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Very Short Introductions #446
Light: A Very Short Introduction
Light enables us to see the world around us. Our sense of sight provides us with direct information about space and time, the physical arrangement of the world, and how it changes. This almost universal shared sensation of vision has led to a fascination with the nature and properties of light across the ages. But the light we see is just a small part of the whole spectrum of electromagnetic radiation, ranging from radio waves to gamma rays.In this Very Short Introduction Ian Walmsley discusses early attempts to explain light, and the development of apparently opposing particulate and wave theories by scientists such as Isaac Newton and Christiaan Huygens. He shows how light was recognized as an electromagnetic wave in the 19th century, and the development of the quantum mechanics view of wave-particle duality in the 20th century. He also describes the many applications of light, domestic and scientific, such asmicrowaves, DVDs, and lasers. We now use the whole range of electromagnetic radiation to peer both into the human body and deep into space. Turning to the future of optics, Walmsley concludes by looking at some of the most exciting new developments using quantum light sources in communications and computing.ABOUT THE The Very Short Introductions series from Oxford University Press contains hundreds of titles in almost every subject area. These pocket-sized books are the perfect way to get ahead in a new subject quickly. Our expert authors combine facts, analysis, perspective, new ideas, and enthusiasm to make interesting and challenging topics highly readable.
- GenresSciencePhysicsNonfiction
152 pages, Kindle Edition
First published July 21, 2015
About the author
Ian A. Walmsley
2 booksIan A. Walmsley FRS is Pro-Vice-Chancellor for Research and Hooke Professor of Experimental Physics at the University of Oxford, and a Professorial Fellow at St Hugh's College, Oxford. He is also Director of the NQIT (Networked Quantum Information Technologies) hub within the UK National Quantum Technology Programme, which is led by the University of Oxford.
Walmsley was educated at Imperial College London, and The Institute of Optics, University of Rochester. He was elected a Fellow of the Royal Society in 2012 for his contributions to quantum optics and ultrafast optics, including his development of the spectral phase interferometry for direct electric-field reconstruction (SPIDER) technique.
Walmsley was educated at Imperial College London, and The Institute of Optics, University of Rochester. He was elected a Fellow of the Royal Society in 2012 for his contributions to quantum optics and ultrafast optics, including his development of the spectral phase interferometry for direct electric-field reconstruction (SPIDER) technique.
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Displaying 1 - 10 of 10 reviews
November 1, 2015
It's fitting that light should be added as a topic to the OUP's growing range of mini-guides in 2015, as this is the International Year of Light (though, to be honest, the year seems to have been a nonstarter of an event). Light is a remarkable phenomenon and one that we rarely think about considering how big a part it plays in our lives.
Ian Walmsley begins by outlining the reasons why light is so important, over and above the mechanism of sight, and gives a very brief historical view of some of the ideas on the nature of light. I was not impressed by his characterisation of Roger Bacon as the 'mad friar of Oxford', but that apart, though fleeting, the historical section was a reasonable gallop through the topic.
For the rest of the content, Walmsley describes optics, light as particles, waves and as a duality in the form of a quantum field. He takes quite an unusual route in doing this and I think it would be easy for a non-technical reader to get somewhat lost along the way. There is quite a long section on special relativity, which, while light-related, is not really the topic of this book, but too little on some aspects of light itself, such as how its speed was first established and measured over the years before settling on the current exact figure. Given the weight that is put on the quantum field description of light, the explanation of quantum fields was too summary, given they remain outside the awareness of most readers.
So, a few key omissions and an approach that in some ways isn't ideal for an introductory guide, but still a solid little collection of material on the nature of light.
Ian Walmsley begins by outlining the reasons why light is so important, over and above the mechanism of sight, and gives a very brief historical view of some of the ideas on the nature of light. I was not impressed by his characterisation of Roger Bacon as the 'mad friar of Oxford', but that apart, though fleeting, the historical section was a reasonable gallop through the topic.
For the rest of the content, Walmsley describes optics, light as particles, waves and as a duality in the form of a quantum field. He takes quite an unusual route in doing this and I think it would be easy for a non-technical reader to get somewhat lost along the way. There is quite a long section on special relativity, which, while light-related, is not really the topic of this book, but too little on some aspects of light itself, such as how its speed was first established and measured over the years before settling on the current exact figure. Given the weight that is put on the quantum field description of light, the explanation of quantum fields was too summary, given they remain outside the awareness of most readers.
So, a few key omissions and an approach that in some ways isn't ideal for an introductory guide, but still a solid little collection of material on the nature of light.
January 3, 2019
Unlike many Very Short Introductions, this one was pretty readable. So much so that I found a few phrases and passages so eminently quotable that I copied them to a notebook for later enjoyment. The book discusses the history of research and science concerning light, particle-wave duality, optical communications and infrastructure, light's relationship to the Theory of Relativity, and discusses implications and oddities of quantum light. There is also a chapter on the cutting edge of research in the field of light, and how light is used in itself, and to build tools to support research in the cutting edge of physics and astrophysics.
Not a bad read.
Not a bad read.
November 11, 2017
Chapter 1: What is light?
Chapter 2: Light rays
Chapter 3: Waves
Chapter 4: Duality
Chapter 5: Light matters
Chapter 6: Light, space, and time
Chapter 7: Lighting the frontiers
Chapter 8: Quantum light
Chapter 9: Twilight
Chapter 2: Light rays
Chapter 3: Waves
Chapter 4: Duality
Chapter 5: Light matters
Chapter 6: Light, space, and time
Chapter 7: Lighting the frontiers
Chapter 8: Quantum light
Chapter 9: Twilight
February 22, 2019
couple of excerpts
"It was modified by Al-Hazen in the 11th century to a form that we now use routinely: objects are illuminated by rays from the Sun (the external fire) and are scattered towards the observer. There are several stories about how he came to this idea—including doing an experiment when he looked directly at the Sun, and determined that the painful sensation he experienced would be there all the time if the ‘internal fire’ were burning all the time. Thus, he argued, the source of the light necessary to generate the image was external.
Fermat’s conception was radically different. He argued that one should define the trajectory in terms of starting and ending points, as shown in Figure 21. He suggested that the question to ask is: what is the path that the light takes to traverse the space between the two points? He proposed that it should take the path that minimizes the time of flight between the two points. That this gives the same answer as Snell is remarkable and profound.
Fermat’s ‘principle of least time’ suggests that the light considers the overall picture of the situation, and that the notion of a ray is one that takes into account both the initial and final positions and directions as well as everything in between. The contrast with the local model of a particle reacting to its immediate environment is telling.
In 1908, George Taylor, working in Cambridge, performed Young’s double-slit experiment with exceptionally feeble light—so weak that on average there was less than one photon in the apparatus at any time. Yet he still saw interference fringes. That outcome is very strange. If we think of one path from the light source to the detector as being via one slit, and a second path via the other slit, then there are two ways that the photon can get from source to detector. The evidence of interference fringes posed a dilemma that caught the attention of the leading scientists of the day. Bohr captured the difficulty, noting that we would ‘be obliged to say, on the one hand, that the photon always chooses one of the two ways, and on the other that it behaves as if it passed through both’. Even single particles can exhibit wave-like behaviour. (less)
Another consequence of this fact is that ‘nothing’ is actually something.
The key is that they all involve matter. More specifically, they involve electric charges moving about. When these charges accelerate—that is, when they change their speed or their direction of motion—then a simple law of physics is that they emit light. Understanding this was one of the great achievements of the theory of electromagnetism. An electric field has its origin in an electric charge, such as an electron in an atom. The electric field, attracting oppositely charged particles, such as protons, extends throughout all space, although it gets weaker quite quickly as you move away from the electron. As I noted in Chapter 3, this is the force that arises from static electricity.
Light is the oldest thing we can see in the universe."
"It was modified by Al-Hazen in the 11th century to a form that we now use routinely: objects are illuminated by rays from the Sun (the external fire) and are scattered towards the observer. There are several stories about how he came to this idea—including doing an experiment when he looked directly at the Sun, and determined that the painful sensation he experienced would be there all the time if the ‘internal fire’ were burning all the time. Thus, he argued, the source of the light necessary to generate the image was external.
Fermat’s conception was radically different. He argued that one should define the trajectory in terms of starting and ending points, as shown in Figure 21. He suggested that the question to ask is: what is the path that the light takes to traverse the space between the two points? He proposed that it should take the path that minimizes the time of flight between the two points. That this gives the same answer as Snell is remarkable and profound.
Fermat’s ‘principle of least time’ suggests that the light considers the overall picture of the situation, and that the notion of a ray is one that takes into account both the initial and final positions and directions as well as everything in between. The contrast with the local model of a particle reacting to its immediate environment is telling.
In 1908, George Taylor, working in Cambridge, performed Young’s double-slit experiment with exceptionally feeble light—so weak that on average there was less than one photon in the apparatus at any time. Yet he still saw interference fringes. That outcome is very strange. If we think of one path from the light source to the detector as being via one slit, and a second path via the other slit, then there are two ways that the photon can get from source to detector. The evidence of interference fringes posed a dilemma that caught the attention of the leading scientists of the day. Bohr captured the difficulty, noting that we would ‘be obliged to say, on the one hand, that the photon always chooses one of the two ways, and on the other that it behaves as if it passed through both’. Even single particles can exhibit wave-like behaviour. (less)
Another consequence of this fact is that ‘nothing’ is actually something.
The key is that they all involve matter. More specifically, they involve electric charges moving about. When these charges accelerate—that is, when they change their speed or their direction of motion—then a simple law of physics is that they emit light. Understanding this was one of the great achievements of the theory of electromagnetism. An electric field has its origin in an electric charge, such as an electron in an atom. The electric field, attracting oppositely charged particles, such as protons, extends throughout all space, although it gets weaker quite quickly as you move away from the electron. As I noted in Chapter 3, this is the force that arises from static electricity.
Light is the oldest thing we can see in the universe."
June 4, 2023
Was expecting more on the visual acts of light — shadow, specularity, diffusion, color, reflection, refraction, caustics, vision, etc. While an abbreviated subset of these along with a brief history of optics forms the beginning of this book, instead almost half of the (admittedly small) book is dedicated to topics like computing the speed of light, special vs general relativity, and quantum light. These more theoretical topics related more to physics and weren’t relevant to my interests in light, and are quite well covered in other texts and websites. Caveat lector.
June 16, 2023
「當我們看著更遠的恆星和星系，其實是在窺探數十億年前的宇宙。在這個意義下，我們接收到的光也是數十億歲了。」
本書為我們闡明了光是什麼以及它能夠做什麼。 讓我們看見事物的光無所不在，從宇宙中遙遠的星系到我們體內的細胞，無一不仰賴光所賦予的能量，地球的能源主要來自太陽光，還有我們平常所呼吸的氧氣，產生的過程也是需要借助陽光的能量(光合作用)，若沒有太陽光，地球上的生命也許就不會出現了。
再來，光也促成了現代科技的發展，例如：我們最常使用的攝影工具(從前的底片相機就是藉由光線照射底片產生的化學反應才能顯影)，也因此讓我們得以紀錄當下看見的美好事物，影像對於我們如何認知世界有著舉足輕重的影響，大多數人應該無法想像沒有Netflix 和 YouTube 的生活吧🫣 我們每天使用的電腦、平板、手機，這些工具都是以光作為媒介，為我們帶來訊息並與他人聯繫，我們不得不承認，是”光”成就了現代便利的生活。
本書為我們闡明了光是什麼以及它能夠做什麼。 讓我們看見事物的光無所不在，從宇宙中遙遠的星系到我們體內的細胞，無一不仰賴光所賦予的能量，地球的能源主要來自太陽光，還有我們平常所呼吸的氧氣，產生的過程也是需要借助陽光的能量(光合作用)，若沒有太陽光，地球上的生命也許就不會出現了。
再來，光也促成了現代科技的發展，例如：我們最常使用的攝影工具(從前的底片相機就是藉由光線照射底片產生的化學反應才能顯影)，也因此讓我們得以紀錄當下看見的美好事物，影像對於我們如何認知世界有著舉足輕重的影響，大多數人應該無法想像沒有Netflix 和 YouTube 的生活吧🫣 我們每天使用的電腦、平板、手機，這些工具都是以光作為媒介，為我們帶來訊息並與他人聯繫，我們不得不承認，是”光”成就了現代便利的生活。
May 22, 2020
As always a very insightful and comprehensive introduction on a high scientific level. The book touches upon the most fascinating aspects of light: where it comes from, what it is, the wave-particle duality, what modern science can do with it. It is at times a bit hard to follow though and certainly not an “easy read” despite (or maybe rather because) it’s brevity.
September 2, 2018
О физике света, не самым простым языком, но в целом доступно.
August 15, 2024
En meget fin introduktion til lys. Det er dog meget koncentreret viden for en nybegynder til området og den er til tider svær at forstå.
June 15, 2025
Light and sweet.
Displaying 1 - 10 of 10 reviews