Contents -- Preface -- Acknowledgements -- Chapter 1 Introducing Light -- 1.1 The perception of light through the ages -- 1.1.1 The ancient Greeks -- 1.1.2 The Middle Ages -- 1.2 Colours -- 1.2.1 The visible spectrum -- 1.3 Measuring the speed of light -- 1.3.1 The astronomical method -- 1.3.2 Terrestrial measurement -- 1.3.3 The speed of light in context -- 1.4 The process of vision -- 1.4.1 'Look and see' -- 1.4.2 The journey of a photon -- 1.4.3 The eye is like a digital camera -- 1.4.4 Reconstructing the object -- 1.4.5 Why is the grass green? -- 1.4.6 Seeing in the dark -- 1.4.7 The branches of optics -- 1.5 The nature of light -- 1.5.1 Contradictory evidence -- 1.5.2 Light as a wave -- 1.5.3 Maxwell's electromagnetic waves -- 1.5.4 Light as a particle -- 1.5.5 An illustration of duality? -- 1.6 The birth of quantum mechanics -- 1.6.1 Particles have wave properties -- 1.6.2 The Copenhagen interpretation -- 1.6.3 The universal messenger -- Chapter 2 Geometrical Optics: Reflection -- 2.1 Fermat's law -- 2.1.1 Light takes the quickest route -- 2.1.2 The path in empty space -- 2.1.3 The quickest path via a reflection -- 2.1.4 The law of reflection -- 2.2 Mirrors -- 2.2.1 A plane mirror -- 2.2.2 Reversal from left to right -- 2.2.3 Reflection from a curved and uneven surface -- 2.2.4 A spherical concave mirror -- 2.2.5 Applications of concave mirrors -- 2.2.6 The 'death rays' of Archimedes -- A historical interlude: Pierre de Fermat (1601-1665) -- Appendix 2.1 The parabolic mirror -- Chapter 3 Geometrical Optics: Refraction -- 3.1 Refraction -- 3.1.1 The refractive index -- 3.1.2 The lifeguard problem -- 3.1.3 Snell's law -- 3.1.4 Apparent depth -- 3.1.5 The dilemma faced by light trying to leave glass -- 3.1.6 Practical applications of total internal reflection -- 3.1.7 Freedom of choice when a ray meets a boundary -- 3.1.8 The mystery.

3.1.9 A practical puzzle - two-way mirrors -- 3.2 Lenses -- 3.2.1 The function of a lens -- 3.2.2 Fermat's principle applied to lenses -- 3.3 Objects and images: converging lenses -- 3.3.1 Ray tracing through a thin lens -- 3.3.2 Principal rays (thin lenses) -- 3.3.3 The lens equation -- 3.3.4 Symmetry -- 3.3.5 Breaking the symmetry -- 3.3.6 An intuitive approach - the task of a lens -- 3.4 Objects and images: diverging lenses -- 3.5 Lens combinations -- 3.5.1 A general method -- 3.5.2 Examples - lenses in contact -- 3.5.3 The power of a lens -- 3.6 The eye -- 3.6.1 The structure of the eye -- 3.6.2 Common eye defects -- 3.7 Making visible what the eye cannot see -- 3.7.1 Distant objects -- 3.7.2 Nearer but not clearer -- 3.7.3 Angular magnification -- 3.8 Combinations of lenses -- 3.8.1 Compound microscopes -- 3.8.2 Telescopes -- 3.9 A final note on Fermat's principle -- Appendix 3.1 The lifeguard problem -- Appendix 3.2 The lens equation -- Appendix 3.3 Calculating the power of spectacles -- Chapter 4 Light from Afar - Astronomy -- 4.1 The earth -- 4.1.1 Is the earth round? -- 4.1.2 Philosophical reasons why the earth should be round -- 4.1.3 Experimental evidence that the earth is round -- 4.2 The Moon -- 4.2.1 The phases of the moon -- 4.2.2 A lunar eclipse -- 4.2.3 A solar eclipse -- 4.3 Sizes and distances -- 4.3.1 Relative sizes of the sun and the moon -- 4.3.2 The shadow of the earth on the moon -- 4.3.3 Shrinking shadows -- 4.3.4 The distance to the moon -- 4.3.5 The distance to the sun -- 4.3.6 A practical problem -- 4.3.7 A summary concerning the earth, moon and sun -- 4.3.8 Astronomical distances -- 4.4 The planets -- 4.4.1 The 'wanderers' -- 4.4.2 Ptolemy's geocentric model -- 4.5 The Copernican revolution -- 4.5.1 Frames of reference -- 4.5.2 Copernicus and the heliocentric model -- 4.5.3 Where did the epicycles come from?.

4.6 After Copernicus -- 4.7 The solar system in perspective -- A historical interlude: Galileo Galilei (1564-1642) -- Appendix 4.1 Mathematics of the ellipse -- Chapter 5 Light from the Past - Astrophysics -- 5.1 The birth of astrophysics -- 5.1.1 Isaac Newton and gravitation -- 5.1.2 Falling without getting nearer -- 5.1.3 The mystery of gravitation -- 5.1.4 Newton's law of gravitation -- 5.1.5 Testing the law -- 5.1.6 Acceleration of the moon towards the earth -- 5.1.7 The period of the moon's orbit -- 5.1.8 Explanation of Kepler's laws -- 5.2 The methods of astrophysics -- 5.2.1 The moon and the falling apple -- 5.2.2 Predicting the existence of new planets -- 5.3 Other stars and their 'solar systems' -- 5.3.1 Planets of other suns -- 5.3.2 Other galaxies -- 5.4 Reconstructing the past -- 5.4.1 The steady state cosmological model -- 5.4.2 The 'big bang' theory -- 5.4.3 A blast from the past -- 5.5 The life and death of a star -- 5.5.1 White dwarfs -- 5.5.2 Supernovae -- 5.5.3 Pulsars -- 5.5.4 Black holes -- 5.5.5 Escape velocities -- 5.5.6 How to 'see' the invisible -- 5.5.7 A strange event in the Milky Way -- 5.5.8 Time stands still -- A historical interlude: Isaac Newton (1642-1727) -- Appendix 5.1 Kepler's third law, derived from Newton's law of universal gravitation -- Appendix 5.2 Escape velocity -- Chapter 6 Introducing Waves -- 6.1 Waves - the basic means of communication -- 6.1.1 Mechanical waves in a medium -- 6.1.2 Transverse waves -- 6.1.3 Longitudinal waves -- 6.2 The mathematics of a travelling wave -- 6.2.1 The making of a wave -- 6.2.2 From the sine of an angle to the picture of a wave -- 6.2.3 An expression for a sine wave in motion -- 6.2.4 Wave parameters -- 6.3 The superposition of waves -- 6.3.1 The superposition principle -- 6.4 Applying the superposition principle.

6.4.1 The superposition of two waves travelling in the same direction -- 6.4.2 Path difference and phase difference -- 6.4.3 When two waves travelling in opposite directions meet -- 6.4.4 A string fixed at both ends -- 6.4.5 Standing waves -- 6.5 Forced oscillations and resonance -- 6.5.1 Forced oscillations -- 6.5.2 Natural frequencies of vibration and resonance -- 6.6 Resonance - a part of life -- 6.6.1 The Tacoma Narrows bridge disaster -- 6.6.2 The Mexico City earthquake -- 6.7 Diffraction - waves can bend around corners -- 6.8 The magic of sine and the simplicity of nature -- 6.8.1 The sum of a number of sine waves -- A historical interlude: Jean Baptiste Joseph Fourier (1768-1830) -- Appendix 6.1 The speed of transverse waves on a string -- Appendix 6.2 Dimensional analysis -- Appendix 6.3 Calculation of the natural frequencies of a string fixed at both ends -- Chapter 7 Sound Waves -- 7.1 Sound and hearing -- 7.1.1 Sound as a pressure wave -- 7.1.2 The speed of sound -- 7.1.3 Ultrasound and infrasound -- 7.2 Sound as a tool -- 7.3 Superposition of sound waves -- 7.3.1 Standing waves -- 7.3.2 Beats -- 7.4 Sound intensity -- 7.4.1 Real and perceived differences in the intensity of sound -- 7.4.2 Quantifying perception -- 7.4.3 Intensity level (loudness) -- 7.4.4 The 'annoyance factor' -- 7.5 Other sensations -- 7.5.1 Pitch -- 7.5.2 Tone quality -- 7.5.3 Propagation of sound in open and confined spaces -- 7.6 Strings and pipes in music -- 7.7 The Doppler effect -- 7.7.1 A moving observer -- 7.7.2 A moving source -- 7.7.3 Two Doppler effects? -- 7.7.4 Moving away from a source at almost the speed of sound -- 7.7.5 Shock waves -- 7.7.6 Shock waves and light -- A historical interlude: The sound barrier -- Appendix 7.1 Derivation of Doppler frequency changes -- Chapter 8 Light as a Wave -- 8.1 Light as a wave -- 8.1.1 The mystery of waves in nothing.

8.2 Wave properties which do not make reference to a medium -- 8.2.1 Superposition -- 8.2.2 Huygens' principle -- 8.2.3 Huygen's principle and refraction -- 8.2.4 Diffraction -- 8.2.5 Huygens' principle and diffraction -- 8.3 Specifically light -- 8.3.1 Diffraction of light -- 8.3.2 The experiment with light -- 8.3.3 Other apertures -- 8.3.4 The curious case of the opaque disc -- 8.4 Is there a limit to what we can distinguish? -- 8.4.1 Images may overlap -- 8.4.2 The Rayleigh criterion -- 8.5 Other electromagnetic waves -- 8.5.1 Message from the stars -- 8.5.2 Other windows on the universe -- 8.6 Light from two sources -- 8.6.1 Young's experiment -- 8.6.2 A pattern within a pattern -- 8.7 Interference as a tool -- 8.7.1 The Michelson interferometer -- 8.8 Thin films -- 8.8.1 Newton's rings -- 8.8.2 Non-reflective coatings -- 8.9 Diffraction gratings -- 8.9.1 Practical diffraction gratings -- 8.9.2 Compact discs -- 8.10 Other 'lights' -- 8.10.1 X-ray diffraction -- 8.10.2 Electron diffraction -- 8.11 Coherence -- 8.11.1 The question of phase -- 8.12 Polarisation -- 8.12.1 Polarisation of electromagnetic waves -- 8.12.2 What happens to light as it passes through a polaroid? -- 8.12.3 Polarisation by reflection -- A historical interlude: Thomas Young (1773-1829) -- Appendix 8.1 Single slit diffraction -- Appendix 8.2 Reflectance of thin films -- Chapter 9 Making Images -- 9.1 Creating images -- 9.1.1 Photography -- 9.1.2 History of the photograph -- 9.1.3 Nuclear photographic emulsion -- 9.1.4 Interpretation of photographic images -- 9.2 Holography -- 9.2.1 The inventor -- 9.2.2 The principle -- 9.2.3 Making a hologram -- 9.2.4 Why does a holographic image look so real? -- 9.2.5 Applications of holography -- Chapter 10 There Was Electricity, There Was Magnetism, and Then There Was Light … -- 10.1 The mystery of 'action at a distance'.

10.1.1 The gravitational force.