What Causes Volcanoes?
Volcanoes appear where rock deep underground melts, and rock melts for three reasons: lower pressure, added water, or extra heat. Each dominates in a different setting.
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Why Does Ice Float?
Water is unusual: it is densest just above freezing, so the solid form is lighter than the liquid. That single anomaly is why lakes freeze from the top and life survives the winter.
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How Do We Know Atoms Exist?
Nobody sees atoms with ordinary light. They were inferred from Brownian motion, measured indirectly for a century, and then eventually photographed one at a time.
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Using Supernovae to Hunt for Particles Nobody Has Seen
A physics team has proposed using the gas a dying star throws off before it explodes as a detector for extremely weakly interacting particles, and set new limits using a recent supernova.
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Why Data Centres Are Turning to Nuclear Power
Commitments to build AI computing capacity are now arriving with power agreements attached, including nuclear deals running for decades. The constraint has stopped being chips.
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How Do We Know the Age of the Earth?
The Earth is about 4.54 billion years old, and we know that because certain atoms decay at a fixed rate. Rocks containing them behave as clocks that started when the rock formed.
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How Does a Plane Stay Up?
A wing generates lift by pushing air downwards. The popular explanation involving air travelling further over the top is wrong, and the correct one is simpler than it sounds.
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Why Is the Ocean Salty?
Rivers carry dissolved minerals into the sea, and evaporation leaves the salt behind. The reason the ocean is not getting saltier is that just as much salt is being removed.
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What Happens Inside a Black Hole
Crossing the event horizon is not like hitting a surface. The honest answer about the interior is that our current physics stops working there, and that is the interesting part.
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What Causes the Seasons?
Seasons are not caused by how far Earth is from the sun. They are caused by a 23.4 degree tilt that changes both how directly sunlight arrives and how long it stays.