Brain Pickings

Censorship and What Freedom of Speech Really Means: Comedian Bill Hicks’s Brilliant Letter to a Priest


“‘Freedom of speech’ means you support the right of people to say exactly those ideas which you do not agree with.”

In early June of 1993, several months before cancer took his life at the age of thirty-two, beloved comedian Bill Hicks received a letter from a priest, bemoaning the “blasphemous” content in Hicks’s live television special Revelations and reprimanding British broadcaster Channel 4 for having put it on the air. Writing a mere eight days before his fatal pancreatic cancer diagnosis — a young man still oblivious to his imminent tragic fate — Hicks decided to respond to the missive personally, in what became one of the most lucid and beautiful defenses of the freedom of speech ever articulated, on par with Voltaire’s piercing admonition about censorship and Madeleine L’Engle’s timeless words on the subject.

From Letters of Note: Correspondence Deserving of a Wider Audience (public library) — the same wonderful compendium by Shaun Usher that gave us young Hunter S. Thompson on how to live a meaningful life, E.B. White’s heartening response to a man who had lost faith in humanity, and Eudora Welty’s impossibly charming lesson in how to apply to your dream job — comes Hicks’s brilliant, thoughtful, and immeasurably important response.

Hicks writes:

Dear Sir,

After reading your letter expressing your concerns regarding my special ‘Revelations’, I felt duty-bound to respond to you myself in hopes of clarifying my position on the points you brought up, and perhaps enlighten you as to who I really am. Where I come from — America — there exists this wacky concept called ‘freedom of speech’, which many people feel is one of the paramount achievements in mankind’s mental development. I myself am a strong supporter of the ‘Right of freedom of speech’, as I’m sure most people would be if they truly understood the concept. ‘Freedom of speech’ means you support the right of people to say exactly those ideas which you do not agree with. (Otherwise, you don’t believe in ‘freedom of speech’, but rather only those ideas which you believe to be acceptably stated.) Seeing as how there are so many different beliefs in the world, and as it would be virtually impossible for all of us to agree on any one belief, you may begin to realize just how important an idea like ‘freedom of speech’ really is. The idea basically states ‘while I don’t agree or care for what you are saying, I do support your right to say it, for herein lies true freedom.

It’s worth pausing here to note that in the DNA of the Christian Church, as an institution, is a compulsion to do precisely the opposite — to suppress the views that contradict its dogmas. One need only look to Galileo’s trails to appreciate how far back and how deeply these foundations of power-maintenance through censorship run. (But, of course, there’s always Flannery O’Connor to clarify the difference between dogmatic religion and faith.)

With his characteristic blend of snark and keen cultural insight, Hicks continues:

While I’ve found many of the religious shows I’ve viewed over the years not to be to my liking, or in line with my own beliefs, I’ve never considered it my place to exert any greater type of censorship than changing the channel, or better yet — turning off the TV completely.

Hicks moves on to the part of the letter that disturbed him the most:

In support of your position of outrage, you posit the hypothetical scenario regarding the possibly ‘angry’ reaction of Muslims to material they might find similarly offensive. Here is my question to you: Are you tacitly condoning the violent terrorism of a handful of thugs to whom the idea of ‘freedom of speech’ and tolerance is perhaps as foreign as Christ’s message itself? If you are somehow implying that their intolerance to contrary beliefs is justifiable, admirable, or perhaps even preferable to one of acceptance and forgiveness, then I wonder what your true beliefs really are.

If you had watched my entire show, you would have noticed in my summation of my beliefs the fervent plea to the governments of the world to spend less money on the machinery of war, and more on feeding, clothing, and educating the poor and needy of the world … A not-so-unchristian sentiment at that!

Ultimately, the message in my material is a call for understanding rather than ignorance, peace rather than war, forgiveness rather than condemnation, and love rather than fear. While this message may have understandably been lost on your ears (due to my presentation), I assure you the thousands of people I played to in my tours of the United Kingdom got it.

Whether or not the priest himself got it, even after the letter, is another story open for speculation.

Letters of Note is a spectacular collection in its entirety, featuring opinionated, vulnerable, beautiful, blunt, and deeply human contributions from such luminaries as Virginia Woolf, Roald Dahl, Richard Feynman, Jack Kerouac, Emily Dickinson, Flannery O’Connor, Leonardo da Vinci, and more. Sample three of my favorites here, here, and here. Usher continues to dig up even more gems and to share them on Letters of Note, one of the most wonderful corners of the internet.

You can watch Hicks’s Revelations below. It, along with the rest of his legacy, can be found on this essential collection of his work.

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Rethinking the Placebo Effect: How Our Minds Actually Affect Our Bodies


The startling physiological effects of loneliness, optimism, and meditation.

In 2013, Neil deGrasse Tyson hosted a mind-bending debate on the nature of “nothing” — an inquiry that has occupied thinkers since the dawn of recorded thought and permeates everything from Hamlet’s iconic question to the boldest frontiers of quantum physics. That’s precisely what New Scientist editor-in-chief Jeremy Webb explores with a kaleidoscopic lens in Nothing: Surprising Insights Everywhere from Zero to Oblivion (public library | IndieBound) — a terrific collection of essays and articles exploring everything from vacuum to the birth and death of the universe to how the concept of zero gained wide acceptance in the 17th century after being shunned as a dangerous innovation for 400 years. As Webb elegantly puts it, “nothing becomes a lens through which we can explore the universe around us and even what it is to be human. It reveals past attitudes and present thinking.”

Among the most intensely interesting pieces in the collection is one by science journalist Jo Marchant, who penned the fascinating story of the world’s oldest analog computer. Titled “Heal Thyself,” the piece explores how the way we think about medical treatments shapes their very real, very physical effects on our bodies — an almost Gandhi-like proposition, except rooted in science rather than philosophy. Specifically, Marchant brings to light a striking new dimension of the placebo effect that runs counter to how the phenomenon has been conventionally explained. She writes:

It has always been assumed that the placebo effect only works if people are conned into believing that they are getting an actual active drug. But now it seems this may not be true. Belief in the placebo effect itself — rather than a particular drug — might be enough to encourage our bodies to heal.

She cites a recent study at the Harvard Medical School, in which people with irritable bowel syndrome were given a placebo and informed that the pills were “made of an inert substance, like sugar pills, that have been shown in clinical studies to produce significant improvement in IBS symptoms through mind-body self-healing processes.” As Marchant notes, this is absolutely true, in a meta kind of way. What the researchers found was startling in its implications for medicine, philosophy, and spirituality — despite being aware they were taking placebos, the participants rated their symptoms as “moderately improved” on average. In other words, they knew what they were taking wasn’t a drug — it was a medical “nothing” — but the very consciousness of taking something made them experience fewer symptoms.

Illustration by Marianne Dubuc from 'The Lion and the Bird.' Click image for more.

This dovetails into recent research confirming what Helen Keller fervently believed by putting some serious science behind the value of optimism. Marchant sums up the findings:

Realism can be bad for your health. Optimists recover better from medical procedures such as coronary bypass surgery, have healthier immune systems and live longer, both in general and when suffering from conditions such as cancer, heart disease and kidney failure.

It is well accepted that negative thoughts and anxiety can make us ill. Stress — the belief that we are at risk — triggers physiological pathways such as the “fight-or-flight” response, mediated by the sympathetic nervous system. These have evolved to protect us from danger, but if switched on long-term they increase the risk of conditions such as diabetes and dementia.

What researchers are now realizing is that positive beliefs don’t just work by quelling stress. They have a positive effect too — feeling safe and secure, or believing things will turn out fine, seems to help the body maintain and repair itself…

Optimism seems to reduce stress-induced inflammation and levels of stress hormones such as cortisol. It may also reduce susceptibility to disease by dampening sympathetic nervous system activity and stimulating the parasympathetic nervous system. The latter governs what’s called the “rest-and-digest” response — the opposite of fight-or-flight.

Just as helpful as taking a rosy view of the future is having a rosy view of yourself. High “self-enhancers” — people who see themselves in a more positive light than others see them — have lower cardiovascular responses to stress and recover faster, as well as lower baseline cortisol levels.

Marchant notes that it’s as beneficial to amplify the world’s perceived positivity as it is to amplify our own — something known as our “self-enhancement bias,” a type of self-delusion that helps keep us sane. But the same applies to our attitudes toward others as well — they too can impact our physical health. She cites University of Chicago psychologist John Cacioppo, who has dedicated his career to studying how social isolation affects individuals. Though solitude might be essential for great writing, being alone a special form of art, and single living the defining modality of our time, loneliness is a different thing altogether — a thing Cacioppo found to be toxic:

Being lonely increases the risk of everything from heart attacks to dementia, depression and death, whereas people who are satisfied with their social lives sleep better, age more slowly and respond better to vaccines. The effect is so strong that curing loneliness is as good for your health as giving up smoking.

Illustration by Marianne Dubuc from 'The Lion and the Bird.' Click image for more.

Marchant quotes another researcher, Charles Raison at Atlanta’s Emory University, who studies mind–body interactions:

It’s probably the single most powerful behavioral finding in the world… People who have rich social lives and warm, open relationships don’t get sick and they live longer.

Marchant points to specific research by Cacioppo, who found that “in lonely people, genes involved in cortisol signaling and the inflammatory response were up-regulated, and that immune cells important in fighting bacteria were more active, too.” Marchant explains the findings and the essential caveat to them:

[Cacioppo] suggests that our bodies may have evolved so that in situations of perceived social isolation, they trigger branches of the immune system involved in wound healing and bacterial infection. An isolated person would be at greater risk of physical trauma, whereas being in a group might favor the immune responses necessary for fighting viruses, which spread easily between people in close contact.

Crucially, these differences relate most strongly to how lonely people think they are, rather than to the actual size of their social network. That also makes sense from an evolutionary point of view, says Cacioppo, because being among hostile strangers can be just as dangerous as being alone. So ending loneliness is not about spending more time with people. Cacioppo thinks it is all about our attitude to others: lonely people become overly sensitive to social threats and come to see others as potentially dangerous. In a review of previous studies … he found that tackling this attitude reduced loneliness more effectively than giving people more opportunities for interaction, or teaching social skills.

Illustration by André François for 'Little Boy Brown,' a lovely vintage ode to childhood and loneliness. Click image for more.

Paradoxically, science suggests that one of the most important interventions to offer benefits that counter the ill effects of loneliness has to do with solitude — or, more precisely, regimented solitude in the form of meditation. Marchant notes that trials on the effects of meditation have been small — something I find troublesomely emblematic of the short-sightedness with which we approach mental health as we continue to prioritize the physical in both our clinical subsidies and our everyday lives (how many people have a workout routine compared to those with a meditation practice?); even within the study of mental health, the vast majority of medical research focuses on the effects of a physical substance — a drug of some sort — on the mind, with very little effort directed at understanding the effects of the mind on the physical body.

Still, the modest body of research on meditation is heartening. Marchant writes:

There is some evidence that meditation boosts the immune response in vaccine recipients and people with cancer, protects against a relapse in major depression, soothes skin conditions and even slows the progression of HIV. Meditation might even slow the aging process. Telomeres, the protective caps on the ends of chromosomes, get shorter every time a cell divides and so play a role in aging. Clifford Saron of the Center for Mind and Brain at the University of California, Davis, and colleagues showed in 2011 that levels of an enzyme that builds up telomeres were higher in people who attended a three-month meditation retreat than in a control group.

As with social interaction, meditation probably works largely by influencing stress response pathways. People who meditate have lower cortisol levels, and one study showed they have changes in their amygdala, a brain area involved in fear and the response to threat.

If you’re intimidated by the time investment, take heart — fMRI studies show that as little as 11 hours of total training, or an hour every other day for three weeks, can produce structural changes in the brain. If you’re considering dipping your toes in the practice, I wholeheartedly recommend meditation teacher Tara Brach, who has changed my life.

But perhaps the most striking finding in exploring how our beliefs affect our bodies has to do with finding your purpose and, more than that, finding meaning in life. The most prominent studies in the field have defined purpose rather narrowly, as religious belief, but even so, the findings offer an undeniably intriguing signpost to further exploration. Marchant synthesizes the research, its criticism, and its broader implications:

In a study of 50 people with advanced lung cancer, those judged by their doctors to have high “spiritual faith” responded better to chemotherapy and survived longer. More than 40 percent were still alive after three years, compared with less than 10 percent of those judged to have little faith. Are your hackles rising? You’re not alone. Of all the research into the healing potential of thoughts and beliefs, studies into the effects of religion are the most controversial.

Critics of these studies … point out that many of them don’t adequately tease out other factors. For instance, religious people often have lower-risk lifestyles and churchgoers tend to enjoy strong social support, and seriously ill people are less likely to attend church.


Others think that what really matters is having a sense of purpose in life, whatever it might be. Having an idea of why you are here and what is important increases our sense of control over events, rendering them less stressful. In Saron’s three-month meditation study, the increase in levels of the enzyme that repairs telomeres correlated with an increased sense of control and an increased sense of purpose in life. In fact, Saron argues, this psychological shift may have been more important than the meditation itself. He points out that the participants were already keen meditators, so the study gave them the chance to spend three months doing something important to them. Spending more time doing what you love, whether it’s gardening or voluntary work, might have a similar effect on health. The big news from the study, Saron says, is “the profound impact of having the opportunity to live your life in a way that you find meaningful.”

Philosopher Daniel Dennett was right all along in asserting that the secret of happiness is to “find something more important than you are and dedicate your life to it.”

Each of the essays in Nothing: Surprising Insights Everywhere from Zero to Oblivion is nothing short of fascinating. Complement them with theoretical physicist Lawrence Krauss on the science of “something” and “nothing.”

Donating = Loving

Bringing you (ad-free) Brain Pickings takes hundreds of hours each month. If you find any joy and stimulation here, please consider becoming a Supporting Member with a recurring monthly donation of your choosing, between a cup of tea and a good dinner.

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A Brief History of Glass and How It Planted the Seed for the Innovation Gap Between the East and West


“The material world is not just a display of our technology and culture, it is part of us. We invented it, we made it, and in turn it makes us who we are.”

By 1950, Picasso was already an artist world-renowned for his creative products — paintings, sculptures, bronze casts — but only those in his inner circle had a true appreciation of the magic in his process. It wasn’t until a documentary captured him painting on glass, with the camera rolling on the other side of his transparent canvas — a radical proposition at the time — that the world gasped at his breathtaking process. Such was the power of glass.

In Stuff Matters: Exploring the Marvelous Materials that Shape Our Man-Made World (public library), British materials scientist, engineer and educator Mark Miodownik sets out to “decipher the material world we have constructed and find out where these materials came from, how they work, and what they say about us,” stripping them down to the elemental human desire that brought each of them into being and exploring how the material science that produced them affects the broader context of our lives. Miodownik paints the backdrop:

This stuff is important. Take away the concrete, the glass, the textiles, the metal, and the other materials from the scene, and I am left naked, shivering in midair. We may like to think of ourselves as civilized, but that civilization is in large part bestowed by material wealth… The material world is not just a display of our technology and culture, it is part of us. We invented it, we made it, and in turn it makes us who we are.

Picasso paints on glass, 1950. Click image for more.

One of the most interesting, and unexpectedly so, materials he examines is glass — a substance so ubiquitous in modern life and yet, at its best, so invisible. Duality and paradox, in fact, seem to be baked into the very nature of glass — quite literally. Before he plunges into the meaty interestingness of this singular material and its cultural history, Miodownik explains the no less interesting basic science of how sand becomes glass — one of the most remarkable transmutations in the observable physical universe:

Sand is a mixture of tiny bits of stone that have fallen off larger bits of rock as a result of the wind and the waves and other wear and tear that stones have to put up with. If you take a close look at a handful of sand you will find that a lot of these bits of stone are made of quartz, a crystal form of silicon dioxide. There is a lot of quartz in the world because the two most abundant chemical elements in the Earth’s crust are oxygen and silicon, which react together to form silicon dioxide molecules (SiO2). A quartz crystal is just a regular arrangement of these SiO2 molecules, in the same way that an ice crystal is a regular arrangement of H2O molecules or iron is a regular arrangement of iron atoms. Heating up quartz gives the SiO2 molecules energy and they vibrate, but until they reach a certain temperature they won’t have enough energy to break the bonds that hold them to their neighbors. This is the essence of being a solid. If you keep heating them, though, their vibrations will eventually reach a critical value — their melting point — at which they have enough energy to break those bonds and jump around quite chaotically, becoming liquid SiO2. H2O molecules do the same thing when ice crystals are melted, becoming liquid water.

But here’s the rub — when you put that liquid water into the freezer, it has no trouble refreezing into ice crystals. And you can do it again and again, melting and freezing into oblivion. Unlike water, however, SiO2 has a hard time forming a crystal once cooled down — it’s almost as if the molecules forget how to assemble into that formation. (There is a fascinating Radiolab episode about this notion.) What’s more, to stay with the anthropomorphism, the molecules grow lethargic — as they lose energy during the cooling, they have an even harder time getting into the appropriate position. Out of this forgetful laziness comes the miracle of glass — “a solid material that has the molecular structure of a chaotic liquid.”

This is where one of glass’s inherent paradoxes arises: If SiO2‘s inability to form a quartz crystal is all it takes to produce glass, one would imagine making it is a piece of cake. Just set a bunch of sand ablaze and watch it glassify. Alas, it’s not nearly as easy — or else Earth’s deserts would have easily turned to glass eons ago. The reason this hasn’t happened is twofold. Miodownik explains:

The first [problem] is that most sand doesn’t contain the right combination of minerals to make good glass: the brown color is a dreaded sign in chemistry, a clue that you have a mixture of impurities. It is the same with paints: random combinations of colors don’t yield pure results; instead you get brownish-gray hues. While some additives, so-called fluxes, such as sodium carbonate, will encourage the formation of glass, most will not. Unfortunately, despite being mainly quartz, sand is also made up of whatever the wind blows in its direction. The second problem is that even if the sand has the right chemical composition, the temperatures needed to melt it are around 1200 ° C, much hotter than any normal fire, which tends to be in the region of 700–800°C.

One of Antoine de Saint-Exupéry's original watercolors for 'The Little Prince,' 1943. Click image for more.

What does the trick, however, is a lightning bolt, which can heat the desert to more than 10,000°C — a temperature well capable of melting the sand. When that happens, shafts of glass called fulgurites form — named after fulgur, the Latin for “thunderbolt.” Because the sand is impure, the fulgurites are murky and nearly opaque. Except in certain curious circumstances:

A lightning bolt will do the job, though. When one of these strikes the desert it creates temperatures in excess of 10,000°C which are easily high enough to melt the sand, creating In one part of the Libyan Desert, there is an area of exceptionally pure white sand, comprised almost entirely of quartz. Search this part of the desert and you may find a rare form of glass that looks nothing like a scruffy fulgurite but which has instead the jewel-like clarity of modern glass. A piece of this desert glass forms the centerpiece of a decorative scarab found on the mummified body of Tutankhamun. We know that this desert glass was not made by the ancient Egyptians because it has recently been established that it is twenty-six million years old. The only glass we know like it is Trinitite glass, the glass formed at the site of the Trinity nuclear bomb test in 1945 at White Sands, Nevada. Given that there was no nuclear bomb in the Libyan Desert twenty-six million years ago, the current theory is that the extremely high temperatures that would have been needed to create such optically pure glass must have been produced by the high-energy impact of a meteor.

But rather than a mere curious oddity, fulgurites embody the hidden potentialities in glass not only as a participant in the cultural and natural history of Earth but also as a teller of that story — because ancient fulgurites trap air bubbles as they form, they offer climate scientists an invaluable record of the past.

In fact, Miodownik’s most interesting point about the cultural role of glass has to do with science — but not in the expected direction of the relationship. As is the case with most world-changing innovations, the inventor and the popularizer who ultimately leads to mass adoption of the invention are different individuals, often years apart. The Greeks and the Egyptians had pioneered glass-making, but the Romans were the ones who introduced it into daily life. After discovering the mineral natron — a naturally occurring form of baking soda — they were able to make relatively clear glass at much lower temperatures than what would be needed to melt pure quartz. They built special furnaces for manufacturing glass in bulk, which they then distributed across the Roman Empire — so the glass revolution wasn’t merely one of technology, but also of infrastructure and marketing. Suddenly, glass was a material available to and affordable for the average citizen — an achievement based not on harnessing a novel technology but, essentially, on setting Moore’s Law into motion.

The crowning achievement of the Roman glass age was the invention of the window — Latin for “wind eye” — that filled the gaping, wind-weary openings on building walls. It was, as Miodownik notes, the birth of our modern obsession with architectural glass. The Romans also invented the modern mirror, which prior to the glass revolution consisted of a highly polished metal surface that rendered a much duller and fuzzier image. The glass-covered mirror not only gave a crisper image, but was also far cheaper and easier to produce.

But the most interesting part of the glass story has to do with the Scientific Revolution itself. Fast-forward to a millennium after the collapse of the Roman Empire, and China has cultivated the world’s greatest mastery of materials through extraordinary craftsmanship of wood, paper, ceramics, and metals.

And yet, they largely ignored glass.

Meanwhile in Europe, scientists and inventors were hard at work building the telescope and the microscope — the powerhouse duo of the Scientific Revolution. In what’s perhaps his most intriguing point, Miodownik argues this may have planted the seed for the growing rift in technological advances and corresponding material wealth between the East and the West over the centuries that followed. Miodownik writes:

The disdain for glass in the East lasted all the way up until the nineteenth century. Before then, the Japanese and Chinese relied on paper for the windows of their buildings, a material that worked perfectly well but resulted in a different kind of architecture. The lack of glass technology in the East meant that, despite their technical sophistication, they never invented the telescope nor the microscope, and had access to neither until Western missionaries introduced them. Whether it was the lack of these two crucial optical instruments that prevented the Chinese from capitalizing on their technological superiority and instigating a scientific revolution, as happened in the West in the seventeenth century, is impossible to say. What is certain, though, is that without a telescope you can’t see that Jupiter has moons, or that Pluto exists, or make the astronomical measurements that underpin our modern understanding of the universe. Similarly, without the microscope, it is impossible to see cells such as bacteria and to study systematically the microscopic world, which was essential to the development of medicine and engineering.


Whether the relationship between glass technology and the seventeenth-century scientific revolution really is a simple case of cause and effect is an open question. It seems more likely that glass was a necessary condition rather than the reason for it. However, there is no doubt that glass was largely ignored in the East for a thousand years.

Backtracking from these complex potential sociopolitical effects, the most remarkable property of glass remains its most elemental — its crystalline clarity and tantalizing transparency, the mysterious quality that lets light pass through it and thus sets it apart from other solids. Miodownik digs deeper to extract the real — and appropriately counterintuitive — mystery:

After all, glass contains all of the same atoms that make up a handful of sand. Why in the form of sand should they be opaque and in the form of glass transparent and able to bend light? Glass is made of silicon and oxygen atoms, as well as a few other sorts. Within every atom there is a central nucleus, which contains protons and neutrons, surrounded by varying numbers of electrons. The size of the nucleus and the individual electrons is tiny compared to the overall size of the atom. If an atom were the size of an athletics stadium, the nucleus would be the size of a pea at its center, and the electrons would be the size of grains of sand in the surrounding stands. So within all atoms — and indeed all matter — there is a majority of empty space. This suggests that there should be plenty of room for light to travel through an atom without bumping into either an electron or the nucleus. Which indeed there is. So the real question is not “Why is glass transparent?,” but “Why aren’t all materials transparent?”

Illustration from Disney's 'Our Friend the Atom,' 1956. Click image for more.

Miodownik extends the metaphor to offer an elegant explanation:

Inside an atomic stadium … the electrons are only allowed to inhabit certain parts of the stands. It is as if most of the seats have been removed and there are only certain rows of seats left, with each electron restricted to its allotted row. If an electron wants to upgrade to a better row, it has to pay more—the currency being energy. When light passes through an atom it provides a burst of energy, and if the amount of energy provided is enough, an electron will use that energy to move into a better seat. In doing so, it absorbs the light, preventing it from passing through the material.

But there is a catch. The energy of the light has to match exactly that required for the electron to move from its seat to a seat in the available row. If it’s too small, or to put it another way, if there are no seats available in the row above (i.e., the energy required to get to them is too large), then the electron cannot upgrade and the light will not be absorbed. This idea of electrons not being able to move between rows (or energy states, as they are called) unless the energy exactly matches is the theory that governs the atomic world, called quantum mechanics. The gaps between rows correspond to specific quantities of energy, or quanta. The way these quanta are arranged in glass is such that moving to a free row requires much more energy than is available in visible light. Consequently, visible light does not have enough energy to allow the electrons to upgrade their seats and has no choice but to pass straight through the atoms. This is why glass is transparent. Higher-energy light, on the other hand, such as UV light, can upgrade the electrons in glass to the better seats, and so glass is opaque to UV light. This is why you can’t get a suntan through glass, since the UV light never reaches you. Opaque materials like wood and stone effectively have lots of cheap seats available and so visible light and UV are easily absorbed by them.

This makes one wonder about popular brands of eyewear advertising a “UV filter” — but then again, saying that all glasses filter UV light by definition is a decidedly less marketable message.

The interaction between light and glass brings us full-circle to the heart of the scientific revolution and Sir Isaac Newton, whose genius — at least when it came to glass — was one of reverse-engineering. Miodownik highlights his landmark contribution:

It wasn’t until 1666 that Isaac Newton realized that what was blindingly obvious was blindingly wrong and came up with the real explanation. Newton’s moment of genius was to notice that a glass prism not only turned “white” light into a mixture of colors, but could also reverse the process. From this, he deduced that all of the colors created by a piece of glass were already in the light in the first place. They had traveled all the way from the sun as a ray of mixed light, only to be split up into their constituent colors when they hit the glass. The same thing would happen if they hit a drop of water, too, since this was also transparent. At a stroke, Newton had for the first time in history managed to explain the main features of the rainbow.

Considering these and many other cultural contributions we owe to glass — it gave chemists clear beakers and let them actually observe the reactions taking place; it radically changed how beer is drunk by transforming it from a once-murky brew to be experienced only in the mouth to a golden gift to be beheld with the eyes — Miodownik contemplates rather beautifully what’s perhaps the greatest cultural paradox of glass:

We have no great love for the material that has made this possible. People do not tend to wax lyrical about glass in the way that they do about, say, a wooden floor or a cast-iron railway station. We do not run our hands down the latest double-glazed panel and admire the sensuality of this material. Maybe this is because in its purest form it is a featureless material: smooth, transparent, and cold. These are not human qualities. People tend to relate more to colored, intricate, delicate, or simply misshapen glass, but this is rarely functional. The most effective glass, the stuff we build our modern cities from, is flat, thick, and perfectly transparent, but it is the least likable, the least knowable: the most invisible…

For all its considerable importance in our history and our lives, glass has somehow failed to win our affections [and] has not become part of the treasured fabric of our lives. The very thing that we value it for has also disqualified it from our affections: it is inert and invisible, not just optically, but culturally.

Stuff Matters is an illuminating and addictively absorbing read in its entirety. Complement with Richard Feynman’s spectacular metaphor for the universe, which wouldn’t be possible without glass.

Donating = Loving

Bringing you (ad-free) Brain Pickings takes hundreds of hours each month. If you find any joy and stimulation here, please consider becoming a Supporting Member with a recurring monthly donation of your choosing, between a cup of tea and a good dinner.

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