Friday, April 13, 2018
This might seem like a technical and obscure point, but in fact symmetry-breaking is as fundamental to the Universe, and to our view of it, as symmetry itself. Water is a uniform soup of molecules, where any particular point is on average the same as any other; but when it freezes into ice, it solidifies into a fixed pattern, in which different places are distinguishable. The difference is the same as between a painted wall and one covered in wallpaper. On the painted surface, every point is identical, but on the papered one, each point is the same as only a few others: the corresponding points in adjacent copies of the pattern. We therefore say that some of a particular kind of symmetry has been lost, something known as translational symmetry – where, for a given movement from one point to another, the object is the same.