Chapter 11: The Clerk From the Patient Office

We know that space is three dimensional; it has three independent directions at right angles to eachother-north, east, and up (like a corner of a building). Although the structure of space at all points is the same, the matter that occupies it may vary. Objects in space can be moved in different ways; they can be rotated, reflected, and translated. But we can also put this into an abstract perspective and say that the transormations being applied are to space itself. This is known as a "change of the frame of reference." The structure of space, as well as the physical laws that express that structure and operate within it, are symmetric under these transformations. Therefore, the laws of physics are the same at all times, and in all locations. When thinking about Earth, we say that the planet is rotating around the sun. But, we can also say that it is the sun that is rotating around the Earth. It all depends on the frame of reference in which we choose. The planets' movement relative to the sun however is much simpler than the planets movement relative to the Earth. The Earth-centered theory is possible but it is extremely complicated.