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Explaining the world
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Have great conversations about ideas through simple and insightful sketches. Visual explanations that are fast to read, fun to share, and hard to forget.

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In a Book: Big Ideas Little Pictures

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Absorb big ideas with crystal-clear understanding through this collection of 135 visual explanations. Including 24 exclusive new sketches and enhanced versions of classic favourites, each page shares life-improving ideas through beautifully simple illustrations.

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Hi, I'm Jono 👋

I'm an author and illustrator creating one of the world's largest libraries of hand-drawn sketches explaining the world—sketch-by-sketch.

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Quote and advice from Jane Goodall's mother: If there's something you really want, you're going to have to work really hard, take advantage of opportunity and, above all, never give up.

And, above all, never give up

I wanted to share not just a short tribute to Jane Goodall, but also a tribute to Jane’s mother. Parents, after all, play a part in remarkable children. Here Jane shares a lesson from her mother that she clearly took to heart: If there’s something you really want, you’re going to have to work really hard, take advantage of opportunity and, above all, never give up. — Jane Goodall's mother, Vanne Goodall, (as recounted by Jane) It’s simple advice, but Jane embodied it. To her last days, she never gave up fighting for all of us. As she said, “I went to Africa as a scientist. I left the jungle as an activist.” One of her key realisations was that if we want to protect animals and the natural world, we have to help people out of extreme poverty. When you’re struggling to survive, the environment isn't your main concern, and animals can look like food. That’s why, perhaps counterintuitively, I've read that some of the most effective ways to help the planet and its wildlife are to help people out of poverty, and particularly by providing education and opportunities for women. For example, see Factfulness by Hans Rosling. Maybe your kids will hear what you tell them after all. A Little About Jane Goodall If you don't know much about Jane, she left England to study chimpanzees in Africa. She made many new discoveries about their behaviour, such as tool use, and hunting and eating meat. She also saw the threat to their habitat and safety and resolved to do something about it. She founded Roots & Shoots (global, USA), a program with the mission: "To foster respect and compassion for all living things, to promote understanding of all cultures and beliefs and to inspire each individual to take action to make the world a better place for animals, people, and the environment." It particularly focuses on young people. The program continues today through the Jane Goodall Institute. “We have the choice to use the gift of our life to make the world a better place.” — Dr. Jane Goodall Jane shared these lessons from her mother in the course I took from her on Masterclass. Jane has also written many books, though I haven't read them. There are also plenty of talks from her that you can watch online. As a small aside, Masterclass isn't cheap, but if you're at a point where you're ready to pack in some learning, there are some amazing classes and teachers on there. They don't sponsor this newsletter...but maybe they should 🤔 Related Ideas to Above All, Never Give Up Also see: A World of 4 Income Levels: beyond developing and developed Going Out was Really Going In Mangroves There is No Away Climate anxiety and the cure of action Hitched to Everything Else in the UniverseI wanted to share not just a short tribute to Jane Goodall, but also a tribute to Jane’s mother. Parents, after all, play a part in remarkable children. Here Jane shares a lesson from her mother that she clearly took to heart: If there’s something you really want, you’re going to have to work really hard, take advantage of opportunity and, above all, never give up. — Jane Goodall's mother, Vanne Goodall, (as recounted by Jane) It’s simple advice, but Jane embodied it. To her last days, she never gave up fighting for all of us. As she said, “I went to Africa as a scientist. I left the jungle as an activist.” One of her key realisations was that if we want to protect animals and the natural world, we have to help people out of extreme poverty. When you’re struggling to survive, the environment isn't your main concern, and animals can look like food. That’s why, perhaps counterintuitively, I've read that some of the most effective ways to help the planet and its wildlife are to help people out of poverty, and particularly by providing education and opportunities for women. For example, see Factfulness by Hans Rosling. Maybe your kids will hear what you tell them after all. A Little About Jane Goodall If you don't know much about Jane, she left England to study chimpanzees in Africa. She made many new discoveries about their behaviour, such as tool use, and hunting and eating meat. She also saw the threat to their habitat and safety and resolved to do something about it. She founded Roots & Shoots (global, USA), a program with the mission: "To foster respect and compassion for all living things, to promote understanding of all cultures and beliefs and to inspire each individual to take action to make the world a better place for animals, people, and the environment." It particularly focuses on young people. The program continues today through the Jane Goodall Institute. “We have the choice to use the gift of our life to make the world a better place.” — Dr. Jane Goodall Jane shared these lessons from her mother in the course I took from her on Masterclass. Jane has also written many books, though I haven't read them. There are also plenty of talks from her that you can watch online. As a small aside, Masterclass isn't cheap, but if you're at a point where you're ready to pack in some learning, there are some amazing classes and teachers on there. They don't sponsor this newsletter...but maybe they should 🤔 Related Ideas to Above All, Never Give Up Also see: A World of 4 Income Levels: beyond developing and developed Going Out was Really Going In Mangroves There is No Away Climate anxiety and the cure of action Hitched to Everything Else in the Universe

✨ Latest

The Buttered Cat Paradox

The Buttered Cat Paradox goes like this: Cats always land on their feet Falling toast always lands butter side down So what will happen if you strap buttered toast to the back of a falling cat? Presumably, the cat righting reflex will fight against the pull of the buttered toast. John Frazee proposed the buttered cat paradox in a July 1993 competition in Omni magazine, including a practical application based on the inevitable hovering that must result: "When a cat is dropped, it always lands on its feet, and when toast is dropped, it always lands with the buttered side facing down. I propose to strap buttered toast to the back of a cat. The two will hover spinning, inches above the ground. With a giant buttered cat array, a high-speed monorail could easily link New York with Chicago." The Buttered Toast Phenomenon Incidentally, the buttered toast phenomenon—why toast always lands butter side down—was the subject of an experiment on the British TV show QED, finding that buttered toast, when thrown into the air, landed equally on the buttered and unbuttered sides. However, Robert Matthews conducted a mathematical analysis of toast falling, as it would more commonly, from the edge of a table. His work showed that landing buttered-side down is the most likely result given the height of an average table, the gravitational constant, and the typical mass of toast. It won him an Ig Nobel Prize in 1996. Buttered toast has been falling for a long time. There's an 1884 poem by James Payn: I never had a slice of bread, Particularly large and wide, That did not fall upon the floor, And always on the buttered side! The Cat Righting Reflex The innate ability for cats to twist around and land on their feet is called the cat righting reflex. They can do this thanks to a very flexible spine and no collarbone. I dropped no cats in the making of this sketch. Please don't drop cats. Here's a print of the cat only More paradoxes The coastline paradox: the length of a coastline depends on how close you measure The transparency paradox: the more transparent the workspace, the more privately people behave The paradox of choice: more choice can make it harder to choose The automation paradox: the better the machines get, the more we struggle when they fail The Abilene paradox: a group can take an action that no one thinks is good The liar paradox: I am lying The paradise paradox: the belief that moving to paradise will solve all our problems Jevon's paradox: Fuel efficiency gains tend to increase fuel use Also see: Murphy's Law: What can go wrong, will go wrong Learn more This archived Scientific American article on the murphodynamics of toast gives more detail about the buttered toast phenomenon.The Buttered Cat Paradox goes like this: Cats always land on their feet Falling toast always lands butter side down So what will happen if you strap buttered toast to the back of a falling cat? Presumably, the cat righting reflex will fight against the pull of the buttered toast. John Frazee proposed the buttered cat paradox in a July 1993 competition in Omni magazine, including a practical application based on the inevitable hovering that must result: "When a cat is dropped, it always lands on its feet, and when toast is dropped, it always lands with the buttered side facing down. I propose to strap buttered toast to the back of a cat. The two will hover spinning, inches above the ground. With a giant buttered cat array, a high-speed monorail could easily link New York with Chicago." The Buttered Toast Phenomenon Incidentally, the buttered toast phenomenon—why toast always lands butter side down—was the subject of an experiment on the British TV show QED, finding that buttered toast, when thrown into the air, landed equally on the buttered and unbuttered sides. However, Robert Matthews conducted a mathematical analysis of toast falling, as it would more commonly, from the edge of a table. His work showed that landing buttered-side down is the most likely result given the height of an average table, the gravitational constant, and the typical mass of toast. It won him an Ig Nobel Prize in 1996. Buttered toast has been falling for a long time. There's an 1884 poem by James Payn: I never had a slice of bread, Particularly large and wide, That did not fall upon the floor, And always on the buttered side! The Cat Righting Reflex The innate ability for cats to twist around and land on their feet is called the cat righting reflex. They can do this thanks to a very flexible spine and no collarbone. I dropped no cats in the making of this sketch. Please don't drop cats. Here's a print of the cat only More paradoxes The coastline paradox: the length of a coastline depends on how close you measure The transparency paradox: the more transparent the workspace, the more privately people behave The paradox of choice: more choice can make it harder to choose The automation paradox: the better the machines get, the more we struggle when they fail The Abilene paradox: a group can take an action that no one thinks is good The liar paradox: I am lying The paradise paradox: the belief that moving to paradise will solve all our problems Jevon's paradox: Fuel efficiency gains tend to increase fuel use Also see: Murphy's Law: What can go wrong, will go wrong Learn more This archived Scientific American article on the murphodynamics of toast gives more detail about the buttered toast phenomenon.

5 Oct

Pace Layers: Six layers of robust and adaptable civilisations

What makes a resilient system? It needs to be strong, but flexible. Pace Layers, sometimes called pace layering, is a framework created by Stewart Brand of the Long Now Foundation that explores how different parts of civilisation change at different speeds. Fast-moving layers like fashion bring novelty and experimentation, while slower layers like culture and nature provide stability and memory. Together, the layers support, reinforce, and challenge each other—creating robust, adaptable societies. Pace layers is a model I have come back to again and again. What is the Pace Layers Framework? The pace layering model has six levels, with each deeper layer moving more slowly than the one above it. In Brand's words: Fast learns, slow remembers. Fast proposes, slow disposes. Fast is discontinuous, slow is continuous. Fast and small instructs slow and big by accrued innovation and occasional revolution. Slow and big controls small and fast by constraint and constancy. Fast gets all our attention, slow has all the power. In short: the fast layers innovate, the slow layers stabilise. Brand argued that all durable dynamic systems have this sort of structure—it’s what makes them adaptable and resilient. According to pace layering, the six layers of pace and size in the working structure of a robust and adaptable civilisation are: Fashion/Art Commerce Infrastructure Governance Culture Nature Pace Layering Example: Electric Scooters An example brings pace layers home to me. Here, I consider electric scooters, but you can take almost any innovation and think through the layers. Fashion/Art New scooter designs, colours, marketing campaigns, and influencer hype cycles. These come and go quickly—some stick, most fade. Commerce Scooter rental startups, pricing models, venture capital funding, and competition with bikes, cars, and other transport. Commerce runs slower than fashion, but still moves quickly through experimentation. Infrastructure Charging docks, scooter lanes, designated parking areas, and integration with city planning—all these take time. Cities and transport systems have to adapt, if electric scooters persist, for them to thrive rather than die out. Governance The laws and regulations surrounding scooters often lag behind the pace of commerce, including speed limits, taxes, penalties, incentives, safety requirements, age restrictions, or bans. Governance responds as the effects of scooters unfold. Culture Culture in the deep sense of how this changes mobility and ideas around travel. It may affect socialising, where people work and live, and what we choose to do as a society. Culture evolves slowly as habits and norms change in tandem with governance and infrastructure. Nature The environmental realities of scooters vs other transport means. Batteries, natural resources, long-term sustainability, and the effect on the climate. Applying the Pace Layers Model to AI Applying pace layers to the growth and development of Artificial Intelligence (AI) is also instructive: Fashion: AI tools and interfaces change daily. Commerce: Models and capabilities change weekly or monthly. Companies compete on quarterly and annual cycles. Infrastructure: Investment, data centres and energy generation are being approved and built slowly. Governance: The rules, ethics, court cases, and legal challenges surrounding the regulation of AI content and companies are developing on a case-by-case basis. Culture: How AI changes work, employment, where people live, and power structures are all in progress. Nature: Effects on the planet, energy and climate take longer to play out. AI can feel like it's changing every day, yet its deepest consequences will play out over decades and centuries. Pace Layers and Time Hierarchy In his book The Clock of the Long Now, Brand also discusses time hierarchy in nature. He describes a coniferous forest: The needle changes within a year. The tree crown over several years. The patch over many decades. The stand over a couple of centuries. The forest over a thousand years. The biome over ten thousand years. The faster elements are constrained by the slower ones: the needle by the crown, the crown by the patch, and so on up to the biome. Yet innovation still percolates through the system via evolutionary competition. Occasionally, shocks—fire, disease, human activity—disrupt the whole structure, sometimes all the way to the biome. You can see this idea in my sketch on Time Hierarchy. Considering the Pace Layers Model I find pace layers thinking interesting as a way to differentiate between the fast and slower changes I see around me. It helps me make better sense of the world and see the age-old tussle between innovation and stability. Related Ideas to Pace Layers Also see: Time Hierarchy The Overview Effect The Overton Window: the range of politically acceptable ideas Human pace The Gartner Hype Cycle Marchetti's Constant The Destiny Instinct The S-Curve The Law of Unintended Consequences I revised my original pace layers sketch because I kept discussing it with people and thought it needed a better visual. Read more on Pace Layers at the Long NowWhat makes a resilient system? It needs to be strong, but flexible. Pace Layers, sometimes called pace layering, is a framework created by Stewart Brand of the Long Now Foundation that explores how different parts of civilisation change at different speeds. Fast-moving layers like fashion bring novelty and experimentation, while slower layers like culture and nature provide stability and memory. Together, the layers support, reinforce, and challenge each other—creating robust, adaptable societies. Pace layers is a model I have come back to again and again. What is the Pace Layers Framework? The pace layering model has six levels, with each deeper layer moving more slowly than the one above it. In Brand's words: Fast learns, slow remembers. Fast proposes, slow disposes. Fast is discontinuous, slow is continuous. Fast and small instructs slow and big by accrued innovation and occasional revolution. Slow and big controls small and fast by constraint and constancy. Fast gets all our attention, slow has all the power. In short: the fast layers innovate, the slow layers stabilise. Brand argued that all durable dynamic systems have this sort of structure—it’s what makes them adaptable and resilient. According to pace layering, the six layers of pace and size in the working structure of a robust and adaptable civilisation are: Fashion/Art Commerce Infrastructure Governance Culture Nature Pace Layering Example: Electric Scooters An example brings pace layers home to me. Here, I consider electric scooters, but you can take almost any innovation and think through the layers. Fashion/Art New scooter designs, colours, marketing campaigns, and influencer hype cycles. These come and go quickly—some stick, most fade. Commerce Scooter rental startups, pricing models, venture capital funding, and competition with bikes, cars, and other transport. Commerce runs slower than fashion, but still moves quickly through experimentation. Infrastructure Charging docks, scooter lanes, designated parking areas, and integration with city planning—all these take time. Cities and transport systems have to adapt, if electric scooters persist, for them to thrive rather than die out. Governance The laws and regulations surrounding scooters often lag behind the pace of commerce, including speed limits, taxes, penalties, incentives, safety requirements, age restrictions, or bans. Governance responds as the effects of scooters unfold. Culture Culture in the deep sense of how this changes mobility and ideas around travel. It may affect socialising, where people work and live, and what we choose to do as a society. Culture evolves slowly as habits and norms change in tandem with governance and infrastructure. Nature The environmental realities of scooters vs other transport means. Batteries, natural resources, long-term sustainability, and the effect on the climate. Applying the Pace Layers Model to AI Applying pace layers to the growth and development of Artificial Intelligence (AI) is also instructive: Fashion: AI tools and interfaces change daily. Commerce: Models and capabilities change weekly or monthly. Companies compete on quarterly and annual cycles. Infrastructure: Investment, data centres and energy generation are being approved and built slowly. Governance: The rules, ethics, court cases, and legal challenges surrounding the regulation of AI content and companies are developing on a case-by-case basis. Culture: How AI changes work, employment, where people live, and power structures are all in progress. Nature: Effects on the planet, energy and climate take longer to play out. AI can feel like it's changing every day, yet its deepest consequences will play out over decades and centuries. Pace Layers and Time Hierarchy In his book The Clock of the Long Now, Brand also discusses time hierarchy in nature. He describes a coniferous forest: The needle changes within a year. The tree crown over several years. The patch over many decades. The stand over a couple of centuries. The forest over a thousand years. The biome over ten thousand years. The faster elements are constrained by the slower ones: the needle by the crown, the crown by the patch, and so on up to the biome. Yet innovation still percolates through the system via evolutionary competition. Occasionally, shocks—fire, disease, human activity—disrupt the whole structure, sometimes all the way to the biome. You can see this idea in my sketch on Time Hierarchy. Considering the Pace Layers Model I find pace layers thinking interesting as a way to differentiate between the fast and slower changes I see around me. It helps me make better sense of the world and see the age-old tussle between innovation and stability. Related Ideas to Pace Layers Also see: Time Hierarchy The Overview Effect The Overton Window: the range of politically acceptable ideas Human pace The Gartner Hype Cycle Marchetti's Constant The Destiny Instinct The S-Curve The Law of Unintended Consequences I revised my original pace layers sketch because I kept discussing it with people and thought it needed a better visual. Read more on Pace Layers at the Long Now

28 Sep

The Repeated Word Illusion

I distinctly remember the first time I saw the “I love Paris in the the springtime” illusion. It definitely got me. My mind happily skipped past a 'the' without a second's notice. Why do our brains do that? Why do so many people fall for this “I love Paris in the springtime” illusion? This little illusion is a fun and memorable example from psychology that illustrates how our minds use shortcuts when reading. There are a few factors at work that let us completely miss repeated words—even when they’re right in front of us. Our minds love taking shortcuts Thinking is expensive—it takes energy. So when our brain sees something familiar, it often skips ahead to save effort. We rely on mental shortcuts (heuristics) to help us move faster and more efficiently, but sometimes those shortcuts trip us up. Top-down and bottom-up processing When presented with a simple sentence, as in the sketch, our minds may engage in top-down processing, jumping straight to the meaning. In contrast, when something is unfamiliar, important (like an exam), or when our role demands precision (like a proofreader), we tend to slow down and use bottom-up processing—scanning each word more carefully. Saccades When reading, our eyes don’t move smoothly along a line—they jump in quick bursts called saccades. How far we jump depends on word length, spacing, familiarity and complexity. Some words may be skipped entirely. Short, common and predictable words Paris and Springtime, though well known, are less common than "the". We are more likely to focus on the less usual, meaning-carrying words and skip short, common, predictable words. Layout matters By stacking the sentence in a pyramid, we subtly guide attention downward and to the right. That extra “the” hides off to the left, where we’re least likely to look back. -- The psychology of what we actually do when we read is much more complex and fascinating than I first realised—as I find so often the case with things. PS Did you catch the repeated 'are', too? Related Ideas to The Repeated Word Illusion More illusions: The Droste Effect The ring-segment illusion The impossible staircase (Penrose stairs) Anamorphosis The moon illusion Hermann grid, Necker cube, Blivet Also see: Leading, tracking, kerning The availability heuristic The frequency illusion Gestalt principles Context is king More This paper has an interesting discussion of word skipping and reading models that try to understand and simulate what we really do when we read: Drieghe, D., Rayner, K., & Pollatsek, A. (2005). Eye movements and word skipping during reading revisited. Journal of Experimental Psychology: Human Perception and Performance, 31(5), 954. I wasn't sure of the name of this illusion. If you know what it should be called, please let me know.I distinctly remember the first time I saw the “I love Paris in the the springtime” illusion. It definitely got me. My mind happily skipped past a 'the' without a second's notice. Why do our brains do that? Why do so many people fall for this “I love Paris in the springtime” illusion? This little illusion is a fun and memorable example from psychology that illustrates how our minds use shortcuts when reading. There are a few factors at work that let us completely miss repeated words—even when they’re right in front of us. Our minds love taking shortcuts Thinking is expensive—it takes energy. So when our brain sees something familiar, it often skips ahead to save effort. We rely on mental shortcuts (heuristics) to help us move faster and more efficiently, but sometimes those shortcuts trip us up. Top-down and bottom-up processing When presented with a simple sentence, as in the sketch, our minds may engage in top-down processing, jumping straight to the meaning. In contrast, when something is unfamiliar, important (like an exam), or when our role demands precision (like a proofreader), we tend to slow down and use bottom-up processing—scanning each word more carefully. Saccades When reading, our eyes don’t move smoothly along a line—they jump in quick bursts called saccades. How far we jump depends on word length, spacing, familiarity and complexity. Some words may be skipped entirely. Short, common and predictable words Paris and Springtime, though well known, are less common than "the". We are more likely to focus on the less usual, meaning-carrying words and skip short, common, predictable words. Layout matters By stacking the sentence in a pyramid, we subtly guide attention downward and to the right. That extra “the” hides off to the left, where we’re least likely to look back. -- The psychology of what we actually do when we read is much more complex and fascinating than I first realised—as I find so often the case with things. PS Did you catch the repeated 'are', too? Related Ideas to The Repeated Word Illusion More illusions: The Droste Effect The ring-segment illusion The impossible staircase (Penrose stairs) Anamorphosis The moon illusion Hermann grid, Necker cube, Blivet Also see: Leading, tracking, kerning The availability heuristic The frequency illusion Gestalt principles Context is king More This paper has an interesting discussion of word skipping and reading models that try to understand and simulate what we really do when we read: Drieghe, D., Rayner, K., & Pollatsek, A. (2005). Eye movements and word skipping during reading revisited. Journal of Experimental Psychology: Human Perception and Performance, 31(5), 954. I wasn't sure of the name of this illusion. If you know what it should be called, please let me know.

21 Sep

The difference between Science and Engineering: quote by Theodore von Kármán "Scientists discover the world that exists; Engineers create the world that never was."

Science and Engineering: What’s the Difference?

People often ask, "What's the difference between science and engineering?" Having studied engineering but always loved science, I've come across a few perspectives I find useful to understand the two. In England at least, studying science usually comes first. In fact, you can't really study engineering until you head off to University. So discussing science and engineering together never came up when I was at school. Engineering seemed to be machines and buildings and projects and design and technology, and science seemed to be everything else. But what really makes science science and engineering engineering? Science vs Engineering: Five perspectives Here are five simple ways people have described science and engineering. Theodore Von Kármán on Scientists and Engineers Aerospace engineer Theodore Von Kármán said: Scientists discover the world that exists; Engineers create the world that never was. — Theodore Von Kármán Richard Hamming on Science and Engineering Bell Labs engineer Richard Hamming, in his book The Art of Doing Science and Engineering: Learning to Learn, captured the difference this way: "In science if you know what you are doing you should not be doing it. In engineering if you do not know what you are doing you should not be doing it." — Richard Hamming Hamming also points out that there's a lot of science in engineering and a lot of engineering in science: "Much of present science rests on engineering tools, and as time goes on, engineering seems to involve more and more of the science part." For example, dealing with huge amounts of data, of the sort generated by weather sensors or particle colliders, requires exceptional engineering techniques. And engineering new displays or ever smaller processing chips requires a lot of scientific knowledge. The two are intertwined: science enables engineering to push forward, and engineering opens new doors for science. Richard Feynman on Computer Science Physicist Richard Feynman, in a talk on quantum computers at Bell Labs (video excerpt), said: "I don't believe in Computer Science. To me, science is the study of the behavior of nature. And engineering or applied things is the behavior of things we make. You need to know how Nature works in order to make the things, and so you use science in engineering, but you're doing it for a human purpose." — Richard Feynman Mythbusters' Adam Savage on Science vs Screwing Around Adam Savage, Mythbusters host, shared: "Remember kids, the only difference between screwing around and science is writing it down." Adam said that the quote was actually from the ballistics expert on a shoot, Alex Jason. It doesn’t quite get to the heart of science versus engineering, but it’s a great reminder of good practice. Why, How, What's Next? A reader shared this framing with me: Science asks “Why” Engineering asks “How” And together, they answer, “What’s next?” And finally, my own phrasing in the first draft for the sketch used: Science: Study of the world Engineering: Doing things with what we've learned about the world So while there probably isn't a single neat answer to the question of what’s the difference between science and engineering, maybe these give some food for thought. If you know of other interesting framings for science and engineering, please let me know. Related Ideas to Science and Engineering Also see: The Feynman Learning Technique Data Information Knowledge Wisdom Bloom's Taxonomy for learning Hitched to Everything Else in the Universe You Get What You Measure - Richard Hamming What Gets Measured Gets Better - Richard Hamming Darwin's 5 Principles of Natural Selection Accuracy and Precision are not the same thing Thesis, Antithesis, Synthesis a progression of ideas Unknown unknowns Greeble (I learned from Adam Savage)People often ask, "What's the difference between science and engineering?" Having studied engineering but always loved science, I've come across a few perspectives I find useful to understand the two. In England at least, studying science usually comes first. In fact, you can't really study engineering until you head off to University. So discussing science and engineering together never came up when I was at school. Engineering seemed to be machines and buildings and projects and design and technology, and science seemed to be everything else. But what really makes science science and engineering engineering? Science vs Engineering: Five perspectives Here are five simple ways people have described science and engineering. Theodore Von Kármán on Scientists and Engineers Aerospace engineer Theodore Von Kármán said: Scientists discover the world that exists; Engineers create the world that never was. — Theodore Von Kármán Richard Hamming on Science and Engineering Bell Labs engineer Richard Hamming, in his book The Art of Doing Science and Engineering: Learning to Learn, captured the difference this way: "In science if you know what you are doing you should not be doing it. In engineering if you do not know what you are doing you should not be doing it." — Richard Hamming Hamming also points out that there's a lot of science in engineering and a lot of engineering in science: "Much of present science rests on engineering tools, and as time goes on, engineering seems to involve more and more of the science part." For example, dealing with huge amounts of data, of the sort generated by weather sensors or particle colliders, requires exceptional engineering techniques. And engineering new displays or ever smaller processing chips requires a lot of scientific knowledge. The two are intertwined: science enables engineering to push forward, and engineering opens new doors for science. Richard Feynman on Computer Science Physicist Richard Feynman, in a talk on quantum computers at Bell Labs (video excerpt), said: "I don't believe in Computer Science. To me, science is the study of the behavior of nature. And engineering or applied things is the behavior of things we make. You need to know how Nature works in order to make the things, and so you use science in engineering, but you're doing it for a human purpose." — Richard Feynman Mythbusters' Adam Savage on Science vs Screwing Around Adam Savage, Mythbusters host, shared: "Remember kids, the only difference between screwing around and science is writing it down." Adam said that the quote was actually from the ballistics expert on a shoot, Alex Jason. It doesn’t quite get to the heart of science versus engineering, but it’s a great reminder of good practice. Why, How, What's Next? A reader shared this framing with me: Science asks “Why” Engineering asks “How” And together, they answer, “What’s next?” And finally, my own phrasing in the first draft for the sketch used: Science: Study of the world Engineering: Doing things with what we've learned about the world So while there probably isn't a single neat answer to the question of what’s the difference between science and engineering, maybe these give some food for thought. If you know of other interesting framings for science and engineering, please let me know. Related Ideas to Science and Engineering Also see: The Feynman Learning Technique Data Information Knowledge Wisdom Bloom's Taxonomy for learning Hitched to Everything Else in the Universe You Get What You Measure - Richard Hamming What Gets Measured Gets Better - Richard Hamming Darwin's 5 Principles of Natural Selection Accuracy and Precision are not the same thing Thesis, Antithesis, Synthesis a progression of ideas Unknown unknowns Greeble (I learned from Adam Savage)

14 Sep

The Figure Skater's Spin and Conservation of Angular Momentum Illustrated with equations

The Figure Skater's Spin and the Conservation of Angular Momentum

Why figure skaters go slower with their arms outstretched When a figure skater pulls into one of those incredible spins, they provide one of the clearest examples of the conservation of angular momentum. When they pull their arms in, they go fast, and when they stretch out their arms or legs, they slow down. What's going on? Angular Momentum You can think of angular momentum as the oomph in a rotating object, like a weight on a string. It's the rotating equivalent of linear momentum. A system's angular momentum depends on the distribution of mass around the axis of rotation, known as its moment of inertia, multiplied by its velocity of rotation. This is written as: L = I x ω Angular momentum L is the product of moment of inertia I and angular velocity ω. If you swing a weight on a short string versus a long string at the same spin rate, the one on the long string carries more angular momentum. That’s because its mass is further from the axis, giving it a bigger moment of inertia. Devices like flywheels store energy by setting a large mass spinning. The faster it spins and the heavier it is, the more rotational energy it stores. I think we know this intuitively because when we see a large thing spinning, it looks dangerous. The Conservation of Angular Momentum The conservation of angular momentum is a fundamental principle in physics that states that if no external torque (rotational force) acts on a system, then the total angular momentum of that system stays constant. In the figure skater's case, this means that when they spin with their arms in and their arms out, their angular momentum—their distribution of mass from the axis of rotation x rotational velocity—remains constant. Arms out With arms out, mass is further from the axis, so rotation slows. Arms in With arms in, mass is closer to the axis, so rotation speeds up. Examples of Angular Momentum We can see this at work in other places as well. The first three are pretty easy to test yourself, as I have done. The Swivel Chair An easy and fun place to test this is with a swivel office chair. If your office chair spins relatively friction-free, then if you set yourself spinning—or have someone else do it—you'll find that you can change your speed by extending or retracting your legs. Tuck them in and you'll go faster; stick them out and you'll slow down. You can also hold something heavy in your hands and stick your arms out. Roundabouts Set a roundabout spinning. If you move towards the centre, it will spin faster than if you move your weight to the edge. You can watch amusing demonstrations by scientists who hate roundabouts. Playgrounds tend to have other spinny-hell devices, so there may be others you can test with. Swing a Yo-Yo After making sure that you're not near anyone, you can set a yo-yo or other object swinging around you and pull the string to shorten it. You should find the speed increases just like for the figure skater, as its angular momentum is conserved. High Divers Divers that jump from high platforms spin faster when they tuck their legs and arms into their body and slower when they come out of the tuck. Planets and satellites A satellite, or planet, travelling in an elliptical orbit will tend to speed up as it comes closer to the body it's orbiting and slow down further away. Related Ideas to the Conservation of Angular Momentum Also see: The Square Cube Law—why adults are no good at the monkey bars Orbit The Doppler Effect Super Moon — perigee, apogee Buoyancy Sonic Boom Learn More Physics teachers like to demo this by holding weights on spinning office chairs, for which there are lots of videos. I thought the video of a spinning Hoberman sphere (contracting/expanding sphere) was a lovely, clear example. As an example of iterating on sketches, I produced both a more complex and simpler version of this one.Why figure skaters go slower with their arms outstretched When a figure skater pulls into one of those incredible spins, they provide one of the clearest examples of the conservation of angular momentum. When they pull their arms in, they go fast, and when they stretch out their arms or legs, they slow down. What's going on? Angular Momentum You can think of angular momentum as the oomph in a rotating object, like a weight on a string. It's the rotating equivalent of linear momentum. A system's angular momentum depends on the distribution of mass around the axis of rotation, known as its moment of inertia, multiplied by its velocity of rotation. This is written as: L = I x ω Angular momentum L is the product of moment of inertia I and angular velocity ω. If you swing a weight on a short string versus a long string at the same spin rate, the one on the long string carries more angular momentum. That’s because its mass is further from the axis, giving it a bigger moment of inertia. Devices like flywheels store energy by setting a large mass spinning. The faster it spins and the heavier it is, the more rotational energy it stores. I think we know this intuitively because when we see a large thing spinning, it looks dangerous. The Conservation of Angular Momentum The conservation of angular momentum is a fundamental principle in physics that states that if no external torque (rotational force) acts on a system, then the total angular momentum of that system stays constant. In the figure skater's case, this means that when they spin with their arms in and their arms out, their angular momentum—their distribution of mass from the axis of rotation x rotational velocity—remains constant. Arms out With arms out, mass is further from the axis, so rotation slows. Arms in With arms in, mass is closer to the axis, so rotation speeds up. Examples of Angular Momentum We can see this at work in other places as well. The first three are pretty easy to test yourself, as I have done. The Swivel Chair An easy and fun place to test this is with a swivel office chair. If your office chair spins relatively friction-free, then if you set yourself spinning—or have someone else do it—you'll find that you can change your speed by extending or retracting your legs. Tuck them in and you'll go faster; stick them out and you'll slow down. You can also hold something heavy in your hands and stick your arms out. Roundabouts Set a roundabout spinning. If you move towards the centre, it will spin faster than if you move your weight to the edge. You can watch amusing demonstrations by scientists who hate roundabouts. Playgrounds tend to have other spinny-hell devices, so there may be others you can test with. Swing a Yo-Yo After making sure that you're not near anyone, you can set a yo-yo or other object swinging around you and pull the string to shorten it. You should find the speed increases just like for the figure skater, as its angular momentum is conserved. High Divers Divers that jump from high platforms spin faster when they tuck their legs and arms into their body and slower when they come out of the tuck. Planets and satellites A satellite, or planet, travelling in an elliptical orbit will tend to speed up as it comes closer to the body it's orbiting and slow down further away. Related Ideas to the Conservation of Angular Momentum Also see: The Square Cube Law—why adults are no good at the monkey bars Orbit The Doppler Effect Super Moon — perigee, apogee Buoyancy Sonic Boom Learn More Physics teachers like to demo this by holding weights on spinning office chairs, for which there are lots of videos. I thought the video of a spinning Hoberman sphere (contracting/expanding sphere) was a lovely, clear example. As an example of iterating on sketches, I produced both a more complex and simpler version of this one.

7 Sep

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