A paradox by Zeno of Elea (Italy, born about 488 BC.)

It arguments: The flying arrow is at rest. At any moment, it is in a space equal to its own length, and therefore is at rest at these moment. So, it's at rest at all moments. The sum of an infinite number of these positions of rest is not a motion.

This paradox must be compared and contrasted with Albert Einstein's thought experiments (Gedanken experiments) about motion. The train experiment, the elevator one and the spacetime's contraction as consequence.

Explaining in detail the gedanken-experiments mentioned is out of the reach of this node, but the concept behind them is the key to understand the relation with Zeno's paradoxes. On both experiments, the speed of light is considered a constant, while the length of the body in motion shortens. It is, the arrow in motion do not really "is in a space equal to its own length", it is shorter because it is in motion with respect to the observer.

The ironic part on it is, Zeno had on his mistaken view of the motion a logical tool that suggested the special theory of relativity. About 400 BC. But it took about 2300 years for someone to give it a scientific sense.

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