Thursday, August 10, 2006


The title of this post is “A,” as in “Q&A,” so if you haven’t read “Q” yet, check it out.

This image isn’t a meteor or disguised space-craft or a catapulted rock. In fact, this boulder is not moving at all. This painting by René Magritte (1898-1967) is entitled La flèche de Zénon (Zeno’s Arrow).

Why “Zeno’s Arrow?” This is a boulder not an arrow.

Well, Zeno (490BC-425BC) is known for his paradoxes dealing with motion, two at least “proving” that motion is impossible.

1) DICHOTOMY PARADOX: In order to move a given distance an object must reach the halfway point, but before it travels from the starting point to the halfway point it must get halfway there, and before it reaches that point . . . (you see where this is going – nowhere!). If space can be infinitely divided, then an infinite number of time intervals must pass before an object moves any given distance, therefore it cannot move.

2) ARROW PARADOX: When an arrow is in a place just its own size, it’s at rest. At every moment of its flight, the arrow is in a place just its own size. Therefore at every moment of its flight, the arrow is at rest (i.e. not moving).

Although it seems gravity should pull the boulder into the ocean, according to these paradoxes the boulder is at rest and will remain so.

These paradoxes may sound silly (since you know that things actually do move), but try disproving them logically! If they don't work, why not?


David Meyer said...

Hmmmm. This brings to mind greater infinities.

Enough said?

Your always questioning and loving husband.

Ellen said...

That just makes my brain hurt. :-P