Geon

Part of speech: noun

Definitions

1. A hypothetical entity proposed in physics as a body of trapped gravitational or electromagnetic energy held together by its own field
2. A theoretical object imagined as a bundle of field energy bound together by gravity and electromagnetism rather than by matter
3. A speculative structure in general relativity, conceived as a mass built entirely from the energy of its own gravitational field

Etymology: Physicist John Archibald Wheeler needed a name for a hypothetical structure: a knot of electromagnetic energy held together by its own gravity, with no matter at its core. He built the name from the phrase "gravitational electromagnetic entity," and the result was a short word for an idea that would otherwise have needed a long description. The ending may also echo "geometric," reflecting Wheeler's broader aim of explaining matter through the shape of spacetime. Both explanations fit his program, which treated mass and charge as features of geometry. The concept stayed theoretical, and no such object has been confirmed in experiments.