Sunday, December 09, 2007

Enlightenment!

Not Nirvana just yet, anyways, I came across a stunning revelation on the bus that day, Zeno's paradox is no paradox, it's simply a misinterpreted math question. For those who are clueless to what I'm talking about, here's the paradox

In the paradox of Achilles and the Tortoise, we imagine the Greek hero Achilles in a footrace with the plodding reptile. Because he is such a fast runner, Achilles graciously allows the tortoise a head start of a hundred feet. If we suppose that each racer starts running at some constant speed (one very fast and one very slow), then after some finite time, Achilles will have run a hundred feet, bringing him to the tortoise's starting point; during this time, the tortoise has "run" a (much shorter) distance, say one foot. It will then take Achilles some further period of time to run that distance, in which said period the tortoise will advance farther; and then another period of time to reach this third point, while the tortoise moves ahead. Thus, whenever Achilles reaches somewhere the tortoise has been, he still has farther to go. Therefore, Zeno says, swift Achilles can never overtake the tortoise. Thus, while common sense and common experience would hold that one runner can catch another, according to the above argument, he cannot; this is the paradox.

Here's a similar old timer question that bugged me for ages and bugged yanwen for even longer.

3 people eat at a restaurant and the bill comes up to $30, so each pay $10 to the waiter. The manager decides to give a discount and returns $5. However, the waiter decides to keep $2 for himself and returns $3 to the customers (by giving each a dollar). Each of them has now paid $9 each right? 3 x 9 = 27, and 27 plu the 2 dollars with the waiter is $29. What happened to the missing dollar?

Go figure. I know all your brains are rusting after exams.

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