Could you change Earth鈥檚 rotation by all running at the same time?
A reader wondered what would happen if everyone in the world gathered in one place and started running. The answers are in
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Swimming strokes: which is the fastest?
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This week鈥檚 new questions
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Physics
Mathematician Eugenia Cheng on the abstract wonder of category theory
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Technology
Psychedelic baby turtle wins 2019 Nikon Small World photography prize
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Space
Spot six planets in the sky this week: Mercury, Mars, Uranus and more
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Health
Will the planet ever be free from the scourge of polio?
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Space
How to use the Orion constellation to find Sirius the dog star
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What makes Donald Trump orange, and other taxing questions
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In the ink: why are blue highlighter markers less bright than others?
Blue fluorescent markers are less bright than green and yellow ones. The reasons, say readers, are to do with our eyes as well as the wavelengths of light
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Good consumers: is online shopping greener than going into town?
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This week鈥檚 new questions
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Jet suits, giant moons and new science 鈥� this was 快猫短视频 Live
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Mind
Joseph Plateau鈥檚 spinning disc illusions were the forerunner of cinema
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