Why Is Physics Beautiful?
CAMBRIDGE – The nineteenth-century physicist Heinrich Hertz once described his feeling that James Clerk Maxwell’s equations, which depict the fundamentals of electricity and magnetism, “have an independent existence and an intelligence of their own, that they are wiser…even than their discoverers, that we get more out of them than was originally put into them.” Not long after, Albert Einstein called Niels Bohr’s atomic model “the highest form of musicality in the sphere of thought.” More recently, the late Nobel laureate Richard Feynman, describing his discovery of new laws of physics, declared, “You can recognize truth by its beauty and simplicity.” Similar sentiments are all but universal among modern physicists.
Wishful thinking could never produce working iPhones, photographs of Pluto, or atomic bombs. Physics, as summarized in a handful of mathematically precise laws, indisputably works. Yet many things that “work” do not inspire the kind of admiration that the fundamental laws of nature do.
Their beauty is rooted, first, in the laws’ symmetry, here meaning the possibility of change without change – a precise yet almost mystical concept. Just as a circle can be rotated about its center at any angle, changing the position of each of its points without changing its form, symmetric laws apply to changed situations without changing or losing validity. For example, special relativity asserts that the fundamental laws of physics remain the same when we view the world from a platform moving at constant velocity. Similarly, so-called time translation symmetry encodes the uniformity of physical law in time: Even as the universe ages, the laws remain the same.