Physicists reverse time using quantum computer

Researchers from the Moscow Institute of Physics and Technology teamed up with colleagues from the U.S. and Switzerland and returned the state of a quantum computer a fraction of a second into the past. They also calculated ...

'Space ball' drops on Namibia

A large metallic ball fell out of the sky on a remote grassland in Namibia, prompting baffled authorities to contact NASA and the European space agency.

Observing clouds in four dimensions

While easily seen by people, the cotton-ball clouds (called shallow cumulus clouds) that drift overhead on partly cloudy days are hard for radars and many other instruments to observe and, therefore, hard to model and predict. ...

Study explains the mystery of ball lightning

(—Sightings of ball lightning have been made for centuries around the world – usually the size of a grapefruit and lasting up to twenty seconds – but no explanation of how it occurs has been universally accepted ...

Fast bowlers who bowl no-balls in cricket need to do the maths

Good fast bowlers add plenty of spice to the game of cricket but they're also prone to bowling no-balls. If they just started their run ups from a little further back most could probably eliminate no-balls altogether, so ...

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A ball is a round, usually spherical but sometimes ovoid, object with various uses. It is used in ball games, where the play of the game follows the state of the ball as it is hit, kicked or thrown by players. Balls can also be used for simpler activities, such as catch, marbles and juggling. Balls made from hard-wearing materials are used in engineering applications to provide very low friction bearings, known as ball bearings. Black powder weapons use stone and metal balls as projectiles.

Although many types of balls are today made from rubber, this form was unknown outside the Americas until after the voyages of Columbus. The Spanish were the first Europeans to see bouncing rubber balls (albeit solid and not inflated) which were employed most notably in the Mesoamerican ballgame. Balls used in various sports in other parts of the world prior to Columbus were made from other materials such as animal bladders or skins, stuffed with various materials.

As balls are one of the most familiar spherical objects to humans, the word "ball" is used to refer to, or to describe, anything spherical or near-spherical.

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