Whatever may be the explanation, an out-of-control playground swing has got families and police in Argentina spooked.
The swing apparently rocks back and forwards without being touched - and anxious parents have decided the playground must be haunted.
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Police in the north-eastern town of Firmat were worried enough to call in physics professors - but they have been unable to explain the mystery motions.
The swing can keep moving continuously for ten days before suddenly coming to a halt, it has been claimed.
And one child has supposedly nicknamed the area the "Blair Witch Playground", claimed teacher Maria de Silva Agustina.
