## 2009年4月18日 星期六

### An Exhibition about Mathematics

A few days ago I went to an exhibition called "Mathema". Below are some random pics I took at the exhibition. (Highlight the space to see the answer.)

What is the purpose of this machine?

Answer: For computing binary numbers.

Can you relate this picture to a famous parable?

Answer: "The parable of the rice grains".

What is the purpose of this machine?

Answer: The Germans used this machine for sending encrypted messages (known as the Caesar's code) during WWII. Note that the the three vertical wheels (just above the keys) will turn the keys, and they allow three degrees of freedom for doing encryption. The guide told us that the British actually broke the code during the war, as the Germans did not use the machine in a careful way. (They always begin their messages with Dear ... ==" )

Why are the above two maps different?
tance, an area r
Answer: Each of the two maps preserve a certain quantity: distance and area respectively.

These two books list out the first 4 million digits of pi!

You can "see" how the Pythagoras' Theorem works by turning the wheel!

This is what NASA sent to the space for aliens to read~

Why is this number so special?

Answer: This number is called "googol", and the name of the famous search engine "google" was inspired by it.

Along which path will a ball from the upper point reach the lower point in the least time?

Answer: Along the curve. This is the famous "Brachistochrone curve". This curve has another remarkable property: the time it takes for the ball to reach the lowest point is always the same, regardless of the starting point!

Mathematicians regard this as the most beautiful theorem in the world. This formula appears so simple but yet it involves some of the most important constants: 1, 0, e, i, pi.