Physics: A Crash Course

Become An Instant Expert

Brian Clegg

• Publisher: Ivy Press
• Year: 2019
• Print ISBN: 9781782408673
• eBook ISBN: 9781782408680
• Topic: Physical Sciences
• Subtopic: Science History

Physics: A Crash Course is the quickest way to get up to speed with the most fundamental of the sciences.
 
Physics tells us how the universe works – it’s behind most of our exciting technology, from space rockets and satellites to cell phones, from electric cars to MRI scanners.
 
This book distils the current body of knowledge into 52 manageable chunks, allowing you to to skim-read or delve in a bit deeper. There are four chapters, each prefaced by a set of biographies of the leading physicists and timelines of key events in the history of physics:
 
• Matter & Light outlines the forms different matter can take and the qualities of light.
• Energy & Heat explores different types of energy, and the specific form of kinetic energy that is heat.
• Quantum Physics brings in the central structures and implications, and developments in quantum theory.
• Motion & Relativity outlines the concepts of mechanics and the other greater transformer of physics, relativity.
 
Taking you from inside an atom to the edge of the universe. What else could it be but a crash course in physics?
 
If you like this, you might also be interested in 30-Second Physics, 30-Second Quantum Physics and Quantum Theory: A Crash Course.

1
MATTER & LIGHT

“Do not Bodies and Light act mutually upon one another; that is to say, Bodies upon light in emitting, reflecting, refracting and inflecting it, and Light upon Bodies for heating them, and putting their parts into a vibrating motion wherein heat consists?”

ISAAC NEWTON, OPTICKS (1704)

INTRODUCTION

Until the middle of the nineteenth century, physics dealt with forces and gravity, light, electricity, and magnetism. It was about the way in which objects behaved, plus the insubstantial oddities of nature. Exploring the composition of substances was left to the chemists.

However, two nineteenth-century breakthroughs would ensure that physics took on a wider remit. The first was over the behavior of atoms and molecules in gases. Scottish physicist James Clerk Maxwell and German physicist Ludwig Boltzmann independently worked on what would become known as statistical mechanics, which described the behavior of gases by treating them as a statistical collection of many interacting particles. This made it possible to use basic physics to deduce many of the physical properties of matter made up from those particles.

Matter became even more part of the essence of physics when in the twentieth century quantum physics (see chapter 3) revealed the nature of atoms and their unique structure. It was realized that the way different elements formed chemical bonds was entirely dependent on the physics of the atomic structure. Even the periodic table, beloved of school chemistry labs and TV quizzes, would prove to be nothing more than a structural diagram of the layout of electrons in the outer layers of the atoms in question.

Heart of the matter

At its heart, physics is all about establishing the basics, the foundations. This is why the nature of matter has become a significant aspect of physics, while the details of the behavior of different chemicals is left to the chemists and biologists. An old joke, beloved of physicists emphasizes their focus on the fundamentals, which can lead to a surprising lack of detail.

A geneticist, a nutritionist, and a physicist are arguing about the best way to produce the perfect racehorse. The geneticist says: “Well, of course, it’s a matter of breeding stock. Getting the best line genetically, breeding the right animals with a perfect pedigree and getting the ideal outcome.” The nutritionist replies: “Of course I accept the importance of genetics, but in the end, it’s what you feed the horse that makes the difference between a winner and a loser.” The physicist smiles, shakes her head, turns to her whiteboard and starts to write an equation. “Let’s assume the racehorse is a sphere,” she says.

The components and makeup of matter, then, have become significant parts of the physics story. However, there is a reason why matter is linked together in this chapter with what appears to be a very different thing: light. We think of matter as far more tangible. Gases may seem at first glance to be similarly insubstantial as a beam of light—until we think of the impact of a hurricane, nothing more than moving gas. Crucially, all matter has mass, where light has none. However, since Einstein’s work, which we’ll come back to in more detail in the fourth chapter, the division between matter and light has become fuzzy at best. We know that matter (m) can be transformed into energy (E) and vice versa according to the relationship of E=mc2—and the form of energy involved in this transformation is light (c).

Linking light and matter

Although all of physics in some way influences our everyday lives, matter and light make up all of our experience. Our bodies and all the objects around us are made up of matter. Knowing more about the nature of the atoms within that matter, and how they are connected with bonds gives us a better picture of how everything around us functions.

Matter may seem to come in many different forms. And it’s been estimated that there are around 1080 atoms of matter in the universe—that’s 1 followed by 80 zeroes. Yet all that matter is made up of arrangements of atoms of around 100 different elements, themselves all formed from a handful of fundamental particles.

Light is also far more than “the thing that allows us to see.” All light produced after the big bang originates in matter. It is when matter loses energy, notably when an electron drops down to a lower energy level around an atom, that a photon of light is produced. In addition an invisible form of light acts as the carrier of the electromagnetic force, which means that pieces of matter don’t pass straight through each other. Light and matter are inextricably intertwined.

Physics is concerned at the fundamental level with what makes up matter, the different forms that matter can take, such as solids, liquids, and gases, and how the atoms within matter interact. When studying light, physics gives us insights into how light gets from place to place and how it interacts with matter. The late Stephen Hawking suggested you should “Look up at the stars and not down at your feet”—but in reality, physics encourages us to do both.

BIOGRAPHIES

JOHN DALTON (1766–1844)

Born in the north of England in 1766, John Dalton had a deep interest in the sciences but was barred from a traditional academic career as he was a Quaker. He picked up information where he could and at the age of 27 began to teach mathematics and science in Manchester. This lasted seven years until the college he worked for got into financial difficulties. Dalton became a private tutor, which remained his main source of income until receiving a government pension.

Dalton was active in the Manchester Literary and Philosophical Society, which encouraged him to explore subjects as wide as the nature of color blindness (he was color blind himself), the weather, and the behavior of gases. This last study inspired Dalton to think about the way that substances combined to make chemical compounds.

Over a number of years up to 1803, Dalton put together a theory of atomic behavior. Various elements made of tiny components called...

Table of contents

• Cover
• Title Page
• Contents
• Introduction
• 1 Matter & Light
• 2 Energy & Heat
• 3 Quantum Theory
• 4 Motion & Relativity
• Glossary
• Further Reading
• Index
• About the Author
• Acknowledgments
• Copyright