Say you woke up one day and your bed was gone. Your room, too. Gone. It's all gone. You wake up in an inky void. Not even a star. Okay, yes, it's a dumb idea, but just go with it. Now say you want to know if you move or not. Are you held fast in one spot? Or do you, say, list off to the left some? What I want to ask you is: Can you find out? Hell no. You can see that, sure. You don't need me to tell you. To move, you have to move to or away from... well, from what? You'd have to say that you don't even get to use a word like "move" when you are the only body in that void. Sure. Okay. Now, let's add the bed back. Your bed is with you in the void. But not for long - it goes away from you. You don't have any way to get it back, so you just let it go. But so now we have a body in the void with you. So does the bed move, or do you move? Or both? Well, you can see as well as I that it can go any way you like. Flip a coin. Who's to say? It's best to just say that you move away from the bed, and that the bed goes away from you. No one can say who's held fast and who isn't. Now, if I took the bed back but gave you the sun - just you and the sun in the void, now - I'll bet you'd say that the sun is so big, next to you, that odds are you move and not the sun. It's easy to move a body like ours, and not so easy to kick a sun to and fro. But that isn't the way to see it. Just like with the bed, no one can say who's held fast. In a word, you can't find any one true at rest. Izzy was the one who told us that. Izzy said that you can't tell if you move or are at rest at any time. You can say that you go and all else is at rest, or you can say that you are at rest and all else goes. It all adds up the same both ways. So we all knew that much from way back when. Aha, but now wait! The sun puts off rays! So: why not look at how fast the rays go past you? From that you'd see how fast you move, yes? For you see, rays move just the same if what puts them off is held fast or not. (Make a note of that, now.) Izzy had no way to know that, back then, but it's true. Rays all move the same. We call how fast that is: c. So, you can see how fast the rays go by you, and how far off that is from c will tell you how fast you move! Hell, you don't even need the sun for that. You can just have a lamp with you - the one by your bed that you use to read by. You can have that lamp in your hand, and see how fast the rays go by you when you turn it on. The lamp will move with you, but the rays will move at c. You will see the rays move a bit more or less than c, and that will be how fast you move. An open-and-shut case, yes? Well, and so we went to test this idea out. Hey, you don't need to be in a void to do this test. We move all the time, even as we sit here. We spin, in fact. So they shot some rays off and took note of how fast they went east, and how fast they went west, and so on. Well, what do you know? The rays went just as fast both ways. All ways, in fact. They all went at c, just the same. Not an iota more or less. To say that we were less than glad to find that out is to be kind. It blew the mind, is more like it. "What is up with that?" we said. And here is when old Al came in.🏁

Say you woke up one day and your bed was gone. Your room, too. Gone. It's all gone. You wake up in an inky void. Not even a star. Okay, yes, it's a dumb idea, but just go with it. Now say you want to know if you move or not. Are you held fast in one spot? Or do you, say, list off to the left some? What I want to ask you is: Can you find out? Hell no. You can see that, sure. You don't need me to tell you. To move, you have to move to or away from... well, from what? You'd have to say that you don't even get to use a word like "move" when you are the only body in that void. Sure. Okay. Now, let's add the bed back. Your bed is with you in the void. But not for long - it goes away from you. You don't have any way to get it back, so you just let it go. But so now we have a body in the void with you. So does the bed move, or do you move? Or both? Well, you can see as well as I that it can go any way you like. Flip a coin. Who's to say? It's best to just say that you move away from the bed, and that the bed goes away from you. No one can say who's held fast and who isn't. Now, if I took the bed back but gave you the sun - just you and the sun in the void, now - I'll bet you'd say that the sun is so big, next to you, that odds are you move and not the sun. It's easy to move a body like ours, and not so easy to kick a sun to and fro. But that isn't the way to see it. Just like with the bed, no one can say who's held fast. In a word, you can't find any one true at rest. Izzy was the one who told us that. Izzy said that you can't tell if you move or are at rest at any time. You can say that you go and all else is at rest, or you can say that you are at rest and all else goes. It all adds up the same both ways. So we all knew that much from way back when. Aha, but now wait! The sun puts off rays! So: why not look at how fast the rays go past you? From that you'd see how fast you move, yes? For you see, rays move just the same if what puts them off is held fast or not. (Make a note of that, now.) Izzy had no way to know that, back then, but it's true. Rays all move the same. We call how fast that is: c. So, you can see how fast the rays go by you, and how far off that is from c will tell you how fast you move! Hell, you don't even need the sun for that. You can just have a lamp with you - the one by your bed that you use to read by. You can have that lamp in your hand, and see how fast the rays go by you when you turn it on. The lamp will move with you, but the rays will move at c. You will see the rays move a bit more or less than c, and that will be how fast you move. An open-and-shut case, yes? Well, and so we went to test this idea out. Hey, you don't need to be in a void to do this test. We move all the time, even as we sit here. We spin, in fact. So they shot some rays off and took note of how fast they went east, and how fast they went west, and so on. Well, what do you know? The rays went just as fast both ways. All ways, in fact. They all went at c, just the same. Not an iota more or less. To say that we were less than glad to find that out is to be kind. It blew the mind, is more like it. "What is up with that?" we said. And here is when old Al came in.🏁