 Hi, this is Ralph Wildman and my friend Matt. We're going to be here talking to you today about the Thermotrope early early optical device and Let's look at one right now. This is a Thermotrope disc and Basically, it was it is a two-sided disc a picture on one side a picture on the other and it it is like one side Is a vase and the other side is flowers and when you twirl it and See it over and over again. It looks like flowers in a vase a very simple idea Thermotrope was invented in 1825 That makes it almost 200 years old Matt. Who was president in 1825? John Quincy Adams, right? Very good. Now. This is a this is a very old device and John Quincy Adams Probably children got one of these for Christmas a box of thermotropes Now you want to try it? Okay, here's one for you. I'll be one, too. You wind yours up. I'll wind mine up Hold it by the string very good and then just turn it turn it and turn it and turn it And then stop and pull and what happens? It's like an image comes What was your image? Person trying to catch Did he catch him Yeah, looks like you did it. Okay Well, the reason that happens is because if you look at one side and the other side in rapid motion They become one picture. So he did catch the pig That's called the persistence of vision because if you look at one picture and then take it away and then show another picture You hold this picture for one eighth of a second and that allows you to connect that picture to this picture And if you see it very rapidly they fuse and become one picture. You got that? So that's about the same thing that happens in a motion picture house when you go to see a movie you see 24 frames 24 pictures every second hard to believe isn't it? Yeah, it's very difficult But nevertheless, that's what gives us the illusion of motion You think you'd like to make one? Yeah, okay, let's start Very good. So that's the thermotropes It's an example of the persistence of vision and it's the phenomenon behind all the modern media