 My name is Chi Ting Chan, I'm from Hong Kong and I do research on the theory of wave equations and material science and one of the topics that I have been working on in the past couple of years is about invisibility clocks. A so-called clock works by guiding a wave away from an object and if you ask me you say that you know who cares why why should I have such a technology and one application that I can think about is for example you want to exclude a wave from a certain area, certain domain to protect yourself say for example an earthquake is coming now earthquake is in fact the kind of wave a vibration of the earth crust and you say that okay I do not want the earthquake to affect my community and then in principle I would say in principle in practice it's not easy but in principle you can design a clock around the city so as to guide the earthquake wave away from the community to somewhere else in which the damage is less. It is about designing materials that can do wonders and it turns out that for most of the time the materials take for example the invisibility clock the material needed cannot be found in nature and then we have to design them we have to make them and these type of knowledge in the long run can help industry to design new materials that can go beyond go beyond what the material in nature can do for us.