tailieunhanh - English for students of Physics_Unit 11

Science tries to explain a very complicated world. We are surrounded by very many objects, moving around, reacting together, breaking up, joining together, growing and shrinking. And there are many invisible things, too - radio waves, sound, ionizing radiation. If we are to make any sense of all this, we need to simplify it. We use models, in everyday life and in science, as a method of simplifying and making sense of everything we observe. A model is a way of explaining something difficult in terms of something more familiar. For example, there are many models used to describe. | 85 Unit Eleven QUANTUM PHYSICS READING PASSAGE Making macroscopic models Science tries to explain a very complicated world. We are surrounded by very many objects moving around reacting together breaking up joining together growing and shrinking. And there are many invisible things too - radio waves sound ionizing radiation. If we are to make any sense of all this we need to simplify it. We use models in everyday life and in science as a method of simplifying and making sense of everything we observe. A model is a way of explaining something difficult in terms of something more familiar. For example there are many models used to describe how the brain works. It s like a telephone exchange - nerves carry messages in and out from various parts of the body. It is like a computer. It is like a library. The brain has something in common with all these things and yet it is different from them all. These are models which have some use but inevitably a model also has its limitations. You have probably come across various models used to explain electricity. We can not see electric current in a wire so we find different ways of explaining what is going on. Current is like water flowing in a pipe. A circuit is like a central heating system. It is like a train carrying coal from mine to power station. And so on. All of these models conjure up some useful impressions of what electricity is but none is perfect. We can make a better model of electric current in a wire using the idea of electrons. Tiny charged particles are moving under the influence of an electric field. We can say how many there are how fast they are moving and we can describe the factors that affect their movement. This is a better model but it is harder to understand because it is further from our everyday experience. We need to know about electric charge atoms and so on. Most people are happier with more concrete models as your understanding of science develops you accept more and more abstract models. .