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Light: A Radiant History from Creation to the Quantum Age

Light: A Radiant History from Creation to the Quantum Age

“As familiar as our own faces, light is the first thing we see at birth, the last thing before dying.” - Bruce Watson

If there is one aspect of the natural world that is both omnipresent and mysterious, it is light. Formless, yet fulfilling, it saturates every aspect of human existence, both metaphorically and literally. By being so consistent, that we barely take notice of it. We might curse its absence when we stub a toe in a dark room. In a dark street or urban setting we might wish we had more of it, feeling that ancient tingle of fear at what shadows hide. However, do we really stop to regard it? To wonder at how our relationship with light has changed. To ask how much it defines our place in the universe. 

Having once studied astrophysics, I am familiar with the scientific study of light, but I hasn’t really thought of light as a topic in and of itself. That is, until I recently read Light by the journalist and writer Bruce Watson. It is an eloquent and focused journey through humankind’s relationship with light. Though it seems he is a frequent writer for the Smithsonian, I’d never encountered his work until now. I am the better for it. 

It seems a popular trend at the moment in non-fiction to follow a single subject across different time periods and contexts. So popular that it may have become a cliché. That isn’t to say it isn’t interesting. Personally, I find these topic-centric pieces of non-fiction are the ones that make me look at society differently. Light follows the story of light in a roughly chronological order, from humankind’s early mystical relationships with light to its most recent technological advantages. 

Like any topic focused work, there is a risk that every aspect of human history becomes bent through the lens of the topic in focus. However, with light, this obsession seems warranted. Light is the basis of our visual arts, our science, technologies, culture. After all, we are a visual species. 

I expected a grand tour through light’s impact on our history. What I didn’t expect what how much of a human story lives beneath our journey to understand light. Originally, our explanations were usually mystical. 

“Because all good came from it and most evil came from its absence, primitive people did not study light - they worshipped it. Envisioning light’s birth, our distant ancestors called on myth and miracle.” - Bruce Watson

The ancient world build totemic circles, statues and monuments to chart the seasons, often with unexpected accuracy. Advances in their knowledge in how light fell would not only help them in their quest to worship it, but also increase their chances of success in early forms of agriculture and finding the right game. 

Though the ancient philosophers like Socrates, Plato and Aristotle all explored light, I was most taken with Bruce Watson’s account of a lesser known Arabic scholar, Al Hacen. Known by a variety of names (Al Hacen, Ibn al-Haytham, Alhazen) he once spent a decade pretending to be mad to avoid being executed by a Pharaoh of Egypt. Finally safely ensconced in Cairo, at nearly the end of his life, he began to experiment with light, stripping back the mysticism with the earliest scientific method. 

“Alone in a dark mausoleum, a slight man, grey bearded and wearing a large turban, lays a small rug on the dirt floor. Kneeling, he bows his head to the ground and says prayers too Allah. Then he begins his experiments. He closes all windows, allowing a beam of light to enter through a hole bored in a shutter… The single shaft pierces the darkness, then begins to do the old man’s bidding. He places object after object in the beam. He charts each shadow […]” - Bruce Watson

From Arabia, the exploration of light moved back into the West as Europe began its long climb out of the Middle Ages towards the rise of science. Galileo, Grosseteste, Bacon and others all worked on light. However, it wasn’t until Newton began his work on optics that the world changed. Hiding in his country house, far from plague-ridden Oxford, with the company of a few basic tools; a dark room, prisms and the like. Newton is regarded by many for his thinking motion and gravity. However, his ideas about light would change the world.  Unfortunately, there is a deeply human element about how science proceeds. A bitter feud with fellow Royal Academy member Robert Hooke kept Newton from making his revolutionary theories on light more widely known until Hooke died. 

“Newton spent the summer of 1672 in the countryside. He had made more optical discoveries but now he withheld them. His revolutionary theory about light, debated by just a handful of curious men, would not reach the rest of the world for another three decades. Hooke, ordered to reconsider Newton’s original paper, suggested to his rival that they correspond in private. Newton agreed, but the feud was far from finished.” - Bruce Watson

It wasn’t until the strange pairing of the charismatic self-taught Michael Faraday and the quieter mathematical genius of James Clerk Maxwell that light began to emerge from its rather secluded place in the scientific world, to a shared endeavour between students of physics, optics, math and other related disciplines. 

“With Michael Faraday and James Clerk Maxwell, the narrow paths paved by light's earlier students began to broaden. The self-absorption of the pre-Socratics, the monastic focus of Robert Grosseteste and Roger Bacon, the bitter rivalry of Newton and Hooke, the contests between Fresnel and the French Académie - each phase had run its course. There would still be the usual academic jousting, and the fierce competition of those trying to make fortunes from light, but on into the twentieth century, physicists examination of ’this thing called light’ would share their discoveries.” - Bruce Watson

The foundational work by Faraday and Maxwell did more to set the scene for seeing light, not just as one aspect of our physical world, but a key part of the entire electromagnetic spectrum. It wasn’t just about the light we can see, but a much larger spectrum of energy, from the massively short gamma radiation to the long waves far beyond the visible spectrum. 

Only with Einstein did we fully realise to what extent light and its limitations defines our very understanding of space, time and causality. Based on Einstein’s work we realised that nothing travels faster then light, which forces time to bend and flex according to our velocity. It is a slippery concept, but time itself becomes subjugated to light. 

Then, of course, there is the technological element to all of this. The wars between Westinghouse and Edison dwarfed the many innovators in the field of lighting, including Maxim (of machine gun fame), Swann and Sawyer. Edison lit the world, not by labouring by himself, but by making innovation a process. 

“No solitary genius toiling in a dark chamber, Edison had gathered the East Coast’s best engineers, who he called his ‘muckers,’ in his laboratory in Menlo Park, New Jersey. From this greatest of all his inventions, the research and development lab […]” - Bruce Watson

Light powers our internet, information storage, healthcare, satellites, science and so much more. Our hunger for more light drowns our the very skies that we use to gaze in awe upon. 

“Cheaper, brighter, ubiquitous LEDs are turning a world that once shuddered at sunset into a world that conquers darkness with ease. Still, you don’t have to be a romantic poet to wonder. Is light, to paraphrase Wordsworth, “too much with us now.’” - Bruce Watson

Yet, in all of this there is a strange irony. Light is the beautiful warmth that paints a landscape orange in a sunset. It warms us, powers more of our world via solar energy. However, the more we know about it, the less we understand. Light has been shown to have properties of both a particle, wave or packet of energy (quanta) depending on its context.  

“If there is a final answer to the question “What is light?” - the answer Galileo dreamt of, the answer Einstein never stopped seeking - we have not found it. The search itself is eternal, spiralling back to the source.” - Bruce Watson

Bruce Watson doesn’t provide the definite answer. However, in his long journey through charting our changing relationship with light, he certainly makes the point that our hunger to know more, to understand, is the defining force in where light takes us next. A reminder that even the most omnipresent of natural forces has many secrets yet to reveal. 

References

Eyewitness (2007) Great Scientists. DK: Great Britain.

Watson, Bruce (2016) Light: A Radiant History from Creation to the Quantum Age. Bloomsbury. United States. 

Light Photo by Vincent van Zalinge on Unsplash

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