the physicist

Volume II of the Ask the Physicist books

I am pleased to announce the publication of the second volume of a series of books based on Q&As originally published on the site. This second volume, Atoms and Photons and Quanta, OH MY!, Ask the physicist about atomic, nuclear, and quantum physics, focuses on quantum physics and atomic and nuclear physics. Collected here are some of my favorite questions and answers, all organized with much added text to organize the material and tie it together. The book may be purchased online at Morgan & Claypool (publishers of the book), Amazon, or Barnes and Noble. A digital version for eReaders (epub format) is also available at Morgan & Claypool, a Kindle version is available at Amazon, and a Nook version is available at Barnes and Noble.


I am The Physicist! Since 2006 I have run a web site, www.AskThePhysicist.com, where I answer questions about physics. The site is not intended for answering highly technical questions; rather the purpose is to answer, with as little mathematics and formalism as possible, questions from intelligent and curious lay persons. For several years before my retirement from the University of Georgia I ran a similar Q&A site for the Department of Physics and Astronomy there. Over the last decade I have answered more than 5000 questions on line and uncounted more by brief email replies. I have found this very rewarding because it is an extension of my more than 40 years experience teaching and because I learn something new almost every day. The questions I receive reveal what aspects of physics interest people and what principles they do not grasp. They reveal a wide-spread thirst to understand how physics describes, on many levels, how our Universe works. It is gratifying that the site has on the order of 50–100 000 visits per month, far more than the number of questions asked; I interpret this to mean that there are many visits by people who simply like to read and learn.

This is the second book in the Ask the Physicist series. The first book, From Newton to Einstein, Ask the Physicist about Mechanics and Relativity, would provide an excellent foundation for this book; that is, it would be better if you read the two books in sequence. While it is certainly possible to get a lot out of this book without having read the first, be warned that some basic understanding of classical mechanics and the theories of special and general relativity are assumed for many concepts in this book.

Although this is a book about topics in ‘modern physics’, it is impossible to appreciate both the roots of quantum physics and its applications without having an understanding of the nature of light, or more generally electromagnetic radiation. And to understand the nature of light, an understanding of electricity and magnetism is needed. To that end, chapter 1 of this book will introduce the electromagnetic concepts required to understand the basics of light needed to understand the foundations of quantum physics.

The bulk of the book is devoted to chapters which will contain mainly categorized groups of Q&As from the web site, sort of a Best of Ask the Physicist. Enjoy and learn!




Author biography

1 Let there be light!

1.1 Introduction

1.2 History

1.3 What are force fields?

1.4 Electric and magnetic fields

1.5 Maxwell’s equations

2 Quanta and photons, oh my!

2.1 Prologue  

2.2 Introduction

2.3 Black-body radiation  

2.4 The photoelectric effect

2.5 Compton scattering  

2.6 de Broglie’s hypothesis

2.7 What’s waving?

2.8 The Heisenberg uncertainty principle

2.8.1 Introduction

2.8.2 The timbre of musical instruments

2.8.3 Fourier transforms and the uncertainty principle

3 Atoms, oh my!

3.1 Atomic sizes and masses

3.2 Atomic spectra

3.3 The discovery of the electron

3.4 Ernest Rutherford and the ‘nuclear model’

3.5 The Bohr model of the hydrogen atom

3.6 The modern atomic model 3

3.6.1 Solving Schrödinger’s equation for hydrogen

3.6.2 Spin and the Pauli exclusion principle

3.6.3 Atoms beyond hydrogen

3.6.4 More details of multi-electron atoms

4 Nuclear physics

4.1 Introduction

4.2 Discovery of the neutron

4.3 The nuclear force (the strong interaction)

4.4 Nuclear masses and binding energies

4.5 Nuclear systematics

4.6 Radioactivity

4.6.1 Introduction

4.6.2 Half-life

4.6.3 α-radiation

4.6.4 β-radiation

4.6.5 β+-radiation

4.6.6 γ-radiation

4.6.7 Spontaneous fission

4.6.8 Effects of radiation

4.7 Nuclear fission

4.7.1 Introduction

4.7.2 How to cause fission

4.7.3 How to keep fission going

4.7.4 How to control fission

4.7.5 Nuclear reactors

4.8 Nuclear fusion

4.9 The standard model

5 Epilogue

5.1 Ask the psychic

5.2 Off the wall hall of fame


A The constants of electricity and magnetism

B Energy  

C Elastic collisions

D Commonly used units

E The Schrödinger equation

F The Bohr model of hydrogen

G Detecting spin

H Chronology

I Miscellaneous calculations and