Modern Physics for Scientists and Engineers

Citation

Thornton, S. T., Rex, A., & Hood, C. E. (2021). Modern Physics for Scientists and Engineers (5th ed.). Cengage Learning.

Chapter Summary

The fifth edition has 16 chapters. Cengage describes the book as taking a contemporary, comprehensive approach with a strong emphasis on applications, discussing the experiments that led to key discoveries in order to give students a historical perspective, and building a sound theoretical foundation in quantum theory for physics and engineering majors. The publisher also says the organization is flexible, so that topics can be taught in the instructor's preferred sequence.

Chapter 1: The Birth of Modern Physics

Six sections: classical physics of the 1890s, the kinetic theory of gases, waves and particles, conservation laws and fundamental forces, the atomic theory of matter, and the unresolved questions of 1895 with their new horizons.

Chapter 2: Special Theory of Relativity

A long chapter of fourteen sections: the apparent need for ether, the Michelson–Morley experiment, Einstein's postulates, the Lorentz transformation, time dilation and length contraction, addition of velocities, experimental verification, the twin paradox, spacetime, the Doppler effect, relativistic momentum and energy, computations in modern physics and electromagnetism and relativity.

Chapters 3–5: Experimental Basis of Quantum Physics; Structure of the Atom; Wave Properties of Matter and Quantum Mechanics I

Chapter 3 follows the discovery of the X-ray and the electron, line spectra, blackbody radiation, the photoelectric effect, X-ray production, the Compton effect and pair production. Chapter 4 moves from the Thomson and Rutherford models and Rutherford scattering to the Bohr model, its successes and failures, characteristic X-ray spectra and atomic excitation. Chapter 5 turns to wave properties: X-ray scattering, de Broglie waves, electron scattering, wave motion, the uncertainty principle, probability and the Copenhagen interpretation, and the particle in a box.

Chapters 6–8: Quantum Mechanics II; The Hydrogen Atom; Atomic Physics

Chapter 6 introduces the Schrödinger equation, expectation values, infinite and finite square wells, a three-dimensional well, the simple harmonic oscillator, and barriers and tunneling. Chapter 7 applies the equation to hydrogen, its solution, quantum numbers, the normal Zeeman effect, intrinsic spin and energy levels and electron probabilities. Chapter 8 covers atomic structure and the periodic table, total angular momentum and the anomalous Zeeman effect.

Chapters 9–11: Statistical Physics; Molecules and Solids; Semiconductor Theory and Devices

Chapter 9 begins with a historical overview and covers the Maxwell velocity and speed distributions, the equipartition theorem, classical and quantum statistics and the Fermi–Dirac and Bose–Einstein distributions. Chapter 10 treats molecular bonding and spectra, stimulated emission and lasers, the structural, thermal and magnetic properties of solids, superconductivity and its applications. Chapter 11 covers band theory, semiconductor theory and devices, and nanotechnology.

Chapters 12–14: The Atomic Nucleus; Nuclear Interactions and Applications; Particle Physics

Chapter 12 starts with the discovery of the neutron and covers nuclear properties, the deuteron, nuclear forces and stability, radioactive decay and radioactive nuclides. Chapter 13 covers nuclear reactions, reaction kinematics and mechanisms, fission and fission reactors, fusion and special applications. Chapter 14 covers early discoveries, the fundamental interactions, classification of particles, conservation laws and symmetries, quarks, the families of matter, physics beyond the Standard Model and accelerators.

Chapters 15–16: Modern Astrophysics and General Relativity; Cosmology: The Beginning and the End

Chapter 15 covers stellar evolution, galaxies and the discovery of dark matter, the tenets of general relativity and their tests, black holes and gravitational waves. Chapter 16 covers evidence for and the theory of the Big Bang, its problems, the age of the Universe, the standard model of cosmology and the future.

Key Concepts

Chapters 1–5: Foundations of Relativity and Quantum Physics

• Lorentz transformation: the relation between observations in different inertial frames.
• Time dilation and length contraction: the relativistic changes in measured time and length.
• Blackbody radiation and the photoelectric effect: experiments that required the quantization of light.
• Uncertainty principle: the limit on knowing certain pairs of quantities together.

Chapters 6–11: Quantum Mechanics Applied

• Schrödinger equation: the wave equation used for wells, oscillators, barriers and hydrogen.
• Quantum numbers and intrinsic spin: the labels that describe states in the hydrogen atom.
• Fermi–Dirac and Bose–Einstein statistics: the distributions for identical quantum particles.
• Band theory: the quantum account of solids and semiconductors.

Chapters 12–16: Nuclei, Particles, Astrophysics and Cosmology

• Fission and fusion: the two nuclear energy-releasing processes, with fission reactors treated separately.
• Quarks and the families of matter: the structure of the particle spectrum.
• General relativity and its tests: gravity as curved spacetime, with black holes and gravitational waves.
• Big Bang cosmology: evidence for the Big Bang and the standard model of cosmology.

Critical Analysis

Strengths

• Experiments in historical context. The publisher stresses the experiments behind each discovery, and the contents show it: Chapters 1, 3 and 4 spend their sections on discoveries, spectra and scattering experiments before wave mechanics begins.
• A sustained quantum foundation. The Schrödinger equation has its own chapter (6), followed by chapters on hydrogen and atomic physics, so the quantum mechanics that later chapters on molecules, solids and nuclei rely on is built up in stages.
• Broad but organized coverage. The 16 chapters include separate chapters on semiconductors and nanotechnology, nuclear reactions and applications, particle physics with accelerators, and astrophysics with general relativity and gravitational waves. The publisher says the sequence can be rearranged.
• Current topics. The fifth edition, which added Carol Hood as an author, is described as updated with the latest research, and the contents include gravitational waves and physics beyond the Standard Model.

Limitations

• Quantum mechanics arrives late. The Schrödinger equation does not appear until Chapter 6, after chapters on relativity, experimental quantum physics, atomic structure and matter waves. Instructors who want to reach it earlier have to use the flexible-sequence option and skip ahead.
• Introductory depth in the late chapters. Nuclear physics occupies two chapters, particle physics one, and astrophysics with general relativity one, so later courses are needed for any of these subjects.
• A compact atomic-physics chapter. Chapter 8 has three sections (atomic structure and the periodic table, total angular momentum, and the anomalous Zeeman effect), against seven in the corresponding chapter of Krane, so many-electron atoms and their applications are treated more briefly.

Where It Fits in the Course

This is a sophomore-level modern physics text and one of two in this course list, the other being Krane's Modern Physics. The two cover similar ground. Thornton, Rex and Hood give semiconductors, particle physics, and astrophysics with general relativity separate chapters and place statistical physics after atomic physics (Chapter 9); Krane places statistical physics after molecules and puts solids, including semiconductors, in a single chapter. Choose between them by the length of treatment preferred for those topics and the format available.

OpenStax's University Physics Volume 3 is a free, lighter route into relativity and quantum ideas, and Taylor and Wheeler's Spacetime Physics is a fuller treatment of special relativity than Chapter 2. For general relativity beyond Chapter 15, Schutz's A First Course in General Relativity is the advanced undergraduate step and Carroll's Spacetime and Geometry the graduate one.

How to Use This Book

The book is aimed at second-year physics and engineering students who have taken calculus-based introductory physics and calculus. Cengage says the fifth edition is exclusively available in an online eBook format, with an updated WebAssign course; check which format a course uses.

For a year-long course, follow the chapters in order. For one semester, cover Chapters 1–8 (relativity through atomic physics) and then choose from Chapters 9–11 (statistics, molecules, solids and semiconductors) and 12–16 (nuclei, particles, astrophysics, cosmology) to suit the department's emphasis. Chapter 1 serves as a review of late nineteenth-century physics and can be read quickly. Read the experimental chapters (3 and 4) before Chapters 5–7, since the book builds quantum theory from the experiments, and use the problems for practice: the WebAssign course lists general problems and supplemental multiple-choice questions for every chapter.