 Fy enw'n gweithio. Mae'n ddweud i'r Gweithgellau Cymru yma ar y newid yn 2015 arall. Yn cymhiystedd yw'r rhaglen iawn. Mae'n gwneud yr ysgol iawn o'r ffordd, ond y gallwn gwneud o'r ffordd o'r ynnod. Mae'n lle i'r Lofty, ac mae'n fawr yn ymgymryd. Mae'n ddweud yn ymddangos i'r holl oherwydd mae'r newid yn ymddangos gyda'r coleg. Professor Che Ting Chan, Professor in Department of Physics at Hong Kong University of Science and Technology in the Hong Kong SAR. Delights to be joined by you, Professor. Maybe a brief introductory note to you. We're going to have a conversation here. We have some questions that have come in from social media over the preceding hours. We will have some media here in the room, but hopefully we'll try to keep this as a free-flowing conversation as possible. I just want to find out more about what you're doing, frankly. What is about your project of making objects invisible? Oh, thank you, Oedipa. It was indeed my pleasure to be here. We do a lot of work on wave and how do we manipulate wave and understand better the wave equations? Invisibility is just one of the projects that we have been working on. So it's all about how can we manipulate wave. Then we try to solve more challenging problems. Now, of course, we all know that the wave equation for all kinds of waves is a very old subject. It has been around for at least 100 years. But what are the implications? What are the limitations? What can we do? What are possible? What are impossible? A lot of these questions have not been answered up to today. Invisibility is one of the standing problem that was not solved until about eight or nine years ago. This is one of those challenging problems that we want to solve. But I do want to emphasise that this is not the only problem that we are working on. The broader topic would be like, let's try to understand better the wave equations and see what are the implications. What can we do and what we cannot do? What are possible and what are impossible with the design? In fact, the key area of our research. Let's just develop that a little bit. Bearing in my visit a very generalist audience, I'm afraid I'm not a scientist. I suspect our audience aren't scientists too. We've known about these waves, these electromagnetic waves, for about 100 years. Eight or nine years ago you said that the principle was established that invisibility could be proven. Tell us a bit more about how that works. Okay. Now, let me take one step back and ask the question, why do we people want to do invisibility? Now, maybe science fiction type of motivation is that I do not want to be detected. Now, there is already a very mature technology called the stealth technology that are being used now and so that military aircraft cannot be detected by radar. Now, then is it good enough? It turns out that stealth objects are not invisible. They actually leave a shadow and so that there are in fact ways to detect a stealth aircraft. For example, if you have a aircraft here, if I have a radar in the back, my sensor is in the front. In fact, the stealth object will leave a shadow so that the sensor can in fact detect the stealth. Now, invisibility will take that to the extreme that invisibility means I have a stealth object that leaves no shadow. So there's no way that you can detect that. And so this is one motivation why people want to do that. This was established in principle recently in the past few years. One of the things we often discuss here at the World Economic Forum meetings and everywhere else is the exponential rate of change in the world and the rapid evolution of innovation as increasingly intensifying and accelerating. It's taken us from 100 years ago to a few years ago to prove this theory. I'd like you to just look forward a little bit and give me some, give us an idea of when you think this. We'll be able to see or not see perhaps. When we'll actually witness the first practical demonstration of this technology. Oh, it has been demonstrated and also has been demonstrated for optical frequencies, usually what we call light in some specific circumstances. Demonstrated in what, can you give us some examples of how you've done this? What objects have you made invisible? First of all, I have to say that I'm a theorist and therefore I only do the theory or do the simulation. But there are experimentalists in all parts of the world that have demonstrated that they can really fabricate what they call the invisibility clock. For the microwave what they did is that they basically have a clock which is something like a circular object and they can put something inside and once they do so then your microwave, which is similar to radar, will not be able to detect that object. Now for the optical frequency what they mean is that they have again a certain device and you can put something in and then you cannot see that thing. But for the optical frequency it's very difficult because due to a lot of reasons that so far it can only be done in a certain very special environment. It cannot be done in, for example, as far as I know, no one can really make a code to make you invisible. So you have to be in some special environment. Okay, okay. Military application is quite clear. I can see why that would work. What other applications do you envisage for the technology you're developing? Oh, now one condition that we can achieve this so-called invisibility is that we actually have to exclude the wave from entering a certain domain. Now that is useful for some purposes. For example you do not want to be, for some reason, bordered by some kind of signal. Signals are waves and then that kind of technology can actually shield you from that kind of wave that you don't want. And for example there are waves that are harmful. For example earthquake is in fact a kind of wave and if you really can control the earthquake wave and do a cloak for that one, that means that actually you can guide the vibration away from the property you want to protect and guide it to somewhere else. Anyway, this type of technology can help someone survive better in a hostile environment. That's fascinating. So essentially you could protect cities from earthquakes? In principle yes. But of course you have to have some land that also outside the city or that village. You have to have some, you know, a lot of areas so that you can implement that kind of structure. If you can afford the land to do so, then in principle it's possible to guide the wave away from the area that is critically important that you need to protect. But I want to add a little bit more because a lot of times this type of research is not just about wave, it's all a lot about materials. Because by the end of the day what we found is that for example if we want to implement a cloak of invisibility, it turns out that we solved the equation and we found that the material needed, we can design them, none of them exists in nature. Then we have to design them and someone have to make them. And that again is very important because let me just take one example. Let me just take my eyeglass and your eyeglass. This is a very, very simple thing. It's just one single material, basically glass, which is silicon dioxide. And then a very simple structure, just a curve and it can do your eyeglass, it can be a telescope, it can be a microscope, it can do wonders for us already. But however, can we for example use this type of thing to see a virus? The answer is you cannot. But is it forbidden by the laws of nature? The answer is no. It simply is that we do not have the material in nature that can do that. So a lot of our research is about solving the wave equation or solving the equation. And then find out what material is required and almost 99% of the time we find that those materials you cannot find in nature. And then we, in collaboration with experimentalists and engineers, we try to really create those structures. And then for example, I would say that essentially old invisibility clock, you have to make them as artificial material. And then it is not just about understanding better the way the equation is about pushing the boundary of creating new materials that can do wonders for us. I think that is another important message that I would want to give. It is a very important point because often we talk about the intersection of various disciplines of science. It sounds like your work has probably quite vast commercial potential in new materials. Anything you can tell us about any commercial applications for materials that have been developed or materials that you envisage developing in the near future? Right now these are quite conceptual, but I would, at least I hope that maybe in the near future, not too far from now with these ideas of a better understanding of the wave equation and the associated advanced material, then we would have better lenses and lenses that allow us to see smaller objects. And we will also be able to have structures or materials that can absorb waves better. That sounds to be a very simple thing, but absorbing a lot of waves is not that easy. For example, if you think about photovoltaics or people called solar energy, it is all about absorbing the light from the sun and converting hopefully the maximum of the energy there into a useful form of energy. But usually the commercial solar energy panel that we can buy on the market, we are talking typically about 10 or maybe 12% efficiency. Now if we can have artificial materials that can absorb better and then we can have a much better way of using energy and for example the same type of idea can help us for example absorb sound waves better. And you will say that who cares, but most of us are bothered by noise. If we have structures that are thin and light, they can absorb sound better and that would be good. The kind of research we are working on with a very simple modification can also be used to achieve those purposes. Which I imagine would have again vast commercial potential maybe in building new buildings where you need less thinner walls between apartment blocks for example. Very, very interesting. Our meeting is about bringing scientists together with businesses and different disciplines. You have been here professor for a day now, this is day 2 of the meeting. From the sessions you have been in, and I saw you in one of the ideas in the lab yesterday. Are there any particular sessions or any other areas of science that you have found particularly interesting in terms of in the context of potential collaboration or using your knowledge of physics and of waves and working in a different area of science. Are there any areas of collaboration that you think you would like to explore having been here for a day? I have to say that it has been really a wonderful experience for me so far that I have the opportunity to listen to and learn about things that I usually do not have a chance to listen to. I went to quite a few idea labs already and also I went to one of these what ifs about mind reading. Of course mind reading one is really very, very interesting. In a way, although the speakers of that particular what if session, the mind reading about EEG and about functional MRI. But you think about what are these techniques. This is about some kind of sensing that they want to know what are the signals in your brain. And I expect that the kind of theory that we are working on, we are talking about, in a way we are talking about sensing. We are talking about using a wave to go into an object and then we look at here the echo. And then we try to see whether it is possible or not possible to know what is happening inside. And so I think there may be ways in which that we can probe our brain or other parts of the body with this kind of non-invasive type of technology. And then we can see then understand better what is happening inside and what are the implications. Of course I am just talking out of my head and it is not going to be easy because there are many challenges. For example the whole idea of invisibility is in fact telling us that if I stand away I want to detect something. What come back to me may not be a unique solution. For example invisibility actually means that you have an object and if I can croak that object then there is no way that an outside observer can tell whether the object is there or it is not there. But by doing that kind of exercises then we come to understand much better about how much or how far or how precise we can by listening or looking at the echoes of way we stand in how much can we learn about what we want to know. And the better we know about these processes I think the better we know how to use wave to detect and to identify and to characterize something. And I think the most exciting and useful application for mankind I would say is to use wave to understand and identify and know what's happening inside our body. And that I think would be a very, very useful but also extremely challenging task in the future. I think I will go back and think about that. I think we should all think about it so it's fascinating absolutely and I'm humbled that the idea was born here in the Darling Convention Centre. Professor it's been fascinating talking to you. Before we close I must invite our audience to ask any questions if you have any. Okay so let's see we've covered quite a lot of ground already. I hope to have you back. This is a very fast moving space professor and we'd love you to join us again for an issue briefing to talk about the ongoing and evolving work in this field. Thank you all for joining us and thank you to our audience watching online.