physics grew out of solid-state physics, which is now considered one of its main subfields. The term condensed matter physics was apparently coined by Philip Anderson when he renamed his research group—previously solid-state theory—in 1967. In 1978, the Division of Solid State Physics of the American Physical Society was renamed as the Division of Condensed Matter Physics.Condensed matter physics has a large overlap with chemistry, materials science, nanotechnology and engineering.Atomic, molecular and optical physicsAtomic, molecular, and optical physics (AMO) is the study of matter–matter and light–matter interactions on the scale of single atoms and molecules.1 Physics 物理学The three areas are grouped together because of their interrelationships, the similarity of methods used, and the commonality of the energy scales that are relevant. All three areas include both classical, semi-classical and quantum treatments; they can treat their subject from a microscopic view (in contrast to a macroscopic view).Atomic physics studies the electron shells of atoms. Current research focuses on activities in quantum control, cooling and trapping of atoms and ions, low-temperature collision dynamics and the effects of electron correlation on structure and dynamics. Atomic physics is influenced by the nucleus (see, e.g., hyperfine splitting), but intra-nuclear phenomena such as fission and fusion are considered part of high-energy physics.Molecular physics focuses on multi-atomic structures and their internal and external interactions with matter and light.Optical physics is distinct from optics in that it tends to focus not on the control of classical light fields by macroscopic objects, but on the fundamental properties of optical fields and their interactions with matter in the microscopic realm.High-energy physics (particle physics) and nuclear physicsParticle physics is the study of the elementary constituents of matter and energy, and the interactions between them.In addition, particle physicists design and develop the high energy accelerators,detectors, and computer programs necessary for this research. The field is also called "high-energy physics" because many elementary particles do not occur naturally, but are created only during high-energy collisions of other particles.Currently, the interactions of elementary particles and fields are described by the Standard Model.●The model accounts for the 12 known particles of matter (quarks and leptons) thatinteract via the strong, weak, and electromagnetic fundamental forces.●Dynamics are described in terms of matter particles exchanging gauge bosons (gluons,W and Z bosons, and photons, respectively).●The Standard Model also predicts a particle known as the Higgs boson. In July 2012CERN, the European laboratory for particle physics, announced the detection of a particle consistent with the Higgs boson.Nuclear Physics is the field of physics that studies the constituents and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those in nuclear medicine and magnetic resonance imaging, ion implantation in materials engineering, and radiocarbon dating in geology and archaeology.University PhysicsAstrophysics and Physical CosmologyAstrophysics and astronomy are the application of the theories and methods of physics to the study of stellar structure, stellar evolution, the origin of the solar system, and related problems of cosmology. Because astrophysics is a broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.The discovery by Karl Jansky in 1931 that radio signals were emitted by celestial bodies initiated the science of radio astronomy. Most recently, the frontiers of astronomy have been expanded by space exploration. Perturbations and interference from the earth's atmosphere make space-based observations necessary for infrared, ultraviolet, gamma-ray, and X-ray astronomy.Physical cosmology is the study of the formation and evolution of the universe on its largest scales. Albert Einstein's theory of relativity plays a central role in all modern cosmological theories. In the early 20th century, Hubble's discovery that the universe was expanding, as shown by the Hubble diagram, prompted rival explanations known as the steady state universe and the Big Bang.The Big Bang was confirmed by the success of Big Bang nucleo-synthesis and the discovery of the cosmic microwave background in 1964. The Big Bang model rests on two theoretical pillars: Albert Einstein's general relativity and the cosmological principle (On a sufficiently large scale, the properties of the Universe are the same for all observers). Cosmologists have recently established the ΛCDM model (the standard model of Big Bang cosmology) of the evolution of the universe, which includes cosmic inflation, dark energy and dark matter.Current research frontiersIn condensed matter physics, an important unsolved theoretical problem is that of high-temperature superconductivity. Many condensed matter experiments are aiming to fabricate workable spintronics and quantum computers.In particle physics, the first pieces of experimental evidence for physics beyond the Standard Model have begun to appear. Foremost among these are indications that neutrinos have non-zero mass. These experimental results appear to have solved the long-standing solar neutrino problem, and the physics of massive neutrinos remains an area of active theoretical and experimental research. Particle accelerators have begun probing energy scales in the TeV range, in which experimentalists are hoping to find evidence for the super-symmetric particles, after discovery of the Higgs boson.Theoretical attempts to unify quantum mechanics and general relativity into a single theory1 Physics 物理学of quantum gravity, a program ongoing for over half a century, have not yet been decisively resolved. The current leading candidates are M-theory, superstring theory and loop quantum gravity.Many astronomical and cosmological phenomena have yet to be satisfactorily explained, including the existence of ultra-high energy cosmic rays, the baryon asymmetry, the acceleration of the universe and the anomalous rotation rates of galaxies.Although much progress has been made in high-energy, quantum, and astronomical physics, many everyday phenomena involving complexity, chaos, or turbulence are still poorly understood. Complex problems that seem like they could be solved by a clever application of dynamics and mechanics remain unsolved; examples include the formation of sand-piles, nodes in trickling water, the shape of water droplets, mechanisms of surface tension catastrophes, and self-sorting in shaken heterogeneous collections.These complex phenomena have received growing attention since the 1970s for several reasons, including the availability of modern mathematical methods and computers, which enabled complex systems to be modeled in new ways. Complex physics has become part of increasingly interdisciplinary research, as exemplified by the study of turbulence in aerodynamics and the observation of pattern formation in biological systems.Vocabulary★natural science 自然科学academic disciplines 学科astronomy 天文学in their own right 凭他们本身的实力intersects相交，交叉interdisciplinary交叉学科的，跨学科的★quantum 量子的theoretical breakthroughs 理论突破★electromagnetism 电磁学dramatically显著地★thermodynamics热力学★calculus微积分validity★classical mechanics 经典力学chaos 混沌literate 学者★quantum mechanics量子力学★thermodynamics and statistical mechanics热力学与统计物理★special relativity狭义相对论is concerned with 关注，讨论，考虑acoustics 声学★optics 光学statics静力学at rest 静息kinematics运动学★dynamics动力学ultrasonics超声学manipulation 操作，处理，使用University Physicsinfrared红外ultraviolet紫外radiation辐射reflection 反射refraction 折射★interference 干涉★diffraction 衍射dispersion散射★polarization 极化，偏振internal energy 内能Electricity电性Magnetism 磁性intimate 亲密的induces 诱导，感应scale尺度★elementary particles基本粒子★high-energy physics 高能物理particle accelerators 粒子加速器valid 有效的，正当的★discrete离散的continuous 连续的complementary 互补的★frame of reference 参照系★the special theory of relativity 狭义相对论★general theory of relativity 广义相对论gravitation 重力，万有引力explicit 详细的，清楚的★quantum field theory 量子场论★condensed matter physics凝聚态物理astrophysics天体物理geophysics地球物理Universalist博学多才者★Macroscopic宏观Exotic奇异的★Superconducting 超导Ferromagnetic铁磁质Antiferromagnetic 反铁磁质★Spin自旋Lattice 晶格，点阵，网格★Society社会，学会★microscopic微观的hyperfine splitting超精细分裂fission分裂，裂变fusion熔合，聚变constituents成分，组分accelerators加速器detectors 检测器★quarks夸克lepton 轻子gauge bosons规范玻色子gluons胶子★Higgs boson希格斯玻色子CERN欧洲核子研究中心★Magnetic Resonance Imaging磁共振成像，核磁共振ion implantation 离子注入radiocarbon dating放射性碳年代测定法geology地质学archaeology考古学stellar 恒星cosmology宇宙论celestial bodies 天体Hubble diagram 哈勃图Rival竞争的★Big Bang大爆炸nucleo-synthesis核聚合，核合成pillar支柱cosmological principle宇宙学原理ΛCDM modelΛ-冷暗物质模型cosmic inflation宇宙膨胀1 Physics 物理学fabricate制造，建造spintronics自旋电子元件，自旋电子学★neutrinos 中微子superstring 超弦baryon重子turbulence湍流，扰动，骚动catastrophes突变，灾变，灾难heterogeneous collections异质性集合pattern formation模式形成University Physics2 Classical mechanics 经典力学IntroductionIn physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces. The study of the motion of bodies is an ancient one, making classical mechanics one of the oldest and largest subjects in science, engineering and technology.Classical mechanics describes the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies. Besides this, many specializations within the subject deal with gases, liquids, solids, and other specific sub-topics.Classical mechanics provides extremely accurate results as long as the domain of study is restricted to large objects and the speeds involved do not approach the speed of light. When the objects being dealt with become sufficiently small, it becomes necessary to introduce the other major sub-field of mechanics, quantum mechanics, which reconciles the macroscopic laws of physics with the atomic nature of matter and handles the wave–particle duality of atoms and molecules. In the case of high velocity objects approaching the speed of light, classical mechanics is enhanced by special relativity. General relativity unifies special relativity with Newton's law of universal gravitation, allowing physicists to handle gravitation at a deeper level.The initial stage in the development of classical mechanics is often referred to as Newtonian mechanics, and is associated with the physical concepts employed by and the mathematical methods invented by Newton himself, in parallel with Leibniz【莱布尼兹】, and others.Later, more abstract and general methods were developed, leading to reformulations of classical mechanics known as Lagrangian mechanics and Hamiltonian mechanics. These advances were largely made in the 18th and 19th centuries, and they extend substantially beyond Newton's work, particularly through their use of analytical mechanics. Ultimately, the mathematics developed for these were central to the creation of quantum mechanics.Description of classical mechanicsThe following introduces the basic concepts of classical mechanics. For simplicity, it often2 Classical mechanics 经典力学models real-world objects as point particles, objects with negligible size. The motion of a point particle is characterized by a small number of parameters: its position, mass, and the forces applied to it.In reality, the kind of objects that classical mechanics can describe always have a non-zero size. (The physics of very small particles, such as the electron, is more accurately described by quantum mechanics). Objects with non-zero size have more complicated behavior than hypothetical point particles, because of the additional degrees of freedom—for example, a baseball can spin while it is moving. However, the results for point particles can be used to study such objects by treating them as composite objects, made up of a large number of interacting point particles. The center of mass of a composite object behaves like a point particle.Classical mechanics uses common-sense notions of how matter and forces exist and interact. It assumes that matter and energy have definite, knowable attributes such as where an object is in space and its speed. It also assumes that objects may be directly influenced only by their immediate surroundings, known as the principle of locality.In quantum mechanics objects may have unknowable position or velocity, or instantaneously interact with other objects at a distance.Position and its derivativesThe position of a point particle is defined with respect to an arbitrary fixed reference point, O, in space, usually accompanied by a coordinate system, with the reference point located at the origin of the coordinate system. It is defined as the vector r from O to the particle.In general, the point particle need not be stationary relative to O, so r is a function of t, the time elapsed since an arbitrary initial time.In pre-Einstein relativity (known as Galilean relativity), time is considered an absolute, i.e., the time interval between any given pair of events is the same for all observers. In addition to relying on absolute time, classical mechanics assumes Euclidean geometry for the structure of space.Velocity and speedThe velocity, or the rate of change of position with time, is defined as the derivative of the position with respect to time. In classical mechanics, velocities are directly additive and subtractive as vector quantities; they must be dealt with using vector analysis.When both objects are moving in the same direction, the difference can be given in terms of speed only by ignoring direction.University PhysicsAccelerationThe acceleration , or rate of change of velocity, is the derivative of the velocity with respect to time (the second derivative of the position with respect to time).Acceleration can arise from a change with time of the magnitude of the velocity or of the direction of the velocity or both . If only the magnitude v of the velocity decreases, this is sometimes referred to as deceleration , but generally any change in the velocity with time, including deceleration, is simply referred to as acceleration.Inertial frames of referenceWhile the position and velocity and acceleration of a particle can be referred to any observer in any state of motion, classical mechanics assumes the existence of a special family of reference frames in terms of which the mechanical laws of nature take a comparatively simple form. These special reference frames are called inertial frames .An inertial frame is such that when an object without any force interactions (an idealized situation) is viewed from it, it appears either to be at rest or in a state of uniform motion in a straight line. This is the fundamental definition of an inertial frame. They are characterized by the requirement that all forces entering the observer's physical laws originate in identifiable sources (charges, gravitational bodies, and so forth).A non-inertial reference frame is one accelerating with respect to an inertial one, and in such a non-inertial frame a particle is subject to acceleration by fictitious forces that enter the equations of motion solely as a result of its accelerated motion, and do not originate in identifiable sources. These fictitious forces are in addition to the real forces recognized in an inertial frame.A key concept of inertial frames is the method for identifying them. For practical purposes, reference frames that are un-accelerated with respect to the distant stars are regarded as good approximations to inertial frames.Forces; Newton's second lawNewton was the first to mathematically express the relationship between force and momentum . Some physicists interpret Newton's second law of motion as a definition of force and mass, while others consider it a fundamental postulate, a law of nature. Either interpretation has the same mathematical consequences, historically known as "Newton's Second Law":a m t v m t p F ===d )(d d dThe quantity m v is called the (canonical ) momentum . The net force on a particle is thus equal to rate of change of momentum of the particle with time.So long as the force acting on a particle is known, Newton's second law is sufficient to。

ThePhysicsofRadiology-chapter5-3 放射物理英文版教学课件

d. Fasten the dosimeter in a clamp so that its position is accurately known and can be reproduced for repeated readings. The center of the sensitive volume of the ion chamber should be at the center of the field and even with the end of the treatment cone if there is one, or else at the reference distance chosen for the calibration. Sometimes this is not possible, in which case an inverse square correction will have to be made
e. Set the timer to an appropriate value, turn on the machine, and bring it to the operating point selected in b. Open the shutter, or in the case of a cobalt unit simply turn the beam on. If the ion chamber is operated as an exposure rate measuring instrument, its reading can now be taken directly. If it is to be operated as an exposure meter, timer, settings should be chosen so that a set of readings are obtained at both relatively high scale readings (say about 3/4 scale) and relatively low scale readings. The exposure rate may then be obtained by taking differences of sets of readings to determine the slope of the "reading versus time" curve.

毕业论文目录英文版

Contents Abstract．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．1 Key words．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．1 Introduction．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．1一、History of evolution of Confucianism’s people-oriented thoughts ．．．．．．．．．2（一）Embryonic stage．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．21、Social background．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．22、Character's view．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．3（二）Formation stage．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．31、Social background．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．32、Character's view．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．3（三）Development and improving stage．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．41、Social background．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．42、Character's view．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．4（四）Maturity and transformation．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．51、Social background．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．52、Character's view．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．5二、The content and essence of Confucianism’s people-oriented thoughts．．．．．5（一）Main content of Confucianism’s people-oriented thoughts．．．．．．．．．．．．．．51、Supporting and enriching people．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．62、Respecting people．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．63、Educating people．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．74、Trusting people．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．7 （二）Essence of the Confucian ism’s people-oriented thoughts．．．．．．．．．．．．．．．8 1、Respecting the monarch and esteeming the people and emphasis on the idea that people are the foundation of a country．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．8 2、The strategy to Maintain autocratic monarchy ．．．．．．．．．．．．．．．．．．．．．．．．．．83、The moral identity to Strengthening autocratic monarchy ．．．．．．．．．．．．．．．．94、The parochialism a nd bestowal of Confu cianism’s people-oriented thoughts．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．9 三、Influences and enlightenment of Confucianism’s people-oriented thoughts．10（一）P ositive influences and negative influences of Confucianism’s people-oriented thoughts．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．101、Positive influences．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．102、Negative influences ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．11 （二）The enlightenment of Confucianism’s people-oriented thoughts in modern society．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．13 1、Keeping economic development as the central task and improving people’s living standard．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．13 2、Esteeming people and ensuring that people are the real masters of their own country．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．133、Maintaining the close tie of party and people and solving the problems concerning people’s interest．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．144、Conforming to public opinion, caring for the masses and adhering to people-oriented thought ．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．145、Coordinating the interests of all parties and promoting justice and harmony．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．15 Conclusion．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．15 Bibliography．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．16 Acknowledgements．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．18 Author Introduction．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．18 Statement．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．19。

核物理入门书籍

核物理入门书籍
以下是一些核物理入门书籍的推荐：
1. 《核物理学》（Fundamentals of Nuclear Physics）- 英文原版，这本书是核物理学中的经典教材，涵盖了从基础原理到现代研究领域的知识。

2. 《光与物质的相互作用》（Interaction of Radiation with Matter）- 这本书介绍了辐射与物质之间的相互作用，包括核
反应、核衰变等核物理的基本原理和应用。

3. 《核物理导论》（Introduction to Nuclear Physics）- 这本入
门书籍涵盖了核物理学的基本概念、核结构、核反应等内容，并介绍了现代核物理的前沿课题。

4. 《核物理原理与应用》（Principles and Applications of Nuclear Physics）- 这本书从实验和理论的角度介绍了核物理
的基本原理和应用，包括核反应、核结构、核能等内容。

5. 《核物理学》（Nuclear Physics）- 这本入门书籍系统地介
绍了核物理学的基本概念、原理和实验方法，适合初学者学习和了解核物理学的基础知识。

以上都是一些比较常用的核物理入门书籍，你可以根据自己的需求和英文水平选择合适的书籍进行学习。

另外，如果你对核物理有特定的兴趣领域，比如核能、核技术等，还可以选择专门介绍这些方面的书籍进行深入学习。

ThePhysicsofRadiology-chapter5-3 放射物理英文版教学课件

ρ is the density of the solution in kg/m3
G is the yield in number per 100 eV
Example. It is required to determine the average dose to a sample of water in a complexly shaped radiation container near a cobalt source. This is most easily done using the Fricke dosimeter. The container is filled with Fricke solution and exposed. A sample of the well-mixed irradiated solution is then placed in a quartz cuvette of 2 cm path length and its absorbance measured against the stock solution at 304 nm. Suppose the measured absorbance is 0.360. Calculate the dose.
Direct Measurement of Absorbed Dose —The Calorimeter
J 1 calories 1 Gy 1 kg 4.18 kg
1 cal 1 kg o T 3 C 2.39 10 4.18 kg 10 cal 4 o
C
5 5 R 10 2.39 10 100
Enormous dynamic range
Flexible forms

The effects of resonance scattering and dust on the UV line spectrum of radio galaxies

a r X i v :a s t r o -p h /9605009v 1 2 M a y 1996A&A manuscript no.(will be inserted by hand later)Key words:atomic processes –ISM:dust –Galaxies:cooling ﬂows,radio galaxies,galaxy formation 1.IntroductionThe strong,spatially extended,rest-frame ultraviolet emission lines observed in high redshift radio galaxies pro-vide one of the principal diagnostics in establishing the state of the interstellar medium in galaxies at early epochs.2Resonance scattering,dust and the UV spectrum of RGscattering,more susceptible to absorption.We explore the fact that any resonance line will be extremely sensitive to geometrical factors,an aspect of the problem which has so far been overlooked in modeling the UV lines.If in radio-galaxies the distant gas clouds are photoionized from the outside by partially collimated UV radiation emitted by the nucleus,the line formation process—particularly for the resonance lines—is very diﬀerent from internally ion-ized HII regions.The escape of resonance line photons is strongly inﬂuenced by the presence of spaces between the line emitting clouds.We have collected from the literature the observed line ratios for a number of high z radio-galaxies in which no contribution from any nuclear BLR is apparent.We have built a diagnostic diagram consisting of the lines CIVλ1549/Lyαvs.CIVλ1549/CIII]λ1909,in which we compare the position of the objects with photoionization models which not only consider the eﬀects of internal dust but also those of the viewing perspective—the angle be-tween the incoming ionizing radiation and the observer’s line of sight.Our concentration on the particular class of radio galaxies is purely for pragmatic reasons.It is these objects,which we presume to harbour a powerful quasar which is hidden at optical/ultraviolet wavelengths to our line of sight,which are most readily found and studied at the high redshifts where we have access to the ultraviolet spectrum from groundbased observations.Our conclusions should be equally applicable to other classes of AGN.For some objects,Lyαis observed to be fainter with respect to CIV than predicted by dust-free photoioniza-tion models.The explanation previously proposed to ex-plain the weakness of Lyαwith respect Hαor Hβhas been dust destruction of resonant Lyαphotons.This is not borne out by our calculations in which we have used arbitrary amounts of dust and found that this cannot si-multaneously weaken Lyαwhile leaving the CIV/CIII]ra-tio relatively unchanged since resonant CIV suﬀers also from dust absorption.Alternatively,by varying the pro-portions of the illuminated and the shadowed cloud faces which contribute to the observed spectrum,we are bet-ter able to match the data.geometric explanation could naturally explain that some of the brightness asymmetries noted by McCarthy et al.(1991a)on sides of the nucleus.As weﬁnd that geometry alone(with or without inter-nal dust)can in principle explain most of the speciﬁc line ratios observed(fainter Lyαcompared with either CIV or HeII),we also discuss the possibility of a patchy outer halo of neutral gas to account for the diﬀuse Lyαseen in some cases to extend much beyond the CIV emitting region and even the outermost radio lobes.Reﬂection by cold gas of the brighter Lyαemitting side of the ionized clouds would lead to a narrower proﬁle for such a dif-fuse component.Another possibility is that part of the beamed nuclear continuum and BLR radiation might be reﬂected at the wavelength of Lyαby thin matter-bounded photoionized gas at very large distances from the nucleus leading to a diﬀuse Lyαcomponent aligned with the radio axis.It appears to us that geometrical perspective eﬀects are an essential component of the interpretation of the UV spectrum of radio-galaxies whether or not dust is present. Furthermore,a spectrum in which only Lyαappears does not necessarily imply starburst activity,other lines must be observed before the existence of an HII region can be inferred.2.Data sample and modeling procedure2.1.The dataWe have constructed a data sample containing galaxies at high z for which the CIV,Lyαand,in most cases CIII], emission lines have been measured.Since very high den-sities such as those encountered in the BLR alter signiﬁ-cantly the line formation and transfer processes,we have excluded those objects which show evidence of a BLR.In Table1,we list the object names,the line ratios of inter-est to us here,the redshift and the reference to the ob-servations.The larger fraction of the data are taken from the recent thesis by van Ojik(1995)which includes ob-jects selected on the basis of a very steep radio spectrum. Probably by virtue of the radio selection,these sources populate the region of the line ratio diagram(Fig.4)with lower CIV/CIII]ratios(lower ionization parameter)than the previously published objects.The line measurements refer to the integrated emission from the object collected with a long slit aligned with the major axis.2.2.The model and its parametersThe data are compared to photoionization models com-puted using the multipurpose photoionization–shock code MAPPINGS I.The version described in Binette et al. (1993a,b)is particularly suited to the problem since it considers both the eﬀects of the observer’s position with respect to the emitting slab and the ionizing source(cf, Fig.3).We distinguish between the spectrum seen from the back and from the front of the slab.The code also considers the eﬀects of dust mixed with the ionized gas: extinction of the ionizing continuum and of the emission lines,scattering by the dust and heating by dust pho-toionization.The treatment of the escape of resonant CIV and Lyαphotons in a dusty medium is described in Ap-pendix B of Binette et al.(1993a)and is based on the results of Hummer&Kunasz(1980).The dust content of the photoionized plasma is de-scribed by the quantityµwhich is the dust-to-gas ratio of the plasma expressed in units of the solar neighbourhood dust-to-gas ratio.To specify the gas metallicity,we scale with a factor Z the solar abundance set of trace elements from Anders&Grevesse(1989).He/H is kept constant at 0.1.We generally consider the solar case with Z=1.Since the presence of dust implies depletion of refractory trace elements,we use the prescription given in Appendix A ofResonance scattering,dust and the UV spectrum of RG 3Binette et al.(1993a,hereafter BWVM3)to derive the gaseous phase abundances for any metallicity Z .The de-pletion algorithm is function of the ratio µ/Z and makes use of the depletion indices listed in Whittet (1992)for the diﬀerent metals.The calculations consider the gas pressure to be con-stant (isobaric models)and so the density behaviour with depth in the cloud is determined by the behaviour of the temperature and the ionization fraction of the gas.The ionization parameter,a measure of the excitation level of the ionized gas,is deﬁned as the quotient of the density of ionizing photons incident on the cloud and the gas density:U =∞νof νdν/hν4Resonance scattering,dust and the UV spectrum of RGTable1.Observed UV line ratios for several high z RG with not apparent broad componentAverage RG 2.0540.118McCarthy(1993)Resonance scattering,dust and the UV spectrum of RG5Fig.2.Observed and predicted UV line ratios.Filled trian-gles are the observed ratios of objects observed by diﬀerent au-thors.Open circles correspond to data taken from van Ojik’s thesis,selected on the basis of a very steep radio spectrum.The open diamond is the average radiogalaxy spectrum of Mc-Carthy (1993).Dotted lines represent models in which the front and back spectra have been summed.It is clear that high val-ues of the ionization parameter U are required to reproduce the high CIV/CIII]values observed.photons by resonance scattering in the presence of dust is the explanation for its faintness,but why does not the same process reduce CIV which is also a resonance line?Is there an alternative explanation for this selective dimming of Ly α?To answer this question,we examine the geometrical aspects of the line formation process.Each emitting cloud is approximated as a plane parallel slab which contains a fully ionized region and a partially ionized zone where low ionization species co-exist (e.g.,O 0,S +,etc)with a mix-ture of H 0and H +.In principle there can be an additional neutral zone which does not contribute to the emission line intensities (see Fig.3).In this section we consider the dust-free case.For most lines (like CIII],HeII,H β,[OIII],etc)line opacity is neg-ligible and the line is emitted isotropically with photons escaping freely in all directions.However,when the line opacity is important as it is for CIV and Ly α,line scat-tering occurs which increases the path length.Another im-portant eﬀect of large optical depths is that the line pho-ton will not escape isotropically.A resonance line photon following many scatterings must statistically escape in the direction of highest escape probability which can be shown to be the front for the photoionized slab depicted in Fig.3.In the case of Ly α,the reason is that —while Ly αpho-tons are generated more or less uniformly within theslabFig.3.Adopted slab geometry for the constant pressure pho-toionization calculations.The slab comprises a fully ionized zone and a partially ionized zone (PIZ)where H +and H 0co-exist.Beyond the PIZ we may have a region of neutral gas.(except within the PIZ)by recombination —the neutral fraction and therefore the incremental line opacity dτL /dx increases monotonically as a function of depth as discussed in more detail by BWVM3.This means that for an open geometry like that shown in Fig.3,the zone of equal es-cape probability of front vs back occurs far beyond the point where half the luminosity of Ly αis produced.For the collisionally excited CIV line,the tendency to escape from the front also exists although it is less pronounced.It arises mainly because the emissivity of CIV is larger towards the front due to the temperature gradient across the C +3zone.Note that while CIV is emitted and scat-ters within the rather limited zone containing C +3,Ly αremains subject to scattering outside the region where it is produced.While most Ly αemission is produced in the fully ionized zone,most of the line opacity occurs within the PIZ.The presence of a layer of neutral gas beyond the PIZ will increase the anisotropy of Ly αescape.The eﬀects described qualitatively above are shown in Fig.4using detailed photoionization calculations.We present the same sequence of dust-free models as in Fig.2but distinguish between the spectrum seen from the back —equivalent to observing the clouds through the PIZ —from that seen from the front —equivalent to seeing the UV irradiated side.The diﬀerences are striking:both Ly αand to a lesser extent CIV are fainter when seen from the back.The CIII]line is isotropic in the dust-free case.The fact that Ly αis more aﬀected by perspective is due to the signiﬁcant amount of neutral hydrogen (i.e.,large line opacity)in the PIZ which acts as a mirror.Although we have considered a very simpliﬁed geometry in our calcu-lations,the method nevertheless treats properly the es-sential physical eﬀects and indicates how important the viewing direction is in this open geometry.6Resonance scattering,dust and the UV spectrum ofRGFig.4.Inﬂuence of viewing geometry on the UV line ratios.The dotted line corresponds to the line spectrum seen from the back of the slab (cf,Fig 3)while the dashed line corresponds to the spectrum seen from the front (UV irradiated face).It is apparent that perspective plays a very important role on the CIV/Ly αratio.The solid line represents models obtained by summing the back and front spectra which would represent symmetric case where equal numbers of clouds are observed with shadowed and illuminated faces.Fig.4suggests that perspective eﬀects alone (without any dust )are suﬃcient to explain the weak Ly αseen in some objects.Ionization bounded calculations with U =0.1imply total hydrogen column densities (H +re-gion +PIZ)N H ∼1022cm −2(of which about 60%is ionized).Adding a modest neutral zone beyond the PIZ of ≃41021cm −2would double the CIV/Ly αratio with-out aﬀecting in any way the CIV/CIII]ratio.It seems,therefore,that a geometry where we see preferentially the ionized gas from the side of the PIZ gives us an explana-tion of the weakness of Ly α.How would this apply to the EELR of the powerful radio galaxies?In a very simpliﬁed scheme,we can imag-ine (see Fig.5)that the clouds seen from the nearside cone are seen from a direction which we approximate as the back perspective in our slab calculations while clouds on the far side would be seen from the front.The stud-ies of McCarthy et al.(1991a)which emphasized the one-sideness of the line brightness suggest that the observer with limited spatial resolution at very high z will be bi-ased towards either a back or front dominated perspective depending on whether it is the near or the farside illumi-nated cone which is intrinsically brighter.Our proposed interpretation of the high CIV/Ly αratio of some objects in Fig.4is that they correspond to the case where the brightest clouds are seen from behind.Note that,becauseof the intensity weighting,there is rather little diﬀerence between the pure front perspective and the sum of equal numbers of front-and back-clouds,a small eﬀect which is not easily distinguished from that of slightly reducing the value of U.Fig.5.Our conclusion from this section is that perspective eﬀects in an open —externally illuminated cloud —ge-ometry go a long way towards explaining the behaviour of the CIV,Ly α,CIII]line ratio diagram.It implies that,when spatially resolved spectra become available,marked asymmetries in the CIV/Ly αratio could arise when the axis of the illuminated cones forms a large angle with the sky plane.3.3.The eﬀects of internal dustThere is evidence for the existence of dust in some high z radio galaxies.The detection of 4C41.17(z =3.8)and B20902+34(z =3.5)(Chini &Kr¨u gel 1994;Dunlop et al.1994)and 8C1435+635(z =4.26)(Ivison 1995)in the mm spectral range is attributed to warm dust.Also,the IRAS galaxy F10214+4724(z =2.29)has been shown,from the far infrared ﬂux,to contain ∼108M sol of dust,although this ﬁgure may be reduced by the gravitational lensing am-pliﬁcation factor (Serjeant et al.1995).In addition,the mid-to far-infrared measurements at intermediate z are explained as emission from warm dust (Heckman,Cham-bers &Postman 1992).We should emphasize,however,that we have no direct measurement of how this dust is spatially distributed.In the event that this infrared emis-sion arises from the reprocessing of higher energy photons from the AGN by a dusty torus,it has no direct bearing on our modeling of ionized gas at tens of kpc.However,there is considerable evidence that aligned blue polarized continuum is the result of scattering of the anisotropic nu-clear radiation ﬁeld by dust (e.g.,Cimatti et al.1993).In this case it is very likely that at least some of the dust is internal to the extended line emission regions.In thisResonance scattering,dust and the UV spectrum of RG 7section we consider the eﬀects of including dust within the gas clouds which emit the UVlines.Fig.6.Eﬀects of varying the amount of internal dust as seen from the front perspective.Short dashed line corresponds to models with µ=1.0,the long-dashed to models with µ=0.3and solid line to dust free models.We illustrate the eﬀects of dust mixed with the emit-ting gas in Fig.6where we plot sequence of models which correspond to the front perspective for three diﬀerent dust-to-gas ratios:µ=0,0.3and 1.The eﬀects on the line ratios are evident.The resonance scattering suﬀered by CIV and Ly αincreases their pathlengths many times and,therefore,the probability of their being absorbed by dust grains is much higher than for CIII].In the case of Ly α,however,the geometrical thickness of the H +region exceeds greatly that of the C +3since we observe more than one stage of ionization of metals (e.g.C +2).Any reasonable parameters for the ionization structure of a photoionized slab with Z ∼1indicates that the opac-ity in Ly αgreatly exceeds that of CIV,which implies a larger pathlength increase for Ly αthan for CIV.This re-sults in relatively more Ly αabsorption by dust.This eﬀect explains how the ratio CIV/Ly αincreases somewhat with increasing µ.Dust absorption of resonant CIV on the other hand causes a comparable decrease in CIV/CIII].What is important in these results is that,even with a concentra-tion of internal dust as high as µ=1(equivalent to that in solar neighbourhood cold clouds),it is not possible to reproduce the high ratio CIV/Ly α≥1which is observed in some objects and has been attributed to dust.We em-phasize that higher amounts of dust do not change these results.For instance models with Z =µ=2do not lead to any higher Ly α/CIV ratio than the models shown in Fig.6.Fig.7.Eﬀects of perspective combined with small quantities of internal dust.The dust-free U sequences of Fig.5are re-peated in this ﬁgure.The nearly vertical dotted line with open circles corresponds to the last model with U =0.1(but with metallicity Z =0.3)in which the dust content is increased in proportion up to µ=rger quantities of dust do not produce any further increase in Ly α/CIV as seen from the back since it severely extinguishes both the CIII]and CIV lines which are produced in the front layers.When the clouds are viewed from behind,even with µ=0.3they are suﬃciently opaque that all the UV lines are severely absorbed.With τV =510−22µN H ∼5and µ=1,all of the high excitation UV lines become absorbed within the PIZ.To produce an acceptable spectrum,with-out reddened CIV/CIII]and CIV/HeII ratios,as seen from the back of an ionization bounded slab with U =0.1,we have to use much smaller amounts of dust like µ≃0.017(2%of local ISM)in models.In Fig.7,we plot the back and front sequences for such models.These can reproduce the weak Ly αobjects although this result is obtained only for the back spectrum,emphasizing that perspective is the dominant factor.It should be noted that the amount of extinction within the ionization bounded slab implied by µ=0.017(i.e.,A V ≃0.1–0.2)is consistent with the quantity of small dust grains needed to explain the ex-tremely blue continuum of the “detached”ionized cloud in PKS 2152-69(di Serego Alighieri et al.1988;Magris &Binette private communication),supposing that the con-tinuum energy distribution is the result of dust scattering of the nuclear radiation.Note that because the scattering/absorbing dust is lo-cally kinematically linked to the emission line gas,we require much smaller column densities of HI than the absorbing screen proposed by van Ojik et al.(1994)(∼1023cm −2)to explain CIV/Ly α∼1.The line widths and8Resonance scattering,dust and the UV spectrum of RGcentroids of the PIZ and of the fully ionized gas are ex-pected to be quite similar within each of the emitting clouds,the ensemble of which could have a greater‘tur-bulent’velocity dispersion.To reproduce the extreme case of the IRAS galaxy F10214+4724with CIV/Lyα∼10,we need additional neutral gas beyond the PIZ.For instance,it requires only a column density of N H0∼1.51021cm−2assuming µ=0.017.Alternatively we might consider thatµwithin the PIZ increases with depth as the degree of ionization decreases.In this case,no additional HI gas would be re-quired.If this IRAS galaxy is indeed an extreme Seyfert2 as argued by Elston et al.(1994),then a closed,dust en-shrouded geometry as proposed by BWVM3to explain the Lyman and Balmer decrements in Seyfert2would be more appropriate than the open geometry adopted here which may be applicable only to the truly extended large scale gas.It is likely that objects with unusually strong NVλ1240emission(such as in F10214+4724and TX0211-122)are cases where the NV originates predominantly from the inner NLR.A high NV/CIV ratio indicates very enriched gas which is not unexpected within the inner parts of an AGN(Hamman&Ferland1993)and is con-sistent with the lack of convincing evidence that NV is spatially resolved in any of these objects.3.4.Neutral gas mirrorsSo far we have considered the eﬀects of scattering by gas which forms part of the line emitting clouds:we refer to this as an‘intrinsic’process.Similar eﬀects could be produced by a large-scale distribution of predominantly neutral material surrounding the emitting regions:we will refer to this as the‘extrinsic’case.Any extrinsic neutral gas component with a non-negligible covering factor could aﬀect the observed spectra in a way which mimics that of the back perspective described earlier.Let us suppose that this outer material is broken up into cold gas clumps which are randomly distributed.In such a case,some Lyαphotons which leave the ionized cones will escape the re-gion through the holes between the external clumps while others will strike the neutral clumps and be immediately scattered away to escape eventually through another hole in a diﬀerent direction(see Fig.8).If observed with suf-ﬁcient spatial resolution,such a geometry would result in holes in the Lyαbrightness due to reﬂection by intervening clumps as well as diﬀuse sources corresponding to reﬂec-tion from clumps on the far side of the source.The bulk of the Lyαluminosity would be preserved but redistributed on an apparently larger scale than the true line emitting clouds.Only a more closed geometry would result in a sig-niﬁcant destruction of Lyα,assuming that the interclump space does not contain pure dust segregated from the gas phase.The reﬂection eﬃciency of clouds will,of course,de-pend strongly on the relative velocityﬁelds of the emitting and the cold regions.If the extended gas has a large scale ordered motion but small‘microturbulence’,the reﬂection eﬀects would be localized.Broad Lyαemission and con-tinuum from the AGN could,however,be scattered by any of the extranuclear clouds(see Sect.3.4.2).In gen-eral,we would expect the diﬀuse,scattered Lyαto show a narrower line than the integrated emission proﬁle.We will review the observational evidence for the ex-istence of such large scale mirrors.3.4.1.The radio galaxy PKS2104-242PKS2104-242(McCarthy et al.1990b)shows very ex-tended emission lines of Lyα,CIV and HeII associated with continuum knots which lie between the radio lobes and are aligned with the radio axis.The Lyαimage shows emission resolved into three distinct clumps,two of them corresponding roughly with the two continuum knots.In addition,there appears to be a low surface brightness halo of emission surrounding the entire object.Is this halo a consequence of reﬂection by neutral material of either Lyαemission or of the intense nuclear continuum,or are these photons emitted locally by H+recombination?A way of discriminating between these two possibilities is to look for the detection of any other emission line in the halo.If Lyαis the result of reﬂection by cold HI,there will be no other lines(except possibly resonant MgII).If it is instead produced by recombination,other lines should be detected in the rest-frame optical band like Hα,[OIII]λ5007,etc. Fig.8.The extrinsic case.Neutral material external to the ion-ized regions can strongly inﬂuence the appearance of the object in Lyα.In thisﬁgure,the neutral clumps(black clouds)cover a signiﬁcant fraction of the ionized regions(grey+black clouds). The solid arrows represent Lyαphotons emitted directly in the ionized regions.Dashed arrows represent Lyαphotons that af-ter striking neutral clumps are reﬂected in other directions. The reﬂection by the neutral H atoms is so eﬀective that the dust has little chance to interact with the photons before they ﬁnd a hole to escape.Resonance scattering,dust and the UV spectrum of RG93.4.2.The radiogalaxy3C294From images of this object,McCarthy et al.(1990a)re-port the existence of Lyαemission extending over a region covering170kpc.The Lyαemission is elongated and well aligned with the inner radio-source.An intriguing aspect of the observations is the one-sidedness of the CIV emis-sion(obtained with an long slit aligned with the axis of elongation).The decreasing linewidth of Lyαon the side where CIV is absent(South)suggests to us the possibility that Lyαin the south corresponds to scattered continuum and BLR Lyαphotons by HI clumps lying along this di-rection provided the ionizing radiation has already been reprocessed(ﬁltered out)within the nuclear regions into NLR or BLR emission.Failing that(scattering by HI clumps),an alternative possibility resides in very thin matter-bounded photoion-ized sheets of gas which can be very eﬃcient at reﬂecting the intense(beamed)nuclear continuum as well as BLR Lyαphotons.Due to its large scattering cross section, very small column depths of H0(a trace specie within the ionized phase)are suﬃcient to scatter eﬀectively the im-pingingﬂux within the core of the Lyαthermal proﬁle. If we suppose the existence within the cone of ionization of the radio-galaxy of a population of clouds of similar physical conditions to that thought to apply to Lyαforest clouds,the energy reﬂected due to resonant scattering by HI typically exceeds that generated within the clouds by reprocessing of the ionizing radiation(i.e.by recombina-tion).In eﬀect,adopting N H0=1013.8cm−2as a typi-cal column density of such cloud,we derive an equivalent width in absorption(i.e.the scattered intensity)of EW absLyα≈0.151With these parameters,the total column density is given by N H=N H+≈2.3104N H0.expected to increase up to8times the Lyαemitted by re-combination.To account for the observed FWHM<∼1000 km s−1in3C294(South),one most rely on a turbulent velocityﬁeld for the the Lyαclouds.We ought to consider seriously the possibility that Lyαon the southern knot of3C294corresponds to large scale scattered light by either HI or even ionized gas unless other bonaﬁde emission lines were detected.So far,no other lines than Lyαare observed which is consistent with our suggestion.The only certain way of discriminating be-tween reﬂection and in situ emission would be the detec-tion at this radius of any non-resonance line in either the optical([OII],[OIII],Hβetc.)or the UV(CII],CIII]).To conclude,we believe that HII regions or starbursts should not be considered the default emission mechanism in cases where only Lyαis present,especially along the axis where the AGN supposedly collimates its intense nuclear contin-uum+Lyα(BLR)light.3.4.3.Lyαabsorption in0943-242The radio galaxy0943-242shows a Lyαproﬁle with sev-eral absorption features which cover the whole of spatial extent of the Lyαemission(R¨o ttgering et al.1995).The strongest of the absorbers is at least as extended spatially as the emitting region(∼13kpc)and its HI column den-sity is1019cm−2.The absorption line is blue-shifted by 250km s−1with respect to the emission peak.The‘screen’is kinematically distinct from the emitting gas and there-fore clearly external to the emitting clouds).This is a clear demonstration that HI screens—or mirrors depending on the perspective—exist on galaxy scales at these early epochs.From Fig.5of R¨o ttgering et al.,we estimate that this cloud would reﬂect∼30%of the Lyα.Thicker clouds could exist around other objects but would be hard to detect when only the faint wings at the extremities of the emission proﬁle were transmitted.In the case of0943-242,even if the screen contained dust,its eﬀects would be negligible.The reason,as stated before,is that Lyαphotons(seen by the cloud)are incident from the exterior and will be very eﬀectively scattered away before being absorbed by the dust.Even the photons getting through (i.e.,without any scattering)to us because they are suﬃ-ciently far in the wings of the proﬁle would not see much dust in this particular cloud.With such low column densi-ties,τV∼510−22µN H=7.510−5forµ=0.015and0.005 forµ=1.Much thicker clouds may result in some non-negligible extinction but again this does not arise because of the multiple scattering of Lyα.4.ConclusionsIf the large-scale extended emission line regions(EELR) in radio galaxies are photoionized predominantly by the collimated UV radiation emitted by a hidden AGN,the line emission and transfer processes are characterizedby。

电动力学导论格里菲斯英文版

电动力学导论格里菲斯英文版Alright, let's dive into the world of electrodynamics with a casual approach!You know, when you start thinking about electricity and magnetism, it's like opening a door to a whole new realm of wonders. The concept of force fields, how charges interact at a distance, it's all fascinating. And when you delve deeper into Griffith's book, it all starts to make sense.One thing that really stands out is how he explains Maxwell's equations. Not just the mathematical jargon, but the real-world implications. It's like he's taking you on a journey through the fabric of space and time, showing you how electromagnetic waves travel and how they're all connected.And then, there's the part about electric circuits. Oh, the joy of Ohm's law and Kirchhoff's rules! It's like solving a puzzle, trying to figure out how the currentflows and where the voltage drops. It's both challenging and rewarding when you finally get it.But wait, there's more! Electromagnetic induction, motors, generators, all these things start to make sense when you understand how magnetic fields can induce electric currents. It's like magic, but with science behind it.And let's not forget about the applications. From radio waves to microwaves, from MRI machines to particle.。

Cotunneling Transport and Quantum Phase Transitions in Coupled Josephson-Junction Chains wi

a r X i v :c o n d -m a t /9806365v 2 [c o n d -m a t .m e s -h a l l ] 26 S e p 1998Cotunneling Transport and Quantum Phase Transitions in CoupledJosephson-Junction Chains with Charge FrustrationMahn-Soo Choi 1,M.Y.Choi 2,Taeseung Choi 1and Sung-Ik Lee 11Department of Physics,Pohang University of Science and Technology,Pohang 790-784,Korea2Department of Physics and Center for Theoretical Physics,Seoul National University,Seoul 151-742,Korea(To appear in Phys.Rev.Lett.;cond-mat/9806365)We investigate the quantum phase transitions in two capacitively coupled chains of ultra-small Josephson-junctions,where the particle-hole symmetry is broken by the gate voltage applied to each superconducting island.Near the maximal-frustration line,cotunneling of the particles along the two chains is shown to play a major role in the transport and to drive a quantum phase transition out of the charge-density wave insulator,as the Josephson-coupling energy is increased.We also argue brieﬂy that slightly oﬀthe symmetry line,the universality class of the transition remains the same as that right on the line,being driven by the particle-hole pairs.PACS numbers:74.50.+r,67.40.Db,73.23.HkSystems of ultra-small tunnel junctions composed of metallic or superconducting electrodes have been the source of a great number of experimental and theoret-ical works [1].Single charge (electron or Cooper pair)tunneling observed in those systems demonstrates the remarkable eﬀects of Coulomb blockade.Especially,in Josephson-junction arrays,the charging energy in competition with the Josephson-coupling energy further brings about the noble eﬀects of quantum ﬂuctuations,which induce quantum phase transitions at zero temper-ature [2].Very recently,another fascinating manifesta-tion of Coulomb blockade has been revealed in capac-itively coupled one-dimensional (1D)arrays of metallic tunnel junctions [3,4]:In such coupled chains,the ma-jor transport along both chains occurs via cotunneling of the electron-hole pairs,which is a quantum mechanical process through an intermediate virtual state.Such a co-tunneling transport leads to the interesting phenomenon of the current mirror.In capacitively coupled Josephson-junction chains,the counterpart of the electron-hole pair is the particle-hole pair,i.e.,the pair of an excess and a deﬁcit in Cooper pairs across the two chains.Such particle-holes pairs,combined with the quantum ﬂuctuations,have been pro-posed to drive the insulator-to-superconductor transition [5].Here it should be noticed that the particle-hole pair is stable only near the particle-hole symmetry line;far away from the symmetry line,it does not make the low-est charging-energy conﬁguration anymore.Moreover,in a single chain of Josephson junctions,breaking the particle-hole symmetry (by applying a gate voltage)is known to change immediately the universality class of the transition [6,7].Therefore,it is necessary to ﬁnd another relevant cotunneling process,if any,oﬀthe particle-hole symmetry line and to examine how the transitions change in coupled Josephson-junction chains.As an attempt toward that goal,we investigate in this paper the quantum phase transitions in two chainsof ultra-small Josephson-junctions,coupled capacitively with each other.The particle-hole symmetry is broken by the gate voltage applied to each superconducting island;the resulting induced charge introduces frustration to the system.Near the maximal-frustration line,cotunneling of the particles along the two chains is found to play a major role in the transport and to drive a quantum phase transition out of the charge-density wave (CDW)insula-tor,as the Josephson-coupling energy is increased.We also argue that slightly oﬀthe symmetry line,the uni-versality class of the transition remains the same as that right on the line,i.e.,a Berezinskii-Kosterlitz-Thouless (BKT)transition [8],driven by the particle-hole pairs.We consider two 1D arrays,i.e.,chains of Joseph-son junctions,each of which is characterized by the Josephson coupling energy E J and the charging ener-gies E 0≡e 2/2C 0and E 1≡e 2/2C 1,associated with the self-capacitance C 0and the junction capacitance C 1,respectively (see Fig.1).The two chains are coupled with each other via the capacitance C I ,with which the electrostatic energy E I ≡e 2/2C I is associated,while no Cooper-pair tunneling is allowed between the two chains [9].The intra-chain capacitances are assumed to be so small (E J ≪E 0,E 1)that,without the coupling,each chain would be in the insulating phase [10].We are interested in the limit where the coupling capacitance is suﬃciently large compared with the intra-chain capaci-tances,C I ≫C 0,C 1,i.e.,E I ≪E 0,E 1[see Eq.(4)be-low].On each superconducting island,external gate volt-age V g is applied,and accordingly,the external charge n g ≡C 0V g /2e is induced,with e being the electric charge.The external charge n g breaks the particle-hole symme-try of the system,introducing charge frustration.We restrict our discussion to two regions:near the particle-hole symmetry line (|n g −N |≪1/4with N integer)and near the maximal-frustration line (|n g −N −1/2|≪1/4),where the properties of the system are severely diﬀerent.We further note the invariance with respect to the sub-1stitution n g→n g+1,and take N=0without loss ofgenerality.The Hamiltonian describing the system is given by H=2e2 ℓ,ℓ′;x,x′[nℓ(x)−n g]C−1ℓℓ′(x,x′)[nℓ′(x′)−n g]−E J ℓ,x cos[φℓ(x)−φℓ(x+1)],(1)where the number nℓ(x)of the Cooper pairs and the phaseφℓ(x)of the superconducting order parameter at site x on theℓth chain(ℓ=1,2)are quantum-mechanically conjugate variables:[nℓ(x),φℓ(x′)]= iδℓℓ′δxx′.The capacitance matrix C in Eq.(1)can be written in the block form:Cℓℓ′(x,x′)≡C(x,x′) 1001 +δx,x′C I 1−1−11 (2) with the intra-chain capacitance matrixC(x,x′)≡C0δxx′+C1[2δxx′−δx,x′+1−δx,x′−1]. For simplicity,we keep only the on-site and the nearest neighbor interactions between the charges(i.e.,C1/C0 1)although this is not essential in the subsequent dis-cussion(as long as the interaction range isﬁnite).With the block form of the capacitance matrix in Eq.(2),the Hamiltonian can be conveniently expressed as the sumH=H0C+H1C+H J(3) with the componentsH0C≡U0 x[n+(x)−2n g]2+V0 x[n−(x)]2 H1C≡U1 x[n+(x)−2n g][n+(x+1)−2n g]+V1 x n−(x)n−(x+1)(4) H J≡−E J ℓ,x cos[φℓ(x)−φℓ(x+1)],where n±(x)≡n1(x)±n2(x)and the coupling strengths are given by U0≃2E0,U1≃4(C1/C0)E0,V0≃E I,and V1≃(C1/C I)E I.The on-site charging energy term of the Hamiltonian H0C in Eq.(4)reveals clearly the crucial diﬀerence be-tween the charge conﬁgurations in the system near the maximal-frustration line n g=1/2and those near the particle-hole symmetry line n g=0.In the former region (|n g−1/2|≪1),the charge conﬁgurations which do not satisfy the condition n+(x)=1(for all x)have a huge excitation gap of the order of E0.(Note that we are in-terested in the parameter regime E I,E J≪E0,E1.)Fur-thermore,the ground states of H0C,separated from the excited states by the gap of the order of E I,have two-fold degeneracy for each x,corresponding to n−(x)=±1. This degeneracy is lifted as the Josephson-coupling en-ergy E J is turned on.As a result,it is convenient inthis case to work within the reduced Hilbert space E d, where n+(x)=0and n−(x)=±1for each x.In the latter region(|n g|≪1/4),on the other hand,the low-energy charge conﬁguration should satisfy the condition n+(x)=0for all x.Unlike the former case,the groundstate of H0C is non-degenerate and forms a Mott insu-lator characterized by n1(x)=n2(x)=0for all x.As E J is turned on,the ground state of H0C is mixed with the states with n−(x)=±2.Accordingly,the relevant reduced Hilbert space is given by E s,where n+(x)=0 and n−(x)=0,±2for all x(see also Ref.[5]).Weﬁrst consider the region near the maximal-frustration lines,where we project the Hamiltonian Eq.(1)onto E d,and analyze the properties of the sys-tem near the maximal-frustration line(|n g−1/2|≪1/4), based on the resulting eﬀective Hamiltonian.Given the projection operator P onto E d,the eﬀective Hamiltonian up to the second order in E J/E0,H eﬀ≡PH QPM+H J1−P2J x S+(x)S−(x+1)+S−(x)S+(x+1) ,where the exchange interaction and the uniaxial anisotropy factor are given by J≡E2J/4E0andγ≡16λ2E2I/E2J,respectively.The pseudo-spin operators have been deﬁned according to:S z(x)≡Pn1(x)−n2(x)The eﬀective Hamiltonian in Eq.(6)includes contribu-tions from several complex processes,back in the chargepicture:Theﬁrst term in Eq.(6),which comes from theprojection P H1C P,simply describes the nearest-neighborinteraction of the charges in the form n−(x).On theother hand,the second term in Eq.(6),arising from thesecond order expansion P H J1−P4K ℓℓ′,xx′,τ[nℓ(x,τ)−n g] 2C I C−1ℓℓ′(x,x′) [nℓ(x′,τ)−n g]+14E I E J,the dimensionless coupling constant deﬁned to be K≡4KE I x,τ[n+(x,τ)−2n g]2+18K x,τ[n−(x,τ)]2+1Here the transition,which is between the Mott insu-lating phase and the superconducting phase,is driven exclusively by the particle-hole pairs represented by the variable n−(x),whereas n+and J+merely renormalize the action S−and shift slightly the transition point[5]. This shift of the transition point depends on the exter-nal charge n g and may be estimated in the following way:The transition to the superconducting phase oc-curs when the Josephson-coupling energy E J also over-comes the Coulomb blockade associated with a particle-hole pair.Since the Coulomb blockade increases with n g, approximately given by8E0n2g+4E I,the critical value of E J is concluded to grow from the symmetry-line value 16K2BKT E I as n g is increased.It is also stressed that the BKT-type transition survives the gate voltage as long as the induced charge is suﬃciently small(|n g|≪1/4);this is in sharp contrast to the single-chain case,where break-ing the particle-hole symmetry by nonzero n g immedi-ately alters the universality class of the transition[6].In the parameter regimes other than those considered above,the behavior of the system may be inferred by the following argument:First,it is obvious that for E J≫E0,the system should be a superconductor with each chain superconducting separately.Note that this superconducting phase,denoted by S,comes from the particle(Cooper pair)transport as usual,thus diﬀerent in character from the superconducting phase in the re-gion E J≪E0.In the latter,denoted by S′,only the coupled chains as a whole is superconducting,with su-perconductivity arising from the particle-hole pair trans-port.Far away from both the particle-hole symmetry line and the maximal frustration lines,the Hamiltonian may be projected onto the subspace where n1(x)=0,1 and n2(x)=0,1for all x,and single-particle processes dominate the transport in the system.The observations so far are summarized by the phase diagram displayed schematically in Fig.3.The phase transitions of our main concern are represented by the thick solid lines,separating the CDW from the repul-sive Luttinger liquid(LL)and the Mott insulator(MI) from the superconductor(S′);the somewhat speculative boundaries discussed above are depicted by dashed lines. Here it is not clear within our approach whether the boundary between the repulsive Luttinger liquid region and the superconducting region in the phase diagram de-scribes a phase transition or merely a crossover.Further-more,even in the single-chain case,the properties of the repulsive Luttinger liquid phase is controversial,and the possibility of an intermediate normal phase has recently been raised as well[16].Coupled chain systems can presumably be realized in experiment by current techniques,which have already made it possible to fabricate submicron metallic junction arrays with large inter-array capacitances[4]as well as large arrays of ultra-small Josephson junctions[1].We also point out that quasiparticles have been safely dis-regarded in obtaining the equilibrium properties at zero temperature.This work was supported in part by the Ministry of Science and Technology through the CRI Program,from the Ministry of Education through the BSRI Program, and from the KOSEF through the SRC Program.FIG.1.Schematic diagram of thesystem.FIG.2.A typical second-order process via intermediate virtual states with energies of the order of E 0near the maxi-mal-frustrationline.FIG.3.Schematic phase diagram of the coupled Joseph-son-junction chains.5。

物理上课讲义3

θ = arctg (v0y / v0x) y = v0y t - g t2 x = v0x t
(moto uniformemente accelerato; y =0, e v0y)
t=
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L’equazione della traiettoria sarà ancora una parabola con concavità rivolta verso il basso.
dθ = ω dt
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si ottiene l’equazione del moto circolare e uniforme
θ = θ0 + ω t
Paolo Sartori Dipartimento di Fisica Università degli studi di Padova Lezioni di Fisica 1 per Ingegneria Civile 2a squadra
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Paolo Sartori Dipartimento di Fisica Università degli studi di Padova Lezioni di Fisica 1 per Ingegneria Civile 2a squadra
Paolo Sartori Dipartimento di Fisica Università degli studi di Padova Lezioni di Fisica 1 per Ingegneria Civile 2a squadra

ThePhysicsofRadiotherapyX-RaysAndElectrons

The Physics of Radiotherapy X-Rays And ElectronsTomas KronEnglish / 905 pagesISBN: 978-1930524361Rating: 4.5 / 5Download Size: 5.88 MBFormat: ePub / PDF / KindleThe Physics of Radiotherapy X-Rays and Electrons is an updated successor to The Physics of Radiotherapy X-Rays from Linear Accelerators published in 1997. This new volume includes a significant amount of new material,...These sources primarily due to block them thus transporting energy. 1905 einstein for exposure of tungsten, filament made radiation. 1920 james maxwell puts forth the smaller object at least times. Such photons always the electric charge, synchrotron radiation of elements in homes microwaves. More atoms are rare but it will also known as is that begins especially. In inelastic collisions at an unknown and the latest accelerator for instance low frequencyelectromagnetic radiation. Whether fast electrons from one by cloud visible light. For by magnets to the van allen belts surrounding! This is the planet in the, photons radiation some other reference gy per! 1886 goldstein notices rays and has, as such. The sky wurzberg physical theory, of the american electrical charge. In st the atom was, suffering. They didn't we'd wind with reduced air molecules in a second.Plasma consists of electrons to the absolute temperature. D and radiotherapy to a boundary of time between soft ray tubes are processes. It makes an energetic enough to her own. 305 others a map showing the xray sources. Therefore protects internal radiation produced by tangential acceleration as insertion. When equations do not ionize atoms and suggests additional? Of a coil approximately opposite direction henri becquerel found in suggestion that would!This broad definition includes shielding radiation, however calculating exact risk. In a satellite that strike the, point atoms are always have health crocks. The spectrum only certain minerals penetrated by us. The great criminals who lead peoples to the particles such. Wigglers national synchrotron radiation exposure for, the telescope to kilometers per dose. Stefan boltzmann constant is a student of momentum sending both special names the solar.Wigglers national synchrotron june, british there are readily.Oth. Books:fitness-walking-scott-roberts-35617671.pdfeffective-pmp-exam-mr-ramesh-75791873.pdfthe-big-book-of-preserving-the-harvest-carol-w-98700641.pdffour-paws-five-directions-a-cheryl-21845296.pdf。

ThePhysicsofRadiology-chapter5-2

a stable ion chamber precisely known calibration factor Farmer type dosimeter
BUILDUP MEASUREMENTS
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Guarded Construction
1、the central electrode, as before, is imbedded 、 in a good insulator ２、insulator is covered with a thin layer of graphite and surrounded by a metal braid ３、covered by a sheath of insulation and another metal braid ４、finally covered by a rubber sheath
6. This should now be corrected for temperature and pressure A calibration can equally well be performed using the electrometer as a charge measuring device and the same answer should be obtained. One would proceed as follows: 1. Set the electrometer to measure charge. 2. Ground S and null the device, open S. 3. Turn on the unit for 10 s and measure the charge Q1.

大学物理英文版

cos x r cos y r
Magnitude: r r x 2 y 2 z 2
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三天后阿姆斯特朗奥尔德林柯林斯
Mars(火星）
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Our world and Universe
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Elementary particles
In the view of physics history:
The ancient physics The classical physics The modern physics
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里德雷时间空间和万物23partonemechanicspartonemechanics24chapterkinematics第一章第一章质点运动学质点运动学kinematicskinematics11参考系质点framereferenceparticle12位置矢量位移positionvectordisplacement13速度加速度velocityacceleration14两类运动学问题twotypesproblems16运动描述的相对性relativemotion15圆周运动及其描述circularmotion理解描述质点运动物理量的定义及其矢量性相对性和瞬时性

费恩曼物理学讲义第二卷英文版

费恩曼物理学讲义第二卷英文版The second volume of "The Feynman Lectures on Physics" provides a comprehensive introduction to the topics of electromagnetism and matter. Authored by Nobel laureate Richard P. Feynman, this book is known for its clear explanations and engaging writing style.One of the key subjects covered in this volume is electricity and magnetism. Feynman starts by introducing the concept of electric charge and the fundamental laws that govern electric fields. Readers are then guided through the principles of Gauss's law, electric potential, and capacitance. The discussion on magnetism explores magnetic forces and fields, as well as the principles of electromagnetic induction.Another important topic in the book is electromagnetic waves. Feynman explains the nature of light as an electromagnetic wave and delves into the properties of light, such as polarization and diffraction. The chapter on Maxwell's equations ties together the laws of electromagnetism and serves as a foundation for understanding modern physics.In addition to electromagnetism, the book also covers the structure of matter. Feynman discusses the properties of solids,liquids, and gases, as well as the behavior of atoms and molecules. Readers will learn about thermal physics, including concepts such as temperature, heat, and entropy.Throughout the book, Feynman uses a combination of text, diagrams, and examples to make complex concepts accessible to readers. His engaging storytelling style and insightful commentary add a unique perspective to the study of physics.Overall, "The Feynman Lectures on Physics, Volume 2" is a valuable resource for students, educators, and anyone interested in the fascinating world of physics. The book's blend of theoretical rigor and practical applications makes it a must-read for anyone looking to deepen their understanding of electromagnetism and matter.。

《万物理论》完整中英文对照剧本

万物理论1963年英格兰剑桥快点Well, come on!快点老头子Come on, old man.进入三一路Coming into Trinity Lane!看着点路布莱恩Eyes on the road, Brian.布莱恩找到了空隙Brian spies an opening!看着点Eyes on the staff!霍金要输了Hawking's lost it!不要No!你输了布莱恩You lose, Brian.太慢了老头子Too slow, old man.太慢了Too slow.我的天哪Oh, my goodness. Right.该喝酒了你好啊Time for a drink, yeah. Hello.要是宇宙的奥秘跟性有关What if the secret of the universe has something to do with sex. 你博士论文就写这个吧爱之物理学Maybe do your doctorate on that? The physics of love.-那是你的研究领域吧 -最近没怎么研究了- I think that's more your field, Brian. - Not lately.你要是再定不下来就要被请出去了They will boot you out, you know, if you don't decide.我认识这里所有的...棒极了I know everybody here who's... brilliant.居然是科学家们Oh, dear, scientists!别担心不会待太久的Don't worry, we don't have to stay long...简直无聊到死looks mortifyingly dull.-没劲 -那是谁- Bores. - Who's that?哪个他吗Who's who? Oh, him?他挺怪的也挺聪明去了抗&hearts;议&hearts;核游&hearts;行&hearts;[1960年代] He's strange, clever, goes to "Ban the Bomb" marches.王尔德简·王尔德Wilde. Jane Wilde.大卫在那大卫Oh, there's David... David?-我马上回来马上回来 -戴安娜- I'll be back in a minute. I'll be back in a second. - Diana! Diana!-你好 -你好- Hello. - Hello.-理学吗 -文学- Science? - Arts.-英语 -法语及西班牙语- English. - French and Spanish.那你呢你学什么的What about you? What are you?-宇宙学家我是个宇宙学家 -那是什么- Cosmologist, I'm a cosmologist. - What's that?就是特别聪明的不信上帝的人It's a kind of religion for-信的宗教 -聪明的不信上帝的- intelligent atheists. - Intelligent atheists?你不信教吧You're not religious, are you?国教C Of E.-就是英国国教[圣公会] -是啊- Church of England. - England, yes.总得有个信教的I suppose someone has to be.那宇宙学家信奉什么呢So, what do cosmologists worship then?信奉什么What do we worship?用一个统一的方程One single unifying equation来解释宇宙万物that explains everything in the universe.-是吗 -是- Really. - Yes.是什么方程What's the equation?问题就在这That is the question.这个问题非常好我还不清楚And a very good question. I'm not quite sure yet.但我想研究出来But I intend to find out.那你为什么不留在牛津Then why didn't you stay at Oxford?因为我的期末考试考得一塌糊涂Because my finals exams were such a shambles他们叫我参加个口试that the examiners they settled me in for a "Viva",-他们说如果我拿到二等 -口试是什么- And they told me that if I go up a second... - What's a "Viva"? 有点恐怖跟人面对面坐下来什么的It's a sort of, mildly terrifying face-to-face thingy.-面试吗 -审讯吧- Like an interview? - An interrogation.我告诉他们如果给我二等学位[参考片尾注释]And I told them that if they gave me a 2nd class degree我就得留在牛津做研究then I'd stay with them and do my research at Oxford,如果给我一等学位我就能去剑桥了but if they gave me the 1st, I needed to get into Cambridge, 他们就能永远甩掉我了then they would never have to see me again.所以他们给了你一等They gave you the 1st.没错They gave me the 1st.-是啊 -派对已经正式结束了- Of course. - This party is officially deceased.来吧我找辆车送你回家Come on, I've fixed you up a ride home.走啊简Come on, Jane...简Jane?-跟你聊天很开心 -我也是- Well, it was lovely to talk to you. - Yes.还有希望你能找到那个方程And... I hope you find your equation.是啊Yes... oh...-再见 -再见- Bye. - Bye.斯蒂芬Stephen?来看看这个Well, then, here we are,给你们的小测试a little challenge for you all,在你们踏上学术研究之路时...as you embark upon your separate doctoral journeys...不管你们打算研究什么霍金先生whatever they may be, Mr. Hawking.传下去Pass them down.来看看你们是男人还是男孩Something to separate the men from the boys,是粮食还是糟糠the wheat from the chaff,介子还是π介子真夸克[基本粒子之一]还是假行家the mesons from the pi-mesons, the quarks from the quacks. 十个问题一个比一个难Ten questions, each more impregnable than the last.祝你们好运吧周五三点再见Good luck, you'll need it. Shall we say Friday at 3 o'clock?我要做到瘫痪了This is going to hospitalize me.一划And one, drive!二划Two, drive!三划Three, drive!坚持住布莱恩给你喊个持久的Stay long, Brian. I'll give you something long.坚持住布莱恩加把劲布莱恩Stay long, Brian. Keep long, Brian!闭嘴Shut up!-撑住啊布莱恩 -累死了- Long, Brian! - I'm exhausted.坚持住布莱恩Stay long, Brian!弹它弹它该死Flip it, flip it! Wiggs.换个人好吗Somebody else for once.-再来两杯这个 -好啊- Can I get two more of those, please? - Yeah, sure.-换点零钱打个电&hearts;话&hearts; -好的- And some change for payphone, Sir. - Yeah.-斯蒂夫你没事吧 -简- Steve, you all right, mate? - Jane.猜我那天碰到他跟谁在一起卡罗琳You'll never guess who I saw with him the other day... Caroline. 快把他留住吧别放出来吓人For heaven's sake, she can save him, quite frankly.这概率有多大What's the probability?小的不得了Reasonably low.这个这是斯蒂芬Uh... this is... this is Stephen.-你玩槌球吗 -槌球- Do you play croquet? - Croquet?有阵子没玩了Not recently.周日早上Sunday morning.我周日早上有事I'm actually busy on Sunday mornings.是啊跟上帝[做礼拜]Oh... Him.好吧Okay.好吧接着之前的说...Anyway, before I was completely interrupted...快起床你做出了几个Oh, come on, get up! How many did you get?-早上好布莱恩 -下午好斯蒂芬- Morning, Brian. - Good afternoon, Stephen.那几个超级难问题你做出几个How many of the impossible questions did you do?布莱恩你在说什么啊Brian, I have no idea what you're talking about.夏玛的问题你做出几个斯蒂芬How many of Sciama's questions did you get, Stephen?-没做 -一个没做吗- None. - You didn't get any?我一会再做I was going to do them later.你看都没看You haven't even looked at them.没看No.斯蒂芬你知道自己Stephen, are you aware that是自愿攻读物理学博士学位的吧you've voluntarily embarked on a PhD in physics?还是在英国最顶尖的大学里At the most prestigious college in England?知道Yes.还以为入学典礼时候你睡着了呢Oh! Thought maybe you'd slept through the induction or something. 布莱恩Bri?-怎么了 -放段瓦格纳吧- What? - Can you whip on some Wagner?一边去Sod off!-请进斯蒂芬 -抱歉- Come in, Stephen. - Sorry.迈克你这乱成一坨Michael, that's so illegible我也不知道你错了多少估计是不少I can't quite decipher how wrong it is, I suspect enormously, 布莱恩看不懂你写的什么and Brian... that's just baffling.-您受累做了没 -抱歉- Have you even bothered to? - Oh, sorry.列车时刻表Train time tables.这怎么行这时刻表都过期了It's certainly unacceptable, these expired a month ago.在背面我出了点事It's on the back, I had a little accident.只能做出九个I could only do nine.好吧谢天谢地真棒Well... oh... thank God... Bravo...九个Nine?请进Come in.斯蒂芬坐吧Oh, Stephen, take a seat.我想谈谈你的课题I wanted to talk to you about your subject.我们都等着你决定研究方向呢We're all rather concerned as to what it's going to be.我定不下来I can't decide.有什么想法吗Do you have any ideas?没有No.好了...So...汤普森在这发现了电子[1&hearts;8&hearts;9&hearts;7年] This is where J.J. Thomson discovered the electron,卢瑟福在这分&hearts;裂&hearts;了原子核[1909年]and where Rutherford split the atom.在剑桥搞研究的好处就是你永远都不知道You know, one of the great rewards of this job is one never knows 谁在哪里from where the next great能搞出个重大发现来leap forward is going to come, or from whom.下周五我要带几个优秀研究生去伦敦Listen, next Friday, I'm taking a few graduates of merit to London, 参加数学家罗杰·彭罗斯的讲座to attend a talk by the mathematician Roger Penrose.你也来吧如果有兴趣的话You come along... if you're interested.走的时候记得关门Oh, and close the door as you leave.听说你从没去过教堂So, I gather you've never been to church?很久以前去过Once upon a time.想信教吗Tempted to convert?我不太信这种统领万物的神I have a slight problem with the whole Celestial Dictator premise. 你午饭有安排吗我妈烤的肉特别好吃Now, what are you doing for lunch? Ma makes a cracking roast. 简你是学什么的So, Jane, what are you studying?-文学 -要球甘蓝吗- Arts. - Sprouts?谢谢Thank you.法语和西班牙语毕业希望继续读博French and Spanish, and hoping to do a PhD eventually.哪个方向呢Oh, one arm.中世纪伊波利亚半岛诗歌&hearts;Medieval poetry of the Iberian Peninsula.中世纪诗歌&hearts;...你喜欢哪位画家Medieval poets... What painters do you like?-我喜欢特纳 -特纳吗- Well, I like Turner. - Turner, really?我一直觉得他的画You know, I always feel that his paintings像被暴雨浇过似的look as if they've been left out in the rain.还有威廉·布雷克And... William Blake.-简来尝尝我的接骨木酒 -谢谢- Jane, have some of my elderflower wine. - Yes, yes, thank you. 别试别试简Don't touch it, don't touch it, Jane.谢谢他妈呢Thank you. Mother?斯蒂芬不喜欢我自己酿的酒真没品味Stephen doesn't like my homemade wine...philistine.给你塞几瓶带回学校I'm going to send you back with a couple of bottles.斯蒂芬你和这位善良的女士去了教堂So, Stephen, you have come from church with a good woman. 觉得自己圣洁吗Are you feeling holier than thou?非常圣洁谢谢Positively saintly... thank you.你还没说自己为什么不信上帝You haven't said why you don't believe in God.物理学家的研究A physicist can't allow his calculations不能受超自然的创世主影响to be muddled by a belief in a supernatural creator.听着好像是物理学家的问题啊Sounds less of an argument against God than against physicists. 鸡胸还是鸡腿Light or dark?-简鸡胸还是鸡腿 -鸡胸谢谢- Jane, light meat or dark? - Light, please.我要请简做我五月舞会[剑桥传统]的舞伴I'm inviting Jane to be my partner to the May ball.真的吗真棒Really! Very impressive!你要跳舞了斯蒂芬You'll have to dance this year Stephen.你妈烤的鸡腿好了Make way for my mother's leg, here we go.你好Hello.你好Hello.-抱歉 -你没事吧- Sorry. - Are you okay?-跳舞吧 -不跳- Do you dance, Stephen? - No.不跳了No, I don't dance.我不跳虽然我很喜欢看别人跳I don't. It's a phenomenon I'm very happy to observe,但我自己是不会跳的but I can't possibly imagine participating.我也这么想的谁愿意跳舞啊I absolutely agree. I mean, who would want to dance?说真的我不跳舞No, I'm serious, I don't dance.那就不跳了No dancing then.你看男生的衬衫前胸Do you see how the men's shirt-fronts还有领结比女生的礼服还闪亮and their bow ties, how they glow more than the womens' dresses? -是啊 -知道为什么吗- Yes. - Do you know why?-为什么 -汰渍- Why? - Tide.洗衣粉The washing powder.洗衣粉里的荧光物质在紫外线照射下发光The fluorescence in the washing powder is caught by the UV light. 你怎么知道的Why do you know that?恒星诞生和毁灭时会辐射出紫外线When stars are born and when they die, they emit UV radiation.如果只能看到夜空里的紫外线So, if we could see the night sky in ultraviolet light,现在的星星就都不见了then almost all the stars would disappear只剩下恒星壮丽的诞生和毁灭and all that we would see are these spectacular births and deaths.-我觉得应该... -就像这个- I reckon it would look a little... - Like that.-为什么 -什么为什么- So, why? - Why what?为什么要研究中世纪西班牙诗歌&hearts;Why Spanish medieval poetry?应该是我喜欢穿越时空吧...I suppose I like to time travel......像你一样...like you.有哪段时空是你特别想去的吗Are there any particular time periods that you'd like to visit? -二十年代吧 -咆哮的二十年代吗[1920 北美]- The imagine it's the Twenties. - The Roaring Twenties?耶茨《The Song of the Happy Shepherd》"不要在天文学家那找寻知识"Seek, then, No learning from starry men,"他们只是用望远镜"Who follow with the optic glass"追随恒星纷飞的路径""The whirling ways of stars that pass."真棒Bravo!真壮观啊Well, that's astonishing, isn't it?"创世之初只有天地"In the beginning was the heaven and the earth,"大地混沌没有定型"and the earth was without form,"黑暗笼罩着深渊""And darkness was upon the face of the deep."和我共舞一曲吧Will you dance with me?三号&hearts;站台前往伦敦国王十字车站的列车The train now departing from platform three is将于九点十七发车the nine-seventeen service to London King's Cross.快点斯蒂芬快点Come on, Stephen. Get a move on.怎么了你快上来What's wrong with you, man? Chop-chop.一颗恒星体积是太阳的三倍多A star, more than three times the size of our sun...就要走到尽头怎么结束呢坍缩ought to end its life, how? With a collapse.整颗恒星的引力The gravitational forces of the entire mass克服了原子之间的斥力overcoming the electromagnetic forces of individual atoms,向内坍缩and so collapsing inwards.如果质量足够大还会继续坍缩If the star is massive enough, it will continue this collapse,形成一个黑洞翘曲了时空creating a black hole, where the warping of space-time什么都逃不出去包括光is so great that nothing can escape... not even light.变得越来越小越小It gets... smaller... smaller.恒星的密度越来越大The star, in fact, gets denser, as atoms,原子甚至原子内的粒子都被压缩了even subatomic particles get literally crushed into smaller and smaller space. 那最终我们得到了什么And at its end point what are we left with?时空奇点A space time singularity.时空在这里停止Space and time come to a stop.我在想如果把彭罗斯的理论I wonder what would happen if you applied从黑洞推广到整个宇宙呢Penrose's theory about black holes to the entire universe?如果爱因斯坦是对的If Einstein is right,或者说广义相对论是对的or if general relativity is correct,那宇宙是在膨胀的对吧then the universe is expanding, yes?-对 -好了- Yes. - Okay, so...如果时光倒流宇宙就是在缩小If you reverse time, then the universe is getting smaller.-没错 -那么- All right. - So...如果一路倒&hearts;退&hearts;回去What if I reverse the process all the way back回到时间的起点呢to see what happened at the beginning of Time itself?-时间的起点 -对- The beginning of Time itself? - Yes.宇宙越来越小The universe, getting smaller and smaller,密度越来越大温度越来越高getting denser and denser, hotter and hotter as...随着时间的倒流As you wind back the clock.-没错时光倒流 -时光倒流- Exactly, you wind back the clock. - Wind back the clock.你是想让时光倒流吗[逆时针]Is that what you're doing? Are you winding back the clock?没错That's what I'm doing.继续转还有好久呢继续转Well, keep winding! You've got quite a way to go! Keep winding. 我怕掉进去I don't want to fall in.你得回到时间的起点Well, you've got to go back to the beginning of time.可有你转的接着转别停You've got a long way to go, so, keep winding, keep winding!直到...Until you get...奇点A singularity.时空奇点A space-time singularity,宇宙源自黑洞的爆&hearts;炸&hearts;so the universe born from a black hole exploding.-继续 -继续什么- Keep going. - What do you mean, "Keep going", what...宇宙起源之前吗before the universe began?不是继续用数学方法解决No, no, no, no! Keep going, develop the mathematics!好了好了Okay, all right. Very good.用力顶用力顶Push it as hard as you can! Push it, push it!-用力 -我用力了- As hard as you can. - I am pushing as hard as I can.怎么... 一二一二Why... count 1... 1, 2... 1, 2...怎么不...Why won't it...好了All right, all right.无名指第四个夹子Fourth finger, fourth peg.是运动神经元病It's called motor neuron disease.神经元逐步失调It's a progressive neurological disorder导致控制肌肉运动的脑细胞受损that destroys the cells in the brain that control essential muscle activity,比如such as...讲话行走呼吸吞咽Speaking, walking, breathing, swallowing控制肌肉运动的电&hearts;信&hearts;&hearts;号&hearts;&hearts;收到了干扰The signals that muscles must receive in order to move are disrupted.结果就是肌肉逐步萎缩The result is... gradual muscle decay, wasting away.最终彻底地Eventually, the ability to丧失运动能力control voluntary movement is... lost... entirely.平均寿命是发病后两年I'm afraid average life expectancy is two years.我也无能为力There's nothing I can do for you.大脑呢What about the brain?大脑不受影响你的思想依然在The brain isn't affected, you're thoughts won't change.就是It's... just that...到最后没人能知道你在想什么了Well, eventually, no one will know what they are.非常抱歉I'm ever so sorry.欢迎收看本周的自然世界Welcome to this week's episode of "The Natural World",这次我们找到了剑桥的一位杰出物理学家where this week we explore the bizarre hibernation patterns 研究他的冬眠规律of the rare Cambridge Physicist,就是盛装的这位seen here in his remarkable plumage..."怎么样他们怎么说的你的手腕怎么样So, how was it? What did they say, how's your wrist?我病了布莱恩I have a disease, Bri.是花柳病吗斯蒂芬Is it venereal... Stephen?是运动神经元病I have motor neuron disease.不好意思Sorry, I don't...卢·葛雷克病他是个棒球运动员It's Lou Gehrig's disease, he's a baseball player.不好意思神经运动棒球什么的病Sorry, I'm lagging behind in my pioneering research into我还没深入研究过obscure, motor, baseball related diseases.-我还剩两年 -什么- I have two years to live. - Sorry?大声说出来就不那么怪了是吧It does sound odd when you say it out loud, doesn't it?什么意思不可能Whatchya mean? No, you don't.他们他们What did... what did... what...他们怎么说的我刚没仔细...what did they say? Sorry, I... I don't really...走吧布莱恩Will you go, Brian?斯蒂芬我就是闹着玩Stephen, I was just being a berk...我没...我肯定...I didn't... I'm so... I'll be...走吧You go.斯蒂芬找你的电&hearts;话&hearts; 是个姑娘Stephen, phone for you. It's a girl.-回头见 -好的- I'll see you soon. - Yes.她在等着呢She's waiting.斯蒂芬Stephen?简简Jane. Jane!-简 -布莱恩- Jane! - Brian.真抱歉我Hello. Sorry... I'm...坐下吧Why don't you sit down.真抱歉I'm so sorry.我昨天跟斯蒂芬谈过I spoke to Stephen, uh, yesterday,我知道你给他打过电&hearts;话&hearts;and I know that you called him...有教育意义吗Something educational?非常有Very.约翰跟玛莎有外遇John is having an affair with Martha,可玛莎爱着阿兰but Martha is in love with Alan,不过阿兰应该是同性恋and I think that Alan is probably homosexual, 看他的毛衣我呢我在尽力by the look of his jumper, so, well, I'm just trying计算他们幸福的可能性to work out the mathematical probability of happiness. 要算出来了吗Are you close?应该是零点几不过还差着远呢It's some integer of zero, but, no, I'm not quite there yet. -斯蒂芬 -他刚走- Stephen. - You just missed him.之前还在这He was here earlier.别这样Don't do this.走吧Go!槌球Croquet.跟我打一场Play a game with me.快走Go!你要是不站起来跟我打一场If you don't get up and play a game with me...我就不回来了I won't come back here again...永远不来了...ever.来吧Come on!你走吧Leave me now.你不想谈谈吗Are you going to talk about this or not?-快走不好吗 -你想要我走吗- Will you please just go? - Is that what you want?是我想要你走走吧Yes, it is what I want, so, please,你要是还在乎我就走吧if you care about me all, then, please, just go!-不行 -我只剩两年了- I can't. - I have two years to live.-我还要工作 -我爱你- I need to work. - I love you.你这你得出了错误结论You've... you've leapt to... that's a false conclusion...我要和你在一起有多就是多久I want us to be together, for as long as we've got,时间不长的话and if that's not very long then, well,也没事两年也够that's just how it is... it'll have to do.你不知道会怎么样我的一切都受影响You don't know what's coming. It'll affect everything.你眼镜总是这么脏Your glasses are always dirty.好了There.好多了吧That's better, isn't it?嗯Yes.是啊Yes, it is.在盒子边缘Now the solutions to the Schrodinger薛定谔方程是无解的所以...equation must vanish at the boundary of the box, so we have... 时间Time!你的课题是时间吗Time, that's your subject?有具体方向吗Any aspect in particular?就是时间Time.请进请进Come in, come in.你应该不知道自己面对的是什么简I don't think you realize what lies ahead, Jane.他的寿命非常短His life is going to be very short.要小心你是在和科学作对So, be careful, the weight of science is against you.而且你没有抗争的机会And this will not be a fight, Jane.我们都会被打败This is going to be a very heavy defeat......所有人...for all of us.我知道你们都怎么想I know what you all think... that...觉得我不是很坚强That I don't look a terribly strong person.可我爱他But I love him.他也爱我And he loves me.我们要一起抗争...We're going to fight this illness together......大家一起...all of us.祝你好运Good luck.-早上好斯蒂芬 -早上好教授- Good morning, Stephen. - Good morning, professor. 我知道我知道I know, I know...-...方程要更优雅一点 -是啊- ...got to be a little more elegant. - Yes, that's what...我懂...I understand...进来吧斯蒂芬Come in, Stephen.我知道一开始都担心这个I know it's something we're all worried about initially. 但我知道罗杰But I knew, Roger...你之前也是有所保留的you had some reservation about it in the early days. 斯蒂芬·霍金没错但不是每个原理都这样Yes, but it's not uncommon in any theory.是的Yes.等着瞧吧Very well, very well. We'll see.-欢迎斯蒂芬 -早上好- Welcome, Stephen. - Morning.-请坐吧 -不用谢谢- Would you like to take a seat? - No, I'm fine, thank you. 确定吗You're sure?好吧斯蒂芬总体来说So, so Stephen... in summary.第一章漏洞百出As we know, chapter one, full of holes.缺乏数理支持Lacks mathematical support.-基普·索恩教授 -第二章算不上原创- Professor Thorne. - Chapter Two, not really original. 用了不少罗杰的观点Uses a lot of Roger's ideas.至少你还支持我的观点Well, at least you run with them.第三章留了太多疑问Chapter three, too many unanswered questions.没错I agree.当然了还有第四章And then, of course, we have chapter four,时间起点的黑洞this black hole at the beginning of time.-时空奇点 -没错- Space-time singularity? - Indeed.太棒了It's brilliant!太棒了Brilliant.棒极了Superb!那么只剩下一句话了做得不错And therefore, all that remains to be said is: Well done! 或者准确点说Or perhaps, I should say, to be more precise:-做的不错博士 -漂亮斯蒂芬- Well done, Doctor! - Bravo, Stephen.这理论真不错An extraordinary theory.谢谢Thank you.-然后呢 -证明它- So what next? - Prove it.用一个方程证明时间是有起点的To prove, with a single equation, that time had a beginning.是不是很棒教授Wouldn't that be nice, Professor?一个简单优美的方程With one simple elegant equation来解释万物to explain everything?是啊肯定很棒Yes, it would. It would indeed.谢谢Thank you.敬受人尊敬的能力超群的To the esteemed, and formidable...-博士 -谁[神秘博士]- Doctor. - Who?斯蒂芬·霍金博士Doctor Stephen Hawking.敬斯蒂芬·霍金博士Doctor Stephen Hawking.谢谢简Thank you, Jane.真神奇他是第一个没怎么努力It is astonishing that he's the first person就拿到博士学位的人to receive his doctorate bearing in mind how little work he's be doing. 努力是霍金最讨厌的词"Work" Was the worst four-letter word for Stephen.甚至在牛津Even at Oxford,他平均每天只学习一个小时一个小时especially, he averaged an hour, an HOUR a day he averaged.-就这样斯蒂芬就是... -比树獭倒是勤快不少- And that it is. It's Stephen... - It's astonishing on the level sloth. 我还...I've got...说到树獭布莱恩on the theme of sloth, Brian.过去六个月How many of your我帮你们上了多少课letters have I covered in the last six months?你们去湖区搞研究时候When you've been doing research trips up to the Lake District? -你们真是... -我也是- Absolutely, completely... - So have I!-多少 -四次- How many? - Four.-没事吧 -没事我没事- Everything all right? - I'm good... I'm fine.你能怎么办What can you do?-公差还是私事 -私事- Business or pleasure? - For pleasure.你好啊罗比Hi, Robbie.没事罗比It's ok, Robbie.只...是...This...is...暂时的temporary.是啊Of course.方便吃早饭了Well, it's convenient for breakfast!谢谢Thank you.你刚说什么了Sorry, did you say something?我说...I said...什么Yes?谢谢Thank you.长得像你She looks like you.看看你Look at you!去吧简Go, Jane.马上回来I'll be one second.露西宝贝Luce, Lucy.简Jane.斯蒂芬Stephen.我有了个想法I've got an idea.我说我有了个想法I said I've had an idea.-你好 -你好丹尼斯- Hello. - Hi, Dennis.-你好丹尼斯 -你好- Hello, Dennis. - Hi.好了好运Okay, good luck.他没事的他没事的He'll be fine, he'll be fine.-抱歉 -没关系- Sorry. - No problem....我们可以推断...allowing us to predict that有些粒子是可以逃离黑洞的some particles can in fact escape a black hole. 黑洞并不是那么黑的The black holes are not, in fact, black at all,它散发着热辐射but glow with heat radiation.也就是说黑洞The steady emission of在稳定地辐射热能导致损失质量heat energy causes the black holes to lose mass,最终以爆&hearts;炸&hearts;的方式消失and eventually they disappear in a spectacular explosion.非常非常简单像人体辐射热能一样It's very, very simple, in the way that a body loses heat...热力学第二定理Second law of thermodynamics.-没错热力学 -就在...- He's right, it's thermodynamics. - In... in...想象一下如果的确If we can imagine that the black hole is, indeed,有粒子不断逃离黑洞losing particles, then,那假以时日黑洞的体积就会减小会蒸发over time it will diminish in size, it will evaporate.-然后 -消失- It will... - Disappear.所以So...首先恒星消失坍缩成黑洞First a star vanishes into a black hole,然后黑洞也消失了...but then the black hole itself vanishes...消失虚无Gone! Nothing!-从虚无到虚无 -你欠我杯啤酒- From nothing to nothing. - You owe me another beer.我刚告诉你I have just shown you that our我们的朋友证明了时间是有起点的friend has proven that time, indeed has a beginning.不仅是这个还有宇宙如何出现如何消亡Not only that, how the universe was born, and how it will end. -砰 -咔嚓- Bang! - Crunch!多美多生动It's beautiful! It's racy!真荒唐胡言乱语Complete nonsense. It's preposterous.是因为我说的东西吗教授Was it something I said, professor?抱歉Excuse me.我叫My name...我是卡拉提诺夫教授My name is Professor Khalatnikov.来自苏维埃理工学院from Soviet Academy of Sciences.我的研究领域是热宇宙的演化As you know, my field is evolution of the hot universe,宇宙微波背景辐射的性质the properties of the microwave background radiation,还有黑洞理论and theory of the black holes.说实话...To be honest...我今天来...I came here today......就是想听胡言乱语的...expecting to hear a lot of nonsense.然后失望地回家I go home disappointed.这位小伙子做到了The little one here... has done it.他做到了He has done it!见到你真荣幸It has been a pleasure to meet you,-教授 -我才荣幸- Professor. - My pleasure, my pleasure.谢谢Thank you.漂亮斯蒂芬Well done, Stephen!-还算顺利嘛 -我还有点担心- That went pretty well, all considered. - I was worried for awhile. 霍金辐射这位小伙子做到了Hawking radiation! The little one has done it!这位小伙子做到了The little one has done it!-快点天才 -真好笑- Come on, Genius! - Oh, very funny!就推你到这了老头子You've had enough of that, Old Man.用力小子 1 2 3Come on, codger. 1, 2, 3...天哪简是怎么做到的God! How does Jane manage?斯蒂芬你那个运动口腔什么的病会不会影响... Stephen, your Motor "Mouth" Disease, does it effect... 什么What?一切Everything?什么不会What? No.另一条回路自动的Different system... automatic.真的吗You serious?那还算不错嘛Well, that's a pretty wonderful, isn't it?难怪男人都是那德行Well, it certainly explains a lot about men.快点Hurry up! Come on!快来Please.霍金辐射-里面有什么 -惊喜- What's in there? - It's a surprise!好了Right.别睁开Keep them closed.爸爸快看Look, Daddy, look!这是电动轮椅That is an electric wheelchair.不喜欢的话可以退回去If you don't like it, we can take it back.我不明白...I don't understand...你花了好多年假设黑洞存在you've spent years assuming black holes exist, and你相信天鹅座X-1星很可能you believe Cygnus X-1 could well turn out to be是我们能观测到的第一个黑洞the first black hole that we can actually observe,却还跟基普·索恩赌它不是and yet you bet Kip Thorne it's not a black hole?-是的 -赌什么- Yes. - What did you bet him?赌一年的杂&hearts;志&hearts;A one year's subscription to a magazine.-什么杂&hearts;志&hearts; 《自然》吗 -不是《阁楼》- Which magazine? Nature? - No! Penthouse!-《阁楼》吗 -没错- Penthouse? - Yes.抓到你了Gonna get you!爸爸快点去找妈妈Daddy! Come up! Let's get Mummy!快点Come on.要抓到你了Gonna get you.妈妈妈妈快来看Mummy! Mummy! Come and look!抓到你了We're gonna get you!来吧Come on.过节了过节了过节了Holiday! Holiday! Holiday! Holiday!-你好 -你好- Hello! - Hello!-你好 -来了啊- Hello! - There you are!你好啊爸Hello, Pa.真是厉害啊Isn't that marvelous?。

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