Commons

This sunspot is a product of the sun’s magnetic fields. The darkest regionin the center is about the size of our planet.Chapter 6Fields6.1 Farewell To the Mechanical UniverseAs late as 1900, physicists generally conceived of the universe inmechanical terms. Newton had revealed the solar system as a collectionof material objects interacting through forces that acted ata distance. By 1900, evidence began to accumulate for the existenceof atoms as real things, and not just as imaginary modelsof reality. In this microscopic realm, the same (successful) Newtonianpicture tended to be transferred over to the microscopic world.Now the actors on the stage were atoms rather than planets, andthe forces were electrical rather than gravitational, but it seemed tobe a variation on the same theme. Some physicists, however, beganto realize that the old mechanical picture wouldn’t quite work. Ata deeper level, the operation of the universe came to be understoodin terms of fields, the general idea being embodied fairly well in“The Force” from the Star Wars movies: “... an energy field createdby all living things. It surrounds us, penetrates us, and bindsthe galaxy together.” Substitute “massive” for “living,” and youhave a fairly good description of the gravitational field, which I firstcasually mentioned on page 20. Substitute “charged” instead, and113