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What happens to a planet if you change one of the things we take for granted? These experiments look at Earth, the Moon and the Sun with simplified physics you can actually turn. They are thought experiments with numbers attached — useful for building intuition, not for predicting a real catastrophe.
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What If Earth Stopped Spinning?
Remove Earth's spin over a time you choose and see the leftover eastward speed, the winds, and the new length of a day.
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10 interactive experiments.
What If Earth Stopped Spinning?
Remove Earth's spin over a time you choose and see the leftover eastward speed, the winds, and the new length of a day.
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What If the Moon Disappeared?
Take the Moon away and separate tonight's tides and darker skies from the slow, million-year question of Earth's tilt.
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What If the Sun Disappeared?
Light and gravity from the Sun are 8 minutes 19 seconds old. After that, Earth goes straight and the dark is not instant ice.
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What If Earth's Gravity Doubled?
Scale surface gravity and compare weight and jump height. Same takeoff energy, higher g, lower flight.
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What If Earth Had Two Moons?
Add a second moon with a mass ratio and a distance in lunar units. Tidal forces add in a simplified way — not a three-body simulation.
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What If Everyone Jumped?
Eight billion people take the same standing jump. Earth's recoil is real — and so small the planet does not notice, especially once everyone lands.
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What If Earth's Atmosphere Disappeared?
Dial remaining pressure from today's sea-level air toward vacuum. Sound, sky, boiling water and radiation change on different clocks.
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What If Earth Rotated Twice as Fast?
Spin Earth faster and watch the day shrink, equatorial speed rise, and a small centrifugal lightening at your latitude.
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What If Everyone Disappeared?
A scientific succession timeline: power, water, plants, buildings. Pick a year and see a sober sketch of that moment.
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What If Earth Was Twice as Large?
Enlarge Earth's radius two ways: keep density (g rises with R) or keep mass (g falls as 1/R²). The assumption is the whole experiment.
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