If Mars can come within roughly 55 million kilometers of Earth, why does a spacecraft sent there travel something closer to 480 million kilometers — and spend around seven months doing it? The answer is one of the most important ideas in sp...
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There is a moment at almost every birthday party when the room changes. The lights dim, a cake appears, tiny flames tremble above the icing and everyone waits while one person silently makes...
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You are almost asleep when the floor seems to disappear. For a fraction of a second, your body feels as though it has stepped off a ledge. A leg kicks, an arm jerks or your whole torso jumps...
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Stay in a swimming pool or bathtub long enough and something peculiar happens to your hands. The smooth pads of your fingers turn into a landscape of ridges and valleys, as if the skin has s...
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Dog owners become experts in noticing small mysteries. One week the mystery is a dog that seems unable to stop licking its front paws. The next it is the same animal stepping onto the lawn a...
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It often begins so subtly that you wonder whether you imagined it: a tiny flutter under one eye, a faint pulse in the eyelid, then another. A few minutes later you are staring into a mirror,...
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There are few moments quite like looking into the toilet and discovering that something which is normally brown has turned unmistakably green. It is the kind of question many people would ra...
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A cat is calmly eating from its bowl. While its attention is elsewhere, someone quietly places a cucumber on the floor behind it. The cat turns, sees the vegetable and suddenly launches itse...
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A newly hatched chick enters the world with an urgent problem. It can walk almost immediately, but walking in the wrong direction could be fatal. In nature, staying near a parent means warmt...
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In 1997, IBM's Deep Blue defeated world chess champion Garry Kasparov in a match. The achievement looked like a milestone on the road to machine intelligence: a computer had conquered a game...
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