Questions & Answers

In Ancient China,

How Our Ancestors

Call Mathematics?

In ancient China, calculation refers to a kind of calculating tool made of bamboo, while arithmetid means the technique which is used to operate such tool, it also means all mathematic knowledge which is relevant o maths. The official presence of arithmetic is found in Nine chapters on the mathematical art, (a well-known Chinese book on mathematics in ancient China). During the Sui and Tang dynasties, a special training organization—mathematics—was created, whose role is similar to department of mathematics of modern universities. The textbooks adopted here are arithemetic books like Sunzi algorithm, arithmetic book of five fileds(one filed is a book about which focuses on the calculation of areas, the second one is a book about which used to solve such military mathematical problems as army deploying and supplies delivering, the third one is a book about trade exchange, the forth one is a book about grain taxes and the volume of stored place, the last one is about trade exchange like silk fabric). From 19th century, western mathematic subjects like algebra, triangle, analytic geometry, calculus, probability theory, spread to China in succession. At first, the western missionary used the term mathematics, while Chinese still followed the traditional name—arithmetics. Until 1935, Chinese Mathematical Society define the exact meaning of arithmetics, but arithmetics and mathematics were both adopted then. Until 1939, Tsinghua University changed its name from department of arithmetics to department of mathematics.

Is It Safe To Turn On WiFi When Flying In The air?

Recently, Air China has began to turn on WiFi on the plane as a pilot project. The first passengers have gained access to online surfing in the sky. In the past, all eletronic equipments are forbidden on civil aircraft, and it might be a dream of faraway to log into the internet in the flying plane. The forbidden order issued by civil air transportation is because they worry about the distraction between electromagnetic signal from eletronic equipments and instruments of the plane, navigators in particular. However, after many years study, scientists find that only the raio-frequency signal of cellphone might distract instruments of the plane because working frequency for cellphone is so close to that of instruments. While other eletronical equipments, such as mobile internet equiments, with iPad as the most representative one, they send electomagnetic signal during performing and will not bring negative influence to plane itself. In the near future, we can play videos or flash microblog with abandon when we have a journey in the plane.

How Far The Spray Of Cough And Sneeze Can Fly?

Mathematists and engineering scientists in MIT, the US, recorded the scene where people cough and sneeze by a high-speed camera, and engaged in such research. The study indicates that the liquid drop sprayed and can be seen by eyes is not the culprit of many diseases, those invisible drops are the real infection source. The spreading distance for big drop is 1.2 meters, as for those tiny ones, the distance can reach 2.4 meters. What is even worse, these tiny drops are not independent propagation, they will interact with air and makes a cloud. The operating law of the cloudiness drops is just like the smoke and fog that inhaled into the nose, they can spread far away with wind flowing, and the actual spread distance can reach is 200 times that of expected distance. Therefore, for the saftey of yourself and others, please seal your mouth and nose when sneezing.