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Physics
From quanta to relativity — the rules the world runs on.
28 pieces
- How Much Do You Know About Light? Why the Apple Is Red — We Have Never Seen an Object The apple is red because it threw red away. And what reaches your eye is not even the light that struck it — it is light the apple has just made and flung back. 1 questions
- How Much Do You Know About Light? Why Does a Mirror Flip Left and Right? It Never Did Raise your right hand and the figure raises its left. So why does the mirror leave up and down alone? It does not — and it never swapped left and right either. 1 questions
- How Much Do You Know About Light? The Eye Is a Very Narrow Window It is easy to take the rainbow for the whole of light. It is a sliver. Remotes, microwave ovens, X-rays and radio are all light. 2 questions
- How Much Do You Know About Light? Particle or Wave — The Answer Is Both Newton said particle, Huygens said wave. The wave won, then was overturned a century later. Today the answer is both. 3 questions
- How Much Do You Know About Light? Light Falls Too — What Bends Is the Stage Light has no weight, so it should not fall. Yet it bends beside something massive — not because it is pulled but because the road itself is curved. 1 questions
- Where the Formulas Came From How the Earth Was Weighed How do you weigh something you cannot put on a scale? The answer was not to weigh the Earth at all. Measure the faint pull between two lead balls hanging in a room, and the mass of the Earth follows. 3 questions
- Quantum Mechanics, In Order Why Energy Comes in Lumps — Counting It Whole Made It Work A blacksmith reads the temperature of iron from its colour alone. When physics in 1900 tried to calculate why that colour and not another, the answer came out infinite. The assumption forced in to close the gap turned out to be how the world actually is. 3 questions
- Quantum Mechanics, In Order Why the Electron Does Not Fall — A Jump With No Middle By the theory of the day, an atom should collapse in a hundred-billionth of a second. Yet here we are. The single assumption a twenty-eight-year-old Bohr made to escape that contradiction went on to explain firework colours, the composition of stars, and where an electron may sit. 3 questions
- Quantum Mechanics, In Order In Two Places at Once — Superposition and Probability Fire electrons one at a time, well separated so none can meet another. The marks still pile up into stripes. What did a lone electron overlap with? This is also the most misread experiment of the last hundred years. 4 questions
- Quantum Mechanics, In Order Not Unknown but Absent — The Uncertainty Principle A very short sound has no pitch — not because the instrument is poor, but because pitch is not in it. Position and momentum are like that for an electron. The uncertainty principle is not about measurement but about what exists. 3 questions
- Quantum Mechanics, In Order Two Objections in 1935 — Entanglement and the Cat Send one glove to Seoul and the other to Busan. The moment Seoul finds a left glove, Busan's is known to be right. Nothing mysterious there. Einstein said quantum mechanics ought to be like that; Schrödinger put a cat in a box. Thirty years later one man put the argument on a laboratory bench. 4 questions
- Science on the Screen Interstellar — Where One Hour Costs Seven Years Where gravity is strong, time runs slow. Not a science-fiction premise but a correction applied to GPS satellites every day. This film carried that theory over not as a number but as a face — a father younger than his daughter. 4 questions
- Science on the Screen Tenet — If Entropy Falls, Does Time Run Backwards? Most of the difficulty people have with this film comes from one thing: hearing entropy decreasing and time running backwards as the same sentence. Entropy is decreasing inside your refrigerator right now. The refrigerator is not travelling into the past. 4 questions
- Wrong, and Useful Anyway The Aether — The Experiment That Found Nothing Sound travels through air, ripples through water. Yet light crosses an empty universe. What, then, does light travel through? The aether was not a fudge but an honest answer to that question. The experiment sent to find it found nothing — and that nothing split physics in two. 5 questions
- Science in Korea — What Is Being Built Here Fusion — Can We Build a Sun on the Ground? In Yuseong-gu, Daejeon, there is a large doughnut-shaped machine. Inside it, gas at a hundred million degrees floats on magnets. It is an attempt to copy, on the ground, what the Sun does. Why so hot, why there is still no power station, and what the people who do this work actually studied. 2 questions
- Science in Korea — What Is Being Built Here The Heavy Ion Accelerator — Making Nuclei That Do Not Exist Under the Sindong district north of Daejeon sits a building the size of eleven football pitches, 550 metres at its longest. Inside, atomic nuclei are thrown at nearly the speed of light into other nuclei. What is anyone hoping to see? And why must this machine be chilled to 269 degrees below zero? 3 questions
- Science in Korea — What Is Being Built Here Orbit — A Rocket Does Not Go Up, It Goes Sideways Say rocket and you picture flame and a climb into the sky. But reaching space and staying in space are very different things. Going a hundred kilometres up and falling back is not hard. Not falling means running sideways. This is where a rocket's size — and the fact that most of it is fuel tank — comes from. 3 questions
- Science in Korea — What Is Being Built Here Standards — Why Is a Kilogram a Kilogram? You measure with a ruler. But what was that ruler measured against? And the ruler that made it? Follow the question all the way up and you arrive at a single reference somewhere in the world. What if that reference drifts? In Daejeon there are people whose work is to see that it does not. 3 questions
- Science in Korea — What Is Being Built Here The Reactor — Getting Heat by Splitting The fusion article said heavy nuclei give out energy when split. A reactor is the machine that does the splitting. But this machine comes with something others do not have: the people who build it and the people who watch it are deliberately kept apart. All three sit in Daejeon. 3 questions
- Science in Korea — What Is Being Built Here Basic Research — Why Do What Has No Use? This series began with the question of what any of it is for. It ends at a place where the question does not apply. In Daejeon there is an institute for research that is not asked what it is good for. Why do that — and is it really of no use? 2 questions
- Science in Korea — What Is Being Built Here The Synchrotron — How a Nuisance Became Treasure Send electrons round fast enough and light leaks out. At first it was a nuisance, energy going to waste. Then it turned out the leaking light was brighter than the sun and its wavelength could be chosen, and everything changed. Pohang has two machines that make it. 2 questions
- Science in Korea — What Is Being Built Here Ships — Why Steel Floats and Why There Is a Bulb Under the Bow A steel nail sinks, yet a steel ship floats. And under the bow of every large ship there is a strange bulb. Both make sense once you know what water does. Institutes in Daejeon and Busan study that water. 2 questions
- In the Making — Things Not Yet Settled A Room-Temperature Superconductor Will Change the World — The Three Technologies That Live at Minus 269 In the summer of 2023 a Korean paper claimed a superconductor that works at room temperature. Shares jumped, laboratories worldwide rushed to check, and a few weeks later the answer was no. But the fuss revealed something: fusion, quantum computers and hospital MRI all live at the same temperature, and making that temperature is the bottleneck all three share. 2 questions
- Where Is the Electron? — The Cloud That Fills the Pitch If an atom is a football pitch and its nucleus a grain of rice, the rest of the pitch is not empty but filled with an electron cloud. An electron is not a small ball but a ripple in a field that fills the universe, and before it is measured it has no single place. Chemistry happens in that empty space. 2 questions
- One Director's Questions — The Olive Tree Below What Does a Person Leave Behind? — Information Is What Reduces Not Knowing Photos, a voice, writing, the me in someone's memory. Science calls all of it information. Information is how much it lets you know that you did not know before, so it can be measured, like a game of twenty questions, by how many yes-or-no questions it takes. But what we leave this way does not last. Photos fade, and memories blur. 1 questions
- One Director's Questions — The Olive Tree Below Do Atoms Remember Whose Breath They Were? — Feelings Travel Another Way Atoms of one kind are identical, with nowhere to record whose breath they were, and quantum strangeness unravels in a warm body faster than a blink. Yet feelings really do cross between people, riding not on atoms but on faces and voices. 1 questions
- One Director's Questions — The Olive Tree Below What Is in Empty Space? — Even Emptiness Has a Field Every point in the universe has a value of the electromagnetic field, and even the emptiest vacuum trembles with it. Between galaxies, every sugar-cube of space still holds about four hundred particles of light left from the Big Bang. Light is a ripple in that field. 3 questions
- One Director's Questions — The Olive Tree Below Why Doesn't Time Run Backwards? — Probability, Not Law, Forbids It Play a film of billiard balls backwards and nothing looks wrong: the laws of physics do not care which way time runs. A burnt book does not reassemble because scattered arrangements vastly outnumber assembled ones. Three walls that block rewinding, and the physicists who imagined universes running the other way. 2 questions