Field
A field assigns a value to every point in space and time. A temperature map of a room is a simple field: each point has a number. The electric and magnetic fields assign a direction and strength instead, and they tell a charged particle how to move when it arrives at that point. Faraday introduced fields to avoid the idea that objects act on each other instantly across empty space, and Maxwell showed that fields carry energy and travel as waves in their own right, which made them physical rather than a bookkeeping device.
Why it matters
The field replaced action at a distance as the basic picture of how anything influences anything else, and every modern theory of matter is a field theory.
Also written: fields, electromagnetic field
Where it comes up
Sources
- Field (physics) English Wikipedia
- Electromagnetism Britannica
- Quantum Field Theory Stanford Encyclopedia of PhilosophyExplains what happens to the field concept once quantum mechanics is applied to it.
