內容簡介
Quantum mechanics is one of the most fascinating, and at the same time most controversial, branches of contemporary science. Disputes have accompanied this science since its birth and have not ceased to this day. What is the sense of a probability interpretation of a physical phenomenon? Which approach to a quantum field theory is more consistent? How must we comprehend a quantum world? This book,leaving aside the search for spiritual content and answers to these questions, allows one to deeply contemplate some ideas and methods that are seldom met in the contemporary literature. Instead of widespread recipes of mathematical physics based on the solutions of integro-differential equations, we prefer logical and partly intuitional derivations of noncommutative algebra. The reader, having become armed with the necessary knowledge and skills from classical physics and symbolic mathematics, can thus directly penetrate the abstract world of quantum mechanics.
For exactly solvable models, we develop the method of factorization. This method, leaning primarily on Green's formalism, is applied for consideration of simple problems in the theory of vibrations and the relativistic theory of an electron. For more complicated problems, mainly related to the physics of various effects of anharmonicity, we develop the method of polynomials of quantum numbers, which enables one to systematize the calculations according to the perturbation theory. Regarding the quantum field theory and the calculation of observable radiative corrections, we rely entirely on Dirac's ideas, not on -at present-the pervasive rules of operation with a scattering matrix. Dirac's theory, possessing a proper elegance, is built on the equations of motion and is suitable for a first acquaintance with the principal problems of quantum electrodynamics, a matter of belief that remains open.
The author respectfully expresses his gratitude to John Ogilvie, who read the manuscript and made valuable comments. This book addresses a wide readership with serious enthusiasm about theoretical physics.
內頁插圖
目錄
Preface
1 Ideas and principles
Quantum world
Probability waves
Physical operators
Noncommutative physics
Moment of momentum
Perturbation theory
Factorization
Oscillator
Quantum numbers
2 Physics of the electron
Hydrogen atom
Bohr's formula
Matrix elements
Dirac's equation
Relativistic invariance
Spin one—half
Pauli's theory
Elementary consequences
Useful definitions
Positrons
Fine structure
Solution according to factorization
Magnetic interaction
Landau levels
Anharmonicity
3 Theory of anharmonicity
Model Hamiltonian
Perturbation method
Inclusion of degenerate levels
Polynomial formalism
Ensemble of anharmonic oscillators
General equations
Physical interpretation
Rules for polynomials
Quantum functions
Other anharmonic models
Morse potential
Generalized Morse problem
4 Quantum fields
Creation and destruction operators
Free scalar field
Quantization of electromagnetic field
Fermi's ideology
Electron—positron Dirac field
Interaction picture
Solution according to perturbation theory
Normal product
Ultraviolet divergences
Regularization of interaction energy
5 Radiative corrections
Renormalization of mass
Anomalous magnetic moment of the electron
On the history of radiative corrections
Bethe's formula
Electromagnetic shift of atomic levels
Vacuum polarization
Renormalization of charge
Dirac's ideas and quantum field theory
Bibliography
前言/序言
Quantum mechanics is one of the most fascinating, and at the same time most controversial, branches of contemporary science. Disputes have accompanied this science since its birth and have not ceased to this day. What is the sense of a probability interpretation of a physical phenomenon? Which approach to a quantum field theory is more consistent? How must we comprehend a quantum world? This book,leaving aside the search for spiritual content and answers to these questions, allows one to deeply contemplate some ideas and methods that are seldom met in the contemporary literature. Instead of widespread recipes of mathematical physics based on the solutions of integro-differential equations, we prefer logical and partly intuitional derivations of noncommutative algebra. The reader, having become armed with the necessary knowledge and skills from classical physics and symbolic mathematics, can thus directly penetrate the abstract world of quantum mechanics.
For exactly solvable models, we develop the method of factorization. This method, leaning primarily on Green's formalism, is applied for consideration of
simple problems in the theory of vibrations and the relativistic theory of an electron. For more complicated problems, mainly related to the physics of various effects of anharmonicity, we develop the method of polynomials of quantum numbers, which enables one to systematize the calculations according to the perturbation theory. Regarding the quantum field theory and the calculation of observable radiative corrections, we rely entirely on Dirac's ideas, not on -at present-the pervasive rules of operation with a scattering matrix. Dirac's theory, possessing a proper elegance, is built on the equations of motion and is suitable for a first acquaintance with the principal problems of quantum electrodynamics, a matter of belief that remains open.
The author respectfully expresses his gratitude to John Ogilvie, who read the manuscript and made valuable comments. This book addresses a wide readership
with serious enthusiasm about theoretical physics.
《經典力學進階:理論與應用》 本書簡介 《經典力學進階:理論與應用》旨在為物理學學生和研究人員提供一個深入、全麵且富有洞察力的經典力學框架。本書超越瞭基礎的牛頓力學範疇,重點探討瞭分析力學的核心原理,特彆是拉格朗日力學和哈密頓力學,並將其嚴謹地應用於一係列復雜的物理係統。 本書的結構設計旨在引導讀者逐步建立起對現代物理學基礎至關重要的概念工具箱。我們深知,理解經典力學,尤其是其更抽象的錶述形式,是通往量子場論、廣義相對論以及更高級統計力學理解的必經之路。因此,本書強調數學形式的優美性與物理直覺的培養並重。 第一部分:從牛頓到拉格朗日——變分原理的崛起 在本書的開篇部分,我們將迴顧牛頓定律,但其作用是作為過渡,迅速引嚮更強大的變分原理。 第1章:牛頓定律的局限與廣義坐標 本章首先批判性地審視瞭牛頓定律在處理約束係統時的不便之處。接著,我們引入瞭描述物理係統的廣義坐標和約束力的概念。重點討論瞭如何使用幾何約束來簡化對多體係統的描述,並為引入變分原理打下基礎。 第2章:達朗貝爾原理與虛功原理 這是理解分析力學的關鍵一步。我們將詳細闡述達朗貝爾原理——將動力學問題轉化為準靜態問題的巧妙方法。通過對虛功原理的深入分析,讀者將掌握如何從能量角度而非力平衡角度來推導運動方程。 第3章:拉格朗日力學的構建 本章的核心是拉格朗日量 $L=T-V$ 的定義及其在運動方程推導中的應用。我們將係統地推導歐拉-拉格朗日方程,並展示該方程在處理各種復雜約束(如單擺、雙擺)時的強大能力。本章將特彆關注守恒量與對稱性之間的關係,引入諾特定理的初步概念,即當拉格朗日量不顯含某一廣義坐標時,對應的廣義動量是守恒的。 第4章:守恒定律與諾特定理的嚴謹推導 在掌握拉格朗日方程後,我們正式引入諾特定理。本章將通過嚴格的數學論證,建立連續對稱性與守恒量之間的精確對應關係。我們將應用此定理分析經典力學中的關鍵守恒量:能量、綫性動量和角動量,並探討這些守恒量如何深刻地限製瞭係統的動力學行為。 第二部分:哈密頓力學的深度探索 第二部分將視角從作用量最小原理轉移到相空間(Phase Space)的概念,這是通嚮量子力學的橋梁。 第5章:勒讓德變換與哈密頓量的定義 本章詳細介紹瞭勒讓德變換,這是從拉格朗日力學過渡到哈密頓力學的數學工具。我們定義瞭哈密頓量 $H(q, p, t)$,並推導齣著名的哈密頓正則方程。重點分析哈密頓量與總能量之間的關係,以及在保守係統中的等價性。 第6章:相空間動力學與泊鬆括號 哈密頓力學的核心在於相空間分析。本章引入瞭泊鬆括號,它是描述相空間中任意兩個函數之間相互作用的微分算符。我們將展示泊鬆括號如何統一瞭經典力學的守恒定律,並闡述瞭泊鬆括號的基本代數性質。此外,本章將探討相空間中的流綫和李維爾定理,該定理描述瞭相空間體積在時間演化中的不變性。 第7章:正則變換與辛結構 正則變換是哈密頓力學中強大的坐標變換工具,它能保持哈密頓方程的形式不變。本章將詳細介紹生成函數法,並探討如何利用正則變換來簡化哈密頓量(例如,通過變換消除對時間的顯式依賴)。我們還會深入探討哈密頓係統的辛幾何結構,這是現代物理學中一個重要且優雅的數學框架。 第8章:哈密頓-雅可比方程 本章聚焦於尋找一個普適的、時間無關的正則變換,從而將哈密頓量對時間顯式依賴的係統,轉化為一個可以求解的零哈密頓量係統。通過求解哈密頓-雅可比偏微分方程,讀者將掌握求解復雜動力學問題的“終極”方法,該方程的解(作用量函數 $S$)直接導齣瞭係統的運動軌跡。 第三部分:經典力學在特定係統中的應用 最後一部分將理論工具應用於具體的、具有挑戰性的物理場景。 第9章:剛體動力學與歐拉角 剛體運動是經典力學中幾何約束最復雜的應用之一。本章將使用拉格朗日量處理剛體係統的平動和轉動,重點討論瞭慣性張量、轉動慣量的主軸,並詳細推導瞭描述剛體取嚮的歐拉方程。 第10章:中心力問題的高級處理 雖然中心力問題在基礎課程中有所涉及,但本章將使用哈密頓力學的語言進行重新審視。我們將利用正則變換,將開普勒問題(如行星軌道)轉換為一個簡單的、可積的係統,從而導齣精確的軌道方程,並展示如何利用相空間分析來理解軌道穩定性。 第11章:微擾論與攝動方法 在許多實際問題中,係統往往是可積係統的微小偏離。本章將介紹處理非可積係統的基礎微擾論。我們將學習如何使用時間相關的微擾理論來計算係統能量和狀態的修正項,特彆是當係統包含周期性驅動或弱非綫性耦閤時,如何應用這些方法。 結論 《經典力學進階:理論與應用》提供瞭一個從基礎力學到高等分析力學的係統路徑。本書不僅旨在傳授解決特定問題的技巧,更緻力於培養讀者對物理定律在抽象數學結構下統一性的深刻理解。掌握這些工具,將為進一步深入學習電動力學、量子力學以及更前沿的理論物理打下堅實的基礎。本書的習題設計強調概念理解和計算的精確性,確保讀者能夠真正內化這些核心概念。