字幕列表 影片播放 列印英文字幕 Tadashi: So here's a mirror of sorts, it's curved. And in front of this mirror, I put this rectangular sheet (with something drawn on it). And when you put it in front of the mirror and look inside the mirror you see a cat. You know, with pointy ears and side protrusions that look like whiskers and everything. So, I am very happy with this cat. I'm proud of this cat. A nice cat, I will say. But when I show this to a mathematician and theoretical physicist colleagues Some people like this because they have good taste. But others say So? Well, that's really sad. I hoped that they didn't say so. But for those of us who'd like to say so: here's the thing. In front, you have a mirror, indeed but that's what we call a "convex mirror." So it's bulging out towards us. In the back, inside of the tube there is a concave mirror. Which is bulging away from us. So now, I'm going to put another cat inside and look at what happens. And if you look from the correct angle you see another cat inside. By the way, some people might wonder how many reflections are bouncing off before it reaches our eyes. But in fact it is just one reflection. It's reflecting on the back side and then coming out. So you have a cat on the inside. Now, the slightly odd thing is that cat on the inside looks very much like the cat on the outside. Although the cat on the outside is from a convex mirror whereas the cat on the inside is from a concave mirror. So convex and concave I mean they are opposite things and you might expect the distortion effects to be the opposite but they look very very similar. So that's quite interesting. It's not much of a hint but one thing that has to do with this effect is the following. This arrow is pointing from left to right. And if you look at it's image reflection in the mirror in front, the convex part it's still pointing from left to right. But let's look at it on the inside on the concave mirror. It's pointing from right to left! So that's quite interesting it reversed it's direction. So, it's a matter of where the center of focus you are placing the arrow. As I move the arrow inside, or according to the outside, move the mirror you see the arrow changing it's shape and somehow it sort of blurs out and eventually at the end you come to the point where you see the real image next to the original arrow. So you can do something like this with a cylindrical mirror and little rectangular sheets of paper. When I first thought of this you know I thought something like this might be interesting to try. The major problem I faced was where do you find a cylindrical mirror? I mean, if you have a flat mirror you know, slightly bulging out or bulging in so it changes the size of your image and so in a way, you can find that in cosmetic shops and so forth. But where do you find a cylindrical mirror? A tube-like mirror? And I thought and I thought and finally I went to the shopping center and I found one! These are cookie cutters! It's a cookie cutter, you know, where you make the cookie dough and then cut the shapes. So you can buy 1 for $1. And, with that you can make a cat in the mirror! Brady: A cat in the cookie cutter? Tadashi: That's right!