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Dear Chinese reader,

The book in your hand is a collection of fun and inspiring amateur science projects.The author, Jiamin, was a PhD student in my group in the Physics Department of the University of Arizona.I witnessed and sometimes participated in the creation of more than half of the projects in my lab.We played with the diamagnetic levitation (Chapter 7) and levitron (Chapter 8) together.From time to time Jiamin would show me other interesting stuff he made in his spare time, such as the bending laser light in sugar water (Chapter 2) and PID controlled magnetic levitations (Chapter 16) etc.Even the day before he left our lab to work in another city, he was trying to measure the microwave leakage from the microwave oven in our lab (Chapter 4).Fortunately, he didn't break the oven.

Jiamin did all these projects in a lab filled with instruments costing hundreds of thousands of dollars.However, he did not use any of this equipment for these projects.So you can also enjoy the fun experiments at home with a little bit of spare money and lots of spare time, and explore some quite broad and deep science topics.Even a professional scientist can find something new and interesting from reading the book and experimenting with the project ideas.

Time to get your hands dirty and start working on them！

Best wishes,
Brian LeRoy
Tucson, Arizona

亲爱的中国读者：

你手中的这本书汇集了许多妙趣横生而且寓意深远的业余科学项目。本书的作者加民曾是我在亚利桑那大学物理系的博士生。我目睹了书中超过半数的科学项目是怎样诞生的，有时我还会参与其中。我们一起玩过逆磁悬浮（第7章）和磁悬浮陀螺（第8章）。加民还会时常给我看一些他在业余时间做的其他好玩的东西，如在糖水中弯曲的激光（第2章），PID控制下的磁悬浮装置（第16章）等。直到他博士毕业，将要离开我们的实验室去别的城市工作，他还在实验室里尝试测量微波炉的电磁波泄漏量（第4章）。幸运的是，他没有弄坏我们的微波炉。

我们的实验室里装满了价值数十万美元的科学仪器，而对于本书中的业余科学实验，加民并没有用到这些昂贵的设备。所以你也可以在自己家中花少许的零钱和大量的闲暇时间享受这些实验带来的乐趣。同时还能探索一些涉及非常广泛和深远的科学领域。即使是职业的科学家，也会在阅读这本书及尝试完成书中的实验时有新的有趣发现。

现在，是时候行动起来开始动手实践了！

送上最好的祝福
布赖恩·勒罗伊
图桑市，亚利桑那州