# The Up-Goer Five

## Prologue

The following text is an attempt to explain my PhD work under the constrain stated in the Ten Hundreds Words of Science Challenge. As described in the previous link, the idea is to write about “complex scientific concepts explained using only the thousand most used words in the English language”. This limit and the choice of these “most used“ words is debatable but this is the rule! I discovered this concept in the December 2014 issue of the CAP Journal, and suggest you to read this article if you wish to get all of the philosophy behind this original idea.

## Ten Hundred Words of Science

Take a ball and make it turning on your finger like a top. It's not so easy, but you can try! If you follow the dance of some points on the ball, you will see that they are moving very quickly around it, except at two positions: where your finger touches the ball, at the bottom, and just on the other side, at the top. If you join these two points, you draw a line around which the ball is turning. Now, move to something really, really bigger!

We are living on a very big ball, most of it being full of rocks stronger than ice. Our ball of rocks turns, like the smaller ball in the story above, in nearly twenty four hours a day: this is why there is night after day and day after night, this is why you can see the sun moving in the sky all the day long. Like you did with the small ball, you can imagine a line around which everything in our world is turning and two points on it where nothing moves. It is very cold near these two places, with a lot of ice and wind, and the day and night last half a year in these areas!

What is interesting is that the line around which we are turning, is changing with time, our big ball turns around a different line, and more or less quickly, at different moments. That is to say, the two points pictured above are moving too, they are dancing around, drawn by the moving line on our ball. You can think it should make you sick if your home were turning a different way all the time but don't worry, in a few years the points are turning around or moving in a straight line as far as you can go by foot in a few minutes!

Most of these moves are there because of the force of the Sun or other bodies of rocks around us in the space that change the way our own world turns around its line. But one of these moves is something different because it doesn't need another force to be there, we say it is “free” (because not “forced”) and call it after the man who found it: Mr Chandler. It just needs our ball to be slightly different, like one a little bit pressed at the top and bottom... and this is actually how our world looks like, not a perfect round ball! We don't know exactly how it works but to excite or start this different move, you just need something to push our ball in some way from times to times. We think it's the air and the water on our world which can play this game.

In my work, I study this dance of the line (or points) around which we are all turning, especially this last Mr Chandler move and the way it lives and dies after being excited. In fact, during these moves, our ball of rocks changes, even if rocks seem to be very strong. It's like ice, it is very strong but if you wait for a long time, it moves and changes like water. I try to understand how our ball changes when it turns in a different way, and in the same idea, how a change inside or outside our world makes it turning in a different way too. These things help to better understand how our world ball works, especially when we want to know how it is changing and moving inside over several months, years or more.