Here are some thoughts on something that has been bothering me for a while. How do we know the world is the way it is? Easy, a pragmatic person would say, just look and measure. We see a tree, a chair, a table; we hear the wind, music, people talking. We feel heat and cold against our skin. Once our brains integrate this sensorial information, we have a conception of what is real that allows us to function in the world. We know where to go, what to eat, what not to touch; we enjoy a good meal, a nice hug. But what happens when we go beyond our senses, using tools to extend our conception of reality? We don’t see galaxies with the naked eye (well, maybe Andromeda on a moonless, dry night) and much less a carbon atom. How do we know they are there, that they exist?